WorldWideScience

Sample records for propagation electronic levels

  1. Electron Beam Propagation in a Plasma

    Directory of Open Access Journals (Sweden)

    Kyoung W. Min

    1988-06-01

    Full Text Available Electron beam propagation in a fully ionized plasma has been studied using a one-dimensional particle simulation model. We compare the results of electrostatic simulations to those of electromagnetic simulations. The electrostatic results show the essential features of beam-plasma instability which accelerates ambient plasmas. The results also show the heating of ambient plasmas and the trapping of plasmas due to the locally generated electric field. The level of the radiation generated by the same non-relativistic beam is slightly higher than the noise level. We discuss the results in context of the heating of coronal plasma during solar flares.

  2. Light propagation and interaction observed with electrons

    Energy Technology Data Exchange (ETDEWEB)

    Word, Robert C.; Fitzgerald, J.P.S.; Könenkamp, R., E-mail: rkoe@pdx.edu

    2016-01-15

    We discuss possibilities for a microscopic optical characterization of thin films and surfaces based on photoemission electron microscopy. We show that propagating light with wavelengths across the visible range can readily be visualized, and linear and non-linear materials properties can be evaluated non-invasively with nanometer spatial resolution. While femtosecond temporal resolution can be achieved in pump-probe-type experiments, the interferometric approach presented here has typical image frame times of ~200 fs. - Highlights: • Non-linear photoemission electron micrographs are analyzed. • Optical properties of transparent and metallic thin films are determined. • Light propagation, surface plasmon resonances and energy transfer are discussed.

  3. Intense relativistic electron beam: generation and propagation

    International Nuclear Information System (INIS)

    Mittal, K.C.; Mondal, J.

    2010-01-01

    A general review of relativistic electron beam extracted from explosive field emission diode has been presented here. The beam current in the diode gap taking into account cathode and anode plasma expansion velocity and excluding the self magnetic field effect is directly proportional to gap voltage V 3/2 and inversely proportional to the square of the effective diode gap (d-vt). In the limit of high current, self magnetic field focusing effect comes into play and results in a critical current at which pinching will take place. When the diode current exceeds the critical current, the electron flow is in the para-potential regime. Different diode geometries such as planner, coaxial, rod-pinched, reflex triode are discussed qualitatively. When the beam is injected into a vacuum drift tube the propagation of the beam is only possible in presence of a strong axial magnetic field which prevents the beam expansion in the radial direction. If the beam is injected in the drift tube filled with dense plasma, then the redistribution of the plasma electrons effectively neutralizes the beam space charge, resulting subsequent propagation of the beam along the drift tube. The beam propagation through neutral gas is similar to the plasma filled drift tube. In this case both the neutral gas pressure and the beam current regulate the transmission of the REB. (author)

  4. Modeling paraxial wave propagation in free-electron laser oscillators

    NARCIS (Netherlands)

    Karssenberg, J.G.; van der Slot, Petrus J.M.; Volokhine, I.; Verschuur, Jeroen W.J.; Boller, Klaus J.

    2006-01-01

    Modeling free-electron laser (FEL) oscillators requires calculation of both the light-beam interaction within the undulator and the light propagation outside the undulator. We have developed a paraxial optical propagation code that can be combined with various existing models of gain media, for

  5. Stable propagation of an electron beam in gas

    International Nuclear Information System (INIS)

    Lee, E.P.; Chambers, F.W.; Lodestro, L.L.; Yu, S.S.

    1977-01-01

    Conditions for the stable propagation of a pinched electron beam in low pressure gas (p approximately 0.1 to 100 torr) are described. The observed window of good propagation around p approximately 2 torr air is interpreted as the quenching of the two-stream mode by sufficiently high plasma density and collision frequency, and the simultaneous suppression of the resistive hose mode by sufficiently rapid generation of electrical conductivity from breakdown ionization

  6. Wave propagation through an electron cyclotron resonance layer

    International Nuclear Information System (INIS)

    Westerhof, E.

    1997-01-01

    The propagation of a wave beam through an electron cyclotron resonance layer is analysed in two-dimensional slab geometry in order to assess the deviation from cold plasma propagation due to resonant, warm plasma changes in wave dispersion. For quasi-perpendicular propagation, N ' 'parallel to'' ≅ v t /c, an O-mode beam is shown to exhibit a strong wiggle in the trajectory of the centre of the beam when passing through the fundamental electron cyclotron resonance. The effects are largest for low temperatures and close to perpendicular propagation. Predictions from standard dielectric wave energy fluxes are inconsistent with the trajectory of the beam. Qualitatively identical results are obtained for the X-mode second harmonic. In contrast, the X-mode at the fundamental resonance shows significant deviations form cold plasma propagation only for strongly oblique propagation and/or high temperatures. On the basis of the obtained results a practical suggestion is made for ray tracing near electron cyclotron resonance. (Author)

  7. Propagation of three-dimensional electron-acoustic solitary waves

    International Nuclear Information System (INIS)

    Shalaby, M.; El-Sherif, L. S.; El-Labany, S. K.; Sabry, R.

    2011-01-01

    Theoretical investigation is carried out for understanding the properties of three-dimensional electron-acoustic waves propagating in magnetized plasma whose constituents are cold magnetized electron fluid, hot electrons obeying nonthermal distribution, and stationary ions. For this purpose, the hydrodynamic equations for the cold magnetized electron fluid, nonthermal electron density distribution, and the Poisson equation are used to derive the corresponding nonlinear evolution equation, Zkharov-Kuznetsov (ZK) equation, in the small- but finite- amplitude regime. The ZK equation is solved analytically and it is found that it supports both solitary and blow-up solutions. It is found that rarefactive electron-acoustic solitary waves strongly depend on the density and temperature ratios of the hot-to-cold electron species as well as the nonthermal electron parameter. Furthermore, there is a critical value for the nonthermal electron parameter, which decides whether the electron-acoustic solitary wave's amplitude is decreased or increased by changing various plasma parameters. Importantly, the change of the propagation angles leads to miss the balance between the nonlinearity and dispersion; hence, the localized pulses convert to explosive/blow-up pulses. The relevance of this study to the nonlinear electron-acoustic structures in the dayside auroral zone in the light of Viking satellite observations is discussed.

  8. Interplay of hot electrons from localized and propagating plasmons.

    Science.gov (United States)

    Hoang, Chung V; Hayashi, Koki; Ito, Yasuo; Gorai, Naoki; Allison, Giles; Shi, Xu; Sun, Quan; Cheng, Zhenzhou; Ueno, Kosei; Goda, Keisuke; Misawa, Hiroaki

    2017-10-03

    Plasmon-induced hot-electron generation has recently received considerable interest and has been studied to develop novel applications in optoelectronics, photovoltaics and green chemistry. Such hot electrons are typically generated from either localized plasmons in metal nanoparticles or propagating plasmons in patterned metal nanostructures. Here we simultaneously generate these heterogeneous plasmon-induced hot electrons and exploit their cooperative interplay in a single metal-semiconductor device to demonstrate, as an example, wavelength-controlled polarity-switchable photoconductivity. Specifically, the dual-plasmon device produces a net photocurrent whose polarity is determined by the balance in population and directionality between the hot electrons from localized and propagating plasmons. The current responsivity and polarity-switching wavelength of the device can be varied over the entire visible spectrum by tailoring the hot-electron interplay in various ways. This phenomenon may provide flexibility to manipulate the electrical output from light-matter interaction and offer opportunities for biosensors, long-distance communications, and photoconversion applications.Plasmon-induced hot electrons have potential applications spanning photodetection and photocatalysis. Here, Hoang et al. study the interplay between hot electrons generated by localized and propagating plasmons, and demonstrate wavelength-controlled polarity-switchable photoconductivity.

  9. Pulse propagation in tapered wiggler free electron lasers

    International Nuclear Information System (INIS)

    Goldstein, J.C.; Colson, W.B.

    1981-01-01

    The one-dimensional theory of short pulse propagation in free electron lasers is extended to tapered wiggler devices and is used to study the behavior of an oscillator with parameter values close to those expected in forthcoming experiments. It is found that stable laser output is possible only over a small range of optical cavity lengths. Optical pulse characteristcs are presented and are found to change considerably over this range

  10. Nanosecond air breakdown parameters for electron and microwave beam propagation

    International Nuclear Information System (INIS)

    Ali, A.W.

    1988-01-01

    Air breakdown by avalanche ionization plays an important role in the electron beam and microwave propagations. For high electric fields and short pulse applications one needs avalanche ionization parameters for modeling and scaling of experimental devices. However, the breakdown parameters, i.e., the ionization frequency vs E/p (volt. cm -1 . Torr -1 ) in air is uncertain for very high values of E/P. A review is given of the experimental data for the electron drift velocity, the Townsend ionization coefficient in N 2 and O 2 and the ionization frequency and the collision frequency for momentum transfer in air are developed. (author)

  11. Measurements on wave propagation characteristics of spiraling electron beams

    Science.gov (United States)

    Singh, A.; Getty, W. D.

    1976-01-01

    Dispersion characteristics of cyclotron-harmonic waves propagating on a neutralized spiraling electron beam immersed in a uniform axial magnetic field are studied experimentally. The experimental setup consisted of a vacuum system, an electron-gun corkscrew assembly which produces a 110-eV beam with the desired delta-function velocity distribution, a measurement region where a microwave signal is injected onto the beam to measure wavelengths, and a velocity analyzer for measuring the axial electron velocity. Results of wavelength measurements made at beam currents of 0.15, 1.0, and 2.0 mA are compared with calculated values, and undesirable effects produced by increasing the beam current are discussed. It is concluded that a suitable electron beam for studies of cyclotron-harmonic waves can be generated by the corkscrew device.

  12. Thermal effects on parallel-propagating electron cyclotron waves

    International Nuclear Information System (INIS)

    Robinson, P.A.

    1987-01-01

    Thermal effects on the dispersion of right-handed electron cyclotron waves propagating parallel to a uniform, ambient magnetic field are investigated in the strictly non-relativistic ('classical') and weakly relativistic approximations for real frequency and complex wave vector. In each approximation, the two branches of the RH mode reconnect near the cyclotron frequency as the plasma temperature is increased or the density is lowered. This reconnection occurs in a manner different from that previously assumed at parallel propagation and from that at perpendicular propagation, giving rise to a new mode near the cold plasma cut-off frequency ωsub(xC). For both parallel and perpendicular propagation, it is noted that reconnection occurs approximately when the cyclotron linewidth equals the width of the stop-band in the cold plasma dispersion relation. Inclusion of weakly relativistic effects is found to be necessary for quantitative calculations and for an accurate treatment of the new mode near ωsub(xC). Weakly relativistic effects also modify the analytic properties of the dispersion relation so as to introduce a new family of weakly damped and undamped solutions. (author)

  13. Oblique propagation of electron thermal modes below the electron plasma frequency without boundary effects

    International Nuclear Information System (INIS)

    Ohnuma, T.; Watanabe, T.; Sanuki, H.

    1981-08-01

    Propagation characteristics and refractive effects of an oblique electron thermal mode without boundary effects below the electron plasma frequency are studied experimentally and theoretically in an inhomogeneous magnetized plasma. The behavior of this mode observed experimentally was confirmed by the theoretical analysis based on a new type of ray theory. (author)

  14. Temporal Talbot effect in propagation of attosecond electron waves

    International Nuclear Information System (INIS)

    Varro, S.

    2010-01-01

    Complete text of publication follows. The rapid development in extreme strong-field and extreme short-pulse laser physics provide us with many potentials to explore the dynamics of fundamental processes taking place in light-matter interactions and in propagation of electromagnetic or matter waves. The present paper discusses the propagation of above-threshold electron waves generated by (not necessary ultra-short) strong laser fields. Recently we have shown that - in analogy with the formation of attosecond light pulses by interference of high-order harmonics - the wave components of photoelectrons are naturally assembled in attosecond spikes, through the Fourier synthesis of these de Broglie waves. We would like to emphasize that the proposed scheme does not presupposes an a priori ultrashort excitation. Owing to the inherent dispersion of electron waves even in vacuum, the clean attosecond structure (emanating perpendicularly from a metal target surface) is gradually spoiled due to destructive interference. Fortunately the collapsed fine structure recovers itself at certain distances from the source within well-defined 'revival layers'. This is a temporal analogon of the optical Talbot effect representing the self-imaging of a grating, which is illuminated by stationary plane waves, in the near field. The 'collaps bands' and the 'revival layers' introduced in ref. 3 have been found merely on the basis of some attosecond layers turned out to show certain regularities. In the meantime we have derived approximate analytic formulae for the propagation characteristics, with the help of which we can keep track of the locations of the 'collaps bands' and the 'revival layers' on a larger scale. We shall report on these semiclassical results, and also discuss their possible connection with the recently found entropy remnants in multiphoton Compton scattering by electronic wave packets. Acknowledgement. This work has been supported by the Hungarian National Scientific

  15. Can Electron Propagator Methods Be Used To Improve Polarization Propagator Methods?

    DEFF Research Database (Denmark)

    Jensen, Hans Jørgen Aagaard

    2008-01-01

    Calculations of Rydberg excitation energies with the second-order polarization propagator approximation (SOPPA) often produce results which are more in error than the random phase approximation (RPA), which formally is the first-order model. This is obviously because of cancellation of errors...... at the RPA level. On the other hand, valence excitation energies behave as expected, and they are systematically improved in SOPPA compared to RPA. Note that a Rydberg series is related to one of the ionization thresholds of the molecule, and it is thus obvious that a good description of the ionization...

  16. The propagation of high power CW scanning electron beam in air

    International Nuclear Information System (INIS)

    Korenev, Sergey; Korenev, Ivan

    2002-01-01

    The question of propagation of high power electron beam in air presents the scientific and applied interests. The high power (80 kW) CW electron accelerator 'Rhodotron' with kinetic energy of electrons 5 and 10 MeV was used in the experiments. The experimental results for propagation of scanning electron beams in air are presented and discussed

  17. Analytic model of electron pulse propagation in ultrafast electron diffraction experiments

    International Nuclear Information System (INIS)

    Michalik, A.M.; Sipe, J.E.

    2006-01-01

    We present a mean-field analytic model to study the propagation of electron pulses used in ultrafast electron diffraction experiments (UED). We assume a Gaussian form to characterize the electron pulse, and derive a system of ordinary differential equations that are solved quickly and easily to give the pulse dynamics. We compare our model to an N-body numerical simulation and are able to show excellent agreement between the two result sets. This model is a convenient alternative to time consuming and computationally intense N-body simulations in exploring the dynamics of UED electron pulses, and as a tool for refining UED experimental designs

  18. APC-II: an electron beam propagation code

    International Nuclear Information System (INIS)

    Iwan, D.C.; Freeman, J.R.

    1984-05-01

    The computer code APC-II simulates the propagation of a relativistic electron beam through air. APC-II is an updated version of the APC envelope model code. It incorporates an improved conductivity model which significantly extends the range of stable calculations. A number of test cases show that these new models are capable of reproducing the simulations of the original APC code. As the result of a major restructuring and reprogramming of the code, APC-II is now friendly to both the occasional user and the experienced user who wishes to make modifications. Most of the code is in standard ANS-II Fortran 77 so that it can be easily transported between machines

  19. Ignition and burn propagation with suprathermal electron auxiliary heating

    International Nuclear Information System (INIS)

    Han Shensheng; Wu Yanqing

    2000-01-01

    The rapid development in ultrahigh-intensity lasers has allowed the exploration of applying an auxiliary heating technique in inertial confinement fusion (ICF) research. It is hoped that, compared with the 'standard fast ignition' scheme, raising the temperature of a hot-spot over the ignition threshold based on the shock-heated temperature will greatly reduce the required output energy of an ignition ultrahigh-intensity pulse. One of the key issues in ICF auxiliary heating is: how can we transport the exogenous energy efficiently into the hot-spot of compressed DT fuel? A scheme is proposed with three phases. First, a partial-spherical-shell capsule, such as double-conical target, is imploded as in the conventional approach to inertial fusion to assemble a high-density fuel configuration with a hot-spot of temperature lower than the ignition threshold. Second, a hole is bored through the shell outside the hot-spot by suprathermal electron explosion boring. Finally, the fuel is ignited by suprathermal electrons produced in the high-intensity ignition laser-plasma interactions. Calculations with a simple hybrid model show that the new scheme can possibly lead to ignition and burn propagation with a total drive energy of a few tens of kilojoules and an output energy as low as hundreds of joules for a single ignition ultrahigh-intensity pulse. (author)

  20. Propagation of a laser-driven relativistic electron beam inside a solid dielectric.

    Science.gov (United States)

    Sarkisov, G S; Ivanov, V V; Leblanc, P; Sentoku, Y; Yates, K; Wiewior, P; Chalyy, O; Astanovitskiy, A; Bychenkov, V Yu; Jobe, D; Spielman, R B

    2012-09-01

    Laser probe diagnostics: shadowgraphy, interferometry, and polarimetry were used for a comprehensive characterization of ionization wave dynamics inside a glass target induced by a laser-driven, relativistic electron beam. Experiments were done using the 50-TW Leopard laser at the University of Nevada, Reno. We show that for a laser flux of ∼2 × 10(18) W/cm2 a hemispherical ionization wave propagates at c/3 for 10 ps and has a smooth electron-density distribution. The maximum free-electron density inside the glass target is ∼2 × 10(19) cm-3, which corresponds to an ionization level of ∼0.1%. Magnetic fields and electric fields do not exceed ∼15 kG and ∼1 MV/cm, respectively. The electron temperature has a hot, ringlike structure with a maximum of ∼0.7 eV. The topology of the interference phase shift shows the signature of the "fountain effect", a narrow electron beam that fans out from the propagation axis and heads back to the target surface. Two-dimensional particle-in-cell (PIC) computer simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields driven by laser. The very low ionization observed after the laser heating pulse suggests a fast recombination on the sub-ps time scale.

  1. Storage ring free electron laser, pulse propagation effects and microwave type instabilities

    International Nuclear Information System (INIS)

    Dattoli, G.; Mezi, L.; Renieri, A.; Migliorati, M.

    2000-01-01

    It has been developed a dynamical model accounting for the storage Ring Free Electron Laser evolution including pulse propagation effects and e-beam instabilities of microwave type. It has been analyzed the general conditions under which the on set of the laser may switch off the instability and focus everybody attention on the interplay between cavity mismatch, laser pulsed behavior and e-beam instability dynamics. Particular attention is also devoted to the laser operation in near threshold conditions, namely at an intracavity level just enough to counteract the instability, that show in this region new and interesting effects arises [it

  2. Symbolic Algebra Development for Higher-Order Electron Propagator Formulation and Implementation.

    Science.gov (United States)

    Tamayo-Mendoza, Teresa; Flores-Moreno, Roberto

    2014-06-10

    Through the use of symbolic algebra, implemented in a program, the algebraic expression of the elements of the self-energy matrix for the electron propagator to different orders were obtained. In addition, a module for the software package Lowdin was automatically generated. Second- and third-order electron propagator results have been calculated to test the correct operation of the program. It was found that the Fortran 90 modules obtained automatically with our algorithm succeeded in calculating ionization energies with the second- and third-order electron propagator in the diagonal approximation. The strategy for the development of this symbolic algebra program is described in detail. This represents a solid starting point for the automatic derivation and implementation of higher-order electron propagator methods.

  3. The influence of the edge density fluctuations on electron cyclotron wave beam propagation in tokamaks

    DEFF Research Database (Denmark)

    Bertelli, N.; Balakin, A.A.; Westerhof, E.

    2010-01-01

    are estimated in a vacuum beam propagation between the edge density layer and the EC resonance absorption layer. Consequences on the EC beam propagation are investigated by using a simplified model in which the density fluctuations are described by a single harmonic oscillation. In addition, quasi......A numerical analysis of the electron cyclotron (EC) wave beam propagation in the presence of edge density fluctuations by means of a quasi-optical code [Balakin A. A. et al, Nucl. Fusion 48 (2008) 065003] is presented. The effects of the density fluctuations on the wave beam propagation...

  4. Lateral propagation of MeV electrons generated by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Seely, J. F.; Szabo, C. I.; Audebert, P.; Brambrink, E.; Tabakhoff, E.; Hudson, L. T.

    2010-01-01

    The propagation of MeV electrons generated by intense (≅10 20 W/cm 2 ) femtosecond laser irradiation, in the lateral direction perpendicular to the incident laser beam, was studied using targets consisting of irradiated metal wires and neighboring spectator wires embedded in electrically conductive (aluminum) or resistive (Teflon) substrates. The K shell spectra in the energy range 40-60 keV from wires of Gd, Dy, Hf, and W were recorded by a transmission crystal spectrometer. The spectra were produced by 1s electron ionization in the irradiated wire and by energetic electron propagation through the substrate material to the spectator wire of a different metal. The electron range and energy were determined from the relative K shell emissions from the irradiated and spectator wires separated by varying substrate lateral distances of up to 1 mm. It was found that electron propagation through Teflon was inhibited, compared to aluminum, implying a relatively weak return current and incomplete space-charge neutralization. The energetic electron propagation in the direction parallel to the electric field of the laser beam was larger than perpendicular to the electric field. Energetic electron production was lower when directly irradiating aluminum or Teflon compared to irradiating the heavy metal wires. These experiments are important for the determination of the energetic electron production mechanism and for understanding lateral electron propagation that can be detrimental to fast-ignition fusion and hard x-ray backlighter radiography.

  5. Propagation of a nonrelativistic electron beam in a plasma in a magnetic field

    International Nuclear Information System (INIS)

    Okuda, H.; Horton, R.; Ono, M.; Ashour-Abdalla, M.

    1986-10-01

    Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam-plasma interaction on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity

  6. Influence of superthermal electrons on obliquely propagating ion-acoustic solitons in magnetized plasmas

    International Nuclear Information System (INIS)

    Kadijani, M Nouri; Abbasi, H; Pajouh, H Hakimi

    2011-01-01

    The effect of superthermal electrons, modeled by a Lorentzian velocity distribution function, on the oblique propagation characteristics of linear and nonlinear ion-acoustic waves in an electron-ion plasma in the presence of a uniform external magnetic field is investigated. First, the linear dispersion relations of the fast and slow modes are obtained. It is shown that the superthermal electrons make both modes propagate with smaller phase velocities. Then, the Korteweg-de Vries equation describing the propagation of nonlinear slow and fast ion-acoustic waves is derived. It is shown that the presence of superthermal electrons has a significant influence on the nature of magnetized ion-acoustic solitons. That is, for a larger population of the superthermal electrons, the soliton velocity of both modes in the laboratory frame significantly decreases and the soliton are slimmer, and on approaching the Maxwellian limit, the width becomes maximum.

  7. Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Herrero, Raúl; Hidalgo, Miguel A.; Carcaboso, Fernando; Blanco, Juan J. [Dpto. de Física y Matemáticas, Universidad de Alcalá, E-28871 Alcalá de Henares, Madrid (Spain); Dresing, Nina; Klassen, Andreas; Heber, Bernd [Institut für Experimentelle und Angewandte Physik, University of Kiel, D-24118, Kiel (Germany); Temmer, Manuela; Veronig, Astrid [Institute of Physics/Kanzelhöhe Observatory, University of Graz, A-8010 Graz (Austria); Bučík, Radoslav [Institut für Astrophysik, Georg-August-Universität Göttingen, D-37077, Göttingen (Germany); Lario, David, E-mail: raul.gomezh@uah.es [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States)

    2017-05-10

    On 2013 December 2 and 3, the SEPT and STE instruments on board STEREO-A observed two solar energetic electron events with unusual sunward-directed fluxes. Both events occurred during a time interval showing typical signatures of interplanetary coronal mass ejections (ICMEs). The electron timing and anisotropies, combined with extreme-ultraviolet solar imaging and radio wave spectral observations, are used to confirm the solar origin and the injection times of the energetic electrons. The solar source of the ICME is investigated using remote-sensing observations and a three-dimensional reconstruction technique. In situ plasma and magnetic field data combined with energetic electron observations and a flux-rope model are used to determine the ICME magnetic topology and the interplanetary electron propagation path from the Sun to 1 au. Two consecutive flux ropes crossed the STEREO-A location and each electron event occurred inside a different flux rope. In both cases, the electrons traveled from the solar source to 1 au along the longest legs of the flux ropes still connected to the Sun. During the December 2 event, energetic electrons propagated along the magnetic field, while during the December 3 event they were propagating against the field. As found by previous studies, the energetic electron propagation times are consistent with a low number of field line rotations N < 5 of the flux rope between the Sun and 1 au. The flux rope model used in this work suggests an even lower number of rotations.

  8. Lateral propagation of fast electrons at the laser-irradiated target surfaces

    International Nuclear Information System (INIS)

    Li, Y T; Lin, X X; Liu, B C; Du, F; Wang, S J; Li, C; Zhou, M L; Zhang, L; Liu, X; Wang, J; Liu, X L; Chen, L M; Wang, Z H; Ma, J L; Wei, Z Y; Zhang, J; Liu, F; Liu, F

    2010-01-01

    Lateral propagation of fast electrons at the target surfaces irradiated by femtosecond intense laser pulses is measured by k α x-ray imaging technique when a preplasma is presented. An annular halo surrounding a bright spot is observed in the x-ray images when the scale length of the electron density is large. For an incidence angle of 70 0 the x-ray images show a non-symmetrical distribution peaked to the laser propagation direction. The x-ray photons in the halo are mainly excited by the fast electrons that flow in the preplasma when their paths intersect the high density regions near the target surface.

  9. One-electron propagation in Fermi, Pasta, Ulam disordered chains with Gaussian acoustic pulse pumping

    Science.gov (United States)

    Silva, L. D. Da; Dos Santos, J. L. L.; Ranciaro Neto, A.; Sales, M. O.; de Moura, F. A. B. F.

    In this work, we consider a one-electron moving on a Fermi, Pasta, Ulam disordered chain under effect of electron-phonon interaction and a Gaussian acoustic pulse pumping. We describe electronic dynamics using quantum mechanics formalism and the nonlinear atomic vibrations using standard classical physics. Solving numerical equations related to coupled quantum/classical behavior of this system, we study electronic propagation properties. Our calculations suggest that the acoustic pumping associated with the electron-lattice interaction promote a sub-diffusive electronic dynamics.

  10. Electron thermal conductivity from heat wave propagation in Wendelstein 7-AS

    Energy Technology Data Exchange (ETDEWEB)

    Giannone, L.; Erckmann, V; Gasparino, U; Hartfuss, H J; Kuehner, G; Maassberg, H; Stroth, U; Tutter, M [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); W7-AS Team; ECRH Group IPF Stuttgart; Gyrotron Group KFK Karlsruhe

    1992-11-01

    Heat wave propagation experiments have been carried out on the Wendelstein 7-AS stellarator. The deposition of electron cyclotron resonance heating power is highly localized in the plasma centre, so that power modulation produces heat waves which propagate away from the deposition volume. Radiometry of the electron cyclotron emission is used to measure the generated temperature perturbation. The propagation time delay of the temperature perturbation as a function of distance to the power deposition region is used to determine the electron thermal conductivity [chi][sub e]. This value is then compared with the value determined by global power balance. In contrast to sawtooth propagation experiments in tokamaks, it is found that the value of [chi][sub e] from heat wave propagation is comparable to that calculated by power balance. In addition, inward propagating waves were produced by choosing a power deposition region away from the plasma centre. Experiments were carried out at 70 GHz in the ordinary mode and at 140 GHz in the extraordinary mode. Variations of the modulation power amplitude have demonstrated that the inferred value of [chi][sub e] is independent of the amplitude of the induced temperature perturbations. (author). 29 refs, 11 figs, 5 tabs.

  11. RADLAC II high current electron beam propagation experiment

    International Nuclear Information System (INIS)

    Frost, C.A.; Shope, S.L.; Mazarakis, M.G.; Poukey, J.W.; Wagner, J.S.; Turman, B.N.; Crist, C.E.; Welch, D.R.; Struve, K.W.

    1993-01-01

    The resistive hose instability of an electron beam was observed to be convective in recent RADLAC II experiments for higher current shots. The effects of air scattering for these shots were minimal. These experiments and theory suggest low-frequency hose motion which does not appear convective may be due to rapid expansion and subsequent drifting of the beam nose

  12. Wave Propagation From Electrons to Photonic Crystals and Left-Handed Materials

    CERN Document Server

    Markos, Peter

    2010-01-01

    This textbook offers the first unified treatment of wave propagation in electronic and electromagnetic systems and introduces readers to the essentials of the transfer matrix method, a powerful analytical tool that can be used to model and study an array of problems pertaining to wave propagation in electrons and photons. It is aimed at graduate and advanced undergraduate students in physics, materials science, electrical and computer engineering, and mathematics, and is ideal for researchers in photonic crystals, negative index materials, left-handed materials, plasmonics, nonlinear effects,

  13. Complex-valued derivative propagation method with approximate Bohmian trajectories: Application to electronic nonadiabatic dynamics

    Science.gov (United States)

    Wang, Yu; Chou, Chia-Chun

    2018-05-01

    The coupled complex quantum Hamilton-Jacobi equations for electronic nonadiabatic transitions are approximately solved by propagating individual quantum trajectories in real space. Equations of motion are derived through use of the derivative propagation method for the complex actions and their spatial derivatives for wave packets moving on each of the coupled electronic potential surfaces. These equations for two surfaces are converted into the moving frame with the same grid point velocities. Excellent wave functions can be obtained by making use of the superposition principle even when nodes develop in wave packet scattering.

  14. Injection and propagation of a nonrelativistic electron beam and spacecraft charging

    International Nuclear Information System (INIS)

    Okuda, H.; Berchem, J.

    1987-05-01

    Two-dimensional numerical simulations have been carried out in order to study the injection and propagation of a nonrelativistic electron beam from a spacecraft into a fully ionized plasma in a magnetic field. Contrary to the earlier results in one-dimension, a high density electron beam whose density is comparable to the ambient density can propagate into a plasma. A strong radial electric field resulting from the net charges in the beam causes the beam electrons to spread radially reducing the beam density. When the injection current exceeds the return current, significant charging of the spacecraft is observed along with the reflection of the injected electrons back to the spacecraft. Recent data on the electron beam injection from the Spacelab 1 (SEPAC) are discussed

  15. The influence of the edge density fluctuations on electron cyclotron wave beam propagation in tokamaks

    International Nuclear Information System (INIS)

    Bertelli, N; Balakin, A A; Westerhof, E; Garcia, O E; Nielsen, A H; Naulin, V

    2010-01-01

    A numerical analysis of the electron cyclotron (EC) wave beam propagation in the presence of edge density fluctuations by means of a quasi-optical code [Balakin A. A. et al, Nucl. Fusion 48 (2008) 065003] is presented. The effects of the density fluctuations on the wave beam propagation are estimated in a vacuum beam propagation between the edge density layer and the EC resonance absorption layer. Consequences on the EC beam propagation are investigated by using a simplified model in which the density fluctuations are described by a single harmonic oscillation. In addition, quasi-optical calculations are shown by using edge density fluctuations as calculated by two-dimensional interchange turbulence simulations and validated with the experimental data [O. E. Garcia et al, Nucl. Fusion 47 (2007) 667].

  16. Arbitrary amplitude electrostatic wave propagation in a magnetized dense plasma containing helium ions and degenerate electrons

    Science.gov (United States)

    Mahmood, S.; Sadiq, Safeer; Haque, Q.; Ali, Munazza Z.

    2016-06-01

    The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found which depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.

  17. Propagation of Dirac electrons in Cantor graphene multilayers

    International Nuclear Information System (INIS)

    Rodríguez-González, R.; Martínez-Orozco, J. C.; Madrigal-Melchor, J.; Rodríguez-Vargas, I.

    2014-01-01

    In this work we use the standard T-matrix method to study the tunneling of Dirac electrons through graphene multilayers. A graphene sheet is deposited on top of slabs of Silicon-Oxide (SiO 2 ) and Silicon-Carbide (SiC) substrates, in which we applied the Cantor’s series. We calculate the transmittance as a function of energy for different incident angles and different generations of the Cantor’s series. Comparing the transmittance, we found three types of self-similarity: (a) local - into generations, (b) between incident angles and (c) between generations. We also compute the angular distribution of the transmittance for fixed energies finding a self-similar pattern between generations. To our knowledge is the first time that four different self-similar patterns are presented in Cantor-based multilayers

  18. Propagation of Dirac electrons in Cantor graphene multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-González, R.; Martínez-Orozco, J. C.; Madrigal-Melchor, J.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)

    2014-05-15

    In this work we use the standard T-matrix method to study the tunneling of Dirac electrons through graphene multilayers. A graphene sheet is deposited on top of slabs of Silicon-Oxide (SiO{sub 2}) and Silicon-Carbide (SiC) substrates, in which we applied the Cantor’s series. We calculate the transmittance as a function of energy for different incident angles and different generations of the Cantor’s series. Comparing the transmittance, we found three types of self-similarity: (a) local - into generations, (b) between incident angles and (c) between generations. We also compute the angular distribution of the transmittance for fixed energies finding a self-similar pattern between generations. To our knowledge is the first time that four different self-similar patterns are presented in Cantor-based multilayers.

  19. Study on the intense relativistic electron beam propagation in a collisionless plasma of small density

    International Nuclear Information System (INIS)

    Korenev, S.A.; Rubin, N.B.; Khodataev, K.V.

    1982-01-01

    The results of the experimental studies of the intense relativistic electron beam (IREB) propagation with ν/γ approximately 0.1, and γ approximately 1.6 (γ is an electron beam relativistic factor) in a collisionless plasma of small density over the 180 cm length are presented. Plasma is generated with the incomplete discharge over dielectric surface at the residual gas pressure of P approximately 10 -5 Torr. It is shown that the transportation efficiency may be essentially high, if the electron concentration in plasma satisfies the equilibrium conditions and if it is less or equal to the electron concentration in a beam. At concentration less than optimum one, the transportation efficiency decreases due to violations of equilibrium conditions. At high concentration the transportation efficiency also decreased due to the scattering and breaking on excited small-scale and plasma oscillations. The IREB propagation occurs without essential time delay under optimum conditions

  20. Intense electron-beam propagation in low-density gases using PHERMEX

    International Nuclear Information System (INIS)

    Moir, D.C.; Newberger, B.S.; Thode, L.E.

    1980-01-01

    Preliminary propagation experiments have been performed using the LASL-PHERMEX 21-MeV electron beam with current densities of 40 kA/cm 2 . Gas densities are varied from 10-m torr to 580 torr. Results indicate the presence of microinstabilities

  1. Resonant tunneling assisted propagation and amplification of plasmons in high electron mobility transistors

    International Nuclear Information System (INIS)

    Bhardwaj, Shubhendu; Sensale-Rodriguez, Berardi; Xing, Huili Grace; Rajan, Siddharth; Volakis, John L.

    2016-01-01

    A rigorous theoretical and computational model is developed for the plasma-wave propagation in high electron mobility transistor structures with electron injection from a resonant tunneling diode at the gate. We discuss the conditions in which low-loss and sustainable plasmon modes can be supported in such structures. The developed analytical model is used to derive the dispersion relation for these plasmon-modes. A non-linear full-wave-hydrodynamic numerical solver is also developed using a finite difference time domain algorithm. The developed analytical solutions are validated via the numerical solution. We also verify previous observations that were based on a simplified transmission line model. It is shown that at high levels of negative differential conductance, plasmon amplification is indeed possible. The proposed rigorous models can enable accurate design and optimization of practical resonant tunnel diode-based plasma-wave devices for terahertz sources, mixers, and detectors, by allowing a precise representation of their coupling when integrated with other electromagnetic structures

  2. Wave propagation and absorption in the electron cyclotron frequency range for TCA and TCV machines

    International Nuclear Information System (INIS)

    Cardinali, A.

    1990-01-01

    The main theoretical aspects of the propagation and absorption of electron cyclotron frequency waves are reviewed and applied to TCA and TCV tokamak plasmas. In particular the electromagnetic cold dispersion relation is solved analytically and numerically in order to recall the basic properties of mode propagation and to calculate the ray-trajectories by means of geometric optics. A numerical code which integrates the coupled first order differential ray-equations, has been developed and applied to the cases of interest. (author) 4 figs., 23 refs

  3. Propagation of electromagnetic waves in the plasma near electron cyclotron resonance: Undulator-induced transparency

    International Nuclear Information System (INIS)

    Shvets, G.; Tushentsov, M.; Tokman, M.D.; Kryachko, A.

    2005-01-01

    Propagation of electromagnetic waves in magnetized plasma near the electron cyclotron frequency can be strongly modified by adding a weak magnetic undulator. For example, both right- and left-hand circularly polarized waves can propagate along the magnetic field without experiencing resonant absorption. This effect of entirely eliminating electron cyclotron heating is referred to as the undulator-induced transparency (UIT) of the plasma, and is the classical equivalent of the well-known quantum mechanical effect of electromagnetically induced transparency. The basics of UIT are reviewed, and various ways in which UIT can be utilized to achieve exotic propagation properties of electromagnetic waves in plasmas are discussed. For example, UIT can dramatically slow down the waves' group velocity, resulting in the extreme compression of the wave energy in the plasma. Compressed waves are polarized along the propagation direction, and can be used for synchronous electron or ion acceleration. Strong coupling between the two wave helicities are explored to impart the waves with high group velocities ∂ω/∂k for vanishing wave numbers k. Cross-helicity coupling for realistic density and magnetic field profiles are examined using a linearized fluid code, particle-in-cell simulations, and ray-tracing WKB calculations

  4. Propagation of a nonrelativistic electron beam in a plasma in a magnetic field

    International Nuclear Information System (INIS)

    Okuda, H.; Horton, R.; Ono, M.; Ashour-Abdalla, M.

    1987-01-01

    Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam--plasma interaction on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity. This rapid diffusion takes place within a several amplification length of the beam--plasma instability given by (ω/sub p/ω 2 /sub b/) -1 /sup // 3 V 0 , where ω/sub p/, ω/sub b/, and V 0 are the target plasma, beam--plasma frequencies, and the beam drift speed. This plateaulike distribution, however, becomes unstable as the high energy tail electrons free-stream, generating a secondary beam. A similar process is observed to take place for the case of continuous beam injection when the beam density is small compared with the total density n/sub b//n/sub t/<1. In particular, the electron velocity distribution is found monotonically decreasing in energy, having a high energy tail whose energy reaches twice the initial beam energy. Such an electron distribution is also seen in laboratory experiments and in computer simulations performed for a uniform, periodic system

  5. Diffusive and convective transport modelling from analysis of ECRH-stimulated electron heat wave propagation. [ECRH (Electron Cyclotron Resonance Heating)

    Energy Technology Data Exchange (ETDEWEB)

    Erckmann, V; Gasparino, U; Giannone, L. (Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)) (and others)

    1992-01-01

    ECRH power modulation experiments in toroidal devices offer the chance to analyze the electron heat transport more conclusively: the electron heat wave propagation can be observed by ECE (or SX) leading to radial profiles of electron temperature modulation amplitude and time delay (phase shift). Taking also the stationary power balance into account, the local electron heat transport can be modelled by a combination of diffusive and convective transport terms. This method is applied to ECRH discharges in the W7-AS stellarator (B=2.5T, R=2m, a[<=]18 cm) where the ECRH power deposition is highly localized. In W7-AS, the T[sub e] modulation profiles measured by a high resolution ECE system are the basis for the local transport analysis. As experimental errors limit the separation of diffusive and convective terms in the electron heat transport for central power deposition, also ECRH power modulation experiments with off-axis deposition and inward heat wave propagation were performed (with 70 GHz o-mode as well as with 140 GHz x-mode for increased absorption). Because collisional electron-ion coupling and radiative losses are only small, low density ECRH discharges are best candidates for estimating the electron heat flux from power balance. (author) 2 refs., 3 figs.

  6. Diffusive and convective transport modelling from analysis of ECRH-stimulated electron heat wave propagation

    International Nuclear Information System (INIS)

    Erckmann, V.; Gasparino, U.; Giannone, L.

    1992-01-01

    ECRH power modulation experiments in toroidal devices offer the chance to analyze the electron heat transport more conclusively: the electron heat wave propagation can be observed by ECE (or SX) leading to radial profiles of electron temperature modulation amplitude and time delay (phase shift). Taking also the stationary power balance into account, the local electron heat transport can be modelled by a combination of diffusive and convective transport terms. This method is applied to ECRH discharges in the W7-AS stellarator (B=2.5T, R=2m, a≤18 cm) where the ECRH power deposition is highly localized. In W7-AS, the T e modulation profiles measured by a high resolution ECE system are the basis for the local transport analysis. As experimental errors limit the separation of diffusive and convective terms in the electron heat transport for central power deposition, also ECRH power modulation experiments with off-axis deposition and inward heat wave propagation were performed (with 70 GHz o-mode as well as with 140 GHz x-mode for increased absorption). Because collisional electron-ion coupling and radiative losses are only small, low density ECRH discharges are best candidates for estimating the electron heat flux from power balance. (author) 2 refs., 3 figs

  7. Propagation of a TE surface mode in a relativistic electron beam–quantum plasma system

    International Nuclear Information System (INIS)

    Abdel Aziz, M.

    2012-01-01

    The dispersion properties of a transverse electric (TE) surface waves propagating along the interface between a magneto-quantum plasma–relativistic beam system and vacuum are studied by using the quantum hydrodynamic model. The general dispersion relations are derived and analyzed in some special cases of interest. Moreover, the effects of density gradients for the beam and plasma on the dispersion properties of surface waves are investigated. The kind of dispersion relations depends strongly on the ambient magnetic field B o via the gyro-frequency ω c , the quantum parameters, and the width of the plasma layer as well as the relativistic factor for the electron beam. It is found that the quantum effects play a crucial role to facilitate the propagation of TE surface waves. -- Highlights: ► Propagation of TE surface waves on bounded magneto-quantum plasma by relativistic beam is studied. ► The quantum plasma consists of transitional layer adjacent to uniform layer. ► Influence of quantum effects on the propagation of TE surface waves are taken into account. ► Effects of homogeneity and inhomogeneity for beam on TE surface waves are considered. ► It is found that quantum effects facilitate the propagation of TE surface modes.

  8. Response to 'Comment on 'Ultrafast electron optics: Propagation dynamics of femtosecond electron packets'' [J. Appl. Phys. 94, 803 (2003)

    International Nuclear Information System (INIS)

    Siwick, Bradley J.; Dwyer, Jason R.; Jordan, Robert E.; Miller, R. J. Dwayne

    2003-01-01

    In this reply, we address the main issues raised by Qian et al. regarding our recent article [J. Appl. Phys. 92, 1643 (2002)]. In particular, we reiterate the approximations used in the development of the mean-field model and demonstrate how the form used for the on-axis potential is applicable to the study of femtosecond electron packet propagation and is not in need of correction. We also repeat our assertion that the one-dimensional (1-D) fluid model developed by Qian et al. [J. Appl. Phys. 91, 462 (2002)] overestimates space-charge-induced pulse broadening and is in qualitative disagreement with femtosecond electron packet propagation dynamics. The key differences between the mean-field and 1-D fluid model are discussed and their range of applicability is clarified

  9. Electron beam propagation in the ion-focused and resistive regimes

    International Nuclear Information System (INIS)

    Hubbard, R.F.; Lampe, M.; Fernsler, R.; Slinker, S.P.

    1993-01-01

    Pinched propagation of intense relativistic electron beams occurs in several distinct pressure regimes. In low density gases (∼ 1-100 mtorr), the beam propagates in the ion-focused regime (IFR). The beam ionizes the neutral gas, and plasma electrons are ejected, leaving behind a positive ion column which pinches the beam electrostatically. At gas densities near 1 atm, the beam-generated plasma is resistive and the pinch effect is provided by the self-magnetic field of the beam. Beam transport experiments in both regimes have been performed on the Advanced Test Accelerator (ATA) at Lawrence Livermore National Lab. and on SuperIBEX at the Naval Research Lab. IFR methods have been employed in both experiments to transport the beam prior to injection into the air and to introduce a head-to-tail taper in the beam radius. IFR simulations have shown how the resulting beam radius and emittance profiles are influenced by gas density, chamber dimensions and entrance and exit foils. Beam propagation in dense gas is subject to disruption by the resistive hose instability. However, both experiments and simulations have shown that the emittance variation introduced by IFR transport can substantially reduce the growth of the hose instability. Both experiments have also propagated beams in reduced-density channels. Simulations predict that the channel may in some cases produce a moderate stabilizing and tracking effect arising from plasma currents flowing at the edge of the channel

  10. Propagation of resist heating mask error to wafer level

    Science.gov (United States)

    Babin, S. V.; Karklin, Linard

    2006-10-01

    As technology is approaching 45 nm and below the IC industry is experiencing a severe product yield hit due to rapidly shrinking process windows and unavoidable manufacturing process variations. Current EDA tools are unable by their nature to deliver optimized and process-centered designs that call for 'post design' localized layout optimization DFM tools. To evaluate the impact of different manufacturing process variations on final product it is important to trace and evaluate all errors through design to manufacturing flow. Photo mask is one of the critical parts of this flow, and special attention should be paid to photo mask manufacturing process and especially to mask tight CD control. Electron beam lithography (EBL) is a major technique which is used for fabrication of high-end photo masks. During the writing process, resist heating is one of the sources for mask CD variations. Electron energy is released in the mask body mainly as heat, leading to significant temperature fluctuations in local areas. The temperature fluctuations cause changes in resist sensitivity, which in turn leads to CD variations. These CD variations depend on mask writing speed, order of exposure, pattern density and its distribution. Recent measurements revealed up to 45 nm CD variation on the mask when using ZEP resist. The resist heating problem with CAR resists is significantly smaller compared to other types of resists. This is partially due to higher resist sensitivity and the lower exposure dose required. However, there is no data yet showing CD errors on the wafer induced by CAR resist heating on the mask. This effect can be amplified by high MEEF values and should be carefully evaluated at 45nm and below technology nodes where tight CD control is required. In this paper, we simulated CD variation on the mask due to resist heating; then a mask pattern with the heating error was transferred onto the wafer. So, a CD error on the wafer was evaluated subject to only one term of the

  11. Strong non-radial propagation of energetic electrons in solar corona

    Science.gov (United States)

    Klassen, A.; Dresing, N.; Gómez-Herrero, R.; Heber, B.; Veronig, A.

    2018-06-01

    Analyzing the sequence of solar energetic electron events measured at both STEREO-A (STA) and STEREO-B (STB) spacecraft during 17-21 July 2014, when their orbital separation was 34°, we found evidence of a strong non-radial electron propagation in the solar corona below the solar wind source surface. The impulsive electron events were associated with recurrent flare and jet (hereafter flare/jet) activity at the border of an isolated coronal hole situated close to the solar equator. We have focused our study on the solar energetic particle (SEP) event on 17 July 2014, during which both spacecraft detected a similar impulsive and anisotropic energetic electron event suggesting optimal connection of both spacecraft to the parent particle source, despite the large angular separation between the parent flare and the nominal magnetic footpoints on the source surface of STA and STB of 68° and 90°, respectively. Combining the remote-sensing extreme ultraviolet (EUV) observations, in-situ plasma, magnetic field, and energetic particle data we investigated and discuss here the origin and the propagation trajectory of energetic electrons in the solar corona. We find that the energetic electrons in the energy range of 55-195 keV together with the associated EUV jet were injected from the flare site toward the spacecraft's magnetic footpoints and propagate along a strongly non-radial and inclined magnetic field below the source surface. From stereoscopic (EUV) observations we estimated the inclination angle of the jet trajectory and the respective magnetic field of 63° ± 11° relative to the radial direction. We show how the flare accelerated electrons reach very distant longitudes in the heliosphere, when the spacecraft are nominally not connected to the particle source. This example illustrates how ballistic backmapping can occasionally fail to characterize the magnetic connectivity during SEP events. This finding also provides an additional mechanism (one among others

  12. Storage ring free electron laser, pulse propagation effects and microwave type instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Dattoli, G.; Mezi, L.; Renieri, A. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Frascati, RM (Italy); Migliorati, M. [Rome Univ. La Sapienza, Rome (Italy). Dipt. di Energetica

    2000-07-01

    It has been developed a dynamical model accounting for the storage Ring Free Electron Laser evolution including pulse propagation effects and e-beam instabilities of microwave type. It has been analyzed the general conditions under which the on set of the laser may switch off the instability and focus everybody attention on the interplay between cavity mismatch, laser pulsed behavior and e-beam instability dynamics. Particular attention is also devoted to the laser operation in near threshold conditions, namely at an intracavity level just enough to counteract the instability, that show in this region new and interesting effects arises. [Italian] Si sviluppa un modello dinamico per la descrizione dell'evoluzione di un laser ad elettroni liberi in anello di accumulazione con l'inclusione di effetti di propagazione d'impulso e di instabilita' a microonda. Si analizzano le condizioni per le quali l'instaurarsi dell'operazione laser puo' spegnere l'instabilita' e si focalizza l'attenzione sulla connessione fra desincronismo della cavita', comportamento pulsato del laser e comportamento instabile del fascio di elettroni: si analizza in particolare l'operazione laser quando il guadagno e' prossimo alle perdite della cavita' e si osservano effetti particolarmente interessanti.

  13. Langmuir wave-packet generation from an electron beam propagating in the inhomogeneous solar wind

    International Nuclear Information System (INIS)

    Zaslavsky, A.; Maksimovic, M.; Volokitin, A. S.; Krasnoselskikh, V. V.; Bale, S. D.

    2010-01-01

    Recent in-situ observations by the TDS instrument equipping the STEREO spacecraft revealed that large amplitude spatially localized Langmuir waves are frequent in the solar wind, and correlated with the presence of suprathermal electron beams during type III events or close to the electron foreshock. We briefly present the new theoretical model used to perform the study of these localized electrostatic waves, and show first results of simulations of the destabilization of Langmuir waves by a beam propagating in the inhomogeneous solar wind. The main results are that the destabilized waves are mainly focalized near the minima of the density profiles, and that the nonlinear interaction of the waves with the resonant particles enhances this focalization compared to a situation in which the only propagation effects are taken into account.

  14. Dielectric constant and laser beam propagation in an underdense collisional plasma: effects of electron temperature

    International Nuclear Information System (INIS)

    Xia Xiongping; Qin Zhen; Xu Bin; Cai Zebin

    2011-01-01

    Dielectric constant and laser beam propagation in an underdense collisional plasma are investigated, using the wave and dielectric function equations, for their dependence on the electron temperature. Simulation results show that, due to the influence of the ponderomotive force there is a nonlinear variation of electron temperature in an underdense collisional plasma, and this leads to a complicated and interesting nonlinear variation of dielectric constant; this nonlinear variation of dielectric constant directly affects the beam propagation and gives rise to laser beam self-focusing in some spatial-temporal regions; in particular, the beam width and the beam intensity present an oscillatory variation in the self-focusing region. The influence of several parameters on the dielectric function and beam self-focusing is discussed.

  15. Pulse propagation in free-electron lasers with a tapered undulator

    International Nuclear Information System (INIS)

    Goldstein, J.C.; Colson, W.B.

    1981-01-01

    The one-dimensional theory of short pulse propagation in free electron lasers is extended to tapered undulator devices and is used to study the behavior of an oscillator with parameter values close to those expected in forthcoming experiments. It is found that stable laser output is possible only over a small range of optical cavity lengths. Optical pulse characteristics are presented and are found to change considerably over this range

  16. Theoretical Studies of TE-Wave Propagation as a Diagnostic for Electron Cloud

    International Nuclear Information System (INIS)

    Penn, Gregory E.; Vay, Jean-Luc

    2010-01-01

    The propagation of TE waves is sensitive to the presence of an electron cloud primarily through phase shifts generated by the altered dielectric function, but can also lead to polarization changes and other effects, especially in the presence of magnetic fields. These effects are studied theoretically and also through simulations using WARP. Examples are shown related to CesrTA parameters, and used to observe different regimes of operation as well as to validate estimates of the phase shift.

  17. Electric potential structures and propagation of electron beams injected from a spacecraft into a plasma

    International Nuclear Information System (INIS)

    Singh, Nagendra; Hwang, K.S.

    1988-01-01

    The propagation of electron beams injected from a spacecraft into an ambient plasma and the associated potential structures are investigated by one-dimensional Vlasov simulations. For moderate beams, for which the time average spacecraft potential (Φ sa ) lies in the range T e much-lt eΦ sa approx-lt W B , where T e is the electron temperature in energy units and W B is the average beam energy, a double layer forms near the beam head which propagates into the ambient plasma much more slowly than the initial beam velocity. The double layer formation is being reported for the first time. For weak beams, for which |eΦ sa | approx-lt T e , the beam propagates with the initial beam velocity, and no double layer formation occurs. On the other hand, for strong beams for which eΦ sa > W B , the bulk of the beam is returned to the spacecraft, and the main feature of the potential structure is a sheath formation with an intense electric field limited to distances d near the spacecraft surface. These features of the potential structures are compared with those seen in laboratory and space experiments on electron beam injections

  18. Propagation of high-current fast electron beam in a dielectric target

    International Nuclear Information System (INIS)

    Klimo, O.; Debayle, A.; Tikhonchuk, V.T.

    2006-01-01

    Complete test of publication follows. A relativistic electron beam with very high current density may be produced during the interaction of a short high intensity laser pulse with a solid target. In Fast Ignition approach to Inertial Confinement Fusion, such beam is supposed to heat a part of the precompressed DT fuel pellet to the conditions of an efficient ignition. For successful implementation of Fast Ignition understanding the propagation and energy deposition of the beam is crucial. A number of processes, mostly associated with the return current, are dissipating the energy of the beam or inhibiting its collimated transport, namely the filamentation. Weibel, two-stream or the recently proposed ionization instability. Ionization instability may develop in a solid dielectric target due to the dependence of the propagation velocity of the beam on the beam density. To study the propagation of high current electron beam in dielectric target, we use a one-dimensional relativistic electrostatic simulation code based on the Particle in Cell method. The code includes ionization processes in dielectric material and collisions of newly generated cold electrons. The current density of the relativistic electron beam used in this work is in the range 3-300 GA/cm 2 , while its length roughly corresponds to the beam, produced by a 40 fs laser pulse. Propagation of the beam in the polyethylene target is studied. The code is complemented by an analytical model, which is applicable og a wider range of beam parameters that are currently beyond our computational possibilities. When the head of the beam enters the plastic target, electric field grows rapidly in consequence of the charge separation and it starts to ionize atoms. In the maximum of the field, which is less than 10% of the atomic field, the density of new free electrons is two orders of magnitude higher than the beam density, which is enough for the current neutralization. Cold electrons are accelerated by the field

  19. Polarity-specific high-level information propagation in neural networks.

    Science.gov (United States)

    Lin, Yen-Nan; Chang, Po-Yen; Hsiao, Pao-Yueh; Lo, Chung-Chuan

    2014-01-01

    Analyzing the connectome of a nervous system provides valuable information about the functions of its subsystems. Although much has been learned about the architectures of neural networks in various organisms by applying analytical tools developed for general networks, two distinct and functionally important properties of neural networks are often overlooked. First, neural networks are endowed with polarity at the circuit level: Information enters a neural network at input neurons, propagates through interneurons, and leaves via output neurons. Second, many functions of nervous systems are implemented by signal propagation through high-level pathways involving multiple and often recurrent connections rather than by the shortest paths between nodes. In the present study, we analyzed two neural networks: the somatic nervous system of Caenorhabditis elegans (C. elegans) and the partial central complex network of Drosophila, in light of these properties. Specifically, we quantified high-level propagation in the vertical and horizontal directions: the former characterizes how signals propagate from specific input nodes to specific output nodes and the latter characterizes how a signal from a specific input node is shared by all output nodes. We found that the two neural networks are characterized by very efficient vertical and horizontal propagation. In comparison, classic small-world networks show a trade-off between vertical and horizontal propagation; increasing the rewiring probability improves the efficiency of horizontal propagation but worsens the efficiency of vertical propagation. Our result provides insights into how the complex functions of natural neural networks may arise from a design that allows them to efficiently transform and combine input signals.

  20. A high-repetition rate LWFA for studies of laser propagation and electron generation

    Science.gov (United States)

    He, Zhaohan; Easter, James; Hou, Bixue; Krushelnick, Karl; Nees, John; Thomas, Alec

    2010-11-01

    Advances in ultrafast optics today have enabled laser systems to deliver ever shorter and more intense pulses. When focused, such laser pulses can easily exceed relativistic intensities where the wakefield created by the strong laser electric field can be used to accelerate electrons. Laser wakefield acceleration of electrons holds promise for future compact electron accelerators or drivers of other radiation sources in many scientific, medical and engineering applications. We present experimental studies of laser wakefield acceleration using the λ-cubed laser at the University of Michigan -- a table-top high-power laser system operating at 500 Hz repetition rate. The high repetition rate allows statistical studies of laser propagation and electron acceleration which are not accessible with typical sub-0.1 Hz repetition rate systems. In addition, we compare the experiments with particle-in-cell simulations using the code OSIRIS.

  1. Propagation of a surface electromagnetic wave in a plasma with allowance for electron heating

    International Nuclear Information System (INIS)

    Boev, A.G.; Prokopov, A.V.

    1978-01-01

    Considered is propagation of a surface high-frequency wave in a semibounded plasma, which electron component is heated within the wave field. Dissipative effects are considered small, that is possible if wave frequency is much higher than the collision frequency and phase velocity of wave considerably exceeds electron heat velocity. Under conditions of anomalous skin-effect the distributions of electron temperature and wave damping have been found. It is established, that higher electron temperature on the boundary results in a higher decrease of temperature inside a plasma, far from the boundary temperature decreases exponentially; damping coefficient under anomalous skin-effect conditions is characterized by a stronger dependence not only on the wave amplitude, but as well as on gas pressure and wave frequency in comparison with normal conditions

  2. 1-MeV electron beam propagation experiments in neutral gas

    International Nuclear Information System (INIS)

    Greenspan, M.A.; Rose, E.A.

    1984-01-01

    Experiments were performed studying the propagation of a 1-MeV, 10-ns electron beam at currents of 2-8 kA. Propagation was studied in a 7.6-cm-diam glass guide tube, the same tube with a conducting screen inside, and in a 3.4-m-diam chamber. In the guide tube with the screen, ion-focused propagation is observed at low pressures (≤ 40 Pa) with net current equal to beam current. At higher pressures (55-130 Pa), a notch in beam current is observed for pressure time products of ≅ 100 Pa-ns. Between 270 Pa and 1070 Pa, good propagation is again observed with net currents of 50-70% of the beam current. The net current fraction of beam current increases with increasing pressure and with decreasing beam current. At pressure above 1070 Pa, hose instability occurs, and net current nearly equal to beam current is observed. The hose frequency is in reasonable accord with theory. Nose erosion is minimized at pressures for 1000-2000 Pa depending on beam current, and increases at lower and higher pressures

  3. Femtosecond Electron Wave Packet Propagation and Diffraction: Towards Making the ``Molecular Movie"

    Science.gov (United States)

    Miller, R. J. Dwayne

    2003-03-01

    Time-resolved electron diffraction harbors great promise for achieving atomic resolution of the fastest chemical processes. The generation of sufficiently short electron pulses to achieve this real time view of a chemical reaction has been limited by problems in maintaining short electron pulses with realistic electron densities to the sample. The propagation dynamics of femtosecond electron packets in the drift region of a photoelectron gun are investigated with an N-body numerical simulation and mean-field model. This analyis shows that the redistribution of electrons inside the packet, arising from space-charge and dispersion contributions, changes the pulse envelope and leads to the development of a spatially linear axial velocity distribution. These results have been used in the design of femtosecond photoelectron guns with higher time resolution and novel electron-optical methods of pulse characterization that are approaching 100 fs timescales. Time-resolved diffraction studies with electron pulses of approximately 500 femtoseconds have focused on solid-liquid phase transitions under far from equilibrium conditions. This work gives a microscopic description of the melting process and illustrates the promise of atomically resolving transition state processes.

  4. Nearly perpendicular wave propagation at the fundamental electron-cyclotron resonance

    International Nuclear Information System (INIS)

    Imre, K.; Weitzner, H.

