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Sample records for directional scattering properties

  1. Measurement of Rank and Other Properties of Direct and Scattered Signals

    Svante Björklund

    2016-01-01

    Full Text Available We have designed an experiment for low-cost indoor measurements of rank and other properties of direct and scattered signals with radar interference suppression in mind. The signal rank is important also in many other applications, for example, DOA (Direction of Arrival estimation, estimation of the number of and location of transmitters in electronic warfare, and increasing the capacity in wireless communications. In real radar applications, such measurements can be very expensive, for example, involving airborne radars with array antennas. We have performed the measurements in an anechoic chamber with several transmitters, a receiving array antenna, and a moving reflector. Our experiment takes several aspects into account: transmitted signals with different correlation, decorrelation of the signals during the acquisition interval, covariance matrix estimation, noise eigenvalue spread, calibration, near-field compensation, scattering in a rough surface, and good control of the influencing factors. With our measurements we have observed rank, DOA spectrum, and eigenpatterns of direct and scattered signals. The agreement of our measured properties with theoretic and simulated results in the literature shows that our experiment is realistic and sound. The detailed description of our experiment could serve as help for conducting other well-controlled experiments.

  2. Direct and inverse scattering for viscoelastic media

    Ammicht, E.; Corones, J.P.; Krueger, R.J.

    1987-01-01

    A time domain approach to direct and inverse scattering problems for one-dimensional viscoelastic media is presented. Such media can be characterized as having a constitutive relation between stress and strain which involves the past history of the strain through a memory function, the relaxation modulus. In the approach in this article, the relaxation modulus of a material is shown to be related to the reflection properties of the material. This relation provides a constructive algorithm for direct and inverse scattering problems. A numerical implementation of this algorithm is tested on several problems involving realistic relaxation moduli

  3. Interactive directional subsurface scattering and transport of emergent light

    Dal Corso, Alessandro; Frisvad, Jeppe Revall; Mosegaard, Jesper

    2016-01-01

    need to store elements of irradiance from specific directions. To include changes in subsurface scattering due to changes in the direction of the incident light, we instead sample incident radiance and store scattered radiosity. This enables us to accommodate not only the common distance....... To build our maps of scattered radiosity, we progressively render the model from different directions using an importance sampling pattern based on the optical properties of the material. We obtain interactive frame rates, our subsurface scattering results are close to ground truth, and our technique...

  4. Multiple scattering processes: inverse and direct

    Kagiwada, H.H.; Kalaba, R.; Ueno, S.

    1975-01-01

    The purpose of the work is to formulate inverse problems in radiative transfer, to introduce the functions b and h as parameters of internal intensity in homogeneous slabs, and to derive initial value problems to replace the more traditional boundary value problems and integral equations of multiple scattering with high computational efficiency. The discussion covers multiple scattering processes in a one-dimensional medium; isotropic scattering in homogeneous slabs illuminated by parallel rays of radiation; the theory of functions b and h in homogeneous slabs illuminated by isotropic sources of radiation either at the top or at the bottom; inverse and direct problems of multiple scattering in slabs including internal sources; multiple scattering in inhomogeneous media, with particular reference to inverse problems for estimation of layers and total thickness of inhomogeneous slabs and to multiple scattering problems with Lambert's law and specular reflectors underlying slabs; and anisotropic scattering with reduction of the number of relevant arguments through axially symmetric fields and expansion in Legendre functions. Gaussian quadrature data for a seven point formula, a FORTRAN program for computing the functions b and h, and tables of these functions supplement the text

  5. A direct sampling method for inverse electromagnetic medium scattering

    Ito, Kazufumi; Jin, Bangti; Zou, Jun

    2013-01-01

    In this paper, we study the inverse electromagnetic medium scattering problem of estimating the support and shape of medium scatterers from scattered electric/magnetic near-field data. We shall develop a novel direct sampling method based

  6. Directional Dipole Model for Subsurface Scattering

    Frisvad, Jeppe Revall; Hachisuka, Toshiya; Kjeldsen, Thomas Kim

    2014-01-01

    Rendering translucent materials using Monte Carlo ray tracing is computationally expensive due to a large number of subsurface scattering events. Faster approaches are based on analytical models derived from diffusion theory. While such analytical models are efficient, they miss out on some...... point source diffusion. A ray source corresponds better to the light that refracts through the surface of a translucent material. Using this ray source, we are able to take the direction of the incident light ray and the direction toward the point of emergence into account. We use a dipole construction...

  7. Directional Scattering of Semiconductor Nanoparticles Embedded in a Liquid Crystal

    Braulio García-Cámara

    2014-04-01

    Full Text Available Light scattering by semiconductor nanoparticles has been shown to be more complex than was believed until now. Both electric and magnetic responses emerge in the visible range. In addition, directional effects on light scattering of these nanoparticles were recently obtained. In particular, zero backward and minimum-forward scattering are observed. These phenomena are very interesting for several applications such as, for instance, optical switches or modulators. The strong dependence of these phenomena on the properties of both the particle and the surrounding medium can be used to tune them. The electrical control on the optical properties of liquid crystals could be used to control the directional effects of embedded semiconductor nanoparticles. In this work, we theoretically analyze the effects on the directional distribution of light scattering by these particles when the refractive index of a surrounded liquid crystal changes from the ordinary to the extraordinary configuration. Several semiconductor materials and liquid crystals are studied in order to optimize the contrast between the two states.

  8. A direct sampling method to an inverse medium scattering problem

    Ito, Kazufumi; Jin, Bangti; Zou, Jun

    2012-01-01

    In this work we present a novel sampling method for time harmonic inverse medium scattering problems. It provides a simple tool to directly estimate the shape of the unknown scatterers (inhomogeneous media), and it is applicable even when

  9. Studies of the dynamic properties of materials using neutron scattering

    Lovesey, S.W.; Windsor, C.G.

    1985-09-01

    The dynamic properties of materials using the neutron scattering technique is reviewed. The basic properties of both nuclear scattering and magnetic scattering are summarized. The experimental methods used in neutron scattering are described, along with access to neutron sources, and neutron inelastic instruments. Applied materials science using inelastic neutron scattering; rotational tunnelling of a methyl group; molecular diffusion from quasi-elastic scattering; and the diffusion of colloidal particles and poly-nuclear complexes; are also briefly discussed. (U.K.)

  10. A direct sampling method for inverse electromagnetic medium scattering

    Ito, Kazufumi

    2013-09-01

    In this paper, we study the inverse electromagnetic medium scattering problem of estimating the support and shape of medium scatterers from scattered electric/magnetic near-field data. We shall develop a novel direct sampling method based on an analysis of electromagnetic scattering and the behavior of the fundamental solution. It is applicable to a few incident fields and needs only to compute inner products of the measured scattered field with the fundamental solutions located at sampling points. Hence, it is strictly direct, computationally very efficient and highly robust to the presence of data noise. Two- and three-dimensional numerical experiments indicate that it can provide reliable support estimates for multiple scatterers in the case of both exact and highly noisy data. © 2013 IOP Publishing Ltd.

  11. Direct and inverse problems of studying the properties of multilayer nanostructures based on a two-dimensional model of X-ray reflection and scattering

    Khachaturov, R. V.

    2014-06-01

    A mathematical model of X-ray reflection and scattering by multilayered nanostructures in the quasi-optical approximation is proposed. X-ray propagation and the electric field distribution inside the multilayered structure are considered with allowance for refraction, which is taken into account via the second derivative with respect to the depth of the structure. This model is used to demonstrate the possibility of solving inverse problems in order to determine the characteristics of irregularities not only over the depth (as in the one-dimensional problem) but also over the length of the structure. An approximate combinatorial method for system decomposition and composition is proposed for solving the inverse problems.

  12. Diffuse scattering and the fundamental properties of materials

    EIce, Gene; Barabash, Rozaliya

    2009-01-01

    Diffuse Scattering-the use of off-specular X-Rays and neutrons from surfaces and interfaces-has grown rapidly as a tool for characterizing the surface properties of materials and related fundamental structural properties. It has proven to be especially useful in the understanding of local properties within materials. This book reflects the efforts of physicists and materials scientists around the world who have helped to refine the techniques and applications of diffuse scattering. Major topics specifically covered include: -- Scattering in Low Dimensions -- Elastic and Thermal Diffuse Scattering from Alloys -- Scattering from Complex and Disordered Materials -- Scattering from Distorted Crystals.

  13. Transfer by anisotropic scattering between subsets of the unit sphere of directions in linear transport theory

    Trombetti, T.

    1990-01-01

    The exact kernel method is presented for linear transport problems with azimuth-dependent angular fluxes. It is based on the evaluation of average scattering densities (ASD's) that fully describe the neutron (or particle) transfer between subsets of the unit sphere of directions by anisotropic scattering. Reciprocity and other ASD functional properties are proved and combined with the symmetry properties of suitable SN quadrature sets. This greatly reduces the number of independent ASD's to be computed and stored. An approach for performing ASD computations with reciprocity checks is presented. ASD expressions of the scattering source for typical 2D geometries are explicitly given. (author)

  14. A direct sampling method to an inverse medium scattering problem

    Ito, Kazufumi

    2012-01-10

    In this work we present a novel sampling method for time harmonic inverse medium scattering problems. It provides a simple tool to directly estimate the shape of the unknown scatterers (inhomogeneous media), and it is applicable even when the measured data are only available for one or two incident directions. A mathematical derivation is provided for its validation. Two- and three-dimensional numerical simulations are presented, which show that the method is accurate even with a few sets of scattered field data, computationally efficient, and very robust with respect to noises in the data. © 2012 IOP Publishing Ltd.

  15. Dynamic properties of electrons in solids by neutron scattering

    Lovesey, S.W.

    1980-12-01

    Illustrative cases of the use of neutron scattering in the study of the electronic properties of materials discussed here include scattering by localised electrons, narrow band materials and electron plasmas. (U.K.)

  16. Tracking Objects with Networked Scattered Directional Sensors

    Plarre, Kurt; Kumar, P. R.

    2007-12-01

    We study the problem of object tracking using highly directional sensors—sensors whose field of vision is a line or a line segment. A network of such sensors monitors a certain region of the plane. Sporadically, objects moving in straight lines and at a constant speed cross the region. A sensor detects an object when it crosses its line of sight, and records the time of the detection. No distance or angle measurements are available. The task of the sensors is to estimate the directions and speeds of the objects, and the sensor lines, which are unknown a priori. This estimation problem involves the minimization of a highly nonconvex cost function. To overcome this difficulty, we introduce an algorithm, which we call "adaptive basis algorithm." This algorithm is divided into three phases: in the first phase, the algorithm is initialized using data from six sensors and four objects; in the second phase, the estimates are updated as data from more sensors and objects are incorporated. The third phase is an optional coordinated transformation. The estimation is done in an "ad-hoc" coordinate system, which we call "adaptive coordinate system." When more information is available, for example, the location of six sensors, the estimates can be transformed to the "real-world" coordinate system. This constitutes the third phase.

  17. Direct nn-scattering at the YAGUAR reactor

    Crawford, B.E. [Gettysburg College, Department of Physics, Gettysburg, PA 17325 (United States)]. E-mail: bcrawfor@gettysburg.edu; Furman, W.I. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Howell, C.R. [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Lychagin, E.V. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Levakov, B.G. [Russian Federal Nuclear Center-All Russian Research Institute of Technical Physics, P.O. Box 245, Snezhinsk 456770 (Russian Federation); Litvin, V.I. [Russian Federal Nuclear Center-All Russian Research Institute of Technical Physics, P.O. Box 245, Snezhinsk 456770 (Russian Federation); Lyzhin, A.E. [Russian Federal Nuclear Center-All Russian Research Institute of Technical Physics, P.O. Box 245, Snezhinsk 456770 (Russian Federation); Magda, E.P. [Russian Federal Nuclear Center-All Russian Research Institute of Technical Physics, P.O. Box 245, Snezhinsk 456770 (Russian Federation); Mitchell, G.E. [North Carolina State University, Raleigh, NC 27695-8202 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Muzichka, A.Yu. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Nekhaev, G.V. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Sharapov, E.I. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Shvetsov, V.N. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Stephenson, S.L. [Gettysburg College, Department of Physics, Gettysburg, PA 17325 (United States); Strelkov, A.V. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Tornow, W. [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    2005-12-15

    The Direct Investigation of a {sub nn} Association (DIANNA) is finalizing the design of a direct measurement of the nn-scattering length to be performed at the YAGUAR reactor in Snezhinsk, Russia. Extensive modeling of the neutron field, nn-scattering kinematics, and sources of detector background have verified the plan for a 3% measurement of a {sub nn}. Measurements of the neutron flux support the neutron field modeling. Initial test measurements of the neutron field inside the underground channel have confirmed calculations of the thermal neutron background.

  18. Optically resonant magneto-electric cubic nanoantennas for ultra-directional light scattering

    Sikdar, Debabrata, E-mail: debabrata.sikdar@monash.edu; Premaratne, Malin [Advanced Computing and Simulation Laboratory (A chi L), Department of Electrical and Computer Systems Engineering, Monash University, Clayton 3800, Victoria (Australia); Cheng, Wenlong [Department of Chemical Engineering, Faculty of Engineering, Monash University, Clayton 3800, Victoria (Australia); The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton 3168, Victoria (Australia)

    2015-02-28

    Cubic dielectric nanoparticles are promising candidates for futuristic low-loss, ultra-compact, nanophotonic applications owing to their larger optical coefficients, greater packing density, and relative ease of fabrication as compared to spherical nanoparticles; besides possessing negligible heating at nanoscale in contrast to their metallic counterparts. Here, we present the first theoretical demonstration of azimuthally symmetric, ultra-directional Kerker's-type scattering of simple dielectric nanocubes in visible and near-infrared regions via simultaneous excitation and interference of optically induced electric- and magnetic-resonances up to quadrupolar modes. Unidirectional forward-scattering by individual nanocubes is observed at the first generalized-Kerker's condition for backward-scattering suppression, having equal electric- and magnetic-dipolar responses. Both directionality and magnitude of these unidirectional-scattering patterns get enhanced where matching electric- and magnetic-quadrupolar responses spectrally overlap. While preserving azimuthal-symmetry and backscattering suppression, a nanocube homodimer provides further directionality improvement for increasing interparticle gap, but with reduced main-lobe magnitude due to emergence of side-scattering lobes from diffraction-grating effect. We thoroughly investigate the influence of interparticle gap on scattering patterns and propose optimal range of gap for minimizing side-scattering lobes. Besides suppressing undesired side-lobes, significant enhancement in scattering magnitude and directionality is attained with increasing number of nanocubes forming a linear chain. Optimal directionality, i.e., the narrowest main-scattering lobe, is found at the wavelength of interfering quadrupolar resonances; whereas the largest main-lobe magnitude is observed at the wavelength satisfying the first Kerker's condition. These unique optical properties of dielectric nanocubes thus can

  19. Workshop report on new directions in x-ray scattering

    Brown, G.; Del Grande, N.K.; Fuoss, P.; Mallett, J.H.; Pratt, R.; Templeton, D.

    1987-01-01

    This report is a summary of the Workshop on New Directions in X-Ray Scattering held at the Asilomar Conference Center, Pacific Grove, California, April 2-5, 1985. The report primarily consists of the edited transcript of the final review session of the workshop, in which members of a panel summarized the proceedings. It is clear that we are close to achieving an accurate theory of scattering in independent particle approximation, but for edge regions, there is need to go beyond this approach. Much of what is experimentally interesting in scattering is occurring between the photoabsorption edge and the photoelectric threshold. Applications in condensed matter and biological and chemical material studies are expanding, exploiting higher intensity sources and faster time resolution as in magnetic scattering and surface studies. Storage rings are now conventional sources, and new high-intensity beam lines are under development; the free electron laser is one of the more speculative sources. Recent work in x-ray scattering has led to advances in x-ray optics, and conversely, advances in x-ray optics have benefitted our understanding of x-ray scattering

  20. Direct sampling methods for inverse elastic scattering problems

    Ji, Xia; Liu, Xiaodong; Xi, Yingxia

    2018-03-01

    We consider the inverse elastic scattering of incident plane compressional and shear waves from the knowledge of the far field patterns. Specifically, three direct sampling methods for location and shape reconstruction are proposed using the different component of the far field patterns. Only inner products are involved in the computation, thus the novel sampling methods are very simple and fast to be implemented. With the help of the factorization of the far field operator, we give a lower bound of the proposed indicator functionals for sampling points inside the scatterers. While for the sampling points outside the scatterers, we show that the indicator functionals decay like the Bessel functions as the sampling point goes away from the boundary of the scatterers. We also show that the proposed indicator functionals continuously dependent on the far field patterns, which further implies that the novel sampling methods are extremely stable with respect to data error. For the case when the observation directions are restricted into the limited aperture, we firstly introduce some data retrieval techniques to obtain those data that can not be measured directly and then use the proposed direct sampling methods for location and shape reconstructions. Finally, some numerical simulations in two dimensions are conducted with noisy data, and the results further verify the effectiveness and robustness of the proposed sampling methods, even for multiple multiscale cases and limited-aperture problems.

  1. Multi-frequency direct sampling method in inverse scattering problem

    Kang, Sangwoo; Lambert, Marc; Park, Won-Kwang

    2017-10-01

    We consider the direct sampling method (DSM) for the two-dimensional inverse scattering problem. Although DSM is fast, stable, and effective, some phenomena remain unexplained by the existing results. We show that the imaging function of the direct sampling method can be expressed by a Bessel function of order zero. We also clarify the previously unexplained imaging phenomena and suggest multi-frequency DSM to overcome traditional DSM. Our method is evaluated in simulation studies using both single and multiple frequencies.

  2. Theory of direct scattering of neutral and charged atoms

    Franco, V.

    1979-01-01

    The theory for direct elastic and inelastic collisions between composite atomic systems formulated within the framework of the Glauber approximation is presented. It is shown that the phase-shift function is the sum of a point Coulomb contribution and of an expression in terms of the known electron-hydrogen-atom and proton-hydrogen-atom phase shift function. The scattering amplitude is reexpressed, the pure Coulomb scattering in the case of elastic collisions between ions is isolated, and the exact optical profile function is approximated by a first-order expansion in Glauber theory which takes into account some multiple collisions. The approximate optical profile function terms corresponding to interactions involving one and two electrons are obtained in forms of Meijer G functions and as a one-dimensional integral, and for collisions involving one or two neutral atoms, the scattering amplitude is further reduced to a simple closed-form expression.

  3. Application of Geometric Polarization to Invariance Properties in Bistatic Scattering

    D. H. O. Bebbington

    2005-01-01

    Full Text Available Bistatic polarimetric radars provide target properties which just one monostatic system can not reveal. Moreover, augmentation of monostatic systems through the provision of bistatic receive-only stations can be a cheap way to increase the amount of remote sensing data. However, bistatic scattering needs to be investigated in order to properly define target properties such as symmetries and invariance, especially regarding choices of polarization basis. In this paper we discuss how the geometric theory of polarization, in which the geometry of the Poincaré sphere is directly related to 3-D geometry of space rather than the 2-D geometry of the wavefront plane, can be used to reduce the ambiguities in the interpretation of data. We also show how in the coherent case a complex scalar invariant can be determined irrespective of the basis combinations.

  4. Direct computation of scattering matrices for general quantum graphs

    Caudrelier, V.; Ragoucy, E.

    2010-01-01

    We present a direct and simple method for the computation of the total scattering matrix of an arbitrary finite noncompact connected quantum graph given its metric structure and local scattering data at each vertex. The method is inspired by the formalism of Reflection-Transmission algebras and quantum field theory on graphs though the results hold independently of this formalism. It yields a simple and direct algebraic derivation of the formula for the total scattering and has a number of advantages compared to existing recursive methods. The case of loops (or tadpoles) is easily incorporated in our method. This provides an extension of recent similar results obtained in a completely different way in the context of abstract graph theory. It also allows us to discuss briefly the inverse scattering problem in the presence of loops using an explicit example to show that the solution is not unique in general. On top of being conceptually very easy, the computational advantage of the method is illustrated on two examples of 'three-dimensional' graphs (tetrahedron and cube) for which other methods are rather heavy or even impractical.

  5. A 'range test' for determining scatterers with unknown physical properties

    Potthast, Roland; Sylvester, John; Kusiak, Steven

    2003-06-01

    We describe a new scheme for determining the convex scattering support of an unknown scatterer when the physical properties of the scatterers are not known. The convex scattering support is a subset of the scatterer and provides information about its location and estimates for its shape. For convex polygonal scatterers the scattering support coincides with the scatterer and we obtain full shape reconstructions. The method will be formulated for the reconstruction of the scatterers from the far field pattern for one or a few incident waves. The method is non-iterative in nature and belongs to the type of recently derived generalized sampling schemes such as the 'no response test' of Luke-Potthast. The range test operates by testing whether it is possible to analytically continue a far field to the exterior of any test domain Omegatest. By intersecting the convex hulls of various test domains we can produce a minimal convex set, the convex scattering support of which must be contained in the convex hull of the support of any scatterer which produces that far field. The convex scattering support is calculated by testing the range of special integral operators for a sampling set of test domains. The numerical results can be used as an approximation for the support of the unknown scatterer. We prove convergence and regularity of the scheme and show numerical examples for sound-soft, sound-hard and medium scatterers. We can apply the range test to non-convex scatterers as well. We can conclude that an Omegatest which passes the range test has a non-empty intersection with the infinity-support (the complement of the unbounded component of the complement of the support) of the true scatterer, but cannot find a minimal set which must be contained therein.

  6. Statistical properties of laser light scattering in Brownian medium

    Suwono; Santoso, Budi; Baiquni, A.

    1983-01-01

    Relationship between statistical properties of laser light scattering in Brownian medium and photon-counting distributions are described in detail. A coherence optical detection has been constructed and by using photon-counting technique the ensemble distribution of the scattered field within space and time coherence has been measured. Good agreement between theory and experiment is shown. (author)

  7. Direct time-domain techniques for transient radiation and scattering

    Miller, E.K.; Landt, J.A.

    1976-01-01

    A tutorial introduction to transient electromagnetics, focusing on direct time-domain techniques, is presented. Physical, mathematical, numerical, and experimental aspects of time-domain methods, with emphasis on wire objects excited as antennas or scatters are examined. Numerous computed examples illustrate the characteristics of direct time-domain procedures, especially where they may offer advantages over procedures in the more familiar frequency domain. These advantages include greater solution efficiency for many types of problems, the ability to handle nonlinearities, improved physical insight and interpretability, availability of wide-band information from a single calculation, and the possibility of isolating interactions among various parts of an object using time-range gating

  8. Shape dependent resonance light scattering properties of gold nanorods

    Zhu Jian; Huang Liqing; Zhao Junwu; Wang Yongchang; Zhao Yanrui; Hao Limei; Lu Yimin

    2005-01-01

    Suspended gold nanorods with mean aspect ratio 2.5 have been synthesized via electrochemical method. Resonance scattering properties have been studied. Two scattering peaks fixed at 400 and 640 nm are due to the scattering of the gold nanorods via coupling to the transverse and longitudinal surface plasmon resonance. The quasi-static calculation results indicate that with the increasing aspect ratio of the nanorods, the longer wavelength scattering peak red shifts linearly and the shorter wavelength peak blue shifts non-linearly. When aspect ratio a/b = 1.0, ellipse degenerate to sphere and the two peaks unite into one peak at 450 nm

  9. Design Study for Direction Variable Compton Scattering Gamma Ray

    Kii, T.; Omer, M.; Negm, H.; Choi, Y. W.; Kinjo, R.; Yoshida, K.; Konstantin, T.; Kimura, N.; Ishida, K.; Imon, H.; Shibata, M.; Shimahashi, K.; Komai, T.; Okumura, K.; Zen, H.; Masuda, K.; Hori, T.; Ohgaki, H.

    2013-03-01

    A monochromatic gamma ray beam is attractive for isotope-specific material/medical imaging or non-destructive inspection. A laser Compton scattering (LCS) gamma ray source which is based on the backward Compton scattering of laser light on high-energy electrons can generate energy variable quasi-monochromatic gamma ray. Due to the principle of the LCS gamma ray, the direction of the gamma beam is limited to the direction of the high-energy electrons. Then the target object is placed on the beam axis, and is usually moved if spatial scanning is required. In this work, we proposed an electron beam transport system consisting of four bending magnets which can stick the collision point and control the electron beam direction, and a laser system consisting of a spheroidal mirror and a parabolic mirror which can also stick the collision point. Then the collision point can be placed on one focus of the spheroid. Thus gamma ray direction and collision angle between the electron beam and the laser beam can be easily controlled. As the results, travelling direction of the LCS gamma ray can be controlled under the limitation of the beam transport system, energy of the gamma ray can be controlled by controlling incident angle of the colliding beams, and energy spread can be controlled by changing the divergence of the laser beam.

  10. Scattering properties of a PT dipole

    Staliunas, K.; Markoš, P.; Kuzmiak, Vladimír

    2017-01-01

    Roč. 96, č. 4 (2017), č. článku 043852. ISSN 2469-9926 R&D Projects: GA ČR(CZ) GA16-00329S Institutional support: RVO:67985882 Keywords : Scattering field * Electromagnetic response * Refractive index Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Electrical and electronic engineering Impact factor: 2.925, year: 2016

  11. Dust grain characterization — Direct measurement of light scattering

    BartoÅ, P.; Pavlů, J.

    2018-01-01

    Dust grains play a key role in dusty plasma since they interact with the plasma we can use them to study plasma itself. The grains are illuminated by visible light (e.g., a laser sheet) and the situation is captured with camera. Despite of simplicity, light scattering on similar-to-wavelength sized grains is complex phenomenon. Interaction of the electromagnetic wave with material has to be computed with respect to Maxwell equations — analytic solution is nowadays available only for several selected shapes like sphere, coated sphere, or infinite cylinder. Moreover, material constants needed for computations are usually unknown. For computation result verification and material constant determination, we designed and developed a device directly measur­ing light scattering profiles. Single dust grains are trapped in the ultrasonic field (so called "acoustic levitation") and illuminated by the laser beam. Scattered light is then measured by a photodiode mounted on rotating platform. Synchronous detection is employed for a noise reduction. This setup brings several benefits against conventional methods: (1) it works in the free air, (2) the measured grain is captured for a long time, and (3) the grain could be of arbitrary shape.

  12. Direct nn-Scattering Measurement With the Pulsed Reactor YAGUAR.

    Mitchell, G E; Furman, W I; Lychagin, E V; Muzichka, A Yu; Nekhaev, G V; Strelkov, A V; Sharapov, E I; Shvetsov, V N; Chernuhin, Yu I; Levakov, B G; Litvin, V I; Lyzhin, A E; Magda, E P; Crawford, B E; Stephenson, S L; Howell, C R; Tornow, W

    2005-01-01

    Although crucial for resolving the issue of charge symmetry in the nuclear force, direct measurement of nn-scattering by colliding free neutrons has never been performed. At present the Russian pulsed reactor YAGUAR is the best neutron source for performing such a measurement. It has a through channel where the neutron moderator is installed. The neutrons are counted by a neutron detector located 12 m from the reactor. In preliminary experiments an instantaneous value of 1.1 × 10(18)/cm(2)s was obtained for the thermal neutron flux density. The experiment will be performed by the DIANNA Collaboration as International Science & Technology Center (ISTC) project No. 2286.

  13. Scattering and Absorption Properties of Biomaterials for Dental Restorative Applications

    Fernandez-Oliveras, A.; Rubiño, M.; Pérez, M. M.

    2013-08-01

    The physical understanding of the optical properties of dental biomaterials is mandatory for their final success in restorative applications.Light propagation in biological media is characterized by the absorption coefficient, the scattering coefficient, the scattering phase function,the refractive index, and the surface conditions (roughness). We have employed the inverse adding-doubling (IAD) method to combine transmittance and reflectance measurements performed using an integrating-sphere setup with the results of the previous scattering-anisotropygoniometric measurements. This has led to the determination of the absorption and the scattering coefficients. The aim was to optically characterize two different dental-resin composites (nanocomposite and hybrid) and one type of zirconia ceramic, and comparatively study them. The experimental procedure was conducted under repeatability conditions of measurement in order to determine the uncertainty associated to the optical properties of the biomaterials. Spectral variations of the refraction index and the scattering anisotropy factor were also considered. The whole experimental procedure fulfilled all the necessary requirements to provide optical-property values with lower associated uncertainties. The effective transport coefficient presented a similar spectral behavior for the two composites but completely different for the zirconia ceramic. The results demonstrated that the scattering anisotropy exerted a clearly distinct impact on the optical properties of the zirconia ceramic compared with those of the dental-resin composites.

  14. Controlling the scattering properties of thin, particle-doped coatings

    Rogers, William; Corbett, Madeleine; Manoharan, Vinothan

    2013-03-01

    Coatings and thin films of small particles suspended in a matrix possess optical properties that are important in several industries from cosmetics and paints to polymer composites. Many of the most interesting applications require coatings that produce several bulk effects simultaneously, but it is often difficult to rationally formulate materials with these desired optical properties. Here, we focus on the specific challenge of designing a thin colloidal film that maximizes both diffuse and total hemispherical transmission. We demonstrate that these bulk optical properties follow a simple scaling with two microscopic length scales: the scattering and transport mean free paths. Using these length scales and Mie scattering calculations, we generate basic design rules that relate scattering at the single particle level to the film's bulk optical properties. These ideas will be useful in the rational design of future optically active coatings.

  15. Dark matter effective field theory scattering in direct detection experiments

    Schneck, K.; Cabrera, B.; Cerdeño, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.

    2015-05-18

    We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  16. Direct Detection of Polarized, Scattered Light from Exoplanets

    Laughlin, Gregory

    We propose to radically advance the state of exoplanet characterization, which lags dramatically behind exoplanet discovery. We propose to directly detect scattered light from the atmospheres of close-in, highly eccentric, and extended/non-spherical exoplanets and thereby determine the following: orbital inclination (and therefore masses free of the M sin i mass ambiguity), geometric albedo, presence or lack of hazes and cloud layers, and scattering particle size and composition. Such measurements are crucial to the understanding of exoplanet atmospheres, because observations with NASA s Hubble, Spitzer, and Kepler space telescopes present the following questions: 1) Do exoplanets have highly reflective haze layers? 2) How does the upper atmospheric composition differ between exoplanets with and without thermal inversions? 3) What are the optical manifestations of the extreme heating of highly eccentric exoplanets? 4) Are the atmospheres of certain exoplanets truly escaping their Roche lobes? Using the POLISH2 polarimeter developed by the Postdoctoral Associate (Wiktorowicz) for the Lick 3-m telescope, we propose to monitor the linear polarization state of exoplanet host stars at the part per million level. POLISH2 consistently delivers nearly photon shot noise limited measurements with this precision. In addition, the simultaneous full-Stokes measurements of POLISH2 and the equatorial mount of the Lick 3-m telescope ensure that systematic effects are mitigated to the part per million level. Indeed, we find the accuracy of the POLISH2 polarimeter to be 0.1 parts per million. This instrument and telescope represent the highest precision polarimeter in the world for exoplanet research. We present potential detection of polarized, scattered light from the HD 189733b, Tau Boo b, and WASP-12b exoplanets. We propose to observe hot Jupiters on circular orbits, highly eccentric exoplanets, exoplanets with extended or non-spherical scattering surfaces, and 55 Cnc e, the

  17. Low-Field Mobility and Galvanomagnetic Properties of Holes in Germanium with Phonon Scattering

    Lawætz, Peter

    1968-01-01

    acoustic scattering, no overall consistency is found between available galvanomagnetic data and deformation potentials derived directly from experiments on strained Ge. The discrepancies may be ascribed to ionized-impurity scattering, but at higher temperatures where optical phonon scattering is operative......A theoretical calculation of the low-field galvanomagnetic properties of holes in Ge has been carried out incorporating all relevant details of the band structure. The scattering is limited to acoustic and optical phonons and is described by the deformation potentials a, b, d, and d0. For pure......, the deviations are still appreciable. We are led to conclude that the deformation-potential theory of phonon scattering needs reconsideration, and a nontrivial correction is pointed out....

  18. Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis

    Shertzer, J.; Temkin, A.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Two new developments in scattering theory are reported. We show, in a practical way, how one can calculate the full scattering amplitude without invoking a partial wave expansion. First, the integral expression for the scattering amplitude f(theta) is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wavefunction which appears in the integral expression for f(theta) is obtained by solving the Schrodinger equation with the finite element method (FEM). As an example, we calculate electron scattering from the Hartree potential. With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.

  19. Defect properties from X-ray scattering experiments

    Peisl, H.

    1976-01-01

    Lattice distortions due to defects in crystals can be studied most directly by elastic X-ray or neutron scattering experiments. The 'size' of the defects can be determined from the shift of the Bragg reflections. Defect induced diffuse scattering intensity close to and between Bragg reflections gives information on the strength and symmetry of the distortion fields and yields the atomic structure of point defects (interstitials, vacancies, small aggregates). Diffuse scattering is a very sensitive method to decide whether defects are present as isolated point defects or have formed aggregates. X-ray scattering has been used to study defects produced in various ionic crystals by γ- and neutron irradiation. After an introduction to the principles of the method the experimental results will be reviewed and discussed in some detail. (orig.) [de

  20. Estimates of oceanic surface wind speed and direction using orthogonal beam scatterometer measurements and comparison of recent sea scattering theories

    Moore, R. K.; Fung, A. K.; Dome, G. J.; Birrer, I. J.

    1978-01-01

    The wind direction properties of radar backscatter from the sea were empirically modelled using a cosine Fourier series through the 4th harmonic in wind direction (referenced to upwind). A comparison with 1975 JONSWAP (Joint North Sea Wave Project) scatterometer data, at incidence angles of 40 and 65, indicates that effects to third and fourth harmonics are negligible. Another important result is that the Fourier coefficients through the second harmonic are related to wind speed by a power law expression. A technique is also proposed to estimate the wind speed and direction over the ocean from two orthogonal scattering measurements. A comparison between two different types of sea scatter theories, one type presented by the work of Wright and the other by that of Chan and Fung, was made with recent scatterometer measurements. It demonstrates that a complete scattering model must include some provisions for the anisotropic characteristics of the sea scatter, and use a sea spectrum which depends upon wind speed.

  1. Direct numerical reconstruction of conductivities in three dimensions using scattering transforms

    Bikowski, Jutta; Knudsen, Kim; Mueller, Jennifer L

    2011-01-01

    A direct three-dimensional EIT reconstruction algorithm based on complex geometrical optics solutions and a nonlinear scattering transform is presented and implemented for spherically symmetric conductivity distributions. The scattering transform is computed both with a Born approximation and from...

  2. Relevant optical properties for direct restorative materials.

    Pecho, Oscar E; Ghinea, Razvan; do Amaral, Erika A Navarro; Cardona, Juan C; Della Bona, Alvaro; Pérez, María M

    2016-05-01

    To evaluate relevant optical properties of esthetic direct restorative materials focusing on whitened and translucent shades. Enamel (E), body (B), dentin (D), translucent (T) and whitened (Wh) shades for E (WhE) and B (WhB) from a restorative system (Filtek Supreme XTE, 3M ESPE) were evaluated. Samples (1 mm thick) were prepared. Spectral reflectance (R%) and color coordinates (L*, a*, b*, C* and h°) were measured against black and white backgrounds, using a spectroradiometer, in a viewing booth, with CIE D65 illuminant and d/0° geometry. Scattering (S) and absorption (K) coefficients and transmittance (T%) were calculated using Kubelka-Munk's equations. Translucency (TP) and opalescence (OP) parameters and whiteness index (W*) were obtained from differences of CIELAB color coordinates. R%, S, K and T% curves from all shades were compared using VAF (Variance Accounting For) coefficient with Cauchy-Schwarz inequality. Color coordinates and optical parameters were statistically analyzed using one-way ANOVA, Tukey's test with Bonferroni correction (α=0.0007). Spectral behavior of R% and S were different for T shades. In addition, T shades showed the lowest R%, S and K values, as well as the highest T%, TP an OP values. In most cases, WhB shades showed different color and optical properties (including TP and W*) than their corresponding B shades. WhE shades showed similar mean W* values and higher mean T% and TP values than E shades. When using whitened or translucent composites, the final color is influenced not only by the intraoral background but also by the color and optical properties of multilayers used in the esthetic restoration. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Statistical properties of chaotic scattering with one open channel

    Izrajlev, F.M.; Saher, D.; Sokolov, V.V.

    1993-01-01

    The correspondence between statistical properties of decaying states and fluctuations in resonance scattering is studied in a statistical model with one open channel. The model is described by an ensemble of random nonhermitian matrices. The dependence of the correlation length on the coupling parameter both for the S-matrix and the cross-section is studied numerically. 37 refs., 7 figs

  4. Properties of the scattering amplitude for electron-atom collisions

    Combes, J.M.; Tip, A.

    1983-02-01

    For the scattering of an electron by an atom finiteness of the amplitude at non threshold energies is proved in the framework of the N-body Schroedinger equation. It is also shown that both the direct and exchange amplitudes have analytic continuations for complex values of incident momentum, with pole or cut singularities on the imaginary axis

  5. Quasi-Three Body Systems: Properties and Scattering

    Amusia, M. Ya.

    2017-01-01

    We investigate systems of three mutually interacting particles with masses m e , m μ , M that obey the following inequality m e ≪ m μ ≪ M. Then the three-body problem reduces to the two-body scattering or structure of m e in the field of the pseudo-nucleus m μ M. We calculate analytically the properties of considered systems, such as the scattering cross-sections, hyperfine splitting, Auger decay of exited states and Lamb shifts, presenting them as expansions in powers of the parameter β=m e /m μ ≪1. (author)

  6. Universal properties of two-port scattering, impedance, and admittance matrices of wave-chaotic systems

    Hemmady, Sameer; Zheng, Xing; Hart, James; Antonsen, Thomas M. Jr.; Ott, Edward; Anlage, Steven M.

    2006-01-01

    Statistical fluctuations in the eigenvalues of the scattering, impedance, and admittance matrices of two-port wave-chaotic systems are studied experimentally using a chaotic microwave cavity. These fluctuations are universal in that their properties are dependent only upon the degree of loss in the cavity. We remove the direct processes introduced by the nonideally coupled driving ports through a matrix normalization process that involves the radiation-impedance matrix of the two driving ports. We find good agreement between the experimentally obtained marginal probability density functions (PDFs) of the eigenvalues of the normalized impedance, admittance, and scattering matrix and those from random matrix theory (RMT). We also experimentally study the evolution of the joint PDF of the eigenphases of the normalized scattering matrix as a function of loss. Experimental agreement with the theory by Brouwer and Beenakker for the joint PDF of the magnitude of the eigenvalues of the normalized scattering matrix is also shown

  7. Directed networks, allocation properties and hierarchy formation

    Slikker, M.; Gilles, R.P.; Norde, H.W.; Tijs, S.H.

    2005-01-01

    We investigate properties for allocation rules on directed communication networks and the formation of such networks under these payoff properties. We study allocation rules satisfying two appealing properties, Component Efficiency (CE) and the Hierarchical Payoff Property (HPP). We show that such

  8. Scattering Properties of Ground-State 23Na Vapor Using Generalized Scattering Theory

    Al-Harazneh, A. A.; Sandouqa, A. S.; Joudeh, B. R.; Ghassib, H. B.

    2018-04-01

    The scattering properties of ground-state 23Na vapor are investigated within the framework of the Galitskii-Migdal-Feynman formalism. Viewed as a generalized scattering theory, this formalism is used to calculate the medium phase shifts. The scattering properties of the system—the total, viscosity, spin-exchange, and average cross sections—are then computed using these phase shifts according to standard recipes. The total cross section is found to exhibit the Ramsauer-Townsend effect as well as resonance peaks. These peaks are caused by the large difference between the potentials for electronic spin-singlet and spin-triplet states. They represent quasi-bound states in the system. The results obtained for the complex spin-exchange cross sections are particularly highlighted because of their importance in the spectroscopy of the Na2 dimer. So are the results for the scattering lengths pertaining to both singlet and triplet states. Wherever possible, comparison is made with other published results.

  9. A review of the light scattering properties of cirrus

    Baran, Anthony J.

    2009-01-01

    In this review paper the light scattering properties of naturally occurring ice crystals that are found in cirrus are discussed. Cirrus, also referred to as ice crystal clouds, due to their cold temperatures, consist of a variety of non-spherical ice particles which may take on a variety of geometrical forms. These geometrical forms can range from symmetric pristine hexagonal ice columns and plates, single bullets and bullet-rosettes to non-symmetric aggregates of these shapes. These aggregates may also consist of highly complex three-dimensional structures, which may themselves consist of symmetric components. Not only does cirrus consist of a wide variety of shapes but also sizes too, and these sizes can range between <10 μm to over 1 cm. With such a variety of shapes and sizes predicting the light scattering properties from such an ensemble of ice crystals is the current challenge. This challenge is important to overcome since with cirrus being so high in the Earth's atmosphere it has an important influence on the Earth-atmosphere radiation balance and consequently adds to the uncertainty of predicting climate change. This is why it is important to represent as accurately as possible the single-scattering properties of cirrus ice crystals within general circulation models so that uncertainties in climate change predictions can be reduced. In this review paper the current measurements and observations of ice crystal size and shape are discussed and how these observations relate to current ice crystal models is reviewed. The light scattering properties of the current ice crystal models are also discussed and it is shown how space-based instruments may be used to test these models. The need for particular microphysical and space-based measurements is stressed in order to further constrain ice crystal light scattering models.

  10. Electronic properties of Be and Al by Compton scattering technique

    Aguiar, J.C.; Di Rocco, H.O.

    2011-01-01

    In this work, electronic properties of beryllium and aluminum are examined by using Compton scattering technique. The method is based on the irradiation of samples using a beam narrow of mono- energetic photons of 59.54 keV product of radioactive decay of Am -241 . Scattered radiation is collected by a high resolution semiconductor detector positioned at an angle of 90°. The measured spectrum is commonly called Compton profile and contains useful information about the electronic structure of the material. The experimental results are compared with theoretical calculations such as density functional theory showing a good agreement. However, these results show some discrepancies with many libraries used in codes such as Monte Carlo simulation. Since these libraries are based on the values tabulated by Biggs, Mendelsohn and Mann 1975 thus overestimating the scattered radiation on the material. (authors) [es

  11. Scattering and short-distance properties in field theory models

    Iagolnitzer, D.

    1987-01-01

    The aim of constructive field theory is not only to define models but also to establish their general properties of physical interest. We here review recent works on scattering and on short-distance properties for weakly coupled theories with mass gap such as typically P(φ) in dimension 2, φ 4 in dimension 3 and the (renormalizable, asymptotically free) massive Gross-Neveu (GN) model in dimension 2. Many of the ideas would apply similarly to other (possibly non renormalizable) theories that might be defined in a similar way via phase-space analysis

  12. Light-scattering models applied to circumstellar dust properties

    Koehler, Melanie; Mann, Ingrid

    2004-01-01

    Radiation pressure force, Poynting-Robertson effect, and collisions are important to determine the size distribution of dust in circumstellar debris disks with the two former parameters depending on the light-scattering properties of grains. We here present Mie and discrete-dipole approximation (DDA) calculations to describe the optical properties of dust particles around β Pictoris, Vega, and Fomalhaut in order to study the influence of the radiation pressure force. We find that the differences between Mie and DDA calculations are lower than 30% for all porosities. Therefore, Mie calculations can be used to determine the cut-off limits which contribute to the size distribution for the different systems

  13. First correlated measurements of the shape and light scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS probe

    A. Abdelmonem

    2011-10-01

    Full Text Available Studying the radiative impact of cirrus clouds requires knowledge of the relationship between their microphysics and the single scattering properties of cloud particles. Usually, this relationship is obtained by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS designed to measure simultaneously the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles. Clouds containing particles ranging from a few micrometers to about 800 μm diameter in size can be characterized systematically with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10° and 8° for side and backscattering directions (from 18° to 170°. The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced size distributions and images comparable to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF program. PHIPS is a highly promising novel airborne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurement instruments.

  14. First correlated measurements of the shape and scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe

    Abdelmonem, A.; Schnaiter, M.; Amsler, P.; Hesse, E.; Meyer, J.; Leisner, T.

    2011-05-01

    Studying the radiative impact of cirrus clouds requires the knowledge of the link between their microphysics and the single scattering properties of the cloud particles. Usually, this link is created by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles, simultaneously. Clouds containing particles ranging in size from a few micrometers to about 800 μm diameter can be systematically characterized with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns which were conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced comparable size distributions and images to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is candidate to be a novel air borne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurements instruments.

  15. First correlated measurements of the shape and light scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe

    Abdelmonem, A.; Schnaiter, M.; Amsler, P.; Hesse, E.; Meyer, J.; Leisner, T.

    2011-10-01

    Studying the radiative impact of cirrus clouds requires knowledge of the relationship between their microphysics and the single scattering properties of cloud particles. Usually, this relationship is obtained by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure simultaneously the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles. Clouds containing particles ranging from a few micrometers to about 800 μm diameter in size can be characterized systematically with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced size distributions and images comparable to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is a highly promising novel airborne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurement instruments.

  16. Properties of scattering forms and their relation to associahedra

    de la Cruz, Leonardo; Kniss, Alexander; Weinzierl, Stefan

    2018-03-01

    We show that the half-integrands in the CHY representation of tree amplitudes give rise to the definition of differential forms — the scattering forms — on the moduli space of a Riemann sphere with n marked points. These differential forms have some remarkable properties. We show that all singularities are on the divisor {\\overline{M}}_{0,n}\\backslash {M}_{0,n} . Each singularity is logarithmic and the residue factorises into two differential forms of lower points. In order for this to work, we provide a threefold generalisation of the CHY polarisation factor (also known as reduced Pfaffian) towards off-shell momenta, unphysical polarisations and away from the solutions of the scattering equations. We discuss explicitly the cases of bi-adjoint scalar amplitudes, Yang-Mills amplitudes and gravity amplitudes.

  17. Simultaneous reconstruction of thermal degradation properties for anisotropic scattering fibrous insulation after high temperature thermal exposures

    Zhao, Shuyuan; Zhang, Wenjiao; He, Xiaodong; Li, Jianjun; Yao, Yongtao; Lin, Xiu

    2015-01-01

    To probe thermal degradation behavior of fibrous insulation for long-term service, an inverse analysis model was developed to simultaneously reconstruct thermal degradation properties of fibers after thermal exposures from the experimental thermal response data, by using the measured infrared spectral transmittance and X-ray phase analysis data as direct inputs. To take into account the possible influence of fibers degradation after thermal exposure on the conduction heat transfer, we introduced a new parameter in the thermal conductivity model. The effect of microstructures on the thermal degradation parameters was evaluated. It was found that after high temperature thermal exposure the decay rate of the radiation intensity passing through the material was weakened, and the probability of being scattered decreased during the photons traveling in the medium. The fibrous medium scattered more radiation into the forward directions. The shortened heat transfer path due to possible mechanical degradation, along with the enhancement of mean free path of phonon scattering as devitrification after severe heat treatment, made the coupled solid/gas thermal conductivities increase with the rise of heat treatment temperature. - Highlights: • A new model is developed to probe conductive and radiative properties degradation of fibers. • To characterize mechanical degradation, a new parameter is introduced in the model. • Thermal degradation properties are reconstructed from experiments by L–M algorithm. • The effect of microstructures on the thermal degradation parameters is evaluated. • The analysis provides a powerful tool to quantify thermal degradation of fiber medium

  18. Properties of hadronic final states in diffractive deep inelastic ep scattering at DESY HERA

    2002-01-01

    Characteristics of the hadronic final state of diffractive deep inelastic scattering events ep→eXp were studied in the kinematic range 4 X 2 2 , 70 P <0.03 with the ZEUS detector at the DESY ep collider HERA using an integrated luminosity of 13.8 pb-1. The events were tagged by identifying the diffractively scattered proton using the leading proton spectrometer. The properties of the hadronic final state X were studied in its center-of-mass frame using thrust, thrust angle, sphericity, energy flow, transverse energy flow, and 'seagull' distributions. As the invariant mass of the system increases, the final state becomes more collimated, more aligned, and more asymmetric in the average transverse momentum with respect to the direction of the virtual photon. Comparisons of the properties of the hadronic final state with predictions from various Monte Carlo model generators suggest that the final state is dominated by qq-barg states at the parton level

  19. Electromagnetic Scattering from a PEC Wedge Capped with Cylindrical Layers with Dielectric and Conductive Properties

    H. Ozturk

    2017-04-01

    Full Text Available Electromagnetic scattering from a layered capped wedge is studied. The wedge is assumed infinite in z-direction (longitudinal and capped with arbitrary layers of dielectric with varying thicknesses and dielectric properties including conductive loss. Scalar Helmholtz equation in two dimensions is formulated for each solution region and a matrix of unknown coefficients are arrived at for electric field representation. Closed form expressions are derived for 2- and 3-layer geometries. Numerical simulations are performed for different wedge shapes and dielectric layer properties and compared to PEC-only case. It has been shown that significant reduction in scattered electric field can be obtained with 2- and 3-layered cap geometries. Total electric field in the far field normalized to incident field is also computed as a precursor to RCS analysis. Analytical results can be useful in radar cross section analysis for aerial vehicles.

  20. Investigation of static and dynamic properties of condensed matter by using neutron scattering

    Davidovic, M.

    1997-01-01

    Possibilities of using neutron scattering for investigating microscopic properties of materials are analyzed. Basic neutron scattering theory is presented and its use in structure and dynamics analyses of condense systems. (author)

  1. Hot electron attenuation of direct and scattered carriers across an epitaxial Schottky interface

    Parui, S.; Klandermans, P. S.; Venkatesan, S.; Scheu, C.; Banerjee, T.

    2013-01-01

    Hot electron transport of direct and scattered carriers across an epitaxial NiSi2/n-Si(111) interface, for different NiSi2 thickness, is studied using ballistic electron emission microscopy (BEEM). We find the BEEM transmission for the scattered hot electrons in NiSi2 to be significantly lower than

  2. Experiment on direct nn scattering - The radiation-induced outgassing complication

    Stephenson, S.L., E-mail: sstephen@gettysburg.edu [Gettysburg College, Gettysburg, PA 17325 (United States); Crawford, B.E. [Gettysburg College, Gettysburg, PA 17325 (United States); Furman, W.I.; Lychagin, E.V.; Muzichka, A.Yu.; Nekhaev, G.V.; Sharapov, E.I.; Shvetsov, V.N.; Strelkov, A.V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Levakov, B.G.; Lyzhin, A.E.; Chernukhin, Yu.I. [Russian Federal Nuclear Center - All Russian Research Institute of Technical Physics, P.O. Box 245, 456770 Snezhinsk (Russian Federation); Howell, C.R. [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Mitchell, G.E. [North Carolina State University, Raleigh, NC 27695-8202 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Showalter-Bucher, R.A. [Northeastern University, Boston, MA 02115 (United States)

    2012-12-01

    The first direct neutron-neutron scattering experiment using the YAGUAR pulsed reactor has yielded initial results. They show a unforeseen significant thermal neutron background as a result of radiation-induced desorption within the scattering chamber. Thermal neutrons are mostly scattering not from other neutrons but instead from the desorbed gas molecules. Analysis of the obtained neutron time-of-flight spectra suggests neutron scattering from H{sub 2} molecules. The presented desorption model agrees with our experimental value of the desorption yield {eta}{sub {gamma}}=0.02 molecules/gamma. Possible techniques to reduce the effect of the desorption background are presented.

  3. Neutron scattering instrumentation. A guide to future directions

    Crawford, R.K.

    2001-01-01

    Many of the neutron scattering instruments being designed or built now are the first generation of pulsed source instruments to provide nearly optimal scattering angle coverage with good spatial resolution in a single setting of the instrument while making full use of modern optics to maximize the useful flux on the sample. Spectacular gains have resulted from such optimization, but in most of these cases there is little room for further large improvements. However, other types of pulsed source instruments are currently less well optimized, and there is room for significant improvements in these types of pulsed source instruments. Several examples will illustrate these points. In the longer term, we can expect source strengths to continue to increase, but only slowly. However, we can expect new science and new ways of doing experiments to emerge. Many of these changes will be driven by enhancements in sample environment capabilities leading to more innovative sample conditions and to efficient parametric studies. Kinetic studies and parametric studies will take on much greater roles with the high data rates now available. Implications of these trends will be discussed. (author)

  4. Polarimetric Scattering Properties of Landslides in Forested Areas and the Dependence on the Local Incidence Angle

    Takashi Shibayama

    2015-11-01

    Full Text Available This paper addresses the local incidence angle dependence of several polarimetric indices corresponding to landslides in forested areas. Landslide is deeply related to the loss of human lives and their property. Various kinds of remote sensing techniques, including aerial photography, high-resolution optical satellite imagery, LiDAR and SAR interferometry (InSAR, have been available for landslide investigations. SAR polarimetry is potentially an effective measure to investigate landslides because fully-polarimetric SAR (PolSAR data contain more information compared to conventional single- or dual-polarization SAR data. However, research on landslide recognition utilizing polarimetric SAR (PolSAR is quite limited. Polarimetric properties of landslides have not been examined quantitatively so far. Accordingly, we examined the polarimetric scattering properties of landslides by an assessment of how the decomposed scattering power components and the polarimetric correlation coefficient change with the local incidence angle. In the assessment, PolSAR data acquired from different directions with both spaceborne and airborne SARs were utilized. It was found that the surface scattering power and the polarimetric correlation coefficient of landslides significantly decrease with the local incidence angle, while these indices of surrounding forest do not. This fact leads to establishing a method of effective detection of landslide area by polarimetric information.

  5. Static and dynamic properties of multiple light scattering

    Štěpánek, Petr

    1993-11-01

    We have examined the onset and evolution of multiple scattering of light on a series of latex dispersions as a function of increasing volume concentration φ of particles. We have shown that using vertically polarized incident light, the static scattered intensity becomes progressively depolarized, with increasing φ. The polarization of scattered light is completely random in the limit of strong multiple scattering. The spectra of decay times of dynamic light scattering display a region of oligo scattering at intermediate φ where both the single and multiple scattering components can be dynamically identified. For φ≳0.03 the limit of diffusive transport of light is attained. The obtained results confirm that our earlier measurements of dynamic light scattering on systems exhibiting critical opalescence are not influenced by multiple light scattering.

  6. Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions

    Vanier P. e.; Dioszegi, I.; Salwen, C.; Forman, L.

    2009-10-25

    We have investigated the response of a DoubleScatter Neutron Spectrometer (DSNS) for sources at long distances (gr than 200 meters). We find that an alternative method for analyzing double scatter data avoids some uncertainties introduced by amplitude measurements in plastic scintillators.Time of flight is used to discriminate between gamma and neutron events, and the kinematic distributions of scattering angles are assumed to apply. Non-relativistic neutrons are most likely to scatter at 45°, while gammas with energies greater than 2 MeV are most likely to be forward scattered. The distribution of scattering angles of fission neutrons arriving from a distant point source generates a 45° cone, which can be back-projected to give the source direction. At the same time, the distribution of Compton-scattered gammas has a maximum in the forward direction, and can be made narrower by selecting events that deposit minimal energy in the first scattering event. We have further determined that the shape of spontaneous fission neutron spectra at ranges gr than 110 m is still significantly different from thecosmic ray background.

  7. Systematic analysis of scaling properties in deep inelastic scattering

    Beuf, Guillaume; Peschanski, Robi; Royon, Christophe; Salek, David

    2008-01-01

    Using the 'quality factor' method, we analyze the scaling properties of deep inelastic processes at the accelerator HERA and fixed target experiments for x≤10 -2 . We look for scaling formulas of the form σ γ * p (τ), where τ(L=logQ 2 ,Y) is a scaling variable suggested by the asymptotic properties of QCD evolution equations with rapidity Y. We consider four cases: 'fixed coupling', corresponding to the original geometric scaling proposal and motivated by the asymptotic properties of the Balitsky-Kovchegov equation with fixed QCD coupling constant; two versions, 'running coupling I, II,' of the scaling suggested by the Balitsky-Kovchegov equation with running coupling; and 'diffusive scaling' suggested by the QCD evolution equation with Pomeron loops. The quality factors, quantifying the phenomenological validity of the candidate scaling variables, are fitted on the total and deeply virtual Compton scattering cross-section data from HERA and predictions are made for the elastic vector meson and for the diffractive cross sections at fixed small x P or β. The first three scaling formulas have comparably good quality factors while the fourth one is disfavored. Adjusting initial conditions gives a significant improvement of the running coupling II scaling.

  8. Photopolarimetric properties of leaf and vegetation covers over a wide range of measurement directions

    Sun, Zhongqiu; Peng, Zhiyan; Wu, Di; Lv, Yunfeng

    2018-02-01

    The optical scattering property of the target is the essential signal for passive remote sensing applications. To deepen our understanding of the light reflected from vegetation, we present results of photopolarimetric laboratory measurements from single leaf and two vegetation covers (planophile and erectophile) over a wide range of viewing directions. The bidirectional polarized reflectance factor (BPRF) was used to characterize the polarization property of our samples. We observed positive and negative polarization (-BPRFQ) of all samples in the forward scattering and backward scattering directions, respectively. Based on the comparison of the BPRF among single leaf, planophile vegetation and erectophile vegetation, our measurements demonstrate that the orientation of the leaf is a key factor in describing the amount of polarization in the forward scattering direction. Our measurements also validated certain model results stating that (1) specular reflection generates a portion of polarization in the forward scattering direction and diffuses scattering of polarized light in all hemisphere directions, (2) BPRFU is anti-symmetric in the principal plane from a recent study in which the authors simulated the polarized reflectance of vegetation cover using the vector radiative transfer theory. These photopolarimetric measurement results, which can be completely explained by the theoretical results, are useful in remote sensing applications to vegetation.

  9. Investigation of magneto-optical properties of ferrofluids by laser light scattering techniques

    Nepomnyashchaya, E.K., E-mail: elina.nep@gmail.com [Department of Quantum Electronics, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251 (Russian Federation); Prokofiev, A.V.; Velichko, E.N. [Department of Quantum Electronics, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251 (Russian Federation); Pleshakov, I.V.; Kuzmin, Yu I. [Department of Quantum Electronics, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251 (Russian Federation); Laboratory of Quantum Electronics, Ioffe Institute, Saint-Petersburg 194021 (Russian Federation)

    2017-06-01

    Investigation of magnetooptical characteristics of ferrofluids is an important task aimed at the development of novel optoelectronic systems. This article reports on the results obtained in the experimental studies of the factors that affect the intensity and spatial distribution of the laser radiation scattered by magnetic particles and their agglomerates in a magnetic field. Laser correlation spectroscopy and direct measurements of laser radiation scattering for studies of the interactions and magnetooptical properties of magnetic particles in solutions were employed. The objects were samples of nanodispersed magnetite (Fe{sub 3}O{sub 4}) suspended in kerosene and in water. Our studies revealed some new behavior of magnetic particles in external magnetic and light fields, which make ferrofluids promising candidates for optical devices.

  10. Signatures of Earth-scattering in the direct detection of Dark Matter

    Kavanagh, Bradley J.; Catena, Riccardo; Kouvaris, Chris

    2017-01-01

    Direct detection experiments search for the interactions of Dark Matter (DM) particles with nuclei in terrestrial detectors. But if these interactions are sufficiently strong, DM particles may scatter in the Earth, affecting their distribution in the lab. We present a new analytic calculation...... of this 'Earth-scattering' effect in the regime where DM particles scatter at most once before reaching the detector. We perform the calculation self-consistently, taking into account not only those particles which are scattered away from the detector, but also those particles which are deflected towards...... the detector. Taking into account a realistic model of the Earth and allowing for a range of DM-nucleon interactions, we present the EarthShadow code, which we make publicly available, for calculating the DM velocity distribution after Earth-scattering. Focusing on low-mass DM, we find that Earth...

  11. Microscopic description of elastic and direct inelastic nucleon scattering off spherical nuclei

    Dupuis, M. [CEA, DAM, DIF, Arpajon (France)

    2017-05-15

    The purpose of this study is to improve the modeling of nucleon direct inelastic scattering to the continuum using a microscopic and parameter-free approach. For the first time, direct elastic scattering, inelastic scattering to discrete excitations and to the continuum are described within a microscopic approach without adjustable parameters. Proton scattering off {sup 90}Zr and {sup 208}Pb are the reactions used as test case examples of the calculations. The model uses the Melbourne g-matrix and the Random Phase Approximation description of nuclear states, implemented with the Gogny D1S interaction. The relevant optical and transition potentials in a finite nucleus are calculated within a local density approximation. As we use the nuclear matter approach we limit our study to incident energies above 40 MeV. We first checked that this model provides an accurate account of measured cross sections for elastic scattering and inelastic scattering to discrete states. It is then applied to the direct inelastic scattering to the continuum considering all one-phonon excitations predicted within the RPA approach. This accounts for a part of the direct pre-equilibrium emission, often labeled as the one-step direct process in quantum-based approaches. Our approach provides a very accurate description of angular distributions where the one-step process dominates. The impact of collective excitations is shown to be non negligible for energy transfer to the target up to 20 MeV, decreasing as the incident energy increases. For incident energies above 80 MeV, our modeling provides a good account of direct proton emission for an energy transfer to the target up to 30 MeV. However, the proton emission we predict underestimates the measured cross sections for incident energies below 80 MeV. We compare our prediction to those of the phenomenological exciton model to help interpret this result. Directions that may improve our modeling are discussed. (orig.)

  12. Microscopic description of elastic and direct inelastic nucleon scattering off spherical nuclei

    Dupuis, M.

    2017-05-01

    The purpose of this study is to improve the modeling of nucleon direct inelastic scattering to the continuum using a microscopic and parameter-free approach. For the first time, direct elastic scattering, inelastic scattering to discrete excitations and to the continuum are described within a microscopic approach without adjustable parameters. Proton scattering off 90Zr and 208Pb are the reactions used as test case examples of the calculations. The model uses the Melbourne g-matrix and the Random Phase Approximation description of nuclear states, implemented with the Gogny D1S interaction. The relevant optical and transition potentials in a finite nucleus are calculated within a local density approximation. As we use the nuclear matter approach we limit our study to incident energies above 40 MeV. We first checked that this model provides an accurate account of measured cross sections for elastic scattering and inelastic scattering to discrete states. It is then applied to the direct inelastic scattering to the continuum considering all one-phonon excitations predicted within the RPA approach. This accounts for a part of the direct pre-equilibrium emission, often labeled as the one-step direct process in quantum-based approaches. Our approach provides a very accurate description of angular distributions where the one-step process dominates. The impact of collective excitations is shown to be non negligible for energy transfer to the target up to 20 MeV, decreasing as the incident energy increases. For incident energies above 80 MeV, our modeling provides a good account of direct proton emission for an energy transfer to the target up to 30 MeV. However, the proton emission we predict underestimates the measured cross sections for incident energies below 80 MeV. We compare our prediction to those of the phenomenological exciton model to help interpret this result. Directions that may improve our modeling are discussed.

