WorldWideScience

Sample records for beam size effects

  1. Transverse Beam Size Effects in Beam Position Monitors

    Science.gov (United States)

    Kurennoy, Sergey

    2001-04-01

    The fields produced by a long beam with a given transverse charge distribution in a homogeneous vacuum chamber are studied. Signals induced by the displaced finite-size beam on electrodes of a beam position monitor (BPM) are calculated and compared to those from a pencil beam. The corrections to BPM signals due to a finite beam size are found analytically for a few particular transverse distributions of the beam current. The results for fields can also be directly applied for calculating the beam coupling impedances of small discontinuities.

  2. Effects of Transverse Beam Size in Beam Position Monitors

    CERN Document Server

    Kurennoy, S S

    2001-01-01

    The fields produced by a long beam with a given transverse charge distribution in a homogeneous vacuum chamber are studied. Signals induced by a displaced finite-size beam on electrodes of a beam position monitor (BPM) are calculated and compared to those produced by a pencil beam. The non-linearities and corrections to BPM signals due to a finite transverse beam size are calculated for an arbitrary chamber cross section. Simple analytical expressions are given for a few particular transverse distributions of the beam current in a circular or rectangular chamber. Of particular interest is a general proof that in an arbitrary homogeneous chamber the beam-size corrections vanish for any axisymmetric beam current distribution.

  3. Effects of transverse beam size in beam position monitors.

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Sergey)

    2001-01-01

    The fields produced by a long beam with a given transverse charge distribution in a homogeneous vacuum chamber are studied. Signals induced by the displaced finite-size beam on electrodes of a beam position monitor (BPM) are calculated and compared to those from a pencil beam. The non-linearities and corrections to BPM signals due to a finite transverse beam size are calculated for an arbitrary chamber cross section. Simple analytical expressions are given for a few particular transverse distributions of the beam current in a circular or rectangular chamber. Of particular interest is a general proof that in an arbitrary homogeneous chamber the beam-size corrections vanish for any axisymmetric beam current distribution.

  4. EFFECTS OF TRANSFERSE BEAM SIZE IN BEAM POSITIONS MONITORS

    Energy Technology Data Exchange (ETDEWEB)

    S.S. KURENNOY

    2001-06-01

    The fields produced by a long beam with a given transverse charge distribution in a homogeneous vacuum chamber are studied. Signals induced by the displaced finite-size beam on electrodes of a beam position monitor (BPM) are calculated and compared to those from a pencil beam. The non-linearities and corrections to BPM signals due to a finite transverse beam size are calculated for an arbitrary chamber cross section. Simple analytical expressions are given for a few particular transverse distributions of the beam current in a circular or rectangular chamber. Of particular interest is a general proof that in an arbitrary homogeneous chamber the beam-size corrections vanish for any axisymmetric beam current distribution.

  5. Beam-size or MD-effect at colliders and correlations of particles in a beam

    CERN Document Server

    Kotkin, G L

    2003-01-01

    For several processes at colliding beams, macroscopically large impact parameters give an essential contribution to the standard cross section. These impact parameters may be much larger than the transverse sizes of the colliding bunches. In that case, the standard calculations have to be essentially modify. The corresponding formulae for such a beam-size effect were given twenty years ago without taking into account correlations of particle coordinates in the beams. In the present paper we derive formulae which necessary to take into account quantitatively the effect of particle correlations in the spectrum of bremsstrahlung as well as in pair production. Besides, we consider critically recent papers of Baier and Katkov [Phys. Rev. D {\\bf 66}, 053009 (2002) and hep-ph/0305304] in which it was calculated a new additional ``subtraction term'' related to the coherent contribution into beam-size effect. We show that this result is groundless and point out the origin of the mistake.

  6. Physical mechanism of the linear beam-size effect at colliders

    Energy Technology Data Exchange (ETDEWEB)

    Melnikov, K. [Institut fuer Physik, THEP, Johannes Gutenberg Universitaet, Staudinger weg 7, D 55099 Mainz (Germany); Kotkin, G.L.; Serbo, V.G. [Novosibirsk State University, 630090, Novosibirsk (Russia)

    1996-09-01

    We present a qualitative but precise description of the linear beam-size effect predicted for the processes in which unstable but long-living particles collide with each other. We derive a physically pronounced equation for the event rate which proves that the linear beam-size effect corresponds to the scattering of one beam of particles on the decay products of the other. We compare this linear beam-size effect with the known logarithmic beam-size effect measured in the experiments on a single bremsstrahlung at Novosibirsk{close_quote}s VEPP-4 and DESY HERA. {copyright} {ital 1996 The American Physical Society.}

  7. Physical mechanism of the linear beam-size effect at colliders

    CERN Document Server

    Melnikov, K; Serbo, V G

    1996-01-01

    We present qualitative but precise description of the linear beam-size effect predicted for the processes in which unstable but long--living particles collide with each other. We derive physically pronounced equation for the events rate which proves that the linear beam-size effect corresponds to the scattering of one beam of particles on the decay products of the other. We compare this linear beam-size effect with the known logarithmic beam-size effect measured in the experiments on a single bremsstrahlung at VEPP-4 and HERA.

  8. Nonlinearities and effects of transverse beam size in beam position monitors

    Science.gov (United States)

    Kurennoy, Sergey S.

    2001-09-01

    The fields produced by a long beam with a given transverse charge distribution in a homogeneous vacuum chamber are studied. Signals induced by a displaced finite-size beam on electrodes of a beam position monitor (BPM) are calculated and compared to those produced by a pencil beam. The nonlinearities and corrections to BPM signals due to a finite transverse beam size are calculated for an arbitrary chamber cross section. Simple analytical expressions are given for a few particular transverse distributions of the beam current in a circular or rectangular chamber. Of particular interest is a general proof that in an arbitrary homogeneous chamber the beam-size corrections vanish for any axisymmetric beam current distribution.

  9. The effect of laser beam size in a zig-zag collimator on transverse cooling of a krypton atomic beam

    Indian Academy of Sciences (India)

    Vivek Singh; V B Tiwari; S Singh; S R Mishra; H S Rawat

    2014-07-01

    The effect of size of a cooling laser beam in a zig-zag atomic beam collimator on transverse cooling of a krypton atomic beam is investigated. The simulation results show that discreteness in the interaction between the cooling laser beam and atomic beam, arising due to finite size and incidence angle of the cooling laser beam, significantly reduces the value of transverse velocity capture range of the collimator. The experimental observations show the trend similar to that obtained from simulations. Our study can be particularly useful where a small zig-zag collimator is required.

  10. Dosimetric effects of beam size and collimation of epithermal neutrons for boron neutron capture therapy.

    Science.gov (United States)

    Yanch, J C; Harling, O K

    1993-08-01

    A series of studies of "ideal" beams has been carried out using Monte Carlo simulation with the goal of providing guidance for the design of epithermal beams for boron neutron capture therapy (BNCT). An "ideal" beam is defined as a monoenergetic, photon-free source of neutrons with user-specified size, shape and angular dependence of neutron current. The dosimetric behavior of monoenergetic neutron beams in an elliptical phantom composed of brain-equivalent material has been assessed as a function of beam diameter and neutron emission angle (beam angle), and the results are reported here. The simulation study indicates that substantial differences exist in the dosimetric behavior of small and large neutron beams (with respect to the phantom) as a function of the extent of beam collimation. With a small beam, dose uniformity increases as the beam becomes more isotropic (less collimated); the opposite is seen with large beams. The penetration of thermal neutrons is enhanced as the neutron emission angle is increased with a small beam; again the opposite trend is seen with large beams. When beam size is small, the dose delivered per neutron is very dependent on the extent of beam collimation; this does not appear to be the case with a larger beam. These trends in dose behavior are presented graphically and discussed in terms of their effect on several figures of merit, the advantage depth, the advantage ratio, and the advantage depth-dose rate. Tables giving quick summaries of these results are provided.

  11. Size Effect Of Glulam Beams In Tension Perpendicular To Grain

    DEFF Research Database (Denmark)

    Astrup, Thomas; Odin Clorius, Christian; Damkilde, Lars;

    2007-01-01

    The strength of wood is reduced when the stressed volume is increased. The phenomenon is termed size effect and is often explained as being stochastic in the sense that the probability of weak locations occurring in the wood increases with increased volume. This paper presents the hypothesis...... that the lower strength is caused by stress concentrations. The stress concentrations arise from the anisotropic structure of wood, and are therefore deterministic. The hypothesis is substantiated through extensive FEM-calculations and experiments. A reasonable agreement between ultimate stresses determined...

  12. Size effect of glulam beams in tension perpendicular to grain

    DEFF Research Database (Denmark)

    Astrup, Thomas; Clorius, Christian Odin; Damkilde, Lars;

    2007-01-01

    that the lower strength is caused by stress concentrations. The stress concentrations arise from the anisotropic structure of wood, and are therefore deterministic. The hypothesis is substantiated through extensive FEM-calculations and experiments. A reasonable agreement between ultimate stresses determined......The strength of wood is reduced when the stressed volume is increased. The phenomenon is termed size effect and is often explained as being stochastic in the sense that the probability of weak locations occurring in the wood increases with increased volume. This paper presents the hypothesis...

  13. Effects of transverse electron beam size on transition radiation angular distribution

    Energy Technology Data Exchange (ETDEWEB)

    Chiadroni, E., E-mail: enrica.chiadroni@lnf.infn.it [Laboratori Nazionali di Frascati-INFN, via E. Fermi, 40, 00044 Frascati (Italy); Castellano, M. [Laboratori Nazionali di Frascati-INFN, via E. Fermi, 40, 00044 Frascati (Italy); Cianchi, A. [University of Rome ' Tor Vergata' and INFN-Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Honkavaara, K.; Kube, G. [Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607 Hamburg (Germany)

    2012-05-01

    In this paper we consider the effect of the transverse electron beam size on the Optical Transition Radiation (OTR) angular distribution in case of both incoherent and coherent emission. Our results confute the theoretical argumentations presented first in Optics Communications 211, 109 (2002), which predicts a dependence of the incoherent OTR angular distribution on the beam size and emission wavelength. We present here theoretical and experimental data not only to validate the well-established Ginzburg-Frank theory, but also to show the impact of the transverse beam size in case of coherent emission.

  14. Effects of Beam Size and Pulse Duration on the Laser Drilling Process

    CERN Document Server

    Afrin, Nazia; Chen, J K; Zhang, Yuwen

    2016-01-01

    A two-dimensional axisymmetric transient laser drilling model is used to analyze the effects of laser beam diameter and laser pulse duration on the laser drilling process. The model includes conduction and convection heat transfer, melting, solidification and vaporization, as well as material removal resulting from the vaporization and melt ejection. The validated model is applied to study the effects of laser beam size and pulse duration on the geometry of the drilled hole. It is found that the ablation effect decrease with the increasing beam diameter due to the effect of increased vaporization rate, and deeper hole is observed for the larger pulse width due to the higher thermal ablation efficiency.

  15. Once Again about Beam-Size or MD-Effect at Colliding Beams

    CERN Document Server

    Kotkin, G L

    2002-01-01

    For several processes at colliding beams, macroscopically large impact parameters give an essential contribution to the standard cross section. These impact parameters may be much larger than the transverse sizes of the colliding bunches. In that case, the standard calculations have to be essentially modify. The corresponding formulae were given twenty years ago. In recent paper of Baier and Katkov [17] it was claimed that the previous results about bremsstrahlung spectrum have to be revised and an additional subtraction related to the coherent contribution has to be done. This additional term has been calculated with the result that it may be essential for the performed and future experiments. In the present paper we analyze in detail the coherent and incoherent contributions in the conditions, considered in paper [17]. In contract to above claims, we found out that under these conditions the coherent contribution is completely negligible and, therefore, there is no need to revise the previous results.

  16. Beam-size effect and particle losses at Super$B$ factory developed in Italy

    CERN Document Server

    Kotkin, G L

    2009-01-01

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the $e^+ e^- \\to e^+ e^- \\gamma$ process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at Super$B$ factory developed in Italy. We find out that this effect reduces beam losses due to bremsstrahlung by about 40%.

  17. Beam-size effect and particle losses at B-factories KEKB and PEP-II

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L.; Serbo, V.G. E-mail: serbo@math.nsc.ru

    2005-01-01

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the e{sup +}e{sup -}{yields}e{sup +}e{sup -}{gamma} process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at B-factories KEKB and PEP-II. We find out that this effect reduces beam losses due to bremsstrahlung by about 20%.

  18. Cell size effects for vibration analysis and design of sandwich beams

    Institute of Scientific and Technical Information of China (English)

    Gaoming Dai; Weihong Zhang

    2009-01-01

    In this work, sandwich beams are studied to reveal the underlying size effects of the periodic core cells for the first time within the framework of free vibration analysis of such an advanced lightweight structure. The energy equiv-alence method is formulated as a theoretical approach that takes into account the cell size effect. It is compared with the asymptotic homogenization method and direct finite element method systematically to show their consistence and appli-cability. The accuracy of free vibration responses predicted by the detailed finite element model is used as the standard of comparison. It is shown that the cell size is an important parameter characterizing the cellular core rigidities that influ-ence vibration responses. The homogenization model agrees exactly with the asymptotic solution of the analytical expres-sion of the beam model only whenever the cell size tends to be infinitely small.

  19. Beam-size effect and particle losses at SuperB factory developed in Italy

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G L; Serbo, V G [Novosibirsk State University, 630090, Novosibirsk, Pirogova st., 2 (Russian Federation)], E-mail: serbo@math.nsc.ru

    2009-06-15

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the e{sup +}e{sup -}{yields} e{sup +}e{sup -}{gamma} process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at SuperB factory developed in Italy. We find out that this effect reduces beam losses due to bremsstrahlung by about 40%. We perform a critical comparison of our result with that presented in the Conceptual Design Report of the Italian SuperB factory.

  20. Effects of ion beam irradiation on size of mutant sector and genetic damage in Arabidopsis

    Science.gov (United States)

    Hase, Yoshihiro; Nozawa, Shigeki; Narumi, Issay; Oono, Yutaka

    2017-01-01

    Size of mutant sector and genetic damage were evaluated in Arabidopsis to further our understanding of effective ion beam use in plant mutation breeding. Arabidopsis seeds, heterozygous for the GLABRA1 (GL1) gene (GL1/gl1-1), were irradiated with 15.8 MeV/u neon ions (mean linear energy transfer (LET): 352 keV/μm), 17.3 MeV/u carbon ions (113 keV/μm), or 60Co gamma rays. The frequency and size of glabrous sectors generated because of inactivation of the GL1 allele were examined. The frequency and overall size of large deletions were evaluated based on the loss of heterozygosity of DNA markers using DNA isolated from glabrous tissue. Irrespective of the radiation properties, plants with mutant sectors were obtained at similar frequencies at the same effective dosage necessary for survival reduction. Ion beams tended to induce larger mutant sectors than gamma rays. The frequency of large deletions (>several kbp) increased as the LET value increased, with chromosome regions larger than 100 kbp lost in most large deletions. The distorted segregation ratio of glabrous plants in the progenies of irradiated GL1/gl1-1 plants suggested frequent occurrence of chromosome rearrangement, especially those subjected to neon ions. Exposure to ion beams with moderate LET values (30-110 keV/μm) is thought effective for inducing mutant sectors without causing extensive genetic damage.

  1. Magnetic field effects on buckling behavior of smart size-dependent graded nanoscale beams

    Science.gov (United States)

    Ebrahimi, Farzad; Reza Barati, Mohammad

    2016-07-01

    In this article, buckling behavior of nonlocal magneto-electro-elastic functionally graded (MEE-FG) beams is investigated based on a higher-order beam model. Material properties of smart nanobeam are supposed to change continuously throughout the thickness based on the power-law model. Eringen's nonlocal elasticity theory is adopted to capture the small size effects. Nonlocal governing equations of MEE-FG nanobeam are obtained employing Hamilton's principle and they are solved using the Navier solution. Numerical results are presented to indicate the effects of magnetic potential, electric voltage, nonlocal parameter and material composition on buckling behavior of MEE-FG nanobeams. Therefore, the present study makes the first attempt in analyzing the buckling responses of higher-order shear deformable (HOSD) MEE-FG nanobeams.

  2. Effect of Photon Beam Energy, Gold Nanoparticle Size and Concentration on the Dose Enhancement in Radiation Therapy

    Directory of Open Access Journals (Sweden)

    Nahideh Gharehaghaji

    2013-02-01

    Full Text Available Introduction: Gold nanoparticles have been used as radiation dose enhancing materials in recent investigations. In the current study, dose enhancement effect of gold nanoparticles on tumor cells was evaluated using Monte Carlo (MC simulation. Methods: We used MCNPX code for MC modeling in the current study. A water phantom and a tumor region with a size of 1×1×1 cm3 loaded with gold nanoparticles were simulated. The macroscopic dose enhancement factor was calculated for gold nanoparticles with sizes of 30, 50, and 100 nm. Also, we simulated different photon beams including mono-energetic beams (50-120 keV, a Cobalt-60 beam, 6 & 18 MV photon beams of a conventional linear accelerator. Results: We found a dose enhancement factor (DEF of from 1.4 to 3.7 for monoenergetic kilovoltage beams, while the DEFs for megavoltage beams were negligible and less than 3% for all GNP sizes and concentrations. The optimum energy for higher DEF was found to be the 90 keV monoenergetic beam. The effect of GNP size was not considerable, but the GNP concentration had a substantial impact on achieved DEF in GNP-based radiation therapy. Conclusion: The results were in close agreement with some previous studies considering the effect of photon energy and GNP concentration on observed DEF. Application of GNP-based radiation therapy using kilovoltage beams is recommended.

  3. EFFECT OF PARTICLE SIZE AND PACKING RATIO OF PID ON VIBRATION AMPLITUDE OF BEAM

    Directory of Open Access Journals (Sweden)

    P.S. Kachare

    2013-06-01

    Full Text Available Everything in the universe that has mass possesses stiffness and intrinsic damping. Owing to the stiffness property, mass will vibrate when excited and its intrinsic damping property will act to stop the vibration. The particle impact damper (PID is a very interesting damper that affects impact and friction effects of particles by means of energy dissipation. PID is a means for achieving high structural damping by using a particle-filled enclosure attached to a structure. The particles absorb the kinetic energy of the structure and convert it into heat through inelastic collisions between the particles themselves and between the particles and the walls of the enclosure. In this work, PID is measured for a cantilever mild steel beam with an enclosure attached to its free end; copper particles are used in this study. The PID is found to be highly nonlinear. The most useful observation is that for a very small weight penalty (about 7% to 8 %, the maximum damped amplitude of vibration at resonance with a PID, is about 9 to 10 times smaller than that without a PID. It is for more than that of with only intrinsic material damping of a majority of structural metals. A satisfactory comparison of damping with and without particles through experimentation is observed. The effect of the size of the particles on the damping performance of the beam and the effective packing ratio can be identified. It is also shown that as the packing ratio changes, the contributions of the phenomena of impact and friction towards damping also change. It is encouraging that despite its deceptive simplicity, the model captures the essential physics of PID.

  4. Effects of mirror distortion by thermal deformation in an interferometry beam size monitor system at PLS-II

    Science.gov (United States)

    Hwang, Ji-Gwang; Kim, Eun-San; Kim, Changbum; Huang, Jung-Yun; Kim, Dotae

    2016-10-01

    Extraction mirrors installed at the most upstream position of interferometry beam size monitor are frequently used for measuring the beam size in storage rings. These mirrors receive the high power synchrotron radiation and are distorted owing to the heat distribution that depends on the position on the mirror surface. The distortion of the mirror changes the effective separation of the slit in the interferometry beam size monitor. Estimation of the effects of the front-end mirror distortion is important for measuring the beam size accurately. In this paper, we present the result of the numerical simulation of the temperature distribution and thermal expansion of the front-end mirror using ANSYS code, the theoretical basis of the effects of mirror distortion and compare with experimental results from Pohang Light Source II (PLS-II) at the Pohang Accelerator Laboratory (PAL). The equipment in the beam diagnosis line in PLS-II and experimental set-up for measuring the distortion of the front-end mirror using a multi-hole square array Hartmann screen are described.

  5. Modeling the Effects of Beam Size and Flaw Morphology on Ultrasonic Pulse/Echo Sizing of Delaminations in Carbon Composites

    Science.gov (United States)

    Margetan, Frank J.; Leckey, Cara A.; Barnard, Dan

    2012-01-01

    The size and shape of a delamination in a multi-layered structure can be estimated in various ways from an ultrasonic pulse/echo image. For example the -6dB contours of measured response provide one simple estimate of the boundary. More sophisticated approaches can be imagined where one adjusts the proposed boundary to bring measured and predicted UT images into optimal agreement. Such approaches require suitable models of the inspection process. In this paper we explore issues pertaining to model-based size estimation for delaminations in carbon fiber reinforced laminates. In particular we consider the influence on sizing when the delamination is non-planar or partially transmitting in certain regions. Two models for predicting broadband sonic time-domain responses are considered: (1) a fast "simple" model using paraxial beam expansions and Kirchhoff and phase-screen approximations; and (2) the more exact (but computationally intensive) 3D elastodynamic finite integration technique (EFIT). Model-to-model and model-to experiment comparisons are made for delaminations in uniaxial composite plates, and the simple model is then used to critique the -6dB rule for delamination sizing.

  6. Influence of the beam-size effect on particle losses at B-factories PEP-II and KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L.; Serbo, V.G. E-mail: serbo@math.nsc.ru

    2004-01-21

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross-section of the e{sup +}e{sup -}{yields}e{sup +}e{sup -}{gamma} process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross-section of this process has to be substantially modified. In the present paper such a beam-size is calculated for bremsstrahlung at B-factories PEP-II and KEKB. We find out that this effect reduces beam losses due to bremsstrahlung by about 20%.

  7. The effect of voxel size on the measurement of mandibular thickness in cone-beam computed tomography

    Directory of Open Access Journals (Sweden)

    Ehsan Hekmatian

    2014-01-01

    Full Text Available Background: Cone-beam computed tomography (CBCT is a new imaging technology that has been widely used in implantology, oral and maxillofacial surgery and orthodontics. This method provides 3-D images that are composed of voxel, which is the smallest image unit, and determines image resolution. Smaller voxel is associated with the higher resolution and also greater radiation exposure. This study was aimed to find out the effect of voxel size on the measurement of mandibular thickness. Materials and Methods: Using voxel sizes of 0.30 mm and 0.15 mm, two CBCT protocols (protocol 1: Field of view (FOV of 15 cm, 85 kVp, 42 mAs, 0.15 mm voxel, 14 s scan time; protocol 2: FOV of 15 cm, 85 kVp, 10 mAs, 0.30 mm voxel, 14 s scan time were carried out on 16 dry human mandibles with permanent dentition. Mandibular thickness was measured at seven different sites (midline region, bilateral canine regions, bilateral mental foramen regions and bilateral molar regions. Analysis of variance was used for analysis of data using the Statistical Package for the Social Sciences version 20 (SPSS Inc., Chicago, IL, USA. P 0.05. Conclusion: Considering the insignificant differences of the mandibular thickness measurements using different voxel sizes, it would be more reasonable to use 0.30 mm voxel size instead of 0.15 mm voxel size to avoid unnecessary radiation exposure.

  8. Influence of the beam-size or MD-effect on particle losses at B-factories PEP-II and KEKB

    CERN Document Server

    Kotkin, G L

    2004-01-01

    For the $e^+ e^- \\to e^+ e^- \\gamma$ process at colliding beams, macroscopically large impact parameters give an essential contribution to the standard cross section. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard calculations have to be essentially modify. In the present paper such a beam-size or MD-effect is calculated for bremsstrahlung at B-factories PEP-II and KEKB using the list of nominal parameters from Review of Particle Physics (2002). We find out that this effect reduces beam losses due to bremsstrahlung by about 20%.

  9. Shaping micron-sized cold neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Ott, Frédéric, E-mail: Frederic.Ott@cea.fr [CEA, IRAMIS, Laboratoire Léon Brillouin, Gif-sur-Yvette F-91191 (France); CNRS, IRAMIS, Laboratoire Léon Brillouin, Gif-sur-Yvette F-91191 (France); Kozhevnikov, Sergey [Joint Institute for Nuclear Research, ul. Joliot-Curie 6, Dubna, Moscow oblast 141980 (Russian Federation); Thiaville, André [Laboratoire de Physique des Solides, Univ. Paris—Sud, CNRS UMR 8502, 91405 Orsay (France); Torrejón, Jacob [Unité Mixte de Physique, CNRS/Thales, Campus de l’Ecole Polytechnique, 91767 Palaiseau (France); Vázquez, Manuel [Instituto de Ciencia de Materiales, CSIC, 28049 Madrid (Spain)

    2015-07-11

    In the field of neutron scattering, the need for micro-sized (1–50 µm) thermal or cold neutron beams has recently appeared, typically in the field of neutron imaging to probe samples with a high spatial resolution. We discuss various possibilities of producing such micro-sized neutron beams. The advantages and drawbacks of the different techniques are discussed. We show that reflective optics offers the most flexible way of producing tiny neutron beams together with an enhanced signal to background ratio. The use of such micro beams is illustrated by the study of micrometric diameter magnetic wires.

  10. Evaluation of size effect on shear strength of reinforced concrete deep beams using refined strut-and-tie model

    Indian Academy of Sciences (India)

    G Appa Rao; R Sundaresan

    2012-02-01

    This paper reports on development of size-dependent shear strength expression for reinforced concrete deep beams using refined strut-and-tie model. The generic form of the size effect law has been retained considering the merits of Siao’s model and modified Bazant’s size effect law using the large experimental data base reported in the literature. The proposed equation for predicting the shear strength of deep beams incorporates the compressive strength of concrete, ratios of the longitudinal and the web reinforcement, shear span-to-depth ratio and the effective depth.

  11. Position and size of the electron beam in the high-energy electron beam ion trap

    CERN Document Server

    Utter, S B; López-Urrutia, J R C; Widmann, K

    1999-01-01

    In the last decade, many spectroscopic studies have been performed using the electron beam ion trap. Often these measurements rely on the electron beam as an effective slit, yet until now, no systematic study of the position and size of the electron beam under various operating conditions has been made. Here, we present a thorough study of the electron beam's position and size (and thus the electron density) as affected by various operating parameters, and give optimal parameter ranges for operating the device as a spectroscopic source. It is shown that the diameter is constant as the energy is varied, which is important for accurate cross-section measurements.

  12. Evaluation of the effect of reconstructed image pixel size on defect detectability in Tl-201 fan-beam SPECT by an observer performance study

    Energy Technology Data Exchange (ETDEWEB)

    Gregoriou, G.K.; Tsui, B.M.W. [Univ. of North Carolina, Chapel Hill, NC (United States); Gullberg, G.T. [Univ. of Utah, Salt Lake City, UT (United States)

    1995-08-01

    The effect of reconstructed image pixel size in the fan-beam filtered backprojection method in myocardial defect detection was investigated using an observer performance study and receiver operating characteristics (ROC) analysis. A mathematical phantom of the human torso was used to model the anatomy and Thallium-201 (TI-201) uptake in humans. Realistic projections from the phantom were simulated using a low-energy high resolution fan-beam collimator that incorporated the effects of photon attenuation, spatially varying detector response, scatter, and Poison noise. For a fan beam collimator with a focal length of 55 cm and with a radius of rotation of 25 cm, the magnification at the center of rotation was two and the maximum magnification in the reconstructed region of interest was three. Myocardial defects were simulated as Gaussian-shaped decreases in Tl-201 uptake distribution. By changing the reconstructed image pixel size, five different classes of reconstructed images resulted, with projection bin width to reconstructed image pixel size (PBIP) ratios of 1, 2, 3, 4, and 5. The results from the observer study indicate that the reconstructed image pixel size has a significant effect on myocardial defect detection in reconstructed Tl-201 SPECT images. Moreover, the study indicated that in order to ensure maximum defect delectability the PBIP ratio should be at least as large as the maximum possible magnification within the reconstructed image array.

  13. Effect of wedge filter and field size on photoneutron dose equivalent for an 18 MV photon beam of a medical linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Mesbahi, Asghar [Medical Physics Department, Medical School, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Radiation Therapy Department, Imam Hospital, Tabriz (Iran, Islamic Republic of)], E-mail: asgharmesbahi@yahoo.com; Keshtkar, Ahmad [Medical Physics Department, Medical School, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Mohammadi, Ehsan [Radiation Therapy Department, Imam Khomeini Hospital, Tehran (Iran, Islamic Republic of); Mohammadzadeh, Mohammad [Radiation Therapy Department, Imam Hospital, Tabriz (Iran, Islamic Republic of)

    2010-01-15

    Photoneutrons produced during radiation therapy with high energy photons is the main source of unwanted out-of-field received doses of patients. To analyze the neutron dose equivalent (NDE) for wedged beams and its variation with field size, Monte Carlo (MC) modeling of an 18 MV photon beam was performed using MCNPX MC code. The results revealed that the NDE is on average 6.5 times higher for wedged beams. For open beams, the NDE decreased with increasing field size especially for field sizes >20x20 cm{sup 2}. While, for wedged beams, the NDE increased with field size. It was suggested that the increase of NDE for wedged beams should be taken into account in radiation-induced secondary cancer risk estimations and radiation protection calculations.

  14. Theory of Nanocluster Size Distributions from Ion Beam Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, C.W.; Yi, D.O.; Sharp, I.D.; Shin, S.J.; Liao, C.Y.; Guzman, J.; Ager III, J.W.; Haller, E.E.; Chrzan, D.C.

    2008-06-13

    Ion beam synthesis of nanoclusters is studied via both kinetic Monte Carlo simulations and the self-consistent mean-field solution to a set of coupled rate equations. Both approaches predict the existence of a steady state shape for the cluster size distribution that depends only on a characteristic length determined by the ratio of the effective diffusion coefficient to the ion flux. The average cluster size in the steady state regime is determined by the implanted species/matrix interface energy.

  15. On Effect Size

    Science.gov (United States)

    Kelley, Ken; Preacher, Kristopher J.

    2012-01-01

    The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension,…

  16. Evaluation of size dependent design shear strength of reinforced concrete beams without web reinforcement

    Indian Academy of Sciences (India)

    G Appa Rao; S S Injaganeri

    2011-06-01

    Analytical studies on the effect of depth of beam and several parameters on the shear strength of reinforced concrete beams are reported. A large data base available has been segregated and a nonlinear regression analysis (NLRA) has been performed for developing the refined design models for both, the cracking and the ultimate shear strengths of reinforced concrete (RC) beams without web reinforcement. The shear strength of RC beams is size dependent, which needs to be evaluated and incorporated in the appropriate size effect models. The proposed models are functions of compressive strength of concrete, percentage of flexural reinforcement and depth of beam. The structural brittleness of large size beams seems to be severe compared with highly ductile small size beams at a given quantity of flexural reinforcement. The proposed models have been validated with the existing popular models as well as with the design code provisions.

  17. Sensitivity studies of beam directionality, beam size, and neutron spectrum for a fission converter-based epithermal neutron beam for boron neutron capture therapy.

    Science.gov (United States)

    Sakamoto, S; Kiger, W S; Harling, O K

    1999-09-01

    Sensitivity studies of epithermal neutron beam performance in boron neutron capture therapy are presented for realistic neutron beams with varying filter/moderator and collimator/delimiter designs to examine the relative importance of neutron beam spectrum, directionality, and size. Figures of merit for in-air and in-phantom beam performance are calculated via the Monte Carlo technique for different well-optimized designs of a fission converter-based epithermal neutron beam with head phantoms as the irradiation target. It is shown that increasing J/phi, a measure of beam directionality, does not always lead to corresponding monotonic improvements in beam performance. Due to the relatively low significance, for most configurations, of its effect on in-phantom performance and the large intensity losses required to produce beams with very high J/phi, beam directionality should not be considered an important figure of merit in epithermal neutron beam design except in terms of its consequences on patient positioning and collateral dose. Hardening the epithermal beam spectrum, while maintaining the specific fast neutron dose well below the inherent hydrogen capture dose, improves beam penetration and advantage depth and, as a desirable by-product, significantly increases beam intensity. Beam figures of merit are shown to be strongly dependent on beam size relative to target size. Beam designs with J/phi approximately 0.65-0.7, specific fast neutron doses of 2-2.6x10(-13) Gy cm2/n and beam sizes equal to or larger than the size of the head target produced the deepest useful penetration, highest therapeutic ratios, and highest intensities.

  18. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Science.gov (United States)

    Yani, Sitti; Dirgayussa, I. Gde E.; Rhani, Moh. Fadhillah; Haryanto, Freddy; Arif, Idam

    2015-09-01

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm3, 1 × 1 × 0.5 cm3, and 1 × 1 × 0.8 cm3. The 1 × 109 histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in dmax from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm3 about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm3 about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  19. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yani, Sitti, E-mail: sitti.yani@s.itb.ac.id [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Akademi Kebidanan Pelita Ibu, Kendari (Indonesia); Dirgayussa, I Gde E.; Haryanto, Freddy; Arif, Idam [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Rhani, Moh. Fadhillah [Tan Tock Seng Hospital (Singapore)

    2015-09-30

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm{sup 3}, 1 × 1 × 0.5 cm{sup 3}, and 1 × 1 × 0.8 cm{sup 3}. The 1 × 10{sup 9} histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in d{sub max} from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm{sup 3} about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm{sup 3} about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  20. Stabilization of electron beam spot size by self bias potential

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, T.J.T.; Moir, D.C.; Snell, C.M.; Kang, M.

    1998-12-31

    In high resolution flash x-ray imaging technology the electric field developed between the electron beam and the converter target is large enough to draw ions from the target surface. The ions provide fractional neutralization and cause the electron beam to focus radially inward, and the focal point subsequently moves upstream due to the expansion of the ion column. A self-bias target concept is proposed and verified via computer simulation that the electron charge deposited on the target can generate an electric potential, which can effectively limit the ion motion and thereby stabilize the growth of the spot size. A target chamber using the self bias target concept was designed and tested in the Integrated Test Stand (ITS). The authors have obtained good agreement between computer simulation and experiment.

  1. Interferometric measurement of the beam size in the compact storage ring

    CERN Document Server

    Yamamoto, Y; Mitsuhashi, T; Amano, D; Iwasaki, H

    2001-01-01

    The beam size in the compact superconducting storage ring AURORA at Ritsumeikan University was measured using the SR-interferometer. The radiation beam from the bending magnet was passed through the double-slit and an interferogram formed in the visible spectral region was recorded using a CCD camera. The spatial coherence of the beam was derived from the analysis of the intensity profile and its dependence on the spatial frequency has yielded the beam size of 10.5 mu m in the vertical direction. It is unexpectedly small, indicating a high accuracy in the design of magnetic field in the magnet. The beam size could be varied by applying an rf kick electric field and the dependence of the beam lifetime on the size has shown that it is primarily governed by the Tauschek effect.

  2. Uniform, variable size rectangle beam scanning. Application to hadrontherapy

    Energy Technology Data Exchange (ETDEWEB)

    Meot, F. [DAPNIA and IN2P3, LPSC, F-38026 Grenoble (France)]. E-mail: meot@lpsc.in2p3.fr

    2006-08-01

    A beam optics method is described, which allows the dynamical adjustment of the transverse size of a sweeping particle beam with rectangular, uniform cross-section. This technique can find applications in the domain of hadrontherapy where it introduces various advantages compared to the existing methods of active or passive irradiation.

  3. Empirical model for controlling beam-beam effects in ISABELLE

    Energy Technology Data Exchange (ETDEWEB)

    Parzen, G

    1980-01-01

    The beam-beam interaction may limit the beam intensity in ISABELLE. Although considerable progress has been made in understanding the beam-beam interaction, there appears to be no reliable method at present for computing the effects of the beam-beam interaction. The steps taken at ISABELLE to limit beam-beam effects are based largely on the experience accumulated at the ISR. At the ISR, the beam-beam effects do not appear to be large, and the beam intensity at the ISR does not appear to be limited by beam-beam effects. The beam-beam effects may be much stronger in ISABELLE because of factors like higher intensity and stronger non-linearities.

  4. Koehler-illumination-based method to improve beam size controllability

    Science.gov (United States)

    Hattori, Kiyoshi; Sunaoshi, Hitoshi; Ando, Atsushi

    1998-06-01

    We have developed a new EB calibration method for adjusting both Koehler illumination condition and beam current density precisely in the EB direct writing system EX-8D. Koehler illumination condition is adjusted by controlling the condenser lens so that the beam size change on the target vs. focus change of the objective is minimized. Beam current density is adjusted to the desired value by controlling the two condenser lenses which acts as a zoom lens function and maintaining above Koehler illumination condition. Using this method, beam size deviation was improved to less than 2 nm for a focus change of 10 micrometers , and beam current density was controlled to less than 0.5 percent error from the desired value. This beam calibration was executed in less than 10 minutes. We have also evaluated the pattern roughness and the pattern size deviation depending on the focus change by delineating a 0.125 micrometers line and space pattern. The pattern roughness was controlled to less than 2 nm and the pattern size deviation was less than 2 nm for a focus change of +/- micrometers .

  5. Duration of load behaviour of different sized straight timber beams subjected to bending in variable climate

    DEFF Research Database (Denmark)

    Hanhijärvi, A.; Galimard, P.; Hoffmeyer, Preben

    1998-01-01

    The paper is the second in a series which sums up the results of an extensive project to quantify the duration-of-load (DOL) effect on different sized timber beams in different climates. The paper deals with straight (unnotched) beams. The results of various DOL-tests of stepwise and constant ben...

  6. Focusing neutron beams to sub-millimeter size

    Energy Technology Data Exchange (ETDEWEB)

    Valicu, Moxana; Boeni, Peter [Physik-Department E21, Technische Universitaet Muenchen, Garching (Germany)

    2010-07-01

    Focusing neutron guides are a well-established means to significantly increase the neutron flux for the investigation of small samples or samples subject to extreme conditions such as pressure or high magnetic fields. Parabolic and elliptic guides can focus the beam in a single point beyond the guide exit with well defined beam characteristics and a gain in intensity of over 30 compared to a non-focused beam. Focusing guides find applications in elastic and inelastic neutron scattering as well as in neutron imaging to increase the spatial resolution and for magnification. The aim of the Monte Carlo simulations using McStas was to produce focal spots with a diameter of the order of 0.1 mm using supermirrors with large angles of reflection. We will discuss the results of our simulations, i.e. the gains obtained, their variation with wavelength as well as the evolution of the beam size.

  7. Size effect in the strength of concrete structures

    Indian Academy of Sciences (India)

    B L Karihaloo; Q Z Xiao

    2002-08-01

    This paper reports on the range of applicability of the various size effect formulae available in the literature. In particular, the failure loads of three point bend (TPB) beams are analysed according to the size effect formulae of Ba$\\breve{z}$ant and of Karihaloo for notched beams and according to those of Ba$\\breve{z}$ant and of Carpinteri for unnotched beams, and the results of this analysis presented. Improvements to Karihaloo’s size effect formula are also proposed.

  8. Overview of non-intercepting beam-size monitoring with optical diffraction radiation

    CERN Document Server

    Lumpkin, Alex H

    2012-01-01

    The initial demonstrations over the last several years of the use of optical diffraction radiation (ODR) as non-intercepting electron-beam-parameter monitors are reviewed. Developments in both far-field imaging and near-field imaging are addressed for ODR generated by a metal plane with a slit aperture, a single metal plane, and two-plane interferences. Polarization effects and sensitivities to beam size, divergence, and position will be discussed as well as a proposed path towards monitoring 10-micron beam sizes at 25 GeV.

  9. Overview of nonintercepting beam-size monitoring with optical diffraction radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, Alex H.; /Fermilab

    2010-08-01

    The initial demonstrations over the last several years of the use of optical diffraction radiation (ODR) as nonintercepting electron-beam-parameter monitors are reviewed. Developments in both far-field imaging and near-field imaging are addressed for ODR generated by a metal plane with a slit aperture, a single metal plane, and two-plane interferences. Polarization effects and sensitivities to beam size, divergence, and position will be discussed as well as a proposed path towards monitoring 10-micron beam sizes at 25 GeV.

  10. Material-Independent and Size-Independent Tractor Beams for Dipole Objects

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Qiu, Cheng-Wei; Lavrinenko, Andrei

    2012-01-01

    A Bessel beam without an axial gradient can exert a pulling force on an object [A. Novitsky, C. W. Qiu, and H. Wang, Phys. Rev. Lett. 107 203601 (2011)]. However, it cannot be called a “tractor beam” per se, as long as the light pulling effect is ultrasensitive to the object’s material and size......, a perturbation of which will make the optical traction go away. In this Letter, we investigate and report on the universality for a Bessel beam to be either a material-independent or size-independent optical tractor beam within the dipolar regime. Moreover, a general condition for a nonparaxial laser...... to be simultaneously a material- and size-independent tractor beam is proposed. These universal pulling effects and conditions are discussed in association with insight on modified far-field scattering, scattering resonances, and induced polarizabilities. Interestingly, we find that the acoustic pulling force exhibits...

  11. Modeling the effect of intermolecular force on the size-dependent pull-in behavior of beam-type NEMS using modified couple stress theory

    Energy Technology Data Exchange (ETDEWEB)

    Beni, Yaghoub Tadi; Karimipour, Iman [Shahrekord University, Shahrekord (Iran, Islamic Republic of); Abadyan, Mohamadreza [Islamic Azad University, Shahrekord (Iran, Islamic Republic of)

    2014-09-15

    Experimental observations reveal that the physical response of nano structures is size-dependent. Herein, modified couple stress theory has been used to study the effect of intermolecular van der Waals force on the size dependent pull-in of nano bridges and nano cantilevers. Three approaches including using differential transformation method, applying numerical method and developing a simple lumped parameter model have been employed to solve the governing equation of the systems. The pull-in parameters i.e. critical tip deflection and instability voltage of the nano structures have been determined. Effect of the van der Waals attraction and the size dependency and the importance of coupling between them on the pull-in performance have been discussed.

  12. Quenched effective population size

    CERN Document Server

    Sagitov, Serik; Vatutin, Vladimir

    2010-01-01

    We study the genealogy of a geographically - or otherwise - structured version of the Wright-Fisher population model with fast migration. The new feature is that migration probabilities may change in a random fashion. Applying Takahashi's results on Markov chains with random transition matrices, we establish convergence to the Kingman coalescent, as the population size goes to infinity. This brings a novel formula for the coalescent effective population size (EPS). We call it a quenched EPS to emphasize the key feature of our model - random environment. The quenched EPS is compared with an annealed (mean-field) EPS which describes the case of constant migration probabilities obtained by averaging the random migration probabilities over possible environments.

  13. Edge effect in beam monitors

    CERN Document Server

    Cuperus, J H

    1977-01-01

    Quite often, particle-beam monitors have not the same cross-section as the beam pipe or vacuum chamber in which they are mounted. In that case, the electromagnetic field of the beam is distorted in the vicinity of the edges of the monitor. This field, at the junction of two rectangular beam pipes of different dimensions, is computed for a beam with constant charge along its length. Solutions which are less accurate but easier to apply are obtained with a first order approximation. The results are extended to intensity-modulated beams and circular or elliptical cross-sections. The errors, due to the edge effect, for the electrostatic pickup and the wall-current monitor are computed. The final formulas are simple and easy to apply to practical cases. (6 refs).

  14. Effect of Hypoeutectic Boron Additions on the Grain Size and Mechanical Properties of Ti-6Al-4V Manufactured with Powder Bed Electron Beam Additive Manufacturing

    Science.gov (United States)

    Mahbooba, Zaynab; West, Harvey; Harrysson, Ola; Wojcieszynski, Andrzej; Dehoff, Ryan; Nandwana, Peeyush; Horn, Timothy

    2017-03-01

    In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricated Ti-6Al-4V + B indicate that the addition of 0.25-1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.

  15. Effect of Hypoeutectic Boron Additions on the Grain Size and Mechanical Properties of Ti-6Al-4V Manufactured with Powder Bed Electron Beam Additive Manufacturing

    Science.gov (United States)

    Mahbooba, Zaynab; West, Harvey; Harrysson, Ola; Wojcieszynski, Andrzej; Dehoff, Ryan; Nandwana, Peeyush; Horn, Timothy

    2016-12-01

    In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricated Ti-6Al-4V + B indicate that the addition of 0.25-1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.

  16. Observed Orbit Effects during Long Range Beam-Beam Studies

    CERN Document Server

    Alemany, R; Buffat, X; Calaga, R; Fitterer, M; Giachino, R; Hemelsoet, GH; Herr, W; Papotti, G; Pieloni, T; Poyer, M; Schaumann, M; Trad, G; Wollmann, D

    2012-01-01

    Possible limitations due to long range beam-beam effects at the LHC have been studied and are presented in this note. With a larger number of bunches and collisions in all interaction points, the crossing angles were reduced to enhance long range beam-beam effects. The analysis of the effects on the dynamic aperture and losses are documented in [1]. This note concentrates on the bunch-by-bunch orbit effects observed during the experiment.

  17. Measurement Error Effects of Beam Parameters Determined by Beam Profiles

    CERN Document Server

    Jang, Ji-Ho; Jeon, Dong-O

    2015-01-01

    A conventional method to determine beam parameters is using the profile measurements and converting them into the values of twiss parameters and beam emittance at a specified position. The beam information can be used to improve transverse beam matching between two different beam lines or accelerating structures. This work is related with the measurement error effects of the beam parameters and the optimal number of profile monitors in a section between MEBT (medium energy beam transport) and QWR (quarter wave resonator) of RAON linear accelerator.

  18. 单调荷载作用下高强混凝土梁受弯性能尺寸效应研究%Size effect on flexural behavior of reinforced high-strength concrete beams subjected to monotonic loading

    Institute of Scientific and Technical Information of China (English)

    车轶; 郑新丰; 王金金; 宋玉普

    2012-01-01

    Reinforced high-strength concrete beams subjected to bending were tested to investigate the effect of depth on flexural behavior of beams.The geometry of specimens varied in cross sections with the depth-width ratios of the cross sections,the shear span ratios and longitudinal reinforcement ratios of specimens being constant.C70 concrete was used to cast the specimens and HRB 400 steel bars were used for the longitudinal reinforcement.The influence of beam depth on the nominal cracking moment,nominal yield moment,nominal ultimate flexural moment,ductility,and plastic rotation capacity of high-strength concrete beams was investigated.It is shown that there is no apparent size effect on nominal cracking moment,nominal yield moment and nominal ultimate moment of reinforced high-strength concrete beams.But the displacement ductility ratio and plastic rotation capacity show significant size effect.The displacement ductility factor and the rotational capacity of high-strength concrete beam decrease with the increasing of cross section.%进行了不同截面尺寸高强混凝土梁的弯曲试验,研究了梁高对其受弯性能的影响。试件采用C70高强混凝土,纵向受力钢筋采用HRB400级钢筋。试件截面尺寸不同,截面长宽比、剪跨比和配筋率等参数保持一致。分析了不同截面尺寸对高强混凝土梁的名义开裂弯矩、名义屈服弯矩、名义极限弯矩、延性以及塑性转动能力的影响。研究结果表明,高强混凝土梁的名义开裂弯矩、名义屈服弯矩和名义极限弯矩无明显尺寸效应,而试件的位移延性系数和塑性铰区的塑性转动能力则表现出明显的尺寸效应,随截面尺寸的增大梁的位移延性系数和塑性铰区塑性转动能力有所降低。

  19. Aperture Effects and Mismatch Oscillations in an Intense Electron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Harris, J R; O' Shea, P G

    2008-05-12

    When an electron beam is apertured, the transmitted beam current is the product of the incident beam current density and the aperture area. Space charge forces generally cause an increase in incident beam current to result in an increase in incident beam spot size. Under certain circumstances, the spot size will increase faster than the current, resulting in a decrease in current extracted from the aperture. When using a gridded electron gun, this can give rise to negative transconductance. In this paper, we explore this effect in the case of an intense beam propagating in a uniform focusing channel. We show that proper placement of the aperture can decouple the current extracted from the aperture from fluctuations in the source current, and that apertures can serve to alter longitudinal space charge wave propagation by changing the relative contribution of velocity and current modulation present in the beam.

  20. Effect sizes in memory research.

    Science.gov (United States)

    Morris, Peter E; Fritz, Catherine O

    2013-01-01

    Effect sizes are omitted from many research articles and are rarely discussed. To help researchers evaluate effect sizes we collected values for the more commonly reported effect size measures (partial eta squared and d) from papers reporting memory research published in 2010. Cohen's small, medium, and large generic guideline values for d mapped neatly onto the observed distributions, but his values for partial eta squared were considerably lower than those observed in current memory research. We recommend interpreting effect sizes in the context of either domain-specific guideline values agreed for an area of research or the distribution of effect size estimates from published research in the domain. We provide cumulative frequency tables for both partial eta squared and d enabling authors to report and consider not only the absolute size of observed effects but also the percentage of reported effects that are larger or smaller than those observed.

  1. Single-shot beam size measurements using visible-light interferometry at CESR

    Science.gov (United States)

    Wang, S. T.; Holtzapple, R.; Rubin, D. L.

    2017-03-01

    A new primary mirror for a visible-light beam size monitor (vBSM) was designed and installed in the Cornell Electron-Positron Storage Ring (CESR). The vertical angular acceptance of the mirror was doubled to allow double-slit interferometry with large slit separation (>12 mm). In addition, the diffraction associated with the first generation mirror has been eliminated. The resolution of the vertical beam size measurements has been dramatically improved but is ultimately limited by the beam motion. Two fast-response detectors, a Photomultiplier Tube (PMT) array and a gated camera, were employed to study the beam motion. The advantages and limitations of both devices are discussed in this paper. The gated camera was also used to measure single-shot beam width and motion of each bunch in a multi-bunch train. We measured significantly more horizontal motion of electron as compared to positron bunch trains in otherwise identical machine condition. This difference may be a signature for the difference between electron cloud build-up for positron bunch trains versus ions effects characteristic of electron bunch trains.

  2. Size Effect in Continuum Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei-Yang [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials; Foulk, James W. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials; Huestis, Edwin M. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials; Connelly, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials; Song, Bo [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials; Yang, Nancy Y. C. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Engineered Materials

    2008-09-01

    The mechanical properties of some materials (Cu, Ni, Ag, etc.) have been shown to develop strong dependence on the geometric dimensions, resulting in a size effect. Several theories have been proposed to model size effects, but have been based on very few experiments conducted at appropriate scales. Some experimental results implied that size effects are caused by increasing strain gradients and have been used to confirm many strain gradient theories. On the other hand, some recent experiments show that a size effect exists in the absence of strain gradients. This report describes a brief analytical and experimental study trying to clarify the material and experimental issues surrounding the most influential size-effect experiments by Fleck et al (1994). This effort is to understand size effects intended to further develop predictive models.

  3. Beam Size Measurement by Optical Diffraction Radiation and Laser System for Compton Polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chuyu [Peking Univ., Beijing (China)

    2012-12-31

    Beam diagnostics is an essential constituent of any accelerator, so that it is named as "organs of sense" or "eyes of the accelerator." Beam diagnostics is a rich field. A great variety of physical effects or physical principles are made use of in this field. Some devices are based on electro-magnetic influence by moving charges, such as faraday cups, beam transformers, pick-ups; Some are related to Coulomb interaction of charged particles with matter, such as scintillators, viewing screens, ionization chambers; Nuclear or elementary particle physics interactions happen in some other devices, like beam loss monitors, polarimeters, luminosity monitors; Some measure photons emitted by moving charges, such as transition radiation, synchrotron radiation monitors and diffraction radiation-which is the topic of the first part of this thesis; Also, some make use of interaction of particles with photons, such as laser wire and Compton polarimeters-which is the second part of my thesis. Diagnostics let us perceive what properties a beam has and how it behaves in a machine, give us guideline for commissioning, controlling the machine and indispensable parameters vital to physics experiments. In the next two decades, the research highlight will be colliders (TESLA, CLIC, JLC) and fourth-generation light sources (TESLA FEL, LCLS, Spring 8 FEL) based on linear accelerator. These machines require a new generation of accelerator with smaller beam, better stability and greater efficiency. Compared with those existing linear accelerators, the performance of next generation linear accelerator will be doubled in all aspects, such as 10 times smaller horizontal beam size, more than 10 times smaller vertical beam size and a few or more times higher peak power. Furthermore, some special positions in the accelerator have even more stringent requirements, such as the interaction point of colliders and wigglor of free electron lasers. Higher performance of these accelerators increases the

  4. Theoretical study of the effect of the size of a high-energy proton beam of the Large Hadron Collider on the formation and propagation of shock waves in copper irradiated by 450-GeV proton beams

    CERN Document Server

    Ryazanov, A I; Vasilyev, Ya S; Ferrari, A

    2014-01-01

    The interaction of 450GeV protons with copper, which is the material of the collimators of the Large Hadron Collider, has been theoretically studied. A theoretical model for the formation and propagation of shock waves has been proposed on the basis of the anal ysis of the energy released by a proton beam in the electronic subsystem of the material owing to the deceleration of secondary particles appearing in nuclear reactions induced by this beam on the electronic subsy stem of the material. The subsequent transfer of the energy from the excited electronic subsystem to the crystal lattice through the electron–phonon interaction has been described within the thermal spike model [I.M. Lifshitz, M.I. Kaganov, and L.V. Tanatarov, Sov. Phys. JETP 4 , 173 (1957); I.M. Lifshitz, M.I. Kaganov, and L.V. Tanatarov, At. Energ. 6 , 391 (1959); K. Yasui, Nucl. Instrum. Methods Phys. Res., Sect. B 90 , 409 (1994)]. The model of the formation of shock waves involves energy exchange processes between excited electronic an...

  5. Effects of Ti charge state, ion size and beam-induced compaction on the formation of Ag metal nanoparticles in fused silica

    Science.gov (United States)

    Magruder, R. H.; Meldrum, A.; Haglund, R. F.

    2015-04-01

    Metal nanoparticles formed by ion implantation in fused silica exhibit linear and nonlinear optical properties that can be altered by co-doping the silica substrate with transition-metal ions. For example, implantation of scandium in fused silica creates a directional optical dichroism due to the different spatial distribution of silver nanoparticles subsequently formed by Ag ion implantation. In this paper, we show that implantation of titanium ions alters the short- and intermediate-range order in the silica and thereby alters the diffusion and nucleation processes that lead to formation of silver nanoparticles. In particular, the dichroic response observed for Ag nanoparticles in Sc-implanted silica is, with one exception, in Ti-implanted silica. Compaction of the silica due to the ion implantation process appears to be similar for both Sc and Ti implantations, based on the observed shift of the 1,124 cm-1 transverse-optical phonon mode in the infrared reflectance spectrum. However, differences in chemical reactivity, bond lengths and electronic structure of Sc and Ti produce changes in electronic structure and strain that are sensitively reflected in the reflectance spectra of the Ag nanoparticles. These differences lead to modifications in the size, shape and spatial distributions of the silver nanoparticles and offer a powerful means of controlling their optical properties.

  6. Size effect in thermoelectric materials

    Science.gov (United States)

    Mao, Jun; Liu, Zihang; Ren, Zhifeng

    2016-12-01

    Thermoelectric applications have attracted increasing interest recently due to its capability of converting waste heat into electricity without hazardous emissions. Materials with enhanced thermoelectric performance have been reported in recent two decades. The revival of research for thermoelectric materials began in early 1990s when the size effect is considered. Low-dimensional materials with exceptionally high thermoelectric figure of merit (ZT) have been presented, which broke the limit of ZT around unity. The idea of size effect in thermoelectric materials even inspired the later nanostructuring and band engineering strategies, which effectively enhanced the thermoelectric performance of bulk materials. In this overview, the size effect in low-dimensional thermoelectric materials is reviewed. We first discuss the quantum confinement effect on carriers, including the enhancement of electronic density of states, semimetal to semiconductor transition and carrier pocket engineering. Then, the effect of assumptions on theoretical calculations is presented. Finally, the effect of phonon confinement and interface scattering on lattice thermal conductivity is discussed.

  7. Surface stress effect on the vibration and instability of nanoscale pipes conveying fluid based on a size-dependent Timoshenko beam model

    Science.gov (United States)

    Ansari, R.; Gholami, R.; Norouzzadeh, A.; Darabi, M. A.

    2015-10-01

    Presented in this paper is a precise investigation of the effect of surface stress on the vibration characteristics and instability of fluid-conveying nanoscale pipes. To this end, the nanoscale pipe is modeled as a Timoshenko nanobeam. The equations of motion of the nanoscale pipe are obtained based on Hamilton's principle and the Gurtin-Murdoch continuum elasticity incorporating the surface stress effect. Afterwards, the generalized differential quadrature method is employed to discretize the governing equations and associated boundary conditions. To what extent important parameters such as the thickness, material and surface stress modulus, residual surface stress, surface density, and boundary conditions influence the natural frequency of nanoscale pipes and the critical velocity of fluid is discussed.

  8. Size Control Technology of Silver Nanoparticles Using Electron Beam Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hyun Suk; Kim, Byungnam; Kim, Hye Won; Koo, Yong Hwan; Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Ji Hyun [Univ. of Science and Technology, Daejeon (Korea, Republic of); Bae, Hyung Bin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Park, Changmoon [Chungnam National Univ., Daejeon (Korea, Republic of)

    2013-12-15

    The manufacturing of silver nanoparticles using an electron beam is easy, fast, and highly productive, and it is possible at room temperature with no chemical residuals. Its various advantages therefore make this an important method for manufacturing nanoparticles such as silver, copper, and platinum. In particular, despite the use of electron beam irradiation, the results show that this method makes it possible to produce silver nanoparticles at low cost since low beam energy and low doses are used. This means that middle and high-energy electron beam accelerators are very expensive, but a low-energy electron beam accelerator has a relatively low cost of around 4-5 times, and mass production for a flow reaction without the need for extra radiation shielding is possible. Silver nanoparticles are of great interest to many researchers owing to their ability to be used in many applications such as catalysis, nanoelectronics, optical filters, electromagnetic interference shielding, surface Raman scattering, medical supplies, fabrics, cosmetics, hygiene and kitchen supplies, and electric home appliances.

  9. Size effects in crystal plasticity

    DEFF Research Database (Denmark)

    Borg, Ulrik

    2007-01-01

    of plastic flow in a single crystal, grain boundary effects in a bicrystal, and grain size effects in a polycrystal are studied. Single crystals containing micro-scale voids have also been analyzed at different loading conditions with focus on the stress and deformation fields around the voids, on void......Numerical analyses of plasticity size effects have been carried out for different problems using a developed strain gradient crystal plasticiy theory. The theory employs higher order stresses as work conjugates to slip gradients and uses higher order boundary conditions. Problems on localization...

  10. Detector dose response in megavoltage small photon beams. II. Pencil beam perturbation effects

    Energy Technology Data Exchange (ETDEWEB)

    Bouchard, Hugo, E-mail: hugo.bouchard@npl.co.uk; Duane, Simon [Acoustics and Ionising Radiation Team, National Physical Laboratory, Hampton Road, Teddington TW11 0LW (United Kingdom); Kamio, Yuji [Centre hospitalier de l’Université de Montréal (CHUM), 1560 Sherbrooke Est, Montréal, Québec H2L 4M1 (Canada); Palmans, Hugo [Acoustics and Ionising Radiation Team, National Physical Laboratory, Hampton Road, Teddington TW11 0LW (United Kingdom); Medical Physics, EBG MedAustron GmbH, Wiener Neustadt A-2700 (Austria); Seuntjens, Jan [Medical Physics Unit, McGill University, Montréal, Québec H3G 1A4 (Canada)

    2015-10-15

    Purpose: To quantify detector perturbation effects in megavoltage small photon fields and support the theoretical explanation on the nature of quality correction factors in these conditions. Methods: In this second paper, a modern approach to radiation dosimetry is defined for any detector and applied to small photon fields. Fano’s theorem is adapted in the form of a cavity theory and applied in the context of nonstandard beams to express four main effects in the form of perturbation factors. The pencil-beam decomposition method is detailed and adapted to the calculation of perturbation factors and quality correction factors. The approach defines a perturbation function which, for a given field size or beam modulation, entirely determines these dosimetric factors. Monte Carlo calculations are performed in different cavity sizes for different detection materials, electron densities, and extracameral components. Results: Perturbation effects are detailed with calculated perturbation functions, showing the relative magnitude of the effects as well as the geometrical extent to which collimating or modulating the beam impacts the dosimetric factors. The existence of a perturbation zone around the detector cavity is demonstrated and the approach is discussed and linked to previous approaches in the literature to determine critical field sizes. Conclusions: Monte Carlo simulations are valuable to describe pencil beam perturbation effects and detail the nature of dosimetric factors in megavoltage small photon fields. In practice, it is shown that dosimetric factors could be avoided if the field size remains larger than the detector perturbation zone. However, given a detector and beam quality, a full account for the detector geometry is necessary to determine critical field sizes.