    1985-01-01

    Waves propagating nearly perpendicular to the equilibrium magnetic field across the fundamental cyclotron resonance layer are studied by a boundary layer analysis for a weakly relativistic, inhomogeneous Vlasov plasma. The plasma is assumed to be perpendicularly stratified. It is found that the wave energy associated with the ordinary mode transmitted through the layer is independent of the relativistic corrections and is given by a geometrical optics formula. It is also found that there is no reflected energy associated with this mode when it is incident from the high-field side. These results are the same as the nonrelativistic case with purely perpendicular propagation. Relativistic effects produce a significant reduction of the reflection coefficient for low-field side incidence from the nonrelativistic value. Correspondingly, for this mode there is a considerable increase in the absorption rate for sufficiently high, but moderate, electron density and temperature

  5. Simulation and analysis of TE wave propagation for measurement of electron cloud densities in particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Sonnad, Kiran G., E-mail: kgs52@cornell.edu [CLASSE, Cornell University, Ithaca, NY (United States); Hammond, Kenneth C. [Department of Physics, Harvard University, Cambridge, MA (United States); Schwartz, Robert M. [CLASSE, Cornell University, Ithaca, NY (United States); Veitzer, Seth A. [Tech-X Corporation, Boulder, CO (United States)

    2014-08-01

    The use of transverse electric (TE) waves has proved to be a powerful, noninvasive method for estimating the densities of electron clouds formed in particle accelerators. Results from the plasma simulation program VSim have served as a useful guide for experimental studies related to this method, which have been performed at various accelerator facilities. This paper provides results of the simulation and modeling work done in conjunction with experimental efforts carried out at the Cornell electron storage ring “Test Accelerator” (CESRTA). This paper begins with a discussion of the phase shift induced by electron clouds in the transmission of RF waves, followed by the effect of reflections along the beam pipe, simulation of the resonant standing wave frequency shifts and finally the effects of external magnetic fields, namely dipoles and wigglers. A derivation of the dispersion relationship of wave propagation for arbitrary geometries in field free regions with a cold, uniform cloud density is also provided.

  6. Second harmonic generation by a relativistic annular electron beam propagating through a cylindrical waveguide

    International Nuclear Information System (INIS)

    Yasumoto, Kiyotoshi; Abe, Hiroshi

    1983-01-01

    The second harmonic generated by a relativistic annular electron beam propagating through a cylindrical waveguide immersed in a strong axial magnetic field is investigated on the basis of the relativistic hydrodynamic equations for cold electrons. The efficiency of second harmonic generation is calculated separately for the pump by the TM electromagnetic wave and for the pump by the slow space-charge wave, by assuming that the electron beam is thin and of low density and the pump wave is azimuthally symmetric. It is shown that, in the case of slow space-charge wave pump, an appreciably large efficiency of second harmonic generation is achieved in the high frequency region, whereas the efficiency by the TM electromagnetic wave pump is relatively small over the whole frequency range.(author)

  7. Quasilinear dynamics of a cloud of hot electrons propagating through a plasma with decreasing density and temperature

    International Nuclear Information System (INIS)

    Foroutan, G.; Khalilpour, H.; Moslehi-Fard, M.; Li, B.; Robinson, P. A.

    2008-01-01

    The effects of plasma inhomogeneities on the propagation of a cloud of hot electrons through a cold background plasma and generation of Langmuir waves are investigated using numerical simulations of the quasilinear equations. It is found that in a plasma with decreasing density the quasilinear relaxation of the electron distribution in velocity space is accelerated and the levels of the generated Langmuir waves are enhanced. The magnitude of the induced emission rate is increased and its maximum value moves to lower velocities. Due to density gradient the height of plateau shows an increase at small distances and a corresponding decrease at large distances. It is also found that in a plasma with decreasing temperature, the relaxation of the beam is retarded, the spectral density of Langmuir waves is broadened, and the height of the plateau decreases below its value in a uniform plasma. In the presence of both density and temperature gradients, at given position, the height and upper boundary of the plateau and the level of Langmuir waves are all increased at small velocities. The spatial expansion of the beam is increased by the plasma inhomogeneities, but its average velocity of propagation decreases. Initially, at a given position, the velocity at the upper boundary of the plateau is smaller in the presence of the density gradient than in the uniform plasma but the reverse is true at longer times. Due to temperature gradient, at large times and small distances, the upper boundary of the plateau is increased above its value in the uniform plasma. Because of fast relaxation, the value of the lower boundary of the plateau in the plasma with decreasing density is always less than its value in the uniform plasma. It is found that the local velocity of the beam decreases when the density gradient is present. The local velocity spread of the beam remains unchanged during the propagation of the beam in the uniform plasma, but increases in the presence of inhomogeneities.

  8. Suitability of high-current standing-wave linac technology for ultra-relativistic electron beam propagation experiments

    International Nuclear Information System (INIS)

    Moir, D.C.; Faehl, R.J.; Newberger, B.S.; Thode, L.E.

    1981-01-01

    Near-term development of the existing PHERMEX standing-wave linac would provide a 40 to 60 MeV electron beam with a current of 3 kA capable of answering a number of fundamental issues concerning endoatmospheric, ultra-relativistic electron beam propagation. Inherent high-repetition rate and multiple-pulse capability would allow alternative propagation scenarios to be investigated. Much of the theoretical expertise required to support the technology development and time-resolved beam propagation experiments presently resides within the Theoretical Applications Division

  9. Cyclotron Acceleration of Relativistic Electrons through Landau Resonance with Obliquely Propagating Whistler Mode Chorus Emissions

    Science.gov (United States)

    Omura, Y.; Hsieh, Y. K.; Foster, J. C.; Erickson, P. J.; Kletzing, C.; Baker, D. N.

    2017-12-01

    A recent test particle simulation of obliquely propagating whistler mode wave-particle interaction [Hsieh and Omura, 2017] shows that the perpendicular wave electric field can play a significant role in trapping and accelerating relativistic electrons through Landau resonance. A further theoretical and numerical investigation verifies that there occurs nonlinear wave trapping of relativistic electrons by the nonlinear Lorentz force of the perpendicular wave magnetic field. An electron moving with a parallel velocity equal to the parallel phase velocity of an obliquely propagating wave basically see a stationary wave phase. Since the electron position is displaced from its gyrocenter by a distance ρ*sin(φ), where ρ is the gyroradius and φ is the gyrophase, the wave phase is modulated with the gyromotion, and the stationary wave fields as seen by the electron are expanded as series of Bessel functions Jn with phase variations n*φ. The J1 components of the wave electric and magnetic fields rotate in the right-hand direction with the gyrofrequency, and they can be in resonance with the electron undergoing the gyromotion, resulting in effective electron acceleration and pitch angle scattering. We have performed a subpacket analysis of chorus waveforms observed by the Van Allen Probes [Foster et al., 2017], and calculated the energy gain by the cyclotron acceleration through Landau resonance. We compare the efficiencies of accelerations by cyclotron and Landau resonances in typical events of rapid electron acceleration observed by the Van Allen Probes.References:[1] Hsieh, Y.-K., and Y. Omura (2017), Nonlinear dynamics of electrons interacting with oblique whistler mode chorus in the magnetosphere, J. Geophys. Res. Space Physics, 122, 675-694, doi:10.1002/2016JA023255.[2] Foster, J. C., P. J. Erickson, Y. Omura, D. N. Baker, C. A. Kletzing, and S. G. Claudepierre (2017), Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear

  10. Space-charge effects on the propagation of hollow electron beams

    International Nuclear Information System (INIS)

    Barroso, J.J.; Stellati, C.

    1994-01-01

    The dynamics of hollow electron beams with gyro motion propagating down a cylindrical drift tube is analysed on the basis of a non-adiabatic-gun-generated laminar beam. Due to the action of beam's self-space charge field, the transverse velocity spread has an oscillatory behavior along the drift tube wherein the spatial auto modulation period shortens with increasing current. Numerical simulation results indicate that even at a 10 A beam current, the resulting transverse velocity spread is still less than the spread for a zero beam current. (author). 5 refs, 3 figs

  11. Electron-cyclotron wave propagation, absorption and current drive in the presence of neoclassical tearing modes

    Science.gov (United States)

    Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas

    2012-09-01

    We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation.

  12. Electron-cyclotron wave propagation, absorption and current drive in the presence of neoclassical tearing modes

    International Nuclear Information System (INIS)

    Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas

    2012-01-01

    We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation. (paper)

  13. Propagation of Electron Acoustic Soliton, Periodic and Shock Waves in Dissipative Plasma with a q-Nonextensive Electron Velocity Distribution

    Science.gov (United States)

    El-Hanbaly, A. M.; El-Shewy, E. K.; Elgarayhi, A.; Kassem, A. I.

    2015-11-01

    The nonlinear properties of small amplitude electron-acoustic (EA) solitary and shock waves in a homogeneous system of unmagnetized collisionless plasma with nonextensive distribution for hot electrons have been investigated. A reductive perturbation method used to obtain the Kadomstev-Petviashvili-Burgers equation. Bifurcation analysis has been discussed for non-dissipative system in the absence of Burgers term and reveals different classes of the traveling wave solutions. The obtained solutions are related to periodic and soliton waves and their behavior are shown graphically. In the presence of the Burgers term, the EXP-function method is used to solve the Kadomstev-Petviashvili-Burgers equation and the obtained solution is related to shock wave. The obtained results may be helpful in better conception of waves propagation in various space plasma environments as well as in inertial confinement fusion laboratory plasmas.

  14. Experimental and numerical studies of sheet electron beam propagation through a planar wiggler magnet

    International Nuclear Information System (INIS)

    Zhang, Ze Xiang; Granatstein, V.L.; Destler, W.W.; Rodgers, J.; Cheng, S.; Antonsen, T.M. Jr.; Levush, B.; Bidwell, S.W.

    1993-01-01

    Detailed experimental studies on sheet relativistic electron beam propagation through a long planar wiggler are reported and compared with numerical simulations. The planar wiggler has 56 periods with a period of 9.6 mm. Typically, the wiggler field peak amplitude is 5 kG. The experimental efforts have been focused on control of the deviation of the beam toward the side edge of the planar wiggler along the wide transverse direction. It is found that a suitably tapered magnetic field configuration at the wiggler entrance can considerably reduce the rate of the deviation. The effects of the following techniques on beam transport efficiency are also discussed: side focusing, beam transverse velocity tuning at the wiggler entrance, and beam spread limiting. High beam transport efficiency (almost 100%) of a 15 A beam has been obtained in some cases. The results are relevant to development of a free electron laser amplifier for application to stabilizing and heating of plasma in magnetic fusion research

  15. Effects of buried high-Z layers on fast electron propagation

    International Nuclear Information System (INIS)

    Yang, Xiaohu; Zhuo, Hongbin; Ma, Yanyun; Shao, Fuqiu; Xu, Han; Yin Yan; Borghesi, M.

    2014-01-01

    The transport through high density plasmas of relativistic electron beams generated by ultra-intense laser-plasma interaction has potential applications in laser-driven ion acceleration and in the fast igniter scheme for inertial confinement fusion. By extending a prior model [A.R. Bell, J.R. Davies, S.M. Guerin, Phys. Rev. E 58, 2471 (1998)], the magnetic field generated during the transport of a fast electron beam driven by an ultra-intense laser in a solid target is derived analytically and applied to estimate the effect of such field on fast electron propagation through a buried high-Z layer in a lower-Z target. It is found that the effect gets weaker with the increase of the depth of the buried layer, the divergence of the fast electrons, and the laser intensity, indicating that magnetic field effects on the fast electron divergence as measured from K a X-ray emission may need to be considered for moderate laser intensities. On the basis of the calculations, some considerations are made on how one can mitigate the effect of the magnetic field generated at the interface. (authors)

  16. Electron beam propagation in the ion focused regime (IFR) with the experimental test accelerator (ETA)

    International Nuclear Information System (INIS)

    Struve, K.W.; Lauer, E.J.; Chambers, F.W.

    1983-01-01

    The IFR is a well-known stable, low pressure (0.10 to 0.120 torr in air) propagation window. Secondary electrons created by collisions of beam electrons with gas atoms are rapidly expelled by the strong radial electric field of the beam charge. The ions that remain inside the beam partially neutralize the electric field, allowing magnetic pinch forces to focus the beam. Experiments with the ETA beam have re-verified this stable window and are reported. Image forces from a close wall IFR propagation tank are also experimentally shown to center the beam and damp transverse oscillations. Results of experiments using 5 and 15 cm dia beam tubes are reported. For p tau > 2 torr-nsec (gas pressure x time into pulse the beam charge becomes completely neutralized by the ions, allowing a build up of plasma and resultant beam-plasma instabilities. The onset of these instabilities has been measured using rf pickup loops (0 to 2 GHz) and microwave detectors (6 to 40 GHz), and are also reported

  17. Investigation of Electronic Corrosion at Device Level

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Minzari, Daniel; Rathinavelu, Umadevi

    2010-01-01

    This work presents device level testing of a lead free soldered electronic device tested with bias on under cyclic humidity conditions in a climatic chamber. Besides severe temperature and humidity during testing some devices were deliberately contaminated before testing. Contaminants investigated...

  18. Propagation of energetic electrons in the solar corona observed with LOFAR

    Science.gov (United States)

    Breitling, F.

    2017-06-01

    This work reports about new high-resolution imaging and spectroscopic observations of solar type III radio bursts at low radio frequencies in the range from 30 to 80 MHz. Solar type III radio bursts are understood as result of the beam-plasma interaction of electron beams in the corona. The Sun provides a unique opportunity to study these plasma processes of an active star. Its activity appears in eruptive events like flares, coronal mass ejections and radio bursts which are all accompanied by enhanced radio emission. Therefore solar radio emission carries important information about plasma processes associated with the Sun's activity. Moreover, the Sun's atmosphere is a unique plasma laboratory with plasma processes under conditions not found in terrestrial laboratories. Because of the Sun's proximity to Earth, it can be studied in greater detail than any other star but new knowledge about the Sun can be transfer to them. This "solar stellar connection" is important for the understanding of processes on other stars. The novel radio interferometer LOFAR provides imaging and spectroscopic capabilities to study these processes at low frequencies. Here it was used for solar observations. LOFAR, the characteristics of its solar data and the processing and analysis of the latter with the Solar Imaging Pipeline and Solar Data Center are described. The Solar Imaging Pipeline is the central software that allows using LOFAR for solar observations. So its development was necessary for the analysis of solar LOFAR data and realized here. Moreover a new density model with heat conduction and Alfvén waves was developed that provides the distance of radio bursts to the Sun from dynamic radio spectra. Its application to the dynamic spectrum of a type III burst observed on March 16, 2016 by LOFAR shows a nonuniform radial propagation velocity of the radio emission. The analysis of an imaging observation of type III bursts on June 23, 2012 resolves a burst as bright, compact region

  19. Propagation of Ion Solitary Pulses in Dense Astrophysical Electron-Positron-Ion Magnetoplasmas

    Science.gov (United States)

    Ata-Ur-Rahman; A. Khan, S.; Qamar, A.

    2015-12-01

    In this paper, we theoretically investigate the existence and propagation of low amplitude nonlinear ion waves in a dense plasma under the influence of a strong magnetic field. The plasma consists of ultra-relativistic and degenerate electrons and positrons and non-degenerate cold ions. Firstly, the appearance of two distinct linear modes and their evolution is studied by deriving a dispersion equation with the aid of Fourier analysis. Secondly, the dynamics of low amplitude ion solitary structures is investigated via a Korteweg-de Vries equation derived by employing a reductive perturbation method. The effects of various plasma parameters like positron concentration, strength of magnetic field, obliqueness of field, etc., are discussed in detail. At the end, analytical results are supplemented through numerical analysis by using typical representative parameters consistent with degenerate and ultra-relativistic magnetoplasmas of astrophysical regimes.

  20. Electron Acceleration and the Propagation of Ultrashort High-Intensity Laser Pulses in Plasmas

    International Nuclear Information System (INIS)

    Wang, Xiaofang; Krishnan, Mohan; Saleh, Ned; Wang, Haiwen; Umstadter, Donald

    2000-01-01

    Reported are interactions of high-intensity laser pulses (λ=810 nm and I≤3x10 18 W /cm 2 ) with plasmas in a new parameter regime, in which the pulse duration (τ=29 fs ) corresponds to 0.6-2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 degree sign is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results. (c) 2000 The American Physical Society

  1. Accurate calculation of the differential cross section of compton scattering with electron mixed chain propagator in SM

    International Nuclear Information System (INIS)

    Chen Xuewen; Fang Zhenyun; Shi Chengye

    2012-01-01

    By using the electroweak standard model (SM), we analyzed the framework of electron mixed chain propagator which composed of serious of different physical loops participating in electroweak interaction and completed the relevant analytical calculation. Then, we obtained the analytical result of electron mixed chain propagator. By applying our result to Compton scattering, the differential cross section of Compton scattering dσ SM (chain) /dcosθ is counted accurately. This result is compared with the lowest order differential cross section dσ (tree) /dcosθ and the electronic chain propagator Compton scattering differential cross section dσ QED (chain) /dcosθ in quantum electrodynamics (QED). It can be seen that dσ SM (chain ) /dcosθ can show the radiation correction more subtly than dσ QED (chain) /dcosθ. (authors)

  2. Propagation of an attosecond pulse in a dense two-level medium

    International Nuclear Information System (INIS)

    Song Xiaohong; Gong Shangqing; Yang Weifeng; Xu Zhizhan

    2004-01-01

    We investigate the propagation of attosecond pulse in a dense two-level medium by using an iterative predictor-corrector finite-difference time-domain method. We find when attosecond pulse is considered, that the standard area theorem will break down even for small area pulses: ideal self-induced transparency cannot occur even for a 2π pulse, while the pulses whose areas are not integer multiples of 2π, such as 1.8π and 2.2π pulses, cannot evolve to 2π pulses as predicted by the standard area theorem. Significantly higher spectra components can occur on all these small area propagating pulses due to strong carrier reshaping. Furthermore, these higher spectral components dependent sensitively on the pulse area: the larger the pulse area is, the more evident are these higher spectral components

  3. Transport and diffusion of material quantities on propagating interfaces via level set methods

    CERN Document Server

    Adalsteinsson, D

    2003-01-01

    We develop theory and numerical algorithms to apply level set methods to problems involving the transport and diffusion of material quantities in a level set framework. Level set methods are computational techniques for tracking moving interfaces; they work by embedding the propagating interface as the zero level set of a higher dimensional function, and then approximate the solution of the resulting initial value partial differential equation using upwind finite difference schemes. The traditional level set method works in the trace space of the evolving interface, and hence disregards any parameterization in the interface description. Consequently, material quantities on the interface which themselves are transported under the interface motion are not easily handled in this framework. We develop model equations and algorithmic techniques to extend the level set method to include these problems. We demonstrate the accuracy of our approach through a series of test examples and convergence studies.

  4. Transport and diffusion of material quantities on propagating interfaces via level set methods

    International Nuclear Information System (INIS)

    Adalsteinsson, David; Sethian, J.A.

    2003-01-01

    We develop theory and numerical algorithms to apply level set methods to problems involving the transport and diffusion of material quantities in a level set framework. Level set methods are computational techniques for tracking moving interfaces; they work by embedding the propagating interface as the zero level set of a higher dimensional function, and then approximate the solution of the resulting initial value partial differential equation using upwind finite difference schemes. The traditional level set method works in the trace space of the evolving interface, and hence disregards any parameterization in the interface description. Consequently, material quantities on the interface which themselves are transported under the interface motion are not easily handled in this framework. We develop model equations and algorithmic techniques to extend the level set method to include these problems. We demonstrate the accuracy of our approach through a series of test examples and convergence studies

  5. Prediction of blast vibration level considered propagation characteristics; Denpa tokusei to koryoshita happa shindo level no yosoku

    Energy Technology Data Exchange (ETDEWEB)

    Kunimatsu, S; Jinguji, M [National Institute for Resources and Environment, Tsukuba (Japan); Yamada, M; Hirai, T [Newjec Inc., Osaka (Japan); Durucan, S; Farsangi, M

    1997-10-22

    With an objective to assess environmental influence induced by blast vibration, a study has been carried out on a method to predict vibration levels. The study has discussed a method to calculate vibration levels, in which vibration propagating characteristics are sought on blast vibration generated from an open-cut limestone mine from acceleration waveforms in the vicinity of the blast source and residential housings by using an octave analysis, and waveforms are predicted. The shortest straight line distance from the blast position to a housing is about 150 m, and the height difference is about 30 to 40 meters. The measuring instruments include a vibration level meter used for pollution measurement and a data recorder, with signals lower than 1 Hz and higher than 90 Hz being interrupted. The environmental influence assessment discusses not only the maximum value of the vibration level, but also sizes of values of each band by using a frequency analysis. The result of the discussions revealed that the prediction of the vibration levels is little affected by phase characteristics, and that no problems are caused in the measurement accuracy even if the vibration levels are predicted by using relative decay amount according to a one-third octave analysis for the propagation characteristics. 5 figs., 4 tabs.

  6. Propagation & Level: Factors Influencing in the ICT Composite Index at the School Level

    Science.gov (United States)

    Aoki, Hiroyuki; Kim, JaMee; Lee, WonGyu

    2013-01-01

    Many nations are greatly affected by their education policies, and the educational level of different schools is relevant to a nation's ICT policy. In the area of ICT, Korea has achieved quite high levels of competency. This study analyzed the level of ICT competency of 4490 elementary and 2419 middle schools in Korea within the context of the…

  7. Electron-capture Isotopes Could Constrain Cosmic-Ray Propagation Models

    Science.gov (United States)

    Benyamin, David; Shaviv, Nir J.; Piran, Tsvi

    2017-12-01

    Electron capture (EC) isotopes are known to provide constraints on the low-energy behavior of cosmic rays (CRs), such as reacceleration. Here, we study the EC isotopes within the framework of the dynamic spiral-arms CR propagation model in which most of the CR sources reside in the galactic spiral arms. The model was previously used to explain the B/C and sub-Fe/Fe ratios. We show that the known inconsistency between the 49Ti/49V and 51V/51Cr ratios remains also in the spiral-arms model. On the other hand, unlike the general wisdom that says the isotope ratios depend primarily on reacceleration, we find here that the ratio also depends on the halo size (Z h) and, in spiral-arms models, also on the time since the last spiral-arm passage ({τ }{arm}). Namely, EC isotopes can, in principle, provide interesting constraints on the diffusion geometry. However, with the present uncertainties in the lab measurements of both the electron attachment rate and the fragmentation cross sections, no meaningful constraint can be placed.

  8. Iteratively-coupled propagating exterior complex scaling method for electron-hydrogen collisions

    International Nuclear Information System (INIS)

    Bartlett, Philip L; Stelbovics, Andris T; Bray, Igor

    2004-01-01

    A newly-derived iterative coupling procedure for the propagating exterior complex scaling (PECS) method is used to efficiently calculate the electron-impact wavefunctions for atomic hydrogen. An overview of this method is given along with methods for extracting scattering cross sections. Differential scattering cross sections at 30 eV are presented for the electron-impact excitation to the n = 1, 2, 3 and 4 final states, for both PECS and convergent close coupling (CCC), which are in excellent agreement with each other and with experiment. PECS results are presented at 27.2 eV and 30 eV for symmetric and asymmetric energy-sharing triple differential cross sections, which are in excellent agreement with CCC and exterior complex scaling calculations, and with experimental data. At these intermediate energies, the efficiency of the PECS method with iterative coupling has allowed highly accurate partial-wave solutions of the full Schroedinger equation, for L ≤ 50 and a large number of coupled angular momentum states, to be obtained with minimal computing resources. (letter to the editor)

  9. The effect of applying different water levels and irrigation frequencies in propagating rosemary (Rosmarinus officinalis L.

    Directory of Open Access Journals (Sweden)

    Javier Giovanni Álvarez Herrera

    2010-01-01

    Full Text Available Rosemary seedlings are obtained by vegetative propagation because the seeds present low viability. Despite being an expanding crop, there is little information on water consumption during the propagation stage. Water levels and irrigation frequencies were therefore applied using a completely randomised design having a 4 x 2 factorial arrangement. The first factor concerned irrigation frequency (4 and 8 days and the second concerned water level (0.6, 0.8, 1.0 and 1.2 evaporation inside the greenhouse. A 1.0 coefficient combined with 4-day irrigation frequency presented the best results regarding height (39.3 cm, fresh weight, dry weight and branch length (146 cm. Water level affected the fresh and dry weight of leaves regardless of frequency. Relative water content in leaves did not present differences due to environmental conditions minimising treatment effect. Rooting percent- tage showed no significant differences regarding irrigation frequency or water level. Irrigation frequency did not affect rosemary growing pattern because sphagnum retains high moisture content. The best branch number (34 was obtained with 1.0 coefficient and 4-day frequency, this being important from the production point of view because this is the material which is sold. Water management changes photoassimilate distribution in rosemary plants.

  10. Propagation of modulated electron and X-ray beams through matter and interactions with radio-frequency structures

    Science.gov (United States)

    Harris, J. R.; Miller, R. B.

    2018-02-01

    The generation and evolution of modulated particle beams and their interactions with resonant radiofrequency (RF) structures are of fundamental interest for both particle accelerator and vacuum electronic systems. When the constraint of propagation in a vacuum is removed, the evolution of such beams can be greatly affected by interactions with matter including scattering, absorption, generation of atmospheric plasma, and the production of multiple generations of secondary particles. Here, we study the propagation of 21 MeV and 25 MeV electron beams produced in S-band and L-band linear accelerators, and their interaction with resonant RF structures, under a number of combinations of geometry, including transmission through both air and metal. Both resonant and nonresonant interactions were observed, with the resonant interactions indicating that the RF modulation on the electron beam is at least partially preserved as the beam propagates through air and metal. When significant thicknesses of metal are placed upstream of a resonant structure, preventing any primary beam electrons from reaching the structure, RF signals could still be induced in the structures. This indicated that the RF modulation present on the electron beam was also impressed onto the x-rays generated when the primary electrons were stopped in the metal, and that this RF modulation was also present on the secondary electrons generated when the x-rays struck the resonant structures. The nature of these interactions and their sensitivities to changes in system configurations will be discussed.

  11. Semiclassical theory of electronically nonadiabatic chemical dynamics: Incorporation of the Zhu-Nakamura theory into the frozen Gaussian propagation method

    International Nuclear Information System (INIS)

    Kondorskiy, A.; Nakamura, H.

    2004-01-01

    The title theory is developed by combining the Herman-Kluk semiclassical theory for adiabatic propagation on single potential-energy surface and the semiclassical Zhu-Nakamura theory for nonadiabatic transition. The formulation with use of natural mathematical principles leads to a quite simple expression for the propagator based on classical trajectories and simple formulas are derived for overall adiabatic and nonadiabatic processes. The theory is applied to electronically nonadiabatic photodissociation processes: a one-dimensional problem of H 2 + in a cw (continuous wave) laser field and a two-dimensional model problem of H 2 O in a cw laser field. The theory is found to work well for the propagation duration of several molecular vibrational periods and wide energy range. Although the formulation is made for the case of laser induced nonadiabatic processes, it is straightforwardly applicable to ordinary electronically nonadiabatic chemical dynamics

  12. Full-wave Simulations of LH Wave Propagation in Toroidal Plasma with non-Maxwellian Electron Distributions

    International Nuclear Information System (INIS)

    Valeo, E.J.; Phillips, C.K.; Bonoli, P.T.; Wright, J.C.; Brambilla, M.

    2007-01-01

    The generation of energetic tails in the electron distribution function is intrinsic to lower-hybrid (LH) heating and current drive in weakly collisional magnetically confined plasma. The effects of these deformations on the RF deposition profile have previously been examined within the ray approximation. Recently, the calculation of full-wave propagation of LH waves in a thermal plasma has been accomplished using an adaptation of the TORIC code. Here, initial results are presented from TORIC simulations of LH propagation in a toroidal plasma with non-thermal electrons. The required efficient computation of the hot plasma dielectric tensor is accomplished using a technique previously demonstrated in full-wave simulations of ICRF propagation in plasma with non-thermal ions

  13. Light propagation from subluminal to superluminal in a three-level Λ-type system

    International Nuclear Information System (INIS)

    Sun Hui; Guo Hong; Bai, Yanfeng; Han Dingan; Fan Shuangli; Chen Xuzong

    2005-01-01

    We show that the group velocity of a weak electromagnetic pulse can be manipulated by adjusting the relative phase of the probing and the pumping fields applied to a Λ-type three-level system, whose two lower states are coupled by an external control magnetic field. Such control field can, in principle, cause the light propagation to be changed from subluminal to superluminal by modulating the relative phase. The same effect can be obtained by varying the intensities of the pumping and the control magnetic fields, but it is different with Agarwal's [Phys. Rev. A 64 (2001) 053809]. The effect of Doppler broadening on the dispersion is also investigated

  14. Synchronization of streak and framing camera measurements of an intense relativistic electron beam propagating through gas

    International Nuclear Information System (INIS)

    Weidman, D.J.; Murphy, D.P.; Myers, M.C.; Meger, R.A.

    1994-01-01

    The expansion of the radius of a 5 MeV, 20 kA, 40 ns electron beam from SuperIBEX during propagation through gas is being measured. The beam is generated, conditions, equilibrated, and then passed through a thin foil that produces Cherenkov light, which is recorded by a streak camera. At a second location, the beam hits another Cherenkov emitter, which is viewed by a framing camera. Measurements at these two locations can provide a time-resolved measure of the beam expansion. The two measurements, however, must be synchronized with each other, because the beam radius is not constant throughout the pulse due to variations in beam current and energy. To correlate the timing of the two diagnostics, several shots have been taken with both diagnostics viewing Cherenkov light from the same foil. Experimental measurements of the Cherenkov light from one foil viewed by both diagnostics will be presented to demonstrate the feasibility of correlating the diagnostics with each other. Streak camera data showing the optical fiducial, as well as the final correlation of the two diagnostics, will also be presented. Preliminary beam radius measurements from Cherenkov light measured at two locations will be shown

  15. Propagation of localized structures in relativistic magnetized electron-positron plasmas using particle-in-cell simulations

    Energy Technology Data Exchange (ETDEWEB)

    López, Rodrigo A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción 4070386 (Chile); Muñoz, Víctor [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Viñas, Adolfo F. [Geospace Physics Laboratory, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Valdivia, Juan A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología (CEDENNA), Santiago 9170124 (Chile)

    2015-09-15

    We use a particle-in-cell simulation to study the propagation of localized structures in a magnetized electron-positron plasma with relativistic finite temperature. We use as initial condition for the simulation an envelope soliton solution of the nonlinear Schrödinger equation, derived from the relativistic two fluid equations in the strongly magnetized limit. This envelope soliton turns out not to be a stable solution for the simulation and splits in two localized structures propagating in opposite directions. However, these two localized structures exhibit a soliton-like behavior, as they keep their profile after they collide with each other due to the periodic boundary conditions. We also observe the formation of localized structures in the evolution of a spatially uniform circularly polarized Alfvén wave. In both cases, the localized structures propagate with an amplitude independent velocity.

  16. Propagation of localized structures in relativistic magnetized electron-positron plasmas using particle-in-cell simulations

    International Nuclear Information System (INIS)

    López, Rodrigo A.; Muñoz, Víctor; Viñas, Adolfo F.; Valdivia, Juan A.

    2015-01-01

    We use a particle-in-cell simulation to study the propagation of localized structures in a magnetized electron-positron plasma with relativistic finite temperature. We use as initial condition for the simulation an envelope soliton solution of the nonlinear Schrödinger equation, derived from the relativistic two fluid equations in the strongly magnetized limit. This envelope soliton turns out not to be a stable solution for the simulation and splits in two localized structures propagating in opposite directions. However, these two localized structures exhibit a soliton-like behavior, as they keep their profile after they collide with each other due to the periodic boundary conditions. We also observe the formation of localized structures in the evolution of a spatially uniform circularly polarized Alfvén wave. In both cases, the localized structures propagate with an amplitude independent velocity

  17. Electron microscopy at reduced levels of irradiation

    International Nuclear Information System (INIS)

    Kuo, I.A.M.

    1975-05-01

    Specimen damage by electron radiation is one of the factors that limits high resolution electron microscopy of biological specimens. A method was developed to record images of periodic objects at a reduced electron exposure in order to preserve high resolution structural detail. The resulting image would tend to be a statistically noisy one, as the electron exposure is reduced to lower and lower values. Reconstruction of a statistically defined image from such data is possible by spatial averaging of the electron signals from a large number of identical unit cells. (U.S.)

  18. Electron acceleration by an obliquely propagating electromagnetic wave in the regime of validity of the Fokker-Planck-Kolmogorov approach

    Science.gov (United States)

    Hizanidis, Kyriakos; Vlahos, L.; Polymilis, C.

    1989-01-01

    The relativistic motion of an ensemble of electrons in an intense monochromatic electromagnetic wave propagating obliquely in a uniform external magnetic field is studied. The problem is formulated from the viewpoint of Hamiltonian theory and the Fokker-Planck-Kolmogorov approach analyzed by Hizanidis (1989), leading to a one-dimensional diffusive acceleration along paths of constant zeroth-order generalized Hamiltonian. For values of the wave amplitude and the propagating angle inside the analytically predicted stochastic region, the numerical results suggest that the diffusion probes proceeds in stages. In the first stage, the electrons are accelerated to relatively high energies by sampling the first few overlapping resonances one by one. During that stage, the ensemble-average square deviation of the variable involved scales quadratically with time. During the second stage, they scale linearly with time. For much longer times, deviation from linear scaling slowly sets in.

  19. The use of Electronic Speckle Pattern Interferometry (ESPI) in the crack propagation analysis of epoxy resins

    Science.gov (United States)

    Herbert, D. P.; Al-Hassani, A. H. M.; Richardson, M. O. W.

    The ESPI (electronic speckle pattern interferometry) technique at high magnification levels is demonstrated to be of considerable value in interpreting the fracture behaviour of epoxy resins. The fracture toughness of powder coating system at different thicknesses has been measured using a TDCB (tapered double cantilever beam) technique and the deformation zone at the tip of the moving crack monitored. Initial indications are that a mechanistic changeover occurs at a critical bond (coating) thickness and that this is synonymous with the occurence of a fracture toughness maximum, which in turn is associated with a deformation zone of specific diameter.

  20. Exact diagonalization of the interacting propagator for the 2D-electron gas in a magnetic field

    International Nuclear Information System (INIS)

    Burke, A.; Cabo, A.

    1990-07-01

    The spatial dependence of the exact one electron propagator for an interacting 2D-electron gas in a magnetic field is shown to be the same as for a non-interacting gas. This happens whenever the translational symmetry is unbroken in the ground state. The result may be extended to a more general class of systems. The translational symmetry also implies that the density of states has the same kind of discrete character as in the non-interacting case. This is shown explicitly in the Hartree-Fock approximation by solving the Dyson equation. (author). 10 refs

  1. Point Coulomb solutions of the Dirac equation: analytical results required for the evaluation of the bound electron propagator in quantum electrodynamics

    International Nuclear Information System (INIS)

    Whittingham, I.B.

    1977-12-01

    The bound electron propagator in quantum electrodynamics is reviewed and the Brown and Schaefer angular momentum representation of the propagator discussed. Regular and irregular solutions of the radial Dirac equations for both /E/ 2 and /E/ >or= mc 2 are required for the computation of the propagator. Analytical expressions for these solutions, and their corresponding Wronskians, are obtained for a point Coulomb potential. Some computational aspects are discussed in an appendix

  2. Assessment of ventricular excitation propagation velocity using intramyocardial electrograms and electron beam tomography images

    International Nuclear Information System (INIS)

    Kraft, A.; Schreier, G.; Hutten, H.; Kastner, P.; Rienmueller, R.; Grasser, B; Iberer, F.; Tscheliessnigg, K.H.

    1999-01-01

    The combination of intramyocardial electrogram (IEGM) recordings and 3D-reconstruction of the heart allows to relate electrophysiological with geometrical parameters of the heart. In 12 Heart transplants the distance of two epimyocardially implanted pacemaker leads d x and the propagation time f x have been correlated. Linear regression analysis revealed significant (p < 0,002) and strong (r = 0,82) correlation. The ventricular excitation propagation velocity (VEPV) within the examined patient group was found to be 0,53 m/s with an offset of 14.25 mm, which is caused by the extent of the electrodes and the region of early capture immediately after stimulation. (author)

  3. Assessment of electron propagator methods for the simulation of vibrationally-resolved valence and core photoionization spectra

    Science.gov (United States)

    Baiardi, A.; Paoloni, L.; Barone, V.; Zakrzewski, V.G.; Ortiz, J.V.

    2017-01-01

    The analysis of photoelectron spectra is usually facilitated by quantum mechanical simulations. Due to the recent improvement of experimental techniques, the resolution of experimental spectra is rapidly increasing, and the inclusion of vibrational effects is usually mandatory to obtain a reliable reproduction of the spectra. With the aim of defining a robust computational protocol, a general time-independent formulation to compute different kinds of vibrationally-resolved electronic spectra has been generalized to support also photoelectron spectroscopy. The electronic structure data underlying the simulation are computed using different electron propagator approaches. In addition to the more standard approaches, a new and robust implementation of the second-order self-energy approximation of the electron propagator based on a transition operator reference (TOEP2) is presented. To validate our implementation, a series of molecules has been used as test cases. The result of the simulations shows that, for ultraviolet photoionization spectra, the more accurate non-diagonal approaches are needed to obtain a reliable reproduction of vertical ionization energies, but diagonal approaches are sufficient for energy gradients and pole strengths. For X-ray photoelectron spectroscopy, the TOEP2 approach, besides being more efficient, is also the most accurate in the reproduction of both vertical ionization energies and vibrationally-resolved bandshapes. PMID:28521087

  4. Electronic circuit provides automatic level control for liquid nitrogen traps

    Science.gov (United States)

    Turvy, R. R.

    1968-01-01

    Electronic circuit, based on the principle of increased thermistor resistance corresponding to decreases in temperature provides an automatic level control for liquid nitrogen cold traps. The electronically controlled apparatus is practically service-free, requiring only occasional reliability checks.

  5. Forecasting Method for Urban Rail Transit Ridership at Station Level Using Back Propagation Neural Network

    Directory of Open Access Journals (Sweden)

    Junfang Li

    2016-01-01

    Full Text Available Direct forecasting method for Urban Rail Transit (URT ridership at the station level is not able to reflect nonlinear relationship between ridership and its predictors. Also, population is inappropriately expressed in this method since it is not uniformly distributed by area. In this paper, a new variable, population per distance band, is considered and a back propagation neural network (BPNN model which can reflect nonlinear relationship between ridership and its predictors is proposed to forecast ridership. Key predictors are obtained through partial correlation analysis. The performance of the proposed model is compared with three other benchmark models, which are linear model with population per distance band, BPNN model with total population, and linear model with total population, using four measures of effectiveness (MOEs, maximum relative error (MRE, smallest relative error (SRE, average relative error (ARE, and mean square root of relative error (MSRRE. Also, another model for contribution rate of population per distance band to ridership is formulated based on the BPNN model with nonpopulation variables fixed. Case studies with Japanese data show that BPNN model with population per distance band outperforms other three models and the contribution rate of population within special distance band to ridership calculated through the contribution rate model is 70%~92.9% close to actual statistical value. The result confirms the effectiveness of models proposed in this paper.

  6. Propagation of frequency-chirped laser pulses in a medium of atoms with a Λ-level scheme

    International Nuclear Information System (INIS)

    Demeter, G.; Dzsotjan, D.; Djotyan, G. P.

    2007-01-01

    We study the propagation of frequency-chirped laser pulses in optically thick media. We consider a medium of atoms with a Λ level-scheme (Lambda atoms) and also, for comparison, a medium of two-level atoms. Frequency-chirped laser pulses that induce adiabatic population transfer between the atomic levels are considered. They induce transitions between the two lower (metastable) levels of the Λ-atoms and between the ground and excited states of the two-level atoms. We show that associated with this adiabatic population transfer in Λ-atoms, there is a regime of enhanced transparency of the medium--the pulses are distorted much less than in the medium of two-level atoms and retain their ability to transfer the atomic population much longer during propagation

  7. Oblique Propagation of Electrostatic Waves in a Magnetized Electron-Positron-Ion Plasma in the Presence of Heavy Particles

    Science.gov (United States)

    Sarker, M.; Hossen, M. R.; Shah, M. G.; Hosen, B.; Mamun, A. A.

    2018-06-01

    A theoretical investigation is carried out to understand the basic features of nonlinear propagation of heavy ion-acoustic (HIA) waves subjected to an external magnetic field in an electron-positron-ion plasma that consists of cold magnetized positively charged heavy ion fluids and superthermal distributed electrons and positrons. In the nonlinear regime, the Korteweg-de Vries (K-dV) and modified K-dV (mK-dV) equations describing the propagation of HIA waves are derived. The latter admits a solitary wave solution with both positive and negative potentials (for K-dV equation) and only positive potential (for mK-dV equation) in the weak amplitude limit. It is observed that the effects of external magnetic field (obliqueness), superthermal electrons and positrons, different plasma species concentration, heavy ion dynamics, and temperature ratio significantly modify the basic features of HIA solitary waves. The application of the results in a magnetized EPI plasma, which occurs in many astrophysical objects (e.g. pulsars, cluster explosions, and active galactic nuclei) is briefly discussed.

  8. Spin-wave propagation and spin-polarized electron transport in single-crystal iron films

    Science.gov (United States)

    Gladii, O.; Halley, D.; Henry, Y.; Bailleul, M.

    2017-11-01

    The techniques of propagating spin-wave spectroscopy and current-induced spin-wave Doppler shift are applied to a 20-nm-thick Fe/MgO(001) film. The magnetic parameters extracted from the position of the spin-wave resonance peaks are very close to those tabulated for bulk iron. From the zero-current propagating wave forms, a group velocity of 4 km/s and an attenuation length of about 6 μ m are extracted for 1.6-μ m -wavelength spin wave at 18 GHz. From the measured current-induced spin-wave Doppler shift, we extract a surprisingly high degree of spin polarization of the current of 83 % , which constitutes the main finding of this work. This set of results makes single-crystalline iron a promising candidate for building devices utilizing high-frequency spin waves and spin-polarized currents.

  9. Nonlinear propagation of ultra-low-frequency electronic modes in a magnetized dusty plasma

    International Nuclear Information System (INIS)

    Mamun, A.A.

    1999-07-01

    A theoretical investigation has been made of nonlinear propagation of ultra-low-frequency electromagnetic waves in a magnetized two fluid (negatively charged dust and positively charged ion fluids) dusty plasma. These are modified Alfven waves for small value of θ and are modified magnetosonic waves for large θ, where θ is the angle between the directions of the external magnetic field and the wave propagation. A nonlinear evolution equation for the wave magnetic field, which is known as Korteweg de Vries (K-dV) equation and which admits a stationary solitary wave solution, is derived by the reductive perturbation method. The effects of external magnetic field and dust characteristics on the amplitude and the width of these solitary structures are examined. The implications of these results to some space and astrophysical plasma systems, especially to planetary ring-systems, are briefly mentioned. (author)

  10. Six-day westward propagating wave in the maximum electron density of the ionosphere

    Directory of Open Access Journals (Sweden)

    D. Altadill

    2003-07-01

    Full Text Available Analyses of time-spatial variations of critical plasma frequency foF2 during the summer of 1998 reveal the existence of an oscillation activity with attributes of a 6-day westward propagating wave. This event manifests itself as a global scale wave in the foF2 of the Northern Hemisphere, having a zonal wave number 2. This event coincides with a 6-day oscillation activity in the meridional neutral winds of the mesosphere/lower thermosphere (MLT. The oscillation in neutral winds seems to be linked to the 6–7-day global scale unstable mode westward propagating wave number 1 in the MLT. The forcing mechanisms of the 6-day wave event in the ionosphere from the wave activity in the MLT are discussed.Key words. Ionosphere (Ionosphere-Atmosphere interactions; Mid-latitude Ionosphere – Meterology and atmospheric dynamics (waves and tides

  11. Six-day westward propagating wave in the maximum electron density of the ionosphere

    Directory of Open Access Journals (Sweden)

    D. Altadill

    Full Text Available Analyses of time-spatial variations of critical plasma frequency foF2 during the summer of 1998 reveal the existence of an oscillation activity with attributes of a 6-day westward propagating wave. This event manifests itself as a global scale wave in the foF2 of the Northern Hemisphere, having a zonal wave number 2. This event coincides with a 6-day oscillation activity in the meridional neutral winds of the mesosphere/lower thermosphere (MLT. The oscillation in neutral winds seems to be linked to the 6–7-day global scale unstable mode westward propagating wave number 1 in the MLT. The forcing mechanisms of the 6-day wave event in the ionosphere from the wave activity in the MLT are discussed.

    Key words. Ionosphere (Ionosphere-Atmosphere interactions; Mid-latitude Ionosphere – Meterology and atmospheric dynamics (waves and tides

  12. In-situ transmission electron microscopy observation of slip propagation in ä3 bicrystals

    Czech Academy of Sciences Publication Activity Database

    Gemperlová, Juliana; Jacques, A.; Gemperle, Antonín; Vystavěl, Tomáš; Zárubová, Niva; Janecek, M.

    2002-01-01

    Roč. 324, - (2002), s. 183-189 ISSN 0921-5093 R&D Projects: GA ČR GA202/98/1281 Institutional research plan: CEZ:AV0Z1010914 Keywords : in- situ TEM deformation * propagation of slip * plastic deformation * grain boundary * symmetrical ä3 bicrystal Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.107, year: 2002

  13. Finite geometry effects on the stability of a charged beam propagating through a relativistic annular electron beam

    International Nuclear Information System (INIS)

    Ganguli, G.; Palmadesso, P.

    1984-01-01

    Finite geometry effects on the stability properties of a charged beam propagating through an intense relativistic annular electron beam have been studied. The stability of the system under transverse oscillation has been examined in detail in a parameter domain pertinent to the collective particle accelerator, currently under development at the Naval Research Laboratory. Both the normal mode and the convective aspects of this instability have been investigated. Despite a substantial temporal growth rate as predicted by the normal mode approach, this instability does not prevent successful acceleration of a portion of the axial beam. Thus the transverse oscillation is not fatal to the collective particle accelerator operation

  14. Electron propagator calculations on the ionization energies of CrH -, MnH - and FeH -

    Science.gov (United States)

    Lin, Jyh-Shing; Ortiz, J. V.

    1990-08-01

    Electron propagator calculations with unrestricted Hartree-Fock reference states yield the ionization energies of the title anions. Spin contamination in the anionic reference state is small, enabling the use of second-and third-order self-energies in the Dyson equation. Feynman-Dyson amplitudes for these ionizations are essentially identical to canonical spin-orbitals. For most of the final states, these consist of an antibonding combination of an sp metal hybrid, polarized away from the hydrogen, and hydroegen s functions. In one case, the Feynman-Dyson amplitude consists of nonbonding d functions. Calculated ionization energies are within 0.5 eV of experiment.

  15. Shock-wave propagation and reflection in semicrystalline polyethylene: A molecular-level investigation

    Science.gov (United States)

    Elder, Robert M.; O'Connor, Thomas C.; Chantawansri, Tanya L.; Sliozberg, Yelena R.; Sirk, Timothy W.; Yeh, In-Chul; Robbins, Mark O.; Andzelm, Jan W.

    2017-09-01

    Semicrystalline polyethylene (PE) is attractive for a variety of mechanically demanding applications, where shock compression can occur. Although often highly crystalline, PE invariably contains nanoscale amorphous domains that influence shock propagation. Our objective in this work is to study the effects of such domains. To this end, we adopt a novel approach wherein we parametrize a simple continuum-level theory based on the shock impedance from molecular dynamics (MD) simulations. Using this theory, we predict how crystalline/amorphous interfaces attenuate shocks via energy reflection due to the impedance mismatch between the phases. The theory predicts that these interfaces attenuate weak shocks more effectively than strong shocks. We compare the theory to explicit nonequilibrium MD simulations of compressive shocks in semicrystalline PE containing nanometer-scale amorphous regions of varying size, where we analyze the pressure response and reflection of energy. The theory and simulations show good agreement for strong shocks (≥1.0 km /s ), but for weak shocks (shock front. However, the simulations show that when amorphous domains are narrow—with widths comparable to the shock front—reflection is reduced compared to the predictions. We identify several nanoscale mechanisms that reduce the impedance mismatch, and thus reduce reflection, at thin amorphous domains. First, the two-wave elastic-plastic structure of shocks in crystalline PE allows the faster-moving elastic precursor wave to compress small amorphous domains before the plastic wave arrives. Second, confinement between stiff, ordered crystalline domains increases the stiffness and chain ordering in small amorphous regions. Moreover, in terms of stiffness the interfaces are similar in width to the shock front, which may contribute to the underprediction of the theory for weak shocks, where the shock front is widest. We conclude by discussing the significance of these results, namely, how they can

  16. Phase mixing of transverse oscillations in the linear and nonlinear regimes for IFR relativistic electron beam propagation

    International Nuclear Information System (INIS)

    Shokair, I.R.

    1991-01-01

    Phase mixing of transverse oscillations changes the nature of the ion hose instability from an absolute to a convective instability. The stronger the phase mixing, the faster an electron beam reaches equilibrium with the guiding ion channel. This is important for long distance propagation of relativistic electron beams where it is desired that transverse oscillations phase mix within a few betatron wavelengths of injection and subsequently an equilibrium is reached with no further beam emittance growth. In the linear regime phase mixing is well understood and results in asymptotic decay of transverse oscillations as 1/Z 2 for a Gaussian beam and channel system, Z being the axial distance measured in betatron wavelengths. In the nonlinear regime (which is likely mode of propagation for long pulse beams) results of the spread mass model indicate that phase mixing is considerably weaker than in the regime. In this paper we consider this problem of phase mixing in the nonlinear regime. Results of the spread mass model will be shown along with a simple analysis of phase mixing for multiple oscillator models. Particle simulations also indicate that phase mixing is weaker in nonlinear regime than in the linear regime. These results will also be shown. 3 refs., 4 figs

  17. Study on intense relativistic electron beam propagation in a low density collisionless plasma

    International Nuclear Information System (INIS)

    Korenev, S.A.; Rubin, N.B.; Khodataev, K.V.

    1982-01-01

    The results of investigations into the increase in effectivity of transport of an intensive relativistic electron beam (IREB) in a collisionless plasma of low density are presented. The electron beam with the current of 1.5 kA, energy of 300 keV, radius of 1.5 cm is in ected into a plasma channel 180 cm long which is a metallic cylinder covered with a biniplast layer from inside 0.5 cm thickness on which there is a metallic net from the vacuum side. Plasma production is carried out during the supply of voltage pulse to the net. A condition of the optimum IREB distribution is found. It is sohwn that self-focusing IREB transport in plasma of low density can be effective if equilibrium conditions are carried out in plasma with the concentration of electrons less (or equal) to the concentration of electrons in a beam

  18. Dispersion relation and growth rate of a relativistic electron beam propagating through a Langmuir wave wiggler

    Science.gov (United States)

    Zirak, H.; Jafari, S.

    2015-06-01

    In this study, a theory of free-electron laser (FEL) with a Langmuir wave wiggler in the presence of an axial magnetic field has been presented. The small wavelength of the plasma wave (in the sub-mm range) allows obtaining higher frequency than conventional wiggler FELs. Electron trajectories have been obtained by solving the equations of motion for a single electron. In addition, a fourth-order Runge-Kutta method has been used to simulate the electron trajectories. Employing a perturbation analysis, the dispersion relation for an electromagnetic and space-charge waves has been derived by solving the momentum transfer, continuity, and wave equations. Numerical calculations show that the growth rate increases with increasing the e-beam energy and e-beam density, while it decreases with increasing the strength of the axial guide magnetic field.

  19. Hybrid matrix method for stable numerical analysis of the propagation of Dirac electrons in gapless bilayer graphene superlattices

    Science.gov (United States)

    Briones-Torres, J. A.; Pernas-Salomón, R.; Pérez-Álvarez, R.; Rodríguez-Vargas, I.

    2016-05-01

    Gapless bilayer graphene (GBG), like monolayer graphene, is a material system with unique properties, such as anti-Klein tunneling and intrinsic Fano resonances. These properties rely on the gapless parabolic dispersion relation and the chiral nature of bilayer graphene electrons. In addition, propagating and evanescent electron states coexist inherently in this material, giving rise to these exotic properties. In this sense, bilayer graphene is unique, since in most material systems in which Fano resonance phenomena are manifested an external source that provides extended states is required. However, from a numerical standpoint, the presence of evanescent-divergent states in the eigenfunctions linear superposition representing the Dirac spinors, leads to a numerical degradation (the so called Ωd problem) in the practical applications of the standard Coefficient Transfer Matrix (K) method used to study charge transport properties in Bilayer Graphene based multi-barrier systems. We present here a straightforward procedure based in the hybrid compliance-stiffness matrix method (H) that can overcome this numerical degradation. Our results show that in contrast to standard matrix method, the proposed H method is suitable to study the transmission and transport properties of electrons in GBG superlattice since it remains numerically stable regardless the size of the superlattice and the range of values taken by the input parameters: the energy and angle of the incident electrons, the barrier height and the thickness and number of barriers. We show that the matrix determinant can be used as a test of the numerical accuracy in real calculations.

  20. Electron trapping in the electrosound solitary wave for propagation of high intensity laser in a relativistic plasma

    International Nuclear Information System (INIS)

    Heidari, E; Aslaninejad, M; Eshraghi, H

    2010-01-01

    Using a set of relativistic equations for plasmas with warm electrons and cold ions, we have investigated the effects of trapped electrons in the propagation of an electrosound wave and discussed the possibility of the formation of electromagnetic solitons in a plasma. The effective potential energy and deviations of the electron and ion number densities in this relativistic model have been found. We have obtained the governing equations for the amplitude of the HF field with relativistic corrections. In order to show the destructive impact of the trapped electrons on the solitary wave, a relativistic effective potential and the governing equation have been found. It is shown that for certain values of the parameters the condition of localization of the HF amplitude is violated. In addition, it is shown that as the flow velocity of the plasma changes, the shape of the solitary wave shows two opposing behaviours, depending on whether the solitary wave velocity is larger than the flow velocity or smaller. Also, the existence of stationary solitary waves which are prohibited for nonrelativistic plasma has been predicted. Finally, we have obtained the Korteweg-de Vries equation showing the relativistic, trapping and nonlinearity effects.

  1. Magnetic-field generation and electron-collimation analysis for propagating fast electron beams in overdense plasmas

    International Nuclear Information System (INIS)

    Cai Hongbo; Zhu Shaoping; Chen Mo; Wu Sizhong; He, X. T.; Mima, Kunioki

    2011-01-01

    An analytical fluid model is proposed for artificially collimating fast electron beams produced in the interaction of ultraintense laser pulses with specially engineered low-density-core-high-density-cladding structure targets. Since this theory clearly predicts the characteristics of the spontaneously generated magnetic field and its dependence on the plasma parameters of the targets transporting fast electrons, it is of substantial relevance to the target design for fast ignition. The theory also reveals that the rapid changing of the flow velocity of the background electrons in a transverse direction (perpendicular to the flow velocity) caused by the density jump dominates the generation of a spontaneous interface magnetic field for these kinds of targets. It is found that the spontaneously generated magnetic field reaches as high as 100 MG, which is large enough to collimate fast electron transport in overdense plasmas. This theory is also supported by numerical simulations performed using a two-dimensional particle-in-cell code. It is found that the simulation results agree well with the theoretical analysis.

  2. Energetic electron propagation in the decay phase of non-thermal flare emission

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jing; Yan, Yihua [Key Laboratory of Solar Activities, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Tsap, Yuri T., E-mail: huangj@nao.cas.cn [Crimean Astrophysical Observatory of Kyiv National Taras Shevchenko University, 98409 Crimea, Nauchny (Ukraine)

    2014-06-01

    On the basis of the trap-plus-precipitation model, the peculiarities of non-thermal emission in the decay phase of solar flares have been considered. The calculation formulas for the escape rate of trapped electrons into the loss cone in terms of time profiles of hard X-ray (HXR) and microwave (MW) emission have been obtained. It has been found that the evolution of the spectral indices of non-thermal emission depend on the regimes of the pitch angle diffusion of trapped particles into the loss cone. The properties of non-thermal electrons related to the HXR and MW emission of the solar flare on 2004 November 3 are studied with Nobeyama Radioheliograph, Nobeyama Radio Polarimeters, RHESSI, and Geostationary Operational Environmental Satellite observations. The spectral indices of non-thermal electrons related to MW and HXR emission remained constant or decreased, while the MW escape rate as distinguished from that of the HXRs increased. This may be associated with different diffusion regimes of trapped electrons into the loss cone. New arguments in favor of an important role of the superstrong diffusion for high-energy electrons in flare coronal loops have been obtained.

  3. Thermal field theory in a layer: Applications of thermal field theory methods to the propagation of photons in a two-dimensional electron sheet

    International Nuclear Information System (INIS)

    Nieves, Jose F.

    2010-01-01

    We apply the thermal field theory methods to study the propagation of photons in a plasma layer, that is a plasma in which the electrons are confined to a two-dimensional plane sheet. We calculate the photon self-energy and determine the appropriate expression for the photon propagator in such a medium, from which the properties of the propagating modes are obtained. The formulas for the photon dispersion relations and polarization vectors are derived explicitly in some detail for some simple cases of the thermal distributions of the charged particle gas, and appropriate formulas that are applicable in more general situations are also given.

  4. Laser pulse propagation and enhanced energy coupling to fast electrons in dense plasma gradients

    International Nuclear Information System (INIS)

    Gray, R J; Carroll, D C; Yuan, X H; Brenner, C M; Coury, M; Quinn, M N; Tresca, O; McKenna, P; Burza, M; Wahlström, C-G; Lancaster, K L; Neely, D; Lin, X X; Li, Y T

    2014-01-01

    Laser energy absorption to fast electrons during the interaction of an ultra-intense (10 20 W cm −2 ), picosecond laser pulse with a solid is investigated, experimentally and numerically, as a function of the plasma density scale length at the irradiated surface. It is shown that there is an optimum density gradient for efficient energy coupling to electrons and that this arises due to strong self-focusing and channeling driving energy absorption over an extended length in the preformed plasma. At longer density gradients the laser filaments, resulting in significantly lower overall energy coupling. As the scale length is further increased, a transition to a second laser energy absorption process is observed experimentally via multiple diagnostics. The results demonstrate that it is possible to significantly enhance laser energy absorption and coupling to fast electrons by dynamically controlling the plasma density gradient. (paper)

  5. Propagation and forcing of high-frequency sea level variability along the west coast of South America

    Science.gov (United States)

    del Pilar Cornejo-Rodriguez, Maria; Enfield, David B.

