WorldWideScience

Sample records for environmental light propagation

  1. Light propagation in linear optical media

    CERN Document Server

    Gillen, Glen D; Guha, Shekhar

    2013-01-01

    Light Propagation in Linear Optical Media describes light propagation in linear media by expanding on diffraction theories beyond what is available in classic optics books. In one volume, this book combines the treatment of light propagation through various media, interfaces, and apertures using scalar and vector diffraction theories. After covering the fundamentals of light and physical optics, the authors discuss light traveling within an anisotropic crystal and present mathematical models for light propagation across planar boundaries between different media. They describe the propagation o

  2. Demonstration of slow light propagation in an optical fiber under dual pump light with co-propagation and counter-propagation

    Science.gov (United States)

    Qiu, Wei; Liu, Jianjun; Wang, Yuda; Yang, Yujing; Gao, Yuan; Lv, Pin; Jiang, Qiuli

    2018-04-01

    In this paper, a general theory of coherent population oscillation effect in an Er3+ -doped fiber under the dual-frequency pumping laser with counter-propagation and co-propagation at room temperature is presented. Using the numerical simulation, in case of dual frequency light waves (1480 nm and 980 nm) with co-propagation and counter-propagation, we analyze the effect of the pump optical power ratio (M) on the group speed of light. The group velocity of light can be varied with the change of M. We research the time delay and fractional delay in an Er3+-doped fiber under the dual-frequency pumping laser with counter-propagation and co-propagation. Compared to the methods of the single pumping, the larger time delay can be got by using the technique of dual-frequency laser pumped fiber with co-propagation and counter-propagation.

  3. Propagation and scattering of light in fluctuating media

    Science.gov (United States)

    Kuz'min, V. L.; Romanov, V. P.; Zubkov, L. A.

    1994-11-01

    The monograph deals with the problems of the propagation and scattering of light in molecular media. The explicit statistical mechanical averaging procedure for the equations of electrodynamics is developed. It permits to transform the molecular level description into the macroscopic one for the electrodynamics of the fluctuating media. In the framework of such an approach, the problems of the molecular correlation contribution into the dielectric permeability, of the calculation of the reflection coefficients with an account of surface layers and of the multiple light scattering are considered. The developed theory is applied to the description of the critical opalescence, the coherent backscattering enhancement, the light scattering depolarization phenomena and the propagation and scattering of light in anisotropic media, including the case of liquid crystals.

  4. 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.

  5. 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)

  6. On the Propagation of Light in an Expanding Universe

    Directory of Open Access Journals (Sweden)

    Yuri Heymann

    2013-07-01

    Full Text Available The equation of the propagation of light in an expanding Universe is derived based on the definition of comoving distances. A numerical method is proposed to solve this equation jointly with the Friedmann equation. As the equation of the propagation of light in an expanding Universe defines a horizon of the visible Universe, this puts a constraint on cosmological models in order to be consistent with an upper limit for redshifts observed from galaxies. This puzzle is challenging current expansionist cosmological models.

  7. Tracing light propagation to the intrinsic accuracy of spacetime geometry

    International Nuclear Information System (INIS)

    Crosta, Mariateresa

    2011-01-01

    Advancement in astronomical observations requires codification of light propagation and of the processes of its physical measurement at a high level of accuracy. This could unveil a new window of several subtle relativistic effects suffered by light while propagating. Indeed, light modeling and its subsequent detection should be conceived in a fully relativistic context, in order to interpret the outcome of the observing process in accordance with the geometrical environment affecting light propagation itself and the precepts of measurement. This paper deals with the complexity of such a topic by showing how the geometrical framework of RAMOD, a relativistic model initially developed for astrometric observations in the visible, constitutes an appropriate environment for back-tracing photons. Through gauging the energy content of a given gravitationally bound system, the geometrical aspects that match the required accuracy of present and future observational capabilities are evidenced. Then, by comparing different formulations of the null geodesic, their domain of validity within the given geometrical scheme is refined. Finally, by proving its ability in retrieving recent literature cases, RAMOD is promoted as a measurement-based general relativistic method for any present and future advancement in the light-tracing problem. (paper)

  8. Light propagation in a magneto-optical hyperbolic biaxial crystal

    Science.gov (United States)

    Kuznetsov, Evgeniy V.; Merzlikin, Alexander M.

    2017-12-01

    The light propagation through a magneto-optical hyperbolic biaxial crystal is investigated. Magnetization of the structure results in splitting and reconnection of an isofrequency near the self-intersection point and thus it leads to the disappearance of conical refraction in a crystal. In its turn the isofrequency splitting leads to band gap opening and makes it possible to steer the beam. These effects allow to control the light propagation by means of an external magnetostatic field. The Poynting's vector distribution in the crystal is calculated by means of a Fourier transform in order to demonstrate the aforementioned effects.

  9. Light Propagation Through Transition Metal Dichalcogenides

    Science.gov (United States)

    Stevens, Christopher; Paul, Jagannath; Zhang, Haoxiang; Stier, Andreas; Karaiskaj, Denis

    C.E.STEVENS,J.PAUL,H.ZHANG, Dept. of Physics, University of South Florida, Tampa, Florida 33620, USA. A.V.STIER, National High Magnetic Field Laboratory, Los Alamos, New Mexico 87545, D. KARAISKAJ, Dept. of Physics, University of South Florida, Tampa, Florida 33620, USA. - Using broadband light, the propagation of light through MoSe2 and WSe2 was investigated. Measuring the optical density for samples with different number of layers, we found that these values differ from what the Beer-Lambert Law predicts. The results were also modeled theoretically according to an effective two-band model. Funded by The Department of Energy.

  10. Propagation of polarized light through azobenzene polyester films

    DEFF Research Database (Denmark)

    Nedelchev, L; Matharu, A; Nikolova, Ludmila

    2002-01-01

    When elliptically polarized light of appropriate wavelength Corresponding to trans-cis-trans isomerisation process is incident on thin films of azobenzene polyesters, a helical structure is induced. We investigate the propagation of the exciting light beam (self-induced) as well as a probe light...... beam outside the absorption band through the polyester films. Investigations are carried out in one amorphous and one liquid crystalline polyester. We show that amorphous polyester after irradiation behaves like classical helical material....

  11. Propagation and storing of light in optically modified atomic media

    International Nuclear Information System (INIS)

    Zaremba, Jaroslaw

    2010-01-01

    Coherent interactions of laser light with atomic ensembles allow one to modify dispersive properties of a medium and lead to new optical phenomena. Studies of the controlled light propagation and storing in such media have recently become a dynamically developing field of research motivated both by the fundamental character of the processes and by potential applications. This article briefly reviews basic theoretical approach to the dynamics of the propagation of laser pulses in optically modified media. The method and the physical processes are discussed that allow one to slow down the group velocity of laser pulse to zero (stopping of light), to transfer the state of a light pulse to atomic coherences and to restore the pulse. The interpretation of these phenomena in the formalism of dark-state polaritons is presented. Examples of possible coherent manipulations on a stored light are also discussed.

  12. Propagation and storing of light in optically modified atomic media

    Energy Technology Data Exchange (ETDEWEB)

    Zaremba, Jaroslaw, E-mail: zaremba@fizyka.iomk.p [Institute of Physics Nicolaus Copernicus University ul. Grudziadzka 5/7 87 100 Torun (Poland)

    2010-03-01

    Coherent interactions of laser light with atomic ensembles allow one to modify dispersive properties of a medium and lead to new optical phenomena. Studies of the controlled light propagation and storing in such media have recently become a dynamically developing field of research motivated both by the fundamental character of the processes and by potential applications. This article briefly reviews basic theoretical approach to the dynamics of the propagation of laser pulses in optically modified media. The method and the physical processes are discussed that allow one to slow down the group velocity of laser pulse to zero (stopping of light), to transfer the state of a light pulse to atomic coherences and to restore the pulse. The interpretation of these phenomena in the formalism of dark-state polaritons is presented. Examples of possible coherent manipulations on a stored light are also discussed.

  13. 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.

  14. Slow light and pulse propagation in semiconductor waveguides

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann

    This thesis concerns the propagation of optical pulses in semiconductor waveguide structures with particular focus on methods for achieving slow light or signal delays. Experimental pulse propagation measurements of pulses with a duration of 180 fs, transmitted through quantum well based waveguide...... structures, are presented. Simultaneous measurements of the pulse transmission and delay are measured as a function of input pulse energy for various applied electrical potentials. Electrically controlled pulse delay and advancement are demonstrated and compared with a theoretical model. The limits...... of the model as well as the underlying physical mechanisms are analysed and discussed. A method to achieve slow light by electromagnetically induced transparency (EIT) in an inhomogeneously broadened quantum dot medium is proposed. The basic principles of EIT are assessed and the main dissimilarities between...

  15. Subluminal and superluminal propagation of light in an N-type medium

    International Nuclear Information System (INIS)

    Han Dingan; Guo Hong; Bai Yanfeng; Sun Hui

    2005-01-01

    For a three-level electromagnetically induced transparency (EIT) atomic system, we show that, adding a third driving field coupled to a fourth state, the properties of the weak probe light propagation are greatly changed. Due to the increase of the driving field, when the driving and the coupling detunings are zero, the light propagation can be changed from subluminal to superluminal. Also, the analytical solution exhibiting superluminal group velocity is given at the zero probe detuning

  16. Light propagation analysis in nervous tissue for wireless optogenetic nanonetworks

    Science.gov (United States)

    Wirdatmadja, Stefanus; Johari, Pedram; Balasubramaniam, Sasitharan; Bae, Yongho; Stachowiak, Michal K.; Jornet, Josep M.

    2018-02-01

    In recent years, numerous methods have been sought for developing novel solutions to counter neurodegenerative diseases. An objective that is being investigated by researchers is to develop cortical implants that are able to wirelessly stimulate neurons at the single cell level. This is a major development compared to current solutions that use electrodes, which are only able to target a population of neurons, or optogenetics, which requires optical fiber-leads to be embedded deep into the brain. In this direction, the concept of wireless optogenetic nanonetworks has been recently introduced. In such architecture, miniature devices are implanted in the cortex for neuronal stimulation through optogenetics. One of the aspects that will determine the topology and performance of wireless optogenetic nanonetworks is related to light propagation in genetically-engineered neurons. In this paper, a channel model that captures the peculiarities of light propagation in neurons is developed. First, the light propagation behavior using the modified Beer-Lambert law is analyzed based on the photon transport through the nervous tissue. This includes analyzing the scattering light diffraction and diffusive reflection that results from the absorption of neural cell chromophores, as well as validating the results by means of extensive multiphysics simulations. Then, analysis is conducted on the path loss through cells at different layers of the cortex by taking into account the multi-path phenomenon. Results show that there is a light focusing effect in the soma of neurons that can potentially help the to stimulate the target cells.

  17. Generalized Beer-Lambert model for near-infrared light propagation in thick biological tissues

    Science.gov (United States)

    Bhatt, Manish; Ayyalasomayajula, Kalyan R.; Yalavarthy, Phaneendra K.

    2016-07-01

    The attenuation of near-infrared (NIR) light intensity as it propagates in a turbid medium like biological tissue is described by modified the Beer-Lambert law (MBLL). The MBLL is generally used to quantify the changes in tissue chromophore concentrations for NIR spectroscopic data analysis. Even though MBLL is effective in terms of providing qualitative comparison, it suffers from its applicability across tissue types and tissue dimensions. In this work, we introduce Lambert-W function-based modeling for light propagation in biological tissues, which is a generalized version of the Beer-Lambert model. The proposed modeling provides parametrization of tissue properties, which includes two attenuation coefficients μ0 and η. We validated our model against the Monte Carlo simulation, which is the gold standard for modeling NIR light propagation in biological tissue. We included numerous human and animal tissues to validate the proposed empirical model, including an inhomogeneous adult human head model. The proposed model, which has a closed form (analytical), is first of its kind in providing accurate modeling of NIR light propagation in biological tissues.

  18. Light propagation with phase discontinuities: generalized laws of reflection and refraction.

    Science.gov (United States)

    Yu, Nanfang; Genevet, Patrice; Kats, Mikhail A; Aieta, Francesco; Tetienne, Jean-Philippe; Capasso, Federico; Gaburro, Zeno

    2011-10-21

    Conventional optical components rely on gradual phase shifts accumulated during light propagation to shape light beams. New degrees of freedom are attained by introducing abrupt phase changes over the scale of the wavelength. A two-dimensional array of optical resonators with spatially varying phase response and subwavelength separation can imprint such phase discontinuities on propagating light as it traverses the interface between two media. Anomalous reflection and refraction phenomena are observed in this regime in optically thin arrays of metallic antennas on silicon with a linear phase variation along the interface, which are in excellent agreement with generalized laws derived from Fermat's principle. Phase discontinuities provide great flexibility in the design of light beams, as illustrated by the generation of optical vortices through use of planar designer metallic interfaces.

  19. Regularization of the light-cone gauge gluon propagator singularities using sub-gauge conditions

    Energy Technology Data Exchange (ETDEWEB)

    Chirilli, Giovanni A.; Kovchegov, Yuri V.; Wertepny, Douglas E. [Department of Physics, The Ohio State University,191 W Woodruff Ave, Columbus, OH 43210 (United States)

    2015-12-21

    Perturbative QCD calculations in the light-cone gauge have long suffered from the ambiguity associated with the regularization of the poles in the gluon propagator. In this work we study sub-gauge conditions within the light-cone gauge corresponding to several known ways of regulating the gluon propagator. Using the functional integral calculation of the gluon propagator, we rederive the known sub-gauge conditions for the θ-function gauges and identify the sub-gauge condition for the principal value (PV) regularization of the gluon propagator’s light-cone poles. The obtained sub-gauge condition for the PV case is further verified by a sample calculation of the classical Yang-Mills field of two collinear ultrarelativistic point color charges. Our method does not allow one to construct a sub-gauge condition corresponding to the well-known Mandelstam-Leibbrandt prescription for regulating the gluon propagator poles.

  20. Modes in light wave propagating in semiconductor laser

    Science.gov (United States)

    Manko, Margarita A.

    1994-01-01

    The study of semiconductor laser based on an analogy of the Schrodinger equation and an equation describing light wave propagation in nonhomogeneous medium is developed. The active region of semiconductor laser is considered as optical waveguide confining the electromagnetic field in the cross-section (x,y) and allowing waveguide propagation along the laser resonator (z). The mode structure is investigated taking into account the transversal and what is the important part of the suggested consideration longitudinal nonhomogeneity of the optical waveguide. It is shown that the Gaussian modes in the case correspond to spatial squeezing and correlation. Spatially squeezed two-mode structure of nonhomogeneous optical waveguide is given explicitly. Distribution of light among the laser discrete modes is presented. Properties of the spatially squeezed two-mode field are described. The analog of Franck-Condon principle for finding the maxima of the distribution function and the analog of Ramsauer effect for control of spatial distribution of laser emission are discussed.

  1. Current-controlled light scattering and asymmetric plasmon propagation in graphene

    Science.gov (United States)

    Wenger, Tobias; Viola, Giovanni; Kinaret, Jari; Fogelström, Mikael; Tassin, Philippe

    2018-02-01

    We demonstrate that plasmons in graphene can be manipulated using a dc current. A source-drain current lifts the forward/backward degeneracy of the plasmons, creating two modes with different propagation properties parallel and antiparallel to the current. We show that the propagation length of the plasmon propagating parallel to the drift current is enhanced, while the propagation length for the antiparallel plasmon is suppressed. We also investigate the scattering of light off graphene due to the plasmons in a periodic dielectric environment and we find that the plasmon resonance separates in two peaks corresponding to the forward and backward plasmon modes. The narrower linewidth of the forward propagating plasmon may be of interest for refractive index sensing and the dc current control could be used for the modulation of mid-infrared electromagnetic radiation.

  2. Human tissue optical properties measurements and light propagation modelling

    CSIR Research Space (South Africa)

    Dam, JS

    2006-07-01

    Full Text Available Biomedical Optics is the study of the optical properties of living biological material, especially its scattering and absorption characteristics, and their significance to light propagation within the material. Determination of tissue optical...

  3. Propagation of coherent light pulses with PHASE

    Science.gov (United States)

    Bahrdt, J.; Flechsig, U.; Grizzoli, W.; Siewert, F.

    2014-09-01

    The current status of the software package PHASE for the propagation of coherent light pulses along a synchrotron radiation beamline is presented. PHASE is based on an asymptotic expansion of the Fresnel-Kirchhoff integral (stationary phase approximation) which is usually truncated at the 2nd order. The limits of this approximation as well as possible extensions to higher orders are discussed. The accuracy is benchmarked against a direct integration of the Fresnel-Kirchhoff integral. Long range slope errors of optical elements can be included by means of 8th order polynomials in the optical element coordinates w and l. Only recently, a method for the description of short range slope errors has been implemented. The accuracy of this method is evaluated and examples for realistic slope errors are given. PHASE can be run either from a built-in graphical user interface or from any script language. The latter method provides substantial flexibility. Optical elements including apertures can be combined. Complete wave packages can be propagated, as well. Fourier propagators are included in the package, thus, the user may choose between a variety of propagators. Several means to speed up the computation time were tested - among them are the parallelization in a multi core environment and the parallelization on a cluster.

  4. Light propagation in optical crystal powders: effects of particle size and volume filling factor

    International Nuclear Information System (INIS)

    GarcIa-Ramiro, B; Illarramendi, M A; Aramburu, I; Fernandez, J; Balda, R; Al-Saleh, M

    2007-01-01

    In this work, we analyse the light propagation in some laser and nonlinear crystal powders. In particular, we study the dependence of the diffusive absorption lengths and the transport lengths on particle size and volume filling factor. The theoretical calculations have been made by assuming a diffusive propagation of light in these materials

  5. Illumination of interior spaces by bended hollow light guides: Application of the theoretical light propagation method

    Energy Technology Data Exchange (ETDEWEB)

    Darula, Stanislav; Kocifaj, Miroslav; Kittler, Richard [ICA, Slovak Academy of Sciences, Bratislava (Slovakia); Kundracik, Frantisek [Department of Experimental Physics, FMPI, Comenius University, Bratislava (Slovakia)

    2010-12-15

    To ensure comfort and healthy conditions in interior spaces the thermal, acoustics and daylight factors of the environment have to be considered in the building design. Due to effective energy performance in buildings the new technology and applications also in daylight engineering are sought such as tubular light guides. These allow the transport of natural light into the building core reducing energy consumption. A lot of installations with various geometrical and optical properties can be applied in real buildings. The simplest set of tubular light guide consists of a transparent cupola, direct tube with high reflected inner surface and a ceiling cover or diffuser redistributing light into the interior. Such vertical tubular guide is often used on flat roofs. When the roof construction is inclined a bend in the light guide system has to be installed. In this case the cupola is set on the sloped roof which collects sunlight and skylight from the seen part of the sky hemisphere as well as that reflected from the ground and opposite facades. In comparison with the vertical tube some additional light losses and distortions of the propagated light have to be expected in bended tubular light guides. Recently the theoretical model of light propagation was already published and its applications are presented in this study solving illuminance distributions on the ceiling cover interface and further illuminance distribution on the working plane in the interior. (author)

  6. Direct mapping of light propagation in photonic crystal waveguides

    DEFF Research Database (Denmark)

    Bozhevolnyi, S.I.; Volkov, V.S.; Arentoft, J.

    2002-01-01

    Using near-field optical microscopy, we directly map the propagation of light in the wavelength range of 1510-1560 nm along bent photonic crystal waveguides formed by removing a single row of holes in the triangular 400-nm-period lattice and connected to access ridge waveguides, the structure being...

  7. Hybrid Monte Carlo-Diffusion Method For Light Propagation in Tissue With a Low-Scattering Region

    Science.gov (United States)

    Hayashi, Toshiyuki; Kashio, Yoshihiko; Okada, Eiji

    2003-06-01

    The heterogeneity of the tissues in a head, especially the low-scattering cerebrospinal fluid (CSF) layer surrounding the brain has previously been shown to strongly affect light propagation in the brain. The radiosity-diffusion method, in which the light propagation in the CSF layer is assumed to obey the radiosity theory, has been employed to predict the light propagation in head models. Although the CSF layer is assumed to be a nonscattering region in the radiosity-diffusion method, fine arachnoid trabeculae cause faint scattering in the CSF layer in real heads. A novel approach, the hybrid Monte Carlo-diffusion method, is proposed to calculate the head models, including the low-scattering region in which the light propagation does not obey neither the diffusion approximation nor the radiosity theory. The light propagation in the high-scattering region is calculated by means of the diffusion approximation solved by the finite-element method and that in the low-scattering region is predicted by the Monte Carlo method. The intensity and mean time of flight of the detected light for the head model with a low-scattering CSF layer calculated by the hybrid method agreed well with those by the Monte Carlo method, whereas the results calculated by means of the diffusion approximation included considerable error caused by the effect of the CSF layer. In the hybrid method, the time-consuming Monte Carlo calculation is employed only for the thin CSF layer, and hence, the computation time of the hybrid method is dramatically shorter than that of the Monte Carlo method.

  8. Self-propagating solar light reduction of graphite oxide in water

    Energy Technology Data Exchange (ETDEWEB)

    Todorova, N.; Giannakopoulou, T.; Boukos, N.; Vermisoglou, E. [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 153 41 Attikis (Greece); Lekakou, C. [Division of Mechanical, Medical, and Aerospace Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford (United Kingdom); Trapalis, C., E-mail: c.trapalis@inn.demokritos.gr [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 153 41 Attikis (Greece)

    2017-01-01

    Highlights: • Graphite oxide was partially reduced by solar light irradiation in water media. • No addition of catalysts nor reductive agent were used for the reduction. • Specific capacitance increased stepwise with increase of irradiation time. • Self-propagating reduction of graphene oxide by solar light is suggested. - Abstract: Graphite Oxide (GtO) is commonly used as an intermediate material for preparation of graphene in the form of reduced graphene oxide (rGO). Being a semiconductor with tunable band gap rGO is often coupled with various photocatalysts to enhance their visible light activity. The behavior of such rGO-based composites could be affected after prolonged exposure to solar light. In the present work, the alteration of the GtO properties under solar light irradiation is investigated. Water dispersions of GtO manufactured by oxidation of natural graphite via Hummers method were irradiated into solar light simulator for different periods of time without addition of catalysts or reductive agent. The FT-IR analysis of the treated dispersions revealed gradual reduction of the GtO with the increase of the irradiation time. The XRD, FT-IR and XPS analyses of the obtained solid materials confirmed the transition of GtO to rGO under solar light irradiation. The reduction of the GtO was also manifested by the CV measurements that revealed stepwise increase of the specific capacitance connected with the restoration of the sp{sup 2} domains. Photothermal self-propagating reduction of graphene oxide in aqueous media under solar light irradiation is suggested as a possible mechanism. The self-photoreduction of GtO utilizing solar light provides a green, sustainable route towards preparation of reduced graphene oxide. However, the instability of the GtO and partially reduced GO under irradiation should be considered when choosing the field of its application.

  9. The propagation of light pollution in the atmosphere

    Science.gov (United States)

    Cinzano, P.; Falchi, F.

    2012-12-01

    Recent methods to map artificial night-sky brightness and stellar visibility across large territories or their distribution over the entire sky at any site are based on computation of the propagation of light pollution with Garstang models, a simplified solution of the radiative transfer problem in the atmosphere that allows fast computation by reducing it to a ray-tracing approach. They are accurate for a clear atmosphere, when a two-scattering approximation is acceptable, which is the most common situation. We present here up-to-date extended Garstang models (EGM), which provide a more general numerical solution for the radiative transfer problem applied to the propagation of light pollution in the atmosphere. We also present the LPTRAN software package, an application of EGM to high-resolution Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) satellite measurements of artificial light emission and to GTOPO30 (Global 30 Arcsecond) digital elevation data, which provides an up-to-date method to predict the artificial brightness distribution of the night sky at any site in the world at any visible wavelength for a broad range of atmospheric situations and the artificial radiation density in the atmosphere across the territory. EGM account for (i) multiple scattering, (ii) wavelengths from 250 nm to infrared, (iii) the Earth's curvature and its screening effects, (iv) site and source elevation, (v) many kinds of atmosphere with the possibility of custom set-up (e.g. including thermal inversion layers), (vi) a mix of different boundary-layer aerosols and tropospheric aerosols, with the possibility of custom set-up, (vii) up to five aerosol layers in the upper atmosphere, including fresh and aged volcanic dust and meteoric dust, (viii) variations of the scattering phase function with elevation, (ix) continuum and line gas absorption from many species, ozone included, (x) up to five cloud layers, (xi) wavelength-dependent bidirectional

  10. Influence of refraction index strength on the light propagation in dielectrics material with periodic refraction index

    International Nuclear Information System (INIS)

    Hidayat, Arif; Latifah, Eny; Kurniati, Diana; Wisodo, Hari

    2016-01-01

    This study investigated the influence of refraction index strength on the light propagation in refraction index-varied dielectric material. This dielectric material served as photonic lattice. The behavior of light propagation influenced by variation of refraction index in photonic lattice was investigated. Modes of the guiding light were determined numerically using squared-operator iteration method. It was found that the greater the strength of refraction index, the smaller the guiding modes.

  11. Simulation of partially coherent light propagation using parallel computing devices

    Science.gov (United States)

    Magalhães, Tiago C.; Rebordão, José M.

    2017-08-01

    Light acquires or loses coherence and coherence is one of the few optical observables. Spectra can be derived from coherence functions and understanding any interferometric experiment is also relying upon coherence functions. Beyond the two limiting cases (full coherence or incoherence) the coherence of light is always partial and it changes with propagation. We have implemented a code to compute the propagation of partially coherent light from the source plane to the observation plane using parallel computing devices (PCDs). In this paper, we restrict the propagation in free space only. To this end, we used the Open Computing Language (OpenCL) and the open-source toolkit PyOpenCL, which gives access to OpenCL parallel computation through Python. To test our code, we chose two coherence source models: an incoherent source and a Gaussian Schell-model source. In the former case, we divided into two different source shapes: circular and rectangular. The results were compared to the theoretical values. Our implemented code allows one to choose between the PyOpenCL implementation and a standard one, i.e using the CPU only. To test the computation time for each implementation (PyOpenCL and standard), we used several computer systems with different CPUs and GPUs. We used powers of two for the dimensions of the cross-spectral density matrix (e.g. 324, 644) and a significant speed increase is observed in the PyOpenCL implementation when compared to the standard one. This can be an important tool for studying new source models.

  12. Stable propagation of light-ion beam in inertial confinement fusion

    International Nuclear Information System (INIS)

    Okada, T.; Murakami, H.

    1996-01-01

    The stabilization mechanism of the filamentation instability for a light ion beam (LIB) penetrating plasma is investigated. For the stabilization of the filamentation instability, external magnetic field which is parallel to the direction of the light ion beam propagation is applied. Linear growth rates of filamentation instabilities in a light ion beam-plasma system with an external magnetic field were obtained by means of a dispersion relation. Numerical simulations were carried out using the particle-in-cell (PIC) method. The stabilizing mechanism of the filamentation instability is described. The theory and simulation comparisons illustrate the results. (author). 1 tab., 1 fig., 10 refs

  13. Stable propagation of light-ion beam in inertial confinement fusion

    Energy Technology Data Exchange (ETDEWEB)

    Okada, T; Murakami, H [Tokyo Univ. of Agriculture and Technology, Koganei (Japan). Faculty of Technology

    1997-12-31

    The stabilization mechanism of the filamentation instability for a light ion beam (LIB) penetrating plasma is investigated. For the stabilization of the filamentation instability, external magnetic field which is parallel to the direction of the light ion beam propagation is applied. Linear growth rates of filamentation instabilities in a light ion beam-plasma system with an external magnetic field were obtained by means of a dispersion relation. Numerical simulations were carried out using the particle-in-cell (PIC) method. The stabilizing mechanism of the filamentation instability is described. The theory and simulation comparisons illustrate the results. (author). 1 tab., 1 fig., 10 refs.

  14. Standard error propagation in R-matrix model fitting for light elements

    International Nuclear Information System (INIS)

    Chen Zhenpeng; Zhang Rui; Sun Yeying; Liu Tingjin

    2003-01-01

    The error propagation features with R-matrix model fitting 7 Li, 11 B and 17 O systems were researched systematically. Some laws of error propagation were revealed, an empirical formula P j = U j c / U j d = K j · S-bar · √m / √N for describing standard error propagation was established, the most likely error ranges for standard cross sections of 6 Li(n,t), 10 B(n,α0) and 10 B(n,α1) were estimated. The problem that the standard error of light nuclei standard cross sections may be too small results mainly from the R-matrix model fitting, which is not perfect. Yet R-matrix model fitting is the most reliable evaluation method for such data. The error propagation features of R-matrix model fitting for compound nucleus system of 7 Li, 11 B and 17 O has been studied systematically, some laws of error propagation are revealed, and these findings are important in solving the problem mentioned above. Furthermore, these conclusions are suitable for similar model fitting in other scientific fields. (author)

  15. Light propagation in composite materials with gain layers

    International Nuclear Information System (INIS)

    Dorofeenko, Aleksandr V; Zyablovsky, A A; Pukhov, Aleksandr A; Lisyansky, A A; Vinogradov, Aleksei P

    2012-01-01

    Light propagation through a single gain layer and a multilayer system with gain layers is studied. Results obtained using the Fresnel formulas, Airy's series summation, and the numerical solution of the nonlinear Maxwell-Bloch equations by the finite difference time domain (FDTD) method are analyzed and compared. Normal and oblique propagation of a wave through a gain layer and a slab of a photonic crystal are examined. For the latter problem, the gain line may be situated in either the pass or stop band of the photonic crystal. It is shown that the monochromatic plane-wave approximation is generally inapplicable for active media, because it leads to results that violate causality. But the problem becomes physically meaningful and correct results can be obtained for all three approaches once the structure of the wavefront and the finite aperture of the beam are taken into account. (reviews of topical problems)

  16. Comments on Graviton Propagation in Light of GW150914

    CERN Document Server

    Ellis, John; Nanopoulos, Dimitri V.

    2016-01-01

    The observation of gravitational waves from the Laser Interferometer Gravitational-Wave Observatory (LIGO) event GW150914 may be used to constrain the possibility of Lorentz violation in graviton propagation, and the observation by the Fermi Gamma-Ray Burst Monitor of a transient source in apparent coincidence may be used to constrain the difference between the velocities of light and gravitational waves: $c_g - c_\\gamma < 10^{-17}$.

  17. Efficient propagation of TM polarized light in photonic crystal components exhibiting band gaps for TE polarized light

    DEFF Research Database (Denmark)

    Borel, Peter Ingo; Frandsen, Lars Hagedorn; Thorhauge, Morten

    2003-01-01

    We have investigated the properties of TM polarized light in planar photonic crystal waveguide structures, which exhibit photonic band gaps for TE polarized light. Straight and bent photonic crystal waveguides and couplers have been fabricated in silicon-on-insulator material and modelled using a 3......D finite-difference-time-domain method. The simulated spectra are in excellent agreement with the experimental results, which show a propagation loss as low as 2.5±4 dB/mm around 1525 nm and bend losses at 2.9±0.2 dB for TM polarized light. We demonstrate a high coupling for TM polarized light...

  18. Hybrid simplified spherical harmonics with diffusion equation for light propagation in tissues

    International Nuclear Information System (INIS)

    Chen, Xueli; Sun, Fangfang; Yang, Defu; Ren, Shenghan; Liang, Jimin; Zhang, Qian

    2015-01-01

    Aiming at the limitations of the simplified spherical harmonics approximation (SP N ) and diffusion equation (DE) in describing the light propagation in tissues, a hybrid simplified spherical harmonics with diffusion equation (HSDE) based diffuse light transport model is proposed. In the HSDE model, the living body is first segmented into several major organs, and then the organs are divided into high scattering tissues and other tissues. DE and SP N are employed to describe the light propagation in these two kinds of tissues respectively, which are finally coupled using the established boundary coupling condition. The HSDE model makes full use of the advantages of SP N and DE, and abandons their disadvantages, so that it can provide a perfect balance between accuracy and computation time. Using the finite element method, the HSDE is solved for light flux density map on body surface. The accuracy and efficiency of the HSDE are validated with both regular geometries and digital mouse model based simulations. Corresponding results reveal that a comparable accuracy and much less computation time are achieved compared with the SP N model as well as a much better accuracy compared with the DE one. (paper)

  19. Hybrid simplified spherical harmonics with diffusion equation for light propagation in tissues.

    Science.gov (United States)

    Chen, Xueli; Sun, Fangfang; Yang, Defu; Ren, Shenghan; Zhang, Qian; Liang, Jimin

    2015-08-21

    Aiming at the limitations of the simplified spherical harmonics approximation (SPN) and diffusion equation (DE) in describing the light propagation in tissues, a hybrid simplified spherical harmonics with diffusion equation (HSDE) based diffuse light transport model is proposed. In the HSDE model, the living body is first segmented into several major organs, and then the organs are divided into high scattering tissues and other tissues. DE and SPN are employed to describe the light propagation in these two kinds of tissues respectively, which are finally coupled using the established boundary coupling condition. The HSDE model makes full use of the advantages of SPN and DE, and abandons their disadvantages, so that it can provide a perfect balance between accuracy and computation time. Using the finite element method, the HSDE is solved for light flux density map on body surface. The accuracy and efficiency of the HSDE are validated with both regular geometries and digital mouse model based simulations. Corresponding results reveal that a comparable accuracy and much less computation time are achieved compared with the SPN model as well as a much better accuracy compared with the DE one.

  20. Some properties of light propagation in relativity

    International Nuclear Information System (INIS)

    Bazanski, Stanislaw L.

    1998-01-01

    An outline of a formalism is proposed that describes relativistic effects associated with the propagation of light rays which after being initially split start to reconverge and intersect each other again. Beside a general geometric description that uses the approach of geometric optics, it has been shown how to compute both the difference of the proper times of arrivals of the two light beams to a measuring apparatus, as well as the frequency shifts of each of the beams taken separately. The formalism used here is applicable to both the special and the general theory of relativity, and it can be used equally well either when the light split is produced by a man-made optical device or when it is caused by the gravity field itself. The geometric description used in the formalism is independent of the physical origin of the frequency shift; of whether it is a Doppler, gravitational or cosmological frequency shift effect. Two simple examples of the application of the formalism have been worked out, which illustrate its results for families of inertial and noninertial observers respectively. Furthermore, a short description of a continuous version of the formalism has been presented in the last section of the article

  1. Controlling emission and propagation of light with photonic band gap crystals

    NARCIS (Netherlands)

    Yeganegi Dastgerdi, Elahe

    2014-01-01

    In certain three-dimensional crystals, a frequency range exist for all polarizations for which light is not allowed to propagate in any direction, called the 3D photonic band gap: a frequency range where the density of vacuum fluctuations vanishes in an ideal infinitely large and perfect system. The

  2. Moving picture recording and observation of femtosecond light pulse propagation using a rewritable holographic material

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiji; Takimoto, Tetsuya; Tosa, Kazuya; Kakue, Takashi [Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585 (Japan); Awatsuji, Yasuhiro, E-mail: awatsuji@kit.ac.jp [Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585 (Japan); Nishio, Kenzo [Advanced Technology Center, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585 (Japan); Ura, Shogo [Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585 (Japan); Kubota, Toshihiro [Kubota Holography Laboratory, Corporation, Nishihata 34-1-609, Ogura, Uji 611-0042 (Japan)

    2011-08-01

    We succeeded in recording and observing femtosecond light pulse propagation as a form of moving picture by means of light-in-flight recording by holography using a rewritable holographic material, for the first time. We used a femtosecond pulsed laser whose center wavelength and duration were 800 nm and {approx}120 fs, respectively. A photo-conductor plastic hologram was used as a rewritable holographic material. The femtosecond light pulse was collimated and obliquely incident to the diffuser plate. The behavior of the cross-section between the collimated femtosecond light pulse and the diffuser plate was recorded on the photo-conductor plastic hologram. We experimentally obtained a spatially and temporally continuous moving picture of the femtosecond light pulse propagation for 58.3 ps. Meanwhile, we also investigated the rewritable performance of the photo-conductor plastic hologram. As a result, we confirmed that ten-time rewriting was possible for a photo-conductor plastic hologram.

  3. Propagation of polarised light in bent hi-bi spun fibres

    Energy Technology Data Exchange (ETDEWEB)

    Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I; Gubin, V P [V.A.Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino branch, Fryazino, Moscow Region (Russian Federation)

    2015-11-30

    The evolution of polarisation states (PS's) of broadband light propagating through a bent optical fibre with a helical structure of its refractive index anisotropy (hi-bi spun fibre) has been studied theoretically and experimentally. It has been shown that there exists a coordinate system of PS's in which the differential Jones matrix can be replaced by a diagonal matrix, which allows the polarisation parameters of the output broadband light to be readily calculated with sufficient accuracy. We have derived a formula for evaluating the magneto-optical sensitivity of a bent spun fibre. An approach has been proposed for restoring the degree of polarisation of light in a bent hi-bi spun fibre and, as a consequence, the visibility (contrast) of the interferometer in a current sensor with a sensing element based on the fibre under consideration. (optical fibres)

  4. Light propagation in gas-filled kagomé hollow core photonic crystal fibres

    Science.gov (United States)

    Rodrigues, Sílvia M. G.; Facão, Margarida; Ferreira, Mário F. S.

    2018-04-01

    We study the propagation of light in kagomé hollow core photonic crystal fibres (HC-PCFs) filled with three different noble gases, namely, helium, xenon and argon. Various properties, including the guided modes, the group-velocity dispersion, and the nonlinear parameter were determined. The zero dispersion wavelength and the nonlinear parameter vary with the gas pressure which may be used to tune the generation of new frequencies using the same pump laser and the same fibre. In the case of the kagomé HC-PCF filled with xenon, the zero dispersion wavelength shifts from 693 to 1973 nm when the pressure is increased from 1 to 150bar, while the effective Kerr nonlinearity becomes comparable to that of silica. We have simulated the propagation of femtosecond pulses launched at 790 nm in order to study the generation of supercontinuum and UV light in kagomé HC-PCFs filled with the noble gases.

  5. Special Relativity Kinematics with Anisotropic Propagation of Light and Correspondence Principle

    Science.gov (United States)

    Burde, Georgy I.

    2016-12-01

    The purpose of the present paper is to develop kinematics of the special relativity with an anisotropy of the one-way speed of light. As distinct from a common approach, when the issue of anisotropy of the light propagation is placed into the context of conventionality of distant simultaneity, it is supposed that an anisotropy of the one-way speed of light is due to a real space anisotropy. In that situation, some assumptions used in developing the standard special relativity kinematics are not valid so that the "anisotropic special relativity" kinematics should be developed based on the first principles, without refereeing to the relations of the standard relativity theory. In particular, using condition of invariance of the interval between two events becomes unfounded in the presence of anisotropy of space since the standard proofs drawing the interval invariance from the invariance of equation of light propagation are not valid in that situation. Instead, the invariance of the equation of light propagation (with an anisotropy of the one-way speed of light incorporated), which is a physical law, should be taken as a first principle. A number of other physical requirements, associativity, reciprocity and so on are satisfied by the requirement that the transformations between the frames form a group. Finally, the correspondence principle is to be satisfied which implies that the coordinate transformations should turn into the Galilean transformations in the limit of small velocities. The above formulation based on the invariance and group property suggests applying the Lie group theory apparatus which includes the following steps: constructing determining equations for the infinitesimal group generators using the invariance condition; solving the determining equations; specifying the solutions using the correspondence principle; defining the finite transformations by solving the Lie equations; relating the group parameter to physical parameters. The

  6. Stirring of the propagation and the absorption of light in complex nanophotonic media

    NARCIS (Netherlands)

    Ojambati, Oluwafemi Stephen

    2016-01-01

    This thesis presents experimental investigations into the propagation of light inside both disordered and ordered complex photonic systems. The experimental results are interpreted using theoretical and numerical models. One of the main focus of this thesis is to determine experimentally and

  7. Toward real-time diffuse optical tomography: accelerating light propagation modeling employing parallel computing on GPU and CPU

    Science.gov (United States)

    Doulgerakis, Matthaios; Eggebrecht, Adam; Wojtkiewicz, Stanislaw; Culver, Joseph; Dehghani, Hamid

    2017-12-01

    Parameter recovery in diffuse optical tomography is a computationally expensive algorithm, especially when used for large and complex volumes, as in the case of human brain functional imaging. The modeling of light propagation, also known as the forward problem, is the computational bottleneck of the recovery algorithm, whereby the lack of a real-time solution is impeding practical and clinical applications. The objective of this work is the acceleration of the forward model, within a diffusion approximation-based finite-element modeling framework, employing parallelization to expedite the calculation of light propagation in realistic adult head models. The proposed methodology is applicable for modeling both continuous wave and frequency-domain systems with the results demonstrating a 10-fold speed increase when GPU architectures are available, while maintaining high accuracy. It is shown that, for a very high-resolution finite-element model of the adult human head with ˜600,000 nodes, consisting of heterogeneous layers, light propagation can be calculated at ˜0.25 s/excitation source.

  8. Electromagnetically induced transparency and nonlinear pulse propagation in a combined tripod and Λ atom-light coupling scheme

    International Nuclear Information System (INIS)

    Hamedi, H R; Ruseckas, J; Juzeliūnas, G

    2017-01-01

    We consider propagation of a probe pulse in an atomic medium characterized by a combined tripod and Lambda (Λ) atom-light coupling scheme. The scheme involves three atomic ground states coupled to two excited states by five light fields. It is demonstrated that dark states can be formed for such an atom-light coupling. This is essential for formation of the electromagnetically induced transparency (EIT) and slow light. In the limiting cases the scheme reduces to conventional Λ- or N -type atom-light couplings providing the EIT or absorption, respectively. Thus, the atomic system can experience a transition from the EIT to the absorption by changing the amplitudes or phases of control lasers. Subsequently the scheme is employed to analyze the nonlinear pulse propagation using the coupled Maxwell–Bloch equations. It is shown that a generation of stable slow light optical solitons is possible in such a five-level combined tripod and Λ atomic system. (paper)

  9. Physical behaviour of anthropogenic light propagation into the nocturnal environment.

    Science.gov (United States)

    Aubé, Martin

    2015-05-05

    Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  10. Simulating propagation of coherent light in random media using the Fredholm type integral equation

    Science.gov (United States)

    Kraszewski, Maciej; Pluciński, Jerzy

    2017-06-01

    Studying propagation of light in random scattering materials is important for both basic and applied research. Such studies often require usage of numerical method for simulating behavior of light beams in random media. However, if such simulations require consideration of coherence properties of light, they may become a complex numerical problems. There are well established methods for simulating multiple scattering of light (e.g. Radiative Transfer Theory and Monte Carlo methods) but they do not treat coherence properties of light directly. Some variations of these methods allows to predict behavior of coherent light but only for an averaged realization of the scattering medium. This limits their application in studying many physical phenomena connected to a specific distribution of scattering particles (e.g. laser speckle). In general, numerical simulation of coherent light propagation in a specific realization of random medium is a time- and memory-consuming problem. The goal of the presented research was to develop new efficient method for solving this problem. The method, presented in our earlier works, is based on solving the Fredholm type integral equation, which describes multiple light scattering process. This equation can be discretized and solved numerically using various algorithms e.g. by direct solving the corresponding linear equations system, as well as by using iterative or Monte Carlo solvers. Here we present recent development of this method including its comparison with well-known analytical results and a finite-difference type simulations. We also present extension of the method for problems of multiple scattering of a polarized light on large spherical particles that joins presented mathematical formalism with Mie theory.

  11. 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.

  12. Toward real-time diffuse optical tomography: accelerating light propagation modeling employing parallel computing on GPU and CPU.