  11. Effect Size in Clinical Phonology

    Science.gov (United States)

    Gierut, Judith A.; Morrisette, Michele L.

    2011-01-01

    The purpose of this article is to motivate the use of effect size (ES) for single-subject research in clinical phonology, with an eye towards meta-analyses of treatment effects for children with phonological disorders. Standard mean difference (SMD) is introduced and illustrated as one ES well suited to the multiple baseline (MBL) design and…

  12. The influence of Laval nozzle throat size on supersonic molecular beam injection

    Institute of Scientific and Technical Information of China (English)

    Xinkui He; Xianfu Feng; Mingmin Zhong; Fujun Gou; Shuiquan Deng; Yong Zhao

    2014-01-01

    In this study, finite element analysis (FEA) has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diam-eter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift pro-gressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.

  13. Simulating Transient Effects of Pulsed Beams on Beam Intercepting Devices

    CERN Document Server

    Richter, Herta; Noah Messomo, Etam

    2011-01-01

    The development in the physics community towards higher beam power through the possibilities of particle accelerators lead to challenges for the developers of elements which are exposed to effect of particle beams (beam intercepting devices = BIDs). For the design of BIDs, the increasing heat load onto these devices due to energetic and focused beams and - in most cases - their highly pulsed nature has to be taken into account. The physics requirements are sometimes opposed to the current state of the art. As one possibility of many in combining the different aspects for these ambitious demands, two highly developed computer programs, namely FLUKA and ANSYS AUTODYN, were joined for this dissertation. The former is a widely enhanced Monte-Carlo-code which specializes on the interaction of particles with static matter, while the latter is a versatile explicit code for the simulation of highly dynamic processes. Both computer programs were developed intensively over years and are still continuously enhanced in o...

  14. Measurement of the Beam Size and Emittance for the CRC Cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sae Hoon; Kim, Yu Seok [Dongguk University, Gyeongju (Korea, Republic of)

    2012-05-15

    The purpose of the present study was to confirm beam property for regional Cyclotron Research Center (CRC) installed at Chosun University Hospital. The regional CRC has been developed to produce radioisotope for positron emission tomography (PET). The original radioisotope production cyclotron had a large beam size, which need to be reduced by collimator. In order to construct the proton-induced X-ray emission and proton-induced gamma-ray emission (PIXE-PIGE) beam line, ion beam will be transported to PIXE-PIGE chamber that we have identified the beam size decreased by collimator and beam emittance. There are several methods to measure the emittace, such as the slit and collector method, the pepper-pot method, and the quad scan method. These methods use a slit and monitor to measure the beam profiles, which depend on the field gradient of the quadrupole magnet. In this study, we did not use magnet and monitor. The emittance calculation based on simulated data by previously proven program is approached to consider various methods. Beam emittance was calculated in two methods. The two methods were classical method and ion beam position with divergence method. We found that the beam sizes of x, y-direction are reduced very well

  15. Size effect on the static behavior of electrostatically actuated microbeams

    Institute of Scientific and Technical Information of China (English)

    Li Yin; Qin Qian; Lin Wang

    2011-01-01

    We present a new analytical model for electrostatically actuated microbeams to explore the size effect by using the modified couple stress theory and the minimum total potential energy principle. A material length scale parameter is introduced to represent the size-dependent characteristics of microbeams. This model also accounts for the nonlinearities associated with the mid-plane stretching force and the electrostatical force. Numerical analysis for microbeams with clamped-clamped and cantilevered conditions has been performed. It is found that the intensity of size effect is closely associated with the thickness of the microbeam, and smaller beam thickness displays stronger size effect and hence yields smaller deflection and larger pull-in voltage. When the beam thickness is comparable to the material length scale parameter, the size effect is significant and the present theoretical model including the material length scale parameter is adequate for predicting the static behavior of microbeam-based MEMS.

  16. Beam Size Estimation from Luminosity Scans at the LHC During 2015 Proton Physics Operation

    CERN Document Server

    Hostettler, Michael

    2016-01-01

    As a complementary method for measuring the beam size for high-intensity beams at 6.5 TeV flat-top energy, beam separation scans were done regularly at the CERN Large Hadron Collider (LHC) during 2015 proton physics operation. The luminosities measured by the CMS experiment during the scans were used to derive the convoluted beam size and orbit offset bunch-by-bunch. This contribution will elaborate on the method used to derive plane-by-plane, bunch-by-bunch emittances from the scan data, including uncertainties and corrections. The measurements are then compared to beam size estimations from absolute luminosity, synchrotron light telescopes, and wire scanners. In particular, the evolution of the emittance over the course of several hours in collisions is studied and bunch-by-bunch differences are highlighted.

  17. Development of a multi-lane X-ray mirror providing variable beam sizes.

    Science.gov (United States)

    Laundy, D; Sawhney, K; Nistea, I; Alcock, S G; Pape, I; Sutter, J; Alianelli, L; Evans, G

    2016-05-01

    Grazing incidence mirrors are used on most X-ray synchrotron beamlines to focus, collimate or suppress harmonics. Increasingly beamline users are demanding variable beam shapes and sizes at the sample position. We have now developed a new concept to rapidly vary the beam size and shape of a focused X-ray beam. The surface of an elliptically figured mirror is divided into a number of laterally separated lanes, each of which is given an additional longitudinal height profile calculated to shape the X-ray beam to a top-hat profile in the focal plane. We have now fabricated two prototype mirrors and present the results of metrology tests and measurements made with one of the mirrors focusing the X-rays on a synchrotron beamline. We envisage that such mirrors could be widely applied to rapid beam-size switching on many synchrotron beamlines.

  18. Simulation of beam-induced plasma for the mitigation of beam-beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Ma, J.; Wang, G.; Samulyak, R.; Yu, K.; Litvinenko, V.

    2015-05-03

    One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.

  19. EFFECT OF SPACE CHARGE ON STABILITY OF BEAM DISTRIBUTION IN THE SNS RING.

    Energy Technology Data Exchange (ETDEWEB)

    FEDOTOV, A.V.; WEI, J.; GLUCKSTERN, R.L.

    2001-06-18

    In the Spallation Neutron Source (SNS) ring, multi-turn injection is employed to obtain a large transverse beam size which significantly reduces the space-charge tune shift of the accumulated beam. Careful choice of the painting scheme and bump function is required to obtain the desired beam profile together with low beam loss. In this paper we examine, both analytically and numerically, the effect of the space charge on the beam profile during multi-turn injection painting.

  20. Noninvasive measurement of micron electron beam size of high energy using diffraction radiation

    CERN Document Server

    Naumenko, G A

    2003-01-01

    Treatments of the usage of diffraction radiation from the relativistic electrons moving though a conductive slit for the transverse beam size measurement encounter hard limitation of the method sensitivity for the electron energy larger than 1 GeV. We consider in this article a possibility of application of the artificial phase shift, which can take place when transverse electron position varies. This allows us to realize the measurements of transverse size of supper-relativistic electron beams with the small emittance.

  1. Report of the group on beam-beam effects in circular colliders

    Energy Technology Data Exchange (ETDEWEB)

    Furman, M.A.

    1991-05-01

    We present a summary of the discussions and conclusions of the working group on beam-beam effects for circular colliders. This group was part of the larger beam-beam dynamics group at the 7th ICFA Workshop on Beam Dynamics, on the subject Beam-Beam and Beam-Radiation Interactions,'' held at UCLA, May 13--16, 1991. 15 refs.

  2. A fourier analysis on the maximum acceptable grid size for discrete proton beam dose calculation.

    Science.gov (United States)

    Li, Haisen S; Romeijn, H Edwin; Dempsey, James F

    2006-09-01

    We developed an analytical method for determining the maximum acceptable grid size for discrete dose calculation in proton therapy treatment plan optimization, so that the accuracy of the optimized dose distribution is guaranteed in the phase of dose sampling and the superfluous computational work is avoided. The accuracy of dose sampling was judged by the criterion that the continuous dose distribution could be reconstructed from the discrete dose within a 2% error limit. To keep the error caused by the discrete dose sampling under a 2% limit, the dose grid size cannot exceed a maximum acceptable value. The method was based on Fourier analysis and the Shannon-Nyquist sampling theorem as an extension of our previous analysis for photon beam intensity modulated radiation therapy [J. F. Dempsey, H. E. Romeijn, J. G. Li, D. A. Low, and J. R. Palta, Med. Phys. 32, 380-388 (2005)]. The proton beam model used for the analysis was a near monoenergetic (of width about 1% the incident energy) and monodirectional infinitesimal (nonintegrated) pencil beam in water medium. By monodirection, we mean that the proton particles are in the same direction before entering the water medium and the various scattering prior to entrance to water is not taken into account. In intensity modulated proton therapy, the elementary intensity modulation entity for proton therapy is either an infinitesimal or finite sized beamlet. Since a finite sized beamlet is the superposition of infinitesimal pencil beams, the result of the maximum acceptable grid size obtained with infinitesimal pencil beam also applies to finite sized beamlet. The analytic Bragg curve function proposed by Bortfeld [T. Bortfeld, Med. Phys. 24, 2024-2033 (1997)] was employed. The lateral profile was approximated by a depth dependent Gaussian distribution. The model included the spreads of the Bragg peak and the lateral profiles due to multiple Coulomb scattering. The dependence of the maximum acceptable dose grid size on the

  3. Study of size effect using digital image correlation

    Directory of Open Access Journals (Sweden)

    A. H. A. SANTOS

    Full Text Available Size effect is an important issue in concrete structures bearing in mind that it can influence many aspects of analysis such as strength, brittleness and structural ductility, fracture toughness and fracture energy, among others. Further this, ever more new methods are being developed to evaluate displacement fields in structures. In this paper an experimental evaluation of the size effect is performed applying Digital Image Correlation (DIC technique to measure displacements on the surface of beams. Three point bending tests were performed on three different size concrete beams with a notch at the midspan. The results allow a better understanding of the size effect and demonstrate the efficiency of Digital Image Correlation to obtain measures of displacements.

  4. Performance analysis of MIMO FSO systems with radial array beams and finite sized detectors

    Science.gov (United States)

    Gökçe, Muhsin C.; Kamacıoǧlu, Canan; Uysal, Murat; Baykal, Yahya

    2014-10-01

    Multiple-input multiple-output (MIMO) systems are employed in free space optical (FSO) links to mitigate the degrading effects of atmospheric turbulence. In this paper, we consider a MIMO FSO system with practical transmitter and receiver configurations that consists of a radial laser array with Gaussian beams and finite sized detectors. We formulate the average received intensity and the power scinitillation as a function of the receiver coordinates in the presence of weak atmospheric turbulence by using the extended Huygens-Fresnel principle. Then, integrations over the finite sized multiple detectors are performed and the effect of the receiver aperture averaging is quantified. We further derive an outage probability expression of this MIMO system in the presence of turbulence-induced fading channels. Using the derived expressions, we demonstrate the effect of several practical system parameters such as the ring radius, the number of array beamlets, the source size, the link length, structure constant and the receiver aperture radius on the system performance.

  5. Beam-Beam Effects in the Ring-Ring Version of eRHIC

    CERN Document Server

    Shi, Jack; Wang, Dong; Wang, Fuhua

    2005-01-01

    The eRHIC is a proposed electron ring at the RHIC that will provide collisions between a polarized 5-10 GeV electron beam and an ion beam from one of the RHIC rings. In order to achieve proposed high luminosity, large bunch current and small beta-functions at the IP has to be employed. Such measures result in large beam-beam parameters, 0.029 and 0.08 for the electron beam and 0.0065 and 0.0033 for the proton beam in the horizontal and vertical plane, respectively, in the current ZDR design. The beam-beam effect especially the coherent beam-beam effect is therefore one of important issues to the eRHIC. Moreover, the proposed configuration of unequal circumferences of the electron and proton rings could further enhance the coherent beam-beam effect. The beam-beam effect of eRHIC has therefore been studied with a self-consistent beam-beam simulation by using the particle-in-cell method. Beam-beam limits of the electron and proton beam were examined as thresholds of the onset of coherent beam-beam instability. F...

  6. A finite-element approach to evaluating the size effects of complex nanostructures

    Science.gov (United States)

    Lu, Dingjie; Xie, Yi Min; Li, Qing; Huang, Xiaodong; Li, Yang Fan; Zhou, Shiwei

    2016-12-01

    The size effects that reveal the dramatic changes of mechanical behaviour at nanoscales have traditionally been analysed for regular beam systems. Here, the method of using finite-element analysis is explored with the intention of evaluating the size effects for complex nanostructures. The surface elasticity theory and generalized Young-Laplace equation are integrated into a beam element to account for the size effects in classical Euler-Bernoulli and Timoshenko beam theories. Computational results match well with the theoretical predictions on the size effect for a cantilever beam and a cubic unit cell containing 24 horizontal/vertical ligaments. For a simply supported nanowire, it is found that the results are very close to the experimental data. With the assumption that nanoporous gold is composed of many randomly connected beams, for the first time, the size effect of such a complex structure is numerically determined.

  7. Solar Hard X-ray Source Sizes in a Beam-Heated and Ionised Chromosphere

    CERN Document Server

    O'Flannagain, A; Gallagher, P T

    2014-01-01

    Solar flare hard X-rays (HXRs) are produced as bremsstrahlung when an accelerated population of electrons interacts with the dense chromospheric plasma. HXR observations presented by using the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) have shown that HXR source sizes are 3-6 times more extended in height than those predicted by the standard collisional thick target model (CTTM). Several possible explanations have been put forward including the multi-threaded nature of flare loops, pitch-angle scattering, and magnetic mirroring. However, the nonuniform ionisation (NUI) structure along the path of the electron beam has not been fully explored as a solution to this problem. Ionised plasma is known to be less effective at producing nonthermal bremsstrahlung HXRs when compared to neutral plasma. If the peak HXR emission was produced in a locally ionised region within the chromosphere, the intensity of emission will be preferentially reduced around this peak, resulting in a more extended source. Due to...

  8. Size-dependent crystalline fluctuation and growth mechanism of bismuth nanoparticles under electron beam irradiation

    Science.gov (United States)

    Wu, Sujuan; Jiang, Yi; Hu, Lijun; Sun, Jianguo; Wan, Piaopiao; Sun, Lidong

    2016-06-01

    Advanced nanofabrication requires accurate tailoring of various nanostructures with the assistance of electron or ion beam irradiation. However, evolution of the nanostructures under the beam irradiation significantly affects the fabrication process. It is thus of paramount importance to study the evolution behaviors and growth mechanism of the nanostructures. In this study, bismuth nanoparticles were selected to investigate crystalline fluctuation under electron beam irradiation via transmission electron microscopy. The results disclose size-dependent crystalline fluctuation of the nanoparticles. The particles exhibit crystalline and non-crystalline features for sizes of above 15 and below 4 nm, respectively, while a mixture of the two states is observed with sizes in between. The crystalline fluctuation facilitates the growth process of the particles when a crystalline particle is in contact with another non-crystalline one. This is promising for applications in nanofabrication where high quality interfaces are desired between two joining parts.Advanced nanofabrication requires accurate tailoring of various nanostructures with the assistance of electron or ion beam irradiation. However, evolution of the nanostructures under the beam irradiation significantly affects the fabrication process. It is thus of paramount importance to study the evolution behaviors and growth mechanism of the nanostructures. In this study, bismuth nanoparticles were selected to investigate crystalline fluctuation under electron beam irradiation via transmission electron microscopy. The results disclose size-dependent crystalline fluctuation of the nanoparticles. The particles exhibit crystalline and non-crystalline features for sizes of above 15 and below 4 nm, respectively, while a mixture of the two states is observed with sizes in between. The crystalline fluctuation facilitates the growth process of the particles when a crystalline particle is in contact with another non

  9. A size-dependent model for beam-like MEMS driven by electrostatic and piezoelectric forces: A variational approach

    Science.gov (United States)

    Yin, Tenghao; Wang, Binglei; Zhou, Shenjie; Zhao, Moli

    2016-10-01

    A size-dependent model of a micro-electromechanical system (MEMS) actuated by both electrostatic and piezoelectric forces is proposed based on the modified couple stress. The governing equation and boundary conditions are derived with the help of the Hamilton principle and solved numerically by employing the Galerkin method and Newton downhill method. A material length scale parameter (MLSP) is incorporated in the model to capture the size effect in microstructures. An excellent agreement is found between the results of the present model and the experimental data, providing the validity of this model. The results reveal that the introduction of the MLSP stiffens the system and increases the pull-in voltage. The size-effect is significant when the dimension of the beam is comparable to the MLSP but it becomes smaller as the beam size increases. Besides, the static characteristic of the micro-switch is studied. It is found that the piezoelectric material attached on the beam can reduce the pull-in voltage remarkably, which may guide the design of the micro-structure when the system is on the order of micron or submicron.

  10. Wavefront-sensor-induced beam size error: physical mechanism, sensitivity-analysis and correction method

    NARCIS (Netherlands)

    Koek, W.D.; Zwet, E.J. van

    2015-01-01

    When using a commonly-used quadri-wave lateral shearing interferometer wavefront sensor (QWLSI WFS) for beam size measurements on a high power CO2 laser, artefacts have been observed in the measured irradiance distribution. The grating in the QWLSI WFS not only generates the diffracted first orders

  11. Effect Sizes in Gifted Education Research

    Science.gov (United States)

    Gentry, Marcia; Peters, Scott J.

    2009-01-01

    Recent calls for reporting and interpreting effect sizes have been numerous, with the 5th edition of the "Publication Manual of the American Psychological Association" (2001) calling for the inclusion of effect sizes to interpret quantitative findings. Many top journals have required that effect sizes accompany claims of statistical significance.…

  12. School size effects: review and conceptual analysis

    NARCIS (Netherlands)

    Scheerens, Jaap; Hendriks, Maria; Luyten, Hans; Luyten, Hans; Hendriks, Maria; Scheerens, Jaap

    2014-01-01

    In this chapter, a review of international review studies on school size effects is presented. Next, ingredients of a more contextualized and tentative causal mediation model of school size effects are discussed. The chapter is completed by a short overview of school size effects as found in interna

  13. Size distribution estimation of cavitation bubble cloud via bubbles dissolution using an ultrasound wide-beam method

    Science.gov (United States)

    Xu, Shanshan; Zong, Yujin; Liu, Xiaodong; Wan, Mingxi

    2017-03-01

    This paper proposed an acoustic technique to estimate size distribution of a cavitation bubble cloud induced by focused ultrasound (FUS) based on the dissolution of bubble cloud trapped by a wide beam of low acoustic pressure, after the acoustic exposure of FUS is turned off. Dissolution of cavitation bubbles in saline and in phase-shift nanodroplet emulsion diluted with degassed saline or saturated saline has been respectively studied to quantify the effects of pulse duration (PD) and acoustic power (AP) or peak negative pressure (PNP) of FUS on size distribution of cavitation bubbles.

  14. Impact of beam-beam effects on precision luminosity measurements at the ILC

    CERN Document Server

    Rimbault, C; Mönig, K; Schulte, D

    2007-01-01

    In this paper, the impact of beam-beam effects on the precision luminosity measurement at the International Linear Collider is investigated quantitatively for the first time. GUINEA-PIG, a beam-beam interaction simulation tool, is adapted to treat the space charge effects affecting the Bhabha events used in this measurement. The biases due to the resulting changes in kinematics are evaluated for different center-of-mass energies and beam parameters.

  15. Modelling of Size Effect with Regularised Continua

    Directory of Open Access Journals (Sweden)

    H. Askes

    2004-01-01

    Full Text Available A nonlocal damage continuum and a viscoplastic damage continuum are used to model size effects. Three-point bending specimens are analysed, whereby a distinction is made between unnotched specimens, specimens with a constant notch and specimens with a proportionally scaled notch. Numerical finite element simulations have been performed for specimen sizes in a range of 1:64. Size effects are established in terms of nominal strength and compared to existing size effect models from the literature. 

  16. Beam Collimation Using an Anisotropic Metamaterial Slab without Any Nanometer-sized Aperture

    CERN Document Server

    Zhang, Shou; Cui, Yanxia; Zhang, Feng; He, Sailing; Hao, Yuying; Zhu, Furong

    2015-01-01

    Plasmonic beam collimation effect has been thoroughly investigated based on the well-known nanometer-scale bull's eye structure formed by complex and high-cost fabrication processes. In this work, we report our effort for attaining beam collimation using an anisotropic metamaterial (AMM) slab that consists of a stack of alternating metal/dielectric layers and an integrated top metal grating. The results show that AMM slab allows creating the beam collimation effect similar to that of the bull's eye structure, an enabling technology for practical application due to its simple architecture and cost benefits. The excitation of surface plasmons at the AMM/air interface is derived. The structure of the AMM slab and its impact on beaming performance were analyzed using the effective medium theory and Finite Element Method.

  17. Spatiospectral transmission of a plane-mirror Fabry-Perot interferometer with nonuniform finite-size diffraction beam illuminations.

    Science.gov (United States)

    Lee, Jae Yong; Hahn, Jae Won; Lee, Hai-Woong

    2002-05-01

    The transmission of a plane-mirror Fabry-Perot (PFP) interferometer is theoretically modeled and investigated by treating the spatial and spectral features in a unified manner. A spatiospectral transfer function is formulated and utilized to describe the beam propagation and the multiple-beam interference occurring in an ideal one-dimensional strip PFP interferometer with no diffraction loss. The spatial-frequency filtration of a finite-size beam input not only determines the transmitted spatial beam profile but also plays a crucial role in affecting the overall spectral transmittance. The inherent deviations of the spectral transmittance from what we know as the standard Airy's formula are revealed in diverse aspects, including the less-than-unity peak transmittance, the displacement of a resonance peak frequency, and the asymmetric detuning profile. Our theoretical analysis extends to the misaligned PFP interferometers, such as the cases in which non-normal-incidence beams or wedge-aligned mirrors are used that could severely degrade the effective interferometer finesse.

  18. Influences of size and position of defects on the fatigue life of electron beam welded-aluminum alloy joints

    Institute of Scientific and Technical Information of China (English)

    LU Li; ZHAO Haiyan; CAI Zhipeng; CUI Xiaofang

    2007-01-01

    Defects such as pores influence the fatigue life of electron beam-welded aluminum alloy joints. In this paper,the influences of pore size and position on the fatigue life of aluminum overlap joint are studied. A finite element model (FEM), combined with experimental data, is established to evaluate the fatigue life of overlap joints. By employing this FE model, the effects of pore size and position on fatigue lives of overlap joints are investigated and discussed. From the present study, when pore position is closer to the weld bead tip or the faying surface, the fatigue life decreases. Also, there is a critical size for the pore; when the pore size is larger than the critical value, the fatigue strength decreases sharply.

  19. Beam fanning effect and image storage in Ce: KNSBN crystal

    Institute of Scientific and Technical Information of China (English)

    LI PanLai; GUO QingLin; WANG ZhiJun; PANG LiBin; LIANG BaoLai

    2007-01-01

    A non-synchronously-numerating experimental system is applied in this research. The effect of the incident beam intensity Ⅰ and the beam incident angle θ on beam fanning effect is investigated with a singular beam incident on Ce:KNSBN crystal. The results show that the beam fanning effect strongly depends on Iand θ. The threshold effect of/for the beam fanning in Ce:KNSBN crystal is observed, and the threshold intensity of incident beam keeps the same value of 38.2 mW/cm2 for different θ, and the steady beam fanning intensity Ifsat reaches a peak at θ=15° under the same Ⅰ. In addition, the effect of the incident beam modulated on the beam fanning noise and holographic storage in Ce:KNSBN crystal is studied. And the results suggest that the beam fanning noise is effectively suppressed, and the quality of the reappearance image is greatly improved.

  20. Beam-Beam Effect with an External Noise in LHC

    CERN Document Server

    Ohmi, K; Höfle, Wolfgang; Tomás, R; Zimmermann, F

    2007-01-01

    In absence of synchrotron radiation, proton beams do not have any damping mechanism for incoherent betatron motion. A noise, which kicks beam particles in the transverse plane, gives a coherent betatron amplitude. If the system is linear, the coherent motion is maintained in amplitude. Nonlinear force, beam-beam and beam-electron cloud interactions, cause a decoherence of the betatron motion keeping the amplitude of each beam particle, with the result that an emittance growth arises. We focus only on fast noise with a correlation time of 1-100 turns. Slower noise is less serious, because it is regarded as an adiabatic change like a closed orbit change. As sources of the noise, we consider the bunch by bunch feedback system and phase jitter of cavities which turns to transverse noise via a crab cavity.

  1. Skin-sparing effects of neutron beam filtering materials.

    Science.gov (United States)

    Otte, V A; Almond, P R; Smathers, J B; Attix, F H

    1987-01-01

    The skin-sparing effects of several filtering materials for fast neutron beams were studied under various conditions. A parallel-plate ionization chamber was used for the measurements. The parameters which were studied included field size, distance from filter to ion chamber, filter material, and filter thickness. On the basis of this work, Teflon (polytetrafluoroethylene) was chosen for fabrication of flattening filters and wedges.

  2. Polarization effect in the photon beam collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F. (AN SSSR, Novosibirsk. Inst. Matematiki); Kotkin, G.L.; Panfil' , S.L.; Serbo, V.G. (Novosibirskij Gosudarstvennyj Univ., USSR)

    1983-10-01

    Polarization effects are investigated for collisions of high-energy ..gamma.. beams produced from the Compton scattering of laser light on electrons. To do this, were obtained Stokes parameters Xisub(i), xisub(j) tilde of the ..gamma..-beams, and their average values (xisub(i)), (xisub(j) tilde), as functions of the photon energies and polarizations of the initial beams. The quantities to be measUred in the ..gamma gamma.. collisions are expressed via the average values (xisub(i)xisub(j) tilde), which are in general different from (Hisub(i))(xisub(j) tilde), the fact making the investigation of the polarization effects more complicated. In particular, (xi/sub 3/xi/sub 3/ tilde-xi/sub 11/ tilde) not equal to 0 even if the electron and the laser beams are not Polarized. It is shown that (xisub(i)xisub(j) tilde) approximately (xisub(i))(xisub(j) tilde) for two important limiting cases. Effects due to a correlation between the beams are considered.

  3. Do class size effects differ across grades?

    DEFF Research Database (Denmark)

    Nandrup, Anne Brink

    This paper contributes to the class size literature by analyzing whether short-run class size effects are constant across grade levels in compulsory school. Results are based on administrative data on all pupils enroled in Danish public schools. Identification is based on a government-imposed class...... size cap that creates exogenous variation in class sizes. Significant (albeit modest) negative effects of class size increases are found for children on primary school levels. The effects on math abilities are statistically different across primary and secondary school. Larger classes do not affect...

  4. Polarization effects in collisions of. gamma. beams

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F.; Kotkin, G.L.; Panfil' , S.L.; Serbo, V.G.

    1983-10-01

    We study polarization effects in collisions of high energy ..gamma.. beams obtained in the Compton scattering of laser light on electrons (according to the scheme of I. F. Ginzburg et al., Preprint 81-50, IYaF SO AN SSSR, Novosibirsk, 1981, and JETP Letters 34, 491 (1982)). For this we determine the Stokes parameters of the ..gamma.. beams xi/sub i/ and xi-tilde/sub j/ and their average values and as functions of the photon energy and polarization of the initial beams. The quantities that are measurable in ..gamma gamma.. collisions are expressed in terms of the average values , which, in general, are not equal to , which complicates the study of polarization phenomena. In particular, not =0, even for unpolarized electron and laser beams. It is shown that in two important limiting cases roughly-equal. Effects due to correlation between the beams are studied.

  5. Commissioning experience and first results from the new SLS beam size monitor

    CERN Document Server

    Schlott, V; Saa Hernandez, A; Streun, A; Andersson, A; Breunlin, J; Milas, N

    2013-01-01

    In the context of the TIARA work package “SLS vertical emittance tuning” (SVET), an extremely small vertical beam size of 3.6 $\\mu$m, corresponding to a vertical emittance of 0.9 pm, was verified using an optical monitor based on imaging of $\\pi$-polarized light. Since the existing beam size monitor reached its limit of resolution, a new monitor beam line was designed and installed at the 08BD bending magnet of the Swiss Light Source (SLS) storage ring. Larger magnification and operation at shorter wavelength provide improved spatial resolution. Reflective optics enables convenient switching between different wavelengths. An optical table is located in a hutch outside the storage ring tunnel to provide access during operation. Movable obstacles in the beam path create interference patterns and thus provide redundancy of model based analysis of the images. In this paper we report on our commissioning experience and provide a comparison of the different measurement methods at different wavelengths.

  6. Impact of cone-beam computed tomography on implant planning and on prediction of implant size

    OpenAIRE

    Ludmila Assunção de Mello Pedroso; Robson Rodrigues Garcia; José Luiz Rodrigues Leles; Cláudio Rodrigues Leles; Maria Alves Garcia Santos Silva

    2014-01-01

    The aim was to investigate the impact of cone-beam computed tomography (CBCT) on implant planning and on prediction of final implant size. Consecutive patients referred for implant treatment were submitted to clinical examination, panoramic (PAN) radiography and a CBCT exam. Initial planning of implant length and width was assessed based on clinical and PAN exams, and final planning, on CBCT exam to complement diagnosis. The actual dimensions of the implants placed during surgery were compare...

  7. The effect of object shape and laser beam shape on lidar system resolution

    Science.gov (United States)

    Cheng, Hongchang; Wang, Jingyi; Ke, Jun

    2016-06-01

    In a LIDAR system, a pulsed laser beam is propagated to a scene, and then reflected back by objects. Ideally if the beam diameter and the pulse width are close to zero, then the reflected beam in time domain is similar to a delta function, which can accurately locate an object's position. However, in a practical system, the beam has finite size. Therefore, even if the pulse width is small, an object shape will make the reflected beam stretched along the time axis, then affect system resolution. In this paper, we assume the beam with Gaussian shape. The beam can be formulated as a delta function convolved with a shape function, such as a rectangular function, in time domain. Then the reflected beam can be defined as a system response function convolved with the shape function. We use symmetric objects to analyze the reflected beam. Corn, sphere, and cylinder objects are used to find a LIDAR system's response function. The case for large beam size is discussed. We assume the beam shape is similar to a plane wave. With this assumption, we get the simplified LIDAR system response functions for the three kinds of objects. Then we use tiny spheres to emulate an arbitrary object, and study its effect to the returned beam.

  8. Implementation of depolarization due to beam-beam effects in the beam-beam interaction simulation tool GUINEA-PIG++

    Science.gov (United States)

    Rimbault, C.; Le Meur, G.; Blampuy, F.; Bambade, P.; Schulte, D.

    2009-12-01

    Depolarization is a new feature in the beam-beam simulation tool GUINEA-PIG++ (GP++). The results of this simulation are studied and compared with another beam-beam simulation tool, CAIN, considering different beam parameters for the International Linear Collider (ILC) with a centre-of-mass energy of 500 GeV.

  9. Modeling size effect in the SMA response: a gradient theory

    Science.gov (United States)

    Tabesh, Majid; Boyd, James G.; Lagoudas, Dimitris C.

    2014-03-01

    Shape memory alloys (SMAs) show size effect in their response. The critical stresses, for instance, for the start of martensite and austenite transformations are reported to increase in some SMA wires for diameters below 100 μm. Simulation of such a behavior cannot be achieved using conventional theories that lack an intrinsic length scale in their constitutive modeling. To enable the size effect, a thermodynamically consistent constitutive model is developed, that in addition to conventional internal variables of martensitic volume fraction and transformation strain, contains the spatial gradient of martensitic volume fraction as an internal variable. The developed theory is simplified for 1D cases and analytical solutions for pure bending of SMA beams are presented. The gradient model captures the size effect in the response of the studied SMA structures.

  10. Size effects in thin films

    CERN Document Server

    Tellier, CR; Siddall, G

    1982-01-01

    A complete and comprehensive study of transport phenomena in thin continuous metal films, this book reviews work carried out on external-surface and grain-boundary electron scattering and proposes new theoretical equations for transport properties of these films. It presents a complete theoretical view of the field, and considers imperfection and impurity effects.

  11. Biostimulative Effect Of Laser Beams

    Science.gov (United States)

    Mester, E.

    1981-05-01

    We report on experiences gained in healing clinical cases treated with He-Ne and Argon-laser grouped according to etiology. In order to elucidate the action mechanism of the bioregulatory process, the following experiments were carried out: 1. Serial electron-microscopic and radioactivity studies of samples obtained from human ulcers; 2. Chemical transfer of stimulating substrate on human leukocyte population; 3. Enzyme histochemical studies in experiments on rats; 4. Study of vascularization with the "ear chamber" technique carried out on rabbit's ear; 5. The increase of tensile strength in rats; 6. Biochemical demonstration of the RNA, DNA, albumin synthesis on human fibrocyte-cultures; 7.a, 7.b, Immunological studies; 8. Prostaglandin producing effect. The discovery of laser opened up new prospects in the field of the biological research and medical use.

  12. Cobalt particle size effects in catalysis

    NARCIS (Netherlands)

    den Breejen, J.P.

    2010-01-01

    Aim of the work described in this thesis was first to investigate cobalt particle size effects in heterogeneous catalysis. The main focus was to provide a deeper understanding of the origin of the cobalt particle size effects in Fischer-Tropsch (FT) catalysis in which synthesis gas (H2/CO) is conver

  13. Size and value effects in Suriname

    NARCIS (Netherlands)

    D.S. Bodeutsch (Denice); Ph.H.B.F. Franses (Philip Hans)

    2013-01-01

    markdownabstract__Abstract__ This paper studies the link between stock returns and size and book-to-market equity effects for 10 companies listed at the Suriname Stock Exchange. We analyze the cross-sectional variation in average returns and we find that there is apparently no size effect, but the

  14. Effect size for dichotomous outcome measures

    Institute of Scientific and Technical Information of China (English)

    Yuanjia WANG; Naihua DUAN

    2011-01-01

    @@ Effect size for continuous outcome measures was discussed in our previous column[1].In this column we discuss several widely used effect size measures for dichotomous (Yes/No) outcome measures such as mortality,relapse,cure,discontinuation of treatment,and so forth.

  15. Determination of size-specific exposure settings in dental cone-beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Pauwels, Ruben [Chulalongkorn University, Department of Radiology, Faculty of Dentistry, Patumwan, Bangkok (Thailand); University of Leuven, OMFS-IMPATH Research Group, Department of Imaging and Pathology, Biomedical Sciences Group, Leuven (Belgium); Jacobs, Reinhilde [University of Leuven, OMFS-IMPATH Research Group, Department of Imaging and Pathology, Biomedical Sciences Group, Leuven (Belgium); Bogaerts, Ria [University of Leuven, Laboratory of Experimental Radiotherapy, Department of Oncology, Biomedical Sciences Group, Leuven (Belgium); Bosmans, Hilde [University of Leuven, Medical Physics and Quality Assessment, Department of Imaging and Pathology, Biomedical Sciences Group, Leuven (Belgium); Panmekiate, Soontra [Chulalongkorn University, Department of Radiology, Faculty of Dentistry, Patumwan, Bangkok (Thailand)

    2017-01-15

    To estimate the possible reduction of tube output as a function of head size in dental cone-beam computed tomography (CBCT). A 16 cm PMMA phantom, containing a central and six peripheral columns filled with PMMA, was used to represent an average adult male head. The phantom was scanned using CBCT, with 0-6 peripheral columns having been removed in order to simulate varying head sizes. For five kV settings (70-90 kV), the mAs required to reach a predetermined image noise level was determined, and corresponding radiation doses were derived. Results were expressed as a function of head size, age, and gender, based on growth reference charts. The use of 90 kV consistently resulted in the largest relative dose reduction. A potential mAs reduction ranging from 7 % to 50 % was seen for the different simulated head sizes, showing an exponential relation between head size and mAs. An optimized exposure protocol based on head circumference or age/gender is proposed. A considerable dose reduction, through reduction of the mAs rather than the kV, is possible for small-sized patients in CBCT, including children and females. Size-specific exposure protocols should be clinically implemented. (orig.)

  16. The Possibility of Noninvasive Micron High Energy Electron Beam Size Measurement Using Diffraction Radiation

    CERN Document Server

    Naumenko, Gennady; Aryshev, Alexander; Cline, David B; Fukui, Yasuo; Hamatsu, Ryosuke; Hayano, Hitoshi; Karataev, Pavel; Muto, Toshiya; Potylitsyn, Alexander; Ross, Marc; Urakawa, Junji

    2005-01-01

    During the last years a noninvasive method for beam size measurement based on the optical diffraction radiation (ODR) has been in progress (P. Karataev, et al., Physical Review Letters 93, 244802 (2004). However this technique encounters with hard sensitivity limitation for electron energies larger than several GeV. For example, for SLAC conditions the sensitivity of this method is 4 orders smaller than an appropriate one. We suggest to use a "dis-phased" slit target, where two semi-planes are turned with respect to each other at a small "dis-phased" angle. In order to ensure the interference between the diverged radiation beams we use a cylindrical lens. This method has much better sensitivity and resolution. A "dis-phased" angle 10 milliradians gives the optimal sensitivity to 5 microns transversal beam size. The theoretical model for calculating the ODR radiation from such targets (including focusing by cylindrical lens) is presented. It is shown that the sensitivity of this method does not depend on the L...

  17. In-beam evaluation of a medium-size Resistive-Plate WELL gaseous particle detector

    CERN Document Server

    Moleri, L

    2016-01-01

    In-beam evaluation of a fully-equipped medium-size 30$\\times$30 cm$^2$ Resistive Plate WELL (RPWELL) detector is presented. It consists here of a single element gas-avalanche multiplier with Semitron ESD225 resistive plate, 1 cm$^2$ readout pads and APV25/SRS electronics. Similarly to previous results with small detector prototypes, stable operation at high detection efficiency (>98%) and low average pad multiplicity (~1.2) were recorded with 150 GeV muon and high-rate pion beams, in Ne/(5%CH$_4$), Ar/(5%CH$_4$) and Ar/(7%CO$_2$). This is an important step towards the realization of robust detectors suitable for applications requiring large-area coverage; among them Digital Hadron Calorimetry.

  18. In-beam evaluation of a medium-size Resistive-Plate WELL gaseous particle detector

    Science.gov (United States)

    Moleri, L.; Amaro, F. D.; Arazi, L.; Azevedo, C. D. R.; Breskin, A.; Coimbra, A. E. C.; Oliveri, E.; Pereira, F. A.; Shaked Renous, D.; Schaarschmidt, J.; dos Santos, J. M. F.; Veloso, J. F. C. A.; Bressler, S.

    2016-09-01

    In-beam evaluation of a fully-equipped medium-size 30 × 30 cm2 Resistive Plate WELL (RPWELL) detector is presented. It consists here of a single element gas-avalanche multiplier with Semitron ESD225 resistive plate, 1 cm2 readout pads and APV25/SRS electronics. Similarly to previous results with small detector prototypes, stable operation at high detection efficiency (> 98%) and low average pad multiplicity (~ 1.2) were recorded with 150 GeV muon and high-rate pion beams, in Ne/(5%CH4), Ar/(5%CH4) and Ar/(7%CO2). This is an important step towards the realization of robust detectors suitable for applications requiring large-area coverage; among them Digital Hadron Calorimetry.

  19. Structural effect of size on interracial friendship.

    Science.gov (United States)

    Cheng, Siwei; Xie, Yu

    2013-04-30

    Social contexts exert structural effects on individuals' social relationships, including interracial friendships. In this study, we posit that, net of group composition, total context size has a distinct effect on interracial friendship. Under the assumptions of (i) maximization of preference in choosing a friend, (ii) multidimensionality of preference, and (iii) preference for same-race friends, we conducted analyses using microsimulation that yielded three main findings. First, increased context size decreases the likelihood of forming an interracial friendship. Second, the size effect increases with the number of preference dimensions. Third, the size effect is diluted by noise, i.e., the random component affecting friendship formation. Analysis of actual friendship data among 4,745 American high school students yielded results consistent with the main conclusion that increased context size promotes racial segregation and discourages interracial friendship.

  20. Effective population size of korean populations.

    Science.gov (United States)

    Park, Leeyoung

    2014-12-01

    Recently, new methods have been developed for estimating the current and recent changes in effective population sizes. Based on the methods, the effective population sizes of Korean populations were estimated using data from the Korean Association Resource (KARE) project. The overall changes in the population sizes of the total populations were similar to CHB (Han Chinese in Beijing, China) and JPT (Japanese in Tokyo, Japan) of the HapMap project. There were no differences in past changes in population sizes with a comparison between an urban area and a rural area. Age-dependent current and recent effective population sizes represent the modern history of Korean populations, including the effects of World War II, the Korean War, and urbanization. The oldest age group showed that the population growth of Koreans had already been substantial at least since the end of the 19th century.

  1. Automatic Calibration Method of Voxel Size for Cone-beam 3D-CT Scanning System

    CERN Document Server

    Yang, Min; Liu, Yipeng; Men, Fanyong; Li, Xingdong; Liu, Wenli; Wei, Dongbo

    2013-01-01

    For cone-beam three-dimensional computed tomography (3D-CT) scanning system, voxel size is an important indicator to guarantee the accuracy of data analysis and feature measurement based on 3D-CT images. Meanwhile, the voxel size changes with the movement of the rotary table along X-ray direction. In order to realize the automatic calibration of the voxel size, a new easily-implemented method is proposed. According to this method, several projections of a spherical phantom are captured at different imaging positions and the corresponding voxel size values are calculated by non-linear least square fitting. Through these interpolation values, a linear equation is obtained, which reflects the relationship between the rotary table displacement distance from its nominal zero position and the voxel size. Finally, the linear equation is imported into the calibration module of the 3D-CT scanning system, and when the rotary table is moving along X-ray direction, the accurate value of the voxel size is dynamically expo...

  2. Size Effects on the Strength of Metals

    DEFF Research Database (Denmark)

    Huang, Xiaoxu

    2014-01-01

    The grain size effect and the specimen size effect on the strength of metals are briefly reviewed with respect to their history and current status of research. It is revealed that the fundamental strengthening mechanisms responsible for these two types of size effect are to increase the resistance...... to dislocation motion and to dislocation generation, respectively. It is shown that both strengthening mechanisms take place in some nanostructured metals, which leads to a suggestion to use these two mechanisms for optimizing the strength and ductility of nanostructured metals. This suggestion is verified...

  3. Nanocoatings size effect in nanostructured films

    CERN Document Server

    Aliofkhazraei, Mahmood

    2014-01-01

    Size effect in structures has been taken into consideration over the last years. In comparison with coatings with micrometer-ranged thickness, nanostructured coatings usually enjoy better and appropriate properties, such as strength and resistance. These coatings enjoy unique magnetic properties and are used with the aim of producing surfaces resistant against erosion, lubricant system, cutting tools, manufacturing hardened sporadic alloys, being resistant against oxidation and corrosion. This book reviews researches on fabrication and classification of nanostructured coatings with focus on size effect in nanometric scale. Size effect on electrochemical, mechanical and physical properties of nanocoatings are presented.

  4. Plasticity size effects in voided crystals

    DEFF Research Database (Denmark)

    Hussein, M.I.; Borg, Ulrik; Niordson, Christian Frithiof

    2008-01-01

    and strain gradient plasticity formulations predict a negligible size effect under shear loading. By contrast, under equi-biaxial loading both plasticity formulations predict a strong size dependence with the flow strength approximately scaling inversely with the void spacing. Excellent agreement is obtained...

  5. Board Size Effects in Closely Held Corporations

    DEFF Research Database (Denmark)

    Bennedsen, Morten; Kongsted, H.C.; Meisner Nielsen, Kasper

    2004-01-01

    Previous work on board size effects in closely held corporationshas established a negative correlation between board size and firm performance.We argue that this work has been incomplete in analysing the causalrelationship due to lack of ownership information and weak identificationstrategies in ...

  6. Relativistic Beaming Effect in Fermi Blazars

    Indian Academy of Sciences (India)

    J. H. Fan; D. Bastieri; J. H. Yang; Y. Liu; D. X. Wu; S. H. Li

    2014-09-01

    The most identified sources observed by Fermi/LAT are blazars, based on which we can investigate the emission mechanisms and beaming effect in the -ray bands for blazars. Here, we used the compiled around 450 Fermi blazars with the available X-ray observations to estimate their Doppler factors and compared them with the integral -ray luminosity in the range of 1–100 GeV. It is interesting that the integral -ray luminosity is closely correlated with the estimated Doppler factor, log = (2.95 ± 0.09) log + 43.59 ± 0.08 for the whole sample. When the dependence of the correlation between them and the X-ray luminosity is removed, the correlation is still strong, which suggests that the -ray emissions are strongly beamed.

  7. Design and Implementation of a Micron-Sized Electron Column Fabricated by Focused Ion Beam Milling

    CERN Document Server

    Wicki, Flavio; Escher, Conrad; Fink, Hans-Werner

    2015-01-01

    We have designed, fabricated and tested a micron-sized electron column with an overall length of about 700 microns comprising two electron lenses; a micro-lens with a minimal bore of 1 micron followed by a second lens with a bore of up to 50 microns in diameter to shape a coherent low-energy electron wave front. The design criteria follow the notion of scaling down source size, lens-dimensions and kinetic electron energy for minimizing spherical aberrations to ensure a parallel coherent electron wave front. All lens apertures have been milled employing a focused ion beam and could thus be precisely aligned within a tolerance of about 300 nm from the optical axis. Experimentally, the final column shapes a quasi-planar wave front with a minimal full divergence angle of 4 mrad and electron energies as low as 100 eV.

  8. Effects of electron beam irradiation on tin dioxide gas sensors

    Indian Academy of Sciences (India)

    Zheng Jiao; Xiaojuan Wan; Bing Zhao; Huijiao Guo; Tiebing Liu; Minghong Wu

    2008-02-01

    In this paper, the effects of electron beam irradiation on the gas sensing performance of tin dioxide thin films toward H2 are studied. The tin dioxide thin films were prepared by ultrasonic spray pyrolysis. The results show that the sensitivity increased after electron beam irradiation. The electron beam irradiation effects on tin dioxide thin films were simulated and the mechanism was discussed.

  9. Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor

    Science.gov (United States)

    Alexander, J. P.; Chatterjee, A.; Conolly, C.; Edwards, E.; Ehrlichman, M. P.; Flanagan, J. W.; Fontes, E.; Heltsley, B. K.; Lyndaker, A.; Peterson, D. P.; Rider, N. T.; Rubin, D. L.; Seeley, R.; Shanks, J.

    2014-12-01

    We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring e+ and e- beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of 10 - 100 μm on a turn-by-turn, bunch-by-bunch basis at e± beam energies of ~ 2 - 5 GeV. x-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.

  10. Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor

    CERN Document Server

    Alexander, J P; Conolly, C; Edwards, E; Ehrlichman, M P; Flanagan, J W; Fontes, E; Heltsley, B K; Lyndaker, A; Peterson, D P; Rider, N T; Rubin, D L; Seeley, R; Shanks, J

    2014-01-01

    We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring $e^+$ and $e^-$ beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of $10-100~\\mu$m on a turn-by-turn, bunch-by-bunch basis at $e^\\pm$ beam energies of $\\sim2-5~$GeV. X-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.

  11. 反复荷载作用下高强混凝土梁受弯性能尺寸效应试验研究%Experimental study on size effect of flexural behavior of reinforced high-strength concrete beams subjected to cyclic loading

    Institute of Scientific and Technical Information of China (English)

    车轶; 王金金; 郑新丰; 宋玉普

    2013-01-01

    Six reinforced high-strength concrete beam-type specimens of different sizes with stubs columns in the middle were fabricated,and tested under low-cycle reversed loading to investigate the effect of depths on flexural behavior of reinforced high-strength concrete beams.The parameters of specimens varied in depths and ratios of longitudinal reinforcement on the top of cross sections,while the depth-width ratios of cross sections,shear span-todepth ratios and ratios of longitudinal reinforcement on the bottom of cross sections and stirrups were constant.C70 concrete was used to cast the specimens and HRB 400 steel bars were used as longitudinal reinforcement.The influence of beam depths on nominal cracking moment,nominal yield moment,nominal ultimate moment,displacement ductility,plastic rotation capacity,stiffness degradation and energy dissipation capacity of high-strength concrete beams were investigated.It is shown that there is no apparent size effect observed on nominal cracking moment,nominal yield moment and nominal ultimate moment of reinforced high-strength concrete beams,and that all specimens subjected to cyclic loading clearly show similar stiffness degradation which is independent of beam depths,while the displacement ductility factors,rotational capacity as well as work index of specimens decrease with increasing of depths,showing significant size effect.%设计了6根不同几何尺寸的中部带有短柱的高强混凝土梁式试件,进行受弯性能低周反复荷载试验,研究试件截面高度对反复荷载作用下高强混凝土梁受弯性能的影响.试件截面高度和上部纵向钢筋配筋率不同,截面长宽比、剪跨比、底部纵向钢筋配筋率和配箍率等参数相同.采用C70高强混凝土,纵向受力钢筋采用HRB400级钢筋.分析了截面高度对高强混凝土梁名义开裂弯矩、名义屈服弯矩、名义极限弯矩、位移延性、塑性转动能力、刚度退化以及耗能能力的影响.研究

  12. The effect of beam directivity on the inspection of anisotropic materials using ultrasonic arrays

    Science.gov (United States)

    Lane, C. J. L.; Wilcox, P. D.

    2012-05-01

    The beam directivity from an ultrasonic transducer in isotropic materials is well documented. However, beam directivities in elastically anisotropic materials and their effect on ultrasonic NDE inspection has been investigated far less extensively. In this paper, analytical and numerical finite element models are developed to predict the beam directivity in a single crystal nickel-based superalloy. This material is highly anisotropic and is used widely in the gas-turbine industry. The developed models are used to investigate the effect of the crystallographic orientation on the beam directivity. In turn, the effect of beam directivity on defect detection sensitivity and characterization capability using an ultrasonic array is demonstrated. It is shown that the effect is particularly important for the accurate sizing of small defects.

  13. Measuring wage effects of plant size

    DEFF Research Database (Denmark)

    Albæk, Karsten; Arai, Mahmood; Asplund, Rita

    1998-01-01

    There are large plant size–wage effects in the Nordic countries after taking into account individual and job characteristics as well as systematical sorting of the workers into various plant-sizes. The plant size–wage elasticities we obtain are, in contrast to other dimensions of the wage distrib......–wage elasticity. Our results indicate that using size–class midpoints yields essentially the same results as using exact measures of plant size...

  14. Effect of Firing on Cracking and Warping of Clay Beams

    Directory of Open Access Journals (Sweden)

    Nawab Ali Lakho

    2016-04-01

    Full Text Available Reinforced baked clay beams may be considered to be a substitute of reinforced cement concrete beams in order to build low cost houses. The baking of these clay beams can pose problems such as cracking and warping. This paper presents the effect of different treatments applied to clay beams during baking to reduce cracking and warping. These clay beams were baked in pottery kiln in which the temperature could not be raised to the extent of fusing of clay beams placed at bottom of firing chamber. As expected, the beams were not baked properly and a number of them got cracked. Then these beams were baked in a commercial Hoffman?s kiln. The beams, in preheating stage, were moistened to full depth due to humidity and moisture of flue gases. As a result, the beams cracked and warped at the time of firing. In order to avoid the beams from being moistened by the moisture of the flue gases, different treatments were opted. Firstly, these beams were covered with plastic sheet, the cracks were reduced to some extent. Secondly, double layer of mud, with a layer of gunny bags between them, was applied. Consequently, a few cracks occurred in the beams. The treatments suggested in this paper can be used for baking of clay beams in Hoffman?s kiln at commercial level

  15. Nano-sized Thin Films Fabricated by Ion Beam Sputtering and Its Properties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nanoscale thick amorphous Ni-Cr alloy thin films were fabricated by low-energy ion beam sputtering technology; then the as-deposited samples experienced rapid thermal process to realize the transformation from amorphous to crystalline state. The film thickness was measured with α-stylus surface profiler, the structure and the compositions of the films were confirmed by low angle X-ray diffraction and scanning auger electron microprobe respectively, and the surface topography was characterized by scanning electron microscope and scanning probe microscope. Electrical property of the films was measured by fourpoint probe. The experimental results illustrate that the combined processes of ion beam sputtering and rapid thermal process are effective for fabrication nanoscale Ni-Cr alloy thin film with good properties.

  16. Operation of the CESR-TA vertical beam size monitor at $E_{\\rm b}$=4 GeV

    CERN Document Server

    Alexander, J P; Edwards, E; Flanagan, J W; Fontes, E; Heltsley, B K; Lyndaker, A; Peterson, D P; Rider, N T; Rubin, D L; Seeley, R; Shanks, J

    2015-01-01

    We describe operation of the CESR-TA vertical beam size monitor (xBSM) with $e^\\pm$ beams with $E_{\\rm b}$=4 GeV. The xBSM measures vertical beam size by imaging synchrotron radiation x-rays through an optical element onto a detector array of 32 InGaAs photodiodes with 50 $\\mu$m pitch. The device has previously been successfully used to measure vertical beam sizes of 10-100 $\\mu$m on a bunch-by-bunch, turn-by-turn basis at $e^\\pm$ beam energies of $\\sim$2 GeV and source magnetic fields below 2.8 kG, for which the detector required calibration for incident x-rays of 1-5 keV. At $E_{\\rm b}=4.0$ GeV and $B$=4.5 kG, however, the incident synchrotron radiation spectrum extends to $\\sim$20 keV, requiring calibration of detector response in that regime. Such a calibration is described and then used to analyze data taken with several different thicknesses of filters in front of the detector. We obtain a relative precision of better than 4% on beam size measurement from 15-100 $\\mu$m over several different ranges of x...

  17. A Simplified Analysis of the Brazier Effect in Composite Beams

    DEFF Research Database (Denmark)

    Damkilde, Lars; Lund, B.

    2009-01-01

    In the design of windturbine blades composite beams are often used as the load bearing element. The beam is primarily subjected to bending moments, and the deformations are relatively large. The large displacements result in a kind of ovalization of the beam section, the so-called Brazier effect...

  18. Numerical Simulation of Beam-Beam Effects in the Proposed Electron-Ion Colider at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Balsa Terzic, Yuhong Zhang

    2010-05-01

    One key limiting factor to a collider luminosity is beam-beam interactions which usually can cause serious emittance growth of colliding beams and fast reduction of luminosity. Such nonlinear collective beam effect can be a very serious design challenge when the machine parameters are pushed into a new regime. In this paper, we present simulation studies of the beam-beam effect for a medium energy ring-ring electron-ion collider based on CEBAF.

  19. Understanding the effect size and its measures.

    Science.gov (United States)

    Ialongo, Cristiano

    2016-01-01

    The evidence based medicine paradigm demands scientific reliability, but modern research seems to overlook it sometimes. The power analysis represents a way to show the meaningfulness of findings, regardless to the emphasized aspect of statistical significance. Within this statistical framework, the estimation of the effect size represents a means to show the relevance of the evidences produced through research. In this regard, this paper presents and discusses the main procedures to estimate the size of an effect with respect to the specific statistical test used for hypothesis testing. Thus, this work can be seen as an introduction and a guide for the reader interested in the use of effect size estimation for its scientific endeavour.

  20. Synthesis of Large-Sized Single-Crystal Hexagonal Boron Nitride Domains on Nickel Foils by Ion Beam Sputtering Deposition.

    Science.gov (United States)

    Wang, Haolin; Zhang, Xingwang; Liu, Heng; Yin, Zhigang; Meng, Junhua; Xia, Jing; Meng, Xiang-Min; Wu, Jinliang; You, Jingbi

    2015-12-22

    Large-sized single-crystal h-BN domains with a lateral size up to 100 μm are synthesized on Ni foils by ion-beam sputtering deposition. The nucleation density of h-BN is dramatically decreased by reducing the concentrations of both active sites and species on the Ni surface through a brief in situ pretreatment of the substrate and optimization of the growth parameters, enabling the growth of large-sized domains.

  1. A Note on the Sagnac Effect for Matter Beams

    CERN Document Server

    Ruggiero, Matteo Luca

    2014-01-01

    We study the Sagnac effect for matter beams, in order to estimate the kinematic corrections to the basic formula, deriving from the position and the extension of the interferometer, and discuss the analogy with the Aharonov-Bohm effect. We show that the formula for the Sagnac time delay is the same for matter and light beams in arbitrary stationary space-times, provided that a suitable condition on the speed of the beams is fulfilled. Hence, the same results obtained for light beams apply to matter beams.

  2. The effects of betatron phase advances on beam-beam and its compensation in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y.; Fischer, W.; Gu, X.; Tepikian, S.; Trbojevic, D.

    2011-03-28

    In this article we perform simulation studies to investigate the effects of betatron phase advances between the beam-beam interaction points on half-integer resonance driving term, second order chromaticty and dynamic aperture in RHIC. The betatron phase advances are adjusted with artificial matrices inserted in the middle of arcs. The lattices for the 2011 RHIC polarized proton (p-p) run and 2010 RHIC Au-Au runs are used in this study. We also scan the betatron phase advances between IP8 and the electron lens for the proposed Blue ring lattice with head-on beam-beam compensation.

  3. TRANSIENT BEAM LOADING EFFECTS IN RF SYSTEMS IN JLEIC

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Guo, Jiquan [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, Shaoheng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    The pulsed electron bunch trains generated from the Continuous Electron Beam Accelerator Facility (CEBAF) linac to inject into the proposed Jefferson Lab Electron Ion Collider (JLEIC) e-ring will produce transient beam loading effects in the Superconducting Radio Frequency (SRF) systems that, if not mitigated, could cause unacceptably large beam energy deviation in the injection capture, or exceed the energy acceptance of CEBAF’s recirculating arcs. In the electron storage ring, the beam abort or ion clearing gaps or uneven bucket filling can cause large beam phase transients in the (S)RF cavity control systems and even beam loss due to Robinson instability. We have first analysed the beam stability criteria in steady state and estimated the transient effect in Feedforward and Feedback RF controls. Initial analytical models for these effects are shown for the design of the JLEIC e-ring from 3GeV to 12GeV.

  4. Creep Effects in Pultruded FRP Beams

    Science.gov (United States)

    Boscato, G.; Casalegno, C.; Russo, S.

    2016-03-01

    The paper presents results of two creep tests on pultruded open-section GFRP beams aimed to evaluate the long-term deformations, the residual deflection after unloading, and the influence of creep strains on the flexuraltorsional buckling phenomenon. Two beams were subjected to a constant load for about one year. Then one of the beams was unloaded to evaluate its residual deflection. For the other beam, the load was increased up to failure, and the residual buckling strength was compared with that of a similar beam tested up to failure. The parameters of the Findley power law are evaluated, and the experimental results are compared with those of numerical analyses and with available formulations for prediction of the time-dependent properties of composite beams. Results of the investigation testify, in particular, to a noninsignificant time-dependent increment in deflections of the beams and to a significant reduction in their buckling strength due to creep deformations.

  5. Size Effect in Tension Perpendicular to Grain

    DEFF Research Database (Denmark)

    Astrup, Thomas; Clorius, Christian Odin; Hoffmeyer, Preben;

    2004-01-01

    The strength of wood is reduced when the stressed volume is increased. The phenomenon is termed size effect and is often explained as being stochastic in the sense that the probability of weak locations occurring in the wood increases with increased volume. This paper presents a hypothesis where ...