    1987-12-01

    Tide and wind data from coastal and island stations from Buenaventura, Colombia (4°N), to Callao, Peru (12°S), have been analyzed for the 1979-1984 time period to determine the propagation and forcing characteristics of coastal sea level variability at periods of days to weeks, as well as how they vary either with season or between the 1982-1983 El Niño-Southern Oscillation (ENSO) period and non-ENSO years. During four non-ENSO years, the ensemble averaged cross spectra between coastal sea level height (SLH) and local winds show weak evidence of local forcing during the whole year without significant differences between the austral summer and winter seasons, other than a greater energy in the wind fluctuations at Talara during summer. Cross spectra between SLH series from neighboring stations show evidence of poleward phase propagation during winter seasons at speeds of about 2.0 m s-1 between La Libertad and Talara at periods of a week or more, and about 2.7 m s-1 between Talara and Callao at periods of 5-11 days, but no propagation is found during summers. During the 1982-1983 ENSO there is a large increase in SLH energy at most frequencies at all coastal stations, but especially in the 8-to-11-day band, where energies are enhanced by as much as an order of magnitude above non-ENSO levels. The cross spectra between adjacent SLH stations indicate a nondispersive poleward propagation of events during the 1982-1983 ENSO with phase speeds of 2.2-3.5 m s-1 from La Libertad to Talara (periods of a week or more) and 3.4-3.6 m s-1 from Talara to Callao (3.5 days or more). As with the SLH energy, the coherence and phase propagation were much stronger along the Peru coast in 1982-1983 than during non-ENSO periods, especially in the 8-to-11-day band. The one-third increase in phase speeds during the ENSO over the non-ENSO speeds is found to be consistent with the anomalous depressions of the density structure during El Niño. Comparisons between coastal SLH and the local

  6. Superluminal propagation in a poly-chromatically driven gain assisted four-level N-type atomic system

    International Nuclear Information System (INIS)

    Bacha, Bakht Amin; Ahmad, Iftikhar; Ullah, Arif; Ali, Hazrat

    2013-01-01

    We investigate the behavior of light propagation in an N-type four-level gain assisted model (Agarwal and Dasgupta 2004 Phys. Rev. A 70 023802) under poly-chromatic pump fields. The system exhibits interesting results of multiple controllable pairs of the gain doublet profile with changes in the intensity of the control field. We observe multiple anomalous dispersive regions for superluminal propagation in the medium. A negative group velocity of −37.50 m s −1 with a negative time delay of −8 ms is observed between each gain doublet in anomalous dispersive regions. This generalized model and its predictions can be tested with existing experimental setups. (paper)

  7. Free-electron laser with a plasma wave wiggler propagating through a magnetized plasma channel

    International Nuclear Information System (INIS)

    Jafari, S; Jafarinia, F; Mehdian, H

    2013-01-01

    A plasma eigenmode has been employed as a wiggler in a magnetized plasma channel for the generation of laser radiation in a free-electron laser. The short wavelength of the plasma wave allows a higher radiation frequency to be obtained than from conventional wiggler free-electron lasers. The plasma can significantly slow down the radiation mode, thereby relaxing the beam energy requirement considerably. In addition, it allows a beam current in excess of the vacuum current limit via charge neutralization. This configuration has a higher tunability by controlling the plasma density in addition to the γ-tunability of the standard FEL. The laser gain has been calculated and numerical computations of the electron trajectories and gain are presented. Four groups (I–IV) of electron orbits have been found. It has been shown that by increasing the cyclotron frequency, the gain for orbits of group I and group III increases, while a decrease in gain has been obtained for orbits of group II and group IV. Similarly, the effect of plasma density on gain has been exhibited. The results indicate that with increasing plasma density, the orbits of all groups shift to higher cyclotron frequencies. The effects of beam self-fields on gain have also been demonstrated. It has been found that in the presence of beam self-fields the sensitivity of the gain increases substantially in the vicinity of gyroresonance. Here, the gain enhancement and reduction are due to the paramagnetic and diamagnetic effects of the self-magnetic field, respectively. (paper)

  8. MgH Rydberg series: Transition energies from electron propagator theory and oscillator strengths from the molecular quantum defect orbital method

    Science.gov (United States)

    Corzo, H. H.; Velasco, A. M.; Lavín, C.; Ortiz, J. V.

    2018-02-01

    Vertical excitation energies belonging to several Rydberg series of MgH have been inferred from 3+ electron-propagator calculations of the electron affinities of MgH+ and are in close agreement with experiment. Many electronically excited states with n > 3 are reported for the first time and new insight is given on the assignment of several Rydberg series. Valence and Rydberg excited states of MgH are distinguished respectively by high and low pole strengths corresponding to Dyson orbitals of electron attachment to the cation. By applying the Molecular Quantum Defect Orbital method, oscillator strengths for electronic transitions involving Rydberg states also have been determined.

  9. Geometry of the diffusive propagation region in the August 14, 1982 solar electron event

    Science.gov (United States)

    Evenson, P. A.

    1985-01-01

    On August 14, 1982, relativistic electrons arrived promptly after an impulsive gamma ray flare, indicating that very little scattering was taking place in interplanetary space. By ignoring anisotropy data the time profile of the event is well described by interplanetary diffusion except for the derived particle injection time. This discrepancy provides independent evidence that the particles are diffusing in a volume close to the Sun rather than in interplanetary space. The flux at maximum method of determining the number of particles produced is still a good approximation when appropriately applied.

  10. Effects of buried high-Z layers on fast electron propagation

    Czech Academy of Sciences Publication Activity Database

    Yang, X.; Xu, H.; Zhuo, H.; Ma, Y.; Shao, F.; Yin, Y.; Borghesi, Marco

    2014-01-01

    Roč. 68, č. 2 (2014), s. 1-7 ISSN 1434-6060 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : laser-plasma interactions * short-pulse * hot-electrons * solid targets * transport * field Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.228, year: 2014

  11. Analysis of Plane-Parallel Electron Beam Propagation in Different Media by Numerical Simulation Methods

    Science.gov (United States)

    Miloichikova, I. A.; Bespalov, V. I.; Krasnykh, A. A.; Stuchebrov, S. G.; Cherepennikov, Yu. M.; Dusaev, R. R.

    2018-04-01

    Simulation by the Monte Carlo method is widely used to calculate the character of ionizing radiation interaction with substance. A wide variety of programs based on the given method allows users to choose the most suitable package for solving computational problems. In turn, it is important to know exactly restrictions of numerical systems to avoid gross errors. Results of estimation of the feasibility of application of the program PCLab (Computer Laboratory, version 9.9) for numerical simulation of the electron energy distribution absorbed in beryllium, aluminum, gold, and water for industrial, research, and clinical beams are presented. The data obtained using programs ITS and Geant4 being the most popular software packages for solving the given problems and the program PCLab are presented in the graphic form. A comparison and an analysis of the results obtained demonstrate the feasibility of application of the program PCLab for simulation of the absorbed energy distribution and dose of electrons in various materials for energies in the range 1-20 MeV.

  12. Electron Energy Level Statistics in Graphene Quantum Dots

    NARCIS (Netherlands)

    De Raedt, H.; Katsnellson, M. I.; Katsnelson, M.I.

    2008-01-01

    Motivated by recent experimental observations of size quantization of electron energy levels in graphene quantum dots [7] we investigate the level statistics in the simplest tight-binding model for different dot shapes by computer simulation. The results are in a reasonable agreement with the

  13. A quasi-one-dimensional velocity regime of super-thermal electron stream propagation through the solar corona

    International Nuclear Information System (INIS)

    Levin, B.N.

    1984-01-01

    The propagation of an inhomogeneous stream of fast electrons through the corona - the type III radio burst source - is considered. It is shown, that the angular spectrum width of plasma waves excited by the stream is defined both by Landau damping by particles of the diffuse component and by damping (in the region of large phase velocities) by particles of the stream itself having large pitch angles. The regime of quasi-one-dimensional diffusion in the velocity space is realized only in the presence of a sufficiently dense diffuse component of super-thermal particles and only for a sufficiently large inhomogeneity scale of the stream. A large scale of the stream space profile is formed, evidently, close to the region of injection of super-thermal particles. It is the result of 'stripping' of part of the electrons from the stream front to its slower part due to essential non-one-dimensionality of the particle diffusion in velocity space. Results obtained may explain, in particular, the evolution of a stream particle angular spectrum in the generation region of type III radio bursts observed by spacecrafts (Lin et al., 1981). For the relatively low energetic part of the stream, the oblique plasma wave stabilization by a diffuse component results in a quasi-one-dimensional regime of diffusion. The latter conserves the beam-like structure of this part of the stream. (orig.)

  14. Semianalytical study of the propagation of an ultrastrong femtosecond laser pulse in a plasma with ultrarelativistic electron jitter

    Energy Technology Data Exchange (ETDEWEB)

    Jovanović, Dušan, E-mail: dusan.jovanovic@ipb.ac.rs [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade, Zemun (Serbia); Fedele, Renato, E-mail: renato.fedele@na.infn.it [Dipartimento di Fisica, Università di Napoli “Federico II,” M.S. Angelo, Napoli (Italy); INFN Sezione di Napoli, Complesso Universitario di M.S. Angelo, Napoli (Italy); Belić, Milivoj, E-mail: milivoj.belic@qatar.tamu.edu [Texas A and M University at Qatar, P.O. Box 23874, Doha (Qatar); De Nicola, Sergio, E-mail: sergio.denicola@spin.cnr.it [SPIN-CNR, Complesso Universitario di M.S. Angelo, Napoli (Italy)

    2015-04-15

    The interaction of a multi-petawatt, pancake-shaped laser pulse with an unmagnetized plasma is studied analytically and numerically in a regime with ultrarelativistic electron jitter velocities, in which the plasma electrons are almost completely expelled from the pulse region. The study is applied to a laser wakefield acceleration scheme with specifications that may be available in the next generation of Ti:Sa lasers and with the use of recently developed pulse compression techniques. A set of novel nonlinear equations is derived using a three-timescale description, with an intermediate timescale associated with the nonlinear phase of the electromagnetic wave and with the spatial bending of its wave front. They describe, on an equal footing, both the strong and the moderate laser intensity regimes, pertinent to the core and to the edges of the pulse. These have fundamentally different dispersive properties since in the core the electrons are almost completely expelled by a very strong ponderomotive force, and the electromagnetic wave packet is imbedded in a vacuum channel, thus having (almost) linear properties. Conversely, at the pulse edges, the laser amplitude is smaller, and the wave is weakly nonlinear and dispersive. New nonlinear terms in the wave equation, introduced by the nonlinear phase, describe without the violation of imposed scaling laws a smooth transition to a nondispersive electromagnetic wave at very large intensities and a simultaneous saturation of the (initially cubic) nonlocal nonlinearity. The temporal evolution of the laser pulse is studied both analytically and by numerically solving the model equations in a two-dimensional geometry, with the spot diameter presently used in some laser acceleration experiments. The most stable initial pulse length is estimated to exceed ≳1.5–2 μm. Moderate stretching of the pulse in the direction of propagation is observed, followed by the development of a vacuum channel and of a very large

  15. Pitch-angle diffusion of electrons through growing and propagating along a magnetic field electromagnetic wave in Earth's radiation belts

    International Nuclear Information System (INIS)

    Choi, C.-R.; Dokgo, K.; Min, K.-W.; Woo, M.-H.; Choi, E.-J.; Hwang, J.; Park, Y.-D.; Lee, D.-Y.

    2015-01-01

    The diffusion of electrons via a linearly polarized, growing electromagnetic (EM) wave propagating along a uniform magnetic field is investigated. The diffusion of electrons that interact with the growing EM wave is investigated through the autocorrelation function of the parallel electron acceleration in several tens of electron gyration timescales, which is a relatively short time compared with the bounce time of electrons between two mirror points in Earth's radiation belts. Furthermore, the pitch-angle diffusion coefficient is derived for the resonant and non-resonant electrons, and the effect of the wave growth on the electron diffusion is discussed. The results can be applied to other problems related to local acceleration or the heating of electrons in space plasmas, such as in the radiation belts

  16. Ion temperature effects on magnetotail Alfvén wave propagation and electron energization: ION TEMPERATURE EFFECTS ON ALFVÉN WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Damiano, P. A. [Princeton Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton University, Princeton New Jersey USA; Johnson, J. R. [Princeton Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton University, Princeton New Jersey USA; Chaston, C. C. [Space Sciences Laboratory, University of California, Berkeley California USA; School of Physics, University of Sydney, Sydney New South Wales Australia

    2015-07-01

    A new 2-D self-consistent hybrid gyrofluid-kinetic electron model in dipolar coordinates is presented and used to simulate dispersive-scale Alfvén wave pulse propagation from the equator to the ionosphere along an L = 10 magnetic field line. The model is an extension of the hybrid MHD-kinetic electron model that incorporates ion Larmor radius corrections via the kinetic fluid model of Cheng and Johnson (1999). It is found that consideration of a realistic ion to electron temperature ratio decreases the propagation time of the wave from the plasma sheet to the ionosphere by several seconds relative to a ρi=0 case (which also implies shorter timing for a substorm onset signal) and leads to significant dispersion of wave energy perpendicular to the ambient magnetic field. Additionally, ion temperature effects reduce the parallel current and electron energization all along the field line for the same magnitude perpendicular electric field perturbation.

  17. A fresh look at the photoelectron spectrum of bromobenzene: A third-order non-Dyson electron propagator study

    International Nuclear Information System (INIS)

    Schneider, M.; Wormit, M.; Dreuw, A.; Soshnikov, D. Yu.; Trofimov, A. B.; Holland, D. M. P.; Powis, I.; Antonsson, E.; Patanen, M.; Nicolas, C.; Miron, C.

    2015-01-01

    The valence-shell ionization spectrum of bromobenzene, as a representative halogen substituted aromatic, was studied using the non-Dyson third-order algebraic-diagrammatic construction [nD-ADC(3)] approximation for the electron propagator. This method, also referred to as IP-ADC(3), was implemented as a part of the Q-Chem program and enables large-scale calculations of the ionization spectra, where the computational effort scales as n 5 with respect to the number of molecular orbitals n. The IP-ADC(3) scheme is ideally suited for investigating low-lying ionization transitions, so fresh insight could be gained into the cationic state manifold of bromobenzene. In particular, the present IP-ADC(3) calculations with the cc-pVTZ basis reveal a whole class of low-lying low-intensity two-hole-one-particle (2h-1p) doublet and quartet states, which are relevant to various photoionization processes. The good qualitative agreement between the theoretical spectral profile for the valence-shell ionization transitions generated with the smaller cc-pVDZ basis set and the experimental photoelectron spectrum measured at a photon energy of 80 eV on the PLÉIADES beamline at the Soleil synchrotron radiation source allowed all the main features to be assigned. Some theoretical aspects of the ionization energy calculations concerning the use of various approximation schemes and basis sets are discussed

  18. The upper level of control system of electron accelerators

    International Nuclear Information System (INIS)

    Gribov, I.V.; Nedeoglo, F.N.; Shvedunov, I.V.

    2005-01-01

    The upper level software of a three-level control system that supports several electron accelerators is described. This software operates in the Linux and RTLinux (Real Time Linux) environment. The object information model functions on the basis of a parametric description supported by the SQLite Data Base Management System. The Javascript sublanguage is used for script forming, and the Qt Designer application is used to construct the user interface [ru

  19. Interaction between electrons and tunneling levels in metallic glasses

    International Nuclear Information System (INIS)

    Black, J.L.; Gyorffy, B.L.

    1978-01-01

    A simple model in which the conduction electrons of a metallic glass experience a local time-dependent potential due to two-level tunneling states is considered. The model exhibits interesting divergent behavior which is quite different from that predicted by an earlier ''s-d Kondo'' model

  20. Assessment of noise level and noise propagation generated by light-lift helicopters in mountain natural environments.

    Science.gov (United States)

    Grigolato, Stefano; Mologni, Omar; Proto, Andrea Rosario; Zimbalatti, Giuseppe; Cavalli, Raffaele

    2018-01-20

    The use of helicopter rises discussion about environmental noise propagation especially when it operates in proximity of environmentally sensitive areas (ESAs) for an extended period because of its potential implications in wildlife behaviours. In order to support decisions on helicopter logging operation management in proximity of ESAs, this study focused on (i) analysing the noise spectrum of a light-lift helicopter during logging operations and on (ii) assessing the noise propagation in the surrounding environments. This study investigated a helicopter logging operation for wood fuel extraction in the eastern part of the Italian Alps. The potential disturbance area covered for the entire helicopter logging operation was evaluated by a specific GIS application according to hearing sensitivity of the most sensitive wildlife species in the study area (different strigiform species). The noise level at the ground appeared to be affected by the location regardless both the use of equivalent continuous sound pressures level dB(A) (LAeq) and the single-event level (SEL) noise metrics. The lowest values were recorded when the helicopter was flown over the sound meter level located under the forest canopy, while the highest was recorded when the helicopter was unhooking the loads at the landing. The GIS application highlighted the consistent of the exceeded noise area (weighted to strigiform hearing range and sensitivity) for the lower frequency bands (0.016-0.250 kHz). A more restricted exceeded noise area concerned instead the most sensitive frequency bands" for the strigiform (1-2 kHz). Graphical abstract ᅟ.

  1. Accelerated uncertainty propagation in two-level probabilistic studies under monotony

    International Nuclear Information System (INIS)

    Limbourg, Philipp; Rocquigny, Etienne de; Andrianov, Guennadi

    2010-01-01

    Double-level probabilistic uncertainty models that separate aleatory and epistemic components enjoy significant interest in risk assessment. But the expensive computational costs associated with calculations of rare failure probabilities are still a large obstacle in practice. Computing accurately a risk lower than 10 -3 with 95% epistemic confidence usually requires 10 7 -10 8 runs in a brute-force double Monte Carlo. For single-level probabilistic studies, FORM (First Order Reliability Analysis) is a classical recipe allowing fast approximation of failure probabilities while MRM (Monotonous Reliability Method) recently proved an attractive robust alternative under monotony. This paper extends these methods to double-level probabilistic models through two novel algorithms designed to compute a set of failure probabilities or an aleatory risk level with an epistemic confidence quantile. The first, L2-FORM (level-2 FORM), allows a rapid approximation of the failure probabilities through a combination of FORM with new ideas to use similarity between computations. L2-MRM (level-2 MRM), a quadrature approach, provides 100%-guaranteed error bounds on the results. Experiments on three flood prediction problems showed that both algorithms approximate a set of 500 failure probabilities of 10 -3 -10 -2 or derived 95% epistemic quantiles with a total of only 500-1000 function evaluations, outperforming importance sampling, iterative FORM and regression splines metamodels.

  2. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter

    International Nuclear Information System (INIS)

    Pisani, F.

    2000-02-01

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  3. In-situ investigation of crack propagation in {gamma}-TiAl alloys using atomic force, focus ion beam and scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Farasat; Goeken, Mathias [Lehrstuhl Allgemeine Werkstoffeigenschaften, Friedrich-Alexander-Universitaet Erlangen-Nuernberg (Germany); Pyczak, Florian [GKSS Research Centre Geesthacht, Geesthacht (Germany)

    2009-07-01

    The present study is focused on crack propagation mechanism in Ti-45Al-1Cr and Ti-45Al-5Nb alloys with lamellar microstructure. Atomic force microscopy (AFM) is a versatile technique to study the crack propagation in-situ. AFM was employed to investigate the local deformations near the crack tip. Scanning electron microscopy (SEM) supplements the in-situ observations and was used to get a basic understanding of the crack propagation path over larger distances.A focused ion beam (FIB) was used to investigate the structures and deformation traces underneath the surface. It is concluded that the {gamma}/{alpha}2 interfaces act as favorable sites for new interfacial crack nucleation and also for interlamellar crack propagation. Nucleation of new cracks was often preceded by the interaction of deformation twins with interfaces and also by strong shear band activity in the {gamma}-TiAl lamellae visible as significant surface topography in AFM.Mostly the underneath crack path follows the {gamma}/{alpha}2 interface similar to the situation observed at the surface. The local misorientation measured with electron backscattered diffraction (EBSD) shows {gamma}-lamellae as the region of high deformation as compare to neighboring {alpha}2 -lamellae around the crack tip and its surroundings.

  4. Pulsar kicks with modified Urca and electrons in Landau levels

    International Nuclear Information System (INIS)

    Henley, Ernest M.; Johnson, Mikkel B.; Kisslinger, Leonard S.

    2007-01-01

    We derive the energy asymmetry given the protoneutron star during the time when the neutrino sphere is near the surface of the protoneutron star, using the modified Urca process. The electrons produced with the antineutrinos are in Landau levels due to the strong magnetic field, and this leads to asymmetry in the neutrino momentum, and a pulsar kick. The magnetic field must be strong enough for a large fraction of the electrons to be in the lowest Landau level; however, there is no direct dependence of our pulsar velocity on the strength of the magnetic field. Our main prediction is that the large pulsar kicks start at about 10 s and last for about 10 s, with the corresponding neutrinos correlated with the direction of the magnetic field. We predict a pulsar velocity of 1.03x10 -4 (T/10 10 K) 7 km/s, which reaches 1000 km/s if T≅10 11 K

  5. Electron spin polarization in realistic trajectories around the magnetic node of two counter-propagating, circularly polarized, ultra-intense lasers

    Science.gov (United States)

    Del Sorbo, D.; Seipt, D.; Thomas, A. G. R.; Ridgers, C. P.

    2018-06-01

    It has recently been suggested that two counter-propagating, circularly polarized, ultra-intense lasers can induce a strong electron spin polarization at the magnetic node of the electromagnetic field that they setup (Del Sorbo et al 2017 Phys. Rev. A 96 043407). We confirm these results by considering a more sophisticated description that integrates over realistic trajectories. The electron dynamics is weakly affected by the variation of power radiated due to the spin polarization. The degree of spin polarization differs by approximately 5% if considering electrons initially at rest or already in a circular orbit. The instability of trajectories at the magnetic node induces a spin precession associated with the electron migration that establishes an upper temporal limit to the polarization of the electron population of about one laser period.

  6. Effects of positron density and temperature on ion-acoustic solitary waves in a magnetized electron-positron-ion plasma: Oblique propagation

    International Nuclear Information System (INIS)

    Esfandyari-Kalejahi, A.; Akbari-Moghanjoughi, M.; Mehdipoor, M.

    2009-01-01

    Ion-acoustic (IA) solitary waves are investigated in a magnetized three-component plasma consisting of cold ions, isothermal hot electrons, and positrons. The basic set of fluid equations is reduced to the Korteweg de Vries equation using the standard reductive perturbation (multiple-scale) technique. Theoretical and numerical analyses confirm significant effects of the presence of positrons and the dependence of the electron to positron temperature ratio on the amplitude and the width of IA solitary waves. It is shown that the rarefactive and compressive IA solitary excitations can propagate when the propagation angle θ satisfies 0≤θ 0 , whereas their width depends strictly on B 0 . The numerical analysis has been done based on the typical numerical data from a pulsar magnetosphere.

  7. Mechanisms of molecular electronic rectification through electronic levels with strong vibrational coupling

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2002-01-01

    We present a new view and an analytical formalism of electron flow through a donor-acceptor molecule inserted between a pair of metal electrodes. The donor and acceptor levels are strongly coupled to an environmental nuclear continuum. The formalism applies to molecular donor-acceptor systems bot...

  8. Nicotine and Cotinine Levels With Electronic Cigarette: A Review.

    Science.gov (United States)

    Marsot, A; Simon, N

    2016-01-01

    Since their introduction in 2004, electronic cigarettes (e-cigarettes) have gained popularity worldwide. E-cigarettes are marketed as nicotine delivery devices. Commonly reported reasons for use include to quit smoking, to reduce urge to smoke, or the perceived lower risk alternative to smoking. But what are the actual amounts of nicotine delivered? This review summarizes all the published studies concerning nicotine or cotinine levels following e-cigarette use. A literature search was conducted from the PubMed database, from 1985 to January 2014, using the following terms: electronic cigarette(s), e-cigarette(s), electronic nicotine delivery system, cotinine, and nicotine. Articles were excluded if they were not pertinent according to our criteria. References of all relevant articles were also evaluated. Eight studies were included in this review. The following information was extracted from the articles: population size, age of participants, recruitment, inclusion and exclusion criteria, concentration of nicotine in refills liquids, study sample design, and observed concentrations. Following design of studies, plasma nicotine Cmax was observed between 0 and 5 ng/mL (no significant changes) or between 13.9 and 16.3 ng/mL (similar to a tobacco cigarette) with a Tmax between 70 and 75 minutes. Cotinine levels after "vaping" an e-cigarette are similar to a tobacco cigarette. This review summarizes e-cigarette studies that contain information on nicotine or cotinine levels. The peak concentration of nicotine appears to be dependent on the use and dose level of e-cigarette cartridge. The value of this peak concentration is similar to the value found with a tobacco cigarette. However, the time corresponding to the peak concentration is delayed compared to a tobacco cigarette. © The Author(s) 2015.

  9. Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

    Energy Technology Data Exchange (ETDEWEB)

    Etemadpour, R.; Dorranian, D., E-mail: doran@srbiau.ac.ir [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Sepehri Javan, N. [Department of Physics, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil (Iran, Islamic Republic of)

    2016-05-15

    The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

  10. Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

    International Nuclear Information System (INIS)

    Etemadpour, R.; Dorranian, D.; Sepehri Javan, N.

    2016-01-01

    The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

  11. Component-Level Electronic-Assembly Repair (CLEAR) System Architecture

    Science.gov (United States)

    Oeftering, Richard C.; Bradish, Martin A.; Juergens, Jeffrey R.; Lewis, Michael J.; Vrnak, Daniel R.

    2011-01-01

    This document captures the system architecture for a Component-Level Electronic-Assembly Repair (CLEAR) capability needed for electronics maintenance and repair of the Constellation Program (CxP). CLEAR is intended to improve flight system supportability and reduce the mass of spares required to maintain the electronics of human rated spacecraft on long duration missions. By necessity it allows the crew to make repairs that would otherwise be performed by Earth based repair depots. Because of practical knowledge and skill limitations of small spaceflight crews they must be augmented by Earth based support crews and automated repair equipment. This system architecture covers the complete system from ground-user to flight hardware and flight crew and defines an Earth segment and a Space segment. The Earth Segment involves database management, operational planning, and remote equipment programming and validation processes. The Space Segment involves the automated diagnostic, test and repair equipment required for a complete repair process. This document defines three major subsystems including, tele-operations that links the flight hardware to ground support, highly reconfigurable diagnostics and test instruments, and a CLEAR Repair Apparatus that automates the physical repair process.

  12. Component-Level Electronic-Assembly Repair (CLEAR) Operational Concept

    Science.gov (United States)

    Oeftering, Richard C.; Bradish, Martin A.; Juergens, Jeffrey R.; Lewis, Michael J.; Vrnak, Daniel R.

    2011-01-01

    This Component-Level Electronic-Assembly Repair (CLEAR) Operational Concept document was developed as a first step in developing the Component-Level Electronic-Assembly Repair (CLEAR) System Architecture (NASA/TM-2011-216956). The CLEAR operational concept defines how the system will be used by the Constellation Program and what needs it meets. The document creates scenarios for major elements of the CLEAR architecture. These scenarios are generic enough to apply to near-Earth, Moon, and Mars missions. The CLEAR operational concept involves basic assumptions about the overall program architecture and interactions with the CLEAR system architecture. The assumptions include spacecraft and operational constraints for near-Earth orbit, Moon, and Mars missions. This document addresses an incremental development strategy where capabilities evolve over time, but it is structured to prevent obsolescence. The approach minimizes flight hardware by exploiting Internet-like telecommunications that enables CLEAR capabilities to remain on Earth and to be uplinked as needed. To minimize crew time and operational cost, CLEAR exploits offline development and validation to support online teleoperations. Operational concept scenarios are developed for diagnostics, repair, and functional test operations. Many of the supporting functions defined in these operational scenarios are further defined as technologies in NASA/TM-2011-216956.

  13. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Science.gov (United States)

    Zhao, Jifei; Lu, Xiangyang; Zhou, Kui; Yang, Ziqin; Yang, Deyu; Luo, Xing; Tan, Weiwei; Yang, Yujia

    2016-06-01

    As an important electron source, Micro-Pulse electron Gun (MPG) which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR), Free Electron Laser (FEL). The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY) curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC) effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  14. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jifei; Lu, Xiangyang, E-mail: xylu@pku.edu.cn; Yang, Ziqin; Yang, Deyu; Tan, Weiwei; Yang, Yujia [Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, 100871 (China); Zhou, Kui; Luo, Xing [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China)

    2016-06-15

    As an important electron source, Micro-Pulse electron Gun (MPG) which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR), Free Electron Laser (FEL). The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY) curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC) effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  15. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Directory of Open Access Journals (Sweden)

    Jifei Zhao

    2016-06-01

    Full Text Available As an important electron source, Micro-Pulse electron Gun (MPG which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR, Free Electron Laser (FEL. The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  16. Urinary cotinine levels of electronic cigarette (e-cigarette) users.

    Science.gov (United States)

    Göney, Gülşen; Çok, İsmet; Tamer, Uğur; Burgaz, Sema; Şengezer, Tijen

    2016-07-01

    The popularity of electronic cigarettes (e-cigarettes) is rapidly increasing in many countries. These devices are designed to imitate regular cigarettes, delivering nicotine via inhalation without combusting tobacco but currently, there is a lack of scientific evidence on the presence or absence of nicotine exposure. Such research relies on evidence from e-cigarette users urine samples. In this study, we aimed to determine the levels and compare the amount of nicotine to which e-cigarette users, cigarette smokers and passive smokers are exposed. Therefore, urine samples were collected from e-cigarette users, cigarette smokers, passive smokers, and healthy nonsmokers. The urinary cotinine levels of the subjects were determined using gas chromatography-mass spectrometry. The mean (±SD) urinary cotinine levels were determined as 1755 ± 1848 ng/g creatinine for 32 e-cigarette users, 1720 ± 1335 ng/g creatinine for 33 cigarette smokers and 81.42 ± 97.90 ng/g creatinine for 33 passive smokers. A significant difference has been found between cotinine levels of e-cigarette users and passive smokers (p e-cigarette users and cigarette smokers (p > 0.05). This is a seminal study to demonstrate the e-cigarette users are exposed to nicotine as much as cigarette smokers.

  17. Polyelectrolytes processing at pilot scale level by electron beam irradiation

    International Nuclear Information System (INIS)

    Martin, D.; Cirstea, E.; Craciun, G.; Ighigeanu, D.; Marin, Gheorghe G.

    2002-01-01

    Three years of research, combined with engineering activities, have culminated in the development of a new method of electron beam processing applicable up to the pilot scale level, namely, the polyelectrolytes (acrylamide - acrylic acid copolymers) electron beam processing. This new radiation processing method has been achieved by bilateral co-operation between the National Institute for Laser, Plasma and Radiation Physics (NILPRP) and the Electrical Design and Research Institute, EDRI - Bucharest. The polyelectrolytes electron beam (EB) processing was put in operation at EDRI, where, recently, an industrial electron accelerator of 2 MeV and 20 kW, manufactured by Institute of Nuclear Physics, Novosibirsk, Russia was installed in a specially designed irradiation facility. Automatic start-up via computer control makes it compatible with industrial processing. According to the first conclusions, which resulted from our experimental research with regard to acrylamide - acrylic acid copolymers production by EB irradiation, the proper physical and chemical characteristics can be well controlled by chemical composition to be treated and by suitable adjustment of absorbed dose and absorbed dose rate. So, it was possible to obtain a very large area of characteristics and therefore a large area of applications. The conversion coefficient is very high (> 98%) and concentration of the residual monomer is under 0.05%. The tests applied to some wastewaters from the vegetable oil plants demonstrated that the fatty substances, matters in suspension, chemical oxygen demand and biological oxygen demand over 5 days were much reduced, in comparison with classical treatment. Also, sedimentation time was around four times smaller and sediment volume was 60% smaller than the values obtained in case of classical treatment. The necessary EB absorbed dose for the acrylamide - acrylic acid aqueous solution polymerization, established by optimization of chemical composition and irradiation

  18. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter; Etude experimentale de la propagation et du depot d'energie d'electrons rapides dans une cible solide ou comprimee par choc laser: application a l'allumeur rapide

    Energy Technology Data Exchange (ETDEWEB)

    Pisani, F

    2000-02-15

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  19. On the correct implementation of Fermi-Dirac statistics and electron trapping in nonlinear electrostatic plane wave propagation in collisionless plasmas

    Science.gov (United States)

    Schamel, Hans; Eliasson, Bengt

    2016-05-01

    Quantum statistics and electron trapping have a decisive influence on the propagation characteristics of coherent stationary electrostatic waves. The description of these strictly nonlinear structures, which are of electron hole type and violate linear Vlasov theory due to the particle trapping at any excitation amplitude, is obtained by a correct reduction of the three-dimensional Fermi-Dirac distribution function to one dimension and by a proper incorporation of trapping. For small but finite amplitudes, the holes become of cnoidal wave type and the electron density is shown to be described by a ϕ ( x ) 1 / 2 rather than a ϕ ( x ) expansion, where ϕ ( x ) is the electrostatic potential. The general coefficients are presented for a degenerate plasma as well as the quantum statistical analogue to these steady state coherent structures, including the shape of ϕ ( x ) and the nonlinear dispersion relation, which describes their phase velocity.

  20. Experimental study of fast electron transport and of the propagation of shock waves generated by laser in the framework of inertial fusion

    International Nuclear Information System (INIS)

    Sakaki, T.

    2016-01-01

    This document presents 3 experiments carried out within the framework of inertial fusion. The first experiment was devoted to the study of fast electron beam transport in a compressed target. The implosion of the target with a cylindrical geometry was carried out with the GEKKO XII laser facility (ILE Osaka, Japan). The fast electron beam was generated by the LFEX laser (∼10"1"9 W/cm"2) and its propagation through the compressed cylinder was observed with several X-ray diagnostics. This experiment showed the guiding effect of the electron beam resulting from self-generated magnetic fields. Furthermore, the results of this experiment were in good agreement with numerical simulations. Two other experiments were performed to study the propagation of strong shock waves created by lasers in a plasma. They were carried out with different laser systems. In the first experiment with the Gekko XII laser, we observed the creation and the propagation of two successive shock waves in an ablation plasma in CH and Be. The objective of characterizing the amplification of a transmitted shock by the collision of two counter-propagating shocks has been partially realized. The comparison of the experimental results with the hydrodynamic simulations enabled us to confirm an amplification of the shock by a factor 2 in pressure in the condition of this experiment. The shot with a Be target allowed the development and validation of the diagnostic method of X-ray radiography for shock wave propagation. The second experiment was performed with PHELIX GSI laser (Darmstadt, Germany). The purpose of this experiment was to study the generation of strong shocks. They were applied to study the equation of state of carbon in the WDM state. The condition of pressure and density for the carbon were obtained by deducing the pressure and the velocity of the shock wave chronometric diagnostics employed in this experiment. In this experiment, diamond was at the metallic liquid phase with a pressure

  1. Controllable generation and propagation of ultraslow optical solitons via parameters management in a five-level hyper inverted-Y atomic system

    International Nuclear Information System (INIS)

    Si Liugang; Lue Xinyou; Li Jiahua; Hao Xiangying; Wang Meng

    2009-01-01

    The dynamics of generation and propagation of ultraslow optical solitons in a lifetime-broadened five-level hyper inverted-Y atomic system are investigated. Due to the novel absorption and dispersion properties of this system which provide the necessary ingredients for making the probe field propagate nearly transparent in three regimes, the generation of bright or dark optical solitons can be controlled with parameters management by actively manipulating the dispersion, the nonlinearity and the gain (absorption coefficient) via adjusting the corresponding one-, two- and three-photon detunings and the Rabi frequencies.

  2. Study of the switching rate of gas-discharge devices based on the open discharge with counter-propagating electron beams

    International Nuclear Information System (INIS)

    Bokhan, P. A.; Gugin, P. P.; Lavrukhin, M. A.; Zakrevsky, Dm. E.

    2015-01-01

    The switching rate of gas-discharge devices “kivotrons” based on the open discharge with counter-propagating electron beams has been experimentally studied. Structures with 2-cm 2 overall cathode area were examined. The switching time was found to show a monotonic decrease with increasing the working-gas helium pressure and with increasing the voltage across the discharge gap at breakdown. The minimum switching time was found to be ∼240 ps at 17 kV voltage, and the maximum rate of electric-current rise limited by the discharge-circuit inductance was 3 × 10 12  A/s

  3. Propagation of Energetic Electrons from the Corona into Interplanetary Space and Type III Radio Emission. Planetary Radio Emissions| PLANETARY RADIO EMISSIONS VII 7|

    OpenAIRE

    Vocks, C.; Breitling, F.; Mann, G.

    2011-01-01

    During solar flares a large amount of electrons with energies greater than 20 keV is generated with a production rate of typically 1036 s-1. A part of them is able to propagate along open magnetic field lines through the corona into interplanetary space. During their travel they emit radio radiation which is observed as type III radio bursts in the frequency range from 100 MHz down to 10 kHz by the WAVES radio spectrometer aboard the spacecraft WIND, for instance. From the drift rates of thes...

  4. The nonlinear gyroresonance interaction between energetic electrons and coherent VLF waves propagating at an arbitrary angle with respect to the earth's magnetic field

    Science.gov (United States)

    Bell, T. F.

    1984-01-01

    A theory is presented of the nonlinear gyroresonance interaction that takes place in the magnetosphere between energetic electrons and coherent VLF waves propagating in the whistler mode at an arbitrary angle psi with respect to the earth's magnetic field B-sub-0. Particularly examined is the phase trapping (PT) mechanism believed to be responsible for the generation of VLF emissions. It is concluded that near the magnetic equatorial plane gradients of psi may play a very important part in the PT process for nonducted waves. Predictions of a higher threshold value for PT for nonducted waves generally agree with experimental data concerning VLF emission triggering by nonducted waves.

  5. Observation of molecular level behavior in molecular electronic junction device

    Science.gov (United States)

    Maitani, Masato

    In this dissertation, I utilize AFM based scanning probe measurement and surface enhanced Raman scattering based vibrational spectroscopic analysis to directly characterize topographic, electronic, and chemical properties of molecules confined in the local area of M3 junction to elucidate the molecular level behavior of molecular junction electronic devices. In the introduction, the characterization of molecular electronic devices with different types of metal-molecule-metal (M3) structures based upon self-assembled monolayers (SAMs) is reviewed. A background of the characterization methods I use in this dissertation, conducting probe atomic force microscopy (cp-AFM) and surface enhanced Raman spectroscopy (SERS), is provided in chapter 1. Several attempts are performed to create the ideal top metal contacts on SAMs by metal vapor phase deposition in order to prevent the metal penetration inducing critical defects of the molecular electronic devices. The scanning probe microscopy (SPM), such as cp-AFM, contact mode (c-) AFM and non-contact mode (nc-) AFM, in ultra high vacuum conditions are utilized to study the process of the metal-SAM interface construction in terms of the correlation between the morphological and electrical properties including the metal nucleation and filament generation as a function of the functionalization of long-chain alkane thiolate SAMs on Au. In chapter 2, the nascent condensation process of vapor phase Al deposition on inert and reactive SAMs are studied by SPM. The results of top deposition, penetration, and filament generation of deposited Al are discussed and compared to the results previously observed by spectroscopic measurements. Cp-AFM was shown to provide new insights into Al filament formation which has not been observed by conventional spectroscopic analysis. Additionally, the electronic characteristics of individual Al filaments are measured. Chapter 3 reveals SPM characterization of Au deposition onto --COOH terminated SAMs

  6. SIMULATION OF FORWARD AND BACKWARD WAVES EVOLUTION OF FEW-CYCLE PULSES PROPAGATING IN AN OPTICAL WAVEGUIDE WITH DISPERSION AND CUBIC NONLINEARITY OF ELECTRONIC AND ELECTRONIC-VIBRATION NATURE

    Directory of Open Access Journals (Sweden)

    L. S. Konev

    2015-09-01

    Full Text Available Numerical method for calculation of forward and backward waves of intense few-cycle laser pulses propagating in an optical waveguide with dispersion and cubic nonlinearity of electronic and electronic-vibration nature is described. Simulations made with the implemented algorithm show that accounting for Raman nonlinearity does not lead to qualitative changes in behavior of the backward wave. Speaking about quantitative changes, the increase of efficiency of energy transfer from the forward wave to the backward wave is observed. Presented method can be also used to simulate interaction of counterpropagating pulses.

  7. Propagation of Ion Acoustic Perturbations

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1975-01-01

    Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered.......Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered....

  8. Simultaneous Propagation of Heat Waves Induced by Sawteeth and Electron-Cyclotron Heating Power Modulation in the Rtp Tokamak

    NARCIS (Netherlands)

    Gorini, G.; Mantica, P.; Hogeweij, G. M. D.; De Luca, F.; Jacchia, A.; Konings, J. A.; Cardozo, N. J. L.; Peters, M.

    1993-01-01

    The incremental electron heat diffusivity chi(inc) is determined in Rijnhuizen Tokamak Project plasmas by measurements of simultaneous heat pulses due to (1) the sawtooth instability and (2) modulated electron cyclotron heating. No systematic difference is observed between the two measured chi(inc)

  9. Pixel detector readout electronics with two-level discriminator scheme

    International Nuclear Information System (INIS)

    Pengg, F.

    1998-01-01

    In preparation for a silicon pixel detector with more than 3,000 readout channels per chip for operation at the future large hadron collider (LHC) at CERN the analog front end of the readout electronics has been designed and measured on several test-arrays with 16 by 4 cells. They are implemented in the HP 0.8 microm process but compatible with the design rules of the radiation hard Honeywell 0.8 microm bulk process. Each cell contains bump bonding pad, preamplifier, discriminator and control logic for masking and testing within a layout area of only 50 microm by 140 microm. A new two-level discriminator scheme has been implemented to cope with the problems of time-walk and interpixel cross-coupling. The measured gain of the preamplifier is 900 mV for a minimum ionizing particle (MIP, about 24,000 e - for a 300 microm thick Si-detector) with a return to baseline within 750 ns for a 1 MIP input signal. The full readout chain (without detector) shows an equivalent noise charge to 60e - r.m.s. The time-walk, a function of the separation between the two threshold levels, is measured to be 22 ns at a separation of 1,500 e - , which is adequate for the 40 MHz beam-crossing frequency at the LHC. The interpixel cross-coupling, measured with a 40fF coupling capacitance, is less than 3%. A single cell consumes 35 microW at 3.5 V supply voltage

  10. MANGO PROPAGATION

    OpenAIRE

    ALBERTO CARLOS DE QUEIROZ PINTO; VICTOR GALÁN SAÚCO; SISIR KUMAR MITRA; FRANCISCO RICARDO FERREIRA

    2018-01-01

    ABSTRACT This Chapter has the objectives to search, through the review of the available literature, important informations on the evolution of mango propagation regarding theoretical and practical aspects from cellular base of sexual propagation, nursery structures and organizations, substrate compositions and uses, importance of rootstock and scion selections, also it will be described the preparation and transport of the grafts (stem and bud) as well as the main asexual propagation methods...

  11. Energy level alignment and electron transport through metal/organic contacts. From interfaces to molecular electronics

    Energy Technology Data Exchange (ETDEWEB)

    Abad, Enrique

    2013-07-01

    A new calculational approach to describing metal/organic interfaces. A valuable step towards a better understanding of molecular electronics. Nominated as an outstanding contribution by the Autonomous University of Madrid. In recent years, ever more electronic devices have started to exploit the advantages of organic semiconductors. The work reported in this thesis focuses on analyzing theoretically the energy level alignment of different metal/organic interfaces, necessary to tailor devices with good performance. Traditional methods based on density functional theory (DFT), are not appropriate for analyzing them because they underestimate the organic energy gap and fail to correctly describe the van der Waals forces. Since the size of these systems prohibits the use of more accurate methods, corrections to those DFT drawbacks are desirable. In this work a combination of a standard DFT calculation with the inclusion of the charging energy (U) of the molecule, calculated from first principles, is presented. Regarding the dispersion forces, incorrect long range interaction is substituted by a van der Waals potential. With these corrections, the C60, benzene, pentacene, TTF and TCNQ/Au(111) interfaces are analyzed, both for single molecules and for a monolayer. The results validate the induced density of interface states model.

  12. Rapid localized deactivation of self-assembled monolayers by propagation-controlled laser-induced plasma and its application to self-patterning of electronics and biosensors

    Science.gov (United States)

    Kim, Jongsu; Kwon, Seung-Gab; Back, Seunghyun; Kang, Bongchul

    2018-03-01

    We present a novel laser-induced surface treatment process to rapidly control the spatial wettabilities of various functional solutions with submicron to micron resolutions. Ultrathin hydrophobic self-assembled monolayers (SAMs) that little absorb typical laser lights due to short penetration depth were selectively deactivated by instantaneous interaction with laser-induced metallic plasmas. The spatial region of the deactivated SAM, which corresponds to process resolution, is adjustable by controlling the spatial propagation of the plasma. This method leads to the parallel formation of hydrophilic functional solutions on glass substrates with a minimum resolution on the submicron scale. To show its feasibility in device engineering fields, this method was applied to the cost-effective fabrication of electronics and biosensors. Rapid self-patterning of electronic and biological functional solutions (silver nanoparticle solution and streptavidin protein solution) was successfully realized by selective deactivation of two different SAMs (tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) for electronics and the hetero-hybrid SAM (octadecyltrichlorosilane (OTS)/2-[methoxy(polyethyleneoxy)propyl] trichlorosilane (PEG)) for biosensors). As a result, this method can be exploited for the rapid and low-cost fabrication of various thin film devices such as electronics, biosensors, energy, displays, and photonics.

  13. Band electron spectrum and thermodynamic properties of the pseudospin-electron model with tunneling splitting of levels

    Directory of Open Access Journals (Sweden)

    O.Ya.Farenyuk

    2006-01-01

    Full Text Available The pseudospin-electron model with tunneling splitting of levels is considered. Generalization of dynamic mean-field method for systems with correlated hopping was applied to the investigation of the model. Electron spectra, electron concentrations, average values of pseudospins and grand canonical potential were calculated within the alloy-analogy approximation. Electron spectrum and dependencies of the electron concentrations on chemical potential were obtained. It was shown that in the alloy-analogy approximation, the model possesses the first order phase transition to ferromagnetic state with the change of chemical potential and the second order phase transition with the change of temperature.

  14. Wavefront propagation simulations for a UV/soft x-ray beamline: Electron Spectro-Microscopy beamline at NSLS-II

    Science.gov (United States)

    Canestrari, N.; Bisogni, V.; Walter, A.; Zhu, Y.; Dvorak, J.; Vescovo, E.; Chubar, O.

    2014-09-01

    A "source-to-sample" wavefront propagation analysis of the Electron Spectro-Microscopy (ESM) UV / soft X-ray beamline, which is under construction at the National Synchrotron Light Source II (NSLS-II) in the Brookhaven National Laboratory, has been conducted. All elements of the beamline - insertion device, mirrors, variable-line-spacing gratings and slits - are included in the simulations. Radiation intensity distributions at the sample position are displayed for representative photon energies in the UV range (20 - 100 eV) where diffraction effects are strong. The finite acceptance of the refocusing mirrors is the dominating factor limiting the spatial resolution at the sample (by ~3 μm at 20 eV). Absolute estimates of the radiation flux and energy resolution at the sample are also obtained from the electromagnetic calculations. The analysis of the propagated UV range undulator radiation at different deflection parameter values demonstrates that within the beamline angular acceptance a slightly "red-shifted" radiation provides higher flux at the sample and better energy resolution compared to the on-axis resonant radiation of the fundamental harmonic.

  15. MANGO PROPAGATION

    Directory of Open Access Journals (Sweden)

    ALBERTO CARLOS DE QUEIROZ PINTO

    2018-03-01

    Full Text Available ABSTRACT This Chapter has the objectives to search, through the review of the available literature, important informations on the evolution of mango propagation regarding theoretical and practical aspects from cellular base of sexual propagation, nursery structures and organizations, substrate compositions and uses, importance of rootstock and scion selections, also it will be described the preparation and transport of the grafts (stem and bud as well as the main asexual propagation methods their uses and practices. Finally, pattern and quality of graft mangos and their commercialization aspects will be discussed in this Chapter.

  16. Study of electron-molecule collisions via the finite-element method and R-matrix propagation technique: Model exchange

    International Nuclear Information System (INIS)

    Abdolsalami, F.; Abdolsalami, M.; Gomez, P.

    1994-01-01

    We have applied the finite-element method to electron-molecule collisions. All the calculations are done in the body frame within the fixed-nuclei approximation. A model potential, which is added to the static and polarization potential, has been used to represent the exchange effect. The method is applied to electron-H 2 scattering and the eigenphase sums and the cross sections obtained are in very good agreement with the corresponding results from the linear-algebraic approach. Finite-element calculations of the R matrix in the region where the static and exchange interactions are strong, however, has about one-half to one-fourth of the memory requirement of the linear-algebraic technique

  17. Dependence of the electron Langmuir wave damping on the angle of propagation in weakly ionized neon plasma

    International Nuclear Information System (INIS)

    Zigman, V.J.; Milic, B.S.

    1995-01-01

    The dependence of the attenuation of the longitudinal electron Langmuir waves (ω ∼ ω pe ), in collisional weakly ionized, non-magnetized, uniform and steady-state plasmas placed in external d.c. electric field, on the angle θ between the wave vector and the electron drift rvec u is studied on the ground of the kinetic theory and the linear perturbation technique. The collisionless and collisional contributions to the overall attenuation were evaluated separately, as it was shown previously that in certain instances the elastic e - n encounters (with collision frequency ν en , ν en much-lt ω pe ) may attenuate the Langmuir waves more efficiently than the Landau mechanism. More precisely, it was found that, for any fixed value of E 0 /n n , there exists a critical value of the ratio n n /X above which the collisional attenuation prevails

  18. Study of electron-molecule collision via finite-element method and r-matrix propagation technique: Exact exchange

    International Nuclear Information System (INIS)

    Abdolsalami, F.; Abdolsalami, M.; Perez, L.; Gomez, P.

    1995-01-01

    The authors have applied the finite-element method to electron-molecule collision with the exchange effect implemented rigorously. All the calculations are done in the body-frame within the fixed-nuclei approximation, where the exact treatment of exchange as a nonlocal effect results in a set of coupled integro-differential equations. The method is applied to e-H 2 and e-N 2 scatterings and the cross sections obtained are in very good agreement with the corresponding results the authors have generated from the linear-algebraic approach. This confirms the significant difference observed between their results generated by linear-algebraic method and the previously published e-N 2 cross sections. Their studies show that the finite-element method is clearly superior to the linear-algebraic approach in both memory usage and CPU time especially for large systems such as e-N 2 . The system coefficient matrix obtained from the finite-element method is often sparse and smaller in size by a factor of 12 to 16, compared to the linear-algebraic technique. Moreover, the CPU time required to obtain stable results with the finite-element method is significantly smaller than the linear-algebraic approach for one incident electron energy. The usage of computer resources in the finite-element method can even be reduced much further when (1) scattering calculations involving multiple electron energies are performed in one computer run and (2) exchange, which is a short range effect, is approximated by a sparse matrix. 17 refs., 7 figs., 5 tabs

  19. High-frequency emissions during the propagation of an electron beam in a high-density plasma

    International Nuclear Information System (INIS)

    Lalita and Tripathi, V.K.

    1988-01-01

    A relativistic annular electron beam passing through a high-density plasma excites Langmuir waves via Cerenkov interaction. The Langmuir waves are backscattered off ions via nonlinear ion Landau damping. At moderately high amplitudes these waves are parametrically up-converted by the beam into high-frequency electromagnetic radiation, as observed in some recent experiments. A nonlocal theory of this process is developed in a cylindrical geometry. It is seen that the growth rate of the Langmuir wave scales as one-third power of beam density. The growth rate of parametric instability scales as one-fourth power of beam density and the square root of beam thickness

  20. Treatment of Electronic Energy Level Transition and Ionization Following the Particle-Based Chemistry Model

    Science.gov (United States)

    Liechty, Derek S.; Lewis, Mark

    2010-01-01

    A new method of treating electronic energy level transitions as well as linking ionization to electronic energy levels is proposed following the particle-based chemistry model of Bird. Although the use of electronic energy levels and ionization reactions in DSMC are not new ideas, the current method of selecting what level to transition to, how to reproduce transition rates, and the linking of the electronic energy levels to ionization are, to the author s knowledge, novel concepts. The resulting equilibrium temperatures are shown to remain constant, and the electronic energy level distributions are shown to reproduce the Boltzmann distribution. The electronic energy level transition rates and ionization rates due to electron impacts are shown to reproduce theoretical and measured rates. The rates due to heavy particle impacts, while not as favorable as the electron impact rates, compare favorably to values from the literature. Thus, these new extensions to the particle-based chemistry model of Bird provide an accurate method for predicting electronic energy level transition and ionization rates in gases.

  1. 2.5-dimensional numerical modeling of the formation of a plasma channel due to ion redistribution during the propagation of a finite sequence of relativistic electron bunches through high-density and low-density plasmas

    International Nuclear Information System (INIS)

    Karas, V.I.; Karas, I.V.; Levchenko, V.D.; Sigov, Yu.S.; Fainberg, Ya.B.

    1997-01-01

    Results of numerical simulations of the excitation of wake fields in high- and low-density plasmas are presented. The propagation of relativistic electron bunches in a plasma is described by a closed set of relativistic Vlasov equations for two spatial coordinates and three velocity coordinates for each plasma component and the nonlinear Maxwell equations for self-consistent electromagnetic fields. Numerical modeling shows that, under ordinary experimental conditions (when the length and radius of the bunch are much less than the skin depth), the radius of the bunches propagating in a plasma varies over a wide range. In this case, the dynamics of both the plasma and the bunches is nonlinear. The radial redistribution of the plasma ions in self-consistent fields leads to the formation of a plasma channel. Incorporating this phenomenon is important for studying the propagation of relativistic electron bunches in a plasma

  2. Patterns of electronic cigarette use and level of psychological distress.

    Directory of Open Access Journals (Sweden)

    Su Hyun Park

    Full Text Available Psychological distress has been correlated with higher levels of nicotine dependence. To date, the possible association between individuals' levels of psychological distress and e-cigarette use has not been investigated, despite the dramatic growth of e-cigarette use in the US. We examined this possible association using a nationally representative sample of US adults.A total of 36,697 adults from the 2014 National Health Interview Survey (NHIS were included. The Kessler 6 scale was used to measure psychological distress. Multivariate logistic regression analysis was conducted to assess the association between level of psychological distress and e-cigarette use.Both e-cigarette and cigarette use varied according to level of psychological distress as well as multiple socio-demographic characteristics. In a multivariate model, psychological distress was significantly associated with the following groups: (a exclusive e-cigarette ever-use (aOR = 3.7; 95% CI = 1.6, 8.6, (b current dual use of e-cigarettes and cigarettes (aOR = 4.6; 95% CI = 3.1, 6.7, (c former cigarette use and ever use of e-cigarette (aOR = 3.2; 95% CI = 2.2, 4.8 and (d current use of cigarettes only (aOR = 2.1; 95% CI = 1.7, 2.6.These are the first data to demonstrate that, as is true for cigarettes, e-cigarette use is associated with increased levels of psychological distress. Further large-scale, longitudinal studies are needed to determine the direction of this relationship and to evaluate the long-term positive and negative consequences of such use.

  3. Photovoltaic Shading Testbed for Module-Level Power Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Deline, C.; Meydbray, J.; Donovan, M.; Forrest, J.

    2012-05-01

    This document describes a repeatable test procedure that attempts to simulate shading situations, as would be experienced by typical residential rooftop photovoltaic (PV) systems. This type of shading test is particularly useful to evaluate the impact of different power conversion setups, including microinverters, DC power optimizers and string inverters, on overall system performance. The performance results are weighted based on annual estimates of shade to predict annual performance improvement. A trial run of the test procedure was conducted with a side by side comparison of a string inverter with a microinverter, both operating on identical 8kW solar arrays. Considering three different shade weighting conditions, the microinverter was found to increase production by 3.7% under light shading, 7.8% under moderate shading, and 12.3% under heavy shading, relative to the reference string inverter case. Detail is provided in this document to allow duplication of the test method at different test installations and for different power electronics devices.

  4. Knickpoint formation, rapid propagation, and landscape response following coastal cliff retreat at last-interglacial sea-level highstand: Kaua'i, Hawai'i

    Science.gov (United States)

    Lamb, Michael; Mackey, Ben; Scheingross, Joel; Farley, Ken

    2013-04-01

    The propagation of knickpoints through a landscape is recognized as a highly efficient mechanism of channel incision, and exerts a first-order control in communicating changes in base level throughout a landscape. However, few settings allow reconstruction of the long-term rate of knickpoint retreat. Here, we use cosmogenic 3He exposure dating of olivine within basalt to document the retreat rate of a waterfall in Ka'ula'ula Valley, a small catchment on the Na Pali coast of Kaua'i, Hawai'i. We constrained the exposure age of 18 features (in-channel boulders, stable boulders on terraces, and in-channel bedrock) along the length of the channel that allow us to discriminate between models of knickpoint propagation. Cosmogenic exposure ages are oldest near the coast (120 ka) and systematically decrease with upstream distance towards the waterfall (waterfall has migrated 4 km up valley over the past 120 ka at an average rate of 33 mm/yr. Steady-state vertical erosion appears to dominate upstream of the waterfall, where the channel has incised ~100 m into the original surface of the shield volcano. Our results indicate the lateral rate of knickpoint retreat exceeds rates of vertical channel incision by three orders of magnitude, and that knickpoints may be the primary driver of relief generation in Hawaiian catchments. Submarine landslides have been proposed as the cause of knickpoints in Kaua'i streams; however, the bathymetry off the northwest Kaua'i coast lacks evidence for large submarine flank collapse. Alternatively, we propose substantial cliff erosion during the last interglacial sea-level highstand generated a waterfall at the coast, which has subsequently propagated inland. Superimposing Kaua'i's subsidence history and Pleistocene sea level fluctuations indicate that the only time waves could have eroded cliffs at Ka'ula'ula Valley's entrance over the past 1.5 Ma was during the last interglacial, ~130-120 ka. Knickpoint generation during sea level high stands

  5. Levels of saliva cotinine in electronic cigarette users.

    Science.gov (United States)

    Etter, Jean-François

    2014-05-01

    To assess saliva cotinine levels in experienced users of e-cigarettes ('vapers'). An internet survey in 2011 and 2012, with collection of saliva vials by mail. Participants were 71 users of e-cigarettes enrolled mainly on websites and online forums dedicated to e-cigarettes. Use of e-cigarettes, tobacco and nicotine medications. Collection of saliva by mail and analysis of cotinine by liquid chromatography-mass spectrometry. Most participants (89%) were former smokers, most (92%) were using e-cigarettes daily, had been using e-cigarettes for 12 months on average and puffed a median of 150 times per day on their e-cigarettes [mean = 220 puffs/day, 95% confidence interval (CI) = 169-271]. The median concentration of nicotine in refill liquids was 16 mg/ml (mean = 16.4, 95% CI = 14.5-18.3). In the 62 e-cigarette users who, in the past 5 days, had not used any tobacco or nicotine medications, the median cotinine level was 353 ng/ml (mean = 374, 95% CI = 318-429), the correlation between cotinine and nicotine concentration in e-liquids was r = 0.33 (P = 0.013), and the correlation between cotinine and the number of cigarettes smoked per day before quitting smoking was r = 0.48 (P Addiction.

  6. Two-electron excitation to Rydberg levels in fast I6+ on hydrogen collisions

    International Nuclear Information System (INIS)

    Liao, C.; Hagmann, S.; Zouros, T.J.M.; Montenegro, E.C.; Toth, G.; Richard, P.; Grabbe, S.; Bhalla, C.P.

    1995-01-01

    The emission of electrons in the forward direction in collisions of 0.3 MeV/u I 6+ with H 2 has been studied, and strong autoionization peaks are observed on the shoulder of the cusp peak. The energies of these autoionization lines in the projectile rest frame are determined by high-resolution electron spectroscopy. Using the electron projectile final charge state coincidence technique, we probe different collision mechanisms, which create continuum electrons that are slow in the projectile rest frame. We conclude that the observed autoionization lines are due to two electron excitation to projectile Rydberg levels. (orig.)

  7. PERCEPTION LEVEL EVALUATION OF RADIO ELECTRONIC MEANS TO A PULSE OF ELECTROMAGNETIC RADIATION

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The method for evaluating the perception level of electronic means to pulsed electromagnetic radiation is consid- ered in this article. The electromagnetic wave penetration mechanism towards the elements of electronic systems and the impact on them are determined by the intensity of the radiation field on the elements of electronic systems. The impact of electromagnetic radiation pulses to the electronic systems refers to physical and analytical parameters of the relationship between exposure to pulses of electromagnetic radiation and the sample parameters of electronic systems. A physical and mathematical model of evaluating the perception level of electronic means to pulsed electromagnetic radiation is given. The developed model was based on the physics of electronics means failure which represents the description of electro- magnetic, electric and thermal processes that lead to the degradation of the original structure of the apparatus elements. The conditions that lead to the total equation electronic systems functional destruction when exposed to electromagnetic radia- tion pulses are described. The internal characteristics of the component elements that respond to the damaging effects are considered. The ratio for the power failure is determined. A thermal breakdown temperature versus pulse duration of expo- sure at various power levels is obtained. The way of evaluation the reliability of electronic systems when exposed to pulses of electromagnetic radiation as a destructive factor is obtained.

  8. Employability Competencies for Entry Level Occupations in Electronics. Part One: Basic Theory.

    Science.gov (United States)

    Werner, Claire

    This syllabus, which is the first of a two-volume set describing the basic competencies needed by entry-level workers in the field of electronics, deals with the basic theories of electricity and electronics. Competencies are organized according to the following skills areas: the meaning of electricity, how electricity works, resistors, Ohm's law,…

  9. Dust Propagation and Radiation In the Presence of a Low-level Jet in Central China on March 17, 2010

    Science.gov (United States)

    McDowell, B. K.; Chen, S. H.