  13. Measuring spatially- and directionally-varying light scattering from biological material.

    Harvey, Todd Alan; Bostwick, Kimberly S; Marschner, Steve

    2013-05-20

    Light interacts with an organism's integument on a variety of spatial scales. For example in an iridescent bird: nano-scale structures produce color; the milli-scale structure of barbs and barbules largely determines the directional pattern of reflected light; and through the macro-scale spatial structure of overlapping, curved feathers, these directional effects create the visual texture. Milli-scale and macro-scale effects determine where on the organism's body, and from what viewpoints and under what illumination, the iridescent colors are seen. Thus, the highly directional flash of brilliant color from the iridescent throat of a hummingbird is inadequately explained by its nano-scale structure alone and questions remain. From a given observation point, which milli-scale elements of the feather are oriented to reflect strongly? Do some species produce broader "windows" for observation of iridescence than others? These and similar questions may be asked about any organisms that have evolved a particular surface appearance for signaling, camouflage, or other reasons. In order to study the directional patterns of light scattering from feathers, and their relationship to the bird's milli-scale morphology, we developed a protocol for measuring light scattered from biological materials using many high-resolution photographs taken with varying illumination and viewing directions. Since we measure scattered light as a function of direction, we can observe the characteristic features in the directional distribution of light scattered from that particular feather, and because barbs and barbules are resolved in our images, we can clearly attribute the directional features to these different milli-scale structures. Keeping the specimen intact preserves the gross-scale scattering behavior seen in nature. The method described here presents a generalized protocol for analyzing spatially- and directionally-varying light scattering from complex biological materials at multiple

  14. Feasibility study of direct spectra measurements for Thomson scattered signals for KSTAR fusion-grade plasmas

    Park, K.-R.; Kim, K.-h.; Kwak, S.; Svensson, J.; Lee, J.; Ghim, Y.-c.

    2017-11-01

    Feasibility study of direct spectra measurements of Thomson scattered photons for fusion-grade plasmas is performed based on a forward model of the KSTAR Thomson scattering system. Expected spectra in the forward model are calculated based on Selden function including the relativistic polarization correction. Noise in the signal is modeled with photon noise and Gaussian electrical noise. Electron temperature and density are inferred using Bayesian probability theory. Based on bias error, full width at half maximum and entropy of posterior distributions, spectral measurements are found to be feasible. Comparisons between spectrometer-based and polychromator-based Thomson scattering systems are performed with varying quantum efficiency and electrical noise levels.

  15. Light-scattering properties of a Venetian blind slat used for daylighting applications

    Nilsson, Annica M. [Department of Engineering Sciences, Angstroem Laboratory, Uppsala University (Sweden); Jonsson, Jacob C. [Environmental Energy Technology Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2010-12-15

    The low cost, simplicity, and aesthetic appearance of external and internal shading devices, make them commonly used for daylighting and glare-control applications. Shading devices, such as Venetian blinds, screens, and roller shades, generally exhibit light scattering and/or light redirecting properties. This requires the bi-directional scattering distribution function (BSDF) of the material to be known in order to accurately predict the daylight distribution and energy flow through the fenestration system. Acquiring the complete BSDF is not a straightforward task, and to complete the process it is often required that a model is used to complement the measured data. In this project, a Venetian blind slat with a white top surface and a brushed aluminum bottom surface was optically characterized. A goniophotometer and an integrating sphere spectrophotometer were used to determine the angle resolved and hemispherical reflectance of the sample, respectively. The acquired data were fitted to a scattering model providing one Lambertian and one angle dependent description of the surface properties. These were used in combination with raytracing to obtain the complete BSDFs of the Venetian blind system. (author)

  16. Progress on calculation of direct inelastic scattering cross section of neutron

    Zhenpeng, Chen [Qinghua Univ., Beijing, BJ (China). Dept. of Physics

    1996-06-01

    For n+ {sup 238}U inelastic scattering cross, there exist discrepancies among the available evaluations in various libraries. This is partly duo to the difference of direct inelastic scattering cross section calculated with coupled channel optical model (CCOM). The research on the level frame used in CCOM calculation, the research on used parameters of spherical optical model in CCOM calculation and the research on the amplitude of octupole phonon {beta}{sub 3} were presented. (2 figs.).

  17. Light-scattering properties of a woven shade-screen material used for daylighting and solar heat-gain control

    Jonsson, Jacob; Jonsson, Jacob C.; Lee, Eleanor S.; Rubin, Mike

    2008-08-01

    Shade-screens are widely used in commercial buildings as a way to limit the amount of direct sunlight that can disturb people in the building. The shade screens also reduce the solar heat-gain through glazing the system. Modern energy and daylighting analysis software such as EnergyPlus and Radiance require complete scattering properties of the scattering materials in the system. In this paper a shade screen used in the LBNL daylighting testbed is characterized using a photogoniometer and a normal angle of incidence integrating sphere. The data is used to create a complete bi-directional scattering distribution function (BSDF) that can be used in simulation programs. The resulting BSDF is compared to a model BADFs, both directly and by calculating the solar heat-gain coefficient for a dual pane system using Window 6.

  18. Theoretical approach to direct resonant inelastic X-ray scattering on magnets and superconductors

    Marra, Pasquale

    2015-10-26

    The capability to probe the dispersion of elementary spin, charge, orbital, and lattice excitations has positioned resonant inelastic X-ray scattering (RIXS) at the forefront of photon science. In this work, we will investigate how RIXS can contribute to a deeper understanding of the orbital properties and of the pairing mechanism in unconventional high-temperature superconductors. In particular, we show how direct RIXS spectra of magnetic excitations can reveal long-range orbital correlations in transition metal compounds, by discriminating different kind of orbital order in magnetic and antiferromagnetic systems. Moreover, we show how RIXS spectra of quasiparticle excitations in superconductors can measure the superconducting gap magnitude, and reveal the presence of nodal points and phase differences of the superconducting order parameter on the Fermi surface. This can reveal the properties of the underlying pairing mechanism in unconventional superconductors, in particular cuprates and iron pnictides, discriminating between different superconducting order parameter symmetries, such as s,d (singlet pairing) and p wave (triplet pairing).

  19. Computational study of the Rayleigh light scattering properties of atmospheric pre-nucleation clusters

    Elm, Jonas; Norman, Patrick; Bilde, Merete

    2014-01-01

    The Rayleigh and hyper Rayleigh scattering properties of the binary (H 2SO4)(H2O)n and ternary (H 2SO4)(NH3)(H2O)n clusters are investigated using a quantum mechanical response theory approach. The molecular Rayleigh scattering intensities are expressed using the dipole polarizability α...... and hyperpolarizability β tensors. Using density functional theory, we elucidate the effect of cluster morphology on the scattering properties using a combinatorial sampling approach. We find that the Rayleigh scattering intensity depends quadratically on the number of water molecules in the cluster and that a single...... ammonia molecule is able to induce a high anisotropy, which further increases the scattering intensity. The hyper Rayleigh scattering activities are found to be extremely low. This study presents the first attempt to map the scattering of atmospheric molecular clusters using a bottom-up approach...

  20. Direct imaging of turbid media using long-time back-scattered photons, a numerical study

    Boulanger, Joan; Liu, Fengshan; El Akel, Azad; Charette, Andre

    2006-01-01

    Direct imaging is a convenient way to obtain information on the interior of a semi-transparent turbid material by non-invasive probing using laser beams. The major difficulty is linked to scattering which scrambles the directional information coming from the laser beam. It is found in this paper that the long-term multiple-scattered reflected photons may provide structural information on the inside of a material, which offers an interesting alternative to using information only from un-scattered or least-scattered photons as obtained from current direct imaging set-ups for thin media. Based on some observations on a non-homogeneous three layered 1-D slab irradiated by a laser pulse, a direct probing methodology making use of the long-term back-scattered photons is illustrated to recover inclusions positions in a turbid 2-D medium. First, the numerical model is presented. Second, an extended parametrical study is conducted on 1-D homogeneous and non-homogeneous slabs with different laser pulse durations. It is found that the reflected asymptotic logarithmic slope carries information about the presence of the inclusion and that short laser pulses are not necessary since only the decaying parts of the remanent optical signature is important. Longer laser pulses allow a higher level of energy injection and signal to noise ratio. Third, those observations are used for the probing of a 2-D non-homogeneous phantom. (author)

  1. The scattering properties of anisotropic dielectric spheres on electromagnetic waves

    Chen Hui; Zhang Weiyi; Wang Zhenlin; Ming Naiben

    2004-01-01

    The scattering coefficients of spheres with dielectric anisotropy are calculated analytically in this paper using the perturbation method. It is found that the different modes of vector spherical harmonics and polarizations are coupled together in the scattering coefficients (c-matrix) in contrast to the isotropic case where all modes are decoupled from each other. The generalized c-matrix is then incorporated into our codes for a vector wave multiple scattering program; the preliminary results on face centred cubic structure show that dielectric anisotropy reduces the symmetry of the scattering c-matrix and removes the degeneracy in photonic band structures composed of isotropic dielectric spheres

  2. Subsurface Scattered Photons: Friend or Foe? Improving visible light laser altimeter elevation estimates, and measuring surface properties using subsurface scattered photons

    Greeley, A.; Kurtz, N. T.; Neumann, T.; Cook, W. B.; Markus, T.

    2016-12-01

    Photon counting laser altimeters such as MABEL (Multiple Altimeter Beam Experimental Lidar) - a single photon counting simulator for ATLAS (Advanced Topographical Laser Altimeter System) - use individual photons with visible wavelengths to measure their range to target surfaces. ATLAS, the sole instrument on NASA's upcoming ICESat-2 mission, will provide scientists a view of Earth's ice sheets, glaciers, and sea ice with unprecedented detail. Precise calibration of these instruments is needed to understand rapidly changing parameters such as sea ice freeboard, and to measure optical properties of surfaces like snow covered ice sheets using subsurface scattered photons. Photons that travel through snow, ice, or water before scattering back to an altimeter receiving system travel farther than photons taking the shortest path between the observatory and the target of interest. These delayed photons produce a negative elevation bias relative to photons scattered directly off these surfaces. We use laboratory measurements of snow surfaces using a flight-tested laser altimeter (MABEL), and Monte Carlo simulations of backscattered photons from snow to estimate elevation biases from subsurface scattered photons. We also use these techniques to demonstrate the ability to retrieve snow surface properties like snow grain size.

  3. SCATTER

    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)

  4. Direct and inverse scattering at fixed energy for massless charged Dirac fields by Kerr-Newman-de Sitter black holes

    Daudé, Thierry

    2017-01-01

    In this paper, the authors study the direct and inverse scattering theory at fixed energy for massless charged Dirac fields evolving in the exterior region of a Kerr-Newman-de Sitter black hole. In the first part, they establish the existence and asymptotic completeness of time-dependent wave operators associated to our Dirac fields. This leads to the definition of the time-dependent scattering operator that encodes the far-field behavior (with respect to a stationary observer) in the asymptotic regions of the black hole: the event and cosmological horizons. The authors also use the miraculous property (quoting Chandrasekhar)-that the Dirac equation can be separated into radial and angular ordinary differential equations-to make the link between the time-dependent scattering operator and its stationary counterpart. This leads to a nice expression of the scattering matrix at fixed energy in terms of stationary solutions of the system of separated equations. In a second part, the authors use this expression of ...

  5. The single scattering properties of the aerosol particles as aggregated spheres

    Wu, Y.; Gu, X.; Cheng, T.; Xie, D.; Yu, T.; Chen, H.; Guo, J.

    2012-01-01

    The light scattering and absorption properties of anthropogenic aerosol particles such as soot aggregates are complicated in the temporal and spatial distribution, which introduce uncertainty of radiative forcing on global climate change. In order to study the single scattering properties of anthorpogenic aerosol particles, the structures of these aerosols such as soot paticles and soot-containing mixtures with the sulfate or organic matter, are simulated using the parallel diffusion limited aggregation algorithm (DLA) based on the transmission electron microscope images (TEM). Then, the single scattering properties of randomly oriented aerosols, such as scattering matrix, single scattering albedo (SSA), and asymmetry parameter (AP), are computed using the superposition T-matrix method. The comparisons of the single scattering properties of these specific types of clusters with different morphological and chemical factors such as fractal parameters, aspect ratio, monomer radius, mixture mode and refractive index, indicate that these different impact factors can respectively generate the significant influences on the single scattering properties of these aerosols. The results show that aspect ratio of circumscribed shape has relatively small effect on single scattering properties, for both differences of SSA and AP are less than 0.1. However, mixture modes of soot clusters with larger sulfate particles have remarkably important effects on the scattering and absorption properties of aggregated spheres, and SSA of those soot-containing mixtures are increased in proportion to the ratio of larger weakly absorbing attachments. Therefore, these complex aerosols come from man made pollution cannot be neglected in the aerosol retrievals. The study of the single scattering properties on these kinds of aggregated spheres is important and helpful in remote sensing observations and atmospheric radiation balance computations.

  6. Directional radiative properties of anisotropic rough silicon and gold surfaces

    Lee, H.J.; Chen, Y.B.; Zhang, Z.M. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2006-11-15

    Recent studies have shown that the topography of some chemically etched microrough silicon surfaces is non-Gaussian and may be strongly anisotropic. However, the bidirectional reflectance distribution function (BRDF) of anisotropic surfaces has not been fully understood. The present study uses the Monte Carlo method to investigate the out-of-plane BRDF, multiple scattering, and the change of the polarization state upon reflection. Two ray-tracing algorithms are developed that incorporate the surface topography or slope distribution of the samples obtained by the use of an atomic force microscope. The predicted BRDFs for silicon surfaces with or without a gold coating are in reasonable agreement with the results measured using a laser scatterometer at a wavelength of 635nm. The employment of surface topographic data is indispensable to the BRDF modeling of anisotropic surfaces. While first-order scattering makes the dominant contribution to reflections from the studied surfaces, it is critical to consider the polarization state change in order to correctly predict the out-of-plane BRDF. The versatile Monte Carlo modeling tools developed through the present study help gain a better understanding of the directional radiative properties of microrough surfaces and, furthermore, will have an impact on thermal metrology in the semiconductor industry. (author)

  7. Stability evaluation considering the scattering of the physical properties of rock mass

    Ito, Hiroshi; Shin, Koichi

    1988-01-01

    The objective of this research is to establish the rational design method which could be evaluated the influence of the scattering of mechanical properties on the stability of the foundation ground of Nuclear Power Plant and surrounding slope. For this purpose, investigation on the actual scattering state of mechanical properties of rock and rock masses, and the stability estimations by the probabilistic method are conducted in this report, and following results are obtained. (1) The actual distribution of scattering of mechanical properties could describe in the probabilistic models of Weibull and Gamma distribution most accurately. The Normal distribution model could also do almostly. The coefficients of variation are so large in the range of 0.4 - 0.8, the remarkable tendency of them among the kinds of mechanical Properties and among the rock classification are not recognized. (2) It is found that the stability estimation considering the scattering of mechanical properties can be sufficiently conducted by using the conventional deterministic method, and the results of deterministic method using the average value of scattering need not be reduce in proportional to the degree of scattering of mechanical properties. (3) Based on these results, new rational design method and procedure, which could be evaluated the scattering of mechanical properties of ground material, is proposed. (author)

  8. Mirror System for Collecting Thomson-Scattered Light in a Tangential Direction

    Barth, C. J.; Grobben, B. J. J.; Verhaag, G. C. H. M.

    1994-01-01

    We describe an optical system for collecting Thomson-scattering light in the tangential direction of a tokamak. The key part of the optics is a set of mirrors arranged as a Venetian blind. This system makes it possible to look around the corner of the tokamak vessel. Design considerations and test

  9. Signatures of Earth-scattering in the direct detection of Dark Matter

    Kavanagh, Bradley J.; Catena, Riccardo; Kouvaris, Chris

    2017-01-01

    Direct detection experiments search for the interactions of Dark Matter (DM) particles with nuclei in terrestrial detectors. But if these interactions are sufficiently strong, DM particles may scatter in the Earth, affecting their distribution in the lab. We present a new analytic calculation...

  10. Directed seed dispersal towards areas with low conspecific tree density by a scatter-hoarding rodent

    Hirsch, Ben T.; Kays, Roland; Pereira, Veronica E.; Jansen, Patrick A.

    2012-01-01

    Scatter-hoarding animals spread out cached seeds to reduce density-dependent theft of their food reserves. This behaviour could lead to directed dispersal into areas with lower densities of conspecific trees, where seed and seedling survival are higher, and could profoundly affect the spatial

  11. Models of direct reactions and quantum pre-equilibrium for nucleon scattering on spherical nuclei

    Dupuis, M.

    2006-01-01

    When a nucleon collides with a target nucleus, several reactions may occur: elastic and inelastic scatterings, charge exchange... In order to describe these reactions, different models are involved: the direct reactions, pre-equilibrium and compound nucleus models. Our goal is to study, within a quantum framework and without any adjustable parameter, the direct and pre-equilibrium reactions for nucleons scatterings off double closed-shell nuclei. We first consider direct reactions: we are studying nucleon scattering with the Melbourne G-matrix, which represents the interaction between the projectile and one target nucleon, and with random phase approximation (RPA) wave functions which describe all target states. This is a fully microscopic approach since no adjustable parameters are involved. A second part is dedicated to the study of nucleon inelastic scattering for large energy transfer which necessarily involves the pre-equilibrium mechanism. Several models have been developed in the past to deal with pre-equilibrium. They start from the Born expansion of the transition amplitude which is associated to the inelastic process and they use several approximations which have not yet been tested. We have achieved some comparisons between second order cross sections which have been calculated with and without these approximations. Our results allow us to criticize some of these approximations and give several directions to improve the quantum pre-equilibrium models. (author)

  12. Optical properties of individual nano-sized gold particle pairs. Mie-scattering, fluorescence, and Raman-scattering

    Olk, Phillip

    2008-07-01

    This thesis examines and exploits the optical properties of pairs of MNPs. Pairs of MNPs offer two further parameters not existent at single MNPs, which both affect the local optical fields in their vicinity: the distance between them, and their relative orientation with respect to the polarisation of the excitation light. These properties are subject of three chapters: One section examines the distance-dependent and orientation-sensitive scattering cross section (SCS) of two equally sized MNPs. Both near- and far-field interactions affect the spectral position and spectral width of the SCS. Far-field coupling affects the SCS even in such a way that a two-particle system may show both a blue- and redshifted SCS, depending only on the distance between the two MNPs. The maximum distance for this effect is the coherence length of the illumination source - a fact of importance for SCS-based experiments using laser sources. Another part of this thesis examines the near-field between two MNPs and the dependence of the locally enhanced field on the relative particle orientation with respect to the polarisation of the excitation light. To attain a figure of merit, the intensity of fluorescence light from dye molecules in the surrounding medium was measured at various directions of polarisation. The field enhancement was turned into fluorescence enhancement, even providing a means for sensing the presence of very small MNPs of 12 nm in diameter. In order to quantify the near-field experimentally, a different technique is devised in a third section of this thesis - scanning particle-enhanced Raman microscopy (SPRM). This device comprises a scanning probe carrying an MNP which in turn is coated with a molecule of known Raman signature. By manoeuvring this outfit MNP into the vicinity of an illuminated second MNP and by measuring the Raman signal intensity, a spatial mapping of the field enhancement was possible. (orig.)

  13. Monitoring muscle optical scattering properties during rigor mortis

    Xia, J.; Ranasinghesagara, J.; Ku, C. W.; Yao, G.

    2007-09-01

    Sarcomere is the fundamental functional unit in skeletal muscle for force generation. In addition, sarcomere structure is also an important factor that affects the eating quality of muscle food, the meat. The sarcomere structure is altered significantly during rigor mortis, which is the critical stage involved in transforming muscle to meat. In this paper, we investigated optical scattering changes during the rigor process in Sternomandibularis muscles. The measured optical scattering parameters were analyzed along with the simultaneously measured passive tension, pH value, and histology analysis. We found that the temporal changes of optical scattering, passive tension, pH value and fiber microstructures were closely correlated during the rigor process. These results suggested that sarcomere structure changes during rigor mortis can be monitored and characterized by optical scattering, which may find practical applications in predicting meat quality.

  14. Scattering of neutral metal clusters: Long-range interactions and response properties

    Kresin, V.V.; Scheidemann, A.

    1993-01-01

    The absolute integral cross sections for low-energy collisions of neutral sodium clusters Na n (n=2--40) with atoms and molecules (Ar, N 2 , O 2 , and halogens) have been measured. The cross sections are found to be exceptionally large (up to thousands of square angstroms), showing the dominant role of long-range intermolecular interactions. Elastic scattering proceeding under the influence of the van der Waals force, and a reaction channel involving electron transfer can successfully describe the measurements. The strength of the van der Waals potential is defined by such cluster response properties as the electric polarizability and the frequency of the giant dipole resonance. The reactive electron-jump channel, in turn, is described by the ''harpooning'' mechanism which is sensitive to the cluster ionization potential. Employing parameters taken from spectroscopic studies of alkali clusters, we obtain good agreement with the observed cross sections. This provides a direct connection between beam scattering experiments and studies of cluster electromagnetic response properties

  15. On the Scattering Properties of Urban and Maritime Aerosols and its ...

    The scattering properties of aerosols play a dominant role in radiative energy transfer and consequently influencing the visibility and turbidity in the atmosphere. In the present attempt, calculations for scattered intensity have been made in case of urban and maritime aerosols in the varying conditions of relative humidity.

  16. Investigation of silicon width (p, p') resonance scattering in left angle 110 right angle channeling direction

    Ditroi, F.; Meyer, J.D.; Michelmann, R.; Kislat, D.; Bethge, K.

    1994-01-01

    Crystalline silicon samples were investigated both in channeling and random directions by using the (p, p') resonance scattering at 2.3 MeV bombarding energy. The samples were positioned in the scattering chamber of a VdG accelerator after 2 m collimating path. The peaks due to the resonance at 2.1 MeV were measured at different angles in the vicinity of the channeling and random directions. A peak shift and broadening was seen at the channeling and near channeling directions compared with the random one. The spectra were also simulated using our modified Monte Carlo calculation method for stopping, range and energy distribution in highly ordered materials. The energy shift and the broadening between the random and the channeling spectra were compared and explained. (orig.)

  17. Direct determination of scattering time delays using the R-matrix propagation method

    Walker, R.B.; Hayes, E.F.

    1989-01-01

    A direct method for determining time delays for scattering processes is developed using the R-matrix propagation method. The procedure involves the simultaneous generation of the global R matrix and its energy derivative. The necessary expressions to obtain the energy derivative of the S matrix are relatively simple and involve many of the same matrix elements required for the R-matrix propagation method. This method is applied to a simple model for a chemical reaction that displays sharp resonance features. The test results of the direct method are shown to be in excellent agreement with the traditional numerical differentiation method for scattering energies near the resonance energy. However, for sharp resonances the numerical differentiation method requires calculation of the S-matrix elements at many closely spaced energies. Since the direct method presented here involves calculations at only a single energy, one is able to generate accurate energy derivatives and time delays much more efficiently and reliably

  18. Direct inelastic scattering of oriented NO from Ag(111) and Pt(111)

    Tenner, M.G.; Kuipers, E.W.; Kleyn, A.W.; Stolte, S.

    1991-01-01

    A pulsed supersonic and cold oriented beam of NO molecules is incident upon the (111) face of clean Ag and Pt single crystal surfaces. The steric effect in the scattered density distributions is determined by a quadrupole mass spectrometer. It is found that the steric effect in the peak in the distribution of direct inelastically scattered molecules depends linearly on the reflection angle. In all circumstances O-end collisions lead to scattering angles more inclined towards the surface than N-end collisions. For the Pt(111) surface a much stronger steric effect is measured than for the Ag(111) surface. The steric effect seems to scale with the incident normal velocity. These strong steric effects can be explained by the larger trapping probability for the N-end orientation and a leverage effect due to the high trapping probability

  19. Update on the direct n-n scattering experiment at the reactor YAGUAR

    Stephenson, S. L.; Crawford, B. E.; Furman, W. I.; Lychagin, E. V.; Muzichka, A. Yu.; Nekhaev, G. V.; Sharapov, E. I.; Shvetsov, V. N.; Strelkov, A. V.; Levakov, B. G.; Lyzhin, A. E.; Chernukhin, Yu. I.; Howell, C. R.; Mitchell, G. E.; Tornow, W.; Showalter-Bucher, R. A.

    2013-10-01

    The first direct measurement of the 1S0 neutron-neutron scattering experiment using the YAGUAR aperiodic reactor at the Russian Federal Nuclear Center - All Russian Research Institute of Technical Physics has preliminary results. Thermal neutrons are scattered from a thermal neutron ``gas'' within the scattering chamber of the reactor and measured via time-of-flight. These initial results show an unexpectedly large thermal neutron background now understood to be from radiation-induced desorption within the scattering chamber. Analysis of the neutron time-of-flight spectra suggests neutron scattering from H2 and possibly H2O molecules. An experimental value for the desorption yield ηγ of 0.02 molecules/gamma agrees with modeled results. Techniques to reduce the effect of the nonthermal desorption will be presented. This work was supported in part by ISTC project No. 2286, Russia Found. Grant 01-02-17181, the US DOE grants Nos. DE-FG02-97-ER41042 and DE-FG02-97-ER41033, and by the US NSF through Award Nos. 0107263 and 0555652.

  20. Direct observation of forward-scattering oscillations in the H+HD→H2+D reaction

    Yuan, Daofu; Yu, Shengrui; Chen, Wentao; Sang, Jiwei; Luo, Chang; Wang, Tao; Xu, Xin; Casavecchia, Piergiorgio; Wang, Xingan; Sun, Zhigang; Zhang, Dong H.; Yang, Xueming

    2018-06-01

    Accurate measurements of product state-resolved angular distributions are central to fundamental studies of chemical reaction dynamics. Yet, fine quantum-mechanical structures in product angular distributions of a reactive scattering process, such as the fast oscillations in the forward-scattering direction, have never been observed experimentally and the nature of these oscillations has not been fully explored. Here we report the crossed-molecular-beam experimental observation of these fast forward-scattering oscillations in the product angular distribution of the benchmark chemical reaction, H + HD → H2 + D. Clear oscillatory structures are observed for the H2(v' = 0, j' = 1, 3) product states at a collision energy of 1.35 eV, in excellent agreement with the quantum-mechanical dynamics calculations. Our analysis reveals that the oscillatory forward-scattering components are mainly contributed by the total angular momentum J around 28. The partial waves and impact parameters responsible for the forward scatterings are also determined from these observed oscillations, providing crucial dynamics information on the transient reaction process.

  1. Light scattering properties of bovine muscle tissue in vitro, a comparison of methods

    Zijp, J.R.; ten Bosch, JJ; Benaron, DA; Chance, B; Ferrari, M; Kohl, M

    1998-01-01

    We measured the light scattering properties of muscular tissue using several methods, and compared the obtained results. Calculation of the extinction coefficient by using collimated transmission measurements and applying Beer's law is not appropriate. Probably surface roughness of the sample

  2. Light scattering reviews 7 radiative transfer and optical properties of atmosphere and underlying surface

    Kokhanovsky, Alexander A

    2014-01-01

    This book describes modern advances in radiative transfer and light scattering. Coverage includes fast radiative transfer techniques, use of polarization in remote sensing and recent developments in remote sensing of snow properties from space observations.

  3. RAMAN SCATTERING BY ACOUSTIC PHONONS AND STRUCTURAL PROPERTIES OF FIBONACCI, THUE-MORSE AND RANDOM SUPERLATTICES

    Merlin , R.; Bajema , K.; Nagle , J.; Ploog , K.

    1987-01-01

    We report structural studies of incommensurate and random GaAs-AlAs superlattices using Raman scattering by acoustic phonons. Properties of the structure factor of Fibonacci and Thue-Morse superlattices are discussed in some detail.

  4. Snow particles extracted from X-ray computed microtomography imagery and their single-scattering properties

    Ishimoto, Hiroshi; Adachi, Satoru; Yamaguchi, Satoru; Tanikawa, Tomonori; Aoki, Teruo; Masuda, Kazuhiko

    2018-04-01

    Sizes and shapes of snow particles were determined from X-ray computed microtomography (micro-CT) images, and their single-scattering properties were calculated at visible and near-infrared wavelengths using a Geometrical Optics Method (GOM). We analyzed seven snow samples including fresh and aged artificial snow and natural snow obtained from field samples. Individual snow particles were numerically extracted, and the shape of each snow particle was defined by applying a rendering method. The size distribution and specific surface area distribution were estimated from the geometrical properties of the snow particles, and an effective particle radius was derived for each snow sample. The GOM calculations at wavelengths of 0.532 and 1.242 μm revealed that the realistic snow particles had similar scattering phase functions as those of previously modeled irregular shaped particles. Furthermore, distinct dendritic particles had a characteristic scattering phase function and asymmetry factor. The single-scattering properties of particles of effective radius reff were compared with the size-averaged single-scattering properties. We found that the particles of reff could be used as representative particles for calculating the average single-scattering properties of the snow. Furthermore, the single-scattering properties of the micro-CT particles were compared to those of particle shape models using our current snow retrieval algorithm. For the single-scattering phase function, the results of the micro-CT particles were consistent with those of a conceptual two-shape model. However, the particle size dependence differed for the single-scattering albedo and asymmetry factor.

  5. Comparative analysis of direct and indirect property investment ...

    Comparative analysis of direct and indirect property investment returns in Abuja. ... in property shares is more risky than commercial property due to the risk ... of the stock market, it was discovered that there is a strong positive relationship ...

  6. Magnetothermoelectric properties of layered structures for ion impurity scattering

    Figarova, S. R.; Huseynov, H. I.; Figarov, V. R.

    2018-05-01

    In the paper, longitudinal and transverse thermoelectric powers are considered in a magnetic field parallel to the layer plane for scattering of charge carriers by weakly screened impurity ions. Based on the semiclassical approximation, it is obtained that, depending on the position of the Fermi level relative to the miniband top and superlattice period, the thermoelectric power can change sign and amplify.

  7. Analytical properties and behaviour of scattering amplitude at high energies in the localizable quantum field theory

    Lazur, V.Yu.; Khimich, I.V.

    1977-01-01

    Analytical properties of the elastic πN-scattering amplitude in in the cos THETA are proved in the Lehmann ellipse. The instrument for establishing analytical properties of the scattering amplitude in the cos THETA is the Jost-Lehmann-Dyson integral representation proved in terms of the localizable quantum field theory containing the strictly localizable theory and theory of moderate growth as particular cases. On this basis the Greenberg-Low restriction is obtained in frames of this class theories for the πN-scattering amplitude. This result gives a possibility to prove the ordinary dispersion relations with a finite number of subtraction in frames of the localizable quantum field theory

  8. On the Retrieval of the Directional Scattering Matrix from Directional Noise

    Wapenaar, C.P.A.; Thorbecke, J.W.

    2013-01-01

    The crosscorrelation of ambient acoustic noise observed at two receivers yields the impulse response between these receivers, assuming that the noise field is diffuse. In practical situations the noise field exhibits directionality, which imprints the angle-dependent correlation function. For the

  9. Brillouin light scattering studies of the mechanical properties of ultrathin low-k dielectric films

    Link, A.; Sooryakumar, R.; Bandhu, R. S.; Antonelli, G. A.

    2006-07-01

    In an effort to reduce RC time delays that accompany decreasing feature sizes, low-k dielectric films are rapidly emerging as potential replacements for silicon dioxide (SiO2) at the interconnect level in integrated circuits. The main challenge in low-k materials is their substantially weaker mechanical properties that accompany the increasing pore volume content needed to reduce k. We show that Brillouin light scattering is an excellent nondestructive technique to monitor and characterize the mechanical properties of these porous films at thicknesses well below 200nm that are pertinent to present applications. Observation of longitudinal and transverse standing wave acoustic resonances and the dispersion that accompany their transformation into traveling waves with finite in-plane wave vectors provides for a direct measure of the principal elastic constants that completely characterize the mechanical properties of these ultrathin films. The mode amplitudes of the standing waves, their variation within the film, and the calculated Brillouin intensities account for most aspects of the spectra. We further show that the values obtained by this method agree well with other experimental techniques such as nanoindentation and picosecond laser ultrasonics.

  10. DaMaSCUS: the impact of underground scatterings on direct detection of light dark matter

    Emken, Timon; Kouvaris, Chris, E-mail: emken@cp3.sdu.dk, E-mail: kouvaris@cp3.sdu.dk [CP3-Origins, University of Southern Denmark, Campusvej 55, DK-5230 Odense (Denmark)

    2017-10-01

    Conventional dark matter direct detection experiments set stringent constraints on dark matter by looking for elastic scattering events between dark matter particles and nuclei in underground detectors. However these constraints weaken significantly in the sub-GeV mass region, simply because light dark matter does not have enough energy to trigger detectors regardless of the dark matter-nucleon scattering cross section. Even if future experiments lower their energy thresholds, they will still be blind to parameter space where dark matter particles interact with nuclei strongly enough that they lose enough energy and become unable to cause a signal above the experimental threshold by the time they reach the underground detector. Therefore in case dark matter is in the sub-GeV region and strongly interacting, possible underground scatterings of dark matter with terrestrial nuclei must be taken into account because they affect significantly the recoil spectra and event rates, regardless of whether the experiment probes DM via DM-nucleus or DM-electron interaction. To quantify this effect we present the publicly available Dark Matter Simulation Code for Underground Scatterings (DaMaSCUS), a Monte Carlo simulator of DM trajectories through the Earth taking underground scatterings into account. Our simulation allows the precise calculation of the density and velocity distribution of dark matter at any detector of given depth and location on Earth. The simulation can also provide the accurate recoil spectrum in underground detectors as well as the phase and amplitude of the diurnal modulation caused by this shadowing effect of the Earth, ultimately relating the modulations expected in different detectors, which is important to decisively conclude if a diurnal modulation is due to dark matter or an irrelevant background.

  11. DaMaSCUS: the impact of underground scatterings on direct detection of light dark matter

    Emken, Timon; Kouvaris, Chris

    2017-01-01

    Conventional dark matter direct detection experiments set stringent constraints on dark matter by looking for elastic scattering events between dark matter particles and nuclei in underground detectors. However these constraints weaken significantly in the sub-GeV mass region, simply because light dark matter does not have enough energy to trigger detectors regardless of the dark matter-nucleon scattering cross section. Even if future experiments lower their energy thresholds, they will still be blind to parameter space where dark matter particles interact with nuclei strongly enough that they lose enough energy and become unable to cause a signal above the experimental threshold by the time they reach the underground detector. Therefore in case dark matter is in the sub-GeV region and strongly interacting, possible underground scatterings of dark matter with terrestrial nuclei must be taken into account because they affect significantly the recoil spectra and event rates, regardless of whether the experiment probes DM via DM-nucleus or DM-electron interaction. To quantify this effect we present the publicly available Dark Matter Simulation Code for Underground Scatterings (DaMaSCUS), a Monte Carlo simulator of DM trajectories through the Earth taking underground scatterings into account. Our simulation allows the precise calculation of the density and velocity distribution of dark matter at any detector of given depth and location on Earth. The simulation can also provide the accurate recoil spectrum in underground detectors as well as the phase and amplitude of the diurnal modulation caused by this shadowing effect of the Earth, ultimately relating the modulations expected in different detectors, which is important to decisively conclude if a diurnal modulation is due to dark matter or an irrelevant background.

  12. Direct Observation of Insulin Association Dynamics with Time-Resolved X-ray Scattering

    Rimmerman, Dolev [Department; Leshchev, Denis [Department; Hsu, Darren J. [Department; Hong, Jiyun [Department; Kosheleva, Irina [Center; Chen, Lin X. [Department; Chemical

    2017-09-05

    Biological functions frequently require protein-protein interactions that involve secondary and tertiary structural perturbation. Here we study protein-protein dissociation and reassociation dynamics in insulin, a model system for protein oligomerization. Insulin dimer dissociation into monomers was induced by a nanosecond temperature-jump (T-jump) of ~8 °C in aqueous solution, and the resulting protein and solvent dynamics were tracked by time-resolved X-ray solution scattering (TRXSS) on time scales of 10 ns to 100 ms. The protein scattering signals revealed the formation of five distinguishable transient species during the association process that deviate from simple two state kinetics. Our results show that the combination of T-jump pump coupled to TRXSS probe allows for direct tracking of structural dynamics in nonphotoactive proteins.

  13. Effect of surface roughness scattering on the transport properties of a 2DEG

    Yarar, Z.

    2004-01-01

    In this work surface roughness scattering of electrons in a two dimensional electron gas (2DEG) formed at heterojunction interfaces is investigated for various auto-correlation functions. Gaussian, exponential and Lorentzian auto-correlation functions are used to represent surface roughness. Poisson and Schrodinger equations are solved self consistently at the hetero interface to find the energy levels, the wave functions corresponding to each level and electron concentrations at each level. Using these wave functions and the auto-correlation functions mentioned above, the scattering rates due to surface roughness are calculated. Scattering rates resulting from acoustic and optical phonons are also calculated. These rates are used to study the transport properties of the two dimensional electrons using ensemble Monte Carlo method at various temperatures. Emphasis is given to the effect of surface roughness scattering on the transport properties of the electrons

  14. A Numerical Method for Analyzing Electromagnetic Scattering Properties of a Moving Conducting Object

    Lei Kuang

    2014-01-01

    Full Text Available A novel numerical approach is developed to analyze electromagnetic scattering properties of a moving conducting object based on the finite-difference time-domain (FDTD algorithm. Relativistic boundary conditions are implemented into the FDTD algorithm to calculate the electromagnetic field on the moving boundary. An improved technique is proposed to solve the scattered field in order to improve the computational efficiency and stability of solutions. The time-harmonic scattered field from a one-dimensional moving conducting surface is first simulated by the proposed approach. Numerical results show that the amplitude and frequency of the scattered field suffer a modulation shift. Then the transient scattered field is calculated, and broadband electromagnetic scattering properties of the moving conducting surface are obtained by the fast Fourier transform (FFT. Finally, the scattered field from a two-dimensional moving square cylinder is analyzed. The numerical results demonstrate the Doppler effect of a moving conducting object. The simulated results agree well with analytical results.

  15. Scattering and radiative properties of semi-external versus external mixtures of different aerosol types

    Mishchenko, Michael I.; Liu Li; Travis, Larry D.; Lacis, Andrew A.

    2004-01-01

    The superposition T-matrix method is used to compute the scattering of unpolarized light by semi-external aerosol mixtures in the form of polydisperse, randomly oriented two-particle clusters with touching components. The results are compared with those for composition-equivalent external aerosol mixtures, in which the components are widely separated and scatter light in isolation from each other. It is concluded that aggregation is likely to have a relatively weak effect on scattering and radiative properties of two-component tropospheric aerosols and can be replaced by the much simpler external-mixture model in remote sensing studies and atmospheric radiation balance computations

  16. Variability in millimeter wave scattering properties of dendritic ice crystals

    Botta, Giovanni; Aydin, Kültegin; Verlinde, Johannes

    2013-01-01

    A detailed electromagnetic scattering model for ice crystals is necessary for calculating radar reflectivity from cloud resolving model output in any radar simulator. The radar reflectivity depends on the backscattering cross sections and size distributions of particles in the radar resolution volume. The backscattering cross section depends on the size, mass and distribution of mass within the crystal. Most of the available electromagnetic scattering data for ice hydrometeors rely on simple ice crystal types and a single mass–dimensional relationship for a given type. However, a literature survey reveals that the mass–dimensional relationships for dendrites cover a relatively broad region in the mass–dimensional plane. This variability of mass and mass distribution of dendritic ice crystals cause significant variability in their backscattering cross sections, more than 10 dB for all sizes (0.5–5 mm maximum dimension) and exceeding 20 dB for the larger ones at X-, Ka-, and W-band frequencies. Realistic particle size distributions are used to calculate radar reflectivity and ice water content (IWC) for three mass–dimensional relationships. The uncertainty in the IWC for a given reflectivity spans an order of magnitude in value at all three frequencies because of variations in the unknown mass–dimensional relationship and particle size distribution. The sensitivity to the particle size distribution is reduced through the use of dual frequency reflectivity ratios, e.g., Ka- and W-band frequencies, together with the reflectivity at one of the frequencies for estimating IWC. -- Highlights: • Millimeter wave backscattering characteristics of dendritic crystals are modeled. • Natural variability of dendrite shapes leads to large variability in their mass. • Dendrite mass variability causes large backscattering cross section variability. • Reflectivity–ice water content relation is sensitive to mass and size distribution. • Dual frequency

  17. Direct observation and theory of trajectory-dependent electronic energy losses in medium-energy ion scattering.

    Hentz, A; Parkinson, G S; Quinn, P D; Muñoz-Márquez, M A; Woodruff, D P; Grande, P L; Schiwietz, G; Bailey, P; Noakes, T C Q

    2009-03-06

    The energy spectrum associated with scattering of 100 keV H+ ions from the outermost few atomic layers of Cu(111) in different scattering geometries provides direct evidence of trajectory-dependent electronic energy loss. Theoretical simulations, combining standard Monte Carlo calculations of the elastic scattering trajectories with coupled-channel calculations to describe inner-shell ionization and excitation as a function of impact parameter, reproduce the effects well and provide a means for far more complete analysis of medium-energy ion scattering data.

  18. Computational Combination of the Optical Properties of Fenestration Layers at High Directional Resolution

    Lars Oliver Grobe

    2017-03-01

    Full Text Available Complex fenestration systems typically comprise co-planar, clear and scattering layers. As there are many ways to combine layers in fenestration systems, a common approach in building simulation is to store optical properties separate for each layer. System properties are then computed employing a fast matrix formalism, often based on a directional basis devised by JHKlems comprising 145 incident and 145 outgoing directions. While this low directional resolution is found sufficient to predict illuminance and solar gains, it is too coarse to replicate the effects of directionality in the generation of imagery. For increased accuracy, a modification of the matrix formalism is proposed. The tensor-tree format of RADIANCE, employing an algorithm subdividing the hemisphere at variable resolutions, replaces the directional basis. The utilization of the tensor-tree with interfaces to simulation software allows sharing and re-use of data. The light scattering properties of two exemplary fenestration systems as computed employing the matrix formalism at variable resolution show good accordance with the results of ray-tracing. Computation times are reduced to 0.4% to 2.5% compared to ray-tracing through co-planar layers. Imagery computed employing the method illustrates the effect of directional resolution. The method is supposed to foster research in the field of daylighting, as well as applications in planning and design.

  19. Measurement of photon production in the very forward direction in deep-inelastic scattering at HERA

    Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (RU)] (and others)

    2011-06-15

    The production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron-proton scattering at HERA. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 126 pb{sup -1}. The analysis covers the range of negative four momentum transfer squared at the positron vertex 67.9 as a function of its transverse momentum p{sub T}{sup lead} and longitudinal momentum fraction of the incoming proton x{sub L}{sup lead}. In addition, the cross sections are studied as a function of the sum of the longitudinal momentum fraction x{sub L}{sup sum} of all photons in the pseudorapidity range {eta}>7.9. The cross sections are normalised to the inclusive deep-inelastic scattering cross section and compared to the predictions of models of deep-inelastic scattering and models of the hadronic interactions of high energy cosmic rays. (orig.)

  20. Measurement of Photon Production in the Very Forward Direction in Deep-Inelastic Scattering at HERA

    Aaron, F.D.; Andreev, V.; Backovic, S.; Baghdasaryan, A.; Baghdasaryan, S.; Barrelet, E.; Bartel, W.; Begzsuren, K.; Belousov, A.; Belov, P.; Bizot, J.C.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Britzger, D.; Bruncko, D.; Bunyatyan, A.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Ceccopieri, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Contreras, J.G.; Coughlan, J.A.; Cvach, J.; Dainton, J.B.; Daum, K.; Delcourt, B.; Delvax, J.; De Wolf, E.A.; Diaconu, C.; Dobre, M.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Egli, S.; Eliseev, A.; Elsen, E.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Huber, F.; Jacquet, M.; Janssen, X.; Jonsson, L.; Jung, H.; Kapichine, M.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kluge, T.; Kogler, R.; Kostka, P.; Kraemer, M.; Kretzschmar, J.; Kruger, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Lendermann, V.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lopez-Fernandez, R.; Lubimov, V.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Moreau, F.; Morozov, A.; Morris, J.V.; Mudrinic, M.; Muller, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikitin, D.; Nowak, G.; Nowak, K.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Perez, E.; Petrukhin, A.; Picuric, I.; Piec, S.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Polifka, R.; Povh, B.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Tabasco, J.E.Ruiz; Rusakov, S.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.C.; Sefkow, F.; Shtarkov, L.N.; Shushkevich, S.; Sloan, T.; Smiljanic, I.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Staykova, Z.; Steder, M.; Stella, B.; Stoicea, G.; Straumann, U.; Sykora, T.; Thompson, P.D.; Tran, T.H.; Traynor, D.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; Wegener, D.; Wunsch, E.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zohrabyan, H.; Zomer, F.

    2011-01-01

    The production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron-proton scattering at HERA. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of $126 \\mathrm{pb}^{-1}$. The analysis covers the range of negative four momentum transfer squared at the positron vertex $67.9$ as a function of its transverse momentum $p_T^{lead}$ and longitudinal momentum fraction of the incoming proton $x_L^{lead}$. In addition, the cross sections are studied as a function of the sum of the longitudinal momentum fraction $x_L^{sum}$ of all photons in the pseudorapidity range $\\eta>7.9$. The cross sections are normalised to the inclusive deep-inelastic scattering cross section and compared to the predictions of models of deep-inelastic scattering and models of the hadronic interactions of high energy cosmic rays.

  1. Fractal scattering of Gaussian solitons in directional couplers with logarithmic nonlinearities

    Teixeira, Rafael M.P.; Cardoso, Wesley B., E-mail: wesleybcardoso@gmail.com

    2016-08-12

    In this paper we study the interaction of Gaussian solitons in a dispersive and nonlinear media with log-law nonlinearity. The model is described by the coupled logarithmic nonlinear Schrödinger equations, which is a nonintegrable system that allows the observation of a very rich scenario in the collision patterns. By employing a variational approach and direct numerical simulations, we observe a fractal-scattering phenomenon from the exit velocities of each soliton as a function of the input velocities. Furthermore, we introduce a linearization model to identify the position of the reflection/transmission window that emerges within the chaotic region. This enables us the possibility of controlling the scattering of solitons as well as the lifetime of bound states. - Highlights: • We study the interaction of Gaussian solitons in a system with log-law nonlinearity. • The model is described by the coupled logarithmic nonlinear Schrödinger equations. • We observe a fractal-scattering phenomenon of the solitons.

  2. Measurement of photon production in the very forward direction in deep-inelastic scattering at HERA

    Aaron, F.D.; Alexa, C.; Rotaru, M.; Stoicea, G. [National Inst. for Physics and Nuclear Engineering, Bucharest (Romania); Andreev, V.; Belousov, A.; Eliseev, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Shtarkov, L.N.; Soloviev, Y.; Vazdik, Y. [Lebedev Physical Inst., Moscow (Russian Federation); Backovic, S.; Dubak, A.; Lastovicka-Medin, G.; Picuric, I.; Raicevic, N. [Univ. of Montenegro, Podgorica (ME); Baghdasaryan, A.; Baghdasaryan, S.; Zohrabyan, H. [Yerevan Physics Inst. (Armenia); Barrelet, E. [Univ. Pierre et Marie Curie Paris 6, LPNHE, Paris (France); Univ. Denis Diderot Paris 7, CNRS/IN2P3, Paris (France); Bartel, W.; Belov, P.; Brandt, G.; Brinkmann, M.; Britzger, D.; Campbell, A.J.; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Gouzevitch, M.; Grebenyuk, A.; Grell, B.R.; Habib, S.; Haidt, D.; Helebrant, C.; Kleinwort, C.; Kogler, R.; Kraemer, M.; Levonian, S.; Lipka, K.; List, J.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Nowak, K.; Olsson, J.E.; Pahl, P.; Panagoulias, I.; Papadopoulou, T.; Petrukhin, A.; Piec, S.; Pitzl, D.; Schmitt, S.; Sefkow, F.; South, D.; Steder, M.; Wuensch, E. [DESY, Hamburg (Germany); Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B. [Inst. of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Bizot, J.C.; Brisson, V.; Delcourt, B.; Jacquet, M.; Pascaud, C.; Tran, T.H.; Zhang, Z.; Zomer, F. [Univ. Paris-Sud, CNRS/IN2P3, LAL, Orsay (France); Boudry, V.; Moreau, F.; Specka, A. [Ecole Polytechnique, CNRS/IN2P3, LLR, Palaiseau (France); Bozovic-Jelisavcic, I.; Mudrinic, M.; Pandurovic, M.; Smiljanic, I. [Univ. of Belgrade, Vinca Institute of Nuclear Sciences, Belgrade (RS); Bracinik, J.; Kenyon, I.R.; Newman, P.R.; Thompson, P.D. [Univ. of Birmingham (United Kingdom); Bruncko, D.; Cerny, V.; Ferencei, J. [Slovak Academy of Sciences, Inst. of Experimental Physics, Kosice (Slovakia)] [and others

    2011-10-15

    The production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron-proton scattering at HERA. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 126 pb{sup -1}. The analysis covers the range of negative four momentum transfer squared at the positron vertex 67.9 as a function of its transverse momentum p{sub T}{sup lead} and longitudinal momentum fraction of the incoming proton x{sub L}{sup lead}. In addition, the cross sections are studied as a function of the sum of the longitudinal momentum fraction x{sub L}{sup sum} of all photons in the pseudorapidity range {eta}>7.9. The cross sections are normalised to the inclusive deep-inelastic scattering cross section and compared to the predictions of models of deep-inelastic scattering and models of the hadronic interactions of high energy cosmic rays. (orig.)

  3. Investigation of deep inelastic scattering processes involving large p$_{t}$ direct photons in the final state

    2002-01-01

    This experiment will investigate various aspects of photon-parton scattering and will be performed in the H2 beam of the SPS North Area with high intensity hadron beams up to 350 GeV/c. \\\\\\\\ a) The directly produced photon yield in deep inelastic hadron-hadron collisions. Large p$_{t}$ direct photons from hadronic interactions are presumably a result of a simple annihilation process of quarks and antiquarks or of a QCD-Compton process. The relative contribution of the two processes can be studied by using various incident beam projectiles $\\pi^{+}, \\pi^{-}, p$ and in the future $\\bar{p}$. \\\\\\\\b) The correlations between directly produced photons and their accompanying hadronic jets. We will examine events with a large p$_{t}$ direct photon for away-side jets. If jets are recognised their properties will be investigated. Differences between a gluon and a quark jet may become observable by comparing reactions where valence quark annihilations (away-side jet originates from a gluon) dominate over the QDC-Compton...

  4. Local analyticity properties of the n particle scattering amplitude

    Bros, J; Glaser, Vladimir Jurko

    1972-01-01

    The connected part F/sub /c(p) of the scattering amplitude (p/sub 1 /...p/sub /r mod S-1 mod p/sub r+1/,..., p/sub n/) defined on the mass shell p/sub i//sup 2/=m/sub i//sup 2/ and deduced from a local field theory involving only (stable) particles with strictly positive masses can be represented in a suitable neighbourhood of any physical point p as a finite sum f/sub /c(p)= Sigma /sub 1//sup N/F/sub i/(p) of partial amplitudes', each F/sub i/(k) analytic in a certain domain F /sub i/ of the complex mass shell k/sub i//sup 2/=m/sub i//sup 2/. The mentioned real neighbourhood lies on the boundary of each F/sub i/. The above decomposition may fail to hold only at points p where any two incoming or any two outgoing four-momenta become parallel (thresholds). The number N as well as the shape of the domains F/sub i / depend on the number n and on the real neighbourhood considered. For a generic configuration p the intersection of the domains F/sub i/ is empty. When this does not happen, F/sub i/(p) is the boundar...

  5. Characterization of the Optical Properties of Turbid Media by Supervised Learning of Scattering Patterns.

    Hassaninia, Iman; Bostanabad, Ramin; Chen, Wei; Mohseni, Hooman

    2017-11-10

    Fabricated tissue phantoms are instrumental in optical in-vitro investigations concerning cancer diagnosis, therapeutic applications, and drug efficacy tests. We present a simple non-invasive computational technique that, when coupled with experiments, has the potential for characterization of a wide range of biological tissues. The fundamental idea of our approach is to find a supervised learner that links the scattering pattern of a turbid sample to its thickness and scattering parameters. Once found, this supervised learner is employed in an inverse optimization problem for estimating the scattering parameters of a sample given its thickness and scattering pattern. Multi-response Gaussian processes are used for the supervised learning task and a simple setup is introduced to obtain the scattering pattern of a tissue sample. To increase the predictive power of the supervised learner, the scattering patterns are filtered, enriched by a regressor, and finally characterized with two parameters, namely, transmitted power and scaled Gaussian width. We computationally illustrate that our approach achieves errors of roughly 5% in predicting the scattering properties of many biological tissues. Our method has the potential to facilitate the characterization of tissues and fabrication of phantoms used for diagnostic and therapeutic purposes over a wide range of optical spectrum.

  6. Influence of the Pauli exclusion principle on scattering properties of cobosons

    Thilagam, A.

    2015-01-01

    We examine the influence of the Pauli exclusion principle on the scattering properties of composite bosons (cobosons) made of two fermions, such as the exciton quasiparticle. The scattering process incorporates boson–phonon interactions that arise due to lattice vibrations. Composite boson scattering rates increase with the entanglement between the two fermionic constituents, which comes with a large number of available single-fermion states. An important role is played by probabilities associated with accommodating an incoming boson among the remaining unoccupied Schmidt modes in the initial composite system. While due attention is given to bi-fermion bosons, the methodology is applicable to any composite boson made up of smaller boson fragments. Due to super-bunching in a system of multiple boson condensates such as bi-bosons, there is enhanced scattering associated with bosons occupying macroscopically occupied Schmidt modes, in contrast to the system of bi-fermion pairs

  7. Scattering Properties of Electromagnetic Waves from Randomly Oriented Rough Metal Plate in the Lower Terahertz Region

    Chen Gang

    2018-02-01

    Full Text Available An efficient hybrid algorithm is proposed to analyze the electromagnetic scattering properties of an infinitely thin metal plate in the lower terahertz (THz frequency region. In this region, the metal plate can be viewed as a perfect electrically conductive object with a marginally rough surface. Hence, the THz scattered field from the metal plate can be divided into coherent and incoherent parts. The physical optics and truncated-wedge incremental-length diffraction coefficients methods are used to compute the coherent part, whereas the small perturbation method is used to compute the incoherent part. Then, the radar cross section of the rough metal plate surface is computed by the multilevel fast multipole and proposed hybrid algorithms. The numerical results show that the proposed algorithm has a good accuracy when rapidly simulating the scattering properties in the lower THz region.

  8. Scattering properties of electromagnetic waves from metal object in the lower terahertz region

    Chen, Gang; Dang, H. X.; Hu, T. Y.; Su, Xiang; Lv, R. C.; Li, Hao; Tan, X. M.; Cui, T. J.

    2018-01-01

    An efficient hybrid algorithm is proposed to analyze the electromagnetic scattering properties of metal objects in the lower terahertz (THz) frequency. The metal object can be viewed as perfectly electrical conducting object with a slightly rough surface in the lower THz region. Hence the THz scattered field from metal object can be divided into coherent and incoherent parts. The physical optics and truncated-wedge incremental-length diffraction coefficients methods are combined to compute the coherent part; while the small perturbation method is used for the incoherent part. With the MonteCarlo method, the radar cross section of the rough metal surface is computed by the multilevel fast multipole algorithm and the proposed hybrid algorithm, respectively. The numerical results show that the proposed algorithm has good accuracy to simulate the scattering properties rapidly in the lower THz region.

  9. Local scattering property scales flow speed estimation in laser speckle contrast imaging

    Miao, Peng; Chao, Zhen; Feng, Shihan; Ji, Yuanyuan; Yu, Hang; Thakor, Nitish V; Li, Nan

    2015-01-01

    Laser speckle contrast imaging (LSCI) has been widely used in in vivo blood flow imaging. However, the effect of local scattering property (scattering coefficient µ s ) on blood flow speed estimation has not been well investigated. In this study, such an effect was quantified and involved in relation between speckle autocorrelation time τ c and flow speed v based on simulation flow experiments. For in vivo blood flow imaging, an improved estimation strategy was developed to eliminate the estimation bias due to the inhomogeneous distribution of the scattering property. Compared to traditional LSCI, a new estimation method significantly suppressed the imaging noise and improves the imaging contrast of vasculatures. Furthermore, the new method successfully captured the blood flow changes and vascular constriction patterns in rats’ cerebral cortex from normothermia to mild and moderate hypothermia. (letter)

  10. Spin rotation after a spin-independent scattering. Spin properties of an electron gas in a solid

    Zayets, V.

    2014-01-01

    It is shown that spin direction of an electron may not be conserved after a spin-independent scattering. The spin rotations occur due to a quantum-mechanical fact that when a quantum state is occupied by two electrons of opposite spins, the total spin of the state is zero and the spin direction of each electron cannot be determined. It is shown that it is possible to divide all conduction electrons into two group distinguished by their time-reversal symmetry. In the first group the electron spins are all directed in one direction. In the second group there are electrons of all spin directions. The number of electrons in each group is conserved after a spin-independent scattering. This makes it convenient to use these groups for the description of the magnetic properties of conduction electrons. The energy distribution of spins, the Pauli paramagnetism and the spin distribution in the ferromagnetic metals are described within the presented model. The effects of spin torque and spin-torque current are described. The origin of spin-transfer torque is explained within the presented model

  11. On calculating phase shifts and performing fits to scattering cross sections or transport properties

    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.)

  12. Predicting scattering properties of ultracold atoms : Adiabatic accumulated phase method and mass scaling

    Verhaar, B.J.; Kempen, van E.G.M.; Kokkelmans, S.J.J.M.F.

    2009-01-01

    Ultracold atoms are increasingly used for high-precision experiments that can be utilized to extract accurate scattering properties. This results in a stronger need to improve on the accuracy of interatomic potentials, and in particular the usually rather inaccurate inner-range potentials. A

  13. Light-scattering properties of undiluted human blood subjected to simple shear

    Steenbergen, Wiendelt; Kolkman, R.G.M.; de Mul, F.F.M.

    1999-01-01

    An experimental investigation was performed into the effect of simple shear on the light-scattering properties of undiluted human blood. Undiluted human blood was enclosed between two glass plates with an adjustable separation between 30 and 120 mm and with one plate moving parallel to the other.

  14. Computing the scattering properties of participating media using Lorenz-Mie theory

    2007-01-01

    This source code implements Lorenz-Mie theory using the formulas presented in the SIGGRAPH 2007 paper: J. R. Frisvad, N. J. Christensen, and H. W. Jensen: "Computing the Scattering Properties of Participating Media Using Lorenz-Mie Theory". Copyright (c) ACM 2007. This is the author's version...

  15. Absorption and scattering properties of arbitrarily shaped particles in the Rayleigh domain

    Min, M.; Hovenier, J.W.; Dominik, C.; Koter, A. de; Yurkin, M.A.

    2006-01-01

    We provide a theoretical foundation for the statistical approach for computing the absorption properties of particles in the Rayleigh domain. We present a general method based on the discrete dipole approximation to compute the absorption and scattering properties of particles in the Rayleigh domain. The method allows to separate the geometrical aspects of a particle from its material properties. Doing the computation of the optical properties of a particle once, provides them for any set of refractive indices, wavelengths and orientations. This allows for fast computations of e.g. absorption spectra of arbitrarily shaped particles. Other practical applications of the method are in the interpretation of atmospheric and radar measurements as well as computations of the scattering matrix of small particles as a function of the scattering angle. In the statistical approach, the optical properties of irregularly shaped particles are represented by the average properties of an ensemble of particles with simple shapes. We show that the absorption cross section of an ensemble of arbitrarily shaped particles with arbitrary orientations can always be uniquely represented by the average absorption cross section of an ensemble of spheroidal particles with the same composition and fixed orientation. This proves for the first time that the statistical approach is generally viable in the Rayleigh domain

  16. Simulations of the Light Scattering Properties of Metal/Oxide Core/Shell Nanospheres

    Ruffino, F.; Piccitto, G.; Grimaldi, M.G.; Ruffino, F.; Grimaldi, M.G.

    2014-01-01

    Given the importance of the optical properties of metal/dielectric core/shell nanoparticles, in this work we focus our attention on the light scattering properties, within the Mie framework, of some specific categories of these noteworthy nano structures. In particular, we report theoretical results of angle-dependent light scattering intensity and scattering efficiency for Ag/Ag 2 O, Al/Al 2 O 2 , Cu/Cu 2 O, Pd/PdO, and Ti/TiO 2 core/shell nanoparticles as a function of the core radius/shell thickness ratio and on a relative comparison. The results highlight the light scattering characteristics of these systems as a function of the radius/shell thickness ratio, helping in the choice of the more suitable materials and sizes for specific applications (i.e., dynamic light scattering for biological and molecular recognition, increasing light trapping in thin-film silicon, organic solar cells for achieving a higher photocurrent).

  17. A simple, direct method for x-ray scatter estimation and correction in digital radiography and cone-beam CT

    Siewerdsen, J.H.; Daly, M.J.; Bakhtiar, B.