    Science.gov (United States)

    Doulgerakis, Matthaios; Eggebrecht, Adam; Wojtkiewicz, Stanislaw; Culver, Joseph; Dehghani, Hamid

    2017-12-01

    Parameter recovery in diffuse optical tomography is a computationally expensive algorithm, especially when used for large and complex volumes, as in the case of human brain functional imaging. The modeling of light propagation, also known as the forward problem, is the computational bottleneck of the recovery algorithm, whereby the lack of a real-time solution is impeding practical and clinical applications. The objective of this work is the acceleration of the forward model, within a diffusion approximation-based finite-element modeling framework, employing parallelization to expedite the calculation of light propagation in realistic adult head models. The proposed methodology is applicable for modeling both continuous wave and frequency-domain systems with the results demonstrating a 10-fold speed increase when GPU architectures are available, while maintaining high accuracy. It is shown that, for a very high-resolution finite-element model of the adult human head with ∼600,000 nodes, consisting of heterogeneous layers, light propagation can be calculated at ∼0.25  s/excitation source. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  13. Understanding the Physical Optics Phenomena by Using a Digital Application for Light Propagation

    International Nuclear Information System (INIS)

    Sierra-Sosa, Daniel-Esteban; Angel-Toro, Luciano

    2011-01-01

    Understanding the light propagation on the basis of the Huygens-Fresnel principle stands for a fundamental factor for deeper comprehension of different physical optics related phenomena like diffraction, self-imaging, image formation, Fourier analysis and spatial filtering. This constitutes the physical approach of the Fourier optics whose principles and applications have been developed since the 1950's. Both for analytical and digital applications purposes, light propagation can be formulated in terms of the Fresnel Integral Transform. In this work, a digital optics application based on the implementation of the Discrete Fresnel Transform (DFT), and addressed to serve as a tool for applications in didactics of optics is presented. This tool allows, at a basic and intermediate learning level, exercising with the identification of basic phenomena, and observing changes associated with modifications of physical parameters. This is achieved by using a friendly graphic user interface (GUI). It also assists the user in the development of his capacity for abstracting and predicting the characteristics of more complicated phenomena. At an upper level of learning, the application could be used to favor a deeper comprehension of involved physics and models, and experimenting with new models and configurations. To achieve this, two characteristics of the didactic tool were taken into account when designing it. First, all physical operations, ranging from simple diffraction experiments to digital holography and interferometry, were developed on the basis of the more fundamental concept of light propagation. Second, the algorithm was conceived to be easily upgradable due its modular architecture based in MATLAB (registered) software environment. Typical results are presented and briefly discussed in connection with didactics of optics.

  14. Understanding the Physical Optics Phenomena by Using a Digital Application for Light Propagation

    Energy Technology Data Exchange (ETDEWEB)

    Sierra-Sosa, Daniel-Esteban; Angel-Toro, Luciano, E-mail: dsierras@eafit.edu.co, E-mail: langel@eafit.edu.co [Grupo de Optica Aplicada, Universidad EAFIT, 1 Medellin (Colombia)

    2011-01-01

    Understanding the light propagation on the basis of the Huygens-Fresnel principle stands for a fundamental factor for deeper comprehension of different physical optics related phenomena like diffraction, self-imaging, image formation, Fourier analysis and spatial filtering. This constitutes the physical approach of the Fourier optics whose principles and applications have been developed since the 1950's. Both for analytical and digital applications purposes, light propagation can be formulated in terms of the Fresnel Integral Transform. In this work, a digital optics application based on the implementation of the Discrete Fresnel Transform (DFT), and addressed to serve as a tool for applications in didactics of optics is presented. This tool allows, at a basic and intermediate learning level, exercising with the identification of basic phenomena, and observing changes associated with modifications of physical parameters. This is achieved by using a friendly graphic user interface (GUI). It also assists the user in the development of his capacity for abstracting and predicting the characteristics of more complicated phenomena. At an upper level of learning, the application could be used to favor a deeper comprehension of involved physics and models, and experimenting with new models and configurations. To achieve this, two characteristics of the didactic tool were taken into account when designing it. First, all physical operations, ranging from simple diffraction experiments to digital holography and interferometry, were developed on the basis of the more fundamental concept of light propagation. Second, the algorithm was conceived to be easily upgradable due its modular architecture based in MATLAB (registered) software environment. Typical results are presented and briefly discussed in connection with didactics of optics.

  15. Understanding the Physical Optics Phenomena by Using a Digital Application for Light Propagation

    Science.gov (United States)

    Sierra-Sosa, Daniel-Esteban; Ángel-Toro, Luciano

    2011-01-01

    Understanding the light propagation on the basis of the Huygens-Fresnel principle stands for a fundamental factor for deeper comprehension of different physical optics related phenomena like diffraction, self-imaging, image formation, Fourier analysis and spatial filtering. This constitutes the physical approach of the Fourier optics whose principles and applications have been developed since the 1950's. Both for analytical and digital applications purposes, light propagation can be formulated in terms of the Fresnel Integral Transform. In this work, a digital optics application based on the implementation of the Discrete Fresnel Transform (DFT), and addressed to serve as a tool for applications in didactics of optics is presented. This tool allows, at a basic and intermediate learning level, exercising with the identification of basic phenomena, and observing changes associated with modifications of physical parameters. This is achieved by using a friendly graphic user interface (GUI). It also assists the user in the development of his capacity for abstracting and predicting the characteristics of more complicated phenomena. At an upper level of learning, the application could be used to favor a deeper comprehension of involved physics and models, and experimenting with new models and configurations. To achieve this, two characteristics of the didactic tool were taken into account when designing it. First, all physical operations, ranging from simple diffraction experiments to digital holography and interferometry, were developed on the basis of the more fundamental concept of light propagation. Second, the algorithm was conceived to be easily upgradable due its modular architecture based in MATLAB® software environment. Typical results are presented and briefly discussed in connection with didactics of optics.

  16. Visualization of light propagation in visible Chinese human head for functional near-infrared spectroscopy

    Science.gov (United States)

    Li, Ting; Gong, Hui; Luo, Qingming

    2011-04-01

    Using the visible Chinese human data set, which faithfully represents human anatomy, we visualize the light propagation in the head in detail based on Monte Carlo simulation. The simulation is verified to agree with published experimental results in terms of a differential path-length factor. The spatial sensitivity profile turns out to seem like a fat tropical fish with strong distortion along the folding cerebral surface. The sensitive brain region covers the gray matter and extends to the superficial white matter, leading to a large penetration depth (>3 cm). Finally, the optimal source-detector separation is suggested to be narrowed down to 3-3.5 cm, while the sensitivity of the detected signal to brain activation reaches the peak of 8%. These results indicate that the cerebral cortex folding geometry actually has substantial effects on light propagation, which should be necessarily considered for applications of functional near-infrared spectroscopy.

  17. Influence investigation of a void region on modeling light propagation in a heterogeneous medium.

    Science.gov (United States)

    Yang, Defu; Chen, Xueli; Ren, Shenghan; Qu, Xiaochao; Tian, Jie; Liang, Jimin

    2013-01-20

    A void region exists in some biological tissues, and previous studies have shown that inaccurate images would be obtained if it were not processed. A hybrid radiosity-diffusion method (HRDM) that couples the radiosity theory and the diffusion equation has been proposed to deal with the void problem and has been well demonstrated in two-dimensional and three-dimensional (3D) simple models. However, the extent of the impact of the void region on the accuracy of modeling light propagation has not been investigated. In this paper, we first implemented and verified the HRDM in 3D models, including both the regular geometries and a digital mouse model, and then investigated the influences of the void region on modeling light propagation in a heterogeneous medium. Our investigation results show that the influence of the region can be neglected when the size of the void is less than a certain range, and other cases must be taken into account.

  18. Theoretical and experimental investigation of near-infrared light propagation in a model of the adult head.

    Science.gov (United States)

    Okada, E; Firbank, M; Schweiger, M; Arridge, S R; Cope, M; Delpy, D T

    1997-01-01

    Near-infrared light propagation in various models of the adult head is analyzed by both time-of-flight measurements and mathematical prediction. The models consist of three- or four-layered slabs, the latter incorporating a clear cerebrospinal fluid (CSF) layer. The most sophisticated model also incorporates slots that imitate sulci on the brain surface. For each model, the experimentally measured mean optical path length as a function of source-detector spacing agrees well with predictions from either a Monte Carlo model or a finite-element method based on diffusion theory or a hybrid radiosity-diffusion theory. Light propagation in the adult head is shown to be highly affected by the presence of the clear CSF layer, and both the optical path length and the spatial sensitivity profile of the models with a CSF layer are quite different from those without the CSF layer. However, the geometry of the sulci and the boundary between the gray and the white matter have little effect on the detected light distribution.

  19. Near-field imaging of light propagation in photonic crystal waveguides: Explicit role of Bloch harmonics

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Volkov, V.S.; Søndergaard, Thomas

    2002-01-01

    We employ a collection scanning near-field optical microscope (SNOM) to image the propagation of light at telecommunication wavelengths along straight and bent regions of silicon-on-insulator photonic crystal waveguides (PCWs) formed by removing a single row of holes in the triangular 410-nm...... the interference between a quasihomogeneous background field and Bloch harmonics of the PCW mode, we account for spatial frequency spectra of the intensity variations and determine the propagation constant of the PCW mode at 1520 nm. The possibilities and limitations of SNOM imaging for the characterization...

  20. Linear and nonlinear light propagations in a Doppler-broadened medium via electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Li Liang; Huang Guoxiang

    2010-01-01

    We present a systematic theoretical study to deal with linear and nonlinear light propagations in a Doppler-broadened three-level Λ system via electromagnetically induced transparency (EIT), with incoherent population exchange between two lower energy levels taken into account. Through a careful analysis of base state and linear excitation, we show that the EIT condition of the system is given by |Ω c | 2 γ 31 >>2γ 21 Δω D 2 , where Ω c is half the Rabi frequency of the control field, Δω D is the Doppler width, and γ jl is the decay rate of the coherence between states |j> and |l>. Under this condition, the effect of incoherent population exchange is insignificant, while dephasing dominates the decoherence of the system. This condition also ensures the validity of the weak nonlinear perturbation theory used in this work for solving the Maxwell-Bloch equations with inhomogeneous broadening. We then investigate the nonlinear propagation of the probe field and show that it is possible to form temporal optical solitons in the Doppler-broadened medium. Such solitons have ultraslow propagating velocity and can be generated in very low light power. The possibility of realizing (1+1)-dimensional and (2+1)-dimensional spatial optical solitons in the adiabatic regime of the system is also discussed.

  1. On the propagation and the twist of Gaussian light in first-order optical systems

    NARCIS (Netherlands)

    Bastiaans, M.J.; Nijhawan, O.P.; Gupta, A.K.; Musla, A.K.; Singh, Kehar

    1998-01-01

    A measure for the twist of Gaussian light is expressed in terms of the second-order moments of the Wigner distribution function. The propagation law for these moments through first-order optical systems is used to express the twist in the output plane in terms of moments in the input plane, and vice

  2. 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

  3. In vitro propagation of the Garden Heliotrope, Valeriana officinalis L.: influence of pre-chilling and light on seed germination.

    Science.gov (United States)

    Bhat, B; Sharma, V D

    2015-03-01

    Valeriana officinalis is an important medicinal herb commonly found in Kashmir valley. This study forms an important preliminary step for in-vitro micro propagation of V. officinalis from breaking the seed dormancy, inducing rapid seed germination and its subsequent micro propagation. We investigated the influence of pretreatment of V. officinalis seeds with reduced temperature and light on seed germination and in-vitro propagation. Culture of explants from cultivated seeds have demonstrated its potential for in vitro propagation and plantlet regeneration. Individual as well as combinations of treatments such as temperature and light availability influenced the germination of seeds variedly. Unchilled seeds of V. officinalis were given dip in GA3 (200 ppm) for 24, 48 and 120 h. Seeds treated with GA3 for 24 h and kept in darkness showed the best results, i.e. 48%. Seeds pretreated with GA3 for 120 h and incubated in dark showed 40% germination. Pre-chilling up to 72 h and kept in light showed maximum germination of 60% followed by 40% kept in darkness. Pre-chilling for 48 h resulted in 40 and 25% seed germination in light and darkness, respectively. GA3 pre-treatment for 72 h and 24 h pre chilling were most effective in inducing seed germination. Maximum shoot response was obtained on MS enriched with BAP (1 mg/L) + IAA (0.1 mg/L) combinations using shoot tips as explants. Multiple shoot regeneration from shoot apices was recorded on BAP (1 mg/L) and BAP (1 mg/L) + IAA (0.1 mg/L).

  4. Environmental and health aspects of lighting: Mercury

    Energy Technology Data Exchange (ETDEWEB)

    Clear, R.; Berman, S.

    1993-07-01

    Most discharge lamps, including fluorescent lamps, metal halide lamps, and high pressure sodium lamps, contain Mercury, a toxic chemical. Lighting professionals need to be able to respond to questions about the direct hazards of Mercury from accidentally breaking lamps, and the potential environmental hazards of lamp operation and disposal. We calculated the exposures that could occur from an accidental breakage of lamps. Acute poisoning appears almost impossible. Under some circumstances a sealed environment, such as a space station, could be contaminated enough to make it unhealthy for long-term occupation. Mercury becomes a potential environmental hazard after it becomes methylated. Mercury is methylated in aquatic environments, where it may accumulate in fish, eventually rendering them toxic to people and other animals. Lighting causes Mercury to enter the environment directly from lamp disposal, and indirectly from power plant emissions. The environmental tradeoffs between incandescent and discharge lamps depend upon the amounts released by these two sources, their local concentrations, and their probabilities of being methylated. Indirect environmental effects of lighting also include the release of other heavy metals (Cadmium, Lead and Arsenic), and other air pollutants and carbon dioxide that are emitted by fossil fuel power plants. For a given light output, the level of power plant emissions depends upon the efficacy of the light source, and is thus much larger for incandescent lamps than for fluorescent or discharge lamps. As disposal and control technologies change the relative direct and indirect emissions from discharge and incandescent lamps will change.

  5. Three-dimensional microscale modelling of CO2 transport and light propagation in tomato leaves enlightens photosynthesis

    NARCIS (Netherlands)

    Ho, Q.T.; Berghuijs, H.N.C.; Watté, R.; Verboven, P.; Herremans, E.; Yin, X.; Retta, M.A.; Aernouts, B.; Saeys, W.; Helfen, L.; Farquhar, G.D.; Struik, P.C.; Nicolai, B.

    2016-01-01

    We present a combined three-dimensional (3-D) model of light propagation, CO2 diffusion and photosynthesis in tomato (Solanum lycopersicum L.) leaves. The model incorporates a geometrical representation of the actual leaf microstructure that we obtained with synchrotron radiation X-ray laminography,

  6. Propagation of light in the lithium niobate crystal along directions close to an optical axis

    International Nuclear Information System (INIS)

    Volkov, V.V.; Egorova, G.A.; Lonskij, Eh.S.; Potapov, E.V.; Rakov, A.V.

    1978-01-01

    Theoretical and experimental results are given of studying some characteristics of electrooptical modulator from lithium niobate when propagating in it linear-polarized light in directions close to the optical axis, the electric field being applied along the X axis. It has been shown that an increase in an angle of deviation from the optical axis of a light beam passing in the crystal changes the value of the controlling voltage. This is accompanied by the rotation of the polarization plane and the change in the intensity of the light being passed. The methods have been proposed of increasing the modulator aperture, determining the main refraction indices and some electrooptical coefficients fo the lithium niobate crystal

  7. Environmental Science Program at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter; A; Anastasio, Cort; Dodge, Cleveland; Fendorf, Scott; Francis, A.J.; Hubbard, Susan; Shuh, David; Tomutsa, Liviu; Tufano, Kate; Tyliszczak, Tolek; Werner, Michelle; Williams, Ken

    2006-04-05

    The Advanced Light Source (ALS) has a variety of capabilities that are applicable to very different types of environmental systems. Shown are the basic descriptions of four of the approximately 35 beam lines at the ALS. The complimentary capabilities of these four beam lines allow for investigations that range from a spatial scale of a few nanometers to several millimeters. The Environmental Science Program at the Advanced Light Source seeks to promote and assist environmental research, particularly on the four beam lines described in this report. Several short examples of the types of research conducted on these beam lines are also described.

  8. Light propagation in 2PN approximation in the field of one moving monopole I. Initial value problem

    Science.gov (United States)

    Zschocke, Sven

    2018-03-01

    In this investigation the light propagation in the gravitational field of one arbitrarily moving body with monopole structure is considered in the second post-Newtonian approximation. It is found that the light trajectory depends on the acceleration of the body. Some of these acceleration terms are important in order to get well-defined logarithmic functions with dimensionless arguments, while all the other acceleration terms are negligible on the pico-second level of accuracy in time-delay measurements. The expressions of the observables total light deflection and time delay are determined.

  9. Economic and Environmental Assessment of Seed and Rhizome Propagated Miscanthus in the UK

    Directory of Open Access Journals (Sweden)

    Astley Hastings

    2017-06-01

    Full Text Available Growth in planted areas of Miscanthus for biomass in Europe has stagnated since 2010 due to technical challenges, economic barriers and environmental concerns. These limitations need to be overcome before biomass production from Miscanthus can expand to several million hectares. In this paper, we consider the economic and environmental effects of introducing seed based hybrids as an alternative to clonal M. x giganteus (Mxg. The impact of seed based propagation and novel agronomy was compared with current Mxg cultivation and used in 10 commercially relevant, field scale experiments planted between 2012 and 2014 in the United Kingdom, Germany, and Ukraine. Economic and greenhouse gas (GHG emissions costs were quantified for the following production chain: propagation, establishment, harvest, transportation, storage, and fuel preparation (excluding soil carbon changes. The production and utilization efficiency of seed and rhizome propagation were compared. Results show that new hybrid seed propagation significantly reduces establishment cost to below £900 ha-1. Calculated GHG emission costs for the seeds established via plugs, though relatively small, was higher than rhizomes because fossil fuels were assumed to heat glasshouses for raising seedling plugs (5.3 and 1.5 kg CO2 eq. C Mg [dry matter (DM]-1, respectively. Plastic mulch film reduced establishment time, improving crop economics. The breakeven yield was calculated to be 6 Mg DM ha-1 y-1, which is about half average United Kingdom yield for Mxg; with newer seeded hybrids reaching 16 Mg DM ha-1 in second year United Kingdom trials. These combined improvements will significantly increase crop profitability. The trade-offs between costs of production for the preparation of different feedstock formats show that bales are the best option for direct firing with the lowest transport costs (£0.04 Mg-1 km-1 and easy on-farm storage. However, if pelleted fuel is required then chip harvesting is

  10. Finite-Difference Time-Domain Simulation of Light Propagation in 2D Periodic and Quasi-Periodic Photonic Structures

    Directory of Open Access Journals (Sweden)

    N. Dadashzadeh

    2013-09-01

    Full Text Available Ultra-short pulse is a promising technology for achieving ultra-high data rate transmission which is required to follow the increased demand of data transport over an optical communication system. Therefore, the propagation of such type of pulses and the effects that it may suffer during its transmission through an optical waveguide has received a great deal of attention in the recent years. We provide an overview of recent theoretical developments in a numerical modeling of Maxwell's equations to analyze the propagation of short laser pulses in photonic structures. The process of short light pulse propagation through 2D periodic and quasi-periodic photonic structures is simulated based on Finite-Difference Time-Domain calculations of Maxwell’s equations.

  11. A modal approach to light emission and propagation in coupled cavity waveguide systems

    DEFF Research Database (Denmark)

    Gregersen, Niels; Kristensen, P. T.; de Lasson, Jakob Rosenkrantz

    2016-01-01

    We theoretically investigate systems of optical cavities coupled to waveguides,which necessitates the introduction of non-trivial radiation conditions and normalization procedures. In return, the approach provides simple and accurate modeling of Green functions,Purcell factors and perturbation...... corrections, as well as an alternative approach to the so-calledcoupled mode theory. In combination, these results may form part of the foundations for highly efficient, yet physically transparent models of light emission and propagation in both classical and quantum integrated photonic circuits....

  12. On the mean profiles of radio pulsars - II. Reconstruction of complex pulsar light curves and other new propagation effects

    Science.gov (United States)

    Hakobyan, H. L.; Beskin, V. S.; Philippov, A. A.

    2017-08-01

    Our previous paper outlined the general aspects of the theory of radio light curve and polarization formation for pulsars. We predicted the one-to-one correspondence between the tilt of the linear polarization position angle of the the circular polarization. However, some of the radio pulsars indicate a clear deviation from that correlation. In this paper, we apply the theory of the radio wave propagation in the pulsar magnetosphere for the analysis of individual effects leading to these deviations. We show that within our theory the circular polarization of a given mode can switch its sign, without the need to introduce a new radiation mode or other effects. Moreover, we show that the generation of different emission modes on different altitudes can explain pulsars, that presumably have the X-O-X light-curve pattern, different from what we predict. General properties of radio emission within our propagation theory are also discussed. In particular, we calculate the intensity patterns for different radiation altitudes and present light curves for different observer viewing angles. In this context we also study the light curves and polarization profiles for pulsars with interpulses. Further, we explain the characteristic width of the position angle curves by introducing the concept of a wide emitting region. Another important feature of radio polarization profiles is the shift of the position angle from the centre, which in some cases demonstrates a weak dependence on the observation frequency. Here we demonstrate that propagation effects do not necessarily imply a significant frequency-dependent change of the position angle curve.

  13. Propagation and scattering of optical light beams in free space, in atmosphere and in biological media

    Science.gov (United States)

    Sahin, Serkan

    With their first production implemented around 1960's, lasers have afterwards proven to be excellent light sources in building the technology. Subsequently, it has been shown that the extraordinary properties of lasers are related to their coherence properties. Recent developments in optics make it possible to synthesize partially coherent light beams from fully coherent ones. In the last several decades it was seen that using partially coherent light sources may be advantageous, in the areas such as laser surface processing, fiber and free-space optical communications, and medical diagnostics. In this thesis, I study extensively the generation, the propagation in different media, and the scattering of partially coherent light beams with respect to their spectral polarization and coherence states. For instance, I analyze the evolution of recently introduced degree of cross-polarization of light fields in free space; then develop a novel partially coherent light source which acquires and keeps a flat intensity profile around the axis at any distance in the far field; and investigate the interaction of electromagnetic random light with the human eye lens. A part of the thesis treats the effect of atmospheric turbulence on random light beams. Due to random variations in the refractive index, atmospheric turbulence modulates all physical and statistical properties of propagating beams. I have explored the possibility of employing the polarimetric domain of the beam for scintillation reduction, which positively affects the performance of free-space communication systems. I also discuss novel techniques for the sensing of rough targets in the turbulent atmosphere by polarization and coherence properties of light. The other contribution to the thesis is the investigation of light scattering from deterministic or random collections of particles, within the validity of first Born approximation. In the case of a random collection, I introduce and model the new quantity

  14. Search for Anisotropic Light Propagation as a Function of Laser Beam Alignment Relative to the Earth's Velocity Vector

    Directory of Open Access Journals (Sweden)

    Navia C. E.

    2007-01-01

    Full Text Available A laser diffraction experiment was conducted to study light propagation in air. The experiment is easy to reproduce and it is based on simple optical principles. Two optical sensors (segmented photo-diodes are used for measuring the position of diffracted light spots with a precision better than 0.1 μ m. The goal is to look for signals of anisotropic light propagation as function of the laser beam alignment to the Earth’s motion (solar barycenter motion obtained by COBE. Two raster search techniques have been used. First, a laser beam fixed in the laboratory frame scans in space due to Earth’s rotation. Second, a laser beam mounted on a turntable system scans actively in space by turning the table. The results obtained with both methods show that the course of light rays are affected by the motion of the Earth, and a predominant first order quantity with a Δ c/c = − β (1 + 2 a cos θ signature with ˉ a = − 0.393 ± 0.032 describes well the experimental results. This result differs in amount of 21% from the Special Relativity Theory prediction and that supplies the value of a = − 1 2 (isotropy.

  15. Light propagation through black-hole lattices

    Energy Technology Data Exchange (ETDEWEB)

    Bentivegna, Eloisa [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Korzyński, Mikołaj [Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Hinder, Ian; Gerlicher, Daniel, E-mail: eloisa.bentivegna@unict.it, E-mail: korzynski@cft.edu.pl, E-mail: ian.hinder@aei.mpg.de, E-mail: daniel.gerlicher@tum.de [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, D-14476 Golm (Germany)

    2017-03-01

    The apparent properties of distant objects encode information about the way the light they emit propagates to an observer, and therefore about the curvature of the underlying spacetime. Measuring the relationship between the redshift z and the luminosity distance D {sub L} of a standard candle, for example, yields information on the Universe's matter content. In practice, however, in order to decode this information the observer needs to make an assumption about the functional form of the D {sub L}( z ) relation; in other words, a cosmological model needs to be assumed. In this work, we use numerical-relativity simulations, equipped with a new ray-tracing module, to numerically obtain this relation for a few black-hole-lattice cosmologies and compare it to the well-known Friedmann-Lema(ȋtre-Robertson-Walker case, as well as to other relevant cosmologies and to the Empty-Beam Approximation. We find that the latter provides the best estimate of the luminosity distance and formulate a simple argument to account for this agreement. We also find that a Friedmann-Lema(ȋtre-Robertson-Walker model can reproduce this observable exactly, as long as a time-dependent cosmological constant is included in the fit. Finally, the dependence of these results on the lattice mass-to-spacing ratio μ is discussed: we discover that, unlike the expansion rate, the D {sub L}( z ) relation in a black-hole lattice does not tend to that measured in the corresponding continuum spacetime as 0μ → .

  16. Two spatial light modulator system for laboratory simulation of random beam propagation in random media.

    Science.gov (United States)

    Wang, Fei; Toselli, Italo; Korotkova, Olga

    2016-02-10

    An optical system consisting of a laser source and two independent consecutive phase-only spatial light modulators (SLMs) is shown to accurately simulate a generated random beam (first SLM) after interaction with a stationary random medium (second SLM). To illustrate the range of possibilities, a recently introduced class of random optical frames is examined on propagation in free space and several weak turbulent channels with Kolmogorov and non-Kolmogorov statistics.

  17. Quantum description of light propagation in generalized media

    International Nuclear Information System (INIS)

    Häyrynen, Teppo; Oksanen, Jani

    2016-01-01

    Linear quantum input–output relation based models are widely applied to describe the light propagation in a lossy medium. The details of the interaction and the associated added noise depend on whether the device is configured to operate as an amplifier or an attenuator. Using the traveling wave (TW) approach, we generalize the linear material model to simultaneously account for both the emission and absorption processes and to have point-wise defined noise field statistics and intensity dependent interaction strengths. Thus, our approach describes the quantum input–output relations of linear media with net attenuation, amplification or transparency without pre-selection of the operation point. The TW approach is then applied to investigate materials at thermal equilibrium, inverted materials, the transparency limit where losses are compensated, and the saturating amplifiers. We also apply the approach to investigate media in nonuniform states which can be e.g. consequences of a temperature gradient over the medium or a position dependent inversion of the amplifier. Furthermore, by using the generalized model we investigate devices with intensity dependent interactions and show how an initial thermal field transforms to a field having coherent statistics due to gain saturation. (paper)

  18. Fatigue and environmentally assisted cracking in light water reactors

    International Nuclear Information System (INIS)

    Kassner, T.F.; Ruther, W.E.; Chung, H.M.; Hicks, P.D.; Hins, A.G.; Park, J.Y.; Shack, W.J.

    1991-12-01

    Fatigue and environmentally assisted cracking of piping, pressure vessels, and core components in light water reactors (LWRs) are important concerns as extended reactor lifetimes are envisaged. The degradation processes include intergranular stress corrosion cracking (IGSCC) of austenitic stainless steel (SS) piping in boiling water reactors (BWRs), and propagation of fatigue or SCC cracks (which initiate in sensitized SS cladding) into low-alloy ferritic steels in BWR pressure vessels. Similar cracking has also occurred in upper shell-to-transition cone girth welds in pressurized water reactor (PWR) steam generator vessels. Another concern is failure of reactor-core internal components after accumulation of relatively high fluence, which has occurred in both BWRs and PWRs. Research during the past year focused on (1) fatigue and SCC of ferritic steels used in piping and in steam generator and reactor pressure vessels, (2) role of chromate and sulfate in simulated BWR water in SCC of sensitized Type 304 SS, and (3) irradiation-assisted SCC in high- and commercial-purity Type 304 SS specimens from control-blade absorber tubes used in two operating BWRs. Failure after accumulation of relatively high fluence has been attributed to radiation-induced segregation (RIS) of elements such as Si, P, Ni, and Cr. This document provides a summary of research progress in these areas

  19. Environmentally Benign Technology for Efficient Warm-White Light Emission

    Science.gov (United States)

    Shen, Pin-Chun; Lin, Ming-Shiun; Lin, Ching-Fuh

    2014-06-01

    Nowadays efficient down conversion for white light emission is mainly based on rare-earth doped phosphors or cadmium-containing quantum dots. Although they exhibit high luminescence efficiency, the rare-earth mining and cadmium pollution have so far led to extremely high environmental cost, which conflicts the original purpose of pursuing efficient lighting. Here, we explore a new strategy to achieve efficient luminescence conversion based on polymer-decorated nanoparticles. The ZnO and Mn2+ doped ZnS nanoparticles are encapsulated by poly(9,9-di-n- hexylfluorenyl-2,7-diyl). The resultant core-shell nanocomposites then encompass three UV-to-visible luminescence conversion routes for photon emissions at blue, green, and orange colors, respectively. As a result, the color temperature is widely tunable (2100 K ~ 6000 K), so candle light or pure white light can be generated. The quantum yield up to 91% could also be achieved. Such rare-earth-element free nanocomposites give the bright perspectives for energy-saving, healthy, and environmentally benign lighting.

  20. Raman Monte Carlo simulation for light propagation for tissue with embedded objects

    Science.gov (United States)

    Periyasamy, Vijitha; Jaafar, Humaira Bte; Pramanik, Manojit

    2018-02-01

    Monte Carlo (MC) stimulation is one of the prominent simulation technique and is rapidly becoming the model of choice to study light-tissue interaction. Monte Carlo simulation for light transport in multi-layered tissue (MCML) is adapted and modelled with different geometry by integrating embedded objects of various shapes (i.e., sphere, cylinder, cuboid and ellipsoid) into the multi-layered structure. These geometries would be useful in providing a realistic tissue structure such as modelling for lymph nodes, tumors, blood vessels, head and other simulation medium. MC simulations were performed on various geometric medium. Simulation of MCML with embedded object (MCML-EO) was improvised for propagation of the photon in the defined medium with Raman scattering. The location of Raman photon generation is recorded. Simulations were experimented on a modelled breast tissue with tumor (spherical and ellipsoidal) and blood vessels (cylindrical). Results were presented in both A-line and B-line scans for embedded objects to determine spatial location where Raman photons were generated. Studies were done for different Raman probabilities.

  1. General theory of light propagation and imaging through the atmosphere

    CERN Document Server

    McKechnie, T Stewart

    2016-01-01

    This book lays out a new, general theory of light propagation and imaging through Earth’s turbulent atmosphere. Current theory is based on the – now widely doubted – assumption of Kolmogorov turbulence. The new theory is based on a generalized atmosphere, the turbulence characteristics of which can be established, as needed, from readily measurable properties of point-object, or star, images. The pessimistic resolution predictions of Kolmogorov theory led to lax optical tolerance prescriptions for large ground-based astronomical telescopes which were widely adhered to in the 1970s and 1980s. Around 1990, however, it became clear that much better resolution was actually possible, and Kolmogorov tolerance prescriptions were promptly abandoned. Most large telescopes built before 1990 have had their optics upgraded (e.g., the UKIRT instrument) and now achieve, without adaptive optics (AO), almost an order of magnitude better resolution than before. As well as providing a more comprehensive and precise under...

  2. 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

  3. Application of polarization information to a light-controlling-light technique.

    Science.gov (United States)

    Liang, J C; Wang, H C

    2017-09-15

    Nonlinear effects of photo-induced waveguides based on isomerization photochemistry are investigated. It is found that polarization information of the controlling light can be used to control the propagation of the signal light in all-optical waveguides, and an accurate and convenient light-controlling-light scheme is proposed, that is, controlling propagation of the signal light by synergic use of the intensity information and polarization information of the controlling light. The polarization dependence of optical nonlinearity is expected to enrich the connotation of the optical nonlinear effects and has theoretical significance and practical value.

  4. An FDTD algorithm for simulating light propagation in anisotropic dynamic gain media

    KAUST Repository

    Al-Jabr, A. A.; San Roman Alerigi, Damian; Ooi, Boon S.; Alsunaidi, M. A.

    2014-01-01

    Simulating light propagation in anisotropic dynamic gain media such as semiconductors and solid-state lasers using the finite difference time-domain FDTD technique is a tedious process, as many variables need to be evaluated in the same instant of time. The algorithm has to take care of the laser dynamic gain, rate equations, anisotropy and dispersion. In this paper, to the best of our knowledge, we present the first algorithm that solves this problem. The algorithm is based on separating calculations into independent layers and hence solving each problem in a layer of calculations. The anisotropic gain medium is presented and tested using a one-dimensional set-up. The algorithm is then used for the analysis of a two-dimensional problem.

  5. An FDTD algorithm for simulating light propagation in anisotropic dynamic gain media

    KAUST Repository

    Al-Jabr, A. A.

    2014-05-02

    Simulating light propagation in anisotropic dynamic gain media such as semiconductors and solid-state lasers using the finite difference time-domain FDTD technique is a tedious process, as many variables need to be evaluated in the same instant of time. The algorithm has to take care of the laser dynamic gain, rate equations, anisotropy and dispersion. In this paper, to the best of our knowledge, we present the first algorithm that solves this problem. The algorithm is based on separating calculations into independent layers and hence solving each problem in a layer of calculations. The anisotropic gain medium is presented and tested using a one-dimensional set-up. The algorithm is then used for the analysis of a two-dimensional problem.

  6. 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

  7. Light pollution : A case study in framing an environmental problem

    NARCIS (Netherlands)

    Stone, T.W.

    2017-01-01

    Light pollution is a topic gaining importance and acceptance in environmental discourse. This concept provides a framework for categorizing the adverse effects of nighttime lighting, which advocacy groups and regulatory efforts are increasingly utilizing. However, the ethical significance of the

  8. Light propagation and emission in scattering media. Application to imaging of complex media

    International Nuclear Information System (INIS)

    Pierrat, Romain

    2007-01-01

    In this manuscript, we raise different aspects of the propagation and emission of electromagnetic waves in a scattering medium. In the first part, we show that the Radiative Transfer Equation (rte) is a very good tool to study light propagation in a complex medium. Thanks to this formalism, we study the evolution of the spatial coherence of the beam inside the medium, which is seen as a signature of the different transport regimes of photons (single scattering, multiple scattering, diffusive regime). Next, we derive rigorously the diffusion approximation by using a modal approach of the rte. In particular, we obtain that the diffusion coefficient is independent of the level of absorption in the dynamic regime while it depends on absorption in the case of the steady-state regime. Finally, we study the temporal fluctuations of the scattered intensity and show that the use of the rte allows to go beyond the diffusive regime described by the diffusing-waves spectroscopy theory (dws). Comparisons between numerical computations and experiments are realized in reflexion to underline the fundamental role of the anisotropy of the scattering, which is not described by the standard theory. The second part is dedicated to the study of light emission in complex media. First, we study the amplification of scattered light in a gain system called random laser and show that it exists a laser threshold in the incoherent feedback regime. This threshold is quantified by using a modal approach of the rte. Thanks to this formalism, we highlight the limitations of the diffusion approximation in such a system. Next, we study the modification of the fluorescent decay rate of a single molecule embedded in a complex medium. We derive a model allowing the replacement of the scattering medium by an homogeneous equivalent medium taking into account the multiple scattering and the interactions between scatterers. This model is validated by comparison with the value of the decay rate of the

  9. Average expansion rate and light propagation in a cosmological Tardis spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Lavinto, Mikko; Räsänen, Syksy [Department of Physics, University of Helsinki, and Helsinki Institute of Physics, P.O. Box 64, FIN-00014 University of Helsinki (Finland); Szybka, Sebastian J., E-mail: mikko.lavinto@helsinki.fi, E-mail: syksy.rasanen@iki.fi, E-mail: sebastian.szybka@uj.edu.pl [Astronomical Observatory, Jagellonian University, Orla 171, 30-244 Kraków (Poland)

    2013-12-01

    We construct the first exact statistically homogeneous and isotropic cosmological solution in which inhomogeneity has a significant effect on the expansion rate. The universe is modelled as a Swiss Cheese, with dust FRW background and inhomogeneous holes. We show that if the holes are described by the quasispherical Szekeres solution, their average expansion rate is close to the background under certain rather general conditions. We specialise to spherically symmetric holes and violate one of these conditions. As a result, the average expansion rate at late times grows relative to the background, \\ie backreaction is significant. The holes fit smoothly into the background, but are larger on the inside than a corresponding background domain: we call them Tardis regions. We study light propagation, find the effective equations of state and consider the relation of the spatially averaged expansion rate to the redshift and the angular diameter distance.

  10. Propagation of Gaussian Beams through Active GRIN Materials

    International Nuclear Information System (INIS)

    Gomez-Varela, A I; Flores-Arias, M T; Bao-Varela, C; Gomez-Reino, C; De la Fuente, X

    2011-01-01

    We discussed light propagation through an active GRIN material that exhibits loss or gain. Effects of gain or loss in GRIN materials can be phenomenologically taken into account by using a complex refractive index in the wave equation. This work examines the implication of using a complex refractive index on light propagation in an active GRIN material illuminated by a non-uniform monochromatic wave described by a Gaussian beam. We analyze how a Gaussian beam is propagated through the active material in order to characterize it by the beam parameters and the transverse irradiance distribution.

  11. Comparative evaluations of the Monte Carlo-based light propagation simulation packages for optical imaging

    Directory of Open Access Journals (Sweden)

    Lin Wang

    2018-01-01

    Full Text Available Monte Carlo simulation of light propagation in turbid medium has been studied for years. A number of software packages have been developed to handle with such issue. However, it is hard to compare these simulation packages, especially for tissues with complex heterogeneous structures. Here, we first designed a group of mesh datasets generated by Iso2Mesh software, and used them to cross-validate the accuracy and to evaluate the performance of four Monte Carlo-based simulation packages, including Monte Carlo model of steady-state light transport in multi-layered tissues (MCML, tetrahedron-based inhomogeneous Monte Carlo optical simulator (TIMOS, Molecular Optical Simulation Environment (MOSE, and Mesh-based Monte Carlo (MMC. The performance of each package was evaluated based on the designed mesh datasets. The merits and demerits of each package were also discussed. Comparative results showed that the TIMOS package provided the best performance, which proved to be a reliable, efficient, and stable MC simulation package for users.

  12. Continuous control of light group velocity from subluminal to superluminal propagation with a standing-wave coupling field in a Rb vapor cell

    International Nuclear Information System (INIS)

    Bae, In-Ho; Moon, Han Seb

    2011-01-01

    We present the continuous control of the light group velocity from subluminal to superluminal propagation with an on-resonant standing-wave coupling field in the 5S 1/2 -5P 1/2 transition of the Λ-type system of 87 Rb atoms. When a coupling field was changed from a traveling-wave to a standing-wave field by adjusting the power of a counterpropagating coupling field, the probe pulse propagation continuously transformed from subluminal propagation, due to electromagnetically induced transparency with the traveling-wave coupling field, to superluminal propagation, due to narrow enhanced absorption with the standing-wave coupling field. The group velocity of the probe pulse was measured to be approximately 0.004c to -0.002c as a function of the disparity between the powers of the copropagating and the counterpropagating coupling fields.

  13. Fast light in atomic media

    International Nuclear Information System (INIS)

    Akulshin, Alexander M; McLean, Russell J

    2010-01-01

    Atomic media have played a major role in studies of fast light. One of their attractive features is the ability to manipulate experimental parameters to control the dispersive properties that determine the group velocity of a propagating light pulse. We give an overview of the experimental methods, based on both linear and nonlinear atom–light interaction, that have produced superluminal propagation in atomic media, and discuss some of the significant theoretical contributions to the issues of pulse preservation and reconciling faster-than-light propagation and the principle of causality. The comparison of storage of light, enhanced Kerr nonlinearity and efficient wave mixing processes in slow and fast light atomic media illustrates their common and distinct features. (review article)

  14. Monte Carlo simulation of near-infrared light propagation in realistic adult head models with hair follicles

    Science.gov (United States)

    Pan, Boan; Fang, Xiang; Liu, Weichao; Li, Nanxi; Zhao, Ke; Li, Ting

    2018-02-01

    Near infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) has been used to measure brain activation, which are clinically important. Monte Carlo simulation has been applied to the near infrared light propagation model in biological tissue, and has the function of predicting diffusion and brain activation. However, previous studies have rarely considered hair and hair follicles as a contributing factor. Here, we attempt to use MCVM (Monte Carlo simulation based on 3D voxelized media) to examine light transmission, absorption, fluence, spatial sensitivity distribution (SSD) and brain activation judgement in the presence or absence of the hair follicles. The data in this study is a series of high-resolution cryosectional color photograph of a standing Chinse male adult. We found that the number of photons transmitted under the scalp decreases dramatically and the photons exported to detector is also decreasing, as the density of hair follicles increases. If there is no hair follicle, the above data increase and has the maximum value. Meanwhile, the light distribution and brain activation have a stable change along with the change of hair follicles density. The findings indicated hair follicles make influence of NIRS in light distribution and brain activation judgement.

  15. The Impact of Environmental Light Intensity on Experimental Tumor Growth.

    Science.gov (United States)

    Suckow, Mark A; Wolter, William R; Duffield, Giles E

    2017-09-01

    Cancer research requires for consistent models that minimize environmental variables. Within the typical laboratory animal housing facility, animals may be exposed to varying intensities of light as a result of cage type, cage position, light source, and other factors; however, studies evaluating the differential effect of light intensity during the light phase on tumor growth are lacking. The effect of cage face light intensity, as determined by cage rack position was evaluated with two tumor models using the C57Bl/6NHsd mouse and transplantable B16F10 melanoma cells or Lewis lung carcinoma (LLC) cells. Animals were housed in individually-ventilated cages placed at the top, middle, or bottom of the rack in a diagonal pattern so that the top cage was closest to the ceiling light source, and cage face light intensity was measured. Following a two-week acclimation period at the assigned cage position, animals were subcutaneously administered either 1.3×10 6 B16F10 melanoma cells or 2.5×10 5 Lewis lung carcinoma cells. Weights of excised tumors were measured following euthanasia 18 days (melanoma) or 21 days (LCC) after tumor cell administration. Cage face light intensity was significantly different depending on the location of the cage, with cages closest to the light source have the greatest intensity. Mean tumor weights were significantly less (plight intensity mice compared to high and low light intensity mice. The environmental light intensity to which experimental animals are exposed may vary markedly with cage location and can significantly influence experimental tumor growth, thus supporting the idea that light intensity should be controlled as an experimental variable for animals used in cancer research. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  16. Analogies between the Torque-Free Motion of a Rigid Body about a Fixed Point and Light Propagation in Anisotropic Media

    Science.gov (United States)

    Bellver-Cebreros, Consuelo; Rodriguez-Danta, Marcelo

    2009-01-01

    An apparently unnoticed analogy between the torque-free motion of a rotating rigid body about a fixed point and the propagation of light in anisotropic media is stated. First, a new plane construction for visualizing this torque-free motion is proposed. This method uses an intrinsic representation alternative to angular momentum and independent of…

  17. Slow light pulse propagation in dispersive media

    DEFF Research Database (Denmark)

    Nielsen, Torben Roland; Mørk, Jesper; Lavrinenko, Andrei

    2009-01-01

    broadening or break-up of the pulse may be observed. The transition from linear to nonlinear pulse propagation is quantified in terms of the spectral width of the pulse. To cite this article: T.R. Nielsen et al., C. R. Physique 10 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All...... rights reserved....

  18. WOW: light print, light propel, light point

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Bañas, Andrew Rafael; Aabo, Thomas

    2012-01-01

    anywhere in a sample at any orientation using real-time 3D optical micromanipulation with six degrees of freedom. One of the key aspects of our demonstrated WOWs is the change in direction of in-coupled light and the marked increase in numerical aperture of the out-coupled light. Hence, each light...... propelled WOW can tap from a relatively broad incident beam and generate a much more tightly confined light at its tip. The presentation contains both numerical simulations related to the propagation of light through a WOW and preliminary experimental demonstrations on our BioPhotonics Workstation...

  19. Subwavelength propagation and localization of light using surface ...

    Indian Academy of Sciences (India)

    2014-01-09

    Jan 9, 2014 ... methods to excite, propagate and detect SPPs and LSPs. 2. ... plasmonic imaging [12], back-focal plane imaging, plasmon leakage radiation ..... Chemically prepared silver nanowires were first diluted using milli-Q water.

  20. Effects of environmental lighting and tryptophan devoid diet on the rat vaginal cycle.

    Science.gov (United States)

    Giammanco, S; Ernandes, M; La Guardia, M

    1997-09-01

    Cerebral serotonin level influences luteinizing hormone release and, consequently, ovulation. The present study evaluated the effects of precooked maize meal (polenta), a diet almost devoid of tryptophan the serotonin precursor on the alterations of the estrus cycle as measured by vaginal smears analysis in Wistar rats. Several conditions of environmental lighting were used in order to modify ovarian cycle: 1) natural alternating light/dark cycle; 2) continuous darkness; 3) continuous light by sodium steams: 4) continuous light by fluorescent neon tubes. Rats bred in continuous lighting showed estrus-proestrus rate significantly greater than rats bred in normal lighting or in continuous darkness. The feeding with precooked maize meal suppressed persistent estrus in rats bred in continuous lighting, and significantly cut down the estrus-proestrus frequency in any condition of environmental lighting. Our results lead to hypothesize that polenta diet, for its low tryptophan content, cutting down both tryptophan plasma content and serotonin neuronal synthesis, promotes luteinizing hormone peak.