    2014-12-01

    Suspended dust in the air can directly change the energy budget in the atmosphere and at the surface through scattering and absorption of radiation. Thus, dust can potentially modify the development of weather systems. To explore the dust-radiation effects on weather systems, a dust model was developed based on the Weather Research and Forecasting (WRF) model. The calculations of dust processes in the WRF dust model include emission, advection, boundary layer mixing, cumulus mixing, dust-radiation interaction, wet scavenging, and sedimentation. Due to a high vertical spatial resolution near the surface a time splitting method was applied to the calculation of dust sedimentation to relax the numerical time step. The "Hexi Corridor" is the historical name given to a string of oases along the northern slope of the Tibetan Plateau that formed a relatively easy transportation route between eastern China and central Asia. As trade developed over the centuries, this route became known as the Silk Road. This corridor also marks the transition from the relatively flat Gobi desert area in northern China to the elevated mountains of the Tibetan Plateau. These mountains present a southern barrier to the paths of dust storms that develop during spring outbreaks of the Mongolian Cyclone. In March of 2010, a series of dust storms developed in the Gobi Desert north of the Hexi Corridor that transported massive amounts of dust eastward to central and northeastern China, Korea and Japan. On March 17 during this event, a low-level jet developed along the northern perimeter of the Plateau, in alignment with upper level winds and the Hexi Corridor. Over the course of the day, a well-defined short-duration dust plume was emitted in the southern Gobi desert area and was transported over 1300 km in a southeast direction, over the Loess Plateau and into the Gansu Province. In this study, the interactions of synoptic conditions with regional topography that led to the development of the low-level

  10. Single-molecule electron tunnelling through multiple redox levels with environmental relaxation

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2004-01-01

    represent the substrate and tip in electrochemical in situ scanning tunnelling microscopy. An equivalent three-electrode configuration represents a molecular single-electron transistor in which the enclosing electrodes constitute source and drain, and the reference electrode the gate. Current-bias voltage...... relations at fixed electrochemical overpotential or gate voltage, and current-overpotential or current-gate voltage relations at fixed bias voltage are equivalent in the two systems. Due to the activation-less nature of the processes, electron flow between the electrodes through the molecular redox levels...... level(s) subsequent to electron transfer. Several physical mechanisms can be distinguished and distinctive current-overpotential/gate voltage or current-bias voltage relations obtained. These reflect electronic level separation, environmental nuclear reorganisation, and coherent or incoherent multi...

  11. Electron-impact excitation out of the metastable levels of Krypton

    International Nuclear Information System (INIS)

    Jung, R.O.; Stone, Tom E.; Boffard, John B.; Anderson, L.W.; Lin, Chun C.

    2005-01-01

    We have measured the electron-impact excitation cross sections out of the two metastable levels of Kr into the ten levels of the 4p 5 5p configuration. For a common 4p 5 5p final level, the peak excitation cross sections out of the two individual 4p 5 5s metastable levels are found to differ by 1 to 2 orders of magnitude. This is explained by the special features of the electronic structure of the two configurations involved. The peak cross sections are 10 to 1600 times larger than the corresponding peak cross sections out of the ground state

  12. Equation level matching: An extension of the method of matched asymptotic expansion for problems of wave propagation

    Science.gov (United States)

    Faria, Luiz; Rosales, Rodolfo

    2017-11-01

    We introduce an alternative to the method of matched asymptotic expansions. In the ``traditional'' implementation, approximate solutions, valid in different (but overlapping) regions are matched by using ``intermediate'' variables. Here we propose to match at the level of the equations involved, via a ``uniform expansion'' whose equations enfold those of the approximations to be matched. This has the advantage that one does not need to explicitly solve the asymptotic equations to do the matching, which can be quite impossible for some problems. In addition, it allows matching to proceed in certain wave situations where the traditional approach fails because the time behaviors differ (e.g., one of the expansions does not include dissipation). On the other hand, this approach does not provide the fairly explicit approximations resulting from standard matching. In fact, this is not even its aim, which to produce the ``simplest'' set of equations that capture the behavior. Ruben Rosales work was partially supported by NSF Grants DMS-1614043 and DMS-1719637.

  13. Beam propagation

    International Nuclear Information System (INIS)

    Hermansson, B.R.

    1989-01-01

    The main part of this thesis consists of 15 published papers, in which the numerical Beam Propagating Method (BPM) is investigated, verified and used in a number of applications. In the introduction a derivation of the nonlinear Schroedinger equation is presented to connect the beginning of the soliton papers with Maxwell's equations including a nonlinear polarization. This thesis focuses on the wide use of the BPM for numerical simulations of propagating light and particle beams through different types of structures such as waveguides, fibers, tapers, Y-junctions, laser arrays and crystalline solids. We verify the BPM in the above listed problems against other numerical methods for example the Finite-element Method, perturbation methods and Runge-Kutta integration. Further, the BPM is shown to be a simple and effective way to numerically set up the Green's function in matrix form for periodic structures. The Green's function matrix can then be diagonalized with matrix methods yielding the eigensolutions of the structure. The BPM inherent transverse periodicity can be untied, if desired, by for example including an absorptive refractive index at the computational window edges. The interaction of two first-order soliton pulses is strongly dependent on the phase relationship between the individual solitons. When optical phase shift keying is used in coherent one-carrier wavelength communication, the fiber attenuation will suppress or delay the nonlinear instability. (orig.)

  14. Molecular design of new P3HT derivatives: Adjusting electronic energy levels for blends with PCBM

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Eliezer Fernando [UNESP – Univ Estadual Paulista, POSMAT – Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Bauru, SP (Brazil); Lavarda, Francisco Carlos, E-mail: lavarda@fc.unesp.br [UNESP – Univ Estadual Paulista, POSMAT – Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Bauru, SP (Brazil); Faculdade de Ciências, UNESP – Univ Estadual Paulista, Departamento de Física, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, 17033-360 Bauru, SP (Brazil)

    2014-12-15

    An intensive search is underway for new materials to make more efficient organic solar cells through improvements in thin film morphology, transport properties, and adjustments to the energy of frontier electronic levels. The use of chemical modifications capable of modifying the electronic properties of materials already known is an interesting approach, as it can, in principle, provide a more adequate adjustment of the frontier electronic levels while preserving properties such as solubility. Based on this idea, we performed a theoretical study of poly(3-hexylthiophene) (P3HT) and 13 new derivatives obtained by substitution with electron acceptor and donor groups, in order to understand how the energy levels of the frontier orbitals are modified. The results show that it is possible to deduce the modification of the electronic levels in accordance with the substituent's acceptor/donor character. We also evaluated how the substituents influence the open circuit voltage and the exciton binding energy. - Highlights: • Prediction of P3HT derivatives properties for bulk-heterojunction solar cells. • Correlating substituent properties with electronic levels of P3HT derivatives. • Fluorinated P3HT improves open circuit voltage and stability.

  15. Noise Levels in Two Emergency Departments Before and After the Introduction of Electronic Whiteboards

    DEFF Research Database (Denmark)

    Hertzum, Morten

    2013-01-01

    . The maximum equivalent continuous noise levels across 1 second were above 80 dB(A) at all four coordination centres. At two of the centres above 80 dB(A) noises also occurred at night. After the introduction of electronic whiteboards the noise level was lowered at one ED but unchanged at the other ED...

  16. Spectroscopic analysis of electron trapping levels in pentacene field-effect transistors

    International Nuclear Information System (INIS)

    Bum Park, Chang

    2014-01-01

    Electron trapping phenomena have been investigated with respect to the energy levels of localized trap states and bias-induced device instability effects in pentacene field-effect transistors. The mechanism of the photoinduced threshold voltage shift (ΔV T ) is presented by providing a ΔV T model governed by the electron trapping. The trap-and-release behaviour functionalized by photo-irradiation also shows that the trap state for electrons is associated with the energy levels in different positions in the forbidden gap of pentacene. Spectroscopic analysis identifies two kinds of electron trap states distributed above and below the energy of 2.5 eV in the band gap of the pentacene crystal. The study of photocurrent spectra shows the specific trap levels of electrons in energy space that play a substantial role in causing device instability. The shallow and deep trapping states are distributed at two centroidal energy levels of ∼1.8 and ∼2.67 eV in the pentacene band gap. Moreover, we present a systematic energy profile of electron trap states in the pentacene crystal for the first time. (paper)

  17. Error propagation in spatial modeling of public health data: a simulation approach using pediatric blood lead level data for Syracuse, New York.

    Science.gov (United States)

    Lee, Monghyeon; Chun, Yongwan; Griffith, Daniel A

    2018-04-01

    Lead poisoning produces serious health problems, which are worse when a victim is younger. The US government and society have tried to prevent lead poisoning, especially since the 1970s; however, lead exposure remains prevalent. Lead poisoning analyses frequently use georeferenced blood lead level data. Like other types of data, these spatial data may contain uncertainties, such as location and attribute measurement errors, which can propagate to analysis results. For this paper, simulation experiments are employed to investigate how selected uncertainties impact regression analyses of blood lead level data in Syracuse, New York. In these simulations, location error and attribute measurement error, as well as a combination of these two errors, are embedded into the original data, and then these data are aggregated into census block group and census tract polygons. These aggregated data are analyzed with regression techniques, and comparisons are reported between the regression coefficients and their standard errors for the error added simulation results and the original results. To account for spatial autocorrelation, the eigenvector spatial filtering method and spatial autoregressive specifications are utilized with linear and generalized linear models. Our findings confirm that location error has more of an impact on the differences than does attribute measurement error, and show that the combined error leads to the greatest deviations. Location error simulation results show that smaller administrative units experience more of a location error impact, and, interestingly, coefficients and standard errors deviate more from their true values for a variable with a low level of spatial autocorrelation. These results imply that uncertainty, especially location error, has a considerable impact on the reliability of spatial analysis results for public health data, and that the level of spatial autocorrelation in a variable also has an impact on modeling results.

  18. Electron excitation cross sections for some Ar I 5d (J = 2) levels

    International Nuclear Information System (INIS)

    Blanco, F.; Sanchez, J.A.; Campos, J.

    1992-01-01

    Absolute excitation cross sections by electron impact for some 5d levels with J = 2 of Ar I have been measured by the optical method. Excitation functions for electron energies in the range from the excitation threshold to 1000 eV are also reported. A delayed coincidence analysis of the de-excitation at 100 eV electron energy allowed for the subtraction of radiative cascades. The resulting excitation cross sections are between 7.3 and 12x10 -20 cm 2 . (author)

  19. The levels of the first excited configuration of one-electron ions in intensive alternating field

    International Nuclear Information System (INIS)

    Klimchitskaya, G.L.

    1984-01-01

    The relativistic generalization of the quasi-energy method is applied for the calculation of the influence of spatjally-homogeneous electric field with the periodic time dependence on the energy levels of the first excited configuration of one-electron multiply charged ions. The dependence is found of the corresponding quasi-energy levels on the amplitude and frequency of intensive external field which wholly mixes the levels of fine structure

  20. Electrons and photons at High Level Trigger in CMS for Run II

    CERN Document Server

    Bin Anuar, Afiq Aizuddin

    2015-01-01

    The CMS experiment has been designed with a 2-level trigger system. The first level is implemented using custom-designed electronics. The second level is the so-called High Level Trigger (HLT), a streamlined version of the CMS offline reconstruction software running on a computer farm. For Run II of the Large Hadron Collider, the increase in center-of-mass energy and luminosity will raise the event rate to a level challenging for the HLT algorithms. New approaches have been studied to keep the HLT output rate manageable while maintaining thresholds low enough to cover physics analyses. The strategy mainly relies on porting online the ingredients that have been successfully applied in the offline reconstruction, thus allowing to move HLT selection closer to offline cuts. Improvements in HLT electron and photon definitions will be presented, focusing in particular on updated clustering algorithm and the energy calibration procedure, new Particle-Flow-based isolation approach and pileup mitigation techniques, a...

  1. Direct Identification of Atomic-Like Electronic Levels in InAs Nano crystal Quantum Dots

    International Nuclear Information System (INIS)

    Millo, O.; Katz, D.

    1999-01-01

    The size dependent level structure of InAs nano crystals in the range 2-7 nm in diameter is investigated using both tunneling and optical spectroscopies. The tunneling measurements are performed using a cryogenic scanning tunneling microscope on individual nano crystals that, are attached to a gold substrate via dithiol molecules. The tunneling I-V characteristics manifest an interplay between single electron charging and quantum size effects. We are able to directly identify quantum confined states of isolated InAs nano crystals having s and p symmetries. These states are observed in the I-V curves as two and six-fold single electron charging multiplets. Excellent agreement is found between the strongly allowed optical transitions [1] and the spacing of levels detected in the tunneling experiment. This correlation provides new information on the quantum-dot level structure, from which we conclude that the top-most valence band state has both s and p characteristics. The interplay between level structure singles electron charging of the nano crystals obeys an atomic-like Aufbau sequential electron level occupation

  2. Tin-vacancy acceptor levels in electron-irradiated n-type silicon

    DEFF Research Database (Denmark)

    Larsen, A. Nylandsted; Goubet, J. J.; Mejlholm, P.

    2000-01-01

    Si crystals (n-type, fz) with doping levels between 1.5x10(14) and 2x10(16)cm(-3) containing in addition similar to 10(18) Sn/cm(3) were irradiated with 2-MeV electrons to different doses and subsequently studied by deep level transient spectroscopy, Mossbauer spectroscopy, and positron...... annihilation. Two tin-vacancy (Sn-V) levels at E-c - 0.214 eV and E-c - 0.501 eV have been identified (E-c denotes the conduction band edge). Based on investigations of the temperature dependence of the electron-capture cross sections, the electric-field dependence of the electron emissivity, the anneal...... temperature, and the defect-introduction rate, it is concluded that these levels are the double and single acceptor levels, respectively, of the Sn-V pair. These conclusions are in agreement with electronic structure calculations carried out using a local spin-density functional theory, incorporating...

  3. Dynamic correlation of photo-excited electrons: Anomalous levels induced by light–matter coupling

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiankai [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Huai, Ping, E-mail: huaiping@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Song, Bo, E-mail: bosong@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China)

    2014-04-01

    Nonlinear light–matter coupling plays an important role in many aspects of modern physics, such as spectroscopy, photo-induced phase transition, light-based devices, light-harvesting systems, light-directed reactions and bio-detection. However, excited states of electrons are still unclear for nano-structures and molecules in a light field. Our studies unexpectedly present that light can induce anomalous levels in the electronic structure of a donor–acceptor nanostructure with the help of the photo-excited electrons transferring dynamically between the donor and the acceptor. Furthermore, the physics underlying is revealed to be the photo-induced dynamical spin–flip correlation among electrons. These anomalous levels can significantly enhance the electron current through the nanostructure. These findings are expected to contribute greatly to the understanding of the photo-excited electrons with dynamic correlations, which provides a push to the development and application of techniques based on photosensitive molecules and nanostructures, such as light-triggered molecular devices, spectroscopic analysis, bio-molecule detection, and systems for solar energy conversion.

  4. Research Update: Spatially resolved mapping of electronic structure on atomic level by multivariate statistical analysis

    International Nuclear Information System (INIS)

    Belianinov, Alex; Ganesh, Panchapakesan; Lin, Wenzhi; Jesse, Stephen; Pan, Minghu; Kalinin, Sergei V.; Sales, Brian C.; Sefat, Athena S.

    2014-01-01

    Atomic level spatial variability of electronic structure in Fe-based superconductor FeTe 0.55 Se 0.45 (T c = 15 K) is explored using current-imaging tunneling-spectroscopy. Multivariate statistical analysis of the data differentiates regions of dissimilar electronic behavior that can be identified with the segregation of chalcogen atoms, as well as boundaries between terminations and near neighbor interactions. Subsequent clustering analysis allows identification of the spatial localization of these dissimilar regions. Similar statistical analysis of modeled calculated density of states of chemically inhomogeneous FeTe 1−x Se x structures further confirms that the two types of chalcogens, i.e., Te and Se, can be identified by their electronic signature and differentiated by their local chemical environment. This approach allows detailed chemical discrimination of the scanning tunneling microscopy data including separation of atomic identities, proximity, and local configuration effects and can be universally applicable to chemically and electronically inhomogeneous surfaces

  5. Radiation levels at CERN's injectors and their impact on electronic equipment

    CERN Document Server

    AUTHOR|(SzGeCERN)649218; Brugger, Markus

    2013-01-01

    Electronic devices operating in hostile radiation environments, such as those found close to high-energy particle accelerators, can suffer from different types of radiation induced failures. At CERN, the mixed particle and energy radiation fields present at the Large Hadron Collider (LHC) and its injector chain can give rise to both stochastic and cumulative effects causing radiation induced failures of exposed electronics and materials, thus directly impacting components and system lifetimes, as well as maintenance requirements. With its original focus on the LHC, the Radiation to Electronics (R2E) project has been successfully implementing mitigation actions in order to avoid accelerator downtime due to radiation induced failures on active electronics. In a next step, the emphasis is put on CERN's injector chain, collecting the respective available information about radiation levels, the definition of additional monitoring requirements and a critical analysis of present and future equipment installations. T...

  6. Polybrominated diphenyl ethers--plasma levels and thyroid status of workers at an electronic recycling facility.

    Science.gov (United States)

    Julander, A; Karlsson, M; Hagström, K; Ohlson, C G; Engwall, M; Bryngelsson, I-L; Westberg, H; van Bavel, B

    2005-08-01

    Personnel working with electronic dismantling are exposed to polybrominated diphenyl ethers (PBDEs), which in animal studies have been shown to alter thyroid homeostasis. The aim of this longitudinal study was to measure plasma level of PBDEs in workers at an electronic recycling facility and to relate these to the workers' thyroid status. PBDEs and three thyroid hormones: triiodothyronine (T(3)), thyroxin (T(4)) and thyroid stimulating hormone (TSH) were repeatedly analysed in plasma from 11 workers during a period of 1.5 years. Plasma levels of PBDEs at start of employment were plasma levels of PBDEs fluctuated during the study period. Due to small changes in thyroid hormone levels it was concluded that no relevant changes were present in relation to PBDE exposure within the workers participating in this study.

  7. Correlation electron cyclotron emission diagnostic and improved calculation of turbulent temperature fluctuation levels on ASDEX Upgrade

    Science.gov (United States)

    Creely, A. J.; Freethy, S. J.; Burke, W. M.; Conway, G. D.; Leccacorvi, R.; Parkin, W. C.; Terry, D. R.; White, A. E.

    2018-05-01

    A newly upgraded correlation electron cyclotron emission (CECE) diagnostic has been installed on the ASDEX Upgrade tokamak and has begun to perform experimental measurements of electron temperature fluctuations. CECE diagnostics measure small amplitude electron temperature fluctuations by correlating closely spaced heterodyne radiometer channels. This upgrade expanded the system from six channels to thirty, allowing simultaneous measurement of fluctuation level radial profiles without repeat discharges, as well as opening up the possibility of measuring radial turbulent correlation lengths. Newly refined statistical techniques have been developed in order to accurately analyze the fluctuation data collected from the CECE system. This paper presents the hardware upgrades for this system and the analysis techniques used to interpret the raw data, as well as measurements of fluctuation spectra and fluctuation level radial profiles.

  8. Approaching an organic semimetal: Electron pockets at the Fermi level for a p-benzoquinonemonoimine zwitterion

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Luis G.; Velev, Julian [Department of Physics and Electronics, University of Puerto Rico, Humacao (United States); Institute for Functional Nanomaterials, University of Puerto Rico, San Juan (United States); Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, NE (United States); Zhang, Zhengzheng [Department of Physics, University of Puerto Rico, Rio Piedras, San Juan (United States); Alvira, Jose; Vega, Omar; Diaz, Gerson [Department of Physics and Electronics, University of Puerto Rico, Humacao (United States); Routaboul, Lucie; Braunstein, Pierre [Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Universite de Strasbourg (France); Doudin, Bernard [Institut de Physique, Applique de Physique et Chimie des Materiaux de Strasbourg, Universite Louis Pasteur Strasbourg (France); Losovyj, Yaroslav B. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan (United States); J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State Univ., Baton Rouge, LA (United States); Dowben, Peter A. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan (United States)

    2012-08-15

    There is compelling evidence of electron pockets, at the Fermi level, in the band structure for an organic zwitterion molecule of the p-benzoquinonemonoimine type. The electronic structure of the zwitterion molecular film has a definite, although small, density of states evident at the Fermi level as well as a nonzero inner potential and thus is very different from a true insulator. In spite of a small Brillouin zone, significant band width is observed in the intermolecular band dispersion. The results demonstrate that Bloch's theorem applies to the wave vector dependence of the electronic band structure formed from the molecular orbitals of adjacent molecules in a molecular thin film of a p-benzoquinonemonoimine type zwitterion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. The front-end (Level-0) electronics interface module for the LHCb RICH detectors

    Energy Technology Data Exchange (ETDEWEB)

    Adinolfi, M. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Bibby, J.H. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Brisbane, S. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Gibson, V. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Harnew, N. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Jones, M. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Libby, J. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom)]. E-mail: j.libby1@physics.ox.ac.uk; Powell, A. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Newby, C. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Rotolo, N. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Smale, N. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Somerville, L.; Sullivan, P.; Topp-Jorgensen, S. [Sub-department of Particle Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Wotton, S. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Wyllie, K. [CERN, CH-1211, Geneva 23 (Switzerland)

    2007-03-11

    The front-end (Level-0) electronics interface module for the LHCb Ring Imaging Cherenkov (RICH) detectors is described. This module integrates the novel hybrid photon detectors (HPDs), which instrument the RICH detectors, to the LHCb trigger, data acquisition (DAQ) and control systems. The system operates at 40 MHz with a first-level trigger rate of 1 MHz. The module design is presented and results are given for both laboratory and beam tests.

  10. The front-end (Level-0) electronics interface module for the LHCb RICH detectors

    International Nuclear Information System (INIS)

    Adinolfi, M.; Bibby, J.H.; Brisbane, S.; Gibson, V.; Harnew, N.; Jones, M.; Libby, J.; Powell, A.; Newby, C.; Rotolo, N.; Smale, N.; Somerville, L.; Sullivan, P.; Topp-Jorgensen, S.; Wotton, S.; Wyllie, K.

    2007-01-01

    The front-end (Level-0) electronics interface module for the LHCb Ring Imaging Cherenkov (RICH) detectors is described. This module integrates the novel hybrid photon detectors (HPDs), which instrument the RICH detectors, to the LHCb trigger, data acquisition (DAQ) and control systems. The system operates at 40 MHz with a first-level trigger rate of 1 MHz. The module design is presented and results are given for both laboratory and beam tests

  11. Photovoltaic Shading Testbed for Module-Level Power Electronics: 2016 Performance Data Update

    Energy Technology Data Exchange (ETDEWEB)

    Deline, Chris [National Renewable Energy Lab. (NREL), Golden, CO (United States); Meydbray, Jenya [PV Evolution Labs (PVEL), Davis, CA (United States); Donovan, Matt [PV Evolution Labs (PVEL), Davis, CA (United States)

    2016-09-01

    The 2012 NREL report 'Photovoltaic Shading Testbed for Module-Level Power Electronics' provides a standard methodology for estimating the performance benefit of distributed power electronics under partial shading conditions. Since the release of the report, experiments have been conducted for a number of products and for different system configurations. Drawing from these experiences, updates to the test and analysis methods are recommended. Proposed changes in data processing have the benefit of reducing the sensitivity to measurement errors and weather variability, as well as bringing the updated performance score in line with measured and simulated values of the shade recovery benefit of distributed PV power electronics. Also, due to the emergence of new technologies including sub-module embedded power electronics, the shading method has been extended to include power electronics that operate at a finer granularity than the module level. An update to the method is proposed to account for these emerging technologies that respond to shading differently than module-level devices. The partial shading test remains a repeatable test procedure that attempts to simulate shading situations as would be experienced by typical residential or commercial rooftop photovoltaic (PV) systems. Performance data for multiple products tested using this method are discussed, based on equipment from Enphase, Solar Edge, Maxim Integrated and SMA. In general, the annual recovery of shading losses from the module-level electronics evaluated is 25-35%, with the major difference between different trials being related to the number of parallel strings in the test installation rather than differences between the equipment tested. Appendix D data has been added in this update.

  12. An X-Ray of the Level of Electronic Purse Usage in Nigeria | Ogbuji ...

    African Journals Online (AJOL)

    This study sets out to examine the level of e-purse usage in Nigeria. Despite the invasion of e-purse as electronic banking channels that has the potential of disempowering the cash systems of exchange and granting firms competitive edge, it is interesting to note that the rate of cash usage still dominates in the Nigeria ...

  13. Building America Case Study: Photovoltaic Systems with Module-Level Power Electronics

    Energy Technology Data Exchange (ETDEWEB)

    2015-09-01

    Direct current (DC) power optimizers and microinverters (together known as module-level power electronics, or MLPE) are one of the fastest growing market segments in the solar industry. According to GTM Research in The Global PV Inverter Landscape 2015, over 55% of all residential photovoltaic (PV) installations in the United States used some form of MLPE in 2014.

  14. Excitation and deexcitation of N2 molecular levels. Induced fluorescence by electrons and laser

    International Nuclear Information System (INIS)

    Perez Fernandez-Mayoralas, A.

    1989-01-01

    The electron impact excitation followed by fluorescence induced by N 2 -laser absorption was used to study the lifetime of the lowest vibrational level of the B 3 π g electronic state of N 2 . The experimental result of this work is 13 + 1 μs. To measure the lifetime of B 3 π g (v=2,3,5,6,7,8) levels the delayed coincidence method by electron impact was use. The lifetime values were compared with recent experimental and theoretical results. The relative intensi-ties of 3 π g --- A 3 Σ Ω + system bands, in the range (6540-10500 A o ) was measured using a hollow cathode lamp as spectral source. The relative transition moments and its dependence versus the r-centroid was obtained. Total cross sections for electron scattering by N molecules in the range 600 - 5000 eV have been obtained from measurements of the attenuation of a linear electron beam. The results have been compared with available experimental cross sections and with theoretical calculations based on the first Born approximation. (Author)

  15. Direct observation of children's preferences and activity levels during interactive and online electronic games.

    Science.gov (United States)

    Sit, Cindy H P; Lam, Jessica W K; McKenzie, Thomas L

    2010-07-01

    Interactive electronic games have recently been popularized and are believed to help promote children's physical activity (PA). The purpose of the study was to examine preferences and PA levels during interactive and online electronic games among overweight and nonoverweight boys and girls. Using a modification of the SOFIT, we systematically observed 70 Hong Kong Chinese children (35 boys, 35 girls; 50 nonoverweight, 20 overweight), age 9 to 12 years, during 2 60-minute recreation sessions and recorded their game mode choices and PA levels. During Session One children could play either an interactive or an online electronic bowling game and during Session Two they could play an interactive or an online electronic running game. Children chose to play the games during 94% of session time and split this time between interactive (52%) and online (48%) versions. They engaged in significantly more moderate-to-vigorous physical activity (MVPA) during interactive games than their online electronic versions (70% vs. 2% of game time). Boys and nonoverweight children expended relatively more energy during the interactive games than girls and overweight children, respectively. New-generation interactive games can facilitate physical activity in children, and given the opportunity children may select them over sedentary versions.

  16. Bolt beam propagation analysis

    Science.gov (United States)

    Shokair, I. R.

    BOLT (Beam on Laser Technology) is a rocket experiment to demonstrate electron beam propagation on a laser ionized plasma channel across the geomagnetic field in the ion focused regime (IFR). The beam parameters for BOLT are: beam current I(sub b) = 100 Amps, beam energy of 1--1.5 MeV (gamma =3-4), and a Gaussian beam and channel of radii r(sub b) = r(sub c) = 1.5 cm. The N+1 ionization scheme is used to ionize atomic oxygen in the upper atmosphere. This scheme utilizes 130 nm light plus three IR lasers to excite and then ionize atomic oxygen. The limiting factor for the channel strength is the energy of the 130 nm laser, which is assumed to be 1.6 mJ for BOLT. At a fixed laser energy and altitude (fixing the density of atomic oxygen), the range can be varied by adjusting the laser tuning, resulting in a neutralization fraction axial profile of the form: f(z) = f(sub 0) e(exp minus z)/R, where R is the range. In this paper we consider the propagation of the BOLT beam and calculate the range of the electron beam taking into account the fact that the erosion rates (magnetic and inductive) vary with beam length as the beam and channel dynamically respond to sausage and hose instabilities.

  17. Studies on deep electronic levels in silicon and aluminium gallium arsenide alloys

    International Nuclear Information System (INIS)

    Pettersson, H.

    1993-01-01

    This thesis reports on investigations of the electrical and optical properties of deep impurity centers, related to the transition metals (TMs) Ti, Mo, W, V and Ni, in silicon. Emission rates, capture cross sections and photoionization cross sections for these impurities were determined by means of various Junction Space Charge Techniques (JSCTs), such as Deep Level Transient Spectroscopy (DLTS), dark capacitance transient and photo capacitance transient techniques. Changes in Gibbs free energy as a function of temperature were calculated for all levels. From this temperature dependence, the changes in enthalpy and entropy involved in the electron and hole transitions were deduced. The influence of high electric fields on the electronic levels in chalcogen-doped silicon were investigated using the dark capacitance transient technique. The enhancement of the electron emission from the deep centers indicated a more complex field enhancement model than the expected Poole-Frenkel effect for coulombic potentials. The possibility to determine charge states of defects using the Poole-Frenkel effect, as often suggested, is therefore questioned. The observation of a persistent decrease of the dark conductivity due to illumination in simplified AlGaAs/GaAs high Electron Mobility Transistors (HEMTs) over the temperature range 170K< T<300K is reported. A model for this peculiar behavior, based on the recombination of electrons in the two-dimensional electron gas (2DEG) located at the AlGaAs/GaAs interface with holes generated by a two-step excitation process via the deep EL2 center in the GaAs epilayer, is put forward

  18. Electron transfer and redox metalloenzyme catalysis at the single-molecule level

    DEFF Research Database (Denmark)

    Hansen, Allan Glargaard; Zhang, Jingdong; Christensen, Hans Erik Mølager

    2004-01-01

    transfer (ET). Image interpretation requires, however, theoretical support, as STM represents both electronic and topographic features. Molecules with accessible redox levels offer other insight into electron tunneling mechanisms, addressed in detail for ET metalloproteins. We present here in situ STM...... of the blue redox metalloenzyme copper nitrite reductase (Achromobacter xylosoxidans, AxCuNiR) on Au(111) electrode surfaces modified by a self-assembled cysteamine monolayer. AxCuNiR displays strong nitrite reduction waves in this environment. AxCuNiR/cysteamine/ Au(111) surfaces were imaged at KNO2...

  19. Excitation of the 5p57p levels of xenon by electron impact

    International Nuclear Information System (INIS)

    Sharma, L.; Sharma, L.; Srivastava, R.; Stauffer, A.D.

    2011-01-01

    We have used our relativistic distorted-wave method to calculate cross sections for the electron-impact excitation of the ground state of xenon to all the 5p 5 7p fine-structure levels. The results are compared with the recent experimental measurements of Jung et al. [Phys. Rev. A 80, 062708 (2009)]. We show that the measured cross sections of Jung et al. for excitation of the levels with angular momentum J odd are dominated by cascading from higher-lying levels. Analytic fits to our cross sections are also provided for use in plasma modeling studies

  20. Electron excitation cross sections of the 2p53s levels of neon

    International Nuclear Information System (INIS)

    Phillips, M.H.

    1982-01-01

    The electron excitation cross sections of the four 2p 5 3s levels of neon are measured by means of a new technique using laser induced fluorescenc. The values of both the apparent and direct excitatiuon cross sections are given as a function of incident electron energy (0-100eV for 1s 3 and 1s 5 metastable levels and 0-300 eV for the 1s 2 and 1s 4 resonance levels). The metastable levels are triplet states and their cross sections are sharply peaked. At the peak, 30 eV, the measured values of the cross sections are 0.59 x 10 -18 cm 2 for the 1s 3 level and 3.2 x 10 -18 cm 2 for the 1s 5 level. The 1s 2 and 1s 4 levels are mixtures of singlet and triplet states, and the cross sections are broad and peak at 60 eV. The apparent cross sections at 60 eV are 13.5 x 10 -18 cm 2 for the 1s 2 level and 2.9 x 10 -18 cm 2 for the 1s 4 level. Measurement of the atomic number density of each of the 1s levels is performed using the pulsed laser induced fluorescence. The measured values of the number density and the excitation cross section are used to obtain the lifetime of each level. The measured value of the reciprocal of the 1s 3 and 1s 5 lifetime is 1 x 10 5 s -1 . The 1s 2 and 1s 4 levels are radiation trapped, and the reciprocals of their lifetimes are 4 x 10 5 s -1 and 3 x 10 5 s -1 respectively. The electron excitation cross sections of the magnetic sublevels of each 1s level are obtained by measuring the polarization of the laser induced fluorescence as a function of laser polarization. The excitation cross sections of each of the magnetic sublevels within a particular 1s level are equal within experimental uncertainty

  1. Propagation of microwaves in pulsar magnetospheres

    Energy Technology Data Exchange (ETDEWEB)

    Bodo, G; Ferrari, A [Turin Univ. (Italy). Ist. di Fisica Generale; Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica); Massaglia, S [Turin Univ. (Italy). Ist. di Fisica Generale; Cambridge Univ. (UK). Inst. of Astronomy)

    1981-12-01

    We discuss the dispersion relation of linearly-polarized waves, propagating along a strong background magnetic field embedded in an electron-positron plasma. The results are then applied to the study of the propagation conditions of coherent curvature radio radiation inside neutron stars magnetospheres, as produced by electric discharges following current pulsar models.

  2. Photoelectron and electron momentum spectroscopy of 1-butene at benchmark theoretical levels

    International Nuclear Information System (INIS)

    Shojaei, S H Reza; Morini, Filippo; Hajgató, Bálazs; Deleuze, Michael S

    2011-01-01

    The results of experimental studies of the valence electronic structure of 1-butene employing photoelectron spectroscopy as well as electron momentum spectroscopy are interpreted on the ground of quantitative calculations of one-electron and shake-up ionization energies and of the related Dyson orbitals, using one-particle Green's function theory in conjunction with the third-order algebraic diagrammatic construction scheme (ADC(3)). Comparison is made with simulations of (e, 2e) electron momentum distributions obtained from standard (B3LYP) Kohn-Sham orbitals. Our analysis is based on highly quantitative determinations of the energy difference between the cis and gauche (C 1 ) conformers, within ∼0.02 kcal mol -1 accuracy, and a thermostatistical evaluation thereby of conformer weights beyond the level of the rigid rotor harmonic oscillator approximation. Relative entropies are found to be particularly sensitive to hindered rotations. The shake-up onset is located at 15.9 eV, and the orbital picture of ionization breaks down completely at electron binding energies above 19 eV. If the available experimental momentum profiles demonstrate the dominance of the C 1 conformer, they are in this case clearly not sensitive enough to the molecular conformation for evaluating conformer abundances with accuracies better than 10% due to the limited energy and momentum resolutions and likely physical complications.

  3. Electron impact excitation of fine-structure levels of neon-like titanium (Ti XIII)

    International Nuclear Information System (INIS)

    Gupta, G.P.; Deb, N.C.; Msezane, A.Z.

    1999-01-01

    The authors present results of a Breit-Pauli R-matrix calculation for the electron impact excitation of neon-like titanium, in which the 27 lowest fine-structure target levels arising out of the 4 lowest configurations 2s 2 2p 6 , 2s 2 2p 5 3s, 2s 2 2p 5 3p, and 2s 2 2p 5 3d are included. These target levels are represented by configuration interaction wave functions using the 1s, 2s, 2p, 3s, 3p, and 3d basic orbitals. The relativistic effects are included in the Breit-Pauli approximation via one-body mass correction, Darwin, and spin-orbit interaction terms in the scattering equations. For many transitions, complex resonance structures are found in the excitation cross sections. The excitation cross sections are integrated over a Maxwellian distribution of electron energies to give electron excitation rate coefficients over a wide temperature range from 150 to 600 eV. The relative populations for different electron densities and temperatures are also presented

  4. Measurement and calculation of excitation cross sections and level ionization by electron impact

    International Nuclear Information System (INIS)

    Blanco Rames, F.

    1990-01-01

    The experimental and theoretical study of the atomic structure in neutral noble gases is studied in this work. It mainly deals with the determination of total cross sections by electron impact and transition probabilities, including: Chapter 1: Theoretical introduction and the intermediate coupling description obtained for 420 levels of s, p and d configurations in neutral noble gases. Chapter 2: Experimental and theoretical values for electron collision cross sections are obtained for several levels of He, Ne, Ar and Kr. Our results as well as those available from existing bibliography are sumarized and compared. By means of an intermediate coupling treatment a number of regularities is found that provides us with some useful approximate semi empirical expressions. Chapter 3: Determination of lifetime and transition probabilities. Lifetime measurements are carried out by means of laser excitation and multichannel delayed coincidences technique. The experimental setup and electronics are also described. Chapter 4: Details the experimental setup developed for electron cross sections measurement by the optical method. The difficulties of this method and their treatment are also shown. (Author)

  5. Voltage tunable plasmon propagation in dual gated bilayer graphene

    Science.gov (United States)

    Farzaneh, Seyed M.; Rakheja, Shaloo

    2017-10-01

    In this paper, we theoretically investigate plasmon propagation characteristics in AB and AA stacked bilayer graphene (BLG) in the presence of energy asymmetry due to an electrostatic field oriented perpendicularly to the plane of the graphene sheet. We first derive the optical conductivity of BLG using the Kubo formalism incorporating energy asymmetry and finite electron scattering. All results are obtained for room temperature (300 K) operation. By solving Maxwell's equations in a dual gate device setup, we obtain the wavevector of propagating plasmon modes in the transverse electric (TE) and transverse magnetic (TM) directions at terahertz frequencies. The plasmon wavevector allows us to compare the compression factor, propagation length, and the mode confinement of TE and TM plasmon modes in bilayer and monolayer graphene sheets and also to study the impact of material parameters on plasmon characteristics. Our results show that the energy asymmetry can be harnessed to increase the propagation length of TM plasmons in BLG. AA stacked BLG shows a larger increase in the propagation length than AB stacked BLG; conversely, it is very insensitive to the Fermi level variations. Additionally, the dual gate structure allows independent modulation of the energy asymmetry and the Fermi level in BLG, which is advantageous for reconfiguring plasmon characteristics post device fabrication.

  6. Study and development of different techniques for the generation, conversion, propagation, and radiation of high power microwaves for the electronic cyclotron frequency plasma heating

    International Nuclear Information System (INIS)

    Rebuffi, L.

    1987-10-01

    The development and optimization of a microwave technique, concerning the high frequency (electronic cyclotron frequency) plasma heating is presented. The experiments are effectuated on the Fontenay-aux-Roses TFR tokamak, with 660 kw whole power, during 100 msec, produced at 60 GHz. Low power tests are performed on the different transmission line components (there are 3, formed by metallic circular waveguides). The work also includes: the development of a lens formed by thin metallic plans; the study of slotted surface mirror; the development of a system for the accurate measurement (5.10 -6 ) of the gyrotronic frequency; a theory, based on the equivalent circuits method, generalized to the rotational and polarization mirrors; the development of a numerical simulation code. A practical scheme, for the optimization of the parameters concerning the optical transmission line project, is given. The results of this work can be applied to the experiment involving power levels, frequencies and times of impulsion increasingly higher (respectively about MW, 100 GHz and 10s) than the reported ones. Moreover, they can also be used in any experiment in the microwave field [fr

  7. Electron transfer behaviour of biological macromolecules towards the single-molecule level

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Grubb, Mikala; Hansen, Allan Glargaard

    2003-01-01

    is combined with state-of-the-art physical electrochemistry with emphasis on single-crystal, atomically planar electrode surfaces, in situ scanning tunnelling microscopy (STM) and other surface techniques. These approaches have brought bioelectrochemistry important steps forward towards the nanoscale...... and single-molecule levels.We discuss here these advances with reference to two specific redox metalloproteins, the blue single-copper protein Pseudomonas aeruginosa azurin and the single-haem protein Saccharomyces cerevisiae yeast cytochrome c, and a short oligonucleotide. Both proteins can be immobilized...... electron transfer (ET) function retained. In situ STM can also address the microscopic mechanisms for electron tunnelling through the biomolecules and offers novel notions such as coherent multi-ET between the substrate and tip via the molecular redox levels. This differs in important respects from...

  8. Part two: Error propagation

    International Nuclear Information System (INIS)

    Picard, R.R.

    1989-01-01

    Topics covered in this chapter include a discussion of exact results as related to nuclear materials management and accounting in nuclear facilities; propagation of error for a single measured value; propagation of error for several measured values; error propagation for materials balances; and an application of error propagation to an example of uranium hexafluoride conversion process

  9. Full counting statistics of level renormalization in electron transport through double quantum dots

    International Nuclear Information System (INIS)

    Luo Junyan; Shen Yu; Cen Gang; He Xiaoling; Wang Changrong; Jiao Hujun

    2011-01-01

    We examine the full counting statistics of electron transport through double quantum dots coupled in series, with particular attention being paid to the unique features originating from level renormalization. It is clearly illustrated that the energy renormalization gives rise to a dynamic charge blockade mechanism, which eventually results in super-Poissonian noise. Coupling of the double dots to an external heat bath leads to dephasing and relaxation mechanisms, which are demonstrated to suppress the noise in a unique way.

  10. Semiclassical propagator of the Wigner function.

    Science.gov (United States)

    Dittrich, Thomas; Viviescas, Carlos; Sandoval, Luis

    2006-02-24

    Propagation of the Wigner function is studied on two levels of semiclassical propagation: one based on the Van Vleck propagator, the other on phase-space path integration. Leading quantum corrections to the classical Liouville propagator take the form of a time-dependent quantum spot. Its oscillatory structure depends on whether the underlying classical flow is elliptic or hyperbolic. It can be interpreted as the result of interference of a pair of classical trajectories, indicating how quantum coherences are to be propagated semiclassically in phase space. The phase-space path-integral approach allows for a finer resolution of the quantum spot in terms of Airy functions.

  11. Electron capture detection of sulphur gases in carbon dioxide at the parts-per-billion level

    International Nuclear Information System (INIS)

    Pick, M.E.

    1979-01-01

    A gas chromatograph with an electron capture detector has been used to determine sulphur gases in CO 2 at the parts-per-billion level, with particular application to the analysis of coolant from CO 2 cooled nuclear reactors. For COS, CS 2 , CH 3 SH, H 2 S and (CH 3 ) 2 S 2 the detector has a sensitivity comparable with the more commonly used flame photometric detector, but it is much less sensitive towards (CH 3 ) 2 S and thiophene. In addition, the paper describes a simple method for trapping sulphur gases which might enable detection of sub parts-per-billion levels of sulphur compounds. (Auth.)

  12. Plasma-screening effects upon energy levels and electron scattering from neutral and ionized caesium

    International Nuclear Information System (INIS)

    Chin, Y.J.; Radtke, R.; Zimmermann, R.

    1988-01-01

    Using interaction potentials screened with the Debye-Hueckel length, the effects of plasma shielding on energy levels and electrons scattering from neutral and ionized caesium are estimated. Both energy levels and atomic scattering cross-sections are found to be sensitive to the inclusion of screening. Relating to the scattering by the Cs + ion, a low-energy resonance near E = 0.3 Ryd is found which arises from the f-wave phase shift and reflects the individual behaviour of the scattering ion. (author)

  13. Plasma-screening effects upon energy levels and electron scattering from neutral and ionized caesium

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Y J; Radtke, R; Zimmermann, R

    1988-01-01

    Using interaction potentials screened with the Debye-Hueckel length, the effects of plasma shielding on energy levels and electrons scattering from neutral and ionized caesium are estimated. Both energy levels and atomic scattering cross-sections are found to be sensitive to the inclusion of screening. Relating to the scattering by the Cs/sup +/ ion, a low-energy resonance near E = 0.3 Ryd is found which arises from the f-wave phase shift and reflects the individual behaviour of the scattering ion.

  14. Isotope shifts and electronic configurations of some of the energy levels of the neutral gadolinium atom

    International Nuclear Information System (INIS)

    Ahmad, S.A.; Venugopalan, A.; Saksena, G.D.

    1982-01-01

    Isotope shift ΔT (156-160) have been evaluated for 52 odd and 90 even energy levels of the neutral gadolinium atom from the measurements carried out on 166 lines of the first spectrum in the region 4535 to 4975 A on a photoelectric recording Fabry-Perot Spectrometer and enriched samples of 156 Gd and 160 Gd. Earlier studies provide data for just two lines in this region. Assignment of electronic configurations to some of the energy levels have been either confirmed or revised; some unassigned levels have been assigned probable configurations. The present study provides, for the first time, isotope shift of the two levels of 4f 7 6s 2 7s configuration of Gd I. (author)

  15. An economic prediction of the finer resolution level wavelet coefficients in electronic structure calculations.

    Science.gov (United States)

    Nagy, Szilvia; Pipek, János

    2015-12-21

    In wavelet based electronic structure calculations, introducing a new, finer resolution level is usually an expensive task, this is why often a two-level approximation is used with very fine starting resolution level. This process results in large matrices to calculate with and a large number of coefficients to be stored. In our previous work we have developed an adaptively refined solution scheme that determines the indices, where the refined basis functions are to be included, and later a method for predicting the next, finer resolution coefficients in a very economic way. In the present contribution, we would like to determine whether the method can be applied for predicting not only the first, but also the other, higher resolution level coefficients. Also the energy expectation values of the predicted wave functions are studied, as well as the scaling behaviour of the coefficients in the fine resolution limit.

  16. Composite Fermi surface in the half-filled Landau level with anisotropic electron mass

    Science.gov (United States)

    Ippoliti, Matteo; Geraedts, Scott; Bhatt, Ravindra

    We study the problem of interacting electrons in the lowest Landau level at half filling in the quantum Hall regime, when the electron dispersion is given by an anisotropic mass tensor. Based on experimental observations and theoretical arguments, the ground state of the system is expected to consist of composite Fermions filling an elliptical Fermi sea, with the anisotropy of the ellipse determined by the competing effects of the isotropic Coulomb interaction and anisotropic electron mass tensor. We test this idea quantitatively by using a numerical density matrix renormalization group method for quantum Hall systems on an infinitely long cylinder. Singularities in the structure factor allow us to map the Fermi surface of the composite Fermions. We compute the composite Fermi surface anisotropy for several values of the electron mass anisotropy which allow us to deduce the functional dependence of the former on the latter. This research was supported by Department of Energy Office of Basic Energy Sciences through Grant No. DE-SC0002140.

  17. Selective excitation of a vibrational level within the electronic ground state of a polyatomic molecule with ultra pulses

    CSIR Research Space (South Africa)

    de Clercq, L

    2010-09-01

    Full Text Available Coherent control of the upper vibrational level populations in the electronic ground state of a polyatomic molecule was simulated. Results indicate that selective excitation of a specific upper state level is possible...

  18. Intranet and village community: optimization of public service based on electronic government at the local level

    Science.gov (United States)

    Pradana, G. W.; Fanida, E. H.; Niswah, F.

    2018-01-01

    The demand for good governance is directed towards the realization of efficiency, effectiveness, and clean government. The move is demonstrated through national and regional levels to develop and implement electronic government concepts. Through the development of electronic government is done structuring management systems and work processes in the government environment by optimizing the utilization of information technology. One of the real forms of electronic government (e-Gov) implementation at the local level is the Intranet Sub-District program in Sukodono Sub-District, Sidoarjo. Intranet Sub-District is an innovation whose purpose is to realize the availability of information on the utilization of management, distribution, and storage of official scripts, and also the optimal delivery of information and communication in the implementation of guidance and supervision of local administration. The type of this paper is descriptive with a qualitative approach and focus on the implementation of the Intranet District Program in Sukodono District, Sidoarjo. The findings of the study are the limited number of human resources who have mastered ICT, the uneven network, the adequacy of institutional needs and the existence of budget support from the authorized institution and the information system has not accommodated all the service needs.

  19. Measured Radiation and Background Levels During Transmission of Megawatt Electron Beams Through Millimeter Apertures

    Energy Technology Data Exchange (ETDEWEB)

    Alarcon, Ricardo [Arizona State University, Glendale, AZ (United States); Balascuta, S. [Arizona State University, Glendale, AZ (United States); Benson, Stephen V. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Bertozzi, William [Massachusetts Institute of Technology, Cambridge, MA (United States); Boyce, James R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Cowan, Ray [Massachusetts Institute of Technology, Cambridge, MA (United States); Douglas, David R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Evtushenko, Pavel [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Fisher, P. [Massachusetts Institute of Technology, Cambridge, MA (United States); Ihloff, Ernest E. [Hampton University, Hampton, VA (United States); Kalantarians, Narbe [Hampton University, Hampton, VA (United States); Kelleher, Aidan Michael [Massachusetts Institute of Technology, Cambridge, MA (United States); Krossler, W. J. [William and Mary College, Williamsburg, VA (United States); Legg, Robert A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Long, Elena [University of New Hampshire, Durham, NH (United States); Milner, Richard [Massachusetts Institute of Technology, Cambridge, MA (United States); Neil, George R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Ou, Longwu [Massachusetts Institute of Technology, Cambridge, MA (United States); Schmookler, Barack Abraham [Massachusetts Institute of Technology, Cambridge, MA (United States); Tennant, Christopher D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Tschalar, C. [Massachusetts Institute of Technology, Cambridge, MA (United States); Williams, Gwyn P. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Zhang, Shukui [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2013-11-01

    We report measurements of photon and neutron radiation levels observed while transmitting a 0.43 MW electron beam through millimeter-sized apertures and during beam-off, but accelerating gradient RF-on, operation. These measurements were conducted at the Free-Electron Laser (FEL) facility of the Jefferson National Accelerator Laboratory (JLab) using a 100 MeV electron beam from an energy-recovery linear accelerator. The beam was directed successively through 6 mm, 4 mm, and 2 mm diameter apertures of length 127 mm in aluminum at a maximum current of 4.3 mA (430 kW beam power). This study was conducted to characterize radiation levels for experiments that need to operate in this environment, such as the proposed DarkLight Experiment. We find that sustained transmission of a 430 kW continuous-wave (CW) beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, multipactoring inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation when the machine is tuned for 130 MeV operation.

  20. Availability, Level of Use and Constraints to Use of Electronic Resources by Law Lecturers in Public Universities in Nigeria

    Science.gov (United States)

    Amusa, Oyintola Isiaka; Atinmo, Morayo

    2016-01-01

    (Purpose) This study surveyed the level of availability, use and constraints to use of electronic resources among law lecturers in Nigeria. (Methodology) Five hundred and fifty-two law lecturers were surveyed and four hundred and forty-two responded. (Results) Data analysis revealed that the level of availability of electronic resources for the…

  1. Tree-level equivalence between a Lorentz-violating extension of QED and its dual model in electron-electron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Toniolo, Giuliano R.; Fargnoli, H.G.; Brito, L.C.T. [Universidade Federal de Lavras, Departamento de Fisica, Caixa Postal 3037, Lavras, Minas Gerais (Brazil); Scarpelli, A.P.B. [Setor Tecnico-Cientifico, Departamento de Policia Federal, Sao Paulo (Brazil)

    2017-02-15

    S-matrix amplitudes for the electron-electron scattering are calculated in order to verify the physical equivalence between two Lorentz-breaking dual models. We begin with an extended Quantum Electrodynamics which incorporates CPT-even Lorentz-violating kinetic and mass terms. Then, in a process of gauge embedding, its gauge-invariant dual model is obtained. The physical equivalence of the two models is established at tree level in the electron-electron scattering and the unpolarized cross section is calculated up to second order in the Lorentz-violating parameter. (orig.)

  2. Tree-level equivalence between a Lorentz-violating extension of QED and its dual model in electron-electron scattering

    International Nuclear Information System (INIS)

    Toniolo, Giuliano R.; Fargnoli, H.G.; Brito, L.C.T.; Scarpelli, A.P.B.

    2017-01-01

    S-matrix amplitudes for the electron-electron scattering are calculated in order to verify the physical equivalence between two Lorentz-breaking dual models. We begin with an extended Quantum Electrodynamics which incorporates CPT-even Lorentz-violating kinetic and mass terms. Then, in a process of gauge embedding, its gauge-invariant dual model is obtained. The physical equivalence of the two models is established at tree level in the electron-electron scattering and the unpolarized cross section is calculated up to second order in the Lorentz-violating parameter. (orig.)

  3. Evaluation of Detrimental Effects on Mechanical Properties of Zry-4 Due to Hydrogen Absorption by means of Scanning Electron Microscopy (SEM) In-Situ Observation of Crack Propagation

    International Nuclear Information System (INIS)

    Fernandez, L; Fernandez, G.E; Bertolino, G; Meyer, G

    2001-01-01

    The study of mechanical properties degradation of zirconium alloys due to hydrides assumes fundamental importance in the nuclear industry.During normal nuclear reactors operation, structural parts absorbed hydrogen generated from radiolysis of water, causing detrimental effects on mechanical properties.As a consequence, these materials are easily cracked in the presence of mechanical solicitation due to loss of ductility of the hydride-phase.The presence of cracks indicates fracture mechanic as the most suitable methodology in the study of mechanical properties degradation.In this work we used the crack tip opening displacement (CTOD) criteria to evaluate the detrimental effects on mechanical properties with the observation in SEM of crack propagation.The samples used were SEN (B) of Zry-4 and cathodic homogenous charged with hydrogen concentrations lower than 400 ppm

  4. Understanding the effects of electronic polarization and delocalization on charge-transport levels in oligoacene systems

    KAUST Repository

    Sutton, Christopher; Tummala, Naga Rajesh; Kemper, Travis; Aziz, Saadullah G.; Sears, John; Coropceanu, Veaceslav; Bredas, Jean-Luc

    2017-01-01

    Electronic polarization and charge delocalization are important aspects that affect the charge-transport levels in organic materials. Here, using a quantum mechanical/ embedded-charge (QM/EC) approach based on a combination of the long-range corrected omega B97X-D exchange-correlation functional (QM) and charge model 5 (CM5) point-charge model (EC), we evaluate the vertical detachment energies and polarization energies of various sizes of crystalline and amorphous anionic oligoacene clusters. Our results indicate that QM/EC calculations yield vertical detachment energies and polarization energies that compare well with the experimental values obtained from ultraviolet photoemission spectroscopy measurements. In order to understand the effect of charge delocalization on the transport levels, we considered crystalline naphthalene systems with QM regions including one or five-molecules. The results for these systems show that the delocalization and polarization effects are additive; therefore, allowing for electron delocalization by increasing the size of the QM region leads to the additional stabilization of the transport levels. Published by AIP Publishing.

  5. Electronic Energy Levels and Band Alignment for Aqueous Phenol and Phenolate from First Principles.

    Science.gov (United States)

    Opalka, Daniel; Pham, Tuan Anh; Sprik, Michiel; Galli, Giulia

    2015-07-30

    Electronic energy levels in phenol and phenolate solutions have been computed using density functional theory and many-body perturbation theory. The valence and conduction bands of the solvent and the ionization energies of the solutes have been aligned with respect to the vacuum level based on the concept of a computational standard hydrogen electrode. We have found significant quantitative differences between the generalized-gradient approximation, calculations with the HSE hybrid functional, and many-body perturbation theory in the G0W0 approximation. For phenol, two ionization energies below the photoionization threshold of bulk water have been assigned in the spectrum of Kohn-Sham eigenvalues of the solution. Deprotonation to phenolate was found to lift a third occupied energy level above the valence band maximum of the solvent which is characterized by an electronic lone pair at the hydroxyl group. The second and third ionization energies of phenolate were found to be very similar and explain the intensity pattern observed in recent experiments using liquid-microjet photoemission spectroscopy.

  6. Chern-Simons field theory of two-dimensional electrons in the lowest Landau level

    International Nuclear Information System (INIS)

    Zhang, L.

    1996-01-01

    We propose a fermion Chern-Simons field theory describing two-dimensional electrons in the lowest Landau level. This theory is constructed with a complete set of states, and the lowest-Landau-level constraint is enforced through a δ functional described by an auxiliary field λ. Unlike the field theory constructed directly with the states in the lowest Landau level, this theory allows one, utilizing the physical picture of open-quote open-quote composite fermion,close-quote close-quote to study the fractional quantum Hall states by mapping them onto certain integer quantum Hall states; but, unlike its application in the unconstrained theory, such a mapping is sensible only when interactions between electrons are present. An open-quote open-quote effective mass,close-quote close-quote which characterizes the scale of low energy excitations in the fractional quantum Hall systems, emerges naturally from our theory. We study a Gaussian effective theory and interpret physically the dressed stationary point equation for λ as an equation for the open-quote open-quote mass renormalization close-quote close-quote of composite fermions. copyright 1996 The American Physical Society

  7. Understanding the effects of electronic polarization and delocalization on charge-transport levels in oligoacene systems

    KAUST Repository

    Sutton, Christopher

    2017-06-13

    Electronic polarization and charge delocalization are important aspects that affect the charge-transport levels in organic materials. Here, using a quantum mechanical/ embedded-charge (QM/EC) approach based on a combination of the long-range corrected omega B97X-D exchange-correlation functional (QM) and charge model 5 (CM5) point-charge model (EC), we evaluate the vertical detachment energies and polarization energies of various sizes of crystalline and amorphous anionic oligoacene clusters. Our results indicate that QM/EC calculations yield vertical detachment energies and polarization energies that compare well with the experimental values obtained from ultraviolet photoemission spectroscopy measurements. In order to understand the effect of charge delocalization on the transport levels, we considered crystalline naphthalene systems with QM regions including one or five-molecules. The results for these systems show that the delocalization and polarization effects are additive; therefore, allowing for electron delocalization by increasing the size of the QM region leads to the additional stabilization of the transport levels. Published by AIP Publishing.

  8. Electron impact excitation out of the 23S metastable level of He

    International Nuclear Information System (INIS)

    Boffard, J.B.; Piech, G.A.; Lagus, M.E.; Anderson, L.W.; Chun C.L.

    1996-01-01

    Using a hollow cathode discharge as a source of He, the authors have measured absolute cross sections for electron excitation out of the 2S level of He into the n=2, 3, 4, and 5 triplet levels for energies up to 20 eV. Their results show a pattern of sharply peaked excitation functions into the n = 3, 4, and 5 3 S and 3 P levels, and comparatively broad excitation functions into the 3 D levels. The 2 3 P level has a remarkably broad excitation function, and its peak direct cross section is over 10 times the size of the next largest peak cross section observed. For energies above 20 eV, the authors use charge exchange of a fast He + beam with cesium to produce a primarily He target. This allows them to extend their measurements for selected triplet levels out to 1 keV. Their data indicate that even at this energy the excitations into the 3 3 S, 3 3 D, 4 3 D have not yet entered the Born regime. Comparisons with other theoretical calculations at low energies will be made

  9. New way for determining electron energy levels in quantum dots arrays using finite difference method

    Science.gov (United States)

    Dujardin, F.; Assaid, E.; Feddi, E.

    2018-06-01

    Electronic states are investigated in quantum dots arrays, depending on the type of cubic Bravais lattice (primitive, body centered or face centered) according to which the dots are arranged, the size of the dots and the interdot distance. It is shown that the ground state energy level can undergo significant variations when these parameters are modified. The results were obtained by means of finite difference method which has proved to be easily adaptable, efficient and precise. The symmetry properties of the lattice have been used to reduce the size of the Hamiltonian matrix.

  10. Numerology, hydrogenic levels, and the ordering of excited states in one-electron atoms

    Science.gov (United States)

    Armstrong, Lloyd, Jr.

    1982-03-01

    We show that the observed ordering of Rydberg states of one-electron atoms can be understood by assuming that these states are basically hydrogenic in nature. Much of the confusion concerning this point is shown to arise from the failure to differentiate between hydrogenic ordering as the nuclear charge approaches infinity, and hydrogenic ordering for an effective charge of one. The origin of κ ordering of Rydberg levels suggested by Sternheimer is considered within this picture, and the predictions of κ ordering are compared with those obtained by assuming hydrogenic ordering.