    2006-01-01

    X-ray scatter poses a significant limitation to image quality in cone-beam CT (CBCT), resulting in contrast reduction, image artifacts, and lack of CT number accuracy. We report the performance of a simple scatter correction method in which scatter fluence is estimated directly in each projection from pixel values near the edge of the detector behind the collimator leaves. The algorithm operates on the simple assumption that signal in the collimator shadow is attributable to x-ray scatter, and the 2D scatter fluence is estimated by interpolating between pixel values measured along the top and bottom edges of the detector behind the collimator leaves. The resulting scatter fluence estimate is subtracted from each projection to yield an estimate of the primary-only images for CBCT reconstruction. Performance was investigated in phantom experiments on an experimental CBCT benchtop, and the effect on image quality was demonstrated in patient images (head, abdomen, and pelvis sites) obtained on a preclinical system for CBCT-guided radiation therapy. The algorithm provides significant reduction in scatter artifacts without compromise in contrast-to-noise ratio (CNR). For example, in a head phantom, cupping artifact was essentially eliminated, CT number accuracy was restored to within 3%, and CNR (breast-to-water) was improved by up to 50%. Similarly in a body phantom, cupping artifact was reduced by at least a factor of 2 without loss in CNR. Patient images demonstrate significantly increased uniformity, accuracy, and contrast, with an overall improvement in image quality in all sites investigated. Qualitative evaluation illustrates that soft-tissue structures that are otherwise undetectable are clearly delineated in scatter-corrected reconstructions. Since scatter is estimated directly in each projection, the algorithm is robust with respect to system geometry, patient size and heterogeneity, patient motion, etc. Operating without prior information, analytical modeling

  18. Direct comparison of Fe-Cr unmixing characterization by atom probe tomography and small angle scattering

    Couturier, Laurent, E-mail: laurent.couturier55@hotmail.fr [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); CNRS, SIMAP, F-38000 Grenoble (France); Department of Materials Engineering, The University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); De Geuser, Frédéric; Deschamps, Alexis [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); CNRS, SIMAP, F-38000 Grenoble (France)

    2016-11-15

    The fine microstructure obtained by unmixing of a solid solution either by classical precipitation or spinodal decomposition is often characterized either by small angle scattering or atom probe tomography. This article shows that a common data analysis framework can be used to analyze data obtained from these two techniques. An example of the application of this common analysis is given for characterization of the unmixing of the Fe-Cr matrix of a 15-5 PH stainless steel during long-term ageing at 350 °C and 400 °C. A direct comparison of the Cr composition fluctuations amplitudes and characteristic lengths obtained with both techniques is made showing a quantitative agreement for the fluctuation amplitudes. The origin of the discrepancy remaining for the characteristic lengths is discussed. - Highlights: •Common analysis framework for atom probe tomography and small angle scattering •Comparison of same microstructural characteristics obtained using both techniques •Good correlation of Cr composition fluctuations amplitudes from both techniques •Good correlation of Cr composition fluctuations amplitudes with classic V parameter.

  19. Structure functions and final-state properties in deeply inelastic electron-proton scattering

    Kharraziha, H.

    1997-01-01

    In this thesis, we give a description of the detailed structure of the proton and a description of the final-state properties in electron-proton scattering. Qualitative results, in a purely gluonic scenario with the leading log approximation, and quantitative results, where quarks are included and some sub-leading corrections have been made, are presented. The quantitative results are in fair agreement with available experimental data and a Monte Carlo event generator for electron-proton scattering is presented. Further, a computer program for calculating QCD colour factors is presented

  20. Phonon scattering and thermal conductance properties in two coupled graphene nanoribbons modulated with bridge atoms

    Tan, Shi-Hua; Tang, Li-Ming; Chen, Ke-Qiu

    2014-01-01

    The phonon scattering and thermal conductance properties have been studied in two coupled graphene nanoribbons connected by different bridge atoms by using density functional theory in combination with non-equilibrium Green's function approach. The results show that a wide range of thermal conductance tuning can be realized by changing the chemical bond strength and atom mass of the bridge atoms. It is found that the chemical bond strength (bridge atom mass) plays the main role in phonon scattering at low (high) temperature. A simple equation is presented to describe the relationship among the thermal conductance, bridge atom, and temperature.

  1. Direct mapping of the angle-dependent barrier to reaction for Cl + CHD3 using polarized scattering data

    Pan, Huilin; Wang, Fengyan; Czakó, Gábor; Liu, Kopin

    2017-12-01

    The transition state, which gates and modulates reactive flux, serves as the central concept in our understanding of activated reactions. The barrier height of the transition state can be estimated from the activation energy taken from thermal kinetics data or from the energetic threshold in the measured excitation function (the dependence of reaction cross-sections on initial collision energies). However, another critical and equally important property, the angle-dependent barrier to reaction, has not yet been amenable to experimental determination until now. Here, using the benchmark reaction of Cl + CHD3(v1 = 1) as an example, we show how to map this anisotropic property of the transition state as a function of collision energy from the preferred reactant bond alignment of the backward-scattered products—the imprints of small impact-parameter collisions. The deduced bend potential at the transition state agrees with ab initio calculations. We expect that the method should be applicable to many other direct reactions with a collinear barrier.

  2. Tip-Enhanced Raman Scattering Microscopy: A Step toward Nanoscale Control of Intrinsic Molecular Properties

    Yano, Taka-aki; Hara, Masahiko

    2018-06-01

    Tip-enhanced Raman scattering microscopy, a family of scanning probe microscopy techniques, has been recognized as a powerful surface analytical technique with both single-molecule sensitivity and angstrom-scale spatial resolution. This review covers the current status of tip-enhanced Raman scattering microscopy in surface and material nanosciences, including a brief history, the basic principles, and applications for the nanoscale characterization of a variety of nanomaterials. The focus is on the recent trend of combining tip-enhanced Raman scattering microscopy with various external stimuli such as pressure, voltage, light, and temperature, which enables the local control of the molecular properties and functions and also enables chemical reactions to be induced on a nanometer scale.

  3. Comparative Analysis of Direct and Indirect Property Investment ...

    Sultan

    substitute for direct property investment in Abuja, Nigeria. The study .... of stock market investment using Lagos,. Ibadan and ... ordinary shares and saving account for the. Adeogun ... Hence, the need for this study which provides information.

  4. Computing the scattering properties of participating media using Lorenz-Mie theory

    Frisvad, Jeppe Revall; Christensen, Niels Jørgen; Jensen, Henrik Wann

    2007-01-01

    is capable of handling both absorbing host media and non-spherical particles, which significantly extends the classes of media and materials that can be modeled. We use the theory to compute optical properties for different types of ice and ocean water, and we derive a novel appearance model for milk...... parameterized by the fat and protein contents. Our results show that we are able to match measured scattering properties in cases where the classical Lorenz-Mie theory breaks down, and we can compute properties for media that cannot be measured using existing techniques in computer graphics....

  5. Multiple Property Cross Direction Control of Paper Machines

    Markku Ohenoja

    2011-07-01

    Full Text Available Cross direction (CD control in sheet-forming process forms a challenging problem with high dimensions. Accounting the interactions between different properties and actuators, the dimensionality increases further and also computational issues arise. We present a multiple property controller feasible to be used especially with imaging measurements that provide high sampling frequency and therefore enable short control interval. The simulation results state the benefits of multiple property CD control over single property control and single property control using full feedforward compensation. The controller presented may also be tuned in automated manner and the results demonstrate the effect of tuning on input saturation.

  6. Low-angle X-ray scattering properties of irradiated spices

    Almeida, A.P.G.; Braz, D.; Barroso, R.C.; Lopes, R.T.

    2007-01-01

    The scattering of X-rays at low angles (LAXS) is a technique dominated by the coherent scattering process. One characteristic observation of low-angle coherent scattering is the so-called molecular interference effect, being characterized by the presence of one or more peaks in the forward direction of scattering. In the present study, LAXS profiles from five different spices are carefully measured in order to establish characteristic scattering signatures. Samples of Ceylon cinnamon, cumin, nutmeg, paprika and black pepper were bought in local market in Rio de Janeiro, Brazil. The LAXS patterns were obtained using a Shimadzu DRX 6000 diffractometer in reflection geometry. Coherent scattering patterns are measured for the samples for θ=5-35 o . The data were collected in 0.05 o increments every 3 s. In order to evaluate the possible molecular structure changes caused to the irradiation procedure, the signatures obtained for control (non-irradiated) spices were compared with spice samples irradiated with different doses varying from 3 to 40 kGy. The LAXS patterns of all samples were obtained after 30, 60, 90, 120 days to evaluate the effect of storage period. Scattering profiles from spices irradiated with different irradiation doses were obtained and the results compared. For each spice, there is no considerable deviation in shape in function of the irradiation dose. It indicates that the molecular structure of each analyzed spices is preserved considering the dose range chosen. The results show that the molecular structure was found to be stable during storage at the ambient temperature for up to 4 months

  7. Label-free direct surface-enhanced Raman scattering (SERS) of nucleic acids (Conference Presentation)

    Guerrini, Luca; Morla-Folch, Judit; Gisbert-Quilis, Patricia; Xie, Hainan; Alvarez-Puebla, Ramon

    2016-03-01

    Recently, plasmonic-based biosensing has experienced an unprecedented level of attention, with a particular focus on the nucleic acid detection, offering efficient solutions to engineer simple, fast, highly sensitive sensing platforms while overcoming important limitations of PCR and microarray techniques. In the broad field of plasmonics, surface-enhanced Raman scattering (SERS) spectroscopy has arisen as a powerful analytical tool for detection and structural characterization of biomolecules. Today applications of SERS to nucleic acid analysis largely rely on indirect strategies, which have been demonstrated very effective for pure sensing purposes but completely dismiss the exquisite structural information provided by the direct acquisition of the biomolecular vibrational fingerprint. Contrarily, direct label-free SERS of nucleic acid shows an outstanding potential in terms of chemical-specific information which, however, remained largely unexpressed mainly because of the inherent poor spectral reproducibility and/or limited sensitivity. To address these limitations, we developed a fast and affordable high-throughput screening direct SERS method for gaining detailed genomic information on nucleic acids (DNA and RNA) and for the characterization and quantitative recognition of DNA interactions with exogenous agents. The simple strategy relies on the electrostatic adhesion of DNA/RNA onto positively-charged silver colloids that promotes the nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at picogram level (i.e. the analysis can be performed without the necessity of amplification steps thus providing realistic direct information of the nucleic acid in its native state). We anticipate this method to gain a vast impact and set of applications in different fields, including medical diagnostics, genomic screening, drug discovery, forensic science and even molecular electronics.

  8. An Investigation of Aerosol Scattering and Absorption Properties in Wuhan, Central China

    Wei Gong

    2015-04-01

    Full Text Available Aerosol scattering and absorption properties were continuously measured and analyzed at the urban Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing (LIESMARS site in Wuhan, central China, from 1 December 2009 to 31 March 2014. The mean aerosol scattering coefficient , absorption coefficient , and single scattering albedo (SSA were 377.54 Mm−1, 119.06 Mm−1, and 0.73, respectively. Both  and  showed obvious annual variability with large values in winter and small values in summer, principally caused by the annual characteristics of meteorological conditions, especially planetary boundary layer height (PBLH and local emissions. The SSA showed a slight annual variation. High values of SSA were related to formation of secondary aerosols in winter hazes and aerosol hygroscopic growth in humid summer. The large SSA in June can be attributed to the biomass combustion in Hubei and surrounding provinces. Both  and  showed double peak phenomena in diurnal variation resulting from the shallow stable PBLH at night and automobile exhaust emission during morning rush hours. The SSA also exhibited a double peak phenomenon related to the proportional variation of black carbon (BC and light scattering particulates in the day and night. The long-term exploration on quantified aerosol optical properties can help offer scientific basis of introducing timely environmental policies for local government.

  9. Indirect and direct measurement of thermal neutron acceleration by inelastic scattering on the 177Lu isomer

    Belier, G.; Roig, O.; Meot, V.; Daugas, J.M.; Aupiais, J.; Jutier, Ch.; Le Petit, G.; Veyssiere, Ch.

    2008-01-01

    When neutrons interact with isomers, these isomers can de-excite and in such a reaction the outgoing neutron has an energy greater than the in-going one. This process is referred as Inelastic Neutron Acceleration or Super-elastic Scattering. Up to now this process was observed for only two nucleus, 152m Eu and 180m Hf by measuring the number of fast neutrons produced by isomeric targets irradiated with thermal neutrons. In these experiments the energies of the accelerated neutrons were not measured. This report presents an indirect measurement of inelastic neutron acceleration on 177m Lu, based on the burn-up and the radiative capture cross sections measurements. Since at thermal energies the inelastic scattering and the radiative capture are the only processes that contribute to the isomer burn-up, the inelastic cross section can be deduced from the difference between the two measured quantities. Applying this method for the 177 Lu isomer with different neutron fluxes we obtained a value of (257 ± 50) barns (for a temperature of 323 K) and determined that there is no integral resonance for this process. In addition the radiative capture cross section on 177g Lu was measured with a much better accuracy than the accepted value. Since the acceleration cross section is quite high, a direct measurement of this process was undertaken, sending thermal neutrons and measuring the fast neutrons. The main goal now is to measure the outgoing neutron energies in order to identify the neutron transitions in the exit channel. In particular the K conservation question can be addressed by such a measurement. (author)

  10. Laser-induced stimulated Raman scattering in the forward direction of a droplet - Comparison of Mie theory with geometrical optics

    Srivastava, Vandana; Jarzembski, Maurice A.

    1991-01-01

    This paper uses Mie theory to treat electromagnetic scattering and to evaluate field enhancement in the forward direction of a small droplet irradiated by a high-energy beam and compares the results of calculations with the field-enhancement evaluation obtained via geometrical optics treatment. Results of this comparison suggest that the field enhancement located at the critical ring region encircling the axis in the forward direction of the droplet can support laser-induced Raman scattering. The results are supported by experimental observations of the interaction of a 120-micron-diam water droplet with a high-energy Nd:YAG laser beam.

  11. Structural and magnetic properties of transition metal substituted BaFe2As2 compounds studied by x-ray and neutron scattering

    Kim, Min Gyu [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    The purpose of my dissertation is to understand the structural and magnetic properties of the newly discovered FeAs-based superconductors and the interconnection between superconductivity, antiferromagnetism, and structure. X-ray and neutron scattering techniques are powerful tools to directly observe the structure and magnetism in this system. I used both x-ray and neutron scattering techniques on different transition substituted BaFe2As2 compounds in order to investigate the substitution dependence of structural and magnetic transitions and try to understand the connections between them.

  12. Characterization of conformational properties of protein/trehalose/water system by neutron scattering

    Brandt, A. [Hahn-Meitner-Institut, BENSC (NI), Glienicker Strasse, 14109 Berlin (Germany); Magazu' , S.; Mangione, A.; Migliardo, F. [Dipartimento di Fisica and INFM, Universita' di Messina, PO Box 55, 98166 Messina (Italy); Vertessy, B.G. [Institute of Enzymology, Hungarian Academy of Sciences, P. O. Box 7, 1518 Budapest (Hungary)

    2002-07-01

    In this contribution we report results of a small-angle neutron scattering (SANS) investigation of dUTPase/D{sub 2}O solutions. Data were collected by the V4 spectrometer at the BENSC facility (Berlin, Germany). The results allow us to characterize the conformational properties of the protein in solution as a function of temperature and in the presence of trehalose, a disaccharide with a noticeable bioprotective action. (orig.)

  13. Characterization of conformational properties of protein/trehalose/water system by neutron scattering

    Brandt, A; Mangione, A; Migliardo, F; Vertessy, B G

    2002-01-01

    In this contribution we report results of a small-angle neutron scattering (SANS) investigation of dUTPase/D sub 2 O solutions. Data were collected by the V4 spectrometer at the BENSC facility (Berlin, Germany). The results allow us to characterize the conformational properties of the protein in solution as a function of temperature and in the presence of trehalose, a disaccharide with a noticeable bioprotective action. (orig.)

  14. On the possibility of using X-ray Compton scattering to study magnetoelectrical properties of crystals

    Collins, S. P., E-mail: steve.collins@diamond.ac.uk; Laundy, D.; Connolley, T.; Laan, G. van der; Fabrizi, F. [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE (United Kingdom); Janssen, O. [Department of Physics, New York University, New York, NY 10003 (United States); Cooper, M. J. [Department of Physics, University of Warwick, CV4 7AL (United Kingdom); Ebert, H.; Mankovsky, S. [Universität München, Department Chemie, Haus E2.033, Butenandtstrasse 5-13, D-81377 München (Germany)

    2016-02-16

    The possibility of using X-ray Compton scattering to reveal antisymmetric components of the electron momentum density, as a fingerprint of magnetoelectric sample properties, is investigated experimentally and theoretically by studying the polar ferromagnet GaFeO{sub 3}. This paper discusses the possibility of using Compton scattering – an inelastic X-ray scattering process that yields a projection of the electron momentum density – to probe magnetoelectrical properties. It is shown that an antisymmetric component of the momentum density is a unique fingerprint of such time- and parity-odd physics. It is argued that polar ferromagnets are ideal candidates to demonstrate this phenomenon and the first experimental results are shown, on a single-domain crystal of GaFeO{sub 3}. The measured antisymmetric Compton profile is very small (≃ 10{sup −5} of the symmetric part) and of the same order of magnitude as the statistical errors. Relativistic first-principles simulations of the antisymmetric Compton profile are presented and it is shown that, while the effect is indeed predicted by theory, and scales with the size of the valence spin–orbit interaction, its magnitude is significantly overestimated. The paper outlines some important constraints on the properties of the antisymmetric Compton profile arising from the underlying crystallographic symmetry of the sample.

  15. The effect of roughness model on scattering properties of ice crystals

    Geogdzhayev, Igor; Diedenhoven, Bastiaan van

    2016-01-01

    We compare stochastic models of microscale surface roughness assuming uniform and Weibull distributions of crystal facet tilt angles to calculate scattering by roughened hexagonal ice crystals using the geometric optics (GO) approximation. Both distributions are determined by similar roughness parameters, while the Weibull model depends on the additional shape parameter. Calculations were performed for two visible wavelengths (864 nm and 410 nm) for roughness values between 0.2 and 0.7 and Weibull shape parameters between 0 and 1.0 for crystals with aspect ratios of 0.21, 1 and 4.8. For this range of parameters we find that, for a given roughness level, varying the Weibull shape parameter can change the asymmetry parameter by up to about 0.05. The largest effect of the shape parameter variation on the phase function is found in the backscattering region, while the degree of linear polarization is most affected at the side-scattering angles. For high roughness, scattering properties calculated using the uniform and Weibull models are in relatively close agreement for a given roughness parameter, especially when a Weibull shape parameter of 0.75 is used. For smaller roughness values, a shape parameter close to unity provides a better agreement. Notable differences are observed in the phase function over the scattering angle range from 5° to 20°, where the uniform roughness model produces a plateau while the Weibull model does not. - Highlights: • We compare scattering by hexagonal crystals for uniform and Weibull roughness models. • The Weibull shape parameter has a stronger effect on the phase function at backscattering. • DoLP is mostly affected at the side-scattering angles. • For high roughness, the two models are in relatively close agreement for a given roughness. • A plateau from 5° to 20° is observed in the phase function when using the uniform model.

  16. Optimal numerical methods for determining the orientation averages of single-scattering properties of atmospheric ice crystals

    Um, Junshik; McFarquhar, Greg M.

    2013-01-01

    The optimal orientation averaging scheme (regular lattice grid scheme or quasi Monte Carlo (QMC) method), the minimum number of orientations, and the corresponding computing time required to calculate the average single-scattering properties (i.e., asymmetry parameter (g), single-scattering albedo (ω o ), extinction efficiency (Q ext ), scattering efficiency (Q sca ), absorption efficiency (Q abs ), and scattering phase function at scattering angles of 90° (P 11 (90°)), and 180° (P 11 (180°))) within a predefined accuracy level (i.e., 1.0%) were determined for four different nonspherical atmospheric ice crystal models (Gaussian random sphere, droxtal, budding Bucky ball, and column) with maximum dimension D=10μm using the Amsterdam discrete dipole approximation at λ=0.55, 3.78, and 11.0μm. The QMC required fewer orientations and less computing time than the lattice grid. The calculations of P 11 (90°) and P 11 (180°) required more orientations than the calculations of integrated scattering properties (i.e., g, ω o , Q ext , Q sca , and Q abs ) regardless of the orientation average scheme. The fewest orientations were required for calculating g and ω o . The minimum number of orientations and the corresponding computing time for single-scattering calculations decreased with an increase of wavelength, whereas they increased with the surface-area ratio that defines particle nonsphericity. -- Highlights: •The number of orientations required to calculate the average single-scattering properties of nonspherical ice crystals is investigated. •Single-scattering properties of ice crystals are calculated using ADDA. •Quasi Monte Carlo method is more efficient than lattice grid method for scattering calculations. •Single-scattering properties of ice crystals depend on a newly defined parameter called surface area ratio

  17. Direct simulation Monte Carlo ray tracing model of light scattering by a class of real particles and comparison with PROGRA2 experimental results

    Mikrenska, M.; Koulev, P.; Renard, J.-B.; Hadamcik, E.; Worms, J.-C.

    2006-01-01

    The Direct Simulation Monte Carlo (DSMC) model is presented for three-dimensional single scattering of natural light by suspended, randomly oriented, optically homogeneous and isotropic, rounded and stochastically rough cubic particles. The modelled particles have large size parameter that allows geometric optics approximation to be used. The proposed computational model is simple and flexible. It is tested by comparison with known geometric optics solution for a perfect cube and Lorenz-Mie solution for a sphere, as extreme cases of the class of rounded cubes. Scattering and polarization properties of particles with various geometrical and optical characteristics are examined. The experimental study of real NaCl crystals with new Progra 2 instrument in microgravity conditions is conducted. The experimental and computed polarization and brightness phase curves are compared

  18. Microstructure and mechanical property of dual-directional-extruded Mg alloy AZ31

    Lu Liwei; Liu Tianmo; Jiang Shan; Pan Fushen; Liu Qing; Wang Zhongchang

    2010-01-01

    We report microstructure evolution and mechanical property of Mg alloy AZ31 processed by a new deformation technique, dual-directional extrusion (DDE). Using optical microscopy, scanning electron microscopy, and electron back scatter diffraction technique, we attribute the significant refinement of original coarse grains in the DDE-processed alloy to the occurrence of dynamic recrystallization. Moreover, we find that low temperature is crucial for yielding fine grain, which consequently results in high micro-hardness and yield stress, large fracture strain, and enhanced elongation. The improved mechanical properties are comparable or even superior to those of the alloy subjected to other deformation techniques, rendering the DDE a promising way for further tailoring properties of Mg-based alloys.

  19. Monte Carlo evaluation of accuracy and noise properties of two scatter correction methods

    Narita, Y.; Eberl, S.; Nakamura, T.

    1996-01-01

    Two independent scatter correction techniques, transmission dependent convolution subtraction (TDCS) and triple-energy window (TEW) method, were evaluated in terms of quantitative accuracy and noise properties using Monte Carlo simulation (EGS4). Emission projections (primary, scatter and scatter plus primary) were simulated for 99m Tc and 201 Tl for numerical chest phantoms. Data were reconstructed with ordered-subset ML-EM algorithm including attenuation correction using the transmission data. In the chest phantom simulation, TDCS provided better S/N than TEW, and better accuracy, i.e., 1.0% vs -7.2% in myocardium, and -3.7% vs -30.1% in the ventricular chamber for 99m Tc with TDCS and TEW, respectively. For 201 Tl, TDCS provided good visual and quantitative agreement with simulated true primary image without noticeably increasing the noise after scatter correction. Overall TDCS proved to be more accurate and less noisy than TEW, facilitating quantitative assessment of physiological functions with SPECT

  20. Direct measurement of the cross section of neutron-neutron scattering at the YAGUAR reactor. Substantiation of the experiment technique

    Chernukhin, Yu.G.; Kandiev, Ya.Z.; Lartsev, V.D.; Levakov, B.G.; Modestov, D.G.; Simonenko, V.A.; Streltsov, S.I.; Khmel'nitskij, D.V.

    2006-01-01

    The main stage of experiment for direct measurement of cross section of neutron-neutron scattering σ nn at low energies (E nn determination. It was shown, that for achieving the criterion ε ∼ 4% it will be necessary to have 40-50 pulses of a reactor [ru

  1. Preliminary laboratory studies of the optical scattering properties of the crystal clouds

    C. Saunders

    Full Text Available Ice crystal clouds have an influence on the radiative budget of the earth; however, the exact size and nature of this influence has yet to be determined. A laboratory cloud chamber experiment has been set up to provide data on the optical scattering behaviour of ice crystals at a visible wavelength in order to gain information which can be used in climate models concerning the radiative characteristics of cirrus clouds. A PMS grey-scale probe is used to monitor simultaneously the cloud microphysical properties in order to correlate these closely with the observed radiative properties. Preliminary results show that ice crystals scatter considerably more at 90° than do water droplets, and that the halo effects are visible in a laboratory-generated cloud when the ice crystal concentration is sufficiently small to prevent masking from multiple scattering.

    Key words. Meteorology and atmosphere dynamics · Climatology · Radiative process · Atmospheric composition and structure · Cloud physics and chemistry

  2. Light scattering and absorption properties of dust particles retrieved from satellite measurements

    Hu, R.-M.; Sokhi, R.S.

    2009-01-01

    We use the radiative transfer model and chemistry transport model to improve our retrievals of dust optical properties from satellite measurements. The optical depth and absorbing optical depth of mineral dust can be obtained from our improved retrieval algorithm. We find the nonsphericity and absorption of dust particles strongly affect the scattering signatures such as phase function and polarization at the ultraviolet wavelengths. From our retrieval results, we find the high levels of dust concentration occurred over most desert regions such as Saharan and Gobi deserts. The dust absorption is found to be sensitive to mineral chemical composition, particularly the fraction of strongly absorbing dust particles. The enhancement of polarization at the scattering angles exceeding 120 0 is found for the nonspherical dust particles. If the polarization is neglected in the radiative transfer calculation, a maximum 50 percent error is introduced for the case of forward scattering and 25 percent error for the case of backscattering. We suggest that the application of polarimeter at the ultraviolet wavelengths has the great potential to improve the satellite retrievals of dust properties. Using refined optical model and radiative transfer model to calculate the solar radiative forcing of dust aerosols can reduce the uncertainties in aerosol radiative forcing assessment.

  3. Non-Directional Radiation Spread Modeling and Non-Invasive Estimating the Radiation Scattering and Absorption Parameters in Biological Tissue

    S. Yu. Makarov

    2015-01-01

    Full Text Available The article dwells on a development of new non-invasive measurement methods of optical parameters of biological tissues, which are responsible for the scattering and absorption of monochromatic radiation. It is known from the theory of radiation transfer [1] that for strongly scattering media, to which many biological tissues pertain, such parameters are parameters of diffusion approximation, as well as a scattering coefficient and an anisotropy parameter.Based on statistical modeling the paper examines a spread of non-directional radiation from a Lambert light beam with the natural polarization that illuminates a surface of the biological tissue. Statistical modeling is based on the Monte Carlo method [2]. Thus, to have the correct energy coefficient values of Fresnel reflection and transmission in simulation of such radiation by Monte Carlo method the author uses his finding that is a function of the statistical representation for the incidence of model photons [3]. The paper describes in detail a principle of fixing the power transmitted by the non-directional radiation into biological tissue [3], and the equations of a power balance in this case.Further, the paper describes the diffusion approximation of a radiation transfer theory, often used in simulation of radiation propagation in strongly scattering media and shows its application in case of fixing the power transmitted into the tissue. Thus, to represent an uneven power distribution is used an approximating expression in conditions of fixing a total input power. The paper reveals behavior peculiarities of solution on the surface of the biological tissue inside and outside of the incident beam. It is shown that the solution in the region outside of the incident beam (especially far away from it, essentially, depends neither on the particular power distribution across the surface, being a part of the tissue, nor on the refractive index of the biological tissue. It is determined only by

  4. Microwave single-scattering properties of randomly oriented soft-ice hydrometeors

    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.

  5. Properties of a new magnetic dipole mode discovered in low energy electron scattering

    Bohle, D.; Guhr, T.; Hartmann, U.; Hummel, K.D.; Kilgus, G.; Milkau, U.; Richter, A.

    1986-01-01

    In a large range of nuclei low lying J π =1 + states have been found that are excited predominantly by a new M1 mode. Four properties of the new mode will be discussed in detail. Firstly, from the excitation energy systematics observed the strength of the Majorana force of the interacting boson model (IBA) is deduced. Secondly, through the comparison of electron scattering and proton scattering experiments it is shown that the new mode is largely due to the orbital motion of protons with respect to neutrons. Thirdly, taking the nucleus 164 Dy as an example, g-factors and effective boson charges of the M1-, E2- and M3 IBA transition operators, respectively, are studied. The F-scalar magnetic octupol g-factor Ω S is derived for the first time. Finally, the distribution of M1 strength in 156 Gd will be discussed in the light of recent theoretical calculations. (orig.)

  6. Quantitative analysis of optical properties of flowing blood using a photon-cell interactive Monte Carlo code: effects of red blood cells' orientation on light scattering.

    Sakota, Daisuke; Takatani, Setsuo

    2012-05-01

    Optical properties of flowing blood were analyzed using a photon-cell interactive Monte Carlo (pciMC) model with the physical properties of the flowing red blood cells (RBCs) such as cell size, shape, refractive index, distribution, and orientation as the parameters. The scattering of light by flowing blood at the He-Ne laser wavelength of 632.8 nm was significantly affected by the shear rate. The light was scattered more in the direction of flow as the flow rate increased. Therefore, the light intensity transmitted forward in the direction perpendicular to flow axis decreased. The pciMC model can duplicate the changes in the photon propagation due to moving RBCs with various orientations. The resulting RBC's orientation that best simulated the experimental results was with their long axis perpendicular to the direction of blood flow. Moreover, the scattering probability was dependent on the orientation of the RBCs. Finally, the pciMC code was used to predict the hematocrit of flowing blood with accuracy of approximately 1.0 HCT%. The photon-cell interactive Monte Carlo (pciMC) model can provide optical properties of flowing blood and will facilitate the development of the non-invasive monitoring of blood in extra corporeal circulatory systems.

  7. Some results on inverse scattering

    Ramm, A.G.

    2008-01-01

    A review of some of the author's results in the area of inverse scattering is given. The following topics are discussed: (1) Property C and applications, (2) Stable inversion of fixed-energy 3D scattering data and its error estimate, (3) Inverse scattering with 'incomplete' data, (4) Inverse scattering for inhomogeneous Schroedinger equation, (5) Krein's inverse scattering method, (6) Invertibility of the steps in Gel'fand-Levitan, Marchenko, and Krein inversion methods, (7) The Newton-Sabatier and Cox-Thompson procedures are not inversion methods, (8) Resonances: existence, location, perturbation theory, (9) Born inversion as an ill-posed problem, (10) Inverse obstacle scattering with fixed-frequency data, (11) Inverse scattering with data at a fixed energy and a fixed incident direction, (12) Creating materials with a desired refraction coefficient and wave-focusing properties. (author)

  8. A study on the directional dependence of scatter ray in radiography

    Oh, Hyun Joo; Kim, Sung Soo; Kim, Young Il; Lee, Who Min; Kim, Hak Sung; Lim, Han Young; Kim, Heung Tae; Lee, Sang Suk

    1995-01-01

    In this papper, the back, forward, side and 45 .deg. oblique scatter dose were measured the X-ray exposure conditions 60, 80, 100, 120 kV, FFD 100 cm, FS 20 x 20 cm, toward the 25 x 25cm x 10 ∼ 20cm of solid water, paraffin and MiX-DP phantom, and Pb, Cu, AI, and styrofoam materials, by the electrometer and 5.3 cc ionization chamber. The obtained results are summarized as following. 1. The percentage depth dose(PDD) at the range of the diagnostic x-ray energy were appeared 50 % depth dose at the 2 cm depth with 60 kV, and 5 cm depth with 120 kV X-ray, 10 % depth dose at the 10 cm depth with 60 kV and 14 cm depth with 120 kV X-ray, 5 % below depth dose at the 20 cm depth. 2. The back scatter dose which were generated the surface of Pb, Cu and Al metal plates were 10 % below, and than the back scatter dose at the Pb plate were a most amount of these which were about 10 %, and were appeared the order of Cu and AI. 3. The percentage forward scatter were appeared from 50 % to 65 %, and the more phantom thickness become, the more forward scatter were increased with the ratio of 5 % per 5 cm thickness. 4. The percentage back scatter which were generated the tissue equivalence materials solid water, paraffin and MiX-DP were from 20 % to 40 %, and than the back scatter dose at the solid water were a mast amount of those, and paraffin and MiX-DP were appeared with the next values. 5. The percentage 90 .deg. lateral and 45 .deg. oblique side scatter dose were measured from 4 % to 12 %. a most amount of scatter dose which were generated from the patient in radiography were the forward scatter, the next values were the back scatter, the third values were the 90 .deg. lateral scatter

  9. Study of mode-converted and directly-excited ion Bernstein waves by CO2 laser scattering in Alcator C

    Takase, Y.; Fiore, C.L.; McDermott, F.S.; Moody, J.D.; Porkolab, M.; Shepard, T.; Squire, J.

    1987-01-01

    Mode-converted and directly excited ion Bernstein waves (IBW) were studied using CO 2 laser scattering in the Alcator C tokamak. During the ICRF fast wave heating experiments, mode-converted IBW was observed on the high-field side of the resonance in both second harmonic and minority heating regimes. By comparing the relative scattered powers from the two antennas separated by 180 0 toroidally, an increased toroidal wave damping with increasing density was inferred. In the IBW heating experiments, optimum direct excitation is obtained when an ion-cyclotron harmonic layer is located just behind the antenna. Wave absorption at the ω = 3Ω/sub D/ = 1.5Ω/sub H/ layer was directly observed. Edge ion heating was inferred from the IBW dispersion when this absorption layer was located in the plasma periphery, which may be responsible for the observed improvement in particle confinement

  10. Direct compression properties of microcrystalline cellulose and its ...

    The influence of silicified microcrystalline cellulose (SMCC) on the flow, compaction and tableting properties of metronidazole powder was investigated. The study compared medium grades of both SMCC and standard microcrystalline cellulose (MCC) as direct compressible excipients. The bulk densities, Hausner quotient ...

  11. Direct detection of near-surface faults by migration of back-scattered surface waves

    Yu, Han; Guo, Bowen; Hanafy, Sherif; Lin, Fan-Chi; Schuster, Gerard T.

    2014-01-01

    We show that diffraction stack migration can be used to estimate the distribution of near-surface faults. The assumption is that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. The processing steps

  12. Nanometer-range atomic order directly recovered from resonant diffuse scattering

    Kopecký, Miloš; Kub, Jiří; Fábry, Jan; Hlinka, Jiří

    2016-01-01

    Roč. 93, č. 5 (2016), 1-8, č. článku 054202. ISSN 1098-0121 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : diffuse scattering * resonant scattering * atomic structure * perovskites * relaxors * PbMg 1/3 Nb 2/3 O 3 (PMN) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  13. Factorization properties and spurious solutions in N-body scattering theories

    Vanzani, V.

    1979-01-01

    The origin of spurious solutions in N-body scattering equations is discussed. It is shown that spurious solutions are expected because of specific factorization properties of the homogeneous equations. The equations proposed by Rosenberg, by Mitra, Gillespie, Sugar and Panchapakesan, by Takahashi and Mishima, by Alessandrini, by Sasakawa, by Sloan, Bencze and Redish, by Weinberg and van Winter and by Avishai are considered. It is explicitly shown that spurious multipliers arise from repeated employment of resolvent equations or, equiValently, from generalized iteration procedure

  14. An experimental and numerical study of the light scattering properties of ice crystals with black carbon inclusions

    Arienti, Marco; Geier, Manfred; Yang, Xiaoyuan; Orcutt, John; Zenker, Jake; Brooks, Sarah D.

    2018-05-01

    We investigate the optical properties of ice crystals nucleated on atmospheric black carbon (BC). The parameters examined in this study are the shape of the ice crystal, the volume fraction of the BC inclusion, and its location inside the crystal. We report on new spectrometer measurements of forward scattering and backward polarization from ice crystals nucleated on BC particles and grown under laboratory-controlled conditions. Data from the Cloud and Aerosol Spectrometer with Polarization (CASPOL) are used for direct comparison with single-particle calculations of the scattering phase matrix. Geometrical optics and discrete dipole approximation techniques are jointly used to provide the best compromise of flexibility and accuracy over a broad range of size parameters. Together with the interpretation of the trends revealed by the CASPOL measurements, the numerical results confirm previous reports on absorption cross-section magnification in the visible light range. Even taking into account effects of crystal shape and inclusion position, the ratio between absorption cross-section of the compound particle and the absorption cross-section of the BC inclusion alone (the absorption magnification) has a lower bound of 1.5; this value increases to 1.7 if the inclusion is centered with respect to the crystal. The simple model of BC-ice particle presented here also offers new insights on the effect of the relative position of the BC inclusion with respect to the crystal's outer surfaces, the shape of the crystal, and its size.

  15. Laboratory studies of the growth, sublimation, and light- scattering properties of single levitated ice particles

    Bacon, Neil Julian

    2001-12-01

    I describe experiments to investigate the properties of microscopic ice particles. The goal of the work was to measure parameters that are important in cloud processes and radiative transfer, using a novel technique that avoids the use of substrates. The experiments were conducted in two separate electrodynamic balance chambers. Single, charged ice particles were formed from frost particles or from droplets frozen either homogeneously or heteroge neously with a bionucleant. The particles were trapped at temperatures between -38°C and -4°C and grown or sublimated according to the temperature gradient in the cham ber. I describe observations of breakup of sublimating frost particles, measurements of light scattering by hexagonal crystals, and observations of the morphology of ice particles grown from frozen water droplets and frost particles. The breaking strength of frost particles was an order of magnitude less than that of bulk ice. Light scattering features not previously observed were analyzed and related to crystal dimension. Initial results from a computer model failed to reproduce these features. The widths of scattering peaks suggest that surface roughness may play a role in determining the angular distribution of scattered light. Ice particle mass evolution was found to be consistent with diffusion- limited growth. Crystals grown slowly from frozen droplets adopted isometric habits, while faster growth resulted in thin side-planes, although there was not an exact correspondence between growth conditions and particle morphology. From the morphological transition, I infer lower limits for the critical supersaturation for layer nucleation on the prism face of 2.4% at -15°C, 4.4% at -20°C, and 3.1% at -25°C. Analytic expressions for the size dependence of facet stability are developed, indicating a strong dependence of stability on both crystal size and surface kinetics, and compared with data. I discuss the role of complex particle morphologies in

  16. Direct detection of near-surface faults by migration of back-scattered surface waves

    Yu, Han

    2014-08-05

    We show that diffraction stack migration can be used to estimate the distribution of near-surface faults. The assumption is that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. The processing steps are to isolate the back-scattered surface waves, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. A deconvolution filter derived from the data can be used to collapse a dispersive arrival into a non-dispersive event. Results with synthetic data and field records validate the feasibility of this method. Applying this method to USArray data or passively recorded exploration data might open new opportunities in mapping tectonic features over the extent of the array.

  17. Direct measurement of the Rayleigh scattering cross section in various gases

    Sneep, Maarten; Ubachs, Wim

    2005-01-01

    Using the laser-based technique of cavity ring-down spectroscopy extinction measurements have been performed in various gases straightforwardly resulting in cross sections for Rayleigh scattering. For Ar and N 2 measurements are performed in the range 470-490nm, while for CO 2 cross sections are determined in the wider range 470-570nm. In addition to these gases also for N 2 O, CH 4 , CO, and SF 6 the scattering cross section is determined at 532nm, a wavelength of importance for lidar applications and combustion laser diagnostics. In O 2 the cross section at 532nm is found to depend on pressure due to collision-induced light absorption. The obtained cross sections validate the cross sections for Rayleigh scattering as derived from refractive indices and depolarization ratios through Rayleigh's theory at the few %-level, although somewhat larger discrepancies are found for CO, N 2 O and CH 4

  18. Measurement of illite particle thickness using a direct Fourier transform of small-angle X-ray scattering data

    Shang, Chao; Rice, James A.; Eberl, Dennis D.; Lin, Jar-Shyong

    2003-01-01

    It has been suggested that interstratified illite-smectite (I-S) minerals are composed of aggregates of fundamental particles. Many attempts have been made to measure the thickness of such fundamental particles, but each of the methods used suffers from its own limitations and uncertainties. Small-angle X-ray scattering (SAXS) can be used to measure the thickness of particles that scatter X-rays coherently. We used SAXS to study suspensions of Na-rectorite and other illites with varying proportions of smectite. The scattering intensity (I) was recorded as a function of the scattering vector, q = (4 /) sin(/2), where  is the X-ray wavelength and  is the scattering angle. The experimental data were treated with a direct Fourier transform to obtain the pair distance distribution function (PDDF) that was then used to determine the thickness of illite particles. The Guinier and Porod extrapolations were used to obtain the scattering intensity beyond the experimental q, and the effects of such extrapolations on the PDDF were examined. The thickness of independent rectorite particles (used as a reference mineral) is 18.3 Å. The SAXS results are compared with those obtained by X-ray diffraction peak broadening methods. It was found that the power-law exponent (α) obtained by fitting the data in the region of q = 0.1-0.6 nm-1 to the power law (I = I0q-α) is a linear function of illite particle thickness. Therefore, illite particle thickness could be predicted by the linear relationship as long as the thickness is within the limit where α <4.0.

  19. Absolute Negative Resistance Induced by Directional Electron-Electron Scattering in a Two-Dimensional Electron Gas

    Kaya, Ismet I.; Eberl, Karl

    2007-05-01

    A three-terminal device formed by two electrostatic barriers crossing an asymmetrically patterned two-dimensional electron gas displays an unusual potential depression at the middle contact, yielding absolute negative resistance. The device displays momentum and current transfer ratios that far exceed unity. The observed reversal of the current or potential in the middle terminal can be interpreted as the analog of Bernoulli’s effect in a Fermi liquid. The results are explained by directional scattering of electrons in two dimensions.

  20. Diffusion properties of active particles with directional reversal

    Großmann, R; Bär, M; Peruani, F

    2016-01-01

    The diffusion properties of self-propelled particles which move at constant speed and, in addition, reverse their direction of motion repeatedly are investigated. The internal dynamics of particles triggering these reversal processes is modeled by a stochastic clock. The velocity correlation function as well as the mean squared displacement is investigated and, furthermore, a general expression for the diffusion coefficient for self-propelled particles with directional reversal is derived. Our analysis reveals the existence of an optimal, finite rotational noise amplitude which maximizes the diffusion coefficient. We comment on the relevance of these results with regard to biological systems and suggest further experiments in this context. (paper)

  1. The matrix element for radiative Bhabha scattering in the forward direction

    Kleiss, R.

    1993-09-01

    We present an approximation to the matrix element for the process e + e - →e + e - γ, appropriate to the situation where one or both of the fermions are scattered over very small angles. The leading terms in the situation where all scattering angles are small contains not only terms quadratic in the electron mass, but also quartic and even sextic terms must be included. Special attention is devoted to the numerical stability of the resultant expression. Its relation to several existing formulae is discussed. (orig.)

  2. A database of microwave and sub-millimetre ice particle single scattering properties

    Ekelund, Robin; Eriksson, Patrick

    2016-04-01

    Ice crystal particles are today a large contributing factor as to why cold-type clouds such as cirrus remain a large uncertainty in global climate models and measurements. The reason for this is the complex and varied morphology in which ice particles appear, as compared to liquid droplets with an in general spheroidal shape, thus making the description of electromagnetic properties of ice particles more complicated. Single scattering properties of frozen hydrometers have traditionally been approximated by representing the particles as spheres using Mie theory. While such practices may work well in radio applications, where the size parameter of the particles is generally low, comparisons with measurements and simulations show that this assumption is insufficient when observing tropospheric cloud ice in the microwave or sub-millimetre regions. In order to assist the radiative transfer and remote sensing communities, a database of single scattering properties of semi-realistic particles is being produced. The data is being produced using DDA (Discrete Dipole Approximation) code which can treat arbitrarily shaped particles, and Tmatrix code for simpler shapes when found sufficiently accurate. The aim has been to mainly cover frequencies used by the upcoming ICI (Ice Cloud Imager) mission with launch in 2022. Examples of particles to be included are columns, plates, bullet rosettes, sector snowflakes and aggregates. The idea is to treat particles with good average optical properties with respect to the multitude of particles and aggregate types appearing in nature. The database will initially only cover macroscopically isotropic orientation, but will eventually also include horizontally aligned particles. Databases of DDA particles do already exist with varying accessibility. The goal of this database is to complement existing data. Regarding the distribution of the data, the plan is that the database shall be available in conjunction with the ARTS (Atmospheric

  3. Opalescence and fluorescence properties of indirect and direct resin materials.

    Song, Sang-Hoon; Yu, Bin; Ahn, Jin-Soo; Lee, Yong-Keun

    2008-08-01

    To measure the opalescence and fluorescence properties of indirect and direct resin materials before and after polymerization, and to determine the influence of the material and shade group combination on these properties. BelleGlass NG (BG, indirect resin) and Estelite Sigma (ES, direct resin), each composed in 3 shade groups (EN, OD and TL for BG; BS, AS and OP for ES) out of a total of 16 shades were investigated. Resin material was packed into a mold (the BEC condition) and polymerized with a light-polymerization unit (CWL). Secondary polymerization (CIC) was performed for BG. Color was measured in the BEC, CWL, and CIC conditions, and the opalescence parameter (OP) and fluorescence parameter (FL) were calculated. For the OP, the mean for BG material was 24.3 before polymerization, which changed to 19.9 after polymerization (CIC). In the case of ES, the mean OP before polymerization was 25.6, which changed to 12.4 after polymerization (CWL). For the FL, the mean FL for BG was 2.5 before polymerization, which changed to 0.7 after polymerization. In the case of ES, the mean FL before polymerization was 1.2, which did not change after polymerization. Material and shade group combination influenced the OP and FL values (popalescence and fluorescence properties of resin materials varied depending on the material, shade group, and polymerization. Clinically, these properties should be considered when neighboring teeth are restored with different types of material.

  4. Direct time integration of Maxwell's equations in linear dispersive media with absorption for scattering and propagation of femtosecond electromagnetic pulses

    Joseph, Rose M.; Hagness, Susan C.; Taflove, Allen

    1991-01-01

    The initial results for femtosecond pulse propagation and scattering interactions for a Lorentz medium obtained by a direct time integration of Maxwell's equations are reported. The computational approach provides reflection coefficients accurate to better than 6 parts in 10,000 over the frequency range of dc to 3 x 10 to the 16th Hz for a single 0.2-fs Gaussian pulse incident upon a Lorentz-medium half-space. New results for Sommerfeld and Brillouin precursors are shown and compared with previous analyses. The present approach is robust and permits 2D and 3D electromagnetic pulse propagation directly from the full-vector Maxwell's equations.

  5. Can listed property shares be a surrogate for direct property investment behaviour?

    Douw Boshoff

    2012-03-01

    Full Text Available The listed property sector in South Africa has grown to a size which could be considered to be a good representation of the income producing property market in general. Stock market listed property investment funds offer the opportunity to compare indirect property investment to direct property investment, which could bridge the gap between irrational investment behaviour and intrinsic asset values. This study investigates the relationship between listed property share prices and the property values in listed property funds. The share prices are correlated with various factors, such as the accounting ratios of the companies, the financial statements of the companies and general economic variables. The outcome of the study is an explanation of the behaviour of listed property shares, and its relationship to the direct property market and the general economy. This would assist in the explanation of market behaviour and provides the opportunity to more accurately predict portfolio asset values, which might be used in the valuation of individual real estate assets.

  6. Assembly of gamma radiation detection with directivity properties

    Stoica, M.; Talpalariu, C.

    2016-01-01

    An assembly of gamma radiation detection with directivity properties and small size enables the development of portable equipment or robots specialized in finding and signaling radioactively contaminated areas in case of nuclear incidents or decommissioning of nuclear installations. Directivity characteristic of the assembly of gamma radiation detection is very important when aiming to build an equipment for searching radioactively contaminated areas. In order to obtain a suitable directivity characteristics in terms of detection of gamma rays, it was necessary to construct a lead collimator with a cylindrical shape. The detector, preamplifier and amplifier pulse were placed inside the collimator and pulse discriminator circuit and power source were placed beside the collimator, all being disposed within the housing cylindrical experimental. A PIN photodiode type was used as a detector of gamma radiation. (authors)

  7. A theoretical and numerical study of polarimetric scattering and emission from random rough surfaces with anisotropic directional spectrum

    Yueh, S. H.; Kwok, R.

    1993-01-01

    In this paper, theoretical and numerical results of the polarimetric scattering and emission from random rough surfaces with anisotropic directional spectrum are presented for the remote sensing of ocean and soil surfaces. The polarimetric scattered field for rough dielectric surfaces is derived to the second order by the small perturbation method (SPM). It is found that the second-order scattered field is coherent in nature, and its coefficients for different polarizations present the lowest-order corrections to the Fresnel reflection coefficients of the surfaces. In addition, the cross-polarized (HV and VH) components of the coherent fields are reciprocal and not zero for surfaces with anisotropic directional spectrum when the azimuth angle of the incident direction is not aligned with the symmetry directions of surfaces. In order to verify the energy conservation condition of the theoretical results, which is important if the theory is to be applied to the passive polarimetry of rough surfaces, a Monte Carlo simulation is performed to numerically calculate the polarimetric reflectivities of one-dimensional random rough surfaces which are generated with a prescribed power-law spectrum in the spectral domain and transformed to the spatial domain by the FFT. The surfaces simulated by this approach are periodic with the period corresponding to the low-wavenumber cutoff. To calculate the scattering from periodic dielectric surfaces, the authors present a new numerical technique which applies the Floquet theorem to reduce the problem to one period and does not require the evaluation of one-dimensional periodic Green's function used in the conventional method of moment formulation. Once the scattering coefficients are obtained, the polarimetric Stokes vectors for the emission from the random surfaces are then calculated according to the Kirchhoff's law and are illustrated as functions of relative azimuth observation and row directions. The second-order SPM is also

  8. Solution processed zinc oxide nanopyramid/silver nanowire transparent network films with highly tunable light scattering properties

    Mehra, Saahil

    2013-01-01

    Metal nanowire transparent networks are promising replacements to indium tin oxide (ITO) transparent electrodes for optoelectronic devices. While the transparency and sheet resistance are key metrics for transparent electrode performance, independent control of the film light scattering properties is important to developing multifunctional electrodes for improved photovoltaic absorption. Here we show that controlled incorporation of ZnO nanopyramids into a metal nanowire network film affords independent, highly tunable control of the scattering properties (haze) with minimal effects on the transparency and sheet resistance. Varying the zinc oxide/silver nanostructure ratios prior to spray deposition results in sheet resistances, transmission (600 nm), and haze (600 nm) of 6-30 Ω □-1, 68-86%, and 34-66%, respectively. Incorporation of zinc oxide nanopyramid scattering agents into the conducting nanowire mesh has a negligible effect on mesh connectivity, providing a straightforward method of controlling electrode scattering properties. The decoupling of the film scattering power and electrical characteristics makes these films promising candidates for highly scattering transparent electrodes in optoelectronic devices and can be generalized to other metal nanowire films as well as carbon nanotube transparent electrodes. © 2013 The Royal Society of Chemistry.

  9. Size-dependent Measurements of the Scattering Properties of Planetary Regolith Analogs: A Challenge to Theory

    Piatek, J. L.; Hapke, B. W.; Nelson, R. M.; Hale, A. S.; Smythe, W. D.

    2003-01-01

    The nature of the scattering of light is thought to be well understood when the medium is made up of independent scatterers that are much larger than the wavelength of that light. This is not the case when the size of the scattering objects is similar to or smaller than the wavelength or the scatterers are not independent. In an attempt to examine the applicability of independent particle scattering models, to planetary regoliths, a dataset of experimental results were compared with theoretical predictions.

  10. In-situ, real-time, studies of film growth processes using ion scattering and direct recoil spectroscopy techniques.

    Smentkowski, V. S.

    1999-04-22

    Time-of-flight ion scattering and recoil spectroscopy (TOF-ISARS) enables the characterization of the composition and structure of surfaces with 1-2 monolayer specificity. It will be shown that surface analysis is possible at ambient pressures greater than 3 mTorr using TOF-ISARS techniques; allowing for real-time, in situ studies of film growth processes. TOF-ISARS comprises three analytical techniques: ion scattering spectroscopy (ISS), which detects the backscattered primary ion beam; direct recoil spectroscopy (DRS), which detects the surface species recoiled into the forward scattering direction; and mass spectroscopy of recoiled ions (MSRI), which is 3 variant of DRS capable of isotopic resolution for all surface species--including H and He. The advantages and limitations of each of these techniques will be discussed. The use of the three TOF-ISARS methods for real-time, in situ film growth studies at high ambient pressures will be illustrated. It will be shown that MSRI analysis is possible during sputter deposition. It will be also be demonstrated that the analyzer used for MSRI can also be used for time of flight secondary ion mass spectroscopy (TOF-SIMS) under high vacuum conditions. The use of a single analyzer to perform the complimentary surface analytical techniques of MSRI and SIMS is unique. The dwd functionality of the MSRI analyzer provides surface information not obtained when either MSRI or SIMS is used independently.

  11. Metal oxide nanoparticle mediated enhanced Raman scattering and its use in direct monitoring of interfacial chemical reactions.

    Li, Li; Hutter, Tanya; Finnemore, Alexander S; Huang, Fu Min; Baumberg, Jeremy J; Elliott, Stephen R; Steiner, Ullrich; Mahajan, Sumeet

    2012-08-08

    Metal oxide nanoparticles (MONPs) have widespread usage across many disciplines, but monitoring molecular processes at their surfaces in situ has not been possible. Here we demonstrate that MONPs give highly enhanced (×10(4)) Raman scattering signals from molecules at the interface permitting direct monitoring of their reactions, when placed on top of flat metallic surfaces. Experiments with different metal oxide materials and molecules indicate that the enhancement is generic and operates at the single nanoparticle level. Simulations confirm that the amplification is principally electromagnetic and is a result of optical modulation of the underlying plasmonic metallic surface by MONPs, which act as scattering antennae and couple light into the confined region sandwiched by the underlying surface. Because of additional functionalities of metal oxides as magnetic, photoelectrochemical and catalytic materials, enhanced Raman scattering mediated by MONPs opens up significant opportunities in fundamental science, allowing direct tracking and understanding of application-specific transformations at such interfaces. We show a first example by monitoring the MONP-assisted photocatalytic decomposition reaction of an organic dye by individual nanoparticles.

  12. Characterizing riverbed sediment using high-frequency acoustics 1: spectral properties of scattering

    Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matt A.

    2014-01-01

    Bed-sediment classification using high-frequency hydro-acoustic instruments is challenging when sediments are spatially heterogeneous, which is often the case in rivers. The use of acoustic backscatter to classify sediments is an attractive alternative to analysis of topography because it is potentially sensitive to grain-scale roughness. Here, a new method is presented which uses high-frequency acoustic backscatter from multibeam sonar to classify heterogeneous riverbed sediments by type (sand, gravel,rock) continuously in space and at small spatial resolution. In this, the first of a pair of papers that examine the scattering signatures from a heterogeneous riverbed, methods are presented to construct spatially explicit maps of spectral properties from geo-referenced point clouds of geometrically and radiometrically corrected echoes. Backscatter power spectra are computed to produce scale and amplitude metrics that collectively characterize the length scales of stochastic measures of riverbed scattering, termed ‘stochastic geometries’. Backscatter aggregated over small spatial scales have spectra that obey a power-law. This apparently self-affine behavior could instead arise from morphological- and grain-scale roughnesses over multiple overlapping scales, or riverbed scattering being transitional between Rayleigh and geometric regimes. Relationships exist between stochastic geometries of backscatter and areas of rough and smooth sediments. However, no one parameter can uniquely characterize a particular substrate, nor definitively separate the relative contributions of roughness and acoustic impedance (hardness). Combinations of spectral quantities do, however, have the potential to delineate riverbed sediment patchiness, in a data-driven approach comparing backscatter with bed-sediment observations (which is the subject of part two of this manuscript).

  13. Quasiresonant scattering

    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)

  14. Synthesis of gold nanoflowers using deep eutectic solvent with high surface enhanced Raman scattering properties

    Aghakhani Mahyari, Farzaneh; Tohidi, Maryam; Safavi, Afsaneh

    2016-09-01

    A facile, seed-less and one-pot method was developed for synthesis of gold nanoflowers with multiple tips through reduction of HAuCl4 with deep eutectic solvent at room temperature. This solvent is eco-friendly, low-cost, non-toxic and biodegradable and can act as both reducing and shape-controlling agent. In this protocol, highly branched and stable gold nanoflowers were obtained without using any capping agent. The obtained products were characterized by different techniques including, field emission scanning electron microscopy, transmission electron microscopy, x-ray diffraction and UV-vis spectroscopy. The as-prepared gold nanoflowers exhibit efficient surface-enhanced Raman scattering (SERS) properties which can be used as excellent substrates for SERS.

  15. QCD and the transverse properties of jets in deep inelastic scattering

    Peccei, R.D.; Rueckl, R.

    1981-01-01

    We study the transverse properties of hadronic jets in deep inelastic scattering, focusing on features which reflect predominantly the underlying QCD structure rather than the process of hadronization. In particular we discuss the QCD induced asymmetries between the transverse size for forward and backward going jets in the virtual boson-nucleon c.m.s. We also analyze the dependence of this transverse spread on the produced hadron energy and indicate how the QCD pattern differs from that expected from hadronization or primordial transverse momentum. We point out, furthermore, the theoretical, and possibly experimental, advantages of studying the average angular spread of the energy flow rather than the transverse momenta of the particle jets. (orig.)

  16. Brillouin light scattering studies on the mechanical properties of ultrathin, porous low-K dielectric films

    Zhou, Wei; Sooryakumar, R.; King, Sean

    2010-03-01

    Low K dielectrics have predominantly replaced silicon dioxide as the interlayer dielectric material for interconnects in state of the art integrated circuits. To further reduce interconnect resistance-capacitance (RC) delays, additional reductions in the K for these low-K materials is being pursued by the introduction of controlled levels of porosity. The main challenge for porous low-K dielectrics is the substantial reduction in mechanical properties that is accompanied by the increased pore volume content needed to reduce K. We report on the application of the nondestructive Brillouin light scattering technique to monitor and characterize the mechanical properties of these porous films at thicknesses well below 200 nm that are pertinent to present applications. Observation of longitudinal and transverse standing wave acoustic resonances and the dispersion that accompany their transformation into traveling waves with finite in-plane wave vectors provides for the principal elastic constants that completely characterize the mechanical properties of these porous films. The mode amplitudes of the standing waves, their variation within the film, and the calculated Brillouin intensities account for most aspects of the spectra. The resulting elastic constants are compared with corresponding values obtained from other experimental techniques.

  17. Use of a solar panel as a directionally sensitive large-area radiation monitor for direct and scattered x-rays and gamma-rays.

    Abdul-Majid, S

    1987-01-01

    The characteristics of a 25.4 X 91 cm solar cell panel used as an x-ray and gamma-ray radiation monitor are presented. Applications for monitoring the primary x-ray beam are described at different values of operating currents and voltages as well as for directional dependence of scattered radiation. Other applications in gamma-ray radiography are also given. The detector showed linear response to both x-ray and gamma-ray exposures. The equipment is rigid, easy to use, relatively inexpensive and requires no power supply or any complex electronic equipment.

  18. Threshold properties of Veneziano model for ππ, πK, and KK scattering

    Wong, N.N.; Kamal, A.N.

    1975-01-01

    The S and P partial waves are projected out at low energies for ππ, πK, K anti K, and KK scatterings from the Veneziano amplitude. The scattering lengths and the effective ranges are compared with the current-algebra predictions. Using ππ scattering as an example one can project out an arbitrary partial wave

  19. Photometric Properties of Network and Faculae Derived from HMI Data Compensated for Scattered Light

    Criscuoli, Serena; Whitney, Taylor [National Solar Observatory, 3665 Discovery Drive, Boulder, CO 80303 (United States); Norton, Aimee [Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, 94305 (United States)

    2017-10-01

    We report on the photometric properties of faculae and network, as observed in full-disk, scattered-light-corrected images from the Helioseismic Magnetic Imager. We use a Lucy–Richardson deconvolution routine that corrects an image in less than one second. Faculae are distinguished from network through proximity to active regions. This is the first report that full-disk observations, including center-to-limb variations, reproduce the photometric properties of faculae and network observed previously only in sub-arcsecond-resolution; small field-of-view studies, i.e. that network, as defined by distance from active regions, exhibit higher photometric contrasts. Specifically, for magnetic flux values larger than approximately 300 G, the network is brighter than faculae and the contrast differences increase toward the limb, where the network contrast is about twice the facular one. For lower magnetic flux values, network appear darker than faculae. Contrary to reports from previous full-disk observations, we also found that network exhibits a higher center-to-limb variation. Our results are in agreement with reports from simulations that indicate magnetic flux alone is a poor proxy of the photometric properties of magnetic features. We estimate that the contribution of faculae and network to Total Solar Irradiance variability of the current Cycle 24 is overestimated by at least 11%, due to the photometric properties of network and faculae not being recognized as different. This estimate is specific to the method employed in this study to reconstruct irradiance variations, so caution should be paid when extending it to other techniques.

  20. Photometric Properties of Network and Faculae Derived from HMI Data Compensated for Scattered Light

    Criscuoli, Serena; Whitney, Taylor; Norton, Aimee

    2017-01-01

    We report on the photometric properties of faculae and network, as observed in full-disk, scattered-light-corrected images from the Helioseismic Magnetic Imager. We use a Lucy–Richardson deconvolution routine that corrects an image in less than one second. Faculae are distinguished from network through proximity to active regions. This is the first report that full-disk observations, including center-to-limb variations, reproduce the photometric properties of faculae and network observed previously only in sub-arcsecond-resolution; small field-of-view studies, i.e. that network, as defined by distance from active regions, exhibit higher photometric contrasts. Specifically, for magnetic flux values larger than approximately 300 G, the network is brighter than faculae and the contrast differences increase toward the limb, where the network contrast is about twice the facular one. For lower magnetic flux values, network appear darker than faculae. Contrary to reports from previous full-disk observations, we also found that network exhibits a higher center-to-limb variation. Our results are in agreement with reports from simulations that indicate magnetic flux alone is a poor proxy of the photometric properties of magnetic features. We estimate that the contribution of faculae and network to Total Solar Irradiance variability of the current Cycle 24 is overestimated by at least 11%, due to the photometric properties of network and faculae not being recognized as different. This estimate is specific to the method employed in this study to reconstruct irradiance variations, so caution should be paid when extending it to other techniques.