  1. Reverse Monte Carlo simulations of light pulse propagation in nonhomogeneous media

    International Nuclear Information System (INIS)

    Lu Xiaodong; Hsu Peifeng

    2005-01-01

    This paper presents a follow-up study of our previous work on the reverse Monte Carlo solution of transient radiation transport in the homogeneous media. In this study, the method is extended to consider nonhomogeneous media, which exist in many practical problems. The transport process of ultra-short light pulse propagation inside the non-emitting, absorbing, and anisotropically scattering multi-layer media is studied. Although only one-dimensional geometry is treated here, the method is applicable and easy to extend to multi-dimensional geometries. In multi-layer media, the time-resolved reflectance exhibits a direct correlation between the signal magnitude and the travel time to the layer interface if the ballistic photons encounter a strongly scattering layer. Furthermore, it is found that even with a symmetric radiative property distribution in a three-layer medium, the reflectance and transmittance signals do not converge at long time when the mid-layer is optically thick. The long time slope of the temporal signal does not provide the specificity required for an inverse analysis parameter as stipulated by earlier studies

  2. New approach for absolute fluence distribution calculations in Monte Carlo simulations of light propagation in turbid media

    International Nuclear Information System (INIS)

    Böcklin, Christoph; Baumann, Dirk; Fröhlich, Jürg

    2014-01-01

    A novel way to attain three dimensional fluence rate maps from Monte-Carlo simulations of photon propagation is presented in this work. The propagation of light in a turbid medium is described by the radiative transfer equation and formulated in terms of radiance. For many applications, particularly in biomedical optics, the fluence rate is a more useful quantity and directly derived from the radiance by integrating over all directions. Contrary to the usual way which calculates the fluence rate from absorbed photon power, the fluence rate in this work is directly calculated from the photon packet trajectory. The voxel based algorithm works in arbitrary geometries and material distributions. It is shown that the new algorithm is more efficient and also works in materials with a low or even zero absorption coefficient. The capabilities of the new algorithm are demonstrated on a curved layered structure, where a non-scattering, non-absorbing layer is sandwiched between two highly scattering layers

  3. Abnormal environmental light exposure in the intensive care environment.

    Science.gov (United States)

    Fan, Emily P; Abbott, Sabra M; Reid, Kathryn J; Zee, Phyllis C; Maas, Matthew B

    2017-08-01

    We sought to characterize ambient light exposure in the intensive care unit (ICU) environment to identify patterns of light exposure relevant to circadian regulation. A light monitor was affixed to subjects' bed at eye level in a modern intensive care unit and continuously recorded illuminescence for at least 24h per subject. Blood was sampled hourly and measured for plasma melatonin. Subjects underwent hourly vital sign and bedside neurologic assessments. Care protocols and the ICU environment were not modified for the study. A total of 67,324 30-second epochs of light data were collected from 17 subjects. Light intensity peaked in the late morning, median 64.1 (interquartile range 19.7-138.7) lux. The 75th percentile of light intensity exceeded 100lx only between 9AM and noon, and never exceeded 150lx. There was no correlation between melatonin amplitude and daytime, nighttime or total light exposure (Spearman's correlation coefficients all 0.5). Patients' environmental light exposure in the intensive care unit is consistently low and follows a diurnal pattern. No effect of nighttime light exposure was observed on melatonin secretion. Inadequate daytime light exposure in the ICU may contribute to abnormal circadian rhythms. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Valley-controlled propagation of pseudospin states in bulk metacrystal waveguides

    Science.gov (United States)

    Chen, Xiao-Dong; Deng, Wei-Min; Lu, Jin-Cheng; Dong, Jian-Wen

    2018-05-01

    Light manipulations such as spin-direction locking propagation, robust transport, quantum teleportation, and reconfigurable electromagnetic pathways have been investigated at the boundaries of photonic systems. Recently by breaking Dirac cones in time-reversal-invariant photonic crystals, valley-pseudospin coupled edge states have been employed to realize selective propagation of light. Here, we realize the controllable propagation of pseudospin states in three-dimensional bulk metacrystal waveguides by valley degree of freedom. Reconfigurable photonic valley Hall effect is achieved for frequency-direction locking propagation in such a way that the propagation path can be tunable precisely by scanning the working frequency. A complete transition diagram is illustrated on the valley-dependent pseudospin states of Dirac-cone-absent photonic bands. A photonic blocker is proposed by cascading two inversion asymmetric metacrystal waveguides in which pseudospin-direction locking propagation exists. In addition, valley-dependent pseudospin bands are also discussed in a realistic metamaterials sample. These results show an alternative way toward molding the pseudospin flow in photonic systems.

  5. Environmental conservation by the use of light metals

    International Nuclear Information System (INIS)

    Lorentsen, Odd-Arne

    2002-01-01

    The electrochemical processing industry produces about 22 million tonnes aluminium and 260 tonnes electrolytic magnesium each year. This causes the emission of the gases CO 2 , CF 4 , C 2 F 6 and SF 6 . These emissions are technology-dependent and can be substantially reduced by means of, for instance, inert anodes. When inert anodes can be used in the manufacture of light metals, oxygen will be produced rather than very strong greenhouse gases, which makes the use of light metals even more environmentally friendly. This technology is expected to be commercially available in the near future. As magnesium burns at temperatures above 500 o C when in contact with oxygen (air), and must be protected by an inert gas, a flux, or a cover gas. The gas SF 6 with a small admixture of CO 2 is an excellent cover gas. SF 6 reacts with the surface of the magnesium and forms stable compounds that protect the metal underneath from reacting with oxygen. Recently, however, SF 6 has become known as a very effective and stable greenhouse gas and many magnesium manufacturers are now using the cover gas SO 2 instead. About 80 per cent of the anthropogenic greenhouse gases are energy related. If more of the light metals aluminium and magnesium replaced steel in the transport sector, then the weight of the vehicles would be reduced by up to 40 per cent and the fuel consumption and air pollution by 30 per cent. Recirculation makes the light metals very environmentally friendly. Re-melting aluminium takes only five per cent of the energy of the primary production

  6. Nonreciprocal propagation of light without external magnetic fields in a semiconductor waveguide isolator with a MnAs layer

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, T. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan) and Japan Science and Techonology Agency, SORST (Japan)]. E-mail: ametomo@hotaka.t.u-tokyo.ac.jp; Shimizu, H. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Japan Science and Techonology Agency, SORST (Japan); Hai, P.N. [Department of Electronic Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Japan Science and Techonology Agency, SORST (Japan); Tanaka, M. [Department of Electronic Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Japan Science and Techonology Agency, SORST (Japan); Nakano, Y. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Japan Science and Techonology Agency, SORST (Japan)

    2007-03-15

    A 1.5-{mu}m, TM-mode waveguide optical isolator was developed for use in photonic integrated circuits. It consists of an InGaAlAs-based optical waveguide with a ferromagnetic MnAs layer and makes use of nonreciprocal propagation loss of light induced by the magnetized MnAs layer. With a large-remanence MnAs layer grown with the Mn-template epitaxy method, the isolator successfully showed an 8.7 dB/mm isolation ratio without external magnetic fields.

  7. Optical propagation in linear media atmospheric gases and particles, solid-state components, and water

    CERN Document Server

    Thomas, Michael E

    2006-01-01

    PART I: Background Theory and Measurement. 1. Optical Electromagnetics I. 2. Optical Electromagnetics II. 3. Spectroscopy of Matter. 4. Electrodynamics I: Macroscopic Interaction of Light and Matter. 5. Electrodynamics II: Microscopic Interaction of Light and Matter. 6. Experimental Techniques. PART II: Practical Models for Various Media. 7. Optical Propagation in Gases and the Atmosphere of the Earth. 8. Optical Propagation in Solids. 9. Optical Propagation in Liquids. 10. Particle Absorption and Scatter. 11. Propagation Background and Noise

  8. Generation, amplification and propagation of partially coherent light in a Nd:glass laser driver for inertial confinement fusion

    International Nuclear Information System (INIS)

    Nakano, Hitoshi; Tsubakimoto, Kouji; Miyanaga, Noriaki; Nakatsuka, Masahiro; Kanabe, Tadashi.

    1992-01-01

    A partially coherent light source has been introduced into the high power twelve beam Nd:glass laser system, Gekko XII for obtaining the smooth intensity distribution of a focused beam pattern. An amplified spontaneous emission (ASE) from Nd:glass was used as a partially coherent source. We adopted the angularly dispersed spectrum not only for beam smoothing but for efficient harmonic conversion. The temporal evolution of the speckle smoothing was experimentally evaluated and compared with a statistical model of speckle pattern. In the amplification of a partially coherent light in Gekko XII, no reduction of the energy gain was found at high power operation 1kJ level. The ASE light can be propagated using image relaying spatial filters, with maintaining the beam divergence up to 32 times diffraction limited. Irradiation nonuniformities on a spherical target were estimated from the focused beam patterns measured at an equivalent target plane. A partially coherent light is quite effective for reducing the nonuniformity from 19.7% (the coherent laser with random phase plate) to 3.8%. Doubling efficiency was found to be reduced at high intensity region due to the phase mismatching with the beam divergence of the ASE light. We discuss possible approaches to obtain the sufficient harmonic conversion with keeping the incoherency of the ASE light. (author)

  9. Impact of slow-light enhancement on optical propagation in active semiconductor photonic crystal waveguides

    DEFF Research Database (Denmark)

    Chen, Yaohui; de Lasson, Jakob Rosenkrantz; Gregersen, Niels

    2015-01-01

    We derive and validate a set of coupled Bloch wave equations for analyzing the reflection and transmission properties of active semiconductor photonic crystal waveguides. In such devices, slow-light propagation can be used to enhance the material gain per unit length, enabling, for example......, the realization of short optical amplifiers compatible with photonic integration. The coupled wave analysis is compared to numerical approaches based on the Fourier modal method and a frequency domain finite element technique. The presence of material gain leads to the build-up of a backscattered field, which...... is interpreted as distributed feedback effects or reflection at passive-active interfaces, depending on the approach taken. For very large material gain values, the band structure of the waveguide is perturbed, and deviations from the simple coupled Bloch wave model are found....

  10. Light propagation in multilayer metamaterials

    NARCIS (Netherlands)

    Maas, R.C.

    2015-01-01

    Metamaterials are artificially constructed materials composed of sub-wavelength building blocks that are designed to interact with light in ways that cannot be achieved with natural materials. Over the last years, improvements in nanoscale fabrication and in metamaterial design have led to the

  11. Simulation of light propagation in the thin-film waveguide lens

    Science.gov (United States)

    Malykh, M. D.; Divakov, D. V.; Sevastianov, L. A.; Sevastianov, A. L.

    2018-04-01

    In this paper we investigate the solution of the problem of modeling the propagation of electromagnetic radiation in three-dimensional integrated optical structures, such as waveguide lenses. When propagating through three-dimensional waveguide structures the waveguide modes can be hybridized, so the mathematical model of their propagation must take into account the connection of TE- and TM-mode components. Therefore, an adequate consideration of hybridization of the waveguide modes is possible only in vector formulation of the problem. An example of three-dimensional structure that hybridizes waveguide modes is the Luneburg waveguide lens, which also has focusing properties. If the waveguide lens has a radius of the order of several tens of wavelengths, its variable thickness at distances of the order of several wavelengths is almost constant. Assuming in this case that the electromagnetic field also varies slowly in the direction perpendicular to the direction of propagation, one can introduce a small parameter characterizing this slow varying and decompose the solution in powers of the small parameter. In this approach, in the zeroth approximation, scalar diffraction problems are obtained, the solution of which is less resource-consuming than the solution of vector problems. The calculated first-order corrections of smallness describe the connection of TE- and TM-modes, so the solutions obtained are weakly-hybridized modes. The formulation of problems and methods for their numerical solution in this paper are based on the authors' research on waveguide diffraction on a lens in a scalar formulation.

  12. Environmental impacts of lighting technologies - Life cycle assessment and sensitivity analysis

    International Nuclear Information System (INIS)

    Welz, Tobias; Hischier, Roland; Hilty, Lorenz M.

    2011-01-01

    With two regulations, 244/2009 and 245/2009, the European Commission recently put into practice the EuP Directive in the area of lighting devices, aiming to improve energy efficiency in the domestic lighting sector. This article presents a comprehensive life cycle assessment comparison of four different lighting technologies: the tungsten lamp, the halogen lamp, the conventional fluorescent lamp and the compact fluorescent lamp. Taking advantage of the most up-to-date life cycle inventory database available (ecoinvent data version 2.01), all life cycle phases were assessed and the sensitivity of the results for varying assumptions analysed: different qualities of compact fluorescent lamps (production phase), different electricity mixes (use phase), and end-of-life scenarios for WEEE recycling versus municipal solid waste incineration (disposal phase). A functional unit of 'one hour of lighting' was defined and the environmental burdens for the whole life cycle for all four lamp types were calculated, showing a clearly lower impact for the two gas-discharge lamps, i.e. the fluorescent and the compact fluorescent lamp. Differences in the product quality of the compact fluorescent lamps reveal to have only a very small effect on the overall environmental performance of this lamp type; a decline of the actual life time of this lamp type doesn't result in a change of the rank order of the results of the here examined four lamp types. It was also shown that the environmental break-even point of the gas-discharge lamps is reached long before the end of their expected life-span. All in all, it can be concluded that a change from today's tungsten lamp technology to a low-energy-consuming technology such as the compact fluorescent lamp results in a substantial environmental benefit.

  13. TRANSBOUNDARY DAMAGE IN THE LIGHT OF INTERNATIONAL ENVIRONMENTAL LAW

    Directory of Open Access Journals (Sweden)

    Oana Maria HANCIU

    2014-05-01

    Full Text Available Some activities that are useful for economic and social development of a State even if are not prohibited by national or international law can cause transboundary damages to other countries. This kind of transboundary damages have given rise to theories of State responsibility and a worldwide demand for increased environmental protection. "Under the principles of international law...no State has the right to use or permit the use of its territory in such a manner as to cause [environmental] injury ... in or to the territory of another or the properties of persons therein, when the case is of serious consequence and the injury is established by clear and convincing evidence." (Stockholm Principle 21 The paper analyses the impact of transboundary damage in the light of international environmental law and the increasing concern among States for environmental protection.

  14. 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...

  15. Overview of environmental materials degradation in light-water reactors

    International Nuclear Information System (INIS)

    Shaaban, H.I.; Wu, P.

    1986-08-01

    This report provides a brief overview of analyses and conclusions reported in published literature regarding environmentally induced degradation of materials in operating light-water reactors. It is intended to provide a synopsis of subjects of concern rather than to address a licensing basis for any newly discovered problems related to reactor materials

  16. Consequences of Spatial Antisymmetry on Light

    Energy Technology Data Exchange (ETDEWEB)

    Mascarenhas, Angelo; Fluegel, Brian

    2016-12-21

    Light propagation in two and three dimensional lattices for which the index of refraction exhibits spatial antisymmetry is investigated in the ray and photonic crystal regimes. In these regimes, all the two dimensional antisymmetry groups for which light fails to propagate are identified. In the ray-regime, it is observed that in tilings described by 7 of the 46 two dimensional antisymmetric groups, light is localized within a fundamental domain and does not propagate through the tiling, in contrast to the behavior in the other 39 groups. To understand the above phenomenon, a rule based on the number of anti-mirror planes passing through a single Bravais lattice point is derived. In the wave regime for photonic crystals, it is observed that there are no propagating eigensolutions for the same 7 tilings as above, whereas propagating solutions and energy pass band dispersion curves can be obtained for the other 39 groups. The reasons underlying this peculiar behavior are analyzed using the topological approach for modeling flow in dynamical billiards to shed light on the applicability of Bloch's theorem for these periodic antisymmetric lattices.

  17. Shape deformation of a light flash through a light pipe

    International Nuclear Information System (INIS)

    Calligaris, F.; Ciuti, P.; Gabrielli, I.; Giacomich, R.

    1976-01-01

    The propagation of a LED light pulse entering a rectangular light pipe under different angles is studied by the single-photon counting technique. A comparison with the theoretical predictions based on geometrical optics is reported. (Auth.)

  18. Kinetic-sound propagation in dilute gas mixtures

    International Nuclear Information System (INIS)

    Campa, A.; Cohen, E.G.D.

    1989-01-01

    Kinetic sound is predicted in dilute disparate-mass binary gas mixtures, propagating exclusively in the light compound and much faster than ordinary sound. It should be detectable by light-scattering experiments, as an extended shoulder in the scattering cross section for large frequencies. As an example, H 2 -Ar mixtures are discussed

  19. Plasmonics light modulators

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Malureanu, Radu; Lavrinenko, Andrei

    Surface plasmon polaritons (SPPs) are waves propagating at the interface between a metal and a dielectric and, due to their tight confinement, may be used for nanoscale control of the light propagation. Thus, photonic integrated circuits can benefit from devices using SPPs because of their highly...

  20. Gain-assisted superluminal propagation and rotary drag of photon and surface plasmon polaritons

    Science.gov (United States)

    Khan, Naveed; Amin Bacha, Bakht; Iqbal, Azmat; Ur Rahman, Amin; Afaq, A.

    2017-07-01

    Superluminal propagation of light is a well-established phenomenon and has motivated immense research interest that has led to state-of-the-art knowledge and potential applications in the emerging technology of quantum optics and photonics. This study presents a theoretical analysis of the gain-assisted superluminal light propagation in a four-level N -type atomic system by exploiting the scheme of electromagnetically induced gain and superluminal propagation of surface plasmon polaritons (SPPs) along the gain-assisted atomic-metal interface simultaneously. In addition, a theoretical demonstration is presented on the comparison between Fresnel's rotary photon drag and SPP drag in view of light polarization state rotation by rotating the coherent atomic medium and the atomic-metal interface, respectively. Analogous to photon drag in the superluminal anomalous dispersion region where light polarization rotation occurs opposite the rotation of the gain-assisted atomic medium, the rotation of the atomic-metal interface also rotates the polarization state of SPPs opposite the rotation of the interface. This further confirms the superluminal nature of SPPs propagating along the interface with negative group velocity. Rabi frequencies of the control and pump fields considerably modify both photon and SPP drag coefficients. Metal conductivity also controls SPP propagation.

  1. Switching of the direction of reflectionless light propagation at exceptional points in non-PT-symmetric structures using phase-change materials.

    Science.gov (United States)

    Huang, Yin; Shen, Yuecheng; Min, Changjun; Veronis, Georgios

    2017-10-30

    We introduce a non-parity-time-symmetric three-layer structure, consisting of a gain medium layer sandwiched between two phase-change medium layers for switching of the direction of reflectionless light propagation. We show that for this structure unidirectional reflectionlessness in the forward direction can be switched to unidirectional reflectionlessness in the backward direction at the optical communication wavelength by switching the phase-change material Ge 2 Sb 2 Te 5 (GST) from its amorphous to its crystalline phase. We also show that it is the existence of exceptional points for this structure with GST in both its amorphous and crystalline phases which leads to unidirectional reflectionless propagation in the forward direction for GST in its amorphous phase, and in the backward direction for GST in its crystalline phase. Our results could be potentially important for developing a new generation of compact active free-space optical devices.

  2. 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.

  3. Emission of a propagation invariant flat-top beam from a microchip laser

    Energy Technology Data Exchange (ETDEWEB)

    Naidoo, Darryl [Council for Scientific and Industrial Research, National Laser Centre, P.O. Box 395, Pretoria 0001 (South Africa); Harfouche, A. [Faculté de Physique, Université des Sciences et de la Technologie Houari Boumédiène, B.P. no 32, El Alia, 16111 Algiers (Algeria); Fromager, Michael; Ait-Ameur, Kamel [Centre de Recherche sur les Ions, les Matériaux et la Photonique, Unité Mixte de Recherche de Recherche 6252, Commissariat à l’Energie Atomique, Centre National de la Recherche Scientifique, Université de Caen Basse Normandie, Ecole Nationale Supérieure des Ingénieurs de Caen, Boulevard Maréchal Juin, F14050 Caen (France); Forbes, Andrew, E-mail: andrew.forbes@wits.ac.za [School of Physics, University of the Witwatersrand, Private Bag 3, Johannesburg 2050 (South Africa)

    2016-02-15

    Light beams with a flat-top intensity profile have found many applications in both pure and applied studies, but are not the natural modes of conventional light sources such as lasers. Moreover, such light beams are also not the eigenmodes of the wave equation in a vacuum and so change their intensity profile dramatically during propagation. Here we overcome both these limitations and create a propagation invariant flat-top beam from a microchip laser. By optical feedback into the excited medium we are able to create emission that is an incoherent mix of two spatial modes, a Gaussian and a donut, so that the sum is a flat-top beam that maintains its shape to infinity. Such miniature sources that emit structured light will be attractive for integrated light-based technologies. - Highlights: • First demonstration of the generation of a flat-top beam from a microchip laser. • The flat-top beam is shape-invariant during propagation. • By optical feedback we can select the desired shape from the microchip laser.

  4. Emission of a propagation invariant flat-top beam from a microchip laser

    International Nuclear Information System (INIS)

    Naidoo, Darryl; Harfouche, A.; Fromager, Michael; Ait-Ameur, Kamel; Forbes, Andrew

    2016-01-01

    Light beams with a flat-top intensity profile have found many applications in both pure and applied studies, but are not the natural modes of conventional light sources such as lasers. Moreover, such light beams are also not the eigenmodes of the wave equation in a vacuum and so change their intensity profile dramatically during propagation. Here we overcome both these limitations and create a propagation invariant flat-top beam from a microchip laser. By optical feedback into the excited medium we are able to create emission that is an incoherent mix of two spatial modes, a Gaussian and a donut, so that the sum is a flat-top beam that maintains its shape to infinity. Such miniature sources that emit structured light will be attractive for integrated light-based technologies. - Highlights: • First demonstration of the generation of a flat-top beam from a microchip laser. • The flat-top beam is shape-invariant during propagation. • By optical feedback we can select the desired shape from the microchip laser.

  5. Coherent field propagation between tilted planes.

    Science.gov (United States)

    Stock, Johannes; Worku, Norman Girma; Gross, Herbert

    2017-10-01

    Propagating electromagnetic light fields between nonparallel planes is of special importance, e.g., within the design of novel computer-generated holograms or the simulation of optical systems. In contrast to the extensively discussed evaluation between parallel planes, the diffraction-based propagation of light onto a tilted plane is more burdensome, since discrete fast Fourier transforms cannot be applied directly. In this work, we propose a quasi-fast algorithm (O(N 3  log N)) that deals with this problem. Based on a proper decomposition into three rotations, the vectorial field distribution is calculated on a tilted plane using the spectrum of plane waves. The algorithm works on equidistant grids, so neither nonuniform Fourier transforms nor an explicit complex interpolation is necessary. The proposed algorithm is discussed in detail and applied to several examples of practical interest.

  6. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products, Part 3: LED Environmental Testing

    Energy Technology Data Exchange (ETDEWEB)

    Tuenge, Jason R.; Hollomon, Brad; Dillon, Heather E.; Snowden-Swan, Lesley J.

    2013-03-01

    This report covers the third part of a larger U.S. Department of Energy (DOE) project to assess the life-cycle environmental and resource impacts in the manufacturing, transport, use, and disposal of light-emitting diode (LED) lighting products in relation to incumbent lighting technologies. All three reports are available on the DOE website (www.ssl.energy.gov/tech_reports.html). • Part 1: Review of the Life-Cycle Energy Consumption of Incandescent, Compact Fluorescent and LED Lamps; • Part 2: LED Manufacturing and Performance; • Part 3: LED Environmental Testing. Parts 1 and 2 were published in February and June 2012, respectively. The Part 1 report included a summary of the life-cycle assessment (LCA) process and methodology, provided a literature review of more than 25 existing LCA studies of various lamp types, and performed a meta-analysis comparing LED lamps with incandescent and compact fluorescent lamps (CFLs). Drawing from the Part 1 findings, Part 2 performed a more detailed assessment of the LED manufacturing process and used these findings to provide a comparative LCA taking into consideration a wider range of environmental impacts. Both reports concluded that the life-cycle environmental impact of a given lamp is dominated by the energy used during lamp operation—the upstream generation of electricity drives the total environmental footprint of the product. However, a more detailed understanding of end-of-life disposal considerations for LED products has become increasingly important as their installation base has grown. The Part 3 study (reported herein) was undertaken to augment the LCA findings with chemical analysis of a variety of LED, CFL, and incandescent lamps using standard testing procedures. A total of 22 samples, representing 11 different models, were tested to determine whether any of 17 elements were present at levels exceeding California or Federal regulatory thresholds for hazardous waste. Key findings include: • The selected

  7. Litrani: a general purpose Monte-Carlo program simulating light propagation in isotropic or anisotropic media

    International Nuclear Information System (INIS)

    Gentit, F.-X.

    2002-01-01

    Litrani is a general purpose Monte-Carlo program simulating light propagation in any type of setup describable by the shapes provided by ROOT. Each shape may be made of a different material. Dielectric constant, absorption length and diffusion length of materials may depend upon wavelength. Dielectric constant and absorption length may be anisotropic. Each face of a volume is either partially or totally in contact with a face of another volume, or covered with some wrapping having defined characteristics of absorption, reflection and diffusion. When in contact with another face of another volume, the possibility exists to have a thin slice of width d and index n between the two faces. The program has various sources of light: spontaneous photons, photons coming from an optical fibre, photons generated by the crossing of particles or photons generated by an electromagnetic shower. The time and wavelength spectra of emitted photons may reproduce any scintillation spectrum. As detectors, phototubes, APD, or any general type of surface or volume detectors may be specified. The aim is to follow each photon until it is absorbed or detected. Quantities to be delivered by the program are the proportion of photons detected, and the time distribution for the arrival of these, or the various ways photons may be lost

  8. Beam-quality measurements using a spatial light modulator

    CSIR Research Space (South Africa)

    Schulze, C

    2012-11-01

    Full Text Available We present a fast and easy technique for measuring the beam propagation ratio, M2, of laser beams using a spatial light modulator. Our technique is based on digitally simulating the free-space propagation of light, thus eliminating the need...

  9. Modulating light propagation in ZnO-Cu₂O-inverse opal solar cells for enhanced photocurrents.

    Science.gov (United States)

    Yantara, Natalia; Pham, Thi Thu Trang; Boix, Pablo P; Mathews, Nripan

    2015-09-07

    The advantages of employing an interconnected periodic ZnO morphology, i.e. an inverse opal structure, in electrodeposited ZnO/Cu2O devices are presented. The solar cells are fabricated using low cost solution based methods such as spin coating and electrodeposition. The impact of inverse opal geometry, mainly the diameter and thickness, is scrutinized. By employing 3 layers of an inverse opal structure with a 300 nm pore diameter, higher short circuit photocurrents (∼84% improvement) are observed; however the open circuit voltages decrease with increasing interfacial area. Optical simulation using a finite difference time domain method shows that the inverse opal structure modulates light propagation within the devices such that more photons are absorbed close to the ZnO/Cu2O junction. This increases the collection probability resulting in improved short circuit currents.

  10. Transverse Localization of Light

    NARCIS (Netherlands)

    Raedt, Hans De; Lagendijk, Ad; Vries, Pedro de

    1989-01-01

    We study the propagation of light through a semi-infinite medium with transverse disorder (that is, disorder in two directions only). We show that such a system exhibits strong two-dimensional localization by demonstrating that on propagation a beam expands until the transverse localization length

  11. Wave propagation in non-linear media

    NARCIS (Netherlands)

    Broer, L.J.F.

    1965-01-01

    The problem of the propagation of electromagnetic waves through solids is essentially one of interaction between light quanta and matter. The most fundamental and general treatment of this subject is therefore undoubtedly based on the quantummechanical theory of this interaction. Nevertheless, a

  12. Environmental blue light prevents stress in the fish Nile tilapia

    Directory of Open Access Journals (Sweden)

    Volpato G.L.

    2001-01-01

    Full Text Available The present study aimed to test the effects of blue, green or white light on the stress response of the Nile tilapia, Oreochromis niloticus (L.. Each color was tested on two groups of isolated adult Nile tilapia (8 replicates each: one being subjected to confinement stress, and the other not (control. A different environmental color was imposed on each compartment by covering the light source with cellophane of the respective color (green or blue; no cellophane was used for white light. The intensity of green, white and blue lights was 250, 590 and 250 lux, respectively. Basal plasma cortisol levels were determined for each fish prior to the experimental procedures. The fish were confined by being displaced toward one side of the aquarium using an opaque partition for 1 h both in the morning and the afternoon of the two consecutive days of the test. At the end of this 48-h period, plasma cortisol levels were measured again. Basal cortisol levels (ng/ml were similar for each group (ANOVA, F(2;42 = 0.77, P = 0.47. Thus, plasma cortisol levels were analyzed in terms of variation from their respective basal level. After confinement, plasma cortisol levels were not increased in fish submitted to a blue light environment. Thus, blue light prevents the confinement-induced cortisol response, an effect not necessarily related to light intensity.

  13. Propagation of monochromatic light in a hot and dense medium

    Science.gov (United States)

    Masood, Samina S.

    2017-12-01

    Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of the photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in an extremely hot and dense background. Photons acquire a dynamically generated mass in such a medium. The screening mass of the photon, the Debye shielding length and the plasma frequency are calculated as functions of the statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the properties of the medium lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe.

  14. Propagation of monochromatic light in a hot and dense medium

    Energy Technology Data Exchange (ETDEWEB)

    Masood, Samina S. [University of Houston Clear Lake, Department of Physical and Applied Sciences, Houston, TX (United States)

    2017-12-15

    Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of the photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in an extremely hot and dense background. Photons acquire a dynamically generated mass in such a medium. The screening mass of the photon, the Debye shielding length and the plasma frequency are calculated as functions of the statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the properties of the medium lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe. (orig.)

  15. The accuracy of dynamic attitude propagation

    Science.gov (United States)

    Harvie, E.; Chu, D.; Woodard, M.

    1990-01-01

    Propagating attitude by integrating Euler's equation for rigid body motion has long been suggested for the Earth Radiation Budget Satellite (ERBS) but until now has not been implemented. Because of limited Sun visibility, propagation is necessary for yaw determination. With the deterioration of the gyros, dynamic propagation has become more attractive. Angular rates are derived from integrating Euler's equation with a stepsize of 1 second, using torques computed from telemetered control system data. The environmental torque model was quite basic. It included gravity gradient and unshadowed aerodynamic torques. Knowledge of control torques is critical to the accuracy of dynamic modeling. Due to their coarseness and sparsity, control actuator telemetry were smoothed before integration. The dynamic model was incorporated into existing ERBS attitude determination software. Modeled rates were then used for attitude propagation in the standard ERBS fine-attitude algorithm. In spite of the simplicity of the approach, the dynamically propagated attitude matched the attitude propagated with good gyros well for roll and yaw but diverged up to 3 degrees for pitch because of the very low resolution in pitch momentum wheel telemetry. When control anomalies significantly perturb the nominal attitude, the effect of telemetry granularity is reduced and the dynamically propagated attitudes are accurate on all three axes.

  16. LIGHT-PROPAGATION THROUGH TEETH CONTAINING SIMULATED CARIES LESIONS

    NARCIS (Netherlands)

    VAARKAMP, J; TENBOSCH, JJ; VERDONSCHOT, EH

    The methods currently utilized in dentistry to detect caries lesions have their limitations and alternatives are being investigated. A promising option is tooth transillumination which is based on an increase of light scattering or light absorption in the affected tissue region. In this study

  17. Reducing environmental burdens of solid-state lighting through end-of-life design

    International Nuclear Information System (INIS)

    Hendrickson, C T; Matthews, D H; Ashe, M; Jaramillo, P; McMichael, F C

    2010-01-01

    With 20% of US electricity used for lighting, energy efficient solid-state lighting technology could have significant benefits. While energy efficiency in use is important, the life cycle cost, energy and environmental impacts of light-emitting diode (LED) solid-state lighting could be reduced by reusing, remanufacturing or recycling components of the end products. Design decisions at this time for the nascent technology can reduce material and manufacturing burdens by considering the ease of disassembly, potential for remanufacturing, and recovery of parts and materials for reuse and recycling. We use teardowns of three commercial solid-state lighting products designed to fit in conventional Edison light bulb sockets to analyze potential end-of-life reuse strategies for solid-state lighting and recommend strategies for the industry. Current lamp designs would benefit from standardization of part connections to facilitate disassembly and remanufacturing of components, and fewer material types in structural pieces to maximize homogeneous materials recovery. The lighting industry should also start now to develop an effective product take-back system for collecting future end-of-life products.

  18. Reducing environmental burdens of solid-state lighting through end-of-life design

    Energy Technology Data Exchange (ETDEWEB)

    Hendrickson, C T; Matthews, D H; Ashe, M; Jaramillo, P; McMichael, F C, E-mail: cth@cmu.ed [Green Design Institute, Carnegie Mellon University (United States)

    2010-01-15

    With 20% of US electricity used for lighting, energy efficient solid-state lighting technology could have significant benefits. While energy efficiency in use is important, the life cycle cost, energy and environmental impacts of light-emitting diode (LED) solid-state lighting could be reduced by reusing, remanufacturing or recycling components of the end products. Design decisions at this time for the nascent technology can reduce material and manufacturing burdens by considering the ease of disassembly, potential for remanufacturing, and recovery of parts and materials for reuse and recycling. We use teardowns of three commercial solid-state lighting products designed to fit in conventional Edison light bulb sockets to analyze potential end-of-life reuse strategies for solid-state lighting and recommend strategies for the industry. Current lamp designs would benefit from standardization of part connections to facilitate disassembly and remanufacturing of components, and fewer material types in structural pieces to maximize homogeneous materials recovery. The lighting industry should also start now to develop an effective product take-back system for collecting future end-of-life products.

  19. Light-Cone and Diffusive Propagation of Correlations in a Many-Body Dissipative System.

    Science.gov (United States)

    Bernier, Jean-Sébastien; Tan, Ryan; Bonnes, Lars; Guo, Chu; Poletti, Dario; Kollath, Corinna

    2018-01-12

    We analyze the propagation of correlations after a sudden interaction change in a strongly interacting quantum system in contact with an environment. In particular, we consider an interaction quench in the Bose-Hubbard model, deep within the Mott-insulating phase, under the effect of dephasing. We observe that dissipation effectively speeds up the propagation of single-particle correlations while reducing their coherence. In contrast, for two-point density correlations, the initial ballistic propagation regime gives way to diffusion at intermediate times. Numerical simulations, based on a time-dependent matrix product state algorithm, are supplemented by a quantitatively accurate fermionic quasiparticle approach providing an intuitive description of the initial dynamics in terms of holon and doublon excitations.

  20. Controlling spontaneous emission of light by photonic crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter

    2005-01-01

    Photonic bandgap crystals were proposed almost two decades ago as a unique tool for controlling propagation and emission of light. Since then the research field of photonic crystals has exploded and many beautiful demonstrations of the use of photonic crystals and fibers for molding light...... propagation have appeared that hold great promises for integrated optics. These major achievements solidly demonstrate the ability to control propagation of light. In contrast, an experimental demonstration of the use of photonic crystals for timing the emission of light has so far lacked. In a recent...... publication in Nature, we have demonstrated experimentally that both the direction and time of spontaneous emission can be controlled, thereby confirming the original proposal by Eli Yablonovich that founded the field of photonic crystals. We believe that this work opens new opportunities for solid...

  1. 75 FR 8753 - Carolina Power & Light Company, Brunswick Steam Electric Plant, Units 1 and 2; Environmental...

    Science.gov (United States)

    2010-02-25

    ... Dusenbury of the North Carolina Department of Environment and Natural Resources regarding the environmental... & Light Company, Brunswick Steam Electric Plant, Units 1 and 2; Environmental Assessment and Finding of No... identification of licensing and regulatory actions requiring environmental assessments,'' the NRC prepared an...

  2. Wave propagation in metamaterials mimicking the topology of a cosmic string

    Science.gov (United States)

    Fernández-Núñez, Isabel; Bulashenko, Oleg

    2018-04-01

    We study the interference and diffraction of light when it propagates through a metamaterial medium mimicking the spacetime of a cosmic string—a topological defect with curvature singularity. The phenomenon may look like a gravitational analogue of the Aharonov-Bohm effect, since the light propagates in a region where the Riemann tensor vanishes, being nonetheless affected by the non-zero curvature confined to the string core. We carry out the full-wave numerical simulation of the metamaterial medium and give the analytical interpretation of the results by use of the asymptotic theory of diffraction, which turns out to be in excellent agreement. In particular, we show that the main features of wave propagation in a medium with conical singularity can be explained by four-wave interference involving two geometrical optics and two diffracted waves.

  3. 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

  4. Light transmission through intraocular lenses with or without yellow chromophore (blue light filter) and its potential influence on functional vision in everyday environmental conditions.

    Science.gov (United States)

    Owczarek, Grzegorz; Gralewicz, Grzegorz; Skuza, Natalia; Jurowski, Piotr

    2016-01-01

    In this research the factors used to evaluate the light transmission through two types of acrylic hydrophobic intraocular lenses, one that contained yellow chromophore that blocks blue light transmission and the other which did not contain that filter, were defined according to various light condition, e.g., daylight and at night. The potential influence of light transmission trough intraocular lenses with or without yellow chromophore on functional vision in everyday environmental conditions was analysed.

  5. Photonic Switching Devices Using Light Bullets

    Science.gov (United States)

    Goorjian, Peter M. (Inventor)

    1999-01-01

    A unique ultra-fast, all-optical switching device or switch is made with readily available, relatively inexpensive, highly nonlinear optical materials. which includes highly nonlinear optical glasses, semiconductor crystals and/or multiple quantum well semiconductor materials. At the specified wavelengths. these optical materials have a sufficiently negative group velocity dispersion and high nonlinear index of refraction to support stable light bullets. The light bullets counter-propagate through, and interact within the waveguide to selectively change each others' directions of propagation into predetermined channels. In one embodiment, the switch utilizes a rectangularly planar slab waveguide. and further includes two central channels and a plurality of lateral channels for guiding the light bullets into and out of the waveguide. An advantage of the present all-optical switching device lies in its practical use of light bullets, thus preventing the degeneration of the pulses due to dispersion and diffraction at the front and back of the pulses. Another advantage of the switching device is the relative insensitivity of the collision process to the time difference in which the counter-propagating pulses enter the waveguide. since. contrary to conventional co-propagating spatial solitons, the relative phase of the colliding pulses does not affect the interaction of these pulses. Yet another feature of the present all-optical switching device is the selection of the light pulse parameters which enables the generation of light bullets in nonlinear optical materials. including highly nonlinear optical glasses and semiconductor materials such as semiconductor crystals and/or multiple quantum well semiconductor materials.

  6. Characteristic of laser diode beam propagation through a collimating lens.

    Science.gov (United States)

    Xu, Qiang; Han, Yiping; Cui, Zhiwei

    2010-01-20

    A mathematical model of a laser diode beam propagating through a collimating lens is presented. Wave propagation beyond the paraxial approximation is studied. The phase delay of the laser diode wave in passing through the lens is analyzed in detail. The propagation optical field after the lens is obtained from the diffraction integral by the stationary phase method. The model is employed to predict the light intensity at various beam cross sections, and the computed intensity distributions are in a good agreement with the corresponding measurements.

  7. Propagation of ionization waves during ignition of fluorescent lamps

    International Nuclear Information System (INIS)

    Langer, R; Tidecks, R; Horn, S; Garner, R; Hilscher, A

    2008-01-01

    The propagation of the first ionization wave in a compact fluorescent lamp (T4 tube with standard electrodes) during ignition was investigated for various initial dc-voltages (both polarities measured against ground) and gas compositions (with and without mercury). In addition the effect of the presence of a fluorescent powder coating was studied. The propagation velocity of the initial wave was measured by an assembly of photomultipliers installed along the tube, which detected the light emitted by the wave head. The propagation was found to be faster for positive than for negative polarity. This effect is explained involving processes in the electrode region as well as in the wave head. Waves propagate faster in the presence of a fluorescent powder coating than without it and gases of lighter mass show a faster propagation than gases with higher mass

  8. Nonlinear Gain Saturation in Active Slow Light Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2013-01-01

    We present a quantitative three-dimensional analysis of slow-light enhanced traveling wave amplification in an active semiconductor photonic crystal waveguides. The impact of slow-light propagation on the nonlinear gain saturation of the device is investigated.......We present a quantitative three-dimensional analysis of slow-light enhanced traveling wave amplification in an active semiconductor photonic crystal waveguides. The impact of slow-light propagation on the nonlinear gain saturation of the device is investigated....

  9. WOW: light print, light propel, light point

    Science.gov (United States)

    Glückstad, Jesper; Bañas, Andrew; Aabo, Thomas; Palima, Darwin

    2012-10-01

    We are presenting so-called Wave-guided Optical Waveguides (WOWs) fabricated by two-photon polymerization and capable of being optically manipulated into any arbitrary orientation. By integrating optical waveguides into the structures we have created freestanding waveguides which can be positioned anywhere in a sample at any orientation using real-time 3D optical micromanipulation with six degrees of freedom. One of the key aspects of our demonstrated WOWs is the change in direction of in-coupled light and the marked increase in numerical aperture of the out-coupled light. Hence, each light propelled WOW can tap from a relatively broad incident beam and generate a much more tightly confined light at its tip. The presentation contains both numerical simulations related to the propagation of light through a WOW and preliminary experimental demonstrations on our BioPhotonics Workstation. In a broader context, this research shows that optically trapped micro-fabricated structures can potentially help bridge the diffraction barrier. This structure-mediated paradigm may be carried forward to open new possibilities for exploiting beams from far-field optics down to the sub-wavelength domain.

  10. Factors Affecting Microcuttings of Stevia Using a Mist-Chamber Propagation Box

    Directory of Open Access Journals (Sweden)

    Mohamad Osman

    2013-01-01

    Full Text Available Stevia rebaudiana Bertoni is a member of Compositae family. Stevia plant has zero calorie content and its leaves are estimated to be 300 times sweeter than sugar. This plant is believed to be the most ideal substitute for sugar and important to assist in medicinal value especially for diabetic patients. In this study, microcutting techniques using a mist-chamber propagation box were used as it was beneficial for propagation of Stevia and gave genetic uniformity to the plant. The effects of different treatments on root stimulation of Stevia in microcuttings technique were evaluated. Treatments studied were different sizes of shoot cuttings, plant growth regulators, lights, and shades. Data logger was used to record the mean value of humidity (>90% RH, light intensity (673–2045 lx, and temperature (28.6–30.1°C inside the mist-chamber propagation box. From analysis of variance, there were significant differences between varieties and treatments in parameters studied (P<0.05. For the size of shoot cuttings treatment, 6 nodes cuttings were observed to increase root number. As compared to control, shoot cuttings treated with indole butyric acid (IBA had better performance regarding root length. Yellow light and 50% shade treatments showed higher root and leaf number and these conditions can be considered as crucial for potential propagation of Stevia.

  11. Light storage via slow-light four-wave mixing

    International Nuclear Information System (INIS)

    Fan, Yun-Fei; Wang, Hai-Hua; Wei, Xiao-Gang; Li, Ai-Jun; Kang, Zhi-Hui; Wu, Jin-Hui; Zhang, Han-Zhuang; Xu, Huai-Liang; Gao, Jin-Yue

    2012-01-01

    We experimentally demonstrate a light storage via slow-light four-wave mixing in a solid-state medium with a four-level double lambda scheme. Using slow light based on electromagnetically induced transparency, we obtain a slowed four-wave mixing signal pulse together with the slowed probe pulse. During the propagation of light pulses, the storage and retrieval of both the slowed four-wave mixing pulse and the slowed probe pulse are studied by manipulating the intensities of the control fields. -- Highlights: ► A light storage via slow-light four-wave mixing is observed in a solid. ► The probe pulse is slowed under electromagnetically induced transparency. ► A slowed four-wave mixing pulse is obtained by slow light. ► The storage of slowed double pulses is studied.

  12. Rotating light ion beam-plasma system in inertial confinement fusion

    International Nuclear Information System (INIS)

    Murakami, H.; Okada, T.

    1997-01-01

    The stabilizing mechanism of filamentation instability in light ion beam propagation is studied numerically by using a particle-in-cell code. Rotating light ion beam scheme has been proposed for the light ion beam propagation. The filamentation instability is stabilized by the external magnetic field which is induced by the rotating light ion beams. From a dispersion relation, linear growth rates of filamentation instabilities are obtained in a light ion beam-plasma system with an external magnetic field. The theory and simulation comparisons illustrate the results. (author)

  13. 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.

  14. Latitudinally propagating on-off switching aurorae and associated geomagnetic pulsations

    International Nuclear Information System (INIS)

    Oguti, T.; Kokubun, S.; Hayashi, K.; Tsuruda, K.; Machida, S.; Kitamura, T.; Saka, O.; Watanabe, T.