  11. Extended Pulse-Powered Humidity-Freeze Cycling for Testing Module-Level Power Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kempe, Michael D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Repins, Ingrid L [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-28

    An EMI suppression capacitor (polypropylene film type) failed by 'popcorning' due to vapor outgassing in pulse powered humidity-freeze cycles. No shorts or shunts could be detected despite mildly corroded metallization visible in the failed capacitor. Humidity-freeze cycling is optimized to break into moisture barriers. However, further studies will be required on additional module level power electronic (MLPE) devices to optimize the stress testing for condensation to precipitate any weakness to short circuiting and other humidity/bias failure modes.

  12. Tobacco-Specific Nitrosamines in Electronic Cigarettes: Comparison between Liquid and Aerosol Levels

    Directory of Open Access Journals (Sweden)

    Konstantinos E. Farsalinos

    2015-07-01

    Full Text Available Introduction: Although electronic cigarette (EC liquids contain low levels of tobacco-specific nitrosamines (TSNAs, studies evaluating the levels emitted to the aerosol are scarce. The purpose of this study was to compare the levels of TSNAs between liquids and generated aerosol. Methods: Three EC liquids were obtained from the market. An additional (spiked sample was prepared by adding known amounts of standard TSNAs solutions to one of the obtained liquids. N-nitrosonornicotine (NNN, N-nitrosoanatabine (NAT, N-nitrosoanabasine (NAB and 4-(methylnitrosamino1-(3-pyridyl-1-butanone (NNK were measured. Three 100-puff sets from each liquid were trapped in filter pads and were subsequently analyzed for the presence of TSNAs. The expected levels of TSNAs (calculated based on the liquid consumption were compared with the measured levels in the aerosol. Results: Only NAB was found at trace levels in two commercial liquids (1.2 and 2.3 ng/g, while the third contained 1.5 ng/g NAB and 7.7 ng/g NNN. The 100-puff sets resulted in 336–515 mg liquid consumption, with no TSNAs being detected in the aerosol. The spiked sample contained 42.0–53.9 ng/g of each of the TSNAs. All TSNAs were detected in the aerosol with the measured levels being statistically similar to the expected amounts. A significant correlation between expected and measured levels of TSNAs in the aerosol was found (r = 0.83, p < 0.001. Conclusion: The findings of this study show that exposure of EC users to TSNAs can be accurately assessed based on the levels present in the liquid, without the need to analyze the aerosol.

  13. Detecting Fermi-level shifts by Auger electron spectroscopy in Si and GaAs

    Science.gov (United States)

    Debehets, J.; Homm, P.; Menghini, M.; Chambers, S. A.; Marchiori, C.; Heyns, M.; Locquet, J. P.; Seo, J. W.

    2018-05-01

    In this paper, changes in surface Fermi-level of Si and GaAs, caused by doping and cleaning, are investigated by Auger electron spectroscopy. Based on the Auger voltage contrast, we compared the Auger transition peak energy but with higher accuracy by using a more accurate analyzer and an improved peak position determination method. For silicon, a peak shift as large as 0.46 eV was detected when comparing a cleaned p-type and n-type wafer, which corresponds rather well with the theoretical difference in Fermi-levels. If no cleaning was applied, the peak position did not differ significantly for both wafer types, indicating Fermi-level pinning in the band gap. For GaAs, peak shifts were detected after cleaning with HF and (NH4)2S-solutions in an inert atmosphere (N2-gas). Although the (NH4)2S-cleaning in N2 is very efficient in removing the oxygen from the surface, the observed Ga- and As-peak shifts are smaller than those obtained after the HF-cleaning. It is shown that the magnitude of the shift is related to the surface composition. After Si-deposition on the (NH4)2S-cleaned surface, the Fermi-level shifts back to a similar position as observed for an as-received wafer, indicating that this combination is not successful in unpinning the Fermi-level of GaAs.

  14. PbSnTe:In compound: Electron capture levels, galvanomagnetic properties, and THz sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Ishchenko, D. V., E-mail: miracle4348@gmail.com; Klimov, A. E.; Shumsky, V. N.; Epov, V. S. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2016-12-15

    A model of the Pb{sub 1–x}Sn{sub x}Te:In compound, based on concepts of the theory of disordered systems is considered. The temperature dependences of the Fermi-level position and carrier concentration are calculated depending on the indium doping level and are compared with experimental data. The transient current–voltage characteristics are calculated in the mode of injection from the contact and current limitation by space charge at various voltage-variation rates. The data obtained are compared with the experiments. It is demonstrated that the shape of the characteristics is controlled by the parameters of electron capture at localized states. Photocurrent relaxation in a magnetic field is studied, and the mechanism of such relaxation is discussed under the assumption of the magnetic freezing of carriers.

  15. Electron-positron annihilation into hadrons at the higher-loop levels

    Energy Technology Data Exchange (ETDEWEB)

    Nesterenko, A.V. [Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation)

    2017-12-15

    The strong corrections to the R-ratio of electron-positron annihilation into hadrons are studied at the higher-loop levels. Specifically, the derivation of a general form of the commonly employed approximate expression for the R-ratio (which constitutes its truncated re-expansion at high energies) is delineated, the appearance of the pertinent π{sup 2}-terms is expounded, and their basic features are examined. It is demonstrated that the validity range of such approximation is strictly limited to √(s)/Λ > exp(π/2) ≅ 4.81 and that it converges rather slowly when the energy scale approaches this value. The spectral function required for the proper calculation of the R-ratio is explicitly derived and its properties at the higher-loop levels are studied. The developed method of calculation of the spectral function enables one to obtain the explicit expression for the latter at an arbitrary loop level. By making use of the derived spectral function the proper expression for the R-ratio is calculated up to the five-loop level and its properties are examined. It is shown that the loop convergence of the proper expression for the R-ratio is better than that of its commonly employed approximation. The impact of the omitted higher-order π{sup 2}-terms on the latter is also discussed. (orig.)

  16. Propagation of an ultra intense laser pulse in an under dense plasma: production of quasi monoenergetic electron beams and development of applications; Propagation d'une impulsion laser ultra-intense dans un plasma sous-dense: generation de faisceaux d'electrons quasi monoenergetiques et developpement d'applications

    Energy Technology Data Exchange (ETDEWEB)

    Glinec, Y

    2006-09-15

    This experimental study concerns the generation of electron beams with original properties. These electrons beams originate from the interaction of an ultra-intense and short laser pulse with a gas jet. Previously, these electron beams had a large divergence and a broad spectrum. A major improvement in this field was achieved when an electron beam with low divergence (10 mrad) and a peaked spectrum (170 MeV) was observed during this thesis, using a new single shot electron spectrometer. A parametric study of the interaction allowed to observe the evolution of the electron beam. Experiments have been carried out to deepen the characterization of the electron beam. The observation of transition radiation generated by the electrons at an interface shows that the electron beam interacts with the laser pulse during the acceleration. Radial oscillations of the electron beam around the laser axis, named betatron oscillations, were also observed on the electron spectra. Such a quasi-monoenergetic spectrum is essential for many applications. In order to justify the interest of this electron beam, several applications are presented: a sub-milli-metric gamma-ray radiography of dense objects, a dose profile of the electron beam comparable to present capabilities of photon sources for radiotherapy, a very short temporal profile useful for water radiolysis and the generation of a bright X-ray source with low divergence. (author)

  17. Propagation of an ultra intense laser pulse in an under dense plasma: production of quasi monoenergetic electron beams and development of applications; Propagation d'une impulsion laser ultra-intense dans un plasma sous-dense: generation de faisceaux d'electrons quasi monoenergetiques et developpement d'applications

    Energy Technology Data Exchange (ETDEWEB)

    Glinec, Y

    2006-09-15

    This experimental study concerns the generation of electron beams with original properties. These electrons beams originate from the interaction of an ultra-intense and short laser pulse with a gas jet. Previously, these electron beams had a large divergence and a broad spectrum. A major improvement in this field was achieved when an electron beam with low divergence (10 mrad) and a peaked spectrum (170 MeV) was observed during this thesis, using a new single shot electron spectrometer. A parametric study of the interaction allowed to observe the evolution of the electron beam. Experiments have been carried out to deepen the characterization of the electron beam. The observation of transition radiation generated by the electrons at an interface shows that the electron beam interacts with the laser pulse during the acceleration. Radial oscillations of the electron beam around the laser axis, named betatron oscillations, were also observed on the electron spectra. Such a quasi-monoenergetic spectrum is essential for many applications. In order to justify the interest of this electron beam, several applications are presented: a sub-milli-metric gamma-ray radiography of dense objects, a dose profile of the electron beam comparable to present capabilities of photon sources for radiotherapy, a very short temporal profile useful for water radiolysis and the generation of a bright X-ray source with low divergence. (author)

  18. Determination of absorbed dose calibration factors for therapy level electron beam ionization chambers.

    Science.gov (United States)

    McEwen, M R; Williams, A J; DuSautoy, A R

    2001-03-01

    Over several years the National Physical Laboratory (NPL) has been developing an absorbed dose calibration service for electron beam radiotherapy. To test this service, a number of trial calibrations of therapy level electron beam ionization chambers have been carried out during the last 3 years. These trials involved 17 UK radiotherapy centres supplying a total of 46 chambers of the NACP, Markus, Roos and Farmer types. Calibration factors were derived from the primary standard calorimeter at seven energies in the range 4 to 19 MeV with an estimated uncertainty of +/-1.5% at the 95% confidence level. Investigations were also carried out into chamber perturbation, polarity effects, ion recombination and repeatability of the calibration process. The instruments were returned to the radiotherapy centres for measurements to be carried out comparing the NPL direct calibration with the 1996 IPEMB air kerma based Code of Practice. It was found that, in general, all chambers of a particular type showed the same energy response. However, it was found that polarity and recombination corrections were quite variable for Markus chambers-differences in the polarity correction of up to 1% were seen. Perturbation corrections were obtained and were found to agree well with the standard data used in the IPEMB Code. The results of the comparison between the NPL calibration and IPEMB Code show agreement between the two methods at the +/-1% level for the NACP and Farmer chambers, but there is a significant difference for the Markus chambers of around 2%. This difference between chamber types is most likely to be due to the design of the Markus chamber.

  19. In situ hybridization at the electron microscope level: hybrid detection by autoradiography and colloidal gold.

    Science.gov (United States)

    Hutchison, N J; Langer-Safer, P R; Ward, D C; Hamkalo, B A

    1982-11-01

    In situ hybridization has become a standard method for localizing DNA or RNA sequences in cytological preparations. We developed two methods to extend this technique to the transmission electron microscope level using mouse satellite DNA hybridization to whole mount metaphase chromosomes as the test system. The first method devised is a direct extension of standard light microscope level using mouse satellite DNA hybridization to whole mount metaphase chromosomes as the test system. The first method devised is a direct extension of standard light microscope in situ hybridization. Radioactively labeled complementary RNA (cRNA) is hybridized to metaphase chromosomes deposited on electron microscope grids and fixed in 70 percent ethanol vapor; hybridixation site are detected by autoradiography. Specific and intense labeling of chromosomal centromeric regions is observed even after relatively short exposure times. Inerphase nuclei present in some of the metaphase chromosome preparations also show defined paatterms of satellite DNA labeling which suggests that satellite-containing regions are associate with each other during interphase. The sensitivity of this method is estimated to at least as good as that at the light microscope level while the resolution is improved at least threefold. The second method, which circumvents the use of autoradiogrphic detection, uses biotin-labeled polynucleotide probes. After hybridization of these probes, either DNA or RNA, to fixed chromosomes on grids, hybrids are detected via reaction is improved at least threefold. The second method, which circumvents the use of autoradiographic detection, uses biotin-labeled polynucleotide probes. After hybridization of these probes, either DNA or RNA, to fixed chromosomes on grids, hybrids are detected via reaction with an antibody against biotin and secondary antibody adsorbed to the surface of over centromeric heterochromatin and along the associated peripheral fibers. Labeling is on average

  20. Radiation level analysis for the port cell of the ITER electron cyclotron-heating upper launcher

    Energy Technology Data Exchange (ETDEWEB)

    Weinhorst, Bastian, E-mail: bastian.weinhorst@kit.edu [KIT, Institute for Neutron Physics and Reactor Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Fischer, Ulrich; Lu, Lei [KIT, Institute for Neutron Physics and Reactor Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Strauss, Dirk; Spaeh, Peter; Scherer, Theo [KIT, Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Leichtle, Dieter [F4E, Analysis & Codes/Technical Support Services, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain)

    2016-11-01

    Highlights: • First detailed neutronic modelling of the ECHUL port cell with ECHUL equipment (including beam lines with diamond windows, the beam lines mounting box, conduit boxes and rails). • Three different bioshield port plug configurations and two different neutron source configurations are investigated. • Radiation Levels are calculated in the port cell, focusing on the position of the diamond window. • The dose rate in the port cell is below the limit for maintenance in the port cell. • The radiation level at the diamond window is very low and should not influence its performance. - Abstract: The electron cyclotron-heating upper launcher (ECHUL) will be installed in four upper ports of the ITER tokamak thermonuclear fusion reactor. Each ECHUL is able to deposit 8 MW power into the plasma for plasma mode stabilization via microwave beam lines. An essential part of these beam lines are the diamond windows. They are located in the upper port cell behind the bioshield to reduce the radiation levels to a minimum. The paper describes the first detailed neutronic modelling of the ECHUL port cell with ECHUL equipment. The bioshield plug is modelled including passageways for the microwave beam lines, piping and cables looms as well as rails and openings for ventilation. The port cell is equipped with the beam lines including the diamond windows, the beam lines mounting box, conduit boxes and rails. The neutrons are transported into the port cell starting from a surface source in front of the bioshield. Neutronic results are obtained for radiation levels in the port cell at different positions, mainly focusing on the diamond windows position. It is shown that the radiation level is below the limit for maintenance in the port cell. The radiation level at the diamond window is very low and should not influence its performance.

  1. Electronic structure of free and doped actinides: N and Z dependences of energy levels and electronic structure parameters

    International Nuclear Information System (INIS)

    Kulagin, N.

    2005-01-01

    Theoretical study of electronic structure of antinide ions and its dependence on N and Z are presented in this paper. The main 5f N and excited 5f N n'l' N' configurations of actinides have been studied using Hartree-Fock-Pauli approximation. Results of calculations of radial integrals and the energy of X-ray lines for all 5f ions with electronic state AC +1 -AC +4 show approximate dependence on N and Z. A square of N and cubic of Z are ewalized for the primary electronic parameters of the actinides. Theoretical values of radial integrals for free actinides and for ions in a cluster AC +n :[L] k are compared, too

  2. Coulomb Repulsion Effect in Two-electron Non-adiabatic Tunneling through a One-level redox Molecule

    DEFF Research Database (Denmark)

    Medvedev, Igor M.; Kuznetsov, Alexander M.; Ulstrup, Jens

    2009-01-01

    We investigated Coulomb repulsion effects in nonadiabatic (diabatic) two-electron tunneling through a redox molecule with a single electronic level in a symmetric electrochemical contact under ambient conditions, i.e., room temperature and condensed matter environment. The electrochemical contact...

  3. A methodology for the extraction of quantitative information from electron microscopy images at the atomic level

    International Nuclear Information System (INIS)

    Galindo, P L; Pizarro, J; Guerrero, E; Guerrero-Lebrero, M P; Scavello, G; Yáñez, A; Sales, D L; Herrera, M; Molina, S I; Núñez-Moraleda, B M; Maestre, J M

    2014-01-01

    In this paper we describe a methodology developed at the University of Cadiz (Spain) in the past few years for the extraction of quantitative information from electron microscopy images at the atomic level. This work is based on a coordinated and synergic activity of several research groups that have been working together over the last decade in two different and complementary fields: Materials Science and Computer Science. The aim of our joint research has been to develop innovative high-performance computing techniques and simulation methods in order to address computationally challenging problems in the analysis, modelling and simulation of materials at the atomic scale, providing significant advances with respect to existing techniques. The methodology involves several fundamental areas of research including the analysis of high resolution electron microscopy images, materials modelling, image simulation and 3D reconstruction using quantitative information from experimental images. These techniques for the analysis, modelling and simulation allow optimizing the control and functionality of devices developed using materials under study, and have been tested using data obtained from experimental samples

  4. Visual attitude propagation for small satellites

    Science.gov (United States)

    Rawashdeh, Samir A.

    As electronics become smaller and more capable, it has become possible to conduct meaningful and sophisticated satellite missions in a small form factor. However, the capability of small satellites and the range of possible applications are limited by the capabilities of several technologies, including attitude determination and control systems. This dissertation evaluates the use of image-based visual attitude propagation as a compliment or alternative to other attitude determination technologies that are suitable for miniature satellites. The concept lies in using miniature cameras to track image features across frames and extracting the underlying rotation. The problem of visual attitude propagation as a small satellite attitude determination system is addressed from several aspects: related work, algorithm design, hardware and performance evaluation, possible applications, and on-orbit experimentation. These areas of consideration reflect the organization of this dissertation. A "stellar gyroscope" is developed, which is a visual star-based attitude propagator that uses relative motion of stars in an imager's field of view to infer the attitude changes. The device generates spacecraft relative attitude estimates in three degrees of freedom. Algorithms to perform the star detection, correspondence, and attitude propagation are presented. The Random Sample Consensus (RANSAC) approach is applied to the correspondence problem to successfully pair stars across frames while mitigating falsepositive and false-negative star detections. This approach provides tolerance to the noise levels expected in using miniature optics and no baffling, and the noise caused by radiation dose on orbit. The hardware design and algorithms are validated using test images of the night sky. The application of the stellar gyroscope as part of a CubeSat attitude determination and control system is described. The stellar gyroscope is used to augment a MEMS gyroscope attitude propagation

  5. Electron spectroscopy in the X-ray range for occupied and free levels and the application to transition metal silicides

    International Nuclear Information System (INIS)

    Speier, W.

    1988-03-01

    Intermetallic compounds of transition metals are investigated by means of XPS, Bremsstrahlung Isochromate Spectroscopy and XAS. Occupied and free levels are characterized and moreover a systematic overview over the electronic structure of the transition element silicides is given. (BHO)

  6. Damage related deep electron levels in ion implanted GaAs

    International Nuclear Information System (INIS)

    Allsopp, D.W.E.; Peaker, A.R.

    1986-01-01

    A study has been made of the deep electron levels in semi-insulating GaAs implanted with either 78 Se + or 29 Si + ions and rendered n-type by subsequent annealing without encapsulation in partial pressures of arsenic or arsine. Three implantation related deep states were detected with concentration profiles approximating to the type of Gaussian distributions expected for point defects related to ion implantation damage. Further heat treatment of the samples at 500 0 C in a gas ambient of U 2 /H 2 substantially reduced concentration of these deep levels. Two of these states were thought to be related to displacements of the substrate atoms. The third, at Esubc -0.67 eV, was found in only 78 Se + ion implanted GaAs substrates and was thought to be a defect involving both Se and As atoms, rather than intrinsic lattice disorder. It is proposed that the annealing rate of these implantation related deep levels depends crucially on the in-diffusion of arsenic vacancies during heat treatments. (author)

  7. Level-1 trigger selection of electrons and photons with CMS for LHC Run-II.

    CERN Document Server

    AUTHOR|(CDS)2088114

    2016-01-01

    The CMS experiment has a sophisticated two-level online selection system that achieves a rejection factor of nearly $10^5$. The first, hardware-level trigger (L1) is based on coarse information coming from the calorimeters and the muon detectors while the High-Level Trigger combines fine-grain information from all subdetectors. During Run II, the LHC will increase its center of mass energy to 13 or 14 TeV, and progressively reach an instantaneous luminosity of $2\\times10^{34} \\mathrm{cm}^{-2}\\mathrm{s}^{-1}$. In order to guarantee a successful and ambitious physics programme in this intense environment, the CMS trigger and data acquisition system must be upgraded. The L1 calorimeter trigger hardware and architecture in particular has been redesigned to maintain the current thresholds even in presence of more demanding conditions (e.g., for electrons and photons) and improve the performance for the selection of $\\tau$ leptons. This design benefits from recent $\\mu$TCA technology, allowing sophisticated algorit...

  8. Electron excitation coefficients of neutral and ionic levels of krypton in Townsend discharges

    International Nuclear Information System (INIS)

    Malovic, G.N.; Strinic, A.I.; Petrovic, Z.Lj.; Sadeghi, N.

    2006-01-01

    In this paper, we present experimental results for excitation coefficients of krypton atoms to several Kr and Kr + excited levels for E/N (electric field to gas particle number density ratio usually in units of Townsend, 1 Td = 10 -21 V m 2 ) values from 7 x 10 -20 V m 2 to above 1 x 10 -17 V m 2 . The data have been obtained in two different parallel plate self-sustained Townsend discharge drift tubes. The spatial distribution of the emission intensities were recorded and then normalized to give excitation coefficients at the anode, by using the electron flux at this point. The values of these coefficients are placed on an absolute scale by using a standard tungsten ribbon lamp calibrated against a primary blackbody radiation standard. The ionization rates at different E/N are obtained from the spatial emission profiles. The data for atomic krypton levels 2p 2 , 2p 3 , 2p 5 , 2p 6 , 2p 7 , 2p 8 , 3p 5 and 3p 6 (in Paschen notation) were converted to excitation coefficients by using quenching coefficients from the literature. The emission coefficients of eight 4s 2 4p 4 ( 3 P)5p levels of Kr + have also been measured for E/N values from about 1 x 10 -18 V m 2 up to nearly 8 x 10 -18 V m 2

  9. The Level of Brand Awareness in Consumer Electronic Products: The Example of Kazakhstan and Kyrgyzstan

    Directory of Open Access Journals (Sweden)

    Kutay Oktay

    2015-03-01

    Full Text Available Brand awareness which is considered as one of the most important factor affecting the consumer purchasing preferences has been investigated by both academics and practitioners in the field of marketing in recent years. The current study investigated brand awareness in Kazakhstan and Kyrgyzstan regarding consumer electronic products, such as laptop computers, tablet computers, and cell phones. To determine brand awareness, data were obtained by using suitable market analysis methods, andthen analyzed by using the Spearman correlation and the chi-square test for independence.Based on the study results, it was observed that the level brand awareness was high for laptop computers and cell phones, while being comparatively lower for tablet computers.

  10. Accumulation of fission fragment 147Pm in subcellular level studied by electron microscopic autoradiography

    International Nuclear Information System (INIS)

    Zhu Shoupeng; Wang Yuanchang

    1990-11-01

    The subcellular localization of fission fragment 147 Pm in tissue cells by electron microscopic autoradiography was investigated. The early harm of internal contaminated accumulation of 147 Pm appeared in blood cells and endothelium cells, obviously in erythrocytes. Then 147 Pm was selectively deposited in ultrastructure of liver cells. Autoradiographic study demonstrated that dense tracks appeared in mitochondria and lysosome of podal cells within renal corpuscle. In nucleus as well as in mitochondria and microbodies of epicyte of kidney near-convoluted tubule, there are numerous radioactive 149 Pm accumulated. With the prolongation of observing time, 149 Pm was selectively and steadily deposited in subcellular level of organic component bone. The radionuclides could be accumulated in nucleus of osteoclasts and osteoblasts. In organelles, the radionuclides was mainly accumulated in rough endoplasmic reticulum and mitochondria. Autoradiographic tracks of 149 Pm was obviously found to be localized in combined point between Golgi complex and transitive vesicle of rough endoplasmic reticulum

  11. Electron mobility on the surface of liquid Helium: influence of surface level atoms and depopulation of lowest subbands

    International Nuclear Information System (INIS)

    Grigoriev, P. D.; Dyugaev, A. M.; Lebedeva, E. V.

    2008-01-01

    The temperature dependence of electron mobility is examined. We calculate the contribution to the electron scattering rate from the surface level atoms (SLAs), proposed in [10]. This contribution is substantial at low temperatures T < 0.5, when the He vapor concentration is exponentially small. We also study the effect of depopulation of the lowest energy subband, which leads to an increase in the electron mobility at high temperature. The results explain certain long-standing discrepancies between the existing theory and experiment on electron mobility on the surface of liquid helium

  12. Magnetic-sublevel cross sections for excitation of the n 1P levels of helium by electron impact

    International Nuclear Information System (INIS)

    Csanak, G.; Cartwright, D.C.; Trajmar, S.

    1992-01-01

    First-order many-body theory has been used to calculate collision-frame magnetic-sublevel differential cross sections for electron-impact excitation of the n 1 P (n=2,3,4,5,6) levels of helium for electrons with incident energy in the 25--500-eV range. By combining results from electron-impact differential-cross-section measurements and electron-photon coincidence measurements, experimental magnetic-sublevel cross sections have also been derived for the excitation of the 2 1 P and 3 1 P levels. The theory predicts a pronounced minimum for the M=0 magnetic-sublevel differential cross section for incident electron energies around 30 eV. Our theoretical results are compared to the experimental data and some other theoretical results

  13. Local, atomic-level elastic strain measurements of metallic glass thin films by electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Ebner, C. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Sarkar, R. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rajagopalan, J. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Department of Mechanical and Aerospace Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rentenberger, C., E-mail: christian.rentenberger@univie.ac.at [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria)

    2016-06-15

    A novel technique is used to measure the atomic-level elastic strain tensor of amorphous materials by tracking geometric changes of the first diffuse ring of selected area electron diffraction patterns (SAD). An automatic procedure, which includes locating the centre and fitting an ellipse to the diffuse ring with sub-pixel precision is developed for extracting the 2-dimensional strain tensor from the SAD patterns. Using this technique, atomic-level principal strains from micrometre-sized regions of freestanding amorphous Ti{sub 0.45}Al{sub 0.55} thin films were measured during in-situ TEM tensile deformation. The thin films were deformed using MEMS based testing stages that allow simultaneous measurement of the macroscopic stress and strain. The calculated atomic-level principal strains show a linear dependence on the applied stress, and good correspondence with the measured macroscopic strains. The calculated Poisson’s ratio of 0.23 is reasonable for brittle metallic glasses. The technique yields a strain accuracy of about 1×10{sup −4} and shows the potential to obtain localized strain profiles/maps of amorphous thin film samples. - Highlights: • A TEM method to measure elastic strain in metallic glass films is proposed. • Method is based on tracking geometric changes in TEM diffraction patterns. • An automatic procedure is developed for extracting the local strain tensor. • Atomic-level strain in amorphous TiAl film was analysed during in-situ deformation. • Capability of the method to obtain micrometer scale strain profiles/maps is shown.

  14. Aspects of HF radio propagation

    Directory of Open Access Journals (Sweden)

    Stephane Saillant

    2009-06-01

    .

    c Development of inversion techniques enabling backscatter ionograms obtained by an HF radar to be used

    to estimate the ionospheric electron density profile. This development facilitates the operation of over the horizon

    HF radars by enhancing the frequency management aspects of the systems.

    d Various propagation prediction techniques have been tested against measurements made over the trough

    path mentioned above, and also over a long-range path between Cyprus and the UK.

    e The effect of changes in the levels of ionospheric disturbances on the operational availability at various

    data throughput rates has been examined for the trough path mentioned earlier.

    The topics covered in this paper are necessarily brief, and the reader is referred to full papers referenced


  15. Deep level centers in electron-irradiated silicon crystals doped with copper at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yarykin, Nikolai [Institute of Microelectronics Technology, RAS, Chernogolovka (Russian Federation); Weber, Joerg [Technische Universitaet Dresden (Germany)

    2017-07-15

    The effect of bombardment with energetic particles on the deep-level spectrum of copper-contaminated silicon wafers is studied by space charge spectroscopy methods. The p-type FZ-Si wafers were doped with copper in the temperature range of 645-750 C and then irradiated with the 10{sup 15} cm{sup -2} fluence of 5 MeV electrons at room temperature. Only the mobile Cu{sub i} species and the Cu{sub PL} centers are detected in significant concentrations in the non-irradiated Cu-doped wafers. The properties of the irradiated samples are found to qualitatively depend on the copper in-diffusion temperature T{sub diff}. For T{sub diff} > 700 C, the irradiation partially reduces the Cu{sub i} concentration and introduces additional Cu{sub PL} centers while no standard radiation defects are detected. If T{sub diff} was below ∝700 C, the irradiation totally removes the mobile Cu{sub i} species. Instead, the standard radiation defects and their complexes with copper appear in the deep-level spectrum. A model for the defects reaction scheme during the irradiation is derived and discussed. DLTS spectrum of the Cu-contaminated and then irradiated silicon qualitatively depends on the copper in-diffusion temperature. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Transionospheric propagation predictions

    Science.gov (United States)

    Klobucher, J. A.; Basu, S.; Basu, S.; Bernhardt, P. A.; Davies, K.; Donatelli, D. E.; Fremouw, E. J.; Goodman, J. M.; Hartmann, G. K.; Leitinger, R.

    1979-01-01

    The current status and future prospects of the capability to make transionospheric propagation predictions are addressed, highlighting the effects of the ionized media, which dominate for frequencies below 1 to 3 GHz, depending upon the state of the ionosphere and the elevation angle through the Earth-space path. The primary concerns are the predictions of time delay of signal modulation (group path delay) and of radio wave scintillation. Progress in these areas is strongly tied to knowledge of variable structures in the ionosphere ranging from the large scale (thousands of kilometers in horizontal extent) to the fine scale (kilometer size). Ionospheric variability and the relative importance of various mechanisms responsible for the time histories observed in total electron content (TEC), proportional to signal group delay, and in irregularity formation are discussed in terms of capability to make both short and long term predictions. The data base upon which predictions are made is examined for its adequacy, and the prospects for prediction improvements by more theoretical studies as well as by increasing the available statistical data base are examined.

  17. An Application of Fuzzy Theory to Technical Competency Analysis for the Entry-Level Electronic Technician.

    Science.gov (United States)

    Chang, Liang-Te; And Others

    A study was conducted to develop the electronic technical competencies of duty and task analysis by using a revised DACUM (Developing a Curriculum) method, a questionnaire survey, and a fuzzy synthesis operation. The revised DACUM process relied on inviting electronics trade professionals to analyze electronic technology for entry-level…

  18. ACTS Propagation Measurements in Maryland and Virginia

    Science.gov (United States)

    Dissanayake, Asoka; Lin, Kuan-Ting

    1996-01-01

    Rapid growth in new satellite services incorporating very small aperture terminals (VSAT) and ultra small aperture terminals (USAT) is expected in the coming years. Small size terminals allow for widespread use of satellite services in small business and domestic applications. Due to congestion of lower frequency bands such as C and Ku, most of these services will use Ka-band (2/20 GHz) frequencies. Propagation impairments produced by the troposphere is a limiting factor for the effective use of the 20/30 GHz band and the use of smaller Earth terminals makes it difficult to provide sufficient link margins for propagation related outages. In this context, reliable prediction of propagation impairments for low margin systems becomes important. Due to the complexity of propagation phenomena propagation modeling is mainly attempted on an empirical basis. As such, the availability of reliable measured data that extend to probability levels well in excess of the traditional limit of 1 percent is of great importance in the development, validation, and refinement of propagation models. The beacon payload on the Advanced Communications Technology Satellite (ACTS) together with the propagation measurement terminals developed under the NASA ACTS propagation program provide an excellent opportunity to collect such data on a long-term basis. This paper presents the results of ACTS propagation measurements conducted in the Washington, DC metropolitan area by COMSAT Laboratories.

  19. Evaluation of alanine as a reference dosimeter for therapy level dose comparisons in megavoltage electron beams

    International Nuclear Information System (INIS)

    McEwen, Malcolm; Sharpe, Peter; Voros, Sandor

    2015-01-01

    When comparing absorbed dose standards from different laboratories (e.g. National Measurement Institutes, NMIs, for Key or Supplementary comparisons) it is rarely possible to carry out a direct comparison of primary standard instruments, and therefore some form of transfer detector is required. Historically, air-filled, unsealed ionization chambers have been used because of the long history of using these instruments, very good stability over many years, and ease of transport. However, the use of ion chambers for therapy-level comparisons is not without its problems. Findings from recent investigations suggest that ion chambers are prone to non-random variations, they are not completely robust to standard courier practices, and failure at any step in a comparison can render all measurements potentially useless. An alternative approach is to identify a transfer system that is insensitive to some of these concerns - effectively a dosimeter that is inexpensive, simple to use, robust, but with sufficient precision and of a size relevant to the disseminated quantity in question. The alanine dosimetry system has been successfully used in a number of situations as an audit dosimeter and therefore the purpose of this investigation was to determine whether alanine could also be used as the transfer detector for dosimetric comparisons, which require a lower value for the measurement uncertainty. A measurement protocol was developed for comparing primary standards of absorbed dose to water in high-energy electron beams using alanine pellets irradiated in a water-equivalent plastic phantom. A trial comparison has been carried out between three NMIs and has indicated that alanine is a suitable alternative to ion chambers, with the system used achieving a precision of 0.1%. Although the focus of the evaluation was on the performance of the dosimeter, the comparison results are encouraging, showing agreement at the level of the combined uncertainties (∼0.6%). Based on this

  20. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  1. Modelling the gluon propagator

    Energy Technology Data Exchange (ETDEWEB)

    Leinweber, D.B.; Parrinello, C.; Skullerud, J.I.; Williams, A.G

    1999-03-01

    Scaling of the Landau gauge gluon propagator calculated at {beta} = 6.0 and at {beta} = 6.2 is demonstrated. A variety of functional forms for the gluon propagator calculated on a large (32{sup 3} x 64) lattice at {beta} = 6.0 are investigated.

  2. Sound propagation in cities

    NARCIS (Netherlands)

    Salomons, E.; Polinder, H.; Lohman, W.; Zhou, H.; Borst, H.

    2009-01-01

    A new engineering model for sound propagation in cities is presented. The model is based on numerical and experimental studies of sound propagation between street canyons. Multiple reflections in the source canyon and the receiver canyon are taken into account in an efficient way, while weak

  3. Level-set segmentation of pulmonary nodules in megavolt electronic portal images using a CT prior

    International Nuclear Information System (INIS)

    Schildkraut, J. S.; Prosser, N.; Savakis, A.; Gomez, J.; Nazareth, D.; Singh, A. K.; Malhotra, H. K.

    2010-01-01

    Purpose: Pulmonary nodules present unique problems during radiation treatment due to nodule position uncertainty that is caused by respiration. The radiation field has to be enlarged to account for nodule motion during treatment. The purpose of this work is to provide a method of locating a pulmonary nodule in a megavolt portal image that can be used to reduce the internal target volume (ITV) during radiation therapy. A reduction in the ITV would result in a decrease in radiation toxicity to healthy tissue. Methods: Eight patients with nonsmall cell lung cancer were used in this study. CT scans that include the pulmonary nodule were captured with a GE Healthcare LightSpeed RT 16 scanner. Megavolt portal images were acquired with a Varian Trilogy unit equipped with an AS1000 electronic portal imaging device. The nodule localization method uses grayscale morphological filtering and level-set segmentation with a prior. The treatment-time portion of the algorithm is implemented on a graphical processing unit. Results: The method was retrospectively tested on eight cases that include a total of 151 megavolt portal image frames. The method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases. The treatment phase portion of the method has a subsecond execution time that makes it suitable for near-real-time nodule localization. Conclusions: A method was developed to localize a pulmonary nodule in a megavolt portal image. The method uses the characteristics of the nodule in a prior CT scan to enhance the nodule in the portal image and to identify the nodule region by level-set segmentation. In a retrospective study, the method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases studied.

  4. Heat and density pulse propagation in ASDEX

    International Nuclear Information System (INIS)

    Giannone, L.; Riedl, K.; Stroth, U.; Eberhagen, A.; Gruber, O.; Mertens, V.

    1990-01-01

    Experimental measurements of the electron thermal conductivity, derived from the radial propagation of the heat pulse generated by a sawtooth crash, have consistently yielded larger values than those obtained by power balance. It has been proposed that this discrepancy could be the result of the coupling of density and temperature perturbations. Numerical modelling of heat and density pulse propagation on ASDEX has been used to address this question. In addition, measurements at various electron densities and in hydrogen and deuterium were undertaken, with the aim of providing a broad base of experimental measurements for testing the various transport models proposed. (author) 9 refs., 1 fig

  5. Heat and density pulse propagation in ASDEX

    International Nuclear Information System (INIS)

    Giannone, L.; Riedel, K.; Stroth, U.; Eberhagen, A.; Gruber, O.; Mertens, V.

    1990-01-01

    Experimental measurements of the electron thermal conductivity, derived from the radial propagation of the heat pulse generated by a sawtooth crash, have consistently yielded larger values than those obtained by power balance. It has been proposed that this discrepancy could be the result of the coupling of density and temperature perturbations. Numerical modelling of heat and density pulse propagation on ASDEX has been used to address this question. In addition, measurements at various electron densities and in hydrogen and deuterium were undertaken, with the aim of providing a broad base of experimental measurements for testing the various transport models proposed. (orig.)

  6. Lessons learned from positron-electron project low level rf and longitudinal feedback

    Directory of Open Access Journals (Sweden)

    J. Fox

    2010-05-01

    Full Text Available The Positron-Electron Project II (PEP-II B Factory collider ended the final phase of operation at nearly twice the design current and 4X the design luminosity. In the ultimate operation state, eight 1.2 MW radio-frequency (rf klystrons and 12 accelerating cavities were added beyond the original implementation, and the two storage rings were operating with longitudinal instability growth rates roughly 5X in excess of the original design estimates. From initial commissioning there has been continual adaptation of the low level rf (LLRF control strategies, configuration tools, and some new hardware in response to unanticipated technical challenges. This paper offers a perspective on the original LLRF and longitudinal instability control design, and highlights via two examples the system evolution from the original design estimates through to the final machine with 1.2×10^{34} luminosity. The impact of unanticipated signals in the coupled-bunch longitudinal feedback and the significance of nonlinear processing elements in the LLRF systems are presented. We present valuable “lessons learned” which are of interest to designers of next generation feedback and impedance controlled LLRF systems.

  7. The role of secondary electrons in some experiments determining fluorescence emission from nitrogen C3Πu levels

    International Nuclear Information System (INIS)

    Blanco, F.; Arqueros, F.

    2005-01-01

    The processes involved in fluorescence emission from C 3 Π u levels of N 2 molecule by electron impact are studied. Secondary electrons are shown to play an important role in typical experiments for the measurement of emission cross sections and fluorescence yields, dominating at high impact energies. A simple model is proposed which accounts for fluorescence measurements in a wide range of experimental conditions, and in particular for some recent results up to 1 GeV energies

  8. Line radiation of multicharged ions with the Fermi-Dirac level distribution of electrons at high temperatures

    International Nuclear Information System (INIS)

    Garanin, S.F.

    2003-01-01

    Line radiation of multicharged ions with the Fermi-Dirac electron distribution by levels in the range of plasma temperatures, when electron movement may be considered quasiclassical, while potential, in which they move, is the Coulomb one, is considered. The spectrum and intensity of ion radiation are calculated. Within high plasma densities the radiation intensity per one ion proved to be independent of density and proportional to T 2 [ru

  9. Excess-electron energy levels, localization and transport in disordered media

    International Nuclear Information System (INIS)

    Hamill, W.H.

    1980-01-01

    In disordered dielectrics, the fundamental parameters which control the physics and chemistry of excess electrons are time, temperature and energy or mean scattering distance. Viscosity and hardness do not directly affect the electron affinity of media, the optical spectra, or the chemical reactivity of dry or delocalized electrons or of relaxed localized or trapped electrons. Since the mean scattering distance and the transport mechanism, including barrier height, are fundamental, both liquids and glasses (including polymers) are considered in order to cover the range of relevant information. Based on the above described background, transport, localization, dry electron scavenging, trapped electron scavenging and recombination are explained. There are no available data for the energy of excess dry electrons in the media relative to vacuum in glasses, unfortunately, because of the very small yield of separated charge pairs at cryogenic temperature. Thermoplastic glassy solids provide attractive possibility above 250 K, and deserve consideration as the substitutes for cryogenic glasses. The same consideration applies to the measurements of electron drift mobility, which are essential for the adequate description of electron scavenging. (Wakatsuki, Y.)

  10. Heterogeneous Electronics – Wafer Level Integration, Packaging, and Assembly Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This facility integrates active electronics with microelectromechanical (MEMS) devices at the miniature system scale. It obviates current size-, weight-, and power...

  11. Determination of the electronic energy levels of colloidal nanocrystals using field-effect transistors and Ab-initio calculations.

    Science.gov (United States)

    Bisri, Satria Zulkarnaen; Degoli, Elena; Spallanzani, Nicola; Krishnan, Gopi; Kooi, Bart Jan; Ghica, Corneliu; Yarema, Maksym; Heiss, Wolfgang; Pulci, Olivia; Ossicini, Stefano; Loi, Maria Antonietta

    2014-08-27

    Colloidal nanocrystals electronic energy levels are determined by strong size-dependent quantum confinement. Understanding the configuration of the energy levels of nanocrystal superlattices is vital in order to use them in heterostructures with other materials. A powerful method is reported to determine the energy levels of PbS nanocrystal assemblies by combining the utilization of electric-double-layer-gated transistors and advanced ab-initio theory. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Edge State Propagation Direction in the Fractional Quantum Hall Regime: Multi-Terminal Magnetocapacitance Experiment

    International Nuclear Information System (INIS)

    JOHNSON, B.L.; MOON, JEONG-SUN; RENO, JOHN L.; SIMMONS, JERRY A.

    1999-01-01

    The propagation direction of fractional quantum Hall effect (FQHE) edge states has been investigated experimentally via the symmetry properties of the multi-terminal capacitances of a two dimensional electron gas. Although strong asymmetries with respect to zero magnetic field appear, no asymmetries with respect to even denominator Landau level filling factor ν are seen. This indicates that current-carrying FQHE edge states propagate in the same direction as integer QHE edge states. In addition, anomalous capacitance features, indicative of enhanced bulk conduction, are observed at ν = 1/2 and 3/2

  13. High speed bending of 2nd level interconnects on printed circuit boards for automotive electronics

    NARCIS (Netherlands)

    Kouters, M.H.M.; Ubachs, R.; Wiel, H.J. van de; Waal, A. van der; Veer, J. van der

    2011-01-01

    Standard drop tests for portable electronics are not representative for the qualification of automotive electronics. High-frequency vibrations are more dominant than abrupt shocks during normal operation. In this work a high speed board bending (HSB) method is developed to mimic the constant cyclic

  14. Board Level Proton Testing Book of Knowledge for NASA Electronic Parts and Packaging Program

    Science.gov (United States)

    Guertin, Steven M.

    2017-01-01

    This book of knowledge (BoK) provides a critical review of the benefits and difficulties associated with using proton irradiation as a means of exploring the radiation hardness of commercial-off-the-shelf (COTS) systems. This work was developed for the NASA Electronic Parts and Packaging (NEPP) Board Level Testing for the COTS task. The fundamental findings of this BoK are the following. The board-level test method can reduce the worst case estimate for a board's single-event effect (SEE) sensitivity compared to the case of no test data, but only by a factor of ten. The estimated worst case rate of failure for untested boards is about 0.1 SEE/board-day. By employing the use of protons with energies near or above 200 MeV, this rate can be safely reduced to 0.01 SEE/board-day, with only those SEEs with deep charge collection mechanisms rising this high. For general SEEs, such as static random-access memory (SRAM) upsets, single-event transients (SETs), single-event gate ruptures (SEGRs), and similar cases where the relevant charge collection depth is less than 10 µm, the worst case rate for SEE is below 0.001 SEE/board-day. Note that these bounds assume that no SEEs are observed during testing. When SEEs are observed during testing, the board-level test method can establish a reliable event rate in some orbits, though all established rates will be at or above 0.001 SEE/board-day. The board-level test approach we explore has picked up support as a radiation hardness assurance technique over the last twenty years. The approach originally was used to provide a very limited verification of the suitability of low cost assemblies to be used in the very benign environment of the International Space Station (ISS), in limited reliability applications. Recently the method has been gaining popularity as a way to establish a minimum level of SEE performance of systems that require somewhat higher reliability performance than previous applications. This sort of application of

  15. Multi-level analysis of electronic health record adoption by health care professionals: A study protocol

    Directory of Open Access Journals (Sweden)

    Labrecque Michel

    2010-04-01

    Full Text Available Abstract Background The electronic health record (EHR is an important application of information and communication technologies to the healthcare sector. EHR implementation is expected to produce benefits for patients, professionals, organisations, and the population as a whole. These benefits cannot be achieved without the adoption of EHR by healthcare professionals. Nevertheless, the influence of individual and organisational factors in determining EHR adoption is still unclear. This study aims to assess the unique contribution of individual and organisational factors on EHR adoption in healthcare settings, as well as possible interrelations between these factors. Methods A prospective study will be conducted. A stratified random sampling method will be used to select 50 healthcare organisations in the Quebec City Health Region (Canada. At the individual level, a sample of 15 to 30 health professionals will be chosen within each organisation depending on its size. A semi-structured questionnaire will be administered to two key informants in each organisation to collect organisational data. A composite adoption score of EHR adoption will be developed based on a Delphi process and will be used as the outcome variable. Twelve to eighteen months after the first contact, depending on the pace of EHR implementation, key informants and clinicians will be contacted once again to monitor the evolution of EHR adoption. A multilevel regression model will be applied to identify the organisational and individual determinants of EHR adoption in clinical settings. Alternative analytical models would be applied if necessary. Results The study will assess the contribution of organisational and individual factors, as well as their interactions, to the implementation of EHR in clinical settings. Conclusions These results will be very relevant for decision makers and managers who are facing the challenge of implementing EHR in the healthcare system. In addition

  16. PyNCS: a microkernel for high-level definition and configuration of neuromorphic electronic systems

    Directory of Open Access Journals (Sweden)

    Fabio eStefanini

    2014-08-01

    Full Text Available Neuromorphic hardware offers an electronic substrate for the realization of asynchronousevent-based sensory-motor systems and large-scale spiking neural network architectures. Inorder to characterize these systems, configure them, and carry out modeling experiments, it isoften necessary to interface them to workstations. The software used for this purpose typicallyconsists of a large monolithic block of code highly specific to the hardware setup used. While thisapproach can lead to highly integrated hardware/software systems, it hampers the developmentof modular and neuromorphic infrastructures. To alleviate this problem, we propose PyNCS,an open-source front-end for the definition of neural network models that is interfaced to thehardware through a set of Python Application Programming Interfaces (APIs. The designof PyNCS promotes modularity, portability and expandability and separates implementationfrom hardware description. The high-level front-end that comes with PyNCS includes tools todefine neural network models as well as to create, monitor and analyze spiking data. Here wereport the design philosophy behind the PyNCS framework and describe its implementation.We demonstrate its functionality with two representative case studies, one using an event-based neuromorphic vision sensor, and one using a set of multi-neuron devices for carryingout a cognitive decision-making task involving state-dependent computation. PyNCS, alreadyapplicable to a wide range of existing spike-based neuromorphic setups, will accelerate thedevelopment of hybrid software/hardware neuromorphic systems, thanks to its code flexibility.The code developed is open-source and available online at https://github.com/inincs/pyNCS.

  17. PyNCS: a microkernel for high-level definition and configuration of neuromorphic electronic systems.

    Science.gov (United States)

    Stefanini, Fabio; Neftci, Emre O; Sheik, Sadique; Indiveri, Giacomo

    2014-01-01

    Neuromorphic hardware offers an electronic substrate for the realization of asynchronous event-based sensory-motor systems and large-scale spiking neural network architectures. In order to characterize these systems, configure them, and carry out modeling experiments, it is often necessary to interface them to workstations. The software used for this purpose typically consists of a large monolithic block of code which is highly specific to the hardware setup used. While this approach can lead to highly integrated hardware/software systems, it hampers the development of modular and reconfigurable infrastructures thus preventing a rapid evolution of such systems. To alleviate this problem, we propose PyNCS, an open-source front-end for the definition of neural network models that is interfaced to the hardware through a set of Python Application Programming Interfaces (APIs). The design of PyNCS promotes modularity, portability and expandability and separates implementation from hardware description. The high-level front-end that comes with PyNCS includes tools to define neural network models as well as to create, monitor and analyze spiking data. Here we report the design philosophy behind the PyNCS framework and describe its implementation. We demonstrate its functionality with two representative case studies, one using an event-based neuromorphic vision sensor, and one using a set of multi-neuron devices for carrying out a cognitive decision-making task involving state-dependent computation. PyNCS, already applicable to a wide range of existing spike-based neuromorphic setups, will accelerate the development of hybrid software/hardware neuromorphic systems, thanks to its code flexibility. The code is open-source and available online at https://github.com/inincs/pyNCS.

  18. PyNCS: a microkernel for high-level definition and configuration of neuromorphic electronic systems

    Science.gov (United States)

    Stefanini, Fabio; Neftci, Emre O.; Sheik, Sadique; Indiveri, Giacomo

    2014-01-01

    Neuromorphic hardware offers an electronic substrate for the realization of asynchronous event-based sensory-motor systems and large-scale spiking neural network architectures. In order to characterize these systems, configure them, and carry out modeling experiments, it is often necessary to interface them to workstations. The software used for this purpose typically consists of a large monolithic block of code which is highly specific to the hardware setup used. While this approach can lead to highly integrated hardware/software systems, it hampers the development of modular and reconfigurable infrastructures thus preventing a rapid evolution of such systems. To alleviate this problem, we propose PyNCS, an open-source front-end for the definition of neural network models that is interfaced to the hardware through a set of Python Application Programming Interfaces (APIs). The design of PyNCS promotes modularity, portability and expandability and separates implementation from hardware description. The high-level front-end that comes with PyNCS includes tools to define neural network models as well as to create, monitor and analyze spiking data. Here we report the design philosophy behind the PyNCS framework and describe its implementation. We demonstrate its functionality with two representative case studies, one using an event-based neuromorphic vision sensor, and one using a set of multi-neuron devices for carrying out a cognitive decision-making task involving state-dependent computation. PyNCS, already applicable to a wide range of existing spike-based neuromorphic setups, will accelerate the development of hybrid software/hardware neuromorphic systems, thanks to its code flexibility. The code is open-source and available online at https://github.com/inincs/pyNCS. PMID:25232314

  19. Heat pulse propagation studies in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, E.D.; Callen, J.D.; Colchin, R.J.; Efthimion, P.C.; Hill, K.W.; Izzo, R.; Mikkelsen, D.R.; Monticello, D.A.; McGuire, K.; Bell, J.D.

    1986-02-01

    The time scales for sawtooth repetition and heat pulse propagation are much longer (10's of msec) in the large tokamak TFTR than in previous, smaller tokamaks. This extended time scale coupled with more detailed diagnostics has led us to revisit the analysis of the heat pulse propagation as a method to determine the electron heat diffusivity, chi/sub e/, in the plasma. A combination of analytic and computer solutions of the electron heat diffusion equation are used to clarify previous work and develop new methods for determining chi/sub e/. Direct comparison of the predicted heat pulses with soft x-ray and ECE data indicates that the space-time evolution is diffusive. However, the chi/sub e/ determined from heat pulse propagation usually exceeds that determined from background plasma power balance considerations by a factor ranging from 2 to 10. Some hypotheses for resolving this discrepancy are discussed. 11 refs., 19 figs., 1 tab.

  20. Heat pulse propagation studies in TFTR

    International Nuclear Information System (INIS)

    Fredrickson, E.D.; Callen, J.D.; Colchin, R.J.

    1986-02-01

    The time scales for sawtooth repetition and heat pulse propagation are much longer (10's of msec) in the large tokamak TFTR than in previous, smaller tokamaks. This extended time scale coupled with more detailed diagnostics has led us to revisit the analysis of the heat pulse propagation as a method to determine the electron heat diffusivity, chi/sub e/, in the plasma. A combination of analytic and computer solutions of the electron heat diffusion equation are used to clarify previous work and develop new methods for determining chi/sub e/. Direct comparison of the predicted heat pulses with soft x-ray and ECE data indicates that the space-time evolution is diffusive. However, the chi/sub e/ determined from heat pulse propagation usually exceeds that determined from background plasma power balance considerations by a factor ranging from 2 to 10. Some hypotheses for resolving this discrepancy are discussed. 11 refs., 19 figs., 1 tab

  1. Interaction of electron irradiation with nitrogen-related deep levels in InGaAsN

    International Nuclear Information System (INIS)

    Khan, Aurangzeb; Gou, J.; Imazumi, M.; Yamaguchi, M.

    2007-01-01

    The authors present an investigation of 1 MeV electron irradiation-induced defects in p-InGaAsN and their impact on nitrogen-related defects. A hitherto existing nitrogen-related electron trap E1 (0.20 eV) shows a significant increase in concentration after 1 MeV electron irradiation. In addition, 1 MeV electron irradiation induced a hole trap H1 at energy of about 0.75 eV above the valence band. Isothermal annealing analysis indicates that E1 is a complex defect involving an interstitial or a substitutional atom in combination with some other defect, whose concentration is enhanced by irradiation. A correlation exists between the recovery of free carrier concentration and recovery of the E1 center to preradiation concentrations, which indicates the possibility of the E1 as an acceptorlike center

  2. Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Duc, Tran Thien [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi (Viet Nam); Pozina, Galia; Son, Nguyen Tien; Kordina, Olof; Janzén, Erik; Hemmingsson, Carl [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); Ohshima, Takeshi [Japan Atomic Energy Agency (JAEA), Takasaki, Gunma 370-1292 (Japan)

    2016-03-07

    Development of high performance GaN-based devices is strongly dependent on the possibility to control and understand defects in material. Important information about deep level defects is obtained by deep level transient spectroscopy and minority carrier transient spectroscopy on as-grown and electron irradiated n-type bulk GaN with low threading dislocation density produced by halide vapor phase epitaxy. One hole trap labelled H1 (E{sub V} + 0.34 eV) has been detected on as-grown GaN sample. After 2 MeV electron irradiation, the concentration of H1 increases and at fluences higher than 5 × 10{sup 14 }cm{sup −2}, a second hole trap labelled H2 is observed. Simultaneously, the concentration of two electron traps, labelled T1 (E{sub C} – 0.12 eV) and T2 (E{sub C} – 0.23 eV), increases. By studying the increase of the defect concentration versus electron irradiation fluence, the introduction rate of T1 and T2 using 2 MeV- electrons was determined to be 7 × 10{sup −3 }cm{sup −1} and 0.9 cm{sup −1}, respectively. Due to the low introduction rate of T1, it is suggested that the defect is associated with a complex. The high introduction rate of trap H1 and T2 suggests that the defects are associated with primary intrinsic defects or complexes. Some deep levels previously observed in irradiated GaN layers with higher threading dislocation densities are not detected in present investigation. It is therefore suggested that the absent traps may be related to primary defects segregated around dislocations.

  3. Awareness and Use of Electronic Health Records in Entry-Level Occupational Therapy and Occupational Therapy Assistant Curricula

    Directory of Open Access Journals (Sweden)

    Louis F. Dmytryk

    2017-03-01

    Full Text Available The Accreditation Council for Occupational Therapy Education (ACOTE requires programs to instruct entrylevel occupational therapy (OT and occupational therapy assistant (OTA students in technology that may include electronic documentation systems, distance communication, virtual environments, and telehealth (standard B1.8. At this time, there are no publications describing if and how electronic health record (EHR instruction is implemented in entry-level OT and OTA programs. The purpose of this study is to investigate awareness and use of EHRs in entry-level OT and OTA curricula. Respondents from 76 nationally accredited entry-level programs (two OT doctoral, 24 OT masters, two OT combined bachelors/masters, and 48 OTA completed a survey. The findings showed inconsistent and incomplete EHR instruction in entry-level OT and OTA education. This study provides a baseline for investigating best practices in EHR education for entrylevel OT and OTA students

  4. Database for propagation models

    Science.gov (United States)

    Kantak, Anil V.

    1991-07-01

    A propagation researcher or a systems engineer who intends to use the results of a propagation experiment is generally faced with various database tasks such as the selection of the computer software, the hardware, and the writing of the programs to pass the data through the models of interest. This task is repeated every time a new experiment is conducted or the same experiment is carried out at a different location generating different data. Thus the users of this data have to spend a considerable portion of their time learning how to implement the computer hardware and the software towards the desired end. This situation may be facilitated considerably if an easily accessible propagation database is created that has all the accepted (standardized) propagation phenomena models approved by the propagation research community. Also, the handling of data will become easier for the user. Such a database construction can only stimulate the growth of the propagation research it if is available to all the researchers, so that the results of the experiment conducted by one researcher can be examined independently by another, without different hardware and software being used. The database may be made flexible so that the researchers need not be confined only to the contents of the database. Another way in which the database may help the researchers is by the fact that they will not have to document the software and hardware tools used in their research since the propagation research community will know the database already. The following sections show a possible database construction, as well as properties of the database for the propagation research.

  5. Lifetimes of some 4p levels of Ne I obtained by two-step (electron-photon) excitation

    International Nuclear Information System (INIS)

    Ortiz, M.; Garcia, G.; Blanco, F.; Campos, J.

    1990-01-01

    Radiative lifetimes of some levels belonging to 2p 5 4p configuration of Ne I have been determined using electron excitation followed by selective laser excitation. The experimental results of this work are 123.8±3.6 ns, 120.3±2.8 ns and 135.9±4.5 ns for the 4p'(3/2) 1 , 4p'(1/2) 1 and 4p(5/2) 2 levels respectively. (orig.)

  6. Charge deep-level transient spectroscopy study of high-energy-electron-beam-irradiated hydrogenated amorphous silicon

    NARCIS (Netherlands)

    Klaver, A.; Nádaždy, V.; Zeman, M.; Swaaiij, R.A.C.M.M.

    2006-01-01

    We present a study of changes in the defect density of states in hydrogenated amorphous silicon (a-Si:H) due to high-energy electron irradiation using charged deep-level transient spectroscopy. It was found that defect states near the conduction band were removed, while in other band gap regions the

  7. Electronics for CMS Endcap Muon Level-1 Trigger System Phase-1 and HL LHC upgrades

    Science.gov (United States)

    Madorsky, A.

    2017-07-01

    To accommodate high-luminosity LHC operation at a 13 TeV collision energy, the CMS Endcap Muon Level-1 Trigger system had to be significantly modified. To provide robust track reconstruction, the trigger system must now import all available trigger primitives generated by the Cathode Strip Chambers and by certain other subsystems, such as Resistive Plate Chambers (RPC). In addition to massive input bandwidth, this also required significant increase in logic and memory resources. To satisfy these requirements, a new Sector Processor unit has been designed. It consists of three modules. The Core Logic module houses the large FPGA that contains the track-finding logic and multi-gigabit serial links for data exchange. The Optical module contains optical receivers and transmitters; it communicates with the Core Logic module via a custom backplane section. The Pt Lookup table (PTLUT) module contains 1 GB of low-latency memory that is used to assign the final Pt to reconstructed muon tracks. The μ TCA architecture (adopted by CMS) was used for this design. The talk presents the details of the hardware and firmware design of the production system based on Xilinx Virtex-7 FPGA family. The next round of LHC and CMS upgrades starts in 2019, followed by a major High-Luminosity (HL) LHC upgrade starting in 2024. In the course of these upgrades, new Gas Electron Multiplier (GEM) detectors and more RPC chambers will be added to the Endcap Muon system. In order to keep up with all these changes, a new Advanced Processor unit is being designed. This device will be based on Xilinx UltraScale+ FPGAs. It will be able to accommodate up to 100 serial links with bit rates of up to 25 Gb/s, and provide up to 2.5 times more logic resources than the device used currently. The amount of PTLUT memory will be significantly increased to provide more flexibility for the Pt assignment algorithm. The talk presents preliminary details of the hardware design program.

  8. Cross sections of electron excitation out of metastable helium levels with a fast metastable target product produced via charge exchange

    International Nuclear Information System (INIS)

    Lagus, M.E.; Boffard, J.B.; Anderson, L.W.; Lin, C.C.

    1996-01-01

    Absolute direct cross sections for electron excitation out of the 2 3 S level and into the 3 3 D, 4 3 D, and 3 3 S levels of the helium atom from threshold to 500 eV and into the 3 3 P level over a more limited energy range have been measured using a fast metastable atomic beam target. We produce the metastable atoms via near-resonant charge exchange between a 1.6-keV He + ion beam and Cs vapor. Because this reaction is highly nonresonant with the ground state of helium, the charge-transfer process yields a primarily metastable beam. We use a thermal detector which we calibrate with ions to measure absolutely the neutral beam flux. The atomic beam is crossed by an electron beam, and we collect the resulting fluorescence at right angles to both the electron and atomic beams. We obtain the cross sections for excitation out of the 2 3 S level into the various excited levels by monitoring the emission out of the excited level of interest. copyright 1996 The American Physical Society

  9. Dynamic simulation of charging processes in polar dielectrics irradiated by the electron bunches of middle level energy

    International Nuclear Information System (INIS)

    Maslovskaya, A.G.