  6. Structural effect of size on interracial friendship

    OpenAIRE

    Cheng, Siwei; Xie, Yu

    2013-01-01

    Social contexts exert structural effects on individuals’ social relationships, including interracial friendships. In this study, we posit that, net of group composition, total context size has a distinct effect on interracial friendship. Under the assumptions of (i) maximization of preference in choosing a friend, (ii) multidimensionality of preference, and (iii) preference for same-race friends, we conducted analyses using microsimulation that yielded three main findings. First, increased co...

  7. Size effects on generation recombination noise

    OpenAIRE

    Gomila, G.; Reggiani, L.

    2002-01-01

    We carry out an analytical theory of generation-recombination noise for a two level resistor model which goes beyond those presently available by including the effects of both space charge fluctuations and diffusion current. Finite size effects are found responsible for the saturation of the low frequency current spectral density at high enough applied voltages. The saturation behaviour is controlled essentially by the correlations coming from the long range Coulomb interaction. It is suggest...

  8. The field size matters: low dose external beam radiotherapy for thumb carpometacarpal osteoarthritis : Importance of field size.

    Science.gov (United States)

    Kaltenborn, Alexander; Bulling, Elke; Nitsche, Mirko; Carl, Ulrich Martin; Hermann, Robert Michael

    2016-08-01

    The purpose of this work was to evaluate the efficacy of low-dose radiotherapy (RT) for thumb carpometacarpal osteoarthritis (rhizarthrosis). The responses of 84 patients (n = 101 joints) were analyzed 3 months after therapy (n = 65) and at 12 months (n = 27). Patients were treated with 6 fractions of 1 Gy, two times a week, with a linear accelerator. At the end of therapy, about 70 % of patients reported a response (partial remission or complete remission), 3 months later about 60 %, and 1 year after treatment 70 %. In univariate regression analysis, higher patient age and field size greater than 6 × 4 cm were associated with response to treatment, while initial increase of pain under treatment was predictive for treatment failure. Duration of RT series (more than 18 days), gender, time of symptoms before RT, stress pain or rest pain, or prior ortheses use, injections, or surgery of the joint were not associated with treatment efficacy. In multivariate regression analysis, only field size and initial pain increase were highly correlated with treatment outcome. In conclusion, RT represents a useful treatment option for patients suffering from carpometacarpal osteoarthritis. In contrast to other benign indications, a larger field size (>6 × 4 cm) seems to be more effective than smaller fields and should be evaluated in further prospective studies.

  9. Accurate determination of electronic transport properties of silicon wafers by nonlinear photocarrier radiometry with multiple pump beam sizes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qian [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Bincheng, E-mail: bcli@uestc.ac.cn [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-12-07

    In this paper, photocarrier radiometry (PCR) technique with multiple pump beam sizes is employed to determine simultaneously the electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) of silicon wafers. By employing the multiple pump beam sizes, the influence of instrumental frequency response on the multi-parameter estimation is totally eliminated. A nonlinear PCR model is developed to interpret the PCR signal. Theoretical simulations are performed to investigate the uncertainties of the estimated parameter values by investigating the dependence of a mean square variance on the corresponding transport parameters and compared to that obtained by the conventional frequency-scan method, in which only the frequency dependences of the PCR amplitude and phase are recorded at single pump beam size. Simulation results show that the proposed multiple-pump-beam-size method can improve significantly the accuracy of the determination of the electronic transport parameters. Comparative experiments with a p-type silicon wafer with resistivity 0.1–0.2 Ω·cm are performed, and the electronic transport properties are determined simultaneously. The estimated uncertainties of the carrier lifetime, diffusion coefficient, and front surface recombination velocity are approximately ±10.7%, ±8.6%, and ±35.4% by the proposed multiple-pump-beam-size method, which is much improved than ±15.9%, ±29.1%, and >±50% by the conventional frequency-scan method. The transport parameters determined by the proposed multiple-pump-beam-size PCR method are in good agreement with that obtained by a steady-state PCR imaging technique.

  10. Thermal effects in orthotropic porous elastic beams

    Science.gov (United States)

    Iaşan, D.

    2009-01-01

    This paper is concerned with the linear theory of anisotropic porous elastic bodies. The extension and bending of orthotropic porous elastic cylinders subjected to a plane temperature field is investigated. The work is motivated by the recent interest in the using of the orthotropic porous elastic solid as model for bones and various engineering materials. First, the thermoelastic deformation of inhomogeneous beams whose constitutive coefficients are independent of the axial coordinate is studied. Then, the extension and bending effects in orthotropic cylinders reinforced by longitudinal rods are investigated. The three-dimensional problem is reduced to the study of two-dimensional problems. The method is used to solve the problem of an orthotropic porous circular cylinder with a special kind of inhomogeneity.

  11. Manufacturing of the full size prototype of the ion source for the ITER neutral beam injector – The SPIDER beam source

    Energy Technology Data Exchange (ETDEWEB)

    Pavei, Mauro, E-mail: mauro.pavei@igi.cnr.it [Consorzio RFX, C.so Stati Uniti 4, I-35127, Padova (Italy); Boilson, Deirdre [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Bonicelli, Tullio [Fusion for Energy, C/Joseph Pla 2, 08019 Barcelona (Spain); Boury, Jacques [Thales Electron Devices, Velizy Villacoublay (France); Bush, Michael [Galvano-T GmbH, T, Raiffeisenstraße 8, 51570 Windeck (Germany); Ceracchi, Andrea; Faso, Diego [CECOM S.r.l., Via Tiburtina – Guidonia Montecelio, Roma (Italy); Graceffa, Joseph [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Heinemann, Bernd [Max-Planck-Institut für Plasmaphysik, D-85740 Garching (Germany); Hemsworth, Ronald [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Lievin, Christophe [Thales Electron Devices, Velizy Villacoublay (France); Marcuzzi, Diego [Consorzio RFX, C.so Stati Uniti 4, I-35127, Padova (Italy); Masiello, Antonio [Fusion for Energy, C/Joseph Pla 2, 08019 Barcelona (Spain); Sczepaniak, Bernd [Galvano-T GmbH, T, Raiffeisenstraße 8, 51570 Windeck (Germany); Singh, Mahendrajit [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Toigo, Vanni; Zaccaria, Pierluigi [Consorzio RFX, C.so Stati Uniti 4, I-35127, Padova (Italy)

    2015-10-15

    Highlights: • Negative ion sources are key components of neutral beam injectors for nuclear fusion. • The SPIDER experiment aims to optimize the negative ion source of MITICA and HNB. • The SPIDER Beam Source manufacturing is currently on-going. • Manufacturing and assembling technological issues encountered are presented. - Abstract: In ITER, each heating neutral beam injector (HNB) will deliver about 16.5 MW heating power by accelerating a 40 A deuterium negative ion beam up to the energy of 1 MeV. The ions are generated inside a caesiated negative ion source, where the injected H{sub 2}/D{sub 2} is ionized by a radio frequency electromagnetic field. The SPIDER test bed, currently being manufactured, is going to be the ion source test facility for the full size ion source of the HNBs and of the diagnostic neutral beam injector of ITER. The SPIDER beam source comprises an ion source with 8 radio-frequency drivers and a three-grid system, providing an overall acceleration up to energies of about 100 keV [1]. SPIDER represents a substantial step forward between the half ITER size ion source, which is currently being tested at the ELISE test bed in IPP-Garching, and the negative ion sources to be used on ITER, in terms of layout, dimensions and operating parameters. The SPIDER beam source will be housed inside a vacuum vessel which will be equipped with a beam dump and a graphite diagnostic calorimeter. The manufacturing design of the main parts of the SPIDER beam source has been completed and many of the tests on the prototypes have been successfully passed. The most complex parts, from the manufacturing point of view, of the ion source and the accelerator, developed by galvanic deposition of copper are being manufactured. The manufacturing phase will be completed within 2015, when the assembly of the device will start at the PRIMA site, in Padova (I). The paper describes the status of the procurement, the adaptations operated on the design of the beam

  12. Resolving Two Beams in Beam Splitters with a Beam Position Monitor

    Science.gov (United States)

    Kurennoy, Sergey

    2002-04-01

    The beam transport system for the Advanced Hydrotest Facility (AHF) anticipates multiple beam splitters. Monitoring two transversely separated beams in a common beam pipe in the splitter sections imposes certain requirements on beam diagnostics for these sections. We explore a two-beam system in a generic beam monitor and study the feasibility of resolving the transverse positions of the two beams with one diagnostics device. Effects of unequal beam currents and of finite transverse sizes of the beams are explored analytically for both the ultra relativistic case and the long-wavelength limit.

  13. The compressive buckling and size effect of single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuzhou, E-mail: yuzhousun@126.com; Zhu, Yanzhi; Li, Dongxia [Department of Civil Engineering and Architecture, Zhongyuan University of Technology, Zhengzhou (China)

    2015-03-10

    A higher-order Bernoulli-Euler beam model is developed to investigate the compressive buckling and size effect of single-walled carbon nanotubes by using a higher-order continuum relationship that has been previously proposed by the present authors. The second-order deformation gradients with respect to the axial direction are also considered, and the beam parameters are obtained by calculating the constitutive response around the circumference. The critical compressive force is analytically provided, and the size effect is studied by estimating the contribution of the higher-order terms.

  14. Size effects in plastic hinges of reinforced concrete members

    NARCIS (Netherlands)

    Bigaj-van Vliet, A.J.; Walraven, J.C.

    2002-01-01

    Reasons for size dependence of rotation capacity of plastic hinges are discussed. The increase of ductility with decreasing member size is interpreted from the viewpoint of fracture mechanics of concrete. The results of the introductory test series on simply supported slender beams loaded in three-p

  15. Size Effects in Plastic Hinges of Reinforced Concrete Members

    NARCIS (Netherlands)

    Bigaj, A.; Walraven, J.C.

    2002-01-01

    Reasons for size dependence of rotation capacity of plastic hinges are discussed. The increase of ductility with decreasing member size is interpreted from the viewpoint of fracture mechanics of concrete. The results of the introductory test series on simply supported slender beams loaded in three-p

  16. Conductivity size effect of polycrystalline metal nanowires

    Directory of Open Access Journals (Sweden)

    Weihuang Xue

    2016-11-01

    Full Text Available It is well known that the conductivity of metal nanowires decreases with the wire diameter. This size effect was first studied for metal thin films when the film thickness approaches the electron mean free path. Fuchs & Sondheimer (FS pointed out that the external surface scattering of the electrons contributes to the conductivity decrease. Mayadas and Shatzkes (MS pointed out that the grain boundary scattering plays a major role for polycrystalline thin films. As is clear that nanowires are 2-d constrained instead of 1-d for thin film, so the size effect would be more eminent. However, today the mostly used physical model for the conductivity of metal nanowires is still the MS theory. This paper proposes a more complete model suitable for circular cross-section polycrystalline metal nanowires, which takes into account of background scattering, external surface scattering, as well as grain boundary scattering. Comparison with experiment data showed that our model can well explain the conductivity size effect of polycrystalline metal nanowires.

  17. Scaling of TNSA-accelerated proton beams with laser energy and focal spot size

    Energy Technology Data Exchange (ETDEWEB)

    Obst, Lieselotte; Metzkes, Josefine; Schramm, Ulrich [Helmholtz-Zentrum Dresden - Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Dresden (Germany); Zeil, Karl; Kraft, Stephan [Helmholtz-Zentrum Dresden - Rossendorf, Dresden (Germany)

    2014-07-01

    We investigate the acceleration of high energy proton pulses generated by relativistic laser-plasma interaction. The scope of this work was the systematic investigation of the scaling of the laser proton acceleration process in the ultra-short pulse regime in order to identify feasible routes towards the potential medical application of this accelerator technology for the development of compact proton sources for radiation therapy. We present an experimental study of the proton beam properties under variation of the laser intensity irradiating thin foil targets. This was achieved by employing different parabolic mirrors with various focal lengths. Hence, in contrast to moving the target in and out of focus, the target was always irradiated with an optimized focal spot. By observing the back reflected light of the laser beam from the target front side, pre-plasma effects on the laser absorption could be investigated. The study was performed at the 150 TW Draco Laser facility of the Helmholtz-Zentrum Dresden-Rossendorf with ultrashort (30 fs) laser pulses of intensities of about 8 . 10{sup 20} W/cm{sup 2}.

  18. Effect of beam oscillation on fatigue life of Ti-6Al-4V electron beam weldments

    Energy Technology Data Exchange (ETDEWEB)

    Babu, N. Kishore [Department of Metallurgical and Materials Engineering, IIT Madras, Chennai (India); Raman, S. Ganesh Sundara [Department of Metallurgical and Materials Engineering, IIT Madras, Chennai (India)], E-mail: ganesh@iitm.ac.in; Murthy, C. V. Srinivasa [Defence Research and Development Laboratory, Hyderabad (India); Reddy, G. Madhusudhan [Defence Metallurgical Research Laboratory, Hyderabad (India)

    2007-12-15

    The present study deals with the effect of beam oscillation technique using elliptical waveform on fatigue life of Ti-6Al-4V electron beam weldments. Autogenous full penetration bead-on-plate electron beam welds were made with and without beam oscillation. Some welds were subjected to post-weld heat treatment (PWHT) at two different temperatures (700 and 900 deg. C). Room temperature hardness, tensile properties and fatigue life of the weldments in the as-welded and PWHT conditions were studied and correlated with the microstructure. The beam oscillated weldments exhibited lower strength (hardness) compared to those made without beam oscillation. This was attributed to wider diffusional {alpha} plates in the beam oscillated welds due to lower cooling rates. The beam oscillated weldments exhibited inferior fatigue lives compared with unoscillated weldments owing to the presence of wider {alpha} platelets in the former. As the width of {alpha} platelets in the weldments subjected to PWHT at 700 deg. C was smaller than that in the weldments subjected to PWHT at 900 deg. C, they exhibited longer fatigue lives.

  19. Ion beam Irradiation-induced Amorphization of Nano-sized KxLnyTa2O7-v Tantalate Pyrochlore

    Directory of Open Access Journals (Sweden)

    Fengyuan eLu

    2014-10-01

    Full Text Available Nano-sized (~10-15 nm tantalate pyrochlores KxLnyTa2O7-v (Ln = Gd, Y, and Lu were irradiated with 1 MeV Kr2+ beams at different temperatures and their radiation response behaviors were studied by in-situ TEM observations. All of these nano-sized KxLnyTa2O7-v pyrochlores are sensitive to radiation-induced amorphization with low critical doses (~0.12 dpa at room temperature and high critical amorphization temperatures above 1160 K. The K+ plays a key role in determining the radiation response of tantalate pyrochlores, in which the K+-rich KLuTa2O7 displays greater amorphization susceptibility than K0.8GdTa2O6.9 and K0.8YTa2O6.9 with lower K+ occupancy at the A-site. The reduced amorphization tolerance of the composition with a greater K+ content is consistent with the prominently larger K+/Ta5+ cationic radius ratio, which may result in more structural deviation from the parent fluorite structure and less capability to accommodate radiation induced defects. An empirical correlation between critical amorphization temperature and ionic size was derived, generally describing the dominant effect of ionic sizes in controlling radiation response of a wide range of pyrochlore compounds as potential nuclear waste forms. The results of the tantalate pyrochlore in this work highlight that nanostructured pyrochlores are not intrinsically radiation tolerant and their responses are highly compositional dependent.

  20. Biological effect of penetration controlled irradiation with ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Atsushi; Shimizu, Takashi; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Watanabe, Hiroshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Yamashita, Takao

    1997-03-01

    To investigate the effect of local irradiation with ion beams on biological systems, technique for penetration controlled irradiation has been established. The range in a target was controlled by changing the distance from beam window in the atmosphere, and could be controlled linearly up to about 31 {mu}m in biological material. In addition, the effects of the penetration controlled irradiations with 1.5 MeV/u C and He ions were examined using tobacco pollen. The increased frequency of leaky pollen produced by ion beams suggests that the efficient pollen envelope damages would be induced at the range-end of ion beams. (author)

  1. A large size ion beam figuring system for 1.2m astronomical telescopes fabrication

    Science.gov (United States)

    Xie, Xuhui; Yang, Bing; Zhou, Lin; Song, Ci; Hu, Hao

    2016-07-01

    An ion beam figuring system (KDIBF2000) for final figuring of large size optics has been designed and built by National University of Defense Technology in China. It can figure optics up to the maximum dimensions of 2.0m×2.0m×0.4m with five axes of servo-motion used to control ion source movement. For operational facility, there are two vacuum chambers with main work chamber and a small supplementary chamber isolated by a flapper valve. The main chamber has two work zones, which can meantime hold a large optics with Φ1.5m and a small optics with 0.4m. The small optics can be transferred through supplementary chamber with a moving vehicle. By this way, it is very convenient and economical to gain the material removal function and check the system's process performance. Now, this system has been gone into running to figure large SiC off-axis aspheric optics. Next step, a 1.2m SiC aspheric primary mirror will be figure by this system.

  2. Impact of cone-beam computed tomography on implant planning and on prediction of implant size

    Energy Technology Data Exchange (ETDEWEB)

    Pedroso, Ludmila Assuncao de Mello; Silva, Maria Alves Garcia Santos, E-mail: ludmilapedroso@hotmail.com [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Fac. de Odontologia; Garcia, Robson Rodrigues [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Fac. de Odontologia. Dept. de Medicina Oral; Leles, Jose Luiz Rodrigues [Universidade Paulista (UNIP), Goiania, GO (Brazil). Fac. de Odontologia. Dept. de Cirurgia; Leles, Claudio Rodrigues [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Fac. de Odontologia. Dept. de Prevencao e Reabilitacao Oral

    2013-11-15

    The aim was to investigate the impact of cone-beam computed tomography (CBCT) on implant planning and on prediction of final implant size. Consecutive patients referred for implant treatment were submitted to clinical examination, panoramic (PAN) radiography and a CBCT exam. Initial planning of implant length and width was assessed based on clinical and PAN exams, and final planning, on CBCT exam to complement diagnosis. The actual dimensions of the implants placed during surgery were compared with those obtained during initial and final planning, using the McNemmar test (p < 0.05). The final sample comprised 95 implants in 27 patients, distributed over the maxilla and mandible. Agreement in implant length was 50.5% between initial and final planning, and correct prediction of the actual implant length was 40.0% and 69.5%, using PAN and CBCT exams, respectively. Agreement in implant width assessment ranged from 69.5% to 73.7%. A paired comparison of the frequency of changes between initial or final planning and implant placement (McNemmar test) showed greater frequency of changes in initial planning for implant length (p < 0.001), but not for implant width (p = 0.850). The frequency of changes was not influenced by implant location at any stage of implant planning (chi-square test, p > 0.05). It was concluded that CBCT improves the ability of predicting the actual implant length and reduces inaccuracy in surgical dental implant planning. (author)

  3. Numerical Study of Scale Effects of Ultra-Thin Nickel Beams

    Institute of Scientific and Technical Information of China (English)

    Li Lei; Xie Shuisheng; Yang Haoqiang; Huang Guojie

    2004-01-01

    Recent experiments have shown that metallic materials display significant size effects when the characteristic length scale of non-uniform plastic deformation is close to a micron. Couple stress plasticity has been developed to explain such phenomena by Fleck and Hutchinson. The mechanical behaviors of ultra-thin nickel beams in different boundary conditions were studied with the hybrid element developed for couple stress plasticity before. Strong scale effects are found when the beam's thickness is close to the material characteristic length scale. Such phenomena will disappear if the beam' s thickness is greatly larger than the material characteristic length scale. The scale effect is the beams inherent property and it does not change with the change of support conditions.

  4. Analytical treatment of the nonlinear electron cloud effect and the combined effects with beam-beam and space charge nonlinear forces in storage rings

    Institute of Scientific and Technical Information of China (English)

    GAO Jie

    2009-01-01

    In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC Ⅱ. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.

  5. The size effect in metal cutting

    Indian Academy of Sciences (India)

    Milton C Shaw

    2003-10-01

    When metal is removed by machining there is substantial increase in the specific energy required with decrease in chip size. It is generally believed this is due to the fact that all metals contain defects (grain boundaries, missing and impurity atoms, etc.), and when the size of the material removed decreases, the probability of encountering a stress-reducing defect decreases. Since the shear stress and strain in metal cutting is unusually high, discontinuous microcracks usually form on the metal-cutting shear plane. If the material being cut is very brittle, or the compressive stress on the shear plane is relatively low, microcracks grow into gross cracks giving rise to discontinuous chip formation. When discontinuous microcracks form on the shear plane they weld and reform as strain proceeds, thus joining the transport of dislocations in accounting for the total slip of the shear plane. In the presence of a contaminant, such as CCl4 vapour at a low cutting speed, the rewelding of microcracks decreases, resulting in decrease in the cutting force required for chip formation. A number of special experiments are described in the paper that support the transport of microcracks across the shear plane, and the important role compressive stress plays on the shear plane. Relatively recently, an alternative explanation for the size effect in cutting was provided based on the premise that shear stress increases with increase in strain rate. When an attempt is made to apply this to metal cutting by Dinesh et al (2001) it is assumed in the analysis that the von Mises criterion pertains to the shear plane. This is inconsistent with the experimental findings of Merchant. Until this difficulty is taken care of, together with the promised experimental verification of the strain rate approach, it should be assumed that the strain rate effect may be responsible for some notion of the size effect in metal cutting. However, based on the many experiments discussed here, it is

  6. Size-effects in porous metals

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    . For porous materials with small void volume fractions under highly triaxial tension, void growth is analyzed through cavitation instabilities using a finite element Rayleigh-Ritz procedure. Cavitation instabilities are found to be delayed for small voids, so that higher stress levels are needed in order......The intrinsic size-effect for porous metals is investigated. The analyses are carried out numerically using a finite strain generalization of a higher order strain gradient plasticity model. Results for plane strain growth of cylindrical voids are presented in terms of response curves and curves...... of relative void growth. The influence of void size compared to a constitutive length parameter is analyzed and it is shown that strain gradient hardening suppresses void growth on the micron scale. This increased resistance to void growth is accompanied by an increase in the overall strength of the material...

  7. Space Charge Effect in the Sheet and Solid Electron Beam

    Science.gov (United States)

    Song, Ho Young; Kim, Hyoung Suk; Ahn, Saeyoung

    1998-11-01

    We analyze the space charge effect of two different types of electron beam ; sheet and solid electron beam. Electron gun simulations are carried out using shadow and control grids for high and low perveance. Rectangular and cylindrical geometries are used for sheet and solid electron beam in planar and disk type cathode. The E-gun code is used to study the limiting current and space charge loading in each geometries.

  8. Influence of nuclear quantum effects on frozen phonon simulations of electron vortex beam HAADF-STEM images

    Energy Technology Data Exchange (ETDEWEB)

    Löfgren, André; Zeiger, Paul; Kocevski, Vancho; Rusz, Ján, E-mail: jan.rusz@fysik.uu.se

    2016-05-15

    We have evaluated atomic resolution high-angle annular dark field images with ordinary beams and electron vortex beams for thin crystals of bcc iron, explicitly considering the atomic vibrations using molecular dynamics. The shape of the image representing an atomic column depends on the orbital angular momentum, sample thickness and temperature. For electron vortex beams we observe characteristic doughnut-shaped images of atomic columns. It is shown how the thermal diffuse scattering reduces the depth of their central minima, which get further smeared by finite source size effects. In addition, it is shown that in calculations of HAADF-STEM images at low temperatures one has to explicitly consider the nuclear quantum effects (zero point vibrations), otherwise the effect of atomic vibrations is strongly underestimated. - Highlights: • HAADF STEM images calculated for ordinary beams and electron vortex beams. • Temperature, sample thickness, convergence angle and source size broadening effects. • Zero point vibrations included into the molecular dynamics calculations.

  9. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: -> Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. -> Deconvolution of the luminosity spectrum distortion due to the ISR emission. -> Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  10. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: - Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. - Deconvolution of the luminosity spectrum distortion due to the ISR emission. - Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  11. Size-Effects in Void Growth

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2005-01-01

    The size-effect on ductile void growth in metals is investigated. The analysis is based on unit cell models both of arrays of cylindrical voids under plane strain deformation, as well as arrays of spherical voids using an axisymmetric model. A recent finite strain generalization of two higher order...... strain gradient plasticity models is implemented in a finite element program, which is used to study void growth numerically. The results based on the two models are compared. It is shown how gradient effects suppress void growth on the micron scale when compared to predictions based on conventional...... models. This increased resistance to void growth, due to gradient hardening, is accompanied by an increase in the overall strength for the material. Furthermore, for increasing initial void volume fraction, it is shown that the effect of gradients becomes more important to the overall response but less...

  12. Size-effects in porous metals

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    2007-01-01

    of the material. For porous materials with small void volume fractions under highly triaxial tension, void growth is analysed through cavitation instabilities using a finite element Rayleigh–Ritz procedure. Cavitation instabilities are found to be delayed for small voids, so that higher stress levels are needed......The intrinsic size-effect for porous metals is investigated. The analyses are carried out numerically using a finite strain generalization of a higher order strain gradient plasticity model. Results for plane strain growth of cylindrical voids are presented in terms of response curves and curves...

  13. Effect of crosstalk on combined beam characteristics in spectral beam combining systems

    Science.gov (United States)

    Yang, Lei; Wu, Zhen; Zhong, Zheqiang; Zhang, Bin

    2017-02-01

    In a spectral beam combining (SBC) system, crosstalk always happens because stray lights are inevitable due to fabrication errors of optical components and 'smile' effect of laser arrays. Two kinds of crosstalk, including the crosstalk generated between two adjacent emitters of the laser array (ad-crosstalk) and that generated between two non-adjacent emitters (non-ad-crosstalk), have been analyzed. The equivalent light of the crosstalk model has been proposed, and the propagation model of the SBC system with the crosstalk has been built up. On this basis, influences of above two kinds of the crosstalk on the combined beam have been numerically simulated and discussed in detail. The results show that the wavelength composition of the combined beam varies evidently owing to the existence of the crosstalk. With the increasing of the crosstalk intensity, the beam quality of the combined beam degrades, and the side lobes of intensity distribution of the combined beam become more and more obvious. Furthermore, the influence of the non-ad-crosstalk on the beam quality is more serious than that of the ad-crosstalk.

  14. Two Effective Heuristics for Beam Angle Optimization in Radiation Therapy

    CERN Document Server

    Yarmand, Hamed

    2013-01-01

    In radiation therapy, mathematical methods have been used for optimizing treatment planning for delivery of sufficient dose to the cancerous cells while keeping the dose to critical surrounding structures minimal. This optimization problem can be modeled using mixed integer programming (MIP) whose solution gives the optimal beam orientation as well as optimal beam intensity. The challenge, however, is the computation time for this large scale MIP. We propose and investigate two novel heuristic approaches to reduce the computation time considerably while attaining high-quality solutions. We introduce a family of heuristic cuts based on the concept of 'adjacent beams' and a beam elimination scheme based on the contribution of each beam to deliver the dose to the tumor in the ideal plan in which all potential beams can be used simultaneously. We show the effectiveness of these heuristics for intensity modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT) on a clinical liver case.

  15. The pack size effect: Influence on consumer perceptions of portion sizes

    NARCIS (Netherlands)

    Hieke, Sophie; Palascha, Aikaterini; Jola, Corinne; Wills, Josephine; Raats, Monique M.

    2016-01-01

    Larger portions as well as larger packs can lead to larger prospective consumption estimates, larger servings and increased consumption, described as 'portion-size effects' and 'pack size effects'. Although related, the effects of pack sizes on portion estimates have received less attention. While i

  16. Effect of electron beam on in vitro cultured orchid organs

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Jaihyunk; Bae, Seho; Bae, Changhyu [Sunchon National Univ., Suncheon (Korea, Republic of); Kang, Hyun Suk; Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-07-01

    Ionizing radiations have been effective mutagen sources to overcome the limitation of the useful genetic resources in natural environment. The study was conducted to investigate an effect of electron beam on organogenesis, growth patterns and genetic variation in the irradiated orchid organs. The in utero cultured rhizomes of orchids were irradiated with the electron beam in the dose range of 15Gy to 2240Gy under the condition of various beam energy and beam current. Significant decreases in survival, growth and organogenesis were observed by increase of intensity of electron beam irradiation. The irradiation intensity of lethal dose 50 of the in utero cultured orchid was estimated as approximately 500Gy to 1000Gy under 10MeV/n, and 1000Gy was optimal for growth and organogenesis of the cultures under 10MeV/n with 0.05mA treatment, and 15Gy {approx} 48Gy under 2MeV/n and 0.5mA electron beam condition. RAPD and ISSR analyses for the electron beam irradiated organs were performed to analyze genetic variation under the electron beam condition. Both of RAPD and ISSR analyses showed higher polymorphic rate in the electron-beam irradiated C. gangrene and C. Kaner.

  17. Influence of the Laser Spot Size, Focal Beam Profile, and Tissue Type on the Lipid Signals Obtained by MALDI-MS Imaging in Oversampling Mode

    Science.gov (United States)

    Wiegelmann, Marcel; Dreisewerd, Klaus; Soltwisch, Jens

    2016-12-01

    To improve the lateral resolution in matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) beyond the dimensions of the focal laser spot oversampling techniques are employed. However, few data are available on the effect of the laser spot size and its focal beam profile on the ion signals recorded in oversampling mode. To investigate these dependencies, we produced 2 times six spots with dimensions between 30 and 200 μm. By optional use of a fundamental beam shaper, square flat-top and Gaussian beam profiles were compared. MALDI-MSI data were collected using a fixed pixel size of 20 μm and both pixel-by-pixel and continuous raster oversampling modes on a QSTAR mass spectrometer. Coronal mouse brain sections coated with 2,5-dihydroxybenzoic acid matrix were used as primary test systems. Sizably higher phospholipid ion signals were produced with laser spots exceeding a dimension of 100 μm, although the same amount of material was essentially ablated from the 20 μm-wide oversampling pixel at all spot size settings. Only on white matter areas of the brain these effects were less apparent to absent. Scanning electron microscopy images showed that these findings can presumably be attributed to different matrix morphologies depending on tissue type. We propose that a transition in the material ejection mechanisms from a molecular desorption at large to ablation at smaller spot sizes and a concomitant reduction in ion yields may be responsible for the observed spot size effects. The combined results indicate a complex interplay between tissue type, matrix crystallization, and laser-derived desorption/ablation and finally analyte ionization.

  18. Interferometric measurement of beam size at Hefei Light Source%合肥光源上采用干涉方法测量束流截面

    Institute of Scientific and Technical Information of China (English)

    张红霞; 张超; 蒋诗平; 邹成刚; 王秋平; 贾大功; 张以谟

    2011-01-01

    The measurement of beam size is important for optimizing system parameters and ensuring stable operation of synchrotron radiation light sources. An interferometric method was adopted to measure the vertical size of beam section at Hefei Light Source. Based on the theory of Cittert-Zernike, the size of beam section can be calculated according to the double-slit inter-ferogram contrast. The interferometric system consists of interference imaging system and image processing system. The results of the five experiments conducted agree well with the theoretical value, verifying the effectiveness of the interferometric method.%束流截面尺寸测量对优化系统参数、确保光源运行至关重要.采用干涉法测量合肥同步辐射光源束流截面垂直方向的尺寸.基于Cittert-Zernike定理,利用双缝干涉条纹的对比度得出相干度和柬流截面尺寸.测量系统由干涉成像与图像处理系统组成.进行了5组试验,试验结果证明了干涉法测量合肥同步辐射束流截面尺寸的可行性.

  19. Beam size reduction of a several hundred-keV compact ion microbeam system by improving the extraction condition in an ion source

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Yasuyuki; Ohkubo, Takeru; Kamiya, Tomihiro; Saitoh, Yuichi

    2015-04-01

    A several hundred-keV compact ion microbeam system with a three-stage acceleration lens has been developed to form an ion beam of several micrometers in diameter. In a previous study of the Ohkubo et al. (2013) and Ishii et al. (2014), a hydrogen beam of 143 keV having 17 μm diameter was experimentally formed using such a microbeam system. It was demonstrated that a three-stage acceleration lens functioned as a focusing lens and indicated that the beam diameter (hereinafter referred to as the “beam size”) depended on the extraction voltage to generate the ion beam and the vacuum pressure in the extraction space in a plasma-type ion source. In this study, the hydrogen beam sizes were experimentally measured at 130 keV as functions of the extraction voltage and vacuum pressure to form the beam size with several micrometers in diameter. These two relationships showed that beam sizes were reduced in the extraction voltage range of 400–500 V and when the vacuum pressure was lowered to a minimum value of 5.33 × 10{sup −5} Pa. In addition, the result showed that the beam size was dominantly influenced by the vacuum pressure. Consequently, a hydrogen beam 5.8 μm in diameter was formed experimentally—the smallest beam yet obtained.

  20. Finite-size effects from giant magnons

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunov, Gleb [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands)]. E-mail: g.arutyunov@phys.uu.nl; Frolov, Sergey [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, D-14476 Potsdam (Germany)]. E-mail: frolovs@aei.mpg.de; Zamaklar, Marija [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, D-14476 Potsdam (Germany)]. E-mail: marzam@aei.mpg.de

    2007-08-27

    In order to analyze finite-size effects for the gauge-fixed string sigma model on AdS{sub 5}xS{sup 5}, we construct one-soliton solutions carrying finite angular momentum J. In the infinite J limit the solutions reduce to the recently constructed one-magnon configuration of Hofman and Maldacena. The solutions do not satisfy the level-matching condition and hence exhibit a dependence on the gauge choice, which however disappears as the size J is taken to infinity. Interestingly, the solutions do not conserve all the global charges of the psu(2,2-vertical bar4) algebra of the sigma model, implying that the symmetry algebra of the gauge-fixed string sigma model is different from psu(2,2-vertical bar4) for finite J, once one gives up the level-matching condition. The magnon dispersion relation exhibits exponential corrections with respect to the infinite J solution. We also find a generalisation of our one-magnon configuration to a solution carrying two charges on the sphere. We comment on the possible implications of our findings for the existence of the Bethe ansatz describing the spectrum of strings carrying finite charges.

  1. In vitro comparison of cone beam computed tomography with different voxel sizes for detection of simulated external root resorption.

    Science.gov (United States)

    Neves, Frederico S; de Freitas, Deborah Q; Campos, Paulo S F; de Almeida, Solange M; Haiter-Neto, Francisco

    2012-09-01

    The present study compared the efficacy of cone beam computed tomography using different voxel sizes in the diagnosis of simulated external root resorption. The presence or absence of simulated defects on buccal, mesial and distal root surfaces of 20 premolars was evaluated. The defects were small (0.26 mm in diameter and 0.08 mm deep), medium (0.62 mm in diameter and 0.19 mm deep) and large (1.05 mm in diameter and 0.24 mm deep), equally distributed on each root surface. Images were obtained using Classic i-CAT cone beam computed tomography with different voxel sizes: 0.12, 0.20, 0.25 and 0.30 mm. Five oral radiologists evaluated the images. Accuracy, sensitivity, specificity, positive and negative predictive values were determined. The sensitivity decreased and specificity increased as voxel size increased. Accuracy values were the highest for the smallest voxel size (0.12 mm). The results for voxel sizes 0.20 mm and 0.25 mm were similar. Positive and negative predictive values were similar in all protocols, except with 0.30 mm, in which they were the lowest. In conclusion, external root resorption was more easily diagnosed when a smaller voxel size was used.

  2. Strong crystal size effect on deformation twinning

    DEFF Research Database (Denmark)

    Yu, Qian; Shan, Zhi-Wei; Li, Ju

    2010-01-01

    find that the stress required for deformation twinning increases drastically with decreasing sample size of a titanium alloy single crystal7, 8, until the sample size is reduced to one micrometre, below which the deformation twinning is entirely replaced by less correlated, ordinary dislocation....... The sample size in transition is relatively large and easily accessible in experiments, making our understanding of size dependence11, 12, 13, 14, 15, 16, 17 relevant for applications....

  3. Ion beam sputter deposition of Ag films: Influence of process parameters on electrical and optical properties, and average grain sizes

    Energy Technology Data Exchange (ETDEWEB)

    Bundesmann, C., E-mail: carsten.bundesmann@iom-leipzig.de; Feder, R.; Gerlach, J.W.; Neumann, H.

    2014-01-31

    Ion beam sputter deposition is used to grow several sets of Ag films under systematic variation of ion beam parameters, such as ion species and ion energy, and geometrical parameters, such as ion incidence angle and polar emission angle. The films are characterized concerning their thickness by profilometry, their electrical properties by 4-point-probe-measurements, their optical properties by spectroscopic ellipsometry, and their average grain sizes by X-ray diffraction. Systematic influences of the growth parameters on film properties are revealed. The film thicknesses show a cosine-like angular distribution. The electrical resistivity increases for all sets with increasing emission angle and is found to be considerably smaller for Ag films grown by sputtering with Xe ions than for the Ag films grown by sputtering with Ar ions. Increasing the ion energy or the ion incidence angle also increases the electrical resistivity. The optical properties, which are the result of free charge carrier absorption, follow the same trends. The observed trends can be partly assigned to changes in the average grain size, which are tentatively attributed to different energetic and angular distributions of the sputtered and back-scattered particles. - Highlights: • Ion beam sputter deposition under systematic variation of process parameters. • Film characterization: thickness, electrical, optical and structural properties. • Electrical resistivity changes considerably with ion species and polar emission angle. • Electrical and optical data reveal a strong correlation with grain sizes. • Change of film properties related to changing properties of film-forming particles.

  4. Modelling the effect of size-asymmetric competition on size inequality

    DEFF Research Database (Denmark)

    Rasmussen, Camilla Ruø; Weiner, Jacob

    2017-01-01

    Abstract The concept of size asymmetry in resource competition among plants, in which larger individuals obtain a disproportionate share of contested resources, appears to be very straightforward, but the effects of size asymmetry on growth and size variation among individuals have proved......) plants. The effects of size symmetry/asymmetry on size inequality are dependent on (1) the individual plant growth model, (2) the parameters of the growth model that are affected by competition and (3) the initial sizes and growth rates. Across a range of reasonable assumptions, very general patterns...... that have been considered evidence for or against size-asymmetric competition do not always hold. Our results emphasize the need for explicit growth models, even very simple ones, for making inferences about the effects of competition on plant growth and size inequality....

  5. Beam hardening correction for a cone-beam CT system and its effect on spatial resolution

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei; WEI Long; YU Zhong-Qiang; FU Guo-Tao; SUN Cui-Li; WANG Yan-Fang; WEI Cun-Feng; CAO Da-Quan; QUE Jie-Min; TANG Xiao; SHI Rong-Jian

    2011-01-01

    In this paper,we present a beam hardening correction (BHC) method in three-dimension space for a cone-beam computed tomography (CBCT) system in a mono-material case and investigate its effect on the spatial resolution.Due to the polychromatic character of the X-ray spectrum used,cupping and streak artifacts called beam hardening artifacts arise in the reconstructed CT images,causing reduced image quality.In addition,enhanced edges are introduced in the reconstructed CT images because of the beam hardening effect.The spatial resolution of the CBCT system is calculated from the edge response function (ERF) on different planes in space.Thus,in the CT images with beam hardening artifacts,enhanced ERFs will be extracted to calculate the modulation transfer function (MTF),obtaining a better spatial resolution that deviates from the real value.Reasonable spatial resolution can be obtained after reducing the artifacts.The 10% MTF value and the full width at half maximum (FWHM) of the point spread function with and without BHC are presented.

  6. Effects of aberration on paraxial wave beams: beam tracing versus quasi-optical solutions

    Energy Technology Data Exchange (ETDEWEB)

    Maj, O [Max-Planck-Institut fuer Sonnensystemforschung, Katlenburg-Lindau (Germany); Balakin, A A [Institute of Applied Physics RAS, Nizhny Novgorod (Russian Federation); Poli, E, E-mail: omaj@ipp.mpg.d [Max-Planck-Institut fuer Plasmaphysik, Garching bei Muenchen (Germany)

    2010-08-15

    This paper aims to clarify the role of aberration effects on the propagation and absorption of wave beams in inhomogeneous dispersive and dissipative media. We consider models in which aberration effects can be caused by the presence of either caustics or spatially dispersive absorption, with reference to the propagation near a cut-off or to the electron-cyclotron (EC) resonance, respectively. For such models, the standard beam tracing description of paraxial wave beams and the recently proposed quasi-optical method, which accounts for aberration, are compared and verified on the basis of the analytical exact solutions. We find that the presence of a cut-off implies no significant aberration of the beam, while significant aberration is found when dispersive absorption is so strong that different wavenumbers in the beam spectrum are damped at different locations. This phenomenon is well described by the quasi-optical method. Finally, an extrapolation of this simple two-dimensional model to the case of the ITER upper EC port is addressed with the result that the broadening of the power deposition profiles never exceeds 10%.

  7. Beam-Induced Multipactoring and Electron-Cloud Effects in Particle Accelerators

    CERN Document Server

    Caspers, Friedhelm; Scandale, Walter; Zimmermann, F

    2009-01-01

    In the beam pipe of high-energy proton or positron accelerators an “electron cloud” can be generated by a variety of processes, e.g. by residual-gas ionization, by photoemission from synchrotron radiation, and, most importantly, by secondary emission via a beam-induced multipactoring process. The electron cloud commonly leads to a degradation of the beam vacuum by several orders of magnitude, to fast beam instabilities, to beam-size increases, and to fast or slow beam losses. At the Large Hadron Collider (LHC), the cloud electrons could also give rise to an additional heat load inside cold superconducting magnets. In addition to the direct heat deposition from incoherently moving electrons, a potential “magnetron effect” has been conjectured, where electrons would radiate coherently when moving in a strong magnetic field under the simultaneous influence of a beam-induced electric “wake” field that may become resonant with the cyclotron frequency. Electron-cloud effects are already being observed w...

  8. Effects of electrons on the shape of nanopores prepared by focused electron beam induced etching

    Science.gov (United States)

    Liebes, Yael; Hadad, Binyamin; Ashkenasy, Nurit

    2011-07-01

    The fabrication of nanometric pores with controlled size is important for applications such as single molecule detection. We have recently suggested the use of focused electron beam induced etching (FEBIE) for the preparation of such nanopores in silicon nitride membranes. The use of a scanning probe microscope as the electron beam source makes this technique comparably accessible, opening the way to widespread fabrication of nanopores. Since the shape of the nanopores is critically important for their performance, in this work we focus on its analysis and study the dependence of the nanopore shape on the electron beam acceleration voltage. We show that the nanopore adopts a funnel-like shape, with a central pore penetrating the entire membrane, surrounded by an extended shallow-etched region at the top of the membrane. While the internal nanopore size was found to depend on the electron acceleration voltage, the nanopore edges extended beyond the primary electron beam spot size due to long-range effects, such as radiolysis and diffusion. Moreover, the size of the peripheral-etched region was found to be less dependent on the acceleration voltage. We also found that chemical etching is the rate-limiting step of the process and is only slightly dependent on the acceleration voltage. Furthermore, due to the chemical etch process the chemical composition of the nanopore rims was found to maintain the bulk membrane composition.

  9. Effects of electrons on the shape of nanopores prepared by focused electron beam induced etching

    Energy Technology Data Exchange (ETDEWEB)

    Liebes, Yael; Ashkenasy, Nurit [Department of Materials Engineering, Ben-Gurion University of the Negev, PO Box 653 Beer-Sheva (Israel); Hadad, Binyamin, E-mail: nurita@bgu.ac.il [The Ilze Kaz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653 Beer-Sheva (Israel)

    2011-07-15

    The fabrication of nanometric pores with controlled size is important for applications such as single molecule detection. We have recently suggested the use of focused electron beam induced etching (FEBIE) for the preparation of such nanopores in silicon nitride membranes. The use of a scanning probe microscope as the electron beam source makes this technique comparably accessible, opening the way to widespread fabrication of nanopores. Since the shape of the nanopores is critically important for their performance, in this work we focus on its analysis and study the dependence of the nanopore shape on the electron beam acceleration voltage. We show that the nanopore adopts a funnel-like shape, with a central pore penetrating the entire membrane, surrounded by an extended shallow-etched region at the top of the membrane. While the internal nanopore size was found to depend on the electron acceleration voltage, the nanopore edges extended beyond the primary electron beam spot size due to long-range effects, such as radiolysis and diffusion. Moreover, the size of the peripheral-etched region was found to be less dependent on the acceleration voltage. We also found that chemical etching is the rate-limiting step of the process and is only slightly dependent on the acceleration voltage. Furthermore, due to the chemical etch process the chemical composition of the nanopore rims was found to maintain the bulk membrane composition.

  10. The System of Nanosecond 280-keV-Hesize="-1">+ Pulsed Beam

    CERN Document Server

    Junphong, Pimporn; Lekprasert, Banyat; Suwannakachorn, Dusadee; Thongnopparat, N; Vilaithong, Thiraphat; Wiedemann, Helmut

    2005-01-01

    At Fast Neutron Research Facility,the 150 kV-pulseds neutron generator is being upgraded to produce a 280-keV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The Multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μA with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has been found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a t...

  11. Studies on transmitted beam modulation effect from laser induced damage on fused silica optics.

    Science.gov (United States)

    Zheng, Yi; Ma, Ping; Li, Haibo; Liu, Zhichao; Chen, Songlin

    2013-07-15

    UV laser induced damage (LID) on exit surface of fused silica could cause modulation effect to transmitted beam and further influence downstream propagation properties. This paper presents our experimental and analytical studies on this topic. In experiment, a series of measurement instruments are applied, including beam profiler, interferometer, microscope, and optical coherent tomography (OCT). Creating and characterizing of LID on fused silica sample have been implemented. Morphological features are studied based on their particular modulation effects on transmitted beam. In theoretical investigation, analytical modeling and numerical simulation are performed. Modulation effects from amplitude, phase, and size factors are analyzed respectively. Furthermore, we have novelly designed a simplified polygon model to simulate actual damage site with multiform modulation features, and the simulation results demonstrate that the modeling is usable and representative.

  12. HOLLOW ELECTRON BEAM COLLIMATION FOR HL-LHC - EFFECT ON THE BEAM CORE

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermilab; Stancari, G. [Fermilab; Valishev, A. [Fermilab; Bruce, R. [CERN; Papadopoulou, S. [CERN; Papotti, G. [CERN; Pellegrini, D. [CERN; Pellegrini, S. [CERN; Valuch, D. [CERN; Wagner, J. F. [CERN

    2016-10-05

    Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.

  13. Effects of electron-cyclotron instabilities on gyrotron beam quality

    Energy Technology Data Exchange (ETDEWEB)

    Jost, G.; Tran, T.M.; Appert, K. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Wuethrich, S. [CRAY Research, PATP/PSE, EPFL, Lausanne (Switzerland)

    1996-02-01

    A two-dimensional PIC code aimed at the investigation of electron-cyclotron beam instabilities in gyrotrons and their effects on the beam quality is presented. The code is based on recently developed techniques for handling charge conservation and open boundaries. It has been implemented on the massively parallel computer CRAY T3D. First results show an electromagnetic backward instability periodically growing and decaying to energy levels close to those obtained from the electrostatic Bernstein wave instability. On the average, the resulting beam degradation is 3 to 4 times larger than that predicted by electrostatic models. (author) 8 figs., 14 refs.

  14. Effect of astigmatism on spectral switches of partially coherent beams

    Institute of Scientific and Technical Information of China (English)

    Zhao Guang-Pu; Xiao Xi; Lü Bai-Da

    2004-01-01

    A detailed study of the spectrum of partially coherent beams diffracted at an astigmatic aperture lens is performed.Considerable attention is paid to the effect of astigmatism on spectral switches of polychromatic Gaussian Schell-model beams. It is shown that the spectral switch can also take place in the vicinity of intensity minimum in a geometrical focal plane for the astigmatic case, but the astigmatism of the lens and the spatial correlation of the beam affect the critical position uc, spectral minimum Smin, and transition height △ of spectral switches.

  15. A novel method for sub-micrometer transverse electron beam size measurements using optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Aryshev, A; Boogert, S T; Karataev, P [John Adams Institute at Royal Holloway, Egham, Surrey, TW20 0EX (United Kingdom); Howell, D [John Adams Institute at Oxford University, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Terunuma, N; Urakawa, J, E-mail: alar@post.kek.j [KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2010-06-01

    Optical Transition Radiation (OTR) appearing when a charged particle crosses a boundary between two media with different dielectric properties has widely been used as a tool for transverse profile measurements of charged particle beams in various facilities worldwide. The resolution of the monitor is defined by so-called Point Spread Function (PSF), source distribution generated by a single electron and projected by an optical system onto a screen. In this paper we represent the development of a novel sub-micrometre electron beam profile monitor based on the measurements of the PSF structure. The first experimental results are presented and future plans on the optimization of the monitor are discussed

  16. Quantum size effects in spherical semiconductor microcrystals

    Science.gov (United States)

    Nair, Selvakumar V.; Sinha, Sucharita; Rustagi, K. C.

    1987-03-01

    The size dependence of the lowest electron-hole state in semiconductor microcrystals is calculated using the variational principle with a three-parameter Hylleraas-type wave function. For very small particles the Coulomb interaction may be treated as a perturbation. For larger particles the size dependence of the energy is much sharper than that expected in previous work.

  17. Effects of beam velocity and density on an ion-beam pulse moving in magnetized plasmas

    CERN Document Server

    Zhao, Xiao-ying; Zhao, Yong-tao; Qi, Xin; Yang, Lei

    2016-01-01

    The wakefield and stopping power of an ion-beam pulse moving in magnetized plasmas are investigated by particle-in-cell (PIC) simulations. The effects of beam velocity and density on the wake and stopping power are discussed. In the presence of magnetic field, it is found that beside the longitudinal conversed V-shaped wakes, the strong whistler wave are observed when low-density and low-velocity pulses moving in plasmas. The corresponding stopping powers are enhanced due to the drag of these whistler waves. As beam velocities increase, the whistler waves disappear, and only are conversed V-shape wakes observed. The corresponding stopping powers are reduced compared with these in isotropic plasmas. When high-density pulses transport in the magnetized plasmas, the whistler waves are greatly inhibited for low-velocity pulses and disappear for high-velocity pulses. Additionally, the magnetic field reduces the stopping powers for all high-density cases.

  18. [Effect sizes, statistical power and sample sizes in "the Japanese Journal of Psychology"].

    Science.gov (United States)

    Suzukawa, Yumi; Toyoda, Hideki

    2012-04-01

    This study analyzed the statistical power of research studies published in the "Japanese Journal of Psychology" in 2008 and 2009. Sample effect sizes and sample statistical powers were calculated for each statistical test and analyzed with respect to the analytical methods and the fields of the studies. The results show that in the fields like perception, cognition or learning, the effect sizes were relatively large, although the sample sizes were small. At the same time, because of the small sample sizes, some meaningful effects could not be detected. In the other fields, because of the large sample sizes, meaningless effects could be detected. This implies that researchers who could not get large enough effect sizes would use larger samples to obtain significant results.

  19. Scattering effect in proton beam windows at spallation targets

    CERN Document Server

    Meng, C; Jing, H T

    2010-01-01

    Proton beam window (PBW) is a boundary wall between a high vacuum area in the proton beam line and the helium atmosphere in a helium vessel at a high beam power target. The thermal and mechanical problems of the PBW have been studied in other spallation neutron sources; however, the scattering effect in PBW is seldom reported in literature but it may pose serious problems for the target design if not well treated. This paper will report the simulation studies of the scattering effect in PBW. Different materials and different structures of PBW are discussed. Taking CSNS as an example, a thin single-layer aluminum alloy PBW with edge cooling has been chosen for CSNS-I and CSNS-II, and a sandwiched aluminum alloy PBW has been chosen for CSNS-III. Simulations results of the scattering effect in the presence of beam uniformization at target by using non-linear magnets at the different CSNS PBWs are presented. The simulations show that the scattering effect at PBW is very important in the beam loss and the beam dis...

  20. Preventing the pack size effect: Exploring the effectiveness of pictorial and non-pictorial serving size recommendations

    NARCIS (Netherlands)

    Versluis, Iris; Papies, Esther; Marchiori, David

    2015-01-01

    People eat more from large than from small packs, which is known as the pack size effect. We hypothesized that providing a serving size recommendation would reduce the influence of the pack size on consumption and would thus diminish the pack size effect. Moreover, we hypothesized that a pictorial s

  1. Effective shielding to measure beam current from an ion source

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, H., E-mail: bayle@bergoz.com [Bergoz Instrumentation, Saint-Genis-Pouilly (France); Delferrière, O.; Gobin, R.; Harrault, F.; Marroncle, J.; Senée, F.; Simon, C.; Tuske, O. [CEA, Saclay (France)

    2014-02-15

    To avoid saturation, beam current transformers must be shielded from solenoid, quad, and RFQ high stray fields. Good understanding of field distribution, shielding materials, and techniques is required. Space availability imposes compact shields along the beam pipe. This paper describes compact effective concatenated magnetic shields for IFMIF-EVEDA LIPAc LEBT and MEBT and for FAIR Proton Linac injector. They protect the ACCT Current Transformers beyond 37 mT radial external fields. Measurements made at Saclay on the SILHI source are presented.

  2. Beam divergence effects on high power optical parametric oscillation

    Institute of Scientific and Technical Information of China (English)

    Li Hui-Qing; Geng Ai-Cong; Bo Yong; Wu Ling-An; Cui Da-Fu; Xu Zu-Yan

    2005-01-01

    The beam divergence effects of the input pump laser on a high power nanosecond optical parametric oscillator (OPO) have been numerically simulated. The OPO conversion efficiency is affected due to the angular deviation of real laser beams from ideal phase matching conditions. Our theoretical model is based on the decomposition of the Gaussian beam and assumes each component has a single deviation angle and thus a Particular wave vector mismatch. We take into account the variable intensity profile in the spatial and temporal domains of the Gaussian beam, the pump depletion effects for large-signal processes as well as the oscillatory effects of the three waves. Two nonlinear crystals β-BaB2O4 (BBO) and LiB3O5 (LBO) have been investigated in detail. The results indicate that the degree of beam divergence strongly influences the maximum pump intensity, optimum crystal length and OPO conversion efficiency.The impact of beam divergence is much more severe in the case of critical phase-matching for BBO than in the case of non-critical phase-matching for LBO. The results provide a way to choose the optimum parameters for a high power ns OPO such as the nonlinear material, the crystal length and the pump intensity, etc. Good agreement is obtained with our experimental results.

  3. How to Estimate and Interpret Various Effect Sizes

    Science.gov (United States)

    Vacha-Haase, Tammi; Thompson, Bruce

    2004-01-01

    The present article presents a tutorial on how to estimate and interpret various effect sizes. The 5th edition of the Publication Manual of the American Psychological Association (2001) described the failure to report effect sizes as a "defect" (p. 5), and 23 journals have published author guidelines requiring effect size reporting. Although…

  4. Surface and size effects on the electrical properties of Cu nanowires

    Science.gov (United States)

    Huang, Qiaojian; Lilley, Carmen M.; Bode, Matthias; Divan, Ralu

    2008-07-01

    Copper nanowires were patterned with e-beam lithography and fabricated with a copper film deposited by e-beam evaporation. Various electrical properties of these nanowires (including resistivity, temperature coefficient of resistance, and failure current density) were characterized. It was experimentally found that surface and size have apparent effects on the electrical properties. Smaller values for the temperature coefficient of resistance and higher failure current density were found for Cu nanowires with decreasing wire width. The experimental finding of width dependent failure current density also agrees with finding for theoretical heat transfer of the nanowire and substrate system as calculated with the finite element method.

  5. Formation of Hexagonal-Close Packed (HCP) Rhodium as a Size Effect.

    Science.gov (United States)

    Huang, Jing Lu; Li, Zhi; Duan, Hao Hong; Cheng, Zhi Ying; Li, Ya Dong; Zhu, Jing; Yu, Rong

    2017-01-18

    Previous studies on the structural and functional properties of rhodium are based on the face-centered-cubic (fcc) structure in the bulk form. Here we report the first discovery of the hexagonal-close packed (hcp) rhodium in the nanoparticle form. The hcp Rh can be directly synthesized by solvothermal reaction or by electron-beam induced decomposition of Rh monolayers. The hcp Rh nanoparticles are stable under electron beam irradiation. Compared with the fcc structure, the hcp Rh nanoparticles show a large lattice expansion (6% larger atomic volume). The first-principles calculations suggest that the lower surface energy of hcp Rh leads to the size effect in the crystal structure.

  6. Effect of Particle Size on Shear Stress of Magnetorheological Fluids

    Directory of Open Access Journals (Sweden)

    Chiranjit Sarkar

    2015-05-01

    Full Text Available Magnetorheological fluids (MRF, known for their variable shear stress contain magnetisable micrometer-sized particles (few micrometer to 200 micrometers in a nonmagnetic carrier liquid. To avoid settling of particles, smaller sized (3-10 micrometers particles are preferred, while larger sized particles can be used in MR brakes, MR clutches, etc. as mechanical stirring action in those mechanisms does not allow particles to settle down. Ideally larger sized particles provide higher shear stress compared to smaller sized particles. However there is need to explore the effect of particle sizes on the shear stress. In the current paper, a comparison of different particle sizes on MR effect has been presented. Particle size distributions of iron particles were measured using HORIBA Laser Scattering Particle Size Distribution Analyser. The particle size distribution, mean sizes and standard deviations have been presented. The nature of particle shapes has been observed using scanning electron microscopy. To explore the effect of particle sizes, nine MR fluids containing small, large and mixed sized carbonyl iron particles have been synthesized. Three concentrations (9%, 18% and 36% by volume for each size of particles have been used. The shear stresses of those MRF samples have been measured using ANTON PAAR MCR-102 Rheometer. With increase in volume fraction of iron particles, the MR fluids synthesized using “mixed sized particles” show better shear stress compared to the MR fluids containing “smaller sized spherical shaped particles” and “larger sized flaked shaped particles” at higher shear rate.

  7. Dynamic behavior of a rotating delaminated composite beam including rotary inertia and shear deformation effects

    Directory of Open Access Journals (Sweden)

    Ramazan-Ali Jafari-Talookolaei

    2015-09-01

    Full Text Available A finite element (FE model is developed to study the free vibration of a rotating laminated composite beam with a single delamination. The rotary inertia and shear deformation effects, as well as the bending–extension, bending–twist and extension–twist coupling terms are taken into account in the FE model. Comparison between the numerical results of the present model and the results published in the literature verifies the validity of the present model. Furthermore, the effects of various parameters, such as delamination size and location, fiber orientation, hub radius, material anisotropy and rotating speed, on the vibration of the beam are studied in detail. These results provide useful information in the study of the free vibration of rotating delaminated composite beams.

  8. The causal effect of board size in the performance of small and medium-sized firms

    DEFF Research Database (Denmark)

    Bennedsen, Morten; Kongsted, Hans Christian; Meisner Nielsen, Kasper

    2008-01-01

    correlation between family size and board size and show this correlation to be driven by firms where the CEO's relatives serve on the board. Second, we find empirical evidence of a small adverse board size effect driven by the minority of small and medium-sized firms that are characterized by having......Empirical studies of large publicly traded firms have shown a robust negative relationship between board size and firm performance. The evidence on small and medium-sized firms is less clear; we show that existing work has been incomplete in analyzing the causal relationship due to weak...... identification strategies. Using a rich data set of almost 7000 closely held corporations we provide a causal analysis of board size effects on firm performance: We use a novel instrument given by the number of children of the chief executive officer (CEO) of the firms. First, we find a strong positive...