  1. Probing Anisotropic Surface Properties of Molybdenite by Direct Force Measurements.

    Lu, Zhenzhen; Liu, Qingxia; Xu, Zhenghe; Zeng, Hongbo

    2015-10-27

    Probing anisotropic surface properties of layer-type mineral is fundamentally important in understanding its surface charge and wettability for a variety of applications. In this study, the surface properties of the face and the edge surfaces of natural molybdenite (MoS2) were investigated by direct surface force measurements using atomic force microscope (AFM). The interaction forces between the AFM tip (Si3N4) and face or edge surface of molybdenite were measured in 10 mM NaCl solutions at various pHs. The force profiles were well-fitted with classical DLVO (Derjaguin-Landau-Verwey-Overbeek) theory to determine the surface potentials of the face and the edge surfaces of molybdenite. The surface potentials of both the face and edge surfaces become more negative with increasing pH. At neutral and alkaline conditions, the edge surface exhibits more negative surface potential than the face surface, which is possibly due to molybdate and hydromolybdate ions on the edge surface. The point of zero charge (PZC) of the edge surface was determined around pH 3 while PZC of the face surface was not observed in the range of pH 3-11. The interaction forces between octadecyltrichlorosilane-treated AFM tip (OTS-tip) and face or edge surface of molybdenite were also measured at various pHs to study the wettability of molybdenite surfaces. An attractive force between the OTS-tip and the face surface was detected. The force profiles were well-fitted by considering DLVO forces and additional hydrophobic force. Our results suggest the hydrophobic feature of the face surface of molybdenite. In contrast, no attractive force between the OTS-tip and the edge surface was detected. This is the first study in directly measuring surface charge and wettability of the pristine face and edge surfaces of molybdenite through surface force measurements.

  2. Fundamental properties of field emission-driven direct current microdischarges

    Rumbach, Paul; Go, David B.

    2012-01-01

    For half a century, it has been known that the onset of field emission in direct current microdischarges with gap sizes less than 10 μm can lead to breakdown at applied voltages far less than predicted by Paschen's law. It is still unclear how field emission affects other fundamental plasma properties at this scale. In this work, a one-dimensional fluid model is used to predict basic scaling laws for fundamental properties including ion density, electric field due to space charge, and current-voltage relations in the pre-breakdown regime. Computational results are compared with approximate analytic solutions. It is shown that field emission provides an abundance of cathode electrons, which in turn create large ion concentrations through ionizing collisions well before Paschen's criterion for breakdown is met. Breakdown due to ion-enhanced field emission occurs when the electric field due to space charge becomes comparable to the applied electric field. Simple scaling analysis of the 1D Poisson equation demonstrates that an ion density of n + ≈ 0.1V A ε 0 /qd 2 is necessary to significantly distort the electric field. Defining breakdown in terms of this critical ion density leads analytically to a simple, effective secondary emission coefficient γ ′ of the same mathematical form initially suggested by Boyle and Kisliuk [Phys. Rev. 97, 255 (1955)].

  3. Aerosol optical properties and direct radiative forcing at Taihu.

    Lü, Rui; Yu, Xingna; Jia, Hailing; Xiao, Sihan

    2017-09-01

    Ground-based characteristics (optical, type, size, and radiative properties) of aerosols measured between 2005 and 2012 were investigated over the Taihu rim region, which encompasses the cities of Shanghai, Suzhou, Wuxi, and Changzhou. The aerosol optical depth (AOD) showed a distinct seasonal variation with the highest value in summer and the lowest AOD in winter. There was broadest frequency distribution with a multimodal structure in summer. The Ångström exponent (AE) showed high values during spring; the relative frequency of AE in the range of 0-0.8 was 5-10 times greater than that of other seasons. The samples with high AOD 440 and low AE 440-870 were mainly observed in spring, which is attributed to the relative abundance of coarse particles. The monthly aerosol volume size distributions presented a bimodal structure (fine and coarse modes). The coarse mode was dominant during spring, while the fine mode was predominant in other seasons. The main aerosol type over Taihu during all the seasons was the mixed small-particle category, followed by the urban/industrial category. The minimum single scattering albedo (SSA) occurred in winter, suggesting that atmosphere aerosol had a higher absorption. All monthly averaged asymmetry factors (ASY) had positive values and no distinct seasonal variation. Both high real (Re) and imaginary (Im) parts of the refractive index occurred in winter. The atmospheric warming effect of aerosol was more significant in winter compared with other seasons, with the averaged atmosphere aerosol radiative forcing (ARF) and the corresponding atmospheric heating rate up to +69.46  W·m -2 and 1.95  K·day -1 , respectively. There existed a significant positive correlation between AOD and ARF (absolute value), and the correlation coefficients (r) exceeded 0.86 in each season with maximum r in summer. Along with the increasing of the SSA, the aerosol radiative forcing efficiency (absolute value) showed a decreasing trend at the

  4. [Light scattering extinction properties of atmospheric particle and pollution characteristics in hazy weather in Hangzhou].

    Xu, Chang; Ye, Hui; Shen, Jian-Dong; Sun, Hong-Liang; Hong, Sheng-Mao; Jiao, Li; Huang, Kan

    2014-12-01

    In order to evaluate the influence of particle scattering on visibility, light scattering coefficient, particle concentrations and meteorological factor were simultaneously monitored from July 2011 to June 2012 in Hangzhou. Daily scattering coefficients ranged from 108.4 to 1 098.1 Mm(-1), with an annual average concentration of 428.6 Mm(-1) ± 200.2 Mm(-1). Seasonal variation of scattering coefficients was significant, with the highest concentrations observed in autumn and winter and the lowest in summer. It was found there were two peaks for the average diurnal variations of the scattering coefficient, which could be observed at 08:00 and 21:00. The scattering efficiencies of PM2.5 and PM10 were 7.6 m2 x g(-1) and 4.4 m2 x g(-1), respectively. The particle scattering was about 90.2 percent of the total light extinction. The scattering coefficients were 684.4 Mm(-1) ± 218.1 Mm(-1) and 1 095.4 Mm(-1) ± 397.7 Mm(-1) in hazy and heavy hazy days, respectively, which were 2.6 and 4.2 times as high as in non-hazy weather, indicating that particle scattering is the main factor for visibility degradation and the occurrence of hazy weather in Hangzhou.

  5. Structural and dynamical properties of chlorinated hydrocarbons studied with resonant inelastic x-ray scattering

    Bohinc, R.; Žitnik, M.; Bučar, K.; Kavčič, M.; Carniato, S.; Journel, L.; Guillemin, R.; Marchenko, T.; Kawerk, E.; Simon, M.; Cao, W.

    2016-04-01

    We present a theoretical and experimental study of resonant inelastic x-ray scattering on a large group of chlorinated hydrocarbons: CH3Cl, CH2Cl2, CHCl3, CCl4, CH3CH2Cl, ClCH2CH2Cl, CH3CHCl2, CH3CCl3, C2H2Cl2-iso, C2H2Cl2-cis, C2H2Cl2-trans, and C6H5Cl. Differences in structural and dynamical properties of the molecules generated by diverse chemical environments are observed in the measured Cl(Kα) spectral maps as well as in the Cl(K) total fluorescence yield spectra. The energy position, relative intensity, and the width of the Franck-Condon distribution of low-lying σ∗ and π∗ resonances are extracted by a fitting procedure taking into account the experimental broadening. The theoretical values obtained with the transition potential and Δ Kohn-Sham methods are in good agreement with the experimental parameters indicating subtle differences due to variations in the molecular structure.

  6. Applicability of surface-enhanced resonance Raman scattering for the direct discrimination of ballpoint pen inks

    Seifar, R.M.; Verheul, J.M.; Ariese, F.; Brinkman, U.A.T.; Gooijer, C.

    2001-01-01

    In situ surface-enhanced resonance Raman spectroscopy (SERRS) with excitation at 685 nm is suitable for the direct discrimination of blue and black ballpoint pen inks on paper. For black inks, shorter excitation wavelengths can also be used. For blue inks, SERRS at 514.5 and 457.9 nm does not

  7. Applications of the quasi-elastic light scattering to the study of dynamic properties of charged macro-molecules

    Gouesin-Menez, Renee

    1979-01-01

    The object of this research thesis is to study the modifications of dynamic properties of a macromolecule under the influence of variations of its medium, by using a frequency analysis of the spectrum of light scattered by a solution of particles. Thus, an important part of this thesis addresses the study and development of the scattering method and of its analysis by 'photon pulses', and the development and adjustment of an electrophoretic device to study light scattering by molecules submitted to an electric field. Then, hydrodynamic characteristics of some macromolecules have been measured with or without electric field. The studied molecular systems have been: calibrated spheres of latex polystyrene, a globular protein (bovine serum albumin), a polysaccharide (under the form of a rigid short stick), a flexible linear polyelectrolyte (polymethacrylate), and two DNA samples

  8. Oxygen transport properties estimation by classical trajectory–direct simulation Monte Carlo

    Bruno, Domenico, E-mail: domenico.bruno@cnr.it [Istituto di Metodologie Inorganiche e dei Plasmi, Consiglio Nazionale delle Ricerche– Via G. Amendola 122, 70125 Bari (Italy); Frezzotti, Aldo, E-mail: aldo.frezzotti@polimi.it; Ghiroldi, Gian Pietro, E-mail: gpghiro@gmail.com [Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano–Via La Masa 34, 20156 Milano (Italy)

    2015-05-15

    Coupling direct simulation Monte Carlo (DSMC) simulations with classical trajectory calculations is a powerful tool to improve predictive capabilities of computational dilute gas dynamics. The considerable increase in computational effort outlined in early applications of the method can be compensated by running simulations on massively parallel computers. In particular, Graphics Processing Unit acceleration has been found quite effective in reducing computing time of classical trajectory (CT)-DSMC simulations. The aim of the present work is to study dilute molecular oxygen flows by modeling binary collisions, in the rigid rotor approximation, through an accurate Potential Energy Surface (PES), obtained by molecular beams scattering. The PES accuracy is assessed by calculating molecular oxygen transport properties by different equilibrium and non-equilibrium CT-DSMC based simulations that provide close values of the transport properties. Comparisons with available experimental data are presented and discussed in the temperature range 300–900 K, where vibrational degrees of freedom are expected to play a limited (but not always negligible) role.

  9. Physicochemical Properties of Biopolymer Hydrogels Treated by Direct Electric Current

    Żaneta Król

    2016-07-01

    Full Text Available The objective of this study was to evaluate the changes within the physicochemical properties of gelatine (2%; 4%; 8%, carrageenan (1.5%; 2%; 2.5% and sodium alginate (0.75%; 1%; 1.25% hydrogels with different sodium chloride concentrations that were triggered by applying direct current (DC of 400 mA for a duration of five minutes. There were three types of gels prepared for the purpose of the study: C, control; H, gels on the basis of hydrosols that were treated with DC; and G, gels treated with DC. In the course of the study, the authors carried out the following analyses: Texture Profile Analysis (TPA, Fourier Transform Infrared spectroscopy (FTIR, Scanning Electron Microscopy (SEM and Swelling Ratio (SR. Furthermore, the color and pH of hydrogels were measured. The FTIR spectra showed that the structures of gelatine, carrageenan and sodium alginate do not significantly change upon applying DC. The results of TPA, SR, color and pH measurement indicate that hydrogels’ properties are significantly dependent on the type of polymer, its concentration and the type of the gel. By changing those parameters, the characteristics of such gels can be additionally tuned, which extends their applicability, e.g., in the food industry. Moreover, the analysis revealed that SR of H gel gelatine after 72 h of storage was 1.84-times higher than SR of the control sample, which indicated that this gel may be considered as a possible component for wound dressing materials.

  10. Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He[sup 2+]-He collisions

    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).

  11. Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He2+-He collisions

    Bordenave-Montesquieu, D.; Dagnac, R.

    1992-01-01

    We studied the single-electron capture as well as the direct processes occurring when a He 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 o 30' (laboratory frame). Single-electron capture into excited states of He + 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)

  12. Resolving the Framework Position of Organic Structure-Directing Agents in Hierarchical Zeolites via Polarized Stimulated Raman Scattering.

    Fleury, Guillaume; Steele, Julian A; Gerber, Iann C; Jolibois, F; Puech, P; Muraoka, Koki; Keoh, Sye Hoe; Chaikittisilp, Watcharop; Okubo, Tatsuya; Roeffaers, Maarten B J

    2018-04-05

    The direct synthesis of hierarchically intergrown silicalite-1 can be achieved using a specific diquaternary ammonium agent. However, the location of these molecules in the zeolite framework, which is critical to understand the formation of the material, remains unclear. Where traditional characterization tools have previously failed, herein we use polarized stimulated Raman scattering (SRS) microscopy to resolve molecular organization inside few-micron-sized crystals. Through a combination of experiment and first-principles calculations, our investigation reveals the preferential location of the templating agent inside the linear pores of the MFI framework. Besides illustrating the attractiveness of SRS microscopy in the field of material science to study and spatially resolve local molecular distribution as well as orientation, these results can be exploited in the design of new templating agents for the preparation of hierarchical zeolites.

  13. Application of conditional simulation of heterogeneous rock properties to seismic scattering and attenuation analysis in gas hydrate reservoirs

    Huang, Jun-Wei; Bellefleur, Gilles; Milkereit, Bernd

    2012-02-01

    We present a conditional simulation algorithm to parameterize three-dimensional heterogeneities and construct heterogeneous petrophysical reservoir models. The models match the data at borehole locations, simulate heterogeneities at the same resolution as borehole logging data elsewhere in the model space, and simultaneously honor the correlations among multiple rock properties. The model provides a heterogeneous environment in which a variety of geophysical experiments can be simulated. This includes the estimation of petrophysical properties and the study of geophysical response to the heterogeneities. As an example, we model the elastic properties of a gas hydrate accumulation located at Mallik, Northwest Territories, Canada. The modeled properties include compressional and shear-wave velocities that primarily depend on the saturation of hydrate in the pore space of the subsurface lithologies. We introduce the conditional heterogeneous petrophysical models into a finite difference modeling program to study seismic scattering and attenuation due to multi-scale heterogeneity. Similarities between resonance scattering analysis of synthetic and field Vertical Seismic Profile data reveal heterogeneity with a horizontal-scale of approximately 50 m in the shallow part of the gas hydrate interval. A cross-borehole numerical experiment demonstrates that apparent seismic energy loss can occur in a pure elastic medium without any intrinsic attenuation of hydrate-bearing sediments. This apparent attenuation is largely attributed to attenuative leaky mode propagation of seismic waves through large-scale gas hydrate occurrence as well as scattering from patchy distribution of gas hydrate.

  14. Properties of Direct Coal Liquefaction Residue Modified Asphalt Mixture

    Jie Ji

    2017-01-01

    Full Text Available The objectives of this paper are to use Direct Coal Liquefaction Residue (DLCR to modify the asphalt binders and mixtures and to evaluate the performance of modified asphalt mixtures. The dynamic modulus and phase angle of DCLR and DCLR-composite modified asphalt mixture were analyzed, and the viscoelastic properties of these modified asphalt mixtures were compared to the base asphalt binder SK-90 and Styrene-Butadiene-Styrene (SBS modified asphalt mixtures. The master curves of the asphalt mixtures were shown, and dynamic and viscoelastic behaviors of asphalt mixtures were described using the Christensen-Anderson-Marasteanu (CAM model. The test results show that the dynamic moduli of DCLR and DCLR-composite asphalt mixtures are higher than those of the SK-90 and SBS modified asphalt mixtures. Based on the viscoelastic parameters of CAM models of the asphalt mixtures, the high- and low-temperature performance of DLCR and DCLR-composite modified asphalt mixtures are obviously better than the SK-90 and SBS modified asphalt mixtures. In addition, the DCLR and DCLR-composite modified asphalt mixtures are more insensitive to the frequency compared to SK-90 and SBS modified asphalt mixtures.

  15. Nanofluid optical property characterization: towards efficient direct absorption solar collectors

    Otanicar Todd

    2011-01-01

    Full Text Available Abstract Suspensions of nanoparticles (i.e., particles with diameters < 100 nm in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm. A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power increase.

  16. Method of measuring directed electron velocities in flowing plasma using the incoherent regions of laser scattering

    Jacoby, B.A.; York, T.M.

    1979-02-01

    With the presumption that a shifted Maxwellian velocity distribution adequately describes the electrons in a flowing plasma, the details of a method to measure their directed velocity are described. The system consists of a ruby laser source and two detectors set 180 0 from each other and both set at 90 0 with respect to the incident laser beam. The lowest velocity that can be determined by this method depends on the electron thermal velocity. The application of this diagnostic to the measurement of flow velocities in plasma being lost from the ends of theta-pinch devices is described

  17. Various scattering properties of a new PT-symmetric non-Hermitian potential

    Ghatak, Ananya, E-mail: gananya04@gmail.com [Department of Physics, Banaras Hindu University, Varanasi-221005 (India); Mandal, Raka Dona Ray, E-mail: rakad.ray@gmail.com [Department of Physics, Rajghat Besant School, Varanasi-221001 (India); Mandal, Bhabani Prasad, E-mail: bhabani.mandal@gmail.com [Department of Physics, Banaras Hindu University, Varanasi-221005 (India)

    2013-09-15

    We complexify a 1-d potential V(x)=V{sub 0}cosh{sup 2}μ(tanh[(x−μd)/d]+tanh(μ)){sup 2} which exhibits bound, reflecting and free states to study various properties of a non-Hermitian system. This potential turns out a PT-symmetric non-Hermitian potential when one of the parameters (μ,d) becomes imaginary. For the case of μ→iμ, we have an entire real bound state spectrum. Explicit scattering states are constructed to show reciprocity at certain discrete values of energy even though the potential is not parity symmetric. Coexistence of deep energy minima of transmissivity with the multiple spectral singularities (MSS) is observed. We further show that this potential becomes invisible from the left (or right) at certain discrete energies. The penetrating states in the other case (d→id) are always reciprocal even though it is PT-invariant and no spectral singularity (SS) is present in this case. The presence of MSS and reflectionlessness is also discussed for the free states in the later case. -- Highlights: •Existence of multiple spectral singularities (MSS) in PT-symmetric non-Hermitian system is shown. •Reciprocity is restored at discrete positive energies even for parity non-invariant complex system. •Co-existence of MSS with deep energy minima of transitivity is obtained. •Possibilities of both unidirectional and bidirectional invisibility are explored for a non-Hermitian system. •Penetrating states are shown to be reciprocal for all energies for PT-symmetric system.

  18. Various scattering properties of a new PT-symmetric non-Hermitian potential

    Ghatak, Ananya; Mandal, Raka Dona Ray; Mandal, Bhabani Prasad

    2013-01-01

    We complexify a 1-d potential V(x)=V 0 cosh 2 μ(tanh[(x−μd)/d]+tanh(μ)) 2 which exhibits bound, reflecting and free states to study various properties of a non-Hermitian system. This potential turns out a PT-symmetric non-Hermitian potential when one of the parameters (μ,d) becomes imaginary. For the case of μ→iμ, we have an entire real bound state spectrum. Explicit scattering states are constructed to show reciprocity at certain discrete values of energy even though the potential is not parity symmetric. Coexistence of deep energy minima of transmissivity with the multiple spectral singularities (MSS) is observed. We further show that this potential becomes invisible from the left (or right) at certain discrete energies. The penetrating states in the other case (d→id) are always reciprocal even though it is PT-invariant and no spectral singularity (SS) is present in this case. The presence of MSS and reflectionlessness is also discussed for the free states in the later case. -- Highlights: •Existence of multiple spectral singularities (MSS) in PT-symmetric non-Hermitian system is shown. •Reciprocity is restored at discrete positive energies even for parity non-invariant complex system. •Co-existence of MSS with deep energy minima of transitivity is obtained. •Possibilities of both unidirectional and bidirectional invisibility are explored for a non-Hermitian system. •Penetrating states are shown to be reciprocal for all energies for PT-symmetric system

  19. On the use of a Hamiltonian with projected potential for the calculation of scattering wave functions : Methods and general properties

    Colle, R.; Simonucci, S.

    1996-01-01

    The theoretical framework of a method that utilizes a projected potential operator to construct scattering wave functions is presented. Theorems and spectral properties of a Hamiltonian with the potential energy operator represented in terms of L'2(R'3)-functions are derived. The computational advantages offered by the method for calculating spectroscopic quantities, like resonance energies, decay probabilities and photoionization cross-sections, are discussed

  20. Dispersion relation for the 3. -->. 3 forward scattering amplitude and the generalized optical theorem. [Crossing properties, dispersion relations

    Logunov, A A; Medvedev, B V; Mestvirishvili, M A; Pavlov, V P; Polivanov, M K; Sukhanov, A D [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Serpukhov. Inst. Fiziki Vysokikh Ehnergij

    1977-11-01

    Investigation of analytical structure of the three-particle forward scattering amplitude with respect to energy variable of one of particles is performed. The results obtained make it possible to draw the conclusions on crossing properties of the amplitude and to derive the generalized optical theorem relating the discontinuity of the amplitude to the distribution function of an inclusive process. For a special case when two of three particles are of zero mass, a dispersion relation is proved.

  1. 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.

  2. Test of Mie-based single-scattering properties of non-spherical dust aerosols in radiative flux calculations

    Fu, Q.; Thorsen, T.J.; Su, J.; Ge, J.M.; Huang, J.P.

    2009-01-01

    We simulate the single-scattering properties (SSPs) of dust aerosols with both spheroidal and spherical shapes at a wavelength of 0.55 μm for two refractive indices and four effective radii. Herein spheres are defined by preserving both projected area and volume of a non-spherical particle. It is shown that the relative errors of the spheres to approximate the spheroids are less than 1% in the extinction efficiency and single-scattering albedo, and less than 2% in the asymmetry factor. It is found that the scattering phase function of spheres agrees with spheroids better than the Henyey-Greenstein (HG) function for the scattering angle range of 0-90 o . In the range of ∼90-180 o , the HG function is systematically smaller than the spheroidal scattering phase function while the spherical scattering phase function is smaller from ∼90 o to 145 o but larger from ∼145 o to 180 o . We examine the errors in reflectivity and absorptivity due to the use of SSPs of equivalent spheres and HG functions for dust aerosols. The reference calculation is based on the delta-DISORT-256-stream scheme using the SSPs of the spheroids. It is found that the errors are mainly caused by the use of the HG function instead of the SSPs for spheres. By examining the errors associated with the delta-four- and delta-two-stream schemes using various approximate SSPs of dust aerosols, we find that the errors related to the HG function dominate in the delta-four-stream results, while the errors related to the radiative transfer scheme dominate in the delta-two-stream calculations. We show that the relative errors in the global reflectivity due to the use of sphere SSPs are always less than 5%. We conclude that Mie-based SSPs of non-spherical dust aerosols are well suited in radiative flux calculations.

  3. Global direct radiative forcing by process-parameterized aerosol optical properties

    KirkevâG, Alf; Iversen, Trond

    2002-10-01

    A parameterization of aerosol optical parameters is developed and implemented in an extended version of the community climate model version 3.2 (CCM3) of the U.S. National Center for Atmospheric Research. Direct radiative forcing (DRF) by monthly averaged calculated concentrations of non-sea-salt sulfate and black carbon (BC) is estimated. Inputs are production-specific BC and sulfate from [2002] and background aerosol size distribution and composition. The scheme interpolates between tabulated values to obtain the aerosol single scattering albedo, asymmetry factor, extinction coefficient, and specific extinction coefficient. The tables are constructed by full calculations of optical properties for an array of aerosol input values, for which size-distributed aerosol properties are estimated from theory for condensation and Brownian coagulation, assumed distribution of cloud-droplet residuals from aqueous phase oxidation, and prescribed properties of the background aerosols. Humidity swelling is estimated from the Köhler equation, and Mie calculations finally yield spectrally resolved aerosol optical parameters for 13 solar bands. The scheme is shown to give excellent agreement with nonparameterized DRF calculations for a wide range of situations. Using IPCC emission scenarios for the years 2000 and 2100, calculations with an atmospheric global cliamte model (AFCM) yield a global net anthropogenic DRF of -0.11 and 0.11 W m-2, respectively, when 90% of BC from biomass burning is assumed anthropogenic. In the 2000 scenario, the individual DRF due to sulfate and BC has separately been estimated to -0.29 and 0.19 W m-2, respectively. Our estimates of DRF by BC per BC mass burden are lower than earlier published estimates. Some sensitivity tests are included to investigate to what extent uncertain assumptions may influence these results.

  4. Effects of multiple scattering on radiative properties of soot fractal aggregates

    Yon, Jérôme; Liu, Fengshan; Bescond, Alexandre; Caumont-Prim, Chloé; Rozé, Claude; Ouf, François-Xavier; Coppalle, Alexis

    2014-01-01

    The in situ optical characterization of smokes composed of soot particles relies on light extinction, angular static light scattering (SLS), or laser induced incandescence (LII). These measurements are usually interpreted by using the Rayleigh–Debye–Gans theory for Fractal Aggregates (RDG-FA). RDG-FA is simple to use but it completely neglects the impact of multiple scattering (MS) within soot aggregates. In this paper, based on a scaling approach that takes into account MS effects, an extended form of the RDG-FA theory is proposed in order to take into account these effects. The parameters of this extended theory and their dependency on the number of primary sphere inside the aggregate (1 p <1006) and on the wavelength (266nm<λ<1064nm) are evaluated thanks to rigorous calculations based on discrete dipole approximation (DDA) and generalized multi-sphere Mie-solution (GMM) calculations. This study shows that size determination by SLS is not distorted by MS effect. On the contrary, it is shown that fractal dimension can be misinterpreted by light scattering experiments, especially at short wavelengths. MS effects should be taken into account for the interpretation of absorption measurements that are involved in LII or extinction measurements. -- Highlights: • We incorporate multiple scattering effects in a scaling approach for fractal aggregates. • A generalized structure factor is introduced for implementation in RDG-FA theory. • Forward scattering is affected by multiple scattering as well as power law regime. • Absorption cross sections are affected by multiple scattering. • Absorption cross sections are 11% higher than that for forward scattering

  5. Scattering properties of ultrafast laser-induced refractive index shaping lenticular structures in hydrogels

    Wozniak, Kaitlin T.; Germer, Thomas A.; Butler, Sam C.; Brooks, Daniel R.; Huxlin, Krystel R.; Ellis, Jonathan D.

    2018-02-01

    We present measurements of light scatter induced by a new ultrafast laser technique being developed for laser refractive correction in transparent ophthalmic materials such as cornea, contact lenses, and/or intraocular lenses. In this new technique, called intra-tissue refractive index shaping (IRIS), a 405 nm femtosecond laser is focused and scanned below the corneal surface, inducing a spatially-varying refractive index change that corrects vision errors. In contrast with traditional laser correction techniques, such as laser in-situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), IRIS does not operate via photoablation, but rather changes the refractive index of transparent materials such as cornea and hydrogels. A concern with any laser eye correction technique is additional scatter induced by the process, which can adversely affect vision, especially at night. The goal of this investigation is to identify sources of scatter induced by IRIS and to mitigate possible effects on visual performance in ophthalmic applications. Preliminary light scattering measurements on patterns written into hydrogel showed four sources of scatter, differentiated by distinct behaviors: (1) scattering from scanned lines; (2) scattering from stitching errors, resulting from adjacent scanning fields not being aligned to one another; (3) diffraction from Fresnel zone discontinuities; and (4) long-period variations in the scans that created distinct diffraction peaks, likely due to inconsistent line spacing in the writing instrument. By knowing the nature of these different scattering errors, it will now be possible to modify and optimize the design of IRIS structures to mitigate potential deficits in visual performance in human clinical trials.

  6. Two-dimensional phononic crystals with time-varying properties: a multiple scattering analysis

    Wright, D W; Cobbold, R S C

    2010-01-01

    Multiple scattering theory is a versatile two- and three-dimensional method for characterizing the acoustic wave transmission through many scatterers. It provides analytical solutions to wave propagation in scattering structures, and its computational complexity grows logarithmically with the number of scatterers. In this paper we show how the 2D method can be adapted to include the effects of time-varying material parameters. Specifically, a new T-matrix is defined to include the effects of frequency modulation that occurs in time-varying phononic crystals. Solutions were verified against finite difference time domain (FDTD) simulations and showed excellent agreement. This new method enables fast characterization of time-varying phononic crystals without the need to resort to lengthy FDTD simulations. Also, the method of combining T-matrices to form the T-supermatrix remains unchanged provided that the new matrix definitions are used. The method is quite compatible with existing implementations of multiple scattering theory and could be readily extended to three-dimensional multiple scattering theory

  7. Indirect and direct measurement of thermal neutron acceleration by inelastic scattering on the {sup 177}Lu isomer

    Belier, G.; Roig, O.; Meot, V.; Daugas, J.M. [CEA Bruyeres-le-Chatel, Dept. de Physique Theorique et Appliquee, 91 (France); Aupiais, J.; Jutier, Ch.; Le Petit, G. [CEA Bruyeres-le-Chatel, Service de Physique Nucleaire, 91 (France). Dept. de Physique Theorique et Appliquee; Letourneau, A.; Marie, F. [CEA Saclay, Dept. d' Astrophysique de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, Service de Physique Nucleaire, 91- Gif sur Yvette (France); Veyssiere, Ch. [CEA Saclay, Dept. d' Astrophysique de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, Service d' Ingenierie des Systemes, 91- Gif sur Yvette (France)

    2008-07-01

    When neutrons interact with isomers, these isomers can de-excite and in such a reaction the outgoing neutron has an energy greater than the in-going one. This process is referred as Inelastic Neutron Acceleration or Super-elastic Scattering. Up to now this process was observed for only two nucleus, {sup 152m}Eu and {sup 180m}Hf by measuring the number of fast neutrons produced by isomeric targets irradiated with thermal neutrons. In these experiments the energies of the accelerated neutrons were not measured. This report presents an indirect measurement of inelastic neutron acceleration on {sup 177m}Lu, based on the burn-up and the radiative capture cross sections measurements. Since at thermal energies the inelastic scattering and the radiative capture are the only processes that contribute to the isomer burn-up, the inelastic cross section can be deduced from the difference between the two measured quantities. Applying this method for the {sup 177}Lu isomer with different neutron fluxes we obtained a value of (257 {+-} 50) barns (for a temperature of 323 K) and determined that there is no integral resonance for this process. In addition the radiative capture cross section on {sup 177g}Lu was measured with a much better accuracy than the accepted value. Since the acceleration cross section is quite high, a direct measurement of this process was undertaken, sending thermal neutrons and measuring the fast neutrons. The main goal now is to measure the outgoing neutron energies in order to identify the neutron transitions in the exit channel. In particular the K conservation question can be addressed by such a measurement. (author)

  8. Aerosol optical properties measurements by a CAPS single scattering albedo monitor: Comparisons between summer and winter in Beijing, China

    Han, Tingting; Xu, Weiqi; Li, Jie; Freedman, Andrew; Zhao, Jian; Wang, Qingqing; Chen, Chen; Zhang, Yingjie; Wang, Zifa; Fu, Pingqing; Liu, Xingang; Sun, Yele

    2017-02-01

    Aerosol optical properties were measured in Beijing in summer and winter using a state-of-the-art cavity attenuated phase shift single scattering albedo monitor (CAPS PMssa) along with aerosol composition measurements by aerosol mass spectrometers and aethalometers. The SSA directly measured by the CAPS PMssa showed overall agreements with those derived from colocated measurements. However, substantial differences were observed during periods with low SSA values in both summer and winter, suggesting that interpretation of low SSA values needs to be cautious. The average (±σ) extinction coefficient (bext) and absorption coefficient (bap) were 336 (±343) Mm-1 and 44 (±41) Mm-1, respectively, during wintertime, which were approximately twice those observed in summer, while the average SSA was relatively similar, 0.86 (±0.06) and 0.85 (±0.04) in summer and winter, respectively. Further analysis showed that the variations in SSA can be approximately parameterized as a function of mass fraction of secondary particulate matter (fSPM), which is SSA = 0.74 + 0.19 × fSPM (fSPM > 0.3, r2 = 0.85). The contributions of aerosol species to extinction coefficients during the two seasons were also estimated. Our results showed that the light extinction was dominantly contributed by ammonium sulfate (30%) and secondary organic aerosol (22%) in summer, while organic aerosol was the largest contributor (51%) in winter. Consistently, SPM played the major role in visibility degradation in both seasons by contributing 70% of the total extinction.

  9. Monte Carlo and experimental evaluation of accuracy and noise properties of two scatter correction methods for SPECT

    Narita, Y.; Eberl, S.; Bautovich, G.; Iida, H.; Hutton, B.F.; Braun, M.; Nakamura, T.

    1996-01-01

    Scatter correction is a prerequisite for quantitative SPECT, but potentially increases noise. Monte Carlo simulations (EGS4) and physical phantom measurements were used to compare accuracy and noise properties of two scatter correction techniques: the triple-energy window (TEW), and the transmission dependent convolution subtraction (TDCS) techniques. Two scatter functions were investigated for TDCS: (i) the originally proposed mono-exponential function (TDCS mono ) and (ii) an exponential plus Gaussian scatter function (TDCS Gauss ) demonstrated to be superior from our Monte Carlo simulations. Signal to noise ratio (S/N) and accuracy were investigated in cylindrical phantoms and a chest phantom. Results from each method were compared to the true primary counts (simulations), or known activity concentrations (phantom studies). 99m Tc was used in all cases. The optimized TDCS Gauss method overall performed best, with an accuracy of better than 4% for all simulations and physical phantom studies. Maximum errors for TEW and TDCS mono of -30 and -22%, respectively, were observed in the heart chamber of the simulated chest phantom. TEW had the worst S/N ratio of the three techniques. The S/N ratios of the two TDCS methods were similar and only slightly lower than those of simulated true primary data. Thus, accurate quantitation can be obtained with TDCS Gauss , with a relatively small reduction in S/N ratio. (author)

  10. The effects of drain scatterings on the electron transport properties of strained-Si diodes with ballistic and non-ballistic channels

    Yasenjan Ghupur; Mamtimin Geni; Mamatrishat Mamat; Abudukelimu Abudureheman

    2015-01-01

    The effects of multiple scattering on the electron transport properties in drain regions are numerically investigated for the cases of strained-Si diodes with or without scattering in the channel. The performance of non-ballistic (with scattering) channel Si-diodes is compared with that of ballistic (without scattering) channel Si-diodes, using the strain and scattering model. Our results show that the values of the electron velocity and the current in the strain model are higher than the respective values in the unstrained model, and the values of the velocity and the current in the ballistic channel model are higher than the respective values in the non-ballistic channel model. In the strain and scattering models, the effect of each carrier scattering mechanism on the performance of the Si-diodes is analyzed in the drain region. For the ballistic channel model, our results show that inter-valley optical phonon scattering improves device performance, whereas intra-valley acoustic phonon scattering degrades device performance. For the strain model, our results imply that the larger energy splitting of the strained Si could suppress the inter-valley phonon scattering rate. In conclusion, for the drain region, investigation of the strained-Si and scattering mechanisms are necessary, in order to improve the performance of nanoscale ballistic regime devices. (paper)

  11. Comparison of spatially and temporally resolved diffuse transillumination measurement systems for extraction of optical properties of scattering media.

    Ortiz-Rascón, E; Bruce, N C; Garduño-Mejía, J; Carrillo-Torres, R; Hernández-Paredes, J; Álvarez-Ramos, M E

    2017-11-20

    This paper discusses the main differences between two different methods for determining the optical properties of tissue optical phantoms by fitting the spatial and temporal intensity distribution functions to the diffusion approximation theory. The consistency in the values of the optical properties is verified by changing the width of the recipient containing the turbid medium; as the optical properties are an intrinsic value of the scattering medium, independently of the recipient width, the stability in these values for different widths implies a better measurement system for the acquisition of the optical properties. It is shown that the temporal fitting method presents higher stability than the spatial fitting method; this is probably due to the addition of the time of flight parameter into the diffusion theory.

  12. Quantitative ultrasound characterization of locally advanced breast cancer by estimation of its scatterer properties

    Tadayyon, Hadi [Physical Sciences, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Sadeghi-Naini, Ali; Czarnota, Gregory, E-mail: Gregory.Czarnota@sunnybrook.ca [Physical Sciences, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada); Department of Radiation Oncology, Faculty of Medicine, University of Toronto, Toronto, Ontario M5T 1P5 (Canada); Wirtzfeld, Lauren [Department of Physics, Ryerson University, Toronto, Ontario M5B 2K3 (Canada); Wright, Frances C. [Division of Surgical Oncology, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada)

    2014-01-15

    Purpose: Tumor grading is an important part of breast cancer diagnosis and currently requires biopsy as its standard. Here, the authors investigate quantitative ultrasound parameters in locally advanced breast cancers that can potentially separate tumors from normal breast tissue and differentiate tumor grades. Methods: Ultrasound images and radiofrequency data from 42 locally advanced breast cancer patients were acquired and analyzed. Parameters related to the linear regression of the power spectrum—midband fit, slope, and 0-MHz-intercept—were determined from breast tumors and normal breast tissues. Mean scatterer spacing was estimated from the spectral autocorrelation, and the effective scatterer diameter and effective acoustic concentration were estimated from the Gaussian form factor. Parametric maps of each quantitative ultrasound parameter were constructed from the gated radiofrequency segments in tumor and normal tissue regions of interest. In addition to the mean values of the parametric maps, higher order statistical features, computed from gray-level co-occurrence matrices were also determined and used for characterization. Finally, linear and quadratic discriminant analyses were performed using combinations of quantitative ultrasound parameters to classify breast tissues. Results: Quantitative ultrasound parameters were found to be statistically different between tumor and normal tissue (p < 0.05). The combination of effective acoustic concentration and mean scatterer spacing could separate tumor from normal tissue with 82% accuracy, while the addition of effective scatterer diameter to the combination did not provide significant improvement (83% accuracy). Furthermore, the two advanced parameters, including effective scatterer diameter and mean scatterer spacing, were found to be statistically differentiating among grade I, II, and III tumors (p = 0.014 for scatterer spacing, p = 0.035 for effective scatterer diameter). The separation of the tumor

  13. Quantitative ultrasound characterization of locally advanced breast cancer by estimation of its scatterer properties

    Tadayyon, Hadi; Sadeghi-Naini, Ali; Czarnota, Gregory; Wirtzfeld, Lauren; Wright, Frances C.

    2014-01-01

    Purpose: Tumor grading is an important part of breast cancer diagnosis and currently requires biopsy as its standard. Here, the authors investigate quantitative ultrasound parameters in locally advanced breast cancers that can potentially separate tumors from normal breast tissue and differentiate tumor grades. Methods: Ultrasound images and radiofrequency data from 42 locally advanced breast cancer patients were acquired and analyzed. Parameters related to the linear regression of the power spectrum—midband fit, slope, and 0-MHz-intercept—were determined from breast tumors and normal breast tissues. Mean scatterer spacing was estimated from the spectral autocorrelation, and the effective scatterer diameter and effective acoustic concentration were estimated from the Gaussian form factor. Parametric maps of each quantitative ultrasound parameter were constructed from the gated radiofrequency segments in tumor and normal tissue regions of interest. In addition to the mean values of the parametric maps, higher order statistical features, computed from gray-level co-occurrence matrices were also determined and used for characterization. Finally, linear and quadratic discriminant analyses were performed using combinations of quantitative ultrasound parameters to classify breast tissues. Results: Quantitative ultrasound parameters were found to be statistically different between tumor and normal tissue (p < 0.05). The combination of effective acoustic concentration and mean scatterer spacing could separate tumor from normal tissue with 82% accuracy, while the addition of effective scatterer diameter to the combination did not provide significant improvement (83% accuracy). Furthermore, the two advanced parameters, including effective scatterer diameter and mean scatterer spacing, were found to be statistically differentiating among grade I, II, and III tumors (p = 0.014 for scatterer spacing, p = 0.035 for effective scatterer diameter). The separation of the tumor

  14. Probing Novel Properties of Nucleons and Nuclei via Parity Violating Electron Scattering

    Mercado, Luis [Univ. of Massachusetts, Amherst, MA (United States)

    2012-05-01

    This thesis reports on two experiments conducted by the HAPPEx (Hall A Proton Parity Experiment) collaboration at the Thomas Jefferson National Accelerator Facility. For both, the weak neutral current interaction (WNC, mediated by the Z0 boson) is used to probe novel properties of hadronic targets. The WNC interaction amplitude is extracted by measuring the parity-violating asymmetry in the elastic scattering of longitudinally polarized electrons o unpolarized target hadrons. HAPPEx-III, conducted in the Fall of 2009, used a liquid hydrogen target at a momentum transfer of Q2 = 0.62 GeV2. The measured asymmetry was used to set new constraints on the contribution of strange quark form factors (GsE,M ) to the nucleon electromagnetic form factors. A value of APV = -23.803±} 0.778 (stat)± 0.359 (syst) ppm resulted in GsE + 0.517GsM = 0.003± 0.010 (stat)± 0.004 (syst)± 0.009 (FF). PREx, conducted in the Spring of 2010, used a polarized electron beam on a 208Pb target at a momentum transfer of Q2 = 0.009 GeV2. This parity-violating asymmetry can be used to obtain a clean measurement of the root-mean-square radius of the neutrons in the 208Pb nucleus. The Z0 boson couples mainly to neutrons; the neutron weak charge is much larger than that of the proton. The value of this asymmetry is at the sub-ppm level and has a projected experimental fractional precision of 3%. We will describe the accelerator setup used to set controls on helicity-correlated beam asymmetries and the analysis methods for finding the raw asymmetry for HAPPEx-III. We will also discuss in some detail the preparations to meet the experimental challenges associated with measuring such a small asymmetry with the degree of precision required for PREx.

  15. The Scattering Properties of Natural Terrestrial Snows versus Icy Satellite Surfaces

    Domingue, Deborah; Hartman, Beth; Verbiscer, Anne

    1997-01-01

    Our comparisons of the single particle scattering behavior of terrestrial snows and icy satellite regoliths to the laboratory particle scattering measurements of McGuire and Hapke demonstrate that the differences between icy satellite regoliths and their terrestrial counterparts are due to particle structures and textures. Terrestrial snow particle structures define a region in the single particle scattering function parameter space separate from the regions defined by the McGuire and Hapke artificial laboratory particles. The particle structures and textures of the grains composing icy satellites regoliths are not simple or uniform but consist of a variety of particle structure and texture types, some of which may be a combination of the particle types investigated by McGuire and Hapke.

  16. Directive properties of active coated nano-particles

    Arslanagic, Samel; Ziolkowski, W.

    2012-01-01

    and optical gain constant on the directivities. While significant variations in the directivities are realized in the cylindrical cases for different source locations within and slightly outside the nano-particles and values of the optical gain constant, the corresponding spherical cases exhibit negligible...

  17. An investigation of the direct compression properties of pre ...

    ADOWIE PERE

    cultivated in times of food scarcity or famine as a result of scarcity of other ... Cassava is the third largest source of food ..... dissolution fluid was withdrawn and replaced with an ..... compression and mechanical properties of ibuprofen tablets.

  18. The study of the structural properties of very low viscosity sodium alginate by small-angle neutron scattering

    Badita, C. R., E-mail: ramona@tandem.nipne.ro [Horia Hulubei National Institute of Physics and Nuclear Engineering, Reactorului 30, RO-077125, POB-MG6, Magurele-Bucharest, Romania, ramona@tandem.nipne.ro, daranghe@nipne.ro (Romania); University of Bucharest, Faculty of Physics, Atomiştilor 405, CP MG - 11, RO – 077125, Bucharest-Magurele (Romania); Aranghel, D., E-mail: daranghe@nipne.ro [Horia Hulubei National Institute of Physics and Nuclear Engineering, Reactorului 30, RO-077125, POB-MG6, Magurele-Bucharest, Romania, ramona@tandem.nipne.ro, daranghe@nipne.ro (Romania); Extreme Light Intrastructure Nuclear Physics (ELI-NP), Reactorului 30, RO-077125, POB-MG6, Magurele-Bucharest (Romania); Radulescu, A. [Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science, 85747 Garching (Germany); Anitas, E. M. [Horia Hulubei National Institute of Physics and Nuclear Engineering, Reactorului 30, RO-077125, POB-MG6, Magurele-Bucharest, Romania, ramona@tandem.nipne.ro, daranghe@nipne.ro (Romania); Joint Institute for Nuclear Research, 141980 Dubna, Moscow region (Russian Federation)

    2016-03-25

    Sodium alginate is a linear polymer extract from brown algae and it is used in the biomedical, food, cosmetics and pharmaceutical industries as solution property modifiers and gelling agents. But despite the extensive studies of the alginate gelation process, still some fundamental questions remain unresolved. The fractal behavior of very low viscosity sodium alginate solutions and their influence on the critical gelation of alginate induced by Ca{sup 2+} ions were investigated using Small-Angle Neutron Scattering (SANS) measurements. SANS data are interpreted using both standard linear plots and the Beaucage model. The scattering intensity is dependent by alginate concentration and Ca{sup 2+} concentration. From a critical concentration of 1.0 % w/w our polymer swelled forming spherical structures with rough surfaces. Also the addition of the salt induces the collapse and the appearance of the aggregation and clusters formation.

  19. Evaluation of light scattering properties and chromophore concentrations in skin tissue based on diffuse reflectance signals at isosbestic wavelengths of hemoglobin

    Yokokawa, Takumi; Nishidate, Izumi

    2016-04-01

    We investigate a method to evaluate light-scattering properties and chromophore concentrations in human skin tissue through diffuse reflectance spectroscopy using the reflectance signals acquired at isosbestic wavelengths of hemoglobin (420, 450, 500, and 585 nm). In the proposed method, Monte Carlo simulation-based empirical formulas are used to specify the scattering parameters of skin tissue, such as the scattering amplitude a and the scattering power b, as well as the concentration of melanin C m and the total blood concentration C tb. The use of isosbestic wavelengths of hemoglobin enables the values of C m, C tb, a, and b to be estimated independently of the oxygenation of hemoglobin. The spectrum of the reduced scattering coefficient is reconstructed from the scattering parameters. Experiments using in vivo human skin tissues were performed to confirm the feasibility of the proposed method for evaluating the changes in scattering properties and chromophore concentrations in skin tissue. The experimental results revealed that light scattering is significantly reduced by the application of a glycerol solution, which indicates an optical clearing effect due to osmotic dehydration and the matching of the refractive indices of scatterers in the epidermis.

  20. Direct measurements of multi-photon induced nonlinear lattice dynamics in semiconductors via time-resolved x-ray scattering.

    Williams, G Jackson; Lee, Sooheyong; Walko, Donald A; Watson, Michael A; Jo, Wonhuyk; Lee, Dong Ryeol; Landahl, Eric C

    2016-12-22

    Nonlinear optical phenomena in semiconductors present several fundamental problems in modern optics that are of great importance for the development of optoelectronic devices. In particular, the details of photo-induced lattice dynamics at early time-scales prior to carrier recombination remain poorly understood. We demonstrate the first integrated measurements of both optical and structural, material-dependent quantities while also inferring the bulk impulsive strain profile by using high spatial-resolution time-resolved x-ray scattering (TRXS) on bulk crystalline gallium arsenide. Our findings reveal distinctive laser-fluence dependent crystal lattice responses, which are not described by previous TRXS experiments or models. The initial linear expansion of the crystal upon laser excitation stagnates at a laser fluence corresponding to the saturation of the free carrier density before resuming expansion in a third regime at higher fluences where two-photon absorption becomes dominant. Our interpretations of the lattice dynamics as nonlinear optical effects are confirmed by numerical simulations and by additional measurements in an n-type semiconductor that allows higher-order nonlinear optical processes to be directly observed as modulations of x-ray diffraction lineshapes.

  1. Small angle neutron scattering studies of the vortex lattice in the UPt3 mixed state: Direct structural evidence for the B->C transition

    Yaron, U.; Gammel, P.L.; Boebinger, G.S.

    1997-01-01

    Small angle neutron scattering studies of the flux line lattice (FLL) in UPt3 for fields H perpendicular to c provide direct microscopic evidence for the 5 kOe B --> C transition. We find a pronounced maximum in the longitudinal correlation length of the FLL at the transition and an abrupt change...

  2. Effect of spin-orbit scattering on transport properties of low-dimensional dilute alloys

    Heers, Swantje

    2011-09-21

    The scope of this thesis is to gain insight, by means of ab initio-calculations, into the physics of momentum and spin relaxation phenomena induced by electron scattering at impurities and defects in the noble metals copper, silver and gold. The main results are subdivided in three parts. In the first part, momentum- and spinrelaxation times due to scattering at 3d, 4sp, 4d, 5sp, 5d and 6sp impurities in copper and gold fcc bulk are investigated. The inversion symmetry of the crystals leads to a two-fold degeneracy of all states on the Fermi surface, and therefore spin relaxation is dominated by the Elliott-Yafet mechanism as well as the spin-orbit coupling of the impurity. For impurities in gold, we calculate much shorter spin-relaxation times than in copper because of the stronger spin-orbit coupling of the gold host. Furthermore, we have found important qualitative differences between the relaxation times obtained for the d- and the sp- impurities. As scattering at d-impurities is resonant, the electrons spend much more time at the impurity sites than in the case of the sp-impurities; therefore, they are much longer exhibited to the spin-orbit coupling of the impurity. This results in considerably shorter spin-relaxation times, even if the momentum scattering rates are in the same order of magnitude. Finally, the investigation of interference of scattering processes at impurity dimers reveals that relevant differences to the independent-impurity approximation appear only for strong d-scatterer, placed at nearest neighboring sites. In the second part we investigate the reduction of spin-conserving surface-state lifetimes induced by adatom- and impurity-scattering on the (111) surfaces of copper, silver and gold films with different thicknesses. We have found strong qualitative differences in the lifetimes when comparing the results for adatoms to those of impurities in the first and second layer. The trends for the latter ones are similar to those calculated in

  3. Study of a new approach to diagnose breast cancer based on synchrotron radiation scattering properties

    Conceicao, A.L.C.; Poletti, M.E.

    2012-01-01

    Full text: Breast cancer is the most frequently occurring cancer in women accounting for about 20% of all cancer deaths. This scenario is, among other factors, due to inherent limitations of the current clinical methods of diagnosis based on x-ray absorption. Meanwhile, recent researches have shown that the scattered radiation can provide information about the structures that compose a biological tissue, like breast tissue. Then, the information provided by x-ray scattering techniques can be used to identify breast cancer. In this work, we developed a classification model based on discriminant analysis of scattering profiles of 106 human breast samples histopathologically classified as normal tissue, benign and malignant lesion, at wide (WAXS) and small angle x-ray scattering (SAXS) regions. WAXS and SAXS experiments were carried out at the D12A-XRD1 and D02-SAXS2 beam lines in the National Synchrotron Light Laboratory (LNLS) in Campinas. For WAXS experiment, was used an x-ray beam energy of 11keV allowing to record the momentum transfer interval of 0.7nm -1 ≤(q=4π.sin(θ/2)/λ)≤70.5nm -1 on the NaI(Tl) detector. While for SAXS experiment was used an x-ray wavelength of 1.488 Angstrom, a two-dimensional detector and several sample-detector distances, allowing to get the range of 0.07nm -1 ≤q≤4.20nm -1 . The scattering profiles at both regions, for each sample were used to build the diagnosis model based on discriminant analysis. From WAXS data, differences related to position and intensity of the peaks of the molecular structures were found, when compared normal and pathological breast tissues. While for SAXS these differences were observed in supramolecular structures. The diagnostic model combining the information at WAXS and SAXS yield two linear functions which, allow to correlate changes at molecular scale with those at supramolecular level as well as, to classify correctly all samples analyzed in this study[1]. Finally, the results achieved in this

  4. Influence of diffuse reflectance measurement accuracy on the scattering coefficient in determination of optical properties with integrating sphere optics (a secondary publication).

    Horibe, Takuro; Ishii, Katsunori; Fukutomi, Daichi; Awazu, Kunio

    2015-12-30

    An estimation error of the scattering coefficient of hemoglobin in the high absorption wavelength range has been observed in optical property calculations of blood-rich tissues. In this study, the relationship between the accuracy of diffuse reflectance measurement in the integrating sphere and calculated scattering coefficient was evaluated with a system to calculate optical properties combined with an integrating sphere setup and the inverse Monte Carlo simulation. Diffuse reflectance was measured with the integrating sphere using a small incident port diameter and optical properties were calculated. As a result, the estimation error of the scattering coefficient was improved by accurate measurement of diffuse reflectance. In the high absorption wavelength range, the accuracy of diffuse reflectance measurement has an effect on the calculated scattering coefficient.

  5. Optimization of surface morphology and scattering properties of TCO/AIT textured glass front electrode for thin film solar cells

    Addonizio, M.L., E-mail: marialuisa.addonizio@enea.it; Fusco, L.; Antonaia, A.; Cominale, F.; Usatii, I.

    2015-12-01

    Graphical abstract: - Highlights: • Aluminium induced texture (AIT) method has been used for obtaining highly textured glass substrates. • The effect of wet etch step on morphological and optical properties has been analyzed. • The morphology features have been optimized in order to obtain the best scattering properties. • Different ZnO surface textures, depending on the underlying glass substrate structures, are obtained. • The effect of different glass texture on optical confinement has been tested in a-Si:H devices. - Abstract: Aluminium induced texture (AIT) method has been used for obtaining highly textured glass substrate suitable for silicon based thin film solar cell technology. Wet etch step parameters of AIT process have been varied and effect of different etchants and different etching times on morphological and optical properties has been analyzed. The resulting morphology features (shape, size distribution, inclination angle) have been optimized in order to obtain the best scattering properties. ZnO:Ga (GZO) films have been deposited by sputtering technique on AIT-processed glass. Two different ZnO surface morphologies have been obtained, strongly depending on the underlying glass substrate morphology induced by different etching times. Very rough and porous texture (σ{sub rms} ∼ 150 nm) was obtained on glass etched 2 min showing cauliflower-like structure, whereas a softer texture (σ{sub rms} ∼ 78 nm) was obtained on glass etched 7 min giving wider and smoother U-shaped craters. The effect of different glass textures on optical confinement has been tested in amorphous silicon based p-i-n devices. Devices fabricated on GZO/high textured glass showed a quantum efficiency enhancement due to both an effective light trapping phenomenon and an effective anti-reflective optical behaviour. Short etching time produce smaller cavities (<1 μm) with deep U-shape characterized by high roughness, high inclination angle and low autocorrelation

  6. Properties of surfactant films in water-in-CO2 microemulsions obtained by small-angle neutron scattering.

    Yan, Ci; Sagisaka, Masanobu; James, Craig; Rogers, Sarah; Alexander, Shirin; Eastoe, Julian

    2014-12-01

    The formation, stability and structural properties of normal liquid phase microemulsions, stabilized by hydrocarbon surfactants, comprising water and hydrocarbon oils can be interpreted in terms of the film bending rigidity (energy) model. Here, this model is tested for unusual water-in-CO2 (w/c) microemulsions, formed at high pressure with supercritical CO2 (sc-CO2) as a solvent and fluorinated surfactants as stabilizers. Hence, it is possible to explore the generality of this model for other types of microemulsions. High Pressure Small-Angle Neutron Scattering (HP-SANS) has been used to study w/c microemulsions, using contrast variation to highlight scattering from the stabilizing fluorinated surfactant films: these data show clear evidence for spherical core-shell structures for the microemulsion droplets. The results extend understanding of w/c microemulsions since previous SANS studies are based only on scattering from water core droplets. Here, detailed structural parameters for the surfactant films, such as thickness and film bending energy, have been extracted from the core-shell SANS profiles revealed by controlled contrast variation. Furthermore, at reduced CO2 densities (∼0.7gcm(-3)), elongated cylindrical droplet structures have been observed, which are uncommon for CO2 microemulsions/emulsions. The implications of the presence of cylindrical micelles and droplets for applications of CO2, and viscosity enhancements are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Possibilities for direct optical observation of negative hydrogen ions in ion beam plasma sources via Rayleigh or Thomson scattering

    Burgess, D.D.

    1985-01-01

    The possibilities of applying optical scattering techniques to the determination of H - concentrations in plasma sources relevant to negative ion beam generation are considered. Rayleigh scattering measurements for incident wavelengths just below the H - photoionization limit appear to be only just feasible experimentally. A more promising possibility is observation of the modification in a plasma containing negative ions of the collective ion-feature in Thomson scattering. Numerical predictions of the effects of H - concentration on the spectral distribution of the ion-feature are presented. (author)

  8. Implications of changing scattering properties on Greenland ice sheet volume change from Cryosat-2 altimetry

    Simonsen, Sebastian Bjerregaard; Sørensen, Louise Sandberg

    2017-01-01

    ) in the elevation change algorithm, to correct for temporal changes in the ratio between surface- and volume-scatter in Cryosat-2 observations. We present elevation and volume changes for the Greenland ice sheet in the period from 2010 until 2014. The waveform parameters considered here are the backscatter...... waveform parameters to be applicable for correcting for changes in volume scattering. The best results in the Synthetic Aperture Radar Interferometric mode area of the GrIS are found when applying only the backscatter correction, whereas the best result in the Low Resolution Mode area is obtained by only......Long-term observations of surface elevation change of the Greenland ice sheet (GrIS) is of utmost importance when assessing the state of the ice sheet. Satellite radar altimetry offers a long time series of data over the GrIS, starting with ERS-1 in 1991. ESA's Cryosat-2 mission, launched in 2010...

  9. Neutron scattering. Lectures

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  10. Neutron scattering. Lectures

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

    2010-01-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  11. Multiphase polymer systems: morphology and optical properties by light scattering methods

    Holoubek, Jaroslav

    2002-01-01

    Roč. 18, 5-6 (2002), s. 286-292 ISSN 0934-0866 R&D Projects: GA ČR GA203/99/0573; GA AV ČR IAA4050902 Institutional research plan: CEZ:AV0Z4050913 Keywords : time-resolved light scattering * diffuse reflectance * phase dissolution Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.633, year: 2002

  12. A review on the study of polymer properties by Small Angle Neutron Scattering

    Seong, Baek Seok; Lee, Chang Hee; Sim, Hae Seop; Lee, Jung Sool; Kim, Hong Doo; Kim, Eu Gene; Cha, Kuk Heon

    1998-05-01

    This report contains concept of small angle neutron scattering , various design features and considerations of the small angle neutron spectrometer at HANARO, and recent trends of polymer studies by using this SANS technique with the installation of the spectrometer in near future. We, therefore, wish to review feasibility of small angle studies for polymer field at this spectrometer and to help possible beam time users for their experimental consideration. (author). 23 refs., 7 tabs., 23 figs

  13. Enforcement of Intellectual Property, Pollution Abatement, and Directed Technical Change

    Schaefer, Andreas

    2017-01-01

    We theoretically investigate the interaction between endogenous enforcement of intellectual property rights (IPRs) and tax-financed pollution abatement measures. IPRs affect dirty and clean intermediates alike such that higher IPR enforcement may promote the transition to the clean technology, if this technology is productive enough. If the green technology is relatively unproductive, higher IPRs promote the dirty technology while pollution is increasing. As households are due to subsistence ...

  14. Direct determination of the resonance properties of metallic conical nanoantennas

    Tuccio, Salvatore; Razzari, Luca; Alabastri, Alessandro; Toma, Andrea; Liberale, Carlo; De Angelis, Francesco De; Candeloro, Patrizio; Das, Gobind; Giugni, Andrea; Di Fabrizio, Enzo M.; Proietti Zaccaria, Remo

    2014-01-01

    We present a simple method that is able to predict the resonant frequencies of a metallic conical nanoantenna. The alculation is based on an integral relation that takes into account the dependence of the effective refractive index of the plasmonic mode on the cone radius. Numerical simulations retrieving the near field properties of nanocones with different lengths are also performed for comparison. The fine agreement between the two approaches demonstrates the validity of our method. © 2014 Optical Society of America.

  15. Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

    Escobar-Cerezo, J.; Palmer, C.; Muñoz, O.; Moreno, F.; Penttilä, A.; Muinonen, K.

    2017-01-01

    The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected to mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.

  16. Light Scattering Tests of Fundamental Theories of Transport Properties in the Critical Region

    Gammon, R. W.; Moldover, M. R.

    1985-01-01

    The objective of this program is to measure the decay rates of critical density fluctuations in a simple fluid (xenon) very near its liquid-vapor critical point using laser light scattering and photon correlation spectroscopy. Such experiments have been severely limited on Earth by the presence of gravity which causes large density gradients in the sample when the compressibility diverges approaching the critical point. The goal is to measure decay rates deep in the critical region where the scaled wavevector is the order of 1000. This will require loading the sample to 0.01% of the critical density and taking data as close as 3 microKelvin to the critical temperature (Tc = 289.72 K). Other technical problems have to be addressed such as multiple scattering and the effect of wetting layers. The ability to avoid multiple scattering by using a thin sample (100 microns) was demonstrated, as well as a temperature history which can avoid wetting layers satisfactory temperature control and measurement, and accurate sample loading. Thus the questions of experimental art are solved leaving the important engineering tasks of mounting the experiment to maintain alignment during flight and automating the state-of-the-art temperature bridges for microcomputer control of the experiment.

  17. Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

    Escobar-Cerezo, J.; Palmer, C.; Muñoz, O.; Moreno, F. [Instituto de Astrofìsica de Andalucìa, CSIC, Glorieta de la Astronomìa s/n, E-18008 Granada (Spain); Penttilä, A.; Muinonen, K. [Department of Physics, P.O. Box 64, FI-00014 University of Helsinki (Finland)

    2017-03-20

    The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected to mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.

  18. Solar Wind Halo Formation by the Scattering of the Strahl via Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function

    Figueroa-Vinas, Adolfo; Gurgiolo, Chris A.; Nieves-Chinchilla, Teresa; Goldstein, Melvyn L.