    1981-01-01

    Poleward propagating on-off switching aurorae and equatorward propagating aurorae, otherwise similar, were observed simultaneously at Rabbit Lake and La Ronge, respectively, for about 40 min before dawn of Feb 20, 1980. Rabbit Lake is a high auroral latitude site at the northern end of the Saskatchewan chain of stations for the Pulsating Aurora Campaign, whereas La Ronge, due south of Rabbit, is almost at the southern edge of the auroral zone. The repetition periods of the on-off switching aurorae are about 6 to 13 s. The poleward propagating aurorae had well defined fronts of light which extended a few hundred kilometres or more in the east-west direction. The light fronts of the equatorward propagating aurorae, though comparable in extent, were less well defined: they were thicker and fuzzier. The poleward propagating aurorae moved with a speed of approximately 10 km/s whereas the equatorward ones did so with a slightly greater velocity. Geomagnetic field fluctuations were concurrent with the aurorae at both sites. At Rabbit Lake, northward (southward) field changes were associated with upward (downward) changes, whereas the trend is reversed at La Ronge, viz., northward (southward) changes with downward (upward) changes. These trends are consistent with a model of a periodic occurrence of two line currents, westward and eastward, the former moving poleward north of Rabbit Lake and the latter approaching La Ronge from the north

  15. Experimentally determined characteristics of the degree of polarization of backscattered light from polystyrene sphere suspensions

    International Nuclear Information System (INIS)

    Sun, Ping; Ma, Yongchao; Xu, Chengwei; Sun, Xiaochun; Liu, Wei

    2013-01-01

    The degree of polarization (DOP) can be used to characterize the polarization-maintaining ability of a beam of polarized light propagating through a turbid medium. Experiments on polystyrene (PST) sphere suspensions show that, the linearly polarized light propagating through the PST sphere suspension of Rayleigh scatterers has better polarization-maintaining ability, whereas the circularly polarized light propagating through the PST sphere suspension of Mie scatterers has better polarization-maintaining ability. Moreover, helicity flipping occurs to the circularly polarized light propagating in the extremely weak PST sphere suspensions or on the surface of suspensions. In addition, the DOP is dependent on the wavelength of incident light. The results can be helpful to image in turbid media by use of diffuse backscattered light. (paper)

  16. Study of phonon propagation in water using picosecond ultrasonics

    International Nuclear Information System (INIS)

    Yang, F; Atay, T; Dang, C H; Grimsley, T J; Che, S; Ma, J; Zhang, Q; Nurmikko, A V; Maris, H J

    2007-01-01

    The propagation of ultra-short sound pulses in water is studied by using the picosecond ultrasonic technique. A sound pulse is generated when light is absorbed in a metal transducer film deposited onto a substrate. The sound propagates across a thin layer of water and is then reflected back to the surface at which it was generated. The efficiency of optoacoustic detection of the reflected sound is enhanced through the use of a resonant optical cavity. We show that the variation of the shape of the returning sound pulse with propagation distance agrees with that calculated by using the attenuation of sound in water that has been measured at lower frequencies

  17. Slow light in moving media

    Science.gov (United States)

    Leonhardt, U.; Piwnicki, P.

    2001-06-01

    We review the theory of light propagation in moving media with extremely low group velocity. We intend to clarify the most elementary features of monochromatic slow light in a moving medium and, whenever possible, to give an instructive simplified picture.

  18. Bistability, multistability and non-reciprocal light propagation in Thue-Morse multilayered structures

    International Nuclear Information System (INIS)

    Grigoriev, Victor; Biancalana, Fabio

    2010-01-01

    The nonlinear properties of quasi-periodic photonic crystals based on the Thue-Morse sequence are investigated. The intrinsic spatial asymmetry of these one-dimensional structures for odd generation numbers results in bistability thresholds, which are sensitive to the propagation direction. Along with resonances of perfect transmission, this feature allows us to achieve strongly non-reciprocal propagation and to create an all-optical diode. The salient qualitative features of such optical diode action are readily explained through a simple coupled resonator model. The efficiency of a passive scheme that does not necessitate an additional short pump signal is compared to an active scheme where such a signal is required.

  19. Systematic design of loss-engineered slow-light waveguides

    DEFF Research Database (Denmark)

    Wang, Fengwen; Jensen, Jakob Søndergaard; Mørk, Jesper

    2012-01-01

    This paper employs topology optimization to systematically design free-topology loss-engineered slow-light waveguides with enlarged group index bandwidth product (GBP). The propagation losses of guided modes are evaluated by the imaginary part of eigenvalues in complex band structure calculations......, where the scattering losses due to manufacturing imperfections are represented by an edge-related effective dissipation. The loss engineering of slow-light waveguides is realized by minimizing the propagation losses of design modes. Numerical examples illustrate that the propagation losses of free......-topology dispersion-engineered waveguides can be significantly suppressed by loss engineering. Comparisons between fixed- and free-topology loss-engineered waveguides demonstrate that the GBP can be enhanced significantly by the free-topology loss-engineered waveguides with a small increase of the propagation losses....

  20. Time-dependent corrosion fatique crack propagation in 7000 series aluminum alloys. M.S. Thesis

    Science.gov (United States)

    Mason, Mark E.

    1995-01-01

    The goal of this research is to characterize environmentally assisted subcritical crack growth for the susceptible short-longitudinal orientation of aluminum alloy 7075-T651, immersed in acidified and inhibited NaCl solution. This work is necessary in order to provide a basis for incorporating environmental effects into fatigue crack propagation life prediction codes such as NASA-FLAGRO (NASGRO). This effort concentrates on determining relevant inputs to a superposition model in order to more accurately model environmental fatigue crack propagation.

  1. Spectral changes in stochastic anisotropic electromagnetic beams propagating through turbulent ocean

    Science.gov (United States)

    Tang, Miaomiao; Zhao, Daomu

    2014-02-01

    Based on the extended Huygens-Fresnel principle and the unified theory of coherence and polarization of light, the spectral changes of stochastic anisotropic electromagnetic beams propagating through oceanic turbulence are revealed. As an example, some numerical calculations are illustrated for an anisotropic electromagnetic Gaussian Schell-model beam propagating in a homogeneous and isotropic turbulent ocean. It is shown that, under the influence of oceanic turbulence, the on-axis spectrum is always blue-shifted along with the propagation distance, however, for the off-axis positions, red-blue spectral switch can be found.

  2. Laser Beam Propagation Through Inhomogeneous Media with Shock-Like Profiles: Modeling and Computing

    Science.gov (United States)

    Adamovsky, Grigory; Ida, Nathan

    1997-01-01

    Wave propagation in inhomogeneous media has been studied for such diverse applications as propagation of radiowaves in atmosphere, light propagation through thin films and in inhomogeneous waveguides, flow visualization, and others. In recent years an increased interest has been developed in wave propagation through shocks in supersonic flows. Results of experiments conducted in the past few years has shown such interesting phenomena as a laser beam splitting and spreading. The paper describes a model constructed to propagate a laser beam through shock-like inhomogeneous media. Numerical techniques are presented to compute the beam through such media. The results of computation are presented, discussed, and compared with experimental data.

  3. Retinal protein synthesis in relationship to environmental lighting

    International Nuclear Information System (INIS)

    Hollyfield, J.G.; Anderson, R.E.

    1982-01-01

    A series of in vivo and in vitro experiments using Xenopus laevis juvenile toads was conducted to probe the relationship between environmental lighting and protein synthesis in the retina. Autoradiographic and biochemical analyses indicated that measurable changes in protein synthesis did not occur during a normal diurnal cycle when animals were conditioned to 12 hr light followed by 12 hr darkness each day (LD). However, when retinas from animals maintained in continuous darkness (DD) for 3 days were incubated with 3 H-leucine, there was a 40% reduction in the specific radioactivity of total retinal proteins compared with retinas from animals maintained in continuous light (LL) for 3 days or on the LD cycle. Retinas from DD animals injected with 3 H-leucine showed a 48% reduction in protein synthesis compared with retinas of LL animals. In autoradiographs of retinas from in vivo or in vitro experiments, grain counts were 40% lower in the total retinas of the DD animals compared with retinas of LL animals. This reduction occurred throughout the entire retina and was not restricted to any specific cell type. There was also a 35% reduction in the rate of radioactive band displacement in the rod outer segments of DD animals, although the percent of 3 H-leucine incorporated into opsin relative to total retinal protein was the same for both groups. We conclude from these studies that fluctuations in the rate of protein synthesis during the normal light-dark cycle are not detectable. However, major differences in protein synthesis are evident when animals are stressed with continuous darkness for several days. This effect is not restricted to any particular retinal layer but occurs throughout the entire retina. Moreover, prolonged darkness affects protein synthesis in extraocular tissues as well

  4. Factors affecting microcuttings of Stevia using a mist-chamber propagation box.

    Science.gov (United States)

    Osman, Mohamad; Samsudin, Nur Syamimi; Faruq, Golam; Nezhadahmadi, Arash

    2013-01-01

    Stevia rebaudiana Bertoni is a member of Compositae family. Stevia plant has zero calorie content and its leaves are estimated to be 300 times sweeter than sugar. This plant is believed to be the most ideal substitute for sugar and important to assist in medicinal value especially for diabetic patients. In this study, microcutting techniques using a mist-chamber propagation box were used as it was beneficial for propagation of Stevia and gave genetic uniformity to the plant. The effects of different treatments on root stimulation of Stevia in microcuttings technique were evaluated. Treatments studied were different sizes of shoot cuttings, plant growth regulators, lights, and shades. Data logger was used to record the mean value of humidity (>90% RH), light intensity (673-2045 lx), and temperature (28.6-30.1°C) inside the mist-chamber propagation box. From analysis of variance, there were significant differences between varieties and treatments in parameters studied (P Stevia.

  5. Nonlinear propagation in fusion laser systems

    International Nuclear Information System (INIS)

    Bliss, E.S.; Glass, A.J.; Glaze, J.A.

    1977-11-01

    This report was assembled to provide a brief review of the historical development of the study of self-focusing and nonlinear light propagation and its impact on the design of large, Nd-glass lasers for fusion research. No claim to completeness is made, but we feel that the enclosed summary does not miss many of the major developments in the field

  6. Propagation and wavefront ambiguity of linear nondiffracting beams

    Science.gov (United States)

    Grunwald, R.; Bock, M.

    2014-02-01

    Ultrashort-pulsed Bessel and Airy beams in free space are often interpreted as "linear light bullets". Usually, interconnected intensity profiles are considered a "propagation" along arbitrary pathways which can even follow curved trajectories. A more detailed analysis, however, shows that this picture gives an adequate description only in situations which do not require to consider the transport of optical signals or causality. To also cover these special cases, a generalization of the terms "beam" and "propagation" is necessary. The problem becomes clearer by representing the angular spectra of the propagating wave fields by rays or Poynting vectors. It is known that quasi-nondiffracting beams can be described as caustics of ray bundles. Their decomposition into Poynting vectors by Shack-Hartmann sensors indicates that, in the frame of their classical definition, the corresponding local wavefronts are ambiguous and concepts based on energy density are not appropriate to describe the propagation completely. For this reason, quantitative parameters like the beam propagation factor have to be treated with caution as well. For applications like communication or optical computing, alternative descriptions are required. A heuristic approach based on vector field based information transport and Fourier analysis is proposed here. Continuity and discontinuity of far field distributions in space and time are discussed. Quantum aspects of propagation are briefly addressed.

  7. PROPAGATOR: a synchronous stochastic wildfire propagation model with distributed computation engine

    Science.gov (United States)

    D´Andrea, M.; Fiorucci, P.; Biondi, G.; Negro, D.

    2012-04-01

    PROPAGATOR is a stochastic model of forest fire spread, useful as a rapid method for fire risk assessment. The model is based on a 2D stochastic cellular automaton. The domain of simulation is discretized using a square regular grid with cell size of 20x20 meters. The model uses high-resolution information such as elevation and type of vegetation on the ground. Input parameters are wind direction, speed and the ignition point of fire. The simulation of fire propagation is done via a stochastic mechanism of propagation between a burning cell and a non-burning cell belonging to its neighbourhood, i.e. the 8 adjacent cells in the rectangular grid. The fire spreads from one cell to its neighbours with a certain base probability, defined using vegetation types of two adjacent cells, and modified by taking into account the slope between them, wind direction and speed. The simulation is synchronous, and takes into account the time needed by the burning fire to cross each cell. Vegetation cover, slope, wind speed and direction affect the fire-propagation speed from cell to cell. The model simulates several mutually independent realizations of the same stochastic fire propagation process. Each of them provides a map of the area burned at each simulation time step. Propagator simulates self-extinction of the fire, and the propagation process continues until at least one cell of the domain is burning in each realization. The output of the model is a series of maps representing the probability of each cell of the domain to be affected by the fire at each time-step: these probabilities are obtained by evaluating the relative frequency of ignition of each cell with respect to the complete set of simulations. Propagator is available as a module in the OWIS (Opera Web Interfaces) system. The model simulation runs on a dedicated server and it is remote controlled from the client program, NAZCA. Ignition points of the simulation can be selected directly in a high-resolution, three

  8. Long-distance transmission of light in a scintillator-based radiation detector

    Science.gov (United States)

    Dowell, Jonathan L.; Talbott, Dale V.; Hehlen, Markus P.

    2017-07-11

    Scintillator-based radiation detectors capable of transmitting light indicating the presence of radiation for long distances are disclosed herein. A radiation detector can include a scintillator layer and a light-guide layer. The scintillator layer is configured to produce light upon receiving incident radiation. The light-guide layer is configured to receive light produced by the scintillator layer and either propagate the received light through the radiation detector or absorb the received light and emit light, through fluorescence, that is propagated through the radiation detector. A radiation detector can also include an outer layer partially surrounding the scintillator layer and light-guide layer. The index of refraction of the light-guide layer can be greater than the index of refraction of adjacent layers.

  9. Radio Wave Propagation Handbook for Communication on and Around Mars

    Science.gov (United States)

    Ho, Christian; Golshan, Nasser; Kliore, Arvydas

    2002-01-01

    This handbook examines the effects of the Martian environment on radio wave propagation on Mars and in the space near the planet. The environmental effects include these from the Martian atmosphere, ionosphere, global dust storms, aerosols, clouds, and geomorphologic features. Relevant Martian environmental parameters were extracted from the measurements of Mars missions during the past 30 years, especially from Mars Pathfinder and Mars Global Surveyor. The results derived from measurements and analyses have been reviewed through an extensive literature search. The updated parameters have been theoretically analyzed to study their effects on radio propagation. This handbook also provides basic information about the entire telecommunications environment on and around Mars for propagation researchers, system engineers, and link analysts. Based on these original analyses, some important recommendations have been made, including the use of the Martian ionosphere as a reflector for Mars global or trans-horizon communication between future Martian colonies, reducing dust storm scattering effects, etc. These results have extended our wave propagation knowledge to a planet other than Earth; and the tables, models, and graphics included in this handbook will benefit telecommunication system engineers and scientific researchers.

  10. Optical vortex propagation in few-mode rectangular polymer waveguides

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir S.; Chipouline, Arkadi; Zywietz, Urs

    2017-01-01

    We demonstrate that rectangular few-mode dielectric waveguides, fabricated with standard lithographic technique, can support on-chip propagation of optical vortices. We show that specific superpositions of waveguide eigenmodes form quasi-degenerate modes carrying light with high purity states...

  11. Two-stream instability for a light ion beam-plasma system with external magnetic field

    International Nuclear Information System (INIS)

    Okada, T.; Tazawa, H.

    1992-12-01

    For inertial confinement fusion, a focused light ion beam (LIB) is required to propagate stably through a chamber to a target. We have pointed out that the applied external magnetic field is important for LIB propagation. To investigate the influence of the external magnetic field on the LIB propagation, we analysed the electrostatic dispersion relation of magnetized light ion beam-plasma system. The particle in-cell (PIC) simulation results are presented for a light ion beam-plasma system with external magnetic field. (author)

  12. Nonlinear propagation of a spatially incoherent laser beam: self-induced smoothing and reduction of scattering instabilities

    International Nuclear Information System (INIS)

    Maximov, A.V.; Ourdev, I.G.; Rozmus, W.; Capjack, C.E.; Mounaix, Ph.; Huller, S.; Pesme, D.; Tikhonchuk, V.T.; Divol, L.

    2000-01-01

    It is shown that plasma-induced angular spreading and spectral broadening of a spatially incoherent laser beam correspond to increased spatial and temporal incoherence of the laser light. The spatial incoherence is characterized by an effective beam f-number, decreasing in space along the direction of light propagation. Plasma-induced beam smoothing can influence laser-plasma interaction physics. In particular, decreasing the correlation time of the propagating laser light may dramatically reduce the levels of backward stimulated Brillouin and Raman scattering inside the plasma. Also, the decrease of the laser beam effective f-number reduces the reflectivity of backward stimulated Brillouin scattering. (authors)

  13. Photon mass drag and the momentum of light in a medium

    DEFF Research Database (Denmark)

    Partanen, Mikko; Häyrynen, Teppo; Oksanen, Jani

    2017-01-01

    Conventional theories of electromagnetic waves in a medium assume that the energy propagating with the light pulse in the medium is entirely carried by the field. Thus, the possibility that the optical force field of the light pulse would drive forward an atomic mass density wave (MDW...... field. We show that a light pulse having a total electromagnetic energy (h) over bar omega propagating in a nondispersive medium transfers a mass equal to delta m = (n(2) - 1) (h) over bar omega/c(2), where n is the refractive index. MDW, which carries this mass, consists of atoms, which are more......) and the related kinetic and elastic energies is neglected. In this work, we present foundations of a covariant theory of light propagation in a medium by considering a light wave simultaneously with the dynamics of the medium atoms driven by optoelastic forces between the induced dipoles and the electromagnetic...

  14. 76 FR 66333 - Carolina Power & Light Company, H.B. Robinson Steam Electric Plant, Unit No. 2; Environmental...

    Science.gov (United States)

    2011-10-26

    ... NUCLEAR REGULATORY COMMISSION [Docket No. 50-261; NRC-2011-0247] Carolina Power & Light Company, H.B. Robinson Steam Electric Plant, Unit No. 2; Environmental Assessment and Finding of No Significant... Facility Operating License No. DPR-23, issued to Carolina Power & Light Company (the licensee), for...

  15. 77 FR 7142 - Jersey Central Power and Light Company, PSEG Fossil, LLC; Notice of Availability of Environmental...

    Science.gov (United States)

    2012-02-10

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 2309-019] Jersey Central Power and Light Company, PSEG Fossil, LLC; Notice of Availability of Environmental Assessment In accordance with the National Environmental Policy Act of 1969 and the Federal Energy Regulatory Commission's...

  16. Environmentally friendly inhibition of pathogenic bacteria and algae propagation due phthalocyanine agents

    International Nuclear Information System (INIS)

    Rihova Ambrozova, J.; Bezdekova, E.; Louckova, E.; Nekovarova, J.

    2007-01-01

    From 2004, in the laboratory of The Institute of Chemical Technology in Prague is being solved the project FT-TA/034 'Environmentally friendly inhibition of pathogenic bacteria and algae propagation in the circulatory cooling systems of nuclear power stations and in other similar technological facilities' to determine effects of phthalocyanine agents. The project bearer is VUOS, Inc. in Rybitvi (Research Institute for Organic Synthesis Inc.), where are the new phthalocyanines synthesized. The aimed goal of the research is environmentally friendly liquidation of bacteria and algae by means of photodynamic generated singlet oxygen through impact of solar radiation in the circulation cooling waters of various technical and technological systems. The principle of the problem outlined is the applying of phthalocyanine agents on samples of pure bacterial, anabaenas and algae cultures to estimate the inhibition effect on the organism exposed. In the course of solution, it is assumed that in such way conducted inhibition of bacteria, anabaenas and algae as well of their proliferation would replace routinely used bactericidal and algicidal preparations, which demand permanent dosing into circulating waters or perhaps from time to time an application of shocking doses. The particular algicidal and bactericidal agents represents in this case in situ emerging singlet oxygen, that is harmless to water biocenoses and whose presence in the water is no reason to ban the outflow of waters treated in such a way into water streams. The goal should be also a direct estimation of the effect those agents on cooling waters samples e. g. from the nuclear power plant systems. The purpose of the tests performance is also elimination of filamentous green algae, emerging in the systems cooling towers. The applied preparations are not toxic and do not burden the living environment, they contain no substances interacting with surface materials of structures in the circulatory cooling circuit

  17. The effect of elimination of environmental light on the metabolism of unconjugated bilirubin in the Gunn rat

    International Nuclear Information System (INIS)

    Zenone, E.A.; Stoll, M.S.; Ostrow, J.D.

    1982-01-01

    In the homozygous jaundiced Gunn rat, bilirubin catabolism is augmented by intense illumination (phototherapy) and by induction of microsomal cytochrome P448. To assess the relative importance of less intense environmental light versus intrinsic mechanisms in the maintenance of bilirubin turnover, Gunn rats were kept for three weeks under either ordinary laboratory lighting (0.3-0.8 mW/cm2, wavelength range 400-600 nm) or in absolute darkness. No differences in plasma concentration, miscible pool, turnover of bilirubin, or in hepatic cytochrome P448 activity were noted between the two groups over this period. A greater than twofold increase in the biliary excretion of unconjugated bilirubin was noted in the animals maintained under light, but this represented only 2% of total bilirubin turnover. These results suggest that intrinsic(enzymatic .) pathways are of primary importance in the maintenance of bilirubin metabolism in the glucuronyltransferase-deficient state under ordinary levels of environmental light

  18. Predicting plant performance under simultaneously changing environmental conditions – the interplay between temperature, light and internode growth

    Directory of Open Access Journals (Sweden)

    Katrin eKahlen

    2015-12-01

    Full Text Available Plant performance is significantly influenced by prevailing light and temperature conditions during plant growth and development. For plants exposed to natural fluctuations in abiotic environmental conditions it is however laborious and cumbersome to experimentally assign any contribution of individual environmental factors to plant responses. This study aimed at analyzing the interplay between light, temperature and internode growth based on model approaches. We extended the light-sensitive virtual plant model L-Cucumber by implementing a common Arrhenius function for appearance rates, growth rates and growth durations. For two greenhouse experiments, the temperature-sensitive model approach resulted in a precise prediction of cucumber mean internode lengths and number of internodes, as well as in accurately predicted patterns of individual internode lengths along the main stem. In addition, a system’s analysis revealed that environmental data averaged over the experimental period were not necessarily related to internode performance. Finally, the need for a species-specific parameterization of the temperature response function and related aspects in modelling temperature effects on plant development and growth is discussed.

  19. Theory of disorder-induced coherent scattering and light localization in slow-light photonic crystal waveguides

    International Nuclear Information System (INIS)

    Patterson, M; Hughes, S

    2010-01-01

    We introduce a theoretical formalism to describe disorder-induced extrinsic scattering in slow light photonic crystal waveguides. This work details and extends the optical scattering theory used in a recent issue of Physics Review Letters (Patterson et al 2009 Phys. Rev. Lett. 102 253903) to describe coherent scattering phenomena and successfully explain related experimental measurements. Our presented theory, which combines Green function and coupled mode methods, allows us to self-consistently account for arbitrary multiple scattering for the propagating electric field and recover experimental features such as resonances near the band edge. The technique is fully three-dimensional and can calculate the effects of disorder on the propagating field over thousands of unit cells. As an application of this theory, we explore various sample lengths and disordered instances, and demonstrate the profound effect of multiple scattering in the waveguide transmission. The spectra yield rich features associated with disorder-induced localization and multiple scattering, which are shown to be exacerbated in the slow light propagation regime

  20. Research on the speed of light transmission in a dual-frequency laser pumped single fiber with two directions

    Science.gov (United States)

    Qiu, Wei; Liu, Jianjun; Wang, Yuda; Yang, Yujing; Gao, Yuan; Lv, Pin; Jiang, Qiuli

    2018-01-01

    In this article a general theory of the coherent population oscillation effect in an erbium-doped fiber at room temperature is presented. We use dual pumping light waves with a simplified two-level system. Thus the time delay equations can be calculated from rate equations and the transmission equation. Using numerical simulation, in the case of dual-frequency pump light waves (1480 nm and 980 nm) with two directions, we analyze the influence of the pump power ratio on the group speed of light propagation. In addition, we compare slow light propagation with a single-pumping light and slow light propagation with a dual-pumping light at room temperature. The discussion shows that a larger time delay of slow light propagation can be obtained with a dual-frequency pumping laser. Compared to previous research methods, a dual-frequency laser pumped fiber with two directions is more controllable. Moreover, we conclude that the group velocity of light can be varied by changing the pump ratio.

  1. A Workflow-Oriented Approach To Propagation Models In Heliophysics

    Directory of Open Access Journals (Sweden)

    Gabriele Pierantoni

    2014-01-01

    Full Text Available The Sun is responsible for the eruption of billions of tons of plasma andthe generation of near light-speed particles that propagate throughout the solarsystem and beyond. If directed towards Earth, these events can be damaging toour tecnological infrastructure. Hence there is an effort to understand the causeof the eruptive events and how they propagate from Sun to Earth. However, thephysics governing their propagation is not well understood, so there is a need todevelop a theoretical description of their propagation, known as a PropagationModel, in order to predict when they may impact Earth. It is often difficultto define a single propagation model that correctly describes the physics ofsolar eruptive events, and even more difficult to implement models capable ofcatering for all these complexities and to validate them using real observational data.In this paper, we envisage that workflows offer both a theoretical andpractical framerwork for a novel approach to propagation models. We definea mathematical framework that aims at encompassing the different modalitieswith which workflows can be used, and provide a set of generic building blockswritten in the TAVERNA workflow language that users can use to build theirown propagation models. Finally we test both the theoretical model and thecomposite building blocks of the workflow with a real Science Use Case that wasdiscussed during the 4th CDAW (Coordinated Data Analysis Workshop eventheld by the HELIO project. We show that generic workflow building blocks canbe used to construct a propagation model that succesfully describes the transitof solar eruptive events toward Earth and predict a correct Earth-impact time

  2. Industrial Ecology and Environmental Lean Management: Lights and Shadows

    Directory of Open Access Journals (Sweden)

    Giuseppe Ioppolo

    2014-09-01

    Full Text Available Current industrial production is driven by increasing globalization, which has led to a steady increase in production volumes and complexity of products aimed at the pursuit of meeting the needs of customers. In this context, one of the main tools in the management of customer value is Lean Manufacturing or Production, though it is considered primarily as a set of tools to reduce the total cost of the resources needed to achieve such needs. This philosophy has recently been enriched in the literature with case studies that link Lean Management (LM with the improvement of environmental sustainability. The consequence is an expansion of the Computer Integrated Manufacturing (CIM; indeed, CIM, currently, combining and integrating the key business functions (e.g., business, engineering, manufacturing, and information management with a view of the life cycle, does not highlight the strategic role of the environmental aspects. In order to deal with the increasingly rapid environmental degradation that is reflected in society, in terms of both economy and quality of life, Industrial Ecology (IE introduced a new paradigm of principles and instruments of analysis and decision support (e.g., Life Cycle Assessment—LCA, Social Life Cycle Assessment -SLCA, Material Flow Account—MFA, etc. that can be considered as the main basis for integrating the environmental aspects in each strategy, design, production, final product, and end of life management, through the re-engineering of processes and activities towards the development of an eco-industrial system. This paper presents the preliminary observations based on a analysis of both theories (LM-IE and provides a possible assessment of the key factors relevant to their integration in a “lean environmental management”, highlighting both positives (lights and possible barriers (shadows.

  3. Light-front zero-mode contribution to the Ward Identity

    International Nuclear Information System (INIS)

    Sales, J.H.O.; Suzuki, A.T.

    2010-01-01

    In a covariant gauge we implicitly assume that the Green's function propagates information from one point of the space-time to another, so that the Green's function is responsible for the dynamics of the relativistic particle. In the light front form one would naively expect that this feature would be preserved. In this manner, the fermionic field propagator can be split into a propagating piece and a non-propagating ('contact') term. Since the latter ('contact') one does not propagate information, and therefore, supposedly can be discarded with no harm to the field dynamics we wanted to know what would be the impact of dropping it off. To do that, we investigated its role in the Ward identity in the light front. Here we use the terminology Ward identity to identify the limiting case of photon's zero momentum transfer in the vertex from the more general Ward-Takahashi identity with nonzero momentum transfer.

  4. Nonlinear magneto-optical rotation with modulated light in tilted magnetic fields

    International Nuclear Information System (INIS)

    Pustelny, S.; Gawlik, W.; Rochester, S. M.; Kimball, D. F. Jackson; Yashchuk, V. V.; Budker, D.

    2006-01-01

    Larmor precession of laser-polarized atoms contained in antirelaxation-coated cells, detected via nonlinear magneto-optical rotation (NMOR), is a promising technique for a new generation of ultrasensitive atomic magnetometers. For magnetic fields directed along the light propagation direction, resonances in NMOR appear when linearly polarized light is frequency or amplitude modulated at twice the Larmor frequency. Because the frequency of these resonances depends on the magnitude but not the direction of the field, they are useful for scalar magnetometry. Additional NMOR resonances at the Larmor frequency appear when the magnetic field is tilted away from the light propagation direction in the plane defined by the light propagation and polarization vectors. These resonances, studied both experimentally and with a density matrix calculation in the present work, offer a convenient method of achieving additional information about a direction of the magnetic field

  5. The finite element model for the propagation of light in scattering media: a direct method for domains with nonscattering regions.

    Science.gov (United States)

    Arridge, S R; Dehghani, H; Schweiger, M; Okada, E

    2000-01-01

    We present a method for handling nonscattering regions within diffusing domains. The method develops from an iterative radiosity-diffusion approach using Green's functions that was computationally slow. Here we present an improved implementation using a finite element method (FEM) that is direct. The fundamental idea is to introduce extra equations into the standard diffusion FEM to represent nondiffusive light propagation across a nonscattering region. By appropriate mesh node ordering the computational time is not much greater than for diffusion alone. We compare results from this method with those from a discrete ordinate transport code, and with Monte Carlo calculations. The agreement is very good, and, in addition, our scheme allows us to easily model time-dependent and frequency domain problems.

  6. Average intensity and spreading of partially coherent model beams propagating in a turbulent biological tissue

    International Nuclear Information System (INIS)

    Wu, Yuqian; Zhang, Yixin; Wang, Qiu; Hu, Zhengda

    2016-01-01

    For Gaussian beams with three different partially coherent models, including Gaussian-Schell model (GSM), Laguerre-Gaussian Schell-model (LGSM) and Bessel-Gaussian Schell-model (BGSM) beams propagating through a biological turbulent tissue, the expression of the spatial coherence radius of a spherical wave propagating in a turbulent biological tissue, and the average intensity and beam spreading for GSM, LGSM and BGSM beams are derived based on the fractal model of power spectrum of refractive-index variations in biological tissue. Effects of partially coherent model and parameters of biological turbulence on such beams are studied in numerical simulations. Our results reveal that the spreading of GSM beams is smaller than LGSM and BGSM beams on the same conditions, and the beam with larger source coherence width has smaller beam spreading than that with smaller coherence width. The results are useful for any applications involved light beam propagation through tissues, especially the cases where the average intensity and spreading properties of the light should be taken into account to evaluate the system performance and investigations in the structures of biological tissue. - Highlights: • Spatial coherence radius of a spherical wave propagating in a turbulent biological tissue is developed. • Expressions of average intensity and beam spreading for GSM, LGSM and BGSM beams in a turbulent biological tissue are derived. • The contrast for the three partially coherent model beams is shown in numerical simulations. • The results are useful for any applications involved light beam propagation through tissues.

  7. Quark chiral condensate from the overlap quark propagator

    Science.gov (United States)

    Wang, Chao; Bi, Yujiang; Cai, Hao; Chen, Ying; Gong, Ming; Liu, Zhaofeng

    2017-05-01

    From the overlap lattice quark propagator calculated in the Landau gauge, we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data. The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with N f = 2+1 flavors. Three ensembles with different light sea quark masses are used at one lattice spacing 1/a = 1.75(4) GeV. We obtain in the SU(2) chiral limit. Supported by National Natural Science Foundation of China (11575197, 11575196, 11335001, 11405178), joint funds of NSFC (U1632104, U1232109), YC and ZL acknowledge the support of NSFC and DFG (CRC110)

  8. 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.)

  9. The optics of gyrotropic crystals in the field of two counter-propagating ultrasound waves

    International Nuclear Information System (INIS)

    Gevorgyan, A H; Harutyunyan, E M; Hovhannisyan, M A; Matinyan, G K

    2014-01-01

    We consider oblique light propagation through a layer of a gyrotropic crystal in the field of two counter-propagating ultrasound waves. The problem is solved by Ambartsumyan's layer addition modified method. The results of the reflection spectra for different values of the problem parameters are presented. The possibilities of such system applications are discussed.

  10. Quantifying light pollution

    International Nuclear Information System (INIS)

    Cinzano, P.; Falchi, F.

    2014-01-01

    In this paper we review new available indicators useful to quantify and monitor light pollution, defined as the alteration of the natural quantity of light in the night environment due to introduction of manmade light. With the introduction of recent radiative transfer methods for the computation of light pollution propagation, several new indicators become available. These indicators represent a primary step in light pollution quantification, beyond the bare evaluation of the night sky brightness, which is an observational effect integrated along the line of sight and thus lacking the three-dimensional information. - Highlights: • We review new available indicators useful to quantify and monitor light pollution. • These indicators are a primary step in light pollution quantification. • These indicators allow to improve light pollution mapping from a 2D to a 3D grid. • These indicators allow carrying out a tomography of light pollution. • We show an application of this technique to an Italian region

  11. 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.

  12. Propagation of ultrashort laser pulses in water: linear absorption and onset of nonlinear spectral transformation.

    Science.gov (United States)

    Sokolov, Alexei V; Naveira, Lucas M; Poudel, Milan P; Strohaber, James; Trendafilova, Cynthia S; Buck, William C; Wang, Jieyu; Strycker, Benjamin D; Wang, Chao; Schuessler, Hans; Kolomenskii, Alexandre; Kattawar, George W

    2010-01-20

    We study propagation of short laser pulses through water and use a spectral hole filling technique to essentially perform a sensitive balanced comparison of absorption coefficients for pulses of different duration. This study is motivated by an alleged violation of the Bouguer-Lambert-Beer law at low light intensities, where the pulse propagation is expected to be linear, and by a possible observation of femtosecond optical precursors in water. We find that at low intensities, absorption of laser light is determined solely by its spectrum and does not directly depend on the pulse duration, in agreement with our earlier work and in contradiction to some work of others. However, as the laser fluence is increased, interaction of light with water becomes nonlinear, causing energy exchange among the pulse's spectral components and resulting in peak-intensity dependent (and therefore pulse-duration dependent) transmission. For 30 fs pulses at 800 nm center wavelength, we determine the onset of nonlinear propagation effects to occur at a peak value of about 0.12 mJ/cm(2) of input laser energy fluence.

  13. 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;

  14. Ultrashort pulse-propagation effects in a semiconductor optical amplifier: Microscopic theory and experiment

    DEFF Research Database (Denmark)

    Hughes, S.; Borri, P.; Knorr, A.

    2001-01-01

    We present microscopic modeling and experimental measurements of femtosecond-pulse interactions in a semiconductor optical amplifier. Two novel nonlinear propagation effects are demonstrated: pulse breakup in the gain regime and pulse compression in the transparency regime. These propagation phen...... phenomena highlight the microscopic origin and important role of adiabatic following in semiconductor optical amplifiers. Fundamental light-matter interactions are discussed in detail and possible applications are highlighted....

  15. Alternative modes for optical trapping and manipulation using counter-propagating shaped beams

    International Nuclear Information System (INIS)

    Palima, D; Tauro, S; Glückstad, J; Lindballe, T B; Kristensen, M V; Stapelfeldt, H; Keiding, S R

    2011-01-01

    Counter-propagating beams have enabled the first stable three-dimensional optical trapping of microparticles and this procedure has been enhanced and developed over the years to achieve independent and interactive manipulation of multiple particles. In this work, we analyse counter-propagating shaped-beam traps that depart from the conventional geometry based on symmetric, coaxial counter-propagating beams. We show that projecting shaped beams with separation distances previously considered axially unstable can, in fact, enhance the axial and transverse trapping stiffnesses. We also show that deviating from using perfectly counter-propagating beams to use oblique beams can improve the axial stability of the traps and improve the axial trapping stiffness. These alternative geometries can be particularly useful for handling larger particles. These results hint at a rich potential for light shaping for optical trapping and manipulation using patterned counter-propagating beams, which still remains to be fully tapped

  16. A Consideration for the Light Environmental Modeling under Tropical Rainforest Canopies

    Science.gov (United States)

    Yoshimura, M.; Yamashita, M.

    2014-09-01

    Photosynthetic Active Radiation (PAR) is the most important light source for plant photosynthesis. It is known that most of PAR from solar radiation is well absorbed by the surface. The canopy is the surface in forest region, consists an aboveground portion of plant community and formed by plant crowns. On the other hand, incident solar radiation is fluctuating at all times because of fluctuating sky conditions. Therefore, qualitative light environmental measurements in forest are recommended to execute under stable cloudy condition. In fact, it is quite a few opportunities to do under this sky condition. It means that the diffuse light condition without the direct light is only suitable for this measurement. In this study, we challenged the characterization the forest light environment as its representativeness under no consideration of sky conditions through analysis huge quantities of instantaneous data which obtained under the different sky conditions. All examined data were obtained under the different sky conditions at the tropical rainforest canopy as one of the typical fluctuating sky conditions regions. An incident PAR is transmitted and scattered by different forest layers at different heights. Various PAR data were measured with quantum units as Photosynthetic Photon Flux Density (PPFD) at different forest heights by the quantum sensors. By comparing PPFDs at different heights with an incident PPFD, relative PPFDs were calculated, which indicate the degree of PPFD decrease from the canopy top to lower levels. As the results of these considerations, daily averaging is confirmed to be cancelled sky fluctuating influences.

  17. Consistency questions in the light cone gauge based on equal time commutation rules

    International Nuclear Information System (INIS)

    Haller, K.

    1989-01-01

    We investigate whether time displacement invariant propagators are compatible canonical formulations in the light cone gauge based on equal time commutation rules. We conclude that, in the light cone gauge, time displacement invariant propagators are not consistent with the requirement that, in canonical formulations of gauge theories, only transversely polarized, massless gauge field excitations (photons, or gluons in perturbative QCD), can contribute to the transverse part of a time displacement invariant propagator. When the time displacement invariant light cone gauge propagator is represented as a four-dimensional momentum space Fourier integral the following is observed: Transverse parts of the propagator obtain time displacement invariant contributions from the (k 3 -k 0 ) pole, as well as from the (vertical strokekvertical stroke 2 -k 0 2 ) pole. But since, in the Schroedinger picture (i.e. at t=0), the divergence-free part of the gauge field consists of transversely polarized gauge field excitations only, the transverse part of the propagator either can have time displacement invariant time dependence determined by the (vertical strokekvertical stroke 2 -k 0 2 ) pole; or, if any part of the transverse propagator has time dependence determined by the (k 3 -k 0 ) pole, it cannot be time displacement invariant. (orig.)

  18. Twisted-Light-Ion Interaction: The Role of Longitudinal Fields

    Science.gov (United States)

    Quinteiro, G. F.; Schmidt-Kaler, Ferdinand; Schmiegelow, Christian T.

    2017-12-01

    The propagation of light beams is well described using the paraxial approximation, where field components along the propagation direction are usually neglected. For strongly inhomogeneous or shaped light fields, however, this approximation may fail, leading to intriguing variations of the light-matter interaction. This is the case of twisted light having opposite orbital and spin angular momenta. We compare experimental data for the excitation of a quadrupole transition in a single trapped 40Ca+ ion from Schmiegelow et al. [Nat. Commun. 7, 12998 (2016), 10.1038/ncomms12998] with a complete model where longitudinal components of the electric field are taken into account. Our model matches the experimental data and excludes by 11 standard deviations the approximation of a complete transverse field. This demonstrates the relevance of all field components for the interaction of twisted light with matter.

  19. A finite element beam propagation method for simulation of liquid crystal devices.

    Science.gov (United States)

    Vanbrabant, Pieter J M; Beeckman, Jeroen; Neyts, Kristiaan; James, Richard; Fernandez, F Anibal

    2009-06-22

    An efficient full-vectorial finite element beam propagation method is presented that uses higher order vector elements to calculate the wide angle propagation of an optical field through inhomogeneous, anisotropic optical materials such as liquid crystals. The full dielectric permittivity tensor is considered in solving Maxwell's equations. The wide applicability of the method is illustrated with different examples: the propagation of a laser beam in a uniaxial medium, the tunability of a directional coupler based on liquid crystals and the near-field diffraction of a plane wave in a structure containing micrometer scale variations in the transverse refractive index, similar to the pixels of a spatial light modulator.

  20. Beam propagation in Cu +-Na + ion exchange channel waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Villegas Vicencio, L. J.; Khomenko, A. V.; Salazar, D.; Marquez, H. [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Baja California (Mexico); Porte, H. [Universite de Franche-Comte, UFR des Sciences et Techniques, Besancon, Cedex (France)

    2001-06-01

    We employ the fast Fourier transform beam propagation method to simulate the propagation of light in graded index channel waveguides, these have been obtained by solid state diffusion of copper ions in soda-lime glass substrates. Longitudinal propagation has been simulated, the input light beam has a gaussian profile. Two cases have been analyzed, in the first, the Gaussian beam is collinear center to center with respect to waveguide; in the second, a small lateral offset and angular tilt have been introduced. Modal beating and bending effects have been founded. We have proven the validity of our numerical results in detailed comparison with experimental data. [Spanish] Se ha empleado el metodo de propagacion de haces por la transformada rapida de Fourier para simular la propagacion de la luz en guias de onda de indice de gradiente. Estas han sido fabricadas por difusion de iones de cobre en estado solido en substratos de vidrios sodicos-calcicos. Se han simulado dos casos, el primero, el perfil de luz de entrada, que es gaussiano, es colineal centro a centro respecto al centro de la guia de ondas: el segundo, se ha dado un pequeno corrimiento lateral y una inclinacion angular. Como consecuencia de los casos anteriores se ha observado efectos de batimiento modal. Los resultados de la simulacion se han validado con resultados experimentales.

  1. Tunable light source for fiber optic lighting applications

    Science.gov (United States)

    Narendran, Nadarajah; Bierman, Andrew; Finney, Mark J.; Edwards, Ian K.

    1997-09-01

    This paper examines the possibility of tuning the lamp spectrum to compensate for color distortions in fiber optic lighting systems. Because most optical fibers have strong absorption in the blue and red wavelength regions, white light entering and propagating down an optical fiber suffers varied amounts of attenuation as a function of wavelength. As a result, the light exiting the optical fiber has a greenish tint that the lighting design community considers undesirable in interior lighting applications. HID lamps are commonly used for the light source in this industry. Certain classes of HID lamps tend to shift in color when their operating position or the input voltage to the lamp is changed. An experimental study is being conducted to characterize the color shift properties of a small HID lamp as a function of tilt and input voltage. The study also examines the possibility of exploiting this color shift to compensate for the color distortions caused by optical fibers. The details of the experiment and the results are presented in this manuscript.

  2. Junction Propagation in Organometal Halide Perovskite-Polymer Composite Thin Films.

    Science.gov (United States)

    Shan, Xin; Li, Junqiang; Chen, Mingming; Geske, Thomas; Bade, Sri Ganesh R; Yu, Zhibin

    2017-06-01

    With the emergence of organometal halide perovskite semiconductors, it has been discovered that a p-i-n junction can be formed in situ due to the migration of ionic species in the perovskite when a bias is applied. In this work, we investigated the junction formation dynamics in methylammonium lead tribromide (MAPbBr 3 )/polymer composite thin films. It was concluded that the p- and n- doped regions propagated into the intrinsic region with an increasing bias, leading to a reduced intrinsic perovskite layer thickness and the formation of an effective light-emitting junction regardless of perovskite layer thicknesses (300 nm to 30 μm). The junction propagation also played a major role in deteriorating the LED operation lifetime. Stable perovskite LEDs can be achieved by restricting the junction propagation after its formation.

  3. 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

  4. Analytical approach of laser beam propagation in the hollow polygonal light pipe.

    Science.gov (United States)

    Zhu, Guangzhi; Zhu, Xiao; Zhu, Changhong

    2013-08-10

    An analytical method of researching the light distribution properties on the output end of a hollow n-sided polygonal light pipe and a light source with a Gaussian distribution is developed. The mirror transformation matrices and a special algorithm of removing void virtual images are created to acquire the location and direction vector of each effective virtual image on the entrance plane. The analytical method is demonstrated by Monte Carlo ray tracing. At the same time, four typical cases are discussed. The analytical results indicate that the uniformity of light distribution varies with the structural and optical parameters of the hollow n-sided polygonal light pipe and light source with a Gaussian distribution. The analytical approach will be useful to design and choose the hollow n-sided polygonal light pipe, especially for high-power laser beam homogenization techniques.