    2011-01-01

    Nowadays the scanning electron microscopy techniques are widely used practically in condenser matter physics to study properties and structure of solids. The electron probe of scanning electron microscope is not merely a passive indicator of the geometrical or potential profile of the sample surface, but also the source producing ionizing, electric and thermal action on the sample. The application of raster electron methods to polar materials, responding to electric and heat exposures of the electron bunches allows us to get a response and create new modes of image formation. Let assume, that a sample surface of dielectric is irradiated by thin focused electron bunches of middle level energy (with order 1÷50 keV). When electrons bombard the dielectric sample the accumulation of absorbed electrons occurs. As a result generated charged areas can irregular drift the initial bunches. Charging effect occurs at any magnifications and any actual probe current. This work considers the results of dynamic simulation of charging process in polar dielectrics under the investigation with the scanning electron microscope. The purpose of present study is design and model implementation of three-dimensional dynamic model of charge relaxation in polar materials irradiated by electron bunches of middle level energy. The mathematical problem definition is given by the system of the continuity equation and Poisson equation. Final system of equations was modified in terms of intrinsic radiation-induced conductivity in sample as well as cylindrical symmetry of the problem. The simulation is based on numerical method solving of boundary problem for partial derivative equation system. In addition the initial electron distribution is determined by Monte-Carlo method using the programming implementation. To solve this problem we used the computational methods of solution of nonstationary mathematical physics problem such as finite difference method and finite element method realized with

  10. Data analysis at the CMS level-1 trigger: migrating complex selection algorithms from offline analysis and high-level trigger to the trigger electronics

    CERN Document Server

    Wulz, Claudia

    2017-01-01

    With ever increasing luminosity at the LHC, optimum online data selection is becoming more and more important. While in the case of some experiments (LHCb and ALICE) this task is being completely transferred to computer farms, the others -- ATLAS and CMS -- will not be able to do this in the medium-term future for technological, detector-related reasons. Therefore, these experiments pursue the complementary approach of migrating more and more of the offline and high-level trigger intelligence into the trigger electronics. The presentation illustrates how the level-1 trigger of the CMS experiment and in particular its concluding stage, the so-called ``Global Trigger", take up this challenge.

  11. The quark propagator in a covariant gauge

    International Nuclear Information System (INIS)

    Bonnet, F.D.R.; Leinweber, D.B.; Williams, A.G.; Zanotti, J.M.

    2000-01-01

    Full text: The quark propagator is one of the fundamental building blocks of QCD. Results strongly depend on the ansatz for the propagator. Direct simulations of QCD on a space time lattice can provide guidance and constraints on the analytic structure of the quark propagator. On the lattice the infrared and asymptotic behaviour of the quark propagator is of particular interest since it is a reflection of the accuracy of the discretised quark action. In the deep infrared region, artefacts associated with the finite size of the lattice spacing become small. This is the most interesting region as nonperturbative physics lies here. However, the ultraviolet behaviour at large momentum of the propagator will in general strongly deviate from the correct continuum behaviour. This behaviour will be action dependent. Some interesting progress has been made in improving the ultraviolet behaviour of the propagator. A method, recently developed and referred to as tree-level correction, consists of using the knowledge of the tree-level behaviour to eliminate the obvious lattice artefacts. Tree-level correction represents a crucial step in extracting meaningful results for the mass function and the renormalisation function outside of the deep infrared region. The mass function is particularly interesting as it provides insights into the constituent quark mass as a measure of the nonperturbative physics. In this poster I will present results from the analytic structure of the propagator in recent lattice studies for a variety of fermion actions in lattice QCD. I will also present the new ratio method used to tree-level correct these quark propagators

  12. Radial propagation of turbulence in tokamaks

    International Nuclear Information System (INIS)

    Garbet, X.; Laurent, L.; Samain, A.

    1993-12-01

    It is shown in this paper that a turbulence propagation can be due to toroidal or non linear mode coupling. An analytical analysis indicates that the toroidal coupling acts through a convection while the non linear effects induce a diffusion. Numerical simulations suggest that the toroidal propagation is usually the fastest process, except perhaps in some highly turbulent regimes. The consequence is the possibility of non local effects on the fluctuation level and the associated transport. (authors). 7 figs., 19 refs

  13. Low energy electron irradiation induced deep level defects in 6H-SiC: The implication for the microstructure of the deep levels E1/E2

    International Nuclear Information System (INIS)

    Chen, X.D.; Fung, S.; Beling, C.D.; Lui, M.K.; Ling, C.C.; Yang, C.L.; Ge, W.K.; Wang, J.N.; Gong, M.

    2004-01-01

    N-type 6H-SiC samples irradiated with electrons having energies of E e =0.2, 0.3, 0.5, and 1.7 were studied by deep level transient technique. No deep level was detected at below 0.2 MeV irradiation energy while for E e ≥0.3 MeV, deep levels ED1, E 1 /E 2 , and E i appeared. By considering the minimum energy required to displace the C atom or the Si atom in the SiC lattice, it is concluded that generation of the deep levels E 1 /E 2 , as well as ED1 and E i , involves the displacement of the C atom in the SiC lattice

  14. Investigation of energy levels of Er-impurity centers in Si by the method of ballistic electron emission spectroscopy

    International Nuclear Information System (INIS)

    Filatov, D. O.; Zimovets, I. A.; Isakov, M. A.; Kuznetsov, V. P.; Kornaukhov, A. V.

    2011-01-01

    The method of ballistic electron emission spectroscopy is used for the first time to study the energy spectrum of Er-impurity complexes in Si. The features are observed in the ballistic electron spectra of mesa diodes based on p + -n + Si structures with a thin (∼30 nm) p + -Si:Er surface layer in the region of ballistic-electron energies eV t lower than the conduction-band-edge energy E c in this layer. They are associated with the tunnel injection of ballistic electrons from the probe of the scanning tunnel microscope to the deep donor levels of the Er-impurity complexes in the p + -Si:Er layer with subsequent thermal excitation into the conduction band and the diffusion to the p + -n + junction and the direct tunneling in it. To verify this assumption, the ballistic-electron transport was simulated in the system of the Pt probe, native-oxide layer SiO 2 -p + -Si:Er-n + , and Si substrate. By approximating the experimental ballistic-electron spectra with the modeling spectra, the ground-state energy of the Er complex in Si was determined: E d ≈ E c − 0.27 eV. The indicated value is consistent with the data published previously and obtained from the measurements of the temperature dependence of the free-carrier concentration in Si:Er layers.

  15. Electron-impact excitation cross sections of the higher argon 3p5np (n=5,6,7) levels

    International Nuclear Information System (INIS)

    Weber, Tobin; Boffard, John B.; Lin, Chun C.

    2003-01-01

    We have measured the electron-impact excitation cross sections for argon into the ten levels of 3p 5 5p configuration, as well as numerous levels of the 3p 5 6p and 3p 5 7p configurations. Fluorescence from the decay of the excited atoms to the levels of 3p 5 4s configuration was used to determine the optical-emission cross sections. These results were combined with transition probabilities to find apparent cross sections into the 3p 5 5p and 3p 5 6p levels. These new cross sections of the Ar(3p 5 np) levels along with the available Ne(2p 5 3p), Kr(4p 5 5p), and Xe(5p 5 6p) data help provide a global view of the excitation behaviors of the np 5 n ' p levels of the rare-gas series

  16. Probing Electron-Induced Bond Cleavage at the Single-Molecule Level Using DNA Origami Templates

    DEFF Research Database (Denmark)

    Keller, Adrian Clemens; Bald, Ilko; Rotaru, Alexandru

    2012-01-01

    Low-energy electrons (LEEs) play an important role in nanolithography, atmospheric chemistry, and DNA radiation damage. Previously, the cleavage of specific chemical bonds triggered by LEEs has been demonstrated in a variety of small organic molecules such as halogenated benzenes and DNA nucleoba...

  17. Application of electron spin resonance for evaluation of the level of ...

    Indian Academy of Sciences (India)

    Abstract. In order to identify and quantify free radicals in the tissues of patients with normal physiological and pathological states of births, we developed a method to evaluate the amount of free radicals in myometrium of subplacental area and from body of uterus, using electron spin resonance spectroscopy. Analysis of the ...

  18. Electronic structure of copper phthalocyanine : An experimental and theoretical study of occupied and unoccupied levels

    NARCIS (Netherlands)

    Evangelista, Fabrizio; Carravetta, Vincenzo; Stefani, Giovanni; Jansik, Branislav; Alagia, Michele; Stranges, Stefano; Ruocco, Alessandro

    2007-01-01

    An experimental and theoretical study of the electronic structure of copper phthalocyanine (CuPc) molecule is presented. We performed x-ray photoemission spectroscopy (XPS) and photoabsorption [x-ray absorption near-edge structure (XANES)] gas phase experiments and we compared the results with

  19. Electricity consumption by battery-powered consumer electronics: A household-level survey

    International Nuclear Information System (INIS)

    McAllister, J. Andrew; Farrell, Alexander E.

    2007-01-01

    The rapid proliferation of battery-powered consumer electronics and their reliance on inefficient linear transformers has been suggested to be an important part of the rapid growth in 'miscellaneous' electricity consumption in recent years, but detailed data are scarce. We conducted a survey of 34 randomly selected households (HHs) in Northern California about the number, type, and usage of consumer electronics. We also measured the energy consumption of 85 typical consumer electronic devices through various parts of the charge cycle. These primary data were supplemented by national sales information for consumer electronics. Results indicate that typical HHs own 8.4 rechargeable devices, which have a total average demand of 12-17 W per HH. Statewide, this amounts to 160-220 MW of demand, with the peak occurring in the late evening, and about 1600 GWh per year. Only about 15% of this energy is used for battery charging, the rest is lost as waste heat during no-load and charge maintenance periods. Technical options to increase the efficiency of these devices, and the research and policy steps needed to realize these savings are discussed

  20. 199 An X-Ray of the Level of Electronic Purse Usage in Nigeria (Pp ...

    African Journals Online (AJOL)

    User

    2010-06-10

    Jun 10, 2010 ... enables the offering of financial services through the electronic media to .... Furthermore, Yang et al (2009) presents a comparative study about the issues ... relationship between the service quality and user input factor dimensions and ..... September 2002, at the Golden Gate Restaurant, Ikoyi, Lagos.

  1. Associations of Electronic Cigarette Nicotine Concentration With Subsequent Cigarette Smoking and Vaping Levels in Adolescents.

    Science.gov (United States)

    Goldenson, Nicholas I; Leventhal, Adam M; Stone, Matthew D; McConnell, Rob S; Barrington-Trimis, Jessica L

    2017-12-01

    Research indicates that electronic cigarette (e-cigarette) use (vaping) among adolescents is associated with the initiation and progression of combustible cigarette smoking. The reasons for this association are unknown. To evaluate whether use of e-cigarettes with higher nicotine concentrations is associated with subsequent increases in the frequency and intensity of combustible cigarette smoking and vaping. In this prospective cohort study involving students from 10 high schools in the Los Angeles, California, metropolitan area, surveys were administered during 10th grade in the spring (baseline) and 11th grade in the fall (6-month follow-up) of 2015 to students who reported using e-cigarettes within the past 30 days and the nicotine concentration level they used at baseline. Self-report of baseline e-cigarette nicotine concentration of none (0 mg/mL), low (1-5 mg/mL), medium (6-17 mg/mL), or high (≥18 mg/mL) typically used during the past 30 days. Frequency of combustible cigarette smoking and e-cigarette use within the past 30 days (0 days [none], 1-2 days [infrequent], or ≥3 days [frequent]) and daily intensity of smoking and vaping (number of cigarettes smoked per day, number of vaping episodes per day, and number of puffs per vaping episode) at the 6-month follow-up. The analytic sample included 181 students (96 boys [53.0%] and 85 girls [47.0%]; mean [SD] age, 16.1 [0.4] years). Each successive increase in nicotine concentration (none to low, low to medium, and medium to high) vaped was associated with a 2.26 (95% CI, 1.28-3.98) increase in the odds of frequent (vs no) smoking and a 1.65 (95% CI, 1.09-2.51) increase in the odds of frequent (vs no) vaping at follow-up after adjustment for baseline frequency of smoking and vaping and other relevant covariates. Use of e-cigarettes with high (vs no) nicotine concentration was associated with a greater number of cigarettes smoked per day at follow-up (adjusted rate ratio [RR], 7.03; 95% CI, 6.11-7.95). An

  2. First observation of 109Te β+ and electron capture decay to levels of 109Sb

    International Nuclear Information System (INIS)

    Ressler, J.J.; Walters, W.B.; Shergur, J.; Davids, C.N.; Heinz, A.; Seweryniak, D.; Dean, D.J.; Hjorth-Jensen, M.

    2002-01-01

    Low-spin levels in 109 Sb populated by 109 Te beta decay are reported for the first time. Seven new levels are proposed, two below 1 MeV excitation energy. Spins and parities of (1/2 + ) and (3/2 + ,5/2 + ) are suggested for the low energy levels by comparison to beta feeding intensities and systematics. These results are compared with new calculated levels for 109 Sb

  3. Echo 2: observations at Fort Churchill of a 4-keV peak in low-level electron precipitation

    International Nuclear Information System (INIS)

    Arnoldy, R.L.; Hendrickson, R.A.; Winckler, J.R.

    1975-01-01

    The Echo 2 rocket flight launched from Fort Churchill, Manitoba, offered the opportunity to observe high-latitude low-level electron precipitation during quiet magnetic conditions. Although no visual aurora was evident at the time of the flight, an auroral spectrum sharply peaked at a few keV was observed to have intensities from 1 to 2 orders of magnitude lower than peaked spectra typically assoicated with bright auroral forms. There is a growing body of evidence that relates peaked electron spectra to discrete aurora. The Echo 2 observations show that whatever the mechanism for peaking the electron spectrum in and above discrete forms, it operates over a range of precipitation intensities covering nearly 3 orders of magnitude down to subvisual or near subvisual events

  4. Propagation characteristics of resonance cone in a nonuniform magnetic field

    International Nuclear Information System (INIS)

    Ohnuma, T.; Sanuki, H.

    1984-01-01

    Propagation characteristics of resonance cone field for frequencies below the electron cyclotron frequency are described in a mirror magnetic field on the basis of fluid equation. Theoretical results are compared qualitatively with those of experiment

  5. Nonlinear optical beam manipulation, beam combining, and atmospheric propagation

    International Nuclear Information System (INIS)

    Fischer, R.A.

    1988-01-01

    These proceedings collect papers on optics: Topics include: diffraction properties of laser speckle, coherent beam combination by plasma modes, nonlinear responses, deformable mirrors, imaging radiometers, electron beam propagation in inhomogeneous media, and stability of laser beams in a structured environment

  6. Electronic-level interactions of tungsten oxide with unsupported Se/Ru electrocatalytic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lewera, Adam; Miecznikowski, Krzysztof [Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland); Hunger, Ralf [Institute of Materials Science, Darmstadt University of Technology, Darmstadt (Germany); Kolary-Zurowska, Aneta [Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland); Wieckowski, Andrzej [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Kulesza, Pawel J., E-mail: pkulesza@chem.uw.edu.p [Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland)

    2010-11-01

    Se/Ru nanoparticles - a potent non-platinum catalyst towards oxygen reduction reaction - were modified by hydrated WO{sub 3} and investigated using the rotating disk/ring electrode methods and by synchrotron X-ray photoelectron spectroscopy. The modification resulted in an enhanced catalytic activity towards oxygen reduction reaction (ORR). Our data indicate that the oxygen reduction current starts ca. 70 mV more positive and formation of undesirable hydrogen peroxide has significantly decreased following the modification of Se/Ru with WO{sub 3}. X-ray photoelectron spectroscopy reveals that WO{sub 3} interacts electronically with Se/Ru as the W 4f and Se 3d line-shapes change. We therefore conclude that the electronic interactions between Se/Ru and WO{sub 3} are primarily responsible for the increase in activity and selectivity of the WO{sub 3}-modified Se/Ru towards ORR.

  7. Electronic-level interactions of tungsten oxide with unsupported Se/Ru electrocatalytic nanoparticles

    International Nuclear Information System (INIS)

    Lewera, Adam; Miecznikowski, Krzysztof; Hunger, Ralf; Kolary-Zurowska, Aneta; Wieckowski, Andrzej; Kulesza, Pawel J.

    2010-01-01

    Se/Ru nanoparticles - a potent non-platinum catalyst towards oxygen reduction reaction - were modified by hydrated WO 3 and investigated using the rotating disk/ring electrode methods and by synchrotron X-ray photoelectron spectroscopy. The modification resulted in an enhanced catalytic activity towards oxygen reduction reaction (ORR). Our data indicate that the oxygen reduction current starts ca. 70 mV more positive and formation of undesirable hydrogen peroxide has significantly decreased following the modification of Se/Ru with WO 3 . X-ray photoelectron spectroscopy reveals that WO 3 interacts electronically with Se/Ru as the W 4f and Se 3d line-shapes change. We therefore conclude that the electronic interactions between Se/Ru and WO 3 are primarily responsible for the increase in activity and selectivity of the WO 3 -modified Se/Ru towards ORR.

  8. Integrating phenotypic data from electronic patient records with molecular level systems biology

    DEFF Research Database (Denmark)

    Brunak, Søren

    2011-01-01

    Electronic patient records remain a rather unexplored, but potentially rich data source for discovering correlations between diseases. We describe a general approach for gathering phenotypic descriptions of patients from medical records in a systematic and non-cohort dependent manner. By extracti...... Classification of Disease ontology and is therefore in principle language independent. As a use case we show how records from a Danish psychiatric hospital lead to the identification of disease correlations, which subsequently are mapped to systems biology frameworks....

  9. Latitudinal variation of the topside electron temperature at different levels of solar activity

    Czech Academy of Sciences Publication Activity Database

    Truhlík, Vladimír; Bilitza, D.; Třísková, Ludmila

    2009-01-01

    Roč. 44, č. 6 (2009), s. 693-700 ISSN 0273-1177 R&D Projects: GA AV ČR IAA300420603 Grant - others: NASA (US) NNH06CD17C Institutional research plan: CEZ:AV0Z30420517 Keywords : Electron temperature * Solar activity variation * Latitudinal dependence Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.079, year: 2009

  10. Propagation of waves

    CERN Document Server

    David, P

    2013-01-01

    Propagation of Waves focuses on the wave propagation around the earth, which is influenced by its curvature, surface irregularities, and by passage through atmospheric layers that may be refracting, absorbing, or ionized. This book begins by outlining the behavior of waves in the various media and at their interfaces, which simplifies the basic phenomena, such as absorption, refraction, reflection, and interference. Applications to the case of the terrestrial sphere are also discussed as a natural generalization. Following the deliberation on the diffraction of the "ground? wave around the ear

  11. Benchmarking of codes for electron cyclotron heating and electron cyclotron current drive under ITER conditions

    NARCIS (Netherlands)

    Prater, R.; Farina, D.; Gribov, Y.; Harvey, R. W.; Ram, A. K.; Lin-Liu, Y. R.; Poli, E.; Smirnov, A. P.; Volpe, F.; Westerhof, E.; Zvonkovo, A.

    2008-01-01

    Optimal design and use of electron cyclotron heating requires that accurate and relatively quick computer codes be available for prediction of wave coupling, propagation, damping and current drive at realistic levels of EC power. To this end, a number of codes have been developed in laboratories

  12. Component-Level Electronic-Assembly Repair (CLEAR) Spacecraft Circuit Diagnostics by Analog and Complex Signature Analysis

    Science.gov (United States)

    Oeftering, Richard C.; Wade, Raymond P.; Izadnegahdar, Alain

    2011-01-01

    The Component-Level Electronic-Assembly Repair (CLEAR) project at the NASA Glenn Research Center is aimed at developing technologies that will enable space-flight crews to perform in situ component-level repair of electronics on Moon and Mars outposts, where there is no existing infrastructure for logistics spares. These technologies must provide effective repair capabilities yet meet the payload and operational constraints of space facilities. Effective repair depends on a diagnostic capability that is versatile but easy to use by crew members that have limited training in electronics. CLEAR studied two techniques that involve extensive precharacterization of "known good" circuits to produce graphical signatures that provide an easy-to-use comparison method to quickly identify faulty components. Analog Signature Analysis (ASA) allows relatively rapid diagnostics of complex electronics by technicians with limited experience. Because of frequency limits and the growing dependence on broadband technologies, ASA must be augmented with other capabilities. To meet this challenge while preserving ease of use, CLEAR proposed an alternative called Complex Signature Analysis (CSA). Tests of ASA and CSA were used to compare capabilities and to determine if the techniques provided an overlapping or complementary capability. The results showed that the methods are complementary.

  13. Energy levels and electron g-factor of spherical quantum dots with Rashba spin-orbit interaction

    International Nuclear Information System (INIS)

    Vaseghi, B.; Rezaei, G.; Malian, M.

    2011-01-01

    We have studied simultaneous effects of Rashba spin-orbit interaction and external electric and magnetic fields on the subbands energy levels and electron g-factor of spherical quantum dots. It is shown that energy eigenvalues strongly depend on the combined effects of external electric and magnetic fields and spin-orbit interaction strength. The more the spin-orbit interaction strength increase, the more the energy eigenvalues increase. Also, we found that the electron g-factor sensitively differers from the bulk value due to the confinement effects. Furthermore, external fields and spin-orbit interaction have a great influence on this important quantity. -- Highlights: → Energy of spherical quantum dots depends on the spin-orbit interaction strength in external electric and magnetic fields. → Spin-orbit interaction shifts the energy levels. → Electron g-factor differs from the bulk value in spherical quantum dots due to the confinement effects. → Electron g-factor strongly depends on the spin-orbit interaction strength in external electric and magnetic fields.

  14. Lande gJ factors for even-parity electronic levels in the holmium atom

    Science.gov (United States)

    Stefanska, D.; Werbowy, S.; Krzykowski, A.; Furmann, B.

    2018-05-01

    In this work the hyperfine structure of the Zeeman splitting for 18 even-parity levels in the holmium atom was investigated. The experimental method applied was laser induced fluorescence in a hollow cathode discharge lamp. 20 spectral lines were investigated involving odd-parity levels from the ground multiplet, for which Lande gJ factors are known with high precision, as the lower levels; this greatly facilitated the evaluation of gJ factors for the upper levels. The gJ values for the even-parity levels considered are reported for the first time. They proved to compare fairly well with the values obtained recently in a semi-empirical analysis for the even-parity level system of Ho I.

  15. Radio Propagation into Modern Buildings

    DEFF Research Database (Denmark)

    Rodriguez Larrad, Ignacio; Nguyen, Huan Cong; Jørgensen, Niels T.K.

    2014-01-01

    Energy-efficient buildings are gaining momentum in order to comply with the new energy regulations. Especially in northern cold countries, thick reinforced walls and energy-efficient windows composed of several layers of glass plus metal coating are becoming the de facto elements in modern building...... constructions. These materials are used in favor of achieving a proper level of thermal isolation, but it has been noticed that they can impact heavily on radio signal propagation. This paper presents a measurement-based analysis of the outdoor-to-indoor attenuation experienced in several modern constructions...

  16. A Secondary-Level Curriculum in Industrial Electronics and Robotics. Final Report.

    Science.gov (United States)

    Besancon, Francis E.

    A curriculum was developed to provide the electromechanical skills necessary to operate and repair industrial robots to students at the secondary and adult vocational levels. To determine requirements for entry-level positions in the robotics industry, manufacturers and employers of industrial robots were contacted. No particular entry-level…

  17. Influence of surface pre-treatment on the electronic levels in silicon MaWCE nanowires.

    Science.gov (United States)

    Venturi, Giulia; Castaldini, Antonio; Schleusener, Alexander; Sivakov, Vladimir; Cavallini, Anna

    2015-05-15

    Deep level transient spectroscopy (DLTS) was performed on n-doped silicon nanowires grown by metal-assisted wet chemical etching (MaWCE) with gold as the catalyst in order to investigate the energetic scheme inside the bandgap. To observe the possible dependence of the level scheme on the processing temperature, DLTS measurements were performed on the nanowires grown on a non-treated Au/Si surface and on a thermally pre-treated Au/Si surface. A noticeable modification of the configuration of the energy levels was observed, induced by the annealing process. Based on our results on these MaWCE nanowires and on literature data about deep levels in bulk silicon, some hypotheses were advanced regarding the identification of the defects responsible of the energy levels revealed.

  18. Two Dimensional Effective Electron Mass at the Fermi Level in Quantum Wells of III-V, Ternary and Quaternary Semiconductors.

    Science.gov (United States)

    Chakrabarti, S; Chatterjee, B; Debbarma, S; Ghatak, K P

    2015-09-01

    In this paper we study the influence of strong electric field on the two dimensional (2D)effective electron mass (EEM) at the Fermi level in quantum wells of III-V, ternary and quaternary semiconductors within the framework of k x p formalism by formulating a new 2D electron energy spectrum. It appears taking quantum wells of InSb, InAs, Hg(1-x)Cd(x)Te and In(1-x)Ga(x)As(1-y)P(y) lattice matched to InP as examples that the EEM increases with decreasing film thickness, increasing electric field and increases with increasing surface electron concentration exhibiting spikey oscillations because of the crossing over of the Fermi level by the quantized level in quantum wells and the quantized oscillation occurs when the Fermi energy touches the sub-band energy. The electric field makes the mass quantum number dependent and the oscillatory mass introduces quantum number dependent mass anisotropy in addition to energy. The EEM increases with decreasing alloy composition where the variations are totally band structure dependent. Under certain limiting conditions all the results for all the cases get simplified into the well-known parabolic energy bands and thus confirming the compatibility test. The content of this paper finds three applications in the fields of nano-science and technology.

  19. Equivalent circuit-level model of quantum cascade lasers with integrated hot-electron and hot-phonon effects

    Science.gov (United States)

    Yousefvand, H. R.

    2017-12-01

    We report a study of the effects of hot-electron and hot-phonon dynamics on the output characteristics of quantum cascade lasers (QCLs) using an equivalent circuit-level model. The model is developed from the energy balance equation to adopt the electron temperature in the active region levels, the heat transfer equation to include the lattice temperature, the nonequilibrium phonon rate to account for the hot phonon dynamics and simplified two-level rate equations to incorporate the carrier and photon dynamics in the active region. This technique simplifies the description of the electron-phonon interaction in QCLs far from the equilibrium condition. Using the presented model, the steady and transient responses of the QCLs for a wide range of sink temperatures (80 to 320 K) are investigated and analysed. The model enables us to explain the operating characteristics found in QCLs. This predictive model is expected to be applicable to all QCL material systems operating in pulsed and cw regimes.

  20. Propagation environments [Chapter 4

    Science.gov (United States)

    Douglass F. Jacobs; Thomas D. Landis; Tara Luna

    2009-01-01

    An understanding of all factors influencing plant growth in a nursery environment is needed for the successful growth and production of high-quality container plants. Propagation structures modify the atmospheric conditions of temperature, light, and relative humidity. Native plant nurseries are different from typical horticultural nurseries because plants must be...

  1. Uncertainty Propagation in OMFIT

    Science.gov (United States)

    Smith, Sterling; Meneghini, Orso; Sung, Choongki

    2017-10-01

    A rigorous comparison of power balance fluxes and turbulent model fluxes requires the propagation of uncertainties in the kinetic profiles and their derivatives. Making extensive use of the python uncertainties package, the OMFIT framework has been used to propagate covariant uncertainties to provide an uncertainty in the power balance calculation from the ONETWO code, as well as through the turbulent fluxes calculated by the TGLF code. The covariant uncertainties arise from fitting 1D (constant on flux surface) density and temperature profiles and associated random errors with parameterized functions such as a modified tanh. The power balance and model fluxes can then be compared with quantification of the uncertainties. No effort is made at propagating systematic errors. A case study will be shown for the effects of resonant magnetic perturbations on the kinetic profiles and fluxes at the top of the pedestal. A separate attempt at modeling the random errors with Monte Carlo sampling will be compared to the method of propagating the fitting function parameter covariant uncertainties. Work supported by US DOE under DE-FC02-04ER54698, DE-FG2-95ER-54309, DE-SC 0012656.

  2. The Weinberg propagators

    International Nuclear Information System (INIS)

    Dvoeglazov, V.V.

    1997-01-01

    An analog of the j = 1/2 Feynman-Dyson propagator is presented in the framework of the j = 1 Weinberg's theory. The basis for this construction is the concept of the Weinberg field as a system of four field functions differing by parity and by dual transformations. (orig.)

  3. UWB Propagation through Walls

    Czech Academy of Sciences Publication Activity Database

    Schejbal, V.; Bezoušek, P.; Čermák, D.; NĚMEC, Z.; Fišer, Ondřej; Hájek, M.

    2006-01-01

    Roč. 15, č. 1 (2006), s. 17-24 ISSN 1210-2512 R&D Projects: GA MPO(CZ) FT-TA2/030 Institutional research plan: CEZ:AV0Z30420517 Keywords : Ultra wide band * UWB antennas * UWB propagation * multipath effects Subject RIV: JB - Sensors, Measurment, Regulation

  4. Tropical Cyclone Propagation

    National Research Council Canada - National Science Library

    Gray, William

    1994-01-01

    This paper discusses the question of tropical cyclone propagation or why the average tropical cyclone moves 1-2 m/s faster and usually 10-20 deg to the left of its surrounding (or 5-7 deg radius) deep layer (850-300 mb) steering current...

  5. Large scale propagation intermittency in the atmosphere

    Science.gov (United States)

    Mehrabi, Ali

    2000-11-01

    Long-term (several minutes to hours) amplitude variations observed in outdoor sound propagation experiments at Disneyland, California, in February 1998 are explained in terms of a time varying index of refraction. The experimentally propagated acoustic signals were received and recorded at several locations ranging from 300 meters to 2,800 meters. Meteorological data was taken as a function of altitude simultaneously with the received signal levels. There were many barriers along the path of acoustic propagation that affected the received signal levels, especially at short ranges. In a downward refraction situation, there could be a random change of amplitude in the predicted signals. A computer model based on the Fast Field Program (FFP) was used to compute the signal loss at the different receiving locations and to verify that the variations in the received signal levels can be predicted numerically. The calculations agree with experimental data with the same trend variations in average amplitude.

  6. Determining the level of awareness of the physicians in using the variety of electronic information resources and the effecting factors.

    Science.gov (United States)

    Papi, Ahmad; Ghazavi, Roghayeh; Moradi, Salimeh

    2015-01-01

    Understanding of the medical society's from the types of information resources for quick and easy access to information is an imperative task in medical researches and management of the treatment. The present study was aimed to determine the level of awareness of the physicians in using various electronic information resources and the factors affecting it. This study was a descriptive survey. The data collection tool was a researcher-made questionnaire. The study population included all the physicians and specialty physicians of the teaching hospitals affiliated to Isfahan University of Medical Sciences and numbered 350. The sample size based on Morgan's formula was set at 180. The content validity of the tool was confirmed by the library and information professionals and the reliability was 95%. Descriptive statistics were used including the SPSS software version 19. On reviewing the need of the physicians to obtain the information on several occasions, the need for information in conducting the researches was reported by the maximum number of physicians (91.9%) and the usage of information resources, especially the electronic resources, formed 65.4% as the highest rate with regard to meeting the information needs of the physicians. Among the electronic information databases, the maximum awareness was related to Medline with 86.5%. Among the various electronic information resources, the highest awareness (43.3%) was related to the E-journals. The highest usage (36%) was also from the same source. The studied physicians considered the most effective deterrent in the use of electronic information resources as being too busy and lack of time. Despite the importance of electronic information resources for the physician's community, there was no comprehensive knowledge of these resources. This can lead to less usage of these resources. Therefore, careful planning is necessary in the hospital libraries in order to introduce the facilities and full capabilities of the

  7. First-principles calculation of electronic energy level alignment at electrochemical interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Azar, Yavar T.; Payami, Mahmoud, E-mail: mpayami@aeoi.org.ir

    2017-08-01

    Highlights: • Using DFT calculation, level shifts of TiO{sub 2} and ZnO at the interfaces with MeCN and DMF are determined. • Level shifts are obtained using potential difference between the surfaces of asymmetric slabs. • Solvent molecules give an up-shift to the levels that varies with coverage. • MD simulations show that at room temperatures the surface is not fully covered by the solvent molecules. - Abstract: Energy level alignment at solid–solvent interfaces is an important step in determining the properties of electrochemical systems. The positions of conduction and valence band edges of a semiconductor are affected by its environment. In this study, using first-principles DFT calculation, we have determined the level shifts of the semiconductors TiO{sub 2} and ZnO at the interfaces with MeCN and DMF solvent molecules. The level shifts of semiconductor are obtained using the potential difference between the clean and exposed surfaces of asymmetric slabs. In this work, neglecting the effects of present ions in the electrolyte solution, we have shown that the solvent molecules give rise to an up-shift for the levels, and the amount of this shift varies with coverage. It is also shown that the shapes of density of states do not change sensibly near the gap. Molecular dynamics simulations of the interface have shown that at room temperatures the semiconductor surface is not fully covered by the solvent molecules, and one must use intermediate values in an static calculations.

  8. Effect of dietary poly unsaturated fatty acids on total brain lipid concentration and anxiety levels of electron beam irradiated mice

    International Nuclear Information System (INIS)

    Suchetha Kumari; Bekal, Mahesh

    2013-01-01

    The whole brain irradiation causes injury to the nervous system at various levels. Omega-3 poly unsaturated fatty acids are very much essential for the growth and development of nervous system. Dietary supplementation of these nutrients will promote the development of injured neuronal cells. Therefore this study was undertaken to establish the role of Omega-3 poly unsaturated fatty acids on total brain lipid concentration, lipid peroxidation and anxiety levels in the irradiated mice. The effect of Electron Beam Radiation (EBR) on total brain lipid concentration, lipid peroxidation and anxiety level were investigated in male Swiss albino mice. The study groups were subjected to a sub-lethal dose of EBR and also the flax seed extract and fish oil were given orally to the irradiated mice. Irradiated groups show significant elevation in anxiety levels when compared to control group, indicating the acute radiation effects on the central nervous system. But the oral supplementation of dietary PUFA source decrees the anxiety level in the irradiated group. The analysis of lipid peroxidation showed a significant level of changes when compared between control and radiation groups. Dietary PUFA supplementation showed a significant level of decrease in the lipid peroxidation in the irradiated groups. The observation of total lipids in brain shows decrease in concentration in the irradiated groups, the differences in the variables follow the similar patterns as of that the MDA levels. This study suggests that the dietary intake of PUFAs may help in prevention and recovery of the oxidative stress caused by radiation. (author)

  9. In-situ environmental (scanning) transmission electron microscopy of catalysts at the atomic level

    International Nuclear Information System (INIS)

    Gai, P L; Boyes, E D

    2014-01-01

    Observing reacting single atoms on the solid catalyst surfaces under controlled reaction conditions is a key goal in understanding and controlling heterogeneous catalytic reactions. In-situ real time aberration corrected environmental (scanning) transmission electron microscopy (E(S)TEM permit the direct imaging of dynamic surface and sub-surface structures of reacting catalysts. In this paper in-situ AC ETEM and AC ESTEM studies under controlled reaction environments of oxide catalysts and supported metal nanocatalysts important in chemical industry are presented. They provide the direct evidence of dynamic processes at the oxide catalyst surface at the atomic scale and single atom dynamics in catalytic reactions. The ESTEM studies of single atom dynamics in controlled reaction environments show that nanoparticles act as reservoirs of ad-atoms. The results have important implications in catalysis and nanoparticle studies

  10. Are associations between electronic media use and BMI different across levels of physical activity?

    DEFF Research Database (Denmark)

    Melkevik, Ole; Haug, Ellen; Rasmussen, Mette

    2015-01-01

    and girls who did not comply with physical activity guidelines. Among physically active adolescents, EM was found to be significantly associated with BMI or odds for overweight among girls, but not among boys. CONCLUSION: While the usage of EM appear to be inconsequential for BMI and the risk of overweight...... among physically active boys, we find evidence indicating that EM use is associated with BMI and risk for overweight among girls, including those who report complying with MVPA guidelines.......BACKGROUND: The use of electronic media has been found to be a risk factor for higher BMI and for being overweight. Physical activity has been found to be associated with lower BMI and lower risk for being overweight. Little is known about whether the associations between physical activity...

  11. A method for atomic-level noncontact thermometry with electron energy distribution

    Science.gov (United States)

    Kinoshita, Ikuo; Tsukada, Chiharu; Ouchi, Kohei; Kobayashi, Eiichi; Ishii, Juntaro

    2017-04-01

    We devised a new method of determining the temperatures of materials with their electron-energy distributions. The Fermi-Dirac distribution convoluted with a linear combination of Gaussian and Lorentzian distributions was fitted to the photoelectron spectrum measured for the Au(110) single-crystal surface at liquid N2-cooled temperature. The fitting successfully determined the surface-local thermodynamic temperature and the energy resolution simultaneously from the photoelectron spectrum, without any preliminary results of other measurements. The determined thermodynamic temperature was 99 ± 2.1 K, which was in good agreement with the reference temperature of 98.5 ± 0.5 K measured using a silicon diode sensor attached to the sample holder.

  12. Excitation of the 1P and 3P levels of Mg atom by electron impact

    International Nuclear Information System (INIS)

    Avdonina, N.B.; Amus'ya, M.Ya.

    1983-01-01

    Using a diagram method of the many-body theory in the first order of the perturbation theory for the interaction of incident electron and atom expressions for differential and integral excitation cross sections of 3s → 3p 1 P and 3s → 3p 3 P magnesium have been derived. Calculational results are compared with experimental as well as with calculations made in the approximation of a strong coupling. In a wide range of scattering angles good agreement with cross sections measured experimentally has been obtained. Necessity of the diagram consideration of a higher order of the perturbation theory during the investigation of the scattering processes at small angles is concluded on the basis of the above comparison

  13. Refined energetic ordering for sulphate-water (n = 3-6) clusters using high-level electronic structure calculations

    Science.gov (United States)

    Lambrecht, Daniel S.; McCaslin, Laura; Xantheas, Sotiris S.; Epifanovsky, Evgeny; Head-Gordon, Martin

    2012-10-01

    This work reports refinements of the energetic ordering of the known low-energy structures of sulphate-water clusters ? (n = 3-6) using high-level electronic structure methods. Coupled cluster singles and doubles with perturbative triples (CCSD(T)) is used in combination with an estimate of basis set effects up to the complete basis set limit using second-order Møller-Plesset theory. Harmonic zero-point energy (ZPE), included at the B3LYP/6-311 + + G(3df,3pd) level, was found to have a significant effect on the energetic ordering. In fact, we show that the energetic ordering is a result of a delicate balance between the electronic and vibrational energies. Limitations of the ZPE calculations, both due to electronic structure errors, and use of the harmonic approximation, probably constitute the largest remaining errors. Due to the often small energy differences between cluster isomers, and the significant role of ZPE, deuteration can alter the relative energies of low-lying structures, and, when it is applied in conjunction with calculated harmonic ZPEs, even alters the global minimum for n = 5. Experiments on deuterated clusters, as well as more sophisticated vibrational calculations, may therefore be quite interesting.

  14. Resonant electronic transport through a triple quantum-dot with Λ-type level structure under dual radiation fields

    International Nuclear Information System (INIS)

    Guan, Chun; Xing, Yunhui; Zhang, Chao; Ma, Zhongshui

    2014-01-01

    Due to quantum interference, light can transmit through dense atomic media, a phenomenon known as electromagnetically induced transparency (EIT). We propose that EIT is not limited to light transmission and there is an electronic analog where resonant transparency in charge transport in an opaque structure can be induced by electromagnetic radiation. A triple-quantum-dots system with Λ-type level structure is generally opaque due to the level in the center dot being significantly higher and therefore hopping from the left dot to the center dot is almost forbidden. We demonstrate that an electromagnetically induced electron transparency (EIET) in charge of transport can indeed occur in the Λ-type system. The direct evidence of EIET is that an electron can travel from the left dot to the right dot, while the center dot apparently becomes invisible. We analyze EIET and the related shot noise in both the zero and strong Coulomb blockade regimes. It is found that the EIET (position, height, and symmetry) can be tuned by several controllable parameters of the radiation fields, such as the Rabi frequencies and detuning frequencies. The result offers a transparency/opaque tuning technique in charge transport using interfering radiation fields

  15. Observation of an electron band above the Fermi level in FeTe0.55Se0.45 from in-situ surface doping

    International Nuclear Information System (INIS)

    Zhang, P.; Ma, J.; Qian, T.; Richard, P.; Ding, H.; Xu, N.; Xu, Y.-M.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.

    2014-01-01

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe 0.55 Se 0.45 . The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily electron-doped KFe 2−x Se 2 compound.

  16. An electronic screen for triaging adolescent substance use by risk levels.

    Science.gov (United States)

    Levy, Sharon; Weiss, Roger; Sherritt, Lon; Ziemnik, Rosemary; Spalding, Allegra; Van Hook, Shari; Shrier, Lydia A

    2014-09-01

    Screening adolescents for substance use and intervening immediately can reduce the burden of addiction and substance-related morbidity. Several screening tools have been developed to identify problem substance use for adolescents, but none have been calibrated to triage adolescents into clinically relevant risk categories to guide interventions. To describe the psychometric properties of an electronic screen and brief assessment tool that triages adolescents into 4 actionable categories regarding their experience with nontobacco substance use. Adolescent patients (age range, 12-17 years) arriving for routine medical care at 2 outpatient primary care centers and 1 outpatient center for substance use treatment at a pediatric hospital completed an electronic screening tool from June 1, 2012, through March 31, 2013, that consisted of a question on the frequency of using 8 types of drugs in the past year (Screening to Brief Intervention). Additional questions assessed severity of any past-year substance use. Patients completed a structured diagnostic interview (Composite International Diagnostic Interview-Substance Abuse Module), yielding Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) substance use diagnoses. For the entire screen and the Screening to Brief Intervention, sensitivity and specificity for identifying nontobacco substance use, substance use disorders, severe substance use disorders, and tobacco dependence were calculated using the Composite International Diagnostic Interview-Substance Abuse Module as the criterion standard. Of 340 patients invited to participate, 216 (63.5%) enrolled in the study. Sensitivity and specificity were 100% and 84% (95% CI, 76%-89%) for identifying nontobacco substance use, 90% (95% CI, 77%-96%) and 94% (95% CI, 89%-96%) for substance use disorders, 100% and 94% (95% CI, 90%-96%) for severe substance use disorders, and 75% (95% CI, 52%-89%) and 98% (95% CI, 95%-100%) for nicotine dependence. No significant

  17. Propagator of stochastic electrodynamics

    International Nuclear Information System (INIS)

    Cavalleri, G.

    1981-01-01

    The ''elementary propagator'' for the position of a free charged particle subject to the zero-point electromagnetic field with Lorentz-invariant spectral density proportionalω 3 is obtained. The nonstationary process for the position is solved by the stationary process for the acceleration. The dispersion of the position elementary propagator is compared with that of quantum electrodynamics. Finally, the evolution of the probability density is obtained starting from an initial distribution confined in a small volume and with a Gaussian distribution in the velocities. The resulting probability density for the position turns out to be equal, to within radiative corrections, to psipsi* where psi is the Kennard wave packet. If the radiative corrections are retained, the present result is new since the corresponding expression in quantum electrodynamics has not yet been found. Besides preceding quantum electrodynamics for this problem, no renormalization is required in stochastic electrodynamics

  18. Preventing Unofficial Information Propagation

    Science.gov (United States)

    Le, Zhengyi; Ouyang, Yi; Xu, Yurong; Ford, James; Makedon, Fillia

    Digital copies are susceptible to theft and vulnerable to leakage, copying, or manipulation. When someone (or some group), who has stolen, leaked, copied, or manipulated digital documents propagates the documents over the Internet and/or distributes those through physical distribution channels many challenges arise which document holders must overcome in order to mitigate the impact to their privacy or business. This paper focuses on the propagation problem of digital credentials, which may contain sensitive information about a credential holder. Existing work such as access control policies and the Platform for Privacy Preferences (P3P) assumes that qualified or certified credential viewers are honest and reliable. The proposed approach in this paper uses short-lived credentials based on reverse forward secure signatures to remove this assumption and mitigate the damage caused by a dishonest or honest but compromised viewer.

  19. Submillimeter wave propagation in tokamak plasmas

    International Nuclear Information System (INIS)

    Ma, C.H.; Hutchinson, D.P.; Staats, P.A.; Vander Sluis, K.L.; Mansfield, D.K.; Park, H.; Johnson, L.C.

    1985-01-01

    The propagation of submillimeter-waves (smm) in tokamak plasmas has been investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses have been carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system has been employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes have been developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements

  20. Submillimeter wave propagation in tokamak plasmas

    International Nuclear Information System (INIS)

    Ma, C.H.; Hutchinson, D.P.; Staats, P.A.; Vander Sluis, K.L.; Mansfield, D.K.; Park, H.; Johnson, L.C.

    1986-01-01

    Propagation of submillimeter waves (smm) in tokamak plasma was investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses were carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system was employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes were developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements. 5 references, 2 figures

  1. DETERMINING ELECTRONIC AND CYBER ATTACK RISK LEVEL FOR UNMANNED AIRCRAFT IN A CONTESTED ENVIRONMENT

    Science.gov (United States)

    2016-08-01

    facilitated by the luxury of operating in generally permissive airspace, facing little resistance from insurgent forces. Along with the increase of UAS...and would be almost exclusively cyber in nature. In this case, an enemy could target the highest levels of national C2 no matter where they lie... exclusively controlled by pilots in the cockpit, as are tankers, transports, and battlefield C2 aircraft. UAS assets can fill a variety of roles in this

  2. Stabilization of Fermi level via electronic excitation in Sn doped CdO thin films

    Science.gov (United States)

    Das, Arkaprava; Singh, Fouran

    2018-04-01

    Pure and Sn doped CdO sol-gel derived thin films were deposited on corning glass substrate and further irradiated by swift heavy ion (SHI) (Ag and O) with fluence upto 3×1013 ions/cm2. The observed tensile stress from X-ray diffraction pattern at higher fluence for Ag ions can be corroborated to the imbrications of cylindrical tracks due to multiple impacts. The anomalous band gap enhancement after irradiation may be attributed to the consolidated effect of Burstein-Moss shift (BMS) and impurity induced virtual gap states (ViGs). At higher excitation density as Fermi stabilization level (EFS) tends to coincide with charge neutrality level (CNL), band gap enhancement saturates as further creation of additional defects inside the lattice becomes unsustainable. Raman spectroscopy divulges an intensity enhancement of 478 cm-1 LO phonon mode with Sn doping and irradiation induces further asymmetric peak broadening due to damage and disordering inside the lattice. However for 3% Sn doped thin film irradiated with Ag ions having 3×1013 fluence shows a drastic change in structural properties and reduction in band gap which might be attributed to the generation of localized energy levels between conduction and valance band due to high density of defects.

  3. Acoustic energy propagation around railways

    Science.gov (United States)

    Cizkova, Petra

    2017-09-01

    The article deals with the issues of acoustic energy propagation around railways. The research subject was noise emission spreading into the surroundings during the passage of trains over a directly travelled steel bridge construction. Noise emissions were measured using direct measurements in the field. The measurements were performed in two measurement profiles. The noise exposures A LAE measured near the steel bridge construction were compared against the noise exposures A LAE captured on an open track. From the difference of these data, the noise level of the steel bridge structure was determined. Part of the research was to evaluate the effect of the reconstruction of the railway track superstructure on the acoustic situation in the given section of the railway track. The article describes the methodology of measurements, including the processing and evaluation of measured data. The article points out the noise levels of the steel bridge construction and assesses changes in the acoustic situation after the reconstruction.

  4. Electron detector

    International Nuclear Information System (INIS)

    Hashimoto, H.; Mogami, A.

    1975-01-01

    A device for measuring electron densities at a given energy level in an electron beam or the like having strong background noise, for example, in the detection of Auger electric energy spectrums is described. An electron analyzer passes electrons at the given energy level and at the same time electrons of at least one adjacent energy level. Detecting means associated therewith produce signals indicative of the densities of the electrons at each energy level and combine these signals to produce a signal indicative of the density of the electrons of the given energy level absent background noise

  5. Coulomb correlations in many-electron systems on the level of self-consistent fields

    International Nuclear Information System (INIS)

    Warken, M.

    1991-06-01

    It was the aim of this thesis to show means and ways, in order to regard Coulomb correlation already on the SCF level. As mean to facilitate this general averaged fields should serve. For this first in chapter I was shown, how by means of suitable gauge fixings terms into effective potentials of the Hartree-Fock or g-Hartree type are introduced, which permit an interpretation as correlation density or as effective coupling constant. The following considerations were exemplarily performed on the cases g-Hartree (in Coulomb gauge) and on f-Hartree-Fock. (orig./HSI) [de

  6. Out-of-order parallel discrete event simulation for electronic system-level design

    CERN Document Server

    Chen, Weiwei

    2014-01-01

    This book offers readers a set of new approaches and tools a set of tools and techniques for facing challenges in parallelization with design of embedded systems.? It provides an advanced parallel simulation infrastructure for efficient and effective system-level model validation and development so as to build better products in less time.? Since parallel discrete event simulation (PDES) has the potential to exploit the underlying parallel computational capability in today's multi-core simulation hosts, the author begins by reviewing the parallelization of discrete event simulation, identifyin

  7. Renormalized molecular levels in a Sc3N@C-80 molecular electronic device

    DEFF Research Database (Denmark)

    Larade, Brian; Taylor, Jeremy Philip; Zheng, Q. R.

    2001-01-01

    We address several general questions about quantum transport through molecular systems by an ab initio analysis of a scandium-nitrogen doped C-80 metallofullerene device. Charge transfer from the Sc3N is found to drastically change the current-voltage characteristics: the current through the Sc3N...... levels and main transmission features shift in energy corresponding to half the applied bias voltage. This is also consistent with our finding that the voltage drops by V-b/2 at each molecule/electrode contact....

  8. The use of radiation trapping in the measurement of the electron excitation cross section for the production of the 1s4 (3P1) level of Ne

    International Nuclear Information System (INIS)

    Miers, R.E.; Gastineau, J.E.; Phillps, M.H.; Anderson, L.W.; Lin, C.C.

    1981-01-01

    The authors report the use of laser induced fluorescence for the first measurement of the electron excitation cross section for the production of the 1s 4 ( 3 P 1 ) level of Ne. Radiation trapping is used to lengthen the effective lifetime of the 1s 4 level allowing for the electron excitation cross section of the 1s 4 level to be measured in a manner similar to the measurement of electron excitation cross sections of the metastable 1s 3 and 1s 5 levels. (Auth.)

  9. Acetone-water complexes at MRCI level using localized orbitals: n ->pi* and pi ->pi* electronic transitions

    DEFF Research Database (Denmark)

    Hoyau, S.; Ben Amor, N.; Borini, Stefano

    2008-01-01

    The n -> pi* and pi -> pi* vertical electronic transitions of acetone with two and four H2O which correspond to a first solvation shell are considered. By using localized orbitals, and thanks to the MRCI approach which permits to know the wave function, the role of the various solvent molecules...... is analysed in details. Distinguishing the solvent molecules allows one to consider them at different calculation levels. The methodology is to compare the spectra obtained with four H2O, with two H2O either in the acetone plane or in a perpendicular plane and when they are completely or partly frozen....

  10. Level-resolved distorted-wave cross-sections of electron impact ionization of Ar{sup 5+}

    Energy Technology Data Exchange (ETDEWEB)

    Yumak, A; Yavuz, I; Altun, Z, E-mail: zikalt@superonline.co [Department of Physics, Marmara University, Istanbul, 34722 (Turkey)

    2009-11-01

    Electron impact ionization cross sections of Ar{sup 5+} were calculated using configuration-average (CADW) and level-resolved (LRDW) distorted-wave methods. Direct ionization cross-sections of 2s, 2p, 3s and 3p subshells were calculated within a CADW approximation. The contributions from the excitation autoionization channels were evaluated assuming single excitations from the 2s, 2p, and 3s subshells and in both CADW and LRDW methods. The radiative stabilization of the excitation autoionization channels were found to reduce the excitation autoionization by a small amount.

  11. Theoretical analysis of the multiple resonances for many-level spin systems. The four-level spin system of s electron ions subjected to strong microwave fields

    International Nuclear Information System (INIS)

    Popescu, F.F.; Marica, F.

    1994-01-01

    The analytic steady state solutions of master equation for the density matrix of a multilevel spin system in dilute paramagnetic crystals at high temperature, subjected to strong microwave fields, are discussed. These solutions enable to obtain the populations of the levels, and the microwave powers absorbed or emitted by the crystal, in the presence of one, two or more microwave fields. A detailed theoretical study of the maser effects for s electron ions with nuclear spin one-half is carried out. In the case of three frequency correlated strong fields, when 'the spectroscopic' bridge conditions are fulfilled, sensitive detections, or high efficient generations of microwaves of frequency higher than those of the pumping fields are predicted. (author) 16 figs., 16 refs

  12. Using electronic mail to improve MMR uptake amongst third level students.

    Science.gov (United States)

    Cooney, F; Ryan, A; Schinaia, N; Breslin, A

    2010-03-01

    This study assessed the usefulness of email in informing third level students about special MMR clinics being provided on campus during a mumps outbreak in the North West of Ireland. Email messages were sent directly to students, informing them of the clinics, inviting them to make a clinic appointment by email and providing details of walk-in clinics. At the clinics, all 177 attendees were asked to fill out a questionnaire and the response rate was 89% (n=158). Regarding the main sources of information about the vaccination clinics, email was selected by 117 (74%) students, word-of-mouth by 27 (17%), posters/leaflets by 8 (5%), and other sources by 6 (4%). Use of email as a source of information was rated as very good/excellent by 115 (73%), as good by 35 (22%) and poor/fair by 8 (5%). This study demonstrates that email is a useful and acceptable way of informing third level students about immunisation clinics in an outbreak situation.

  13. Using electronic mail to improve MMR uptake amongst third level students.

    LENUS (Irish Health Repository)

    Cooney, F

    2010-03-01

    This study assessed the usefulness of email in informing third level students about special MMR clinics being provided on campus during a mumps outbreak in the North West of Ireland. Email messages were sent directly to students, informing them of the clinics, inviting them to make a clinic appointment by email and providing details of walk-in clinics. At the clinics, all 177 attendees were asked to fill out a questionnaire and the response rate was 89% (n=158). Regarding the main sources of information about the vaccination clinics, email was selected by 117 (74%) students, word-of-mouth by 27 (17%), posters\\/leaflets by 8 (5%), and other sources by 6 (4%). Use of email as a source of information was rated as very good\\/excellent by 115 (73%), as good by 35 (22%) and poor\\/fair by 8 (5%). This study demonstrates that email is a useful and acceptable way of informing third level students about immunisation clinics in an outbreak situation.

  14. Low level radiation testing of micro-electronic components. Pt. 1

    International Nuclear Information System (INIS)

    Farren, J.; Stephen, J.H.; Mapper, D.; Sanderson, T.K.; Hardman, M.

    1984-05-01

    A review of the existing literature has been carried out, dealing with the current technology relating to low level radiation testing of microelectronic devices, as used in space satellite systems. After consideration of the space radiation environment, the general effects of cosmic radiation on MOSFET structures and other MOS devices have been assessed. The important aspect of annealing phenomena in relation to gamma-ray induced damage has also been reviewed in detail. The experimental and theoretical aspects of radiation testing have been assessed, with particular reference to the Harwell LORAD low level irradiation test facility. In addition, a review of modern dosimetry methods has been carried out, with specific regard to the problems of accurately measuring low radiation fields (1 to 10 R/hour) over periods of many months. Finally, a detailed account of the proposed experimental programme to be carried out in the LORAD facility is presented, and aspects of the experimental set-up discussed. The particular types of test circuits to be studied are dealt with, and full consideration is given to the various CMOS memory devices of special interest in the ESA space satellite programme. (author)

  15. Holography and coherent diffraction with low-energy electrons: A route towards structural biology at the single molecule level.

    Science.gov (United States)

    Latychevskaia, Tatiana; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

    2015-12-01

    The current state of the art in structural biology is led by NMR, X-ray crystallography and TEM investigations. These powerful tools however all rely on averaging over a large ensemble of molecules. Here, we present an alternative concept aiming at structural analysis at the single molecule level. We show that by combining electron holography and coherent diffraction imaging estimations concerning the phase of the scattered wave become needless as the phase information is extracted from the data directly and unambiguously. Performed with low-energy electrons the resolution of this lens-less microscope is just limited by the De Broglie wavelength of the electron wave and the numerical aperture, given by detector geometry. In imaging freestanding graphene, a resolution of 2Å has been achieved revealing the 660.000 unit cells of the graphene sheet from a single data set. Once applied to individual biomolecules the method shall ultimately allow for non-destructive imaging and imports the potential to distinguish between different conformations of proteins with atomic resolution. Copyright © 2015. Published by Elsevier B.V.

  16. 'Away' is a place: The impact of electronic waste recycling on blood lead levels in Ghana.

    Science.gov (United States)

    Amankwaa, Ebenezer Forkuo; Adovor Tsikudo, Kwame A; Bowman, Jay A

    2017-12-01

    E-waste recycling remains a major source of livelihood for many urban poor in developing countries, but this economic activity is fraught with significant environmental health risk. Yet, human exposure to the toxic elements associated with e-waste activities remains understudied and not evidently understood. This study investigates the impact of informal e-waste processing on the blood lead levels (BLLs) of e-waste workers and non-e-waste workers (mainly females working in activities that serve the Agbogbloshie e-waste site), and relates their lead exposure to socio-demographic and occupational characteristics. A total of 128 blood samples were analysed for lead levels. Surprisingly, the mean BLL (3.54μg/dL) of non-e-waste workers was slightly higher than that of e-waste workers (3.49μg/dL), although higher BLLs ranges were found among e-waste workers (0.50-18.80μg/dL) than non-e-waste workers (0.30-8.20μg/dL). Workers who engaged in e-waste burning tended to have the highest BLLs. In general, the BLLs are within the ABLES/US CDC reference level of 5μg/dL, although 12.3% of the workers have elevated BLLs, i.e. BLL ≥5μg/dL. The study concludes that the impact of e-waste recycling is not limited to workers alone. Traders and residents within the Agbogbloshie enclave are equally at risk through a range of environmental vectors. This calls for increased public awareness about the effects of human exposure to lead and other toxic elements from e-waste recycling. A key contribution is that government and stakeholder projects for safe e-waste infrastructure should disaggregate the e-waste value chain, recognize differential risk and resist one-size-fits-all strategies. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Quantum propagation across cosmological singularities

    Science.gov (United States)

    Gielen, Steffen; Turok, Neil

    2017-05-01

    The initial singularity is the most troubling feature of the standard cosmology, which quantum effects are hoped to resolve. In this paper, we study quantum cosmology with conformal (Weyl) invariant matter. We show that it is natural to extend the scale factor to negative values, allowing a large, collapsing universe to evolve across a quantum "bounce" into an expanding universe like ours. We compute the Feynman propagator for Friedmann-Robertson-Walker backgrounds exactly, identifying curious pathologies in the case of curved (open or closed) universes. We then include anisotropies, fixing the operator ordering of the quantum Hamiltonian by imposing covariance under field redefinitions and again finding exact solutions. We show how complex classical solutions allow one to circumvent the singularity while maintaining the validity of the semiclassical approximation. The simplest isotropic universes sit on a critical boundary, beyond which there is qualitatively different behavior, with potential for instability. Additional scalars improve the theory's stability. Finally, we study the semiclassical propagation of inhomogeneous perturbations about the flat, isotropic case, at linear and nonlinear order, showing that, at least at this level, there is no particle production across the bounce. These results form the basis for a promising new approach to quantum cosmology and the resolution of the big bang singularity.

  18. Electronic defect levels in continuous wave laser annealed silicon metal oxide semiconductor devices

    Science.gov (United States)

    Cervera, M.; Garcia, B. J.; Martinez, J.; Garrido, J.; Piqueras, J.