    2010-01-01

    It has been suggested by a number of authors that the solar wind electron halo can be formed by the scattering of the strahl. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions) a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a very limited energy range. When the magnetic field is well off the nominal solar wind flow direction such filaments are inconsistent with any local forces and are probably the result of strong scattering. Furthermore, observations indicates that the strahl component is frequently and significantly anisotropic (Tper/Tpal approx.2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component.

  19. Studies of the underlying-event properties and of hard double parton scattering with the ATLAS detector

    AUTHOR|(INSPIRE)INSPIRE-00173407; The ATLAS collaboration

    2018-01-01

    A correct modelling of the underlying event in proton-proton collisions at Large Hadron Collider is important for the proper simulation of kinematic distributions of final state objects. The ATLAS collaboration performed a study at 13 TeV, measuring the number and transverse-momentum sum of charged particles in different regions with respect to the direction of the reconstructed leading track. These measurements are sensitive to the underlying-event activity. The results are compared to predictions of several Monte Carlo generators. Inclusive four-jet events produced in proton-proton collisions at a centre-of-mass energy of 7 TeV in the ATLAS detector have been analysed for the presence of hard double parton scattering. The fraction of events originating from hard double parton scattering has been extracted, and used to measure the effective proton cross section. Distributions sensitive to the presence of double parton scattering were unfolded to the parton level and compared to various tunes of a selected Mo...

  20. Direct measurements of transport properties are essential for site characterization

    Wright, J.; Conca, J.L.

    1994-08-01

    Direct measurements of transport parameters on subsurface sediments using, the UFA method provided detailed hydrostratigraphic mapping, and subsurface flux distributions at a mixed-waste disposal site at Hanford. Seven hundred unsaturated conductivity measurements on fifty samples were obtained in only six months total of UFA run time. These data are used to provide realistic information to conceptual models, predictive models and restoration strategies. The UFA instrument consists of an ultracentrifuge with a constant, ultralow flow pump that provides fluid to the sample surface through a rotating seal assembly and microdispersal system. Effluent from the sample is collected in a transparent, volumetrically-calibrated chamber at the bottom of the sample assembly. Using a strobe light, an observer can check the chamber while the sample is being centrifuged. Materials can be run in the UFA as recomposited samples or in situ samples can be subcored directly into the sample UFA chamber

  1. Characterization of Direct Piezoelectric Properties for Vibration Energy Harvesting

    Yoshimura, Takeshi; Miyabuchi, Hiroki; Ashida, Atsushi; Fujimura, Norifumi [Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531 (Japan); Murakami, Syuichi, E-mail: tyoshi@pe.osakafu-u.ac.jp [Technology Research Institute of Osaka Prefecture, 2-7-1 Ayumino, Izumi, Osaka, 594-1157 (Japan)

    2011-10-29

    Direct piezoelectric effect of Pb(Zr,Ti)O{sub 3} (PZT) thin films was investigated to discuss the application of ferroelectric films to vibration energy harvesting. From the model of the piezoelectric vibration energy harvester, it was found that the figure of merit (FOM) is proportional of the square of the effective transverse piezoelectric coefficient e{sub 31,f}. The e{sub 31,f} coefficient of PZT films were measured by substrate bending method. Furthermore, it was found that the e{sub 31,f} coefficient increases with increasing strain, which is favourable for the vibration energy harvesting.

  2. Steady-state properties of Josephson junctions with direct conductivity

    Zubkov, A.A.; Kupriyanov, M.Y.; Semenov, V.K.

    1981-01-01

    A new criterion for determining the kinetic inductance of Josephson junctions is introduced. The effects of temperature T, the critical temperatures of the superconducting electrodes T/sub c/1 and T/sub c/2, and the weak-link length on the kinetic inductance of ''dirty'' junctions with direct conductivity are analyzed within the framework of the Usadel equations. Numerical calculations show that both a large characteristic voltage and a nearly harmonic dependence of the current on the phase difference of the superconducting-electrode wave functions cannot be obtained by varying the junction parameters

  3. Continental pollution in the Western Mediterranean basin: large variability of the aerosol single scattering albedo and influence on the direct shortwave radiative effect

    C. Di Biagio

    2016-08-01

    Full Text Available Pollution aerosols strongly influence the composition of the Western Mediterranean basin, but at present little is known on their optical properties. We report in this study in situ observations of the single scattering albedo (ω of pollution aerosol plumes measured over the Western Mediterranean basin during the TRAQA (TRansport and Air QuAlity airborne campaign in summer 2012. Cases of pollution export from different source regions around the basin and at different altitudes between  ∼  160 and 3500 m above sea level were sampled during the flights. Data from this study show a large variability of ω, with values between 0.84–0.98 at 370 nm and 0.70–0.99 at 950 nm. The single scattering albedo generally decreases with the wavelength, with some exception associated to the mixing of pollution with sea spray or dust particles over the sea surface. The lowest values of ω (0.84–0.70 between 370 and 950 nm are measured in correspondence of a fresh plume possibly linked to ship emissions over the basin. The range of variability of ω observed in this study seems to be independent of the source region around the basin, as well as of the altitude and aging time of the plumes. The observed variability of ω reflects in a large variability for the complex refractive index of pollution aerosols, which is estimated to span in the large range 1.41–1.77 and 0.002–0.097 for the real and the imaginary parts, respectively, between 370 and 950 nm. Radiative calculations in clear-sky conditions were performed with the GAME radiative transfer model to test the sensitivity of the aerosol shortwave Direct Radiative Effect (DRE to the variability of ω as observed in this study. Results from the calculations suggest up to a 50 and 30 % change of the forcing efficiency (FE, i.e. the DRE per unit of optical depth, at the surface (−160/−235 W m−2 τ−1 at 60° solar zenith angle and at the Top-Of-Atmosphere (−137/−92

  4. Dynamic light scattering. Observation of polymer dynamics

    Hiroi, Takashi

    2015-01-01

    Dynamic light scattering is a technique to measure properties of polymer solutions such as size distribution. Principle of dynamic light scattering is briefly explained. Sometime dynamic light scattering is regarded as the observation of Doppler shift of scattered light. First, the difficulty for the direct observation of this Doppler shift is mentioned. Then the measurement by using a time correlation function is introduced. Measuring techniques for dynamic light scattering are also introduced. In addition to homodyne and heterodyne detection techniques, the technique called partial heterodyne method is also introduced. This technique is useful for the analysis of nonergodic medium such as polymer gels. Then the application of this technique to condensed suspension is briefly reviewed. As one of the examples, a dynamic light scattering microscope is introduced. By using this apparatus, we can measure the concentration dependence of the size distribution of polymer solutions. (author)

  5. Simultaneous Retrieval of Aerosol and Surface Optical Properties from Combined Airborne- and Ground-Based Direct and Diffuse Radiometric Measurements

    Gatebe, C. K.; Dubovik, O.; King, M. D.; Sinyuk, A.

    2010-01-01

    This paper presents a new method for simultaneously retrieving aerosol and surface reflectance properties from combined airborne and ground-based direct and diffuse radiometric measurements. The method is based on the standard Aerosol Robotic Network (AERONET) method for retrieving aerosol size distribution, complex index of refraction, and single scattering albedo, but modified to retrieve aerosol properties in two layers, below and above the aircraft, and parameters on surface optical properties from combined datasets (Cloud Absorption Radiometer (CAR) and AERONET data). A key advantage of this method is the inversion of all available spectral and angular data at the same time, while accounting for the influence of noise in the inversion procedure using statistical optimization. The wide spectral (0.34-2.30 m) and angular range (180 ) of the CAR instrument, combined with observations from an AERONET sunphotometer, provide sufficient measurement constraints for characterizing aerosol and surface properties with minimal assumptions. The robustness of the method was tested on observations made during four different field campaigns: (a) the Southern African Regional Science Initiative 2000 over Mongu, Zambia, (b) the Intercontinental Transport Experiment-Phase B over Mexico City, Mexico (c) Cloud and Land Surface Interaction Campaign over the Atmospheric Radiation Measurement (ARM) Central Facility, Oklahoma, USA, and (d) the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) over Elson Lagoon in Barrow, Alaska, USA. The four areas are dominated by different surface characteristics and aerosol types, and therefore provide good test cases for the new inversion method.

  6. Direct measurement of nonlinear properties of bipartite quantum states.

    Bovino, Fabio Antonio; Castagnoli, Giuseppe; Ekert, Artur; Horodecki, Paweł; Alves, Carolina Moura; Sergienko, Alexander Vladimir

    2005-12-09

    Nonlinear properties of quantum states, such as entropy or entanglement, quantify important physical resources and are frequently used in quantum-information science. They are usually calculated from a full description of a quantum state, even though they depend only on a small number of parameters that specify the state. Here we extract a nonlocal and a nonlinear quantity, namely, the Renyi entropy, from local measurements on two pairs of polarization-entangled photons. We also introduce a "phase marking" technique which allows the selection of uncorrupted outcomes even with nondeterministic sources of entangled photons. We use our experimental data to demonstrate the violation of entropic inequalities. They are examples of nonlinear entanglement witnesses and their power exceeds all linear tests for quantum entanglement based on all possible Bell-Clauser-Horne-Shimony-Holt inequalities.

  7. Non-Linear Rheological Properties and Neutron Scattering Investigation on Dilute Ring-Linear Blends

    Pyckhout-Hintzen, W.; Bras, A.R.; Wischnewski, A.

    in a filament stretching rheometer, followed by quenching, strong anisotropic scattering patterns were obtained which were described by affinely deformed rings which function as giant, polymeric chemical crosslinks or sliplinks and more or less isotropic topological contributions from the entangling...... with interpenetrating linear chains. At the same time the non-linear rheological and mechanical data fit to a non-affine slip-tube model as for moderately crosslinked networks and to interchain pressure models or a modified non-linear Doi-Edwards description for the observed strain hardening during the extensional...

  8. Real Estate Crowdfunding. A financial innovation for direct property investment

    Giacomo Morri

    2016-12-01

    Full Text Available The aim of this work is to provide a simple overview on crowdfunding with a focus on its potential application to the real estate market. The Global Financial Crisis of 2008 paralyzed the global economy, creating a strong diminishing trust in financial services and in the banking system in general. One of the most revolutionary systems to get funded in the market has been crowdfunding, a way of financing coming directly from the crowd through the Internet. Crowdfunding in real estate started in 2012 with the Jumpstart Our Business Startup Act (JOBS Act in USA and has been developing at a fast rate every year. In Italy, crowdfunding for real estate projects is not allowed yet, but there are various platforms that are already using the concept in different ways. Real Estate Crowdfunding could represent an interesting opportunity for private individual to have an exposure to direct real estate investments. After an initial description of crowdfunding in general, we present real estate crowdfunding in the U.S. by presenting the most relevant cases up to date. Finally, we analyze the Italian market by explaining why this innovative way of financing real estate projects is not feasible yet and how some platforms are legally trying to overcome the current limitations. In the U.S. the RECF has already raised more than $1 billion and there are more than 125 platforms; in Italy there are still limits for startups dealing with crowdfunding and a few platforms are starting to operate with a similar model.

  9. Scattering properties of textured TCO substrates in thin-film silicon solar cells; Streuverhalten von texturierten TCO-Substraten in Silizium-Duennschichtsolarzellen

    Schulte, Melanie

    2009-04-27

    In this PhD thesis the scattering properties of textured transparent conducting oxides (TCO) for the application in thin-film silicon solar cells are investigated. The main focus is the correlation between the nanotextured surface and its scattering behaviour. Therefore a ray tracing model based on geometric optics and atomic force microscopy data is developed. Simulation results are compared and discussed with measurements of angle resolved scattering in the far field and experimentally determined scanning near field microscopy data in the near field. Besides, simulation results obtained by applying geometric optics and solutions of the Maxwell equation in the near field are compared and discussed. The scattering properties of TCO-air and TCO-silicon interfaces are considered. (orig.)

  10. Single-scattering properties of ice particles in the microwave regime: Temperature effect on the ice refractive index with implications in remote sensing

    Ding, Jiachen; Bi, Lei; Yang, Ping; Kattawar, George W.; Weng, Fuzhong; Liu, Quanhua; Greenwald, Thomas

    2017-01-01

    An ice crystal single-scattering property database is developed in the microwave spectral region (1 to 874 GHz) to provide the scattering, absorption, and polarization properties of 12 ice crystal habits (10-plate aggregate, 5-plate aggregate, 8-column aggregate, solid hexagonal column, hollow hexagonal column, hexagonal plate, solid bullet rosette, hollow bullet rosette, droxtal, oblate spheroid, prolate spheroid, and sphere) with particle maximum dimensions from 2 µm to 10 mm. For each habit, four temperatures (160, 200, 230, and 270 K) are selected to account for temperature dependence of the ice refractive index. The microphysical and scattering properties include projected area, volume, extinction efficiency, single-scattering albedo, asymmetry factor, and six independent nonzero phase matrix elements (i.e. P_1_1, P_1_2, P_2_2, P_3_3, P_4_3 and P_4_4). The scattering properties are computed by the Invariant Imbedding T-Matrix (II-TM) method and the Improved Geometric Optics Method (IGOM). The computation results show that the temperature dependence of the ice single-scattering properties in the microwave region is significant, particularly at high frequencies. Potential active and passive remote sensing applications of the database are illustrated through radar reflectivity and radiative transfer calculations. For cloud radar applications, ignoring temperature dependence has little effect on ice water content measurements. For passive microwave remote sensing, ignoring temperature dependence may lead to brightness temperature biases up to 5 K in the case of a large ice water path. - Highlights: • Single-scattering properties of ice crystals are computed from 1 to 874 GHz. • Ice refractive index temperature dependence is considered at 160, 200, 230 and 270 K. • Potential applications of the database to microwave remote sensing are illustrated. • Ignoring temperature dependence of ice refractive index can lead to 5 K difference in IWP retrieval

  11. Evaluation and Future Direction of Intellectual Property Strategy - Setting out a new intellectual property policy - (Japanese)

    KUGAI Takashi

    2010-01-01

    1. An intellectual property strategy is a policy aimed at improving the international competitiveness of industry and reinvigorating the economy through the creation, protection, and greater use of intellectual property. 2. The realization of IP policies conventionally considered difficult to implement and greater awareness of intellectual property at all levels of society, as demonstrated the establishment of Intellectual Property High Courts that exclusively and solely handle intellectual p...

  12. The structural and magnetic properties of Fe/native-oxide systems resolved by x-ray scattering and spectroscopy methods

    Couet, Sebastien

    2008-12-01

    Since the discovery of the giant magnetoresistance (GMR) effect in metallic magnetic multilayers and its industrial application in magnetic read heads, the data storage density and reading speed of hard disks steadily increased. But now the point is reached where conventional conductive multilayer structures suffer from parasitic eddy currents which decrease the signal to noise ratio of the system. To tackle this problem, new classes of materials have to be studied. One approach is to introduce ultra thin oxide layers in a metallic iron structure to reduce the conductivity while keeping a high net magnetization. This can be achieved by alternating metal deposition and controlled oxidation to produce metal/metal-oxide multilayers. However, the magnetic structure that forms in such multilayer is still rather unexplored. The aim of this work was to achieve a better understanding of the magnetic structure that forms in such iron/native-oxide multilayers. For that purpose, X-ray and neutron scattering experiments were carried out to determine the magnetic structure and its evolution in ex-situ and in-situ experiments, respectively. It was found that a non-collinear magnetic coupling appears between the metal layers, which is mediated by the antiferromagnetically ordered oxide layer in between. The use of isotope sensitive scattering techniques (namely nuclear resonant scattering and neutron reflectometry) allowed to resolve the magnetic depth profile of the system, showing that the buried oxide carries a net magnetic moment. The chemical and magnetic structure of the buried oxide was studied by in-situ X-ray absorption spectroscopy and nuclear resonant scattering. After oxidation, the layer exhibits a mixture of different oxide phases and incorporates 10 to 15% of Fe with metallic character. Upon deposition of only one atomic layer of metallic Fe, the layer reduces to a single phase FeO-like oxide. This structural change does not lead to a magnetically ordered oxide

  13. The structural and magnetic properties of Fe/native-oxide systems resolved by x-ray scattering and spectroscopy methods

    Couet, Sebastien

    2008-12-15

    Since the discovery of the giant magnetoresistance (GMR) effect in metallic magnetic multilayers and its industrial application in magnetic read heads, the data storage density and reading speed of hard disks steadily increased. But now the point is reached where conventional conductive multilayer structures suffer from parasitic eddy currents which decrease the signal to noise ratio of the system. To tackle this problem, new classes of materials have to be studied. One approach is to introduce ultra thin oxide layers in a metallic iron structure to reduce the conductivity while keeping a high net magnetization. This can be achieved by alternating metal deposition and controlled oxidation to produce metal/metal-oxide multilayers. However, the magnetic structure that forms in such multilayer is still rather unexplored. The aim of this work was to achieve a better understanding of the magnetic structure that forms in such iron/native-oxide multilayers. For that purpose, X-ray and neutron scattering experiments were carried out to determine the magnetic structure and its evolution in ex-situ and in-situ experiments, respectively. It was found that a non-collinear magnetic coupling appears between the metal layers, which is mediated by the antiferromagnetically ordered oxide layer in between. The use of isotope sensitive scattering techniques (namely nuclear resonant scattering and neutron reflectometry) allowed to resolve the magnetic depth profile of the system, showing that the buried oxide carries a net magnetic moment. The chemical and magnetic structure of the buried oxide was studied by in-situ X-ray absorption spectroscopy and nuclear resonant scattering. After oxidation, the layer exhibits a mixture of different oxide phases and incorporates 10 to 15% of Fe with metallic character. Upon deposition of only one atomic layer of metallic Fe, the layer reduces to a single phase FeO-like oxide. This structural change does not lead to a magnetically ordered oxide

  14. Modeling single-scattering properties of small cirrus particles by use of a size-shape distribution of ice spheroids and cylinders

    Liu Li; Mishchenko, Michael I.; Cairns, Brian; Carlson, Barbara E.; Travis, Larry D.

    2006-01-01

    In this study, we model single-scattering properties of small cirrus crystals using mixtures of polydisperse, randomly oriented spheroids and cylinders with varying aspect ratios and with a refractive index representative of water ice at a wavelength of 1.88 μm. The Stokes scattering matrix elements averaged over wide shape distributions of spheroids and cylinders are compared with those computed for polydisperse surface-equivalent spheres. The shape-averaged phase function for a mixture of oblate and prolate spheroids is smooth, featureless, and nearly flat at side-scattering angles and closely resembles those typically measured for cirrus. Compared with the ensemble-averaged phase function for spheroids, that for a shape distribution of cylinders shows a relatively deeper minimum at side-scattering angles. This may indicate that light scattering from realistic cirrus crystals can be better represented by a shape mixture of ice spheroids. Interestingly, the single-scattering properties of shape-averaged oblate and prolate cylinders are very similar to those of compact cylinders with a diameter-to-length ratio of unity. The differences in the optical cross sections, single-scattering albedo, and asymmetry parameter between the spherical and the nonspherical particles studied appear to be relatively small. This may suggest that for a given optical thickness, the influence of particle shape on the radiative forcing caused by a cloud composed of small ice crystals can be negligible

  15. Uni-directional transport properties of a serpent billiard

    Horvat, Martin; Prosen, Tomaz

    2004-01-01

    We present a dynamical analysis of a classical billiard chain-a channel with parallel semi-circular walls, which can serve as a model for a bent optical fibre. An interesting feature of this model is the fact that the phase space separates into two disjoint invariant components corresponding to the left and right uni-directional motions. Dynamics is decomposed into the jump map, a Poincare map between the two ends of a basic cell, and the time function, travelling time across a basic cell of a point on a surface of section. The jump map has a mixed phase space where the relative sizes of the regular and chaotic components depend on the width of the channel. For a suitable value of this parameter, we can have almost fully chaotic phase space. We have studied numerically the Lyapunov exponents, time auto-correlation functions and diffusion of particles along the chain. As a result of the singularity of the time function, we obtain marginally normal diffusion after we subtract the average drift. The last result is also supported by some analytical arguments

  16. Scattering properties of vein induced localized surface plasmon resonances on a gold disk

    Amin, Muhammad

    2011-12-01

    It is demonstrated via simulations that a gold nano-disk with a non-concentric cavity supports localized surface plasmon resonances over a frequency band that includes the visible and the near-infrared parts of the spectrum. The charge distribution on the disk indicates that the two distinct peaks in the scattering cross section are due to the (hybridized) higher-order plasmon modes; plasmon hybridization that involves the dipole modes of the disk and the cavity enforces the "coupling" of the plane-wave excitation to the originally-dark higher-order modes. It is further demonstrated that the resonance frequencies can be tuned by varying the radius of the embedded non-concentric cavity. The near-field enhancement observed at these two tunable resonance frequencies suggests that the proposed structure can be used as a substrate in surface enhanced spectroscopy applications. © 2011 IEEE.

  17. Multi-property isotropic intermolecular potentials and predicted spectral lineshapes of collision-induced absorption (CIA), collision-induced light scattering (CILS) and collision-induced hyper-Rayleigh scattering (CIHR) for H2sbnd Ne, -Kr and -Xe

    El-Kader, M. S. A.; Godet, J.-L.; Gustafsson, M.; Maroulis, G.

    2018-04-01

    Quantum mechanical lineshapes of collision-induced absorption (CIA), collision-induced light scattering (CILS) and collision-induced hyper-Rayleigh scattering (CIHR) at room temperature (295 K) are computed for gaseous mixtures of molecular hydrogen with neon, krypton and xenon. The induced spectra are detected using theoretical values for induced dipole moment, pair-polarizability trace and anisotropy, hyper-polarizability and updated intermolecular potentials. Good agreement is observed for all spectra when the literature and the present potentials which are constructed from the transport and thermo-physical properties are used.

  18. Effect of various structure directing agents on the physicochemical properties of the silica aerogels prepared at an ambient pressure

    Sarawade, Pradip; Shao, Godlistennamwel; Quang, Dangviet; Kim, Heetaik

    2013-01-01

    We studied the effects of various surfactants on the textural properties (BET surface area, pore size, and pore volume) of the silica aerogels prepared at an ambient pressure. A simple surface modification of silica gel prepared at an ambient pressure through hydrolysis and polycondensation of TEOS as asilica precursor was conducted using various structure directing agents. The treatment was found to induce a significant difference in the porosity of the silica aerogel. Highly porous silica aerogels with bimodal porous structures were prepared by modifying the surface of the silica wet-gel (alcogel) with trimethylchlorosilane (TMCS) in order to preserve its porosity. The samples were analyzed by small-angle X-ray scattering and nitrogen adsorption. In this work, a possible new type of highly porous hydrophobic silica aerogel with a bimodal porous structure is presented. A hydrophilic extremely porous (high surface area and large pore volume) silica aerogel was obtained by heating the as-synthesized hydrophobic silica aerogel at 400°C for 1 h. There was a significant effect of structure directing agent on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the silicaaerogels. © 2013 Elsevier B.V. All rights reserved.

  19. Effect of various structure directing agents on the physicochemical properties of the silica aerogels prepared at an ambient pressure

    Sarawade, Pradip

    2013-12-01

    We studied the effects of various surfactants on the textural properties (BET surface area, pore size, and pore volume) of the silica aerogels prepared at an ambient pressure. A simple surface modification of silica gel prepared at an ambient pressure through hydrolysis and polycondensation of TEOS as asilica precursor was conducted using various structure directing agents. The treatment was found to induce a significant difference in the porosity of the silica aerogel. Highly porous silica aerogels with bimodal porous structures were prepared by modifying the surface of the silica wet-gel (alcogel) with trimethylchlorosilane (TMCS) in order to preserve its porosity. The samples were analyzed by small-angle X-ray scattering and nitrogen adsorption. In this work, a possible new type of highly porous hydrophobic silica aerogel with a bimodal porous structure is presented. A hydrophilic extremely porous (high surface area and large pore volume) silica aerogel was obtained by heating the as-synthesized hydrophobic silica aerogel at 400°C for 1 h. There was a significant effect of structure directing agent on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the silicaaerogels. © 2013 Elsevier B.V. All rights reserved.

  20. Relationship between electrical properties and crystallization of indium oxide thin films using ex-situ grazing-incidence wide-angle x-ray scattering

    González, G. B.; Okasinski, J. S.; Buchholz, D. B.; Boesso, J.; Almer, J. D.; Zeng, L.; Bedzyk, M. J.; Chang, R. P. H.

    2017-05-01

    Grazing-incidence, wide-angle x-ray scattering measurements were conducted on indium oxide thin films grown on silica substrates via pulsed laser deposition. Growth temperatures (TG) in this study ranged from -50 °C to 600 °C, in order to investigate the thermal effects on the film structure and its spatial homogeneity, as well as their relationship to electrical properties. Films grown below room temperature were amorphous, while films prepared at TG = 25 °C and above crystallized in the cubic bixbyite structure, and their crystalline fraction increased with deposition temperature. The electrical conductivity (σ) and electrical mobility (μ) were strongly enhanced at low deposition temperatures. For TG = 25 °C and 50 °C, a strong ⟨100⟩ preferred orientation (texture) occurred, but it decreased as the deposition temperature, and consequential crystallinity, increased. Higher variations in texture coefficients and in lattice parameters were measured at the film surface compared to the interior of the film, indicating strong microstructural gradients. At low crystallinity, the in-plane lattice spacing expanded, while the out-of-plane spacing contracted, and those values merged at TG = 400 °C, where high μ was measured. This directional difference in lattice spacing, or deviatoric strain, was linear as a function of both deposition temperature and the degree of crystallinity. The crystalline sample with TG = 100 °C had the lowest mobility, as well as film diffraction peaks which split into doublets. The deviatoric strains from these doublet peaks differ by a factor of four, supporting the presence of both a microstructure and strain gradient in this film. More isotropic films exhibit larger μ values, indicating that the microstructure directly correlates with electrical properties. These results provide valuable insights that can help to improve the desirable properties of indium oxide, as well as other transparent conducting oxides.

  1. Raman scattering, electrical and optical properties of fluorine-doped tin oxide thin films with (200) and (301) preferred orientation

    Kim, Chang-Yeoul, E-mail: cykim15@kicet.re.kr [Nano-Convergence Intelligence Material Team, Korea Institute of Ceramic Eng. and Tech., Gasan-digtial-ro 10 Gil 77 Geumcheon-gu, 153-801 Seoul (Korea, Republic of); Riu, Doh-Hyung [Dept. of New Material Sci. and Eng., Seoul National University of Technology, Seoul (Korea, Republic of)

    2014-12-15

    (200) and (301) preferred oriented fluorine-doped tin oxide (FTO) thin films were fabricated by spray pyrolysis of ethanol-added and water-based FTO precursor solutions, respectively. (200) oriented FTO thin film from ethanol-added solution shows the lower electrical resistivity and visible light transmission than (301) preferred thin film from water-based solution. It is due to the higher carrier concentration and electron mobility in (200) oriented crystals, that is, the lower ionized impurity scattering. The higher electron concentration is related to the higher optical band gap energy, the lower visible light transmission, and the higher IR reflection. For (301) preferred FTO thin films from water-based solution, the lower carrier concentration and electron mobility make the higher electrical resistivity and visible light transmission. Raman scattering analysis shows that IR active modes prominent in (200) oriented FTO thin film are related with the lower electrical resistivity. - Highlights: • We coated fluorine-doped tin oxide thin films with preferred orientation of (200) and (301). • We examine changes in the level of electrical and optical properties with the orientation. • (200) preferred orientation showed lower electrical resistivity and optical transmittance. • (200) oriented thin films have higher electron concentrations that are related with IR active modes.

  2. Scattering in relativistic particle mechanics

    De Bievre, S.

    1986-01-01

    The problem of direct interaction in relativistic particle mechanics has been extensively studied and a variety of models has been proposed avoiding the conclusions of the so-called no-interaction theorems. In this thesis the authors studied scattering in the relativistic two-body problem. He uses the results to analyze gauge invariance in Hamiltonian constraint models and the uniqueness of the symplectic structure in manifestly covariant relativistic particle mechanics. A general geometric framework that underlies approaches to relativistic particle mechanics is presented and the kinematic properties of the scattering transformation, i.e., those properties that arise solely from the invariance of the theory under the Poincare group are studied. The second part of the analysis of the relativistic two-body scattering problem is devoted to the dynamical properties of the scattering process. Using general geometric arguments, gauge invariance of the scattering transformation in the Todorov-Komar Hamiltonian constraint model is proved. Finally, quantization of the models is discussed

  3. Elastic Properties of Hard Films Multi-Layer Protective Coatings by Light Scattering

    Sooryakumar, R

    2000-01-01

    ... (silicon oxynitride and ZnSe) and free-standing membranes (SiN). These harmonics provide a direct means to investigate the longitudinal and transverse sound velocities and thereby to determine the C11 and C44 elastic constants...

  4. Frequency Properties Research of Elevator Drive System with Direct Torque Control-Pulse with Modulation

    A. S. Koval

    2008-01-01

    Full Text Available In the article problems of frequency properties research for electric drive system with direct torque control and pulse width modulator are described. The mathematical description of elevator is present. Simplified mathematical description of direct torque control - pulse width modulator electric drive system is shown. Transfer functions for torque and speed loops are determined. Logarithmic frequency characteristics are computed. Damping properties of elevator drive system are estimated.

  5. Sintering, structure, and mechanical properties of nanophase SiC: A molecular-dynamics and neutron scattering study

    Chatterjee, Alok; Kalia, Rajiv K.; Nakano, Aiichiro; Omeltchenko, Andrey; Tsuruta, Kenji; Vashishta, Priya; Loong, Chun-Keung; Winterer, Markus; Klein, Sylke

    2000-01-01

    Structure, mechanical properties, and sintering of nanostructured SiC (n-SiC) are investigated with neutron scattering and molecular-dynamics (MD) techniques. Both MD and the experiment indicate the onset of sintering around 1500 K. During sintering, the pores shrink while maintaining their morphology: the fractal dimension is ∼2 and the surface roughness exponent is ∼0.45. Structural analyses reveal that interfacial regions in n-SiC are disordered with nearly the same number of three- and fourfold coordinated Si atoms. The elastic moduli scale with the density as ∼ρ μ , where μ=3.4±0.1. (c) 2000 American Institute of Physics

  6. Acoustic Phonons and Mechanical Properties of Ultra-Thin Porous Low-k Films: A Surface Brillouin Scattering Study

    Zizka, J.; King, S.; Every, A.; Sooryakumar, R.

    2018-04-01

    To reduce the RC (resistance-capacitance) time delay of interconnects, a key development of the past 20 years has been the introduction of porous low-k dielectrics to replace the traditional use of SiO2. Moreover, in keeping pace with concomitant reduction in technology nodes, these low-k materials have reached thicknesses below 100 nm wherein the porosity becomes a significant fraction of the film volume. The large degree of porosity not only reduces mechanical strength of the dielectric layer but also renders a need for non-destructive approaches to measure the mechanical properties of such ultra-thin films within device configurations. In this study, surface Brillouin scattering (SBS) is utilized to determine the elastic constants, Poisson's ratio, and Young's modulus of these porous low-k SiOC:H films (˜ 25-250 nm thick) grown on Si substrates by probing surface acoustic phonons and their dispersions.

  7. Investigation on the elastic properties of Gd-Sc-Al garnet by the Mandelstam-Brillouin light scattering method

    Zharikov, E.V.; Zagumennyj, A.I.; Kitaeva, V.F.; Lutts, G.B.; Terskov, D.B.

    1991-01-01

    The Gd-Sc-Al garnet (GSAG) crystals grown from the melt with composition Gd 2.88 Sc 1.89 Al 3.23 O 12 , were investigated. The GSAG doped with chromium was also studied. The Mandelstam-Brillouin (MB) light scattering in the GSAG crystals was observed. The garnet elastic components were determined using the data on the MB component shifts, the products of the elastic constants by molar volume were calculated as well. The GSAG is elastically anisotropic. The doping addition introduction do not cause noticeable change in the elastic properties. The obtained values of elastic constants and their combinations for GSAG were compared with the data for aluminium and gallium garnets. The comparison has shown that the values of elastic constants for GSAG is closer to those for Gd-Sc-Ga garnet than to the corresponding values for the Y-Al one

  8. Photoacoustic-fluorescence in vitro flow cytometry for quantification of absorption, scattering and fluorescence properties of the cells

    Nedosekin, D. A.; Sarimollaoglu, M.; Foster, S.; Galanzha, E. I.; Zharov, V. P.

    2013-03-01

    Fluorescence flow cytometry is a well-established analytical tool that provides quantification of multiple biological parameters of cells at molecular levels, including their functional states, morphology, composition, proliferation, and protein expression. However, only the fluorescence and scattering parameters of the cells or labels are available for detection. Cell pigmentation, presence of non-fluorescent dyes or nanoparticles cannot be reliably quantified. Herewith, we present a novel photoacoustic (PA) flow cytometry design for simple integration of absorbance measurements into schematics of conventional in vitro flow cytometers. The integrated system allow simultaneous measurements of light absorbance, scattering and of multicolor fluorescence from single cells in the flow at rates up to 2 m/s. We compared various combinations of excitation laser sources for multicolor detection, including simultaneous excitation of PA and fluorescence using a single 500 kHz pulsed nanosecond laser. Multichannel detection scheme allows simultaneous detection of up to 8 labels, including 4 fluorescent tags and 4 PA colors. In vitro PA-fluorescence flow cytometer was used for studies of nanoparticles uptake and for the analysis of cell line pigmentation, including genetically encoded melanin expression in breast cancer cell line. We demonstrate that this system can be used for direct nanotoxicity studies with simultaneous quantification of nanoparticles content and assessment of cell viability using a conventional fluorescent apoptosis assays.

  9. Influence of core diameter and length of polymer optical fiber on Brillouin scattering properties

    Mizuno, Yosuke; Ishigure, Takaaki; Nakamura, Kentaro

    2012-02-01

    Brillouin scattering in perfluorinated graded-index polymer optical fibers (PFGI-POFs) is potentially useful in developing high-accuracy distributed temperature sensors with reduced strain sensitivity. In this study, we investigate, both experimentally and theoretically, the influence of the fiber core diameter and length on the Brillouin gain spectra (BGS) in PFGI-POFs. First, we show that smaller core diameter drastically enhances the Stokes power using PFGI-POFs with 62.5-μm and 120-μm core diameters, and discuss the Brillouin threshold power. Then, we demonstrate that the PFGI-POF length has little influence on the BGS when the length is longer than 50 m. We also predict that, at 1.55-μm wavelength, it is difficult to reduce the Brillouin threshold power of PFGI-POFs below that of long silica single-mode fibers even if their core diameter is sufficiently reduced to satisfy the single-mode condition. Finally, making use of the enhanced Stokes signal, we confirm the Brillouin linewidth narrowing effect.

  10. The K-property of 4D billiards with nonorthogonal cylindric scatterers

    Simanyi, N.; Szasz, D.

    1994-01-01

    The K-property of cylindric billiards give on the 4-torus is established. These billiards are neither open-quotes orthogonal,close quotes where general necessary and sufficient conditions were obtained by D.Szasz, nor isomorphic to hard-ball systems, where the connecting path formula of N. Simanyi is a hand

  11. Ultraviolet Imaging Telescope images of the reflection nebula NGC 7023 - Derivation of ultraviolet scattering properties of dust grains

    Witt, Adolf N.; Petersohn, Jens K.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

    1992-01-01

    The Ultraviolet Imaging Telescope as part of the Astro-1 mission, was used to obtain high-resolution surface brightness distribution data in six ultraviolet wavelength bands for the bright reflection nebula NGC 7023. From the quantitative comparison of the measured surface brightness gradients ratios of nebular to stellar flux, and detail radial surface brightness profiles with corresponding data from the visible, two major conclusions results: (1) the scattering in the near- and far-ultraviolet in this nebula is more strongly forward-directed than in the visible; (2) the dust albedo in the ultraviolet for wavelengths not less than 140 nm is identical to that in the visible, with the exception of the 220 nm bump in the extinction curve. In the wavelengths region of the bump, the albedo is reduced by 25 to 30 percent in comparison with wavelengths regions both shorter and longer. This lower albedo is expected, if the bump is a pure absorption feature.

  12. Application of Fourier elastodynamics to direct and inverse problems for the scattering of elastic waves from flaws near surfaces

    Richardson, J.M.; Fertig, K.W. Jr.

    1983-01-01

    In order to inspect flaws which lie too close to the surface a Fourier elastodynamic formalism is proposed which enables one to decompose the elastodynamic system into separately charterizable parts by means of planes perpendicular to the z-axis. The process can be represented by a generalized transfer function relating the near-field scattered waves to the waves incident on a slab of material containing the flaw. The Fourier elastodynamics are applied to the characterization of the total scattering process involving a flaw at various distances from a plastic-water interface. An abbreviated discussion of Fourier elastodynamics is presented, and the results specialized to the case of spherical voids and inclusions bear an interface. Finally, the computational results for several ranges of temporal frequency and for a sequence of values of the distance from the flaw center to the interface are discussed

  13. Measurement of Feynman-x spectra of photons and neutrons in the very forward direction in deep-inelastic scattering at HERA

    Andreev, V.; Baghdasaryan, A.; Begzsuren, K.

    2014-03-01

    Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to the proton beam direction in deep-inelastic ep scattering at HERA are presented as a function of the Feynman variable x F and of the centre-of-mass energy of the virtual photon-proton system W. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 131 pb -1 . The measurement is restricted to photons and neutrons in the pseudorapidity range η > 7.9 and covers the range of negative four momentum transfer squared at the positron vertex 6 2 2 , of inelasticity 0.05 F dependent cross sections is investigated. Predictions of deep-inelastic scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections.

  14. Proton nuclear scattering radiography

    Duchazeaubeneix, J.C.; Faivre, J.C.; Garreta, D.

    1982-10-01

    Nuclear scattering of protons allows to radiograph objects with specific properties: direct 3- dimensional radiography, different information as compared to X-ray technique, hydrogen radiography. Furthermore, it is a well adapted method to gating techniques allowing the radiography of fast periodic moving systems. Results obtained on different objects (light and heavy materials) are shown and discussed. The dose delivery is compatible with clinical use, but at the moment, the irradiation time is too long between 1 and 4 hours. Perspectives to make the radiography faster and to get a practical method are discussed

  15. Neutron scattering study of dynamical properties of liquid helium confined into porous media

    Albergamo, Francesco

    2001-01-01

    The study of liquid helium confined into porous materials should allow for a better understanding of the relation between superfluidity and Bose-Einstein condensation, lacking, at present, o f a satisfactory theoretical description. Experiments on confined liquid helium are quite difficult and samples should be prepared very carefully. One should know at best the confining material characteristics and should control the actual filling status of the porous sample. To achieve this condition, we added an experimental stage to the procedure commonly used in the studies conducted insofar. We conducted helium adsorption isotherms on each porous sample supposed to be used a s a confining sample. In this way we were able to know, with an high degree of precision, the amount of helium necessary to fill the porous sample. We also get information on macroscopic phenomena occurring during the filling procedure. Some experimental tricks have been used in order to avoid condensation of liquid helium into the injection capillary. Two inelastic neutron scattering techniques have been used in order to get information respectively on the mean kinetic energy per particle and on the elementary excitations spectrum. The kinetic energy measurements showed that confinement is responsible for a rise in this quantity. The elementary excitations measurements showed a correspondence between the capillary condensation process (detected by helium adsorption isotherms measurements) and the presence of elementary excitations typical of the liquid helium. Moreover, the long-wavelength elementary excitations are found to be perturbed in a way compatible with the system geometry. An intrinsic (at T=0.4 K) width of the roton peak is also found. (author) [fr

  16. Direct rapid analysis of trace bioavailable soil macronutrients by chemometrics-assisted energy dispersive X-ray fluorescence and scattering spectrometry

    Kaniu, M.I.; Angeyo, K.H.; Mwala, A.K.; Mangala, M.J.

    2012-01-01

    Highlights: ► Chemometrics-assisted EDXRFS spectroscopy realizes direct, rapid and accurate analysis of trace bioavailable macronutrients in soils. ► The method is minimally invasive, involves little sample preparation, short analysis times and is relatively insensitive to matrix effects. ► This opens up the ability to rapidly characterize large number of samples/matrices with this method. - Abstract: Precision agriculture depends on the knowledge and management of soil quality (SQ), which calls for affordable, simple and rapid but accurate analysis of bioavailable soil nutrients. Conventional SQ analysis methods are tedious and expensive. We demonstrate the utility of a new chemometrics-assisted energy dispersive X-ray fluorescence and scattering (EDXRFS) spectroscopy method we have developed for direct rapid analysis of trace ‘bioavailable’ macronutrients (i.e. C, N, Na, Mg, P) in soils. The method exploits, in addition to X-ray fluorescence, the scatter peaks detected from soil pellets to develop a model for SQ analysis. Spectra were acquired from soil samples held in a Teflon holder analyzed using 109 Cd isotope source EDXRF spectrometer for 200 s. Chemometric techniques namely principal component analysis (PCA), partial least squares (PLS) and artificial neural networks (ANNs) were utilized for pattern recognition based on fluorescence and Compton scatter peaks regions, and to develop multivariate quantitative calibration models based on Compton scatter peak respectively. SQ analyses were realized with high CMD (R 2 > 0.9) and low SEP (0.01% for N and Na, 0.05% for C, 0.08% for Mg and 1.98 μg g −1 for P). Comparison of predicted macronutrients with reference standards using a one-way ANOVA test showed no statistical difference at 95% confidence level. To the best of the authors’ knowledge, this is the first time that an XRF method has demonstrated utility in trace analysis of macronutrients in soil or related matrices.

  17. Atomic substitution effects on the structural and vibrational properties of Ni{sub x}Pb{sub 1-x}TiO{sub 3}: X-ray diffraction and Raman scattering investigations

    Costa, R. C. da [Universidade Federal de São Carlos, Departamento de Física, São Carlos-SP, 13565-905 (Brazil); Universidade Federal de Campina Grande, Pombal-PB, 58840-000 (Brazil); Toledo, T. A. de; Pizani, P. S., E-mail: pizani@df.ufscar.br [Universidade Federal de São Carlos, Departamento de Física, São Carlos-SP, 13565-905 (Brazil); Espinosa, J. W. M. [Universidade Federal de Goiás, Engenharia de Produção, Catalão-GO, 75704-020 (Brazil)

    2015-07-15

    The effects of the atomic substitution of Pb by Ni in the PbTiO{sub 3} ferroelectric perovskite on the vibrational and structural properties was studied using x-ray diffraction and Raman scattering. It was observed that for Ni concentrations between 0.0 and 0.4, there is the formation of a solid solution with reduction of the Raman wavenumber of the E(TO1) soft mode and the tetragonallity factor, which influence directly the temperature of the tetragonal ferroelectric to cubic paraelectric phase transition, the Curie temperature. For concentrations greater than 0.4, it is observed the formation of a PbTiO{sub 3} and NiTiO{sub 3} composite, denounced by the recovering of the both, tetragonallity factor and the E(TO1) soft mode wavenumber. The values of the Curie temperatures were estimated by the Raman scattering measurements for temperatures ranging from 300 to 950 K.

  18. The Influence of Forming Directions and Strain Rate on Dynamic Shear Properties of Aerial Aluminum Alloy

    Ying Meng

    2018-03-01

    Full Text Available Dynamic shear properties under high strain rate are an important basis for studying the dynamic mechanical properties and microscopic mechanisms of materials. Dynamic impact shear tests of aerial aluminum alloy 7050-T7451 in rolling direction (RD, transverse direction (TD and normal direction (ND were performed at a range of strain rates from 2.5 × 104 s−1 to 4.5 × 104 s−1 by High Split Hopkinson Pressure Bar (SHPB. The influence of different forming directions and strain rates on the dynamic shear properties of material and the microstructure evolution under dynamic shear were emphatically analyzed. The results showed that aluminum alloy 7050-T7451 had a certain strain rate sensitivity and positive strain rate strengthening effect, and also the material had no obvious strain strengthening effect. Different forming directions had a great influence on dynamic shear properties. The shear stress in ND was the largest, followed by that in RD, and the lowest was that in TD. The microstructure observation showed that the size and orientation of the grain structure were different in three directions, which led to the preferred orientation of the material. All of those were the main reasons for the difference of dynamic shear properties of the material.

  19. Does variation in mineral composition alter the short-wave light scattering properties of desert dust aerosol?

    Smith, Andrew J.A.; Grainger, Roy G.

    2014-01-01

    Mineral dust aerosol is a major component of natural airborne particulates. Using satellite measurements from the visible and near-infrared, there is insufficient information to retrieve a full microphysical and chemical description of an aerosol distribution. As such, refractive index is one of many parameters that must be implicitly assumed in order to obtain an optical depth retrieval. This is essentially a proxy for the dust mineralogy. Using a global soil map, it is shown that as long as a reasonable refractive index for dust is assumed, global dust variability is unlikely to cause significant variation in the optical properties of a dust aerosol distribution in the short-wave, and so should not greatly affect retrievals of mineral dust aerosol from space by visible and near-infrared radiometers. Errors in aerosol optical depth due to this variation are expected to be ≲1%. The work is framed around the ORAC AATSR aerosol retrieval, but is equally applicable to similar satellite retrievals. In this case, variations in the top-of-atmosphere reflectance caused by mineral variation are within the noise limits of the instrument. -- Highlights: • Global variation in dust aerosol refractive index is quantified using soil maps. • Resulting visible light scattering properties have limited variability. • Satellite aerosol retrievals do not need to account for varying dust refractive indices

  20. Technique charts for EC film: direct optical measurements to account for the effects of X-ray scatter

    Munro, Peter; Jordan, Kevin; Lewis, Craig; Heerema, Tim

    2001-01-01

    Purpose: To develop a method of measuring technique charts for enhanced contrast (EC) film, to demonstrate how X-ray scatter changes the response of EC film, and to generate technique charts for general use. Methods and Materials: We have developed a 'digital cassette' - consisting of a metal plate/phosphor screen, a light guide, a photodiode sensor, and an electrometer - that can be used to measure the light generated in the phosphor screen of the film cassette. In turn, these measurements can be used to generate technique charts for EC film. The digital cassette has been used to measure technique charts for 4-MV and 6-MV X-ray beams for a variety of different phantom thicknesses, field sizes, and phantom-to-cassette air gaps. Results and Discussion: We have observed that the signals generated in an ionization chamber located 9.4 cm behind a 30-cm-thick water-equivalent phantom increase by a factor of 1.9 when the field size is increased from 4x4 cm 2 to 40x40 cm 2 when irradiated by a 6-MV X-ray beam. However, the change in EC film response is a factor of 3.5 under the same conditions. Irradiations to optimally expose the EC film predicted by the digital cassette differ by up to 82% compared to those predicted by ion chamber measurements. Nevertheless, the technique charts measured using the digital cassette predict the response of the EC film to ±0.2 optical density. The overresponse of the EC film is most likely due to low-energy scattered photons, which interact with the high atomic number (Z=64) phosphor screen of the enhanced contrast localization cassette. Therefore, simple solutions, such as placing a high atomic number material above the enhanced contrast localization cassette, can reduce this contribution by scattered photons to the signal generated in the cassettes. Conclusions: We have developed a digital cassette that can make more accurate measurements of the technique charts for EC films. Our measurements show that under some conditions, X

  1. Inelastic neutron scattering from clusters

    Gudel, H.U.

    1985-01-01

    Magnetic excitations in clusters of paramagnetic ions have non-vanishing cross-sections for inelastic neutron scattering (INS). Exchange splittings can be determined, the temperature dependence of exchange can be studied, intra- and intercluster effects can be separated and magnetic form factors determined. INS provides a more direct access to the molecular properties than bulk techniques. Its application is restricted to complexes with no or few (< 10%) hydrogen atoms

  2. User's manual for EXALPHA (a code for calculating electronic properties of molecules). [Muscatel code, multiply scattered electron approximation

    Jones, H.D.

    1976-06-01

    The EXALPHA procedures provide a simplified method for running the MUSCATEL computer code, which in turn is used for calculating electronic properties of simple molecules and atomic clusters, based on the multiply scattered electron approximation for the wave equations. The use of the EXALPHA procedures to set up a run of MUSCATEL is described.

  3. Elastic properties of aspirin in its crystalline and glassy phases studied by micro-Brillouin scattering

    Ko, Jae-Hyeon; Lee, Kwang-Sei; Ike, Yuji; Kojima, Seiji

    2008-11-01

    The acoustic waves propagating along the direction perpendicular to the (1 0 0) cleavage plane of aspirin crystal were investigated using micro-Brillouin spectroscopy from which C11, C55 and C66 were obtained. The temperature dependence of the longitudinal acoustic waves could be explained by normal anharmonic lattice models, while the transverse acoustic waves showed an abnormal increase in the hypersonic attenuation at low temperatures indicating their coupling to local remnant dynamics. The sound velocity as well as the attenuation of the longitudinal acoustic waves of glassy aspirin showed a substantial change at ˜235 K confirming a transition from glassy to supercooled liquid state in vitreous aspirin.

  4. An axis-specific rotational rainbow in the direct scatter of formaldehyde from Au(111) and its influence on trapping probability.

    Park, G Barratt; Krüger, Bastian C; Meyer, Sven; Kandratsenka, Alexander; Wodtke, Alec M; Schäfer, Tim

    2017-08-02

    The conversion of translational to rotational motion often plays a major role in the trapping of small molecules at surfaces, a crucial first step for a wide variety chemical processes that occur at gas-surface interfaces. However, to date most quantum-state resolved surface scattering experiments have been performed on diatomic molecules, and little detailed information is available about how the structure of nonlinear polyatomic molecules influences the mechanisms for energy exchange with surfaces. In the current work, we employ a new rotationally resolved 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme to measure the rotational distribution in formaldehyde molecules directly scattered from the Au(111) surface at incidence kinetic energies in the range 0.3-1.2 eV. The results indicate a pronounced propensity to excite a-axis rotation (twirling) rather than b- or c-axis rotation (tumbling or cartwheeling), and are consistent with a rotational rainbow scattering model. Classical trajectory calculations suggest that the effect arises-to zeroth order-from the three-dimensional shape of the molecule (steric effects). Analysis suggests that the high degree of rotational excitation has a substantial influence on the trapping probability of formaldehyde at incidence translational energies above 0.5 eV.

  5. A validation of a ray-tracing tool used to generate bi-directional scattering distribution functions for complex fenestration systems

    McNeil, A.; Jonsson, C.J.; Appelfeld, David

    2013-01-01

    , or daylighting systems. However, such tools require users to provide bi-directional scattering distribution function (BSDF) data that describe the solar-optical performance of the CFS. A free, open-source Radiance tool genBSDF enables users to generate BSDF data for arbitrary CFS. Prior to genBSDF, BSDF data.......We explain the basis and use of the genBSDF tool and validate the tool by comparing results for four different cases to BSDF data produced via alternate methods. This validation demonstrates that BSDFs created with genBSDF are comparable to BSDFs generated analytically using TracePro and by measurement...

  6. Complete direct method for electron-hydrogen scattering: Application to the collinear and Temkin-Poet models

    Bartlett, Philip L.; Stelbovics, Andris T.

    2004-01-01

    We present an efficient generalization of the exterior complex scaling (ECS) method to extract discrete inelastic and ionization amplitudes for electron-impact scattering of atomic hydrogen. This fully quantal method is demonstrated over a range of energies for the collinear and Temkin-Poet models and near-threshold ionization is examined in detail for singlet and triplet scattering. Our numerical calculations for total ionization cross sections near threshold strongly support the classical threshold law of Wannier [Phys. Rev. 90, 817 (1953)] (σ∝E 1.128±0.004 ) for the L=0 singlet collinear model and the semiclassical threshold law of Peterkop [J. Phys. B 16, L587 (1983)] (σ∝E 3.37±0.02 ) for the L=0 triplet collinear model, and are consistent with the semiclassical threshold law of Macek and Ihra [Phys. Rev. A 55, 2024 (1997)] (σ∝exp[(-6.87±0.01)E -1/6 ]) for the singlet Temkin-Poet model

  7. Effects of Preprocessing on Multi-Direction Properties of Aluminum Alloy Cold-Spray Deposits

    Rokni, M. R.; Nardi, A. T.; Champagne, V. K.; Nutt, S. R.

    2018-05-01

    The effects of powder preprocessing (degassing at 400 °C for 6 h) on microstructure and mechanical properties of 5056 aluminum deposits produced by high-pressure cold spray were investigated. To investigate directionality of the mechanical properties, microtensile coupons were excised from different directions of the deposit, i.e., longitudinal, short transverse, long transverse, and diagonal and then tested. The results were compared to properties of wrought 5056 and the coating deposited with as-received 5056 Al powder and correlated with the observed microstructures. Preprocessing softened the particles and eliminated the pores within them, resulting in more extensive and uniform deformation upon impact with the substrate and with underlying deposited material. Microstructural characterization and finite element simulation indicated that upon particle impact, the peripheral regions experienced more extensive deformation and higher temperatures than the central contact zone. This led to more recrystallization and stronger bonding at peripheral regions relative to the contact zone area and yielded superior properties in the longitudinal direction compared with the short transverse direction. Fractography revealed that crack propagation takes place along the particle-particle interfaces in the transverse directions (caused by insufficient bonding and recrystallization), whereas through the deposited particles, fracture is dominant in the longitudinal direction.

  8. Direct rapid analysis of trace bioavailable soil macronutrients by chemometrics-assisted energy dispersive X-ray fluorescence and scattering spectrometry.

    Kaniu, M I; Angeyo, K H; Mwala, A K; Mangala, M J

    2012-06-04

    Precision agriculture depends on the knowledge and management of soil quality (SQ), which calls for affordable, simple and rapid but accurate analysis of bioavailable soil nutrients. Conventional SQ analysis methods are tedious and expensive. We demonstrate the utility of a new chemometrics-assisted energy dispersive X-ray fluorescence and scattering (EDXRFS) spectroscopy method we have developed for direct rapid analysis of trace 'bioavailable' macronutrients (i.e. C, N, Na, Mg, P) in soils. The method exploits, in addition to X-ray fluorescence, the scatter peaks detected from soil pellets to develop a model for SQ analysis. Spectra were acquired from soil samples held in a Teflon holder analyzed using (109)Cd isotope source EDXRF spectrometer for 200 s. Chemometric techniques namely principal component analysis (PCA), partial least squares (PLS) and artificial neural networks (ANNs) were utilized for pattern recognition based on fluorescence and Compton scatter peaks regions, and to develop multivariate quantitative calibration models based on Compton scatter peak respectively. SQ analyses were realized with high CMD (R(2)>0.9) and low SEP (0.01% for N and Na, 0.05% for C, 0.08% for Mg and 1.98 μg g(-1) for P). Comparison of predicted macronutrients with reference standards using a one-way ANOVA test showed no statistical difference at 95% confidence level. To the best of the authors' knowledge, this is the first time that an XRF method has demonstrated utility in trace analysis of macronutrients in soil or related matrices. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Polarization phenomena in deuteron proton scattering: a useful tool for the study of nucleon resonances properties

    Rekalo, M.P.; Tomasi-Gustafsson, E.

    1996-01-01

    The microscopic structure of the nucleon N and its excited states N* can be determined through the (elastic or inelastic) electromagnetic form factors. These form factors should help to understand the nature of the transition regime from soft physics of the confinement region to the hard physics of the perturbative QCD. The authors show that hadron induced reactions with isospin zero projectiles, could be an effective method for the study of the nucleon structure, in particular through the measurement of polarization observables. They analyzed the properties of the inclusive d + p reactions, with particular interest in the domain of nucleonic resonances excitation. The calculated cross section and polarization observables show that it is possible to disentangle the different reaction mechanisms (omega, sigma and eta exchange) and bring new information about the electromagnetic form factors of the deuteron as well as of the nucleonic resonances. Existing data on the tensor analyzing power are in agreement with the prediction based on the omega exchange model. (authors)

  10. Leaf optical properties with explicit description of its biochemical composition: direct and inverse problems

    Fourty, T. [INRA, Avignon (France); Baret, F.; Jacquemoud, S.; Schmuck, G.; Verdebout, J.

    1996-05-15

    This study presents a methodology to estimate the leaf biochemical compounds specific absorption coefficients and to use them to predict leaf biochemistry. A wide range of leaves was collected including variations in species and leaf status. All the leaves were dried out. The biochemical composition was measured using classical wet chemistry techniques to determine lignin, cellulose, hemicellulose, starch, and protein contents. Concurrently, leaf reflectance and transmittance were measured with a high spectral resolution spectrophotometer in the 800–2500 nm range with approximately 1 nm spectral resolution and sampling interval. In addition, infinite reflectance achieved by stacking leaves was also measured. The PROSPECT leaf optical properties model was first inverted over a selection of wavebands in the 800–2400 nm domain to provide estimates of the scattering characteristics using leaf reflectance, transmittance, and infinite reflectance data. Then, the model was inverted again over all the wavelengths to estimate the global absorption coefficient, using the previously estimated scattering properties. The global absorption coefficient was eventually explained using the measured biochemical composition by fitting the corresponding specific absorption coefficients after substraction of the measured contribution of the residual structural water absorption. Results show that the derived specific absorption coefficients are quite robustly estimated. Further, they are in good agreement with known absorption features of each biochemical compound. The average contribution of each biochemical compound to leaf absorption feature is also evaluated. Sugar, cellulose, and hemicellulose are the main compounds that contribute to absorption. Results demonstrate the possibility of modeling leaf optical properties of dry leaves with explicit description of leaf biochemistry. Estimates of the detailed biochemical composition obtained by model inversion over the 1300–2400 nm

  11. Magnetic properties of URu2Si2 under uniaxial stress by neutron scattering

    Bourdarot, Frederic; Martin, Nicolas; Raymond, Stephane; Regnault, Louis-Pierre; Aoki, Dai; Taufour, Valentin; Flouquet, Jacques

    2011-01-01

    The aim of this study is to compare the magnetic behavior of URu 2 Si 2 under uniaxial stress along the a axis with the behavior under hydrostatic pressure. Both are very similar, but uniaxial stress presents a critical stress σ x a [0.33(5) GPa] that is smaller than the hydrostatic critical pressure p x (0.5 GPa) where the ground state switches from a HO (hidden-order) to AF (antiferromagnetic) ground state. From these critical values and Larmor neutron diffraction, we conclude that the magnetic properties are governed by the shortest U-U distance in the plane (a lattice parameter). Under stress, the orthorhombic unit cell stays centered. A key point shown by this study is the presence of a threshold for the uniaxial stress along the a axis before the appearance of the large AF moment, which indicates no mixture of the order parameter between the HO ground state and the AF one as under hydrostatic pressure. The two most intense longitudinal magnetic excitations at Q 0 =(1,0,0) and Q 1 =(0.6,0,0) were measured in the HO state: the excitation at Q 0 decreases in energy while the excitation at Q 1 increases in energy with the uniaxial stress along the a axis. The decrease of the energy of the excitation at Q 0 seems to indicate a critical energy-gap value of 1.2(1) meV at σ x a . A similar value was derived from studies under hydrostatic pressure at p x .

  12. Volatility measurement with directional change in Chinese stock market: Statistical property and investment strategy

    Ma, Junjun; Xiong, Xiong; He, Feng; Zhang, Wei

    2017-04-01

    The stock price fluctuation is studied in this paper with intrinsic time perspective. The event, directional change (DC) or overshoot, are considered as time scale of price time series. With this directional change law, its corresponding statistical properties and parameter estimation is tested in Chinese stock market. Furthermore, a directional change trading strategy is proposed for invest in the market portfolio in Chinese stock market, and both in-sample and out-of-sample performance are compared among the different method of model parameter estimation. We conclude that DC method can capture important fluctuations in Chinese stock market and gain profit due to the statistical property that average upturn overshoot size is bigger than average downturn directional change size. The optimal parameter of DC method is not fixed and we obtained 1.8% annual excess return with this DC-based trading strategy.

  13. A simple property of the contribution of double scattered radiation to the lidar returnes from homogeneous fogs

    Bruscaglioni, P.

    1979-01-01

    By using the formulas presented in a previous paper for the calculation of the ratio D/S between the contributions of doubly scattered and singly scattered radiation to lidar returns from homogeneous fogs, it is shown that the ratio D/S is proportional to the lidar range, indipendently from the particular model of fog, i.e. from the assumed phase scattering function

  14. THEORETICAL MODELLING STUDY ON THE RELATIONSHIP BETWEEN MULTI-FREQUENCY MICROWAVE VEGETATION INDEX AND VEGETATION PROPERTIES (OPTICAL DEPTH AND SINGLE SCATTERING ALBEDO

    S. Talebi

    2018-04-01

    Full Text Available This paper presents a theoretical study of derivation Microwave Vegetation Indices (MVIs in different pairs of frequencies using two methods. In the first method calculating MVI in different frequencies based on Matrix Doubling Model (to take in to account multi scattering effects has been done and analyzed in various soil properties. The second method was based on MVI theoretical basis and its independency to underlying soil surface signals. Comparing the results from two methods with vegetation properties (single scattering albedo and optical depth indicated partial correlation between MVI from first method and optical depth, and full correlation between MVI from second method and vegetation properties. The second method to derive MVI can be used widely in global microwave vegetation monitoring.

  15. Particle Engineering of Excipients for Direct Compression: Understanding the Role of Material Properties.

    Mangal, Sharad; Meiser, Felix; Morton, David; Larson, Ian

    2015-01-01

    Tablets represent the preferred and most commonly dispensed pharmaceutical dosage form for administering active pharmaceutical ingredients (APIs). Minimizing the cost of goods and improving manufacturing output efficiency has motivated companies to use direct compression as a preferred method of tablet manufacturing. Excipients dictate the success of direct compression, notably by optimizing powder formulation compactability and flow, thus there has been a surge in creating excipients specifically designed to meet these needs for direct compression. Greater scientific understanding of tablet manufacturing coupled with effective application of the principles of material science and particle engineering has resulted in a number of improved direct compression excipients. Despite this, significant practical disadvantages of direct compression remain relative to granulation, and this is partly due to the limitations of direct compression excipients. For instance, in formulating high-dose APIs, a much higher level of excipient is required relative to wet or dry granulation and so tablets are much bigger. Creating excipients to enable direct compression of high-dose APIs requires the knowledge of the relationship between fundamental material properties and excipient functionalities. In this paper, we review the current understanding of the relationship between fundamental material properties and excipient functionality for direct compression.