  9. Single beam collective effects in FCC-ee due to beam coupling impedance

    CERN Document Server

    Belli, Eleonora; Persichelli, Serena; Zobov, Mikhail

    2016-01-01

    The Future Circular Collider study, hosted by CERN to design post-LHC particle accelerator options in a worldwide context, is focused on proton-proton high-energy and electron-positron high-luminosity frontier machines. This new accelerator complex represents a great challenge under several aspects, which involve R&D on beam dynamics and new technologies. One very critical point in this context is represented by collective effects, generated by the interaction of the beam with self-induced electromagnetic fields, called wake fields, which could produce beam instabilities, thus reducing the machines performance and limiting the maximum stored current. It is therefore very important to be able to predict these effects and to study in detail potential solutions to counteract them. In this paper the resistive wall and some other important geometrical sources of impedance for the FCC electron-positron accelera- tor are identified and evaluated, and their impact on the beam dynamics, which in some cases could l...

  10. Single beam collective effects in FCC-ee due to beam coupling impedance

    CERN Document Server

    Belli, Eleonora; Persichelli, Serena; Zobov, Mikhail

    2016-01-01

    The Future Circular Collider study, hosted by CERN to design post-LHC particle accelerator options in a worldwide context, is focused on proton-proton high-energy and electron-positron high-luminosity frontier machines. This new accelerator complex represents a great challenge under several aspects, which involve R&D on beam dynamics and new technologies. One very critical point in this context is represented by collective effects, generated by the interaction of the beam with self-induced electromagnetic fields, called wake fields, which could produce beam instabilities, thus reducing the machines performance and limiting the maximum stored current. It is therefore very important to be able to predict these effects and to study in detail potential solutions to counteract them. In this paper the resistive wall and some other important geometrical sources of impedance for the FCC electron-positron accelerator are identified and evaluated, and their impact on the beam dynamics, which in some cases could lea...

  11. Biological Effects on Fruit Fly by N+ ion Beam Implantation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Mutation induced by low energy ion beam implantation has beenapplied widely both in plants and microbes. However, due to the vacuum limitation, such ion implantation into animals was never studied except for silkworm. In this study, Pupae of fruit fly were irradiated with different dosage N+ ions at energy 20 KeV to study the biological effect of ion beam on animal. The results showed a saddle-like curve exists between incubate rate and dosage. Damage of pupae by ion beam implantation was observed using scanning electron microscope. Some individuals with incomplete wing were obtained after implantation but no similar character was observed in their offspring. Furthermore, about 5.47% mutants with wide variation appeared in M1 generation. Therefore, ion beam implantation could be widely used for mutation breeding.

  12. Effect of noncircularity of experimental beam on CMB parameter estimation

    Science.gov (United States)

    Das, Santanu; Mitra, Sanjit; Tabitha Paulson, Sonu

    2015-03-01

    Measurement of Cosmic Microwave Background (CMB) anisotropies has been playing a lead role in precision cosmology by providing some of the tightest constrains on cosmological models and parameters. However, precision can only be meaningful when all major systematic effects are taken into account. Non-circular beams in CMB experiments can cause large systematic deviation in the angular power spectrum, not only by modifying the measurement at a given multipole, but also introducing coupling between different multipoles through a deterministic bias matrix. Here we add a mechanism for emulating the effect of a full bias matrix to the PLANCK likelihood code through the parameter estimation code SCoPE. We show that if the angular power spectrum was measured with a non-circular beam, the assumption of circular Gaussian beam or considering only the diagonal part of the bias matrix can lead to huge error in parameter estimation. We demonstrate that, at least for elliptical Gaussian beams, use of scalar beam window functions obtained via Monte Carlo simulations starting from a fiducial spectrum, as implemented in PLANCK analyses for example, leads to only few percent of sigma deviation of the best-fit parameters. However, we notice more significant differences in the posterior distributions for some of the parameters, which would in turn lead to incorrect errorbars. These differences can be reduced, so that the errorbars match within few percent, by adding an iterative reanalysis step, where the beam window function would be recomputed using the best-fit spectrum estimated in the first step.

  13. Size effects of effective Young's modulus for periodic cellular materials

    Institute of Scientific and Technical Information of China (English)

    DAI GaoMing; ZHANG WeiHong

    2009-01-01

    With the wide demands of cellular materials applications in aerospace and civil engineering, research effort sacrificed for this type of materials attains nowadays a higher level than ever before. This paper is focused on the prediction methods of effective Young's modulus for periodical cellular materials. Based on comprehensive studies of the existing homogenization method (HM), the G-A meso-me-chanice method (G-A MMM) and the stretching energy method (SEM) that are unable to reflect the size effect, we propose the bending energy method (BEM) for the first time, and a comparative study of these four methods is further made to show the generality and the capability of capturing the size effect of the BEM method. Meanwhile, the underlying characteristics of each method and their relations are clarified. To do this, the detailed finite element computing and existing experimental results of hex-agonal honeycombs from the literature are adopted as the standard of comparison for the above four methods. Stretch and bending models of periodical cellular materials are taken into account, respec-tively for the comparison of stretch and flexural displacements resulting from the above methods. We conclude that the BEM has the strong ability of both predicting the effective Young's modulus and re- vealing the size effect. Such a method is also able to predict well the variations of structural displace-ments in terms of the cell size under stretching and bending loads including the non-monotonous variations for the hexagonal cell. On the contrary, other three methods can only predict the limited re- sults whenever the cell size tends to be infinitely small.

  14. Causality in Statistical Power: Isomorphic Properties of Measurement, Research Design, Effect Size, and Sample Size

    Science.gov (United States)

    Heidel, R. Eric

    2016-01-01

    Statistical power is the ability to detect a significant effect, given that the effect actually exists in a population. Like most statistical concepts, statistical power tends to induce cognitive dissonance in hepatology researchers. However, planning for statistical power by an a priori sample size calculation is of paramount importance when designing a research study. There are five specific empirical components that make up an a priori sample size calculation: the scale of measurement of the outcome, the research design, the magnitude of the effect size, the variance of the effect size, and the sample size. A framework grounded in the phenomenon of isomorphism, or interdependencies amongst different constructs with similar forms, will be presented to understand the isomorphic effects of decisions made on each of the five aforementioned components of statistical power. PMID:27073717

  15. Causality in Statistical Power: Isomorphic Properties of Measurement, Research Design, Effect Size, and Sample Size

    Directory of Open Access Journals (Sweden)

    R. Eric Heidel

    2016-01-01

    Full Text Available Statistical power is the ability to detect a significant effect, given that the effect actually exists in a population. Like most statistical concepts, statistical power tends to induce cognitive dissonance in hepatology researchers. However, planning for statistical power by an a priori sample size calculation is of paramount importance when designing a research study. There are five specific empirical components that make up an a priori sample size calculation: the scale of measurement of the outcome, the research design, the magnitude of the effect size, the variance of the effect size, and the sample size. A framework grounded in the phenomenon of isomorphism, or interdependencies amongst different constructs with similar forms, will be presented to understand the isomorphic effects of decisions made on each of the five aforementioned components of statistical power.

  16. RF Wire Compensator of Long-Range Beam-Beam Effects

    CERN Document Server

    Dorda, U; Kroyer, T; Zimmermann, F

    2008-01-01

    The dynamic aperture of the proton beam circulating in the Large Hadron Collider (LHC) is expected to be limited by up to 120 long-range beam-beam encounters. In order to perfectly compensate the LHC long-range beambeam effect for nominal as well as for so-called "PACMAN" bunches, i.e. bunches at the start or end of a bunch train, the strength of a wire compensator should be adjusted for each bunch individually. Here an RF-based compensator is proposed as a practical solution for the PACMAN compensation. We show that this approach also allows relaxing the power and precision requirements compared with those of a pulsed DC device, to a level within the state-of-the-art of RF technology. Furthermore it permits the use of a passive circulator in the tunnel close to the beam and thus a significant reduction of the transmission line length and of the associated multiple reflections. Simulations of dynamic aperture and emittance growth, issues related to RF phase noise, and first experimental results from laborator...

  17. Interpreting and Reporting Effect Sizes in Research Investigations.

    Science.gov (United States)

    Tapia, Martha; Marsh, George E., II

    Since 1994, the American Psychological Association (APA) has advocated the inclusion of effect size indices in reporting research to elucidate the statistical significance of studies based on sample size. In 2001, the fifth edition of the APA "Publication Manual" stressed the importance of including an index of effect size to clarify…

  18. SU-E-T-454: Impact of Air Gap On PDDs of 6 MV Photon Beam for Various Field Sizes in Inhomogeneous Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Oyewale, S [Cancer Centers of Southwest Oklahoma, Lawton, OK (United States); Pokharel [21st Century Oncology, Estero, FL (United States); Singh, H [Procure Proton Therapy Center, Oklahoma City, OK (United States); Islam, M [University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Rana, S [ProCure Proton Therapy Center, Oklahoma City, OK (United States)

    2015-06-15

    Purpose: To investigate how the shape of air gap and its size will impact the percent depth doses (PDDs) of a 6MV photon beam for various field sizes. Methods: Two in-house phantoms were manufactured containing rectangular (phantom A) and circular (phantom B) air gaps. Both phantoms A and B were composed of same top layer (solid-water; 30×30cm{sup 2},5cm thickness) and bottom layer (solid-water; 30×30cm {sup 2},8cm thickness), but middle layer was varied to observe air gap effects and scatter contribution to the measurement point. In phantom A, a rectangular shaped air gap (30×30cm{sup 2},7cm thickness) was created by placing Styrofoam blocks between top and bottom layers of the phantom. In phantom B, middle layer was replaced by “inhomogenous block”, composed of acrylic plate (30×30cm{sup 2}, 4cm thickness) followed by PVC(30×30cm{sup 2},3cm thickness). Additionally, circular air gap was created by drilling a hole (diameter=2.8cm, length=7cm) at the center of “inhomogenous block”. In both phantoms, measurement readings were obtained at 13cm depth (i.e., 1cm after air gap) and depth of maximum dose(6MV energy; 100 MUs; field sizes ranged from 3×3cm{sup 2} to 10×10cm{sup 2}). The PDDs at 13cm depth were compared in both phantoms. Results: The measurements in both phantoms A and B showed an almost linear increase in PDDs with increasing field size, especially for smaller field sizes (from 3×3 to 7×7cm{sup 2}). For each field size, the PDD in phantom A was smaller compared to the one in phantom B. The difference in PDDs between two phantoms decreased with an increase in field size as the PDD difference decreased from 9.0% to 6.4%. Conclusion: The shape and size of air gap affect the PDD measurements in secondary build-up region as 6 MV primary beam traverses through the center of air gap. The scatter contribution due to increase in field size was more noticeable for field sizes ≤7×7cm{sup 2}.

  19. Vertical beam size measurement in the CESR-TA $e^+e^-$ storage ring using x-rays from synchrotron radiation

    CERN Document Server

    Alexander, J P; Conolly, C; Edwards, E; Ehrlichman, M P; Fontes, E; Heltsley, B K; Hopkins, W; Lyndaker, A; Peterson, D P; Rider, N T; Rubin, D L; Savino, J; Seeley, R; Shanks, J; Flanagan, J W

    2013-01-01

    We describe the construction and operation of an x-ray beam size monitor (xBSM), a device measuring $e^+$ and $e^-$ beam sizes in the CESR-TA storage ring using synchrotron radiation. The device can measure vertical beam sizes of $10-100~\\mu$m on a turn-by-turn, bunch-by-bunch basis at $e^\\pm$ beam energies of $\\sim2~$GeV. At such beam energies the xBSM images x-rays of $\\epsilon\\approx$1-10$~$keV ($\\lambda\\approx 0.1-1$ nm) that emerge from a hard-bend magnet through a single- or multiple-slit (coded aperture) optical element onto an array of 32 InGaAs photodiodes with 50$~\\mu$m pitch. Beamlines and detectors are entirely in-vacuum, enabling single-shot beam size measurement down to below 0.1$~$mA ($2.5\\times10^9$ particles) per bunch and inter-bunch spacing of as little as 4$~$ns. At $E_{\\rm b}=2.1 $GeV, systematic precision of $\\sim 1~\\mu$m is achieved for a beam size of $\\sim12~\\mu$m; this is expected to scale as $\\propto 1/\\sigma_{\\rm b}$ and $\\propto 1/E_{\\rm b}$. Achieving this precision requires compr...

  20. SIZE EFFECT ON THE BENDING AND TENSILE STRENGTH OF MICROMACHINED POLYSILICON FILMS FOR MEMS

    Institute of Scientific and Technical Information of China (English)

    DingJianning; YangJichang; WenShizhu

    2004-01-01

    The bending strength of microfabricated polysilicon beams was measured by beam bending using a nanoindenter. Also, the tensile strength of microfabricated polysilicon thin films was measured by tensile testing with a new microtensile test device. It was found that the bending strength and tensile strength of polysilicon microstructures exerts size effect on the size of the specimens. In such cases, the size effect can be traced back to the ratio of surface area to volume as the governing parameter. A statistical analysis of the bending strength for various specimen sizes shows that the average bending strength of polysilicon microcantilever beams is 2.885±0.408 GPa. The measured average value of Young's modulus, 164±1.2 GPa, falls within the theoretical bounds. The average fracture tensile strength is 1.36 GPa with a standard deviation of 0.14 GPa, and the Weibull modulus is 10.4-11.7, respectively. The tensile testing of 40 specimens on failure results in a recommendation for design that the nominal strain be maintained below 0.0057.

  1. Simple and cost-effective fabrication of size-tunable zinc oxide architectures by multiple size reduction technique

    Directory of Open Access Journals (Sweden)

    Hyeong-Ho Park, Xin Zhang, Seon-Yong Hwang, Sang Hyun Jung, Semin Kang, Hyun-Beom Shin, Ho Kwan Kang, Hyung-Ho Park, Ross H Hill and Chul Ki Ko

    2012-01-01

    Full Text Available We present a simple size reduction technique for fabricating 400 nm zinc oxide (ZnO architectures using a silicon master containing only microscale architectures. In this approach, the overall fabrication, from the master to the molds and the final ZnO architectures, features cost-effective UV photolithography, instead of electron beam lithography or deep-UV photolithography. A photosensitive Zn-containing sol–gel precursor was used to imprint architectures by direct UV-assisted nanoimprint lithography (UV-NIL. The resulting Zn-containing architectures were then converted to ZnO architectures with reduced feature sizes by thermal annealing at 400 °C for 1 h. The imprinted and annealed ZnO architectures were also used as new masters for the size reduction technique. ZnO pillars of 400 nm diameter were obtained from a silicon master with pillars of 1000 nm diameter by simply repeating the size reduction technique. The photosensitivity and contrast of the Zn-containing precursor were measured as 6.5 J cm−2 and 16.5, respectively. Interesting complex ZnO patterns, with both microscale pillars and nanoscale holes, were demonstrated by the combination of dose-controlled UV exposure and a two-step UV-NIL.

  2. Effect of high energy electron beam irradiation on the optical properties of nanocrystalline TiO 2

    OpenAIRE

    Priyanka, K. P.; SUNNY JOSEPH; ANUTRESA SUNNY; THOMAS VARGHESE

    2013-01-01

    The effect of high energy electron beam irradiation on the optical properties of TiO 2 nanoparticles was studied in order to improve the optical absorption performance and photoactivity. Electron beam irradiation may have resulted in size reduction, which in turn caused an increase of the optical band gap and photoluminescence intensity. Irradiation at a suitable dose rate was found to enhance the optical absorption performance and photoactivity of the tested TiO 2 nanoparticles.

  3. The pack size effect: Influence on consumer perceptions of portion sizes.

    Science.gov (United States)

    Hieke, Sophie; Palascha, Aikaterini; Jola, Corinne; Wills, Josephine; Raats, Monique M

    2016-01-01

    Larger portions as well as larger packs can lead to larger prospective consumption estimates, larger servings and increased consumption, described as 'portion-size effects' and 'pack size effects'. Although related, the effects of pack sizes on portion estimates have received less attention. While it is not possible to generalize consumer behaviour across cultures, external cues taken from pack size may affect us all. We thus examined whether pack sizes influence portion size estimates across cultures, leading to a general 'pack size effect'. We compared portion size estimates based on digital presentations of different product pack sizes of solid and liquid products. The study with 13,177 participants across six European countries consisted of three parts. Parts 1 and 2 asked participants to indicate the number of portions present in a combined photographic and text-based description of different pack sizes. The estimated portion size was calculated as the quotient of the content weight or volume of the food presented and the number of stated portions. In Part 3, participants stated the number of food items that make up a portion when presented with packs of food containing either a small or a large number of items. The estimated portion size was calculated as the item weight times the item number. For all three parts and across all countries, we found that participants' portion estimates were based on larger portions for larger packs compared to smaller packs (Part 1 and 2) as well as more items to make up a portion (Part 3); hence, portions were stated to be larger in all cases. Considering that the larger estimated portions are likely to be consumed, there are implications for energy intake and weight status.

  4. Effect size estimates: current use, calculations, and interpretation.

    Science.gov (United States)

    Fritz, Catherine O; Morris, Peter E; Richler, Jennifer J

    2012-02-01

    The Publication Manual of the American Psychological Association (American Psychological Association, 2001, American Psychological Association, 2010) calls for the reporting of effect sizes and their confidence intervals. Estimates of effect size are useful for determining the practical or theoretical importance of an effect, the relative contributions of factors, and the power of an analysis. We surveyed articles published in 2009 and 2010 in the Journal of Experimental Psychology: General, noting the statistical analyses reported and the associated reporting of effect size estimates. Effect sizes were reported for fewer than half of the analyses; no article reported a confidence interval for an effect size. The most often reported analysis was analysis of variance, and almost half of these reports were not accompanied by effect sizes. Partial η2 was the most commonly reported effect size estimate for analysis of variance. For t tests, 2/3 of the articles did not report an associated effect size estimate; Cohen's d was the most often reported. We provide a straightforward guide to understanding, selecting, calculating, and interpreting effect sizes for many types of data and to methods for calculating effect size confidence intervals and power analysis.

  5. Simulation of Proton Beam Effects in Thin Insulating Films

    Directory of Open Access Journals (Sweden)

    Ljubinko Timotijevic

    2013-01-01

    Full Text Available Effects of exposing several insulators, commonly used for various purposes in integrated circuits, to beams of protons have been investigated. Materials considered include silicon dioxide, silicon nitride, aluminium nitride, alumina, and polycarbonate (Lexan. The passage of proton beams through ultrathin layers of these materials has been modeled by Monte Carlo simulations of particle transport. Parameters that have been varied in simulations include proton energy and insulating layer thickness. Materials are compared according to both ionizing and nonionizing effects produced by the passage of protons.

  6. Size Effects in Heavy Ions Fragmentation

    CERN Document Server

    Barrañon, A; Dorso, C O

    2003-01-01

    Rise-Plateau Caloric curves for different Heavy Ion collisions have been obtained, in the range of experimental observations. Limit temperature decreases when the residual size is increased, in agreement with recent theoretical analysis of experimental results reported by other Collaborations. Besides, promptly emitted particles influence on temperature plateau is shown. LATINO binary interaction semiclassical model is used to reproduce the inter-nucleonic forces via Pandharipande Potential and fragments are detected with an Early Cluster Recognition Algorithm.

  7. Implementing the complete beam hardening effect of the bowtie filter versus scaling beam intensities: effects on dosimetric applications in computed tomography.

    Science.gov (United States)

    Lopez-Rendon, Xochitl; Zhang, Guozhi; Bosmans, Hilde; Oyen, Raymond; Zanca, Federica

    2014-10-01

    The bowtie filter is an essential element of computed tomography scanners. Implementation of this filter in a Monte Carlo dosimetry platform can be based on Turner's method, which describes how to measure the filter thickness and relate the x-ray beam as a function of bowtie angle to the central beam. In that application, the beam hardening is accounted for by means of weighting factors that are associated to the photons according to their position (fan angle) and energy. We assessed an alternative approximation in which the photon spectrum is given a fan angle-dependent scaling factor. The aim of our investigation was to evaluate the effects on dose accuracy estimation when using the gold standard bowtie filter method versus a beam scaling approximation method. In particular, we wanted to assess the percentage dose differences between the two methods for several water thicknesses representative for different patients of different body mass index. The largest percentage differences were found for the thickest part of the bowtie filter and increased with patient size.

  8. Effect of reconstruction parameters on defect detection in fan-beam SPECT

    Science.gov (United States)

    Gregoriou, George K.

    2002-05-01

    The effect of reconstruction parameters on the fan-beam filtered backprojection method in myocardial defect detection was investigated using an observer performance study and receiver operating characteristics (ROC) analysis. A mathematical phantom of the human torso was used to model the anatomy and Thallium-201 (Tl-201) uptake in humans. Half-scan fan-beam realistic projections were simulated using a low-energy high resolution (LEHR) collimator that incorporated the effects of photon attenuation, spatially varying detector response, scatter, and Poison noise. A focal length of 55 cm and a radius of rotation of 25 cm were used, which resulted to a magnification of two at the center of rotation and a maximum magnification of three in the reconstructed region of interest. By changing the reconstruction pixel size, five different projection bin width to reconstruction pixel size (PBWRPS) ratios were obtained which resulted in five classes of reconstructed images. Myocardial defects were simulated as Gaussian-shaped decreases in Tl-201 uptake distribution. The total projection count per 3 mm image slice was 44,000. A total of 96 reconstructed transaxial images from each one of the five classes were shown to eight observers for evaluation. The results indicate that the reconstruction pixel size has a significant effect on the quality of fan-beam SPECT images. Moreover, the study indicated that in order to ensure best image quality the PBWRPS ratio should be at least as large as the maximum possible magnification inside the reconstructed image array.

  9. Multiple helical scans and the reconstruction of over FOV-sized objects in cone-beam CT

    Institute of Scientific and Technical Information of China (English)

    Han Yu; Yan Bin; Li Lei; Yu Chao-Qun; Li Jian-Xin; Bao Shang-Lian

    2012-01-01

    In cone-beam computed tomography (CBCT),there are often cases where the size of the specimen is larger than the field of view (FOV) (referred to as over FOV-sized (OFS)).To acquire the complete projection data for OFS objects,some scan modes have been developed for long objects and short but over-wide objects.However,these modes still cannot meet the requirements for both longitudinally long and transversely wide objects.In this paper,we propose a multiple helical scan mode and a corresponding reconstruction algorithm for both longitudinally long and transversely wide objects.The simulation results show that our model can deal with the problem and that the results are acceptable,while the OFS object is twice as long compared with the FOV in the same latitude.

  10. Sample Size Calculations for Precise Interval Estimation of the Eta-Squared Effect Size

    Science.gov (United States)

    Shieh, Gwowen

    2015-01-01

    Analysis of variance is one of the most frequently used statistical analyses in the behavioral, educational, and social sciences, and special attention has been paid to the selection and use of an appropriate effect size measure of association in analysis of variance. This article presents the sample size procedures for precise interval estimation…

  11. Design of the 'half-size' ITER neutral beam source for the test facility ELISE

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, B. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85740 Garching (Germany)], E-mail: bernd.heinemann@ipp.mpg.de; Falter, H.; Fantz, U.; Franzen, P.; Froeschle, M.; Gutser, R.; Kraus, W.; Nocentini, R.; Riedl, R.; Speth, E.; Staebler, A.; Wuenderlich, D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85740 Garching (Germany); Agostinetti, P. [Consorzio RFX, EURATOM Association, Corso Stati Uniti 4, I-35127 Padova (Italy); Jiang, T. [Southwestern Institute of Physics, ChengDu (China)

    2009-06-15

    In 2007 the radio frequency driven negative hydrogen ion source developed at IPP in Garching was chosen by the ITER board as the new reference source for the ITER neutral beam system. In order to support the design and the commissioning and operating phases of the ITER test facilities ISTF and NBTF in Padua, IPP is presently constructing a new test facility ELISE (Extraction from a Large Ion Source Experiment). ELISE will be operated with the so-called 'half-size ITER source' which is an intermediate step between the present small IPP RF sources (1/8 ITER size) and the full size ITER source. The source will have approximately the width but only half the height of the ITER source. The modular concept with 4 drivers will allow an easy extrapolation to the full ITER size with 8 drivers. Pulsed beam extraction and acceleration up to 60 kV (corresponding to pre-acceleration voltage of SINGAP) is foreseen. The aim of the design of the ELISE source and extraction system was to be as close as possible to the ITER design; it has however some modifications allowing a better diagnostic access as well as more flexibility for exploring open questions. Therefore one major difference compared to the source of ITER, NBTF or ISTF is the possible operation in air. Specific requirements for RF sources as found on IPP test facilities BATMAN and MANITU are implemented [A. Staebler, et al., Development of a RF-driven ion source for the ITER NBI system, SOFT Conference 2008, Fusion Engineering and Design, 84 (2009) 265-268].

  12. Effect of noncircularity of experimental beam on CMB parameter estimation

    CERN Document Server

    Das, Santanu; Paulson, Sonu Tabitha

    2015-01-01

    Measurement of Cosmic Microwave Background (CMB) anisotropies has been playing a lead role in precision cosmology by providing some of the tightest constrains on cosmological models and parameters. However, precision can only be meaningful when all major systematic effects are taken into account. Non-circular beams in CMB experiments can cause large systematic deviation in the angular power spectrum, not only by modifying the measurement at a given multipole, but also introducing coupling between different multipoles through a deterministic bias matrix. Here we add a mechanism for emulating the effect of a full bias matrix to the Planck likelihood code through the parameter estimation code SCoPE. We show that if the angular power spectrum was measured with a non-circular beam, the assumption of circular Gaussian beam or considering only the diagonal part of the bias matrix can lead to huge error in parameter estimation. We demonstrate that, at least for elliptical Gaussian beams, use of scalar beam window fun...

  13. Microfocusing of the FERMI@Elettra FEL beam with a K–B active optics system: Spot size predictions by application of the WISE code

    Energy Technology Data Exchange (ETDEWEB)

    Raimondi, L., E-mail: lorenzo.raimondi@elettra.trieste.it [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); Svetina, C.; Mahne, N. [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); Cocco, D. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, MS-19 Menlo Park, CA 94025 (United States); Abrami, A.; De Marco, M.; Fava, C.; Gerusina, S.; Gobessi, R.; Capotondi, F.; Pedersoli, E.; Kiskinova, M. [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); De Ninno, G. [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); University of Nova Gorica, Vipavska 13, Rozna Dolina, SI-5000 Nova Gorica (Slovenia); Zeitoun, P. [Laboratoire d' Optique Appliquée, CNRS-ENSTA-École Polytechnique, Chemin de la Humiére, 91761 Palaiseau (France); Dovillaire, G. [Imagine Optic, 18 Rue Charles de Gaulle, 91400 Orsay (France); Lambert, G. [Laboratoire d' Optique Appliquée, CNRS-ENSTA-École Polytechnique, Chemin de la Humiére, 91761 Palaiseau (France); Boutu, W.; Merdji, H.; Gonzalez, A.I. [Service des Photons, Atomes et Molécules, IRAMIS, CEA-Saclay, Btiment 522, 91191 Gif-sur-Yvette (France); Gauthier, D. [University of Nova Gorica, Vipavska 13, Rozna Dolina, SI-5000 Nova Gorica (Slovenia); and others

    2013-05-11

    FERMI@Elettra, the first seeded EUV-SXR free electron laser (FEL) facility located at Elettra Sincrotrone Trieste has been conceived to provide very short (10–100 fs) pulses with ultrahigh peak brightness and wavelengths from 100 nm to 4 nm. A section fully dedicated to the photon transport and analysis diagnostics, named PADReS, has already been installed and commissioned. Three of the beamlines, EIS-TIMEX, DiProI and LDM, installed after the PADReS section, are in advanced commissioning state and will accept the first users in December 2012. These beam lines employ active X-ray optics in order to focus the FEL beam as well as to perform a controlled beam-shaping at focus. Starting from mirror surface metrology characterization, it is difficult to predict the focal spot shape applying only methods based on geometrical optics such as the ray tracing. Within the geometrical optics approach one cannot take into account the diffraction effect from the optics edges, i.e. the aperture diffraction, and the impact of different surface spatial wavelengths to the spot size degradation. Both these effects are strongly dependent on the photon beam energy and mirror incident angles. We employed a method based on physical optics, which applies the Huygens–Fresnel principle to reflection (on which the WISE code is based). In this work we report the results of the first measurements of the focal spot in the DiProI beamline end-station and compare them to the predictions computed with Shadow code and WISE code, starting from the mirror surface profile characterization.

  14. Experiments investigating the generation and transport of 10--12 MeV, 30-kA, mm-size electron beams with linear inductive voltage adders

    Energy Technology Data Exchange (ETDEWEB)

    Mazarakis, M.G.; Poukey, J.W.; Maenchen, J.E.

    1997-06-01

    The authors present the design, analysis, and results of the high-brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: 8--12 MeV, 35--50 kA, 30--60 ns FWHM, and 0.5-mm rms beam radius. The accelerators utilized are SABRE and HERMES III. Both are linear inductive voltage adders modified to higher impedance and fitted with magnetically immersed foil less electron diodes. In the strong 20--50 Tesla solenoidal magnetic field of the diode, mm-size electron beams are generated and propagated to a beam stop. The electron beam is field emitted from mm-diameter needle-shaped cathode electrode and is contained in a similar size envelop by the strong magnetic field. These extremely space charge dominated beams provide the opportunity to study beam dynamics and possible instabilities in a unique parameter space. The SABRE experiments are already completed and have produced 30-kA, 1.5-mm FWHM electron beams, while the HERMES-III experiments are on-going.

  15. Application of size effect to compressive strength of concrete members

    Indian Academy of Sciences (India)

    Jin-Keun Kim; Seong-Tae Yi

    2002-08-01

    It is important to consider the effect of size when estimating the ultimate strength of a concrete member under various loading conditions. Well known as the size effect, the strength of a member tends to decrease when its size increases. Therefore, in view of recent increased interest in the size effect of concrete this research focuses on the size effect of two main classes of compressive strength of concrete: pure axial compressive strength and flexural compressive strength. First, fracture mechanics type size effect on the compressive strength of cylindrical concrete specimens was studied, with the diameter, and the height/diameter ratio considered as the main parameters. Theoretical and statistical analyses were conducted, and a size effect equation was proposed to predict the compressive strength specimens. The proposed equation showed good agreement with the existing test results for concrete cylinders. Second, the size, length, and depth variations of a flexural compressive member have been studied experimentally. A series of -shaped specimens subjected to axial compressive load and bending moment were tested. The shape of specimens and the test procedures used were similar to those by Hognestad and others. The test results are curve-fitted using Levenberg-Marquardt’s least squares method (LSM) to obtain parameters for the modified size effect law (MSEL) by Kim and co workers. The results of the analysis show that the effect of specimen size, length, and depth on ultimate strength is significant. Finally, more general parameters for MSEL are suggested.

  16. Measurements of effective total macroscopic cross sections and effective energy of continuum beam

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Hisao [Rikkyo Univ., Yokosuka, Kanagawa (Japan). Inst. for Atomic Energy

    1998-03-01

    Two practically useful quantities are introduced in this study to characterize a continuum neutron beam and to describe transmission phenomena of the beam in field of quantitative neutron radiography: an effective energy instead of a peak energy or a mean energy of the spectrum and an effective total macroscopic (ETM) cross section instead of a total macroscopic (TM) cross section defined at the monochromatic energy. The effective energy was evaluated by means of energy dependence of ETM cross section. To realize the method a beam quality indicator (BQI) has been proposed recently. Several effective energies were measured for non-filtered, filtered neutron beams, and outputs of neutron guide tubes in world by the BQI. A thermal neutron beam and three beams modulated by Pb filters with different thicknesses are studied to measure ETM cross sections for various materials and summarized in a table. Validity of the effective energy determined by the BQI is discussed relating with ETM cross sections of materials. (author)

  17. Quantum effects in beam-plasma instabilities

    CERN Document Server

    Bret, A

    2015-01-01

    Among the numerous works on quantum effects that have been published in recent years, streaming instabilities in plasma have also been revisited. Both the fluid quantum and the kinetic Wigner-Maxwell models have been used to explore quantum effects on the Weibel, Filamentation and Two-Stream instabilities. While quantum effects usually tend to reduce the instabilities, they can also spur new unstable branches. A number of theoretical results will be reviewed together with the implications to one physical setting, namely the electron driven fast ignition scenario.

  18. Size, effect of flexible proof mass on the mechanical behavior of micron-scale cantilevers for energy harvesting appications.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M.; Hong, S.; Miller, D. J.; Dugundji, J.; Wardle, B. L. (Materials Science Division); (MIT)

    2011-12-15

    Mechanical behavior of micron-scale cantilevers with a distributed, flexible proof mass is investigated to understand proof mass size effects on the performance of microelectromechanical system energy harvesters. Single-crystal silicon beams with proof masses of various lengths were fabricated using focused ion beam milling and tested using atomic force microscopy. Comparison of three different modeling results with measured data reveals that a 'two-beam' method has the most accurate predictive capability in terms of both resonant frequency and strain. Accurate strain prediction is essential because energy harvested scales with strain squared and maximum strain will be a design limit in fatigue.

  19. Proximity effect in ion-beam-induced deposition of nanopillars

    NARCIS (Netherlands)

    Chen, P.; Salemink, H.W.M.; Alkemade, P.F.A.

    2009-01-01

    Ion-beam-induced deposition (IBID) is a powerful technique for prototyping three-dimensional nanostructures. To study its capability for this purpose, the authors investigate the proximity effect in IBID of nanopillars. In particular, the changes in shape and dimension of pillars are studied when a

  20. Effects of ion beam irradiation on semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Nashiyama, Isamu; Hirao, Toshio; Itoh, Hisayoshi; Ohshima, Takeshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    Energetic heavy-ion irradiation apparatus has been developed for single-event effects (SEE) testing. We have applied three irradiation methods such as a scattered-ion irradiation method, a recoiled-atom irradiation method, and a direct-beam irradiation method to perform SEE testing efficiently. (author)

  1. Investigation of effect of electron beam on various polyethylene blends

    CERN Document Server

    Morshedian, J

    2003-01-01

    With regards to the expanding usage of electron beams irradiation in polymer industries such as sterilization of polymeric disposable medical products; cable manufacturing; pipes, heat shrinkable materials, etc. In this project the effect of electron beam on polyethylene used in manufacturing of pipe and heat shrinkable products was studied. Results showed that by increasing the applied dose on samples; the crosslink density would increase and polymers with tertiary carbon atoms in their backbone structure tend to crosslink more readily. The melting temperature and crystallinity percent decreased and degradation temperature increased. Density in low doses decreased and in high doses increased.

  2. Effect of beam-pointing errors on bistatic SAR imaging

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The purpose is to conduct a research in the energy variation of echo wave and the imaging effect caused by the aero bistatic SAR pointing errors.Based on the moving geometry configuration of aero bistatic SAR,a model of beam pointing errors is built.Based on this,the azimuth Doppler frequency center estimation caused by these errors and the limitation to the beam pointing synchronization error are studied,and then the imaging result of different errors are analyzed.The computer's simulations are provided to prove the validity of the above analysis.

  3. Irradiation Effects on RIA Fragmentation Cu Beam Dump

    CERN Document Server

    Reyes, Susana; Boles, Jason; Stein, Werner; Wirth, Brian

    2005-01-01

    Within the scope of conceptual R&D activities in support of the Rare-Isotope Accelerator (RIA) facility, high priority is given to the development of high-power fragmentation beam dumps. A pre-study was made of a static water-cooled Cu beam dump that can meet requirements for a 400 MeV/u uranium beam. The issue of beam sputtering was addressed and found to be not a significant issue. Preliminary radiation transport simulations show significant damage (dpa) in the vicinity of the Bragg peak of uranium ions. Experimental data show that defects in Cu following neutron or high-energy particle irradiation tend to saturate at doses between 1 and 5 dpa, and this saturation in defect density also results in saturation of mechanical property degradation. However, effects of swift heavy ion irradiation and the production of gaseous and solid transmutant elements still need to be addressed. Initial calculations indicate that He concentrations on the order of 100 appm are produced in the beam dump after several weeks...

  4. Size effect on compressive strength of reactive powder concrete

    Institute of Scientific and Technical Information of China (English)

    AN Ming-zhe; ZHANG Li-jun; YI Quan-xin

    2008-01-01

    In this paper the coefficient and law of the size effect of RPC were studied through experiments and theoretical analysis. The size-effect coefficients for the compressive strength of RPC are deduced through experiments. They indicate that RPC without fiber behaves quite the same as normal or high strength concrete. The size effect on compressive strength is more prominent in RPC containing fiber. Bazant's size effect formula of compressive strength applies to RPC. A formula is given to predict the compressive strength of cubic RPC specimens 100 mm on a side where the fiber dosage ranges from 0-2%.

  5. Effect of electron beam irradiation on seed germination

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seunghee; Bae, Youngmin [Changwon Univ., Changwon (Korea, Republic of)

    2013-07-01

    Effect of electron beam irradiation on seed germination was investigated in this research. Electron beam of 0.5, 1.0, 1.5 and 2.0 kGy was irradiated to the seeds of lettuce, green onion and cucumber, and the irradiated seeds were incubated at 25 .deg. Cn Nitsch medium solidified with 0.2% Phytagel. Germination percentage and the length of the sprouts were determined after 72 hours. Germination percentage of lettuce seeds was greatly reduced by the irradiation, and that of the green onion and cucumber were moderately reduced or unchanged by the irradiation. Although average length of the lettuce sprouts was reduced severely, that of the green onion and cucumber was unchanged or moderately reduced. Conclusively, electron beam irradiation might be a useful way of disinfecting some plant seeds including green onion and cucumber.

  6. Adaptive beamlet-based finite-size pencil beam dose calculation for independent verification of IMRT and VMAT

    Energy Technology Data Exchange (ETDEWEB)

    Park, Justin C.; Li, Jonathan G.; Arhjoul, Lahcen; Yan, Guanghua; Lu, Bo; Fan, Qiyong; Liu, Chihray, E-mail: liucr@ufl.edu [Department of Radiation Oncology, University of Florida, Gainesville, Florida 32610-0385 (United States)

    2015-04-15

    Purpose: The use of sophisticated dose calculation procedure in modern radiation therapy treatment planning is inevitable in order to account for complex treatment fields created by multileaf collimators (MLCs). As a consequence, independent volumetric dose verification is time consuming, which affects the efficiency of clinical workflow. In this study, the authors present an efficient adaptive beamlet-based finite-size pencil beam (AB-FSPB) dose calculation algorithm that minimizes the computational procedure while preserving the accuracy. Methods: The computational time of finite-size pencil beam (FSPB) algorithm is proportional to the number of infinitesimal and identical beamlets that constitute an arbitrary field shape. In AB-FSPB, dose distribution from each beamlet is mathematically modeled such that the sizes of beamlets to represent an arbitrary field shape no longer need to be infinitesimal nor identical. As a result, it is possible to represent an arbitrary field shape with combinations of different sized and minimal number of beamlets. In addition, the authors included the model parameters to consider MLC for its rounded edge and transmission. Results: Root mean square error (RMSE) between treatment planning system and conventional FSPB on a 10 × 10 cm{sup 2} square field using 10 × 10, 2.5 × 2.5, and 0.5 × 0.5 cm{sup 2} beamlet sizes were 4.90%, 3.19%, and 2.87%, respectively, compared with RMSE of 1.10%, 1.11%, and 1.14% for AB-FSPB. This finding holds true for a larger square field size of 25 × 25 cm{sup 2}, where RMSE for 25 × 25, 2.5 × 2.5, and 0.5 × 0.5 cm{sup 2} beamlet sizes were 5.41%, 4.76%, and 3.54% in FSPB, respectively, compared with RMSE of 0.86%, 0.83%, and 0.88% for AB-FSPB. It was found that AB-FSPB could successfully account for the MLC transmissions without major discrepancy. The algorithm was also graphical processing unit (GPU) compatible to maximize its computational speed. For an intensity modulated radiation therapy (

  7. Analysis of the variation of the attenuation curve in function of the radiation field size for k Vp X-ray beams using the MCNP-5C code

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Marco A.R., E-mail: marco@cetea.com.b, E-mail: marfernandes@fmb.unesp.b [Universidade Estadual Paulista Julio de Mesquita Filho (FMB/UNESP), Botucatu, SP (Brazil). Fac. de Medicina; Ribeiro, Victor A.B. [Universidade Estadual Paulista Julio de Mesquita Filho (IBB/UNESP), Botucatu, SP (Brazil). Inst. de Biociencias; Viana, Rodrigo S.S.; Coelho, Talita S. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The paper illustrates the use of the Monte Carlo method, MCNP-5C code, to analyze the attenuation curve behavior of the 50 kVp radiation beam from superficial radiotherapy equipment as Dermopan2 model. The simulations seek to verify the MCNP-5C code performance to study the variation of the attenuation curve - percentage depth dose (PDD) curve - in function of the radiation field dimension used at radiotherapy of skin tumors with 50 kVp X-ray beams. The PDD curve was calculated for six different radiation field sizes with circular geometry of 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 cm in diameter. The radiation source was modeled considering a tungsten target with inclination 30 deg, focal point of 6.5 mm in diameter and energy beam of 50 kVp; the X-ray spectrum was calculated with the MCNP-5C code adopting total filtration (beryllium window of 1 mm and aluminum additional filter of 1 mm). The PDD showed decreasing behavior with the attenuation depth similar what is presented on the literature. There was not significant variation at the PDD values for the radiation field between 1.0 and 4.0 cm in diameter. The differences increased for fields of 5.0 and 6.0 cm and at attenuation depth higher than 1.0 cm. When it is compared the PDD values for fields of 3.0 and 6.0 cm in diameter, it verifies the greater difference (12.6 %) at depth of 5.7 cm, proving the scattered radiation effect. The MCNP-5C code showed as an appropriate procedure to analyze the attenuation curves of the superficial radiotherapy beams. (author)

  8. Poly(methyl methacrylate) Composites with Size-selected Silver Nanoparticles Fabricated Using Cluster Beam Technique

    DEFF Research Database (Denmark)

    Muhammad, Hanif; Juluri, Raghavendra R.; Chirumamilla, Manohar;

    2016-01-01

    tendency to flattening upon impact. By controlling the polymer hardness (from viscous to soft state) prior the cluster deposition and annealing conditions after the deposition the degree of immersion of the nanoparticles into polymer can be tuned, thus, making it possible to create composites with either......An embedment of metal nanoparticles of well-defined sizes in thin polymer films is of significant interest for a number of practical applications, in particular, for preparing materials with tunable plasmonic properties. In this article, we present a fabrication route for metal–polymer composites...... particles partly or fully embedded into the film. Good size selection and rather homogeneous dispersion of nanoparticles in the thin polymer film lead to excellent plasmonic properties characterized by the narrow band and high quality factor of localized surface plasmon resonance....

  9. Simulation of electron cloud effects to heavy ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, Fatih; Gjonaj, Erion; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder

    2011-07-01

    Electron cloud (EC) driven instability can cause beam loss, emittance growth, trajectory change and wake fields. Mentioned crucial effects of EC motivated researchers to understand the EC build up mechanism and the effects of EC to the beam. This motivation also induced the progress of developing new simulation codes. EC simulations can roughly be divided into two classes such as, softwares whose goals are to simulate the build up of the EC during the passage of a bunch train and the codes which model the interaction of a bunch with an EC. The aim of this study is to simulate the effects of electron cloud (EC) on the dynamics of heavy ion beams which are used in heavy ion synchrotron (SIS-18) at GSI. To do this, a 3-D and self-consistent simulation program based on particle in cell (PIC) method is used. In the PIC cycle, accurate solution of the Maxwell equations is obtained by employing discontinuous Galerkin finite element method. As a model, we assumed a perfectly conducting beam pipe which was uniformly (or randomly) loaded with the electrons. Then as parallel with the realistic cases in SIS-18, a single bunch consisting of U{sup +73} ions was extracted which could propagate in this pipe. Due to EC-ion bunch interaction, electrons gained energy and their displacements were observed. Electric and magnetic field components and EC charge density were calculated, numerically.

  10. Effect of electron beam on chemical changes of nutrients in infant formula.

    Science.gov (United States)

    Tesfai, Adiam; Beamer, Sarah K; Matak, Kristen E; Jaczynski, Jacek

    2014-04-15

    Infant milk formula has recently been implicated as a transmission vehicle for an emerging foodborne pathogen, Enterobacter sakazakii, resulting in high mortality rates. Electron beam (e-beam) efficiently and non-thermally inactivates foodborne pathogens, including E. sakazakii, in infant milk formula. However, the effects of e-beam on chemical changes of nutrients in infant formula have not been determined. Therefore, the objective of this study was to fulfill this gap. Dehydrated infant milk formula was processed with e-beam at 0 (control) to 25 kGy. Amino acid, fatty acid, and mineral profiles (AAP, FAP, and MP, respectively), as well as protein degradation and lipid oxidation, were determined. There were no differences (P>0.05) in FAP, AAP, and MP. SDS-PAGE electrophoresis qualitatively detected three major protein bands in all samples up to 25 kGy. Densitometry analysis of SDS-PAGE gels confirmed no size degradation (P>0.05) as a function of increased e-beam dose. Totol-volatile-basic-nitrogen (TVBN) excluded (P>0.05) protein degradation due to microbial activity. There was no increase (P>0.05) in lipid oxidation, as assessed with thiobarbituric-reactive-substances (TBARS), except in samples processed at 25 kGy. Dehydrated formula has low water activity, which likely protected nutrients from e-beam-induced chemical changes. This study demonstrates that proteins, lipids, and minerals in infant milk formula are stable when processed with e-beam up to 25 kGy at low temperature and under anaerobic conditions.

  11. Size Effect for Normal Strength Concrete in Uniaxial Tension

    Institute of Scientific and Technical Information of China (English)

    李庆斌; 尹玉先

    2004-01-01

    This paper presents a new size effect model for normal strength concrete subjected to uniaxial tension. The model is based on two extremes, sand cement paste in uniaxial tension and a sand-cement-paste/rock interface in uniaxial tension. Uniaxial tension tests with normal strength concrete measuring the tensile strength of normal strength concrete specimens with different geometrical shapes and different ratios of the aggregate size to the characteristic dimension of the concrete specimen show a significant size effect. The theoretical size effect law prediction agrees well with the experimental data.

  12. Friction related size-effect in microforming – a review

    Directory of Open Access Journals (Sweden)

    Wang Chunju

    2014-01-01

    Full Text Available This paper presents a thorough literature review of the size effects of friction in microforming. During miniaturization, the size effects of friction occur clearly. The paper first introduces experimental research progress on size effects of friction in both micro bulk and sheet forming. The effects of several parameters are discussed. Based on the experimental results, several approaches have been performed to develop a model or functions to analyse the mechanism of size effects of friction, and simulate the micro deep drawing process by integrating them into an FE program. Following this, surface modification, e.g. a DLC film and a micro structure/textured surface, as a method to reduce friction are presented. Finally, the outlook for the size effect of friction in the future is assessed, based on the understanding of the current research progress.

  13. Quantum size effects in InP inner film fiber

    Institute of Scientific and Technical Information of China (English)

    WANG Ting-yun; WANG Ke-xin; LU Jun

    2005-01-01

    Based on the semiconductor amplifiing properties and the structure of optical fiber wave guide an InP inner fiber is developed.The InP inner film fiber can be employed as a small size,broadband,and ultra-short fiber amplifier.The quantum size effects of the fiber are emphatically investigated in the work.Using the experimental data,we compare the effective mass approximation (EMA) with effective parameterization within the tight binding (EPTB) models for the accurate description of the quantum size effects in InP.The results show that the EPTB model provides an excellent description of band gap variation over a wide range of sizes.The Bohr diameter and the effective Rydberg energy of InP are calculated.Finally,the amplifiing properties of the InP inner film fiber are discussed due to the quantum size effects.

  14. Ion beam radiation effects in monazite

    Energy Technology Data Exchange (ETDEWEB)

    Picot, V. [Institut de Chimie Separative de Marcoule, UMR 5257, BP 17171, 30207 Bagnols-sur-Ceze (France); Deschanels, X. [Institut de Chimie Separative de Marcoule, UMR 5257, BP 17171, 30207 Bagnols-sur-Ceze (France)], E-mail: xavier.deschanels@cea.fr; Peuget, S. [CEA Centre de Marcoule, BP 17171, 30207 Bagnols-sur-Ceze (France); Glorieux, B. [Laboratoire des Procedes, Materiaux et Energie Solaire, UPR 8521, Rambla de la Thermodynamique, 66100 Perpignan (France); Seydoux-Guillaume, A.M. [Laboratoire des Mecanismes et Transferts en Geologie, CNRS, Universite Paul Sabatier, IRD, OMP, 14 Avenue Edouard Belin, 31400 Toulouse (France); Wirth, R. [GeoForschungsZentrum Potsdam, PB 4.1, Telegrafenberg, 14473 Potsdam (Germany)

    2008-11-15

    Monazite is a potential matrix for conditioning minor actinides arising from spent fuel reprocessing. The matrix behavior under irradiation must be investigated to ensure long-term containment performance. Monazite compounds were irradiated by gold and helium ions to simulate the consequences of alpha decay. This article describes the effects of such irradiation on the structural and macroscopic properties (density and hardness) of monazites LaPO{sub 4} and La{sub 0.73}Ce{sub 0.27}PO{sub 4}. Irradiation by gold ions results in major changes in the material properties. At a damage level of 6.7 dpa, monazite exhibits volume expansion of about 8.1%, a 59% drop in hardness, and structure amorphization, although Raman spectroscopy analysis shows that the phosphate-oxygen bond is unaffected. Conversely, no change in the properties of these compounds was observed after He ion implantation. These results indicate that ballistic effects predominate in the studied dose range.

  15. Developer molecular size dependence of pattern formation of polymer type electron beam resists with various molecular weights

    Science.gov (United States)

    Takayama, Tomohiro; Asada, Hironori; Kishimura, Yukiko; Ochiai, Shunsuke; Hoshino, Ryoichi; Kawata, Atsushi

    2016-05-01

    The sensitivity and the resolution are affected by not only the nature of the resist such as a chemical structure and a molecular weight but also the developing process such as a developer molecular size. Exposure characteristics of positive-tone polymer resists having various molecular weights (Mw's) ranging from 60 k to 500 k are investigated using different ester solvents as a developer. The line-and-space (L/S) patterns are exposed by the electron beam writing system with an acceleration voltage of 50 kV and the samples are developed by amyl acetate, hexyl acetate and heptyl acetate. The pattern shape becomes better and the surface of the resist also becomes smoother with increasing developer molecular size, though the exposure dose required for the formation of the L/S pattern increases. The dose margin of pattern formation is also wider in all the resists having the different molecular weights. The dissolution in the unexposed portions of the 60k-Mw resist for heptyl acetate is reduced significantly compared with those for amyl acetate and hexyl acetate. The improvement of the pattern shape and the increasing of dose margin are remarkable in the low molecular weight resist. The 3σ of line width roughness tends to be smaller in the higher molecular weight resist and with the larger molecular size developer. Exposure experiment of the 35 nm pitch pattern using the 500k-Mw resist developed at the room temperature is presented.

  16. Thermal effects in high power cavities for photoneutralization of D- beams in future neutral beam injectors

    Science.gov (United States)

    Fiorucci, Donatella; Feng, Jiatai; Pichot, Mikhaël; Chaibi, Walid

    2015-04-01

    Photoneutralization may represent a key issue in the neutral beam injectors for future fusion reactors. In fact, photodetachment based neutralization combined with an energy recovery system increase the injector overall efficiency up to 60%. This is the SIPHORE injector concept in which photoneutralization is realized in a refolded cavity [1]. However, about 1 W of the several megaWatts intracavity power is absorbed by the mirrors coatings and gives rise to important thermoelastic distortions. This is expected to change the optical behavior of the mirrors and reduce the enhancement factor of the cavity. In this paper, we estimate these effects and we propose a thermal system to compensate it.

  17. Loss of acoustic black hole effect in a structure of finite size

    Science.gov (United States)

    Tang, Liling; Cheng, Li

    2016-07-01

    The Acoustic Black Hole (ABH) effect takes place in thin-walled structures with diminishing thickness as a result of the reduction in the bending wave speed. It was shown to exist as a broadband phenomenon, based on wave propagation theory in structures of semi-infinite size. The ABH effect exhibits appealing features for various applications, such as passive vibration control, energy harvesting, and sound radiation control. In this paper, we demonstrate the disappearance of the ABH effect in a finite beam at specific frequency ranges above the cut-on frequency, both experimentally and theoretically. Analyses show that the phenomenon takes place at frequencies which are close to the low order local resonant frequencies of the portion of the beam demarcated by the position of the excitation force. These frequencies can be predicted so that the phenomenon can be avoided for the targeted frequency ranges in ABH applications.

  18. MODE II FRACTURE PARAMETERS FOR VARIOUS SIZES OF BEAMS IN PLAIN CONCRETE

    Directory of Open Access Journals (Sweden)

    Darsigunta Seshaiah

    2015-11-01

    Full Text Available Blended aggregate in concrete and arriving at the structural properties of blended aggregate concrete is a thrust area. Pumice is very light and porous igneous rock that is formed during volcanic eruptions.Cinder is a waste material obtained from steel manufacturing units. Shear strength is a property of major significance for wide range of civil engineering materials and structures. Shear and punching shear failures particularly in deep beams, in corbels and in concrete flat slabs are considered to be more critical and catastrophic than other types of failures. This area has received greater attention in recent years. For investigating shear type of failures, from the literature it is found that double central notched (DCN specimen geometry proposed by Prakash Desai and V.Bhaskar Desai is supposed the best suited geometry. In this present experimental investigation an attempt is made to study the Mode-II fracture property of light weight blended aggregate cement concrete combining both the pumice and cinder in different proportions, and making use of DCN test specimen geometry . By blending the pumice and cinder in different percentages of 0, 25, 50, 75 and 100 by volumeof concrete, a blended light weight aggregate concrete is prepared. By using this the property such as in plane shear strength is studied. Finally an analysis is carried out regarding Mode-II fracture properties of blended concrete. It is concluded that the Ultimate load in Mode-II is found to decrease continuously with the percentage increase in Pumice aggregate content. It is also observed that the ultimate stress in Mode II is found to increase continuously with percentage increase in cinder aggregate content.

  19. Relativistic Beaming and Orientation Effects in BL Lacertae Objects

    Indian Academy of Sciences (India)

    F. C. Odo; A. A. Ubachukwu; A. E. Chukwude

    2012-09-01

    We use the correlation between the core-to-lobe radio luminosity ratio () and the linear size () of a sample of BL Lacertae objects to investigate the relativistic beaming and radio source orientation paradigm for high peaked and low-peaked BL Lacs (X-ray and radio selected BL Lacs respectively) and to constrain relativistic beaming model for this extreme class of active galactic nuclei. We show that the - distributions of the BL Lac populations contradict blazar orientation sequence, with the X-ray selected BL Lacs (XBLs) being more consistent with the beaming and orientation model. On the premise that Fanaroff-Riley Type I radio galaxies are the unbeamed parent population of these objects, we derive the bulk Lorentz factor of the jets, ∼ 7-20 corresponding to a critical cone angle for optimum boosting, c of ∼ 1° - 4°, while on average, these objects are inclined at 5° - 12° to the line-of-sight. The implications of these results for the blazar unification sequence are discussed.

  20. An Effect Size for Regression Predictors in Meta-Analysis

    Science.gov (United States)

    Aloe, Ariel M.; Becker, Betsy Jane

    2012-01-01

    A new effect size representing the predictive power of an independent variable from a multiple regression model is presented. The index, denoted as r[subscript sp], is the semipartial correlation of the predictor with the outcome of interest. This effect size can be computed when multiple predictor variables are included in the regression model…

  1. Effect of Proton Beam on Cancer Progressive and Metastatic Enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Y. H.; Nam, K. S.; Oh, Y. H.; Kim, M. K.; Kim, M. Y.; Jang, J. S. [Dongguk University, Seoul (Korea, Republic of)

    2008-04-15

    The purpose of this study was to investigate the effect of proton beam on enzymes for promotion/progression of carcinogenesis and metastasis of malignant tumor cells to clarify proton beam-specific biological effects. The changes of cancer chemopreventive enzymes in human colorectal adenocarcinoma HT-29 cells irradiated with proton beams were tested by measuring the activities of quinine reductase (QR), glutathione S-transferase (GST), and ornithine decarboxylase (ODC), glutathione (GSH) levels, and expression of cyclooxygenase-2 (COX-2). We also examined the effect of proton beam on the ODC activity and expression of COX-2 in human breast cancer cell. We then assessed the metastatic capabilities of HT-29 and MDA-MB-231 cells irradiated with proton beam by measuring the invasiveness of cells through Matrigel-coated membrane and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MMP activity in MDA-MB-231 and HT-29 cells. QR activity of irradiated HT-29 cells was slightly increased. Proton irradiation at dose of 32 Gy in HT-29 cells increased GST activity by 1.23-fold. In addition GSH levels in HT-29 cells was significantly increased 1.23- (p<0.05), 1.32- (p<0.01) and 1.34-fold (p<0.01) with the proton irradiation at doses of 8, 16 and 32 Gy, respectively. These results suggest that colon cancer chemopreventive activity was increased with the proton irradiation by increasing QR and GST activities and GSH levels and inhibiting ODC activity. Proton ion irradiation decreased the invasiveness of TPA-treated HT-29 cells and MDA-MB-231 cells through Matrigel-coated membrane. Proton ion irradiation pretreatment decreased TPA-induced MMP activity in MDA-MB-231 and HT-29 cells. Further studies are necessary to investigate if these findings could be translated to in vivo situations

  2. A GPU-based finite-size pencil beam algorithm with 3D-density correction for radiotherapy dose calculation

    CERN Document Server

    Gu, Xuejun; Li, Jinsheng; Jia, Xun; Jiang, Steve B

    2011-01-01

    Targeting at developing an accurate and efficient dose calculation engine for online adaptive radiotherapy, we have implemented a finite size pencil beam (FSPB) algorithm with a 3D-density correction method on GPU. This new GPU-based dose engine is built on our previously published ultrafast FSPB computational framework [Gu et al. Phys. Med. Biol. 54 6287-97, 2009]. Dosimetric evaluations against MCSIM Monte Carlo dose calculations are conducted on 10 IMRT treatment plans with heterogeneous treatment regions (5 head-and-neck cases and 5 lung cases). For head and neck cases, when cavities exist near the target, the improvement with the 3D-density correction over the conventional FSPB algorithm is significant. However, when there are high-density dental filling materials in beam paths, the improvement is small and the accuracy of the new algorithm is still unsatisfactory. On the other hand, significant improvement of dose calculation accuracy is observed in all lung cases. Especially when the target is in the m...

  3. Operational Experiences Tuning the ATF2 Final Focus Optics Towards Obtaining a 37nm Electron Beam IP Spot Size

    CERN Document Server

    White, Glen; Woodley, Mark; Bai, Sha; Bambade, Philip; Renier, Yves; Bolzon, Benoit; Kamiya, Yoshio; Komamiya, Sachio; Oroku, Masahiro; Yamaguchi, Yohei; Yamanaka, Takashi; Kubo, Kiyoshi; Kuroda, Shigeru; Okugi, Toshiyuki; Tauchi, Toshiaki; Marin, Eduardo

    2010-01-01

    The primary aim of the ATF2 research accelerator is to test a scaled version of the final focus optics planned for use in next-generation linear lepton colliders. ATF2 consists of a 1.3 GeV linac, damping ring providing lowemittance electron beams (<12pm in the vertical plane), extraction line and final focus optics. The design details of the final focus optics and implementation at ATF2 are presented elsewhere. The ATF2 accelerator is currently being commissioned, with a staged approach to achieving the design IP spot size. It is expected that as we implement more demanding optics and reduce the vertical beta function at the IP, the tuning becomes more difficult and takes longer. We present here a description of the implementation of the tuning procedures and describe operational experiences and performances

  4. Focused Ion Beam Induced Effects on MOS Transistor Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Abramo, Marsha T.; Antoniou, Nicholas; Campbell, Ann N.; Fleetwood, Daniel M.; Hembree, Charles E.; Jessing, Jeffrey R.; Soden, Jerry M.; Swanson, Scot E.; Tangyunyong, Paiboon; Vanderlinde, William E.