  5. 3D geometric modeling and simulation of laser propagation through turbulence with plenoptic functions

    Science.gov (United States)

    Wu, Chensheng; Nelson, William; Davis, Christopher C.

    2014-10-01

    Plenoptic functions are functions that preserve all the necessary light field information of optical events. Theoretical work has demonstrated that geometric based plenoptic functions can serve equally well in the traditional wave propagation equation known as the "scalar stochastic Helmholtz equation". However, in addressing problems of 3D turbulence simulation, the dominant methods using phase screen models have limitations both in explaining the choice of parameters (on the transverse plane) in real-world measurements, and finding proper correlations between neighboring phase screens (the Markov assumption breaks down). Though possible corrections to phase screen models are still promising, the equivalent geometric approach based on plenoptic functions begins to show some advantages. In fact, in these geometric approaches, a continuous wave problem is reduced to discrete trajectories of rays. This allows for convenience in parallel computing and guarantees conservation of energy. Besides the pairwise independence of simulated rays, the assigned refractive index grids can be directly tested by temperature measurements with tiny thermoprobes combined with other parameters such as humidity level and wind speed. Furthermore, without loss of generality one can break the causal chain in phase screen models by defining regional refractive centers to allow rays that are less affected to propagate through directly. As a result, our work shows that the 3D geometric approach serves as an efficient and accurate method in assessing relevant turbulence problems with inputs of several environmental measurements and reasonable guesses (such as Cn 2 levels). This approach will facilitate analysis and possible corrections in lateral wave propagation problems, such as image de-blurring, prediction of laser propagation over long ranges, and improvement of free space optic communication systems. In this paper, the plenoptic function model and relevant parallel algorithm computing

  6. Environmentally assisted cracking in light water reactors

    International Nuclear Information System (INIS)

    Chopra, O.K.; Chung, H.M.; Gruber, E.E.

    1996-07-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from April 1995 to December 1995. Topics that have been investigated include fatigue of carbon and low-alloy steel used in reactor piping and pressure vessels, EAC of Alloy 600 and 690, and irradiation-assisted stress corrosion cracking (IASCC) of Type 304 SS. Fatigue tests were conducted on ferritic steels in water that contained various concentrations of dissolved oxygen (DO) to determine whether a slow strain rate applied during different portions of a tensile-loading cycle are equally effective in decreasing fatigue life. Crack-growth-rate tests were conducted on compact-tension specimens from several heats of Alloys 600 and 690 in simulated LWR environments. Effects of fluoride-ion contamination on susceptibility to intergranular cracking of high- and commercial- purity Type 304 SS specimens from control-tensile tests at 288 degrees Centigrade. Microchemical changes in the specimens were studied by Auger electron spectroscopy and scanning electron microscopy to determine whether trace impurity elements may contribute to IASCC of these materials

  7. Propagation stability of self-reconstructing Bessel beams enables contrast-enhanced imaging in thick media.

    Science.gov (United States)

    Fahrbach, Florian O; Rohrbach, Alexander

    2012-01-17

    Laser beams that can self-reconstruct their initial beam profile even in the presence of massive phase perturbations are able to propagate deeper into inhomogeneous media. This ability has crucial advantages for light sheet-based microscopy in thick media, such as cell clusters, embryos, skin or brain tissue or plants, as well as scattering synthetic materials. A ring system around the central intensity maximum of a Bessel beam enables its self-reconstruction, but at the same time illuminates out-of-focus regions and deteriorates image contrast. Here we present a detection method that minimizes the negative effect of the ring system. The beam's propagation stability along one straight line enables the use of a confocal line principle, resulting in a significant increase in image contrast. The axial resolution could be improved by nearly 100% relative to the standard light-sheet techniques using scanned Gaussian beams, while demonstrating self-reconstruction also for high propagation depths.

  8. The use of public funds for environmental preservation and environmental education activities in the light of the Polish Supreme Audit Office reports

    Directory of Open Access Journals (Sweden)

    Maciej Serowaniec

    2018-03-01

    Full Text Available This article aims to present the assessment of the implementation of public funds provided under grant agreements for environmental preservation and environmental education activities in the light of the reports submitted by the Polish Supreme Audit Office (NIK. The areas covered by the audit were: the completeness and timeliness of the tasks defined in the agreements, the economy and legality of the use of the financial resources, the correctness of keeping financial and accounting records, and the preparation of reports and the settlement of funds.

  9. Light in flight photography and applications (Conference Presentation)

    Science.gov (United States)

    Faccio, Daniele

    2017-02-01

    The first successful attempts (Abramson) at capturing light in flight relied on the holographic interference between the ``object'' beam scattered from a screen and a short reference pulse propagating at an angle, acting as an ultrafast shutter cite{egg}. This interference pattern was recorded on a photographic plate or film and allowed the visualisation of light as it propagated through complex environments with unprecedented temporal and spatial resolution. More recently, advances in ultrafast camera technology and in particular the use of picosecond resolution streak cameras allowed the direct digital recording of a light pulse propagating through a plastic bottle (Rasker at el.). This represented a remarkable step forward as it provided the first ever video recording (in the traditional sense with which one intends a video, i.e. something that can be played back directly on a screen and saved in digital format) of a pulse of light in flight. We will discuss a different technology that is based on an imaging camera with a pixel array in which each individual pixel is a single photon avalanche diode (SPAD). SPADs offer both sensitivity to single photons and picosecond temporal resolution of the photon arrival time (with respect to a trigger event). When adding imaging capability, SPAD arrays can deliver videos of light pulse propagating in free space, without the need for a scattering medium or diffuser as in all previous work (Gariepy et al). This capability can then be harnessed for a variety of applications. We will discuss the details of SPAD camera detection of moving objects (e.g. human beings) that are hidden from view and then conclude with a discussion of future perspectives in the field of bio-imaging.

  10. Solar Lighting Technologies for Highway Green Rest Areas in China: Energy Saving Economic and Environmental Evaluation

    Directory of Open Access Journals (Sweden)

    Xiaochun Qin

    2015-01-01

    Full Text Available In this paper, taking Lushan West Sea highway green rest area in Jiangxi Province of China as the case study, the suitable types, applicability, advantages, and effective methods of solar lighting technologies for highway rest area were determined based on the analysis of characteristics of highway green rest area. It was proved that solar lighting technologies including the natural light guidance system, solar LED lighting, and maximizing natural light penetration were quite suitable for highway rest area in terms of lighting effects and energy and economic efficiency. The illuminance comparison of light guidance system with electrical lighting was made based on the on-site experiment. Also, the feasibility of natural light guidance system was well verified in terms of the lighting demand of the visitor centre in the rest area by the illuminance simulation analysis. The evaluation of the energy saving, economic benefits, and environmental effects of solar lighting technologies for highway rest area was, respectively, made in detail. It was proved that the application of solar technology for green lighting of highway rest facilities not only could have considerable energy saving capacity and achieve high economic benefits, but also make great contributions to the reduction of environment pollution.

  11. The Classical Pathways of Occipital Lobe Epileptic Propagation Revised in the Light of White Matter Dissection.

    Science.gov (United States)

    Latini, Francesco; Hjortberg, Mats; Aldskogius, Håkan; Ryttlefors, Mats

    2015-01-01

    The clinical evidences of variable epileptic propagation in occipital lobe epilepsy (OLE) have been demonstrated by several studies. However the exact localization of the epileptic focus sometimes represents a problem because of the rapid propagation to frontal, parietal, or temporal regions. Each white matter pathway close to the supposed initial focus can lead the propagation towards a specific direction, explaining the variable semiology of these rare epilepsy syndromes. Some new insights in occipital white matter anatomy are herein described by means of white matter dissection and compared to the classical epileptic patterns, mostly based on the central position of the primary visual cortex. The dissections showed a complex white matter architecture composed by vertical and longitudinal bundles, which are closely interconnected and segregated and are able to support specific high order functions with parallel bidirectional propagation of the electric signal. The same sublobar lesions may hyperactivate different white matter bundles reemphasizing the importance of the ictal semiology as a specific clinical demonstration of the subcortical networks recruited. Merging semiology, white matter anatomy, and electrophysiology may lead us to a better understanding of these complex syndromes and tailored therapeutic options based on individual white matter connectivity.

  12. The Classical Pathways of Occipital Lobe Epileptic Propagation Revised in the Light of White Matter Dissection

    Science.gov (United States)

    Latini, Francesco; Hjortberg, Mats; Aldskogius, Håkan; Ryttlefors, Mats

    2015-01-01

    The clinical evidences of variable epileptic propagation in occipital lobe epilepsy (OLE) have been demonstrated by several studies. However the exact localization of the epileptic focus sometimes represents a problem because of the rapid propagation to frontal, parietal, or temporal regions. Each white matter pathway close to the supposed initial focus can lead the propagation towards a specific direction, explaining the variable semiology of these rare epilepsy syndromes. Some new insights in occipital white matter anatomy are herein described by means of white matter dissection and compared to the classical epileptic patterns, mostly based on the central position of the primary visual cortex. The dissections showed a complex white matter architecture composed by vertical and longitudinal bundles, which are closely interconnected and segregated and are able to support specific high order functions with parallel bidirectional propagation of the electric signal. The same sublobar lesions may hyperactivate different white matter bundles reemphasizing the importance of the ictal semiology as a specific clinical demonstration of the subcortical networks recruited. Merging semiology, white matter anatomy, and electrophysiology may lead us to a better understanding of these complex syndromes and tailored therapeutic options based on individual white matter connectivity. PMID:26063964

  13. Light Beam Generation

    DEFF Research Database (Denmark)

    2007-01-01

    The invention relates to a method and a system for synthesizing a set of controllable light beams by provision of a system for synthesizing a set of light beams, comprising a spatially modulated light source for generation of electromagnetic radiation with a set of replicas of a predetermined......(x-xs, y-ys), a Fourier transforming lens for Fourier transforming the electromagnetic radiation, a first spatial light modulator for phase shifting the Fourier transformed electromagnetic radiation with the phase -F(u, v) of S*, S* is the complex conjugate of the Fourier transformed symbol s, a Fourier...... transforming lens for Inverse Fourier transforming the spatially modulated radiation, whereby a set of light beams are formed propagating through the inverse Fourier plane (x', y') at desired positions (x's, y's), and a controller for controlling the position of a replica of the symbol, s, for movement...

  14. Light propagation through the eye: numerical considerations and applications to presbylasik surgery analysis

    OpenAIRE

    Espinosa Tomás, Julián; Pérez Rodríguez, Jorge; Mas Candela, David; Illueca Contri, Carlos; Sala Pomares, Esperanza; Ortiz Márquez, Dolores; Alió y Sanz, Jorge L.

    2006-01-01

    Trabajo presentado en el 3rd European Meeting in Physiological Optics, London, September 7-9, 2006. Transmittance evaluation of cornea. Transmittance evaluation of crystalline lens. Wave propagation (angular spectrum) up to the plane of interest. Applications to presbylasik surgery analysis.

  15. Modeling the propagation of electromagnetic waves over the surface of the human body

    Science.gov (United States)

    Vendik, I. B.; Vendik, O. G.; Kirillov, V. V.; Pleskachev, V. V.; Tural'chuk, P. A.

    2016-12-01

    The results of modeling and an experimental study of electromagnetic (EM) waves in microwave range propagating along the surface of the human body have been presented. The parameters of wave propagation, such as the attenuation and phase velocity, have also been investigated. The calculation of the propagation of EM waves by the numerical method FDTD (finite difference time domain), as well as the use of the analytical model of the propagation of the EM wave along flat and curved surfaces has been fulfilled. An experimental study on a human body has been conducted. It has been shown that creeping waves are slow and exhibit a noticeable dispersion, while the surface waves are dispersionless and propagate at the speed of light in free space. A comparison of the results of numerical simulation, analytical calculation, and experimental investigations at a frequency of 2.55 GHz has been carried out.

  16. Light-scattering theory of diffraction.

    Science.gov (United States)

    Guo, Wei

    2010-03-01

    Since diffraction is a scattering process in principle, light propagation through one aperture in a screen is discussed in the light-scattering theory. Through specific calculation, the expression of the electric field observed at an observation point is obtained and is used not only to explain why Kirchhoff's diffraction theory is a good approximation when the screen is both opaque and sufficiently thin but also to demonstrate that the mathematical and physical problems faced by Kirchhoff's theory are avoided in the light-scattering theory.

  17. Control of Wave Propagation and Effect of Kerr Nonlinearity on Group Index

    International Nuclear Information System (INIS)

    Hazrat, Ali; Iftikhar, Ahmed; Ziauddin

    2013-01-01

    We use four-level atomic system and control the wave propagation via forbidden decay rate. The Raman gain process becomes dominant on electromagnetically induced transparency (EIT) medium by increasing the forbidden decay rate via increasing the number of atoms [G.S. Agarwal and T.N. Dey, Phys. Rev. A 74 (2006) 043805 and K. Harada, T. Kanbashi, and M. Mitsunaga, Phys. Rev. A 73 (2006) 013803]. The behavior of wave propagation is dramatically changed from normal (subluminal) to anomalous (superluminal) dispersion by increasing the forbidden decay rate. The system can also give a control over the group velocity of the light propagating through the medium via Kerr field. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  18. ''Heavy light bullets'' in electron-positron plasma

    International Nuclear Information System (INIS)

    Berezhiani, V.I.; Mahajan, S.M.

    1995-03-01

    The nonlinear propagation of circularly polarized electromagnetic waves with relativistically strong amplitudes in an unmagnetized hot electron-positron plasma with a small fraction of ions is investigated. The possibility of finding localized solutions in such a plasma is explored. It is shown that these plasmas support the propagation of ''heavy light bullets''; nondiffracting and nondispersive electromagnetic (EM) pulses with large density bunching. (author). 24 refs, 12 figs

  19. Collective behavior of light in vacuum

    Science.gov (United States)

    Briscese, Fabio

    2018-03-01

    Under the action of light-by-light scattering, light beams show collective behaviors in vacuum. For instance, in the case of two counterpropagating laser beams with specific initial helicity, the polarization of each beam oscillates periodically between the left and right helicity. Furthermore, the amplitudes and the corresponding intensities of each polarization propagate like waves. Such polarization waves might be observationally accessible in future laser experiments, in a physical regime complementary to those explored by particle accelerators.

  20. Partial coherence and imperfect optics at a synchrotron radiation source modeled by wavefront propagation

    Science.gov (United States)

    Laundy, David; Alcock, Simon G.; Alianelli, Lucia; Sutter, John P.; Sawhney, Kawal J. S.; Chubar, Oleg

    2014-09-01

    A full wave propagation of X-rays from source to sample at a storage ring beamline requires simulation of the electron beam source and optical elements in the beamline. The finite emittance source causes the appearance of partial coherence in the wave field. Consequently, the wavefront cannot be treated exactly with fully coherent wave propagation or fully incoherent ray tracing. We have used the wavefront code Synchrotron Radiation Workshop (SRW) to perform partially coherent wavefront propagation using a parallel computing cluster at the Diamond Light Source. Measured mirror profiles have been used to correct the wavefront for surface errors.

  1. Quantum control of light using electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Andre, A; Eisaman, M D; Walsworth, R L; Zibrov, A S; Lukin, M D

    2005-01-01

    We present an overview of recent theoretical and experimental work on the control of the propagation and quantum properties of light using electromagnetically induced transparency in atomic ensembles. Specifically, we discuss techniques for the generation and storage of few-photon quantum-mechanical states of light as well as novel approaches to manipulate weak pulses of light via enhanced nonlinear optical processes

  2. Light-cone observables and gauge-invariance in the geodesic light-cone formalism

    Energy Technology Data Exchange (ETDEWEB)

    Scaccabarozzi, Fulvio; Yoo, Jaiyul, E-mail: fulvio@physik.uzh.ch, E-mail: jyoo@physik.uzh.ch [Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich (Switzerland)

    2017-06-01

    The remarkable properties of the geodesic light-cone (GLC) coordinates allow analytic expressions for the light-cone observables, providing a new non-perturbative way for calculating the effects of inhomogeneities in our Universe. However, the gauge-invariance of these expressions in the GLC formalism has not been shown explicitly. Here we provide this missing part of the GLC formalism by proving the gauge-invariance of the GLC expressions for the light-cone observables, such as the observed redshift, the luminosity distance, and the physical area and volume of the observed sources. Our study provides a new insight on the properties of the GLC coordinates and it complements the previous work by the GLC collaboration, leading to a comprehensive description of light propagation in the GLC representation.

  3. Propagation Analysis for Wireless Sensor Networks Applied to Viticulture

    Directory of Open Access Journals (Sweden)

    Felipe Pinheiro Correia

    2017-01-01

    Full Text Available Wireless sensor networks have been proposed as a solution to obtain soil and environment information in large distributed areas. The main economic activity of the São Francisco Valley region in the Northeast of Brazil is the irrigated fruit production. The region is one of the major agricultural regions of the country. Grape plantations receive large investments and provide good financial return. However, the region still lacks electronic sensing systems to extract adequate information from plantations. Considering these facts, this paper presents a study of path loss in grape plantations for a 2.4 GHz operating frequency. In order to determine the position of the sensor nodes, the research dealt with various environmental factors that influence the intensity of the received signal. It has been noticed that main plantation aisles favor the guided propagation, and the vegetation along the secondary plantation aisles compromises the propagation. Diffraction over the grape trees is the main propagation mechanism in the diagonal propagation path. Transmission carried out above the vineyard showed that reflection on the top of the trees is the main mechanism.

  4. Light-Induced Reduction of Cuprous Oxide in an Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Cavalca, Filippo Carlo; Laursen, Anders Bo; Wagner, Jakob Birkedal

    2013-01-01

    Photocatalysts for solar fuel production are subject to intensive investigation as they constitute one viable route for solar energy harvesting. Cuprous oxide (Cu2O) is a working photocatalyst for hydrogen evolution but it photocorrodes upon light illumination in an aqueous environment....... Environmental transmission electron microscopy (ETEM) makes it possible to obtain insight into the local structure, composition and reactivity of catalysts in their working environment, which is of fundamental interest for sustainable energy research and is essential for further material optimization. Herein...

  5. Light propagation studies on laser modified waveguides using scanning near-field optical microscopy

    DEFF Research Database (Denmark)

    Borrise, X.; Berini, Abadal Gabriel; Jimenez, D.

    2001-01-01

    By means of direct laser writing on Al, a new method to locally modify optical waveguides is proposed. This technique has been applied to silicon nitride waveguides, allowing modifications of the optical propagation along the guide. To study the formed structures, a scanning near-held optical mic...

  6. Analyzing the Propagation Behavior of a Gaussian Laser Beam through Seawater and Comparing with Atmosphere

    Directory of Open Access Journals (Sweden)

    F Dabbagh Kashani

    2013-12-01

    Full Text Available Study of the beam propagation behavior through oceanic media is a challenging subject. In this paper, based on generalized Collins integral, the mean irradiance profile of Gaussian laser beam propagation through ocean is investigated. Power In Special Bucket (PIB is calculated. Using analytical expressions and calculating seawater transmission, the effects of absorption and scattering on beam propagation are studied. Based on these formulae, propagation in ocean and atmosphere are compared. The effects of some optical and environmental specifications, such as divergence angle and chlorophyll concentration in seawater on beam propagation by using mean irradiance, PIB and analytical formula of oceanic transmission are studied. The calculated results are shown graphically.

  7. Disordered resonant media: Self-induced transparency versus light localization

    Science.gov (United States)

    Novitsky, Denis V.

    2018-01-01

    We propose a concept of disordered resonant media, which are characterized by random variations of their parameters along the light propagation direction. In particular, a simple model of disorder considered in the paper implies random change of the density of active particles (two-level atoms). Within this model, the effect of disorder on self-induced transparency (SIT) is analyzed using numerical simulations of light pulse propagation through the medium. The transition from the SIT to localization regime is revealed as well as its dependence on the disorder level, atom density, medium thickness, and period of random variations.

  8. Light transport through the bandedge states of Fibonacci quasicrystals

    NARCIS (Netherlands)

    Dal Negro, Luca; Oton, Claudio J.; Gaburro, Zeno; Pavesi, Lorenzo; Johnson, Patrick; Lagendijk, Aart; Righini, Roberto; Colocci, Marcello; Wiersma, Diederik S.

    2003-01-01

    The propagation of light in nonperiodic quasicrystals is studied by ultrashort pulse interferometry. Samples consist of multilayer dielectric structures of the Fibonacci type and are realized from porous silicon. We observe mode beating and strong pulse stretching in the light transport through

  9. Applications of the Advanced Light Source to problems in the earth, soil, and environmental sciences report of the workshop

    International Nuclear Information System (INIS)

    1992-10-01

    This report discusses the following topics: ALS status and research opportunities; advanced light source applications to geological materials; applications in the soil and environmental sciences; x-ray microprobe analysis; potential applications of the ALS in soil and environmental sciences; and x-ray spectroscopy using soft x-rays: applications to earth materials

  10. Quasiparticle engineering and entanglement propagation in a quantum many-body system.

    Science.gov (United States)

    Jurcevic, P; Lanyon, B P; Hauke, P; Hempel, C; Zoller, P; Blatt, R; Roos, C F

    2014-07-10

    The key to explaining and controlling a range of quantum phenomena is to study how information propagates around many-body systems. Quantum dynamics can be described by particle-like carriers of information that emerge in the collective behaviour of the underlying system, the so-called quasiparticles. These elementary excitations are predicted to distribute quantum information in a fashion determined by the system's interactions. Here we report quasiparticle dynamics observed in a quantum many-body system of trapped atomic ions. First, we observe the entanglement distributed by quasiparticles as they trace out light-cone-like wavefronts. Second, using the ability to tune the interaction range in our system, we observe information propagation in an experimental regime where the effective-light-cone picture does not apply. Our results will enable experimental studies of a range of quantum phenomena, including transport, thermalization, localization and entanglement growth, and represent a first step towards a new quantum-optic regime of engineered quasiparticles with tunable nonlinear interactions.

  11. Propagation effects in the generation process of high-order vortex harmonics.

    Science.gov (United States)

    Zhang, Chaojin; Wu, Erheng; Gu, Mingliang; Liu, Chengpu

    2017-09-04

    We numerically study the propagation of a Laguerre-Gaussian beam through polar molecular media via the exact solution of full-wave Maxwell-Bloch equations where the rotating-wave and slowly-varying-envelope approximations are not included. It is found that beyond the coexistence of odd-order and even-order vortex harmonics due to inversion asymmetry of the system, the light propagation effect results in the intensity enhancement of a high-order vortex harmonics. Moreover, the orbital momentum successfully transfers from the fundamental laser driver to the vortex harmonics which topological charger number is directly proportional to its order.

  12. Mechanistic dissimilarities between environmentally-influenced fatigue-crack propagation at near-threshold and higher growth rates in lower-strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, S.; Ritchie, R. O.

    1981-11-01

    The role of hydrogen gas in influencing fatigue crack propagation is examined for several classes of lower strength pressure vessel and piping steels. Based on measurements over a wide range of growth rates from 10/sup -8/ to 10/sup -2/ mm/cycle, crack propagation rates are found to be significantly higher in dehumidified gaseous hydrogen compared to moist air in two distinct regimes of crack growth, namely (i) at the intermediate range of growth typically above approx. 10/sup -5/ mm/cycle, and (ii) at the near-threshold region below approx. 10/sup -6/ mm/cycle approaching lattice dimensions per cycle. Both effects are seen at maximum stress intensities (K/sub max/) far below the sustained-load threshold stress intensity for hydrogen-assisted cracking (K/sub Iscc/). Characteristics of environmentally influenced fatigue crack growth in each regime are shown to be markedly different with regard to fractography and the effect of such variables as load ratio and frequency. It is concluded that the primary mechanisms responsible for the influence of the environment in each regime are distinctly different. Whereas corrosion fatigue behavior at intermediate growth rates can be attributed to hydrogen embrittlement processes, the primary role of moist environments at near-threshold levels is shown to involve a contribution from enhanced crack closure due to the formation of crack surface corrosion deposits at low load ratios.

  13. Light pollution offshore: Zenithal sky glow measurements in the mediterranean coastal waters

    Science.gov (United States)

    Ges, Xavier; Bará, Salvador; García-Gil, Manuel; Zamorano, Jaime; Ribas, Salvador J.; Masana, Eduard

    2018-05-01

    Light pollution is a worldwide phenomenon whose consequences for the natural environment and the human health are being intensively studied nowadays. Most published studies address issues related to light pollution inland. Coastal waters, however, are spaces of high environmental interest, due to their biodiversity richness and their economical significance. The elevated population density in coastal regions is accompanied by correspondingly large emissions of artificial light at night, whose role as an environmental stressor is increasingly being recognized. Characterizing the light pollution levels in coastal waters is a necessary step for protecting these areas. At the same time, the marine surface environment provides a stage free from obstacles for measuring the dependence of the skyglow on the distance to the light polluting sources, and validating (or rejecting) atmospheric light propagation models. In this work we present a proof-of-concept of a gimbal measurement system that can be used for zenithal skyglow measurements on board both small boats and large vessels under actual navigation conditions. We report the results obtained in the summer of 2016 along two measurement routes in the Mediterranean waters offshore Barcelona, travelling 9 and 31.7 km away from the coast. The atmospheric conditions in both routes were different from the ones assumed for the calculation of recently published models of the anthropogenic sky brightness. They were closer in the first route, whose results approach better the theoretical predictions. The results obtained in the second route, conducted under a clearer atmosphere, showed systematic differences that can be traced back to two expected phenomena, which are a consequence of the smaller aerosol content: the reduction of the anthropogenic sky glow at short distances from the sources, and the slower decay rate of brightness with distance, which gives rise to a relative excess of brightness at large distances from the

  14. Simulation of action potential propagation in plants.

    Science.gov (United States)

    Sukhov, Vladimir; Nerush, Vladimir; Orlova, Lyubov; Vodeneev, Vladimir

    2011-12-21

    Action potential is considered to be one of the primary responses of a plant to action of various environmental factors. Understanding plant action potential propagation mechanisms requires experimental investigation and simulation; however, a detailed mathematical model of plant electrical signal transmission is absent. Here, the mathematical model of action potential propagation in plants has been worked out. The model is a two-dimensional system of excitable cells; each of them is electrically coupled with four neighboring ones. Ion diffusion between excitable cell apoplast areas is also taken into account. The action potential generation in a single cell has been described on the basis of our previous model. The model simulates active and passive signal transmission well enough. It has been used to analyze theoretically the influence of cell to cell electrical conductivity and H(+)-ATPase activity on the signal transmission in plants. An increase in cell to cell electrical conductivity has been shown to stimulate an increase in the length constant, the action potential propagation velocity and the temperature threshold, while the membrane potential threshold being weakly changed. The growth of H(+)-ATPase activity has been found to induce the increase of temperature and membrane potential thresholds and the reduction of the length constant and the action potential propagation velocity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Using memory-efficient algorithm for large-scale time-domain modeling of surface plasmon polaritons propagation in organic light emitting diodes

    Science.gov (United States)

    Zakirov, Andrey; Belousov, Sergei; Valuev, Ilya; Levchenko, Vadim; Perepelkina, Anastasia; Zempo, Yasunari

    2017-10-01

    We demonstrate an efficient approach to numerical modeling of optical properties of large-scale structures with typical dimensions much greater than the wavelength of light. For this purpose, we use the finite-difference time-domain (FDTD) method enhanced with a memory efficient Locally Recursive non-Locally Asynchronous (LRnLA) algorithm called DiamondTorre and implemented for General Purpose Graphical Processing Units (GPGPU) architecture. We apply our approach to simulation of optical properties of organic light emitting diodes (OLEDs), which is an essential step in the process of designing OLEDs with improved efficiency. Specifically, we consider a problem of excitation and propagation of surface plasmon polaritons (SPPs) in a typical OLED, which is a challenging task given that SPP decay length can be about two orders of magnitude greater than the wavelength of excitation. We show that with our approach it is possible to extend the simulated volume size sufficiently so that SPP decay dynamics is accounted for. We further consider an OLED with periodically corrugated metallic cathode and show how the SPP decay length can be greatly reduced due to scattering off the corrugation. Ultimately, we compare the performance of our algorithm to the conventional FDTD and demonstrate that our approach can efficiently be used for large-scale FDTD simulations with the use of only a single GPGPU-powered workstation, which is not practically feasible with the conventional FDTD.

  16. Light propagation in Liquid-infiltrated Microstructured Optical Fibres”

    DEFF Research Database (Denmark)

    Rasmussen, Per Dalgaard

    2008-01-01

    The work presented in this thesis is focussed on studying the possibilities of tuning and optimizing the performance of infiltrated waveguides in systems where nonlinear optical effects are exploited. Infiltrated systems where either nonlinear temporal or spatial effects come into play have been...... considered. First a general introduction to the basic principles used throughout the work is given. It is then shown how infiltrated waveguides can be used for manipulating dispersive and diffractive properties of light propagartion....

  17. Ponderomotive and weakly relativistic self-focusing of Gaussian laser beam in plasma: Effect of light absorption

    Energy Technology Data Exchange (ETDEWEB)

    Patil, S. D., E-mail: sdpatilphy@gmail.com [Department of Physics, Devchand College, Arjunnagar, Dist.: Kolhapur 591 237 (India); Takale, M. V. [Department of Physics, Shivaji University, Kolhapur 416 004 (India)

    2016-05-06

    This paper presents an influence of light absorption on self-focusing of laser beam propagation in plasma. The differential equation for beam-width parameter is obtained using the Wentzel-Kramers-Brillouin and paraxial approximations through parabolic equation approach. The nonlinearity in dielectric function is assumed to be aroused due to the combined effect of weakly relativistic and ponderomotive regime. To highlight the nature of propagation, behavior of beam-width parameter with dimensionless distance of propagation is presented graphically and discussed. The present work is helpful to understand issues related to the beam propagation in laser plasma interaction experiments where light absorption plays a vital role.

  18. Light in all its states; La lumiere dans tous ses etats

    Energy Technology Data Exchange (ETDEWEB)

    Aspect, A.; Grangier, Ph.; Bouyer, Ph.; Westbrook, Ch. [CNRS, Lab. Charles Fabry de l' Institut d' optique, 91 - Orsay (France); Reynaud, S.; Courty, J.M.; Treps, N.; Guery-Odelin, D.; Dalibard, J.; Fabre, C. [CNRS, Lab. Kastler Brossel, ENS, 75 - Paris (France); Abram, I.; Robert-Philip, I.; Bencheikh, K.; Levenson, A. [Laboratoire de Photonique et de Nanostructures, 91 - Marcoussis (France); Verstergaard Hau, L. [Harvard Univ. (United States); Institut de Rowland pour la Science de Cambridge, Massachusetts (United States); Lourtioz, J.M. [Paris-11 Univ., Institut d' Electronique Fondamentale, 91 - Orsay (France); Maystre, D. [Universite Paul Cezanne, Institut Fresnel, 13 - Marseille (France); Bigo, S.; Hamaide, J.P. [Alcatel, 91 - Marcoussis (France); Howard, W. [Societe d' eMagin, New York (United States); Geffroy, B. [CEA Saclay Dir. de la Recherche Technologique, 91 - Gif sur Yvette (France); Hopkins, J.M.; Sibbett, W. [Saint Andrews Univ. (United Kingdom); Mourou, G. [Ecole Nationale Superieure de Techniques Avancees, Lab. d' Optique Appliquee, 75 - Paris (France); Acef, O. [Observatoire de Paris, Lab. Systemes de Reference Temps et Espace, 75 (France); Bern, M. [Irvine Univ. (United States); Samain, E. [Observatoire de la Cote d' Azur (France); Kasparian, J. [Lyon-1 Univ., Lab. de Spectrometrie Ionique et Moleculaire, 69 (France); Hajian, A. [Observatoire Naval des Etats-Unis (United States); Armstrong, Th. [Laboratoire de Recherche Navale de Washington (United States); Labeyrie, A. [College de France, Lab. d' Interferometrie Stellaire et Exoplanetaire, 75 - Paris (France)

    2006-10-15

    This series of short articles is dedicated to different modern aspects of the physics of light. It is a work of popularization that is centered of 4 issues: 1) photons and one-photon light, 2) the propagation of light in the matter, 3) laser radiation, and 4) the use of light as a tool for measurement: interferometry.

  19. Impact of wave propagation delay on latency in optical communication systems

    Science.gov (United States)

    Kawanishi, Tetsuya; Kanno, Atsushi; Yoshida, Yuki; Kitayama, Ken-ichi

    2012-12-01

    Latency is an important figure to describe performance of transmission systems for particular applications, such as data transfer for earthquake early warning, transaction for financial businesses, interactive services such as online games, etc. Latency consists of delay due to signal processing at nodes and transmitters, and of signal propagation delay due to propagation of electromagnetic waves. The lower limit of the latency in transmission systems using conventional single mode fibers (SMFs) depends on wave propagation speed in the SMFs which is slower than c. Photonic crystal fibers, holly fibers and large core fibers can have low effective refractive indices, and can transfer light faster than in SMFs. In free-space optical systems, signals propagate with the speed c, so that the latency could be smaller than in optical fibers. For example, LEO satellites would transmit data faster than optical submarine cables, when the transmission distance is longer than a few thousand kilometers. This paper will discuss combination of various transmission media to reduce negative impact of the latency, as well as applications of low-latency systems.

  20. Multiple cracks initiation and propagation behavior of stainless steel in high temperature water environment

    International Nuclear Information System (INIS)

    Kamaya, Masayuki; Chiba, Goro; Nakajima, Nobuo; Totsuka, Nobuo

    2001-01-01

    Environmentally assisted crack initiation behavior is greatly affected by applied stress and environmental factors, such as water temperature, contained impurities and so on. On the other hand, crack initiation behavior also influences crack propagation. A typical example of this influence can be observed as the interference effects of multiple cracks, such as the coalescence of approaching crack tips or the arrest phenomena in the relaxation zone of an adjacent crack. To understand these effects of crack initiation on crack propagation behavior is very important to predict the lifetime of components, in which quite a few cracks tend to occur. This study aimed at revealing the crack initiation behavior and the influence of this behavior on propagation. At first, to evaluate the effect of applied stress on crack initiation behavior, sensitized stainless steel was subjected to a four-point bending test in a high temperature water environment at the constant potentials of ECP +50 mV and ECP +150 mV. Secondly, a crack initiation and growth simulation model was developed, in which the interference effect of multiple cracks is evaluated by the finite element method, based on the experimental results. Using this model, the relationship between crack initiation and propagation was studied. From the model, it was revealed that the increasing number of the cracks accelerates crack propagation and reduces life. (author)

  1. Initiation and propagation of multiple cracks of stainless steel in high temperature water environment

    Energy Technology Data Exchange (ETDEWEB)

    Kamaya, Masayuki; Chiba, Goro; Nakajima, Nobuo; Totsuka, Nobuo [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)

    2001-09-01

    Environmentally assisted crack initiation behavior is greatly affected by applied stress and environmental factors, such as water temperature, contained impurities and so on. Crack initiation behavior also influences crack propagation. A typical example of this influence can be observed as the interference effects of multiple cracks, such as the coalescence of approaching crack tips or the arrest phenomena in the relaxation zone of an adjacent crack. To understand these effects of crack initiation on crack propagation behavior is very important to predict the lifetime of components, in which relatively large number of cracks tend to occur. This study aimed at revealing the crack initiation behavior and the influence of this behavior on propagation. At first, to evaluate the effect of applied stress on crack initiation behavior, sensitized stainless steel was subjected to a four-point bending test in high temperature water environment at the constant potentials of +50 mV SHE and +150 mV SHE Secondly, a crack initiation and growth simulation model was developed, in which the interference effect of multiple cracks is evaluated by the finite element method, based on the experimental results. Using this model, the relationship between crack initiation and propagation was investigated, and it was revealed that the increasing number of the cracks accelerates crack propagation and reduces life. (author)

  2. Optical propagators in vector and spinor theories by path integral formalism

    International Nuclear Information System (INIS)

    Linares, J.

    1993-01-01

    The construction of an extended parabolic (wide-angle) vector and spinor wave theory is presented. For that, optical propagators in monochromatic vector light optics and monoenergetic spinor electron optics are evaluated by the path integral formalism. The auxiliary parameter method introduced by Fock and the Feynman-Dyson perturbative series are used. The proposed theory supplies, by a generalized Fermat's principle, the Mukunda-Simon-Sudarshan transformation for the passage from scalar to vector light (or spinor electron) optics in an asymptotic approximation. (author). 19 refs

  3. Two-Loop Quark Self-Energy in a New Formalism; 2, Renormalization of the Quark Propagator in the Light-Cone Gauge

    CERN Document Server

    Leibbrandt, George; Leibbrandt, George; Williams, Jimmy D.

    2000-01-01

    The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the noncovariant light-cone gauge (lcg). (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n^*-prescription for the spurious poles of 1/qn, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma_2 contains both covariant and noncovariant components, and is a local function of the external momentum p, even off the mass-shell, as all nonlocal divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma_2 implies a quark mass counterterm of the form $\\delta m (lcg) = m\\tilde\\alpha_s C_F(3+\\tilde\\alpha_sW) + {\\rm O} (\\tilde\\alpha_s^3)$, the dimensional regulator epsilon, and on th...

  4. An analysis of the theoretical rationale for using strategic environmental assessment to deliver environmental justice in the light of the Scottish Environmental Assessment Act

    International Nuclear Information System (INIS)

    Jackson, Tony; Illsley, Barbara

    2007-01-01

    The different ways in which its territorial jurisdictions have chosen to apply the European Union's (EU's) Directive on strategic environmental assessment (SEA) to their public sector policies, plans and programmes (PPPs) suggest that the United Kingdom (UK) continues to be uncertain about the theoretical rationale for this technique. In order to evaluate the analytical significance of these alternative interpretations, their methodological foundations need to be examined. Baseline-led approaches to SEA which are intended to operationalise sustainability can be shown to place unrealistic expectations on instrumental rationality. Objectives-led policy appraisal makes SEA contingent on whatever particular social construction of sustainable development holds sway. These expert-driven approaches contrast with a reflexive interpretation of environmental governance, in which SEA helps to expose the conflictual nature of public actions claiming to deliver sustainability, and offers stakeholders increased opportunities to challenge these. The approach adopted in Scotland, in which SEA forms part of an agenda for environmental justice, is evaluated in the light of this critique. The Scottish Executive's eclectic legislation, which covers all its public sector PPPs, may offer a way of mediating between these competing interpretations of SEA

  5. 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...

  6. Slow-light solitons in atomic media and doped optical fibers

    International Nuclear Information System (INIS)

    Korolkova, N.; Sinclair, G.F.; Leonhardt, U.

    2005-01-01

    Full text: We show how to generate optical solitons in atomic media that can be slowed down or accelerated at will. Such slow-light soliton is a polarization structure propagating with a speed that is proportional to the total intensity of the incident light. Ultimately, this method will allow the storage, retrieval and possibly the manipulation of the quantum information in atomic media. Solitons with controllable speed are constructed generalizing the theory of slow-light propagation to an integrable regime of nonlinear dynamics. For the first time, the inverse scattering method for slow-light solitons is developed. In contrast to the pioneering experimental demonstrations of slow light, we consider strong spin modulations where the non-linear dynamics of light and atoms creates polarization solitons. We also analyze how this scheme can be implemented in optical fibers doped with Lambda-atoms. In quantum-information applications, such slow-light solitons could complement the use of quantum solitons in fibres with the advantage of storing quantum information in media and complement methods for quantum memory with the advantages of non-linear dynamics, in particular the intrinsic stability of solitons. (author)

  7. Quantum hologram of macroscopically entangled light via the mechanism of diffuse light storage

    International Nuclear Information System (INIS)

    Gerasimov, L V; Sokolov, I M; Kupriyanov, D V; Havey, M D

    2012-01-01

    In this paper, we consider a quantum memory scheme for light diffusely propagating through a spatially disordered atomic gas. A unique characteristic is enhanced trapping of the signal light pulse by quantum multiple scattering, which can be naturally integrated with the mechanism of stimulated Raman conversion into a long-lived spin coherence. Then, the quantum state of the light can be mapped onto the disordered atomic spin subsystem and can be stored in it for a relatively long time. The proposed memory scheme can be applicable for storage of the macroscopic analogue of the Ψ (−) Bell state and the prepared entangled atomic state performs its quantum hologram, which suggests the possibility of further quantum information processing. (paper)

  8. Analysis of beam propagation characteristics in gain-guided, index antiguided fibers with the beam propagation method.

    Science.gov (United States)

    Ai, Fei; Qian, Jianqiang; Shi, Junfeng; Zhang, Machi

    2017-10-10

    The transmission properties of beams in gain fibers are studied with the complex refractive index beam propagation method (CRI-BPM). The method is checked by comparison with an analytic method. The behavior of a gain-guided, index antiguided (GG-IAG) fiber with different gain coefficients is studied. The simulation results show that the signal can transfer in the fiber with almost no loss when the gain coefficient reaches the threshold of the fundamental mode, and the shape of output spot will have no major changes when the gain coefficient is over the thresholds of high-order modes, even when the mode competition is not obvious. The CRI-BPM can predict the changes in light power and light mode at the same time, and will be very useful in the designing of fiber amplifiers and lasers with complex structures. More factors will be considered in this method to provide reference for practical application in our further research.

  9. SPEAKING IN LIGHT - Jupiter radio signals as deflections of light-emitting electron beams in a vacuum chamber

    Science.gov (United States)

    Petrovic, K.

    2015-10-01

    Light emitting electron beam generated in a vacuum chamber is used as a medium for visualizing Jupiter's electromagnetic radiation. Dual dipole array antenna is receiving HF radio signals that are next amplified to radiate a strong electromagnetic field capable of influencing the propagation of electron beam in plasma. Installation aims to provide a platform for observing the characteristics of light emitting beam in 3D, as opposed to the experiments with cathode ray tubes in 2-dimensional television screens. Gas giant 'speaking' to us by radio waves bends the light in the tube, allowing us to see and hear the messages of Jupiter - God of light and sky.

  10. THE IMPLICATIONS OF THE ENVIRONMENTAL MARKETING FACTORS WITHIN THE LIGHTING SOURCES AND FIXTURES MARKET

    Directory of Open Access Journals (Sweden)

    Cornelia Denisa IVAN

    2014-10-01

    Full Text Available Every company functionality is influenced by the environment in which they operate. In the present economical environment, the enterprise cannot survive in a market based on competition without continuously struggling to keep informed about the surroundings. The aim of this paper is to identify at the right time the new opportunities of development and also the threats which may compromise the company’s results or, even worse, may put the company in a difficult position. This research is important for the development of the enterprise’s strategies. The analysis of the marketing environment varies according to the field of the enterprise’s activity. Therefore, this article is a case study that examines the influence of environmental factors on the lighting sources and fixtures market (LSF. The originality and quality of the case stem from the attempt to analyze a dynamic field characterized by the buyers’ change of preferences and their receptivity to what is new, which requires increased consideration for the influence of environmental factors. The challenges of analyzing this domain consist of the transformations that take place with the new lighting technologies proposed by manufacturers to meet the users’ preferences. This review is relevant to the LSF market, but it can also be extended to other related fields.

  11. Atomic Interferometry with Detuned Counter-Propagating Electromagnetic Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, Ming -Yee [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-09-05

    Atomic fountain interferometry uses atoms cooled with optical molasses to 1 μK, which are then launched in a fountain mode. The interferometer relies on the nonlinear Raman interaction of counter-propagating visible light pulses. We present models of these key transitions through a series of Hamiltonians. Our models, which have been verified against special cases with known solutions, allow us to incorporate the effects of non-ideal pulse shapes and realistic laser frequency or wavevector jitter.

  12. Study of fatigue crack propagation in magnesium alloys

    International Nuclear Information System (INIS)

    Yarema, S.Ya.; Zinyuk, O.D.; Ostash, O.P.; Kudryashov, V.G.; Elkin, F.M.