  16. Spectral properties of the Google matrix of the World Wide Web and other directed networks.

    Georgeot, Bertrand; Giraud, Olivier; Shepelyansky, Dima L

    2010-05-01

    We study numerically the spectrum and eigenstate properties of the Google matrix of various examples of directed networks such as vocabulary networks of dictionaries and university World Wide Web networks. The spectra have gapless structure in the vicinity of the maximal eigenvalue for Google damping parameter α equal to unity. The vocabulary networks have relatively homogeneous spectral density, while university networks have pronounced spectral structures which change from one university to another, reflecting specific properties of the networks. We also determine specific properties of eigenstates of the Google matrix, including the PageRank. The fidelity of the PageRank is proposed as a characterization of its stability.

  17. Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu2(Fe,Zn)SnS4

    Fontané, X.; Izquierdo-Roca, V.; Saucedo, E.; Schorr, S.; Yukhymchuk, V.O.; Valakh, M.Ya.; Pérez-Rodríguez, A.; Morante, J.R.

    2012-01-01

    Highlights: ► Analysis of main and weaker Raman peaks from Cu 2 FeZnS 4 and Cu 2 ZnSnS 4 compounds. ► Identification of a cation disorder induced Raman peak in Cu 2 ZnSnS 4 . ► Analysis of spectral features of main Raman peaks from Cu 2 (Fe,Zn)SnS 4 . - Abstract: This work reports the analysis of the vibrational properties of stannite–kesterite Cu 2 (Fe,Zn)SnS 4 compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu 2 FeSnS 4 (CFTS) and kesterite Cu 2 ZnSnS 4 (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm −1 . This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A 1 peak with the chemical composition.

  18. Properties and cellular effects of particulate matter from direct emissions and ambient sources.

    Jin, Wenjie; Su, Shu; Wang, Bin; Zhu, Xi; Chen, Yilin; Shen, Guofeng; Liu, Junfeng; Cheng, Hefa; Wang, Xilong; Wu, Shuiping; Zeng, Eddy; Xing, Baoshan; Tao, Shu

    2016-10-14

    The pollution of particulate matter (PM) is of great concern in China and many other developing countries. It is generally recognized that the toxicity of PM is source and property dependent. However, the relationship between PM properties and toxicity is still not well understood. In this study, PM samples from direct emissions of wood, straw, coal, diesel combustion, cigarette smoking and ambient air were collected and characterized for their physicochemical properties. Their expression of intracellular reactive oxygen species (ROS) and levels of inflammatory cytokines (i.e., tumor necrosis factor-α (TNF-α)) was measured using a RAW264.7 cell model. Our results demonstrated that the properties of the samples from different origins exhibited remarkable differences. Significant increases in ROS were observed when the cells were exposed to PMs from biomass origins, including wood, straw and cigarettes, while increases in TNF-α were found for all the samples, particularly those from ambient air. The most important factor associated with ROS generation was the presence of water-soluble organic carbon, which was extremely abundant in the samples that directly resulted from biomass combustion. Metals, endotoxins and PM size were the most important properties associated with increases in TNF-α expression levels. The association of the origins of PM particles and physicochemical properties with cytotoxic properties is illustrated using a cluster analysis.

  19. The effects of surface roughness on the scattering properties of hexagonal columns with sizes from the Rayleigh to the geometric optics regimes

    Liu, Chao; Lee Panetta, R.; Yang, Ping

    2013-01-01

    Effects of surface roughness on the optical scattering properties of ice crystals are investigated using a random wave superposition model of roughness that is a simplification of models used in studies of scattering by surface water waves. Unlike previous work with models of rough surfaces applicable only in limited size ranges, such as surface perturbation methods in the small particle regime or the tilted-facet (TF) method in the large particle regime, ours uses a single roughness model to cover a range in sizes extending from the Rayleigh to the geometric optics regimes. The basic crystal shape we examine is the hexagonal column but our roughening model can be used for a wide variety of particle geometries. To compute scattering properties over the range of sizes we use the pseudo-spectral time domain method (PSTD) for small to moderate sized particles and the improved geometric optics method (IGOM) for large ones. Use of the PSTD with our roughness model is straightforward. By discretizing the roughened surface with triangular sub-elements, we adapt the IGOM to give full consideration of shadow effects, multiple reflections/refractions at the surface, and possible reentrance of the scattered beams. We measure the degree of roughness of a surface by the variance (σ 2 ) of surface slopes occurring on the surfaces. For moderately roughened surfaces (σ 2 ≤0.1) in the large particle regime, the scattering properties given by the TF and IGOM agree well, but differences in results obtained with the two methods become noticeable as the surface becomes increasingly roughened. Having a definite, albeit idealized, roughness model we are able to use the combination of the PSTD and IGOM to examine how a fixed degree of surface roughness affects the scattering properties of a particle as the size parameter of the particle changes. We find that for moderately rough surfaces in our model, as particle size parameter increases beyond about 20 the influence of surface

  20. Direct rapid analysis of trace bioavailable soil macronutrients by chemometrics-assisted energy dispersive X-ray fluorescence and scattering spectrometry

    Kaniu, M.I., E-mail: ikaniu@uonbi.ac.ke [Institute of Nuclear Science and Technology, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya); Angeyo, K.H. [Department of Physics, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya); Mwala, A.K. [Department of Land Resource Management and Agricultural Technology, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya); Mangala, M.J. [Institute of Nuclear Science and Technology, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya)

    2012-06-04

    Highlights: Black-Right-Pointing-Pointer Chemometrics-assisted EDXRFS spectroscopy realizes direct, rapid and accurate analysis of trace bioavailable macronutrients in soils. Black-Right-Pointing-Pointer The method is minimally invasive, involves little sample preparation, short analysis times and is relatively insensitive to matrix effects. Black-Right-Pointing-Pointer This opens up the ability to rapidly characterize large number of samples/matrices with this method. - Abstract: Precision agriculture depends on the knowledge and management of soil quality (SQ), which calls for affordable, simple and rapid but accurate analysis of bioavailable soil nutrients. Conventional SQ analysis methods are tedious and expensive. We demonstrate the utility of a new chemometrics-assisted energy dispersive X-ray fluorescence and scattering (EDXRFS) spectroscopy method we have developed for direct rapid analysis of trace 'bioavailable' macronutrients (i.e. C, N, Na, Mg, P) in soils. The method exploits, in addition to X-ray fluorescence, the scatter peaks detected from soil pellets to develop a model for SQ analysis. Spectra were acquired from soil samples held in a Teflon holder analyzed using {sup 109}Cd isotope source EDXRF spectrometer for 200 s. Chemometric techniques namely principal component analysis (PCA), partial least squares (PLS) and artificial neural networks (ANNs) were utilized for pattern recognition based on fluorescence and Compton scatter peaks regions, and to develop multivariate quantitative calibration models based on Compton scatter peak respectively. SQ analyses were realized with high CMD (R{sup 2} > 0.9) and low SEP (0.01% for N and Na, 0.05% for C, 0.08% for Mg and 1.98 {mu}g g{sup -1} for P). Comparison of predicted macronutrients with reference standards using a one-way ANOVA test showed no statistical difference at 95% confidence level. To the best of the authors' knowledge, this is the first time that an XRF method has demonstrated

  1. Monolayer-directed Assembly and Magnetic Properties of FePt Nanoparticles on Patterned Aluminum Oxide

    Yildirim, O.; Gang, T.; Kinge, S.S.; Reinhoudt, David; Blank, David H.A.; van der Wiel, Wilfred Gerard; Rijnders, Augustinus J.H.M.; Huskens, Jurriaan

    2010-01-01

    FePt nanoparticles (NPs) were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(on)ates were used as an adsorbate to form self-assembled monolayers (SAMs) on alumina to direct the assembly of NPs

  2. Matter scattering in quadratic gravity and unitarity

    Abe, Yugo; Inami, Takeo; Izumi, Keisuke; Kitamura, Tomotaka

    2018-03-01

    We investigate the ultraviolet (UV) behavior of two-scalar elastic scattering with graviton exchanges in higher-curvature gravity theory. In Einstein gravity, matter scattering is shown not to satisfy the unitarity bound at tree level at high energy. Among some of the possible directions for the UV completion of Einstein gravity, such as string theory, modified gravity, and inclusion of high-mass/high-spin states, we take R_{μν}^2 gravity coupled to matter. We show that matter scattering with graviton interactions satisfies the unitarity bound at high energy, even with negative norm states due to the higher-order derivatives of metric components. The difference in the unitarity property of these two gravity theories is probably connected to that in another UV property, namely, the renormalizability property of the two.

  3. Specimen alignment in an axial tensile test of thin films using direct imaging and its influence on the mechanical properties of BeCu

    Kang, Dong-Joong; Park, Jun-Hyub; Shin, Myung-Soo; Ha, Jong-Eun; Lee, Hak-Joo

    2010-01-01

    This paper proposes a new system for verification of the alignment of loading fixtures and test specimens during tensile testing of thin film with a micrometer size through direct imaging. The novel and reliable image recognition system to evaluate the misalignment between the load train and the specimen axes during tensile test of thin film was developed using digital image processing technology with CCD. The decision of whether alignment of the tensile specimen is acceptable or not is based on a probabilistic analysis through the edge feature extraction of digital imaging. In order to verify the performance of the proposed system and investigate the effect of the misalignment of the specimen on tensile properties, the tensile tests were performed as displacement control in air and at room temperature for metal thin film, the beryllium copper (BeCu) alloys. In the case of the metal thin films, bending stresses caused by misalignment are insignificant because the films are easily bent during tensile tests to eliminate the bending stresses. And it was observed that little effects and scatters on tensile properties occur by stress gradient caused by twisting at in-plane misalignment, and the effects and scatters on tensile properties are insignificant at out-of-plane misalignment, in the case of the BeCu thin film.

  4. Photoacoustic imaging in scattering media by combining a correlation matrix filter with a time reversal operator.

    Rui, Wei; Tao, Chao; Liu, Xiaojun

    2017-09-18

    Acoustic scattering medium is a fundamental challenge for photoacoustic imaging. In this study, we reveal the different coherent properties of the scattering photoacoustic waves and the direct photoacoustic waves in a matrix form. Direct waves show a particular coherence on the antidiagonals of the matrix, whereas scattering waves do not. Based on this property, a correlation matrix filter combining with a time reversal operator is proposed to preserve the direct waves and recover the image behind a scattering layer. Both numerical simulations and photoacoustic imaging experiments demonstrate that the proposed approach effectively increases the image contrast and decreases the background speckles in a scattering medium. This study might improve the quality of photoacoustic imaging in an acoustic scattering environment and extend its applications.

  5. Diffractive scattering

    De Wolf, E.A.

    2002-01-01

    We discuss basic concepts and properties of diffractive phenomena in soft hadron collisions and in deep-inelastic scattering at low Bjorken-x. The paper is not a review of the rapidly developing field but presents an attempt to show in simple terms the close inter-relationship between the dynamics of high-energy hadronic and deep-inelastic diffraction. Using the saturation model of Golec-Biernat and Wusthoff as an example, a simple explanation of geometrical scaling is presented. The relation between the QCD anomalous multiplicity dimension and the Pomeron intercept is discussed.

  6. Diffractive Scattering

    Wolf, E.A. de

    2002-01-01

    We discuss basic concepts and properties of diffractive phenomena in soft hadron collisions and in deep-inelastic scattering at low Bjorken - x. The paper is not a review of the rapidly developing field but presents an attempt to show in simple terms the close inter-relationship between the dynamics of high-energy hadronic and deep-inelastic diffraction. Using the saturation model of Golec-Biernat and Wuesthoff as an example, a simple explanation of geometrical scaling is presented. The relation between the QCD anomalous multiplicity dimension and the Pomeron intercept is discussed. (author)

  7. Neutron scattering

    1991-02-01

    The annual report on hand gives an overview of the research work carried out in the Laboratory for Neutron Scattering (LNS) of the ETH Zuerich in 1990. Using the method of neutron scattering, it is possible to examine in detail the static and dynamic properties of the condensed material. In accordance with the multidisciplined character of the method, the LNS has for years maintained a system of intensive co-operation with numerous institutes in the areas of biology, chemistry, solid-state physics, crystallography and materials research. In 1990 over 100 scientists from more than 40 research groups both at home and abroad took part in the experiments. It was again a pleasure to see the number of graduate students present, who were studying for a doctorate and who could be introduced into the neutron scattering during their stay at the LNS and thus were in the position to touch on central ways of looking at a problem in their dissertation using this modern experimental method of solid-state research. In addition to the numerous and interesting ways of formulating the questions to explain the structure, nowadays the scientific programme increasingly includes particularly topical studies in connection with high temperature-supraconductors and materials research

  8. Neutron scattering and magnetism

    Mackintosh, A.R.

    1983-01-01

    Those properties of the neutron which make it a unique tool for the study of magnetism are described. The scattering of neutrons by magnetic solids is briefly reviewed, with emphasis on the information on the magnetic structure and dynamics which is inherent in the scattering cross-section. The contribution of neutron scattering to our understanding of magnetic ordering, excitations and phase transitions is illustrated by experimental results on a variety of magnetic crystals. (author)

  9. Measurement of Feynman-x spectra of photons and neutrons in the very forward direction in deep-inelastic scattering at HERA

    Andreev, V.; Belousov, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Vazdik, Y. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A.; Zohrabyan, H. [Yerevan Physics Institute, Yerevan (Armenia); Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Belov, P.; Brinkmann, M.; Britzger, D.; Campbell, A.J.; Dodonov, V.; Eckerlin, G.; Elsen, E.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Gouzevitch, M.; Haidt, D.; Kleinwort, C.; Krueger, K.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Petrukhin, A.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Radescu, V.; Schmitt, S.; Sefkow, F.; Shushkevich, S.; South, D.; Steder, M.; Wuensch, E. [DESY, Hamburg (Germany); Boudry, V.; Specka, A. [LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau (France); Brandt, G. [Oxford University, Department of Physics, Oxford (United Kingdom); Brisson, V.; Jacquet, M.; Pascaud, C.; Zhang, Z.; Zomer, F. [LAL, Universite Paris-Sud, CNRS/IN2P3, Orsay (France); Buniatyan, A.; Huber, F.; Sauter, M.; Schoening, A. [Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Bylinkin, A.; Bystritskaya, L.; Fedotov, A.; Rostovtsev, A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Cantun Avila, K.B.; Contreras, J.G. [CINVESTAV, Departamento de Fisica Aplicada, Merida, Yucatan (Mexico); Ceccopieri, F.; Favart, L.; Grebenyuk, A.; Hreus, T.; Janssen, X.; Roosen, R.; Mechelen, P. van [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (Belgium); Cerny, K.; Pokorny, B.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Zlebcik, R. [Charles University, Faculty of Mathematics and Physics, Prague (Czech Republic); Chekelian, V.; Grindhammer, G.; Kiesling, C. [Max-Planck-Institut fuer Physik, Munich (Germany); Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kostka, P.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D. [University of Liverpool, Department of Physics, Liverpool (United Kingdom); Daum, K.; Meyer, H. [Fachbereich C, Universitaet Wuppertal, Wuppertal (Germany); Diaconu, C.; Hoffmann, D.; Sauvan, E.; Vallee, C. [CPPM, Aix-Marseille Univ, CNRS/IN2P3, Marseille (France); Dobre, M.; Rotaru, M. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Dossanov, A. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Max-Planck-Institut fuer Physik, Munich (Germany); Egli, S.; Horisberger, R. [Paul Scherrer Institut, Villigen (Switzerland); Feltesse, J.; Perez, E.; Schoeffel, L. [CEA, DSM/Irfu, CE-Saclay, Gif-sur-Yvette (France); Ferencei, J. [Slovak Academy of Sciences, Institute of Experimental Physics, Kosice (Slovakia); Goerlich, L.; Mikocki, S.; Nowak, G.; Sopicki, P.; Turnau, J. [Institute for Nuclear Physics, Cracow (Poland); Grab, C. [Institut fuer Teilchenphysik, ETH, Zurich (Switzerland); Henderson, R.C.W. [University of Lancaster, Department of Physics, Lancaster (United Kingdom); Herbst, M.; Schultz-Coulon, H.C. [Kirchhoff-Institut fuer Physik, Universitaet Heidelberg, Heidelberg (Germany); Hladky, J.; Reimer, P. [Academy of Sciences of the Czech Republic, Institute of Physics, Prague (Czech Republic); Jung, H. [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (Belgium); DESY, Hamburg (Germany); Kapichine, M.; Lytkin, L.; Morozov, A.; Spaskov, V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kogler, R.; Nowak, K. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Landon, M.P.J.; Rizvi, E.; Traynor, D. [University of London, School of Physics and Astronomy, Queen Mary, London (GB); Lange, W.; Naumann, T. [DESY, Zeuthen (DE); Martyn, H.U. [I. Physikalisches Institut der RWTH, Aachen (DE); Mueller, K.; Robmann, P.; Straumann, U.; Truoel, P. [Physik-Institut der Universitaet Zuerich, Zurich (CH); Newman, P.R.; Thompson, P.D. [School of Physics and Astronomy, University of Birmingham, Birmingham (GB); Picuric, I.; Raicevic, N. [University of Montenegro, Faculty of Science, Podgorica (ME); Povh, B. [Max-Planck-Institut fuer Kernphysik, Heidelberg (DE); Sankey, D.P.C. [STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire (GB); Soloviev, Y. [DESY, Hamburg (DE); Lebedev Physical Institute, Moscow (RU); Stella, B. [Dipartimento di Fisica Universita di Roma Tre (IT); INFN Roma 3, Rome (IT); Sykora, T. [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (BE); Charles University, Faculty of Mathematics and Physics, Prague (CZ); Tsakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (BG); Wegener, D. [Institut fuer Physik, TU Dortmund, Dortmund (DE); Collaboration: H1 Collaboration

    2014-06-15

    Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to the proton beam direction in deep-inelastic ep scattering at HERA are presented as a function of the Feynman variable x{sub F} and of the centre-of-mass energy of the virtual photon-proton system W. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 131 pb{sup -1}. The measurement is restricted to photons and neutrons in the pseudorapidity range η > 7.9 and covers the range of negative four momentum transfer squared at the positron vertex 6 < Q{sup 2} < 100 GeV{sup 2}, of inelasticity 0.05 < y < 0.6 and of 70 < W < 245 GeV. To test the Feynman scaling hypothesis the W dependence of the x{sub F} dependent cross sections is investigated. Predictions of deep-inelastic scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections. (orig.)

  10. Structure property relationship of biological nano composites studies by combination of in-situ synchrotron scattering and mechanical tests

    Martinschitz, K.

    2005-06-01

    Biological materials represent hierarchical nano fibre composites with complicated morphology and architecture varying on the nm level. The mechanical response of those materials is influenced by many parameters like chemical composition and crystal structure of constituents, preferred orientation, internal morphology with specific sizes of features etc. In-situ wide-angle x-ray scattering (WAXS) combined with mechanical tests provide a unique means to evaluate structural changes in biological materials at specific stages of tensile experiments. In this way it is possible to identify distinct architectural/compositional elements responsible for specific mechanical characteristics of the biological materials. In this thesis, structure-property relationship is analyzed using in-situ WAXS in the tissues of Picea abies, coir fibre, bacterial cellulose and cellulose II based composites. The experiments were performed at the beamline ID01 of European synchrotron radiation facility in Grenoble, France. The tissues were strained in a tensile stage, while the structural changes were monitored using WAXS. Complex straining procedures were applied including cyclic straining. One of the main goals was to understand the stiffness recovery and strain hardening effects in the tissues. The results demonstrate that, in all cellulosics, the orientation of the cellulose crystallites is only the function of the external strain while the stiffness depends on the specific stage of the tensile experiment. Whenever the strain is increased, the tissues exhibit stiffness equal or larger than the initial one. The recovery of the mechanical function is attributed to the molecular mechanistic effects operating between the crystalline domains of the cellulose. (author)

  11. Continuity of the direct and inverse problems in one-dimensional scattering theory and numerical solution of the inverse problem

    Moura, C.A. de.

    1976-09-01

    We propose an algorithm for computing the potential V(x) associated to the one-dimensional Schroedinger operator E identical to - d 2 /dx 2 + V(x) -infinite < x< infinite from knowledge of the S.matrix, more exactly, of one of the reelection coefficients. The convergence of the algorithm is guaranteed by the stability results obtained for both the direct and inverse problems

  12. Effect of growth anisotropy on the morphology and property of directionally solidified RE123

    Nakamura, Yuichi; Shibusawa, Akira; Ooishi, Yoshihiro; Misu, Tomohiko; Inada, Ryoji; Oota, Akio

    2005-01-01

    The REBa 2 Cu 3 O y (RE123: RE = Y, Sm, Gd etc.) superconducting current lead is a favorable application due to the high J c properties and low thermal conductivity. Since the RE123 crystal shows the anisotropy in the J c properties as well as the mechanical properties, the ab-plane of the crystal parallel to the growth direction is preferable. The preferential growth direction during directional solidification is determined by the growth anisotropy in the early stage of the growth. In order to get the fundamental information to control the growth orientation, we investigated the growth rates of the Gd123 and Sm123 crystals against the undercooling and the continuous growth condition of Sm123 in directional solidification process. The growth rates of Sm123 and Gd123 were found to be about 5-10 times larger than that of Y123 at the same undercooling. The Sm123 showed the continuous growth structure up to 15 mm/h for fiber samples and up to 10 mm/h for 2 mm circle rods by the zone melting process. These pulling rates for continuous growth are larger than those of Y123 although the difference in growth rates between Sm123 and Y123 is much larger than this difference

  13. A short note on physical properties to irradiated nuclear fuel by means of X-ray diffraction and neutron scattering techniques

    Abdullah, Yusof, E-mail: yusofabd@nuclearmalaysia.gov.my; Husain, Hishamuddin; Hak, Cik Rohaida Che; Alias, Nor Hayati; Yusof, Mohd Reusmaazran; Kasim, Norasiah Ab; Zali, Nurazila Mat [Malaysian Nuclear Agency, Bangi, Kajang 43000, Selangor (Malaysia); Mohamed, Abdul Aziz [College of Engineering, Universiti Tenaga National, Jalan Ikram-Uniten, 43000 Kajang, Selangor (Malaysia)

    2015-04-29

    For nuclear reactor applications, understanding the evolution of the fuel materials microstructure during irradiation are of great importance. This paper reviews the physical properties of irradiated nuclear fuel analysis which are considered to be of most importance in determining the performance behavior of fuel. X-rays diffraction was recognize as important tool to investigate the phase identification while neutron scattering analyses the interaction between uranium and other materials and also investigation of the defect structure.

  14. High-resolution He beam scattering as a tool for the investigation of the structural and dynamical properties of surface soliton dislocations

    El-Batanouny, M.; Martini, K.M.

    1986-01-01

    We discuss the applicability of high-resolution-He-beam/surface scattering to the investigation of the structural and dynamic properties of soliton-like surface misfit dislocations and associated phase transitions. We present evidence, based on recent He diffraction measurements, for the existence of double-sine-Gordon soliton-like dislocations on the reconstructed Au(111) surface. 18 refs., 3 figs., 1 tab

  15. Pion-pion scattering

    Kuehnelt, H.

    1975-01-01

    We discuss a few properties of scattering amplitudes proved within the framework of the field theory and their significance in the derivation of quantitative statements. The state of the boundaries for the scattering lengths is to be especially discussed as well as the question as to how far it is possible to exclude various solutions from phase displacement analyses. (orig./LH) [de

  16. Development study of the X-ray scattering properties of a group of optically polished flat samples

    Froechtenigt, J. F.

    1973-01-01

    A group of twelve optically polished flat samples were used to study the scattering of X-rays. The X-ray beam reflected from the twelve optical flat samples was analyzed by means of a long vacuum system of special design for these tests. The scattering measurements were made at 8.34A and 0.92 deg angle of incidence. The results for ten of the samples are comparable, the two exceptions being the fire polished samples.

  17. Regge poles and alpha scattering

    Ceuleneer, R.

    1974-01-01

    The direct Regge pole model as a means of describing resonances in elastic particle scattering has been used for the analysis of the so-called ''anormalous large angle scattering'' of alpha particles by spinless nuclei. (Z.M.)

  18. Predictive modeling capabilities from incident powder and laser to mechanical properties for laser directed energy deposition

    Shin, Yung C.; Bailey, Neil; Katinas, Christopher; Tan, Wenda

    2018-01-01

    This paper presents an overview of vertically integrated comprehensive predictive modeling capabilities for directed energy deposition processes, which have been developed at Purdue University. The overall predictive models consist of vertically integrated several modules, including powder flow model, molten pool model, microstructure prediction model and residual stress model, which can be used for predicting mechanical properties of additively manufactured parts by directed energy deposition processes with blown powder as well as other additive manufacturing processes. Critical governing equations of each model and how various modules are connected are illustrated. Various illustrative results along with corresponding experimental validation results are presented to illustrate the capabilities and fidelity of the models. The good correlations with experimental results prove the integrated models can be used to design the metal additive manufacturing processes and predict the resultant microstructure and mechanical properties.

  19. THERMAL AND DIELECTRIC PROPERTIES OF PINE WOOD IN THE TRANSVERSE DIRECTION

    Hamiyet Şahin Kol

    2009-11-01

    Full Text Available In this paper, the thermal conductivity and dielectric parameters for pine [Pinus sylvestris (L.] woods were determined in transverse directions for moisture conditions from oven-dry to 22 percent at a room temperature of 22 to 24 °C. Results indicate that the behaviors of thermal conductivity and dielectric parameters with moisture content and structural directions were similar. In general, the properties increased within the range studied with increasing moisture content. The radial values were similar to tangential values for both thermal conductivity and dielectric properties. The data presented here should be useful in most design problems where pine wood is subjected to microwave electric fields and heat changes.

  20. Predictive modeling capabilities from incident powder and laser to mechanical properties for laser directed energy deposition

    Shin, Yung C.; Bailey, Neil; Katinas, Christopher; Tan, Wenda

    2018-05-01

    This paper presents an overview of vertically integrated comprehensive predictive modeling capabilities for directed energy deposition processes, which have been developed at Purdue University. The overall predictive models consist of vertically integrated several modules, including powder flow model, molten pool model, microstructure prediction model and residual stress model, which can be used for predicting mechanical properties of additively manufactured parts by directed energy deposition processes with blown powder as well as other additive manufacturing processes. Critical governing equations of each model and how various modules are connected are illustrated. Various illustrative results along with corresponding experimental validation results are presented to illustrate the capabilities and fidelity of the models. The good correlations with experimental results prove the integrated models can be used to design the metal additive manufacturing processes and predict the resultant microstructure and mechanical properties.

  1. The finite element model for the propagation of light in scattering media: a direct method for domains with nonscattering regions.

    Arridge, S R; Dehghani, H; Schweiger, M; Okada, E

    2000-01-01

    We present a method for handling nonscattering regions within diffusing domains. The method develops from an iterative radiosity-diffusion approach using Green's functions that was computationally slow. Here we present an improved implementation using a finite element method (FEM) that is direct. The fundamental idea is to introduce extra equations into the standard diffusion FEM to represent nondiffusive light propagation across a nonscattering region. By appropriate mesh node ordering the computational time is not much greater than for diffusion alone. We compare results from this method with those from a discrete ordinate transport code, and with Monte Carlo calculations. The agreement is very good, and, in addition, our scheme allows us to easily model time-dependent and frequency domain problems.

  2. Ultrasensitive Direct Quantification of Nucleobase Modifications in DNA by Surface-Enhanced Raman Scattering: The Case of Cytosine.

    Morla-Folch, Judit; Xie, Hai-nan; Gisbert-Quilis, Patricia; Gómez-de Pedro, Sara; Pazos-Perez, Nicolas; Alvarez-Puebla, Ramon A; Guerrini, Luca

    2015-11-09

    Recognition of chemical modifications in canonical nucleobases of nucleic acids is of key importance since such modified variants act as different genetic encoders, introducing variability in the biological information contained in DNA. Herein, we demonstrate the feasibility of direct SERS in combination with chemometrics and microfluidics for the identification and relative quantification of 4 different cytosine modifications in both single- and double-stranded DNA. The minute amount of DNA required per measurement, in the sub-nanogram regime, removes the necessity of pre-amplification or enrichment steps (which are also potential sources of artificial DNA damages). These findings show great potentials for the development of fast, low-cost and high-throughput screening analytical devices capable of detecting known and unknown modifications in nucleic acids (DNA and RNA) opening new windows of activity in several fields such as biology, medicine and forensic sciences. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. The CU 2-D-MAX-DOAS instrument – Part 2: Raman scattering probability measurements and retrieval of aerosol optical properties

    Ortega, Ivan; Coburn, Sean; Berg, Larry K.; Lantz, Kathy; Michalsky, Joseph; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Volkamer, Rainer

    2016-01-01

    The multiannual global mean of aerosol optical depth at 550 nm (AOD550) over land is ~0.19, and that over oceans is ~0.13. About 45 % of the Earth surface shows AOD550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions. We present an inherently calibrated retrieval (i.e., no need for radiance calibration) to simultaneously measure AOD and the aerosol phase function parameter, g, based on measurements of azimuth distributions of the Raman scattering probability (RSP), the near-absolute rotational Raman scattering (RRS) intensity. We employ radiative transfer model simulations to show that for solar azimuth RSP measurements at solar elevation and solar zenith angle (SZA) smaller than 80°, RSP is insensitive to the vertical distribution of aerosols and maximally sensitive to changes in AOD and g under near-molecular scattering conditions. The University of Colorado two-dimensional Multi-AXis Differential Optical Absorption Spectroscopy (CU 2-D-MAX-DOAS) instrument was deployed as part of the Two Column Aerosol Project (TCAP) at Cape Cod, MA, during the summer of 2012 to measure direct sun spectra and RSP from scattered light spectra at solar relative azimuth angles (SRAAs) between 5 and 170°. During two case study days with (1) high aerosol load (17 July, 0.3 < AOD430 < 0.6) and (2) near-molecular scattering conditions (22 July, AOD430 < 0.13) we compare RSP-based retrievals of AOD430 and g with data from a co-located CIMEL sun photometer, Multi-Filter Rotating Shadowband Radiometer (MFRSR), and an airborne High Spectral Resolution Lidar (HSRL-2). The average difference (relative to DOAS) for AOD430 is +0.012 ± 0.023 (CIMEL), -0.012 ± 0.024 (MFRSR), -0.011 ± 0.014 (HSRL-2), and +0.023 ± 0.013 (CIMELAOD - MFRSRAOD) and yields the following

  4. Monthly and seasonal variations of aerosol optical properties and direct radiative forcing over Zanjan, Iran

    Gharibzadeh, Maryam; Alam, Khan; Abedini, Yousefali; Bidokhti, Abbasali Aliakbari; Masoumi, Amir

    2017-11-01

    Aerosol optical properties and radiative forcing over Zanjan in northwest of Iran has been analyzed during 2010-2013. The aerosol optical and radiative properties are less studied over Zanjan, and therefore, require a careful and in depth analysis. The optical properties like Aerosol Optical Depth (AOD), Ångström Exponent (AE), ASYmmetry parameter (ASY), Single Scattering Albedo (SSA), and Aerosol Volume Size Distribution (AVSD) have been evaluated using the ground-based AErosol RObotic NETwork (AERONET) data. Higher AOD while relatively lower AE were observed in the spring and summer, which showed the presence of coarse mode particles in these seasons. An obvious increase of coarse mode particles in AVSD distribution, as well as a higher value of SSA represented considerable addition of coarse mode particles like dust into the atmosphere of Zanjan in these two seasons. Increase in AE, while a decrease in AOD was detected in the winter and fall. The presence of fine particles indicates the dominance of particles like urban-industrial aerosols from local sources especially in the winter. The Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model was utilized to calculate the Aerosol Radiative Forcing (ARF) at the Top of the Atmosphere (TOA), earth's surface and within the atmosphere. The annual averaged ARF values were -13.47 W m-2 and -36.1 W m-2 at the TOA and earth's surface, respectively, which indicate a significant cooling effect. Likewise, the ARF efficiencies at the TOA and earth's surface were -65.08 W m-2 and -158.43 W m-2, respectively. The annual mean atmospheric ARF and heating rate within the atmosphere were 22.63 W m-2 and 0.27 Kday-1 respectively, represented the warming effect within the atmosphere. Finally, a good agreement was found between AERONET retrieved ARF and SBDART simulated ARF.

  5. Direct prediction of spatially and temporally varying physical properties from time-lapse electrical resistance data

    Hermans, Thomas; Oware, Erasmus; Caers, Jef

    2016-09-01

    Time-lapse applications of electrical methods have grown significantly over the last decade. However, the quantitative interpretation of tomograms in terms of physical properties, such as salinity, temperature or saturation, remains difficult. In many applications, geophysical models are transformed into hydrological models, but this transformation suffers from spatially and temporally varying resolution resulting from the regularization used by the deterministic inversion. In this study, we investigate a prediction-focused approach (PFA) to directly estimate subsurface physical properties with electrical resistance data, circumventing the need for classic tomographic inversions. First, we generate a prior set of resistance data and physical property forecast through hydrogeological and geophysical simulations mimicking the field experiment. We reduce the dimension of both the data and the forecast through principal component analysis in order to keep the most informative part of both sets in a reduced dimension space. Then, we apply canonical correlation analysis to explore the relationship between the data and the forecast in their reduced dimension space. If a linear relationship can be established, the posterior distribution of the forecast can be directly sampled using a Gaussian process regression where the field data scores are the conditioning data. In this paper, we demonstrate PFA for various physical property distributions. We also develop a framework to propagate the estimated noise level in the reduced dimension space. We validate the results by a Monte Carlo study on the posterior distribution and demonstrate that PFA yields accurate uncertainty for the cases studied.

  6. Nanofluid Types, Their Synthesis, Properties and Incorporation in Direct Solar Thermal Collectors: A Review

    Wisut Chamsa-ard

    2017-05-01

    Full Text Available The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented.

  7. Nanofluid Types, Their Synthesis, Properties and Incorporation in Direct Solar Thermal Collectors: A Review.

    Chamsa-Ard, Wisut; Brundavanam, Sridevi; Fung, Chun Che; Fawcett, Derek; Poinern, Gerrard

    2017-05-31

    The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented.

  8. Note on the directional properties of meter-scale gravity waves

    Peureux, Charles; Benetazzo, Alvise; Ardhuin, Fabrice

    2018-01-01

    The directional distribution of the energy of young waves is bimodal for frequencies above twice the peak frequency; i.e., their directional distribution exhibits two peaks in different directions and a minimum between. Here we analyze in detail a typical case measured with a peak frequency fp = 0.18 Hz and a wind speed of 10.7 m s-1 using a stereo-video system. This technique allows for the separation of free waves from the spectrum of the sea-surface elevation. The latter indeed tend to reduce the contrast between the two peaks and the background. The directional distribution for a given wavenumber is nearly symmetric, with the angle distance between the two peaks growing with frequency, reaching 150° at 35 times the peak wavenumber kp and increasing up to 45 kp. When considering only free waves, the lobe ratio, the ratio of oblique peak energy density over energy in the wind direction, increases linearly with the non-dimensional wavenumber k/kp, up to a value of 6 at k/kp ≃ 22, and possibly more for shorter components. These observations extend to shorter components' previous measurements, and have important consequences for wave properties sensitive to the directional distribution, such as surface slopes, Stokes drift or microseism sources.

  9. Note on the directional properties of meter-scale gravity waves

    C. Peureux

    2018-01-01

    Full Text Available The directional distribution of the energy of young waves is bimodal for frequencies above twice the peak frequency; i.e., their directional distribution exhibits two peaks in different directions and a minimum between. Here we analyze in detail a typical case measured with a peak frequency fp = 0.18 Hz and a wind speed of 10.7 m s−1 using a stereo-video system. This technique allows for the separation of free waves from the spectrum of the sea-surface elevation. The latter indeed tend to reduce the contrast between the two peaks and the background. The directional distribution for a given wavenumber is nearly symmetric, with the angle distance between the two peaks growing with frequency, reaching 150° at 35 times the peak wavenumber kp and increasing up to 45 kp. When considering only free waves, the lobe ratio, the ratio of oblique peak energy density over energy in the wind direction, increases linearly with the non-dimensional wavenumber k∕kp, up to a value of 6 at k∕kp ≃ 22, and possibly more for shorter components. These observations extend to shorter components' previous measurements, and have important consequences for wave properties sensitive to the directional distribution, such as surface slopes, Stokes drift or microseism sources.

  10. Visual perception of dynamic properties: cue heuristics versus direct-perceptual competence.

    Runeson, S; Juslin, P; Olsson, H

    2000-07-01

    Constructivist and Gibsonian approaches disagree over the possibility of direct perceptual use of advanced information. A trenchant instance concerns visual perception of underlying dynamic properties as specified by kinematic patterns of events. For the paradigmatic task of discrimination of relative mass in observed collisions, 2 mathematical models are developed, 1 model representing a direct, invariant-based approach, and 1 representing a cue-heuristic approach. The models enable a critical experimental design with distinct predictions concerning performance data and confidence ratings. Although pretraining results were mixed, the invariant-based model was empirically confirmed after a minimal amount of training: Competence entails the use of advanced kinematic information in a direct-perceptual ("sensory") mode of apprehension, in contrast to beginners' use of simpler cues in an inferential ("cognitive") mode.

  11. Scattering with polarized neutrons

    Schweizer, J.

    2007-01-01

    In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)

  12. Preparation and Properties of Asphalt Binders Modified by THFS Extracted From Direct Coal Liquefaction Residue

    Jie Ji

    2017-11-01

    Full Text Available This paper aims to study the preparation and viscoelastic properties of asphalt binder modified by tetrahydrofuran soluble fraction (THFS extracted from direct coal liquefaction residue. The modified asphalt binders, which blended with SK-90 (control asphalt binder and 4%, 6%, 8% and 10% THFS (by weight of SK-90, were fabricated. The preparation process for asphalt binder was optimized in terms of the orthogonal array test strategy and gray correlation analysis results. The properties of asphalt binder were measured by applying Penetration performance grade and Superpave performance grade specifications. In addition, the temperature step and frequency sweep test in Dynamic Shear Rheometer were conducted to predict the rheological behavior, temperature and frequency susceptibility of asphalt binder. The test results suggested the optimal preparation process, such as 150 °C shearing temperature, 45 min shearing time and 4000 rpm shearing rate. Subsequently, the addition of THFS was beneficial in increasing the high-temperature properties but decreased the low-temperature properties and resistance to fatigue. The content analysis of THFS showed the percentage of 4~6% achieved a balance in the high-and-low temperature properties of asphalt binder. The asphalt binder with higher THFS content exhibited higher resistance to rutting and less sensitivity to frequency and temperature.

  13. Nuclear structure of weakly bound radioactive nuclei through elastic and and inelastic scattering on proton. Impacts of the couplings induced by these exotic nuclei on direct reactions

    Lapoux, V.

    2005-09-01

    Information on the structure, spectroscopy and target interaction potentials of exotic nuclei can be inferred by interpreting measured data from direct reactions on proton such as elastic or inelastic scattering of proton (p,p') or one-nucleon transfer reaction (p,d). A series of experimental results has been obtained at the GANIL facilities on the setting composed of the MUST telescope array used for the detection of light charged-particles and of CATS beam detectors. This setting aims at measuring reactions on light proton or deuteron targets through reverse kinematics. Particularly, results on C 10 , C 11 and on direct reactions with the He 8 beam of Spiral are presented. The first chapter is dedicated to the description of the most important theories concerning the nucleus. The experimental tools used to probe the nucleus are reported in the second chapter. The third and fourth chapters present the framework that has allowed us to analyse results from (p,p') and (p,d) reactions on weakly bound exotic nuclei. The last chapter is dedicated to the description of future experimental programs. (A.C.)

  14. Self-Assembled Nanocube-Based Plasmene Nanosheets as Soft Surface-Enhanced Raman Scattering Substrates toward Direct Quantitative Drug Identification on Surfaces.

    Si, Kae Jye; Guo, Pengzhen; Shi, Qianqian; Cheng, Wenlong

    2015-05-19

    We report on self-assembled nanocube-based plasmene nanosheets as new surface-enhanced Raman scattering (SERS) substrates toward direct identification of a trace amount of drugs sitting on topologically complex real-world surfaces. The uniform nanocube arrays (superlattices) led to low spatial SERS signal variances (∼2%). Unlike conventional SERS substrates which are based on rigid nanostructured metals, our plasmene nanosheets are mechanically soft and optically semitransparent, enabling conformal attachment to real-world solid surfaces such as banknotes for direct SERS identification of drugs. Our plasmene nanosheets were able to detect benzocaine overdose down to a parts-per-billion (ppb) level with an excellent linear relationship (R(2) > 0.99) between characteristic peak intensity and concentration. On banknote surfaces, a detection limit of ∼0.9 × 10(-6) g/cm(2) benzocaine could be achieved. Furthermore, a few other drugs could also be identified, even in their binary mixtures with our plasmene nanosheets. Our experimental results clearly show that our plasmene sheets represent a new class of unique SERS substrates, potentially serving as a versatile platform for real-world forensic drug identification.

  15. Cross plane scattering correction

    Shao, L.; Karp, J.S.

    1990-01-01

    Most previous scattering correction techniques for PET are based on assumptions made for a single transaxial plane and are independent of axial variations. These techniques will incorrectly estimate the scattering fraction for volumetric PET imaging systems since they do not take the cross-plane scattering into account. In this paper, the authors propose a new point source scattering deconvolution method (2-D). The cross-plane scattering is incorporated into the algorithm by modeling a scattering point source function. In the model, the scattering dependence both on axial and transaxial directions is reflected in the exponential fitting parameters and these parameters are directly estimated from a limited number of measured point response functions. The authors' results comparing the standard in-plane point source deconvolution to the authors' cross-plane source deconvolution show that for a small source, the former technique overestimates the scatter fraction in the plane of the source and underestimate the scatter fraction in adjacent planes. In addition, the authors also propose a simple approximation technique for deconvolution

  16. EFFECT OF THE B DRIFT DIRECTION ON PLASMA EDGE PROPERTIES AND THEL-H TRANSITION ON DIII-D

    T.N. CARLSTROM; R.J. GROEBNER; G.R. McKEE; R.A. MOYER; T.L. RHODES; J.C. ROST; G.D. PORTER X.Q. XU; W.M. NEVINS

    2002-07-01

    The power threshold for the L-H transition, P{sub TH}, is low when the ion {del}B drift is toward the X-point and increases significantly when it is away from the X-point. In order to study the cause of this effect, we have compared lower single-null (LSN) discharges with upper single-null (USN) discharges where the ion {del}B drift direction is down in both cases. Since many plasma parameters change with input power, we have made comparisons at the same power level (PTOT=2.3 MW). For these experiments, the LSN discharge is just below PTH (2.7 MW) and the USN discharge is far from P{sub TH} (6.8 MW). We have measured various properties of the edge plasma in an attempt to identify changes that may be responsible for the difference in P{sub TH} for the two cases. The equilibrium flux surfaces and diagnostic measurement locations are shown. The most pronounced difference is the reversal and the increased shear in the poloidal group velocity of the density fluctuations near the plasma edge [1]. These results complement a previous study where the plasma configuration was held fixed and the toroidal field was reversed [2]. In that study, differences in the divertor and X-point plasma were measured. In the present work, the X-point could not be located in the range of the divertor Thomson scattering diagnostic due to top/bottom symmetry issues, and those measurements are not available.

  17. Theory of Graphene Raman Scattering.

    Heller, Eric J; Yang, Yuan; Kocia, Lucas; Chen, Wei; Fang, Shiang; Borunda, Mario; Kaxiras, Efthimios

    2016-02-23

    Raman scattering plays a key role in unraveling the quantum dynamics of graphene, perhaps the most promising material of recent times. It is crucial to correctly interpret the meaning of the spectra. It is therefore very surprising that the widely accepted understanding of Raman scattering, i.e., Kramers-Heisenberg-Dirac theory, has never been applied to graphene. Doing so here, a remarkable mechanism we term"transition sliding" is uncovered, explaining the uncommon brightness of overtones in graphene. Graphene's dispersive and fixed Raman bands, missing bands, defect density and laser frequency dependence of band intensities, widths of overtone bands, Stokes, anti-Stokes anomalies, and other known properties emerge simply and directly.

  18. Microstructure and mechanical properties of direct metal laser sintered TI-6AL-4V

    Becker, Thorsten Hermann

    2015-05-01

    Full Text Available Direct metal laser sintering (DMLS is a selective laser melting (SLM manufacturing process that can produce near net shape parts from metallic powders. A range of materials are suitable for SLM; they include various metals such as titanium, steel, aluminium, and cobalt-chrome alloys. This paper forms part of a research drive that aims to evaluate the material performance of the SLM-manufactured metals. It presents DMLS-produced Ti-6Al-4V, a titanium alloy often used in biomedical and aerospace applications. This paper also studies the effect of several heat treatments on the microstructure and mechanical properties of Ti-6Al-4V processed by SLM. It reports the achievable mechanical properties of the alloy, including quasi-static, crack growth behaviour, density and porosity distribution, and post-processing using various heat-treatment conditions.

  19. The effect of linear imperfection in [001] direction on the thermal properties of silver crystal

    J Davoodi

    2013-09-01

    Full Text Available  The aim of this investigation was to calculate the thermal properties of silver crystal in the presence of linear imperfection. The simulations were performed by molecular dynamics simulation technique in NPT as well as NVT ensemble based on quantum Sutton-Chen many body potential. The thermal properties including cohesive energy, melting temperature, isobaric heat capacity and thermal expansion of imperfect silver crystal were calculated and compared to those of the perfect crystal. Moreover, the quantities such as radial distribution function, order parameter and lindemann index were calculated in order to obtain information on crystal structure and disorder in atoms. All calculations were done both with liner imperfection in [001] direction and without imperfection at different temperature. The simulation results show that cohesive energy, linear thermal expansion coefficient increase and melting temperature, latent heat of fusion decrease with increasing linear imperfection. Also, the results show that linear imperfection has no effect on the heat capacity.

  20. Properties of Laser-Produced Highly Charged Heavy Ions for Direct Injection Scheme

    Sakakibara, Kazuhiko; Hayashizaki, Noriyosu; Ito, Taku; Kashiwagi, Hirotsugu; Okamura, Masahiro

    2005-01-01

    To accelerate highly charged intense ion beam, we have developed the Direct Plasma Injection Scheme (DPIS) with laser ion source. In this scheme an ion beam from a laser ion source is injected directly to a RFQ linac without a low energy beam transport (LEBT) and the beam loss in the LEBT can be avoided. We achieved high current acceleration of carbon ions (60mA) by DPIS with the high current optimized RFQ. As the next setp we will use heavier elements like Ag, Pb, Al and Cu as target in LIS (using CO2, Nd-YAG or other laser) for DPIS and will examine properties of laser-produced plasma (the relationship of between charge state and laser power density, the current dependence of the distance from the target, etc).

  1. Evaluation of glass transition temperature and dynamic mechanical properties of autopolymerized hard direct denture reline resins.

    Takase, Kazuma; Watanabe, Ikuya; Kurogi, Tadafumi; Murata, Hiroshi

    2015-01-01

    This study assessed methods for evaluation of glass transition temperature (Tg) of autopolymerized hard direct denture reline resins using dynamic mechanical analysis and differential scanning calorimetry in addition to the dynamic mechanical properties. The Tg values of 3 different reline resins were determined using a dynamic viscoelastometer and differential scanning calorimeter, and rheological parameters were also determined. Although all materials exhibited higher storage modulus and loss modulus values, and a lower loss tangent at 37˚C with a higher frequency, the frequency dependence was not large. Tg values obtained by dynamic mechanical analysis were higher than those by differential scanning calorimetry and higher frequency led to higher Tg, while more stable Tg values were also obtained by that method. These results suggest that dynamic mechanical analysis is more advantageous for characterization of autopolymerized hard direct denture reline resins than differential scanning calorimetry.

  2. Fast radiative transfer models for retrieval of cloud properties in the back-scattering region: application to DSCOVR-EPIC sensor

    Molina Garcia, Victor; Sasi, Sruthy; Efremenko, Dmitry; Doicu, Adrian; Loyola, Diego

    2017-04-01

    In this work, the requirements for the retrieval of cloud properties in the back-scattering region are described, and their application to the measurements taken by the Earth Polychromatic Imaging Camera (EPIC) on board the Deep Space Climate Observatory (DSCOVR) is shown. Various radiative transfer models and their linearizations are implemented, and their advantages and issues are analyzed. As radiative transfer calculations in the back-scattering region are computationally time-consuming, several acceleration techniques are also studied. The radiative transfer models analyzed include the exact Discrete Ordinate method with Matrix Exponential (DOME), the Matrix Operator method with Matrix Exponential (MOME), and the approximate asymptotic and equivalent Lambertian cloud models. To reduce the computational cost of the line-by-line (LBL) calculations, the k-distribution method, the Principal Component Analysis (PCA) and a combination of the k-distribution method plus PCA are used. The linearized radiative transfer models for retrieval of cloud properties include the Linearized Discrete Ordinate method with Matrix Exponential (LDOME), the Linearized Matrix Operator method with Matrix Exponential (LMOME) and the Forward-Adjoint Discrete Ordinate method with Matrix Exponential (FADOME). These models were applied to the EPIC oxygen-A band absorption channel at 764 nm. It is shown that the approximate asymptotic and equivalent Lambertian cloud models give inaccurate results, so an offline processor for the retrieval of cloud properties in the back-scattering region requires the use of exact models such as DOME and MOME, which behave similarly. The combination of the k-distribution method plus PCA presents similar accuracy to the LBL calculations, but it is up to 360 times faster, and the relative errors for the computed radiances are less than 1.5% compared to the results when the exact phase function is used. Finally, the linearized models studied show similar behavior

  3. Electron Raman scattering in asymmetrical multiple quantum wells

    Betancourt-Riera, R; Rosas, R; Marin-Enriquez, I; Riera, R; Marin, J L

    2005-01-01

    Optical properties of asymmetrical multiple quantum wells for the construction of quantum cascade lasers are calculated, and expressions for the electronic states of asymmetrical multiple quantum wells are presented. The gain and differential cross-section for an electron Raman scattering process are obtained. Also, the emission spectra for several scattering configurations are discussed, and the corresponding selection rules for the processes involved are studied; an interpretation of the singularities found in the spectra is given. The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers

  4. Effects of anisotropic interaction-induced properties of hydrogen-rare gas compounds on rototranslational Raman scattering spectra: Comprehensive theoretical and numerical analysis

    Głaz, Waldemar, E-mail: glaz@kielich.amu.edu.pl; Bancewicz, Tadeusz [Nonlinear Optics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Godet, Jean-Luc [Laboratoire de Photonique d’Angers, Université d’Angers, 2 Boulevard Lavoisier, 49045 Angers (France); Gustafsson, Magnus [Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-97187 Luleå (Sweden); Haskopoulos, Anastasios; Maroulis, George [Department of Chemistry, University of Patras, GR-26500 Patras (Greece)

    2016-07-21

    A comprehensive study is presented of many aspects of the depolarized anisotropic collision induced (CI) component of light scattered by weakly bound compounds composed of a dihydrogen molecule and a rare gas (Rg) atom, H{sub 2}–Rg. The work continues a series of earlier projects marking the revival of interest in linear light scattering following the development of new highly advanced tools of quantum chemistry and other theoretical, computational, and experimental means of spectral analyses. Sophisticated ab initio computing procedures are applied in order to obtain the anisotropic polarizability component’s dependence on the H{sub 2}–Rg geometry. These data are then used to evaluate the CI spectral lines for all types of Rg atoms ranging from He to Xe (Rn excluded). Evolution of the properties of CI spectra with growing polarizability/masses of the complexes studied is observed. Special attention is given to the heaviest, Kr and Xe based, scatterers. The influence of specific factors shaping the spectral lines (e.g., bound and metastable contribution, potential anisotropy) is discussed. Also the share of pressure broadened allowed rotational transitions in the overall spectral profile is taken into account and the extent to which it is separable from the pure CI contribution is discussed. We finish with a brief comparison between the obtained results and available experimental data.

  5. Off-shell properties of the second-order Born approximation for laser-assisted potential scattering

    Trombetta, F.

    1991-01-01

    A formal method is presented to evaluate the second-order Born approximation of the laser-assisted potential scattering. It is an implicit closure technique that includes intermediate virtual-state transitions and enables one to find the exact explicit expression of the transition amplitude. This is of interest from two standpoints: first, one can deal with ranges of parameters in which the first-order Born approximation is a poor one; second, one can set limits of on-shell approximations that are also widely used to analyze recent laser-assisted experiments. The off-shell character yields new terms in the exact amplitude, and in particular, it is shown to play a crucial role in forward scattering from a long-range potential

  6. A Brillouin scattering study of the effect of chemical passivation on the elastic properties of porous silicon

    Fan, H. J.; Kuok, M. H.; Ng, S. C.; Boukherroub, R.; Lockwood, D. J.

    2002-07-01

    Brillouin scattering has been performed to probe acoustic waves in porous silicon films that have been chemically modified with either 1-decene, decyl aldehyde, undecylenic acid, or ethyl undecylenate. The shift in the frequencies of acoustic modes in the passivated porous silicon samples, relative to those in freshly prepared porous silicon, is different for different chemical modifiers. The magnitude of the frequency shift is qualitatively correlated with the change, caused by the passivation, in the average densities and elastic constants of the samples.

  7. Collective properties of injection-induced earthquake sequences: 1. Model description and directivity bias

    Dempsey, David; Suckale, Jenny

    2016-05-01

    Induced seismicity is of increasing concern for oil and gas, geothermal, and carbon sequestration operations, with several M > 5 events triggered in recent years. Modeling plays an important role in understanding the causes of this seismicity and in constraining seismic hazard. Here we study the collective properties of induced earthquake sequences and the physics underpinning them. In this first paper of a two-part series, we focus on the directivity ratio, which quantifies whether fault rupture is dominated by one (unilateral) or two (bilateral) propagating fronts. In a second paper, we focus on the spatiotemporal and magnitude-frequency distributions of induced seismicity. We develop a model that couples a fracture mechanics description of 1-D fault rupture with fractal stress heterogeneity and the evolving pore pressure distribution around an injection well that triggers earthquakes. The extent of fault rupture is calculated from the equations of motion for two tips of an expanding crack centered at the earthquake hypocenter. Under tectonic loading conditions, our model exhibits a preference for unilateral rupture and a normal distribution of hypocenter locations, two features that are consistent with seismological observations. On the other hand, catalogs of induced events when injection occurs directly onto a fault exhibit a bias toward ruptures that propagate toward the injection well. This bias is due to relatively favorable conditions for rupture that exist within the high-pressure plume. The strength of the directivity bias depends on a number of factors including the style of pressure buildup, the proximity of the fault to failure and event magnitude. For injection off a fault that triggers earthquakes, the modeled directivity bias is small and may be too weak for practical detection. For two hypothetical injection scenarios, we estimate the number of earthquake observations required to detect directivity bias.

  8. Microstructure and Tensile/Corrosion Properties Relationships of Directionally Solidified Al-Cu-Ni Alloys

    Rodrigues, Adilson V.; Lima, Thiago S.; Vida, Talita A.; Brito, Crystopher; Garcia, Amauri; Cheung, Noé

    2018-03-01

    Al-Cu-Ni alloys are of scientific and technological interest due to high strength/high temperature applications, based on the reinforcement originated from the interaction between the Al-rich phase and intermetallic composites. The nature, morphology, size, volume fraction and dispersion of IMCs particles throughout the Al-rich matrix are important factors determining the resulting mechanical and chemical properties. The present work aims to evaluate the effect of the addition of 1wt%Ni into Al-5wt%Cu and Al-15wt%Cu alloys on the solidification rate, macrosegregation, microstructure features and the interrelations of such characteristics on tensile and corrosion properties. A directional solidification technique is used permitting a wide range of microstructural scales to be examined. Experimental growth laws relating the primary and secondary dendritic spacings to growth rate and solidification cooling rate are proposed, and Hall-Petch type equations are derived relating the ultimate tensile strength and elongation to the primary dendritic spacing. Considering a compromise between ultimate tensile strength and corrosion resistance of the examined alloys samples from both alloys castings it is shown that the samples having more refined microstructures are associated with the highest values of such properties.

  9. Comparative study of mechanical properties of direct core build-up materials

    Girish Kumar

    2015-01-01

    Full Text Available Background and Objectives: The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement. Materials and Methods: All the materials were manipulated according to the manufacturer′s recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done. Results: Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus. Conclusions: Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success.

  10. In-field direct combustion fuel property changes of switchgrass harvested from summer to fall

    Ogden, C.A.; Ileleji, K.E. [Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN (United States); Johnson, K.D. [Department of Agronomy, Purdue University, West Lafayette, IN (United States); Wang, Q. [State Key Laboratory for Clean Energy Utilization, Zhejiang University, Hangzhou, 310027 (China)

    2010-03-15

    Switchgrass, a perennial warm-season grass and potential energy crop, is usually harvested during the time between full maturity in the fall to the following spring. During this wide harvest window, the changes in fuel properties that could occur are important for making appropriate decisions with respect to the optimum harvest time for maximum fuel quality. A field plot study was carried out to investigate the quantitative fuel properties (proximate, ultimate and mineral analyses) of switchgrass over a harvest period from crop maturity in July through November. Harvest moisture decreased from July to November and moisture was uniformly distributed in the switchgrass plant at all times in the harvest period. There were significant differences in ash, volatiles, fixed carbon and nitrogen among months of harvest. Nitrogen, ash and fixed carbon contents decreased while oxygen and volatiles increased through the harvest period. Also, there were significant differences in oxides of silicon, calcium, potassium, phosphorus and sulfur among harvest times. The concentration of oxides of potassium and sulfur decreased at the end of the harvesting period. Fouling and slagging indices decreased as harvest was delayed but remained low throughout harvest. However, the decreases are small and might not dramatically impact fouling and slagging. Overall, the results appear to favor a later harvest for switchgrass used for direct combustion. This study will benefit feedstock producers as well as biomass feedstock facility operators by providing a better understanding of how the properties of switchgrass vary over a typical harvest period and their potential effect on boiler equipment. (author)

  11. A polarimetric scattering database for non-spherical ice particles at microwave wavelengths

    Lu, Yinghui; Jiang, Zhiyuan; Aydin, Kultegin; Verlinde, Johannes; Clothiaux, Eugene E.; Botta, Giovanni

    2016-10-01

    The atmospheric science community has entered a period in which electromagnetic scattering properties at microwave frequencies of realistically constructed ice particles are necessary for making progress on a number of fronts. One front includes retrieval of ice-particle properties and signatures from ground-based, airborne, and satellite-based radar and radiometer observations. Another front is evaluation of model microphysics by application of forward operators to their outputs and comparison to observations during case study periods. Yet a third front is data assimilation, where again forward operators are applied to databases of ice-particle scattering properties and the results compared to observations, with their differences leading to corrections of the model state. Over the past decade investigators have developed databases of ice-particle scattering properties at microwave frequencies and made them openly available. Motivated by and complementing these earlier efforts, a database containing polarimetric single-scattering properties of various types of ice particles at millimeter to centimeter wavelengths is presented. While the database presented here contains only single-scattering properties of ice particles in a fixed orientation, ice-particle scattering properties are computed for many different directions of the radiation incident on them. These results are useful for understanding the dependence of ice-particle scattering properties on ice-particle orientation with respect to the incident radiation. For ice particles that are small compared to the wavelength, the number of incident directions of the radiation is sufficient to compute reasonable estimates of their (randomly) orientation-averaged scattering properties. This database is complementary to earlier ones in that it contains complete (polarimetric) scattering property information for each ice particle - 44 plates, 30 columns, 405 branched planar crystals, 660 aggregates, and 640 conical

  12. Screening of several excipients for direct compression of tablets: A new perspective based on functional properties

    John Rojas

    2013-01-01

    Full Text Available Excipients are widely used to formulate solid drug forms by direct compression. However, the powderforming and tableting properties of these excipients are affected by the presence of lubricants and active ingredients. In this study, a screening methodology was employed to test the performance of an excipient for direct compression. The effects of three lubricants (magnesium stearate, stearic acid and talc on the compressibility and compaction of these excipients were assessed by the compressibility index and lubricant sensitivity ratio, respectively. Likewise, the dilution potential in blends with a poorly compactible drug such as acetaminophen was also assessed. Finally, the elastic recovery of tablets was evaluated five days after production. All lubricants increased the compressibility of these excipients and improved their flowability. However, hydrophobic lubricants such as magnesium stearate had a marked negative effect on compactibility, especially in plastic-deforming and more regularlyshaped materials with a smooth surface such as Starch 1500. Alginic acid, rice and cassava starches had the largest elastic recovery (>5%, indicating a tendency to cap. Moreover, highly plastic deforming materials such as sorbitol and polyvinylpyrrolidone (PVP-K30 exhibited the best dilution potential (~10%, whereas alginic acid showed a very high value (~70%. In terms of performance, sorbitol, PVP-K30, Avicel PH-101, sodium alginate and pregelatinized starch were the most appropriate excipients for the direct compression of drugs.

  13. Directional biases reveal utilization of arm's biomechanical properties for optimization of motor behavior.

    Goble, Jacob A; Zhang, Yanxin; Shimansky, Yury; Sharma, Siddharth; Dounskaia, Natalia V

    2007-09-01

    Strategies used by the CNS to optimize arm movements in terms of speed, accuracy, and resistance to fatigue remain largely unknown. A hypothesis is studied that the CNS exploits biomechanical properties of multijoint limbs to increase efficiency of movement control. To test this notion, a novel free-stroke drawing task was used that instructs subjects to make straight strokes in as many different directions as possible in the horizontal plane through rotations of the elbow and shoulder joints. Despite explicit instructions to distribute strokes uniformly, subjects showed biases to move in specific directions. These biases were associated with a tendency to perform movements that included active motion at one joint and largely passive motion at the other joint, revealing a tendency to minimize intervention of muscle torque for regulation of the effect of interaction torque. Other biomechanical factors, such as inertial resistance and kinematic manipulability, were unable to adequately account for these significant biases. Also, minimizations of jerk, muscle torque change, and sum of squared muscle torque were analyzed; however, these cost functions failed to explain the observed directional biases. Collectively, these results suggest that knowledge of biomechanical cost functions regarding interaction torque (IT) regulation is available to the control system. This knowledge may be used to evaluate potential movements and to select movement of "low cost." The preference to reduce active regulation of interaction torque suggests that, in addition to muscle energy, the criterion for movement cost may include neural activity required for movement control.