    1999-07-28

    We report on recent studies of the effects of 50 keV focused ion beam (FIB) exposure on MOS transistors. We demonstrate that the changes in value of transistor parameters (such as threshold voltage, V{sub t}) are essentially the same for exposure to a Ga+ ion beam at 30 and 50 keV under the same exposure conditions. We characterize the effects of FIB exposure on test transistors fabricated in both 0.5 {micro}m and 0.225 {micro}m technologies from two different vendors. We report on the effectiveness of overlying metal layers in screening MOS transistors from FIB-induced damage and examine the importance of ion dose rate and the physical dimensions of the exposed area.

  5. Size Effects in Linear Elastic Fracture Mechanics

    Science.gov (United States)

    1988-01-01

    Recent Theoretical and Experimental Developments in Fracture Mechanics", Fracture 1977, 1 (1977) 695-723. 40 S. Mindess and J. S. Nadeau," Effect of Notch...0.4 1.42 b 2.0 0.80 b Mindess and Nadeau [40], 1.0 3.98 0.86 b Mortar, 3PB 8.03 0.80 b 12.0 0.82 b 16.0 0.84 b 20.0 0.83 b Concrete, 3PB 1.0 3.54 1.08

  6. Effects of anisotropic turbulence on average polarizability of Gaussian Schell-model quantized beams through ocean link.

    Science.gov (United States)

    Li, Ye; Zhang, Yixin; Zhu, Yun; Chen, Minyu

    2016-07-01

    Based on the spatial power spectrum of the refractive index of anisotropic turbulence, the average polarizability of the Gaussian Schell-model quantized beams and lateral coherence length of the spherical wave propagating through the ocean water channel are derived. Numerical results show that, in strong temperature fluctuation, the depolarization effects of anisotropic turbulence are inferior to isotropic turbulence, as the other parameters of two links are the same. The depolarization effects of salinity fluctuation are less than the effects of the temperature fluctuation; the average polarizability of beams increases when increasing the inner scale of turbulence and the source's transverse size; and the larger rate of dissipation of kinetic energy per unit mass of fluid enhances the average polarizability of beams. The region of the receiving radius is smaller than the characteristic radius and the average polarizability of beams in isotropy turbulence is smaller than that of beams in anisotropy turbulence. However, the receiving radius region is larger than a characteristic radius and the average polarizability of beams in isotropy turbulence is larger than that of beams in anisotropy turbulence.

  7. Size effect of sandstone after high temperature under uniaxial compression

    Institute of Scientific and Technical Information of China (English)

    SU Hai-jian; JING Hong-wen; MAO Xian-biao; ZHAO Hong-hui; YIN Qian; WANG Chen

    2015-01-01

    Uniaxial compression tests on sandstone samples with five different sizes after high temperature processes were performed in order to investigate the size effect and its evolution. The test results show that the density, longitudinal wave velocity, peak strength, average modulus and secant modulus of sandstone decrease with the increase of temperature, however, peak strain increases gradually. With the increase of ratio of height to diameter, peak strength of sandstone decreases, which has an obvious size effect. A new theoretical model of size effect of sandstone material considering the influence of temperature is put forward, and with the increase of temperature, the size effect is more apparent. The threshold decreases gradually with the increase of temperature, and the deviations of the experimental values and the theoretical values are between 0.44% and 6.06%, which shows quite a credibility of the theoretical model.

  8. The dose delivery effect of the different Beam ON interval in FFF SBRT: TrueBEAM

    Science.gov (United States)

    Tawonwong, T.; Suriyapee, S.; Oonsiri, S.; Sanghangthum, T.; Oonsiri, P.

    2016-03-01

    The purpose of this study is to determine the dose delivery effect of the different Beam ON interval in Flattening Filter Free Stereotactic Body Radiation Therapy (FFF-SBRT). The three 10MV-FFF SBRT plans (2 half rotating Rapid Arc, 9 to10 Gray/Fraction) were selected and irradiated in three different intervals (100%, 50% and 25%) using the RPM gating system. The plan verification was performed by the ArcCHECK for gamma analysis and the ionization chamber for point dose measurement. The dose delivery time of each interval were observed. For gamma analysis (2%&2mm criteria), the average percent pass of all plans for 100%, 50% and 25% intervals were 86.1±3.3%, 86.0±3.0% and 86.1±3.3%, respectively. For point dose measurement, the average ratios of each interval to the treatment planning were 1.012±0.015, 1.011±0.014 and 1.011±0.013 for 100%, 50% and 25% interval, respectively. The average dose delivery time was increasing from 74.3±5.0 second for 100% interval to 154.3±12.6 and 347.9±20.3 second for 50% and 25% interval, respectively. The same quality of the dose delivery from different Beam ON intervals in FFF-SBRT by TrueBEAM was illustrated. While the 100% interval represents the breath-hold treatment technique, the differences for the free-breathing using RPM gating system can be treated confidently.

  9. Electron beam heating effects during environmental scanning electron microscopy imaging of water condensation on superhydrophobic surfaces

    Science.gov (United States)

    Rykaczewski, K.; Scott, J. H. J.; Fedorov, A. G.

    2011-02-01

    Superhydrophobic surfaces (SHSs) show promise as promoters of dropwise condensation. Droplets with diameters below ˜10 μm account for the majority of the heat transferred during dropwise condensation but their growth dynamics on SHS have not been systematically studied. Due to the complex topography of the surface environmental scanning electron microscopy is the preferred method for observing the growth dynamics of droplets in this size regime. By studying electron beam heating effects on condensed water droplets we establish a magnification limit below which the heating effects are negligible and use this insight to study the mechanism of individual drop growth.

  10. Development and Clinical Implementation of a Universal Bolus to Maintain Spot Size During Delivery of Base of Skull Pencil Beam Scanning Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Both, Stefan, E-mail: Stefan.Both@uphs.upenn.edu [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Shen, Jiajian [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Department of Radiation Oncology, Mayo Clinic, Phoenix, Arizona (United States); Kirk, Maura; Lin, Liyong; Tang, Shikui; Alonso-Basanta, Michelle; Lustig, Robert; Lin, Haibo; Deville, Curtiland; Hill-Kayser, Christine; Tochner, Zelig; McDonough, James [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States)

    2014-09-01

    Purpose: To report on a universal bolus (UB) designed to replace the range shifter (RS); the UB allows the treatment of shallow tumors while keeping the pencil beam scanning (PBS) spot size small. Methods and Materials: Ten patients with brain cancers treated from 2010 to 2011 were planned using the PBS technique with bolus and the RS. In-air spot sizes of the pencil beam were measured and compared for 4 conditions (open field, with RS, and with UB at 2- and 8-cm air gap) in isocentric geometry. The UB was applied in our clinic to treat brain tumors, and the plans with UB were compared with the plans with RS. Results: A UB of 5.5 cm water equivalent thickness was found to meet the needs of the majority of patients. By using the UB, the PBS spot sizes are similar with the open beam (P>.1). The heterogeneity index was found to be approximately 10% lower for the UB plans than for the RS plans. The coverage for plans with UB is more conformal than for plans with RS; the largest increase in sparing is usually for peripheral organs at risk. Conclusions: The integrity of the physical properties of the PBS beam can be maintained using a UB that allows for highly conformal PBS treatment design, even in a simple geometry of the fixed beam line when noncoplanar beams are used.

  11. Electron beam welding in the fabrication of thick-walled large-size pipes of C-Mn steels. Final report; Elektronenstrahlschweissen bei der Fertigung von dickwandigen Grossrohren aus C-Mn-Staehlen. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Woeste, K.

    2001-11-01

    This research project investigates electron beam welding as a method of fabrication of large-size pipes with longitudinal welds. The effects of the welding speed on the mechanical and technological properties of the weld are investigated. From the economic view, electron beam welding is much more favourable than submerged-arc welding. [German] Dieses Forschungsprojekt soll dazu beitragen, das Elektronenstrahlschweissen als Fertigungsverfahren fuer laengsnahtgeschweisste Grossrohre zu qualifizieren. Dabei wird der Einfluss der Schweissgeschwindigkeit auf die mechanisch-technologischen Eigenschaften der Schweissung untersucht. Im Wirtschaftlichkeitsvergleich schneidet Elektronenstrahlschweissverfahren gegenueber dem Unterpulverschweissverfahren eindeutig besser ab.

  12. Limiting of the spot size of intense relativistic electronic beams in a solenoidal field%螺线管场下强流相对论电子束焦斑尺寸的限制

    Institute of Scientific and Technical Information of China (English)

    石金水; 林郁正; 丁伯南

    2001-01-01

    分析了螺线管场下影响强流相对论电子束聚焦的主要因素,并给出了各影响因素所限制的最小焦斑。计算结果表明,当发射度和能散度的值分别控制在0.397mm*rad和1%以内, 单个螺线管磁轴的偏心不大于0.54mrad;初始注入束偏心不大于1mrad时,对于20MeV、3kA的电子束和15MeV、2.5kA的电子束,最终打靶束焦斑均可小于1.5mm。%High-resolution X-ray photographing needs to focus intense relativistic electron beams of several thousand amperes on the bremsstrahlung converter target, thereon forming a small and stable spot. In the ideal case, electron beams cn be focused to a point. However, due to the influence of such factrs as the space charge effect, the beam emittance, the spherical aberration of the lens, and the chromatic aberration, the minimization of the spot size of electron beams is limited. Furthermore, the corkscrew oscillation of the beam centroid not only leads to the increase of the spot size but also to the distortion of the spot shape.The effects of solenoidal field on the spot size of intense relativistic electronic beams are analyzed and the minimal spot sizes limited by various factors are given. The results of the numerical calculation show that if the emittance ≤0.397mm*rad and the energy sweep ≤1%,the ultimate minimal spot size for 20MeV, 3kA and 15MeV, 3kA intense beams is less than 1.5mm when the tilt of each solenoid ≤1mrad and the injection tilt of beams ≤1mrad.

  13. Light propagation in tissues: effect of finite size of tissue sample

    Science.gov (United States)

    Melnik, Ivan S.; Dets, Sergiy M.; Rusina, Tatyana V.

    1995-12-01

    Laser beam propagation inside tissues with different lateral dimensions has been considered. Scattering and anisotropic properties of tissue critically determine spatial fluence distribution and predict sizes of tissue specimens when deviations of this distribution can be neglected. Along the axis of incident beam the fluence rate weakly depends on sample size whereas its relative increase (more than 20%) towards the lateral boundaries. The finite sizes were considered to be substantial only for samples with sizes comparable with the diameter of the laser beam. Interstitial irradiance patterns simulated by Monte Carlo method were compared with direct measurements in human brain specimens.

  14. Compensation of beam-beam and space-charge effects: experience to-date and near-future opportunities

    CERN Document Server

    Shiltsev, V

    2014-01-01

    Beam-beam interactions and space-charge effects belong to the category of the most long-standing issues in beam physics, and even today, after several decades of very active exploration and development of counter-measures, they still pose the most profound limitations on performance of accelerator facilities. In this brief review we consider past experience in active compensation of these effects and possible new schemes for further exploration in near-future, in particular, within the framework of the electron-ion collider R&D.

  15. Effects of Structural Parameters on the Dynamics of a Beam Structure with a Beam-Type Vibration Absorber

    Directory of Open Access Journals (Sweden)

    Mothanna Y. Abd

    2012-01-01

    Full Text Available A beam-type absorber has been known as one of the dynamic vibration absorbers used to suppress excessive vibration of an engineering structure. This paper studies an absorbing beam which is attached through a visco-elastic layer on a primary beam structure. Solutions of the dynamic response are presented at the midspan of the primary and absorbing beams in simply supported edges subjected to a stationary harmonic load. The effect of structural parameters, namely, rigidity ratio, mass ratio, and damping of the layer and the structure as well as the layer stiffness on the response is investigated to reduce the vibration amplitude at the fundamental frequency of the original single primary beam. It is found that this can considerably reduce the amplitude at the corresponding troublesome frequency, but compromised situation should be noted by controlling the structural parameters. The model is also validated with measured data with reasonable agreement.

  16. Correction of the Long-Range Beam-Beam Effect in LHC using Electro-Magnetic Lenses

    CERN Document Server

    Koutchouk, Jean-Pierre

    2001-01-01

    The beams in LHC collide head-on in at most four experimental points. Due to the small bunch spacing, the beams experience more than one hundred 'near-misses' on either side of the collision points. The transverse beam separation at these places, limited by the quadrupole aperture, is in the range of 7 to 13 sigma. The non-linear part of these 'long-range' interactions appears to be the dominant mechanism for beam blow-up or beam loss in simulation. A simple non-linear model of the long-range interactions can be devised. It shows that the latter may be locally corrected with good accuracy using wires as correcting lenses. The non-linearity measured by the tune footprint is reduced by one order of magnitude. Pulsing the correcting lenses cancels the so-called PACMAN effect.

  17. Effects of Titanium Dioxide Nanoparticle Aggregate Size on Gene Expression

    Directory of Open Access Journals (Sweden)

    Junko Okuda-Shimazaki

    2010-06-01

    Full Text Available Titanium dioxide (titania nanoparticle aggregation is an important factor in understanding cytotoxicity. However, the effect of the aggregate size of nanoparticles on cells is unclear. We prepared two sizes of titania aggregate particles and investigated their biological activity by analyzing biomarker expression based on mRNA expression analysis. The aggregate particle sizes of small and large aggregated titania were 166 nm (PDI = 0.291 and 596 nm (PDI = 0.417, respectively. These two size groups were separated by centrifugation from the same initial nanoparticle sample. We analyzed the gene expression of biomarkers focused on stress, inflammation, and cytotoxicity. Large titania aggregates show a larger effect on cell viability and gene expression when compared with the small aggregates. This suggests that particle aggregate size is related to cellular effects.

  18. Effect sizes for research univariate and multivariate applications

    CERN Document Server

    Grissom, Robert J

    2005-01-01

    The goal of this book is to inform a broad readership about a variety of measures and estimators of effect sizes for research, their proper applications and interpretations, and their limitations. Its focus is on analyzing post-research results. The book provides an evenhanded account of controversial issues in the field, such as the role of significance testing. Consistent with the trend toward greater use of robust statistical methods, the book pays much attention to the statistical assumptions of the methods and to robust measures of effect size.Effect Sizes for Research

  19. Size effect in tension perpendicular to the grain

    DEFF Research Database (Denmark)

    Pedersen, Martin Bo Uhre; Clorius, Christian Odin; Damkilde, Lars;

    1999-01-01

    The strength in tension perpendicular to the grain is known to decrease with an increase in the stressed volume. Usually this size effect is explained on a stochastic basis, that is an explanation relying on an increased probability of encountering a strength reducing flaw when the volume of the ...... that the size effect can be explained on a deterministic basis. Arguments for such a simple deterministic explanation of size effect is found in finite element modelling using the orthotropic stiffness characteristics in the transverse plane of wood....

  20. QUANTUM SIZE EFFECTS IN THE ATTRACTIVE HUBBARD-MODEL

    NARCIS (Netherlands)

    BORMANN, D; SCHNEIDER, T; FRICK, M

    1992-01-01

    We investigate superconducting pair correlations in the attractive Hubbard model on a finite square lattice. Our aim is to understand the pronounced size dependence which they display in the weak and intermediate coupling regimes. These size effects originate from the electronic shell structure of f

  1. Effect of bubble size on nanofiber diameter in bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Ren Zhong-Fu

    2016-01-01

    Full Text Available Polymer bubbles are widely used for fabrication of nanofibers. Bubble size affects not only bubble's surface tension, but also fiber's morphology. A mathematical model is established to reveal the effect of bubble size on the spinning process, and the experiment verification shows the theoretical analysis is reliable.

  2. EFFECTS OF ULTRASOUND ON THE MORPHOLOGY, PARTICLE SIZE, CRYSTALLINITY, AND CRYSTALLITE SIZE OF CELLULOSE

    Directory of Open Access Journals (Sweden)

    SUMARI SUMARI

    2014-05-01

    Full Text Available The aim of this study is to optimize ultrasound treatment to produce fragment of cellulose that is low in particles size, crystallite size, and crystallinity. Slurry of 1 % (w/v the cellulose was sonicated at different time periods and temperatures. An ultrasonic reactor was operated at 300 Watts and 28 kHz to cut down the polymer into smaller particles. We proved that ultrasound damages and fragments the cellulose particles into shorter fibers. The fiber lengths were reduced from in the range of 80-120 µm to 30-50 µm due to an hour ultrasonication and became 20-30 µm after 5 hours. It was also found some signs of erosion on the surface and stringy. The acoustic cavitation also generated a decrease in particle size, crystallinity, and crystallite size of the cellulose along with increasing sonication time but it did not change d-spacing. However, the highest reduction of particle size, crystallite size, and crystallinity of the cellulose occurred within the first hour of ultrasonication, after which the efficiency was decreased. The particle diameter, crystallite size, and crystallinity were decreased from 19.88 µm to 15.96 µm, 5.81 Å to 2.98 Å, and 77.7% to 73.9% respectively due to an hour ultrasound treatment at 40 °C. The treatment that was conducted at 40 °C or 60 °C did not give a different effect significantly. Cellulose with a smaller particle and crystallite size as well as a more amorphous shape is preferred for further study.

  3. Effect of flexural crack on plain concrete beam failure mechanism A numerical simulation

    Directory of Open Access Journals (Sweden)

    Abdoullah Namdar

    2016-03-01

    Full Text Available The flexural failure of plain concrete beam occurs along with development of flexural crack on beam. In this paper by using ABAQUS, mechanism failure of plain concrete beam under three steps have been simulated. The cracking moment has been analytically calculated and applied on the both sides of the fixed beam, and flexural crack has been simulated on beam. Displacement, von Mises, load reaction, displacementcrack length, von Mises-crack length and von Mises-displacement of beams have been graphical depicted. Results indicated that, the flexural crack governs beam mechanism failure and its effects on beam resistance failure. It has been found that the flexural crack in initial stage it developed slowly and changes to be fast at the final stage of collapsing beam due to reduction of the flexural resistance of beam. Increasing mechanical properties of concrete, collapse displacement is reduced.

  4. Effect of beam quality on tilt measurement using cyclic interferometer

    Science.gov (United States)

    Pretheesh Kumar, V. C.; Ganesan, A. R.; Joenathan, C.; Somasundaram, U.

    2016-08-01

    Accurate measurement of angles is extremely important in various metrological applications. Interferometry has always been an excellent technique for accurate measurements. Several methods have been proposed for accurate tilt measurement using interferometric techniques. Almost all of them use the Michelson configuration which is extremely sensitive to environmental vibrations and turbulences. We know that a cyclic interferometer is extremely stable. Even though it is not sensitive to displacement changes, it is twice sensitive to tilt compared to that of a Michelson interferometer. We have enhanced the sensitivity to measure tilt using multiple reflections in a cyclic interferometer. Since the input beam is collimated, we have studied the effect of aberration of the input beam on the accuracy of tilt measurement. Experimental results on this study are presented in this paper.

  5. Infrared Polarization and Beaming Effect for BL Lac Objects

    Institute of Scientific and Technical Information of China (English)

    MEI Dong-Cheng; XIE Guang-Zhong

    2001-01-01

    With the idea of the beaming models, we derive a relation between the observed polarization and Dopplercorrected magnitude; that is, the observed polarization is in anti-correlation with the Doppler-corrected magnitude. Making use of the infrared data observed simultaneously by Impey et al. [Mon. Not. R. Astron. Soc.200 (1982) 19; 209 (1984) 245] and Holmes et al. [ibid. 210 (1984) 961] we found that: (1) there is a significant correlation between the observed maximum polarization and Doppler-corrected magnitude but the polarization is not in anti-correlation with the Doppler-corrected magnitude; (2) the maximum infrared polarization is strongly correlated with the maximum optical polarization. Our conclusion is that the infrared polarization depends only on the degree of ordering of the magnetic field in the synchrotron emission regions and not on the beaming effect.Both infrared and optical emissions originate from the synchrotron radiation.

  6. Effects of electron beam irradiation on cut flowers and mites

    Energy Technology Data Exchange (ETDEWEB)

    Dohino, Toshiyuki; Tanabe, Kazuo [Yokohama Plant Protection Station (Japan)

    1994-08-01

    Two spotted spider mite, Tetranychus urticae KOCH were irradiated with electron beams (2.5MeV) to develop an alternative quarantine treatment for imported cut flowers. The tolerance of eggs increased with age (1-5-day-old). Immature stages (larva-teleiochrysalis) irradiated at 0.4-0.8kGy increased tolerance with their development. Mated mature females irradiated at 0.4kGy or higher did not produce viable eggs, although temporary recovery was observed at 0.2kGy. Adult males were sterilized at 0.4kGy because non-irradiated virgin females mated with yielded female progeny malformed and sterilized. Various effects of electron beam irradiation were observed when nine species of cut flowers were irradiated in 5MeV Dynamitron accelerator. Chrysanthemum and rose were most sensitive among cut flowers. (author).

  7. Proton beam irradiation and hyperthermia. Effects on experimental choroidal melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, K.G.; Svitra, P.P.; Seddon, J.M.; Albert, D.M.; Gragoudas, E.S.; Koehler, A.M.; Coleman, D.J.; Torpey, J.; Lizzi, F.L.; Driller, J.

    1985-12-01

    Ultrasonically induced hyperthermia (4.75 MHz) and proton irradiation (160 meV) were evaluated alone and combined to treat experimental choroidal melanoma in 58 rabbit eyes. Threshold tumoricidal doses were established for each modality. Therapy was performed combining subthreshold doses of heat and radiation. Focused ultrasonic energy via an external beam was found to deliver well-localized heat to an intraocular tumor. Ectopic temperature elevations due to soft-tissue-bone interfaces were alleviated by modifying beam alignment. The results indicate that hyperthermia (43 degrees C for one hour) potentiated the tumoricidal effects of radiation, while sparing normal ocular structures. Therefore, we believe that experimental hyperthermia is suitable as an adjuvant treatment modality. This shows that ultrasound hyperthermia has the potential to increase the efficacy of proton irradiation by lowering radiation doses and thus decreasing posttreatment ocular morbidity in human intraocular malignancies.

  8. Montelukast in Adenoid Hypertrophy: Its Effect on Size and Symptoms

    Directory of Open Access Journals (Sweden)

    Farshid Shokouhi

    2015-11-01

    Conclusion:  Montelukast chewable tablets achieved a significant reduction in adenoid size and improved the related clinical symptoms of AH and can therefore be considered an effective alternative to surgical treatment in children with adenoid hypertrophy.

  9. Stiction of a Nano-Beam with Surface Effect

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Lin; XIA Re; ZHOU Yue-Ting

    2011-01-01

    Nanowire stiction is a cruciai bottleneck for the development of M/NEMS devices. We present a model of a nano-beam stuck to te substrate in consideration of both surface elasticity and residual surface stress. The critical detachment length can be derived from the transversality condition using the variational method. The effects of the surface parameters on the adhesion of the nano-beam are discussed in detail. These analyses provide some suggestions for engineers in the design and fabrication of more accurate M/NEMS instruments.%Nanowire stiction is a crucial bottleneck for the development of M/NEMS devices.We present a model of a nano-beam stuck to the substrate in consideration of both surface elasticity and residual surface stress.The critical detachment length can be derived from the transversality condition using the variational method.The effects of the surface parameters on the adhesion of the nano-beam are discussed in detail.These analyses provide some suggestions for engineers in the design and fabrication of more accurate M/NEMS instruments.In the bottom-up approach,nanowires and nanobelts are widely used as the building blocks of micro/nano devices,such as micro-sensors,resonators,probes,transistors and actuators in micro/nanoelectro-mechanical systems (M/NMES).[1-3] Unfortunately,the stiction failure caused by spontaneous adhesion between M/NEMS structures has become a major limitation to push better application of these novel devices and this problem has been highlighted as a hot topic in the past decades.[4,5] The main reason of stiction is that in the small spacings,slender structures with high compliance are easily brought into contact with a substrate with strong surface energy.

  10. Modelling beam transport and biological effectiveness to develop treatment planning for ion beam radiotherapy

    CERN Document Server

    Grzanka, Leszek

    2014-01-01

    Radiation therapy with carbon ions is a novel technique of cancer radiotherapy, applicable in particular to treating radioresistant tumours at difficult localisations. Therapy planning, where the medical physicist, following the medical prescription, finds the optimum distribution of cancer cells to be inactivated by their irradiation over the tumour volume, is a basic procedure of cancer radiotherapy. The main difficulty encountered in therapy planning for ion radiotherapy is to correctly account for the enhanced radiobiological effectiveness of ions in the Spread Out Bragg Peak (SOBP) region over the tumour volume. In this case, unlike in conventional radiotherapy with photon beams, achieving a uniform dose distribution over the tumour volume does not imply achieving uniform cancer cell inactivation. In this thesis, an algorithm of the basic element (kernel) of a treatment planning system (TPS) for carbon ion therapy is developed. The algorithm consists of a radiobiological part which suitably corrects for ...

  11. Cohesive stresses and size effect in quasi-brittle materials

    Indian Academy of Sciences (India)

    V E Saouma; D Natekar

    2002-08-01

    A novel approach to the derivation of Ba$\\breve{z}$ant’s size effect law is presented. Contrarily to the original Lagrangian derivation which hinged on energetic consideration, a Newtonian approach based on local stress intensity factors is presented. Through this approach, it is shown that Ba$\\breve{z}$ant’s size effect law is the first (and dominant) term in a series expansion for the nominal stress. Furthermore, analytical expressions for are derived for selected specimen geometries.

  12. Chemical effects of size quantization of CdS nanoparticles

    Institute of Scientific and Technical Information of China (English)

    陈德文; 王素华

    1996-01-01

    The behaviour of photoreaction occurring on the superfine duster interface of semiconductor CdS has been studied. The results indicated that the size quantization effect of semiconductor nanoparticles was obviously reflected not only in their physical properties, but also in the interfacial photocatalysis reactions initiated by superfine nanopartides. This means that the direction and mechanisms in photoreactions of the compounds adsorbed on the surface of nanopartides could vary with the alteration of particle size because the redox potential values of semiconductor particles could be changed with the variation of particle size. Doubtlessly, this effect could play an important role in controlling the interfacial reaction mechanisms and raising the selectivity to photoreaction paths.

  13. Theoretical modeling on the laser induced effect of liquid crystal optical phased beam steering

    Science.gov (United States)

    He, Xiaoxian; Wang, Xiangru; Wu, Liang; Tan, Qinggui; Li, Man; Shang, Jiyang; Wu, Shuanghong; Huang, Ziqiang

    2017-01-01

    Non-mechanical laser beam steering has been reported previously in liquid crystal array devices. To be one of the most promising candidates to be practical non-mechanical laser deflector, its laser induced effect still has few theoretical model. In this paper, we propose a theoretical model to analyze this laser induced effect of LC-OPA to evaluate the deterioration on phased beam steering. The model has three parts: laser induced thermal distribution; temperature dependence of material parameters and beam steering deterioration. After these three steps, the far field of laser beam is obtained to demonstrate the steering performance with the respect to the incident laser beam power and beam waist.

  14. Effects of shutter transients in molecular beam epitaxy.

    Science.gov (United States)

    Gozu, Shin-Ichiro; Mozume, Teruo; Kuwatsuka, Haruhiko; Ishikawa, Hiroshi

    2012-11-12

    : We have studied the effects of shutter transients (STs) in molecular beam epitaxy (MBE). Two series of samples were grown by MBE and evaluated by X-ray diffraction (XRD) and X-ray reflectivity (XRR) measurements. The effects of STs were evaluated by growth rate (GR) analysis using a combination of growth time (GT) and thickness evaluated by XRD and XRR measurements. We revealed two opposite effects of STs: (1) overshoot of GR and (2) increase in GR with GT and subsequent saturation. Each effect was consistent with the previous studies; however, the previous studies showed no relationships between these two effects. By considering closing time of the shutter, the two opposite effects were well understood.

  15. SU-D-213-02: Characterization of the Effect of a New Commercial Transmission Detector On Radiotherapy Beams

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, J; Morin, O [University of California San Francisco, San Francisco, CA (United States)

    2015-06-15

    Purpose: To evaluate the influence of a new commercial transmission detector on radiotherapy beams of various energies. Methods: A transmission detector designed for online treatment monitoring was characterized on a TrueBeam STx linear accelerator with 6MV, 6FFF, 10MV, and 10FFF beams. Measurements of beam characteristics including percentage depth doses (PDDs), inplane and crossplane off-axis profiles at different depths, transmission factors, and skin dose were acquired at field sizes of 3×3cm, 5×5m, 10×10cm, and 20×20cm at 100cm and 80cm source-to-surface distance (SSD). All measurements were taken with and without the transmission detector in the path of the beam. A CC04 chamber was used for all profile and transmission factor measurements. Skin dose was assessed at 100cm, 90cm, and 80cm SSD and using a variety of detectors (Roos and Markus parallel-plate chambers, and OSLD). Results: The PDDs showed small differences between the unperturbed and perturbed beams for both 100cm and 80cm SSD (≤4mm dmax difference and <1.2% average profile difference). The differences were larger for the flattened beams and at larger field sizes. The off-axis profiles showed similar trends. The penumbras looked similar with and without the transmission detector. Comparisons in the central 80% of the profile showed a maximum average (maximum) profile difference between all field sizes of 0.756% (1.535%) and 0.739% (3.682%) for 100cm and 80cm SSD, respectively. The average measured skin dose at 100cm (80cm) SSD for 10×10cm field size was <4% (<35%) dose increase for all energies. For 20×20cm field size, this value increased to <10% (≤45%). Conclusion: The transmission detector has minimal effect on the clinically relevant radiotherapy beams for IMRT and VMAT (field sizes 10×10cm and less). For larger field sizes, some perturbations are observable which would need to be assessed for clinical impact. The authors of this publication has research support from IBA Dosimetry.

  16. Optimal beam focusing through turbulence.

    Science.gov (United States)

    Charnotskii, Mikhail

    2015-11-01

    Beam spread and beam wandering are the most perceptible effects of atmospheric turbulence on propagating laser beams. The width of the mean irradiance profile is typically used to characterize the beam spread. This so-called long-term (LT) statistic allows for a relatively simple theoretical description. However, the LT beam size is not a very practical measure of the beam spread because its measurements are sensitive to the movements of the source and detector, and to the large-scale variations of the refractive index that are not associated with turbulence. The short-term (ST) beam spread is measured relative to the instantaneous position of the beam center and is free of these drawbacks, but has not been studied as thoroughly as the LT spread. We present a theoretical model for the ST beam irradiance that is based on the parabolic equation for the beam wave propagation in random media, and the Markov approximation for calculation of the statistics of the optical field, and discuss an approximation that allows introduction of the isoplanatic ST point spread function (PSF). Unlike the LT PSF, the ST PSF depends on the overall beam geometry. This allows optimization of the initial beam field in terms of minimizing the ST beam size at the observation plane. Calculations supporting this conjecture are presented for the simple case of the coherent Gaussian beam, and Kolmogorov turbulence.

  17. Self-effect in expanding electron beam plasma

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M

    1999-05-07

    An analytical model of plasma flow from a metal plate hit by an intense, pulsed, electron beam aims to bridge the gap between radiation-hydrodynamics simulations and experiments, and to quantify the self-effect of the electron beam penetrating the flow. Does the flow disrupt the tight focus of the initial electron bunch, or later pulses in a train? This work aims to model the spatial distribution of plasma speed, density, degree of ionization, and magnetization to inquire. The initial solid density, several eV plasma expands to 1 cm and 10{sup {minus}4} relative density by 2 {micro}s, beyond which numerical simulations are imprecise. Yet, a Faraday cup detector at the ETA-II facility is at 25 cm from the target and observes the flow after 50 {micro}s. The model helps bridge this gap. The expansion of the target plasma into vacuum is so rapid that the ionized portion of the flow departs from local thermodynamic equilibrium. When the temperature (in eV) in a parcel of fluid drops below V{sub i} x [(2{gamma} - 2)/(5{gamma} + 17)], where V{sub i} is the ionization potential of the target metal (7.8 eV for tantalum), and {gamma} is the ratio of specific heats (5/3 for atoms), then the fractional ionization and electron temperature in that parcel remain fixed during subsequent expansion. The freezing temperature as defined here is V{sub i}/19. The balance between the self-pinching force and the space charge repulsion of an electron beam changes on penetrating a flow: (i) the target plasma cancels the space-charge field, (ii) internal eddy currents arise to counter the magnetization of relativistic electrons, and (iii) electron beam heating alters the flow magnetization by changing the plasma density gradient and the magnitude of the conductivity.

  18. Reduction of metal artifacts: beam hardening and photon starvation effects

    Science.gov (United States)

    Yadava, Girijesh K.; Pal, Debashish; Hsieh, Jiang

    2014-03-01

    The presence of metal-artifacts in CT imaging can obscure relevant anatomy and interfere with disease diagnosis. The cause and occurrence of metal-artifacts are primarily due to beam hardening, scatter, partial volume and photon starvation; however, the contribution to the artifacts from each of them depends on the type of hardware. A comparison of CT images obtained with different metallic hardware in various applications, along with acquisition and reconstruction parameters, helps understand methods for reducing or overcoming such artifacts. In this work, a metal beam hardening correction (BHC) and a projection-completion based metal artifact reduction (MAR) algorithms were developed, and applied on phantom and clinical CT scans with various metallic implants. Stainless-steel and Titanium were used to model and correct for metal beam hardening effect. In the MAR algorithm, the corrupted projection samples are replaced by the combination of original projections and in-painted data obtained by forward projecting a prior image. The data included spine fixation screws, hip-implants, dental-filling, and body extremity fixations, covering range of clinically used metal implants. Comparison of BHC and MAR on different metallic implants was used to characterize dominant source of the artifacts, and conceivable methods to overcome those. Results of the study indicate that beam hardening could be a dominant source of artifact in many spine and extremity fixations, whereas dental and hip implants could be dominant source of photon starvation. The BHC algorithm could significantly improve image quality in CT scans with metallic screws, whereas MAR algorithm could alleviate artifacts in hip-implants and dentalfillings.

  19. Numerical analysis of the effects of non-conventional laser beam geometries during laser melting of metallic materials

    Science.gov (United States)

    Safdar, Shakeel; Li, Lin; Sheikh, M. A.

    2007-01-01

    Laser melting is an important industrial activity encountered in a variety of laser manufacturing processes, e.g. selective laser melting, welding, brazing, soldering, glazing, surface alloying, cladding etc. The majority of these processes are carried out by using either circular or rectangular beams. At present, the melt pool characteristics such as melt pool geometry, thermal gradients and cooling rate are controlled by the variation of laser power, spot size or scanning speed. However, the variations in these parameters are often limited by other processing conditions. Although different laser beam modes and intensity distributions have been studied to improve the process, no other laser beam geometries have been investigated. The effect of laser beam geometry on the laser melting process has received very little attention. This paper presents an investigation of the effects of different beam geometries including circular, rectangular and diamond shapes on laser melting of metallic materials. The finite volume method has been used to simulate the transient effects of a moving beam for laser melting of mild steel (EN-43A) taking into account Marangoni and buoyancy convection. The temperature distribution, melt pool geometry, fluid flow velocities and heating/cooling rates have been calculated. Some of the results have been compared with the experimental data.

  20. Interviewer Effects on a Network-Size Filter Question

    Directory of Open Access Journals (Sweden)

    Josten Michael

    2016-06-01

    Full Text Available There is evidence that survey interviewers may be tempted to manipulate answers to filter questions in a way that minimizes the number of follow-up questions. This becomes relevant when ego-centered network data are collected. The reported network size has a huge impact on interview duration if multiple questions on each alter are triggered. We analyze interviewer effects on a network-size question in the mixed-mode survey “Panel Study ‘Labour Market and Social Security’” (PASS, where interviewers could skip up to 15 follow-up questions by generating small networks. Applying multilevel models, we find almost no interviewer effects in CATI mode, where interviewers are paid by the hour and frequently supervised. In CAPI, however, where interviewers are paid by case and no close supervision is possible, we find strong interviewer effects on network size. As the area-specific network size is known from telephone mode, where allocation to interviewers is random, interviewer and area effects can be separated. Furthermore, a difference-in-difference analysis reveals the negative effect of introducing the follow-up questions in Wave 3 on CAPI network size. Attempting to explain interviewer effects we neither find significant main effects of experience within a wave, nor significantly different slopes between interviewers.

  1. Enhanced oxidation resistance of active nanostructures via dynamic size effect

    Science.gov (United States)

    Liu, Yun; Yang, Fan; Zhang, Yi; Xiao, Jianping; Yu, Liang; Liu, Qingfei; Ning, Yanxiao; Zhou, Zhiwen; Chen, Hao; Huang, Wugen; Liu, Ping; Bao, Xinhe

    2017-02-01

    A major challenge limiting the practical applications of nanomaterials is that the activities of nanostructures (NSs) increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Here, using FeO NSs as an example, we show to the contrary, that reducing the size of active NSs can drastically increase their oxidation resistance. A maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. Rather than being determined by the structure or electronic properties of active sites, the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. We find this dynamic size effect to govern the chemical properties of active NSs.

  2. Monitoring and Compensation of Large-Size Flat-Top Laser Beam%大尺寸平顶激光光束的监测补偿

    Institute of Scientific and Technical Information of China (English)

    赵天卓; 樊仲维; 余锦; 麻云凤; 刘洋; 张雪; 闫莹

    2011-01-01

    介绍了为一个平顶激光光束放大器所搭建的监测和补偿系统.该放大器采用多级放大结构,能够输出单脉冲能量5 J,光斑尺寸50 min×50 mm的平顶激光光束.放大器内部的液晶光阀可以对输出光斑的能量分布进行有效的调制.监控系统与放大器中的空间滤波器相结合,通过傅里叶像传递的原理,将液晶光阀上的能量分布成像到监测CCD上.补偿系统通过将放大器输出光斑反馈到液晶光阀上,有效的提高了输出激光光束的质量.实验结果表明,整形后的光斑内部能量分布更加均匀,放大器输出的平顶激光光束近场调制度为1.64,软化因子为0.053.所设计的监测和补偿系统较好的实现了对光束质量的控制和改善.%A monitoring and compensation system which is built for an amplifier that can generate flat-top laser beam is described. The amplifier uses a multi-level amplification structure. It can output 5 J energy of a single pulse, and the spot size of the flat-top laser beam is 50 mm × 50 mm. The liquid-crystal valve in the amplifier can modulate energy distribution of the output spot effectively. The monitoring system is combined with the spatial filter in the amplifier, and by the theory of Fourier-image transfer, it can image energy distribution of the liquid-crystal valve on the monitoring CCD. The compensation system effectively improves the quality of the output laser beam by feeding back the output spot of the amplifier on the liquid-crystal valve. Experimental result shows that energy distribution of the shaped beam is more uniform, and the near-field modulation of the flat-top laser beam generated by the amplifier is 1.64, the softening factor is 0. 053. The beam-quality control and improvement are well realized by the monitoring and compensation structure.

  3. Potential errors in relative dose measurements in kilovoltage photon beams due to polarity effects in plane-parallel ionisation chambers

    Science.gov (United States)

    Dowdell, S.; Tyler, M.; McNamara, J.; Sloan, K.; Ceylan, A.; Rinks, A.

    2016-12-01

    Plane-parallel ionisation chambers are regularly used to conduct relative dosimetry measurements for therapeutic kilovoltage beams during commissioning and routine quality assurance. This paper presents the first quantification of the polarity effect in kilovoltage photon beams for two types of commercially available plane-parallel ionisation chambers used for such measurements. Measurements were performed at various depths along the central axis in a solid water phantom and for different field sizes at 2 cm depth to determine the polarity effect for PTW Advanced Markus and Roos ionisation chambers (PTW-Freiburg, Germany). Data was acquired for kilovoltage beams between 100 kVp (half-value layer (HVL)  =  2.88 mm Al) and 250 kVp (HVL  =  2.12 mm Cu) and field sizes of 3-15 cm diameter for 30 cm focus-source distance (FSD) and 4  ×  4 cm2-20  ×  20 cm2 for 50 cm FSD. Substantial polarity effects, up to 9.6%, were observed for the Advanced Markus chamber compared to a maximum 0.5% for the Roos chamber. The magnitude of the polarity effect was observed to increase with field size and beam energy but was consistent with depth. The polarity effect is directly influenced by chamber design, with potentially large polarity effects for some plane-parallel ionisation chambers. Depending on the specific chamber used, polarity corrections may be required for output factor measurements of kilovoltage photon beams. Failure to account for polarity effects could lead to an incorrect dose being delivered to the patient.

  4. Potential errors in relative dose measurements in kilovoltage photon beams due to polarity effects in plane-parallel ionisation chambers.

    Science.gov (United States)

    Dowdell, S; Tyler, M; McNamara, J; Sloan, K; Ceylan, A; Rinks, A

    2016-11-15

    Plane-parallel ionisation chambers are regularly used to conduct relative dosimetry measurements for therapeutic kilovoltage beams during commissioning and routine quality assurance. This paper presents the first quantification of the polarity effect in kilovoltage photon beams for two types of commercially available plane-parallel ionisation chambers used for such measurements. Measurements were performed at various depths along the central axis in a solid water phantom and for different field sizes at 2 cm depth to determine the polarity effect for PTW Advanced Markus and Roos ionisation chambers (PTW-Freiburg, Germany). Data was acquired for kilovoltage beams between 100 kVp (half-value layer (HVL)  =  2.88 mm Al) and 250 kVp (HVL  =  2.12 mm Cu) and field sizes of 3-15 cm diameter for 30 cm focus-source distance (FSD) and 4  ×  4 cm(2)-20  ×  20 cm(2) for 50 cm FSD. Substantial polarity effects, up to 9.6%, were observed for the Advanced Markus chamber compared to a maximum 0.5% for the Roos chamber. The magnitude of the polarity effect was observed to increase with field size and beam energy but was consistent with depth. The polarity effect is directly influenced by chamber design, with potentially large polarity effects for some plane-parallel ionisation chambers. Depending on the specific chamber used, polarity corrections may be required for output factor measurements of kilovoltage photon beams. Failure to account for polarity effects could lead to an incorrect dose being delivered to the patient.

  5. Confidence Intervals for Standardized Effect Sizes: Theory, Application, and Implementation

    Directory of Open Access Journals (Sweden)

    Ken Kelley

    2007-02-01

    Full Text Available The behavioral, educational, and social sciences are undergoing a paradigmatic shift in methodology, from disciplines that focus on the dichotomous outcome of null hypothesis significance tests to disciplines that report and interpret effect sizes and their corresponding confidence intervals. Due to the arbitrariness of many measurement instruments used in the behavioral, educational, and social sciences, some of the most widely reported effect sizes are standardized. Although forming confidence intervals for standardized effect sizes can be very beneficial, such confidence interval procedures are generally difficult to implement because they depend on noncentral t, F, and x2 distributions. At present, no main-stream statistical package provides exact confidence intervals for standardized effects without the use of specialized programming scripts. Methods for the Behavioral, Educational, and Social Sciences (MBESS is an R package that has routines for calculating confidence intervals for noncentral t, F, and x2 distributions, which are then used in the calculation of exact confidence intervals for standardized effect sizes by using the confidence interval transformation and inversion principles. The present article discusses the way in which confidence intervals are formed for standardized effect sizes and illustrates how such confidence intervals can be easily formed using MBESS in R.

  6. Effect of a spectrometer magnet on the beam-beam interaction

    Energy Technology Data Exchange (ETDEWEB)

    Cornacchia, M; Parzen, G

    1981-01-01

    The presence of experimental apparatus in the interaction regions of an intersecting beam accelerator changes the configuration of the crossing beams. This changes the space-charge forces with respect to the standard, magnet-free crossing. The question is: what is the maximum allowable perturbation caused by the spectrometer magnet that can be tolerated from the point of view of the beam dynamics. This paper is limited to the perturbations that the curved trajectories cause the beam-beam space charge nonlinearities. The question has arisen of how one defines the strength of the perturbation. The only solution is to compute the strength of the most important nonlinear resources. In what follows, the computational method used in calculating these resonances is described, and compared with those induced by random orbit errors.

  7. An efficient method to improve the proximity effect for electron beam optical disc mastering

    Science.gov (United States)

    Pan, C. T.; Chen, M. F.

    2005-04-01

    For the next-generation optical disc, electron beam mastering has been considered as a high-potential technique to fabricate a high-density optical disc. However, for electron beam mastering, the proximity effect caused by electron backscattering is an important problem. In this study, the influence of the proximity effect on the linewidth (full width at half magnitude, FWHM) and thickness of the residual resist is discussed. Some methods are presented to solve the proximity effect for optical disc mastering, i.e., by raising the electron beam voltage and depositing thin film material with low atomic number on a silicon substrate. In the study, thin film materials such as Al, Ni, SiO2, and Si3N4 are deposited on a silicon wafer to explore the proximity effect. The preliminary experimental results show that raising the electron beam voltage and depositing SiO2 or Si3N4 thin film on a silicon substrate can efficiently solve this problem. Later, the resist with a nano-pattern is transferred into a metal Ni-Co (nickel-cobalt) mould by electroplating. The technique of the Ni-Co electroplating process with hardness at least Vicker hardness (Hv) 650 and residual stress below 1.5 kg mm-2 is developed. Then, with the Ni-Co mould, a modified LIGA process is applied to produce a high-density optical disc. The Ni-Co mould serves as the master for the hot embossing process to replicate the nano-pattern onto the PMMA sheet. Since the feature size is down to the nanometre range, the study presents an innovative demoulding mechanism to demould the master from the PMMA sheet without damaging the nanometre patterns.

  8. Origin of size effect on efficiency of organic photovoltaics

    DEFF Research Database (Denmark)

    Manor, Assaf; Katz, Eugene A.; Tromholt, Thomas;

    2011-01-01

    on the voltage dependence of photocurrent and dark current is the key to understanding size limitation of the organic photovoltaics (OPV) efficiency. Practical methods to overcome this limitation as well as the possibility of producing concentrator OPV cells operating under sunlight concentrations higher than 10......It is widely accepted that efficiency of organic solar cells could be limited by their size. However, the published data on this effect are very limited and none of them includes analysis of light intensity dependence of the key cell parameters. We report such analysis for bulk heterojunction solar...... cells of various sizes and suggest that the origin of both the size and the light intensity effects should include underlying physical mechanisms other than conventional series resistance dissipation. In particular, we conclude that the distributed nature of the ITO resistance and its influence...

  9. Size and shape effects on Curie temperature of ferromagnetic nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A simplified model was developed to describe the Curie temperature suppression of ferromagnetic nanoparticles. Based on a size and shape dependent model of cohesive energy, the critical temperature variations of ferromagnetic nanoparticles were deduced. It is predicted that the Curie temperature of nanoparticles depends on both size and shape conditions, among which the temperature suppression is strongly influenced by the particle size and the shape effect is comparably minor. The calculation values for freestanding nanoparticles are in good agreement with other theoretical model and the experimental results. The model is also potential for predictions for the nanoparticles embedded in different substrates.

  10. Electron beam irradiation effects on poly(ethylene terephthalate)

    Energy Technology Data Exchange (ETDEWEB)

    Burillo, G. [Departamento de Quimica de Radiaciones y Radioquimica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico, DF 04510 (Mexico)], E-mail: burillo@nucleares.unam.mx; Tenorio, L.; Bucio, E. [Departamento de Quimica de Radiaciones y Radioquimica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico, DF 04510 (Mexico); Adem, E. [Departamento de Fisica Experimental, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico, DF 04510 (Mexico); Lopez, G.P. [Department of Chemical and Nuclear Engineering, Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM 87131 (United States)

    2007-11-15

    Changes in poly(ethylene terephthalate) subjected to electron beam irradiation at doses up to 15 MGy and dose rate of 1.65 MGy/h, were investigated by differential scanning calorimetry, molecular weight measurement, X-ray photoelectron spectroscopy, and scanning electron microscopy. Irradiated samples showed a decrease of molecular weight with a minimum at 5 MGy, which is attributed to chain scission of the macromolecules and then an increase at further doses due to branching and some degradation effect. Irradiation in air is not an important factor because the high dose rate of irradiation inhibits oxygen diffusion in the samples.

  11. Study of Effect of Ion Source Energy Spread on RFQ Beam Dynamics at REX-ISOLDE

    CERN Document Server

    Fraser, M A

    2013-01-01

    With an upgrade to the Electron Beam Ion Source (EBIS) at REX under consideration a study was launched in order to understand the effect of an increased energy spread from the ion source on the beam dynamics of the RFQ. Due to the increased electron beam potential needed to achieve the upgrade’s charge breeding specification it is expected that the energy spread of the beam will increase from today’s estimated value of approximately +-0.1%. It is shown through beam dynamics simulations that the energy spread can be increased to +-1% without significant degradation of the beam quality output by the RFQ.

  12. Fundamental edge broadening effects during focused electron beam induced nanosynthesis

    Directory of Open Access Journals (Sweden)

    Roland Schmied

    2015-02-01

    Full Text Available The present study explores lateral broadening effects of 3D structures fabricated through focused electron beam induced deposition using MeCpPt(IVMe3 precursor. In particular, the scaling behavior of proximity effects as a function of the primary electron energy and the deposit height is investigated through experiments and validated through simulations. Correlated Kelvin force microscopy and conductive atomic force microscopy measurements identified conductive and non-conductive proximity regions. It was determined that the highest primary electron energies enable the highest edge sharpness while lower energies contain a complex convolution of broadening effects. Moreover, it is demonstrated that intermediate energies lead to even more complex proximity effects that significantly reduce lateral edge sharpness and thus should be avoided if desiring high lateral resolution.

  13. Thermophoresis of microemulsion droplets: size dependence of the Soret effect.

    Science.gov (United States)

    Vigolo, Daniele; Brambilla, Giovanni; Piazza, Roberto

    2007-04-01

    Thermophoresis, akin to thermal diffusion in simple fluid mixtures, consists of particle drift induced by a temperature gradient. Notwithstanding its practical interest, the dependence of thermophoretic effects on particle size R is still theoretically and experimentally debated. By performing measurements of water-in-oil microemulsion droplets with tunable size, we show that the thermal diffusion coefficient, at least for a suspension of small particles in a nonpolar solvent, does not appreciably depend on R .

  14. Effect of Beam Oscillation on Microstructure and Mechanical Properties of AISI 316L Electron Beam Welds

    Science.gov (United States)

    Kar, Jyotirmaya; Roy, Sanat Kumar; Roy, Gour Gopal

    2017-04-01

    The properties of electron beam-welded AISI 316L stainless steel butt joints prepared with and without beam oscillation were evaluated by microstructural analysis, mechanical testing like microhardness measurements, tensile tests at room and elevated temperature 973 K (700 °C), three-point bend, and Charpy impact tests. All joints, irrespective of being prepared with or without beam oscillation, were found to be defect free. Welds produced by beam oscillation exhibited narrower fusion zone (FZ) with lathy ferrite morphology, while the weld without beam oscillation was characterized by wider FZ and skeletal ferrite morphology. During tensile tests at room and elevated temperature 973 K (700 °C), all samples fractured in the base metal (BM) and showed almost the same tensile properties as that of the BM. However, the notch tensile tests at room temperature demonstrated higher strength for joints prepared with the oscillating beam. Besides, face and root bend tests, as well as Charpy impact tests, showed higher bending strength and notch toughness, respectively, for joints prepared with beam oscillation.

  15. Effect of Beam Oscillation on Microstructure and Mechanical Properties of AISI 316L Electron Beam Welds

    Science.gov (United States)

    Kar, Jyotirmaya; Roy, Sanat Kumar; Roy, Gour Gopal

    2017-02-01

    The properties of electron beam-welded AISI 316L stainless steel butt joints prepared with and without beam oscillation were evaluated by microstructural analysis, mechanical testing like microhardness measurements, tensile tests at room and elevated temperature 973 K (700 °C), three-point bend, and Charpy impact tests. All joints, irrespective of being prepared with or without beam oscillation, were found to be defect free. Welds produced by beam oscillation exhibited narrower fusion zone (FZ) with lathy ferrite morphology, while the weld without beam oscillation was characterized by wider FZ and skeletal ferrite morphology. During tensile tests at room and elevated temperature 973 K (700 °C), all samples fractured in the base metal (BM) and showed almost the same tensile properties as that of the BM. However, the notch tensile tests at room temperature demonstrated higher strength for joints prepared with the oscillating beam. Besides, face and root bend tests, as well as Charpy impact tests, showed higher bending strength and notch toughness, respectively, for joints prepared with beam oscillation.

  16. Experimental Effects on IR Reflectance Spectra: Particle Size and Morphology

    Energy Technology Data Exchange (ETDEWEB)

    Beiswenger, Toya N.; Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong; Blake, Thomas A.; Ertel, Alyssa B.; Tonkyn, Russell G.; Szecsody, James E.; Johnson, Timothy J.; Smith, Milton; Lanker, Cory

    2016-05-23

    For geologic and extraterrestrial samples it is known that both particle size and morphology can have strong effects on the species’ infrared reflectance spectra. Due to such effects, the reflectance spectra cannot be predicted from the absorption coefficients alone. This is because reflectance is both a surface as well as a bulk phenomenon, incorporating both dispersion as well as absorption effects. The same spectral features can even be observed as either a maximum or minimum. The complex effects depend on particle size and preparation, as well as the relative amplitudes of the optical constants n and k, i.e. the real and imaginary components of the complex refractive index. While somewhat oversimplified, upward-going amplitude in the reflectance spectrum usually result from surface scattering, i.e. rays that have been reflected from the surface without penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. While the effects are well known, we report seminal measurements of reflectance along with quantified particle size of the samples, the sizing obtained from optical microscopy measurements. The size measurements are correlated with the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to understand the effects on the spectral features as a function of the mean grain size of the sample. We report results for both sodium sulfate Na2SO4 as well as ammonium sulfate (NH4)2SO4; the optical constants have been measured for (NH4)2SO4. To go a step further from the field to the laboratory we explore our understanding of particle size effects on reflectance spectra in the field using standoff detection. This has helped identify weaknesses and strengths in detection using standoff distances of up 160 meters away from the Target. The studies have

  17. The Size Effects on Process Design of Micro Deep Drawing

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper suggested to reformulate cylindrical deep drawing parameters with dimensionless form. A diagram, in which a feasible zone is drawn to bound both the maximal allowable tension and compression stress during the deep drawing process, was established. Since it is presented in a dimensionless form, it may be applied for both conventional and micro deep drawing. Cylindrical cup deep drawing was taken as an example to show the dimensionless process design method. In addition, the size effects should be taken into account. Two kinds of size effects on micro deep drawing were investigated, which can be explained by surface layer model and strain gradient model. Numerical simulations were carried out to compare the strain distribution with or without consideration of size effect.

  18. Effect of 8 MeV electron beam irradiation on the structural and optical properties of CeO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Babitha, K.K.; Priyanka, K.P. [Nanoscience Research Centre (NSRC), Department of Physics, Nirmala College, Muvattupuzha, 686 661, Kerala (India); Sreedevi, A. [Department of Applied Science and Humanities, Thejus Engineering College, Thrissur, 680584 Kerala (India); Ganesh, S. [Microtron Centre, Mangalore University, Mangalagangotri, 574 199 Karnataka (India); Varghese, Thomas, E-mail: nanoncm@gmail.com [Nanoscience Research Centre (NSRC), Department of Physics, Nirmala College, Muvattupuzha, 686 661, Kerala (India)

    2014-12-15

    The effect of 8 MeV electron beam irradiation on the structural and optical properties of cerium oxide nanoparticles was investigated. Ceria nanoparticles were synthesized by chemical precipitation method, and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible, photoluminescence and Raman spectroscopy. Ultraviolet–visible absorption spectra, photoluminescence and Raman spectra of beam irradiated samples were modified, and shifted to blue region, which were attributed to quantum size effect. Systematic observations found that nonstoichiometry, defects and size reduction caused by beam irradiation have great influence on optical band gap, blue shift, photoluminescence and Raman band modifications. Moreover, electron beam irradiation is a suitable technique to enhance the structural and optical properties of nanoceria by controlling the particle size, which may lead to potentially useful technological applications. - Highlights: • Investigated effect of beam irradiation on CeO{sub 2} nanoparticles • Beam irradiation caused size reduction and surface modification. • It increases microstrain, decreases d-spacing and broadens XRD peaks. • It also modifies optical band gap, absorption, PL and Raman bands.

  19. Inner scale effect on scintillation index of flat-topped beam in non-Kolmogorov weak turbulence.

    Science.gov (United States)

    Zeng, Zhihong; Luo, Xiujuan; Xia, Aili; Zhang, Yu; Cao, Bei

    2015-04-01

    A simpler generalized expression of irradiance fluctuation for flat-topped beams is presented based on the Born and Rytov perturbation methods. The theoretical expression of the on-axis scintillation index in non-Kolmogorov weak atmospheric optics links is developed using the generalized von Kármán spectrum model, and using the equivalent structure constant that is different for all power-law exponents. The effect of the inner scale on the on-axis scintillation index is examined comprehensively. It is observed that flat-topped beams happen to possess smaller scintillation indices at larger inner scale. The effects of the power law, flat-topped order, source size of the fundamental Gaussian beam, propagation distance, and wavelength are also analyzed.

  20. Thermomechanical assessment of the effects of a jaw-beam angle during beam impact on Large Hadron Collider collimators

    Science.gov (United States)

    Cauchi, Marija; Assmann, R. W.; Bertarelli, A.; Carra, F.; Lari, L.; Rossi, A.; Mollicone, P.; Sammut, N.

    2015-02-01

    The correct functioning of a collimation system is crucial to safely and successfully operate high-energy particle accelerators, such as the Large Hadron Collider (LHC). However, the requirements to handle high-intensity beams can be demanding, and accident scenarios must be well studied in order to assess if the collimator design is robust against possible error scenarios. One of the catastrophic, though not very probable, accident scenarios identified within the LHC is an asynchronous beam dump. In this case, one (or more) of the 15 precharged kicker circuits fires out of time with the abort gap, spraying beam pulses onto LHC machine elements before the machine protection system can fire the remaining kicker circuits and bring the beam to the dump. If a proton bunch directly hits a collimator during such an event, severe beam-induced damage such as magnet quenches and other equipment damage might result, with consequent downtime for the machine. This study investigates a number of newly defined jaw error cases, which include angular misalignment errors of the collimator jaw. A numerical finite element method approach is presented in order to precisely evaluate the thermomechanical response of tertiary collimators to beam impact. We identify the most critical and interesting cases, and show that a tilt of the jaw can actually mitigate the effect of an asynchronous dump on the collimators. Relevant collimator damage limits are taken into account, with the aim to identify optimal operational conditions for the LHC.

  1. Effects of cell size on compressive properties of aluminum foam

    Institute of Scientific and Technical Information of China (English)

    CAO Xiao-qing; WANG Zhi-hua; MA Hong-wei; ZHAO Long-mao; YANG Gui-tong

    2006-01-01

    The effects of cell size on the quasi-static and dynamic compressive properties of open cell aluminum foams produced by infiltrating process were studied experimentally. The quasi-static and dynamic compressive tests were carried out on MTS 810 system and SHPB(split Hopkinson pressure bar) respectively. It is found that the elastic moduli and compressive strengths of the studied aluminum foam are not only dependent on the relative density but also dependent on the cell size of the foam under both quasi-static loading and dynamic loading. The foams studied show a significant strain rate sensitivity, the flow strength can be improved as much as 112%, and the cell size also has a sound influence on the strain rate sensitivity of the foams. The foams of middle cell size exhibit the highest elastic modulus, the highest flow strength and the most significant strain rate sensitivity.

  2. Beam manipulation techniques, nonlinear beam dynamics, and space charge effect in high energy high power accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S. Y.

    2014-04-07

    We had carried out a design of an ultimate storage ring with beam emittance less than 10 picometer for the feasibility of coherent light source at X-ray wavelength. The accelerator has an inherent small dynamic aperture. We study method to improve the dynamic aperture and collective instability for an ultimate storage ring. Beam measurement and accelerator modeling are an integral part of accelerator physics. We develop the independent component analysis (ICA) and the orbit response matrix method for improving accelerator reliability and performance. In collaboration with scientists in National Laboratories, we also carry out experimental and theoretical studies on beam dynamics. Our proposed research topics are relevant to nuclear and particle physics using high brightness particle and photon beams.