    1981-01-01

    Fatigue crack propagation in standard (MA2-1, MA8) and super light (MA21, MA18) alloys has been investigated in the whole range of load amplitude changes-from threshold to critical; the materials have been compared by cyclic crack resistance, fractographic analysis has been made. It is shown that MA2-1 alloy crack resistance is slightly lower than the resistance of the other three alloys. MA8 and MA21 alloys having similar mechanical properties almost do not differ in cyclic crack resistance as well. MA18 alloy has the highest resistance to fatigue crack propagation in the whole range of Ksub(max) changes. The presented results on cyclic crack resistance of MA21 and MA18 alloys agree with the data on statistic fracture toughness. The fractures have been also investigated using a scanning electron microscope. Fracture microrelieves of MA8 and MA21 alloys are very similar. At low crack propagation rates (v - 7 m/cycle) it develops through grains, in MA2-1 alloy fracture intergrain fracture areas can be observed. In MA8 and MA21 alloy fractures groove covered areas can be seen alonside with areas of slipping plane laminatron; their specific weight increases with #betta# decrease. Lower crack propagation rates and higher values of threshold stress intensity factors for MA8 and MA21 alloys than for MA2-1 alloy are caused by the absence of intergrain fracture

  13. Slow light with low group-velocity dispersion at the edge of photonic graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang Chunfang; Dong Biqin; Liu Xiaohan; Zi Jian [Department of Physics, Key Laboratory of Micro- and Nanophotonic Structures, Ministry of Education, and Key Laboratory of Surface Physics, Fudan University, Shanghai 200433 (China); Xiong Zhiqiang; Zhao Fangyuan; Hu Xinhua [Department of Material Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433 (China)

    2011-07-15

    We theoretically study the light propagation at the zigzag edges of a honeycomb photonic crystal (PC), or photonic graphene. It is found that the corresponding edge states have a sinusoidal dispersion similar to those found in PC coupled resonator optical waveguides [CROWs; M. Notomi et al., Nature Photon. 2, 741 (2008)]. The sinusoidal dispersion curve can be made very flat by carefully tuning edge parameters. As a result, low group velocity and small group velocity dispersion can be simultaneously obtained for light propagating at the zigzag edge of photonic graphene. Compared with PC CROWs, our slow-light system exhibits no intrinsic radiation loss and has a larger group velocity bandwidth product. Our results could find applications in on-chip optical buffers and enhanced light-matter interaction.

  14. Long-Range Energy Propagation in Nanometer Arrays of Light Harvesting Antenna Complexes

    NARCIS (Netherlands)

    Escalantet, Maryana; Escalante Marun, M.; Lenferink, Aufrid T.M.; Zhao, Yiping; Tas, Niels Roelof; Huskens, Jurriaan; Hunter, C. Neil; Subramaniam, Vinod; Otto, Cornelis

    2010-01-01

    Here we report the first observation of long-range transport of excitation energy within a biomimetic molecular nanoarray constructed from LH2 antenna complexes from Rhodobacter sphaeroides. Fluorescence microscopy of the emission of light after local excitation with a diffraction-limited light beam

  15. 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.

  16. Cost effective flat plate photovoltaic modules using light trapping

    Science.gov (United States)

    Bain, C. N.; Gordon, B. A.; Knasel, T. M.; Malinowski, R. L.

    1981-01-01

    Work in optical trapping in 'thick films' is described to form a design guide for photovoltaic engineers. A thick optical film can trap light by diffusive reflection and total internal reflection. Light can be propagated reasonably long distances compared with layer thicknesses by this technique. This makes it possible to conduct light from inter-cell and intra-cell areas now not used in photovoltaic modules onto active cell areas.

  17. Non-unitary neutrino propagation from neutrino decay

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, Jeffrey M., E-mail: jeffreyberryman2012@u.northwestern.edu [Northwestern University, Department of Physics & Astronomy, 2145 Sheridan Road, Evanston, IL 60208 (United States); Gouvêa, André de; Hernández, Daniel [Northwestern University, Department of Physics & Astronomy, 2145 Sheridan Road, Evanston, IL 60208 (United States); Oliveira, Roberto L.N. [Northwestern University, Department of Physics & Astronomy, 2145 Sheridan Road, Evanston, IL 60208 (United States); Instituto de Física Gleb Wataghin Universidade Estadual de Campinas, UNICAMP 13083-970, Campinas, São Paulo (Brazil)

    2015-03-06

    Neutrino propagation in space-time is not constrained to be unitary if very light states – lighter than the active neutrinos – exist into which neutrinos may decay. If this is the case, neutrino flavor-change is governed by a handful of extra mixing and “oscillation” parameters, including new sources of CP-invariance violation. We compute the transition probabilities in the two- and three-flavor scenarios and discuss the different phenomenological consequences of the new physics. These are qualitatively different from other sources of unitarity violation discussed in the literature.

  18. Non-unitary neutrino propagation from neutrino decay

    International Nuclear Information System (INIS)

    Berryman, Jeffrey M.; Gouvêa, André de; Hernández, Daniel; Oliveira, Roberto L.N.

    2015-01-01

    Neutrino propagation in space-time is not constrained to be unitary if very light states – lighter than the active neutrinos – exist into which neutrinos may decay. If this is the case, neutrino flavor-change is governed by a handful of extra mixing and “oscillation” parameters, including new sources of CP-invariance violation. We compute the transition probabilities in the two- and three-flavor scenarios and discuss the different phenomenological consequences of the new physics. These are qualitatively different from other sources of unitarity violation discussed in the literature

  19. Spatial filtering of light by chirped photonic crystals

    International Nuclear Information System (INIS)

    Staliunas, Kestutis; Sanchez-Morcillo, Victor J.

    2009-01-01

    We propose an efficient method for spatial filtering of light beams by propagating them through two-dimensional (also three dimensional) chirped photonic crystals, i.e., through the photonic structures with fixed transverse lattice period and with the longitudinal lattice period varying along the direction of the beam propagation. We prove the proposed idea by numerically solving the paraxial propagation equation in refraction-index-modulated media and we evaluate the efficiency of the process by harmonic-expansion analysis. The technique can be also applied for filtering (for cleaning) of the packages of atomic waves (Bose condensates), also to improve the directionality of acoustic and mechanical waves.

  20. Characterization of Partially Polarized Light Fields

    CERN Document Server

    Martínez-Herrero, Rosario; Piquero, Gemma

    2009-01-01

    Polarization involves the vectorial nature of light fields. In current applications of optical science, the electromagnetic description of light with its vector features has been shown to be essential: In practice, optical radiation also exhibits randomness and spatial non-uniformity of the polarization state. Moreover, propagation through photonic devices can alter the correlation properties of the light field, resulting in changes in polarization. All these vectorial properties have been gaining importance in recent years, and they are attracting increasing attention in the literature. This is the framework and the scope of the present book, which includes the authors’ own contributions to these issues.

  1. Investigation on electrical tree propagation in polyethylene based on etching method

    Directory of Open Access Journals (Sweden)

    Zexiang Shi

    2017-11-01

    Full Text Available To investigate the characteristic of electrical tree propagation in semi-crystalline polymers, the low-density polyethylene (LDPE samples containing electrical trees are cut into slices by using ultramicrotome. Then the slice samples are etched by potassium permanganate etchant. Finally, the crystalline structure and the electrical tree propagation path in samples are observed by polarized light microscopy (PLM. According to the observation, the LDPE spherocrystal structure model is established on the basis of crystallization kinetics and morphology of polymers. And the electrical tree growth process in LDPE is discussed based on the free volume breakdown theory, the molecular chain relaxation theory, the electromechanical force theory, the thermal expansion effect and the space charge shielding effect.

  2. Propagation of optical pulses in a resonantly absorbing medium: Observation of negative velocity in Rb vapor

    International Nuclear Information System (INIS)

    Tanaka, H.; Hayami, K.; Furue, S.; Nakayama, K.; Niwa, H.; Kohmoto, T.; Kunitomo, M.; Fukuda, Y.

    2003-01-01

    Propagation of optical pulses in a resonantly absorbing medium is studied. Propagation time of nanosecond pulses was measured for the Rb D 1 transition. At the center of two absorption lines, delay of the pulse peak which is about ten times as large as the pulse width was observed, where zero delay is defined for the propagation with the light velocity in vacuum. On the other hand, at the peak of an absorption line, negative delay was observed for large absorption, where the advance time is as large as 25% of the pulse width. Simulation including the effect of absorption and phase shift reproduced well the experimental results

  3. Real and virtual propagation dynamics of angular accelerating white light beams

    CSIR Research Space (South Africa)

    Vetter, C

    2017-08-01

    Full Text Available light modulators. References and links 1. H. Rubinsztein-Dunlop, A. Forbes, M. Berry, M. Dennis, D. L. Andrews, M. Mansuripur, C. Denz, C. Alpmann, P. Banzer, T. Bauer, E. Karimi, L. Marrucci, M. Padgett, M. Ritsch-Marte, N.M. Litchinitser, N. P. Bigelow...–678 (2008). 16. N. K. Efremidis and D. N. Christodoulides, “Abruptly autofocusing waves,” Opt. Lett. 35, 4045–4047 (2010). 17. R. Steiger, S. Bernet, and M. Ritsch-Marte, “Slm-based off-axis fourier filtering in microscopy with white light illumination,” Opt...

  4. Studies of nonlinear femtosecond pulse propagation in bulk materials

    Science.gov (United States)

    Eaton, Hilary Kaye

    2000-10-01

    Femtosecond pulse lasers are finding widespread application in a variety of fields including medical research, optical switching and communications, plasma formation, high harmonic generation, and wavepacket formation and control. As the number of applications for femtosecond pulses increases, so does the need to fully understand the linear and nonlinear processes involved in propagating these pulses through materials under various conditions. Recent advances in pulse measurement techniques, such as frequency-resolved optical gating (FROG), allow measurement of the full electric field of the pulse and have made detailed investigations of short- pulse propagation effects feasible. In this thesis, I present detailed experimental studies of my work involving nonlinear propagation of femtosecond pulses in bulk media. Studies of plane-wave propagation in fused silica extend the SHG form of FROG from a simple pulse diagnostic to a useful method of interrogating the nonlinear response of a material. Studies of nonlinear propagation are also performed in a regime where temporal pulse splitting occurs. Experimental results are compared with a three- dimensional nonlinear Schrödinger equation. This comparison fuels the development of a more complete model for pulse splitting. Experiments are also performed at peak input powers above those at which pulse splitting is observed. At these higher intensities, a broadband continuum is generated. This work presents a detailed study of continuum behavior and power loss as well as the first near-field spatial- spectral measurements of the generated continuum light. Nonlinear plane-wave propagation of short pulses in liquids is also investigated, and a non-instantaneous nonlinearity with a surprisingly short response time of 10 fs is observed in methanol. Experiments in water confirm that this effect in methanol is indeed real. Possible explanations for the observed effect are discussed and several are experimentally rejected. This

  5. 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.

  6. 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.

  7. Vulnerability of Cochin Backwaters to meteorological disturbances with special reference to tidal propagation

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Balachandran, K.K.; Mehra, P.; Desai, R.G.P.; Dabholkar, N.; Kumar, V.; Revichandran, C.; Agarvadekar, Y.

    to meteorological disturbances has significant implications on its ecological and environmental health. Spectral analysis of tides revealed some of the special features of a complex shallow estuary. As the tide propagates into the interior estuary, it undergoes...

  8. Note: Experimental observation of nano-channel pattern in light sheet laser interference nanolithography system

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Kavya; Mondal, Partha Pratim, E-mail: partha@iap.iisc.ernet.in [Nanobioimaging Laboratory, Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012 (India)

    2016-06-15

    We experimentally observed nano-channel-like pattern in a light-sheet based interference nanolithography system. The optical system created nano-channel-like patterned illumination. Coherent counter-propagating light sheets are made to interfere at and near geometrical focus along the propagation z-axis. This results in the formation of nano-channel-like pattern (of size ≈ 300 nm and inter-channel periodicity of ≈337.5 nm) inside the sample due to constructive and destructive interference. In addition, the technique has the ability to generate large area patterning using larger light-sheets. Exciting applications are in the broad field of nanotechnology (nano-electronics and nano-fluidics).

  9. Two-loop quark self-energy in a new formalism; 2, Renormalization of the quark propagator in the light-cone gauge

    CERN Document Server

    Leibbrandt, G

    2000-01-01

    For pt.I see ibid., vol.440, p.537-602, 1995. The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the non-covariant light-cone gauge (LCG), n.A/sup a/(x)=0, n/sup 2/=0. (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n*/sub mu /-prescription for the spurious poles of (q.n)/sup -1/, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma /sub 2/ contains both covariant and non-covariant components, and is a local function of the external momentum p, even off the mass-shell, as all non-local divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma /sub 2/ implies a quark mass counterterm of the form delta m(LCG)=m alpha /sub...

  10. Analytical Study on Propagation Dynamics of Optical Beam in Parity-Time Symmetric Optical Couplers

    International Nuclear Information System (INIS)

    Zhou Zheng; Zhang Li-Juan; Zhu Bo

    2015-01-01

    We present exact analytical solutions to parity-time (PT) symmetric optical system describing light transport in PT-symmetric optical couplers. We show that light intensity oscillates periodically between two waveguides for unbroken PT-symmetric phase, whereas light always leaves the system from the waveguide experiencing gain when light is initially input at either waveguide experiencing gain or waveguide experiencing loss for broken PT-symmetric phase. These analytical results agree with the recent experimental observation reported by Rüter et al. [Nat. Phys. 6 (2010) 192]. Besides, we present a scheme for manipulating PT symmetry by applying a periodic modulation. Our results provide an efficient way to control light propagation in periodically modulated PT-symmetric system by tuning the modulation amplitude and frequency. (paper)

  11. Effects of Photonic Crystals on the Light Output of Heavy Inorganic Scintillators

    CERN Document Server

    Knapitsch, Arno; Fabjan, Christian W; Leclercq, Jean-Louis; Letartre, Xavier; Mazurczyk, Radoslaw; Lecoq, Paul

    2013-01-01

    Photonic crystals (PhCs) are optical materials which can affect the propagation of light in multiple ways. In recent years PhCs contributed to major technological developments in the field of semiconductor lasers, light emitting diodes and photovoltaic applications. In our case we are investigating the capabilities of photonic crystal slabs with the aim to improve the performance of heavy inorganic scintillators. To study the combination of scintillators and PhCs we use a Monte-Carlo program to simulate the light propagation inside a scintillator and a rigorous coupled wave analysis (RCWA) framework to analyse the optical PhC properties. The simulations show light output improvements of a wide range of scintillating materials due to light scattering effects of the PhC slabs. First samples have been produced on top of 1.2 × 2.6 × 5 mm LSO (cerium-doped Lutetium Oxyorthosilicate, Lu_2SiO_5:Ce^3+) scintillators using electron beam lithography and reactive ion etching (RIE). Our samples show a 30-60% light outp...

  12. Beam propagation modeling of modified volume Fresnel zone plates fabricated by femtosecond laser direct writing.

    Science.gov (United States)

    Srisungsitthisunti, Pornsak; Ersoy, Okan K; Xu, Xianfan

    2009-01-01

    Light diffraction by volume Fresnel zone plates (VFZPs) is simulated by the Hankel transform beam propagation method (Hankel BPM). The method utilizes circularly symmetric geometry and small step propagation to calculate the diffracted wave fields by VFZP layers. It is shown that fast and accurate diffraction results can be obtained with the Hankel BPM. The results show an excellent agreement with the scalar diffraction theory and the experimental results. The numerical method allows more comprehensive studies of the VFZP parameters to achieve higher diffraction efficiency.

  13. Postquench prethermalization in a disordered quantum fluid of light

    Science.gov (United States)

    Larré, Pierre-Élie; Delande, Dominique; Cherroret, Nicolas

    2018-04-01

    We study the coherence of a disordered and interacting quantum light field after propagation along a nonlinear optical fiber. Disorder is generated by a cross-phase modulation with a randomized auxiliary classical light field, while interactions are induced by self-phase modulation. When penetrating the fiber from free space, the incoming quantum light undergoes a disorder and interaction quench. By calculating the coherence function of the transmitted quantum light, we show that the decoherence induced by the quench spreads in a light-cone fashion in the nonequilibrium many-body quantum system, leaving the latter prethermalize with peculiar features originating from disorder.

  14. 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

  15. 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

  16. High speed photography for studying the shock wave propagation at high Mach numbers through a reflection nozzle

    International Nuclear Information System (INIS)

    Zaytsev, S.G.; Lazareva, E.V.; Mikhailova, A.V.; Nikolaev-Kozlov, V.L.; Chebotareva, E.I.

    1979-01-01

    Propagation of intensive shock waves with a temperature of about 1 eV has been studied in a two-dimensional reflection nozzle mounted at the exit of a shock tube. The Toepler technique has been involved along with the interference scheme with a laser light source allowing the multiple-frame recording to be done. Density distribution in the nozzle as well as the wave pattern occurring at the shock propagation are presented. (author)

  17. B meson excitations with chirally improved light quarks

    Energy Technology Data Exchange (ETDEWEB)

    Burch, Tommy [University of Regensburg (Germany); University of Utah (United States); Chakrabarti, Dipanker [University of Regensburg (Germany); Swansea University (United Kingdom); Hagen, Christian; Maurer, Thilo; Schaefer, Andreas [University of Regensburg (Germany); Lang, Christian; Limmer, Markus [University of Graz (Austria)

    2008-07-01

    We present our latest results for the excitations of static-light mesons on both quenched and unquenched lattices, where the light quarks are simulated using the chirally improved (CI) lattice Dirac operator. To improve our results we use a new technique to estimate the light quark propagator. The b quark is treated as infinitely heavy, in the so-called static approximation. We are able to find several excited states reaching from S-waves up to D-waves for both B and B{sub s}.

  18. Light-induced attractive force between two metal bodies separated by a subwavelength slit

    International Nuclear Information System (INIS)

    Nesterov, Vladimir; Frumin, Leonid

    2011-01-01

    A novel light-induced attractive force which acts as a force with negative light pressure has been revealed. The force arises by the interaction of plasmon polaritons which are excited at the surface of metal when a transverse magnetic mode propagates through a subwavelength slit between two metal bodies. The estimation of the repulsive force acting on the metal walls of the slit in the case of subwavelength TE mode propagation along the slit is presented. The explicit analytical expressions of light-induced forces between two macroscopic metal bodies or films separated by a subwavelength slit have been derived. These forces could be used to manipulate metallic macro-, micro- and nano-objects in vacuum or in a dielectric medium. Estimations of these light-induced forces show that the forces are sufficient for measurements and practical applications

  19. Final generic environmental statement on the use of recycle plutonium in mixed oxide fuel in light water cooled reactors. Volume 2

    International Nuclear Information System (INIS)

    1976-08-01

    This environmental statement assesses the impacts of the implementation of plutonium recycle in the LWR industry. It is based on assumptions that are intended to reflect conservatively an acceptable level of the application of current technology. It is not intended to be a representation of the ''as low as reasonably achievable'' (ALARA) philosophy. This generic environmental statement discusses the anticipated effects of recycling plutonium in light water nuclear power reactors. It is based on about 30 years of experience with the element in the context of a projected light water nuclear power industry that is already substantial. A background perspective on plutonium, its safety, and its recycling as a reactor fuel is presented

  20. 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.

  1. Light speed and the expansion of the universe

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Shigeto, E-mail: snagao@lilac.plala.or.jp [Business Development and Licensing, Nippon Boehringer Ingelheim Co., Ltd (Japan)

    2011-07-08

    Based on the formerly proposed model of the time and universe, a time-course of the light speed along with the expansion of the universe is discussed. Formulas of light propagated distance of a supernova are derived, whose graphs showed an excellent consistency to the observed supernovae data. This outcome verifies that the universe has been expanding at a constant speed by our observed time as the model predicts.

  2. Orbit covariance propagation via quadratic-order state transition matrix in curvilinear coordinates

    Science.gov (United States)

    Hernando-Ayuso, Javier; Bombardelli, Claudio

    2017-09-01

    In this paper, an analytical second-order state transition matrix (STM) for relative motion in curvilinear coordinates is presented and applied to the problem of orbit uncertainty propagation in nearly circular orbits (eccentricity smaller than 0.1). The matrix is obtained by linearization around a second-order analytical approximation of the relative motion recently proposed by one of the authors and can be seen as a second-order extension of the curvilinear Clohessy-Wiltshire (C-W) solution. The accuracy of the uncertainty propagation is assessed by comparison with numerical results based on Monte Carlo propagation of a high-fidelity model including geopotential and third-body perturbations. Results show that the proposed STM can greatly improve the accuracy of the predicted relative state: the average error is found to be at least one order of magnitude smaller compared to the curvilinear C-W solution. In addition, the effect of environmental perturbations on the uncertainty propagation is shown to be negligible up to several revolutions in the geostationary region and for a few revolutions in low Earth orbit in the worst case.

  3. Environmental coupling and population dynamics in the PE545 light-harvesting complex

    Energy Technology Data Exchange (ETDEWEB)

    Aghtar, Mortaza; Kleinekathöfer, Ulrich, E-mail: u.kleinekathoefer@jacobs-university.de

    2016-01-15

    Long-lived quantum coherences have been shown experimentally in the Fenna–Matthews–Olson (FMO) complex of green sulfur bacteria as well as in the phycoerythrin 545 (PE545) photosynthetic antenna system of marine algae. A combination of classical molecular dynamics simulations, quantum chemistry and quantum dynamical calculations is employed to determine the excitation transfer dynamics in PE545. One key property of the light-harvesting system concerning the excitation transfer and dephasing phenomena is the spectral density. This quantity is determined from time series of the vertical excitation energies of the aggregate. In the present study we focus on the quantum dynamical simulations using the earlier QM/MM calculations as input. Employing an ensemble-averaged classical path-based wave packet dynamics, the excitation transfer dynamics between the different bilins in the PE545 complex is determined and analyzed. Furthermore, the nature of the environmental fluctuations determining the transfer dynamics is discussed. - Highlights: • Modeling of excitation energy transfer in the light-harvesting system PE545. • Combination of molecular dynamics simulations, quantum chemistry and quantum dynamics. • Spectral densities for bilins in the PE545 complex.

  4. Conversion and conservation of light energy in a photosynthetic microbial mat ecosystem

    DEFF Research Database (Denmark)

    Al-Najjar, A.A.; De Beer, D.; Jørgensen, B. B.

    2011-01-01

    approach uses microscale measurements of the rates of heat dissipation, gross photosynthesis and light absorption in the system, and a model describing light propagation and conversion in a scattering-absorbing medium. The energy budget was dominated by heat dissipation on the expense of photosynthesis...

  5. Propagating Collective Hope in the Midst of Environmental Doom and Gloom

    Science.gov (United States)

    Kelsey, Elin

    2016-01-01

    Environmental educators recognize the importance of empowering children and adults, yet environmental education operates within a grand narrative of environmental gloom and doom. Growing evidence exists that children feel hopeless about the future of the planet. Given relationships between hope and agency, the question arises of how to propagate…

  6. Inventory calculation and nuclear data uncertainty propagation on light water reactor fuel using ALEPH-2 and SCALE 6.2

    International Nuclear Information System (INIS)

    Fiorito, L.; Piedra, D.; Cabellos, O.; Diez, C.J.

    2015-01-01

    Highlights: • We performed burnup calculations of PWR and BWR benchmarks using ALEPH and SCALE. • We propagated nuclear data uncertainty and correlations using different procedures and code. • Decay data uncertainties have negligible impact on nuclide densities. • Uncorrelated fission yields play a major role on the uncertainties of fission products. • Fission yields impact is strongly reduced by the introduction of correlations. - Abstract: Two fuel assemblies, one belonging to the Takahama-3 PWR and the other to the Fukushima-Daini-2 BWR, were modelled and the fuel irradiation was simulated with the TRITON module of SCALE 6.2 and with the ALEPH-2 code. Our results were compared to the experimental measurements of four samples: SF95-4 and SF96-4 were taken from the Takahama-3 reactor, while samples SF98-6 and SF99-6 belonged to the Fukushima-Daini-2. Then, we propagated the uncertainties coming from the nuclear data to the isotopic inventory of sample SF95-4. We used the ALEPH-2 adjoint procedure to propagate the decay constant uncertainties. The impact was inappreciable. The cross-section covariance information was propagated with the SAMPLER module of the beta3 version of SCALE 6.2. This contribution mostly affected the uncertainties of the actinides. Finally, the uncertainties of the fission yields were propagated both through ALEPH-2 and TRITON with a Monte Carlo sampling approach and appeared to have the largest impact on the uncertainties of the fission products. However, the lack of fission yield correlations results is a serious overestimation of the response uncertainties

  7. Hybrid diffusion and two-flux approximation for multilayered tissue light propagation modeling

    Science.gov (United States)

    Yudovsky, Dmitry; Durkin, Anthony J.

    2011-07-01

    Accurate and rapid estimation of fluence, reflectance, and absorbance in multilayered biological media has been essential in many biophotonics applications that aim to diagnose, cure, or model in vivo tissue. The radiative transfer equation (RTE) rigorously models light transfer in absorbing and scattering media. However, analytical solutions to the RTE are limited even in simple homogeneous or plane media. Monte Carlo simulation has been used extensively to solve the RTE. However, Monte Carlo simulation is computationally intensive and may not be practical for applications that demand real-time results. Instead, the diffusion approximation has been shown to provide accurate estimates of light transport in strongly scattering tissue. The diffusion approximation is a greatly simplified model and produces analytical solutions for the reflectance and absorbance in tissue. However, the diffusion approximation breaks down if tissue is strongly absorbing, which is common in the visible part of the spectrum or in applications that involve darkly pigmented skin and/or high local volumes of blood such as port-wine stain therapy or reconstructive flap monitoring. In these cases, a model of light transfer that can accommodate both strongly and weakly absorbing regimes is required. Here we present a model of light transfer through layered biological media that represents skin with two strongly scattering and one strongly absorbing layer.

  8. Light distribution system comprising spectral conversion means

    DEFF Research Database (Denmark)

    2012-01-01

    , longer wavelength,a spectral conversion characteristics of the spectral conversion fibre being essentially determined by the spectral absorption and emission properties of the photoluminescent agent, the amount of photo- luminescent agent,and the distribution of the photoluminescent agent in the spectral......System (200, 300) for the distribution of white light, having a supply side (201, 301, 401) and a delivery side (202, 302, 402), the system being configured for guiding light with a multitude of visible wavelengths in a propagation direction P from the supply side to the distribution side...... of providing a light distribution system and a method of correcting the spectral transmission characteristics of a light distribution system are disclosed....

  9. Nutrition in the spotlight: metabolic effects of environmental light

    NARCIS (Netherlands)

    Versteeg, Ruth I.; Stenvers, Dirk J.; Kalsbeek, Andries; Bisschop, Peter H.; Serlie, Mireille J.; la Fleur, Susanne E.

    2016-01-01

    Use of artificial light resulted in relative independence from the natural light-dark (LD) cycle, allowing human subjects to shift the timing of food intake and work to convenient times. However, the increase in artificial light exposure parallels the increase in obesity prevalence. Light is the

  10. Nutrition in the spotlight metabolic effects of environmental light

    NARCIS (Netherlands)

    Versteeg, Ruth I; Stenvers, Dirk J; Kalsbeek, A.; Bisschop, Peter H; Serlie, Mireille J; la Fleur, Susanne E

    2016-01-01

    Use of artificial light resulted in relative independence from the natural light-dark (LD) cycle, allowing human subjects to shift the timing of food intake and work to convenient times. However, the increase in artificial light exposure parallels the increase in obesity prevalence. Light is the

  11. Wave propagation inside one-dimensional photonic crystals with single-negative materials

    International Nuclear Information System (INIS)

    Wang Ligang; Chen Hong; Zhu Shiyao

    2006-01-01

    The propagation of light waves in one-dimensional photonic crystals (1DPCs) composed of alternating layers of two kinds of single-negative materials is investigated theoretically. The phase velocity is negative when the frequency of the light wave is smaller than the certain critical frequency ω cr , while the Poynting vector is always positive. At normal incidence, such 1DPCs may act as equivalent left-handed materials. At the inclined incidence, the effective wave vectors inside such 1DPCs do refract negatively, while the effective energy flows do not refract negatively. Therefore, at the inclined incidence, the 1DPCs are not equivalent to the left-handed materials

  12. Propagation of gravitational waves in the generalized tensor-vector-scalar theory

    International Nuclear Information System (INIS)

    Sagi, Eva

    2010-01-01

    Efforts are underway to improve the design and sensitivity of gravitational wave detectors, with the hope that the next generation of these detectors will observe a gravitational wave signal. Such a signal will not only provide information on dynamics in the strong gravity regime that characterizes potential sources of gravitational waves, but will also serve as a decisive test for alternative theories of gravitation that are consistent with all other current experimental observations. We study the linearized theory of the tensor-vector-scalar theory of gravity with generalized vector action, an alternative theory of gravitation designed to explain the apparent deficit of visible matter in galaxies and clusters of galaxies without postulating yet-undetected dark matter. We find the polarization states and propagation speeds for gravitational waves in vacuum, and show that in addition to the usual transverse-traceless propagation modes, there are two more mixed longitudinal-transverse modes and two trace modes, of which at least one has longitudinal polarization. Additionally, the propagation speeds are different from the speed of light.

  13. Soft X-Ray Microscopy and Spectroscopy at the Molecular Environmental Science Beamline at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Bluhm, Hendrik; Andersson, Klas J.; Araki, Tohru; Benzerara, Karim; Brown, Gordon E.; Dynes, Jay J.; Ghosal, Sutapa; Gilles, Mary K.; Hansen, Hans C.; Hemminger, J. C.; Hitchcock, Adam P.; Ketteler, Guido; Kilcoyne, Arthur L.; Kneedler, Eric M.; Lawrence, John R.; Leppard, Gary G.; Majzlam, Juraj; Mun, B. S.; Myneni, Satish C.; Nilsson, Anders R.; Ogasawara, Hirohito; Ogletree, D. F.; Pecher, Klaus H.; Salmeron, Miquel B.; Shuh, David K.; Tonner, Brian; Tyliszczak, Tolek; Warwick, Tony; Yoon, T. H.

    2006-02-01

    We present examples of the application of synchrotron-based spectroscopies and microscopies to environmentally-relevant samples. The experiments were performed at the Molecular Environmental Science beamline (11.0.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Examples range from the study of water monolayers on Pt(111) single crystal surfaces using X-ray emission spectroscopy and the examination of alkali halide solution/water vapor interfaces using ambient pressure photoemission spectroscopy, to the investigation of actinides, river-water biofilms, Al-containing colloids and mineral-bacteria suspensions using scanning transmission X-ray spectromicroscopy. The results of our experiments show that spectroscopy and microscopy in the soft X-ray energy range are excellent tools for the investigation of environmentally relevant samples under realistic conditions, i.e. with water or water vapor present at ambient temperature.

  14. Quantum manipulation of two-color stationary light: Quantum wavelength conversion

    International Nuclear Information System (INIS)

    Moiseev, S. A.; Ham, B. S.

    2006-01-01

    We present a quantum manipulation of a traveling light pulse using electromagnetically induced transparency-based slow light phenomenon for the generation of two-color stationary light. We theoretically discuss the two-color stationary light for the quantum wavelength conversion process in terms of pulse area, energy transfer, and propagation directions. The condition of the two-color stationary light pulse generation has been found and the quantum light dynamics has been studied analytically in the adiabatic limit. The quantum frequency conversion rate of the traveling light is dependent on the spatial spreading of the two-color stationary light pulse and can be near unity in an optically dense medium for the optimal frequencies of the control laser fields

  15. An environmental index of noise and light pollution at EU by spatial correlation of quiet and unlit areas.

    Science.gov (United States)

    Votsi, Nefta-Eleftheria P; Kallimanis, Athanasios S; Pantis, Ioannis D

    2017-02-01

    Quietness exists in places without human induced noise sources and could offer multiple benefits to citizens. Unlit areas are sites free of human intense interference at night time. The aim of this research is to develop an integrated environmental index of noise and light pollution. In order to achieve this goal the spatial pattern of quietness and darkness of Europe was identified, as well as their overlap. The environmental index revealed that the spatial patterns of Quiet and Unlit Areas differ to a great extent highlighting the importance of preserving quietness as well as darkness in EU. The spatial overlap of these two environmental characteristics covers 32.06% of EU surface area, which could be considered a feasible threshold for protection. This diurnal and nocturnal metric of environmental quality accompanied with all direct and indirect benefits to human well-being could indicate a target for environmental protection in the EU policy and practices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Structured Light-Matter Interactions Enabled By Novel Photonic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Litchinitser, Natalia [Univ. at Buffalo, NY (United States); Feng, Liang [Univ. at Buffalo, NY (United States)

    2017-05-02

    The synergy of complex materials and complex light is expected to add a new dimension to the science of light and its applications [1]. The goal of this program is to investigate novel phenomena emerging at the interface of these two branches of modern optics. While metamaterials research was largely focused on relatively “simple” linearly or circularly polarized light propagation in “complex” nanostructured, carefully designed materials with properties not found in nature, many singular optics studies addressed “complex” structured light transmission in “simple” homogeneous, isotropic, nondispersive transparent media, where both spin and orbital angular momentum are independently conserved. However, if both light and medium are complex so that structured light interacts with a metamaterial whose optical materials properties can be designed at will, the spin or angular momentum can change, which leads to spin-orbit interaction and many novel optical phenomena that will be studied in the proposed project. Indeed, metamaterials enable unprecedented control over light propagation, opening new avenues for using spin and quantum optical phenomena, and design flexibility facilitating new linear and nonlinear optical properties and functionalities, including negative index of refraction, magnetism at optical frequencies, giant optical activity, subwavelength imaging, cloaking, dispersion engineering, and unique phase-matching conditions for nonlinear optical interactions. In this research program we focused on structured light-matter interactions in complex media with three particularly remarkable properties that were enabled only with the emergence of metamaterials: extreme anisotropy, extreme material parameters, and magneto-electric coupling–bi-anisotropy and chirality.

  17. Ultrahigh energy nuclei propagation in a structured, magnetized universe

    International Nuclear Information System (INIS)

    Armengaud, Eric; Sigl, Guenter; Miniati, Francesco

    2005-01-01

    We compare the propagation of iron and proton nuclei above 10 19 eV in a structured Universe with source and magnetic field distributions obtained from a large-scale structure simulation and source densities ∼10 -5 Mpc -3 . All relevant cosmic ray interactions are taken into account, including photo-disintegration and propagation of secondary products. Iron injection predicts spectral shapes different from proton injection which disagree with existing data below ≅30 EeV. Injection of light nuclei or protons must therefore contribute at these energies. However, at higher energies, existing data are consistent with injection of pure iron with spectral indices between ∼2 and ∼2.4. This allows a significant recovery of the spectrum above ≅100 EeV, especially in the case of large deflections. Significant autocorrelation and anisotropy, and considerable cosmic variance are also predicted in this energy range. The mean atomic mass fluctuates considerably between different scenarios. At energies below 60 EeV, if the observed A > or approx. 35, magnetic fields must have a negligible effect on propagation. At the highest energies the observed flux will be dominated by only a few sources whose location may be determined by next generation experiments to within 10-20 deg. even if extra-galactic magnetic fields are important

  18. Characteristics of coupled acoustic wave propagation in metal pipe

    International Nuclear Information System (INIS)

    Kim, Ho Wuk; Kim, Min Soo; Lee, Sang Kwon

    2008-01-01

    The circular cylinder pipes are used in the many industrial areas. In this paper, the acoustic wave propagation in the pipe containing gas is researched. First of all, the theory for the coupled acoustic wave propagation in a pipe is investigated. Acoustic wave propagation in pipe can not be occurred independently between the wave of the fluid and the shell. It requires complicated analysis. However, as a special case, the coupled wave in a high density pipe containing a light density medium is corresponded closely to the uncoupled in-vacuo shell waves and to the rigid-walled duct fluid waves. The coincidence frequencies of acoustic and shell modes contribute to the predominant energy transmission. The coincidence frequency means the frequency corresponding to the coincidence of the wavenumber in both acoustic and shell. In this paper, it is assumed that the internal medium is much lighter than the pipe shell. After the uncoupled acoustic wave in the internal medium and uncoupled shell wave are considered, the coincidence frequencies are found. The analysis is successfully confirmed by the verification of the experiment using the real long steel pipe. This work verifies that the coupled wave characteristic of the shell and the fluid is occurred as predominant energy transmission at the coincidence frequencies

  19. Photon extraction from nitride ultraviolet light-emitting devices

    Science.gov (United States)

    Schowalter, Leo J; Chen, Jianfeng; Grandusky, James R

    2015-02-24

    In various embodiments, a rigid lens is attached to a light-emitting semiconductor die via a layer of encapsulant having a thickness insufficient to prevent propagation of thermal expansion mismatch-induced strain between the rigid lens and the semiconductor die.

  20. Slow light in quantum dot photonic crystal waveguides

    DEFF Research Database (Denmark)

    Nielsen, Torben Roland; Lavrinenko, Andrei; Mørk, Jesper

    2009-01-01

    A theoretical analysis of pulse propagation in a semiconductor quantum dot photonic crystal waveguide in the regime of electromagnetically induced transparency is presented. The slow light mechanism considered here is based on both material and waveguide dispersion. The group index n...

  1. Imaging of propagation dynamics of optically-excited spin waves in a garnet film

    International Nuclear Information System (INIS)

    Hashimoto, Yusuke; Saitoh, Eiji

    2016-01-01

    We demonstrate the direct imaging of the propagation dynamics of the optically-excited spin waves in a garnet film observed with an all-optical pump-and-probe magneto-optical imaging technique having sub-pico second time-resolution, sub-micrometer spatial resolution, and milli-degrees of accuracy in the rotation angle of the light polarization. (author)

  2. Excitation of fluorescent nanoparticles by channel plasmon polaritons propagating in V-grooves

    DEFF Research Database (Denmark)

    Cuesta, Irene Fernandez; Nielsen, Rasmus Bundgaard; Boltasseva, Alexandra

    2009-01-01

    Recently, it has been proven that light can be squeezed into metallic channels with subwavelength lateral dimensions. Here, we present the study of the propagation of channel plasmon polaritons confined in gold V-grooves, filled with fluorescent particles. In this way, channel plasmon polaritons......-diameter beads, we show the possibility of individual excitation, what may have applications to develop very sensitive biosensors....

  3. Hot electron spatial distribution under presence of laser light self-focusing in over-dense plasmas

    International Nuclear Information System (INIS)

    Tanimoto, T; Yabuuchi, T; Habara, H; Kondo, K; Kodama, R; Mima, K; Tanaka, K A; Lei, A L

    2008-01-01

    In fast ignition for laser thermonuclear fusion, an ultra intense laser (UIL) pulse irradiates an imploded plasma in order to fast-heat a high-density core with hot electrons generated in laser-plasma interactions. An UIL pulse needs to make plasma channel via laser self-focusing and to propagate through the corona plasma to reach close enough to the core. Hot electrons are used for heating the core. Therefore the propagation of laser light in the high-density plasma region and spatial distribution of hot electron are important in issues in order to study the feasibility of this scheme. We measure the spatial distribution of hot electron when the laser light propagates into the high-density plasma region by self-focusing

  4. Can Lighting Influence Self-Disclosure?

    Science.gov (United States)

    Mehta, Veli; Mukherjee, Sumitava; Manjaly, Jaison A

    2017-01-01

    With the advent of social networks where people disclose a lot of their information and opinions publicly, this research attempted to re-look at the effect of environmental lighting on willingness and actual disclosure of personal information. Previous literatures mostly addressed counseling setups and the findings were mixed. In order to clarify the effect of lighting on self-disclosure, two experiments were conducted with reported willingness to disclose (Experiment 1) as well as actual disclosure (Experiment 2) on a range of topics like social issues, body, money, work, and personality. While quite a handful of studies have reported differences in disclosure from very subtle environmental lighting manipulations, in both experiments we could not find any effect of ambient room lighting conditions on self-disclosure. These results call for caution both in over-interpreting subtle environmental effects and in increased generalization of perceptual metaphors to actual behavior.

  5. Assessing Light Pollution in China Based on Nighttime Light Imagery

    OpenAIRE

    Wei Jiang; Guojin He; Tengfei Long; Chen Wang; Yuan Ni; Ruiqi Ma

    2017-01-01

    Rapid urbanization and economic development inevitably lead to light pollution, which has become a universal environmental issue. In order to reveal the spatiotemporal patterns and evolvement rules of light pollution in China, images from 1992 to 2012 were selected from the Defense Meteorological Satellite Program Operational Linescan System (DMSP/OLS) and systematically corrected to ensure consistency. Furthermore, we employed a linear regression trend method and nighttime light index method...

  6. Estimation of crosstalk in LED fNIRS by photon propagation Monte Carlo simulation

    Science.gov (United States)

    Iwano, Takayuki; Umeyama, Shinji

    2015-12-01

    fNIRS (functional near-Infrared spectroscopy) can measure brain activity non-invasively and has advantages such as low cost and portability. While the conventional fNIRS has used laser light, LED light fNIRS is recently becoming common in use. Using LED for fNIRS, equipment can be more inexpensive and more portable. LED light, however, has a wider illumination spectrum than laser light, which may change crosstalk between the calculated concentration change of oxygenated and deoxygenated hemoglobins. The crosstalk is caused by difference in light path length in the head tissues depending on wavelengths used. We conducted Monte Carlo simulations of photon propagation in the tissue layers of head (scalp, skull, CSF, gray matter, and white matter) to estimate the light path length in each layers. Based on the estimated path lengths, the crosstalk in fNIRS using LED light was calculated. Our results showed that LED light more increases the crosstalk than laser light does when certain combinations of wavelengths were adopted. Even in such cases, the crosstalk increased by using LED light can be effectively suppressed by replacing the value of extinction coefficients used in the hemoglobin calculation to their weighted average over illumination spectrum.

  7. Light pollution : working paper

    NARCIS (Netherlands)

    Lechner, Stefan; Arns, Marieke

    2013-01-01

    Light pollution is one of the fastest growing and most pervasive of environmental pollution (Chepesiuk, 2009). In the last couple of years, a lot of research has been done about the effects of light pollution. The interest in light pollution has been growing in many fields of science, extending from

  8. Contrasting trends in light pollution across Europe based on satellite observed night time lights.

    Science.gov (United States)

    Bennie, Jonathan; Davies, Thomas W; Duffy, James P; Inger, Richard; Gaston, Kevin J

    2014-01-21

    Since the 1970s nighttime satellite images of the Earth from space have provided a striking illustration of the extent of artificial light. Meanwhile, growing awareness of adverse impacts of artificial light at night on scientific astronomy, human health, ecological processes and aesthetic enjoyment of the night sky has led to recognition of light pollution as a significant global environmental issue. Links between economic activity, population growth and artificial light are well documented in rapidly developing regions. Applying a novel method to analysis of satellite images of European nighttime lights over 15 years, we show that while the continental trend is towards increasing brightness, some economically developed regions show more complex patterns with large areas decreasing in observed brightness over this period. This highlights that opportunities exist to constrain and even reduce the environmental impact of artificial light pollution while delivering cost and energy-saving benefits.

  9. The intergalactic propagation of ultrahigh energy cosmic ray nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hooper, Dan; /Fermilab; Sarkar, Subir; /Oxford U., Theor. Phys.; Taylor, Andrew M.; /Oxford U.

    2006-08-01

    We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).

  10. Transient Aspects of Wave Propagation Connected with Spatial Coherence

    Directory of Open Access Journals (Sweden)

    Ezzat G. Bakhoum

    2013-01-01

    Full Text Available This study presents transient aspects of light wave propagation connected with spatial coherence. It is shown that reflection and refraction phenomena involve spatial patterns which are created within a certain transient time interval. After this transient time interval, these patterns act like a memory, determining the wave vector for subsequent sets of reflected/refracted waves. The validity of this model is based on intuitive aspects regarding phase conservation of energy for waves reflected/refracted by multiple centers in a certain material medium.

  11. Environmentally assisted cracking in Light Water Reactors

    International Nuclear Information System (INIS)

    Chung, H.M.; Chopra, O.K.; Ruther, W.E.; Kassner, T.F.; Michaud, W.F.; Park, J.Y.; Sanecki, J.E.; Shack, W.J.

    1993-09-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) during the six months from October 1992 to March 1993. Fatigue and EAC of piping, pressure vessels, and core components in LWRs are important concerns as extended reactor lifetimes are envisaged. Topics that have been investigated include (1) fatigue of low-alloy steel used in piping, steam generators, and reactor pressure vessels. (2) EAC of cast stainless steels (SSs), (3) radiation-induced segregation and irradiation-assisted stress corrosion cracking of Type 304 SS after accumulation of relatively high fluence, and (4) EAC of low-alloy steels. Fatigue tests were conducted on medium-sulfur-content A106-Gr B piping and A533-Gr B pressure vessel steels in simulated PWR water and in air. Additional crack growth data were obtained on fracture-mechanics specimens of cast austenitic SSs in the as-received and thermally aged conditions and chromium-nickel-plated A533-Gr B steel in simulated boiling-water reactor (BWR) water at 289 degrees C. The data were compared with predictions based on crack growth correlations for ferritic steels in oxygenated water and correlations for wrought austenitic SS in oxygenated water developed at ANL and rates in air from Section XI of the ASME Code. Microchemical and microstructural changes in high- and commercial-purity Type 304 SS specimens from control-blade absorber tubes and a control-blade sheath from operating BWRs were studied by Auger electron spectroscopy and scanning electron microscopy

  12. Food for thought: Conditions for discourse reflection in the light of environmental assessment

    International Nuclear Information System (INIS)

    Runhaar, Hens; Runhaar, Piety R.; Oegema, Tammo

    2010-01-01

    People tend to take notice of what is happening around them selectively. Discourses-frames through which actors give meaning to aspects of the world-act as built-in filters that distinguish relevant from irrelevant data. Use of knowledge generated by environmental assessments (EAs) in decision-making may be understood from this perspective. Environmental knowledge that is inconsistent with dominant discourses runs the risk of being ignored. Discourses on the value of EA as a tool for decision-making may have a similar effect. Stimulating decision-makers and stakeholders to critically reflect on and reconsider their discourses in the light of EAs-also known as frame reflection or policy learning-may enhance the probability that these assessments and the knowledge that they generate impact upon decision-making. Up to now little has been written about how discourse reflection in the context of EA can be promoted. Valuable inputs are fragmented over different bodies of literature. In this paper we draw from these bodies to identify favourable conditions for discourse reflection.