  14. Structural and mechanical properties of diamond-like carbon films deposited by direct current magnetron sputtering

    Broitman, E.; Hellgren, N.; Czigany, Zs.; Twesten, R.D.; Luning, J.; Petrov, I.; Hultman, L.; Holloway, B.C.

    2003-01-01

    The microstructure, morphology, and mechanical properties of diamond-like carbon (DLC) films deposited by direct current magnetron sputtering were investigated for microelectromechanical systems applications. Film properties were found to vary markedly with the ion energy (E ion ) and ion-to-carbon flux ratio (J ion /J C ). Cross-sectional high-resolution transmission electron microscopy revealed an amorphous microstructure. However, the presence of nanometer-sized domains at E ion ∼85 eV was detected. Film stresses, σ, which were compressive in all cases, ranged from 0.5 to 3.5 GPa and depended on the flux ratio as well as ion energy. The hardness (H), Young's moduli (ε), and elastic recovery (R) increased with E ion to maximum values of H=27 GPa, ε=250 GPa, and R=68% at E ion =85 eV and J ion /J C =4.4. However, near edge x-ray absorption fine structure and electron energy-loss spectrum analysis showed that the sp 2 /sp 3 content of the films does not change with E ion or J ion /J C . The measured change in mechanical properties without a corresponding change in sp 2 /sp 3 ratio is not consistent with any previously published models. We suggest that, in the ranges 5 eV ≤E ion ≤85 eV and 1.1 ≤J ion /J C ≤6.8, the presence of defective graphite formed by subplanted C and Ar atoms has the dominant influence on the mechanical properties of DLC films

  15. Biopolymer coated gold nanocrystals prepared using the green chemistry approach and their shape-dependent catalytic and surface-enhanced Raman scattering properties.

    Chou, Chih-Wei; Hsieh, Hui-Hsuan; Hseu, You-Cheng; Chen, Ko-Shao; Wang, Gou-Jen; Chang, Hsien-Chang; Pan, Yong-Li; Wei, Yi-Syuan; Chang, Ko Hsin; Harn, Yeu-Wei

    2013-07-21

    This study deals with the preparation of multi-shaped nanoscale gold crystals under synthetically simple, green, and efficient conditions using a seed-mediated growth approach in the presence of hyaluronic acid (HA). These highly biocompatible multi-shaped gold nanocrystals were examined to evaluate their catalytic and surface enhanced Raman scattering (SERS) properties. The results show that the size and shape of the nanocrystals are mainly correlated to the amount of seed, seed size, HA concentration, and reaction temperature. Gold seeds accelerate the reduction of the gold precursor to form gold nanocrystals using HA. The HA serves as a reducing agent and a growth template for the reduction of Au(III) and nanocrystal stabilization. The multi-shaped gold nanocrystals showed superior catalytic properties and higher SERS performance. The simple, green approach efficiently controls the nanocrystals and creates many opportunities for future applications.

  16. Concentric layered Hermite scatterers

    Astheimer, Jeffrey P.; Parker, Kevin J.

    2018-05-01

    The long wavelength limit of scattering from spheres has a rich history in optics, electromagnetics, and acoustics. Recently it was shown that a common integral kernel pertains to formulations of weak spherical scatterers in both acoustics and electromagnetic regimes. Furthermore, the relationship between backscattered amplitude and wavenumber k was shown to follow power laws higher than the Rayleigh scattering k2 power law, when the inhomogeneity had a material composition that conformed to a Gaussian weighted Hermite polynomial. Although this class of scatterers, called Hermite scatterers, are plausible, it may be simpler to manufacture scatterers with a core surrounded by one or more layers. In this case the inhomogeneous material property conforms to a piecewise continuous constant function. We demonstrate that the necessary and sufficient conditions for supra-Rayleigh scattering power laws in this case can be stated simply by considering moments of the inhomogeneous function and its spatial transform. This development opens an additional path for construction of, and use of scatterers with unique power law behavior.

  17. Direct Laser Interference Patterning: Tailoring of Contact Area for Frictional and Antibacterial Properties

    Andreas Rosenkranz

    2016-01-01

    Full Text Available Surface functionalization by topographic micro- and nano-structures in order to achieve unique properties, like super-hydrophobicity or ultrahigh light absorption, is a common strategy in nature. In this paper, direct laser interference patterning (DLIP is presented as a promising tool allowing for the generation of such surface patterns on technical surfaces in order to mimic these biological surfaces and effects. Friction optimization and antibacterial effects by DLIP are exemplarily described. Topographic surface patterns on the micro- and nano-scale demonstrated a significant reduction in the coefficient of friction and bacterial adhesion. It was shown that in both cases, the control of the contact area between surfaces or between surface and bacteria is of utmost importance.

  18. Up sector of minimal flavor violation: top quark properties and direct D meson CP violation

    Bai, Yang; Berger, Joshua; Hewett, JoAnne L.; Li, Ye

    2013-07-01

    Minimal Flavor Violation in the up-type quark sector leads to particularly interesting phenomenology due to the interplay of flavor physics in the charm sector and collider physics from flavor changing processes in the top sector. We study the most general operators that can affect top quark properties and D meson decays in this scenario, concentrating on two CP violating operators for detailed studies. The consequences of these effective operators on charm and top flavor changing processes are generically small, but can be enhanced if there exists a light flavor mediator that is a Standard Model gauge singlet scalar and transforms under the flavor symmetry group. This flavor mediator can satisfy the current experimental bounds with a mass as low as tens of GeV and explain observed D-meson direct CP violation. Additionally, the model predicts a non-trivial branching fraction for a top quark decay that would mimic a dijet resonance.

  19. MECHANICAL PROPERTIES OF THIN GDP SHELLS USED AS CRYOGENIC DIRECT DRIVE TARGETS AT OMEGA

    NIKROO, A.; CZECHOWICZ, D.; CHEN, K.C.; DICKEN, M.; MORRIS, C.; ANDREWS, R.; GREENWOOD, A.L; CASTILLO, E.

    2003-09-01

    OAK-B135 Thin glow discharge polymer (GDP) shells are currently used as the targets for cryogenic direct drive laser fusion experiments. These shells need to be filled with nearly 1000 atm of D 2 and cooled to cryogenic temperatures without failing due to buckling and bursting pressures they experience in this process. Therefore, the mechanical and permeation properties of these shells are of utmost importance in successful and rapid filling with D 2 . In this paper, they present an overview of buckle and burst pressures of several different types of GDP shells. These include those made using traditional GDP deposition parameters (standard GDP) using a high deposition pressure and using modified parameters (strong GDP) of low deposition pressure that leads to more robust shells

  20. In situ–Directed Growth of Organic Nanofibers and Nanoflakes: Electrical and Morphological Properties

    de Oliveira Hansen Roana

    2011-01-01

    Full Text Available Abstract Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes for electrical connection continues to be a significant hindrance toward their large-scale implementation. Here, we demonstrate in situ–directed growth of such organic nanostructures between pre-fabricated contacts, which are source–drain gold electrodes on a transistor platform (bottom-gate on silicon dioxide patterned by a combination of optical lithography and electron beam lithography. The dimensions of the gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties. The ability to control such nanofiber or nanoflake growth opens the possibility for large-scale optoelectronic device fabrication.

  1. Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity.

    Yusuf, Nur Kamilah; Lajis, Mohd Amri; Ahmad, Azlan

    2017-08-03

    Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (T s = 430, 480, and 530 °C) and holding times (t s = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at T s = 530 °C and t s = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices.

  2. Quasi-one-dimensional scattering in a discrete model

    Valiente, Manuel; Mølmer, Klaus

    2011-01-01

    We study quasi-one-dimensional scattering of one and two particles with short-range interactions on a discrete lattice model in two dimensions. One of the directions is tightly confined by an arbitrary trapping potential. We obtain the collisional properties of these systems both at finite and zero...

  3. Infrared laser scattering system for the plasma diagnostics

    Hiraki, Naoji; Kawasaki, Shoji; Muraoka, Katsunori

    1975-01-01

    As the results of the parametric studies of the double discharge TEA CO 2 laser, the required properties on the laser system for the scattering diagnostics of plasmas are shown to be realized with our CO 2 laser. The direction of the future improvements of the laser performance is also discussed. (auth.)

  4. Studies of the underlying-event properties and of hard double parton scattering with the ATLAS detector

    Kuprash, Oleg; The ATLAS collaboration

    2017-01-01

    A correct modelling of the underlying event in proton-proton collisions is important for the proper simulation of kinematic distributions of high-energy collisions. The ATLAS collaboration extended previous studies at 7 TeV with a leading track or jet or Z boson by a new study at 13 TeV, measuring the number and transverse-momentum sum of charged particles as a function of pseudorapidity and azimuthal angle in dependence of the reconstructed leading track. These measurements are sensitive to the underlying-event as well as the onset of hard emissions. The results are compared to predictions of several MC generators. + Inclusive four-jet events produced in proton--proton collisions at a center-of-mass energy of 7 TeV have been analyzed for the presence of hard double parton scattering collected with the ATLAS detector. The contribution of hard double parton scattering to the production of four-jet events has been extracted using an artificial neural network. The assumption was made that hard double parton scat...

  5. Experimental investigation on photothermal properties of nanofluids for direct absorption solar thermal energy systems

    He, Qinbo; Wang, Shuangfeng; Zeng, Shequan; Zheng, Zhaozhi

    2013-01-01

    Highlights: • The factors affecting the transmittance of Cu–H 2 O nanofluids were studied with UV–Vis–NIR spectrophotometer. • The optical properties of Cu–H 2 O nanofluids were studied through the theoretical model. • The Cu–H 2 O nanofluids can enhance the absorption ability for solar energy. - Abstract: In this article, Cu–H 2 O nanofluids were prepared through two-step method. The transmittance of nanofluids over solar spectrum (250–2500 nm) was measured by the UV–Vis–NIR spectrophotometer based on integrating sphere principle. The factors influencing transmittance of nanofluids, such as particle size, mass fraction and optical path were investigated. The extinction coefficients measured experimentally were compared with the theoretical calculation value. Meanwhile, the photothermal properties of nanofluids were also investigated. The experimental results show that the transmittance of Cu–H 2 O nanofluids is much less than that of deionized water, and decreases with increasing nanoparticle size, mass fraction and optical depth. The highest temperature of Cu–H 2 O nanofluids (0.1 wt.%) can increased up to 25.3% compared with deionized water. The good absorption ability of Cu–H 2 O nanofluids for solar energy indicates that it is suitable for direct absorption solar thermal energy systems

  6. Electron scattering studies by means of various nuclear models

    Essaniyazov, Sh.; Juraev, Sh.; Ismatov, E.I.

    2006-01-01

    Full text: Let us consider a general case of various interaction processes of electrons with nuclei. The study of the scattering o electrons of nuclei is the source of information on the structure of nuclei. At collision of fast electrons with nuclei, both elastic and inelastic scattering can be observed. Elastic scattering gives information on the sizes of nuclei, whereas the electrons inelastic scattering processes give important information on the dynamical properties of nuclei. In the first case, the characteristics of excited states, energy levels, their widths and others, and in the second case, momentum distribution of nucleons and other particles in nuclei are studied. Let us denote the momentum and the energy of the incident electron before and after the scattering as k and ε, and k' and ε', respectively. The angle between the vectors k and k' is denoted as θ. The scattering process is characterized by three parameters: k, k' and θ. However, it is convenient to introduce three other parameters instead of the indicated above. They are: energy ω ε - ε' and momentum q = k - k', transferred by electron at scattering, and the scattering angle θ. It is worth of mentioning the two reasons why the study of electron scattering is very effective tool to study the nuclear structure. First of all, the character of electron interaction with nucleus is a well-known electromagnetic interaction of electron with current and charge in nucleus. Secondly, this interaction is relatively weak (e 2 /ℎc) 2 = ω 2 is possible (since the photon mass is zero). In case of electrons, at fixed energy transfer ω various momentum transfer are possible. Therefore, at electron scattering study one can establish the dependence of the matrix elements of q, which are the Fourier-representations of the charge and current densities. Thus, it is possible to determine directly the spatial distribution of charge and current in nucleus. The inelastic scattering is accompanied by

  7. Pore structure and mechanical properties of directionally solidified porous aluminum alloys

    Komissarchuk Olga

    2014-01-01

    Full Text Available Porous aluminum alloys produced by the metal-gas eutectic method or GASAR process need to be performed under a certain pressure of hydrogen, and to carry over melt to a tailor-made apparatus that ensures directional solidification. Hydrogen is driven out of the melt, and then the quasi-cylindrical pores normal to the solidification front are usually formed. In the research, the effects of processing parameters (saturation pressure, solidification pressure, temperature, and holding time on the pore structure and porosity of porous aluminum alloys were analyzed. The mechanical properties of Al-Mg alloys were studied by the compressive tests, and the advantages of the porous structure were indicated. By using the GASAR method, pure aluminum, Al-3wt.%Mg, Al-6wt.%Mg and Al-35wt.%Mg alloys with oriented pores have been successfully produced under processing conditions of varying gas pressure, and the relationship between the final pore structure and the solidification pressure, as well as the influences of Mg quantity on the pore size, porosity and mechanical properties of Al-Mg alloy were investigated. The results show that a higher pressure of solidification tends to yield smaller pores in aluminum and its alloys. In the case of Al-Mg alloys, it was proved that with the increasing of Mg amount, the mechanical properties of the alloys sharply deteriorate. However, since Al-3%Mg and Al-6wt.%Mg alloys are ductile metals, their porous samples have greater compressive strength than that of the dense samples due to the existence of pores. It gives the opportunity to use them in industry at the same conditions as dense alloys with savings in weight and material consumption.

  8. Pp scattering at SIN

    Aprile-Giboni, E.; Cantale, G.; Hausammann, R.

    1983-01-01

    Using the PM1 polarized proton beam at SIN and a polarized target, the elastic pp scattering as well as the inelastic channel pp → π + d have been studied between 400 and 600 MeV. For the elastic reaction, a sufficient number of spin dependent parameters has been measured in order to do a direct reconstruction of the scattering matrix between 38 0 /sub cm/ and 90 0 /sub cm/. 10 references, 6 figures

  9. Spectrum of an electromagnetic light wave on scattering from an anisotropic semisoft boundary medium.

    Wang, Tao; Jiang, Zhenfei; Ji, Xiaoling; Zhao, Daomu

    2016-04-01

    Spectral shifts and spectral switches of a polychromatic electromagnetic light wave on scattering from an anisotropic semisoft boundary medium are discussed. It is shown that both the property of the incident field and the character of the scattering medium play roles in the change of the spectrum of the far-zone scattered field. It is also shown that the distribution of the far-zone scattered spectrum, including the magnitude of the spectral shift and the direction at which the spectral switch occurs, is rotationally nonsymmetric.

  10. Microstructures and mechanical properties of directionally solidified Ni-25%Si full lamellar in situ composites

    Zhang, Binggang; Li, Xiaopeng; Wang, Ting; Liu, Zheng

    2016-01-01

    Directional solidification experiments have been performed on Ni-25 at% Si alloy using electron beam floating zone method. A fully regular eutectic microstructures consisting of Ni, γ-Ni 31 Si 12 and β 1 -Ni 3 Si have been obtained. The influences of the directional solidification rate on the microstructures and properties of the full lamellar structures have been studied. The results show that the relationship between the mean interphase spacing (λ) and withdrawal rate (v) meets λ=29.9v −0.65 . The hardness increases with the increasing of growth rate (v) and decreasing of the interlamellar spacing (λ) which meets the relationship of H V =445.2v 0.14 and H V =910λ −0.21 . The maximum compressive strength, 2576 MPa, for DS samples is obtained by 10 mm/h. The average fracture toughness value found for 5 mm/h, 7 mm/h, 10 mm/h is 28.3 MPa m 1/2 , 29.1 MPa m 1/2 and 35.9 MPa m 1/2 , respectively. The crack bridging and crack deflection/interface debonding are the main toughening mechanism of Ni-25 at% Si with full lamellar structures.

  11. Characterization and gas sensing properties of CuO synthesized by DC directly applying voltage

    Klinbumrung, Arrak [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Titipun [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Somchai, E-mail: schthongtem@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-09-15

    Highlights: • CuO as a p-type semiconductor. • It was synthesized by directly applying voltage. • A promising material for ammonia detection. - Abstract: CuO microstructure was successfully synthesized by 50 A and 3.6 V DC directly applying voltage. Crystalline structure was characterized by X-ray diffraction (XRD), morphology by scanning and transmission electron microscopy (SEM, TEM). The sample of the 15 min processing time has an irregular shape with diameter about several hundreds of nanometer. Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy and photoluminescence (PL) were used to determine vibrational modes and optical properties of the as-synthesized samples: 529 and 585 cm{sup −1} vibrational modes, 3.95 eV band gap, and 402 nm emitting wavelength in violet region of CuO. X-ray photoelectron (XPS) spectroscopy was used to determine chemical composition, Cu(II)O, of the metal oxide surface. Gas sensing performance exposing to NH{sub 3} mixed with air at various working temperatures and NH{sub 3} concentrations of the as-synthesized CuO has the best response at the optimal working temperature of 250 °C: sensitivity of 56.6% exposed to 5275 ppm NH{sub 3}.

  12. Characterization and gas sensing properties of CuO synthesized by DC directly applying voltage

    Klinbumrung, Arrak; Thongtem, Titipun; Thongtem, Somchai

    2014-01-01

    Highlights: • CuO as a p-type semiconductor. • It was synthesized by directly applying voltage. • A promising material for ammonia detection. - Abstract: CuO microstructure was successfully synthesized by 50 A and 3.6 V DC directly applying voltage. Crystalline structure was characterized by X-ray diffraction (XRD), morphology by scanning and transmission electron microscopy (SEM, TEM). The sample of the 15 min processing time has an irregular shape with diameter about several hundreds of nanometer. Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy and photoluminescence (PL) were used to determine vibrational modes and optical properties of the as-synthesized samples: 529 and 585 cm −1 vibrational modes, 3.95 eV band gap, and 402 nm emitting wavelength in violet region of CuO. X-ray photoelectron (XPS) spectroscopy was used to determine chemical composition, Cu(II)O, of the metal oxide surface. Gas sensing performance exposing to NH 3 mixed with air at various working temperatures and NH 3 concentrations of the as-synthesized CuO has the best response at the optimal working temperature of 250 °C: sensitivity of 56.6% exposed to 5275 ppm NH 3

  13. Dynamic light scattering and X-ray photoelectron spectroscopy characterization of PEGylated polymer nanocarriers: internal structure and surface properties.

    Celasco, Edvige; Valente, Ilaria; Marchisio, Daniele L; Barresi, Antonello A

    2014-07-22

    In this work, nanospheres and nanocapsules are precipitated in confined impinging jet mixers through solvent displacement and characterized. Acetone and water are used as the solvent and antisolvent, respectively, together with polymethoxypolyethylene glycol cyanoacrylate-co-hexadecylcyanoacrylate and Miglyol as the copolymer and oil, respectively. Characterization is performed with dynamic light scattering, with electrophoretic measurements, and for the first time with X-ray photoelectron spectroscopy. Results show that the presence of polyethylene glycol chains seems to be more pronounced on the surface of nanospheres than on that of nanocapsules. The thickness of the copolymer layer in nanocapsules ranges from 1 to 10 nm, depending on the value of the oil:copolymer mass ratio. Fast dilution is confirmed to have a positive effect in suppressing aggregation but can induce further copolymer precipitation.

  14. Magnetic properties of exchange biased and of unbiased oxide/permalloy thin layers: a ferromagnetic resonance and Brillouin scattering study

    Zighem, F; Roussigne, Y; Cherif, S-M; Moch, P [Laboratoire des Proprietes Mecaniques et Thermodynamiques des Materiaux, CNRS UPR 9001, Universite Paris Nord, 93430 Villetaneuse (France); Ben Youssef, J [Laboratoire de Magnetisme de Bretagne, CNRS, Universite de Bretagne Occidentale, 29285 Brest (France); Paumier, F, E-mail: fatih.zighem@cea.f [Institut Pprime, CNRS UPR 3346, Universite de Poitiers, ENSMA, 86962 Futuroscope (France)

    2010-10-13

    Microstrip ferromagnetic resonance and Brillouin scattering are used to provide a comparative determination of the magnetic parameters of thin permalloy layers interfaced with a non-magnetic (Al{sub 2}O{sub 3}) or with an antiferromagnetic oxide (NiO). It results from our microstructural study that no preferential texture is favoured in the observed polycrystalline sublayers. It is shown that the perpendicular anisotropy can be monitored using an interfacial surface energy term which is practically independent of the nature of the interface. In the interval of thicknesses investigated (5-25 nm) the saturation magnetization does not significantly differ from the reported one in bulk permalloy. In-plane uniaxial anisotropy and exchange bias anisotropy are also derived from the study of the dynamic magnetic excitations and compared with our independent evaluations using conventional magnetometry.

  15. Sum rules and other properties involving resonance projection operators. [for optical potential description of electron scattering from atoms and ions

    Berk, A.; Temkin, A.

    1985-01-01

    A sum rule is derived for the auxiliary eigenvalues of an equation whose eigenspectrum pertains to projection operators which describe electron scattering from multielectron atoms and ions. The sum rule's right-hand side depends on an integral involving the target system eigenfunctions. The sum rule is checked for several approximations of the two-electron target. It is shown that target functions which have a unit eigenvalue in their auxiliary eigenspectrum do not give rise to well-defined projection operators except through a limiting process. For Hylleraas target approximations, the auxiliary equations are shown to contain an infinite spectrum. However, using a Rayleigh-Ritz variational principle, it is shown that a comparatively simple aproximation can exhaust the sum rule to better than five significant figures. The auxiliary Hylleraas equation is greatly simplified by conversion to a square root equation containing the same eigenfunction spectrum and from which the required eigenvalues are trivially recovered by squaring.

  16. Tensile properties and microstructure of direct metal laser-sintered TI6AL4V (ELI alloy

    Moletsane, M. G.

    2016-11-01

    Full Text Available Direct metal laser sintering (DMLS is an additive manufacturing technology used to melt metal powder by high laser power to produce customised parts, light-weight structures, or other complex objects. During DMLS, powder is melted and solidified track-by-track and layer-by-layer; thus, building direction can influence the mechanical properties of DMLS parts. The mechanical properties and microstructure of material produced by DMLS can depend on the powder properties, process parameters, scanning strategy, and building geometry. In this study, the microstructure, tensile properties, and porosity of DMLS Ti6Al4V (ELI horizontal samples were analysed. Defect analysis by CT scans in pre-strained samples was used to detect the crack formation mechanism during tensile testing of as-built and heat-treated samples. The mechanical properties of the samples before and after stress relieving are discussed.

  17. Hydraulic Properties of Closely Spaced Dipping Open Fractures Intersecting a Fluid-Filled Borehole Derived From Tube Wave Generation and Scattering

    Minato, Shohei; Ghose, Ranajit; Tsuji, Takeshi; Ikeda, Michiharu; Onishi, Kozo

    2017-10-01

    Fluid-filled fractures and fissures often determine the pathways and volume of fluid movement. They are critically important in crustal seismology and in the exploration of geothermal and hydrocarbon reservoirs. We introduce a model for tube wave scattering and generation at dipping, parallel-wall fractures intersecting a fluid-filled borehole. A new equation reveals the interaction of tube wavefield with multiple, closely spaced fractures, showing that the fracture dip significantly affects the tube waves. Numerical modeling demonstrates the possibility of imaging these fractures using a focusing analysis. The focused traces correspond well with the known fracture density, aperture, and dip angles. Testing the method on a VSP data set obtained at a fault-damaged zone in the Median Tectonic Line, Japan, presents evidences of tube waves being generated and scattered at open fractures and thin cataclasite layers. This finding leads to a new possibility for imaging, characterizing, and monitoring in situ hydraulic properties of dipping fractures using the tube wavefield.

  18. General Properties of Scattering Matrix for Mode Conversion Process between B Waves and External EM Waves and Their Consequence to Experiments

    Maekawa, T.; Tanaka, H.; Uchida, M.; Igami, H.

    2003-01-01

    General properties of scattering matrix, which governs the mode conversion process between electron Bernstein (B) waves and external electromagnetic (EM) waves in the presence of steep density gradient, are theoretically analyzed. Based on the analysis, polarization adjustment of incident EM waves for optimal mode conversion to B waves is possible and effective for a range of density gradient near the upper hybrid resonance, which are not covered by the previously proposed schemes of perpendicular injection of X mode and oblique injection of O mode. Furthermore, the analysis shows that the polarization of the externally emitted EM waves from B waves is uniquely related to the optimized polarization of incident EM waves for B wave heating and that the mode conversion rate is the same for the both processes of emission and the injection with the optimized polarization

  19. Thomson Scattering

    Donne, A. J. H.

    1994-01-01

    Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wave vector is much larger than the plasma Debye length, the total scattered power is

  20. Neutron scattering study of dilute supercritical solutions

    Cochran, H.D.; Wignall, G.D.; Shah, V.M.; Londono, J.D.; Bienkowski, P.R.

    1994-01-01

    Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope 36 Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast

  1. Modeling C-band single scattering properties of hydrometeors using discrete-dipole approximation and T-matrix method

    Tyynelae, Jani; Nousiainen, Timo; Goeke, Sabine; Muinonen, Karri

    2009-01-01

    We study the applicability of the discrete-dipole approximation by modeling centimeter (C-band) radar echoes for hydrometeors, and compare the results to exact theories. We use ice and water particles of various shapes with varying water-content to investigate how the backscattering, extinction, and absorption cross sections change as a function of particle radius. We also compute radar parameters, such as the differential reflectivity, the linear depolarization ratio, and the copolarized correlation coefficient. We find that using discrete-dipole approximation (DDA) to model pure ice and pure water particles at the C-band, is a lot more accurate than particles containing both ice and water. For coated particles, a large grid-size is recommended so that the coating is modeled adequately. We also find that the absorption cross section is significantly less accurate than the scattering and backscattering cross sections. The accuracy of DDA can be increased by increasing the number of dipoles, but also by using the filtered coupled dipole-option for the polarizability. This halved the relative errors in cross sections.

  2. A study of the properties of tablets made of directly compressible maltose.

    Muzíková, J; Balhárková, J

    2008-01-01

    The paper deals with the study of the strength and disintegration time of tablets made of directly compressible maltose Advantose 100. It studies the differences of the effects of two types of lubricants, magnesium stearate and sodium stearylfumarate, on the above-mentioned properties, and it also tests the mixtures of the substance with microcrystalline cellulose Vivapur 102 in a ratio of 1:1 and with ascorbic and acetylsalicylic acids. The compacts are obtained by using three compression forces, excepting mixtures with active ingredients, where one compression force is used. In the compression forces of 6 and 8 kN, no statistically significant difference was found in the intervention of the lubricants into the strength of the compacts made of Advantose 100, only in the compression force of 10 kN Pruv decreased the strength more than stearate. The mixture of Advantose 100 and Vivapur 102 yielded the strongest tablets, an addition of Pruv to it decreased the strength of compacts more than stearate. The periods of disintegration time of Advantose compacts as well as those of the mixture of dry binders were longer with an addition of Pruv. The compacts with acetylsalicylic acid possessed higher strength and a longer period of disintegration than those with ascorbic acid. There was no statistically significant difference within the type of the lubricant employed, both in the case of Advantose 100 and its mixture with Vivapur 102, between the values of strength of the compacts with acetylsalicylic acid.

  3. Monolayer-directed Assembly and Magnetic Properties of FePt Nanoparticles on Patterned Aluminum Oxide

    Guus Rijnders

    2010-03-01

    Full Text Available FePt nanoparticles (NPs were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(onates were used as an adsorbate to form self-assembled monolayers (SAMs on alumina to direct the assembly of NPs onto the surface. The Al2O3 substrates were functionalized with aminobutylphosphonic acid (ABP or phosphonoundecanoic acid (PNDA SAMs or with poly(ethyleneimine (PEI as a reference. FePt NPs assembled on all of these monolayers, but much less on unmodified Al2O3, which shows that ligand exchange at the NPs is the most likely mechanism of attachment. Proper modification of the Al2O3 surface and controlling the immersion time of the modified Al2O3 substrates into the FePt NP solution resulted in FePt NPs assembly with controlled NP density. Alumina substrates were patterned by microcontact printing using aminobutylphosphonic acid as the ink, allowing local NP assembly. Thermal annealing under reducing conditions (96%N2/4%H2 led to a phase change of the FePt NPs from the disordered FCC phase to the ordered FCT phase. This resulted in ferromagnetic behavior at room temperature. Such a process can potentially be applied in the fabrication of spintronic devices.

  4. Ecosystem properties self-organize in response to a directional fog-vegetation interaction.

    Stanton, Daniel E; Armesto, Juan J; Hedin, Lars O

    2014-05-01

    Feedbacks between vegetation and resource inputs can lead to the local, self-organization of ecosystem properties. In particular, feedbacks in response to directional resources (e.g., coastal fog, slope runoff) can create complex spatial patterns, such as vegetation banding. Although similar feedbacks are thought to be involved in the development of ecosystems, clear empirical examples are rare. We created a simple model of a fog-influenced, temperate rainforest in central Chile, which allows the comparison of natural banding patterns to simulations of various putative mechanisms. We show that only feedbacks between plants and fog were able to replicate the characteristic distributions of vegetation, soil water, and soil nutrients observed in field transects. Other processes, such as rainfall, were unable to match these diagnostic distributions. Furthermore, fog interception by windward trees leads to increased downwind mortality, leading to progressive extinction of the leeward edge. This pattern of ecosystem development and decay through self-organized processes illustrates, on a relatively small spatial and temporal scale, the patterns predicted for ecosystem evolution.

  5. Molecular Weight and Structural Properties of Biodegradable PLA Synthesized with Different Catalysts by Direct Melt Polycondensation

    Hyung Woo Lee

    2015-09-01

    Full Text Available Production of biodegradable polylactic acid (PLA from biomassbased lactic acid is widely studied for substituting petro-based plastics or polymers. This study investigated PLA production from commercial lactic acid in a batch reactor by applying a direct melt polycondensation method with two kinds of catalyst, γ-aluminium(III oxide (γ-Al2O3 or zinc oxide (ZnO, in reduced pressure. The molecular weight of the synthesized PLA was determined by capillary viscometry and its structural properties were analyzed by functional group analysis using FT-IR. The yields of polymer production with respect to the theoretical conversion were 47% for γ-Al2O3 and 35% for ZnO. However, the PLA from ZnO had a higher molecular weight (150,600 g/mol than that from γ-Al2O3 (81,400 g/mol. The IR spectra of the synthesized PLA from both catalysts using polycondensation show the same behavior of absorption peaks at wave numbers from 4,500 cm-1 to 500 cm-1, whereas the PLA produced by two other polymerization methods – polycondensation and ring opening polymerization –showed a significant difference in % transmittance intensity pattern as well as peak area absorption at a wave number of 3,500 cm-1 as –OH vibration peak and at 1,750 cm-1 as –C=O carbonyl vibrational peak.

  6. Synthesis of Ag nanobars in the presence of single-crystal seeds and a bromide compound, and their surface-enhanced Raman scattering (SERS) properties.

    Zhang, Qiang; Moran, Christine H; Xia, Xiaohu; Rycenga, Matthew; Li, Naixu; Xia, Younan

    2012-06-19

    This Article describes the synthesis of Ag nanobars with different aspect ratios using a seed-mediated method and evaluation of their use for surface-enhanced Raman scattering (SERS). The formation of Ag nanobars was found to critically depend on the introduction of a bromide compound into the reaction system, with ionic salts being more effective than covalent molecules. We examined single-crystal seeds with both spherical and cubic shapes and found that Ag nanobars grown from spherical seeds had much higher aspect ratios than those grown from cubic seeds. The typical product of a synthesis contained nanocrystals with three different morphologies: nanocubes, nanobars with a square cross section, and nanobars with a rectangular cross section. Their formation can be attributed to the difference in growth rates along the three orthogonal directions. The SERS enhancement factor of the Ag nanobar was found to depend on its aspect ratio, its orientation relative to the laser polarization, and the wavelength of excitation.

  7. Direct measurements of surface scattering in Si nanosheets using a microscale phonon spectrometer: implications for Casimir-limit predicted by Ziman theory.

    Hertzberg, Jared B; Aksit, Mahmut; Otelaja, Obafemi O; Stewart, Derek A; Robinson, Richard D

    2014-02-12

    Thermal transport in nanostructures is strongly affected by phonon-surface interactions, which are expected to depend on the phonon's wavelength and the surface roughness. Here we fabricate silicon nanosheets, measure their surface roughness (∼ 1 nm) using atomic force microscopy (AFM), and assess the phonon scattering rate in the sheets with a novel technique: a microscale phonon spectrometer. The spectrometer employs superconducting tunnel junctions (STJs) to produce and detect controllable nonthermal distributions of phonons from ∼ 90 to ∼ 870 GHz. This technique offers spectral resolution nearly 10 times better than a thermal conductance measurement. We compare measured phonon transmission rates to rates predicted by a Monte Carlo model of phonon trajectories, assuming that these trajectories are dominated by phonon-surface interactions and using the Ziman theory to predict phonon-surface scattering rates based on surface topology. Whereas theory predicts a diffuse surface scattering probability of less than 40%, our measurements are consistent with a 100% probability. Our nanosheets therefore exhibit the so-called "Casimir limit" at a much lower frequency than expected if the phonon scattering rates follow the Ziman theory for a 1 nm surface roughness. Such a result holds implications for thermal management in nanoscale electronics and the design of nanostructured thermoelectrics.

  8. The Low-Temperature Inflection Observed in Neutron Scattering Measurements of Proteins Is Due to Methyl Rotation : Direct Evidence Using Isotope Labeling and Molecular Dynamics Simulations

    Wood, Kathleen; Tobias, Douglas J.; Kessler, Brigitte; Gabel, Frank; Oesterhelt, Dieter; Mulder, Frans A. A.; Zaccai, Giuseppe; Weik, Martin

    2010-01-01

    There is increasing interest in the contribution of methyl groups to the overall dynamics measured by neutron scattering experiments of proteins. In particular an inflection observed in atomic mean square displacements measured as a function of temperature on high resolution spectrometers (similar

  9. Column-integrated aerosol optical properties and direct radiative forcing over the urban-industrial megacity Nanjing in the Yangtze River Delta, China.

    Kang, Na; Kumar, K Raghavendra; Yu, Xingna; Yin, Yan

    2016-09-01

    Aerosol optical properties were measured and analyzed through the ground-based remote sensing Aerosol Robotic Network (AERONET) over an urban-industrial site, Nanjing (32.21° N, 118.72° E, and 62 m above sea level), in the Yangtze River Delta, China, during September 2007-August 2008. The annual averaged values of aerosol optical depth (AOD500) and the Ångström exponent (AE440-870) were measured to be 0.94 ± 0.52 and 1.10 ± 0.21, respectively. The seasonal averaged values of AOD500 (AE440-870) were noticed to be high in summer (autumn) and low in autumn (spring). The characterization of aerosol types showed the dominance of mixed type followed by the biomass burning and urban-industrial type of aerosol at Nanjing. Subsequently, the curvature (a 2) obtained from the second-order polynomial fit and the second derivative of AE (α') were also analyzed to understand the dominant aerosol type. The single scattering albedo at 440 nm (SSA440) varied from 0.88 to 0.93 with relatively lower (higher) values during the summer (spring), suggesting an increase in black carbon and mineral dust (desert dust) aerosols of absorbing (scattering) nature. The averaged monthly and seasonal evolutions of shortwave (0.3-4.0 μm) direct aerosol radiative forcing (DARF) values were computed from the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model both at the top of atmosphere (TOA) and bottom of atmosphere (SUR) during the study period. Further, the aerosol forcing efficiency (AFE) and the corresponding atmospheric heating rates (AHR) were also estimated from the forcing within the atmosphere (ATM). The derived DARF values, therefore, produced a warming effect within the atmosphere due to strong absorption of solar radiation.

  10. Microhydration effect on structural, energetic and light scattering properties of first branched interstellar molecule ( i-PrCN)

    Chakraborty, Sumana; Routh, Swati; Krishnappa, Madhu

    2015-01-01

    In this work, we have focused on microsolvation of isopropyl cyanide (i-PrCN) as isopropyl cyanide has been recently detected in interstellar space and is of great importance from the astrochemical and bio-chemical point of view for its branching carbon chains. Such branches are needed for many molecules crucial to life, such as the amino acids that build proteins. The phenomenon of the formation of hydrogen bond affects structure, energetic and electric properties of microhydrated isopropyl ...

  11. Progress in three-particle scattering from LQCD

    Briceño Raúl A.

    2017-01-01

    Full Text Available We present the status of our formalism for extracting three-particle scattering observables from lattice QCD (LQCD. The method relies on relating the discrete finitevolume energy spectrum of a quantum field theory with its scattering amplitudes. As the finite-volume spectrum can be directly determined in LQCD, this provides a method for determining scattering observables, and associated resonance properties, from the underlying theory. In a pair of papers published over the last two years, two of us have extended this approach to apply to relativistic three-particle scattering states. In this talk we summarize recent progress in checking and further extending this result. We describe an extension of the formalism to include systems in which two-to-three transitions can occur. We then present a check of the previously published formalism, in which we reproduce the known finite-volume energy shift of a three-particle bound state.

  12. Inversion assuming weak scattering

    Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus

    2013-01-01

    due to the complex nature of the field. A method based on linear inversion is employed to infer information about the statistical properties of the scattering field from the obtained cross-spectral matrix. A synthetic example based on an active high-frequency sonar demonstrates that the proposed...

  13. Scattering theory

    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

  14. Inelastic scattering and deformation parameters

    Ford, J.L.C. Jr.

    1978-01-01

    In recent years there has been extensive study of nuclear shape parameters by electron scattering, μ meson atomic transitions, Coulomb excitation and direct nuclear inelastic scattering. Inelastic scattering of strongly absorbed particles, e.g., alpha-particles and heavy ions, at energies below and above the Coulomb barrier probe the charge and mass distributions within the nucleus. This paper summarizes measurements in this field performed at Oak Ridge National Laboratory

  15. Laser bistatic two-dimensional scattering imaging simulation of lambert cone

    Gong, Yanjun; Zhu, Chongyue; Wang, Mingjun; Gong, Lei

    2015-11-01

    This paper deals with the laser bistatic two-dimensional scattering imaging simulation of lambert cone. Two-dimensional imaging is called as planar imaging. It can reflect the shape of the target and material properties. Two-dimensional imaging has important significance for target recognition. The expression of bistatic laser scattering intensity of lambert cone is obtained based on laser radar eauqtion. The scattering intensity of a micro-element on the target could be obtained. The intensity is related to local angle of incidence, local angle of scattering and the infinitesimal area on the cone. According to the incident direction of laser, scattering direction and normal of infinitesimal area, the local incidence angle and scattering angle can be calculated. Through surface integration and the introduction of the rectangular function, we can get the intensity of imaging unit on the imaging surface, and then get Lambert cone bistatic laser two-dimensional scattering imaging simulation model. We analyze the effect of distinguishability, incident direction, observed direction and target size on the imaging. From the results, we can see that the scattering imaging simulation results of the lambert cone bistatic laser is correct.

  16. Light scattering reviews 9 light scattering and radiative transfer

    Kokhanovsky, Alexander A

    2014-01-01

    This book details modern methods of the radiative transfer theory. It presents recent advances in light scattering (measurements and theory) and highlights the newest developments in remote sensing of aerosol and cloud properties.

  17. Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

    Pinto, C.; Galdámez, A.; Barahona, P.; Moris, S.; Peña, O.

    2018-06-01

    Selenospinels, CuCr2-xMxSe4 (M = Zr and Sn), were synthesized via conventional solid-state reactions. The crystal structure of CuCr1.5Sn0.5Se4, CuCr1.7Sn0.3Se4, CuCr1.5Zr0.5Se4, and CuCr1.8Zr0.2Se4 were determined using single-crystal X-ray diffraction. All the phases crystallized in a cubic spinel-type structure. The chemical compositions of the single-crystals were examined using energy-dispersive X-ray analysis (EDS). Powder X-ray diffraction patterns of CuCr1.3Sn0.7Se4 and CuCr1.7Sn0.3Se4 were consistent with phases belonging to the Fd 3 bar m Space group. An analysis of the vibrational properties on the single-crystals was performed using Raman scattering measurements. The magnetic properties showed a spin glass behavior with increasing Sn content and ferromagnetic order for CuCr1.7Sn0.3Se4.

  18. MAGNETIC NEUTRON SCATTERING

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  19. Direct observation of electronic and nuclear ground state splitting in external magnetic field by inelastic neutron scattering on oxidized ferrocene and ferrocene containing polymers

    Appel, Markus; Frick, Bernhard; Elbert, Johannes; Gallei, Markus; Stühn, Bernd

    2015-01-01

    The quantum mechanical splitting of states by interaction of a magnetic moment with an external magnetic field is well known, e.g., as Zeeman effect in optical transitions, and is also often seen in magnetic neutron scattering. We report excitations observed in inelastic neutron spectroscopy on the redox-responsive polymer poly(vinylferrocene). They are interpreted as splitting of the electronic ground state in the organometallic ferrocene units attached to the polymer chain where a magnetic moment is created by oxidation. In a second experiment using high resolution neutron backscattering spectroscopy we observe the hyperfine splitting, i.e., interaction of nuclear magnetic moments with external magnetic fields leading to sub-μeV excitations observable in incoherent neutron spin-flip scattering on hydrogen and vanadium nuclei.

  20. Critical scattering

    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

  1. Spatial, spectral and statistical properties of the electrostatic fluctuations and measurements of the scattering of the beam in a strongly turbulent plasma

    McFarland, Michael Duane

    The purpose of this investigation is to measure the spatial, spectral and statistical properties of the high (/omega/ ~/ ω pe) and low (/omega/ ~/ ωpi) frequency electrostatic fluctuations in an unmagnetized, statistically stable, beam-driven, strongly turbulent plasma and compare the results to theoretical predictions. In addition the scattering of the electron beam in both angle and energy is measured and compared to theory. This study is motivated by the recent advances in statistical theories of strong Langmuir turbulence and the glaring lack of confirmatory experimental data. With the advent of modern computers and electronics, enormous data sets are now routinely digitize and subjected to sophisticated statistical and spectral analysis. These methods, along with traditional procedures and an innovative technique known as a 'conditional trigger', are used to extract ensemble averages from the turbulent system for comparison with the theoretical models. It is found that the high-frequency fluctuations consist of low-level wave activity /langle W/rangle/ ~/ 10-2 - 103 punctuated by semi-periodic, intense, spiky field events /langle W/rangle/ ~/ 1, where /langle W/rangle is the normalized intensity. The low- level wave activity has a spectral spread Δ k/k/ ~/ /Delta/omega//omega/ ~ 30%, dispersion relation v beam/ ~/ /omega/k, and correlation length lc/ /approx/ 3λES, where λES is the electrostatic wavelength, and shows evidence of low-intensity parametric decay products. The intense field events, on the other hand, show little correlation for l/ >/ λES, have a full-width-at-half-maximum of 1 f/ /n2/ /propto/ β where β ~/ 1.3 for the experiment and is predicted to be β ~/ 1.98 by the model. The scattering of the electron beam in angle for a typical wave intensity level /langle W/rangle/ ~/ 0.04 is Θ ~/ 3o, and in energy is Δ U/ ~/ 25 eV for a 400 eV beam. The scattering of the beam in both angle and energy is found to agree well with theory.

  2. Light scattering by small particles

    Hulst, H C van de

    1981-01-01

    ""A must for researchers using the techniques of light scattering."" ? S. C. Snowdon, Journal of the Franklin InstituteThe measurement of light scattering of independent, homogeneous particles has many useful applications in physical chemistry, meteorology and astronomy. There is, however, a sizeable gap between the abstract formulae related to electromagnetic-wave-scattering phenomena, and the computation of reliable figures and curves. Dr. van de Hulst's book enables researchers to bridge that gap. The product of twelve years of work, it is an exhaustive study of light-scattering properties

  3. Bibliography for thermal neutron scattering

    Sakamoto, M.; Chihara, J.; Nakahara, Y.; Kadotani, H.; Sekiya, T.

    1976-12-01

    It contains bibliographical references to measurements, calculations, reviews and basic studies on thermal neutron scatterings and dynamical properties of condensed matter. About 2,700 documents up to the end of 1975 are covered. (auth.)

  4. Modeling of absorption and scattering properties of core -shell nanoparticles for application as nanoantenna in optical domain

    Devi, Jutika; Datta, Pranayee; Saikia, Rashmi

    2016-01-01

    The present paper describes the study of core-shell nanoparticles for application as nanoantenna in the optical domain. To obtain the absorption and extinction efficiencies as well as the angular distribution of the far field radiation pattern and the resonance wavelengths for these metal-dielectric, dielectric-metal and metal-metal core-shell nanoparticles in optical domain, we have used Finite Element Method based COMSOL Multiphysics Software and Mie Theory. From the comparative study of the extinction efficiencies of core-shell nanoparticles of different materials, it is found that for silica - gold core - shell nanoparticles, the resonant wavelength is greater than that of the gold - silver, silver-gold and gold-silica core - shell nanoparticles and also the radiation pattern of the silica-gold core-shell nanoparticle is the most suitable one from the point of view of directivity. The dielectric functions of the core and shell material as well as of the embedded matrix are extremely important and plays a very major role to tune the directivity and resonance wavelength. Such highly controllable parameters of the dielectric - metal core - shell nanoparticles make them suitable for efficient coupling of optical radiation into nanoscale structures for a broad range of applications in the field of communications. (paper)

  5. Modeling of absorption and scattering properties of core -shell nanoparticles for application as nanoantenna in optical domain

    Devi, Jutika; Saikia, Rashmi; Datta, Pranayee

    2016-10-01

    The present paper describes the study of core-shell nanoparticles for application as nanoantenna in the optical domain. To obtain the absorption and extinction efficiencies as well as the angular distribution of the far field radiation pattern and the resonance wavelengths for these metal-dielectric, dielectric-metal and metal-metal core-shell nanoparticles in optical domain, we have used Finite Element Method based COMSOL Multiphysics Software and Mie Theory. From the comparative study of the extinction efficiencies of core-shell nanoparticles of different materials, it is found that for silica - gold core - shell nanoparticles, the resonant wavelength is greater than that of the gold - silver, silver-gold and gold-silica core - shell nanoparticles and also the radiation pattern of the silica-gold core-shell nanoparticle is the most suitable one from the point of view of directivity. The dielectric functions of the core and shell material as well as of the embedded matrix are extremely important and plays a very major role to tune the directivity and resonance wavelength. Such highly controllable parameters of the dielectric - metal core - shell nanoparticles make them suitable for efficient coupling of optical radiation into nanoscale structures for a broad range of applications in the field of communications.

  6. Role of direct covalent bonding in enhanced heat dissipation property of flexible graphene oxide–carbon nanotube hybrid film

    Hwang, Yongseon; Kim, Myeongjin; Kim, Jooheon

    2013-01-01

    The thermal conductivity of graphene oxide/multiwalled carbon nanotube (GO/MWCNT) hybrid films with and without covalent bonding is examined in this study. To fabricate chemically bonded GO/MWCNT hybrid films, chlorinated GO and amino-functionalized MWCNTs are bonded covalently. The mixtures of surface modified GO and MWCNT were filtered and then subjected to hot pressing to fabricate stacked films. Examination of these chemically bonded hybrid films reveal that chlorine-doped GO exhibits enhanced electrical properties because it creates hole charge carriers by attracting the electrons in GO towards chlorine. Enhanced electrical conductivity and low sheet resistance are observed also with increasing MWCNT loadings. On comparing the through-plane thermal properties, the chemically bonded hybrid films were found to exhibit higher thermal conductivity than do the physically bonded hybrid films because of the synergetic interaction of functional groups in GO and MWCNTs in the former films. However, excess addition of MWCNTs to the films leads to an increasing phonon scattering density and a decreased thermal conductivity. - Highlights: • Graphene oxide/carbon nanotube (GO/CNT) films are bonded covalently. • GO/CNT hybrid films are prepared through filtering and hot-pressing method. • Chemically bonded hybrid films exhibit enhanced electrical and thermal properties. • Enhanced thermal conductivity is explained according to increasing CNT contents

  7. Direct laboratory observation of fluid distribution and its influence on acoustic properties of patchy saturated rocks

    Lebedev, M.; Clennell, B.; Pervukhina, M.; Shulakova, V.; Mueller, T.; Gurevich, B.

    2009-04-01

    Porous rocks in hydrocarbon reservoirs are often saturated with a mixture of two or more fluids. Interpretation of exploration seismograms requires understanding of the relationship between distribution of the fluids patches and acoustic properties of rocks. The sizes of patches as well as their distribution affect significantly the seismic response. If the size of the fluid patch is smaller than the diffusion wavelength then pressure equilibration is achieved and the bulk modulus of the rock saturated with a mixture is defined by the Gassmann equations (Gassmann, 1951) with the saturation-weighted average of the fluid bulk modulus given by Wood's law (Wood, 1955, Mavko et al., 1998). If the fluid patch size is much larger than the diffusion wavelength then there is no pressure communication between different patches. In this case, fluid-flow effects can be neglected and the overall rock may be considered equivalent to an elastic composite material consisting of homogeneous parts whose properties are given by Gassmann theory with Hill's equation for the bulk modulus (Hill, 1963, Mavko et al., 1998). At intermediate values of fluid saturation the velocity-saturation relationship is significantly affected by the fluid patch distribution. In order to get an improved understanding of factors influencing the patch distribution and the resulting seismic wave response we performed simultaneous measurements of P-wave velocities and rock sample CT imaging. The CT imaging allows us to map the fluid distribution inside rock sample during saturation (water imbibition). We compare the experimental results with theoretical predictions. In this paper we will present results of simultaneous measurements of longitudinal wave velocities and imaging mapping of fluid distribution inside rock sample during sample saturation. We will report results of two kinds of experiments: "dynamic" and "quasi static" saturation. In both experiments Casino Cores Otway Basin sandstone, Australia core

  8. Effect of fiber directionality on the static and dynamic mechanical properties of 3D SiCf/SiC composites

    Hou, Zhenhua; Luo, Ruiying; Yang, Wei; Xu, Huaizhe; Han, Tao

    2016-01-01

    The static and dynamic mechanical properties of three-dimensional (3D) 4-directional and 3D 5-directional braided SiC f /SiC composites fabricated by polymer infiltration and pyrolysis (PIP) were investigated using static and dynamic bending tests, as well as microstructural characterization. X-ray diffraction revealed that polycarbosilane was converted into a matrix of crystalline β-SiC after PIP cycling. Test results indicated that the density, flexural strength, elastic modulus, fracture toughness, and storage modulus of 3D 5-directional SiC f /SiC composites were superior to those of 3D 4-directional braided SiC f /SiC composites; the former also showed a smaller internal friction than the latter. Results from Weibull statistical analysis indicated that the scale parameter σ 0 (736.9 MPa) and Weibull modulus m (21.7) of the 3D 5-directional specimen were higher than those of 3D 4-directional braided SiC f /SiC composites (629.6 MPa, 14.7). Both 3D braided composites demonstrated good toughness and avoided catastrophic brittle fractures under loading because of the effective crack energy dissipating mechanisms of crack deflection, interface debonding, and fiber pull-out. The internal friction and storage modulus of the 3D braided composites were sensitive to temperature. The cross angle of fiber placement in the preform and the direction of the applied force, as well as the pre-crack propagation remarkably influenced the static mechanical properties and failure behavior of the 3D braided SiC f /SiC composites. The dynamic mechanical properties of the 3D braided composites, including internal friction and storage modulus, were also considerably affected by fiber directionality in their preforms.

  9. Proton nuclear scattering radiography

    Saudinos, J.

    1982-04-01

    Nuclear scattering of protons allows to radiograph objects with specific properties: 3-dimensional radiography, different information as compared to X-ray technique, hydrogen radiography. Furthermore the nuclear scattering radiography (NSR) is a well adapted method to gating techniques allowing the radiography of fast periodic moving objects. Results obtained on phantoms, formalin fixed head and moving object are shown and discussed. The dose delivery is compatible with clinical use, but at the moment, the irradiation time is too long between 1 and 4 hours. Perspectives to make the radiograph faster and to get a practical method are discussed

  10. Single Crystal Diffuse Neutron Scattering

    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.

  11. MMP-sensitive PEG diacrylate hydrogels with spatial variations in matrix properties stimulate directional vascular sprout formation.

    Michael V Turturro

    Full Text Available The spatial presentation of immobilized extracellular matrix (ECM cues and matrix mechanical properties play an important role in directed and guided cell behavior and neovascularization. The goal of this work was to explore whether gradients of elastic modulus, immobilized matrix metalloproteinase (MMP-sensitivity, and YRGDS cell adhesion ligands are capable of directing 3D vascular sprout formation in tissue engineered scaffolds. PEGDA hydrogels were engineered with mechanical and biofunctional gradients using perfusion-based frontal photopolymerization (PBFP. Bulk photopolymerized hydrogels with uniform mechanical properties, degradation, and immobilized biofunctionality served as controls. Gradient hydrogels exhibited an 80.4% decrease in elastic modulus and a 56.2% decrease in immobilized YRGDS. PBFP hydrogels also demonstrated gradients in hydrogel degradation with degradation times ranging from 10-12 hours in the more crosslinked regions to 4-6 hours in less crosslinked regions. An in vitro model of neovascularization, composed of co-culture aggregates of endothelial and smooth muscle cells, was used to evaluate the effect of these gradients on vascular sprout formation. Aggregate invasion in gradient hydrogels occurred bi-directionally with sprout alignment observed in the direction parallel to the gradient while control hydrogels with homogeneous properties resulted in uniform invasion. In PBFP gradient hydrogels, aggregate sprout length was found to be twice as long in the direction parallel to the gradient as compared to the perpendicular direction after three weeks in culture. This directionality was found to be more prominent in gradient regions of increased stiffness, crosslinked MMP-sensitive peptide presentation, and immobilized YRGDS concentration.

  12. State-to-state time-of-flight measurements of NO scattering from Au(111): direct observation of translation-to-vibration coupling in electronically nonadiabatic energy transfer.

    Golibrzuch, Kai; Shirhatti, Pranav R; Altschäffel, Jan; Rahinov, Igor; Auerbach, Daniel J; Wodtke, Alec M; Bartels, Christof

    2013-09-12

    Translational motion is believed to be a spectator degree of freedom in electronically nonadiabatic vibrational energy transfer between molecules and metal surfaces, but the experimental evidence available to support this view is limited. In this work, we have experimentally determined the translational inelasticity in collisions of NO molecules with a single-crystal Au(111) surface-a system with strong electronic nonadiabaticity. State-to-state molecular beam surface scattering was combined with an IR-UV double resonance scheme to obtain high-resolution time-of-flight data. The measurements include vibrationally elastic collisions (v = 3→3, 2→2) as well as collisions where one or two quanta of molecular vibration are excited (2→3, 2→4) or de-excited (2→1, 3→2, 3→1). In addition, we have carried out comprehensive measurements of the effects of rotational excitation on the translational energy of the scattered molecules. We find that under all conditions of this work, the NO molecules lose a large fraction (∼0.45) of their incidence translational energy to the surface. Those molecules that undergo vibrational excitation (relaxation) during the collision recoil slightly slower (faster) than vibrationally elastically scattered molecules. The amount of translational energy change depends on the surface temperature. The translation-to-rotation coupling, which is well-known for v = 0→0 collisions, is found to be significantly weaker for vibrationally inelastic than elastic channels. Our results clearly show that the spectator view of the translational motion in electronically nonadiabatic vibrational energy transfer between NO and Au(111) is only approximately correct.

  13. Quantum Optical Multiple Scattering

    Ott, Johan Raunkjær

    . In the first part we use a scattering-matrix formalism combined with results from random-matrix theory to investigate the interference of quantum optical states on a multiple scattering medium. We investigate a single realization of a scattering medium thereby showing that it is possible to create entangled...... states by interference of squeezed beams. Mixing photon states on the single realization also shows that quantum interference naturally arises by interfering quantum states. We further investigate the ensemble averaged transmission properties of the quantized light and see that the induced quantum...... interference survives even after disorder averaging. The quantum interference manifests itself through increased photon correlations. Furthermore, the theoretical description of a measurement procedure is presented. In this work we relate the noise power spectrum of the total transmitted or reflected light...

  14. Aggregation and composition effects on absorption and scattering properties of dye-sensitized anatase TiO{sub 2} particle clusters

    Vargas, William E. [Centro de Investigacion en Ciencia e Ingenieria de Materiales and Escuela de Fisica, Universidad de Costa Rica, 2060 San Jose (Costa Rica)], E-mail: vargasc@cariari.ucr.ac.cr

    2008-06-15

    A transition matrix approach is used to compute the scattering and absorption cross sections, as well as phase functions, asymmetry factors and forward scattering ratios, of clusters of spherical particles. In order to approach the local structure and composition of the nanosized active layer of photoelectrochemical solar cells, some clusters consist of homogeneous non-absorbing anatase spherical pigments, others have anatase particles coated with a monolayer of absorbing dye molecules, and others can consist of both uncoated and dye-coated anatase particles. Orientation average values of the volumetric scattering and absorption cross sections are computed in terms of the size of the spherical particles in the clusters and their number. The degree of scattering and absorption when considering dye-coated anatase particles in the clusters is characterized. The effect of dependent scattering on the average angular distribution of the scattered radiation is also considered.

  15. Correlation in atomic scattering

    McGuire, J.H.

    1987-01-01

    Correlation due to the Coulomb interactions between electrons in many-electron targets colliding with charged particles is formulated, and various approximate probability amplitudes are evaluated. In the limit that the electron-electron, 1/r/sub i//sub j/, correlation interactions are ignored or approximated by central potentials, the independent-electron approximation is obtained. Two types of correlations, or corrections to the independent-electron approximation due to 1/r/sub i//sub j/ terms, are identified: namely, static and scattering correlation. Static correlation is that contained in the asymptotic, e.g., bound-state, wave functions. Scattering correlation, arising from correlation in the scattering operator, is new and is considered in some detail. Expressions for a scattering correlation amplitude, static correlation or rearrangement amplitude, and independent-electron or direct amplitude are derived at high collision velocity and compared. At high velocities the direct and rearrangement amplitudes dominate. At very high velocities, ν, the rearrangement amplitude falls off less rapidly with ν than the direct amplitude which, however, is dominant as electron-electron correlation tends to zero. Comparisons with experimental observations are discussed

  16. Direct fluorination? Useful tool to enhance commercial properties of polymer articles

    Kharitonov, A.P.; Taege, R.; Ferrier, G.; Teplyakov, V.V.; Syrtsova, D.A.; Syrtsova, D.A.; Koops, G.H.

    2005-01-01

    Fundamental features and industrial applications of the direct fluorination of polymers are reviewed. Fundamental features of the direct fluorination of a set of polymers, such as polystyrene, polyethyleneterephthalate, poly(2,6-dimethyl-1,4-phenylene oxide), PMMA, LDPE (two types), HDPE (six

  17. An algorithm to determine backscattering ratio and single scattering albedo

    Suresh, T.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.A.M.Q.; Nayak, S.R.; Naik, P.

    Algorithms to determine the inherent optical properties of water, backscattering probability and single scattering albedo at 490 and 676 nm from the apparent optical property, remote sensing reflectance are presented here. The measured scattering...

  18. Raman scattering in GaN, AlN and AlGaN. Basic material properties, processing and devices

    Hayes, J.M.

    2002-05-01

    GaN, AIN and AIGaN are very promising materials for high-power, high-temperature and high-frequency electronic device applications but many of their material properties and the effects of processing steps for device fabrication have not yet been fully investigated. AIGaN/GaN films were annealed at temperatures of 800 to 1300 deg C in different ambient atmospheres. The films were then analysed by micro-Raman spectroscopy. Compressive stress was found in films annealed in oxygen containing atmospheres which was significantly enhanced by the presence of water vapour in the annealing atmosphere. No stress was detected after annealing in nitrogen even at temperatures close to the thermal decomposition temperature and in the presence of water vapour. Thermal decomposition can be prevented by the use of high-pressure atmospheres during annealing. Mg/P implanted and non-implanted GaN films annealed at temperatures up to 1500 deg C with nitrogen over-pressures of 1-1.5 GPa were analysed by micro-Raman spectroscopy. Annealing temperatures of 1400-1500 deg C resulted in the nearly full recovery of the crystalline quality of the ion-implanted GaN. Ultraviolet Raman spectroscopy showed that no significant surface degradation occurred during the annealing. High-quality bulk AIN crystals were studied by micro-Raman spectroscopy. The pressure dependence of the phonon frequencies was measured in the range 0 GPa to 9.5 GPa determining the mode-Grueneisen parameters. The temperature dependence of the phonon frequencies and lifetimes was measured from 10 K to 1275 K. Empirical fitting and theoretical modelling of the temperature dependence was performed. The results have application for the monitoring of temperature in (Ga/AI)N. The E 2 (high) phonon frequency of GaN measured by micro-Raman spectroscopy was used to monitor local temperatures in active AIGaN/GaN hetero-structure field effect transistor devices (HFETs). The temperature rise in the active area of devices on sapphire

  19. Properties of thermal neutron scattering on the nucleus of hydrogen atom of methane molecule; Osobine rasejanja termalnih neutrona na jezgru vodonikovog atoma molekula metana

    Miloradovic, M M [Tehnicki fakultet, Cacak (Yugoslavia); Markovic, M I [Elektrotehnicki fakultet, Beograd (Yugoslavia)

    1987-07-01

    On the basis of derived quantum-mechanical expression for the microscopic nucleus scattering the single and collective influences of translational, rotational and intravibrational motions of the methane molecule on the thermal neutron scattering are established. When incident neutron energy is E{sub 0} {<=} 0.1 eV, it is found that only translational and rotational motion of the methane molecule influences the thermal neutron scattering. The influence of these motions for E{sub 0} . 0.1 eV decreases rapidly with the increase of the incident neutron energy and then the significant influence on the thermal neutron scattering exerts inelastic scattering on the combined rotational with single intravibrational phonons of the methane molecule, while the inelastic scattering on single intravibrational phonons is significantly less. In the combination with rotational phonons the biggest influence has threefold degenerated deformed intravibrational phonons, somehow less influence has twofold degenerated deformed intravibrational phonons, and the least influence has valent intravibrational phonons. All the effects of quasielastic and quantum inelastic scattering are clearly expressed with the thermal neutron scattering at small angles, so that for E{sub 0} =1 eV practically there is no scattering backward. (author)

  20. Co-spray Drying with HPMC as a Platform to Improve Direct Compaction Properties of Various Tablet Fillers.

    Li, JinZhi; Zhao, LiJie; Lin, Xiao; Shen, Lan; Feng, Yi

    2017-11-01

    Many commonly used tablet fillers are not suitable for direct compaction process due to insufficient properties, mainly of flowability and compactability. This work therefore aimed to use co-spray drying with HPMC as a platform to improve direct compaction properties of various tablet fillers. Starch, calcium hydrogen phosphate dihydrate (DCPD), and mannitol were chosen as a representative of three types of commonly used fillers (i.e. organic macromolecules, water-insoluble inorganic salts, and water-soluble small molecular carbohydrates), respectively. The five-level central composite design-response surface methodology was used (i) to investigate the effects of HPMC level and solid content of the feed on various powder, tableting, and tablet properties of composite excipients, and (ii) to optimize the composition. The results showed that the impacts of the two factors on various properties of composite excipients showed great similarity, despite of significantly different primary properties of the parent fillers, and the HPMC level was the main contributor to the majority of the impacts. An increase in HPMC level significantly improved tablet tensile strength and various tableting parameters. For all the three fillers, their optimized composite excipients provided by the established models showed excellent performances as predicted. The platform suggested is confirmed to be effective and promising.