  3. Plasma effects on fast pair beams. III. Oblique electrostatic growth rates for perpendicular Maxwellian pair beams

    Energy Technology Data Exchange (ETDEWEB)

    Supsar, Markus; Schlickeiser, Reinhard, E-mail: markus.supsar@tp4.rub.de, E-mail: rsch@tp4.rub.de [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2014-03-10

    The distant universe is opaque to γ radiation from blazars due to gamma-gamma attenuation with extragalactic background light. This process produces electron-positron pair beams that interact with the intergalactic medium and are unstable to linear instabilities, particularly the electrostatic and Weibel instabilities. The electrostatic instability grows faster and so determines the dissipation of the free energy of the beam. Here, we generalize the calculation of the electrostatic growth rate to a beam plasma system with a Maxwellian perpendicular momentum spread and allow for oblique propagation directions. We show that the growth rate for the oblique electrostatic mode has a maximum value that is even higher than for a cold beam or for one with a constant perpendicular momentum spread.

  4. Preliminary study on the size effect of composite materials subjected to bending

    Directory of Open Access Journals (Sweden)

    Yusof M.Z.

    2014-03-01

    Full Text Available The purpose of this paper is to evaluate the effect of size or dimension changes of reinforced concrete structures, in terms of structural performance and serviceability limit states. A theoretical and design study was carried out to evaluate the structural performance and serviceability of reinforced concrete structures using the European Code of Practice (EC2 and British Code of Practice (BS8110. The analysis required nine different sizes of reinforced concrete beams, with dimension between 150mm × 250mm and 350mm × 250mm. The study showed that dimension changes significantly affected the load-carrying capacity and deflection of reinforced concrete members; regardless of their depth/width ratio. The analysis results also produced an equation (presented here to assess the performance of reinforced concrete members, based on the codes of practice.

  5. Finite-size effects, pseudocritical quantities and signatures of the chiral critical endpoint of QCD

    CERN Document Server

    Palhares, L F; Kodama, T

    2009-01-01

    We investigate finite-size effects on the phase diagram of strong interactions, and discuss their influence (and utility) on experimental signatures in high-energy heavy ion collisions. We calculate the modification of the pseudocritical transition line and isentropic trajectories, and discuss how this affects proposed signatures of the chiral critical endpoint. We argue that a finite-size scaling analysis may be crucial in the process of data analysis in the Beam Energy Scan program at RHIC and in future experiments at FAIR-GSI. We propose the use of extrapolations, full scaling plots and a chi-squared method as tools for searching the critical endpoint of QCD and determining its universality class.

  6. On the Relativistic Beaming and Orientation Effects in Core-Dominated Quasars

    Indian Academy of Sciences (India)

    A. A. Ubachukwu; A. E. Chukwude

    2002-09-01

    In this paper, we investigate the relativistic beaming effects in a well-defined sample of core-dominated quasars using the correlation between the relative prominence of the core with respect to the extended emission (defined as the ratio of core- to lobe- flux density measured in the rest frame of the source) and the projected linear size as an indicator of relativistic beaming and source orientation. Based on the orientation-dependent relativistic beaming and unification paradigm for high luminosity sources in which the Fanaroff-Riley class-II radio galaxies form the unbeamed parent population of both the lobe- and core-dominated quasars which are expected to lie at successively smaller angles to the line of sight, we find that the flows in the cores of these core-dominated quasars are highly relativistic, with optimum bulk Lorentz factor, opt ∼ 6—16, and also highly anisotropic, with an average viewing angle, ∼ 9°-16°. Furthermore, the largest boosting occurs within a critical cone angle of ≈ 4°-10°.

  7. Effect of Desiccation of Marine Environment on Beam Structure

    Institute of Scientific and Technical Information of China (English)

    CHEN Da; WANG Na; HOU Li-jun; LIAO Ying-di

    2013-01-01

    This paper presents the study on the effect of desiccation for different part of offshore structure corresponding to the water level.A coupled elastoplastic damage model is proposed to describe the mechanical behavior of cement-based materials under external loading and desiccation,in which both the plastic and damage behaviors under multi-axial stress are considered in composition with the desiccation effect.The comparison between numerical simulation and experimental data indicates that the proposed model can well predict the mechanical characteristics of cement-based materials with different saturations.In addition,a series of small beams subjected to desiccation are further analyzed to reveal the response of structure in the drying process.

  8. Effect of desiccation of marine environment on beam structure

    Science.gov (United States)

    Chen, Da; Wang, Na; Hou, Li-jun; Liao, Ying-di

    2013-03-01

    This paper presents the study on the effect of desiccation for different part of offshore structure corresponding to the water level. A coupled elastoplastic damage model is proposed to describe the mechanical behavior of cement-based materials under external loading and desiccation, in which both the plastic and damage behaviors under multi-axial stress are considered in composition with the desiccation effect. The comparison between numerical simulation and experimental data indicates that the proposed model can well predict the mechanical characteristics of cement-based materials with different saturations. In addition, a series of small beams subjected to desiccation are further analyzed to reveal the response of structure in the drying process.

  9. Neutron Beam Effects on Spin Exchange Polarized He-3

    CERN Document Server

    Sharma, M; Andersen, K H; Barron-Palos, L; Becker, M; Boag, S; Chen, W C; Chupp, T E; Danagoulian, A; Gentile, T R; Klein, A; Penttila, S; Petoukhov, A; Soldner, T; Tardiff, E R; Walker, T G; Wilburn, W S

    2008-01-01

    We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal-spin-exchange polarized He-3 cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable He-3 polarization and was attributed to a decrease of alkali-metal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at LANSCE and ILL. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as the square root of the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the recombination-limited ion concentration, but is much larger than expected from earlier work.

  10. Core size effects on safety performances of LMRs

    Energy Technology Data Exchange (ETDEWEB)

    Na, Byung Chan; Hahn, Do Hee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    An oxide fuel small size core (1200 MWt) was analyzed in comparison with a large size core (3600 MWt) in order to evaluate the size effects on transient safety performances of liquid-metal reactors (LMRs). In the first part of the study, main static safety parameters (i.e., Doppler coefficient, sodium void effect, etc.) of the two cores were characterized, and the second part of the study was focused on the dynamic behavior of the cores in two representative transient events: the unprotected loss-of-flow (ULOF) and the unprotected transient overpower (UTOP). Margins to fuel melting and sodium boiling have been evaluated for these representative transients. Results show that the small core has a generally better or equivalent level of safety performances during these events. 6 refs., 4 figs., 2 tabs. (Author)

  11. The damaging effects of nitrogen ion beam implantation on upland cotton ( Gossypium hirsutum L.) pollen grains

    Science.gov (United States)

    Yu, Yanjie; Wu, Lijun; Wu, Yuejin; Wang, Qingya; Tang, Canming

    2008-09-01

    With the aim to study the effects of an ion beam on plant cells, upland cotton (Gossypium hirsutum L.) cultivar "Sumian 22" pollen grains were irradiated in vacuum (7.8 × 10-3 Pa) by low-energy nitrogen ions with an energy of 20 keV at various fluences ranging from 0.26 × 1016 to 0.78 × 1016 N+/cm2. The irradiation effects on pollen grains were tested, considering the ultrastructural changes in the exine and interior walls of pollen grains, their germination rate, the growth speed of the pollen tubes in the style, fertilization and boll development after the pistils were pollinated by the pollen grains which had been implanted with nitrogen ions. Nitrogen ions entered the pollen grains by etching and penetrating the exine and interior walls and destroying cell structures. A greater percentage of the pollen grains were destroyed as the fluence of N+ ions increased. Obviously, the nitrogen ion beam penetrated the exine and interior walls of the pollen grains and produced holes of different sizes. As the ion fluence increased, the amount and the density of pollen grain inclusions decreased and the size of the lacuna and starch granules increased. Pollen grain germination rates decreased with increasing ion fluence. The number of pollen tubes in the style declined with increased ion implantation into pollen grains, but the growth speed of the tubes did not change. All of the pollen tubes reached the end of the style at 13 h after pollination. This result was consistent with that of the control. Also, the weight and the diameter of the ovary decreased and shortened with increased ion beam implantation fluence. No evident change in the fecundation time of the ovule was observed. These results indicate that nitrogen ions can enter pollen grains and cause a series of biological changes in pollen grains of upland cotton.

  12. 大尺寸 SIC 空间反射镜离子束加工热效应分析与抑制%Analysis and suppression of thermal effects of ion beam processing for large-size SIC space mirror

    Institute of Scientific and Technical Information of China (English)

    许艳军; 赵宇宸; 沙巍; 齐光

    2014-01-01

    to expansion, so it is necessary to suppress the thermal effect. A method of machining path planning and heat conduction enhancement was proposed to control the temperature of the mirror. For a primary mirror of 600 mm ×260 mm, research and finite element analysis were carried out for ion beam processing with different processing paths before and after heat conduction enhancement, which shows that the path selection and heat conduction enhancement have serious effects to the mirror. Before heat conduction enhancement, the maximum temperature of the mirror was 35.8 ℃ , PV = /5 when horizontal grid-shape machining path was used, and the maximum temperature of the mirror was 52 ℃, PV= /10 when vertical grid-shaped machining path was used. After heat conduction enhancement, the temperature of mirror about all machining path declined, the maximum temperature of the mirror was 28.2 ℃, PV= /20, when horizontal grid-shape machining path was used and increasing the heat conduction path, the maximum temperature of the mirror was 52 ℃ , PV = /10, when vertical grid-shaped machining path was used. By contrast, the method of horizontal grid-shape machining path was used and the heat conduction path was increased finally. The optimal path was tested experimentally. The results agree with the simulational result,and it shows that optimizing the processing path and enhancing heat conduction measures can suppress the thermal effect of ion beam processing. This research provides theoretical basis for the thermal effects suppression of ion beam processing.

  13. Numerical Simulation of the Self-Heating Effect Induced by Electron Beam Plasma in Atmosphere

    Institute of Scientific and Technical Information of China (English)

    邓永锋; 谭畅; 韩先伟; 谭永华

    2012-01-01

    For exploiting advantages of electron beam air plasma in some unusual applications, a Monte Carlo (MC) model coupled with heat transfer model is established to simulate the characteristics of electron beam air plasma by considering the self-heating effect. Based on the model, the electron beam induced temperature field and the related plasma properties are investigated. The results indicate that a nonuniform temperature field is formed in the electron beam plasma region and the average temperature is of the order of 600 K. Moreover, much larger volume pear-shaped electron beam plasma is produced in hot state rather than in cold state. The beam ranges can, with beam energies of 75 keV and 80 keV, exceed 1.0 m and 1.2 m in air at pressure of 100 torr, respectively. Finally, a well verified formula is obtained for calculating the range of high energy electron beam in atmosphere.

  14. Effects of injection beam parameters and foil scattering for CSNS/RCS

    Science.gov (United States)

    Huang, Ming-Yang; Wang, Sheng; Qiu, Jing; Wang, Na; Xu, Shou-Yan

    2013-06-01

    The China Spallation Neutron Source (CSNS) uses H- stripping and phase space painting method to fill a large ring acceptance with a small emittance linac beam. The dependence of the painting beam on the injection beam parameters was studied for the Rapid Cycling Synchrotron (RCS). The simulation study was done for injection with different momentum spreads, different rms emittances of the injection beam, and different matching conditions. Then, the beam loss, 99% and rms emittances were obtained, and the optimized injection beam parameters were given. The interaction between H- beam and stripping foil was studied, and the effect of foil scattering was simulated. The stripping efficiency was calculated and the suitable thickness of stripping foil was obtained. In addition, the energy deposition on the foil and the beam loss due to the foil scattering were also studied.

  15. Effects of the spatial frequency composition of the target pattern and the number of quantization levels in diffractive beam shaper design.

    Science.gov (United States)

    Hsu, Ku-Hui; Lin, Hoang Yan

    2012-06-01

    A mathematical model is derived, and numerical simulation is analyzed for laser beam shaping by using multilevel phase-only diffractive optical elements (DOEs). We used the simulated annealing algorithm to design the beam shapers. The result has an essential effect on the diffractive pattern quality caused by the spatial frequency composition of target patterns for the same incident gaussian beam size and target pattern area. The root mean square error between the diffractive and target patterns is smaller for the target patterns with lower spatial frequencies. Moreover, the effect of spatial frequency composition can be relaxed for the cases of larger incident gaussian beam size. In addition, finer quality control of a diffraction pattern can be obtained by increasing the number of quantization levels at the DOEs.

  16. Simulation of grain size effects in nanocrystalline shape memory alloys

    Science.gov (United States)

    Ahluwalia, Rajeev; Quek, Siu Sin; Wu, David T.

    2015-06-01

    Recently, it has been demonstrated that martensitic transformation in nanocrystalline shape memory alloys can be suppressed for small grain sizes. Motivated by these results, we study the grain size dependence of martensitic transformations and stress-strain response of nanocrystalline shape memory alloys within the framework of the Ginzburg-Landau (GL) theory. A GL model for a square to rectangle transformation in polycrystals is extended to account for grain boundary effects. We propose that an inhibition of the transformation in grain boundary regions can occur, if the grain boundary energy of the martensite is higher than that of the austenite phase. We show that this inhibition of transformation in grain boundary regions has a strong influence on domain patterns inside grains. Although the transformation is inhibited only at the grain boundaries, it leads to a suppression of the transformation even inside the grains as grain size is decreased. In fact, below a critical grain size, the transformation can be completely suppressed. We explain these results in terms of the extra strain gradient cost associated with grain boundaries, when the transformation is inhibited at grain boundaries. On the other hand, no significant size effects are observed when transformation is not inhibited at grain boundaries. We also study the grain size dependence of the stress strain curve. It is found that when the transformation is inhibited at grain boundaries, a significant reduction in the hysteresis associated with stress-strain curves during the loading-unloading cycles is observed. The hysteresis for this situation reduces even further as the grain size is reduced, which is consistent with recent experiments. The simulations also demonstrate that the mechanical behavior is influenced by inter-granular interactions and the local microstructural neighbourhood of a grain has a stronger influence than the orientation of the grain itself.

  17. In-vivo dosimetry for field sizes down to 6 × 6 mm2 in shaped beam radiosurgery with microMOSFET.

    Science.gov (United States)

    Sors, A; Cassol, E; Latorzeff, I; Duthil, P; Sabatier, J; Lotterie, J A; Redon, A; Berry, I; Franceries, X

    2014-09-01

    The aim of this study is to evaluate microMOSFET as in-vivo dosimeter in 6 MV shaped-beam radiosurgery for field sizes down to 6 × 6 mm2. A homemade build-up cap was developed and its use with microMOSFET was evaluated down to 6 × 6 mm2. The study with the homemade build-up cap was performed considering its influence on field size over-cover occurring at surface, achievement of the overall process of electronic equilibrium, dose deposition along beam axis and dose attenuation. An optimized calibration method has been validated using MOSFET in shaped-beam radiosurgery for field sizes from 98 × 98 down to 18 × 18 mm2. The method was detailed in a previous study and validated in irregular field shapes series measurements performed on a head phantom. The optimized calibration method was applied to microMOSFET equipped with homemade build-up cap down to 6 × 6 mm2. Using the same irregular field shapes, dose measurements were performed on head phantom. MicroMOSFET results were compared to previous MOSFET ones. Additional irregular field shapes down to 8.8 × 8.8 mm2 were studied with microMOSFET. Isocenter dose attenuation due to the homemade build-up cap over the microMOSFET was near 2% irrespective of field size. Our results suggested that microMOSFET equipped with homemade build-up cap is suitable for in-vivo dosimetry in shaped-beam radiosurgery for field sizes down to 6 × 6 mm2 and therefore that the required build-up cap dimensions to perform entrance in-vivo dosimetry in small-fields have to ensure only partial charge particle equilibrium.

  18. Effect size, confidence intervals and statistical power in psychological research.

    Directory of Open Access Journals (Sweden)

    Téllez A.

    2015-07-01

    Full Text Available Quantitative psychological research is focused on detecting the occurrence of certain population phenomena by analyzing data from a sample, and statistics is a particularly helpful mathematical tool that is used by researchers to evaluate hypotheses and make decisions to accept or reject such hypotheses. In this paper, the various statistical tools in psychological research are reviewed. The limitations of null hypothesis significance testing (NHST and the advantages of using effect size and its respective confidence intervals are explained, as the latter two measurements can provide important information about the results of a study. These measurements also can facilitate data interpretation and easily detect trivial effects, enabling researchers to make decisions in a more clinically relevant fashion. Moreover, it is recommended to establish an appropriate sample size by calculating the optimum statistical power at the moment that the research is designed. Psychological journal editors are encouraged to follow APA recommendations strictly and ask authors of original research studies to report the effect size, its confidence intervals, statistical power and, when required, any measure of clinical significance. Additionally, we must account for the teaching of statistics at the graduate level. At that level, students do not receive sufficient information concerning the importance of using different types of effect sizes and their confidence intervals according to the different types of research designs; instead, most of the information is focused on the various tools of NHST.

  19. Effect of Screen Size on Multimedia Vocabulary Learning

    Science.gov (United States)

    Kim, Daesang; Kim, Dong-Joong

    2012-01-01

    The objective of this study was to investigate the effects of three different screen sizes (small, medium and large) and two types of multimedia instruction (text only and text with pictorial annotation) on vocabulary learning. One hundred thirty-five Korean middle school students learning English as a foreign language were randomly distributed…

  20. An Introductory Summary of Various Effect Size Choices.

    Science.gov (United States)

    Cromwell, Susan

    This paper provides a tutorial summary of some of the many effect size choices so that members of the Southwest Educational Research Association would be better able to follow the recommendations of the American Psychological Association (APA) publication manual, the APA Task Force on Statistical Inference, and the publication requirements of some…

  1. Confidence Intervals for Effect Sizes: Applying Bootstrap Resampling

    Science.gov (United States)

    Banjanovic, Erin S.; Osborne, Jason W.

    2016-01-01

    Confidence intervals for effect sizes (CIES) provide readers with an estimate of the strength of a reported statistic as well as the relative precision of the point estimate. These statistics offer more information and context than null hypothesis statistic testing. Although confidence intervals have been recommended by scholars for many years,…

  2. Socialization Effects on the Size of Nigerian Children's Drawings.

    Science.gov (United States)

    Pfeffer, Karen; Olowu, A. A.

    1985-01-01

    Examines the effects of socialization on the size of Yoruba children's drawings of a man and a woman through use of the Draw a Person test. Findings support the prediction that male figures were drawn relatively larger than female figures only in the low income group, reflecting the gender inequality that appears typical of the Yoruba social…

  3. Investigation of the size effect for photonic crystals

    Science.gov (United States)

    Liu, M.; Xu, W.; Bai, J.; Chua, C. K.; Wei, J.; Li, Z.; Gao, Y.; Kim, D. H.; Zhou, K.

    2016-10-01

    Three types of photonic crystal (PC) thin films have been prepared for the investigation of their deformation behaviors by nanoindentation tests at the microscale and nanoscale. Each type of PC thin film was composed of poly(methyl methacrylate) (PMMA) nanoparticles with a uniform size. Another type of thin film was prepared by assembling nanoparticles with three different sizes. It was exciting to observe that the hardness and Young’s modulus were significantly improved (more than 15 times) in well-ordered PC thin films than disordered ones. Furthermore, size-dependent mechanical properties were observed for the three types of PCs. Such a size effect phenomenon can be attributed to the special polycrystalline material having a periodical face-centered cubic structure of PC thin films. Furthermore, the indentation size effect that shows that the indentation hardness decreases with an increasing indentation depth has also been observed for all four types of thin films. It is conjectured that the application of the PC structure to other functional materials may enhance their mechanical properties.

  4. Size-dependent antimicrobial effects of novel palladium nanoparticles.

    Directory of Open Access Journals (Sweden)

    Clara P Adams

    Full Text Available Investigating the interactions between nanoscale materials and microorganisms is crucial to provide a comprehensive, proactive understanding of nanomaterial toxicity and explore the potential for novel applications. It is well known that nanomaterial behavior is governed by the size and composition of the particles, though the effects of small differences in size toward biological cells have not been well investigated. Palladium nanoparticles (Pd NPs have gained significant interest as catalysts for important carbon-carbon and carbon-heteroatom reactions and are increasingly used in the chemical industry, however, few other applications of Pd NPs have been investigated. In the present study, we examined the antimicrobial capacity of Pd NPs, which provides both an indication of their usefulness as target antimicrobial compounds, as well as their potency as potential environmental pollutants. We synthesized Pd NPs of three different well-constrained sizes, 2.0 ± 0.1 nm, 2.5 ± 0.2 nm and 3.1 ± 0.2 nm. We examined the inhibitory effects of the Pd NPs and Pd(2+ ions toward gram negative Escherichia coli (E. coli and gram positive Staphylococcus aureus (S. aureus bacterial cultures throughout a 24 hour period. Inhibitory growth effects of six concentrations of Pd NPs and Pd(2+ ions (2.5 × 10(-4, 10(-5, 10(-6, 10(-7, 10(-8, and 10(-9 M were examined. Our results indicate that Pd NPs are generally much more inhibitory toward S. aureus than toward E. coli, though all sizes are toxic at ≥ 10(-5 M to both organisms. We observed a significant difference in size-dependence of antimicrobial activity, which differed based on the microorganism tested. Our work shows that Pd NPs are highly antimicrobial, and that fine-scale (<1 nm differences in size can alter antimicrobial activity.

  5. Surface and Size Effects in Spin-Crossover Nanocrystals

    Science.gov (United States)

    Gudyma, Iurii; Ivashko, Victor; Bobák, Andrej

    2017-02-01

    We perform Monte Carlo simulations to analyze the surface and size effects in spin-crossover nanocrystals using an Ising-like model including surface and core intermolecular interactions. The consequences of downsizing effect on the transition temperature and the width of hysteresis as finger of the system cooperativity are discussed. The critical temperature is calculated using the real-space renormalization method. The obtained results are in agreement with the experimental data.

  6. Infrared reflectance spectra: Effects of particle size, provenance and preparation

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yin-Fong; Myers, Tanya L.; Brauer, Carolyn S.; Blake, Thomas A.; Forland, Brenda M.; Szecsody, James E.; Johnson, Timothy J.

    2014-09-22

    We have recently developed methods for making more accurate infrared total and diffuse directional - hemispherical reflectance measurements using an integrating sphere. We have found that reflectance spectra of solids, especially powders, are influenced by a number of factors including the sample preparation method, the particle size and morphology, as well as the sample origin. On a quantitative basis we have investigated some of these parameters and the effects they have on reflectance spectra, particularly in the longwave infrared. In the IR the spectral features may be observed as either maxima or minima: In general, upward-going peaks in the reflectance spectrum result from strong surface scattering, i.e. rays that are reflected from the surface without bulk penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. The light signals reflected from solids usually encompass all such effects, but with strong dependencies on particle size and preparation. This paper measures the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to observe the effects on the spectral features: Bulk materials were ground with a mortar and pestle and sieved to separate the samples into various size fractions between 5 and 500 microns. The median particle size is demonstrated to have large effects on the reflectance spectra. For certain minerals we also observe significant spectral change depending on the geologic origin of the sample. All three such effects (particle size, preparation and provenance) result in substantial change in the reflectance spectra for solid materials; successful identification algorithms will require sufficient flexibility to account for these parameters.

  7. The Effect of Pretreatment by using Electron Beam Irradiation on Oil Palm Empty Fruit Bunch

    Directory of Open Access Journals (Sweden)

    A. Kristiani

    2016-04-01

    Full Text Available Oil palm empty fruit bunch (OPEFB is a potential type of lignocellulosic biomass for second-generation bioethanol production. The pretreatment process is an important process in the series of processes to produce bioethanol. This research aims to study the effects of pretreatment process by using electron beam irradiation to OPEFB’s characterization as raw materials for the hydrolysis reaction to produce monomer sugars which will be fermented into ethanol. The untreated and treated OPEFB are characterized in terms of their physical and chemical properties. Analysis results of the compositional analysis by using NREL/TP-510-42618 method show that after pretreatment by using electron beam irradiation, OPEFB's total lignin content is changed little while its cellulose and hemicellulose contents tend to decrease with increasing irradiation dose. X-ray diffraction (XRD analysis shows that there is a decrease of crystallinity compared to untreated OPEFB, except for 200-kGy irradiated OPEFB. The highest decrease of crystallinity was shown by 300-kGy irradiated OPEFB. Further, crystallite sizes of treated OPEFBs are not significantly different from the untreated, except for the 200-kGy irradiated OPEFB. Irradiation pretreatment also increases specific surface area, pore volume, and pore size. The IR spectra analysis show the absorption of cellulose, hemicellulose, and lignin.

  8. Size effects on insect hovering aerodynamics: an integrated computational study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H [Graduate School of Engineering, Chiba University, Chiba, 263-8522 (Japan); Aono, H [Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI48109 (United States)], E-mail: hliu@faculty.chiba-u.jp, E-mail: aonoh@umich.edu

    2009-03-01

    Hovering is a miracle of insects that is observed for all sizes of flying insects. Sizing effect in insect hovering on flapping-wing aerodynamics is of interest to both the micro-air-vehicle (MAV) community and also of importance to comparative morphologists. In this study, we present an integrated computational study of such size effects on insect hovering aerodynamics, which is performed using a biology-inspired dynamic flight simulator that integrates the modelling of realistic wing-body morphology, the modelling of flapping-wing and body kinematics and an in-house Navier-Stokes solver. Results of four typical insect hovering flights including a hawkmoth, a honeybee, a fruit fly and a thrips, over a wide range of Reynolds numbers from O(10{sup 4}) to O(10{sup 1}) are presented, which demonstrate the feasibility of the present integrated computational methods in quantitatively modelling and evaluating the unsteady aerodynamics in insect flapping flight. Our results based on realistically modelling of insect hovering therefore offer an integrated understanding of the near-field vortex dynamics, the far-field wake and downwash structures, and their correlation with the force production in terms of sizing and Reynolds number as well as wing kinematics. Our results not only give an integrated interpretation on the similarity and discrepancy of the near- and far-field vortex structures in insect hovering but also demonstrate that our methods can be an effective tool in the MAVs design.

  9. Modeling an elastic beam with piezoelectric patches by including magnetic effects

    CERN Document Server

    Ozer, A O

    2014-01-01

    Models for piezoelectric beams using Euler-Bernoulli small displacement theory predict the dynamics of slender beams at the low frequency accurately but are insufficient for beams vibrating at high frequencies or beams with low length-to-width aspect ratios. A more thorough model that includes the effects of rotational inertia and shear strain, Mindlin-Timoshenko small displacement theory, is needed to predict the dynamics more accurately for these cases. Moreover, existing models ignore the magnetic effects since the magnetic effects are relatively small. However, it was shown recently \\cite{O-M1} that these effects can substantially change the controllability and stabilizability properties of even a single piezoelectric beam. In this paper, we use a variational approach to derive models that include magnetic effects for an elastic beam with two piezoelectric patches actuated by different voltage sources. Both Euler-Bernoulli and Mindlin-Timoshenko small displacement theories are considered. Due to the magne...

  10. 3D Simulations of Space Charge Effects in Particle Beams

    Energy Technology Data Exchange (ETDEWEB)

    Adelmann, A

    2002-10-01

    For the first time, it is possible to calculate the complicated three-dimensional proton accelerator structures at the Paul Scherrer Institut (PSI). Under consideration are external and self effects, arising from guiding and space-charge forces. This thesis has as its theme the design, implementation and validation of a tracking program for charged particles in accelerator structures. This work form part of the discipline of Computational Science and Engineering (CSE), more specifically in computational accelerator modelling. The physical model is based on the collisionless Vlasov-Maxwell theory, justified by the low density ({approx} 10{sup 9} protons/cm{sup 3}) of the beam and of the residual gas. The probability of large angle scattering between the protons and the residual gas is then sufficiently low, as can be estimated by considering the mean free path and the total distance a particle travels in the accelerator structure. (author)

  11. Finite size effects in Neutron Star and Nuclear matter simulations

    CERN Document Server

    Molinelli, P A Giménez

    2014-01-01

    In this work we study molecular dynamics simulations of symmetric nuclear matter using a semi-classical nucleon interaction model. We show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the ``nuclear pasta'' phases expected in Neutron Star Matter simulations, but shaped by artificial aspects of the simulations. We explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. We find that different cells may yield different solutions for the same physical conditions (i.e. density and temperature). The particular shape of the solution at a given density can be predicted analytically by energy minimization. We also show that even if this behavior is due to finite size effects, it does not mean that it vanishes for very large systems and it actually is independent of the system size: The system size sets the only characteristic length scale for the inhomogeneitie...

  12. The Effect of Size and Ecology on Extinction Susceptibility

    Science.gov (United States)

    Huynh, C.; Yuan, A.; Heim, N.; Payne, J.

    2015-12-01

    Although life on Earth first emerged as prokaryotic organisms, it eventually evolved into billions of different species. However, extinctions on Earth, especially the five mass extinctions, have decimated species. So what leads to a species survival or demise during a mass extinction? Are certain species more susceptible to extinctions based on their size and ecology? For this project, we focused on the data of marine animals. To examine the impact of size and ecology on a species's likelihood of survival, we compared the sizes and ecologies of the survivors and victims of the five mass extinctions. The ecology, or life mode, of a genus consists of the combination of tiering, motility, and feeding mechanism. Tiering refers to the animal's typical location in the water column and sediments, motility refers to its ability to move, and feeding mechanism describes the way the organism eats; together, they describe the animal's behavior. We analyzed the effect of ecology on survival using logistic regression, which compares life mode to the success or failure of a genus during each mass extinction interval. For organism size, we found the extinct organisms' mean size (both volume and length) and compared it with the average size of survivors on a graph. Our results show that while surviving genera of mass extinctions tended to be slightly larger than those that went extinct, there was no significant difference. Even though the Permian (Changhsingian) and Triassic (Rhaetian) extinctions had larger surviving species, likewise the difference was small. Ecology had a more obvious impact on the likelihood of survival; fast-moving, predatory pelagic organisms were the most likely to go extinct, while sedentary, infaunal suspension feeders had the greatest chances of survival. Overall, ecology played a greater role than size in determining the survival of a species. With this information, we can use ecology to predict which species would survive future extinctions.

  13. AFM study of the SIMS beam induced roughness in monocrystalline silicon in presence of initial surface or bulk defects of nanometric size

    Energy Technology Data Exchange (ETDEWEB)

    Fares, B. [Laboratoire de Physique de la Matiere (UMR CNRS 5511), INSA de Lyon, 7 Avenue Capelle, F-69621 Villeurbanne Cedex (France)]. E-mail: boubker.fares@insa-lyon.fr; Dubois, C. [Laboratoire de Physique de la Matiere (UMR CNRS 5511), INSA de Lyon, 7 Avenue Capelle, F-69621 Villeurbanne Cedex (France); Gautier, B. [Laboratoire de Physique de la Matiere (UMR CNRS 5511), INSA de Lyon, 7 Avenue Capelle, F-69621 Villeurbanne Cedex (France); Dupuy, J.C. [Laboratoire de Physique de la Matiere (UMR CNRS 5511), INSA de Lyon, 7 Avenue Capelle, F-69621 Villeurbanne Cedex (France); Cayrel, F. [Universite de Tours, Laboratoire de Micro-Electronique de Puissance, 16 Rue Pierre et Marie Curie, F-37071 Tours Cedex 2 (France); Gaudin, G. [Universite de Tours, Laboratoire de Micro-Electronique de Puissance, 16 Rue Pierre et Marie Curie, F-37071 Tours Cedex 2 (France)

    2006-07-30

    In this paper, the SIMS beam induced roughness (BIR) in monocrystalline Si in presence of initial surface or bulk defects of nanometric size is studied. We follow the development of the BIR by monitoring the increase of Si{sup 2+} and SiO{sub 2} {sup +} signals during SIMS sputtering. The topography of the crater bottoms is measured at different steps of the evolution of the roughness using an atomic force microscope (AFM). We show that in presence of nanometric sized defects on the surface or in the bulk, the BIR develops far more rapidly than usual. It appears as soon as the crater reaches the defects and, as reported on Si free from any treatment, the same morphology evidencing waves perpendicular to the sputtering beam develops rapidly. This study of the behaviour of the BIR in presence of voluntarily introduced defects allows us to better understand the basic physical phenomena involved in its apparition.

  14. Grain size effects on He bubbles distribution and evolution

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Gao, X.; Gao, N. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Z.G., E-mail: zhgwang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Cui, M.H.; Wei, K.F.; Yao, C.F.; Sun, J.R.; Li, B.S.; Zhu, Y.B.; Pang, L.L. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Y.F. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang, D. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xie, E.Q. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2015-02-15

    Highlights: • SMAT treated T91 and conventional T91 were implanted by 200 keV He{sup 2+} to 1 × 10{sup 21} He m{sup −2} at room temperature and annealed at 450 °C for 3.5 h. • He bubbles in nanometer-size-grained T91 are smaller in as-implanted case. • The bubbles in the matrix of nanograins were hard to detect and those along the nanograin boundaries coalesced and filled with the grain boundaries after annealing. • Brownian motion and coalescence and Ostwald ripening process might lead to bubbles morphology presented in the nanometer-size-grained T91 after annealing. - Abstract: Grain boundary and grain size effects on He bubble distribution and evolution were investigated by He implantation into nanometer-size-grained T91 obtained by Surface Mechanical Attrition Treatment (SMAT) and the conventional coarse-grained T91. It was found that bubbles in the nanometer-size-grained T91 were smaller than those in the conventional coarse-grained T91 in as-implanted case, and bubbles in the matrix of nanograins were undetectable while those at nanograin boundaries (GBs) coalesced and filled in GBs after heat treatment. These results suggested that the grain size of structural material should be larger than the mean free path of bubble’s Brownian motion and/or denuded zone around GBs in order to prevent bubbles accumulation at GBs, and multiple instead of one type of defects should be introduced into structural materials to effectively reduce the susceptibility of materials to He embrittlement and improve the irradiation tolerance of structural materials.

  15. Enhanced oxidation resistance of active nanostructures via dynamic size effect

    Science.gov (United States)

    Liu, Yun; Yang, Fan; Zhang, Yi; Xiao, Jianping; Yu, Liang; Liu, Qingfei; Ning, Yanxiao; Zhou, Zhiwen; Chen, Hao; Huang, Wugen; Liu, Ping; Bao, Xinhe

    2017-01-01

    A major challenge limiting the practical applications of nanomaterials is that the activities of nanostructures (NSs) increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Here, using FeO NSs as an example, we show to the contrary, that reducing the size of active NSs can drastically increase their oxidation resistance. A maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. Rather than being determined by the structure or electronic properties of active sites, the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. We find this dynamic size effect to govern the chemical properties of active NSs. PMID:28223687

  16. [The effect of group size on salience of member desirability].

    Science.gov (United States)

    Sugimori, S

    1993-04-01

    This study tested the hypothesis that undesirable members are salient in a small group, while desirable members become salient in a larger group. One hundred and forty-five students were randomly assigned to twelve conditions, and read sentences desirably, undesirably, or neutrally describing each member of a college student club. The twelve clubs had one of three group sizes: 13, 39, or 52, and the proportion of the desirable or undesirable to the neutral was either 11:2 or 2:11, forming a three-way (3 x 2 x 2) factorial. Twelve subjects each were asked to make proportion judgments and impression ratings. Results indicated that proportion of the undesirable members was over estimated when the group size was 13, showing negativity bias, whereas proportion of the desirable was overestimated when the size was 52, displaying positivity bias. The size 39 showed neither positivity nor negativity bias. These results along with those from impression ratings suggested that salience of member desirability interacted with group size. It is argued that illusory correlation and group cognition studies may well take these effects into consideration.

  17. Study of effective dose of various protocols in equipment cone beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Soares, M. R.; Maia, A. F. [Universidade Federale de Sergipe, Departamento de Fisica, Cidade Universitaria Prof. Jose Aloisio de Campos, Marechal Rondon s/n, Jardim Rosa Elze, 49-100000 Sao Cristovao, Sergipe (Brazil); Batista, W. O. [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho, Salvador, 40301015 Bahia (Brazil); Caldas, L. V. E.; Lara, P. A., E-mail: mrs2206@gmail.com [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

    2014-08-15

    Currently the cone beam computed tomography is widely used in various procedures of dental radiology. Although the doses values associated with the procedures of cone beam CT are low compared to typical values associated with dental radiology procedure in multi slices CT. However can be high compared to typical values of other techniques commonly used in dental radiology. The present scenario is a very wide range of designs of equipment and, consequently, lack of uniformity in all parameters associated with x-ray generation and geometry. In this context, this study aimed to evaluate and calculate the absorbed dose in organs and tissues relevant and estimate effective dose for different protocols with different geometries of exposure in five cone beam CT equipment. For this, a female Alderson anthropomorphic phantom, manufactured by Radiology Support Devices was used. The phantom was irradiated with 26 dosimeters LiF: Mg, Ti (TLD-100), inserted in organs and tissues along the layers forming the head and neck of the phantom. The equipment used, in this present assessment, was: i-CAT Classical, Kodak 9000 3D, Gendex GXCB 500, Sirona Orthophos X G 3D and Planmeca Pro Max 3D. The effective doses were be determined by the ICRP 103 weighting factors. The values were between 7.0 and 111.5 micro Sv, confirming the broad dose range expected due to the diversity of equipment and protocols used in each equipment. The values of effective dose per Fov size were: between 7 and 51.2 micro Sv for located Fov; between 17.6 and 52.0 micro Sv for medium Fov; and between 11.5 and 43.1 micro Sv to large Fov (maxillofacial). In obtaining the effective dose the measurements highlighted a relevance contribution of dose absorbed by the remaining organs (36%), Salivary glands (30%), thyroid (12%) and bone marrow (12%). (Author)

  18. TU-A-BRE-01: The Relative Biological Effectiveness of Proton Beams Relative to Photon Beams

    Energy Technology Data Exchange (ETDEWEB)

    Paganetti, H [Massachusetts General Hospital ' Harvard Medical School, Boston, MA (United States); Stewart, R [University of Washington, Seattle, WA (United States); Carabe-Fernandez, A [Hospital of the University of Pennsylvania, Philadelphia, PA (United States)

    2014-06-15

    Proton therapy patients receive a 10% lower physical dose than the dose administered using photons, i.e. the proton relative biological effectiveness (RBE) is 1.1 in comparison to high-energy photons. The use of a generic, spatially invariant RBE within tumor targets and normal tissue structures disregards a large body of evidence indicating that proton RBE tends to increase with increasing linear energy transfer (LET). Because the doseaveraged proton LET in the distal edge of a spread out Bragg peak (SOBP) is larger than the LET in the plateau region or proximal edge of a SOBP, the use of a spatially invariant RBE is not well justified from a mechanistic point of view. On the other hand, the available clinical data on local tumor control rates and early or late side effects do not provide strong evidence against the continued use of a constant and spatially invariant clinical RBE. The only potential downside to the ongoing use of a constant RBE of 1.1 seems to be that we are missing a potential opportunity to enhance the therapeutic ratio, i.e., design proton therapy treatments in ways that exploit, rather than mitigate, spatial variations in proton RBE. Speakers in this symposium will: 1-review the laboratory and clinical evidence for and against the continued use of a spatially invariant RBE of 1.1, 2-examine some of the putative mechanisms connecting spatial variations in particle LET to estimates of the proton RBE at the molecular, cellular and tissue levels 3-assess the possible clinical significance of incorporating models for spatial variations in proton RBE into treatment planning systems. 4-discuss treatment planning and delivery techniques that will exploit the spatial variations of RBE within proton beams. Learning Objectives: To review laboratory and clinical evidence for and against the continued use of a constant RBE of 1.1 To understand major mechanisms connecting proton LET to RBE at the molecular, cellular and tissue levels. To quantify the

  19. Two-proton small-angle correlations in central heavy-ion collisions: A beam-energy- and system-size-dependent study

    Energy Technology Data Exchange (ETDEWEB)

    Kotte, R. [Forschungszentrum Rossendorf, IKH, PF 510119, Dresden (Germany); Alard, P.; Barret, V.; Bastid, N.; Crochet, P.; Dupieux, P. [IN2P3/CNRS and Universite Blaise Pascal, Laboratoire de Physique Corpusculaire, Clermont-Ferrand (France); Andronic, A.A. [Institute for Nuclear Physics and Engineering, Bucharest (Romania); Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Basrak, Z.; Caplar, R.; Dzelalija, M.; Gasparic, I. [Rudjer Boskovic Institute Zagreb, Zagreb (Croatia); Benabderrahmane, M.L.; Cordier, E.; Herrmann, N. [Physikalisches Institut der Universitaet Heidelberg, Heidelberg (Germany); Fodor, Z. [Central Research Institute for Physics, Budapest (Hungary); Gobbi, A.; Hartmann, O.N.; Hildenbrand, K.D. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Grishkin, Y. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Hong, B. [Korea University, Seoul (Korea); Kecskemeti, J.; Kim, Y.J.; Kirejczyk, M.; Koczon, P.; Korolija, M.; Kress, T.; Lebedev, A.; Leifels, Y.; Lopez, X.; Merschmeyer, M.; Moesner, J.; Neubert, W.; Pelte, P.; Petrovici, M.; Rami, F.; Reisdorf, W.; De Schauenburg, B.; Schuettauf, A.; Seres, Z.; Sikora, B.; Sim, K.S.; Simion, V.; Siwek-Wilczynska, K.; Smolyankin, V.; Stoicea, G.; Tyminski, Z.; Wagner, P.; Wisniewski, K.; Wohlfarth, D.; Xiao, Z.G.; Yushmanov, Y.; Zhilin, A.

    2005-02-01

    Small-angle correlations of pairs of protons emitted in central collisions of Ca+Ca, Ru+Ru and Au+Au at beam energies from 400 to 1500 MeV per nucleon are investigated with the FOPI detector system at SIS/GSI Darmstadt. Dependences on system size and beam energy are presented which extend the experimental data basis of pp correlations in the SIS energy range substantially. The size of the proton-emitting source is estimated by comparing the experimental data with the output of a final-state interaction model which utilizes either static Gaussian sources or the one-body phase-space distribution of protons provided by the BUU transport approach. The trends in the experimental data, i.e.system size and beam energy dependences, are well reproduced by this hybrid model. However, the pp correlation function is found rather insensitive to the stiffness of the equation of state entering the transport model calculations. (orig.)

  20. Finite size effects in neutron star and nuclear matter simulations

    Energy Technology Data Exchange (ETDEWEB)

    Giménez Molinelli, P.A., E-mail: pagm@df.uba.ar; Dorso, C.O.

    2015-01-15

    single structure per cell while the cubic and truncated octahedron show consistent results, with more than one structure per cell. For systems of the size studied in this work these effects are still noticeable, but we find evidence to support that the dependence of the results on the cell geometry becomes smaller as the system size is increased. When the Coulomb interaction is present, the competition between opposing interactions of different range results in a proper, physically meaningful length scale that is independent of the system size and periodic cell of choice. Only under these conditions “finite size effects” will vanish for large enough systems (i.e. cells much larger than this characteristic length). Larger simulations are in order, but our computational capabilities forbid it for the time being.

  1. Effect of ion and electron beam irradiation on surface morphology and optical properties of PVA

    Institute of Scientific and Technical Information of China (English)

    HM Eyssa; MO sman; SAK andil; MMA bdelrahman

    2015-01-01

    Polyvinyl alcohol (PVA) is a well-known friendly polymer for paper-making, textiles, and a variety of coat-ings, biomedical applications such as artificial pancreas, synthetic vitreous body, wound dressing, artificial skin, and cardiovascular device. In this paper, ion/electron beam is employed to get insight into the irradiation effect on surface morphology and optical properties of PVA polymer. UV-Vis spectra are recorded to investigate the effect of induced defects on the optical band gap and the formed carbon clusters size. Scanning electron microscopy (SEM) is used to relate and investigate surface morphology and optical properties of the target poly-mer with different doses (15, 30 and 60 min). Also, PVA polymer is subjected to theoretical studies by using semi-empirical PM7 quantum chemical method.

  2. Effect of size on the chaotic behavior of nano resonators

    Science.gov (United States)

    Alemansour, Hamed; Miandoab, Ehsan Maani; Pishkenari, Hossein Nejat

    2017-03-01

    Present study is devoted to investigate the size effect on chaotic behavior of a micro-electro-mechanical resonator under external electrostatic excitation. Using Galerkin's decomposition method, approximating the actuation force with a new effective lumped model, and neglecting higher order terms in the Taylor-series expansion, a simplified model of the main system is developed. By utilizing the Melnikov's method and based on the new form of the electrostatic force, an expression in terms of the system parameters is developed which can be used to rapidly estimate the chaotic region of the simplified system. Based on the analysis of the simple proposed model, it is shown that the effect of size on chaotic region varies significantly depending on bias voltage. By considering the size effect, it is demonstrated that chaotic vibration initiates at much higher constant voltages than predicted by classical theories; and, in high constant voltages, it is shown that strain gradient theory predicts occurrence of chaos at much lower amplitudes.

  3. Does screen size matter for smartphones? Utilitarian and hedonic effects of screen size on smartphone adoption.

    Science.gov (United States)

    Kim, Ki Joon; Sundar, S Shyam

    2014-07-01

    This study explores the psychological effects of screen size on smartphone adoption by proposing an extended Technology Acceptance Model (TAM) that integrates an empirical comparison between large and small screens with perceived control, affective quality, and the original TAM constructs. A structural equation modeling analysis was conducted on data collected from a between-subjects experiment (N=130) in which users performed a web-based task on a smartphone with either a large (5.3 inches) or a small (3.7 inches) screen. Results show that a large screen, compared to a small screen, is likely to lead to higher smartphone adoption by simultaneously promoting both the utilitarian and hedonic qualities of smartphones, which in turn positively influence perceived ease of use of-and attitude toward-the device respectively. Implications and directions for future research are discussed.

  4. Power and sample size in cost-effectiveness analysis.

    Science.gov (United States)

    Laska, E M; Meisner, M; Siegel, C

    1999-01-01

    For resource allocation under a constrained budget, optimal decision rules for mutually exclusive programs require that the treatment with the highest incremental cost-effectiveness ratio (ICER) below a willingness-to-pay (WTP) criterion be funded. This is equivalent to determining the treatment with the smallest net health cost. The designer of a cost-effectiveness study needs to select a sample size so that the power to reject the null hypothesis, the equality of the net health costs of two treatments, is high. A recently published formula derived under normal distribution theory overstates sample-size requirements. Using net health costs, the authors present simple methods for power analysis based on conventional normal and on nonparametric statistical theory.

  5. Size effects in Al nanopillars: Single crystalline vs. bicrystalline

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, Allison; Pathak, Siddhartha [Division of Engineering and Applied Sciences, California Institute of Technology, 1200 East California Boulevard, MC 309-81, Pasadena, CA 91125-8100 (United States); Greer, Julia R., E-mail: jrgreer@caltech.edu [Division of Engineering and Applied Sciences, California Institute of Technology, 1200 East California Boulevard, MC 309-81, Pasadena, CA 91125-8100 (United States)

    2011-06-15

    The mechanical behavior of bicrystalline aluminum nano-pillars under uniaxial compression reveals size effects, a stochastic stress-strain signature, and strain hardening. Pillar diameters range from 400 nm to 2 {mu}m and contain a single, non-sigma high angle grain boundary oriented parallel to the pillar axes. Our results indicate that these bicrystalline pillars are characterized by intermittent strain bursts and exhibit an identical size effect to their single crystalline counterparts. Further, we find that the presence of this particular grain boundary generally decreases the degree of work hardening relative to the single crystalline samples. These findings, along with transmission electron microscopy analysis, show that nano-pillar plasticity in the presence of a grain boundary is also characterized by dislocation avalanches, likely resulting from dislocation nucleation-controlled mechanisms, and that at these small length scales this grain boundary may serve as a dislocation sink rather than a dislocation source.

  6. Shear-banding Induced Indentation Size Effect in Metallic Glasses

    Science.gov (United States)

    Lu, Y. M.; Sun, B. A.; Zhao, L. Z.; Wang, W. H.; Pan, M. X.; Liu, C. T.; Yang, Y.

    2016-06-01

    Shear-banding is commonly regarded as the “plasticity carrier” of metallic glasses (MGs), which usually causes severe strain localization and catastrophic failure if unhindered. However, through the use of the high-throughput dynamic nanoindentation technique, here we reveal that nano-scale shear-banding in different MGs evolves from a “distributed” fashion to a “localized” mode when the resultant plastic flow extends over a critical length scale. Consequently, a pronounced indentation size effect arises from the distributed shear-banding but vanishes when shear-banding becomes localized. Based on the critical length scales obtained for a variety of MGs, we unveil an intrinsic interplay between elasticity and fragility that governs the nanoscale plasticity transition in MGs. Our current findings provide a quantitative insight into the indentation size effect and transition mechanisms of nano-scale plasticity in MGs.

  7. Experimental study of vortex ring interactions with a flexible beam; investigating the role of viscous effects

    Science.gov (United States)

    Pirnia, Alireza; Hu, Jiacheng; Peterson, Sean; Erath, Byron

    2016-11-01

    Energy can be extracted from flow instabilities in the environment for powering low consumption devices. When vortices pass tangentially over a flexible beam the lower pressure in the vortex core causes the beam to deflect, and induces sustained oscillations which can be converted into energy via piezoelectric materials. The beam dynamics can be parameterized according to the beam properties (nondimensional mass and stiffness ratios) as well as the vortex properties (size, vortex circulation strength and advection velocity). Recently, inviscid models have been developed to solve this fluid-structure interaction problem but they do not capture viscous interactions; features that become more prominent when the beam is positioned close to the vortex core. In this study the interaction of a vortex ring passing tangentially over a flexible beam as a function of circulation strength, beam properties, and offset distance are investigated to identify how viscous interactions influence the energy exchange process. Particle image velocimetry is acquired in tandem with the beam dynamics. The velocity and pressure fields, and transient beam dynamics are compared and contrasted with an inviscid model to identify the role of viscous interactions. This work was supported by the National Science Foundation Grant CBET #1511761.

  8. Size Effect of Electromagnetic Constitutive Characteristics of Ultrathin Al Films

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The ultrathin aluminum films with thickness in the range of 2~60 nm have been deposited by dc magnetron sputtering apparatus. Reflectance and transmittance of the obtained samples were measured with a WFZ-900-D4 UV/VIS spectrophotometer. The optical constant (n, k) and permittivity (ε', e") were determined by applying Newton-Simpson recurrent substitution method. The results indicate that the electromagnetic constitutive characteristic of ultrathin aluminum films is a function of thickness and has obvious size effect.

  9. Implicit Finite-Size Effects in Computer Simulations

    OpenAIRE

    Denton, A. R.; EGELSTAFF, P. A.

    1997-01-01

    The influence of periodic boundary conditions (implicit finite-size effects) on the anisotropy of pair correlations in computer simulations is studied for a dense classical fluid of pair-wise interacting krypton atoms near the triple point. Molecular dynamics simulation data for the pair distribution function of N-particle systems, as a function of radial distance, polar angle, and azimuthal angle are compared directly with corresponding theoretical predictions [L. R. Pratt and S. W. Haan, J....

  10. System effects influencing the bending strength of timber beams

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager; Källsner, B.

    1998-01-01

    measurements of the strengths of a large number of shorttest pieces cut from the beams such that judgementally each test piece contains only a single defect cluster. The testpiece is spliced to stronger wood beam shafts in both ends. Due to the occurrence of a substantial number of splicefailures in the total...

  11. Study of the Temperature Turbulences Effect upon Optical Beam in Atmospheric Optical Communication

    Directory of Open Access Journals (Sweden)

    F. Dvorak

    2011-09-01

    Full Text Available The paper deals with the study of the effect of temperature turbulences upon the optical beam. The polarization parameters of optical radiation sources and different optical beam states of polarization have been investigated. The obtained polarization parameters are projected on the Poincare sphere by means of Stokes vectors. The optical power distribution curves of optical beams are processed into diagrams. The horizontal and vertical components of linearly and circularly polarized optical beams have been studied. The turbulence flux has vertical direction and the optical beam is propagating through an atmosphere environment with three different states of turbulence. The evaluation of the obtained data was done by means of variance and correlation functions computing. Different rates of effect of temperature turbulences upon horizontal and vertical components were found. To reduce the rate of effect the advantage of an optical beam with circular polarization has been proposed.

  12. Size Effects in Impact Damage of Composite Sandwich Panels

    Science.gov (United States)

    Dobyns, Alan; Jackson, Wade

    2003-01-01

    Panel size has a large effect on the impact response and resultant damage level of honeycomb sandwich panels. It has been observed during impact testing that panels of the same design but different panel sizes will show large differences in damage when impacted with the same impact energy. To study this effect, a test program was conducted with instrumented impact testing of three different sizes of sandwich panels to obtain data on panel response and residual damage. In concert with the test program. a closed form analysis method was developed that incorporates the effects of damage on the impact response. This analysis method will predict both the impact response and the residual damage of a simply-supported sandwich panel impacted at any position on the panel. The damage is incorporated by the use of an experimental load-indentation curve obtained for the face-sheet/honeycomb and indentor combination under study. This curve inherently includes the damage response and can be obtained quasi-statically from a rigidly-backed specimen or a specimen with any support conditions. Good correlation has been obtained between the test data and the analysis results for the maximum force and residual indentation. The predictions can be improved by using a dynamic indentation curve. Analyses have also been done using the MSC/DYTRAN finite element code.

  13. Radiation and Background Levels in a CLIC Detector due to Beam-Beam Effects Optimisation of Detector Geometries and Technologies

    CERN Document Server

    Sailer, André; Lohse, Thomas

    2013-01-10

    The high charge density---due to small beam sizes---and the high energy of the proposed CLIC concept for a linear electron--positron collider with a centre-of-mass energy of up to 3~TeV lead to the production of a large number of particles through beam-beam interactions at the interaction point during every bunch crossing (BX). A large fraction of these particles safely leaves the detector. A still significant amount of energy will be deposited in the forward region nonetheless, which will produce secondary particles able to cause background in the detector. Furthermore, some particles will be created with large polar angles and directly cause background in the tracking detectors and calorimeters. The main sources of background in the detector, either directly or indirectly, are the incoherent $mathrm{e}^{+}mathrm{e}^{-}$ pairs and the particles from $gammagamma ightarrow$ hadron events. The background and radiation levels in the detector have to be estimated, to study if a detector is feasible, that can han...

  14. PECVD Environmental Effects on Silicon Nanoparticle Size and Quality

    Science.gov (United States)

    Klafehn, Grant; Kendrick, Chito; Guan, Tianyuan; Theingi, San; Riskey, Kory; Vitti, Lauren; Bagolini, Luigi; Lusk, Mark; Gorman, Brian; Taylor, Craig; Collins, Reuben; Fields, Jeremy; Stradins, Paul

    2014-03-01

    Silicon based nanoparticles (SiNPs) have recently been of great interest to the PV community because of their unique properties compared to their bulk constituents. By decreasing a nanoparticle's (NP) size below its exciton Bohr radius, its band gap can be increased relative to the bulk. This talk will discuss fundamental variables involved in defining and controlling plasma-grown SiNP size and quality. A quartz tube with a RF electrode ring is used to create a plasma in an argon-silane mixture to grow the SiNPs. Their quality and size can be changed by varying the reactor pressure, gas flow, and thus the resulting residence time. They are then characterized by Raman, PL, ESR, XRD, and TEM, and then mapped to a phase diagram with respect to pressure and flow. Higher residence times of 10 ms resulted in highly crystalline, 7 nm SiNPs. Residence times of 2 ms create 4 nm particles, while below 2 ms will result in highly defective material, even though the PL exhibits peaks at 1.6 eV. These parameters will be discussed, including how each variable affects the resultant SiNP size, quality. Also included will be a discussion about additive gasses and their additional effects on SiNP characteristics. We acknowledge support given by the DOE (DE-EE0005326) and NSF REMRSEC (DMR 0820518).

  15. Effect of sonication on the particle size of montmorillonite clays.

    Science.gov (United States)

    Poli, Alessandra L; Batista, Tatiana; Schmitt, Carla C; Gessner, Fergus; Neumann, Miguel G

    2008-09-15

    This paper reports on the effect of sonication on SAz-1 and SWy-1 montmorillonite suspensions. Changes in the size of the particles of these materials and modifications of their properties have been investigated. The variation of the particle size has been analyzed by DLS (dynamic light scattering). In all cases the clay particles show a bimodal distribution. Sonication resulted in a decrease of the larger modal diameter, as well as a reduction of its volume percentage. Simultaneously, the proportion of the smallest particles increases. After 60 min of sonication, SAz-1 presented a very broad particle size distribution with a modal diameter of 283 nm. On the other hand, the SWy-1 sonicated for 60 min presents a bimodal distribution of particles at 140 and 454 nm. Changes in the properties of the clay suspensions due to sonication were evaluated spectroscopically from dye-clay interactions, using Methylene Blue. The acidic sites present in the interlamellar region, which are responsible for dye protonation, disappeared after sonication of the clay. The changes in the size of the scattering particles and the lack of acidic sites after sonication suggest that sonication induces delamination of the clay particles.

  16. Serving size guidance for consumers: is it effective?

    Science.gov (United States)

    Faulkner, G P; Pourshahidi, L K; Wallace, J M W; Kerr, M A; McCrorie, T A; Livingstone, M B E

    2012-11-01

    Larger portion sizes (PS) may be inciting over-eating and contributing to obesity rates. Currently, there is a paucity of data on the effectiveness of serving size (SS) guidance. The aims of the present review are to evaluate SS guidance; the understanding, usability and acceptability of such guidance, its impact on consumers and potential barriers to its uptake. A sample of worldwide SS guidance schemes (n 87) were identified using targeted and untargeted searches, overall these were found to communicate various inconsistent and often conflicting messages about PS selection. The available data suggest that consumers have difficulty in understanding terms such as 'portion size' and 'serving size', as these tend to be used interchangeably. In addition, discrepancies between recommended SS and those present on food labels add to the confusion. Consumers generally understand and visualise SS best when expressed in terms of household measures rather than actual weights. Only a limited number of studies have examined the direct impact of SS guidance on consumer behaviour with equivocal results. Although consumers recognise that guidance on selecting SS would be helpful, they are often unwilling to act on such guidance. The challenge of achieving consumer adherence to SS guidance is formidable due to several barriers including chronic exposure to larger PS, distorted consumption norms and perceptions, the habit of 'cleaning one's plate' and language barriers for ethnic minorities. In conclusion, the impact of SS guidance on consumers merits further investigation to ensure that future guidance resonates with consumers by being more understandable, usable and acceptable.

  17. Size and shape effects on magnetic properties of Ni nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Xuemin He; Huigang Shi

    2012-01-01

    Pure Ni nanoparticles ranging in size from 24 to 200nm are prepared via thermal decomposition of nickel acetylacetonate in oleylamine.The as-prepared Ni particles change from spherical to dendritic or starlike with increasing precursor concentration.The particles are stable because the organic coating occurs in situ.Magnetic measurement reveals that all the Ni nanoparticles are ferromagnetic and show ferromagnetic-paramagnetic transitions at their Curie points.The saturation magnetization Ms is sizedependent,with a maximum value of 52.01 and 82.31 emu/g at room temperature and 5 K,respectively.The coercivity decreases at first and then increases with increasing particle size,which is attributed to the competition between size effect and shape anisotropy.The Curie temperature Tc is 593,612,622,626 and 627 K for the 24,50,96,165 and 200 nm Ni nanoparticles,respectively.A theoretical model is proposed to explain the size-dependence of Ni nanoparticle Curie temperature.