    1988-09-01

    The effect of laser treatment on the bulk and interface states of the Si-SiO2 structure has been investigated. The annealing was performed prior to the gate metallization using a continuous wave Ar+ laser. For low laser powers the interface state density seems to decrease slightly in comparison with untreated samples. However, for the highest irradiating laser powers a new bulk level at 0.41 eV above the valence band with concentrations up to 1015 cm-3 arises probably due to the electrical activation of the oxygen diluted in the Czochralski silicon. Later postmetallization annealings reduce the interface state density to values in the 1010 cm-2 eV-1 range but leave the concentration of the 0.41-eV center nearly unchanged.

  19. Experimental and theoretical studies of the energy level structure of multiply charged many-electron ions

    International Nuclear Information System (INIS)

    Redfors, A.

    1991-01-01

    Magnesiumlike and aluminumlike spectra of the elements calcium - germanium have been obtained through the use of laser-produced plasmas (LPP) and a 3 m normal incidence vacuum spectrograph. The spectral analyses were mainly based on isoelectronic regularities. Intermediate ionization stages of cerium (Ce V) and silicon (SI VI) have also been studied. The light sources in these cases were a sliding spark and a modified version of the LPP. The Eagle spectrograph at the National Institute of Standards and Technology, Gaitherburg, Maryland was used to record the cerium spectrum. Ab initio calculations and least-squares fits of the Slater energy parameters to the experimental energy levels are reported for all investigated spectra. Theoretical predictions of oscillator strengths for Y III and Zr III in the region 1150-3200 AA are presented. The oscillator strengths are needed for abundance determinations of Y 2+ and Zr 2+ in chemically peculiar stars, Cp stars. (65 refs.)

  20. Dependence levels in users of electronic cigarettes, nicotine gums and tobacco cigarettes.

    Science.gov (United States)

    Etter, Jean-François; Eissenberg, Thomas

    2015-02-01

    To assess dependence levels in users of e-cigarettes, and compare them with dependence levels in users of nicotine gums and tobacco cigarettes. Self-reports from cross-sectional Internet and mail surveys. Comparisons of: (a) 766 daily users of nicotine-containing e-cigarettes with 30 daily users of nicotine-free e-cigarettes; (b) 911 former smokers who used the e-cigarette daily with 451 former smokers who used the nicotine gum daily (but no e-cigarette); (c) 125 daily e-cigarette users who smoked daily (dual users) with two samples of daily smokers who did not use e-cigarettes (2206 enrolled on the Internet and 292 enrolled by mail from the general population of Geneva). We used the Fagerström test for nicotine dependence, the nicotine dependence syndrome scale, the cigarette dependence scale and versions of these scales adapted for e-cigarettes and nicotine gums. Dependence ratings were slightly higher in users of nicotine-containing e-cigarettes than in users of nicotine-free e-cigarettes. In former smokers, long-term (>3 months) users of e-cigarettes were less dependent on e-cigarettes than long-term users of the nicotine gum were dependent on the gum. There were few differences in dependence ratings between short-term (≤3 months) users of gums or e-cigarettes. Dependence on e-cigarettes was generally lower in dual users than dependence on tobacco cigarettes in the two other samples of daily smokers. Some e-cigarette users were dependent on nicotine-containing e-cigarettes, but these products were less addictive than tobacco cigarettes. E-cigarettes may be as or less addictive than nicotine gums, which themselves are not very addictive. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  1. Wave propagation in elastic solids

    CERN Document Server

    Achenbach, Jan

    1984-01-01

    The propagation of mechanical disturbances in solids is of interest in many branches of the physical scienses and engineering. This book aims to present an account of the theory of wave propagation in elastic solids. The material is arranged to present an exposition of the basic concepts of mechanical wave propagation within a one-dimensional setting and a discussion of formal aspects of elastodynamic theory in three dimensions, followed by chapters expounding on typical wave propagation phenomena, such as radiation, reflection, refraction, propagation in waveguides, and diffraction. The treat

  2. PSCAD modeling of a two-level space vector pulse width modulation algorithm for power electronics education

    Directory of Open Access Journals (Sweden)

    Ahmet Mete Vural

    2016-09-01

    Full Text Available This paper presents the design details of a two-level space vector pulse width modulation algorithm in PSCAD that is able to generate pulses for three-phase two-level DC/AC converters with two different switching patterns. The presented FORTRAN code is generic and can be easily modified to meet many other kinds of space vector modulation strategies. The code is also editable for hardware programming. The new component is tested and verified by comparing its output as six gating signals with those of a similar component in MATLAB library. Moreover the component is used to generate digital signals for closed-loop control of STATCOM for reactive power compensation in PSCAD. This add-on can be an effective tool to give students better understanding of the space vector modulation algorithm for different control tasks in power electronics area, and can motivate them for learning.

  3. Temporal scaling in information propagation

    Science.gov (United States)

    Huang, Junming; Li, Chao; Wang, Wen-Qiang; Shen, Hua-Wei; Li, Guojie; Cheng, Xue-Qi

    2014-06-01

    For the study of information propagation, one fundamental problem is uncovering universal laws governing the dynamics of information propagation. This problem, from the microscopic perspective, is formulated as estimating the propagation probability that a piece of information propagates from one individual to another. Such a propagation probability generally depends on two major classes of factors: the intrinsic attractiveness of information and the interactions between individuals. Despite the fact that the temporal effect of attractiveness is widely studied, temporal laws underlying individual interactions remain unclear, causing inaccurate prediction of information propagation on evolving social networks. In this report, we empirically study the dynamics of information propagation, using the dataset from a population-scale social media website. We discover a temporal scaling in information propagation: the probability a message propagates between two individuals decays with the length of time latency since their latest interaction, obeying a power-law rule. Leveraging the scaling law, we further propose a temporal model to estimate future propagation probabilities between individuals, reducing the error rate of information propagation prediction from 6.7% to 2.6% and improving viral marketing with 9.7% incremental customers.

  4. Human- Versus System-Level Factors and Their Effect on Electronic Work List Variation: Challenging Radiology's Fundamental Attribution Error.

    Science.gov (United States)

    Davenport, Matthew S; Khalatbari, Shokoufeh; Platt, Joel F

    2015-09-01

    The aim of this study was to analyze sources of variation influencing the unread volume on an electronic abdominopelvic CT work list and to compare those results with blinded radiologist perception. The requirement for institutional review board approval was waived for this HIPAA-compliant quality improvement effort. Data pertaining to an electronic abdominopelvic CT work list were analyzed retrospectively from July 1, 2013, to June 30, 2014, and modeled with respect to the unread case total at 6 pm (Monday through Friday, excluding holidays). Eighteen system-level factors outside individual control (eg, number of workers, workload) and 7 human-level factors within individual control (eg, individual productivity) were studied. Attending radiologist perception was assessed with a blinded anonymous survey (n = 12 of 15 surveys completed). The mean daily unread total was 24 (range, 3-72). The upper control limit (48 CT studies [3 SDs above the mean]) was exceeded 10 times. Multivariate analysis revealed that the rate of unread CT studies was affected principally by system-level factors, including the number of experienced trainees on service (postgraduate year 5 residents [odds ratio, 0.83; 95% confidence interval, 0.74-0.92; P = .0008] and fellows [odds ratio, 0.84; 95% confidence interval, 0.74-0.95; P = .005]) and the daily workload (P = .02 to P level factors best predict the variation in unread CT examinations, but blinded faculty radiologists believe that it relates most strongly to variable individual effort. Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  5. Electronic couplings for molecular charge transfer: Benchmarking CDFT, FODFT, and FODFTB against high-level ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kubas, Adam; Blumberger, Jochen, E-mail: j.blumberger@ucl.ac.uk [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Hoffmann, Felix [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Universitätsstr. 150, 44801 Bochum (Germany); Heck, Alexander; Elstner, Marcus [Institute of Physical Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe (Germany); Oberhofer, Harald [Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85747 Garching (Germany)

    2014-03-14

    We introduce a database (HAB11) of electronic coupling matrix elements (H{sub ab}) for electron transfer in 11 π-conjugated organic homo-dimer cations. High-level ab inito calculations at the multireference configuration interaction MRCI+Q level of theory, n-electron valence state perturbation theory NEVPT2, and (spin-component scaled) approximate coupled cluster model (SCS)-CC2 are reported for this database to assess the performance of three DFT methods of decreasing computational cost, including constrained density functional theory (CDFT), fragment-orbital DFT (FODFT), and self-consistent charge density functional tight-binding (FODFTB). We find that the CDFT approach in combination with a modified PBE functional containing 50% Hartree-Fock exchange gives best results for absolute H{sub ab} values (mean relative unsigned error = 5.3%) and exponential distance decay constants β (4.3%). CDFT in combination with pure PBE overestimates couplings by 38.7% due to a too diffuse excess charge distribution, whereas the economic FODFT and highly cost-effective FODFTB methods underestimate couplings by 37.6% and 42.4%, respectively, due to neglect of interaction between donor and acceptor. The errors are systematic, however, and can be significantly reduced by applying a uniform scaling factor for each method. Applications to dimers outside the database, specifically rotated thiophene dimers and larger acenes up to pentacene, suggests that the same scaling procedure significantly improves the FODFT and FODFTB results for larger π-conjugated systems relevant to organic semiconductors and DNA.

  6. Electronics for CMS Endcap Muon Level-1 Trigger System Phase-1 and HL LHC Upgrades Summary

    CERN Document Server

    Madorsky, Alexander

    2017-01-01

    To accommodate high-luminosity LHC operation at 13 TeV collision energy, the CMS Endcap Muon Level-1 Trigger system had to be significantly modified. To provide the best track reconstruction, the trigger system must now import all available trigger primitives generated by Cathode Strip Chambers and by certain other subsystems, such as Resistive Plate Chambers (RPC). In addition to massive input bandwidth, this also required significant increase in logic and memory resources.To satisfy these requirements, a new Sector Processor unit has been designed. It consists of three modules. The Core Logic module houses the large FPGA that contains the track-finding logic and multi-gigabit serial links for data exchange. The Optical module contains optical receivers and transmitters; it communicates with the Core Logic module via a custom backplane section. The Pt Lookup Table (PTLUT) module contains 1 GB of low-latency memory that is used to assign the final Pt to reconstructed muon tracks. The µTCA architecture (ado...

  7. Role of Off-Line-of-Sight Propagation in Geomagnetic EMP Formation

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Hans W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-05-23

    The author’s synchrotron radiation based 3D geomagnetic EMP code MACSYNC has been used to explore the impact on pulse rise time and air conductivity of EMP propagation paths to the observer that are located off the direct line-of-sight (LOS) between gamma source and observer. This geometry is always present because, for an isotropic source, most the gammas are emitted at an angle with respect to the LOS. Computations for a 1 kt near-surface burst observed from space yield two principal findings: 1. The rise time is generated by the combined actions of a) electron spreading along the LOS due to the Compton electron emission angular distribution folded with electron multiple scattering effects, and b) radiation arrival time spreading due to length differences for different off-LOS propagation paths. The pulse rise time does not depend on the rise time of the conductivity. The conductivity rise time determines the pulse amplitude. 2. One-dimensional legacy EMP codes are inherently incapable of producing the correct pulse shape because they cannot treat the dependence of the conductivity on two dimensions, i.e. the radius from the source and the angle of the propagation path with the LOS. This divergence from one-dimensionality begins at a small fraction of a nanosecond for a sea-level burst. This effect will also be present in high-altitude bursts, however, determination of its onset time and magnitude requires high-altitude computations which have not yet been done.

  8. Enhancement of in vitro Guayule propagation

    Science.gov (United States)

    Dastoor, M. N.; Schubert, W. W.; Petersen, G. R. (Inventor)

    1982-01-01

    A method for stimulating in vitro propagation of Guayule from a nutrient medium containing Guayule tissue by adding a substituted trialkyl amine bioinducing agent to the nutrient medium is described. Selective or differentiated propagation of shoots or callus is obtained by varying the amounts of substituted trialky amine present in the nutrient medium. The luxuriant growth provided may be processed for its poly isoprene content or may be transferred to a rooting medium for production of whole plants as identical clones of the original tissue. The method also provides for the production of large numbers of Guayule plants having identical desirable properties such as high polyisoprene levels.

  9. Laser beam trapping and propagation in cylindrical plasma columns

    International Nuclear Information System (INIS)

    Feit, M.D.; Fleck, J.A. Jr.

    1976-01-01

    An analysis of the scheme to heat magnetically confined plasma columns to kilovolt temperatures with a laser beam requires consideration of two propagation problems. The first question to be answered is whether stable beam trapping is possible. Since the laser beam creates its own density profile by heating the plasma, the propagation of the beam becomes a nonlinear phenomenon, but not necessarily a stable one. In addition, the electron density at a given time depends on the preceding history of both the medium and the laser pulse. A self-consistent time dependent treatment of the beam propagation and the medium hydrodynamics is consequently required to predict the behavior of the laser beam. Such calculations have been carried out and indicate that propagation of a laser beam in an initially uniform plasma can form a stable filament which alternately focuses and defocuses. An additional question that is discussed is whether diffractive losses associated with long propagation paths are significant

  10. Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption.

    Science.gov (United States)

    Li, Yongfang

    2012-05-15

    Bulk heterojunction (BHJ) polymer solar cells (PSCs) sandwich a blend layer of conjugated polymer donor and fullerene derivative acceptor between a transparent ITO positive electrode and a low work function metal negative electrode. In comparison with traditional inorganic semiconductor solar cells, PSCs offer a simpler device structure, easier fabrication, lower cost, and lighter weight, and these structures can be fabricated into flexible devices. But currently the power conversion efficiency (PCE) of the PSCs is not sufficient for future commercialization. The polymer donors and fullerene derivative acceptors are the key photovoltaic materials that will need to be optimized for high-performance PSCs. In this Account, I discuss the basic requirements and scientific issues in the molecular design of high efficiency photovoltaic molecules. I also summarize recent progress in electronic energy level engineering and absorption spectral broadening of the donor and acceptor photovoltaic materials by my research group and others. For high-efficiency conjugated polymer donors, key requirements are a narrower energy bandgap (E(g)) and broad absorption, relatively lower-lying HOMO (the highest occupied molecular orbital) level, and higher hole mobility. There are three strategies to meet these requirements: D-A copolymerization for narrower E(g) and lower-lying HOMO, substitution with electron-withdrawing groups for lower-lying HOMO, and two-dimensional conjugation for broad absorption and higher hole mobility. Moreover, better main chain planarity and less side chain steric hindrance could strengthen π-π stacking and increase hole mobility. Furthermore, the molecular weight of the polymers also influences their photovoltaic performance. To produce high efficiency photovoltaic polymers, researchers should attempt to increase molecular weight while maintaining solubility. High-efficiency D-A copolymers have been obtained by using benzodithiophene (BDT), dithienosilole

  11. Measuring propagation speed of Coulomb fields

    Energy Technology Data Exchange (ETDEWEB)

    Sangro, R. de; Finocchiaro, G.; Patteri, P.; Piccolo, M.; Pizzella, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Frascati (Italy)

    2015-03-01

    The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planet motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Lienard-Weichert retarded potential leads to the same formula as the one obtained assuming that the electric field propagate with infinite velocity. The Feynman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformly moving electron beam. The results we obtain, on a finite lifetime kinematical state, are compatible with an electric field rigidly carried by the beam itself. (orig.)

  12. Communication: The ground electronic state of Si2C: Rovibrational level structure, quantum monodromy, and astrophysical implications

    International Nuclear Information System (INIS)

    Reilly, Neil J.; Kokkin, Damian L.; McCarthy, Michael C.; Changala, P. Bryan; Baraban, Joshua H.; Stanton, John F.

    2015-01-01

    We report the gas-phase optical detection of Si 2 C near 390 nm and the first experimental investigation of the rovibrational structure of its 1 A 1 ground electronic state using mass-resolved and fluorescence spectroscopy and variational calculations performed on a high-level ab initio potential. From this joint study, it is possible to assign all observed K a = 1 vibrational levels up to 3800 cm −1 with confidence, as well as a number of levels in the K a = 0, 2,  and 3 manifolds. Dixon-dip plots for the bending coordinate (ν 2 ) allow an experimental determination of a barrier to linearity of 783(48) cm −1 (2σ), in good agreement with theory (802(9) cm −1 ). The calculated (K a , ν 2 ) eigenvalue lattice shows an archetypal example of quantum monodromy (absence of a globally valid set of quantum numbers) that is reflected by the experimentally observed rovibrational levels. The present study provides a solid foundation for infrared and optical surveys of Si 2 C in astronomical objects, particularly in the photosphere of N- and J-type carbon stars where the isovalent SiC 2 molecule is known to be abundant

  13. Propagation speed of gamma radiation in brass

    International Nuclear Information System (INIS)

    Cavalcante, Jose T.P.D.; Silva, Paulo R.J.; Saitovich, Henrique

    2009-01-01

    The propagation speed (PS) of visible light -represented by a short frequency range in the large frame of electromagnetic radiations (ER) frequencies- in air was measured during the last century, using a great deal of different methods, with high precision results being achieved. Presently, a well accepted value, with very small uncertainty, is c= 299,792.458 Km/s) (c reporting to the Latin word celeritas: 'speed swiftness'). When propagating in denser material media (MM), such value is always lower when compared to the air value, with the propagating MM density playing an important role. Until present, such studies focusing propagation speeds, refractive indexes, dispersions were specially related to visible light, or to ER in wavelengths ranges dose to it, and with a transparent MM. A first incursion in this subject dealing with γ-rays was performed using an electronic coincidence counting system, when the value of it's PS was measured in air, C γ(air) 298,300.15 Km/s; a method that went on with later electronic improvements. always in air. To perform such measurements the availability of a γ-radiation source in which two γ-rays are emitted simultaneously in opposite directions -as already used as well as applied in the present case- turns out to be essential to the feasibility of the experiment, as far as no reflection techniques could be used. Such a suitable source was the positron emitter 22 Na placed in a thin wall metal container in which the positrons are stopped and annihilated when reacting with the medium electrons, in such way originating -as it is very well established from momentum/energy conservation laws - two gamma-rays, energy 511 KeV each, both emitted simultaneously in opposite directions. In all the previous experiments were used photomultiplier detectors coupled to NaI(Tl) crystal scintillators, which have a good energy resolution but a deficient time resolution for such purposes. Presently, as an innovative improvement, were used BaF 2

  14. Electronic structure of deep levels in silicon. A study of gold, magnesium, and iron centers in silicon

    International Nuclear Information System (INIS)

    Thilderkvist, A. L.

    1994-02-01

    The electronic structure of gold, magnesium and iron related deep centers in silicon is investigated. Their deep and shallow levels are studied by means of fourier transform spectroscopy, combined with uniaxial stress and Zeeman spectroscopy. The neutral substitutional gold center in silicon is investigated and the center is paramagnetic, S=1/2, with g||≅2.8 and g≅0, and has a static distortion. Reorientation between different equivalent distortions is observed even at 1.9 K. A gold pair center in silicon is studied and several line series, with a zero-phonon line followed by several phonon replicas, are observed. Uniaxial stress and Zeeman results reveal a trigonal symmetry of the center, which together with the high dissociation energy of 1.7 eV suggests that the center consists of two nearest-neighbor substitutional gold atoms. A divacancy model is employed to explain the electronic properties of the center. The interstitial magnesium double donor in silicon in its two charge states Mg o and Mg + is investigated. Deviations in the binding energies of the excited states from those calculated within the effective-mass theory (EMT) are found and explained by a perturbation in the central-cell region. The quadratic Zeeman effect of shallow donors in silicon is analyzed within the framework of the EMT using a numerical approach. The wave functions are calculated in a discrete radial mesh and the Zeeman Hamiltonian has be evaluated for the lowest excited states for fields up to 6 T. The neutral interstitial iron defect in silicon gives rise to two sets of line spectra. The first set arises when an electron is excited to a shallow donor like state where the electron is decoupled from the Fe + core which has a 4 T 1 ground state term. The second set arises when an excited electron of a 1 symmetry is coupled by exchange interaction to the core, yielding at 5 T 1 final state. Experiments determine the multiplet splitting of the 4 T 1 and 5 T 1 states due to spring

  15. Excitation of propagating surface plasmons with a scanning tunnelling microscope.

    Science.gov (United States)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

    2011-04-29

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10  µm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  16. Faraday tarotion: new parameter for electromagnetic pulse propagation in magnetoplasma

    International Nuclear Information System (INIS)

    Bloch, S.C.; Lyons, P.W.

    1976-01-01

    Extreme distortion and time-dependent Faraday rotation occur for propagation of short electromagnetic pulses in magnetoplasma, for some ranges of plasma parameters. In order to relate pulse and monochromatic waves for propagation-path diagnostic purposes, a new parameter is introduced for the transmitted pulse train which has properties that correspond very accurately to results that would be expected for Faraday rotation of a continuous wave having the central frequency of the incident pulse spectrum. Results for 5-ns pulses (10 GHz) are presented for varying propagating length, static magnetic field, electron density, and collisional absorption

  17. Beam propagation considerations in the Aurora laser system

    International Nuclear Information System (INIS)

    Rosoche, L.A.; Mc Leod, J.; Hanlon, J.A.

    1987-01-01

    Aurora is a high-power KrF laser system now being constructed for inertial confinement fusion (ICF) studies. It will use optical angular multiplexing and serial amplification by electron-beam-driven KrF amplifiers to deliver a stacked, multikilojoule 5-ns-duration laser pulse to ICF targets. The requirements of angular multiplexing KrF lasers at the multikilojoule level dictate path lengths on the order of 1 km. The inherent complicated path crossings produced by angular multiplexing and pulse stacking do not allow isolation of individual beam lines, so the optical quality of the long beam paths must be controlled. Propagation of the 248-nm light beams over long paths in air is affected by scattering, absorption thermal gradients and turbulence, beam alignment, and control and optical component figure errors

  18. Two-Level Chebyshev Filter Based Complementary Subspace Method: Pushing the Envelope of Large-Scale Electronic Structure Calculations.

    Science.gov (United States)

    Banerjee, Amartya S; Lin, Lin; Suryanarayana, Phanish; Yang, Chao; Pask, John E

    2018-06-12

    We describe a novel iterative strategy for Kohn-Sham density functional theory calculations aimed at large systems (>1,000 electrons), applicable to metals and insulators alike. In lieu of explicit diagonalization of the Kohn-Sham Hamiltonian on every self-consistent field (SCF) iteration, we employ a two-level Chebyshev polynomial filter based complementary subspace strategy to (1) compute a set of vectors that span the occupied subspace of the Hamiltonian; (2) reduce subspace diagonalization to just partially occupied states; and (3) obtain those states in an efficient, scalable manner via an inner Chebyshev filter iteration. By reducing the necessary computation to just partially occupied states and obtaining these through an inner Chebyshev iteration, our approach reduces the cost of large metallic calculations significantly, while eliminating subspace diagonalization for insulating systems altogether. We describe the implementation of the method within the framework of the discontinuous Galerkin (DG) electronic structure method and show that this results in a computational scheme that can effectively tackle bulk and nano systems containing tens of thousands of electrons, with chemical accuracy, within a few minutes or less of wall clock time per SCF iteration on large-scale computing platforms. We anticipate that our method will be instrumental in pushing the envelope of large-scale ab initio molecular dynamics. As a demonstration of this, we simulate a bulk silicon system containing 8,000 atoms at finite temperature, and obtain an average SCF step wall time of 51 s on 34,560 processors; thus allowing us to carry out 1.0 ps of ab initio molecular dynamics in approximately 28 h (of wall time).

  19. The Effect of Electronic Devices Self-Efficacy, Electronic Devices Usage and Information Security Awareness on Identity-Theft Anxiety Level

    Science.gov (United States)

    Sanga, Sushma

    2016-01-01

    Identity-theft means stealing someone's personal information and using it without his or her permission. Each year, millions of Americans are becoming the victims of identity-theft, and this is one of the seriously growing and widespread issues in the U.S. This study examines the effect of electronic devices self-efficacy, electronic devices…

  20. Farmers' Market Manager's Level of Communication and Influence on Electronic Benefits Transfer (EBT) Adoption at Midwest Farmers' Markets.

    Science.gov (United States)

    Hasin, Afroza; Smith, Sylvia

    2018-01-01

    To understand market managers' level of communication and use of technology that might influence decision to adopt Electronic Benefits Transfer (EBT) at farmers' markets. Cross-sectional study using the Theory of Diffusion of Innovation. Electronic survey administered in midwest states of Illinois, Michigan, and Wisconsin. Farmers' market managers in Illinois, Michigan, and Wisconsin. Information on EBT adoption, market managers' communication, and technology use. Binary logistic regression analysis with EBT adoption as the dependent variable and frequency of technology use, partnership with organizations, farmers' market association (FMA) membership, Facebook page and Web site for the market, and primary source of information as independent variables. Chi-square tests and ANOVA were used to compare states and adopter categories. Logistic regression results showed that the odds of adopting EBT was 7.5 times higher for markets that had partnership with other organizations. Compared with non-adopters, a significantly greater number of early adopters had partnership, FMA membership, and a Facebook page and Web site for market, and reported to a board of directors. Markets that had partnership, FMA membership, a Facebook page and Web site, and mandatory reporting to a board of directors were important factors that influenced EBT adoption at midwest farmers' markets. Copyright © 2017 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

  1. The uniformity study of non-oxide thin film at device level using electron energy loss spectroscopy

    Science.gov (United States)

    Li, Zhi-Peng; Zheng, Yuankai; Li, Shaoping; Wang, Haifeng

    2018-05-01

    Electron energy loss spectroscopy (EELS) has been widely used as a chemical analysis technique to characterize materials chemical properties, such as element valence states, atoms/ions bonding environment. This study provides a new method to characterize physical properties (i.e., film uniformity, grain orientations) of non-oxide thin films in the magnetic device by using EELS microanalysis on scanning transmission electron microscope. This method is based on analyzing white line ratio of spectra and related extended energy loss fine structures so as to correlate it with thin film uniformity. This new approach can provide an effective and sensitive method to monitor/characterize thin film quality (i.e., uniformity) at atomic level for thin film development, which is especially useful for examining ultra-thin films (i.e., several nanometers) or embedded films in devices for industry applications. More importantly, this technique enables development of quantitative characterization of thin film uniformity and it would be a remarkably useful technique for examining various types of devices for industrial applications.

  2. Yeast cytochrome c integrated with electronic elements: a nanoscopic and spectroscopic study down to single-molecule level

    International Nuclear Information System (INIS)

    Delfino, I; Bonanni, B; Andolfi, L; Baldacchini, C; Bizzarri, A R; Cannistraro, S

    2007-01-01

    Various aspects of redox protein integration with nano-electronic elements are addressed by a multi-technique investigation of different yeast cytochrome c (YCC)-based hybrid systems. Three different immobilization strategies on gold via organic linkers are explored, involving either covalent bonding or electrostatic interaction. Specifically, Au surfaces are chemically modified by self-assembled monolayers (SAMs) exposing thiol-reactive groups, or by acid-oxidized single-wall carbon nanotubes (SWNTs). Atomic force microscopy and scanning tunnelling microscopy are employed to characterize the morphology and the electronic properties of single YCC molecules adsorbed on the modified gold surfaces. In each hybrid system, the protein molecules are stably assembled, in a native configuration. A standing-up arrangement of YCC on SAMs is suggested, together with an enhancement of the molecular conduction, as compared to YCC directly assembled on gold. The electrostatic interaction with functionalized SWNTs allows several YCC adsorption geometries, with a preferential high-spin haem configuration, as outlined by Raman spectroscopy. Moreover, the conduction properties of YCC, explored in different YCC nanojunctions by conductive atomic force microscopy, indicate the effectiveness of electrical conduction through the molecule and its dependence on the electrode material. The joint employment of several techniques confirms the key role of a well-designed immobilization strategy, for optimizing biorecognition capabilities and electrical coupling with conductive substrates at the single-molecule level, as a starting point for advanced applications in nano-biotechnology

  3. Propagators and path integrals

    Energy Technology Data Exchange (ETDEWEB)

    Holten, J.W. van

    1995-08-22

    Path-integral expressions for one-particle propagators in scalar and fermionic field theories are derived, for arbitrary mass. This establishes a direct connection between field theory and specific classical point-particle models. The role of world-line reparametrization invariance of the classical action and the implementation of the corresponding BRST-symmetry in the quantum theory are discussed. The presence of classical world-line supersymmetry is shown to lead to an unwanted doubling of states for massive spin-1/2 particles. The origin of this phenomenon is traced to a `hidden` topological fermionic excitation. A different formulation of the pseudo-classical mechanics using a bosonic representation of {gamma}{sub 5} is shown to remove these extra states at the expense of losing manifest supersymmetry. (orig.).

  4. Curvilinear crack layer propagation

    Science.gov (United States)

    Chudnovsky, Alexander; Chaoui, Kamel; Moet, Abdelsamie

    1987-01-01

    An account is given of an experiment designed to allow observation of the effect of damage orientation on the direction of crack growth in the case of crack layer propagation, using polystyrene as the model material. The direction of crack advance under a given loading condition is noted to be determined by a competition between the tendency of the crack to maintain its current direction and the tendency to follow the orientation of the crazes at its tip. The orientation of the crazes is, on the other hand, determined by the stress field due to the interaction of the crack, the crazes, and the hole. The changes in craze rotation relative to the crack define the active zone rotation.

  5. Atomistics of crack propagation

    International Nuclear Information System (INIS)

    Sieradzki, K.; Dienes, G.J.; Paskin, A.; Massoumzadeh, B.

    1988-01-01

    The molecular dynamic technique is used to investigate static and dynamic aspects of crack extension. The material chosen for this study was the 2D triangular solid with atoms interacting via the Johnson potential. The 2D Johnson solid was chosen for this study since a sharp crack in this material remains stable against dislocation emission up to the critical Griffith load. This behavior allows for a meaningful comparison between the simulation results and continuum energy theorems for crack extension by appropriately defining an effective modulus which accounts for sample size effects and the non-linear elastic behavior of the Johnson solid. Simulation results are presented for the stress fields of moving cracks and these dynamic results are discussed in terms of the dynamic crack propagation theories, of Mott, Eshelby, and Freund

  6. Broadband unidirectional ultrasound propagation

    Science.gov (United States)

    Sinha, Dipen N.; Pantea, Cristian

    2017-12-12

    A passive, linear arrangement of a sonic crystal-based apparatus and method including a 1D sonic crystal, a nonlinear medium, and an acoustic low-pass filter, for permitting unidirectional broadband ultrasound propagation as a collimated beam for underwater, air or other fluid communication, are described. The signal to be transmitted is first used to modulate a high-frequency ultrasonic carrier wave which is directed into the sonic crystal side of the apparatus. The apparatus processes the modulated signal, whereby the original low-frequency signal exits the apparatus as a collimated beam on the side of the apparatus opposite the sonic crystal. The sonic crystal provides a bandpass acoustic filter through which the modulated high-frequency ultrasonic signal passes, and the nonlinear medium demodulates the modulated signal and recovers the low-frequency sound beam. The low-pass filter removes remaining high-frequency components, and contributes to the unidirectional property of the apparatus.

  7. Propagation into an unstable state

    International Nuclear Information System (INIS)

    Dee, G.

    1985-01-01

    We describe propagating front solutions of the equations of motion of pattern-forming systems. We make a number of conjectures concerning the properties of such fronts in connection with pattern selection in these systems. We describe a calculation which can be used to calculate the velocity and state selected by certain types of propagating fronts. We investigate the propagating front solutions of the amplitude equation which provides a valid dynamical description of many pattern-forming systems near onset

  8. The level of the usage of the human resource information system and electronic recruitment in Croatian companies

    Directory of Open Access Journals (Sweden)

    Snježana Pivac

    2014-12-01

    Full Text Available Performing business according to contemporary requirements influences companies for continuous usage of modern managerial tools, such as a human resource information system (HRIS and electronic recruitment (ER. Human resources have been recognised as curtail resources and the main source of a competitive advantage in creation of successful business performance. In order to attract and select the top employees, companies use quality information software for attracting internal ones, and electronic recruitment for attracting the best possible external candidates. The main aim of this paper is to research the level of the usage of HRIS and ER within medium-size and large Croatian companies. Moreover, the additional aim of this paper is to evaluate the relationship among the usage of these modern managerial tools and the overall success of human resource management within these companies. For the purpose of this paper, primary and secondary research has been conducted in order to reveal the level of the usage of HRIS and ER as well as the overall success of human resource management in Croatian companies. The companies’ classification (HRIS and ER is done by using the non-hierarchical k-means cluster method as well as the nonparametric Kruskal Wallis test. Further, the companies are ranked by the multicriteria PROMETHEE method. Relevant nonparametric tests are used for testing the overall companies’ HRM. Finally, binary logistic regression is estimated, relating binary variable HRM and HRIS development. After detailed research, it can be concluded that large Croatian companies apply HRIS in majority (with a positive relation to HRM performance, but still require certain degrees of its development.

  9. In situ atomic-level observation of the formation of platinum silicide at platinum-silicon oxide interfaces under electron irradiation

    Directory of Open Access Journals (Sweden)

    Takeshi Nagase

    2018-05-01

    Full Text Available In situ atomic-level observation of the formation of Pt2Si at Pt/SiOx interface by electronic excitation under electron irradiation was performed by using scanning transmission electron microscopy. Scanning of an electron-beam probe stimulates silicide formation at the Pt/SiOx interface; the change in the Pt column corresponding to Pt2Si formation with a crystallographic orientation of (001Pt//(001Pt2Si and [110]Pt//[110]Pt2Si was observed in high-angle annular dark-field images.

  10. The effects of electronic cigarette emissions on systemic cotinine levels, weight and postnatal lung growth in neonatal mice.

    Directory of Open Access Journals (Sweden)

    Sharon A McGrath-Morrow

    Full Text Available Electronic cigarette (E-cigarettes emissions present a potentially new hazard to neonates through inhalation, dermal and oral contact. Exposure to nicotine containing E-cigarettes may cause significant systemic absorption in neonates due to the potential for multi-route exposure. Systemic absorption of nicotine and constituents of E-cigarette emissions may adversely impact weight and lung development in the neonate. To address these questions we exposed neonatal mice to E-cigarette emissions and measured systemic cotinine levels and alveolar lung growth.Neonatal mice were exposed to E-cigarettes for the first 10 days of life. E-cigarette cartridges contained either 1.8% nicotine in propylene glycol (PG or PG vehicle alone. Daily weights, plasma and urine cotinine levels and lung growth using the alveolar mean linear intercept (MLI method were measured at 10 days of life and compared to room air controls. Mice exposed to 1.8% nicotine/PG had a 13.3% decrease in total body weight compared to room air controls. Plasma cotinine levels were found to be elevated in neonatal mice exposed to 1.8% nicotine/PG E-cigarettes (mean 62.34± 3.3 ng/ml. After adjusting for sex and weight, the nicotine exposed mice were found to have modestly impaired lung growth by MLI compared to room air control mice (p<.054 trial 1; p<.006 trial 2. These studies indicate that exposure to E-cigarette emissions during the neonatal period can adversely impact weight gain. In addition exposure to nicotine containing E-cigarettes can cause detectable levels of systemic cotinine, diminished alveolar cell proliferation and a modest impairment in postnatal lung growth.

  11. Small rural emergency services can electronically collect accurate episode-level data: A cross-sectional study.

    Science.gov (United States)

    Dawson, Samantha L; Baker, Tim; Salzman, Scott

    2015-04-01

    There is little evidence that useful electronic data could be collected at Australian small rural emergency services. If in future their funding model changed to the Activity-Based Funding model, then they would need to collect and submit more data. We determine whether it is possible to collect episode-level data at six small rural emergency services and quantify the accuracy of eight fields. A prospective cross-sectional study. South-West Victoria, Australia. Six small rural emergency services. We collected and audited episode-level emergency data from participating services between 1 February 2011 and 31 January 2012. A random sample of these data were audited monthly. Research assistants located at each service supported data entry and audited data accuracy for four hours per week. Rates for data completeness, accuracy and total accuracy were calculated using audit data. Episode-level data were collected for 20 224 presentations across six facilities. The audit dataset consisted of 8.5% (1504/17 627) of presentations from five facilities. For all fields audited, the accuracy of entered data was high (>93%).Triage category was deemed appropriate for 95.9% (95% confidence interval (CI): 94.9-96.9%) of the patient records reviewed. Some procedures were missing (28.7%, 95%CI: 27.2-30.3%). No significant improvement in data accuracy over 12 months was observed. All six services collected useful episode-level data for 12-months with four hours per week of assistance. Data entry accuracy was high for all fields audited, and data entry completeness was low for procedures. © 2015 National Rural Health Alliance Inc.

  12. The effects of electronic cigarette emissions on systemic cotinine levels, weight and postnatal lung growth in neonatal mice.

    Science.gov (United States)

    McGrath-Morrow, Sharon A; Hayashi, Madoka; Aherrera, Angela; Lopez, Armando; Malinina, Alla; Collaco, Joseph M; Neptune, Enid; Klein, Jonathan D; Winickoff, Jonathan P; Breysse, Patrick; Lazarus, Philip; Chen, Gang

    2015-01-01

    Electronic cigarette (E-cigarettes) emissions present a potentially new hazard to neonates through inhalation, dermal and oral contact. Exposure to nicotine containing E-cigarettes may cause significant systemic absorption in neonates due to the potential for multi-route exposure. Systemic absorption of nicotine and constituents of E-cigarette emissions may adversely impact weight and lung development in the neonate. To address these questions we exposed neonatal mice to E-cigarette emissions and measured systemic cotinine levels and alveolar lung growth. Neonatal mice were exposed to E-cigarettes for the first 10 days of life. E-cigarette cartridges contained either 1.8% nicotine in propylene glycol (PG) or PG vehicle alone. Daily weights, plasma and urine cotinine levels and lung growth using the alveolar mean linear intercept (MLI) method were measured at 10 days of life and compared to room air controls. Mice exposed to 1.8% nicotine/PG had a 13.3% decrease in total body weight compared to room air controls. Plasma cotinine levels were found to be elevated in neonatal mice exposed to 1.8% nicotine/PG E-cigarettes (mean 62.34± 3.3 ng/ml). After adjusting for sex and weight, the nicotine exposed mice were found to have modestly impaired lung growth by MLI compared to room air control mice (pE-cigarette emissions during the neonatal period can adversely impact weight gain. In addition exposure to nicotine containing E-cigarettes can cause detectable levels of systemic cotinine, diminished alveolar cell proliferation and a modest impairment in postnatal lung growth.

  13. Multi-level multi-thermal-electron FDTD simulation of plasmonic interaction with semiconducting gain media: applications to plasmonic amplifiers and nano-lasers.

    Science.gov (United States)

    Chen, X; Bhola, B; Huang, Y; Ho, S T

    2010-08-02

    Interactions between a semiconducting gain medium and confined plasmon-polaritons are studied using a multilevel multi-thermal-electron finite-difference time-domain (MLMTE-FDTD) simulator. We investigated the amplification of wave propagating in a plasmonic metal-semiconductor-metal (MSM) waveguide filled with semiconductor gain medium and obtained the conditions required to achieve net optical gain. The MSM gain waveguide is used to form a plasmonic semiconductor nano-ring laser(PSNRL) with an effective mode volume of 0.0071 microm3, which is about an order of magnitude smaller than the smallest demonstrated integrated photonic crystal based laser cavities. The simulation shows a lasing threshold current density of 1kA/cm2 for a 300 nm outer diameter ring cavity with 80 nm-wide ring. This current density can be realistically achieved in typical III-V semiconductor, which shows the experimental feasibility of the proposed PSNRL structure.

  14. Study of electron and ion fluxes in a microsecond plasma switch during current switch phase at power level of 0,2TW

    International Nuclear Information System (INIS)

    Anan'in, P.S.; Bystritskij, V.M.; Karpov, V.B.; Krasik, Ya.E.; Lisitsin, I.V.; Sinebryukhov, A.A.

    1991-01-01

    Results of experimental study of dynamics of electron and ion losses in a microsecond plasma switch (PS), carring the short-circuited inductance load and operating with open potential electrode, are presented. Investigations were carried out at 'DUBL' microsecond generator with stored energy of 56 kJ and 300 kA current amplitude in inductive storage. The investigations showed that primary channel of energy losses, limiting microsecond plasma switch impedance, are energy losses: they constitute 70% of all losses under inductive load and 30% during operation with an open cathode. It was shown that ion current in PS attains its peak value by the end of conductivity phase and it does not increase in switch phase. With an open cathode, PS impedance is defined by an electron beam, forming during current switch phase and propagating towards external electrode end. In this high-current electron beam H + ions, accelerated up to 3.5-4.2 MeV energy, and outcoming from PS plasma boundary, were detected

  15. Propagation effects on radio range and noise in earth-space telecommunications

    Science.gov (United States)

    Flock, W. L.; Slobin, S. D.; Smith, E. K.

    1982-01-01

    Attention is given to the propagation effects on radio range and noise in earth-space telecommunications. The use of higher frequencies minimizes ionospheric effects on propagation, but tropospheric effects often increase or dominate. For paths of geostationary satellites, and beyond, the excess range delay caused by the ionosphere and plasmasphere is proportional to the total electron content along the path and inversely proportional to frequency squared. The delay due to dry air is usually of the order of a few meters while the delay due to water vapor (a few tens of centimeters) is responsible for most of the temporal variation in the range delay for clean air. For systems such as that of the Voyager spacecraft, and for attenuation values up to about 10 dB, increased sky noise degrades the received signal-to-noise ratio more than does the reduction in signal level due to attenuation.

  16. Localized Elf Propagation Anomalies.

    Science.gov (United States)

    1985-06-01

    the above three SPEs. Those important auxiliary data are used as inputs to air- chemistry codes to calculate the electron and ion density height...horizontal magnetic intensity H is H A ( ATAR ) 1 / 2 (9 d)- 1/2 exp(-’afL- d) e- d/ 8 " 7 coso A/m, (1) where A depends on the antenna moment, frequency...those rates are input to air- chemistry equations to obtain height profiles of electron and ion densities. Calculation of ion-pair production rates

  17. Propagating annular modes

    Science.gov (United States)

    Sheshadri, A.; Plumb, R. A.

    2017-12-01

    The leading "annular mode", defined as the dominant EOF of surface pressure or of zonal mean zonal wind variability, appears as a dipolar structure straddling the mean midlatitude jet and thus seems to describe north-south wobbling of the jet latitude. However, extratropical zonal wind anomalies frequently tend to migrate poleward. This behavior can be described by the first two EOFs, the first (AM1) being the dipolar structure, and the second (AM2) having a tripolar structure centered on the mean jet. Taken in isolation, AM1 thus describes a north-south wobbling of the jet position, while AM2 describes a strengthening and narrowing of the jet. However, despite the fact that they are spatially orthogonal, and their corresponding time series temporally orthogonal, AM1 and AM2 are not independent, but show significant lag-correlations which reveal the propagation. The EOFs are not modes of the underlying dynamical system governing the zonal flow evolution. The true modes can be estimated using principal oscillation pattern (POP) analysis. In the troposphere, the leading POPs manifest themselves as a pair of complex conjugate structures with conjugate eigenvalues thus, in reality, constituting a single, complex, mode that describes propagating anomalies. Even though the principal components associated with the two leading EOFs decay at different rates, each decays faster than the true mode. These facts have implications for eddy feedback and the susceptibility of the mode to external perturbations. If one interprets the annular modes as the modes of the system, then simple theory predicts that the response to steady forcing will usually be dominated by AM1 (with the longest time scale). However, such arguments should really be applied to the true modes. Experiments with a simplified GCM show that climate response to perturbations do not necessarily have AM1 structures. Implications of these results for stratosphere-troposphere interactions are explored. The POP

  18. Propagation of highly aberrated laser beams in nonquadratic plasma waveguides

    International Nuclear Information System (INIS)

    Feit, M.D.; Fleck, J.A. Jr.; Morris, J.R.

    1977-01-01

    The propagation of a laser beam in a plasma column several meters long with a realistic electron density distribution is examined. The electron density distribution is based on laser-beam heating at z=0, but is otherwise uncoupled to the laser beam. The aberrated nature of the resulting lenslike medium leads to essentially aperiodic beam properties, which contrast with the completely periodic properties of Gaussian beams propagating in quadratic lenslike media. The beam is nonetheless stably trapped. These aberrated-beam properties also help to stabilize the beam against axial variations in refractive index

  19. Propagation Engineering in Wireless Communications

    CERN Document Server

    Ghasemi, Abdollah; Ghasemi, Farshid

    2012-01-01

    Wireless communications has seen explosive growth in recent decades, in a realm that is both broad and rapidly expanding to include satellite services, navigational aids, remote sensing, telemetering, audio and video broadcasting, high-speed data communications, mobile radio systems and much more. Propagation Engineering in Wireless Communications deals with the basic principles of radiowaves propagation for frequency bands used in radio-communications, offering descriptions of new achievements and newly developed propagation models. The book bridges the gap between theoretical calculations and approaches, and applied procedures needed for advanced radio links design. The primary objective of this two-volume set is to demonstrate the fundamentals, and to introduce propagation phenomena and mechanisms that engineers are likely to encounter in the design and evaluation of radio links of a given type and operating frequency. Volume one covers basic principles, along with tropospheric and ionospheric propagation,...

  20. Is the regulation of the electronic properties of organic molecules by polynuclear superhalogens more effective than that by mononuclear superhalogens? A high-level ab initio case study.

    Science.gov (United States)

    Li, Miao-Miao; Li, Jin-Feng; Bai, Hongcun; Sun, Yin-Yin; Li, Jian-Li; Yin, Bing

    2015-08-21

    The regulation of the electronic properties of organic molecules induced by polynuclear superhalogens is theoretically explored here for sixteen composite structures. It is clearly indicated by the higher vertical electron detachment energy (VDE) that polynuclear superhalogens are more effective in regulating the electronic properties than mononuclear structures. However, this enhanced regulation is not only determined by superhalogens themselves but also related to the distribution of the extra electron of the final composites. The composites, in which the extra electron is mainly aggregated into the superhalogen moiety, will possess higher VDE values, as reported in the case of C1', 7.12 eV at the CCSD(T) level. This is probably due to the fact that, compared with organic molecules, superhalogens possess stronger attraction towards the extra electron and thus should lead to lower energies of the extra electrons and to higher VDE values eventually. Compared with CCSD(T), the Outer Valence Green's Function (OVGF) method fails completely for composite structures containing Cl atoms, while MP2 results are generally consistent in terms of the relative order of VDEs. Actually if the extra electron distribution of the systems could be approximated by the HOMO, the results at the OVGF level will be consistent with the CCSD(T) results. Conversely, the difference in VDEs between OVGF and CCSD(T) is significantly large. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to various fragmentation channels were also investigated for all the composite structures.

  1. Dressing the nucleon propagator

    International Nuclear Information System (INIS)

    Fishman, S.; Gersten, A.

    1976-01-01

    The nucleon propagator in the ''nested bubbles'' approximation is analyzed. The approximation is built from the minimal set of diagrams which is needed to maintain the unitarity condition under two-pion production threshold in the two-nucleon Bethe--Salpeter equation. Recursive formulas for subsets of ''nested bubbles'' diagrams calculated in the framework of the pseudoscalar interaction are obtained by the use of dispersion relations. We prove that the sum of all the ''nested bubbles'' diverges. Moreover, the successive iterations are plagued with ghost poles. We prove that the first approximation--which is the so-called chain approximation--has ghost poles for any nonvanishing coupling constant. In an earlier paper we have shown that ghost poles lead to ghost cuts. These cuts are present in the ''nested bubbles.'' Ghost elimination procedures are discussed. Modifications of the ''nested bubbles'' approximation are introduced in order to obtain convergence and in order to eliminate the ghost poles and ghost cuts. In a similar way as in the Lee model, cutoff functions are introduced in order to eliminate the ghost poles. The necessary and sufficient conditions for the absence of ghost poles are formulated and analyzed. The spectral functions of the modified ''nested bubbles'' are analyzed and computed. Finally, we present a theorem, similar in its form to Levinson's theorem in scattering theory, which enables one to compute in a simple way the number of ghost poles

  2. 100 Million Views of Electronic Cigarette YouTube Videos and Counting: Quantification, Content Evaluation, and Engagement Levels of Videos.

    Science.gov (United States)

    Huang, Jidong; Kornfield, Rachel; Emery, Sherry L

    2016-03-18

    The video-sharing website, YouTube, has become an important avenue for product marketing, including tobacco products. It may also serve as an important medium for promoting electronic cigarettes, which have rapidly increased in popularity and are heavily marketed online. While a few studies have examined a limited subset of tobacco-related videos on YouTube, none has explored e-cigarette videos' overall presence on the platform. To quantify e-cigarette-related videos on YouTube, assess their content, and characterize levels of engagement with those videos. Understanding promotion and discussion of e-cigarettes on YouTube may help clarify the platform's impact on consumer attitudes and behaviors and inform regulations. Using an automated crawling procedure and keyword rules, e-cigarette-related videos posted on YouTube and their associated metadata were collected between July 1, 2012, and June 30, 2013. Metadata were analyzed to describe posting and viewing time trends, number of views, comments, and ratings. Metadata were content coded for mentions of health, safety, smoking cessation, promotional offers, Web addresses, product types, top-selling brands, or names of celebrity endorsers. As of June 30, 2013, approximately 28,000 videos related to e-cigarettes were captured. Videos were posted by approximately 10,000 unique YouTube accounts, viewed more than 100 million times, rated over 380,000 times, and commented on more than 280,000 times. More than 2200 new videos were being uploaded every month by June 2013. The top 1% of most-viewed videos accounted for 44% of total views. Text fields for the majority of videos mentioned websites (70.11%); many referenced health (13.63%), safety (10.12%), smoking cessation (9.22%), or top e-cigarette brands (33.39%). The number of e-cigarette-related YouTube videos was projected to exceed 65,000 by the end of 2014, with approximately 190 million views. YouTube is a major information-sharing platform for electronic cigarettes

  3. 100 Million Views of Electronic Cigarette YouTube Videos and Counting: Quantification, Content Evaluation, and Engagement Levels of Videos

    Science.gov (United States)

    2016-01-01

    Background The video-sharing website, YouTube, has become an important avenue for product marketing, including tobacco products. It may also serve as an important medium for promoting electronic cigarettes, which have rapidly increased in popularity and are heavily marketed online. While a few studies have examined a limited subset of tobacco-related videos on YouTube, none has explored e-cigarette videos’ overall presence on the platform. Objective To quantify e-cigarette-related videos on YouTube, assess their content, and characterize levels of engagement with those videos. Understanding promotion and discussion of e-cigarettes on YouTube may help clarify the platform’s impact on consumer attitudes and behaviors and inform regulations. Methods Using an automated crawling procedure and keyword rules, e-cigarette-related videos posted on YouTube and their associated metadata were collected between July 1, 2012, and June 30, 2013. Metadata were analyzed to describe posting and viewing time trends, number of views, comments, and ratings. Metadata were content coded for mentions of health, safety, smoking cessation, promotional offers, Web addresses, product types, top-selling brands, or names of celebrity endorsers. Results As of June 30, 2013, approximately 28,000 videos related to e-cigarettes were captured. Videos were posted by approximately 10,000 unique YouTube accounts, viewed more than 100 million times, rated over 380,000 times, and commented on more than 280,000 times. More than 2200 new videos were being uploaded every month by June 2013. The top 1% of most-viewed videos accounted for 44% of total views. Text fields for the majority of videos mentioned websites (70.11%); many referenced health (13.63%), safety (10.12%), smoking cessation (9.22%), or top e-cigarette brands (33.39%). The number of e-cigarette-related YouTube videos was projected to exceed 65,000 by the end of 2014, with approximately 190 million views. Conclusions YouTube is a major

  4. Application of NCRP REPORT No.151 for evaluating the radiation level at the ambience of megavoltage medical electron linear accelerator treatment room

    International Nuclear Information System (INIS)

    Yang Haiyou; Yu Shui

    2011-01-01

    Objective: The estimation model,on radiation level at the ambience of medical electron linear accelerator treatment rooms, is derived on the basis of NCRP REPORT No.151, which presents the calculation model of shielding design about barrier thicknesses of megavoltage medical electron linear accelerator treatment rooms. Methods: The estimation model comes from NCRP REPORT No.151- S tructural Shielding Design and Evaluation for Megavoltage X-and Gamma-Ray Radiotherapy Facilities , which presents the calculation model of shielding design about megavoltage medical electron linear accelerator treatment rooms, and the dose rate at isocenter replaces the workload, and the occupancy factor and the use factor are forsaken, then the converse deduction is done according to barrier thicknesses of shielding materials. Ultimately, the estimation model, on radiation level at the ambience of medical electron linear accelerator treatment rooms, is derived. Results: It can be regarded as a systematic estimation model for calculating the radiation level at the ambience of medical electron linear accelerator treatment room. Conclusion: The estimation model has certain practical value to evaluate the radiation level at the ambience of medical electron linear accelerator treatment room. (authors)

  5. Wind turbine noise propagation modelling: An unsteady approach

    DEFF Research Database (Denmark)

    Barlas, Emre; Zhu, Wei Jun; Shen, Wen Zhong

    2016-01-01

    Wind turbine sound generation and propagation phenomena are inherently time dependent, hence tools that incorporate the dynamic nature of these two issues are needed for accurate modelling. In this paper, we investigate the sound propagation from a wind turbine by considering the effects of unste...... Pressure Level (SPL).......Wind turbine sound generation and propagation phenomena are inherently time dependent, hence tools that incorporate the dynamic nature of these two issues are needed for accurate modelling. In this paper, we investigate the sound propagation from a wind turbine by considering the effects...... of unsteady flow around it and time dependent source characteristics. For the acoustics modelling we employ the Parabolic Equation (PE) method while Large Eddy Simulation (LES) as well as synthetically generated turbulence fields are used to generate the medium flow upon which sound propagates. Unsteady...

  6. Effects of laser beam propagation in a multilevel photoionization system

    International Nuclear Information System (INIS)

    Izawa, Y.; Nomaru, K.; Chen, Y. W.

    1995-01-01

    When the intense laser pulse propagates in the atomic vapor over a long distance, the laser pulse shape, the carrier frequency and the propagating velocity are greatly modified during the propagation by the resonant and/or the near-resonant interactions with atoms. We have been investigating these effects on the laser beam propagation experimentally and analytically. The simulation code named CEALIS-P has been developed, which employs the coupled three- level Bloch-Maxwell equations to study the atomic excitation and laser beam propagation simultaneously. Several features of the resonant and near-resonant effects based on the the self-induced transparency, the self-phase modulation and the nonlinear group velocity dispersion are described and the influences of such effects on the photoionization efficiency are analyzed.

  7. Charged particle beam propagation studies at the Naval Research Laboratory

    International Nuclear Information System (INIS)

    Meger, R.A.; Hubbard, R.F.; Antoniades, J.A.; Fernsler, R.F.; Lampe, M.; Murphy, D.P.; Myers, M.C.; Pechacek, R.E.; Peyser, T.A.; Santos, J.; Slinker, S.P.

    1993-01-01

    The Plasma Physics Division of the Naval Research Laboratory has been performing research into the propagation of high current electron beams for 20 years. Recent efforts have focused on the stabilization of the resistive hose instability. Experiments have utilized the SuperIBEX e-beam generator (5-MeV, 100-kA, 40-ns pulse) and a 2-m diameter, 5-m long propagation chamber. Full density air propagation experiments have successfully demonstrated techniques to control the hose instability allowing stable 5-m transport of 1-2 cm radius, 10-20 kA total current beams. Analytic theory and particle simulations have been used to both guide and interpret the experimental results. This paper will provide background on the program and summarize the achievements of the NRL propagation program up to this point. Further details can be found in other papers presented in this conference

  8. Wave propagation in the magnetosphere of Jupiter

    Science.gov (United States)

    Liemohn, H. B.

    1972-01-01

    A systematic procedure is developed for identifying the spatial regimes of various modes of wave propagation in the Jupiter magnetosphere that may be encountered by flyby missions. The Clemmow-Mullaly-Allis (CMA) diagram of plasma physics is utilized to identify the frequency regimes in which different modes of propagation occur in the magnetoplasma. The Gledhill model and the Ioannidis and Brice model of the magnetoplasma are summarized, and configuration-space CMA diagrams are constructed for each model for frequencies from 10 Hz to 1 MHz. The distinctive propagation features, the radio noise regimes, and the wave-particle interactions are discussed. It is concluded that the concentration of plasma in the equatorial plane makes this region of vital importance for radio observations with flyby missions. Local radio noise around the electron cyclotron frequency will probably differ appreciably from its terrestrial counterpart due to the lack of field-line guidance. Hydromagnetic wave properties at frequencies near the ion cyclotron frequency and below will probably be similar to the terrestrial case.

  9. Pulsed positive corona streamer propagation and branching

    International Nuclear Information System (INIS)

    Veldhuizen, E.M. van; Rutgers, W.R.

    2002-01-01

    The propagation and branching of pulsed positive corona streamers in a short gap is observed with high resolution in space and time. The appearance of the pre-breakdown phenomena can be controlled by the electrode configuration, the gas composition and the impedance of the pulsed power circuit. In a point-wire gap the positive corona shows much more branching than in the parallel plane gap with a protrusion. In air, the branching is more pronounced than in argon. The pulsed power circuit appears to operate in two modes, either as an inductive circuit creating a lower number of thick streamers or as a resistive circuit giving a higher number of thin streamers. A possible cause for branching is electrostatic repulsion of two parts of the streamer head. The electric field at the streamer head is limited, the maximum values found are ∼170 kV cm -1 in air and ∼100 kV cm -1 in argon. At these maximum field strengths, the electrons have 5-10 eV energy, so the ionization is dominated by two-step processes. Differences between argon and ambient air in the field strength at which streamers propagate are ascribed to the difference in de-excitation processes in noble and molecular gases. The fact that the pulsed power circuit can control the streamer structure is important for applications, but this effect must also be taken into account in fundamental studies of streamer propagation and branching. (author)

  10. Pulsed positive corona streamer propagation and branching

    Energy Technology Data Exchange (ETDEWEB)

    Veldhuizen, E.M. van [Department of Physics, Technische Universiteit Eindhoven, Eindhoven (Netherlands)]. E-mail: e.m.v.veldhuizen@tue.nl; Rutgers, W.R. [Department of Physics, Technische Universiteit Eindhoven, Eindhoven (Netherlands)

    2002-09-07

    The propagation and branching of pulsed positive corona streamers in a short gap is observed with high resolution in space and time. The appearance of the pre-breakdown phenomena can be controlled by the electrode configuration, the gas composition and the impedance of the pulsed power circuit. In a point-wire gap the positive corona shows much more branching than in the parallel plane gap with a protrusion. In air, the branching is more pronounced than in argon. The pulsed power circuit appears to operate in two modes, either as an inductive circuit creating a lower number of thick streamers or as a resistive circuit giving a higher number of thin streamers. A possible cause for branching is electrostatic repulsion of two parts of the streamer head. The electric field at the streamer head is limited, the maximum values found are {approx}170 kV cm{sup -1} in air and {approx}100 kV cm{sup -1} in argon. At these maximum field strengths, the electrons have 5-10 eV energy, so the ionization is dominated by two-step processes. Differences between argon and ambient air in the field strength at which streamers propagate are ascribed to the difference in de-excitation processes in noble and molecular gases. The fact that the pulsed power circuit can control the streamer structure is important for applications, but this effect must also be taken into account in fundamental studies of streamer propagation and branching. (author)

  11. Current understanding of SEP acceleration and propagation

    International Nuclear Information System (INIS)

    Klecker, B

    2013-01-01

    The solar energetic particle (SEP) populations of electrons and ions are highly variable in space and time, in intensity, energy, and composition. Over the last ∼20 years advanced instrumentation onboard many spacecraft (e.g. ACE, Coronas, GOES, Hinode, RHESSI, SAMPEX, SDO, SOHO, STEREO, TRACE, Ulysses, Yokoh, to name a few) extended our ability to explore the characteristics of solar energetic particles by in-situ measurements in interplanetary space and by observing their source characteristics near the Sun by remote-sensing observation of electromagnetic emission over a wide frequency range. These measurements provide crucial information for understanding the sources of the particle populations and the acceleration and propagation processes involved. We are now able to measure intensity-time profiles and anisotropies, energy spectra, elemental and isotopic abundances, and the ionic charge of particles over an extended energy range of 0.01 to several 100 MeV/nuc and for a large dynamic range of particle intensities. Furthermore, multi-spacecraft in-situ observations at different solar longitudes and latitudes provide new insight into the acceleration and propagation processes of SEPs near the Sun and in interplanetary space. In this paper we present an overview of SEP observations, their implications for SEP acceleration and propagation processes, and discuss open questions.