  13. Slow light enhancement and limitations in periodic media

    DEFF Research Database (Denmark)

    Grgic, Jure

    in the vicinity of the band edge. The minimum attainable group velocity will depend on the amount of imperfections. Since imperfections are inherited as part of any periodic structure it is necessary to take them into account when we are interested in slow light applications. Slowly propagating light gives rise......Properties of periodic dielectric media have attracted a big interest in the last two decades due to numerous exciting physical phenomena that cannot occur in homogeneous media. Due to their strong dispersive properties, the speed of light can be significantly slowed down in periodic structures....... When light velocity is much smaller than the speed of light in a vacuum, we describe this phenomena as slow light. In this thesis, we analyze important properties of slow light enhancement and limitations in periodic structures. We analyze quantitatively and qualitatively different technologies...

  14. On the propagation velocity of a wave packet in an amplifying medium

    International Nuclear Information System (INIS)

    Bukhman, N S

    2001-01-01

    It is shown that the delay time of a weak signal propagating in an amplifying medium on the wings of the spectral amplification line may be shorter than the time of propagation of the signal with the velocity of light in vacuum. It is found that in this case, the time dependence of the signal is exactly 'reconstructed' at the point of detection, and the detection of the signal continues even if it is abruptly terminated at the point of transmission. It is also shown that using the complex time of group delay of the signal, it is possible to improve the accuracy of the results in the first order of dispersion theory within this approximation. (physical foundations of quantum electronics)

  15. Rigorous vector wave propagation for arbitrary flat media

    Science.gov (United States)

    Bos, Steven P.; Haffert, Sebastiaan Y.; Keller, Christoph U.

    2017-08-01

    Precise modelling of the (off-axis) point spread function (PSF) to identify geometrical and polarization aberrations is important for many optical systems. In order to characterise the PSF of the system in all Stokes parameters, an end-to-end simulation of the system has to be performed in which Maxwell's equations are rigorously solved. We present the first results of a python code that we are developing to perform multiscale end-to-end wave propagation simulations that include all relevant physics. Currently we can handle plane-parallel near- and far-field vector diffraction effects of propagating waves in homogeneous isotropic and anisotropic materials, refraction and reflection of flat parallel surfaces, interference effects in thin films and unpolarized light. We show that the code has a numerical precision on the order of 10-16 for non-absorbing isotropic and anisotropic materials. For absorbing materials the precision is on the order of 10-8. The capabilities of the code are demonstrated by simulating a converging beam reflecting from a flat aluminium mirror at normal incidence.

  16. Adaptive Generation and Diagnostics of Linear Few-Cycle Light Bullets

    Directory of Open Access Journals (Sweden)

    Martin Bock

    2013-02-01

    Full Text Available Recently we introduced the class of highly localized wavepackets (HLWs as a generalization of optical Bessel-like needle beams. Here we report on the progress in this field. In contrast to pulsed Bessel beams and Airy beams, ultrashort-pulsed HLWs propagate with high stability in both spatial and temporal domain, are nearly paraxial (supercollimated, have fringe-less spatial profiles and thus represent the best possible approximation to linear “light bullets”. Like Bessel beams and Airy beams, HLWs show self-reconstructing behavior. Adaptive HLWs can be shaped by ultraflat three-dimensional phase profiles (generalized axicons which are programmed via calibrated grayscale maps of liquid-crystal-on-silicon spatial light modulators (LCoS-SLMs. Light bullets of even higher complexity can either be freely formed from quasi-continuous phase maps or discretely composed from addressable arrays of identical nondiffracting beams. The characterization of few-cycle light bullets requires spatially resolved measuring techniques. In our experiments, wavefront, pulse and phase were detected with a Shack-Hartmann wavefront sensor, 2D-autocorrelation and spectral phase interferometry for direct electric-field reconstruction (SPIDER. The combination of the unique propagation properties of light bullets with the flexibility of adaptive optics opens new prospects for applications of structured light like optical tweezers, microscopy, data transfer and storage, laser fusion, plasmon control or nonlinear spectroscopy.

  17. Analysis of SCC initiation/propagation behavior of stainless steels in LWR environments

    International Nuclear Information System (INIS)

    Saito, Koichi; Kuniya, Jiro

    1999-01-01

    This paper presents a method to analyze initiation and propagation behavior of stress corrosion cracking (SCC) of stainless steels on the basis of a new prediction algorithm in which the initiation period and propagation period of SCC under irradiation conditions are considered from a practical viewpoint. The prediction algorithm is based on three ideas: (1) threshold neutron fluence of radiation-enhanced SCC (RESCC), (2) equivalent critical crack depth, and (3) threshold stress intensity factor for SCC (K ISCC ). SCC initiation/propagation behavior in light water reactor (LWR) environments is analyzed by incorporating model equations on irradiation hardening, irradiation-enhanced electrochemical potentiokinetic reactivation (EPR) and irradiation stress relaxation that are phenomena peculiar to neutron irradiation. The analytical method is applied to predict crack growth behavior of a semi-elliptical surface crack in a flat plane that has an arbitrary residual stress profile; specimens are sensitized type 304 stainless steels which had been subjected to neutron irradiation in high temperature water. SCC growth behavior of a semi-elliptical surface crack was greatly dependent on the distribution of residual stress in a flat plane. When residual stress at the surface of the flat plane was relatively small, the method predicted SCC propagation did not take place. (author)

  18. FY1995 fundamental study of imaging simulator for diagnostics and therapeutics using light; 1995 nendo hikari wo riyosuru shindan chiryoyo gazo simulator no kiso kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Medical application of lasers is rapidly expanding in accordance with the development of laser technology. However, it is difficult to predict how light propagates and is absorbed by living bodies because of strong scattering of light by biological tissues. Therefore, the determination of light dose has been based on experience. This fundamental study aims to develop a imaging simulator which can predict propagation of light and its effectiveness in medical diagnostics and therapeutics. Teoretical models of light propagation in biological tissues have been constructed, and experiments have been conducted to validate the theoretical calculation. In the theoretical calculation, a three-dimensional model which simulates a human head with five layers of different tissue types. Numerical calculation has been done by using the finite element method to simulate the propagation of ultrashort pulse light, and it is shown by a computer graphics technique for the first time in the world. In the experiment, a solid phantom which anatomically and optically simulates a human head based on MRI images has been fabricated by using the optical prototyping technology for the first time in the world again. Also, we have compared the experimental results of the transmitted light through the solid phantoms with the theoretical results and have succeeded in reconstructing the tomographic images of optical properties. (NEDO)

  19. Microbial alignment in flow changes ocean light climate.

    Science.gov (United States)

    Marcos; Seymour, Justin R; Luhar, Mitul; Durham, William M; Mitchell, James G; Macke, Andreas; Stocker, Roman

    2011-03-08

    The growth of microbial cultures in the laboratory often is assessed informally with a quick flick of the wrist: dense suspensions of microorganisms produce translucent "swirls" when agitated. Here, we rationalize the mechanism behind this phenomenon and show that the same process may affect the propagation of light through the upper ocean. Analogous to the shaken test tubes, the ocean can be characterized by intense fluid motion and abundant microorganisms. We demonstrate that the swirl patterns arise when elongated microorganisms align preferentially in the direction of fluid flow and alter light scattering. Using a combination of experiments and mathematical modeling, we find that this phenomenon can be recurrent under typical marine conditions. Moderate shear rates (0.1 s(-1)) can increase optical backscattering of natural microbial assemblages by more than 20%, and even small shear rates (0.001 s(-1)) can increase backscattering from blooms of large phytoplankton by more than 30%. These results imply that fluid flow, currently neglected in models of marine optics, may exert an important control on light propagation, influencing rates of global carbon fixation and how we estimate these rates via remote sensing.

  20. Slow light propagation in a thin optical fiber via electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Patnaik, Anil K.; Liang, J.Q.; Hakuta, K.

    2002-01-01

    We propose a configuration that utilizes electromagnetically induced transparency (EIT) to tailor a fiber mode propagating inside a thin optical fiber and coherently control its dispersion properties to drastically reduce the group velocity of the fiber mode. The key to this proposal is that the evanescent field of the thin fiber strongly couples with the surrounding active medium, so that the EIT condition is met by the medium. We show how the properties of the fiber mode are modified due to the EIT medium, both numerically and analytically. We demonstrate that the group velocity of the modified fiber mode can be drastically reduced (≅44 m/sec) using the coherently prepared orthohydrogen doped in a matrix of parahydrogen crystal as the EIT medium

  1. Evaluating Alternative Fuel Vehicles from Technical, Environmental and Economic Perspectives: Case of Light-Duty Vehicles in Iran

    OpenAIRE

    Vahid Aryanpur; Ehsan Shafiei

    2012-01-01

    This paper presents an environmental and technoeconomic evaluation of light duty vehicles in Iran. A comprehensive well-to-wheel (WTW) analysis is applied to compare different automotive fuel chains, conventional internal combustion engines and innovative vehicle powertrains. The study examines the competitiveness of 15 various pathways in terms of energy efficiencies, GHG emissions, and levelized cost of different energy carriers. The results indicate that electric vehic...

  2. Photonic crystals, light manipulation, and imaging in complex nematic structures

    Science.gov (United States)

    Ravnik, Miha; Å timulak, Mitja; Mur, Urban; Čančula, Miha; Čopar, Simon; Žumer, Slobodan

    2016-03-01

    Three selected approaches for manipulation of light by complex nematic colloidal and non-colloidal structures are presented using different own custom developed theoretical and modelling approaches. Photonic crystals bands of distorted cholesteric liquid crystal helix and of nematic colloidal opals are presented, also revealing distinct photonic modes and density of states. Light propagation along half-integer nematic disclinations is shown with changes in the light polarization of various winding numbers. As third, simulated light transmission polarization micrographs of nematic torons are shown, offering a new insight into the complex structure characterization. Finally, this work is a contribution towards using complex soft matter in optics and photonics for advanced light manipulation.

  3. Engineering photonic and plasmonic light emission enhancement

    Science.gov (United States)

    Lawrence, Nathaniel

    Semiconductor photonic devices are a rapidly maturing technology which currently occupy multi-billion dollar markets in the areas of LED lighting and optical data communication. LEDs currently demonstrate the highest luminous efficiency of any light source for general lighting. Long-haul optical data communication currently forms the backbone of the global communication network. Proper design of light management is required for photonic devices, which can increase the overall efficiency or add new device functionality. In this thesis, novel methods for the control of light propagation and confinement are developed for the use in integrated photonic devices. The first part of this work focuses on the engineering of field confinement within deep subwavelength plasmonic resonators for the enhancement of light-matter interaction. In this section, plasmonic ring nanocavities are shown to form gap plasmon modes confined to the dielectric region between two metal layers. The scattering properties, near-field enhancement and photonic density of states of nanocavity devices are studied using analytic theory and 3D finite difference time domain simulations. Plasmonic ring nanocavities are fabricated and characterized using photoluminescence intensity and decay rate measurements. A 25 times increase in the radiative decay rate of Er:Si02 is demonstrated in nanocavities where light is confined to volumes as small as 0.01( ln )3. The potential to achieve lasing, due to the enhancement of stimulated emission rate in ring nanocavities, is studied as a route to Si-compatible plasmon-enhanced nanolasers. The second part of this work focuses on the manipulation of light generated in planar semiconductor devices using arrays of dielectric nanopillars. In particular, aperiodic arrays of nanopillars are engineered for omnidirectional light extraction enhancement. Arrays of Er:SiNx, nanopillars are fabricated and a ten times increase in light extraction is experimentally demonstrated

  4. Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

    Directory of Open Access Journals (Sweden)

    Vojkan M. Radonjić

    2011-01-01

    Full Text Available Quality transmission of digital signals from a transmitting radio-relay device to a receiving one depends on the impact of environmental effects on the propagation of electromagnetic waves. In this paper some of the most important effects are explained and modeled, especially those characteristic for the frequency range within which the GRC 408E operates. The modeling resulted in the conclusions about the quality of transmission of digital signals in the GRC 408E radio-relay equipment. Propagation of electromagnetic waves A radio-relay link is achieved by direct electromagnetic waves, provided there is a line of sight between the transmitting and receiving antenna of a radio-relay device. Electromagnetic waves on the road are exposed to various environmental influences causing phenomena such as bending, reflection, refraction, absorption and multiple propagation. Due to these environmental effects, the quality of information transmission is not satisfactory and a radio-relay link is not reliable. The approach to the analysis of the quality of links in digital radiorelay devices is different from the one in analog radio-relay devices. Therefore, the quality is seen through errors in the received bit ( BER , the propagation conditions are taken into account, a reservation for the fading is determined by other means, etc.. Phenomena which accompany the propagation of electromagnetic waves in digital radio-relay links The propagation of direct EM waves is followed by the following phenomena: - attenuation due to propagation, - diffraction (changing table, - refraction (refraction, - reflection (refusing, - absorption (absorption and - multiple wave propagation. Each of these has a negative effect on the quality of the received signal at the receiving antenna of the radio-relay device. Attenuation due to propagation of electromagnetic waves The main parameter for evaluating the quality of radio-relay links is the level of the field at the reception

  5. 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

  6. Influence of light absorption on relativistic self-focusing of Gaussian laser beam in cold quantum plasma

    Science.gov (United States)

    Patil, S. D.; Valkunde, A. T.; Vhanmore, B. D.; Urunkar, T. U.; Gavade, K. M.; Takale, M. V.

    2018-05-01

    When inter particle distance is comparable to the de Broglies wavelength of charged particles, quantum effects in plasmas are unavoidable. We have exploited an influence of light absorption on self-focusing of Gaussian laser beam in cold quantum plasma by considering relativistic nonlinearity. Nonlinear differential equation governing beam-width parameter has been established by using parabolic equation approach under paraxial and WKB approximations. The effect of light absorption on variation of beam-width parameter with dimensionless distance of propagation is presented graphically and discussed. It is found that light absorption plays vital role in weakening the relativistic self-focusing of laser beam during propagation in cold quantum plasma and gives reasonably interesting results.

  7. Pulse propagation dynamics in the presence of a continuous-wave field

    International Nuclear Information System (INIS)

    Dimitrijević, Jelena; Arsenović, Dušan; Jelenković, Branislav M

    2013-01-01

    We present theoretical results for the propagation dynamics of an electromagnetic field pulse through rubidium vapor, while another field, a continuous-wave electromagnetic field, is present. The frequencies of both electromagnetic fields are resonant with the transition between the ground and excited state hyperfine levels of Rb, F g  → F e  = F g  ± 1. Detuning from resonance is done by the magnetic field oriented along the light propagation direction (Hanle configuration). When both the electromagnetic fields are simultaneously interacting with Rb atoms, either electromagnetically induced transparency or absorption is induced. Propagation dynamics was obtained solving the set of Maxwell–Bloch equations for the interacting atoms with two electromagnetic fields. Motivated by recent results (Brazhnikov et al 2011 Eur. Phys. J. D 63 315–25; Brazhnikov et al 2010 JETP Lett. 91 625–9; Kou et al 2011 Phys. Rev. A 84 063807), we have analyzed the influence of experimental parameters, laser polarization, and mutual phases between lasers, which can lead to optical switching, i.e. the transformation from electromagnetically induced absorption to transparency and vice versa. (paper)

  8. Towards a deep understanding of malware propagation in online social networks

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Guanhua [Los Alamos National Laboratory; Eidenbenz, Stephan [Los Alamos National Laboratory; Chen, Guanling [U OF MASSACHUSETTS LOWELL; Li, Nan [U OF MASSACHUSETTS LOWELL

    2009-01-01

    Online social networks, which have been expanding at a blistering speed in the recent years, have emerged as a popular communication infrastructure for Internet users. Meanwhile, malware that specifically targets these online social networks are also on the rise. In this work, we aim to investigate the characteristics of malware propagation in online social networks. Our study is based on a dataset collected from a real-world location-based online social network. We analyze the social structure and user activity patterns of this network. We further use extensive trace-driven simulation to study the impact of initial infection, user click probability, social structure, and activity patterns on malware propagation in online social networks. The results from this work has greatly deepened our understanding of the nature of online social network malware and also shed light on how to defend against them effectively.

  9. Slow light based on material and waveguide dispersion

    DEFF Research Database (Denmark)

    Nielsen, Torben Roland; Lavrinenko, Andrei; Mørk, Jesper

    2009-01-01

    We study slow light pulse propagation in a photonic crystal structure consisting of a dispersive and absorptive dielectric material and compare it with the constant wave case. The group index and the trasmission are investigated for the example of an ensemble of semiconductor quantum dots embedded...

  10. Superluminal two-color light in a multiple Raman gain medium

    KAUST Repository

    Kudriašov, V.

    2014-09-17

    We investigate theoretically the formation of two-component light with superluminal group velocity in a medium controlled by four Raman pump fields. In such an optical scheme only a particular combination of the probe fields is coupled to the matter and exhibits superluminal propagation; the orthogonal combination is uncoupled. The individual probe fields do not have a definite group velocity in the medium. Calculations demonstrate that this superluminal component experiences an envelope advancement in the medium with respect to the propagation in vacuum.

  11. Superluminal two-color light in a multiple Raman gain medium

    KAUST Repository

    Kudriašov, V.; Ruseckas, J.; Mekys, A.; Ekers, Aigars; Bezuglov, N.; Juzeliūnas, G.

    2014-01-01

    We investigate theoretically the formation of two-component light with superluminal group velocity in a medium controlled by four Raman pump fields. In such an optical scheme only a particular combination of the probe fields is coupled to the matter and exhibits superluminal propagation; the orthogonal combination is uncoupled. The individual probe fields do not have a definite group velocity in the medium. Calculations demonstrate that this superluminal component experiences an envelope advancement in the medium with respect to the propagation in vacuum.

  12. 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.

  13. Integration of Enhanced Propagation, Environmental Variability, and Network Performance Models into the InfraMAP Software Toolkit

    National Research Council Canada - National Science Library

    Norris, David; Gibson, Robert

    2007-01-01

    ... infrasonic networks. New propagation modeling features include a high altitude, low frequency absorption model, a synthetic waveform generator from ray tracing, and an improved Parabolic Equation (PE...

  14. Studies in ambient intelligent lighting

    NARCIS (Netherlands)

    Sekulovski, D.

    2013-01-01

    The revolution in lighting we are arguably experiencing is led by technical developments in the area of solid state lighting technology. The improved lifetime, efficiency and environmentally friendly raw materials make LEDs the main contender for the light source of the future. The core of the

  15. Nonlinear gap junctions enable long-distance propagation of pulsating calcium waves in astrocyte networks.

    Directory of Open Access Journals (Sweden)

    Mati Goldberg

    Full Text Available A new paradigm has recently emerged in brain science whereby communications between glial cells and neuron-glia interactions should be considered together with neurons and their networks to understand higher brain functions. In particular, astrocytes, the main type of glial cells in the cortex, have been shown to communicate with neurons and with each other. They are thought to form a gap-junction-coupled syncytium supporting cell-cell communication via propagating Ca(2+ waves. An identified mode of propagation is based on cytoplasm-to-cytoplasm transport of inositol trisphosphate (IP(3 through gap junctions that locally trigger Ca(2+ pulses via IP(3-dependent Ca(2+-induced Ca(2+ release. It is, however, currently unknown whether this intracellular route is able to support the propagation of long-distance regenerative Ca(2+ waves or is restricted to short-distance signaling. Furthermore, the influence of the intracellular signaling dynamics on intercellular propagation remains to be understood. In this work, we propose a model of the gap-junctional route for intercellular Ca(2+ wave propagation in astrocytes. Our model yields two major predictions. First, we show that long-distance regenerative signaling requires nonlinear coupling in the gap junctions. Second, we show that even with nonlinear gap junctions, long-distance regenerative signaling is favored when the internal Ca(2+ dynamics implements frequency modulation-encoding oscillations with pulsating dynamics, while amplitude modulation-encoding dynamics tends to restrict the propagation range. As a result, spatially heterogeneous molecular properties and/or weak couplings are shown to give rise to rich spatiotemporal dynamics that support complex propagation behaviors. These results shed new light on the mechanisms implicated in the propagation of Ca(2+ waves across astrocytes and the precise conditions under which glial cells may participate in information processing in the brain.

  16. New features on the environmental regulation of metabolism revealed by modeling the cellular proteomic adaptations induced by light, carbon and inorganic nitrogen in Chlamydomonas reinhardtii

    Directory of Open Access Journals (Sweden)

    Stéphanie Gérin

    2016-08-01

    Full Text Available Microalgae are currently emerging to be very promising organisms for the production of biofuels and high-added value compounds. Understanding the influence of environmental alterations on their metabolism is a crucial issue. Light, carbon and nitrogen availability have been reported to induce important metabolic adaptations. So far, the influence of these variables has essentially been studied while varying only one or two environmental factors at the same time. The goal of the present work was to model the cellular proteomic adaptations of the green microalga Chlamydomonas reinhardtii upon the simultaneous changes of light intensity, carbon concentrations (CO2 and acetate and inorganic nitrogen concentrations (nitrate and ammonium in the culture medium. Statistical design of experiments (DOE enabled to define 32 culture conditions to be tested experimentally. Relative protein abundance was quantified by two dimensional differential in-gel electrophoresis (2D-DIGE. Additional assays for respiration, photosynthesis, and lipid and pigment concentrations were also carried out. A hierarchical clustering survey enabled to partition biological variables (proteins + assays into eight co-regulated clusters. In most cases, the biological variables partitioned in the same cluster had already been reported to participate to common biological functions (acetate assimilation, bioenergetic processes, light harvesting, Calvin cycle and protein metabolism. The environmental regulation within each cluster was further characterized by a series of multivariate methods including principal component analysis and multiple linear regressions. This metadata analysis enabled to highlight the existence of a clear regulatory pattern for every cluster and to mathematically simulate the effects of light, carbon and nitrogen. The influence of these environmental variables on cellular metabolism is described in details and thoroughly discussed. This work provides an overview

  17. Defocusing of an ion beam propagating in background plasma due to two-stream instability

    Energy Technology Data Exchange (ETDEWEB)

    Tokluoglu, Erinc; Kaganovich, Igor D. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2015-04-15

    The current and charge neutralization of charged particle beams by background plasma enable ballistic beam propagation and have a wide range of applications in inertial fusion and high energy density physics. However, the beam-plasma interaction can result in the development of collective instabilities that may have deleterious effects on ballistic propagation of an ion beam. In the case of fast, light-ion beams, non-linear fields created by instabilities can lead to significant defocusing of the beam. We study an ion beam pulse propagating in a background plasma, which is subjected to two-stream instability between the beam ions and plasma electrons, using PIC code LSP. The defocusing effects of the instability on the beam can be much more pronounced in small radius beams. We show through simulations that a beamlet produced from an ion beam passed through an aperture can be used as a diagnostic tool to identify the presence of the two-stream instability and quantify its defocusing effects. The effect can be observed on the Neutralized Drift Compression Experiment-II facility by measuring the spot size of the extracted beamlet propagating through several meters of plasma.

  18. Development of fatigue crack propagation models for engineering applications at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Tomkins, B.

    1975-05-01

    The value of modelling the fatigue crack propagation process is discussed and current models are examined in the light of increasing knowledge of crack tip deformation. Elevated temperature fatigue is examined in detail as an area in which models could contribute significantly to engineering design. A model is developed which examines the role of time-dependent creep cavitation on the failure process in an interactive creep-fatigue situation. (auth)

  19. Simulating non-Kolmogorov turbulence phase screens based on equivalent structure constant and its influence on simulations of beam propagation

    Directory of Open Access Journals (Sweden)

    Ming Chen

    Full Text Available Gaussian distribution is used to describe the power law along the propagation path and phase screen of the non-Kolmogorov turbulence is proposed based on the equivalent refractive-index structure constants. Various simulations of Gaussian beam propagation in Kolmogorov and non-Kolmogorov turbulence are used for telling the difference between isotropic and anisotropic turbulence. The results imply that the non-Kolmogorov turbulence makes a great influence on the simulations via power law in spectrum and the number of phase screens. Furthermore, the influence is mainly reflected in light intensity and beam drift. Statistics suggest that when Gaussian beam propagate through single phase screen of non-Kolmogorov, maximum and uniformity of light intensity increase first and then decrease with power law, and beam drift firstly increases and then to stabilize. When Gaussian beam propagate through multiple phase screens, relative errors of beam drift decrease with the number of phase screens. And scintillation indices in non-Kolmogorov turbulence is larger than that in Kolmogorov turbulence when the number is small. When the number is big, the scintillation indices in non-Kolmogorov turbulence is smaller than that in Kolmogorov turbulence. The results shown in this paper demonstrate the effect of the non-Kolmogorov turbulence on laser atmospheric transmissions. Thus, this paper suggests a possible direction of the improvement of the laser transmission accuracy over a long distance through the atmosphere.

  20. On the possibility of superluminal energy propagation in a hyperbolic metamaterial of metal-dielectric layers

    Directory of Open Access Journals (Sweden)

    Pi-Gang Luan

    2018-01-01

    Full Text Available The energy propagation of electromagnetic fields in the effective medium of a one-dimensional photonic crystal consisting of dielectric and metallic layers is investigated. We show that the medium behaves like Drude and Lorentz medium, respectively, when the electric field is parallel and perpendicular to the layers. For arbitrary time-varying electromagnetic fields in this medium, the energy density formula is derived. We prove rigorously that the group velocity of any propagating mode obeying the hyperbolic dispersion must be slower than the speed of light in vacuum, taking into account the frequency dependence of the permittivity tensor. That is, it is not possible to have superluminal propagation in this dispersive hyperbolic medium consisting of real dielectric and metallic material layers. The propagation velocity of a wave packet is also studied numerically. This packet velocity is very close to the velocity of the propagating mode having the central frequency and central wave vector of the wave packet. When the frequency spread of the wave packet is not narrow enough, small discrepancy between these two velocities manifests, which is caused by the non-penetration effect of the evanescent modes. This work reveals that no superluminal phenomenon can happen in a dispersive anisotropic metamaterial medium made of real materials.

  1. 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)

  2. Instantaneous interactions of hadrons on the light cone

    International Nuclear Information System (INIS)

    Hyer, T.

    1994-01-01

    Hadron wave functions are most naturally defined in the framework of light-cone quantization, a Hamiltonian formulation quantized at equal light-cone ''time'' τ≡t+z. One feature of the light-cone perturbation theory is the presence of instantaneous interactions, which complicate the consideration of processes involving bound states. We show that these interactions can be written in a simple and general form, parametrized by an instantaneous contribution ψ to the hadronic wave function. We use the rotational invariance of Feynman diagrams to relate this instantaneous piece of the meson wave function to the propagating part, and to obtain constraints relating wave functions and quark fragmentation amplitudes

  3. Nonclassical-light generation in a photonic-band-gap nonlinear planar waveguide

    International Nuclear Information System (INIS)

    Perina, Jan Jr.; Sibilia, Concita; Tricca, Daniela; Bertolotti, Mario

    2004-01-01

    The optical parametric process occurring in a photonic-band-gap planar waveguide is studied from the point of view of nonclassical-light generation. The nonlinearly interacting optical fields are described by the generalized superposition of coherent signals and noise using the method of operator linear corrections to a classical strong solution. Scattered backward-propagating fields are taken into account. Squeezed light as well as light with sub-Poissonian statistics can be obtained in two-mode fields under the specified conditions

  4. The Influence of Environmental Spatial Layout on Perceived Lightness

    Science.gov (United States)

    Kanari, Kei; Inagami, Makoto; Kaneko, Hirohiko

    2011-01-01

    It is obvious that perceived lightness of a surface depends on the surrounding luminance distribution in 2D and 3D. These effects are usually explained by the mechanisms at relatively low level of visual system. However, there seems to be a relation between the illuminance and spatial layout of the scene regardless of the surrounding luminance distribution. If this is valid, perceived lightness of a surface in the scene could be influenced by the spatial layout in the scene. In this research, we investigated the relation between the perceived lightness of surface and the spatial layout of the scene. The subject matched the lightness of test patch presented on a natural picture with various spatial layout to that of comparison stimulus presented on a uniform gray background. The mean luminance of the surround stimuli were the same and the local contrast between the text patch and the surround was kept constant. Results showed that the perceived lightness of a stimulus depended on the spatial structure presented in the background. This result indicates that the spatial layout of the scene is related to the illuminance of that and influenced on perceived lightness.

  5. Some features of light propagation through layers with a complex refractive index

    International Nuclear Information System (INIS)

    Efimov, V.V.; Sementsov, D.I.

    1994-01-01

    By solving Maxwell's equations, expressions are obtained for the energy fluxes both inside and outside a layer with a complex refractive index at normal incidence of light. It is shown that inside the layer, along with fluxes of forward and backward waves, an interference flux can be distinguished whose magnitude is proportional to the imaginary part of the refractive index. A detailed numerical analysis of the energy transmission (T) and reflection (R) coefficients versus the thickness of the layer with negative absorption is performed for normal incidence of light onto the layer surface. Total distribution of the energy flux over the layer thickness is considered both for absorbing and amplifying layers. 13 refs., 4 figs

  6. Shedding light on diatom photonics by means of digital holography.

    Science.gov (United States)

    Di Caprio, Giuseppe; Coppola, Giuseppe; De Stefano, Luca; De Stefano, Mario; Antonucci, Alessandra; Congestri, Roberta; De Tommasi, Edoardo

    2014-05-01

    Diatoms are among the dominant phytoplankters in the world's oceans, and their external silica investments, resembling artificial photonic crystals, are expected to play an active role in light manipulation. Digital holography allowed studying the interaction with light of Coscinodiscus wailesii cell wall reconstructing the light confinement inside the cell cytoplasm, condition that is hardly accessible via standard microscopy. The full characterization of the propagated beam, in terms of quantitative phase and intensity, removed a long-standing ambiguity about the origin of the light confinement. The data were discussed in the light of living cell behavior in response to their environment. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Theory of light transfer in food and biological materials

    Science.gov (United States)

    In this chapter, we first define the basic radiometric quantities that are needed for describing light propagation in food and biological materials. Radiative transfer theory is then derived, according to the principle of the conservation of energy. Because the radiative transfer theory equation is ...

  8. Studies on laser beam propagation and stimulated scattering in multiple beam experiments

    International Nuclear Information System (INIS)

    Labaune, C.; Lewis, K.; Bandulet, H.; Lewis, K.; Depierreux, S.; Huller, S.; Masson-Laborde, P.E.; Pesme, D.; Riazuelo, G.

    2006-01-01

    The propagation and stimulated scattering of intense laser beams interacting with underdense plasmas are two important issues for inertial confinement fusion (ICF). The purpose of this work was to perform experiments under well-controlled interaction conditions and confront them with numerical simulations to test the physics included in the codes. Experimental diagnostics include time and space resolved images of incident and SBS light and of SBS-ion acoustic activity. New numerical diagnostics, including similar constraints as the experimental ones and the treatment of the propagation of the light between the emitting area and the detectors, have been developed. Particular care was put to include realistic plasma density and velocity profiles, as well as laser pulse shape in the simulations. In the experiments presented in this paper, the interaction beam was used with a random phase plate (RPP) to produce a statistical distribution of speckles in the focal volume. Stimulated Brillouin Scattering (SBS) was described using a decomposition of the spatial scales which provides a predictive modeling of SBS in an expanding mm-scale plasma. Spatial and temporal behavior of the SBS-ion acoustic waves was found to be in good agreement with the experimental ones for two laser intensities. (authors)

  9. Road lighting for safety.

    NARCIS (Netherlands)

    Schreuder, D.A.

    2000-01-01

    This book is aimed at broad readership, not especially at lighting experts. Lighting is presented as a system, as part of the public highway. Much attention is paid to subjects not greatly covered in the specialist literature, such as environmental aspects, traffic safety, crime prevention, and the

  10. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products Part 2: LED Manufacturing and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Scholand, Michael; Dillon, Heather E.

    2012-05-01

    Part 2 of the project (this report) uses the conclusions from Part 1 as a point of departure to focus on two objectives: producing a more detailed and conservative assessment of the manufacturing process and providing a comparative LCA with other lighting products based on the improved manufacturing analysis and taking into consideration a wider range of environmental impacts. In this study, we first analyzed the manufacturing process for a white-light LED (based on a sapphire-substrate, blue-light, gallium-nitride LED pumping a yellow phosphor), to understand the impacts of the manufacturing process. We then conducted a comparative LCA, looking at the impacts associated with the Philips Master LEDbulb and comparing those to a CFL and an incandescent lamp. The comparison took into account the Philips Master LEDbulb as it is now in 2012 and then projected forward what it might be in 2017, accounting for some of the anticipated improvements in LED manufacturing, performance and driver electronics.

  11. Radio propagation and adaptive antennas for wireless communication networks

    CERN Document Server

    Blaunstein, Nathan

    2014-01-01

    Explores novel wireless networks beyond 3G, and advanced 4G technologies, such as MIMO, via propagation phenomena and the fundamentals of adapted antenna usage.Explains how adaptive antennas can improve GoS and QoS for any wireless channel, with specific examples and applications in land, aircraft and satellite communications.Introduces new stochastic approach based on several multi-parametric models describing various terrestrial scenarios, which have been experimentally verified in different environmental conditionsNew chapters on fundamentals of wireless networks, cellular and non-cellular,

  12. Change of Measure between Light Travel Time and Euclidean Distances

    Directory of Open Access Journals (Sweden)

    Heymann Y.

    2013-04-01

    Full Text Available The problem of cosmological distances is approached using a method based on the propagation of light in an expanding Universe. From the chan ge of measure between Light Travel Time and Euclidean Distances, a formula is deri ved to compute distances as a function of redshift. This formula is identical to Matti g’s formula (with q 0 = 1 / 2 which is based on Friedmann’s equations of general relativi ty.

  13. An Investigation of the Sub-Microsecond Features of Dynamic Crack Propagation in PMMA and the Rdx-Based Explosive PBX 9205

    Science.gov (United States)

    Washabaugh, P. D.; Hill, L. G.

    2007-12-01

    A dynamic crack propagating in a brittle material releases enough thermal energy to produce visible light. The dynamic fracture of even macroscopically amorphous materials becomes unsteady as the crack propagation velocity approaches the material wave-speeds. The heat generated at a crack-tip, especially as it jumps, may be a mechanism to initiate a self-sustaining reaction in an energetic material. Experiments were conducted in specimens to simulate an infinite plate for ˜10 μs. The initial specimens were 152 mm square by 6 mm thick acrylic sheets, and were fabricated to study non-steady near-wave-speed crack propagation. A variant of this specimen embedded a 25 mm×3 mm PBX 9205 pellet to explore the influence of dynamic Mode-I cracks in these materials. The crack was initiated by up to 0.24 g of Detasheet placed along a precursor 50 mm long notch, with a shield to contain the reaction products and prevent propagation along the fractured surfaces. The crack was studied by means of a streak camera and a Fourier-filter of the light reflecting off the newly minted surfaces. The sub-microsecond behavior of holes initiating, preceding and coalescing with the main crack were observed in the PMMA samples. The embedding and mechanical loading of explosives by this technique did not initiate a self-sustaining reaction in preliminary testing.

  14. Pump-beam-instability limits to Raman-gain-doublet ''fast-light'' pulse propagation

    International Nuclear Information System (INIS)

    Stenner, Michael D.; Gauthier, Daniel J.

    2003-01-01

    We investigate the behavior of a system for generating ''fast-light'' pulses in which a bichromatic Raman pumping beam is used to generate optical gain at two frequencies and a region of anomalous dispersion between them. It is expected that increasing the gain will increase the pulse advancement. However, as the gain increases, the pumping field becomes increasingly distorted, effectively limiting the pulse advancement. We observe as much as 12% of the input pump power converted to orthogonal polarization, broadening of the initially bichromatic pump field (25 MHz initial frequency separation) to more than 2.5 GHz, and a temporal collapse of the pump beam into an erratic train of sub-500-ps pulses. The instability is attributed to the combined effects of the cross modulation instability and stimulated Raman scattering. Extreme distortion of an injected pulse that should (absent the instability) experience an advancement of 21% of its width is observed. We conclude that the fast-light pulse advancement is limited to just a few percent of the pulse width using this pulse advancement technique. The limitation imposed by the instability is important because careful study of the information velocity in fast-light pulses requires that pulse advancement be large enough to distinguish the velocities of different pulse features. Possible methods for achieving pulse advancement by avoiding the distortion caused by the instability are discussed

  15. Impact of the Diamond Light Source on research in Earth and environmental sciences: current work and future perspectives.

    Science.gov (United States)

    Burke, Ian T; Mosselmans, J Frederick W; Shaw, Samuel; Peacock, Caroline L; Benning, Liane G; Coker, Victoria S

    2015-03-06

    Diamond Light Source Ltd celebrated its 10th anniversary as a company in December 2012 and has now accepted user experiments for over 5 years. This paper describes the current facilities available at Diamond and future developments that enhance its capacities with respect to the Earth and environmental sciences. A review of relevant research conducted at Diamond thus far is provided. This highlights how synchrotron-based studies have brought about important advances in our understanding of the fundamental parameters controlling highly complex mineral-fluid-microbe interface reactions in the natural environment. This new knowledge not only enhances our understanding of global biogeochemical processes, but also provides the opportunity for interventions to be designed for environmental remediation and beneficial use.

  16. Derivation of the gauge link in light cone gauge

    International Nuclear Information System (INIS)

    Gao Jianhua

    2010-01-01

    In light cone gauge, a gauge link at light cone infinity is necessary for transverse momentum-dependent parton distribution to restore the gauge invariance in some specific boundary conditions. We derive such transverse gauge link in a more regular and general method. We find the gauge link at light cone infinity naturally arises from the contribution of the pinched poles: one is from the quark propagator and the other is hidden in the gauge vector field in light cone gauge. Actually, in the amplitude level, we have obtained a more general gauge link over the hypersurface at light cone infinity which is beyond the transverse direction. The difference of such gauge link between semi-inclusive deep inelastic scattering and Drell-Yan processes can also be obtained directly and clearly in our derivation.

  17. Evaluating potential spectral impacts of various artificial lights on melatonin suppression, photosynthesis, and star visibility.

    Directory of Open Access Journals (Sweden)

    Martin Aubé

    Full Text Available Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies.

  18. Modelling Elastic Scattering and Light Transport in 3D Collagen Gel Constructs

    National Research Council Canada - National Science Library

    Bixio, L

    2001-01-01

    A model of elastic scattering and light propagation is presented, which can be used to obtain the scattering coefficient, the index of refraction and the distribution of the collagen fibrils in a gel...

  19. Proceedings of the Twentieth NASA Propagation Experimenters Meeting (NAPEX XX) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

    Science.gov (United States)

    Golshan, Nassar (Editor)

    1996-01-01

    The NASA Propagation Experimenters (NAPEX) Meeting and associated Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop convene yearly to discuss studies supported by the NASA Propagation Program. Representatives from the satellite communications (satcom)industry, academia, and government with an interest in space-ground radio wave propagation have peer discussion of work in progress, disseminate propagation results, and interact with the satcom industry. NAPEX XX, in Fairbanks, Alaska, June 4-5, 1996, had three sessions: (1) "ACTS Propagation Study: Background, Objectives, and Outcomes," covered results from thirteen station-years of Ka-band experiments; (2) "Propagation Studies for Mobile and Personal Satellite Applications," provided the latest developments in measurement, modeling, and dissemination of propagation phenomena of interest to the mobile, personal, and aeronautical satcom industry; and (3)"Propagation Research Topics," covered a range of topics including space/ground optical propagation experiments, propagation databases, the NASA Propagation Web Site, and revision plans for the NASA propagation effects handbooks. The ACTS Miniworkshop, June 6, 1996, covered ACTS status, engineering support for ACTS propagation terminals, and the ACTS Propagation Data Center. A plenary session made specific recommendations for the future direction of the program.

  20. UV waveguides light fabricated in fluoropolymer CYTOP by femtosecond laser direct writing.

    Science.gov (United States)

    Hanada, Yasutaka; Sugioka, Koji; Midorikawa, Katsumi

    2010-01-18

    We have fabricated optical waveguides inside the UV-transparent polymer, CYTOP, by femtosecond laser direct writing for propagating UV light in biochip applications. Femtosecond laser irradiation is estimated to increase the refractive index of CYTOP by 1.7 x 10(-3) due to partial bond breaking in CYTOP. The waveguide in CYTOP has propagation losses of 0.49, 0.77, and 0.91 dB/cm at wavelengths of 632.8, 355, and 266 nm, respectively.

  1. Correlation between observation task performance and visual acuity, contrast sensitivity and environmental light in a simulated maritime study.

    Science.gov (United States)

    Koefoed, Vilhelm F; Assmuss, Jörg; Høvding, Gunnar

    2018-03-25

    To examine the relevance of visual acuity (VA) and index of contrast sensitivity (ICS) as predictors for visual observation task performance in a maritime environment. Sixty naval cadets were recruited to a study on observation tasks in a simulated maritime environment under three different light settings. Their ICS were computed based on contrast sensitivity (CS) data recorded by Optec 6500 and CSV-1000E CS tests. The correlation between object identification distance and VA/ICS was examined by stepwise linear regression. The object detection distance was significantly correlated to the level of environmental light (p maritime environment may presumably be ascribed to the normal and uniform visual capacity in all our study subjects. © 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  2. Tropospheric radiowave propagation beyond the horizon

    CERN Document Server

    Du Castel, François

    1966-01-01

    Tropospheric Radiowave Propagation Beyond the Horizon deals with developments concerning the tropospheric propagation of ultra-short radio waves beyond the horizon, with emphasis on the relationship between the theoretical and the experimental. Topics covered include the general conditions of propagation in the troposphere; general characteristics of propagation beyond the horizon; and attenuation in propagation. This volume is comprised of six chapters and begins with a brief historical look at the various stages that have brought the technique of transhorizon links to its state of developmen

  3. Design of a multifiber light delivery system for photoacoustic-guided surgery

    Science.gov (United States)

    Eddins, Blackberrie; Bell, Muyinatu A. Lediju

    2017-04-01

    This work explores light delivery optimization for photoacoustic-guided minimally invasive surgeries, such as the endonasal transsphenoidal approach. Monte Carlo simulations were employed to study three-dimensional light propagation in tissue, comprising one or two 4-mm diameter arteries located 3 mm below bone, an absorbing metallic drill contacting the bone surface, and a single light source placed next to the 2.4-mm diameter drill shaft with a 2.9-mm diameter spherical drill tip. The optimal fiber distance from the drill shaft was determined from the maximum normalized fluence to the underlying artery. Using this optimal fiber-to-drill shaft distance, Zemax simulations were employed to propagate Gaussian beams through one or more 600 micron-core diameter optical fibers for detection on the bone surface. When the number of equally spaced fibers surrounding the drill increased, a single merged optical profile formed with seven or more fibers, determined by thresholding the resulting light profile images at 1/e times the maximum intensity. We used these simulations to inform design requirements, build a one to seven multifiber light delivery prototype to surround a surgical drill, and demonstrate its ability to simultaneously visualize the tool tip and blood vessel targets in the absence and presence of bone. The results and methodology are generalizable to multiple interventional photoacoustic applications.

  4. Metal-clad waveguide characterization for contact-based light transmission into tissue

    Science.gov (United States)

    Chininis, Jeffrey; Whiteside, Paul; Hunt, Heather K.

    2016-02-01

    As contemporary laser dermatology procedures, like tattoo removal and skin resurfacing, become more popular, the complications of their operation are also becoming more prevalent. Frequent incidences of over-exposure, ocular injury, and excessive thermal damage represent mounting concerns for those seeking such procedures; moreover, each of these problems is a direct consequence of the standard, free-space method of laser transmission predominantly used in clinical settings. Therefore, an alternative method of light transmission is needed to minimize these problems. Here, we demonstrate and characterize an alternative method that uses planar waveguides to deliver light into sample tissue via direct contact. To do this, slab substrates made from glass were clad in layers of titanium and silver, constraining the light within the waveguide along the waveguide's length. By creating active areas on the waveguide surface, the propagating light could then optically tunnel into the tissue sample, when the waveguide was brought into contact with the tissue. SEM and EDS were used to characterize the metal film thickness and deposition rates onto the glass substrates. Laser light from a Q-switched Nd:YAG source operating at 532nm was coupled into the waveguide and transmitted into samples of pig skin. The amount of light transmitted was measured using photoacoustics techniques, in conjunction with a photodiode and integrating sphere. Transmitting light into tissue in this manner effectively resolves or circumvents the complications caused by free-space propagation methods as it reduces the operating distance to 0, which prevents hazardous back-reflections and allows for the ready incorporation of contact cooling technologies.