  18. Reinforced polypropylene composites: effects of chemical compositions and particle size.

    Science.gov (United States)

    Ashori, Alireza; Nourbakhsh, Amir

    2010-04-01

    In this work, the effects of wood species, particle sizes and hot-water treatment on some physical and mechanical properties of wood-plastic composites were studied. Composites of thermoplastic reinforced with oak (Quercus castaneifolia) and pine (Pinus eldarica) wood were prepared. Polypropylene (PP) and maleic anhydride grafted polypropylene (MAPP) were used as the polymer matrix and coupling agent, respectively. The results showed that pine fiber had significant effect on the mechanical properties considered in this study. This effect is explained by the higher fiber length and aspect ratio of pine compared to the oak fiber. The hot-water treated (extractive-free) samples, in both wood species, improved the tensile, flexural and impact properties, but increased the water absorption for 24h. This work clearly showed that lignocellulosic materials in both forms of fiber and flour could be effectively used as reinforcing elements in PP matrix. Furthermore, extractives have marked effects on the mechanical and physical properties.

  19. Quantumlike description of the nonlinear and collective effects on relativistic electron beams in strongly magnetized plasmas

    CERN Document Server

    Tanjia, Fatema; Fedele, Renato; Shukla, P K; Jovanovic, Dusan

    2011-01-01

    A numerical analysis of the self-interaction induced by a relativistic electron/positron beam in the presence of an intense external longitudinal magnetic field in plasmas is carried out. Within the context of the Plasma Wake Field theory in the overdense regime, the transverse beam-plasma dynamics is described by a quantumlike Zakharov system of equations in the long beam limit provided by the Thermal Wave Model. In the limiting case of beam spot size much larger than the plasma wavelength, the Zakharov system is reduced to a 2D Gross-Pitaevskii-type equation, where the trap potential well is due to the external magnetic field. Vortices, "beam halos" and nonlinear coherent states (2D solitons) are predicted.

  20. Assessment of protocols in cone beam CT with symmetric and asymmetric beam using effective dose and P{sub ka}

    Energy Technology Data Exchange (ETDEWEB)

    Batista, W. O.; Linhares de O, M. V. [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho, Salvador, 40301015 Bahia (Brazil); Soares, M. R.; Maia, A. F. [Universidade Federal de Sergipe, Departamento de Fisica, Cidade Universitaria Prof. Jose Aloisio de Campos, Marechal Rondon s/n, Jardim Rosa Elze, 49-100000 Sao Cristovao, Sergipe (Brazil); Caldas, L. V. E., E-mail: wilsonottobatista@gmail.com [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

    2014-08-15

    The cone beam CT is an emerging technology in dental radiology with significant differences the point of view of design technology between the various manufacturers on the world market. This study aims to evaluate and compare protocols with similar purposes in a cone beam CT scanner using TLDs and air kerma - area product (P{sub ka}) as kerma index. Measurements were performed on two protocols used to obtain the image the maxilla-mandible in equipment Gendex GXCB 500: Protocol [GX1] extended diameter and asymmetric beam (14 cm x 8.5 cm - maxilla / mandible) and protocol [GX2] symmetrical beam (8.5 cm x 8.5 cm - maxillary / mandible). Was used LiF dosimeters (TLD 100) inserted into a female anthropomorphic phantom manufactured by Radiology Support Devices. For all protocols evaluated the value of P{sub ka} using a meter Diamentor E2 and PTW system Radcal Rapidose. The results obtained for Effective Dose / P{sub ka} these measurements were separated by protocol image. Protocol [GX1]: 44.5 μSv/478 mGy cm{sup 2}; protocol [GX2]: 54.8 μSv/507 mGy cm{sup 2}. These values indicate that the relationship between the diameter of the image acquired in the protocol [GX1] and the diameter of the image in the protocol [GX2] is equal to 1.65, the Effective Dose for the first protocol has lower value at 18%. P{sub ka} values reveal very similar results between the two protocols, although, common sense leads to the interpretation that imaging protocols with field of view (Fov) of large diameters imply high values of effective dose when compared to small diameters. However, in this particular case, this is not true due to the asymmetrical beam technology. Conclude that for the cases where the scanner uses asymmetric beam to obtain images with large diameters that cover the entire face there are advantages from the point of view of reducing the exposure of patients with respect to the use of symmetrical beam and / or to Fov images with a smaller diameter. (Author)

  1. Effect of Size Polydispersity on Melting of Charged Colloidal Systems

    Institute of Scientific and Technical Information of China (English)

    陈勇

    2003-01-01

    We introduce simple prescriptions of the Yukawa potential to describe the effect of size polydispersity and macroion shielding effect in charged colloidal systems. The solid-liquid phase boundaries were presented with the Lindemann criterion based on molecular dynamics simulations. Compared with the Robbins-Kremer-Grest simulation results, a deviation of melting line is observed at small λ, which means large macroion screening length. This deviation of phase boundary is qualitatively consistent with the simulation result of the nonlinear Poisson-Boltzmann equation with full many-body interactions. It is found that this deviation of the solid-liquid phase behaviour is sensitive to the screening parameter.

  2. Hofmeister effects: interplay of hydration, nonelectrostatic potentials, and ion size.

    Science.gov (United States)

    Parsons, Drew F; Boström, Mathias; Lo Nostro, Pierandrea; Ninham, Barry W

    2011-07-21

    The classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloids, and corresponding theories of electrolytes, are unable to explain ion specific forces between colloidal particles quantitatively. The same is true generally, for surfactant aggregates, lipids, proteins, for zeta and membrane potentials and in adsorption phenomena. Even with fitting parameters the theory is not predictive. The classical theories of interactions begin with continuum solvent electrostatic (double layer) forces. Extensions to include surface hydration are taken care of with concepts like inner and outer Helmholtz planes, and "dressed" ion sizes. The opposing quantum mechanical attractive forces (variously termed van der Waals, Hamaker, Lifshitz, dispersion, nonelectrostatic forces) are treated separately from electrostatic forces. The ansatz that separates electrostatic and quantum forces can be shown to be thermodynamically inconsistent. Hofmeister or specific ion effects usually show up above ≈10(-2) molar salt. Parameters to accommodate these in terms of hydration and ion size had to be invoked, specific to each case. Ionic dispersion forces, between ions and solvent, for ion-ion and ion-surface interactions are not explicit in classical theories that use "effective" potentials. It can be shown that the missing ionic quantum fluctuation forces have a large role to play in specific ion effects, and in hydration. In a consistent predictive theory they have to be included at the same level as the nonlinear electrostatic forces that form the skeletal framework of standard theory. This poses a challenge. The challenges go further than academic theory and have implications for the interpretation and meaning of concepts like pH, buffers and membrane potentials, and for their experimental interpretation. In this article we overview recent quantitative developments in our evolving understanding of the theoretical origins of specific ion, or Hofmeister effects. These are demonstrated

  3. Thickness effect on properties of titanium film deposited by d.c. magnetron sputtering and electron beam evaporation techniques

    Indian Academy of Sciences (India)

    Nishat Arshi; Junqing Lu; Chan Gyu Lee; Jae Hong Yoon; Bon Heun Koo; Faheem Ahmed

    2013-10-01

    This paper reports effect of thickness on the properties of titanium (Ti) film deposited on Si/SiO2 (100) substrate using two different methods: d.c. magnetron sputtering and electron beam (e-beam) evaporation technique. The structural and morphological characterization of Ti film were performed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). XRD pattern revealed that the films deposited using d.c. magnetron sputtering have HCP symmetry with preferred orientation along (002) plane, while those deposited with e-beam evaporation possessed fcc symmetry with preferred orientation along (200) plane. The presence of metallic Ti was also confirmed by XPS analysis. FESEM images depicted that the finite sized grains were uniformly distributed on the surface and AFM micrographs revealed roughness of the film. The electrical resistivity measured using four-point probe showed that the film deposited using d.c. magnetron sputtering has lower resistivity of ∼13 cm than the film deposited using e-beam evaporation technique, i.e. ∼60 cm. The hardness of Ti films deposited using d.c. magnetron sputtering has lower value (∼7.9 GPa) than the film deposited using e-beam technique (∼9.4 GPa).

  4. EXPLOSIVE ABSORPTION EFFECT OF POWER CO2 LASER BEAM IN ATMOSPHERE

    OpenAIRE

    Zakharov, V.; Shmelev, V.; Nesterenko, A.

    1991-01-01

    The interaction of a wide beam of intense 10.6 µm and 9.4 µm laser radiation with atmospheric CO2 is studied. The threshold spectroscopic effect of explosive absorption have been obtained. In this effect the absorption coefficient of the atmosphere increases sharply owing to strong self-heating ([MATH] 700-1000 K) of the beam channel.

  5. Green's functions of the forced vibration of Timoshenko beams with damping effect

    Science.gov (United States)

    Li, X. Y.; Zhao, X.; Li, Y. H.

    2014-03-01

    This paper is concerned with the dynamic solutions for forced vibrations of Timoshenko beams in a systematical manner. Damping effects on the vibrations of the beam are taken into consideration by introducing two characteristic parameters. Laplace transform method is applied in the present study and corresponding Green's functions are presented explicitly for beams with various boundaries. The present solutions can be readily reduced to those for others classical beam models by setting corresponding parameters to zero or infinite. Numerical calculations are performed to validate the present solutions and the effects of various important physical parameters are investigated.

  6. Gaussian Beam Effect on Equivalence Principle Test Using Free-Fall Interferometry

    Institute of Scientific and Technical Information of China (English)

    严琴; 周泽兵; 龙长才; 罗俊; 张元仲; 聂玉昕

    2002-01-01

    We discuss the Gaussian beam effect on the test of the equivalence principle using a free-fall interferometer.A two-lens assembly is used to improve the propagating character of the laser beam, and the beam radius is collimated to about 3.0 mm. The analysis shows that the gravity acceleration difference induced by the Gaussian beam effect could be less than 10-15 g for our double free-fall experimental design, but it would be 10-9 g for the absolute measurement of the gravity acceleration with the usual single free-fall method.

  7. Finite size effects in simulations of protein aggregation.

    Directory of Open Access Journals (Sweden)

    Amol Pawar

    Full Text Available It is becoming increasingly clear that the soluble protofibrillar species that proceed amyloid fibril formation are associated with a range of neurodegenerative disorders such as Alzheimer's and Parkinson diseases. Computer simulations of the processes that lead to the formation of these oligomeric species are starting to make significant contributions to our understanding of the determinants of protein aggregation. We simulate different systems at constant concentration but with a different number of peptides and we study the how the finite number of proteins affects the underlying free energy of the system and therefore the relative stability of the species involved in the process. If not taken into account, this finite size effect can undermine the validity of theoretical predictions regarding the relative stability of the species involved and the rates of conversion from one to the other. We discuss the reasons that give rise to this finite size effect form both a probabilistic and energy fluctuations point of view and also how this problem can be dealt by a finite size scaling analysis.

  8. Ion size effect on colloidal forces within the primitive model

    Directory of Open Access Journals (Sweden)

    J.Wu

    2005-01-01

    Full Text Available The effect of ion size on the mean force between a pair of isolated charged particles in an electrolyte solution is investigated using Monte Carlo simulations within the framework of the primitive model where both colloidal particles and small ions are represented by charged hard spheres and the solvent is treated as a dielectric continuum. It is found that the short-ranged attraction between like-charged macroions diminishes as the diameter of the intermediating divalent counterions and coions increases and the maximum attractive force is approximately a linear function of the counterion diameter. This size effect contradicts the prediction of the Asakura-Oosawa theory suggesting that an increase in the excluded volume of small ions would lead to a stronger depletion between colloidal particles. Interestingly, the simulation results indicate that both the hard-sphere collision and the electrostatic contributions to the mean force are insensitive to the size disparity of colloidal particles with the same average diameter.

  9. Visual acuity in mammals: effects of eye size and ecology.

    Science.gov (United States)

    Veilleux, Carrie C; Kirk, E Christopher

    2014-01-01

    Previous comparative research has attributed interspecific variation in eye size among mammals to selection related to visual acuity. Mammalian species have also been hypothesized to differ in visual acuity partly as a result of differences in ecology. While a number of prior studies have explored ecological and phylogenetic effects on eye shape, a broad comparative analysis of the relationships between visual acuity, eye size and ecology in mammals is currently lacking. Here we use phylogenetic comparative methods to explore these relationships in a taxonomically and ecologically diverse sample of 91 mammal species. These data confirm that axial eye length and visual acuity are significantly positively correlated in mammals. This relationship conforms to expectations based on theoretical optics and prior analyses of smaller comparative samples. Our data also demonstrate that higher visual acuity in mammals is associated with: (1) diurnality and (2) predatory habits once the effects of eye size and phylogeny have been statistically controlled. These results suggest that interspecific variation in mammalian visual acuity is the result of a complex interplay between phylogenetic history, visual anatomy and ecology.

  10. Ion beam induced luminescence: Relevance to radiation induced bystander effects

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S.B., E-mail: ahmad.rabilal@gmail.com [Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, Ontario (Canada); McNeill, F.E., E-mail: fmcneill@mcmaster.ca [Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, Ontario (Canada); Byun, S.H., E-mail: soohyun@mcmaster.ca [Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, Ontario (Canada); Prestwich, W.V., E-mail: prestwic@mcmaster.ca [Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, Ontario (Canada); Seymour, C., E-mail: seymouc@mcmaster.ca [Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, Ontario (Canada); Mothersill, C.E., E-mail: mothers@mcmaster.ca [Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, Ontario (Canada)

    2012-10-01

    The aim of this work is quantify the light emitted as a result of charged particle interaction in materials which may be of relevance to radiation induced 'bystander effects' studies. We have developed a system which employs single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. The system uses a fast photomultiplier tube with a peak cathode response at 420 nm. It has been tested in a proof-of-principle experiment using polystyrene targets. Light output, as a result of irradiation, was measured. The luminescence yield appears to have a non-linear behavior with the incident ion fluence: it rises exponentially to an asymptotic value. The target was irradiated with beam energies varying from 1 to 2 MeV and showed saturation at or before an incident fluence rate of 3 Multiplication-Sign 10{sup 13} H{sup +}/cm{sup 2} s. The average saturation value for the photon output was found to be 40 Multiplication-Sign 10{sup 6} cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28 Multiplication-Sign 10{sup 3}, 10 Multiplication-Sign 10{sup 6}, and 35 Multiplication-Sign 10{sup 6} cps for wavelengths of 280 {+-} 5 nm, 320 {+-} 5 nm and 340 {+-} 5 nm respectively. The light output reaches a maximum value because of damage induced in the polymer. Our measurements indicate a 'damage cross section' of the order of 10{sup -14} cm{sup 2}. The average radiant intensity was found to increase at wavelengths of 280 and 320 nm when the proton energy was increased. This was not found to occur at 340 nm. In conclusion, the light emission at specific wavelengths was found to depend upon the incident proton fluence and the proton energy. The wavelengths of the emitted light measured in this study have significance for the understanding of radiation induced bystander effects.

  11. Non-stationary Effects In Space-charge Dominated Electron Beams

    CERN Document Server

    Agafonov, A V; Tarakanov, V P

    2004-01-01

    Problems of non-linear dynamics of space charge dominated electron beams in plane and in coaxial electron guns are discussed from the point of view of non-stationary behaviour of beams. The results of computer simulations of beam formation are presented for several simple plane diode geometries and for the gun with large compression of annular beam. Emphasised is non-stationary behaviour combined with edge and hysteresis effects. Non-stationary effects in crossed electron and magnetic field are considered from the point of view a development of schemes of intense electron beam formation for compact accelerators and RF-devices. The results of computer simulation of beam formation inside coaxial guns are described under condition of secondary self-sustaining emission. Possibilities of electron storage and capture due to transient processes are discussed. Work supported by RFBR under grant 03-02-17301.

  12. Effects of picture size reduction and blurring on emotional engagement.

    Directory of Open Access Journals (Sweden)

    Andrea De Cesarei

    Full Text Available The activity of basic motivational systems is reflected in emotional responses to arousing stimuli, such as natural pictures. The manipulation of picture properties such as size or detail allows for investigation into the extent to which separate emotional reactions are similarly modulated by perceptual changes, or, rather, may subserve different functions. Pursuing this line of research, the present study examined the effects of two types of perceptual degradation, namely picture size reduction and blurring, on emotional responses. Both manipulations reduced picture relevance and dampened affective modulation of skin conductance, possibly because of a reduced action preparation in response to degraded or remote pictures. However, the affective modulation of the startle reflex did not vary with picture degradation, suggesting that the identification of these degraded affective cues activated the neural circuits mediating appetitive or defensive motivation.

  13. Shaking and Blending Effect on Microalgae Concentrates Size

    Directory of Open Access Journals (Sweden)

    LUDI PARWADANI AJI

    2012-03-01

    Full Text Available Microalgae concentrates (paste can be used as an alternative feed to replace live microalgae for aquaculture due to its nutritional value and convenience. However, the clumping of cells and negative buoyancy of algae concentrate can affect bivalve culture as bivalves only capture particles in suspension and ingest a certain size range of particles. This study investigated the effect of shaking and blending treatments on the preparation of food suspensions prepared from algae concentrates (Isochrysis and Pavlova. The results indicated that the higher the shaking time (5, 10, and 15 times or blending time (10, 30, and 60 seconds, the smaller was the diameter of the resulting algae particles. Moreover, the greater the volume of algae concentrate used in preparation, the larger the diameter of algae particles produced. Shaking may be the best option because it is cheaper and simpler. However, all the treatments provided a suitable particle size range for ingestion by bivalves.

  14. Fast and accurate determination of modularity and its effect size

    CERN Document Server

    Treviño, Santiago; Del Genio, Charo I; Bassler, Kevin E

    2014-01-01

    We present a fast spectral algorithm for community detection in complex networks. Our method searches for the partition with the maximum value of the modularity via the interplay of several refinement steps that include both agglomeration and division. We validate the accuracy of the algorithm by applying it to several real-world benchmark networks. On all these, our algorithm performs as well or better than any other known polynomial scheme. This allows us to extensively study the modularity distribution in ensembles of Erd\\H{o}s-R\\'enyi networks, producing theoretical predictions for means and variances inclusive of finite-size corrections. Our work provides a way to accurately estimate the effect size of modularity, providing a $z$-score measure of it and enabling a more informative comparison of networks with different numbers of nodes and links.

  15. Modeling the light-travel-time effect on the far-infrared size of IRC +10216

    Science.gov (United States)

    Wright, Edward L.; Baganoff, Frederick K.

    1995-01-01

    Models of the far-infrared emission from the large circumstellar dust envelope surrounding the carbon star IRC +10216 are used to assess the importance of the light-travel-time effect (LTTE) on the observed size of the source. The central star is a long-period variable with an average period of 644 +/- 17 days and a peak-to-peak amplitude of two magnituds, so a large light-travel-time effect is seen at 1 min radius. An attempt is made to use the LTTE to reconcile the discrepancy between the observations of Fazio et al. and Lester et al. regarding the far-infrared source size. This discrepancy is reviewed in light of recent, high-spatial-resolution observations at 11 microns by Danchi et al. We conclude that IRC +10216 has been resolved on the arcminute scale by Fazio et al. Convolution of the model intensity profile at 61 microns with the 60 sec x 90 sec Gaussian beam of Fazio et al. yields an observed source size full width at half maximum (FWHM) that ranges from approximately 67 sec to 75 sec depending on the phase of the star and the assumed distance to the source. Using a simple r(exp -2) dust distribution and the 106 deg phase of the Fazio et al. observations, the LTTE model reaches a peak size of 74.3 sec at a distance of 300 pc. This agrees favorably with the 78 sec x 6 sec size measured by Fazio et al. Finally, a method is outlined for using the LTTE as a distance indicator to IRC +10216 and other stars with extended mass outflows.

  16. Accuracy of linear measurements from cone-beam computed tomography-derived surface models of different voxel sizes

    NARCIS (Netherlands)

    Damstra, Janalt; Fourie, Zacharias; Huddleston Slater, James J R; Ren, Yijin

    2010-01-01

    INTRODUCTION: The aims of this study were to determine the linear accuracy of 3-dimensional surface models derived from a commercially available cone-beam computed tomography (CBCT) dental imaging system and volumetric rendering software and to investigate the influence of voxel resolution on the li

  17. Radiologic evaluation of an unusually sized complex odontoma involving the maxillary sinus by cone beam computed tomography.

    Science.gov (United States)

    Isler, Sabri Cemil; Demircan, Sabit; Soluk, Merva; Cebi, Zerrin

    2009-01-01

    As a group, odontomas are the most common odontogenic neoplasms. This case report illustrates the benefits of cone beam computed tomography, in terms of treatment planning and surgical technique, to localize a large maxillary odontoma and accurately establish its relationship with the maxillary sinus and molar.

  18. Effects of particle size on the leachability of trace elements

    Energy Technology Data Exchange (ETDEWEB)

    M. Zandi; N.V. Russell; R.G.J. Edyvean; R. Hand; P. Ward [University of Sheffield, Sheffield (United Kingdom). Department of Chemical and Process Engineering

    2007-07-01

    Leaching tests are widely used as indicators to estimate the release potential of hazardous elements from solid materials under laboratory conditions in order to assess environmental impacts of utilisation or deposition of the examined material. Several institutes and agencies have introduced standard leaching tests for estimating the mobility of trace elements from a solid material under specific conditions. These tests are often criticised on the grounds that the results obtained are neither reliable nor able to be extrapolated to the application. The lack of agreement between the estimates by standard leaching tests and measurements in the field may be the result of inadequate specification of the physical and chemical conditions used in the test. For example, in BS EN 12457 the particle size distribution of the sample is not well defined. This can lead to different interpretations by different laboratories resulting in different leaching rates being reported. The lack of understanding of the leaching mechanism leads to the design of poorly defined leaching tests. Therefore, there is a need to have a good understanding of all parameters involved in the leaching process and the factors that affect it. It is known that particle surface area has a great impact on the leachability of trace elements from solid matter. This paper investigates effects of particle size on the leaching process using BS EN 12457-2 conditions. A slag sample from a metal refiner has been crushed and sieved to obtain different fractions with different particle sizes from 4 to 0.5 mm. The leaching rate of trace elements from each fraction has been determined using deionised water as the leachant. It was found that sample preparation procedure is a critical step in leaching analysis and effects of particle size on the leachability should be taken into account. 9 refs., 2 figs., 2 tabs.

  19. High power beam analysis

    Science.gov (United States)

    Aharon, Oren

    2014-02-01

    In various modern scientific and industrial laser applications, beam-shaping optics manipulates the laser spot size and its intensity distribution. However the designed laser spot frequently deviates from the design goal due to real life imperfections and effects, such as: input laser distortions, optical distortion, heating, overall instabilities, and non-linear effects. Lasers provide the ability to accurately deliver large amounts of energy to a target area with very high accuracy. Thus monitoring beam size power and beam location is of high importance for high quality results and repeatability. Depending on the combination of wavelength, beam size and pulse duration , laser energy is absorbed by the material surface, yielding into processes such as cutting, welding, surface treatment, brazing and many other applications. This article will cover the aspect of laser beam measurements, especially at the focal point where it matters the most. A brief introduction to the material processing interactions will be covered, followed by fundamentals of laser beam propagation, novel measurement techniques, actual measurement and brief conclusions.

  20. Proximity effect of electron beam lithography on single-electron transistors

    Indian Academy of Sciences (India)

    Shu-Fen Hu; Kuo-Dong Huang; Yue-Min Wan; Chin-Lung Sung

    2006-07-01

    A simple method, based on the proximity effect of electron beam lithography, alleviated by exposing various shapes in the pattern of incident electron exposures with various intensities, was applied to fabricate silicon point-contact devices. The drain current (d) of the device oscillates against gate voltage. The electrical characteristics of the single-electron transistor were observed to be consistent with the expected behavior of electron transport through gated quantum dots, up to 150 K. The dependence of the electrical characteristics on the dot size reveals that the d oscillation follows from the Coulomb blockade by poly-Si grains in the poly-Si dot. The method of fabrication of this device is completely compatible with complementary metal-oxide-semiconductor technology, raising the possibility of manufacturing large-scale integrated nanoelectronic systems.

  1. Effect of electron beam irradiation on the structure and optical properties of nickel oxide nanocubes

    Indian Academy of Sciences (India)

    P A Sheena; K P Priyanka; N Aloysius Sabu; S Ganesh; Thomas Varghese

    2015-08-01

    This work reports the effect of electron beam (EB) irradiation on the structure and optical properties of nanocrystalline nickel oxide (NiO) cubes. NiO nanocubes were synthesized by the chemical precipitation method. The characterization was carried out by employing analytical techniques like X-ray diffraction, transmission electron microscopy, UV–visible and photoluminescence (PL) spectroscopy. The present investigation found that non-stoichiometry, defects and particle size variation caused by EB irradiation have a great influence on optical band gap, blue shift and band modification of absorption and PL spectra. Moreover, EB irradiation can result enhanced optical absorption performance and photo-activity in NiO nanocubes for optoelectronics and photo-catalytic applications. The study of International Commission on Illumination chromaticity diagram indicates that NiO can be developed as a suitable phosphor material for the application in near ultraviolet excited colour LEDs.

  2. A Study on the Effects of Layout and Material Type of the Middle Layer on Elasticity Module of I-Beams

    Directory of Open Access Journals (Sweden)

    Mahdi Mashmoul

    2016-12-01

    Full Text Available The present study aimed to investigate the effect of layout and material type of the middle layer on elasticity module of I beams made out of PopulusNigra, Plywood, and MDF in three forms of wooden material, zinc-coated sheets and compound materials. In order to in order to make the beams, PopulusNigra of 100 * 6* 4 centimeter size was used in the wings of the beam and the body of the beam was made of plywood, MDF and zinc-coated sheet of 100* 18 centimeter size. Combining the above-mentioned factors, nine treatments were created which were repeated four times and created 36 I beams the elasticity module of which were tested using mechanic al gauging device. Two-factor factorial test was used in a random form of statistical analysis and the means were compared through Duncan’s multiple range test (DMRT. Results revealed that maximum elasticity module was for zinc-coated beams and minimum module was observed in beams made of MDF.

  3. LET effects of high energy ion beam irradiation on polysilanes

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Shu; Kanzaki, Kenichi; Tagawa, Seiichi; Yoshida, Yoichi [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research; Kudoh, Hisaaki; Sugimoto, Masaki; Sasuga, Tsuneo; Seguchi, Tadao; Shibata, Hiromi

    1997-03-01

    Thin films of poly(di-n-hexylsilane) were irradiated with 2-20 MeV H{sup +} and He{sup +} ion beams. The beams caused heterogeneous reactions of crosslinking and main chain scission in the films. The relative efficiency of the crosslinking was drastically changed in comparison with that of main chain scission. The anomalous change in the molecular weight distribution was analyzed with increasing irradiation fluence, and the ion beam induced reaction radius; track radius was determined for the radiation sources by the function of molecular weight dispersion. Obtained values were 59{+-}15 A and 14{+-}6 A for 2 MeV He{sup +} and 20 MeV H{sup +} ion beams respectively. (author)

  4. THE EFFECT OF FLY ASH ON FLEXURAL CAPACITY CONCRETE BEAMS

    Directory of Open Access Journals (Sweden)

    Amir Mohammad Amiri

    2016-06-01

    Full Text Available This paper presents the flexural response of Reinforced Geopolymer Concrete (RGPC beam. A commercial finite element (FE software ABAQUS has been used to perform a structural behavior of RGPC beam. Using parameters such: stress, strain, Young’s modulus, and Poisson’s ratio obtained from experimental results, a beam model has been simulated in ABAQUS. The results from experimental test and ABAQUS simulation were compared. Due to friction forces at the supports and loading rollers; slip occurring, the actual deflection of RGPC beam from experimental test results were slightly different from the results of ABAQUS. And there is good agreement between the crack patterns of fly-ash based geopolymer concrete generated by FE analysis using ABAQUS, and those in experimental data.

  5. Beam steering effects in turbulent high pressure flames

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The propagation of a laser beam through a flame is influenced by variations of the optical density. Especially in turbulent high pressure flames this may seriously limit the use of laser diagnostic methods. (author) 1 fig., 2 refs.

  6. Phase effects due to beam misalignment on diffraction gratings

    CERN Document Server

    Lodhia, Deepali; Brueckner, Frank; Carbone, Ludovico; Fulda, Paul; Kokeyama, Keiko; Freise, Andreas

    2013-01-01

    All-reflective interferometer configurations have been proposed for the next generation of gravitational wave detectors, with diffractive elements replacing transmissive optics. However, an additional phase noise creates more stringent conditions for alignment stability. A framework for alignment stability with the use of diffractive elements was required using a Gaussian model. We successfully create such a framework involving modal decomposition to replicate small displacements of the beam (or grating) and show that the modal model does not contain the phase changes seen in an otherwise geometric planewave approach. The modal decomposition description is justified by verifying experimentally that the phase of a diffracted Gaussian beam is independent of the beam shape, achieved by comparing the phase change between a zero-order and first-order mode beam. To interpret our findings we employ a rigorous time-domain simulation to demonstrate that the phase changes resulting from a modal decomposition are correc...

  7. Evaluation of thermal effects on the beam quality of disk laser with unstable resonator

    Science.gov (United States)

    Shayganmanesh, Mahdi; Beirami, Reza

    2017-01-01

    In this paper thermal effects of the disk active medium and associated effects on the beam quality of laser are investigated. Using Collins integral and iterative method, transverse mode of an unstable resonator including a Yb:YAG active medium in disk geometry is calculated. After that the beam quality of the laser is calculated based on the generalized beam characterization method. Thermal lensing of the disk is calculated based on the OPD (Optical Path Difference) concept. Five factors influencing the OPD including temperature gradient, disk thermal expansion, photo-elastic effect, electronic lens and disk deformation are considered in our calculations. The calculations show that the effect of disk deformation factor on the quality of laser beam in the resonator is strong. However the total effect of all the thermal factors on the internal beam quality is fewer. Also it is shown that thermal effects degrade the output power, beam profile and beam quality of the output laser beam severely. As well the magnitude of each of affecting factors is evaluated distinctly.

  8. 100-nm-size ferroelectric-gate field-effect transistor with 108-cycle endurance

    Science.gov (United States)

    Van Hai, Le; Takahashi, Mitsue; Zhang, Wei; Sakai, Shigeki

    2015-08-01

    The fabrication process of 100-nm-size ferroelectric-gate field-effect transistors (FeFETs) with high endurance was reported. The FeFETs had Pt/Sr0.8Ca0.2Bi2Ta2O9 (SCBT)/HfO2/Si stacks where the Pt gate length was 100 nm. The FeFETs were successfully fabricated by integrating many technologies such as fine patterning of etching masks by electron-beam lithography, precise anisotropic etching of the gate stacks, well-controlled ion implantation for gate-self-aligned sources and drains, and the sidewall-cover process that we had developed. Good performances of the FeFETs were characterized by the endurance of 108 program-and-erase cycles with negligible threshold-voltage shift and good drain-current retention for 3.98 × 105 s.

  9. The effect of nanocrystalline magnetite size on arsenic removal

    Directory of Open Access Journals (Sweden)

    J.T. Mayo et al

    2007-01-01

    Full Text Available Higher environmental standards have made the removal of arsenic from water an important problem for environmental engineering. Iron oxide is a particularly interesting sorbent to consider for this application. Its magnetic properties allow relatively routine dispersal and recovery of the adsorbent into and from groundwater or industrial processing facilities; in addition, iron oxide has strong and specific interactions with both As(III and As(V. Finally, this material can be produced with nanoscale dimensions, which enhance both its capacity and removal. The objective of this study is to evaluate the potential arsenic adsorption by nanoscale iron oxides, specifically magnetite (Fe3O4 nanoparticles. We focus on the effect of Fe3O4 particle size on the adsorption and desorption behavior of As(III and As(V. The results show that the nanoparticle size has a dramatic effect on the adsorption and desorption of arsenic. As particle size is decreased from 300 to 12 nm the adsorption capacities for both As(III and As(V increase nearly 200 times. Interestingly, such an increase is more than expected from simple considerations of surface area and suggests that nanoscale iron oxide materials sorb arsenic through different means than bulk systems. The desorption process, however, exhibits some hysteresis with the effect becoming more pronounced with small nanoparticles. This hysteresis most likely results from a higher arsenic affinity for Fe3O4 nanoparticles. This work suggests that Fe3O4 nanocrystals and magnetic separations offer a promising method for arsenic removal.

  10. Effect of precipitation procedure and detection technique on particle size distribution of CaCO 3

    Science.gov (United States)

    Martos, C.; Coto, B.; Peña, J. L.; Rodríguez, R.; Merino-Garcia, D.; Pastor, G.

    2010-09-01

    The deposition of inorganic salts ("scales") such as calcium carbonate is an important flow assurance problem during crude oil production. The knowledge of the features of the precipitated solids, mainly the particle size and morphology, is crucial to understand the nature of the solids and to avoid or reduce the effect of their deposition. For instance, the use of additives is one of the most usual procedures to mitigate this problem. Additives interact with scale-forming substances either by increasing the induction time, or by inhibiting crystal growth, changing the morphology of solids. In this work, CaCO 3 was precipitated by two different experimental methods: by mixing sodium carbonate and calcium chloride at 25 °C (method 1), and by changing the pH (method 2). Precipitated solids were analyzed by means of the following techniques: laser diffraction (LD), focused-beam reflectance measurement (FBRM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), in order to select a method for the determination of particle size of solids similar to scales, in order to study these deposits at the beginning of their formation and to evaluate the effect of additives in the scales particle size. Results were compared to those of scale deposits extracted from crude oil pipelines. SEM and XRD characterization showed that both the precipitation methods lead to calcium carbonate as a mixture of calcite, aragonite and vaterite, with rhombohedral morphology for method 1 and spherical for method 2. The effects of temperature, kinetics and Mg 2+ presence in the morphology of CaCO 3 were evaluated. Thus, the solids obtained by static bottle test and real scales are mainly formed by long needle-shaped aragonite. The comparison of the several particle size characterization methods determinates that an LD is a fast and sensitive technique for spherical and non-spherical solids, and it is a convenient technique for the analysis of scales extracted from oil pipelines.

  11. Rolling induced size effects in elastic–viscoplastic sheet metals

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    2015-01-01

    Rolling processes for which the characteristic length scale reaches into the range where size effects become important are receiving increased interest. In particularly, this is owed to the roll-molding process under development for high-throughput of micron-scale surface features. The study...... presented revolves around the rolling induced effect of visco-plasticity (ranging hot and cold rolling) in combination with strain gradient hardening – including both dissipative and energetic contributions. To bring out first order effects on rolling at small scale, the modeling efforts are limited to flat...... sheet rolling, where a non-homogeneous material deformation takes place between the rollers. Large strain gradients develop where the rollers first come in contact with the sheet, and a higher order plasticity model is employed to illustrate their influence at small scales. The study reveals...

  12. The flexoelectric effect associated size dependent pyroelectricity in solid dielectrics

    Directory of Open Access Journals (Sweden)

    Gang Bai

    2015-09-01

    Full Text Available A phenomenological thermodynamic theory is used to investigate the effect of strain gradient on the pyroelectric effect in centrosymmetric dielectric solids. Direct pyroelectricity can exist as external mechanical stress is applied to non-pyroelectric dielectrics with shapes such as truncated pyramids, due to elastic strain gradient induced flexoelectric polarization. Effective pyroelectric coefficient was analyzed in truncated pyramids. It is found to be controlled by size, ambient temperature, stress, and aspect ratio and depends mainly on temperature sensitivity of flexoelectric coefficient (TSFC and strain gradient of the truncated pyramids dielectric solids. These results show that the pyroelectric property of Ba0.67Sr0.33TiO3 above Tc similar to PZT and other lead-based ferroelectrics can be obtained. This feature might widely broaden the selection of materials for infrared detectors with preferable properties.

  13. The flexoelectric effect associated size dependent pyroelectricity in solid dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Gang, E-mail: baigang@njupt.edu.cn [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Liu, Zhiguo [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Xie, Qiyun; Guo, Yanyan; Li, Wei [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Yan, Xiaobing [College of Electronic and information Engineering, Hebei University, Baoding 071002 (China)

    2015-09-15

    A phenomenological thermodynamic theory is used to investigate the effect of strain gradient on the pyroelectric effect in centrosymmetric dielectric solids. Direct pyroelectricity can exist as external mechanical stress is applied to non-pyroelectric dielectrics with shapes such as truncated pyramids, due to elastic strain gradient induced flexoelectric polarization. Effective pyroelectric coefficient was analyzed in truncated pyramids. It is found to be controlled by size, ambient temperature, stress, and aspect ratio and depends mainly on temperature sensitivity of flexoelectric coefficient (TSFC) and strain gradient of the truncated pyramids dielectric solids. These results show that the pyroelectric property of Ba{sub 0.67}Sr{sub 0.33}TiO{sub 3} above T{sub c} similar to PZT and other lead-based ferroelectrics can be obtained. This feature might widely broaden the selection of materials for infrared detectors with preferable properties.

  14. Finite-size effects in amorphous indium oxide

    Science.gov (United States)

    Mitra, Sreemanta; Tewari, Girish C.; Mahalu, Diana; Shahar, Dan

    2016-04-01

    We study the low-temperature magnetotransport properties of several highly disordered amorphous indium oxide (a:InO) samples. Simultaneously fabricated devices comprising a two-dimensional (2D) film and 10 -μ m -long wires of different widths were measured to investigate the effect of size as we approach the 1D limit, which is around 4 times the correlation length, and happens to be around 100 nm for a:InO. The film and the wires showed magnetic field (B )-induced superconductor to insulator transition (SIT). In the superconducting side, the resistance increased with decrease in wire width, whereas an opposite trend is observed in the insulating side. We find that this effect can be explained in light of charge-vortex duality picture of the SIT. Resistance of the 2D film follows an activated behavior over the temperature (T ), whereas, the wires show a crossover from the high-T -activated to a T -independent behavior. At high-temperature regime the wires' resistance follow the film's until they deviate and became independent of T . We find that the temperature at which this deviation occurs evolves with the magnetic field and the width of the wire, which show the effect of finite size on the transport.

  15. Why herd size matters - mitigating the effects of livestock crashes.

    Directory of Open Access Journals (Sweden)

    Marius Warg Næss

    Full Text Available Analysing the effect of pastoral risk management strategies provides insights into a system of subsistence that have persevered in marginal areas for hundreds to thousands of years and may shed light into the future of around 200 million households in the face of climate change. This study investigated the efficiency of herd accumulation as a buffer strategy by analysing changes in livestock holdings during an environmental crisis in the Saami reindeer husbandry in Norway. We found a positive relationship between: (1 pre- and post-collapse herd size; and (2 pre-collapse herd size and the number of animals lost during the collapse, indicating that herd accumulation is an effective but costly strategy. Policies that fail to incorporate the risk-beneficial aspect of herd accumulation will have a limited effect and may indeed fail entirely. In the context of climate change, official policies that incorporate pastoral risk management strategies may be the only solution for ensuring their continued existence.

  16. Size-effects in plane strain sheet-necking

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Redanz, Pia

    2003-01-01

    are analyzed. The strain gradient plasticity theory predicts delayed onset of localization when compared to conventional theory, and it depresses deformation localization in the neck. The sensitivity to imperfections is analyzed as well as differently hardening materials.......A finite strain generalization of the strain gradient plasticity theory by Fleck and Hutchinson (2001) is proposed and used to study size effects in plane strain necking of thin sheets using the finite element method. Both sheets with rigid grips at the ends and specimens with shear free ends...

  17. Size-effects in plane strain sheet-necking

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Redanz, Pia

    2004-01-01

    and specimens with shear free ends are analyzed. The strain gradient plasticity theory predicts delayed onset of localization when compared to conventional theory, and it depresses deformation localization in the neck. The sensitivity to imperfections is analyzed as well as differently hardening materials. (C......A finite strain generalization of the strain gradient plasticity theory by Fleck and Hutchinson (J. Mech. Phys. Solids 49 (2001a) 2245) is proposed and used to study size effects in plane strain necking of thin sheets using the finite element method. Both sheets with rigid grips at the ends...

  18. Effect Sizes for Research Univariate and Multivariate Applications

    CERN Document Server

    Grissom, Robert J

    2011-01-01

    Noted for its comprehensive coverage, this greatly expanded new edition now covers the use of univariate and multivariate effect sizes. Many measures and estimators are reviewed along with their application, interpretation, and limitations. Noted for its practical approach, the book features numerous examples using real data for a variety of variables and designs, to help readers apply the material to their own data. Tips on the use of SPSS, SAS, R, and S-Plus are provided. The book's broad disciplinary appeal results from its inclusion of a variety of examples from psychology, medicine, educa

  19. Effect of filler size on wear resistance of resin cement.

    Science.gov (United States)

    Shinkai, K; Suzuki, S; Katoh, Y

    2001-11-01

    The purpose of this study was to evaluate the effect of filler size on the wear of resin cements. Materials tested included four experimental dual-cure resin cements (Kuraray) consisting of different-sized filler particles. A rectangular box cavity was prepared on the flattened occlusal surface of extracted human molars. Ceramic inlays for the cavities were fabricated using the Cerec 2 system. The Cerec inlays were cemented with the respective cements and adhesive systems according to the manufacturer's directions. The restored surface was finished by wet-grinding with an 800-grit silicon carbide paper. Six specimens were prepared for each resin cement. Half of the specimens were subjected to a three-body wear test for 200,000 cycles, and the others were subjected to a toothbrush abrasion test for 30,000 cycles. The worn surface of each restoration was scanned by a profilometer (Surfcom 475 A) at eight different points for each restoration. The wear value was determined by measuring the vertical gap depth on the profilometric tracings. The data were statistically analyzed by one-way analysis of variance (ANOVA) and Scheffe's test. The results showed that, with increase of filler size, the wear value decreased in the toothbrush test and increased in the three-body wear test. The cement with 0.04-microm filler exhibited the lowest wear value among the materials in the three-body wear test, and the same wear value as the cement with 0.97-microm filler in the toothbrush test. Based upon the results of this study, it is concluded that the wear of resin cements was affected by the filler size as well as the mode of wear test.

  20. Transport, retention, and size perturbation of graphene oxide in saturated porous media: Effects of input concentration and grain size

    Science.gov (United States)

    Accurately predicting the fate and transport of graphene oxide (GO) in porous media is critical to assess its environmental impact. In this work, sand column experiments were conducted to determine the effect of input concentration and grain size on transport, retention, and size perturbation of GO ...

  1. Effect of shape of elastic beam hair on its adhesion with wavy surfaces

    Science.gov (United States)

    Hemthavy, Pasomphone; Yazaki, Takehiko; Wang, Boqing; Sekiguchi, Yu; Takahashi, Kunio

    2014-08-01

    An analysis on a tapered elastic beam whose side surface partially adhered to a rigid surface was carried out to study the effect of the beam shape on the gripping force. Considering the total energy of the system, the relation between the gripping force and the displacement was obtained analytically in closed form. The analytical result is significant because it provides an intuitive picture of the gripping force. Although, an individually tapered beam can generate less gripping force for flat or slightly wavy surfaces, compared to a rectangular beam, the analysis result suggests that the tapered beam has more ability to absorb surface waviness. This result can be applied to a multi-beam structure.

  2. Application of nonlocal models to nano beams. Part I: Axial length scale effect.

    Science.gov (United States)

    Kim, Jun-Sik

    2014-10-01

    Applicability of nonlocal models to nano-beams is discussed in terms of physical implications via the similarity between a nonlocal Euler-Bernoulli (EB) beam theory and a classical Rankine-Timoshenko (RT) beam theory. The nonlocal EB beam model, Eringen's model, is briefly reviewed and the classical RT beam theory is recast by the primary variables of the EB model. A careful comparison of these two models reveals that the scale parameter used to the Eringen's model has a strike resemblance to the shear flexibility in the RT model. This implies that the nonlocal model employed in literature consider the axial length scale effect only. In addition, the paradox for a cantilevered nano-beam subjected to tip shear force is clearly explained by finding appropriate displacement prescribed boundary conditions.

  3. Electron-beam curing of epoxy resins: effect of alcohols on cationic polymerization

    Indian Academy of Sciences (India)

    N N Ghosh; G R Palmese

    2005-10-01

    Electron-beam (e-beam) induced polymerization of epoxy resins proceeds via cationic mechanism in presence of suitable photoinitiator. Despite good thermal properties and significant processing advantages, epoxy-based composites manufactured using e-beam curing suffer from low compressive strength, poor interlaminar shear strength, and low fracture toughness. A detailed understanding of the reaction mechanism involving e-beam induced polymerization is required to properly address the shortcomings associated with ebeam curable resin systems. This work investigated the effect of hydroxyl containing materials on the reaction mechanism of e-beam induced cationic polymerization of phenyl glycidyl ether (PGE). The alcohols were found to play important roles in polymerization. Compared to hydroxyl group of aliphatic alcohol, phenolic hydroxyl group is significantly less reactive with the oxonium active centre, generated during e-beam induced polymerization of epoxy resin system.

  4. Full characterization of a high-power semiconductor disk laser beam with simultaneous capture of optimally sized focus and farfield.

    Science.gov (United States)

    Borgentun, Carl; Bengtsson, Jörgen; Larsson, Anders

    2011-04-20

    We report on a beam characterization method that is based on the simultaneous measurement of the focus field and the farfield, thus avoiding problems with beam fluctuations during the measurement. By using reflections from both sides of a planoconvex lens, the method implements two branches of an optical system working simultaneously. Also, by letting the planoconvex lens be antireflection treated, and by allowing for both of the reflected fields to fill large and approximately equal areas on a camera detector array, the method significantly lowers the intensity onto the detector array, thus minimizing the need for additional disturbing attenuation filters to avoid camera saturation. In the numerical retrieval of the phase distribution, based on the measured intensity distributions of the focus and farfield, iterative propagation between the two branches is performed. The phase retrieval uses the two-step algorithm for the numerical field propagation conveniently providing an arbitrary choice of sampling distance in each plane.

  5. Polarization of a probe laser beam due to nonlinear QED effects

    Science.gov (United States)

    Shakeri, Soroush; Kalantari, Seyed Zafarollah; Xue, She-Sheng

    2017-01-01

    Nonlinear QED interactions induce different polarization properties on a given probe beam. We consider the polarization effects caused by the photon-photon interaction in laser experiments, when a laser beam propagates through a constant magnetic field or collides with another laser beam. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian for both time-dependent and constant background field to explore the time evolution of the Stokes parameters Q, U, and V describing polarization. Assuming an initially linearly polarized probe laser beam, we also calculate the induced ellipticity and rotation of the polarization plane.

  6. Charge Stripper Effects on Beam Optics in 180-degree Bending Section of RISP Linac

    CERN Document Server

    Jang, Ji-Ho; Song, Jeong Seog

    2016-01-01

    The RAON, a superconducting linear accelerator for RISP (Rare Isotope Science Project), will use a charge stripper in order to increase the charge states of the heavy ions for effective acceleration in the higher energy part of the linac. The charge stripper affects the beam qualities by scattering when the heavy ions go through the charge stripper. Moreover we have to select and accelerate proper charge states between 77+ and 81+ for uranium beam case in order to satisfy the beam power requirement at an IF (Inflight Fragmentation) target. This work focuses on the beam optics affected by the charge stripper in the 180-dgree bending section.

  7. FLEXURAL VIBRATIONS BAND GAPS IN PERIODIC BEAMS INCLUDING ROTARY INERTIA AND SHEAR DEFORMATION EFFECTS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    With the idea of the phononic crystals, the beams with periodic structure are designed.Flexural vibration through such periodic beams composed of two kinds of materials is studied. The emphasis is laid on the effects of rotary inertia and shear deformation. Based on the vibration equation, plane wave expansion method is provided. The acceleration frequency responses of such beams with finite structure are simulated by the finite element method. The frequency ranges of sharp drops in the calculated acceleration frequency response curves are in good agreement with those in the band structures. The findings will be significant in the application of the periodic beams.

  8. On the effect of shear coefficients in free vibration analysis of curved beams

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Gon; Lee, Jae Kon; Yoon, Hyun Joong [Catholic University of Daegu, Daegu (Korea, Republic of)

    2014-08-15

    We did a comparative study of shear coefficients in free vibration analysis of curved beams having circular and rectangular cross sections. Until recently, the shear coefficient k in Timoshenko beam theory has been studied by many researchers to include transverse shear deformation effect. To obtain more reliable numerical results, a higher-order hybrid-mixed curved beam element is formulated and programmed in MATLAB. The present numerical experiments show that k = 6(1+v){sup 2}/(7+12v+4v{sup 2}) is the best expression both for circular and rectangular cross-sections in the flexural vibration of curved beams.

  9. Material length scales in gradient-dependent plasticity/damage and size effects: Theory and computation

    Science.gov (United States)

    Abu Al-Rub, Rashid Kamel

    the interpretation of indentation size effects in micro/nano-hardness when using pyramidal and spherical indenters and gives sound interpretations of the size effects in micro-torsion of thin wires and micro-bending of thin beams. Future studies should be directed toward incorporation of the size effects into design procedures and code recommendations of modern engineering structures (e.g. for MEMS, NEMS, coatings, thin films), fiber composites (e.g. for aircrafts and ships), etc.

  10. Effects of reconstruction parameters on image noise and spatial resolution in cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Wan; Lee, Chang-Lae; Cho, Hyo-Min; Park, Hye-Suk; Kim, Dae-Hong; Choi, Yu-Na; Kim, Hee-Joung [Yonsei University, Wonju (Korea, Republic of)

    2011-10-15

    CBCT (cone-beam computed tomography) is a promising modality in many medical applications due to the properties of fast volume coverage, lower radiation dose, easy hardware implementation, and higher spatial resolution. Recently, attention is being paid to the noise and resolution relationship for CBCT. In a CBCT system, image noise and spatial resolution play very important roles in image quality. However, there have not been many works to evaluate the relationship between the image noise and the spatial resolution in CBCT. In this study, we evaluated the effects of reconstruction parameters, such as the characteristics of the filter, the number of projections, and the voxel size, on the image noise and the spatial resolution in a CBCT system. The simulated projection data of a Catphan 600 phantom were reconstructed using the FDK (Feldkamp) algorithm. To evaluate the image noise and the spatial resolution, we calculated the COV (coefficient of variation) of the attenuation coefficient and the MTF (modulation transfer function) in axial images. Five reconstruction filters, Ram-Lak, Shepp-Logan, Cosine, Hamming, and Hann, were used to reconstruct the images. Different numbers of projections for a circular scan of 360 degrees and different voxel sizes were used to reconstruct the images to evaluate their effect on image noise and spatial resolution. The image noise given by the Hann filter was the lowest and the spatial resolution given by the Ram-Lak filter was the highest. The image noise was decreased as functions of the number of projections and the voxel size. The spatial resolution was increased as a function of the number of projections and decreased as a function of the voxel size. The results of this study show the relationship between the image noise and the spatial resolution in a CBCT system and the characteristics of the reconstruction factors for trade-off between the image noise and the spatial resolution. It can also provide information of the image

  11. Effect of body size on toxicity of zinc in neonates of four differently sized Daphnia species

    NARCIS (Netherlands)

    Vesela, S.; Vijverberg, J.

    2007-01-01

    The sensitivity of neonates of four Daphnia species to zinc was tested in relation to their mean body size. These mean sizes of these four Daphnia spp were: D. magna, 0.813 ± 0.055 mm, D.␣pulicaria, 0.745 ± 0.063 mm, D. pulex, 0.645 ± 0.044 mm and D. galeata, 0.611 ± 0.058 mm. A positive relationshi

  12. Effects of Kurozu concentrated liquid on adipocyte size in rats

    Directory of Open Access Journals (Sweden)

    Nakamura Kumi

    2010-11-01

    Full Text Available Abstract Background Kurozu concentrated liquid (KCL is used as a health-promoting supplement for the treatment of disorders such as cancer, hyperlipidemia, and hypertension in Japan. We investigated the possible anti-obesity effects of KCL in rats. Methods Male Sprague Dawley rats were fed American Institute of Nutrition 76 formula diet and were orally administrated KCL or acetic acid at a dose of 100 mg/kg body weight or deionized water for 4 weeks. Adipocyte size, DNA content in subcutaneous adipose tissue, lipid levels in the serum and liver, and the rate of fatty acid excretion were determined. Effects of KCL on pancreatic lipase activity and 3T3-L1 preadipocyte differentiation were investigated in vitro. Results In the KCL group, the average adipocyte size in subcutaneous and perirenal adipose tissues was significantly reduced. The KCL-administered rats displayed greater numbers of small adipocytes in the subcutaneous, perirenal and mesenteric adipose tissues than did rats from the other groups. In the KCL group, the DNA content in subcutaneous adipose tissue was significantly increased. The rate of fatty acid excretion was significantly increased in the KCL group. Furthermore, KCL significantly inhibited pancreatic lipase activity in vitro, and also significantly inhibited fat accumulation and mRNA expression of fatty acid binding protein 2 (aP2 and peroxisome proliferator-activated γ (PPARγ in 3T3-L1 preadipocyte. The levels of serum and liver lipids, the concentration of serum glucose, and the levels of adiponectin were similar among the 3 groups. Conclusion Oral administration of KCL decreases the adipocyte size via inhibition of dietary fat absorption and reductions of PPARγ and aP2 mRNA expression levels in adipocytes.

  13. Effects of corm size and storage period on allocation

    Directory of Open Access Journals (Sweden)

    mehdi nasiry mahalati

    2009-06-01

    Full Text Available In order to correlate corm size and storage period of corms to allocation of assimilates in different parts of the plant an experiment was conducted during growth period of 2004 and 2005 in Faculty of Agriculture, Ferdowsi University of Mashhad. Treatments were four groups of corm size (3-6, 6-9, 9-12 and 12-15 g either stored for a period of time before planting or sown directly without storage. Experiment was conducted in a Complete Randomized Block design with three replications. Results indicated that storing corms before planting had a negative effect on number, area, length and width of leaf and also on weight of leaf, weight of main shoot, weight of leaves of lateral shoots and total weight of plant. However, weight of corm, number and weight of lateral shoots and area of lateral leaf was not affected by storing the corms. Nevertheless, in the second year, number, length and weight of leaf on main shoot, number of cormlet, number, area and weight of leaf on lateral shoots, total weight of plant, corm weight, weight of main shoot and weight of lateral buds was reduced while leaf width were not affected. Effect of corm size on almost all measured parameters was positive and with increasing corm weight an increasing trend was observed in the above parameters. No flower was observed on corms which were stored, while corms which planted after lifting produced flowers and Larger corms of 9-12 and 12-15 g were superior in terms of number of flowers per unit area and also weight of flower and stigma per unit area. Corms with 9-15 grams planted immediately after lifting the corms produced higher yield.

  14. Junction size dependence of ferroelectric properties in e-beam patterned BaTiO{sub 3} ferroelectric tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Singh, A. V.; Gupta, A. [Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Althammer, M. [Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Walther-Meissner-Institut, Bayerische Akdademie der Wissenschaften, Garching 85748 (Germany); Rott, K.; Reiss, G. [Thin Films and Physics of Nanostructures, Department of Physics and Center for Spinelectronic Materials and Devices, Bielefeld University, Bielefeld 33615 (Germany)

    2015-09-21

    We investigate the switching characteristics in BaTiO{sub 3}-based ferroelectric tunnel junctions patterned in a capacitive geometry with circular Ru top electrode with diameters ranging from ∼430 to 2300 nm. Two different patterning schemes, viz., lift-off and ion-milling, have been employed to examine the variations in the ferroelectric polarization, switching, and tunnel electro-resistance resulting from differences in the pattering processes. The values of polarization switching field are measured and compared for junctions of different diameter in the samples fabricated using both patterning schemes. We do not find any specific dependence of polarization switching bias on the size of junctions in both sample stacks. The junctions in the ion-milled sample show up to three orders of resistance change by polarization switching and the polarization retention is found to improve with increasing junction diameter. However, similar switching is absent in the lift-off sample, highlighting the effect of patterning scheme on the polarization retention.

  15. Correlation-induced self-focusing and self-shaping effect of a partially coherent beam

    Institute of Scientific and Technical Information of China (English)

    Yahong Chen; Yangjian Cai

    2016-01-01

    A new specially correlated partially coherent beam named nonuniform multi-Gaussian correlated(NMGC) partially coherent beam is introduced. The correlation functions of such beam in x and y directions are different from each other,i.e., nonuniform correlation function in one direction and multi-Gaussian correlated Schell-model function in the other direction. The propagation properties of an NMGC partially coherent beam in free pace are demonstrated, and we find that the intensity distribution of such beam exhibits self-focusing and self-shifting effect in one direction and self-shaping effect in the other direction on propagation. The correlation-induced self-focusing and self-shaping effect will be useful in some applications, where the high power and shaped laser is required, such as material thermal processing and laser carving.

  16. Laser Plasmas : Effect of rippled laser beam on excitation of ion acoustic wave

    Indian Academy of Sciences (India)

    Nareshpal Singh Saini; Tarsem Singh Gill

    2000-11-01

    Growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam in collisional unmagnetised plasma is investigated. From numerical computation, it is observed that self-focusing of main beam as well as ripple determine the growth dynamics of ripple with the distance of propagation. The effect of growing ripple on excitation of ion acoustic wave (IAW) has also been studied

  17. Size effects in MgO cube dissolution.

    Science.gov (United States)

    Baumann, Stefan O; Schneider, Johannes; Sternig, Andreas; Thomele, Daniel; Stankic, Slavica; Berger, Thomas; Grönbeck, Henrik; Diwald, Oliver

    2015-03-10

    Stability parameters and dissolution behavior of engineered nanomaterials in aqueous systems are critical to assess their functionality and fate under environmental conditions. Using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we investigated the stability of cubic MgO particles in water. MgO dissolution proceeding via water dissociation at the oxide surface, disintegration of Mg(2+)-O(2-) surface elements, and their subsequent solvation ultimately leads to precipitation of Mg(OH)2 nanosheets. At a pH ≥ 10, MgO nanocubes with a size distribution below 10 nm quantitatively dissolve within few minutes and convert into Mg(OH)2 nanosheets. This effect is different from MgO cubes originating from magnesium combustion in air. With a size distribution in the range 10 nm ≤ d ≤ 1000 nm they dissolve with a significantly smaller dissolution rate in water. On these particles water induced etching generates (110) faces which, above a certain face area, dissolve at a rate equal to that of (100) planes.1 The delayed solubility of microcrystalline MgO is attributed to surface hydroxide induced self-inhibition effects occurring at the (100) and (110) microplanes. The present work underlines the importance of morphology evolution and surface faceting of engineered nanomaterials particles during their dissolution.

  18. Cost-effective unilateral climate policy design: Size Matters

    Energy Technology Data Exchange (ETDEWEB)

    Boehringer, Christoph; Fischer, Carolyn; Rosendahl, Knut Einar

    2011-07-01

    Given the bleak prospects for a global agreement on mitigating climate change, pressure for unilateral abatement is increasing. A major challenge is emissions leakage. Border carbon adjustments and output-based allocation of emissions allowances can increase effectiveness of unilateral action but introduce distortions of their own. We assess antileakage measures as a function of abatement coalition size. We first develop a partial equilibrium analytical framework to see how these instruments affect emissions within and outside the coalition. We then employ a computable general equilibrium model of international trade and energy use to assess the strategies as the coalition grows. We find that full border adjustments rank first in global cost-effectiveness, followed by import tariffs and output-based rebates. The differences across measures and their overall appeal decline as the abatement coalition grows. In terms of cost, the coalition countries prefer border carbon adjustments; countries outside the coalition prefer output-based rebates.(Author)

  19. Effect Size: A guide for researchers and users

    Directory of Open Access Journals (Sweden)

    Robert Coe

    2003-06-01

    Full Text Available The present article describes a method to quantify the magnitude of the differences between two measures and/or the degree of the effect of a variable about criteria, and it is named likethe effect size measure, d. Use it use in research and applied contexts provides a quitedescriptive complementary information, improving the interpretation of the results obtained bythe traditional methods that emphasize the statistical significance. Severa forms there are of interpreting the d, and an example taken of an experimental research, is presented to clarify the concepts and necessary calculations. This method is not robust to sorne conditions that they candistort its interpretation, for example, the non normality of the data; alternative methods are mentioned to the statistical d. We ending with sorne conclusions that will notice about the appropriate use of it.