  12. Dike Propagation Near Drifts

    International Nuclear Information System (INIS)

    2002-01-01

    The purpose of this Analysis and Model Report (AMR) supporting the Site Recommendation/License Application (SR/LA) for the Yucca Mountain Project is the development of elementary analyses of the interactions of a hypothetical dike with a repository drift (i.e., tunnel) and with the drift contents at the potential Yucca Mountain repository. This effort is intended to support the analysis of disruptive events for Total System Performance Assessment (TSPA). This AMR supports the Process Model Report (PMR) on disruptive events (CRWMS M and O 2000a). This purpose is documented in the development plan (DP) ''Coordinate Modeling of Dike Propagation Near Drifts Consequences for TSPA-SR/LA'' (CRWMS M and O 2000b). Evaluation of that Development Plan and the work to be conducted to prepare Interim Change Notice (ICN) 1 of this report, which now includes the design option of ''Open'' drifts, indicated that no revision to that DP was needed. These analyses are intended to provide reasonable bounds for a number of expected effects: (1) Temperature changes to the waste package from exposure to magma; (2) The gas flow available to degrade waste containers during the intrusion; (3) Movement of the waste package as it is displaced by the gas, pyroclasts and magma from the intruding dike (the number of packages damaged); (4) Movement of the backfill (Backfill is treated here as a design option); (5) The nature of the mechanics of the dike/drift interaction. These analyses serve two objectives: to provide preliminary analyses needed to support evaluation of the consequences of an intrusive event and to provide a basis for addressing some of the concerns of the Nuclear Regulatory Commission (NRC) expressed in the Igneous Activity Issue Resolution Status Report

  13. Levels and risk factors of antimony contamination in human hair from an electronic waste recycling area, Guiyu, China.

    Science.gov (United States)

    Huang, Yue; Ni, Wenqing; Chen, Yaowen; Wang, Xiaoling; Zhang, Jingwen; Wu, Kusheng

    2015-05-01

    The primitive electronic waste (e-waste) recycling has brought a series of environmental pollutants in Guiyu, China. Antimony is one of the important metal contaminants and has aroused the global concerns recently. We aimed to investigate concentrations of antimony in human hair from Guiyu and compared them with those from a control area where no e-waste recycling exists, and assessed the potential risk factors. A total of 205 human hair samples from Guiyu and 80 samples from Jinping were collected for analysis. All volunteers were asked to complete a questionnaire including socio-demographic characteristics and other possible factors related to hair antimony exposure. The concentrations of hair antimony were analyzed using atomic absorption spectrophotometer. Our results indicated that the level of hair antimony in volunteers from Guiyu (median, 160.78; range, 6.99-4412.59 ng/g) was significantly higher than those from Jinping (median, 61.74; range, 2.98-628.43 ng/g). The residents who engaged in e-waste recycling activities in Guiyu had higher hair antimony concentrations than others (P recycling. Multiple stepwise regression analysis indicated that hair antimony concentrations were associated with education level (β = -0.064), the time of residence in Guiyu (β = 0.112), living house also served as e-waste workshop (β = 0.099), the work related to e-waste (β = 0.169), and smoking (β = 0.018). The elevated hair antimony concentrations implied that the residents in Guiyu might be at high risk of antimony contamination, especially the e-waste recycling workers. Work related to e-waste recycling activities and long-time residence in Guiyu contributed to the high hair antimony exposure.

  14. Revealing energy level structure of individual quantum dots by tunneling rate measured by single-electron sensitive electrostatic force spectroscopy.

    Science.gov (United States)

    Roy-Gobeil, Antoine; Miyahara, Yoichi; Grutter, Peter

    2015-04-08

    We present theoretical and experimental studies of the effect of the density of states of a quantum dot (QD) on the rate of single-electron tunneling that can be directly measured by electrostatic force microscopy (e-EFM) experiments. In e-EFM, the motion of a biased atomic force microscope cantilever tip modulates the charge state of a QD in the Coulomb blockade regime. The charge dynamics of the dot, which is detected through its back-action on the capacitavely coupled cantilever, depends on the tunneling rate of the QD to a back-electrode. The density of states of the QD can therefore be measured through its effect on the energy dependence of tunneling rate. We present experimental data on individual 5 nm colloidal gold nanoparticles that exhibit a near continuous density of state at 77 K. In contrast, our analysis of already published data on self-assembled InAs QDs at 4 K clearly reveals discrete degenerate energy levels.

  15. Electronic nicotine delivery system landscape in licensed tobacco retailers: results of a county-level survey in Oklahoma

    Science.gov (United States)

    Brame, L S; Mowls, D S; Damphousse, K E; Beebe, L A

    2016-01-01

    Objectives Electronic nicotine delivery systems (ENDS) have recently emerged as a component of the tobacco retail environment. The aims of this study were to describe the availability, types of ENDS and placement of ENDS relative to traditional tobacco products at franchised licensed tobacco retailers and non-franchised licensed tobacco retailers. Design Observational study. Setting Franchised and non-franchised tobacco retailers in Cleveland County, Oklahoma, USA. Primary and secondary outcome measures The number of stores selling ENDS, the variability in brands of ENDS sold, the location of the ENDS within the retailers, the quantity of ENDS sold compared with traditional tobacco products, and the presence of outdoor signage. Results Data from 57 randomly sampled tobacco retailers were used to describe the presence of ENDS at independent non-franchised and franchised tobacco retailers. The overwhelming majority (90%) of licensed tobacco retailers sold ENDS, and differences were observed between franchised and non-franchised stores. 45 of the 51 retailers (88%) selling ENDS had them placed at the point of sale. 2 of the 21 franchised retailers (9.5%) had ENDS placed at ≤3½ feet above floor level compared to none of the 30 non-franchised retailers (0%). Conclusions This small study is the first to characterise ENDS within the tobacco retail environment in a county in Oklahoma, USA. The results from this study demonstrate the complexity of the tobacco retail landscape and generate questions for future studies regarding the incorporation and placement of ENDS in tobacco retail environments. PMID:27266774

  16. Development a low-cost carbon monoxide sensor using homemade CW-DFB QCL and board-level electronics

    Science.gov (United States)

    Dang, Jingmin; Yu, Haiye; Zheng, Chuantao; Wang, Lijun; Sui, Yuanyuan; Wang, Yiding

    2018-05-01

    A mid-infrared sensor was demonstrated for the detection of carbon monoxide (CO) at trace level. In order to reduce cost, a homemade continuous-wave mode distributed feedback quantum cascade laser (CW-DFB QCL), a mini gas cell with 1.6-m optical length, and some self-development electronic modules were adopted as excitation source, absorption pool, and signal controlling and processing tool, respectively. Wavelength modulation spectroscopy (WMS) and phase sensitive detection (PSD) techniques as well as wavelet filtering software algorithm were used to reduce the influence of light source fluctuation and system noise and to improve measurement precision and sensitivity. Under the selected P(11) absorption line located at 2099.083 cm-1, a limit of detection (LoD) of 26 parts per billion by volume (ppbv) at atmospheric pressure was achieved with a 1-s acquisition time. Allan deviation was used to characterize the long-term performance of the CO sensor, and a measurement precision of ∼3.4 ppbv was observed with an optimal integration time of ∼114 s. As a field measurement, a continuous monitoring on indoor CO concentration for a period of 24 h was conducted, which verified the reliable and robust operation of the developed sensor.

  17. Laser beam propagation generation and propagation of customized light

    CERN Document Server

    Forbes, Andrew

    2014-01-01

    ""The text is easy to read and is accompanied by beautiful illustrations. It is an excellent book for anyone working in laser beam propagation and an asset for any library.""-Optics & Photonics News, July 2014

  18. Levels in /sup 179/W studied in the /sup 181/Ta(p, 3n) reaction by on-line electron and gamma ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Meijer, B J; Konijn, J [Instituut voor Kernphysisch Onderzoek, Amsterdam (Netherlands); Klank, B; Jett, J H; Ristinen, R A [Colorado Univ., Boulder (USA)

    1975-01-01

    Levels in /sup 179/W have been deduced from in-beam gamma and conversion electron studies of the /sup 181/Ta(p, 3n)/sup 179/W reaction. The gamma-ray spectrum was studied with Ge(Li) detectors and a crystal diffraction spectrometer; the conversion electrons were measured with solenoid Si(Li) spectrometer. The multipolarities of some 50 transitions could be determined. Coriolis mixing of the Nilsson orbits with N = 6 was calculated.

  19. The Next Level of Research on Electronic Play: Potential Benefits and Contextual Influences for Children and Adolescents

    Directory of Open Access Journals (Sweden)

    Dorothy E. Salonius-Pasternak

    2005-01-01

    Full Text Available Most research on electronic play has focused on its possible negative effects for children and adolescents, and contextual factors such as socioeconomic status (SES and culture are rarely considered. This article considers the potential benefits of electronic play from a psychological perspective, as well as individual and contextual factors that may shape the influence of electronic play for children and adolescents. Demographics of players and the games themselves are presented, and recommendations for research and policy are discussed.

  20. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis.

    Science.gov (United States)

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-26

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum.

  1. Patient and public attitudes towards informed consent models and levels of awareness of Electronic Health Records in the UK

    Science.gov (United States)

    Riordan, Fiona; Papoutsi, Chrysanthi; Reed, Julie E.; Marston, Cicely; Bell, Derek; Majeed, Azeem

    2015-01-01

    Background The development of Electronic Health Records (EHRs) forms an integral part of the information strategy for the National Health Service (NHS) in the UK, with the aim of facilitating health information exchange for patient care and secondary use, including research and healthcare planning. Implementing EHR systems requires an understanding of patient expectations for consent mechanisms and consideration of public awareness towards information sharing as might be made possible through integrated EHRs across primary and secondary health providers. Objectives To explore levels of public awareness about EHRs and to examine attitudes towards different consent models with respect to sharing identifiable and de-identified records for healthcare provision, research and planning. Methods A cross-sectional questionnaire survey was administered to adult patients and members of the public in primary and secondary care clinics in West London, UK in 2011. In total, 5331 individuals participated in the survey, and 3157 were included in the final analysis. Results The majority (91%) of respondents expected to be explicitly asked for consent for their identifiable records to be accessed for health provision, research or planning. Half the respondents (49%) did not expect to be asked for consent before their de-identified records were accessed. Compared with White British respondents, those from all other ethnic groups were more likely to anticipate their permission would be obtained before their de-identified records were used. Of the study population, 59% reported already being aware of EHRs before the survey. Older respondents and individuals with complex patterns of interaction with healthcare services were more likely to report prior awareness of EHRs. Individuals self-identifying as belonging to ethnic groups other than White British, and those with lower educational qualifications were less likely to report being aware of EHRs than White British respondents and

  2. Noise propagation issues in Belle II pixel detector power cable

    Science.gov (United States)

    Iglesias, M.; Arteche, F.; Echeverria, I.; Pradas, A.; Rivetta, C.; Moser, H.-G.; Kiesling, C.; Rummel, S.; Arcega, F. J.

    2018-04-01

    The vertex detector used in the upgrade of High-Energy physics experiment Belle II includes DEPFET pixel detector (PXD) technology. In this complex topology the power supply units and the front-end electronics are connected through a PXD power cable bundle which may propagate the output noise from the power supplies to the vertex area. This paper presents a study of the propagation of noise caused by power converters in the PXD cable bundle based on Multi-conductor Transmission Line (MTL) theory. The work exposes the effect of the complex cable topology and shield connections on the noise propagation, which has an impact on the requirements of the power supplies. This analysis is part of the electromagnetic compatibility based design focused on functional safety to define the shield connections and power supply specifications required to ensure the successful integration of the detector and, specifically, to achieve the designed performance of the front-end electronics.

  3. Influence of chemical disorder on the electronic level spacing distribution of the Ag{sub 5083} nanoparticle: A tight-binding study

    Energy Technology Data Exchange (ETDEWEB)

    Medrano, L.R., E-mail: leonardoms20@gmail.com [Faculty of Physical Sciences, National University of San Marcos, P.O. Box 14-0149, Lima 14 (Peru); Landauro, C.V., E-mail: clandauros@unmsm.edu.pe [Faculty of Physical Sciences, National University of San Marcos, P.O. Box 14-0149, Lima 14 (Peru)

    2013-03-01

    In the present work we study, employing a tight-binding Hamiltonian, the influence of chemical disorder on the electronic level spacing distribution of a silver nanoparticle containing 5083 atoms (∼ 5.5 nm). This nanoparticle was obtained by molecular dynamics simulations with a tight-binding atomic potential. The results indicate that in the absence of disorder the level spacing distributions are similar to those expected for systems belonging to the Gaussian Orthogonal Ensemble. Whereas, after increasing the chemical disorder, the electronic level spacing distribution and the Σ{sub 2} statistics tend to the corresponding form for the Poisson Ensemble, i.e., the silver nanoparticle acquires an insulating character which is expected for strongly disordered systems. Hence, this kind of disorder produces the localization of the electronic states of the nanoparticle.

  4. Electron wind in strong wave guide fields

    Science.gov (United States)

    Krienen, F.

    1985-03-01

    The X-ray activity observed near highly powered waveguide structures is usually caused by local electric discharges originating from discontinuities such as couplers, tuners or bends. In traveling waves electrons move in the direction of the power flow. Seed electrons can multipactor in a traveling wave, the moving charge pattern is different from the multipactor in a resonant structure and is self-extinguishing. The charge density in the wave guide will modify impedance and propagation constant of the wave guide. The radiation level inside the output wave guide of the SLAC, 50 MW, S-band, klystron is estimated. Possible contributions of radiation to window failure are discussed.

  5. Methodologies of Uncertainty Propagation Calculation

    International Nuclear Information System (INIS)

    Chojnacki, Eric

    2002-01-01

    After recalling the theoretical principle and the practical difficulties of the methodologies of uncertainty propagation calculation, the author discussed how to propagate input uncertainties. He said there were two kinds of input uncertainty: - variability: uncertainty due to heterogeneity, - lack of knowledge: uncertainty due to ignorance. It was therefore necessary to use two different propagation methods. He demonstrated this in a simple example which he generalised, treating the variability uncertainty by the probability theory and the lack of knowledge uncertainty by the fuzzy theory. He cautioned, however, against the systematic use of probability theory which may lead to unjustifiable and illegitimate precise answers. Mr Chojnacki's conclusions were that the importance of distinguishing variability and lack of knowledge increased as the problem was getting more and more complex in terms of number of parameters or time steps, and that it was necessary to develop uncertainty propagation methodologies combining probability theory and fuzzy theory

  6. Propagation engineering in wireless communications

    CERN Document Server

    Ghasemi, Abdollah; Ghasemi, Farshid

    2016-01-01

    This book covers the basic principles for understanding radio wave propagation for common frequency bands used in radio-communications. This includes achievements and developments in propagation models for wireless communication. This book is intended to bridge the gap between the theoretical calculations and approaches to the applied procedures needed for radio links design in a proper manner. The authors emphasize propagation engineering by giving fundamental information and explain the use of basic principles together with technical achievements. This new edition includes additional information on radio wave propagation in guided media and technical issues for fiber optics cable networks with several examples and problems. This book also includes a solution manual - with 90 solved examples distributed throughout the chapters - and 158 problems including practical values and assumptions.

  7. Wave propagation in electromagnetic media

    CERN Document Server

    Davis, Julian L

    1990-01-01

    This is the second work of a set of two volumes on the phenomena of wave propagation in nonreacting and reacting media. The first, entitled Wave Propagation in Solids and Fluids (published by Springer-Verlag in 1988), deals with wave phenomena in nonreacting media (solids and fluids). This book is concerned with wave propagation in reacting media-specifically, in electro­ magnetic materials. Since these volumes were designed to be relatively self­ contained, we have taken the liberty of adapting some of the pertinent material, especially in the theory of hyperbolic partial differential equations (concerned with electromagnetic wave propagation), variational methods, and Hamilton-Jacobi theory, to the phenomena of electromagnetic waves. The purpose of this volume is similar to that of the first, except that here we are dealing with electromagnetic waves. We attempt to present a clear and systematic account of the mathematical methods of wave phenomena in electromagnetic materials that will be readily accessi...

  8. Massive propagators in instanton fields

    International Nuclear Information System (INIS)

    Brown, L.S.; Lee, C.

    1978-01-01

    Green's functions for massive spinor and vector particles propagating in a self-dual but otherwise arbitrary non-Abelian gauge field are shown to be completely determined by the corresponding Green's functions of massive scalar particles

  9. Propagation of dynamic measurement uncertainty

    International Nuclear Information System (INIS)

    Hessling, J P

    2011-01-01

    The time-dependent measurement uncertainty has been evaluated in a number of recent publications, starting from a known uncertain dynamic model. This could be defined as the 'downward' propagation of uncertainty from the model to the targeted measurement. The propagation of uncertainty 'upward' from the calibration experiment to a dynamic model traditionally belongs to system identification. The use of different representations (time, frequency, etc) is ubiquitous in dynamic measurement analyses. An expression of uncertainty in dynamic measurements is formulated for the first time in this paper independent of representation, joining upward as well as downward propagation. For applications in metrology, the high quality of the characterization may be prohibitive for any reasonably large and robust model to pass the whiteness test. This test is therefore relaxed by not directly requiring small systematic model errors in comparison to the randomness of the characterization. Instead, the systematic error of the dynamic model is propagated to the uncertainty of the measurand, analogously but differently to how stochastic contributions are propagated. The pass criterion of the model is thereby transferred from the identification to acceptance of the total accumulated uncertainty of the measurand. This increases the relevance of the test of the model as it relates to its final use rather than the quality of the calibration. The propagation of uncertainty hence includes the propagation of systematic model errors. For illustration, the 'upward' propagation of uncertainty is applied to determine if an appliance box is damaged in an earthquake experiment. In this case, relaxation of the whiteness test was required to reach a conclusive result

  10. Streamer propagation velocity to anode and to cathode in He, Xe, N2 and SF6

    International Nuclear Information System (INIS)

    Yakovlenko, S.I.

    2004-01-01

    One studied mechanism of ionization propagation in a solid gas associated with propagation of background electrons in heterogenous electric field. The mentioned mechanism does not depend on the sign of field projection on ionization propagation direction. One derived analytical expression for ionization front rate. The mentioned expression conforms well with numerical calculations. Dependence of wave ionization front rate as a function of a field intensity on boundary of streamer for He, Xe, N 2 and SF 6 is tabulated [ru

  11. Atomic level study of water-gas shift catalysts via transmission electron microscopy and x-ray spectroscopy

    Science.gov (United States)

    Akatay, Mehmed Cem

    Water-gas shift (WGS), CO + H2O ⇆ CO2 + H2 (DeltaH° = -41 kJ mol -1), is an industrially important reaction for the production of high purity hydrogen. Commercial Cu/ZnO/Al2O3 catalysts are employed to accelerate this reaction, yet these catalysts suffer from certain drawbacks, including costly regeneration processes and sulfur poisoning. Extensive research is focused on developing new catalysts to replace the current technology. Supported noble metals stand out as promising candidates, yet comprise intricate nanostructures complicating the understanding of their working mechanism. In this study, the structure of the supported Pt catalysts is explored by transmission electron microscopy and X-ray spectroscopy. The effect of the supporting phase and the use of secondary metals on the reaction kinetics is investigated. Structural heterogeneities are quantified and correlated with the kinetic descriptors of the catalysts to develop a fundamental understanding of the catalytic mechanism. The effect of the reaction environment on catalyst structure is examined by in-situ techniques. This study benefitted greatly from the use of model catalysts that provide a convenient medium for the atomic level characterization of nanostructures. Based on these studies, Pt supported on iron oxide nano islands deposited on inert spherical alumina exhibited 48 times higher WGS turnover rate (normalized by the total Pt surface area) than Pt supported on bulk iron oxide. The rate of aqueous phase glycerol reforming reaction of Pt supported on multiwall carbon nanotubes (MWCNT) is promoted by co-impregnating with cobalt. The synthesis resulted in a variety of nanostructures among which Pt-Co bimetallic nanoparticles are found to be responsible for the observed promotion. The unprecedented WGS rate of Pt supported on Mo2C is explored by forming Mo 2C patches on top of MWCNTs and the rate promotion is found to be caused by the Pt-Mo bimetallic entities.

  12. Semiclassical propagation of Wigner functions.

    Science.gov (United States)

    Dittrich, T; Gómez, E A; Pachón, L A

    2010-06-07

    We present a comprehensive study of semiclassical phase-space propagation in the Wigner representation, emphasizing numerical applications, in particular as an initial-value representation. Two semiclassical approximation schemes are discussed. The propagator of the Wigner function based on van Vleck's approximation replaces the Liouville propagator by a quantum spot with an oscillatory pattern reflecting the interference between pairs of classical trajectories. Employing phase-space path integration instead, caustics in the quantum spot are resolved in terms of Airy functions. We apply both to two benchmark models of nonlinear molecular potentials, the Morse oscillator and the quartic double well, to test them in standard tasks such as computing autocorrelation functions and propagating coherent states. The performance of semiclassical Wigner propagation is very good even in the presence of marked quantum effects, e.g., in coherent tunneling and in propagating Schrodinger cat states, and of classical chaos in four-dimensional phase space. We suggest options for an effective numerical implementation of our method and for integrating it in Monte-Carlo-Metropolis algorithms suitable for high-dimensional systems.

  13. Surface plasmon polariton propagation in organic nanofiber based plasmonic waveguides

    DEFF Research Database (Denmark)

    Leißner, Till; Lemke, Christoph; Jauernik, Stephan

    2013-01-01

    Plasmonic wave packet propagation is monitored in dielectric-loaded surface plasmon polariton waveguides realized from para-hexaphenylene nanofibers deposited onto a 60 nm thick gold film. Using interferometric time resolved two-photon photoemission electron microscopy we are able to determine...

  14. Nonlinear propagation of short wavelength drift-Alfven waves

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two-dim...

  15. Radial propagation of microturbulence in tokamaks

    International Nuclear Information System (INIS)

    Garbet, X.; Laurent, L.; Roubin, J.P.; Samain, A.

    1992-01-01

    Energy confinement time in tokamaks exhibits a clear dependence on global plasma parameters. This is not the case for transport coefficients; their dependence on local plasma parameters cannot be precisely established. The aim of the present paper is to give a possible explanation of this behaviour; turbulence propagates radially because of departure from cylindrical geometry. This implies that the turbulence level at a given point and hence transport coefficients are not only functions of local plasma parameters. A quantitative estimate of the propagation velocity is derived from a Lagrangian formalism. Two cases are considered: the effect of toroidicity and the effect of non linear mode-mode coupling. The consequences of this model are discussed. This process does not depend on the type of instability. For the sake of simplicity only electrostatic perturbations are considered

  16. Alternative model of thrust-fault propagation

    Science.gov (United States)

    Eisenstadt, Gloria; de Paor, Declan G.

    1987-07-01

    A widely accepted explanation for the geometry of thrust faults is that initial failures occur on deeply buried planes of weak rock and that thrust faults propagate toward the surface along a staircase trajectory. We propose an alternative model that applies Gretener's beam-failure mechanism to a multilayered sequence. Invoking compatibility conditions, which demand that a thrust propagate both upsection and downsection, we suggest that ramps form first, at shallow levels, and are subsequently connected by flat faults. This hypothesis also explains the formation of many minor structures associated with thrusts, such as backthrusts, wedge structures, pop-ups, and duplexes, and provides a unified conceptual framework in which to evaluate field observations.

  17. Unidirectional reflectionless light propagation at exceptional points

    Directory of Open Access Journals (Sweden)

    Huang Yin

    2017-05-01

    Full Text Available In this paper, we provide a comprehensive review of unidirectional reflectionless light propagation in photonic devices at exceptional points (EPs. EPs, which are branch point singularities of the spectrum, associated with the coalescence of both eigenvalues and corresponding eigenstates, lead to interesting phenomena, such as level repulsion and crossing, bifurcation, chaos, and phase transitions in open quantum systems described by non-Hermitian Hamiltonians. Recently, it was shown that judiciously designed photonic synthetic matters could mimic the complex non-Hermitian Hamiltonians in quantum mechanics and realize unidirectional reflection at optical EPs. Unidirectional reflectionlessness is of great interest for optical invisibility. Achieving unidirectional reflectionless light propagation could also be potentially important for developing optical devices, such as optical network analyzers. Here, we discuss unidirectional reflectionlessness at EPs in both parity-time (PT-symmetric and non-PT-symmetric optical systems. We also provide an outlook on possible future directions in this field.

  18. Cross sections for the vibrational excitation of the H2 X 1Σ+g(v) levels generated by electron collisional excitation of the higher singlet states

    International Nuclear Information System (INIS)

    Hiskes, J.R.

    1991-01-01

    The excitation cross sections, σ(v,v double-prime), for an H 2 molecule initially in any one of the 15 vibrational levels, v belonging to the ground electronic state and excited to a final vibrational level, v double-prime are evaluated for direct excitations via all members of the excited electronic singlet spectrum. Account is taken of predissociation, autoionization, and radiative decay of the excited electronic spectrum that leads to a final population distribution for the ground electronic state, X 1 Σ + g (v double-prime). For v=0, account is taken explicitly of transitions via the B, C, B', and D electronic states in evaluating the cross sections. The additional contribution of excitations via all Rydberg states lying above the D state enhances these cross sections by approximately 10%. For v>0, cross sections are evaluated taking explicit account of transitions through the B and C states; higher singlet excitations enhance these values by 25%. The choice of the reference total cross sections remains a subjective one, causing the values calculated here to have a possible uncertainty of +20% -30% . For excitations occurring within a hydrogen discharge, collisional excitation-ionization events among the intermediate singlet states will effectively quench the v, v double-prime excitation process for discharge densities in excess of the range 10 15 --10 16 electrons/cm -3

  19. Wave propagation in elastic layers with damping

    DEFF Research Database (Denmark)

    Sorokin, Sergey; Darula, Radoslav

    2016-01-01

    The conventional concepts of a loss factor and complex-valued elastic moduli are used to study wave attenuation in a visco-elastic layer. The hierarchy of reduced-order models is employed to assess attenuation levels in various situations. For the forcing problem, the attenuation levels are found...... for alternative excitation cases. The differences between two regimes, the low frequency one, when a waveguide supports only one propagating wave, and the high frequency one, when several waves are supported, are demonstrated and explained....

  20. Excitation-energy-dependent resonances in x-ray emissions under near-threshold electron excitation of the Ce 3d and 4d levels

    International Nuclear Information System (INIS)

    Chamberlain, M.B.; Baun, W.L.

    1975-01-01

    Soft x-ray appearance potential spectra of the 3d and 4d levels of polycrystalline cerium metal are reported in this paper. Resonant x-ray emissions are observed when the electron-excitation energy sweeps through the ionization energies of the 3d and 4d levels. The resonant x rays excited at the 3d-level onsets are considerably more intense, and are excited at a lower electron-excitation energy than the 3d-series characteristic x rays. In the neighborhood of the 4d-electron thresholds, four line-like structures extend to approx.8 eV below the 4d-electron binding energies, while two broad and more intense structures occur above the 4d onsets, with the largest one reaching a peak intensity at 12 eV above the 4d thresholds. The resonant emissions apparently arise from the decay of threshold-excited states which are bound to the inner vacancy and have core configurations nd 9 4f 3 , (n=3,4). The exchange interaction between the three 4f electrons and the respective d-orbital vacancy spreads the 4d-threshold structures over a 20 eV range of excitation energies and the 3d-threshold structures over a much smaller range

  1. Time-resolved electron transport in quantum-dot systems; Zeitaufgeloester Elektronentransport in Quantendotsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Croy, Alexander

    2010-06-30

    In this thesis the time-resolved electron transport in quantum dot systems was studied. For this two different formalisms were presented: The nonequilibrium Green functions and the generalized quantum master equations. For both formalisms a propagation method for the numerical calculation of time-resolved expectation values, like the occupation and the electron current, was developed. For the demonstration of the propagation method two different question formulations were considered. On the one hand the stochastically driven resonant-level model was studied. On the other hand the pulse-induced transport through a double quantum dot was considered.

  2. LAT Perspectives in Detection of High Energy Cosmic Ray Electrons

    International Nuclear Information System (INIS)

    Moiseev, Alexander; Ormes, J.F.; Funk, Stefan

    2007-01-01

    The LAT science objectives and capabilities in the detection of high energy electrons in the energy range from 20 GeV to ∼1.5 TeV are presented. LAT simulations are used to establish the event selections. It is found that maintaining the efficiency of electron detection at the level of 30%, the residual hadron contamination does not exceed 2-3% of the electron flux. It is expected to collect ∼ ten million of electrons with the energy above 20 GeV for one year of observation. Precise spectrum reconstruction with collected electron statistics opens the unique opportunity to investigate several important problems such as models of IC radiation, revealing the signatures of nearby sources such as high energy cutoff in the electron spectrum, testing the propagation model, and search for KKDM particles decay through their contribution to the electron spectrum

  3. The Interplay of Rashba Spin-Orbit Interaction and Landau Level Broadening on a Two-Dimensional Electron Gas Under a Tilted Magnetic Field

    International Nuclear Information System (INIS)

    Gammag, Rayda; Villagonzalo, Cristine

    2012-01-01

    A two-dimensional electron gas in a tilted magnetic field with Rashba spin-orbit interaction (RSOI) was studied. The RSOI is accredited to the asymmetry of the heterostructure where the two-dimensional electron gas is found. The effects of the disorder-attributed Landau level broadening and the RSOI on the spin splitting were identified by simulating the density of states which was assumed to take a Gaussian shape. Increased Landau level broadening obscures the spin splitting and increases the overlap between spin states resulting to stout Gaussian peaks. On the other hand, stronger RSOI amplifies the splitting and lessens the overlap between spin states of the Landau levels. The splitting, however, results to stouter peaks. The similarity in the RSOI and Landau level broadening effects can be explained by recognizing that the asymmetry of the heterostructure is in itself a form of structural disorder.

  4. geometric optics and WKB method for electromagnetic wave propagation in an inhomogeneous plasma near cutoff

    Energy Technology Data Exchange (ETDEWEB)

    Light, Max Eugene [Los Alamos National Laboratory

    2017-04-13

    This report outlines the theory underlying electromagnetic (EM) wave propagation in an unmagnetized, inhomogeneous plasma. The inhomogeneity is given by a spatially nonuniform plasma electron density ne(r), which will modify the wave propagation in the direction of the gradient rne(r).

  5. New approach to K-electron-capture probabilities to the 437 and 384 keV levels in the decay of /sup 133/Ba

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K; Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

    1983-12-01

    The K-electron-capture probabilities to the 437 and 384 keV levels in the decay of /sup 133/Ba have been determined from a measurement of gamma-ray intensities in conjunction with an analysis of the K x-ray-gamma-ray sum peaks. The results are independent of fluorescence yield and detector efficiency.

  6. Electromagnetic Wave Propagation Assessment

    Science.gov (United States)

    1993-03-01

    the increacd availabilit , ol such systems are critical for their optimum use. This computers and display technology. An early example is illustrated...Gaseous zO - H 0.25 mm/hr 2 H2 I - Temperature - 20 C D ~~Sea Level - p1 am, Z Water Vapour - 7.5 g/m 3 I- < 0 3Gaseous L . II I I I LIiIU hJ1 001 10

  7. Coherent control of single electrons: a review of current progress

    Science.gov (United States)

    Bäuerle, Christopher; Glattli, D. Christian; Meunier, Tristan; Portier, Fabien; Roche, Patrice; Roulleau, Preden; Takada, Shintaro; Waintal, Xavier

    2018-05-01

    In this report we review the present state of the art of the control of propagating quantum states at the single-electron level and its potential application to quantum information processing. We give an overview of the different approaches that have been developed over the last few years in order to gain full control over a propagating single-electron in a solid-state system. After a brief introduction of the basic concepts, we present experiments on flying qubit circuits for ensemble of electrons measured in the low frequency (DC) limit. We then present the basic ingredients necessary to realise such experiments at the single-electron level. This includes a review of the various single-electron sources that have been developed over the last years and which are compatible with integrated single-electron circuits. This is followed by a review of recent key experiments on electron quantum optics with single electrons. Finally we will present recent developments in the new physics that has emerged using ultrashort voltage pulses. We conclude our review with an outlook and future challenges in the field.

  8. Group symmetries and information propagation

    International Nuclear Information System (INIS)

    Draayer, J.P.

    1980-01-01

    Spectroscopy concerns itself with the ways in which the Hamiltonian and other interesting operators defined in few-particle spaces are determined or determine properties of many-particle systems. But the action of the central limit theorem (CLT) filters the transmission of information between source and observed so whether propagating forward from a few-particle defining space, as is usual in theoretical studies, or projecting backward to it from measured things, each is only sensitive to averaged properties of the other. Our concern is with the propagation of spectroscopic information in the presence of good symmetries when filtering action of the CLT is effective. Specifically, we propose to address the question, What propagates and how. We begin with some examples, using both scalar and isospin geometries to illustrate simple propagation. Examples of matrix propagation are studied; contact with standard tensor algebra is established and an algorithm put forward for the expansion of any operator in terms of another set, complete or not; shell-model results for 20 Ne using a realistic interaction and two trace-equivalent forms are presented; and some further challenges are mentioned

  9. Crack propagation on spherical pressure vessels

    International Nuclear Information System (INIS)

    Lebey, J.; Roche, R.

    1975-01-01

    The risk presented by a crack on a pressure vessel built with a ductile steel cannot be well evaluated by simple application of the rules of Linear Elastic Fracture Mechanics, which only apply to brittle materials. Tests were carried out on spherical vessels of three different scales built with the same steel. Cracks of different length were machined through the vessel wall. From the results obtained, crack initiation stress (beginning of stable propagation) and instable propagation stress may be plotted against the lengths of these cracks. For small and medium size, subject to ductile fracture, the resulting curves are identical, and may be used for ductile fracture prediction. Brittle rupture was observed on larger vessels and crack propagation occurred at lower stress level. Preceedings curves are not usable for fracture analysis. Ultimate pressure can be computed with a good accuracy by using equivalent energy toughness, Ksub(1cd), characteristic of the metal plates. Satisfactory measurements have been obtained on thin samples. The risks of brittle fracture may then judged by comparing Ksub(1cd) with the calculated K 1 value, in which corrections for vessel shape are taken into account. It is thus possible to establish the bursting pressure of cracked spherical vessels, with the help of two rules, one for brittle fracture, the other for ductile instability. A practical method is proposed on the basis of the work reported here

  10. A theory of coherent propagation of light wave in semiconductors

    International Nuclear Information System (INIS)

    Zi-zhao, G.; Guo-zhen, Y.

    1980-05-01

    In this paper, we suggest a theory to describe the pheonmena of coherent propagation of light wave in semiconductors. Basing on two band system and considering the interband and intraband transitions induced by light wave and the interaction between electrons, we obtain the nonlinear equations for the description of interaction between carriers and coherent light wave. We have made use of the equations to analyse the phenomena which arise from the interaction between semiconductors and coherent light, for example, the multiphoton transitions, the saturation of light absorption of exciton, the shift of exciton line in intense light field, and the coherent propagation phenomena such as self-induced transparency, etc. (author)

  11. Ductile cast irons: microstructure influence on fatigue crack propagation resistance

    Directory of Open Access Journals (Sweden)

    Mauro Cavallini

    2010-07-01

    Full Text Available Microstructure influence on fatigue crack propagation resistance in five different ductile cast irons (DCI was investigated. Four ferrite/pearlite volume fractions were considered, performing fatigue crack propagation tests according to ASTM E647 standard (R equals to 0.1, 0.5 and 0.75, respectively. Results were compared with an austempered DCI. Damaging micromechanisms were investigated according to the following procedures: - “traditional” Scanning Electron Microscope (SEM fracture surfaces analysis; - SEM fracture surface analysis with 3D quantitative analysis; - SEM longitudinal crack profile analysis - Light Optical Microscope (LOM transversal crack profile analysis;

  12. Signal propagation along the axon.

    Science.gov (United States)

    Rama, Sylvain; Zbili, Mickaël; Debanne, Dominique

    2018-03-08

    Axons link distant brain regions and are usually considered as simple transmission cables in which reliable propagation occurs once an action potential has been generated. Safe propagation of action potentials relies on specific ion channel expression at strategic points of the axon such as nodes of Ranvier or axonal branch points. However, while action potentials are generally considered as the quantum of neuronal information, their signaling is not entirely digital. In fact, both their shape and their conduction speed have been shown to be modulated by activity, leading to regulations of synaptic latency and synaptic strength. We report here newly identified mechanisms of (1) safe spike propagation along the axon, (2) compartmentalization of action potential shape in the axon, (3) analog modulation of spike-evoked synaptic transmission and (4) alteration in conduction time after persistent regulation of axon morphology in central neurons. We discuss the contribution of these regulations in information processing. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Wave equations for pulse propagation

    International Nuclear Information System (INIS)

    Shore, B.W.

    1987-01-01

    Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity. The memo discusses various ways of characterizing the polarization characteristics of plane waves, that is, of parameterizing a transverse unit vector, such as the Jones vector, the Stokes vector, and the Poincare sphere. It discusses the connection between macroscopically defined quantities, such as the intensity or, more generally, the Stokes parameters, and microscopic field amplitudes. The material presented here is a portion of a more extensive treatment of propagation to be presented separately. The equations presented here have been described in various books and articles. They are collected here as a summary and review of theory needed when treating pulse propagation

  14. The drift-diffusion interpretation of the electron current within the organic semiconductor characterized by the bulk single energy trap level

    Science.gov (United States)

    Cvikl, B.

    2010-01-01

    The closed solution for the internal electric field and the total charge density derived in the drift-diffusion approximation for the model of a single layer organic semiconductor structure characterized by the bulk shallow single trap-charge energy level is presented. The solutions for two examples of electric field boundary conditions are tested on room temperature current density-voltage data of the electron conducting aluminum/tris(8-hydroxyquinoline aluminum/calcium structure [W. Brütting et al., Synth. Met. 122, 99 (2001)] for which jexp∝Va3.4, within the interval of bias 0.4 V≤Va≤7. In each case investigated the apparent electron mobility determined at given bias is distributed within a given, finite interval of values. The bias dependence of the logarithm of their lower limit, i.e., their minimum values, is found to be in each case, to a good approximation, proportional to the square root of the applied electric field. On account of the bias dependence as incorporated in the minimum value of the apparent electron mobility the spatial distribution of the organic bulk electric field as well as the total charge density turn out to be bias independent. The first case investigated is based on the boundary condition of zero electric field at the electron injection interface. It is shown that for minimum valued apparent mobilities, the strong but finite accumulation of electrons close to the anode is obtained, which characterize the inverted space charge limited current (SCLC) effect. The second example refers to the internal electric field allowing for self-adjustment of its boundary values. The total electron charge density is than found typically to be of U shape, which may, depending on the parameters, peak at both or at either Alq3 boundary. It is this example in which the proper SCLC effect is consequently predicted. In each of the above two cases, the calculations predict the minimum values of the electron apparent mobility, which substantially

  15. A 3D thermal runaway propagation model for a large format lithium ion battery module

    International Nuclear Information System (INIS)

    Feng, Xuning; Lu, Languang; Ouyang, Minggao; Li, Jiangqiu; He, Xiangming

    2016-01-01

    In this paper, a 3D thermal runaway (TR) propagation model is built for a large format lithium ion battery module. The 3D TR propagation model is built based on the energy balance equation. Empirical equations are utilized to simplify the calculation of the chemical kinetics for TR, whereas equivalent thermal resistant layer is employed to simplify the heat transfer through the thin thermal layer. The 3D TR propagation model is validated by experiment and can provide beneficial discussions on the mechanisms of TR propagation. According to the modeling analysis of the 3D model, the TR propagation can be delayed or prevented through: 1) increasing the TR triggering temperature; 2) reducing the total electric energy released during TR; 3) enhancing the heat dissipation level; 4) adding extra thermal resistant layer between adjacent batteries. The TR propagation is successfully prevented in the model and validated by experiment. The model with 3D temperature distribution provides a beneficial tool for researchers to study the TR propagation mechanisms and for engineers to design a safer battery pack. - Highlights: • A 3D thermal runaway (TR) propagation model for Li-ion battery pack is built. • The 3D TR propagation model can fit experimental results well. • Temperature distributions during TR propagation are presented using the 3D model. • Modeling analysis provides solutions for the prevention of TR propagation. • Quantified solutions to prevent TR propagation in battery pack are discussed.

  16. Wave propagation in electromagnetic media

    International Nuclear Information System (INIS)

    Davis, J.L.

    1990-01-01

    This book is concerned with wave propagation in reacting media, specifically in electromagnetic materials. An account is presented of the mathematical methods of wave phenomena in electromagnetic materials. The author presents the theory of time-varying electromagnetic fields, which involves a discussion of Faraday's laws, Maxwell's equations and their application to electromagnetic wave propagation under a variety of conditions. The author gives a discussion of magnetohydrodynamics and plasma physics. Chapters are included on quantum mechanics and the theory of relativity. The mathematical foundation of electromagnetic waves vis a vis partial differential equations is discussed

  17. Vegetative propagation of Bambusa vulgaris

    Directory of Open Access Journals (Sweden)

    Rafael Malfitano Braga

    2017-06-01

    Full Text Available Bamboo is an important source of raw material of multiple uses. The development of simple techniques for its propagation is a practical way to enable its implementation in ownership of low technology. The present work had the objective of evaluating artisanal propagation methods for Bambusa vulgaris. Two types of propagules were tested, with buds budded or not, and three relative positions to the removal of vegetative material on the culm. The best propagule was with only one node, extracted from the lower thirds of the stem, presenting 72% of rooting. This result demonstrates its potential for seedling production of this species under low tech.

  18. Nonequilibrium theory of flame propagation

    International Nuclear Information System (INIS)

    Merzhanov, A.G.

    1995-01-01

    The nonequilibrium theory of flame propagation is considered as applied to the following three processes of wave propagation: the combustion waves of the second kind, the combustion waves with broad reaction zones, and the combustion waves with chemical stages. Kinetic and combustion wave parameters are presented for different in composition mixtures of boron and transition metals, such as Zr, Hf, Ti, Nb, Ta, Mo, as well as for the Ta-N, Zr-C-H, Nb-B-O systems to illustrate specific features of the above-mentioned processes [ru

  19. Analyzing the Environmental Impacts of Laptop Enclosures Using Screening-Level Life Cycle Assessment to Support Sustainable Consumer Electronics

    Science.gov (United States)

    With the ever-increasing amount of consumer electronics in service, it is essential industries and policy-makers work together to develop ways to manufacture more environmentally sustainable IT products which meet the needs of society. The objective of this study was to better un...

  20. Do Students Using Electronic Books Display Different Reading Comprehension and Motivation Levels than Students Using Traditional Print Books?

    Science.gov (United States)

    Wells, Casey L.

    2012-01-01

    The effect of electronic books on the reading comprehension of middle and high school students was examined using an experimental posttest-only control-group design. A convenience sample of 140 randomly assigned middle and high school English students at an independent school in eastern North Carolina participated. Half of the students used…

  1. Electronic structure and core-level spectra of light actinide dioxides in the dynamical mean-field theory

    Czech Academy of Sciences Publication Activity Database

    Kolorenč, Jindřich; Shick, Alexander; Lichtenstein, A.I.

    2015-01-01

    Roč. 92, č. 8 (2015), "085125-1"-"085125-10" ISSN 1098-0121 R&D Projects: GA ČR GC15-05872J Institutional support: RVO:68378271 Keywords : electronic-structure calculations * dynamical mean-field theory * Mott insulators * actinides * oxides * photoemission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  2. The impact of PMSE and NLC particles on VLF propagation

    Directory of Open Access Journals (Sweden)

    D. Nunn

    2004-04-01

    Full Text Available PMSE or Polar Mesosphere Summer Echoes are a well-known phenomenon in the summer northern polar regions, in which anomalous VHF/UHF radar echoes are returned from heights ~85km. Noctilucent clouds and electron density biteouts are two phenomena that sometimes occur together with PMSE. Electron density biteouts are electron density depletion layers of up to 90%, which may be several kms thick. Using the NOSC Modefndr code based on Wait's modal theory for subionospheric propagation, we calculate the shifts in received VLF amplitude and phase that occur as a result of electron density biteouts. The code assumes a homogeneous background ionosphere and a homogeneous biteout layer along the Great Circle Path (GCP corridor, for transmitter receiver path lengths in the range of 500–6000km.

    For profiles during the 10h about midnight and under quiet geomagnetic conditions, where the electron density at 85km would normally be less than 500el/cc, it was found that received signal perturbations were significant, of the order of 1–4dB and 5–40° of phase. Perturbation amplitudes increase roughly as the square root of frequency. At short range perturbations are rather erratic, but more consistent at large ranges, readily interpretable in terms of the shifts in excitation factor, attenuation factor and v/c ratios for Wait's modes. Under these conditions such shifts should be detectable by a well constituted experiment involving multiple paths and multiple frequencies in the north polar region in summer. It is anticipated that VLF propagation could be a valuable diagnostic for biteout/PMSE when electron density at 85km is under 500el/cc, under which circumstances PMSE are not directly detectable by VHF/UHF radars.

    Key words. Electromagnetism (wave propagation – Ionosphere (polar ionosphere – Radioscience (ionospheric propagation

  3. Assessment of homogeneity of candidate reference material at the nanogram level and investigation on representativeness of single particle analysis using electron probe X ray microanalysis

    International Nuclear Information System (INIS)

    Ro, Chul-Un; Hoornaerta, S.; Griekena, R. van

    2002-01-01

    Particulate samples of a candidate reference material are evaluated on their homogeneity from bottle to bottle using electron probe X ray microanalysis technique. The evaluation on the homogeneity is done by the utilization of the Kolmogorov-Smirnov statistics to the processing of the quantitative electron probe X ray microanalysis data. Due to a limitation, existing even in computer controlled electron probe X ray microanalysis, in terms of analysis time and expenses, the number of particles analyzed is much smaller compared to that in the sample. Therefore, it is investigated whether this technique provides representative analysis results for the characteristics of the sample, even though a very small portion of the sample is really analyzed. Furthermore, the required number of particles for the analysis, to insure a certain level of reproducibility, e.g. 5% relative standard deviation, is determined by the application of the Ingamells sampling theory. (author)

  4. Excitation of propagating surface plasmons with a scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

    2011-01-01

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 μm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  5. Excitation of propagating surface plasmons with a scanning tunnelling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G, E-mail: Elizabeth.Boer-Duchemin@u-psud.fr [Institut des Sciences Moleculaire d' Orsay (ISMO), CNRS Universite Paris-Sud, 91405 Orsay (France)

    2011-04-29

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 {mu}m. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  6. A Study on the Radio Propagation in the Korean Ionosphere

    Directory of Open Access Journals (Sweden)

    Seok-Hee Bae

    1992-06-01

    Full Text Available The effects of the ionosphere on the radio wave propagation are scattering of radio waves, attenuation, angle error, ranging error, and time delay. If ionospheric conditions are suitable, the charged particles can remove energy from radio waves and thus attenuate the signal. Also, a radio wave traveling a path along which the electron density is not constant undergoes changes in direction, position and time of propagation. The present study is based on Korean ionospheric data obtained at the AnYong Radio Research Institute from Jan. 1985 through Oct. 1989. The data are used to simulate the Korean ionosphere following the Chapman law. The effects of the model ionosphere on the radio wave propagation, such as the angle, position error, time delay, and the attenuation, are studies for the various cases of the wave frequency and the altitude.

  7. Prepulse effect on intense femtosecond laser pulse propagation in gas

    International Nuclear Information System (INIS)

    Giulietti, Antonio; Tomassini, Paolo; Galimberti, Marco; Giulietti, Danilo; Gizzi, Leonida A.; Koester, Petra; Labate, Luca; Ceccotti, Tiberio; D'Oliveira, Pascal; Auguste, Thierry; Monot, Pascal; Martin, Philippe

    2006-01-01

    The propagation of an ultrashort laser pulse can be affected by the light reaching the medium before the pulse. This can cause a serious drawback to possible applications. The propagation in He of an intense 60-fs pulse delivered by a Ti:sapphire laser in the chirped pulse amplification (CPA) mode has been investigated in conditions of interest for laser-plasma acceleration of electrons. The effects of both nanosecond amplified spontaneous emission and picosecond pedestals have been clearly identified. There is evidence that such effects are basically of refractive nature and that they are not detrimental for the propagation of a CPA pulse focused to moderately relativistic intensity. The observations are fully consistent with numerical simulations and can contribute to the search of a stable regime for laser acceleration

  8. Physics of Earthquake Rupture Propagation

    Science.gov (United States)

    Xu, Shiqing; Fukuyama, Eiichi; Sagy, Amir; Doan, Mai-Linh

    2018-05-01

    A comprehensive understanding of earthquake rupture propagation requires the study of not only the sudden release of elastic strain energy during co-seismic slip, but also of other processes that operate at a variety of spatiotemporal scales. For example, the accumulation of the elastic strain energy usually takes decades to hundreds of years, and rupture propagation and termination modify the bulk properties of the surrounding medium that can influence the behavior of future earthquakes. To share recent findings in the multiscale investigation of earthquake rupture propagation, we held a session entitled "Physics of Earthquake Rupture Propagation" during the 2016 American Geophysical Union (AGU) Fall Meeting in San Francisco. The session included 46 poster and 32 oral presentations, reporting observations of natural earthquakes, numerical and experimental simulations of earthquake ruptures, and studies of earthquake fault friction. These presentations and discussions during and after the session suggested a need to document more formally the research findings, particularly new observations and views different from conventional ones, complexities in fault zone properties and loading conditions, the diversity of fault slip modes and their interactions, the evaluation of observational and model uncertainties, and comparison between empirical and physics-based models. Therefore, we organize this Special Issue (SI) of Tectonophysics under the same title as our AGU session, hoping to inspire future investigations. Eighteen articles (marked with "this issue") are included in this SI and grouped into the following six categories.

  9. Invisibility cloaking without superluminal propagation

    Energy Technology Data Exchange (ETDEWEB)

    Perczel, Janos; Leonhardt, Ulf [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Tyc, Tomas, E-mail: jp394@st-andrews.ac.uk, E-mail: tomtyc@physics.muni.cz, E-mail: ulf@st-andrews.ac.uk [Faculty of Science, Kotlarska 2 and Faculty of Informatics, Botanicka 68a, Masaryk University, 61137 Brno (Czech Republic)

    2011-08-15

    Conventional cloaking based on Euclidean transformation optics requires that the speed of light should tend to infinity on the inner surface of the cloak. Non-Euclidean cloaking still needs media with superluminal propagation. Here we show by giving an example that this is no longer necessary.

  10. Propagating Class and Method Combination

    DEFF Research Database (Denmark)

    Ernst, Erik

    1999-01-01

    number of implicit combinations. For example, it is possible to specify separate aspects of a family of classes, and then combine several aspects into a full-fledged class family. The combination expressions would explicitly combine whole-family aspects, and by propagation implicitly combine the aspects...

  11. Propagation modeling in a manufacturing environment

    Energy Technology Data Exchange (ETDEWEB)

    Birdwell, J.D.; Horn, R.D.; Rader, M.S. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Electrical Engineering; Shourbaji, A.A. [Oak Ridge Centers for Mfg. Technology, TN (United States)

    1995-12-31

    Wireless sensors which utilize low power spread spectrum data transmission have significant potential in industrial environments due to low cabling and installation costs. In addition, this technology imposes fewer constraints upon placement due to cable routing, allowing sensors to be installed in areas with poor access. Limitations are imposed on sensor and receiver placement by electromagnetic propagation effects in the industrial environment, including multipath and the presence of absorbing media. This paper explores the electromagnetic analysis of potential wireless sensor applications using commercially available finite element software. In addition, since the applications environment is often at least partially specified in electronic form using computer-aided drafting software, the importation of information from this software is discussed. Both three-dimensional and two-dimensional examples are presented which demonstrate the utility and limitations of the method.

  12. Propagation of an ionizing surface electromagnetic wave

    Energy Technology Data Exchange (ETDEWEB)

    Boev, A.G.; Prokopov, A.V.

    1976-11-01

    The propagation of an rf surface wave in a plasma which is ionized by the wave itself is analyzed. The exact solution of the nonlinear Maxwell equations is discussed for the case in which the density of plasma electrons is an exponential function of the square of the electric field. The range over which the surface wave exists and the frequency dependence of the phase velocity are found. A detailed analysis is given for the case of a plasma whose initial density exceeds the critical density at the wave frequency. An increase in the wave amplitude is shown to expand the frequency range over which the plasma is transparent; The energy flux in the plasma tends toward a certain finite value which is governed by the effective ionization field.

  13. Effects of water stress on photosynthetic electron transport, photophosphorylation, and metabolite levels of Xanthium strumarium mesophyll cells.

    Science.gov (United States)

    Sharkey, T D; Badger, M R

    1982-12-01

    Several component processes of photosynthesis were measured in osmotically stressed mesophyll cells of Xanthium strumarium L. The ribulose-1,5-bisphosphate regeneration capacity was reduced by water stress. Photophoshorylation was sensitive to water stress but photosynthetic electron transport was unaffected by water potentials down to-40 bar (-4 MPa). The concentrations of several intermediates of the photosynthetic carbon-reduction cycle remained relatively constant and did not indicate that ATP supply was limiting photosynthesis in the water-stressed cells.

  14. Taking worker productivity to a new level? Electronic Monitoring in homecare - the (re)production of unpaid labour

    OpenAIRE

    Sian, Moore; Hayes, Lydia

    2017-01-01

    The editors of this journal have outlined the capacity of digital technology to restructure the temporal dimensions of work and called for further focused empirical study (Howcroft and Taylor, 2014). This article explores the impact of the Electronic Monitoring (EM) of homecare work on working time in the context of severe financial pressures on public sector provision of social care in the UK. Homecare workers are overwhelmingly women and provide personal care to older and disabled people in...

  15. Propagation speed and incident direction of transient ionospheric disturbance (TID)

    International Nuclear Information System (INIS)

    Maeda, Sawako; Handa, Shun.

    1978-01-01

    It is well known that large scale transient ionospheric disturbance (ls-TID) of period from 20 min to 3 hours and spatial wave length from hundreds to thousands km among TID's is in close correlation to geomagnetic activity at high latitude. Since TID well agrees with the wave characteristic of internal gravitational waves, it has come to be considered that the internal gravitational waves excited by Lorentz's force and joule heating due to the ionospheric current in auroral zone at the time of substorm cause disturbances to ionosphere electron density. The authors have examined the propagation speed and incident direction of TID using the data observed at 5 min intervals of maximum electron density in F layer during IGY (international geophysical year). The data was processed through a band pass filter because only the waves with period from 20 min to 3 hours were required. Since two proposed modes for ls-TID have been discussed, whose dispersion properties are different, it is necessary to determine the propagation characteristics of ls-TID by observation, and to clarify the propagation mechanism of internal gravitational waves. Therefore, the dependence of propagation speed on period has been investigated. It is concluded that ls-TID was observed at the time of polar magnetic field disturbances, the average propagation speed was about 500 m/s and the incident direction was north-north east for the variation of from 20 min to 3 hours, and as for the dependence of propagation speed on period, the average speed was about 670 m/s for the long period change (approximately 100 min period), and about 440 m/s for short period change (approximately 30 min period) and the dispersion was observed. (Wakatsuki, Y.)

  16. High current relativistic beam propagates stably in gas surrounded by nonconducting walls

    International Nuclear Information System (INIS)

    Clark, J.C.

    1977-01-01

    LLL has been studying the propagation of high current electron beams for a number of years to understand their behavior for use in a variety of experimental uses. Our latest experiments have shown that a mildly relativistic electron beam of 10 to 15 kA and a pulse width of 30 to 40 ns can propagate stably and with no net current transfer in insulating tubes filled with neutral gases. These experiments have been performed in the Magnetic Fusion Energy program where Electronics Engineering has been operating an electron beam accelerator, designing some of the diagnostics, such as laser interferometers, and performing the experiments. This article briefly describes our experimental observations

  17. Focused proton beams propagating in reactor of fusion power plant

    Energy Technology Data Exchange (ETDEWEB)

    Niu, K [Teikyo Heisei Univ., Uruido, Ichihara, Chiba (Japan)

    1997-12-31

    One of the difficult tasks of light ion beam fusion is to propagate the beam in the reactor cavity and to focus the beam on the target. The light ion beam has a certain local divergence angle because there are several causes for divergence at the diode. The electrostatic force induced at the leading edge causes beam divergence during propagation. To confine the beam within a small radius during propagation, the magnetic field must be employed. Here the electron beam is proposed to be launched simultaneously with the launching of the proton beam. If the electron beam has the excess current, the beam induces a magnetic field in the negative azimuthal direction, which confines the ion beam within a small radius by the electrostatic field as well as the electron beam by the Lorentz force. The metal guide around the beam path helps the beam confinement and reduces the total amount of magnetic field energy induced by the electron current. (author). 2 figs., 15 refs.

  18. Time-dependent wave front propagation simulation of a hard x-ray split-and-delay unit: Towards a measurement of the temporal coherence properties of x-ray free electron lasers

    Directory of Open Access Journals (Sweden)

    S. Roling

    2014-11-01

    Full Text Available For the European x-ray free electron laser (XFEL a split-and-delay unit based on geometrical wavefront beam splitting and multilayer mirrors is built which covers the range of photon energies from 5 keV up to 20 keV. Maximum delays between Δτ=±2.5  ps at hν=20  keV and up to Δτ=±23  ps at hν=5  keV will be possible. Time-dependent wave-optics simulations have been performed by means of Synchrotron Radiation Workshop software for XFEL pulses at hν=5  keV. The XFEL radiation was simulated using results of time-dependent simulations applying the self-amplified spontaneous emission code FAST. Main features of the optical layout, including diffraction on the beam splitter edge and optics imperfections measured with a nanometer optic component measuring machine slope measuring profiler, were taken into account. The impact of these effects on the characterization of the temporal properties of XFEL pulses is analyzed. An approach based on fast Fourier transformation allows for the evaluation of the temporal coherence despite large wavefront distortions caused by the optics imperfections. In this way, the fringes resulting from time-dependent two-beam interference can be filtered and evaluated yielding a coherence time of τ_{c}=0.187  fs (HWHM for real, nonperfect mirrors, while for ideal mirrors a coherence time of τ_{c}=0.191  fs (HWHM is expected.

  19. High-performance n-type organic semiconductors: incorporating specific electron-withdrawing motifs to achieve tight molecular stacking and optimized energy levels.

    Science.gov (United States)

    Yun, Sun Woo; Kim, Jong H; Shin, Seunghoon; Yang, Hoichang; An, Byeong-Kwan; Yang, Lin; Park, Soo Young

    2012-02-14

    Novel π–conjugated cyanostilbene-based semiconductors (Hex-3,5-TFPTA and Hex-4-TFPTA) with tight molecular stacking and optimized energy levels are synthesized. Hex-4-TFPTA exhibits high-performance n-type organic field-effect transistor (OFET) properties with electron mobilities as high as 2.14 cm2 V−1s−1 and on-off current ratios Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Network-based analysis of software change propagation.

    Science.gov (United States)

    Wang, Rongcun; Huang, Rubing; Qu, Binbin

    2014-01-01

    The object-oriented software systems frequently evolve to meet new change requirements. Understanding the characteristics of changes aids testers and system designers to improve the quality of softwares. Identifying important modules becomes a key issue in the process of evolution. In this context, a novel network-based approach is proposed to comprehensively investigate change distributions and the correlation between centrality measures and the scope of change propagation. First, software dependency networks are constructed at class level. And then, the number of times of cochanges among classes is minded from software repositories. According to the dependency relationships and the number of times of cochanges among classes, the scope of change propagation is calculated. Using Spearman rank correlation analyzes the correlation between centrality measures and the scope of change propagation. Three case studies on java open source software projects Findbugs, Hibernate, and Spring are conducted to research the characteristics of change propagation. Experimental results show that (i) change distribution is very uneven; (ii) PageRank, Degree, and CIRank are significantly correlated to the scope of change propagation. Particularly, CIRank shows higher correlation coefficient, which suggests it can be a more useful indicator for measuring the scope of change propagation of classes in object-oriented software system.