  1. Delbrueck scattering of monoenergetic photons

    Kahane, S.

    1978-05-01

    The Delbrueck effect was experimentally investigated in high Z nuclei with monoenergetic photons in the range 6.8-11.4 MeV. Two different methods were used for measurements of the differential scattering cross-section, in the 25-140 deg range and in the forward direction (theta = 1.5 deg), respectively. The known Compton scattering cross-section was used in a new and unique way for the determination of the elastic scattering cross-section. Isolation of the contribution of the real Delbrueck amplitudes to the cross-section was crried out successfully. Experimental confirmation of the theoretical calculations of Papatzacos and Mork and measurement, for the first time, of the Rayleigh scattering in the 10 MeV region are also reported. One of the most interesting findings is the presence of Coulomb corrections in Delbrueck scattering at these energies. More theoretical effort is needed in this last direction. (author)

  2. Direct transitions among atomic states of negative reflection symmetry in the scattering plane: Li(2p0,3p0,3d±1)-He collisions

    Nielsen, S.E.; Andersen, N.

    1988-01-01

    This paper reports coupled channel model calculations of direct transitions in Li-He collisions among excited Li-states of negative reflection symmetry in the scattering plane. Using the natural coordinate frame, transition probabilities and orientation and alignment parameters are predicted as functions of impact energy and impact parameter for various initial states. It is found that for geometrical reasons transition probabilities are one to two orders of magnitude smaller than for corresponding states with positive reflection symmetry. Some experimental consequences of this finding are pointed out. (orig.)

  3. In Situ Lipolysis and Synchrotron Small-Angle X-ray Scattering for the Direct Determination of the Precipitation and Solid-State Form of a Poorly Water-Soluble Drug During Digestion of a Lipid-Based Formulation

    Khan, Jamal; Hawley, Adrian; Rades, Thomas

    2016-01-01

    In situ lipolysis and synchrotron small-angle X-ray scattering (SAXS) were used to directly detect and elucidate the solid-state form of precipitated fenofibrate from the digestion of a model lipid-based formulation (LBF). This method was developed in light of recent findings that indicate variab...... on drugs, and experimental conditions, which are anticipated to produce altered solid-state forms upon the precipitation of drug (i.e., polymorphs, amorphous forms, and salts). © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci....

  4. Scattering by two spheres: Theory and experiment

    Bjørnø, Irina; Jensen, Leif Bjørnø

    1998-01-01

    of suspended sediments. The scattering properties of single regular-shaped particles have been studied in depth by several authors in the past. However, single particle scattering cannot explain all features of scattering by suspended sediment. When the concentration of particles exceeds a certain limit...... on three issues: (1) to develop a simplified theory for scattering by two elastical spheres; (2) to measure the scattering by two spheres in a water tank, and (3) to compare the theoretical/numerical results with the measured data. A number of factors influencing multiple scattering, including...

  5. Compton scattering

    Botto, D.J.; Pratt, R.H.

    1979-05-01

    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A -2 based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required

  6. Compton scattering

    Botto, D.J.; Pratt, R.H.

    1979-05-01

    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A/sup -2/ based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required.

  7. Simultaneous in situ measurements of properties of particulates in rf silane plasmas using a polarization-sensitive laser-light-scattering method

    Shiratani, Masaharu; Kawasaki, Hiroharu; Fukuzawa, Tsuyoshi; Yoshioka, Takashi; Ueda, Yoshio; Singh, Sanjay; Watanabe, Yukio

    1996-01-01

    A polarization-sensitive laser-light-scattering method is developed for simultaneous in situ measurements of properties (size, size dispersion, density, and refractive index) of particulates formed in processing plasmas. The developed system is applied to observe the growth processes of particulates in a range of their size larger than about 10 nm in rf silane plasmas. A size, a size dispersion (logarithm of a standard deviation of size), a density, and a refractive index of particulates in the plasmas are found to be 10-200 nm, about 0.1, 107-109 cm-3 and about 3-5i, respectively. The former three of such values agree fairly well with ones deduced from scanning electron microscopic (SEM) observation. These particulates grow through three phases of nucleation and initial growth, rapid growth, and growth saturation. Coexistence of two size groups of particulates with narrow size dispersions during and after the rapid growth phase verified by the SEM observation may be explained by a model taking into account coagulation between oppositely charged particulates.

  8. Copper doped TiO2 nanoparticles characterized by X-ray absorption spectroscopy, total scattering, and powder diffraction--a benchmark structure-property study.

    Lock, Nina; Jensen, Ellen M L; Mi, Jianli; Mamakhel, Aref; Norén, Katarina; Qingbo, Meng; Iversen, Bo B

    2013-07-14

    Metal functionalized nanoparticles potentially have improved properties e.g. in catalytic applications, but their precise structures are often very challenging to determine. Here we report a structural benchmark study based on tetragonal anatase TiO2 nanoparticles containing 0-2 wt% copper. The particles were synthesized by continuous flow synthesis under supercritical water-isopropanol conditions. Size determination using synchrotron PXRD, TEM, and X-ray total scattering reveals 5-7 nm monodisperse particles. The precise dopant structure and thermal stability of the highly crystalline powders were characterized by X-ray absorption spectroscopy and multi-temperature synchrotron PXRD (300-1000 K). The combined evidence reveals that copper is present as a dopant on the particle surfaces, most likely in an amorphous oxide or hydroxide shell. UV-VIS spectroscopy shows that copper presence at concentrations higher than 0.3 wt% lowers the band gap energy. The particles are unaffected by heating to 600 K, while growth and partial transformation to rutile TiO2 occur at higher temperatures. Anisotropic unit cell behavior of anatase is observed as a consequence of the particle growth (a decreases and c increases).

  9. Synthesis of silver/silver chloride/graphene oxide composite and its surface-enhanced Raman scattering activity and self-cleaning property

    Zhao, Nan; Fei, Xiao; Cheng, Xiaonong; Yang, Juan

    2017-09-01

    Recently, silver nanoparticles decorated with graphene and graphene oxide (GO) sheets can be employed as surface-enhanced Raman scattering (SERS) substrates. However, their SERS activity on macromolecular compound detection is all one-time process. In order to solve this issue and decrease the cost of routine SERS detection, silver/silver chloride (Ag/AgCl) with photocatalytic activity under visible light was introduced. In this study, a novel, simple and clean approach is carried out for synthesis of the Ag/AgCl/GO composite. The Ag/AgCl colloidal solution is obtained by hydrothermal method and then mixed with GO solution to obtain the Ag/AgCl/GO composite using a facile electrostatic self-assembly method. Results showed that the Ag/AgCl/GO composite has the optimized SERS activity to Rhodamine 6G molecules with the maximum enhancement factor value of 3.8×107. Furthermore, the Ag/AgCl particles with high efficient and stable photocatalytic activity under visible light lead to an outstanding self-cleaning property of the Ag/AgCl/GO composite.

  10. Synthesis of one-dimensional metal-containing insulated molecular wire with versatile properties directed toward molecular electronics materials.

    Masai, Hiroshi; Terao, Jun; Seki, Shu; Nakashima, Shigeto; Kiguchi, Manabu; Okoshi, Kento; Fujihara, Tetsuaki; Tsuji, Yasushi

    2014-02-05

    We report, herein, the design, synthesis, and properties of new materials directed toward molecular electronics. A transition metal-containing insulated molecular wire was synthesized through the coordination polymerization of a Ru(II) porphyrin with an insulated bridging ligand of well-defined structure. The wire displayed not only high linearity and rigidity, but also high intramolecular charge mobility. Owing to the unique properties of the coordination bond, the interconversion between the monomer and polymer states was realized under a carbon monoxide atmosphere or UV irradiation. The results demonstrated a high potential of the metal-containing insulated molecular wire for applications in molecular electronics.

  11. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    John H. Bradford; Stephen Holbrook; Scott B. Smithson

    2004-12-09

    The focus of this project is direct detection of DNAPL's specifically chlorinated solvents, via material property estimation from multi-fold surface ground-penetrating radar (GPR) data. We combine state-of-the-art GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects.

  12. Membrane properties of striatal direct and indirect pathway neurons in mouse and rat slices and their modulation by dopamine.

    Henrike Planert

    Full Text Available D1 and D2 receptor expressing striatal medium spiny neurons (MSNs are ascribed to striatonigral ("direct" and striatopallidal ("indirect" pathways, respectively, that are believed to function antagonistically in motor control. Glutamatergic synaptic transmission onto the two types is differentially affected by Dopamine (DA, however, less is known about the effects on MSN intrinsic electrical properties. Using patch clamp recordings, we comprehensively characterized the two pathways in rats and mice, and investigated their DA modulation. We identified the direct pathway by retrograde labeling in rats, and in mice we used transgenic animals in which EGFP is expressed in D1 MSNs. MSNs were subjected to a series of current injections to pinpoint differences between the populations, and in mice also following bath application of DA. In both animal models, most electrical properties were similar, however, membrane excitability as measured by step and ramp current injections consistently differed, with direct pathway MSNs being less excitable than their counterparts. DA had opposite effects on excitability of D1 and D2 MSNs, counteracting the initial differences. Pronounced changes in AP shape were seen in D2 MSNs. In direct pathway MSNs, excitability increased across experimental conditions and parameters, and also when applying DA or the D1 agonist SKF-81297 in presence of blockers of cholinergic, GABAergic, and glutamatergic receptors. Thus, DA induced changes in excitability were D1 R mediated and intrinsic to direct pathway MSNs, and not a secondary network effect of altered synaptic transmission. DAergic modulation of intrinsic properties therefore acts in a synergistic manner with previously reported effects of DA on afferent synaptic transmission and dendritic processing, supporting the antagonistic model for direct vs. indirect striatal pathway function.

  13. Nonstationary interference and scattering from random media

    Nazikian, R.

    1991-12-01

    For the small angle scattering of coherent plane waves from inhomogeneous random media, the three dimensional mean square distribution of random fluctuations may be recovered from the interferometric detection of the nonstationary modulational structure of the scattered field. Modulational properties of coherent waves scattered from random media are related to nonlocal correlations in the double sideband structure of the Fourier transform of the scattering potential. Such correlations may be expressed in terms of a suitability generalized spectral coherence function for analytic fields

  14. Quasielastic Neutron Scattering by Superionic Strontium Chloride

    Dickens, M. H.; Hutchings, M. T.; Kjems, Jørgen

    1978-01-01

    The scattering, from powder and single crystal samples, appears only above the superionic transition temperature, 1000K. The integrated intensity is found to be strongly dependent on the direction and magnitude of the scattering vector, Q, (which suggests the scattering is coherent) but does not ...

  15. Measurement of scattering and absorption properties of dust aerosol in a Gobi farmland region of northwestern China – a potential anthropogenic influence

    J. Bi

    2017-06-01

    Full Text Available We conducted a comprehensive field campaign to explore the optical characteristics of mineral dust in Dunhuang farmland near the Gobi Desert of northwest China during spring of 2012. The day-to-day and diurnal variations of dust aerosol showed prominent features throughout the experiment, primarily attributable to frequent dust events and local anthropogenic emissions. The overall average mass concentrations of the particulate matter with an aerodynamic diameter less than 10 µm (PM10, light scattering coefficient (σsp, 670, absorption coefficient (σap, 670, and single-scattering albedo (SSA670 were 113 ± 169 µg m−3, 53.3 ± 74.8 Mm−1, 3.2 ± 2.4 Mm−1, and 0.913 ± 0.05, respectively, which were comparable to the background levels in the southern United States but smaller than those in the eastern and other northwestern Chinese cities. The anthropogenic dust produced by agricultural cultivations (e.g., land planning, plowing, and disking exerted a significant superimposed effect on high dust concentrations in Dunhuang farmland prior to the growing season (i.e., from 1 April to 10 May. Strong south valley wind and vertical mixing in daytime scavenged the pollution, and the weak northeast mountain wind and stable inversion layer at night favorably accumulated the air pollutants near the surface. In the afternoon (13:00–18:00 LT, local time, mean SSA670 was 0.945 ± 0.04 predominantly from dust particles, whereas finer particles and lower SSA670 values ( ∼  0.90–0.92 were measured at night, suggesting the potential influence by the mixed dust pollutants. During a typical biomass burning event on 4 April 2012, σap, 670 increased from  ∼  2.0 to 4.75 Mm−1 and SSA670 changed from  ∼  0.90 to  ∼  0.83, implying remarkable modification of aerosol absorptive properties induced by human activities. The findings of this study would help to advance an in

  16. Detection of explosives by neutron scattering

    Brooks, F.D.; Buffler, A.; Allie, M.S.; Nchodu, M.R.; Bharuth-Ram, K.

    1998-01-01

    For non-intrusive detection of hidden explosives or other contraband such as narcotics a fast neutron scattering analysis (FNSA) technique is proposed. An experimental arrangement uses a collimated, pulsed beam of neutrons directed at the sample. Scattered neutrons are detected by liquid scintillation counters at different scattering angles. A scattering signature is derived from two-parameter data, counts vs pulse height and time-of-flight measured for each element (H, C, N or O) at each of two scattering angles and two neutron energies. The elemental signatures are very distinctive and constitute a good response matrix for unfolding elemental components from the scattering signatures measured for different compounds

  17. Field-based dynamic light scattering microscopy: theory and numerical analysis.

    Joo, Chulmin; de Boer, Johannes F

    2013-11-01

    We present a theoretical framework for field-based dynamic light scattering microscopy based on a spectral-domain optical coherence phase microscopy (SD-OCPM) platform. SD-OCPM is an interferometric microscope capable of quantitative measurement of amplitude and phase of scattered light with high phase stability. Field-based dynamic light scattering (F-DLS) analysis allows for direct evaluation of complex-valued field autocorrelation function and measurement of localized diffusive and directional dynamic properties of biological and material samples with high spatial resolution. In order to gain insight into the information provided by F-DLS microscopy, theoretical and numerical analyses are performed to evaluate the effect of numerical aperture of the imaging optics. We demonstrate that sharp focusing of fields affects the measured diffusive and transport velocity, which leads to smaller values for the dynamic properties in the sample. An approach for accurately determining the dynamic properties of the samples is discussed.

  18. Direct Comparison of Physical Properties of Bacillus subtilis NCIB 3610 and B-1 Biofilms

    Kesel, Sara; Grumbein, Stefan; Gümperlein, Ina; Tallawi, Marwa; Marel, Anna-Kristina

    2016-01-01

    Many bacteria form surface-attached communities known as biofilms. Due to the extreme resistance of these bacterial biofilms to antibiotics and mechanical stresses, biofilms are of growing interest not only in microbiology but also in medicine and industry. Previous studies have determined the extracellular polymeric substances present in the matrix of biofilms formed by Bacillus subtilis NCIB 3610. However, studies on the physical properties of biofilms formed by this strain are just emerging. In particular, quantitative data on the contributions of biofilm matrix biopolymers to these physical properties are lacking. Here, we quantitatively investigated three physical properties of B. subtilis NCIB 3610 biofilms: the surface roughness and stiffness and the bulk viscoelasticity of these biofilms. We show how specific biomolecules constituting the biofilm matrix formed by this strain contribute to those biofilm properties. In particular, we demonstrate that the surface roughness and surface elasticity of 1-day-old NCIB 3610 biofilms are strongly affected by the surface layer protein BslA. For a second strain, B. subtilis B-1, which forms biofilms containing mainly γ-polyglutamate, we found significantly different physical biofilm properties that are also differently affected by the commonly used antibacterial agent ethanol. We show that B-1 biofilms are protected from ethanol-induced changes in the biofilm's stiffness and that this protective effect can be transferred to NCIB 3610 biofilms by the sole addition of γ-polyglutamate to growing NCIB 3610 biofilms. Together, our results demonstrate the importance of specific biofilm matrix components for the distinct physical properties of B. subtilis biofilms. PMID:26873313

  19. Direct monitoring of calcium-triggered phase transitions in cubosomes using small-angle X-ray scattering combined with microfluidics

    Ghazal, Aghiad; Gontsarik, Mark; Kutter, Jörg P.

    2016-01-01

    This article introduces a simple microfluidic device that can be combined with synchrotron small-angle X-ray scattering (SAXS) for monitoring dynamic structural transitions. The microfluidic device is a thiol-ene-based system equipped with 125 µm-thick polystyrene windows, which are suitable for ....... The combination of microfluidics with X-ray techniques can be used for investigating protein unfolding, for monitoring the formation of nanoparticles in real time, and for other biomedical and pharmaceutical investigations.......-ray experiments. The device was prepared by soft lithography using elastomeric molds followed by a simple UV-initiated curing step to polymerize the chip material and simultaneously seal the device with the polystyrene windows. The microfluidic device was successfully used to explore the dynamics...

  20. Quantitative theory of channeling particle diffusion in transverse energy in the presence of nuclear scattering and direct evaluation of dechanneling length

    Tikhomirov, Victor V. [Belarusian State University, Institute for Nuclear Problems, Minsk (Belarus)

    2017-07-15

    A refined equation for channeling particle diffusion in transverse energy taking into consideration large-angle scattering by nuclei is suggested. This equation is reduced to the Sturm-Liouville problem, allowing one to reveal both the origin and the limitations of the dechanneling length notion. The values of the latter are evaluated for both positively and negatively charged particles of various energies. New features of the dechanneling dynamics of positively charged particles are also revealed. First, it is demonstrated that the dechanneling length notion is completely inapplicable for their nuclear dechanneling process. Second, the effective electron dechanneling length of positively charged particle varies more than twice converging to a constant asymptotic value only at the depth exceeding the latter. (orig.)

  1. Light scattering studies of solids and atomic vapors

    Chiang, T.C.

    1978-09-01

    The general technique of light scattering and luminescence was used to study the properties of a number of material systems. First, multi-phonon resonant Raman scattering up to four phonons in GaSe and one- and two-phonon resonant Raman scattering in the mixed GaS/sub x/Se/sub 1-x/ crystals with x 2 is reported. The result is used to determine the position of the direct gap of HfS 2 . Third, the first observation of the π-polarized one-magnon luminescence sideband of the 4 T/sub lg/ ( 4 G) → 6 A/sub lg/( 6 S) excitonic transition in antiferromagnetic MnF 2 is presented. An effective temperature of the crystal is deduced from the simultaneously observed anti-Stokes sideband emission. Multi-magnon ( 2 , KMnF 2 , and RbMnF 3 using pulsed excitation and detection. A simple model based on two-ion local exchange is proposed to explain the results qualitatively. Fourth, the first observation of two-magnon resonant Raman scattering in MnF 2 around the magnon sidebands is reported. A simple theoretical description explains the experimental observations. Fifth, a detailed theory of exciton-exciton interaction in MnF 2 is developed to explain and to predict the experimental results on two-exciton absorption, high level excitation, and exciton--exciton scattering. Sixth, Brillouin scattering was used to obtain the five independent elastic constants of the layered compound GaSe. The results show clear elastic anisotropy of the crystal. Resonant Brillouin scattering near the absorption edge was also studied, but no resonant enhancement was found. Seventh, two-photon parametric scattering in sodium vapor was studied. Phase matching angles and scattering cross sections are calculated for a given set of experimental conditions

  2. Electrocatalytic properties of graphite nanofibers-supported platinum catalysts for direct methanol fuel cells.

    Park, Soo-Jin; Park, Jeong-Min; Seo, Min-Kang

    2009-09-01

    Graphite nanofibers (GNFs) treated at various temperatures were used as carbon supports to improve the efficiency of PtRu catalysts. The electrochemical properties of the PtRu/GNFs catalysts were then investigated to evaluate their potential for application in DMFCs. The results indicated that the particle size and dispersibility of PtRu in the catalysts were changed by heat treatment, and the electrochemical activity of the catalysts was improved. Consequently, it was found that heat treatments could have an influence on the surface and structural properties of GNFs, resulting in enhancing an electrocatalytic activity of the catalysts for DMFCs.

  3. Instruments evaluating the self-directed learning abilities among nursing students and nurses: a systematic review of psychometric properties.

    Cadorin, Lucia; Bressan, Valentina; Palese, Alvisa

    2017-11-25

    Modern healthcare institutions are continuously changing, and Self-Directed Learning (SDL) abilities are considered a prerequisite for both nursing students and nurses in order to be proactive about these demanding challenges. To date, no systematic reviews of existing instruments aimed at detecting and critically evaluating SDL abilities have been published. Therefore, the aims of this review are: 1) identify the instruments for assessment of SDL abilities among nursing students and nurses; 2) critically evaluate the methodological studies quality; and 3) compare the psychometric properties of the available instruments. A psychometric-systematic-review was performed. CDSR, CINAHL, ERIC, MEDLINE, PROSPERO, SCOPUS databases were searched without restrictions in time and setting. All primary studies involving nursing students or nurses, written in English and aimed at validating SDL assessment tools, were included. Studies retrieved were evaluated according to the COnsensus-based-Standards for the selection of health Measurement-INstruments (COSMIN) panel. Study inclusion, data extraction and quality assessment were performed by researchers independently. Eleven studies were included and four tools based on Knowles's theory have emerged: 1) the Self-Directed Learning Readiness Scale; 2) the Self-Directed Learning Readiness Scale for Nursing Education; 3) the Self-Rating Scale of Self-Directed Learning, and 4) the Self-Directed Learning Instrument. A few psychometric properties have been considered in each study, from two to four out of the ten required. The quality of the methodologies used was in general, from fair to poor with the exception of one instrument (the Self-Directed-Learning-Instrument). The psychometric proprieties that emerged across the tools were good in general: the Cronbach α was from 0.73 to 0.91; structural validities have also reported good indexes both in the explorative and in the confirmative factor analyses. On the basis of the findings

  4. Instruments evaluating the self-directed learning abilities among nursing students and nurses: a systematic review of psychometric properties

    Lucia Cadorin

    2017-11-01

    Full Text Available Abstract Background Modern healthcare institutions are continuously changing, and Self-Directed Learning (SDL abilities are considered a prerequisite for both nursing students and nurses in order to be proactive about these demanding challenges. To date, no systematic reviews of existing instruments aimed at detecting and critically evaluating SDL abilities have been published. Therefore, the aims of this review are: 1 identify the instruments for assessment of SDL abilities among nursing students and nurses; 2 critically evaluate the methodological studies quality; and 3 compare the psychometric properties of the available instruments. Methods A psychometric-systematic-review was performed. CDSR, CINAHL, ERIC, MEDLINE, PROSPERO, SCOPUS databases were searched without restrictions in time and setting. All primary studies involving nursing students or nurses, written in English and aimed at validating SDL assessment tools, were included. Studies retrieved were evaluated according to the COnsensus-based-Standards for the selection of health Measurement-INstruments (COSMIN panel. Study inclusion, data extraction and quality assessment were performed by researchers independently. Results Eleven studies were included and four tools based on Knowles’s theory have emerged: 1 the Self-Directed Learning Readiness Scale; 2 the Self-Directed Learning Readiness Scale for Nursing Education; 3 the Self-Rating Scale of Self-Directed Learning, and 4 the Self-Directed Learning Instrument. A few psychometric properties have been considered in each study, from two to four out of the ten required. The quality of the methodologies used was in general, from fair to poor with the exception of one instrument (the Self-Directed-Learning-Instrument. The psychometric proprieties that emerged across the tools were good in general: the Cronbach α was from 0.73 to 0.91; structural validities have also reported good indexes both in the explorative and in the confirmative

  5. Effect of direct quenching on the microstructure and mechanical properties of the lean-chemistry HSLA-100 steel plates

    Dhua, S.K.; Sen, S.K.

    2011-01-01

    Highlights: → Direct-quenched and tempered (DQT) steels gives better mechanical properties. → Fine Cu and Nb (C, N) precipitates enhance matrix strengthening and tempering resistance. → Boron promotes hardenability, but low temperature Charpy impact toughness gets affected. → Mechanical properties equivalent to HSLA-100 steel is achieved by directly quenched leaner chemistry alloys. - Abstract: The influence of direct quenching on structure-property behavior of lean chemistry HSLA-100 steels was studied. Two laboratory heats, one containing Cu and Nb (C:0.052, Mn:0.99, Cu:1.08, Nb:0.043, Cr:0.57, Ni:1.76, Mo:0.55 pct) and the other containing Cu, Nb and B (C:0.04, Mn:1.02, Cu:1.06, Nb:0.036, Cr:0.87, Ni:1.32, Mo:0.41, B:0.002 percent) were hot-rolled into 25 and 12.5 mm thick plates by varying finish-rolling temperatures. The plates were heat-treated by conventional reheat quenching and tempering (RQT), as well as by direct quenching and tempering (DQT) techniques. In general, direct-quench and tempered plates of Nb-Cu heat exhibited good strength (yield strength ∼ 900 MPa) and low-temperature impact toughness (average: 74 J at -85 deg. C); the Charpy V-notch impact energies were marginally lower than conventional HSLA-100 steel. In Nb-Cu-B heat, impact toughness at low-temperature was inferior owing to boron segregation at grain boundaries. Transmission electron microscopy (TEM) and scanning auger microprobe (SAM) analysis confirmed existence of borocarbides at grain boundaries in this steel. In general, for both the steels, the mechanical properties of the direct-quench and tempered plates were found to be superior to reheat quench and tempered plates. A detailed transmission electron microscopy study revealed presence of fine Cu and Nb (C, N) precipitates in these steels. It was also observed that smaller martensite inter-lath spacing, finer grains and precipitates in direct-quench and tempered plates compared to the reheat quench and tempered plates

  6. TABLETING PROPERTIES OF EXPERIMENTAL AND COMMERCIALLY AVAILABLE LACTOSE GRANULATIONS FOR DIRECT COMPRESSION

    BOLHUIS, GK; ZUURMAN, K

    1995-01-01

    Lactose granulations (125-250 mu m) were prepared from two different alpha-lactose monohydrate powders and one roller dried beta-lactose powder respectively, by wet granulation with only water as a binder. As an effect of the granulation process, the flow properties improved, but the compactibility

  7. Scattered X-ray beam nondestructive testing

    Harding, G.; Kosanetzky, J.

    1988-01-01

    X-ray scatter interactions generally dominate the linear attenuation coefficient at the photon energies typical of medical and industrial radiography. Specific advantages of X-ray scatter imaging, including a flexible choice of measurement geometry, direct 3D-imaging capability (tomography) and improved information for material characterization, are illustrated with results from Compton and coherent scatter devices. Applications of a Compton backscatter scanner (ComScan) in the aerospace industry and coherent scatter imaging in security screening are briefly considered [pt

  8. Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTES

    Stolker, T.; Min, M.; Stam, D. M.; Mollière, P.; Dominik, C.; Waters, L. B. F. M.

    2017-11-01

    Context. Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly detectable with the newest generation of high-contrast imaging instruments. Aims: We aim to investigate the effect of latitudinal and longitudinal cloud variations, circumplanetary disks, atmospheric oblateness, and cloud particle properties on the integrated degree and direction of polarization in the near-infrared. We want to understand how 3D atmospheric asymmetries affect the polarization signal in order to assess the potential of infrared polarimetry for direct imaging observations of planetary-mass companions. Methods: We have developed a three-dimensional Monte Carlo radiative transfer code (ARTES) for scattered light simulations in (exo)planetary atmospheres. The code is applicable to calculations of reflected light and thermal radiation in a spherical grid with a parameterized distribution of gas, clouds, hazes, and circumplanetary material. A gray atmosphere approximation is used for the thermal structure. Results: The disk-integrated degree of polarization of a horizontally-inhomogeneous atmosphere is maximal when the planet is flattened, the optical thickness of the equatorial clouds is large compared to the polar clouds, and the clouds are located at high altitude. For a flattened planet, the integrated polarization can both increase or decrease with respect to a spherical planet which depends on the horizontal distribution and optical thickness of the clouds. The direction of polarization can be either parallel or perpendicular to the projected direction of the rotation axis when clouds are zonally distributed. Rayleigh scattering by submicron-sized cloud particles will maximize the polarimetric signal whereas the integrated degree of polarization is significantly reduced with micron

  9. Assessing the measurement of aerosol single scattering albedo by Cavity Attenuated Phase-Shift Single Scattering Monitor (CAPS PMssa)

    Perim de Faria, Julia; Bundke, Ulrich; Onasch, Timothy B.; Freedman, Andrew; Petzold, Andreas

    2016-04-01

    The necessity to quantify the direct impact of aerosol particles on climate forcing is already well known; assessing this impact requires continuous and systematic measurements of the aerosol optical properties. Two of the main parameters that need to be accurately measured are the aerosol optical depth and single scattering albedo (SSA, defined as the ratio of particulate scattering to extinction). The measurement of single scattering albedo commonly involves the measurement of two optical parameters, the scattering and the absorption coefficients. Although there are well established technologies to measure both of these parameters, the use of two separate instruments with different principles and uncertainties represents potential sources of significant errors and biases. Based on the recently developed cavity attenuated phase shift particle extinction monitor (CAPS PM_{ex) instrument, the CAPS PM_{ssa instrument combines the CAPS technology to measure particle extinction with an integrating sphere capable of simultaneously measuring the scattering coefficient of the same sample. The scattering channel is calibrated to the extinction channel, such that the accuracy of the single scattering albedo measurement is only a function of the accuracy of the extinction measurement and the nephelometer truncation losses. This gives the instrument an accurate and direct measurement of the single scattering albedo. In this study, we assess the measurements of both the extinction and scattering channels of the CAPS PM_{ssa through intercomparisons with Mie theory, as a fundamental comparison, and with proven technologies, such as integrating nephelometers and filter-based absorption monitors. For comparison, we use two nephelometers, a TSI 3563 and an Aurora 4000, and two measurements of the absorption coefficient, using a Particulate Soot Absorption Photometer (PSAP) and a Multi Angle Absorption Photometer (MAAP). We also assess the indirect absorption coefficient

  10. New polymeric electrolyte membranes based on proton donor proton acceptor properties for direct methanol fuel cells

    Manea, G.C.; Mulder, M.H.V.

    2002-01-01

    In order to reduce the high methanol permeability of membranes in a direct methanol fuel cell application new and better materials are still required. In this paper membranes made from polybenzimidazole/sulfonated polysulfone are given and compared with homopolymer membranes made from sulfonated

  11. Transmission Property of Directly Modulated Signals Enhanced by a Micro-ring Resonator

    An, Yi; Lorences Riesgo, Abel; Seoane, Jorge

    2012-01-01

    A silicon micro-ring resonator is used to enhance the modulation speed of a 10-Gbit/s directly modulated laser to 40 Gbit/s. The generated signal is transmitted error free over 4.5 km SSMF. Dispersion tolerance is also studied....

  12. Influence of Short-time Oxidation on Corrosion Properties of Directionally Solidified Superalloys with Different Orientations

    MA Luo-ning

    2016-07-01

    Full Text Available In order to investigate the corrosion performance on intersecting and longitudinal surfaces of unoxidized and oxidized directionally solidified superalloys, Ni-base directionally solidified superalloy DZ125 and Co-base directionally solidified superalloy DZ40M were selected. Oxidation behavior on both alloys with different orientations was investigated at 1050℃ at different times, simulating the oxidation process of vanes or blades in service; subsequent electrochemical performance in 3.5%NaCl aqueous solution was studied on two orientations of unoxidized and oxidized alloys, simulating the corrosion process of superalloy during downtime. The results show that grain boundaries and sub-boundaries of directionally solidified superalloys are susceptible to corrosion and thus longitudinal surface with lower area fraction of grain boundaries has higher corrosion resistance. Compared to intersecting surface of alloys, the structure of grain boundaries of longitudinal surface is less conducive to diffusion and thus the oxidation rate on longitudinal surface is lower. Formation of oxide layers on alloys after short-time oxidation provides protective effect and enhances the corrosion resistance.

  13. Direct mechanics assessment of elastic symmetries and properties of trabecular bone architecture

    Rietbergen, van B.; Odgaard, A.; Kabel, J.; Huiskes, H.W.J.

    1996-01-01

    A method is presented to find orthotropic elastic symmetries and constants directly from the elastic coefficients in the overall stiffness matrix of trabecular bone test specimens. Contrary to earlier developed techniques, this method does not require pure orthotropic behavior or additional fabric

  14. Direct investigation of the vectorization properties of amphiphilic cyclodextrins in phospholipid films.

    Javierre, Isabelle; Nedyalkov, Mickael; Petkova, Vera; Benattar, Jean Jacques; Weisse, Sandrine; Auzély-Velty, Rachel; Djedaïni-Pilard, Florence; Perly, Bruno

    2002-10-01

    Recently, new cyclodextrin derivatives were synthesized and shown to exhibit strong amphiphilic properties. In this paper, we study the action of these new amphiphilic cyclodextrins on phospholipids. Mixed phospholipid/cyclodextrin derivative films were prepared and studied using X-ray reflectivity for various phospholipid/cyclodextrin ratios. A molar ratio of 3 provides a highly stable film the molecular structure of which has been investigated in detail. The cholesterol tail of the cyclodextrin molecule was found to be anchored into the phospholipid film. The cyclodextrin moieties exposed to the aqueous medium are prone to the addition of the guest molecule Dosulepin, making them of high interest for drug delivery. For this purpose and as an example of a potential application, this cyclodextrin molecular carrier property is also addressed to this complex film architecture.

  15. Fracture properties of high-strength concrete obtained by direct modification of structure

    Solodkyy Serhiy

    2017-01-01

    Full Text Available High-strength concrete is effectively used worldwide in the last three decades, but it is more brittle in comparison with normal strength concretes. Partial substitution of cement in concrete by active mineral additives and usage of chemical admixture of plasticizing and air-entraining action can considerably change their fracture properties. The obtained results show that the increase of the fracture properties is observed in concretes modified with chemical admixtures incorporating mineral additives such as zeolite and limestone due to consolidation of the concrete microstructure. Densification takes place as a result of limiting the amount of calcium hydroxide (CH due to its reaction with active silica included in the zeolite and the formation of larger amounts of hydrated calcium silicates of tobermorite type as well as calcium hydroaluminate and hydrocarboaluminate with the simultaneous adsorption modification of hydrated products by chemical admixtures.

  16. Surface-enhanced Raman scattering from silver electrodes

    Trott, G.R.

    1982-01-01

    The chemical and physical origins of the anomalously large enhancement of the Raman scattering cross section for molecules adsorbed on silver electrodes in an electrochemical cell were investigated. The effect of the chemical reactions which occur during the anodization/activation procedure were studied using the Ag-CN system. It was shown that the function of the anodization process is to roughen the electrode surface and create an activated site for bonding to the cyanide. A new nonelectrochemical technique for activating the silver surface, along with a study of the enhanced cyanide Raman scattering in different background electrolytes, showed that the Raman active entity on the surface must be a silver-cyanide complex. In order to study the physical mechanism of the enhancement, the angular dependence of the scattered radiation was measured from pyridine adsorbed on an evaporated silver electrode. Both polycrystalline and single crystalline silver films were used. The angular dependence of the scattered radiation from these films showed that the metal surface was controlling the directional properties of the scattered radiation, and not the polarizability tensor of the adsorbate. Based on these experimental results, it was concluded that for weakly roughened silver electrodes the source of the anomalous enhancement is due to a resonant Raman scattering process

  17. STOCHASTIC OPTICS: A SCATTERING MITIGATION FRAMEWORK FOR RADIO INTERFEROMETRIC IMAGING

    Johnson, Michael D.

    2016-01-01

    Just as turbulence in the Earth’s atmosphere can severely limit the angular resolution of optical telescopes, turbulence in the ionized interstellar medium fundamentally limits the resolution of radio telescopes. We present a scattering mitigation framework for radio imaging with very long baseline interferometry (VLBI) that partially overcomes this limitation. Our framework, “stochastic optics,” derives from a simplification of strong interstellar scattering to separate small-scale (“diffractive”) effects from large-scale (“refractive”) effects, thereby separating deterministic and random contributions to the scattering. Stochastic optics extends traditional synthesis imaging by simultaneously reconstructing an unscattered image and its refractive perturbations. Its advantages over direct imaging come from utilizing the many deterministic properties of the scattering—such as the time-averaged “blurring,” polarization independence, and the deterministic evolution in frequency and time—while still accounting for the stochastic image distortions on large scales. These distortions are identified in the image reconstructions through regularization by their time-averaged power spectrum. Using synthetic data, we show that this framework effectively removes the blurring from diffractive scattering while reducing the spurious image features from refractive scattering. Stochastic optics can provide significant improvements over existing scattering mitigation strategies and is especially promising for imaging the Galactic Center supermassive black hole, Sagittarius A*, with the Global mm-VLBI Array and with the Event Horizon Telescope.

  18. STOCHASTIC OPTICS: A SCATTERING MITIGATION FRAMEWORK FOR RADIO INTERFEROMETRIC IMAGING

    Johnson, Michael D., E-mail: mjohnson@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-12-10

    Just as turbulence in the Earth’s atmosphere can severely limit the angular resolution of optical telescopes, turbulence in the ionized interstellar medium fundamentally limits the resolution of radio telescopes. We present a scattering mitigation framework for radio imaging with very long baseline interferometry (VLBI) that partially overcomes this limitation. Our framework, “stochastic optics,” derives from a simplification of strong interstellar scattering to separate small-scale (“diffractive”) effects from large-scale (“refractive”) effects, thereby separating deterministic and random contributions to the scattering. Stochastic optics extends traditional synthesis imaging by simultaneously reconstructing an unscattered image and its refractive perturbations. Its advantages over direct imaging come from utilizing the many deterministic properties of the scattering—such as the time-averaged “blurring,” polarization independence, and the deterministic evolution in frequency and time—while still accounting for the stochastic image distortions on large scales. These distortions are identified in the image reconstructions through regularization by their time-averaged power spectrum. Using synthetic data, we show that this framework effectively removes the blurring from diffractive scattering while reducing the spurious image features from refractive scattering. Stochastic optics can provide significant improvements over existing scattering mitigation strategies and is especially promising for imaging the Galactic Center supermassive black hole, Sagittarius A*, with the Global mm-VLBI Array and with the Event Horizon Telescope.

  19. High-temperature Brillouin scattering study of haplogranitic glasses and liquids: Effects of F, K, Na and Li on Tg and elastic properties

    Manghnani, M. H.; Hushur, A.; Williams, Q. C.; Dingwell, D. B.

    2010-12-01

    The density, compressibility and viscosity of silicate melts are important in understanding the thermodynamic and fluid dynamic properties of magmatic systems. Knowledge of the compressibility of silicate melts at 1 bar is an important component in the construction of accurate pressure-volume-temperature equations of state. In light of this, the velocity (nVp, Vp, Vs) and refractive index n of four anhydrous haplogranitic glasses and liquids with similar alkali abundances, but different cations, are measured at high temperature by Brillouin scattering spectroscopy through the glass transition temperature (Tg) in both platelet and back scattering geometry. The compositions of four haplogranites are 5 wt% of the components Li2O, Na2O, K2O and F each added to a base of haplogranitic (HPG8) composition. The glass transition temperature Tg of different haplogranite samples at the GHz frequency of the Brillouin probe are determined from the change in slope of the temperature-dependent longitudinal or transverse sound velocity. HPG8-Li5 has the lowest glass transition temperature (466°C), while HPG8-K5 has the highest glass transition temperature (575°C). Our Brillouin results, when compared with DSC measurements, show lower Tg values. This raises the possibility of a role of either heating rates or a frequency dependence of the glass transition in explaining the discrepancies in Tg values derived from the two methods. The sound velocity (nVp, Vp, Vs) shows markedly different temperature dependences (including differences in sign) below Tg depending on their different alkali contents. The unrelaxed elastic moduli of three haplogranitic glasses with added Li2O, Na2O and F components have been obtained as a function of temperature. The unrelaxed bulk modulus, shear modulus and Poisson’s ratio show strong compositional dependences at ambient temperature. On heating, The K initially decreases with increasing temperature up to ~ 135°C, then increases up to Tg, and then

  20. Intellectual Property Rights, Imitation, and Foreign Direct Investment: Theory and Evidence

    Lee Branstetter; Raymond Fisman; C. Fritz Foley; Kamal Saggi

    2007-01-01

    This paper theoretically and empirically analyzes the effect of strengthening intellectual property rights in developing countries on the level and composition of industrial development. We develop a North-South product cycle model in which Northern innovation, Southern imitation, and FDI are all endogenous. Our model predicts that IPR reform in the South leads to increased FDI in the North, as Northern firms shift production to Southern affiliates. This FDI accelerates Southern industrial de...

  1. Matching the optical properties of direct esthetic dental restorative materials to those of human enamel and dentin

    Ragain, James Carlton, Jr.

    One of the goals of the restorative dentist is to restore the appearance of the natural dentition. Clinical matching of teeth and restorative materials are seldom accurate and shade selection techniques are subjective. The first specific aim of this research was to characterize the optical absorption and scattering that occurs within enamel, dentin, and composite resin and compomer restorative materials and to relate those phenomena to translucency and color. The second aim was to evaluate small color differences among composite restorative materials which would be detectable by humans. The last aim was to lay the foundation for developing an improved model of specifying layers of dental restorative materials in order to match the translucency and color to those of human enamel. The Kubelka-Munk theory was validated for enamel, dentin, and the restorative materials. These tissues and materials were then characterized in terms of their color parameters. Tooth cores were also characterized in terms of color space parameters. Human subjects were evaluated for their abilities to discriminate small color differences in the dental composite resin materials. The following conclusions were derived from this study: (1) Kubelka-Munk theory accurately predicts the diffuse reflectance spectra of enamel, dentin, and the direct esthetic dental restorative materials studied. (2) Scattering and absorption coefficients of the dental tissues and esthetic restorative materials can be directly calculated from diffuse reflectance measurements of a uniformly thick slab of tissue/material using black and white backings and the appropriate refractive index. (3) For tooth cores, there is a positive correlation between L* and b* and a negative correlation between L* and a*. (4) The range of translucency parameters for the restorative materials studied does not match those of enamel and dentin. (5) None of the shades of the dental composite resin restorative materials studied fit into the

  2. Applications of neutron scattering to the study of magnetic materials

    Koehler, W.C.

    1976-01-01

    The types of interactions that neutrons undergo with condensed matter are reviewed and those properties of neutrons that make them an ideal probe for the study of magnetism on a microscopic scale are discussed. Following a very brief survey of experimental methods, a few illustrative examples of specific investigations are described in sufficient detail to illustrate the power of the techniques. Views as to the future directions that may be taken by neutron scattering are presented

  3. To Study Capping or Lamination Tendency of Tablets Through Evaluation of Powder Rheological Properties and Tablet Mechanical Properties of Directly Compressible Blends.

    Dudhat, Siddhi M; Kettler, Charles N; Dave, Rutesh H

    2017-05-01

    Air entrapment efficiency of the powders is one of the main factors leading to occurrence of capping or lamination tendency of tablets manufactured from the directly compressible powder blends. The purpose of the current research was to study this underlying cause leading to occurrence of capping or lamination of tablets through evaluation of powder rheological properties. Powder blends were prepared by addition of 0% w/w to 100% w/w of individual active pharmaceutical ingredient (API) [two model API: acetaminophen (APAP) and ibuprofen (IBU)] with microcrystalline cellulose without and with 0.5% w/w Magnesium Stearate as lubricant. Powder rheological properties were analyzed using FT4 Powder Rheometer for dynamic, bulk, and shear properties. Tablet mechanical properties of the respective blends were studied by determining the ability of the material to form tablet of specific strength under applied compaction pressure through tabletability profile. The results showed that powder rheometer distinguished the powder blends based on their ability to relieve entrapped air along with the distinctive flow characteristics. Powder blend prepared with increasing addition of APAP displayed low powder permeability as compared to IBU blends with better powder permeability, compressibility and flow characteristics. Also, lubrication of the APAP blends did not ease their ability to relieve air. Tabletability profiles revealed the potential occurrence of capping or lamination in tablets prepared from the powder blends with high APAP content. This study can help scientist to understand tableting performance at the early-developmental stages and can avoid occurrence capping and lamination of tablets.

  4. Elastic scattering

    Leader, Elliot

    1991-01-01

    With very few unexplained results to challenge conventional ideas, physicists have to look hard to search for gaps in understanding. An area of physics which offers a lot more than meets the eye is elastic and diffractive scattering where particles either 'bounce' off each other, emerging unscathed, or just graze past, emerging relatively unscathed. The 'Blois' workshops provide a regular focus for this unspectacular, but compelling physics, attracting highly motivated devotees

  5. Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu{sub 2}(Fe,Zn)SnS{sub 4}

    Fontane, X.; Izquierdo-Roca, V.; Saucedo, E. [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); Schorr, S. [Free University Berlin, Institute of Geological Sciences, Malteserstr. 74-100, Berlin (Germany); Yukhymchuk, V.O.; Valakh, M.Ya. [V.E. Lahskaryov Institute of Semiconductor Physics, National Academy of Sciences, Prospekt Nauki 41, Kiev 03028 (Ukraine); Perez-Rodriguez, A., E-mail: aperezr@irec.cat [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain); Morante, J.R. [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer Analysis of main and weaker Raman peaks from Cu{sub 2}FeZnS{sub 4} and Cu{sub 2}ZnSnS{sub 4} compounds. Black-Right-Pointing-Pointer Identification of a cation disorder induced Raman peak in Cu{sub 2}ZnSnS{sub 4}. Black-Right-Pointing-Pointer Analysis of spectral features of main Raman peaks from Cu{sub 2}(Fe,Zn)SnS{sub 4}. - Abstract: This work reports the analysis of the vibrational properties of stannite-kesterite Cu{sub 2}(Fe,Zn)SnS{sub 4} compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu{sub 2}FeSnS{sub 4} (CFTS) and kesterite Cu{sub 2}ZnSnS{sub 4} (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm{sup -1}. This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A{sub 1} peak with the chemical composition.

  6. Characterization of nanometer-thick polycrystalline silicon with phonon-boundary scattering enhanced thermoelectric properties and its application in infrared sensors.

    Zhou, Huchuan; Kropelnicki, Piotr; Lee, Chengkuo

    2015-01-14

    Although significantly reducing the thermal conductivity of silicon nanowires has been reported, it remains a challenge to integrate silicon nanowires with structure materials and electrodes in the complementary metal-oxide-semiconductor (CMOS) process. In this paper, we investigated the thermal conductivity of nanometer-thick polycrystalline silicon (poly-Si) theoretically and experimentally. By leveraging the phonon-boundary scattering, the thermal conductivity of 52 nm thick poly-Si was measured as low as around 12 W mK(-1) which is only about 10% of the value of bulk single crystalline silicon. The ZT of n-doped and p-doped 52 nm thick poly-Si was measured as 0.067 and 0.024, respectively, while most previously reported data had values of about 0.02 and 0.01 for a poly-Si layer with a thickness of 0.5 μm and above. Thermopile infrared sensors comprising 128 pairs of thermocouples made of either n-doped or p-doped nanometer-thick poly-Si strips in a series connected by an aluminium (Al) metal interconnect layer are fabricated using microelectromechanical system (MEMS) technology. The measured vacuum specific detectivity (D*) of the n-doped and p-doped thermopile infrared (IR) sensors are 3.00 × 10(8) and 1.83 × 10(8) cm Hz(1/2) W(-1) for sensors of 52 nm thick poly-Si, and 5.75 × 10(7) and 3.95 × 10(7) cm Hz(1/2) W(-1) for sensors of 300 nm thick poly-Si, respectively. The outstanding thermoelectric properties indicate our approach is promising for diverse applications using ultrathin poly-Si technology.

  7. Nuclear matter and electron scattering

    Sick, I [Dept. fuer Physik und Astronomie, Univ. Basel (Switzerland)

    1998-06-01

    We show that inclusive electron scattering at large momentum transfer allows a measurement of short-range properties of nuclear matter. This provides a very valuable constraint in selecting the calculations appropriate for predicting nuclear matter properties at the densities of astrophysical interest. (orig.)

  8. Scattering theory

    Friedrich, Harald

    2016-01-01

    This corrected and updated second edition of "Scattering Theory" presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is k...

  9. Direct visual evidence of end-on adsorption geometry of pyridine on silver surface investigated by surface enhanced Raman scattering and density functional theory calculations.

    Bhunia, Snehasis; Forster, Stefan; Vyas, Nidhi; Schmitt, Hans-Christian; Ojha, Animesh K

    2015-12-05

    Fourier transform Raman (FT-Raman) spectra of neat pyridine (Py) and surface enhanced Raman scattering (SERS) spectra of Py with silver nanoparticles (AgNPs) solution at different molar concentrations (X=1.5M, 1.0M, 0.50 M, 0.25 M, and 0.125 M) were recorded using 1064 nm excitation wavelength. The intensity of Raman bands at ∼1003 (ν11) and ∼1035 (ν21) cm(-1) of Py is enhanced in the SERS spectra. Two new Raman bands were observed at ∼1009 (ν12) and ∼1038 (ν22) cm(-1) in the SERS spectra. These bands correspond to the ring breathing vibrations of Py molecules adsorbed at the AgNPs surface. The value of intensity ratios (I12/I11) and (I21/I22) is increased with dilution and attains a maximum value at X=0.5M and upon further dilution (0.25 and 0.125 M) it drops gradually. The theoretically calculated Raman spectra were found to be in good agreement with experimentally observed Raman spectra. Both, experimental and theoretical investigations have confirmed that the Py interacts with AgNPs via the end-on geometry. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Comprehension of direct extraction of hydrophilic antioxidants using vegetable oils by polar paradox theory and small angle X-ray scattering analysis.

    Li, Ying; Fabiano-Tixier, Anne Sylvie; Ruiz, Karine; Rossignol Castera, Anne; Bauduin, Pierre; Diat, Olivier; Chemat, Farid

    2015-04-15

    Since the polar paradox theory rationalised the fact that polar antioxidants are more effective in nonpolar media, extractions of phenolic compounds in vegetable oils were inspired and achieved in this study for obtaining oils enriched in phenolic compounds. Moreover, the influence of surfactants on the extractability of phenolic compounds was experimentally studied first, followed by the small angle X-ray scattering analysis for the oil structural observation before and after extraction so as to better understand the dissolving mechanism underpinning the extraction. The results showed a significant difference on the extraction yield of phenolic compounds among oils, which was mainly dependent on their composition instead of the unsaturation of fatty acids. Appropriate surfactant additions could significantly improve extraction yield for refined sunflower oils, which 1% w/w addition of glyceryl oleate was determined as the optimal. Besides, 5% w/w addition of lecithin performed the best in oil enrichments compared with mono- and di-glycerides. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Microstructure and property of directionally solidified Ni-Si hypereutectic alloy

    Cui, Chunjuan; Tian, Lulu; Zhang, Jun; Yu, Shengnan; Liu, Lin; Fu, Hengzhi

    2016-03-01

    This paper investigates the influence of the solidification rate on the microstructure, solid/liquid interface, and micro-hardness of the directionally solidified Ni-Si hypereutectic alloy. Microstructure of the Ni-Si hypereutectic alloy is refined with the increase of the solidification rate. The Ni-Si hypereutectic composite is mainly composed of α-Ni matrix, Ni-Ni3Si eutectic phase, and metastable Ni31Si12 phase. The solid/liquid interface always keeps planar interface no matter how high the solidification rate is increased. This is proved by the calculation in terms of M-S interface stability criterion. Moreover, the Ni-Si hypereutectic composites present higher micro-hardness as compared with that of the pure Ni3Si compound. This is caused by the formation of the metastable Ni31Si12 phase and NiSi phase during the directional solidification process.

  12. Nonlinear Scattering of VLF Waves in the Radiation Belts

    Crabtree, Chris; Rudakov, Leonid; Ganguli, Guru; Mithaiwala, Manish

    2014-10-01

    Electromagnetic VLF waves, such as whistler mode waves, control the lifetime of trapped electrons in the radiation belts by pitch-angle scattering. Since the pitch-angle scattering rate is a strong function of the wave properties, a solid understanding of VLF wave sources and propagation in the magnetosphere is critical to accurately calculate electron lifetimes. Nonlinear scattering (Nonlinear Landau Damping) is a mechanism that can strongly alter VLF wave propagation [Ganguli et al. 2010], primarily by altering the direction of propagation, and has not been accounted for in previous models of radiation belt dynamics. Laboratory results have confirmed the dramatic change in propagation direction when the pump wave has sufficient amplitude to exceed the nonlinear threshold [Tejero et al. 2014]. Recent results show that the threshold for nonlinear scattering can often be met by naturally occurring VLF waves in the magnetosphere, with wave magnetic fields of the order of 50-100 pT inside the plasmapause. Nonlinear scattering can then dramatically alter the macroscopic dynamics of waves in the radiation belts leading to the formation of a long-lasting wave-cavity [Crabtree et al. 2012] and, when amplification is present, a multi-pass amplifier [Ganguli et al. 2012]. By considering these effects, the lifetimes of electrons can be dramatically reduced. This work is supported by the Naval Research Laboratory base program.

  13. Molecular dynamics simulations of Gay-Berne nematic liquid crystal: Elastic properties from direct correlation functions

    Stelzer, J.; Trebin, H.R.; Longa, L.

    1994-08-01

    We report NVT and NPT molecular dynamics simulations of a Gay-Berne nematic liquid crystal using generalization of recently proposed algorithm by Toxvaerd [Phys. Rev. E47, 343, 1993]. On the basis of these simulations the Oseen-Zoher-Frank elastic constants K 11 , K 22 and K 33 as well as the surface constants K 13 and K 24 have been calculated within the framework of the direct correlation function approach of Lipkin et al. [J. Chem. Phys. 82, 472 (1985)]. The angular coefficients of the direct pair correlation function, which enter the final formulas, have been determined from the computer simulation data for the pair correlation function of the nematic by combining the Ornstein-Zernike relation and the Wienier-Hopf factorization scheme. The unoriented nematic approximation has been assumed when constructing the reference, isotropic state of Lipkin et al. By an extensive study of the model over a wide range of temperatures, densities and pressures a very detailed information has been provided about elastic behaviour of the Gay-Berne nematic. Interestingly, it is found that the results for the surface elastic constants are qualitatively different than those obtained with the help of analytical approximations for the isotropic, direct pair correlation function. For example, the values of the surface elastic constants are negative and an order of magnitude smaller than the bulk elasticity. (author). 30 refs, 9 figs

  14. Markov chain Monte Carlo analysis to constrain dark matter properties with directional detection

    Billard, J.; Mayet, F.; Santos, D.

    2011-01-01

    Directional detection is a promising dark matter search strategy. Indeed, weakly interacting massive particle (WIMP)-induced recoils would present a direction dependence toward the Cygnus constellation, while background-induced recoils exhibit an isotropic distribution in the Galactic rest frame. Taking advantage of these characteristic features, and even in the presence of a sizeable background, it has recently been shown that data from forthcoming directional detectors could lead either to a competitive exclusion or to a conclusive discovery, depending on the value of the WIMP-nucleon cross section. However, it is possible to further exploit these upcoming data by using the strong dependence of the WIMP signal with: the WIMP mass and the local WIMP velocity distribution. Using a Markov chain Monte Carlo analysis of recoil events, we show for the first time the possibility to constrain the unknown WIMP parameters, both from particle physics (mass and cross section) and Galactic halo (velocity dispersion along the three axis), leading to an identification of non-baryonic dark matter.

  15. Numerical investigation of natural gas direct injection properties and mixture formation in a spark ignition engine

    Yadollahi Bijan

    2014-01-01

    Full Text Available In this study, a numerical model has been developed in AVL FIRE software to perform investigation of Direct Natural Gas Injection into the cylinder of Spark Ignition Internal Combustion Engines. In this regard two main parts have been taken into consideration, aiming to convert an MPFI gasoline engine to direct injection NG engine. In the first part of study multi-dimensional numerical simulation of transient injection process, mixing and flow field have been performed via three different validation cases in order to assure the numerical model validity of results. Adaption of such a modeling was found to be a challenging task because of required computational effort and numerical instabilities. In all cases present results were found to have excellent agreement with experimental and numerical results from literature. In the second part, using the moving mesh capability the validated model has been applied to methane Injection into the cylinder of a Direct Injection engine. Five different piston head shapes along with two injector types have been taken into consideration in investigations. A centrally mounted injector location has been adapted to all cases. The effects of injection parameters, combustion chamber geometry, injector type and engine RPM have been studied on mixing of air-fuel inside cylinder. Based on the results, suitable geometrical configuration for a NG DI Engine has been discussed.

  16. Got spirit? The spiritual climate scale, psychometric properties, benchmarking data and future directions.

    Doram, Keith; Chadwick, Whitney; Bokovoy, Joni; Profit, Jochen; Sexton, Janel D; Sexton, J Bryan

    2017-02-11

    Organizations that encourage the respectful expression of diverse spiritual views have higher productivity and performance, and support employees with greater organizational commitment and job satisfaction. Within healthcare, there is a paucity of studies which define or intervene on the spiritual needs of healthcare workers, or examine the effects of a pro-spirituality environment on teamwork and patient safety. Our objective was to describe a novel survey scale for evaluating spiritual climate in healthcare workers, evaluate its psychometric properties, provide benchmarking data from a large faith-based healthcare system, and investigate relationships between spiritual climate and other predictors of patient safety and job satisfaction. Cross-sectional survey study of US healthcare workers within a large, faith-based health system. Seven thousand nine hundred twenty three of 9199 eligible healthcare workers across 325 clinical areas within 16 hospitals completed our survey in 2009 (86% response rate). The spiritual climate scale exhibited good psychometric properties (internal consistency: Cronbach α = .863). On average 68% (SD 17.7) of respondents of a given clinical area expressed good spiritual climate, although assessments varied widely (14 to 100%). Spiritual climate correlated positively with teamwork climate (r = .434, p spiritual climate were less likely to have intentions to leave, to be burned out, or to experience disruptive behaviors in their unit and more likely to have participated in executive rounding (p spiritual climate scale exhibits good psychometric properties, elicits results that vary widely by clinical area, and aligns well with other culture constructs that have been found to correlate with clinical and organizational outcomes.

  17. Microstructure and properties of A15 superconductors formed by direct precipitation

    Hong, M.; Dietderich, D.R.; Wu, I.W.; Morris, J.W. Jr.

    1980-09-01

    Superconducting materials were made by quenching supersaturated solutions of V-Ga and Nb-Al, deforming the quenched specimens, and then precipitating the A15 phase by aging at intermediate temperature. The critical current characteristics of the product materials depend both on the inherent properties of the A15 phase, which presumably reflect its composition, and on the details of the precipitation process, which determine the grain size, continuity, and volume fraction of the A15. These features of the precipitation process differ qualitatively between V-Ga and Nb-Al. They are described and used to interpret the critical current characteristics

  18. Transverse Tensile Properties of 3 Dimension-4 Directional Braided Cf/SiC Composite Based on Double-Scale Model

    Niu, Xuming; Sun, Zhigang; Song, Yingdong

    2017-11-01

    In this thesis, a double-scale model for 3 Dimension-4 directional(3D-4d) braided C/SiC composites(CMCs) has been proposed to investigate mechanical properties of it. The double-scale model involves micro-scale which takes fiber/matrix/porosity in fibers tows into consideration and the unit cell scale which considers the 3D-4d braiding structure. Basing on the Micro-optical photographs of composite, we can build a parameterized finite element model that reflects structure of 3D-4d braided composites. The mechanical properties of fiber tows in transverse direction are studied by combining the crack band theory for matrix cracking and cohesive zone model for interface debonding. Transverse tensile process of 3D-4d CMCs can be simulated by introducing mechanical properties of fiber tows into finite element of 3D-4d braided CMCs. Quasi-static tensile tests of 3D-4d braided CMCs have been performed with PWS-100 test system. The predicted tensile stress-strain curve by the double scale model finds good agreement with the experimental results.

  19. Inelastic light scattering in crystals

    Sushchinskii, M. M.

    The papers presented in this volume are concerned with a variety of problems in optics and solid state physics, such as Raman scattering of light in crystals and disperse media, Rayleigh and inelastic scattering during phase transitions, characteristics of ferroelectrics in relation to the general soft mode concept, and inelastic spectral opalescence. A group-theory approach is used to classify the vibrational spectra of the crystal lattice and to analyze the properties of idealized crystal models. Particular attention is given to surface vibrational states and to the study of the surface layers of crystals and films by light scattering methods.

  20. Determination of structural changes of dispersed clay platelets in a polymer blend during solid-state rheological property measurement by small-angle X-ray scattering

    Bandyopadhyay, J

    2011-05-01

    Full Text Available -angle X-ray scattering studies showed that the degree of anisotropy and mean orientation angles of clay platelets in blend matrix were altered significantly after frequency and temperature sweep tests....