  20. Computation of Effect Size for Moderating Effects of Categorical Variables in Multiple Regression

    Science.gov (United States)

    Aguinis, Herman; Pierce, Charles A.

    2006-01-01

    The computation and reporting of effect size estimates is becoming the norm in many journals in psychology and related disciplines. Despite the increased importance of effect sizes, researchers may not report them or may report inaccurate values because of a lack of appropriate computational tools. For instance, Pierce, Block, and Aguinis (2004)…

  1. Influence of the transverse beam sizes on the ep -> ep. gamma. cross section at the HERA and a FUTURE CERN electron-proton collider

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L.; Polityko, S.I.; Serbo, V.G.; Schiller, A.

    1988-06-01

    In the process ep -> ep..gamma.., proposed for luminosity measurements at HERA, impact parameters occur which are larger than the transverse beam sizes in the ep-colliders in HERA and a CERN option (LHC+LEP). This decreases the number of observed photons compared to the standard QED calculation. The difference is larger than 10% at photon energies E/sub ..gamma../ < 0.4E/sub e/ for the CERN option and E/sub ..gamma../ < 0.01E/sub e/ for HERA. (orig.)

  2. Analysis of beam plasma instability effects on incoherent scatter spectra

    Directory of Open Access Journals (Sweden)

    M. A. Diaz

    2010-12-01

    Full Text Available Naturally Enhanced Ion Acoustic Lines (NEIALs detected with Incoherent Scatter Radars (ISRs can be produced by a Langmuir decay mechanism, triggered by a bump on tail instability. A recent model of the beam-plasma instability suggests that weak-warm beams, such those associated with NEIAL events, might produce Langmuir harmonics which could be detected by a properly configured ISR. The analysis performed in this work shows that such a beam-driven wave may be simultaneously detected with NEIALs within the baseband signal of a single ISR. The analysis shows that simultaneous detection of NEIALs and the first Langmuir harmonic is more likely than simultaneous detection of NEIALs and enhanced plasma line. This detection not only would help to discriminate between current NEIAL models, but could also aid in the parameter estimation of soft precipitating electrons.

  3. Accuracy in the diagnosis of vertical root fractures, external root resorptions, and root perforations using cone-beam computed tomography with different voxel sizes of acquisition

    Science.gov (United States)

    Bragatto, Fernanda Paula; Iwaki Filho, Liogi; Kasuya, Amanda Vessoni Barbosa; Chicarelli, Mariliani; Queiroz, Alfredo Franco; Takeshita, Wilton Mitsunari; Iwaki, Lilian Cristina Vessoni

    2016-01-01

    Aim: The aim of this study is to assess the accuracy of images acquired with cone-beam computed tomography (CBCT) in the identification of three different root alterations. Materials and Methods: Forty human premolars were allocated to four experimental groups (n = 10): sound teeth (control), vertical root fracture (VRF), external root resorption (ERR), and root perforation (RP). After the root alterations had been produced, four teeth were randomly assembled into 10 macerated mandibles and submitted to CBCT. Images were acquired with five voxel sizes (0.125, 0.200, 0.250, 0.300, and 0.400 mm) and assessed by three experienced dental radiologists. Sensitivity, specificity, positive and negative predictive values, and the areas under the receiver operating characteristic curve (accuracy) were calculated. The accuracy of imaging in different voxel sizes was compared with Tukey exact binomial test (α=5%). Results: Accuracy with voxel sizes 0.125, 0.200, and 0.250 mm was significantly higher in the detection of ERRs and VRFs than voxel sizes 0.300 and 0.400 mm. No statistical difference was found in terms of accuracy among any of the studied voxel sizes in the identification of RPs. Conclusions: Voxel size 0.125 mm produced images with the best resolution without increasing radiation levels to the patient when compared to voxel sizes 0.200 and 0.250 mm. Voxel sizes 0.300 and 0.400 mm should be avoided in the identification of root alterations. PMID:27994322

  4. A preliminary study of material homogeneity for size effect investigations

    Energy Technology Data Exchange (ETDEWEB)

    Krompholz, K.; Kamber, J.; Kalkhof, D.

    1999-06-01

    The forged material 20 MnMoNi 55, material number 1.6310 (heat number 69906) with a heat treatment of 900 {sup o}C, water quenched, 730 {sup o}C, air cooled, was subjected to an intensive quality control consisting of chemical analysis, metallography, hardness tests, tensile tests, and impact tests. Six plates of the material were investigated, and all specimens were taken from a diagonal of each plate in three positions, outer margins and the centre of the plates. The quality control exhibits the following results: (1) The material fulfill the material specification in all respects. (2) This material is a fine grained homogeneous ferritic material of bainitic structure; neither from the chemical analysis, metallography, nor from hardness tests influences from the position of the specimens taken from the plates could be derived. (3) The tensile tests clearly revealed position dependent material properties. With the exception of one plate, one of the selected positions exhibits no natural yield strength, higher rupture strength, and lower elongation to fracture compared with the other two positions at 293 K and 573 K. (4) Many of the data obtained from the impact tests at room temperature were larger than the capacity of the impact machine, i.e. 225 Joule; the experimental condition was changed from tests at 573 K to tests at 253 K to obtain data from the transition region. The main conclusions drawn for the size effect experiments where that all the tensile test results for different specimen sizes have to be discussed with respect of the specimen positions within the plates, and that for all bend bar as well as impact experiments with different specimen sizes the notch depth to specimen width ratio a/w has to be changed from a/w = 0.2 to a/w = 0.3 to get reasonable results within the frame of the available test equipment. (author)

  5. On the Effect of Functionally Graded Materials on Resonances of Rotating Beams

    Directory of Open Access Journals (Sweden)

    Arnaldo J. Mazzei Jr.

    2012-01-01

    Full Text Available Radially rotating beams attached to a rigid stem occur in several important engineering applications. Some examples include helicopter blades, turbine blades and certain aerospace applications. In most studies the beams have been treated as homogeneous. Here, with a goal of system improvement, non-homogeneous beams made of functionally graded materials are explored. The effects on the natural frequencies of the system are investigated. Euler-Bernoulli theory, including an axial stiffening effect and variations of both Young's modulus and density, is employed. An assumed mode approach is utilized, with the modes taken to be beam characteristic orthogonal polynomials. Results are obtained via Rayleigh-Ritz method and are compared for both the homogeneous and non-homogeneous cases. It was found, for example, that allowing Young's modulus and density to vary by approximately 2.15 and 1.15 times, respectively, leads to an increase of 23% in the lowest bending rotating natural frequency of the beam.

  6. Effects of size and interactions on the magnetic behaviour of elliptical (0 0 1)Fe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, M. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)]. E-mail: maj.hanson@fy.chalmers.se; Brucas, R. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Kazakova, O. [National Physical Laboratory, TW11 0LW Teddington, Middlesex (United Kingdom)

    2007-09-15

    Arrays of elliptical particles with aspect ratio 1:3 and short axes 50, 100 and 150 nm were prepared by electron-beam lithography and ion-beam milling of epitaxial (0 0 1)Fe films of thicknesses 10 and 20 nm. The domain state of an individual particle imaged by magnetic force microscopy in zero field after demagnetization was observed to change from being bi-domain or multidomain (MD) to stable single domains (SD) as the lateral size and film thickness were decreased. The critical size for SD formation was found to be close to the actual lateral sizes of 100 nmx300 nm and 150 nmx450 nm for the thicknesses of 20 and 10 nm, respectively. Only in the 10 nm thick ellipses of lateral size 100 nmx300 nm, the magnetization reversal may take place through coherent rotation. For all other investigated samples, the experimental switching field is lower than what would be required for this process.

  7. Nanometer-Size Effect on Hydrogen Sites in Palladium Lattice.

    Science.gov (United States)

    Akiba, Hiroshi; Kofu, Maiko; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Ikeda, Kazutaka; Otomo, Toshiya; Yamamuro, Osamu

    2016-08-17

    Nanometer-sized materials attract much attention because their physical and chemical properties are substantially different from those of bulk materials owing to their size and surface effects. In this work, neutron powder diffraction experiments on the nanoparticles of palladium hydride, which is the most popular metal hydride, have been performed at 300, 150, and 44 K to investigate the positions of the hydrogen atoms in the face-centered cubic (fcc) lattice of palladium. We used high-quality PdD0.363 nanocrystals with a diameter of 8.0 ± 0.9 nm. The Rietveld analysis revealed that 30% of D atoms are located at the tetrahedral (T) sites and 70% at the octahedral (O) sites. In contrast, only the O sites are occupied in bulk palladium hydride and in most fcc metal hydrides. The temperature dependence of the T-site occupancy suggested that the T-sites are occupied only in a limited part, probably in the subsurface region, of the nanoparticles. This is the first study to determine the hydrogen sites in metal nanoparticles.

  8. Atomic size effects studied by transport in single silicide nanowires

    Science.gov (United States)

    Miccoli, I.; Edler, F.; Pfnür, H.; Appelfeller, S.; Dähne, M.; Holtgrewe, K.; Sanna, S.; Schmidt, W. G.; Tegenkamp, C.

    2016-03-01

    Ultrathin metallic silicide nanowires with extremely high aspect ratios can be easily grown, e.g., by deposition of rare earth elements on semiconducting surfaces. These wires play a pivotal role in fundamental research and open intriguing perspectives for CMOS applications. However, the electronic properties of these one-dimensional systems are extremely sensitive to atomic-sized defects, which easily alter the transport characteristics. In this study, we characterized comprehensively TbSi2 wires grown on Si(100) and correlated details of the atomic structure with their electrical resistivities. Scanning tunneling microscopy (STM) as well as all transport experiments were performed in situ using a four-tip STM system. The measurements are complemented by local spectroscopy and density functional theory revealing that the silicide wires are electronically decoupled from the Si template. On the basis of a quasiclassical transport model, the size effect found for the resistivity is quantitatively explained in terms of bulk and surface transport channels considering details of atomic-scale roughness. Regarding future applications the full wealth of these robust nanostructures will emerge only if wires with truly atomically sharp interfaces can be reliably grown.

  9. Nosewitness Identification: Effects of Lineup Size and Retention Interval

    Science.gov (United States)

    Alho, Laura; Soares, Sandra C.; Costa, Liliana P.; Pinto, Elisa; Ferreira, Jacqueline H. T.; Sorjonen, Kimmo; Silva, Carlos F.; Olsson, Mats J.

    2016-01-01

    Although canine identification of body odor (BO) has been widely used as forensic evidence, the concept of nosewitness identification by human observers was only recently put to the test. The results indicated that BOs associated with male characters in authentic crime videos could later be identified in BO lineup tests well above chance. To further evaluate nosewitness memory, we assessed the effects of lineup size (Experiment 1) and retention interval (Experiment 2), using a forced-choice memory test. The results showed that nosewitness identification works for all lineup sizes (3, 5, and 8 BOs), but that larger lineups compromise identification performance in similarity to observations from eye- and earwitness studies. Also in line with previous eye- and earwitness studies, but in disagreement with some studies on odor memory, Experiment 2 showed significant forgetting between shorter retention intervals (15 min) and longer retention intervals (1-week) using lineups of five BOs. Altogether this study shows that identification of BO in a forensic setting is possible and has limits and characteristics in line with witness identification through other sensory modalities. PMID:27303317

  10. Finite-size effects in parametric subharmonic instability

    CERN Document Server

    Bourget, Baptiste; Dauxois, Thierry; Bars, Michaël Le; Odier, Philippe; Joubaud, Sylvain

    2014-01-01

    The parametric subharmonic instability in stratified fluids depends on the frequency and the amplitude of the primary plane wave. In this paper, we present experimental and numerical results emphasizing that the finite width of the beam also plays an important role on this triadic instability. A new theoretical approach based on a simple energy balance is developed and compared to numerical and experimental results. Because of the finite width of the primary wave beam, the secondary pair of waves can leave the interaction zone which affects the transfer of energy. Experimental and numerical results are in good agreement with the prediction of this theory, which brings new insights on energy transfers in the ocean where internal waves with finite-width beams are dominant.

  11. Artificial fish schools : Collective effects of school size, body size, and body form

    NARCIS (Netherlands)

    Kunz, H.; Hemelrijk, C.K.

    2003-01-01

    Individual-based models of schooling in fish have demonstrated that, via processes of self-organization. artificial fish may school in the absence of a leader or external stimuli, using local information only. We study for the first time how body size and body form of artificial fish affect school f

  12. Quantum coherent tractor beam effect for atoms trapped near a nanowaveguide

    Science.gov (United States)

    Sadgrove, Mark; Wimberger, Sandro; Nic Chormaic, Síle

    2016-01-01

    We propose several schemes to realize a tractor beam effect for ultracold atoms in the vicinity of a few-mode nanowaveguide. Atoms trapped near the waveguide are transported in a direction opposite to the guided mode propagation direction. We analyse three specific examples for ultracold 23Na atoms trapped near a specific nanowaveguide (i.e. an optical nanofibre): (i) a conveyor belt-type tractor beam effect, (ii) an accelerator tractor beam effect, and (iii) a quantum coherent tractor beam effect, all of which can effectively pull atoms along the nanofibre toward the light source. This technique provides a new tool for controlling the motion of particles near nanowaveguides with potential applications in the study of particle transport and binding as well as atom interferometry. PMID:27440516

  13. Effect of Physical Nonlinearity on Local Buckling in Sandwich Beams

    NARCIS (Netherlands)

    Koissin, Vitaly; Shipsha, Andrey; Skvortsov, Vitaly

    2010-01-01

    This article deals with experimental, theoretical, and FE characterization of the local buckling in foam-core sandwich beams. In the theoretical approach, this phenomena is considered in a periodic formulation (unbounded wrinkle wave); a nonlinear stress—strain response of the face material is accou

  14. The Spectral Index and Beaming Effect for Radio Sources

    Indian Academy of Sciences (India)

    J. Pan; J. H. Fan

    2011-03-01

    In this paper, we revisited the relationship between the spectral index and the core-dominance parameter using a larger sample of blazars. Conclusively, we explain that the spectral index is associated with the core-dominance parameter using the two-component relativistic beaming model.

  15. Effect of tube size on electromagnetic tube bulging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The commercial finite code ANSYS was employed for the simulation of the electromagnetic tube bulging process. The finite element model and boundary conditions were thoroughly discussed. ANSYS/EMAG was used to model the time varying electromagnetic field in order to obtain the radial and axial magnetic pressure acting on the tube. The magnetic pressure was then used as boundary conditions to model the high velocity deformation of various length tube with ANSYS/LSDYNA. The time space distribution of magnetic pressure on various length tubes was presented. Effect of tube size on the distribution of radial magnetic pressure and axial magnetic pressure and high velocity deformation were discussed. According to the radial magnetic pressure ratio of tube end to tube center and corresponding dimensionless length ratio of tube to coil, the free electromagnetic tube bulging was studied in classification. The calculated results show good agreements with practice.

  16. Effects of Breakdown, Backlog and Rework on Replenishment Lot Size

    Directory of Open Access Journals (Sweden)

    Tsu-Ming Yeh

    2012-11-01

    Full Text Available This study studies the effects of machine breakdown, backlog and rework on the replenishment lot size. In real-life manufacturing systems, random defective rate and breakdown of equipment are inevitable. When backlogging is permitted during a production run, a random machine failure may take place either in backlog filling stage or in inventory piling time; this study focuses on the former situation and considers all defective items produced are repairable through a rework process. The objective of this study is to determine the optimal run time that minimizes the long-run average production-inventory costs. The result can be directly applied to the practical production planning and control field to assist practitioner in production management cost reduction.

  17. Effect of chip size on steam explosion pretreatment of softwood.

    Science.gov (United States)

    Ballesteros, I; Oliva, J M; Navarro, A A; González, A; Carrasco, J; Ballesteros, M

    2000-01-01

    Although considerable progress has been made in technology for converting lignocellulosic biomass into ethanol, substantial opportunities still exist to reduce production costs. In biomass pretreatment, reducing milling power is a technological improvement that will substantially lower production costs for ethanol. Improving sugar yield from hemicellulose hydrolysis would also reduce ethanol production costs. Thus, it would be desirable to test innovative pretreatment conditions to improve the economics by reducing electrical power of the milling stage and by optimizing pretreatment recovery of hemicellulose, as well as to enhance cellulose hydrolysis. The objective of this study was to evaluate the effect of chip size (2-5, 5-8, and 8-12 mm) on steam-explosion pretreatment (190 and 210 degrees C, 4 and 8 min) of softwood (Pinus pinaster).

  18. The effect of material heterogeneity in curved composite beams for use in aircraft structures

    Science.gov (United States)

    Otoole, Brendan J.; Santare, Michael H.

    1992-01-01

    A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams for use in aircraft fuselage structures. Material heterogeneity can be induced during processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing a gradient in material properties in both the radial and tangential directions. The analysis procedure uses a separate two-dimensional elasticity solution for the stresses in the flanges and web sections of the beam. The separate solutions are coupled by requiring the forces and displacements match at the section boundaries. Analysis is performed for curved beams loaded in pure bending and uniform pressure. The beams can be of any general cross-section such as a hat, T-, I-, or J-beam. Preliminary results show that geometry of the beam dictates the effect of heterogeneity on performance. Heterogeneity plays a much larger role in beams with a small average radius to depth ratio, R/t, where R is the average radius of the beam and t is the difference between the inside and outside radius. Results of the analysis are in the form of stresses and displacements, and they are compared to both mechanics of materials and numerical solutions obtained using finite element analysis.

  19. Aerodynamic Ground Effect in Fruitfly Sized Insect Takeoff.

    Directory of Open Access Journals (Sweden)

    Dmitry Kolomenskiy

    Full Text Available Aerodynamic ground effect in flapping-wing insect flight is of importance to comparative morphologies and of interest to the micro-air-vehicle (MAV community. Recent studies, however, show apparently contradictory results of either some significant extra lift or power savings, or zero ground effect. Here we present a numerical study of fruitfly sized insect takeoff with a specific focus on the significance of leg thrust and wing kinematics. Flapping-wing takeoff is studied using numerical modelling and high performance computing. The aerodynamic forces are calculated using a three-dimensional Navier-Stokes solver based on a pseudo-spectral method with volume penalization. It is coupled with a flight dynamics solver that accounts for the body weight, inertia and the leg thrust, while only having two degrees of freedom: the vertical and the longitudinal horizontal displacement. The natural voluntary takeoff of a fruitfly is considered as reference. The parameters of the model are then varied to explore possible effects of interaction between the flapping-wing model and the ground plane. These modified takeoffs include cases with decreased leg thrust parameter, and/or with periodic wing kinematics, constant body pitch angle. The results show that the ground effect during natural voluntary takeoff is negligible. In the modified takeoffs, when the rate of climb is slow, the difference in the aerodynamic forces due to the interaction with the ground is up to 6%. Surprisingly, depending on the kinematics, the difference is either positive or negative, in contrast to the intuition based on the helicopter theory, which suggests positive excess lift. This effect is attributed to unsteady wing-wake interactions. A similar effect is found during hovering.

  20. Beam-Beam Simulations with GUINEA-PIG

    CERN Document Server

    Schulte, Daniel

    1998-01-01

    While the bunches in a linear collider cross only once, due to their small size they experience a strong beam-beam effect. GUINEA-PIG is a code to simulate the impact of this effect on luminosity and back ground. A short overview of the program is given with examples of its application to the back ground strudies for TESLA, the top quark threshold scan and a possible luminosity monitor, as well as some results for CLIC.

  1. Reduction of effective terahertz focal spot size by means of nested concentric parabolic reflectors

    NARCIS (Netherlands)

    Neumann, V.A.; Laurita, N.J.; Pan, LiDong; Armitage, N.P.

    2016-01-01

    An ongoing limitation of terahertz spectroscopy is that the technique is generally limited to the study of relatively large samples of order 4 mm across due to the generally large size of the focal beam spot. We present a nested concentric parabolic reflector design which can reduce the terahertz fo

  2. Influence of eye size and beam entry angle on dose to non-targeted tissues of the eye during stereotactic x-ray radiosurgery of AMD

    Science.gov (United States)

    Cantley, Justin L.; Hanlon, Justin; Chell, Erik; Lee, Choonsik; Smith, W. Clay; Bolch, Wesley E.

    2013-10-01

    Age-related macular degeneration is a leading cause of vision loss for the elderly population of industrialized nations. The IRay® Radiotherapy System, developed by Oraya® Therapeutics, Inc., is a stereotactic low-voltage irradiation system designed to treat the wet form of the disease. The IRay System uses three robotically positioned 100 kVp collimated photon beams to deliver an absorbed dose of up to 24 Gy to the macula. The present study uses the Monte Carlo radiation transport code MCNPX to assess absorbed dose to six non-targeted tissues within the eye—total lens, radiosensitive tissues of the lens, optic nerve, distal tip of the central retinal artery, non-targeted portion of the retina, and the ciliary body--all as a function of eye size and beam entry angle. The ocular axial length was ranged from 20 to 28 mm in 2 mm increments, with the polar entry angle of the delivery system varied from 18° to 34° in 2° increments. The resulting data showed insignificant variations in dose for all eye sizes. Slight variations in the dose to the optic nerve and the distal tip of the central retinal artery were noted as the polar beam angle changed. An increase in non-targeted retinal dose was noted as the entry angle increased, while the dose to the lens, sensitive volume of the lens, and ciliary body decreased as the treatment polar angle increased. Polar angles of 26° or greater resulted in no portion of the sensitive volume of the lens receiving an absorbed dose of 0.5 Gy or greater. All doses to non-targeted structures reported in this study were less than accepted thresholds for post-procedure complications.

  3. Effect of imperfections of the radial component of a magnetic field on beam dynamics in medical cyclotron C235-V3

    Science.gov (United States)

    Karamysheva, G. A.; Kostromin, S. A.; Morozov, N. A.; Samsonov, E. V.; Syresin, E. M.

    2014-11-01

    This paper presents numerical simulations and experimental results related to the effect of imperfections of the radial component of a magnetic field on the beam dynamics in the medical cyclotron C235-V3 of the Dimitrovgrad Proton Therapy Center. These imperfections in the region of the minimal axial betatron frequency lead to a transformation of coherent motion of the center of gravity of the beam to the incoherent motion of separate particles. The radial component increases the axial size of the beam by a factor of 2 at a radius of 20 cm, which produces additional losses of protons. To reduce undesirable actions of the radial component on the axial motion, the magnetic system in the central region has been optimized using two procedures: the positioning of shim correctors on sectors and selecting a special asymmetric arrangement of the upper and lower central plugs. This led to a twofold reduction in the axial size of the beam and a decrease in proton losses. Eventually, the beam transmission in C235-V3 has been increased to 72% without a limiting aperture diaphragm, which is commonly used in cyclotrons of this type. This makes it possible to reduce the irradiation dose of machine elements and increase the beam current at a deflector entrance of the cyclotron C235-V3 by a factor of 1.5 when compared to a serial C235 cyclotron.

  4. Effects of aperture averaging and beam width on a partially coherent Gaussian beam over free-space optical links with turbulence and pointing errors.

    Science.gov (United States)

    Lee, It Ee; Ghassemlooy, Zabih; Ng, Wai Pang; Khalighi, Mohammad-Ali; Liaw, Shien-Kuei

    2016-01-01

    Joint effects of aperture averaging and beam width on the performance of free-space optical communication links, under the impairments of atmospheric loss, turbulence, and pointing errors (PEs), are investigated from an information theory perspective. The propagation of a spatially partially coherent Gaussian-beam wave through a random turbulent medium is characterized, taking into account the diverging and focusing properties of the optical beam as well as the scintillation and beam wander effects. Results show that a noticeable improvement in the average channel capacity can be achieved with an enlarged receiver aperture in the moderate-to-strong turbulence regime, even without knowledge of the channel state information. In particular, it is observed that the optimum beam width can be reduced to improve the channel capacity, albeit the presence of scintillation and PEs, given that either one or both of these adverse effects are least dominant. We show that, under strong turbulence conditions, the beam width increases linearly with the Rytov variance for a relatively smaller PE loss but changes exponentially with steeper increments for higher PE losses. Our findings conclude that the optimal beam width is dependent on the combined effects of turbulence and PEs, and this parameter should be adjusted according to the varying atmospheric channel conditions. Therefore, we demonstrate that the maximum channel capacity is best achieved through the introduction of a larger receiver aperture and a beam-width optimization technique.

  5. Elimination of the beam effect on channeling dips of bismuth implanted in silicon

    Science.gov (United States)

    Wagh, A. G.; Radhakrishnan, S.; Gaonkar, S. G.; Kansara, M. J.

    1980-01-01

    The effect of the analysing He + ion beam has been eliminated from channeling measurements on Si(Bi) by extrapolating the plot of normalised yield against He + dose to zero ion dose. The magnitude of the beam effect varies with the angle of incidence, being minimum for beam incidence along the crystallographic axis. The axial channeling dips thus obtained exhibit similar minimum yields for bismuth and silicon. The bismuth dips are, however, narrower than for silicon. The planar channeling experiments, on the other hand, yield nearly identical bismuth and silicon dips. The results indicate that the bismuth atom occupies the substitutional site in silicon, but the lattice is strained in its vicinity.

  6. Observation of nonspecular effects for Gaussian Schell-model light beams

    CERN Document Server

    Merano, Michele; Mistura, Giampaolo

    2012-01-01

    We investigate experimentally the role of spatial coherence on optical beam shifts. This topic has been the subject of recent theoretical debate. We consider Gaussian Schell-model beams, with different spatial degrees of coherence, reflected at an air-glass interface. We prove that the angular Goos-H\\"anchen and the angular Imbert-Fedorov effects are affected by the spatial degree of coherence of the incident beam, whereas the spatial Goos-H\\"anchen effect does not depend on incoherence. Our data unambiguously resolve the theoretical debate in favour of one specific theory.

  7. Reducing beam hardening effects and metal artefacts using Medipix3RX: With applications from biomaterial science

    CERN Document Server

    Rajendran, K; de Ruiter, N J A; Chernoglazov, A I; Panta, R K; Butler, A P H; Butler, P H; Bell, S T; Anderson, N G; Woodfield, T B F; Tredinnick, S J; Healy, J L; Bateman, C J; Aamir, R; Doesburg, R M N; Renaud, P F; Gieseg, S P; Smithies, D J; Mohr, J L; Mandalika, V B H; Opie, A M T; Cook, N J; Ronaldson, J P; Nik, S J; Atharifard, A; Clyne, M; Bones, P J; Bartneck, C; Grasset, R; Schleich, N; Billinghurst, M

    2014-01-01

    This paper discusses methods for reducing beam hardening effects using spectral data for biomaterial applications. A small-animal spectral scanner operating in the diagnostic energy range was used. We investigate the use of photon-processing features of the Medipix3RX ASIC in reducing beam hardening and associated artefacts. A fully operational charge summing mode was used during the imaging routine. We present spectral data collected for metal alloy samples, its analysis using algebraic 3D reconstruction software and volume visualisation using a custom volume rendering software. Narrow high energy acquisition using the photon-processing detector revealed substantial reduction in beam hardening effects and metal artefacts.

  8. Knife mill operating factors effect on switchgrass particle size distributions.

    Science.gov (United States)

    Bitra, Venkata S P; Womac, Alvin R; Yang, Yuechuan T; Igathinathane, C; Miu, Petre I; Chevanan, Nehru; Sokhansanj, Shahab

    2009-11-01

    Biomass particle size impacts handling, storage, conversion, and dust control systems. Switchgrass (Panicum virgatum L.) particle size distributions created by a knife mill were determined for integral classifying screen sizes from 12.7 to 50.8 mm, operating speeds from 250 to 500 rpm, and mass input rates from 2 to 11 kg/min. Particle distributions were classified with standardized sieves for forage analysis that included horizontal sieving motion with machined-aluminum sieves of thickness proportional to sieve opening dimensions. Then, a wide range of analytical descriptors were examined to mathematically represent the range of particle sizes in the distributions. Correlation coefficient of geometric mean length with knife mill screen size, feed rate, and speed were 0.872, 0.349, and 0.037, respectively. Hence, knife mill screen size largely determined particle size of switchgrass chop. Feed rate had an unexpected influence on particle size, though to a lesser degree than screen size. The Rosin-Rammler function fit the chopped switchgrass size distribution data with an R(2)>0.982. Mass relative span was greater than 1, which indicated a wide distribution of particle sizes. Uniformity coefficient was more than 4.0, which indicated a large assortment of particles and also represented a well-graded particle size distribution. Knife mill chopping of switchgrass produced 'strongly fine skewed mesokurtic' particles with 12.7-25.4 mm screens and 'fine skewed mesokurtic' particles with 50.8 mm screen. Results of this extensive analysis of particle sizes can be applied to selection of knife mill operating parameters to produce a particular size of switchgrass chop, and will serve as a guide for relations among the various analytic descriptors of biomass particle distributions.

  9. Effect of boundary conditions and convection on thermally induced motion of beams subjected to internal heating

    Institute of Scientific and Technical Information of China (English)

    MALIK Pravin; KADOLI Ravikiran; GANESAN N.

    2007-01-01

    Numerical exercises are presented on the thermally induced motion of internally heated beams under various heat transfer and structural boundary conditions. The dynamic displacement and dynamic thermal moment of the beam are analyzed taking into consideration that the temperature gradient is independent as well as dependent on the beam displacement. The effect of length to thickness ratio of the beam on the thermally induced vibration is also investigated. The type of boundary conditions has its influence on the magnitude of dynamic displacement and dynamic thermal moment. A sustained thermally induced motion is observed with progress of time when the temperature gradient being evaluated is dependent on the forced convection generated due to beam motion. A finite element method (FEM) is used to solve the structural equation of motion as well as the heat transfer equation.

  10. Effects of Nominal Maximum Aggregate Size on the Performance of Stone Matrix Asphalt

    Directory of Open Access Journals (Sweden)

    Hongying Liu

    2017-01-01

    Full Text Available It is well known that the performance of hot mix asphalt (HMA in service life is closely related to a proper aggregate gradation. A laboratory study was conducted to investigate the effects of nominal maximum aggregate size (NMAS on the performance of stone matrix asphalt (SMA. The volumetric characteristics and performance properties obtained from wheel tracking tests, permeability test, beam bending test, contabro test are compared for SMA mixes with different NMAS. The results indicated that voids in mineral aggregate (VMA and voids filled with asphalt (VFA of SMA mixtures increased with a decrease of aggregate size in aggregate gradation. SMA30 had the lowest optimum asphalt content among all the mixtures. Increase of NMAS contributed to improvement of the rutting resistance of SMA mixtures. However, a decrease of NMAS showed better cracking and raveling resistance. Permeability rate of SMA was primarily affected by the air voids (AV and break point sieve, but was also sensitive to aggregate gradation to some extent, with reduced NMAS corresponding to less permeability rate. Based on the test results, SMA5 and SMA13 are suggested to be used as a water-proof layer in bridge deck pavement, and SMA20 and SMA30 are suggested to be used as binder course in asphalt pavement, which needs to possess superior rutting resistance at high temperature.

  11. Numerical Investigation of Size and Structure Effect on Tensile Characteristics of Symmetric and Asymmetric CNTs

    Directory of Open Access Journals (Sweden)

    Mahnaz Zakeri

    2016-06-01

    Full Text Available In this research, the influence of structure on the tensile properties of single- walled carbon nanotubes (CNTs is evaluated using molecular mechanics technique and finite element method. The effects of diameter, length and chiral angle on elastic modulus and Poisson’s ratio of armchair, zigzag and chiral structures are investigated. To simulate the CNTs, a 3D FEM code is developed using the ANSYS commercial software. Considering the carbon-carbon covalent bonds as connecting load-carrying beam elements, and the atoms as joints of the elements, CNTs are simulated as space-frame structures. The atomic potentials are estimated using harmonic simple functions. The numerical results show that by increasing the diameter and length to a certain amount, the size effect on tensile behavior of modeled nanotubes is omitted. In fact, for nanotubes with diameter over 2 nm and length over 36.5 nm the chiral angle is the only effective factor on the tensile properties. Also, it is found that the structure has a little effect on the elasticity modulus, which is about 4%. However, Poisson’s ratio can be affected significantly with chiral angle. Asymmetric structures with angles θ

  12. Size-dependent ion-beam-induced anisotropic plastic deformation at the nanoscale by nonhydrostatic capillary stresses

    NARCIS (Netherlands)

    van Dillen, T.; van der Giessen, E.; Onck, P. R.; Polman, A.

    2006-01-01

    We develop a phenomenological model for size-dependent anisotropic plastic deformation of colloidal nanoparticles under ion irradiation. We show that, at the nanoscale, nonhydrostatic capillary stresses drive radiation-induced Newtonian viscous flow, counteracting the stress state that initiates the

  13. Multi-beam raindrop size distributions retrievals on the Doppler spectra: Influence of averaging and mean horizontal wind correction

    NARCIS (Netherlands)

    Unal, C.M.H.

    2012-01-01

    Acquiring the raindrop size distribution (DSD) from radar data is still a challenge. For profiling radar, this distribution can be estimated from the Doppler spectra. However the Doppler spectrum is not a direct measure of the DSD. The radial component of the wind shifts the Doppler spectrum related

  14. The dose response relation for rat spinal cord paralysis analyzed in terms of the effective size of the functional subunit

    Science.gov (United States)

    Adamus-Górka, Magdalena; Mavroidis, Panayiotis; Brahme, Anders; Lind, Bengt K.

    2008-11-01

    Radiobiological models for estimating normal tissue complication probability (NTCP) are increasingly used in order to quantify or optimize the clinical outcome of radiation therapy. A good NTCP model should fulfill at least the following two requirements: (a) it should predict the sigmoid shape of the corresponding dose-response curve and (b) it should accurately describe the probability of a specified response for arbitrary non-uniform dose delivery for a given endpoint as accurately as possible, i.e. predict the volume dependence. In recent studies of the volume effect of a rat spinal cord after irradiation with narrow and broad proton beams the authors claim that none of the existing NTCP models is able to describe their results. Published experimental data have been used here to try to quantify the change in the effective dose (D50) causing 50% response for different field sizes. The present study was initiated to describe the induction of white matter necrosis in a rat spinal cord after irradiation with narrow proton beams in terms of the mean dose to the effective volume of the functional subunit (FSU). The physically delivered dose distribution was convolved with a function describing the effective size or, more accurately, the sensitivity distribution of the FSU to obtain the effective mean dose deposited in it. This procedure allows the determination of the mean D50 value of the FSUs of a certain size which is of interest for example if the cell nucleus of the oligodendrocyte is the sensitive target. Using the least-squares method to compare the effective doses for different sizes of the functional subunits with the experimental data the best fit was obtained with a length of about 9 mm. For the non-uniform dose distributions an effective FSU length of 8 mm gave the optimal fit with the probit dose-response model. The method could also be used to interpret the so-called bath and shower experiments where the heterogeneous dose delivery was used in the

  15. Effect of ion compensation of the beam space charge on gyrotron operation

    Energy Technology Data Exchange (ETDEWEB)

    Fokin, A. P.; Glyavin, M. Yu. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Nusinovich, G. S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)

    2015-04-15

    In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ion compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.

  16. SIZE EFFECT AND GEOMETRICAL EFFECT OF SOLIDS IN MICRO-INDENTATION TEST

    Institute of Scientific and Technical Information of China (English)

    魏悦广; 王学峥; 赵满洪; 郑哲敏; 白以龙

    2003-01-01

    Micro-indentation tests at scales of the order of sub-micron show that the measured hardness increases strongly with decreasing indent depth or indent size, which is frequently referred to as the size effect. At the same time, at micron or sub-micron scale, another effect, which is referred to as the geometrical size effects such as crystal grain size effect, thin film thickness effect, etc., also influences the measured material hardness. However, the trends are at odds with the size-independence implied by the conventional elastic-plastic theory. In the present research, the strain gradient plasticity theory (Fleck and Hutchinson) is used to model the composition effects (size effect and geometrical effect) for polycrystal material and metal thin film/ceramic substrate systems when materials undergo micro-indenting. The phenomena of the "pile-up" and "sink-in" appeared in the indentation test for the polycrystal materials are also discussed. Meanwhile, the micro-indentation experiments for the polycrystal A1 and for the Ti/Si3N4 thin film/substrate system are carried out. By comparing the theoretical predictions with experimental measurements, the values and the variation trends of the micro-scale parameter included in the strain gradient plasticity theory are predicted.

  17. Collective instabilities and collisional effects for space charge dominated beams

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, C. [Dipartimento di Fisica, Universita di Bologna and INFN, Via Irnerio 46, 40126 Bologna (Italy)]. E-mail: benedetti@bo.infn.it; Turchetti, G. [Dipartimento di Fisica, Universita di Bologna and INFN, Via Irnerio 46, 40126 Bologna (Italy)

    2007-07-01

    This paper is organized into two parts. In the first one we analyze the equipartitioning process in the presence of collisions for a Gaussian anisotropic beam. Far from instabilities the equipartition process can be described correctly by using Landau's collisional theory, whereas when the dynamics of the system is strongly nonlinear (e.g. in the vicinity of a resonance) a hybrid dynamical-collisional equipartition mechanism occurs. In the second part of the paper we discuss shortly a systematic study of the collective instabilities in a symmetric periodic focusing channel for a KV beam by using the moments method. We emphasize differences occurring when the periodic focusing lattice is replaced by the corresponding constant focusing one.

  18. The other half of the story: effect size analysis in quantitative research.

    Science.gov (United States)

    Maher, Jessica Middlemis; Markey, Jonathan C; Ebert-May, Diane

    2013-01-01

    Statistical significance testing is the cornerstone of quantitative research, but studies that fail to report measures of effect size are potentially missing a robust part of the analysis. We provide a rationale for why effect size measures should be included in quantitative discipline-based education research. Examples from both biological and educational research demonstrate the utility of effect size for evaluating practical significance. We also provide details about some effect size indices that are paired with common statistical significance tests used in educational research and offer general suggestions for interpreting effect size measures. Finally, we discuss some inherent limitations of effect size measures and provide further recommendations about reporting confidence intervals.

  19. The Effects of Undulator Field on Stored Electron Beam

    OpenAIRE

    Thananchai DASRI; Supagorn RUGMAI

    2012-01-01

    In order to extend the usable photon spectrum to higher photon flux, an undulator with periodic magnetic field has to be installed into the storage ring of the synchrotron facility. This paper presents the perturbations from the magnetic field of such a device on the electron beam dynamics in the ring. Theories and an example of a practical device are discussed. The U60 undulator of the Siam Photon Source is selected for illustrating these ideas.Graphical abstract

  20. The Effects of Undulator Field on Stored Electron Beam

    Directory of Open Access Journals (Sweden)

    Thananchai DASRI

    2012-03-01

    Full Text Available In order to extend the usable photon spectrum to higher photon flux, an undulator with periodic magnetic field has to be installed into the storage ring of the synchrotron facility. This paper presents the perturbations from the magnetic field of such a device on the electron beam dynamics in the ring. Theories and an example of a practical device are discussed. The U60 undulator of the Siam Photon Source is selected for illustrating these ideas.Graphical abstract

  1. Size speed bias or size arrival effect-How judgments of vehicles' approach speed and time to arrival are influenced by the vehicles' size.

    Science.gov (United States)

    Petzoldt, Tibor

    2016-10-01

    Crashes at railway level crossings are a key problem for railway operations. It has been suggested that a potential explanation for such crashes might lie in a so-called size speed bias, which describes the phenomenon that observers underestimate the speed of larger objects, such as aircraft or trains. While there is some evidence that this size speed bias indeed exists, it is somewhat at odds with another well researched phenomenon, the size arrival effect. When asked to judge the time it takes an approaching object to arrive at a predefined position (time to arrival, TTA), observers tend to provide lower estimates for larger objects. In that case, road users' crossing decisions when confronted with larger vehicles should be rather conservative, which has been confirmed in multiple studies on gap acceptance. The aim of the experiment reported in this paper was to clarify the relationship between size speed bias and size arrival effect. Employing a relative judgment task, both speed and TTA estimates were assessed for virtual depictions of a train and a truck, using a car as a reference to compare against. The results confirmed the size speed bias for the speed judgments, with both train and truck being perceived as travelling slower than the car. A comparable bias was also present in the TTA estimates for the truck. In contrast, no size arrival effect could be found for the train or the truck, neither in the speed nor the TTA judgments. This finding is inconsistent with the fact that crossing behaviour when confronted with larger vehicles appears to be consistently more conservative. This discrepancy might be interpreted as an indication that factors other than perceived speed or TTA play an important role for the differences in gap acceptance between different types of vehicles.

  2. Effectiveness of trimethylopropane trimethacrylate for the electron-beam-irradiation-induced cross-linking of polylactic acid

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Hon-Meng [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Bee, Soo-Tueen, E-mail: beest@utar.edu.my [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Ratnam, C.T. [Radiation Processing Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Sin, Lee Tin; Phang, Yee-Yao; Tee, Tiam-Ting [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Rahmat, A.R. [Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

    2014-01-15

    Highlights: • Investigation of trimethylopropane trimethacrylate (TMPTMA) on electron beam irradiated PLA. • Irradiated PLA blends were weakened by incorporation of high amount of TMPTMA. • TMPTMA interacts with polymer free radicals to build crosslinking network. -- Abstract: The purpose of this research was to investigate the effects of various loading levels of trimethylopropane trimethacrylate (TMPTMA) on the properties of polylactic acid (PLA) cross-linked via electron-beam irradiation. PLA was compounded with 3–5 wt.% of TMPTMA to induce cross-linking upon subjection to electron-beam irradiation doses of 25–250 kGy. The physical properties of the PLA samples were characterised by means of X-ray diffraction, gel fraction and scanning electron microscopy analyses on fractured surfaces after tensile tests. The presence of TMPTMA in PLA was found to effectively increase the crystallite size and gel fraction. However, higher loading levels of TMPTMA could compromise the properties of the PLA/TMPTMA samples, indicating that a larger amount of monomer free radicals might promote degradation within the substantially cross-linked amorphous phase. Irradiation-induced cross-linking in the samples could improve the cross-linking density while decreasing the elongation and interfering with the crystallisation. These effects are caused by the intensive irradiation-induced chain scission that is responsible for the deterioration of the mechanical and crystalline properties of the samples.

  3. Effect of particle size on lead absorption from the gut

    Energy Technology Data Exchange (ETDEWEB)

    Barltrop, D.; Meek, F.

    1979-07-01

    The relationship between particle size and absorption of lead particles from the gastrointestinal tract of the rat has been investigated. Preparations of metallic lead of particle size between 0. and 250..mu.. were incorporated in laboratory rat diets and absorption determined by measurement of tissue lead concentrations attained under standard conditions. An inverse relationship was found between particle size and lead absorption; this relationship was most marked in the 0 to 100..mu.. range. A five-fold enhancement of absorption was observed from the diet with lead particles of mean size 6..mu.., compared with 197..mu.. particle size. Lead absorption from dried paint films containing lead chromate and lead octoate was measured using a similar technique. a marked enhancement of absorption was observed for both paints when particle size was reduced from 500 to 1000..mu.. to < 50..mu...

  4. Simulation of Head-on Beam-Beam Limitations in Future High Energy Colliders

    CERN Document Server

    Buffat, Xavier; Florio, Adrien; Pieloni, Tatiana; Tambasco, Claudia

    2016-01-01

    The Future Circular Hadron Collider (FCC-hh) project calls for studies in a new regime of beam-beam interactions. While the emittance damping due to synchrotron radiation is still slower than in past or existing lepton colliders, it is significantly larger than in other hadron colliders. The slow reduction of the emittance is profitable for higher luminosity in term of transverse beam size at the interaction points and also to mitigate long-range beam-beam effects, potentially allowing for a reduction of the crossing angle between the beams during the operation. In such conditions, the strength of head-on beam-beam interactions increases, potentially limiting the beam brightness. 4D weak-strong and strong-strong simulations are performed in order to assess these limitations.

  5. Digital orthodontic radiographic set versus cone-beam computed tomography: an evaluation of the effective dose

    Science.gov (United States)

    Chinem, Lillian Atsumi Simabuguro; Vilella, Beatriz de Souza; Maurício, Cláudia Lúcia de Pinho; Canevaro, Lucia Viviana; Deluiz, Luiz Fernando; Vilella, Oswaldo de Vasconcellos

    2016-01-01

    ABSTRACT Objective: The aim of this study was to compare the equivalent and effective doses of different digital radiographic methods (panoramic, lateral cephalometric and periapical) with cone-beam computed tomography (CBCT). Methods: Precalibrated thermoluminescent dosimeters were placed at 24 locations in an anthropomorphic phantom (Alderson Rando Phantom, Alderson Research Laboratories, New York, NY, USA), representing a medium sized adult. The following devices were tested: Heliodent Plus (Sirona Dental Systems, Bernsheim, Germany), Orthophos XG 5 (Sirona Dental Systems, Bernsheim, Germany) and i-CAT (Imaging Sciences International, Hatfield, PA, USA). The equivalent doses and effective doses were calculated considering the recommendations of the International Commission of Radiological Protection (ICRP) issued in 1990 and 2007. Results: Although the effective dose of the radiographic set corresponded to 17.5% (ICRP 1990) and 47.2% (ICRP 2007) of the CBCT dose, the equivalent doses of skin, bone surface and muscle obtained by the radiographic set were higher when compared to CBCT. However, in some areas, the radiation produced by the orthodontic set was higher due to the complete periapical examination. Conclusion: Considering the optimization principle of radiation protection, i-CAT tomography should be used only in specific and justified circumstances. Additionally, following the ALARA principle, single periapical radiographies covering restricted areas are more suitable than the complete periapical examination. PMID:27653266

  6. Digital orthodontic radiographic set versus cone-beam computed tomography: an evaluation of the effective dose

    Directory of Open Access Journals (Sweden)

    Lillian Atsumi Simabuguro Chinem

    Full Text Available ABSTRACT Objective: The aim of this study was to compare the equivalent and effective doses of different digital radiographic methods (panoramic, lateral cephalometric and periapical with cone-beam computed tomography (CBCT. Methods: Precalibrated thermoluminescent dosimeters were placed at 24 locations in an anthropomorphic phantom (Alderson Rando Phantom, Alderson Research Laboratories, New York, NY, USA, representing a medium sized adult. The following devices were tested: Heliodent Plus (Sirona Dental Systems, Bernsheim, Germany, Orthophos XG 5 (Sirona Dental Systems, Bernsheim, Germany and i-CAT (Imaging Sciences International, Hatfield, PA, USA. The equivalent doses and effective doses were calculated considering the recommendations of the International Commission of Radiological Protection (ICRP issued in 1990 and 2007. Results: Although the effective dose of the radiographic set corresponded to 17.5% (ICRP 1990 and 47.2% (ICRP 2007 of the CBCT dose, the equivalent doses of skin, bone surface and muscle obtained by the radiographic set were higher when compared to CBCT. However, in some areas, the radiation produced by the orthodontic set was higher due to the complete periapical examination. Conclusion: Considering the optimization principle of radiation protection, i-CAT tomography should be used only in specific and justified circumstances. Additionally, following the ALARA principle, single periapical radiographies covering restricted areas are more suitable than the complete periapical examination.

  7. The effect of the iBEAM Evo carbon fiber tabletop on skin sparing.

    Science.gov (United States)

    Simpson, John B; Godwin, Guy A

    2011-01-01

    Replicating the attenuation properties of the treatment tabletop are of primary importance for accurate treatment planning; however, the effect of the tabletop on the skin-sparing properties of x-rays can be overlooked. Under some conditions, the reaction of skin to the radiation can be so serious as to be the dose-limiting organ for radiotherapy treatment. Hence, an understanding of the magnitude of the reduction in skin sparing is important. Because of the development of image-guided radiotherapy, modern tabletops have been developed without the use of metal supports that otherwise provided the necessary level of rigidity. Rigidity is instead provided by compressed foam within a carbon-fiber shell, which, although it provides artefact-free imaging and high levels of rigidity, has an adverse affect on the dose in the build-up region. Representative of this type is the iBEAM evo tabletop, whose effect on the skin dose was determined at 6-MV, 10-MV, and 18-MV x-rays. Skin dose was found to increase by 60-70% owing to the tabletop, with the effect increasing with field size and decreasing with energy. By considering an endpoint of erythema, a radiobiological advantage of selecting 10 MV over 6 MV for applicable treatments was demonstrated.

  8. 50 MeV lithium ion beam irradiation effects in poly vinylidene fluoride (PVDF) polymer

    Indian Academy of Sciences (India)

    A K Srivastava; H S Virk

    2000-12-01

    Irradiation effects of 50 MeV 7Li+3 ion beam induced in bulk PVDF polymer have been studied with respect to their optical, chemical, structural and electrical behaviour by using UV-visible, FT-IR spectroscopy, XRD technique and electrical frequency response using LCR bridge. The ion fluences ranging from 1.27 × 1011 to 2.15 × 1013 ions cm–2 have been used to study dose effects of irradiation in PVDF. The recorded UV-visible spectra clearly shows five characteristic peaks at 315, 325, 360, 425 and 600 nm. Due to irradiation, the optical absorption initially decreases but then increases with higher fluences. In the FT-IR spectra, no appreciable change has been observed after irradiation, indicating that this polymer is chemically stable. There is exponential increase in admittance with log of frequency but the effect of irradiation is not quite appreciable. The value of tan and relaxation frequency are changed appreciably due to irradiation. The diffraction pattern of PVDF indicates that this polymer is in semi-crystalline form; a decrease in the crystallinity and crystallite size has been observed due to irradiation.

  9. The first experience with LHC beam gas ionization monitor

    CERN Document Server

    Sapinski, M; Dehning, B; Guerrero, A; Patecki, M; Versteegen, R

    2012-01-01

    The Beam Gas Ionization Monitors (BGI) are used to measure beam emittance on LHC. This paper describes the detectors and their operation and discusses the issues met during the commissioning. It also discusses the various calibration procedures used to correct for non-uniformity of Multi-Channel plates and to correct the beam size for effects affecting the electron trajectory after ionization.

  10. Beam-Switch Transient Effects in the RF Path of the ICAPA Receive Phased Array Antenna

    Science.gov (United States)

    Sands, O. Scott

    2003-01-01

    When the beam of a Phased Array Antenna (PAA) is switched from one pointing direction to another, transient effects in the RF path of the antenna are observed. Testing described in the report has revealed implementation-specific transient effects in the RF channel that are associated with digital clocking pulses that occur with transfer of data from the Beam Steering Controller (BSC) to the digital electronics of the PAA under test. The testing described here provides an initial assessment of the beam-switch phenomena by digitally acquiring time series of the RF communications channel, under CW excitation, during the period of time that the beam switch transient occurs. Effects are analyzed using time-frequency distributions and instantaneous frequency estimation techniques. The results of tests conducted with CW excitation supports further Bit-Error-Rate (BER) testing of the PAA communication channel.

  11. Heater size effect on subcooled pool boiling of FC-72

    Energy Technology Data Exchange (ETDEWEB)

    Raj, Rishi; Kim, Jungho [University of Maryland, College Park, MD (United States). Dept. of Mechanical Engineering

    2009-07-01

    Extensive research has been conducted on pool boiling using heaters larger than the capillary length. For large heaters and/or high gravity conditions, boiling is dominated by buoyancy, and the heat transfer is heater size independent. Much less is known about boiling on small heaters and at low gravity levels. The ratio of heater size L{sub h} to capillary length L{sub c} is an important parameter in the determination of heater size dependence on heat transfer. As the ratio L{sub h}/L{sub c} decreases due to a decrease in either heater size or gravity, surface tension forces become dominant. It is proposed that transition from buoyancy to surface tension dominated boiling occurs when the heater size and bubble departure diameter are of the same order. Previous work in variable gravity with flat surfaces has shown that the heat transfer was heater size independent only when the ratio L{sub h}/L{sub c} was considerably larger than 1. An array of 96 platinum resistance heater elements in a 10 x 10 configuration with individual elements 0.7 x 0.7 mm{sup 2} in size was used to vary heater size and measure the heat transfer. The threshold value of L{sub h}/L{sub c} above which pool boiling is heater size independent was found to be about 2.8. (author)

  12. Grain Constraint and Size Effects in Shape Memory Alloy Microwires

    Science.gov (United States)

    Ueland, Stian Melhus

    Shape memory alloys exhibit interesting and useful properties, such as the shape memory effect and superelasticity. Among the many alloy families that have been shown to exhibit shape memory properties the ones based on copper are interesting because they are relatively inexpensive and show excellent properties when made as single crystals. However, the performance ofthese alloys is severely compromised by the introduction of grain boundaries, to the point where they are too poor for commercial applications. This thesis studies the mechanical properties of fine Cobased wires with a bamboo microstructure, i.e., where triple junctions are absent and grain boundaries run perpendicular to the wire axis. These microwires are not single crystals, but their microstructure is not as complex as that of polycrystals either: we call this new class of shape memory alloys oligocrystals. This thesis seeks to better understand the relationship between microstructure and properties in these alloys through a combination of mechanical testing, in situ experiments and modeling. First, in situ scanning electron microscopy, together with finite element modeling, is used to understand the role of grain constraint on the martensitic transformation. Grain constraints are observed to be much less severe in oligocrystalline wires as compared to polycrystals. Oligocrystalline microwires are then thermomechanically tested and shown to exhibit excellent properties that approach those of single crystals. Next, property evolution during cycling is investigated, revealing training effects as well as fatigue life and fracture. Finally, size effects in damping and transformation morphology are studied and it is shown that a transition from a many-domain to a single domain martensite morphology takes place when the wire diameter is decreased. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

  13. Investigating the effect of electron emission pattern on RF gun beam quality

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, A. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Shokri, B., E-mail: b-shokri@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of)

    2016-05-11

    Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect. - Highlights: • We developed a 3D code to simulate the beam dynamics of thermionic RF gun. • Te impact of the emission pattern on the beam dynamic was investigated. • Different emission pattern results different emittance in the gun exit. • Using a nosecone around the cathode adjacent wall reduces back bombardment effect.

  14. Modeling the Biophysical Effects in a Carbon Beam Delivery Line using Monte Carlo Simulation

    CERN Document Server

    Cho, Ilsung; Cho, Sungho; Kim, Eun Ho; Song, Yongkeun; Shin, Jae-ik; Jung, Won-Gyun

    2016-01-01

    Relative biological effectiveness (RBE) plays an important role in designing a uniform dose response for ion beam therapy. In this study the biological effectiveness of a carbon ion beam delivery system was investigated using Monte Carlo simulation. A carbon ion beam delivery line was designed for the Korea Heavy Ion Medical Accelerator (KHIMA) project. The GEANT4 simulation tool kit was used to simulate carbon beam transporting into media. An incident energy carbon ion beam in the range between 220 MeV/u and 290 MeV/u was chosen to generate secondary particles. The microdosimetric-kinetic (MK) model is applied to describe the RBE of 10% survival in human salivary gland (HSG) cells. The RBE weighted dose was estimated as a function of the penetrating depth of the water phantom along the incident beam direction. A biologically photon-equivalent Spread Out Bragg Peak (SOBP) was designed using the RBE weighted absorbed dose. Finally, the RBE of mixed beams was predicted as a function of the water phantom depth.

  15. Modeling the biophysical effects in a carbon beam delivery line by using Monte Carlo simulations

    Science.gov (United States)

    Cho, Ilsung; Yoo, SeungHoon; Cho, Sungho; Kim, Eun Ho; Song, Yongkeun; Shin, Jae-ik; Jung, Won-Gyun

    2016-09-01

    The Relative biological effectiveness (RBE) plays an important role in designing a uniform dose response for ion-beam therapy. In this study, the biological effectiveness of a carbon-ion beam delivery system was investigated using Monte Carlo simulations. A carbon-ion beam delivery line was designed for the Korea Heavy Ion Medical Accelerator (KHIMA) project. The GEANT4 simulation tool kit was used to simulate carbon-ion beam transport into media. An incident energy carbon-ion beam with energy in the range between 220 MeV/u and 290 MeV/u was chosen to generate secondary particles. The microdosimetric-kinetic (MK) model was applied to describe the RBE of 10% survival in human salivary-gland (HSG) cells. The RBE weighted dose was estimated as a function of the penetration depth in the water phantom along the incident beam's direction. A biologically photon-equivalent Spread Out Bragg Peak (SOBP) was designed using the RBE-weighted absorbed dose. Finally, the RBE of mixed beams was predicted as a function of the depth in the water phantom.

  16. Lensless Ghost Diffraction with Partially Coherent Sources: Effects of the Source Size, Transverse Coherence, Detector Size and Defocusing Length

    Science.gov (United States)

    Lin, Jie; Cheng, Jing

    2011-09-01

    Lensless ghost diffraction with partially coherent sources is investigated theoretically and numerically. Based on the classical optical coherent theory and the Gauss-Shell model of the partially coherent sources, we derive an analytical imaging formula of lensless ghost diffraction (LGD). Using this formula, we can see the effects of the transverse size and coherence of the sources, the detector size and defocusing length on the quality of LGD. Numerical results are presented to show that for different detector sizes and defocusing lengths, high quality LGD can be realized by using sources with appropriate transverse sizes and coherent widths. These findings can be used to choose the optimal parameters in the design of a realistic LGD system.

  17. Analysis of the Influence of Fibre Diameter on Wirescanner Beam Profile Measurements

    CERN Document Server

    King, Quentin

    1988-01-01

    It is often important to be able to measure beam profiles in regions where the beam size is very small. Following concern that the profile measurement might be affected by having a beam size of the same order as the diameter of the wirescanner fibre, the effect was analysed numerically, and the results are presented.

  18. Effects of Meaning and Symmetry on Judgments of Size

    DEFF Research Database (Denmark)

    Reber, Rolf; Christensen, Bo T.; Meier, Beat

    2014-01-01

    Research has shown that people judge words as having bigger font size than non-words. This finding has been interpreted in terms of processing fluency, with higher fluency leading to judgments of bigger size. If so, symmetric numbers (e.g., 44) which can be processed more fluently are predicted...

  19. Polychaete Annelid Biomass Size Spectra: The Effects of Hypoxia Stress

    Directory of Open Access Journals (Sweden)

    Fangyuan Qu

    2015-01-01

    Full Text Available Quantitative benthic samples were taken during spring and summer at three locations on the Louisiana continental shelf from 2004 to 2012 to assess the influence of hypoxia on the mean sizes (wet weight of polychaete annelid worms. While the mean body size over the entire study of 64 samples was 3.99 ± 4.66 mg wet weight per individual, the mean ranged from 2.97 ± 2.87 mg during consistently hypoxic conditions (2 mg/L. The variations in size within assemblages were estimated from conventional biomass size spectra (BSS and normalized biomass size spectra (NBSS across a broad range of oxygen concentrations. The decline in size was due to the elimination of large species under hypoxic conditions (<2 mg/L, not a reduction in size within species. At “severe” levels of hypoxia (<1 mg/L, the smallest species also declined in abundance, whereas the ubiquitous “medium-sized” Paraprionospio pinnata flourished. These results suggest that there will be enhanced selection for small sizes and species with enlarged branchial palps such as those in P. pinnata if, as predicted, hypoxia becomes more commonplace in time and space worldwide.

  20. An evaluation testing technique of single event effect using Beam Blanking SEM

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, J.; Hada, T.; Pesce, A.; Akutsu, T.; Matsuda, S. [National Space Development Agency of Japan, Tsukuba, Ibaraki (Japan). Tsukuba Space Center; Igarashi, T.; Baba, S.

    1997-03-01

    Beam Blanking SEM (Scanning Electron Microscope) testing technique has been applied to CMOS SRAM devices to evaluate the occurence of soft errors on memory cells. Cross-section versus beam current and LET curves derived from BBSEM and heavy ion testing technique, respectively, have been compared. A linear relation between BBSEM current and heavy ion LET has been found. The purpose of this study was to demonstrate that the application of focused pulsed electron beam could be a reliable, convenient and inexpensive tool to investigate the effects of heavy ions and high energy particles on memory devices for space application. (author)