  5. 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.

  6. Propagation phenomena in real world networks

    CERN Document Server

    Fay, Damien; Gabryś, Bogdan

    2015-01-01

    Propagation, which looks at spreading in complex networks, can be seen from many viewpoints; it is undesirable, or desirable, controllable, the mechanisms generating that propagation can be the topic of interest, but in the end all depends on the setting. This book covers leading research on a wide spectrum of propagation phenomenon and the techniques currently used in its modelling, prediction, analysis and control. Fourteen papers range over topics including epidemic models, models for trust inference, coverage strategies for networks, vehicle flow propagation, bio-inspired routing algorithms, P2P botnet attacks and defences, fault propagation in gene-cellular networks, malware propagation for mobile networks, information propagation in crisis situations, financial contagion in interbank networks, and finally how to maximize the spread of influence in social networks. The compendium will be of interest to researchers, those working in social networking, communications and finance and is aimed at providin...

  7. Integrated single- and two-photon light sheet microscopy using accelerating beams

    DEFF Research Database (Denmark)

    Piksarv, Peeter; Marti, Dominik; Le, Tuan

    2017-01-01

    We demonstrate the first light sheet microscope using propagation invariant, accelerating Airy beams that operates both in single- and two-photon modes. The use of the Airy beam permits us to develop an ultra compact, high resolution light sheet system without beam scanning. In two-photon mode......, an increase in the field of view over the use of a standard Gaussian beam by a factor of six is demonstrated. This implementation for light sheet microscopy opens up new possibilities across a wide range of biomedical applications, especially for the study of neuronal processes....

  8. 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

  9. Waves in periodic medium. Atomic matter waves in light crystals

    International Nuclear Information System (INIS)

    Oberthaler, M. K.

    1997-07-01

    This work deals with the propagation of matter waves inside a periodic potential. In analogy to photon optics a potential can be described by a refractive index for matter waves. A real potential leads to a refractive spatial structure while an imaginary potential leads to an absorptive structure. A general theoretical description is given in the framework of Floquet theory. The equivalent approach of dynamical diffraction theory will be treated in detail. The analytic solution for weak potentials are given in a general form so that they are applicable for every kind of wave and medium. For our experiments an open two level atom (metastable Argon) propagating inside a standing light wave was used. Detuning the frequency of the light wave from the atomic resonance leads to a real (refractive) periodic potential. Tuning the laser exact on resonance gives rise to a pure imaginary (absorptive) periodic potential. In analogy to solid state crystals in X-ray and neutron optics we call a standing light wave a light crystal. Tuning the standing light field on resonance we demonstrated experimentally the Borrmann effect. This effect describes the increase of the total transmission through a crystal for Bragg incidence. Furthermore, we confirmed that this effect is coherent and that a sinusoidal wave field is formed inside the crystal. The nodes of the wave field were found to coincide with the maxima of absorption. For a detuned standing light field a refractive crystal was realized, for which the expected Pendelloesung effect was demonstrated. In this case the maximum of the wave field inside the crystal was found at the steepest gradient of the potential as predicted by dynamical diffraction theory. Superposing an absorptive and a refractive light crystal a complex light crystal was realized. With such a crystal the violation of Friedel's law was demonstrated in a very clear way. (author)

  10. Physics of quantum light emitters in disordered photonic nanostructures

    International Nuclear Information System (INIS)

    Garcia, P.D.; Lodahl, P.

    2017-01-01

    Nanophotonics focuses on the control of light and the interaction with matter by the aid of intricate nanostructures. Typically, a photonic nanostructure is carefully designed for a specific application and any imperfections may reduce its performance, i.e., a thorough investigation of the role of unavoidable fabrication imperfections is essential for any application. However, another approach to nanophotonic applications exists where fabrication disorder is used to induce functionalities by enhancing light-matter interaction. Disorder leads to multiple scattering of light, which is the realm of statistical optics where light propagation requires a statistical description. We review here the recent progress on disordered photonic nanostructures and the potential implications for quantum photonics devices. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Physics of quantum light emitters in disordered photonic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, P.D. [Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Barcelona (Spain); Lodahl, P. [Niels Bohr Institute, University of Copenhagen (Denmark)

    2017-08-15

    Nanophotonics focuses on the control of light and the interaction with matter by the aid of intricate nanostructures. Typically, a photonic nanostructure is carefully designed for a specific application and any imperfections may reduce its performance, i.e., a thorough investigation of the role of unavoidable fabrication imperfections is essential for any application. However, another approach to nanophotonic applications exists where fabrication disorder is used to induce functionalities by enhancing light-matter interaction. Disorder leads to multiple scattering of light, which is the realm of statistical optics where light propagation requires a statistical description. We review here the recent progress on disordered photonic nanostructures and the potential implications for quantum photonics devices. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Study of gamma propagation by using the ZEUS mono-kinetic code

    International Nuclear Information System (INIS)

    Vergnaud, Therese

    1969-10-01

    As studies of radiation protection often require the knowledge of heating due to capture gamma of thermal neutrons, the authors report an attempt of assessment of neutrons and γ propagation by using the same code (Zeus) which computes particle scattering by implementing a mono-kinetic Monte Carlo method. With this method, it is possible to study rather complex geometries and gamma source distributions directly obtained by a previous calculation of thermal neutrons. However, this method is not suitable for the study of energy degradation of gamma rays during their propagation. An approximate shock law is used to take shock-induced energy loss into account. This method is tested for different materials or media (either light like water and aluminium, or heavy like iron). Results are compared with those obtained by Goldstein with the method of moments. Results obtained by using Zeus are discussed: some of them appear to be over-estimated [fr

  13. ASSESSMENT OF IMPACT OF COHERENT LIGHT ON RESISTANCE OF PLANTS GROWING IN UNFAVOURABLE ENVIRONMENTAL CONDITIONS

    Directory of Open Access Journals (Sweden)

    Małgorzata Śliwka

    2014-04-01

    Full Text Available The results of experiments on the effect of the coherent light emitted by lasers on plant material show that properly selected laser stimulation parameters, such as: wavelength, power, time and type of exposure, allow to obtain a greater growth of plant biomass, changes in the content of elements in the biomass and increasing plant resistance to unfavorable environmental conditions. The aim of this study was to determine the effect of laser stimulation on selected plant species (Iris pseudoacorus L., Lemna minor L. to increase their resistance to low temperatures and the ability to adapt to an environment polluted by mining activities (Phelum pratense L.. Plants from experimental groups (Iris pseudoacorus L., Phelum pratense L., Lemna minor L. were stimulated with coherent light with specific characteristics. To irradiate plants from experimental groups different algorithms of stimulation parameters, differentiating the method and time of exposure were used. Plants group without the stimulation, were the reference group. The article discusses the results of preliminary experiments carried out on a laboratory scale and pot experiments.

  14. 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,...

  15. An initial investigation of the sub-microsecond features of dynamic crack propagation in PMMA and the RDX-based explosive PBX 9205

    Science.gov (United States)

    Washabaugh, Peter; Hill, Larry

    2007-06-01

    A dynamic crack propagating in a brittle material releases enough thermal energy to produce visible light. The dynamic fracture of even macroscopically amorphous materials becomes unsteady as the crack propagation velocity approaches the material wave-speeds. The heat generated at a crack-tip, especially as it jumps, may be a mechanism to initiate a self-sustaining reaction in an energetic material. Experiments were conducted in specimens to simulate an infinite plate for 20 μs. The initial specimens were 152 mm square by 6 mm thick acrylic sheets, and were fabricated to study non-steady near-wave-speed crack propagation. A variant of this specimen embedded a 25 mm x 3 mm PBX 9205 pellet to explore the influence of dynamic Mode-I cracks in these materials. The crack was initiated by up to 0.2 g of Detasheet placed along a precursor 50 mm long notch, with a shield to contain the reaction products and prevent propagation along the fractured surfaces. The crack was studied by means of a streak camera and a Fourier-filter of the light reflecting off the newly minted surfaces. The sub-microsecond behavior of holes initiating, preceding and coalescing with the main crack were observed in the PMMA samples. The embedding and mechanical loading of explosives by this technique did not initiate a self-sustaining reaction in preliminary testing.

  16. Route-asymmetrical light transmission of a fiber-chip-fiber optomechanical system

    DEFF Research Database (Denmark)

    Liu, Li; Ding, Yunhong; Cai, Xinlun

    2016-01-01

    In this paper, we proposed and experimentally demonstrated a route-asymmetrical light transmission scheme based on the thermal radiative effect, which means that forward and backward propagations of an optical device have different transmittances provided they are not present simultaneously. Empl...

  17. Schrodinger cat state generation using a slow light

    International Nuclear Information System (INIS)

    Ham, B. S.; Kim, M. S.

    2003-01-01

    We show a practical application of giant Kerr nonlinearity to quantum information processing based on superposition of two distinct macroscopic states- Schrodinger cat state. The giant Kerr nonlinearity can be achieved by using electromagnetically induced transparency, in which light propagation should be slowed down so that a pi-phase shift can be easily obtained owing to increased interaction time.

  18. A fast algorithm for the computation of incoherent propagation loss for variable water depth : A validation study

    NARCIS (Netherlands)

    Sertlek, H.O.; Ainslie, M.A.

    2014-01-01

    Accurate and fast estimation of propagation loss (PL) is needed for simulations of sonar or acoustic communication performance, and for environmental risk assessment. Accurate calculation of PL in range dependent and lossy waveguides can require computationally expensive wave theory techniques . In

  19. Unidirectional THz radiation propagation in BiFeO3

    Science.gov (United States)

    Room, Toomas

    The mutual coupling between magnetism and electricity present in many multiferroic materials permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to write a magnetic state current-free by an electric voltage would provide a huge technological advantage. However, ME coupling changes the low energy electrodynamics of these materials in unprecedented way - optical ME effects give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. The transparent direction can be switched with dc magnetic or electric field, thus opening up new possibilities to manipulate the propagation of electromagnetic waves in multiferroic materials. We studied the unidirectional transmission of THz radiation in BiFeO3 crystals, the unique multiferroic compound offering a real potential for room temperature applications. The electrodynamics of BiFeO3 at 1THz and below is dominated by the spin wave modes of cycloidal spin order. We found that the optical magnetoelectric effect generated by spin waves in BiFeO3 is robust enough to cause considerable nonreciprocal directional dichroism in the GHz-THz range even at room temperature. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. Our work demonstrates that the nonreciprocal directional dichroism spectra of low energy excitations and their theoretical analysis provide microscopic model of ME couplings in multiferroic materials. Recent THz spectroscopy studies of multiferroic materials are an important step toward the realization of optical diodes, devices which transmit light in one but not in the opposite direction.

  20. Fatigue crack propagation behavior under creep conditions

    International Nuclear Information System (INIS)

    Ohji, Kiyotsugu; Kubo, Shiro

    1991-01-01

    The crack propagation behavior of the SUS 304 stainless steel under creep-fatigue conditions was reviewed. Cracks propagated either in purely time-dependent mode or in purely cycle-dependent mode, depending on loading conditions. The time-dependent crack propagation rate was correlated with modified J-integral J * and the cycle-dependent crack propagation rate was correlated with J-integral range ΔJ f . Threshold was observed in the cycle-dependent crack propagation, and below this threshold the time-dependent crack propagation appeared. The crack propagation rates were uniquely characterized by taking the effective values of J * and ΔJ f , when crack closure was observed. Change in crack propagation mode occurred reversibly and was predicted by the competitive damage model. The threshold disappeared and the cycle-dependent crack propagation continued in a subthreshold region under variable amplitude conditions, where the threshold was interposed between the maximum and minimum ΔJ f . (orig.)

  1. Visualizing light with electrons

    Science.gov (United States)

    Fitzgerald, J. P. S.; Word, R. C.; Koenenkamp, R.

    2014-03-01

    In multiphoton photoemission electron microscopy (nP-PEEM) electrons are emitted from surfaces at a rate proportional to the surface electromagnetic field amplitude. We use 2P-PEEM to give nanometer scale visualizations of light of diffracted and waveguide fields around various microstructures. We use Fourier analysis to determine the phase and amplitude of surface fields in relation to incident light from the interference patterns. To provide quick and intuitive simulations of surface fields, we employ two dimensional Fresnel-Kirchhoff integration, a technique based on freely propagating waves and Huygens' principle. We find generally good agreement between simulations and experiment. Additionally diffracted wave simulations exhibit greater phase accuracy, indicating that these waves are well represented by a two dimensional approximation. The authors gratefully acknowledge funding of this research by the US-DOE Basic Science Office under Contract DE-FG02-10ER46406.

  2. In situ observation of modulated light emission of fiber fuse synchronized with void train over hetero-core splice point.

    Directory of Open Access Journals (Sweden)

    Shin-ichi Todoroki

    Full Text Available BACKGROUND: Fiber fuse is a process of optical fiber destruction under the action of laser radiation, found 20 years ago. Once initiated, opical discharge runs along the fiber core region to the light source and leaves periodic voids whose shape looks like a bullet pointing the direction of laser beam. The relation between damage pattern and propagation mode of optical discharge is still unclear even after the first in situ observation three years ago. METHODOLOGY/PRINCIPAL FINDINGS: Fiber fuse propagation over hetero-core splice point (Corning SMF-28e and HI 1060 was observed in situ. Sequential photographs obtained at intervals of 2.78 micros recorded a periodic emission at the tail of an optical discharge pumped by 1070 nm and 9 W light. The signal stopped when the discharge ran over the splice point. The corresponding damage pattern left in the fiber core region included a segment free of periodicity. CONCLUSIONS: The spatial modulation pattern of the light emission agreed with the void train formed over the hetero-core splice point. Some segments included a bullet-shaped void pointing in the opposite direction to the laser beam propagation although the sequential photographs did not reveal any directional change in the optical discharge propagation.

  3. Impact of environmental colored noise in single-species population dynamics

    Science.gov (United States)

    Spanio, Tommaso; Hidalgo, Jorge; Muñoz, Miguel A.

    2017-10-01

    Variability on external conditions has important consequences for the dynamics and the organization of biological systems. In many cases, the characteristic timescale of environmental changes as well as their correlations play a fundamental role in the way living systems adapt and respond to it. A proper mathematical approach to understand population dynamics, thus, requires approaches more refined than, e.g., simple white-noise approximations. To shed further light onto this problem, in this paper we propose a unifying framework based on different analytical and numerical tools available to deal with "colored" environmental noise. In particular, we employ a "unified colored noise approximation" to map the original problem into an effective one with white noise, and then we apply a standard path integral approach to gain analytical understanding. For the sake of specificity, we present our approach using as a guideline a variation of the contact process—which can also be seen as a birth-death process of the Malthus-Verhulst class—where the propagation or birth rate varies stochastically in time. Our approach allows us to tackle in a systematic manner some of the relevant questions concerning population dynamics under environmental variability, such as determining the stationary population density, establishing the conditions under which a population may become extinct, and estimating extinction times. We focus on the emerging phase diagram and its possible phase transitions, underlying how these are affected by the presence of environmental noise time-correlations.

  4. 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.

  5. Controlling the light propagation in one-dimensional photonic crystal via incoherent pump and interdot tunneling

    Science.gov (United States)

    Abbasabadi, Majid; Sahrai, Mostafa

    2018-01-01

    We investigated the propagation of an electromagnetic pulse through a one-dimensional photonic crystal doped with quantum-dot (QD) molecules in a defect layer. The QD molecules behave as a three-level quantum system and are driven by a coherent probe laser field and an incoherent pump field. No coherent coupling laser fields were introduced, and the coherence was created by the interdot tunnel effect. Further studied was the effect of tunneling and incoherent pumping on the group velocity of the transmitted and reflected probe pulse.

  6. 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.

  7. 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.

  8. 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

  9. Load function modelling for light impact

    International Nuclear Information System (INIS)

    Klingmueller, O.

    1982-01-01

    For Pile Integrity Testing light weight drop hammers are used to induce stress waves. In the computational analysis of one-dimensional wave propagation a load function has to be used. Several mechanical models and corresponding load functions are discussed. It is shown that a bell-shaped function which does not correspond to a mechanical model is in best accordance with test results and does not lead to numerical disturbances in the computational results. (orig.) [de

  10. Broadband angular selectivity of light at the nanoscale: Progress, applications, and outlook

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yichen, E-mail: ycshen@mit.edu; Joannopoulos, John D.; Soljačić, Marin [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hsu, Chia Wei [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Yeng, Yi Xiang [Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2016-03-15

    Humankind has long endeavored to control the propagation direction of light. Since time immemorial, shades, lenses, and mirrors have been used to control the flow of light. In modern society, with the rapid development of nanotechnology, the control of light is moving toward devices at micrometer and even nanometer scales. At such scales, traditional devices based on geometrical optics reach their fundamental diffraction limits and cease to work. Nano-photonics, on the other hand, has attracted wide attention from researchers, especially in the last decade, due to its ability to manipulate light at the nanoscale. This review focuses on the nano-photonics systems that aim to select light based on its propagation direction. In the first half of this review, we survey the literature and the current state of the art focused on enabling optical broadband angular selectivity. The mechanisms we review can be classified into three main categories: (i) microscale geometrical optics, (ii) multilayer birefringent materials, and (iii) Brewster modes in plasmonic systems, photonic crystals, and metamaterials. In the second half, we present two categories of potential applications for broadband angularly selective systems. The first category aims at enhancing the efficiency of solar energy harvesting, through photovoltaic process or solar thermal process. The second category aims at enhancing light extracting efficiency and detection sensitivity. Finally, we discuss the most prominent challenges in broadband angular selectivity and some prospects on how to solve these challenges.

  11. Dissipative light-bullets in the filamentation of femtosecond pulses

    International Nuclear Information System (INIS)

    Porras, M.A.; Gonzalo, I.

    2010-01-01

    Complete text of publication follows. With the growing interest in filamentation in solid and liquid media, the regime of filamentation with anomalous dispersion is receiving more attention. In this work we show that basics aspects of the filament dynamics in this regime can be explained in terms of a novel type of light-bullet, which is not of solitary or of conical types, but a wave-packet that maximizes the energy dissipation into the medium while remaining localized and stationary in propagation. We first show that a nonlinear optical medium at a given carrier wave length at which dispersion is anomalous, supports 'dissipative' light-bullets, i.e., waves localized in space and time and that propagate without change as a result of a balance between nonlinear compression and nonlinear absorption. Among them, the particular dissipative light-bullet with the highest possible dissipation is unique in a given medium, in the sense that all its properties are fixed by the properties of the medium at the carrier wave length. In this light-bullet, self-focusing continuously transports energy towards the pulse center by an amount that just compensates for the nonlinear losses. Figure 1(a) shows the radial profiles of the dissipative light-bullets that maximizes energy dissipation for several orders of multi-photon absorption responsible for the nonlinear losses. We have also found that this dissipative light-bullet tends to be spontaneously formed in the filamentary dynamics in media with anomalous dispersion. Figure 1(b) shows the peak intensity, the total energy and losses of a pulse that undergoes self-focusing and filamentation in an ideal medium with only Kerr nonlinearity and multi-photon absorption. This simple model reproduces the particularly long filament 'segments' and the 'burst' observed in experiments and in more accurate simulations. The peak intensity in the filament is identical to that of the dissipative light-bullet with maximum dissipation, and the

  12. Unirradiated cladding rip-propagation tests

    International Nuclear Information System (INIS)

    Hu, W.L.; Hunter, C.W.

    1981-04-01

    The size of cladding rips which develop when a fuel pin fails can affect the subassembly cooling and determine how rapidly fuel escapes from the pin. The object of the Cladding Rip Propagation Test (CRPT) was to quantify the failure development of cladding so that a more realistic fuel pin failure modeling may be performed. The test results for unirradiated 20% CS 316 stainless steel cladding show significantly different rip propagation behavior at different temperatures. At room temperature, the rip growth is stable as the rip extension increases monotonically with the applied deformation. At 500 0 C, the rip propagation becomes unstable after a short period of stable rip propagation. The rapid propagation rate is approximately 200 m/s, and the critical rip length is 9 mm. At test temperatures above 850 0 C, the cladding exhibits very high failure resistances, and failure occurs by multiple cracking at high cladding deformation. 13 figures

  13. Quantum memory for nonstationary light fields based on controlled reversible inhomogeneous broadening

    International Nuclear Information System (INIS)

    Kraus, B.; Tittel, W.; Gisin, N.; Nilsson, M.; Kroell, S.; Cirac, J. I.

    2006-01-01

    We propose a method for efficient storage and recall of arbitrary nonstationary light fields, such as, for instance, single photon time-bin qubits or intense fields, in optically dense atomic ensembles. Our approach to quantum memory is based on controlled, reversible, inhomogeneous broadening and relies on a hidden time-reversal symmetry of the optical Bloch equations describing the propagation of the light field. We briefly discuss experimental realizations of our proposal

  14. Generalized Fermat's principle and action for light rays in a curved spacetime

    Science.gov (United States)

    Frolov, Valeri P.

    2013-09-01

    We start with formulation of the generalized Fermat’s principle for light propagation in a curved spacetime. We apply Pontryagin’s minimum principle of the optimal control theory and obtain an effective Hamiltonian for null geodesics in a curved spacetime. We explicitly demonstrate that dynamical equations for this Hamiltonian correctly reproduce null geodesic equations. Other forms of the action for light rays in a curved spacetime are also discussed.

  15. Gravitational-recoil effects on fermion propagation in space-time foam

    CERN Document Server

    Ellis, John R.; Nanopoulos, Dimitri V.; Volkov, G.

    2000-01-01

    Motivated by the possible experimental opportunities to test quantum gravity via its effects on high-energy neutrinos propagating through space-time foam, we discuss how to incorporate spin structures in our D-brane description of gravitational recoil effects in vacuo. We also point to an interesting analogous condensed-matter system. We use a suitable supersymmetrization of the Born-Infeld action for excited D-brane gravitational backgrounds to argue that energetic fermions may travel slower than the low-energy velocity of light: pulses of neutrinos at energies approaching 10^{19} eV: these would be observable only if M \\gsim 10^{27} GeV.

  16. Disinfection of Biofilms in Tubes with Ultraviolet Light

    DEFF Research Database (Denmark)

    Bak, Jimmy; Begovic, Tanja

    2009-01-01

    Bacterial biofilms on long-term catheters are a major source of infection. We demonstrate here the potential of UVC light emitting diodes (LED) for disinfection purposes in catheter like tubes contaminated with biofilm. We show that UVC Light propagation is possible through teflon tubes using...... to a flow system and biofilms were produced during a three day period. Tubes in lengths of 10 cm (FEP teflon) were contaminated. Tubes for control and for UVC treatment were contaminated in parallel. The control and UVC treated tubes were both filled with a 20 % NaCl solution during the UVC treatment time...

  17. Green frequency-doubled laser-beam propagation in high-temperature hohlraum plasmas.

    Science.gov (United States)

    Niemann, C; Berger, R L; Divol, L; Froula, D H; Jones, O; Kirkwood, R K; Meezan, N; Moody, J D; Ross, J; Sorce, C; Suter, L J; Glenzer, S H

    2008-02-01

    We demonstrate propagation and small backscatter losses of a frequency-doubled (2omega) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of 2 higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2omega laser-beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggest that good laser coupling into fusion hohlraums using 2omega light is possible.

  18. Managing the environmental impacts of utility lighting retrofits programs

    International Nuclear Information System (INIS)

    Cress, K.

    1993-01-01

    One of the most popular demand-side management (DSM) programs currently being sponsored by electric utilities is the removal of old fluorescent light ballasts and replacing them with more efficient models. This type of program, however, can produce a substantial waste stream of the old ballasts, many of which contain Polychlorinated Biphenyl(s) (PCBs), a regulated hazardous substance. The proper disposal of spent light ballasts should be an integral component of DSM programs. This paper will discuss the experience that New England Electric System (NEES) 1 has had with disposing of spent light ballasts resulting from the implementation of our Small Commercial ampersand Industrial Program (a direct install lighting program which provides for the installation of energy efficient lighting measures which include fluorescent fixtures, ballasts and lamps, specular reflectors, compact fluorescent systems, high intensity discharge fixtures, and occupancy sensors. This innovative program is one of the largest in the country and has achieved over 6,000 installations). In this paper, we will review why PCBs are classified as hazardous substances and what effect State and Federal regulations have on the transportation and disposal of ballasts that contain PCBs. Second, we will explain our ballast disposal process which includes collecting, processing, storing, shipping and ultimate disposal. Third, we will discuss our experiences with two different methods of disposal - incineration and recycling. And last we will report on program results

  19. Study on spectral features of terahertz wave propagating in the air

    Science.gov (United States)

    Kang, Shengwu

    2018-03-01

    Now, Terahertz technology has been widely used in many fields, which is mainly related to imaging detection. While the frequency range of the terahertz-wave is located between microwave and visible light, whether the existing visible light principle is applicable to terahertz-wave should be studied again. Through experiment, we measure the terahertz-wave field amplitude distribution on the receiving plane perpendicular to the direction of propagation in the air and picture out the energy distribution curve; derive an energy decay formula of terahertz wave based on the results; design a terahertz wavelength apparatus using the F-P interferometer theory; test the wavelength between 1 and 3 THz from the SIFIR-50THz laser of American Corehent company; finally analyze the related factors affecting the measurement precision including the beam incident angle, mechanical vibration, temperature fluctuation and the refractive index fluctuation.

  20. Combined effects of blue light and supplemental far-red light and effects of increasing red light with constant far-red light on growth of kidney bean [Phaseolus vulgaris] under mixtures of narrow-band light sources

    International Nuclear Information System (INIS)

    Hanyu, H.; Shoji, K.

    2000-01-01

    Increasing blue light and decreasing R: FR with supplementary far-red light affect morphogenesis, dry matter production and dry matter partitioning to leaves, stems and roots. In this study, the combined effects of the two spectral treatments were examined in kidney bean (Phaseolus vulgaris L.) grown under the mixture of four different narrow-band light sources. In addition, because the leaf and stem growth are accelerated by increasing red light (600-700 nm) in proportion to far-red light (700-800 nm) while keeping R : FR constant, this study was conducted to determine whether red light or far-red light causes the acceleration of growth. Increasing blue light (400-500 nm) and decreasing R : FR only interacted on stem extension. The results illustrated with figures suggest that blue light amplifies or attenuates the acceleration of stem extension caused by decreasing R : FR. On the other hand, increasing red light with constant far-red light had no influence on leaf expansion or stem extension while R : FR increased. Because the acceleration of leaf and stem growth is caused by increasing either far-red light or both red and far-red light in our environmental conditions, the stimulative effects on leaves and stems seem to require increases in far-red light rather than red light

  1. Propagation engineering in radio links design

    CERN Document Server

    Ghasemi, Abdollah; Ghasemi, Farshid

    2013-01-01

    Propagation Engineering in Radio Link Design covers the basic principles of radiowaves propagation in a practical manner.  This fundamental understanding enables the readers to design radio links efficiently. This book elaborates on new achievements as well as recently developed propagation models.  This is in addition to a comprehensive overview of fundamentals of propagation in various scenarios. It examines theoretical calculations, approaches and applied procedures needed for radio links design. The authors study and analysis of the main propagation phenomena and its mechanisms based on the recommendations of International Telecommunications Union, (ITU). The book has been organized in 9 chapters and examines the role of antennas and passive reflectors in radio services, propagation mechanisms related to radar, satellite, short distance, broadcasting and trans-horizon radio links, with two chapters devoted to radio noise and main  parameters of radio link design. The book presents some 278 illustration...

  2. Propagation of crises in the virtual water trade network

    Science.gov (United States)

    Tamea, Stefania; Laio, Francesco; Ridolfi, Luca

    2015-04-01

    The international trade of agricultural goods is associated to the displacement of the water used to produce such goods and embedded in trade as a factor of production. Water virtually exchanged from producing to consuming countries, named virtual water, defines flows across an international network of 'virtual water trade' which enable the assessment of environmental forcings and implications of trade, such as global water savings or country dependencies on foreign water resources. Given the recent expansion of commodity (and virtual water) trade, in both displaced volumes and network structure, concerns have been raised about the exposure to crises of individuals and societies. In fact, if one country had to markedly decrease its export following a socio-economical or environmental crisis, such as a war or a drought, many -if not all- countries would be affected due to a cascade effect within the trade network. The present contribution proposes a mechanistic model describing the propagation of a local crisis into the virtual water trade network, accounting for the network structure and the virtual water balance of all countries. The model, built on data-based assumptions, is tested on the real case study of the Argentinean crisis in 2008-09, when the internal agricultural production (measured as virtual water volume) decreased by 26% and the virtual water export of Argentina dropped accordingly. Crisis propagation and effects on the virtual water trade are correctly captured, showing the way forward to investigations of crises impact and country vulnerability based on the results of the model proposed.

  3. Monte Carlo simulation of light reflection from cosmetic powders on the skin

    Science.gov (United States)

    Okamoto, Takashi; Motoda, Masafumi; Igarashi, Takanori; Nakao, Keisuke

    2011-07-01

    The reflection and scattering properties of light incident on skin covered with powder particles have been investigated. A three-layer skin structure with a spot is modeled, and the propagation of light in the skin and the scattering of light by particles on the skin surface are simulated by means of a Monte Carlo method. Under the condition in which only single scattering of light occurs in the powder layer, the reflection spectra of light from the skin change dramatically with the size of powder particles. The color difference between normal skin and spots is found to diminish more when powder particles smaller than the wavelength of light are used. It is shown that particle polydispersity suppresses substantially the extreme spectral change caused by monodisperse particles with a size comparable to the light wavelength.

  4. Analysis of the Metal Oxide Space Clouds (MOSC) HF Propagation Environment

    Science.gov (United States)

    Jackson-Booth, N.; Selzer, L.

    2015-12-01

    Artificial Ionospheric Modification (AIM) attempts to modify the ionosphere in order to alter the high frequency (HF) propagation environment. It can be achieved through injections of aerosols, chemicals or radio (RF) signals into the ionosphere. The Metal Oxide Space Clouds (MOSC) experiment was undertaken in April/May 2013 to investigate chemical AIM. Two sounding rockets were launched from the Kwajalein Atoll (part of the Marshall Islands) and each released a cloud of vaporized samarium (Sm). The samarium created a localized plasma cloud, with increased electron density, which formed an additional ionospheric layer. The ionospheric effects were measured by a wide range of ground based instrumentation which included a network of high frequency (HF) sounders. Chirp transmissions were made from three atolls and received at five sites within the Marshall Islands. One of the receive sites consisted of an 18 antenna phased array, which was used for direction finding. The ionograms have shown that as well as generating a new layer the clouds created anomalous RF propagation paths, which interact with both the cloud and the F-layer, resulting in 'ghost traces'. To fully understand the propagation environment a 3D numerical ray trace has been undertaken, using a variety of background ionospheric and cloud models, to find the paths through the electron density grid for a given fan of elevation and azimuth firing angles. Synthetic ionograms were then produced using the ratio of ray path length to speed of light as an estimation of the delay between transmission and observation for a given frequency of radio wave. This paper reports on the latest analysis of the MOSC propagation environment, comparing theory with observations, to further understanding of AIM.

  5. Maximizing heavy oil value while minimizing environmental impact with HTL upgrading of heavy to light oil

    Energy Technology Data Exchange (ETDEWEB)

    Koshka, E. [Ivanhoe Energy Inc., Calgary, AB (Canada)

    2009-07-01

    This presentation described Ivanhoe Energy Inc.'s proprietary HTL upgrading technology which was designed to process heavy oil in the field to cost effectively produce an upgraded synthetic oil that meets pipeline requirements. Steam and electricity are generated from the energy produced during the process. HTL improves the economics of heavy oil production by reducing the need for natural gas and diluent, and by capturing most of the heavy to light oil price differential. Integrated HTL heavy oil production also provides many environmental benefits regarding greenhouse gas (GHG) emissions. The HTL upgrading process is ready for full scale application. tabs., figs.

  6. Beyond Snel's law: Refraction of a nano-beam of light

    International Nuclear Information System (INIS)

    Sun Wenbo; Videen, Gorden; Lin Bing; Hu Yongxiang; Fu Qiang

    2011-01-01

    The refraction of a localized narrow beam is significantly different from that of a plane wave. As the beam width decreases to be in the order of the wavelength, the refraction behavior deviates noticeably from Snel's law, and when the width of a light beam is smaller than about one fifth of the wavelength of the incident light, finite-difference time-domain simulations demonstrate that refraction becomes negligible. That is, the narrow light beam retains its propagation direction even after entering another medium at an oblique angle. The result reveals novel features of nano-beams and may have applications in precise biomedical measurement or micro optical device.

  7. The scope for first-order tests of light speed anisotropy

    International Nuclear Information System (INIS)

    Aspden, H.

    1983-01-01

    New optical experiments aimed at testing light speed anisotropy to first-order in v/c are proposed on the basis of an intuitive enquiry into the physical processes by which the vacuum exhibits zero dispersion when regulating the proppagation of light waves. Such experiments can be justified because standing waves are present in experiments of the Michelson-Morley type and these may have a disturbing influence on light propagation speed in the standing-wave region. Though a null result from an initial experiment is reported, the outcome of a second experiment yet to be performed is needed to reach a conclusion from this investigation

  8. Mobile Multi-Gigabit Visible Light Communication System in Realistic Indoor Environment

    OpenAIRE

    Hussein, AT; Elmirghani, JMH

    2015-01-01

    The main challenges facing high data rate visible light communication (VLC) are the low-modulation bandwidth of the current transmitters (i.e., light emitting diodes), the intersymbol interference (ISI) caused by the multipath propagation and cochannel interference (CCI) due to multiple transmitters. In this paper, for the first time, to the best of our knowledge, we propose, design, and evaluate the use of laser diodes (LDs) for communication as well as illumination. In addition, we propose ...

  9. Numerical analysis of light extraction enhancement of GaN-based thin-film flip-chip light-emitting diodes with high-refractive-index buckling nanostructures

    Science.gov (United States)

    Yue, Qing-Yang; Yang, Yang; Cheng, Zhen-Jia; Guo, Cheng-Shan

    2018-06-01

    In this work, the light extraction efficiency enhancement of GaN-based thin-film flip-chip (TFFC) light-emitting diodes (LEDs) with high-refractive-index (TiO2) buckling nanostructures was studied using the three-dimensional finite difference time domain method. Compared with 2-D photonic crystals, the buckling structures have the advantages of a random directionality and a broad distribution in periodicity, which can effectively extract the guided light propagating in all azimuthal directions over a wide spectrum. Numerical studies revealed that the light extraction efficiency of buckling-structured LEDs reaches 1.1 times that of triangular lattice photonic crystals. The effects of the buckling structure feature sizes and the thickness of the N-GaN layer on the light extraction efficiency for TFFC LEDs were also investigated systematically. With optimized structural parameters, a significant light extraction enhancement of about 2.6 times was achieved for TiO2 buckling-structured TFFC LEDs compared with planar LEDs.

  10. Environmental Science Program at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Susan; Shuh, David; Nico, Peter

    2005-06-01

    Synchrotron Radiation (SR)-based techniques have become an essential and fundamental research tool in Molecular Environmental Science (MES) research. MES is an emerging scientific field that has largely evolved from research interactions at the U.S. Department of Energy (U.S. DOE) SR laboratories in response to the pressing need for understanding fundamental molecular-level chemical and biological processes that involve the speciation, properties, and behavior of contaminants, within natural systems. The role of SR-based investigations in MES and their impact on environmental problems of importance to society has been recently documented in Molecular Environmental Science: An Assessment of Research Accomplishment, Available Synchrotron Radiation Facilities, and Needs (EnviroSync, 2003).

  11. Switching waves dynamics in optical bistable cavity-free system at femtosecond laser pulse propagation in semiconductor under light diffraction

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Egorenkov, Vladimir A.; Loginova, Maria M.

    2018-02-01

    We consider a propagation of laser pulse in a semiconductor under the conditions of an occurrence of optical bistability, which appears due to a nonlinear absorption of the semiconductor. As a result, the domains of high concentration of free charged particles (electrons and ionized donors) occur if an intensity of the incident optical pulse is greater than certain intensity. As it is well-known, that an optical beam must undergo a diffraction on (or reflection from) the domains boundaries. Usually, the beam diffraction along a coordinate of the optical pulse propagation does not take into account by using the slowly varying envelope approximation for the laser pulse interaction with optical bistable element. Therefore, a reflection of the beam from the domains with abrupt boundary does not take into account under computer simulation of the laser pulse propagation. However, the optical beams, reflected from nonhomogeneities caused by the domains of high concentration of free-charged particles, can essentially influence on a formation of switching waves in a semiconductor. We illustrate this statement by computer simulation results provided on the base of nonlinear Schrödinger equation and a set of PDEs, which describe an evolution of the semiconductor characteristics (concentrations of free-charged particles and potential of an electric field strength), and taking into account the longitudinal and transverse diffraction effects.

  12. Propagation of waves in a randomly inhomogeneous medium with strongly developed fluctuations. III. Arbitrary power-law noise correlation function

    International Nuclear Information System (INIS)

    Adzhemyan, L.Ts.; Vasil'ev, A.N.; Pis'mak, Yu.M.

    1988-01-01

    The investigation of the infrared behavior of the propagator of a light wave in a randomly inhomogeneous medium with massless Gaussian noise is continued. The infrared representation of the propagator for correlation function D varphi (k)∼k -2 is generalized to the case of an arbitrary power-law noise correlation function is rigorously established in the first two orders of the infrared asymptotic behavior by construction of a suitable R operation. As a consequence, the results are generalized to the case of critical opalescence, when D varphi (k)∼k -2+η , where η ∼ 0.03 is the Fisher index

  13. 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.

  14. Propagation based phase retrieval of simulated intensity measurements using artificial neural networks

    Science.gov (United States)

    Kemp, Z. D. C.

    2018-04-01

    Determining the phase of a wave from intensity measurements has many applications in fields such as electron microscopy, visible light optics, and medical imaging. Propagation based phase retrieval, where the phase is obtained from defocused images, has shown significant promise. There are, however, limitations in the accuracy of the retrieved phase arising from such methods. Sources of error include shot noise, image misalignment, and diffraction artifacts. We explore the use of artificial neural networks (ANNs) to improve the accuracy of propagation based phase retrieval algorithms applied to simulated intensity measurements. We employ a phase retrieval algorithm based on the transport-of-intensity equation to obtain the phase from simulated micrographs of procedurally generated specimens. We then train an ANN with pairs of retrieved and exact phases, and use the trained ANN to process a test set of retrieved phase maps. The total error in the phase is significantly reduced using this method. We also discuss a variety of potential extensions to this work.

  15. 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

  16. Radio wave propagation and parabolic equation modeling

    CERN Document Server

    Apaydin, Gokhan

    2018-01-01

    A thorough understanding of electromagnetic wave propagation is fundamental to the development of sophisticated communication and detection technologies. The powerful numerical methods described in this book represent a major step forward in our ability to accurately model electromagnetic wave propagation in order to establish and maintain reliable communication links, to detect targets in radar systems, and to maintain robust mobile phone and broadcasting networks. The first new book on guided wave propagation modeling and simulation to appear in nearly two decades, Radio Wave Propagation and Parabolic Equation Modeling addresses the fundamentals of electromagnetic wave propagation generally, with a specific focus on radio wave propagation through various media. The authors explore an array of new applications, and detail various v rtual electromagnetic tools for solving several frequent electromagnetic propagation problems. All of the methods described are presented within the context of real-world scenari...

  17. Environmentally assisted cracking in light water reactors - annual report, January-December 2001

    International Nuclear Information System (INIS)

    Chopra, O. K.; Chung, H. M.; Clark, R. W.; Gruber, E. E; Hiller, R. W.; Shack, W. J.; Soppet, W. K.; Strain, R. V.

    2003-01-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from January to December 2001. Topics that have been investigated include (a) environmental effects on fatigue S-N behavior of austenitic stainless steels (SSs), (b) irradiation-assisted stress corrosion cracking (IASCC) of austenitic SSs, and (c) EAC of Alloy 600. The effects of key material and loading variables, such as strain amplitude, strain rate, temperature, dissolved oxygen (DO) level in water, and material heat treatment, on the fatigue lives of wrought and cast austenitic SSs in air and LWR environments have been evaluated. The mechanism of fatigue crack initiation in austenitic SSs in LWR environments has also been examined. The results indicate that the presence of a surface oxide film or difference in the characteristics of the oxide film has no effect on fatigue crack initiation in austenitic SSs in LWR environments. Slow-strain-rate tensile tests and post-test fractographic analyses were conducted on several model SS alloys irradiated to ∼2 x 10 21 n · cm -2 (E > 1 MeV) (∼3 dpa) in He at 289 C in the Halden reactor. The results were used to determine the influence of alloying and impurity elements on the susceptibility of these steels to IASCC. Corrosion fatigue tests were conducted on nonirradiated austenitic SSs in high-purity water at 289 C to establish the test procedure and conditions that will be used for the tests on irradiated materials. A comprehensive irradiation experiment was initiated to obtain many tensile and disk specimens irradiated under simulated pressurized water reactor conditions at ∼325 C to 5, 10, 20, and 40 dpa. Crack growth tests were completed on 30% cold-worked Alloy 600 in high-purity water under various environmental and loading conditions. The results are compared with data obtained earlier on several heats of Alloy 600 tested in high-DO water under several

  18. Cell sorting using efficient light shaping approaches

    DEFF Research Database (Denmark)

    Banas, Andrew; Palima, Darwin; Villangca, Mark Jayson

    2016-01-01

    distributions aimed at the positions of the detected cells. Furthermore, the beam shaping freedom provided by GPC can allow optimizations in the beam’s propagation and its interaction with the catapulted cells. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading...... is gentler, less invasive and more economical compared to conventional FACS systems. As cells are less responsive to plastic or glass beads commonly used in the optical manipulation literature, and since laser safety would be an issue in clinical use, we develop efficient approaches in utilizing lasers...... and light modulation devices. The Generalized Phase Contrast (GPC) method that can be used for efficiently illuminating spatial light modulators or creating well-defined contiguous optical traps is supplemented by diffractive techniques capable of integrating the available light and creating 2D or 3D beam...

  19. The propagator of quantum gravity in minisuperspace

    International Nuclear Information System (INIS)

    Louko, J.

    1985-04-01

    We study the quantum gravitational propagation amplitude between two spacelike three-surfaces in minisuperspaces where the supermomentum constraints are identically satisfied. We derive a well-defined path integral formula for the propagator and show that the propagator is an inverse of the canonical Hamiltonian operator. In an exactly solvable deSitter minisuperspace model the propagator is found to obey semi-classically correct boundary conditions. We discuss the implications for the full theory and suggest an approach to unravelling the physical meaning of the propagator. (orig.)

  20. Neural network construction via back-propagation

    International Nuclear Information System (INIS)

    Burwick, T.T.

    1994-06-01

    A method is presented that combines back-propagation with multi-layer neural network construction. Back-propagation is used not only to adjust the weights but also the signal functions. Going from one network to an equivalent one that has additional linear units, the non-linearity of these units and thus their effective presence is then introduced via back-propagation (weight-splitting). The back-propagated error causes the network to include new units in order to minimize the error function. We also show how this formalism allows to escape local minima

  1. Terrestrial propagation of long electromagnetic waves

    CERN Document Server

    Galejs, Janis; Fock, V A

    2013-01-01

    Terrestrial Propagation of Long Electromagnetic Waves deals with the propagation of long electromagnetic waves confined principally to the shell between the earth and the ionosphere, known as the terrestrial waveguide. The discussion is limited to steady-state solutions in a waveguide that is uniform in the direction of propagation. Wave propagation is characterized almost exclusively by mode theory. The mathematics are developed only for sources at the ground surface or within the waveguide, including artificial sources as well as lightning discharges. This volume is comprised of nine chapte

  2. Light propagation and transmission in hybrid-aligned nematic liquid crystal cells: Geometrical optics calculations

    Science.gov (United States)

    Mendoza, Carlos I.; Reyes, J. Adrian

    2006-08-01

    The authors present a geometrical approach to calculate the transmission of light in a hybrid-aligned nematic cell under the influence of an applied electric field. Using the framework of geometrical optics they present results for the ray tracing as well as the transmission of light as a function of the applied low frequency voltage. Dispersion effects are included through a wavelength dependent dielectric function. Their results for the transmittance as a function of the applied voltage show oscillations that are in good qualitative agreement with previously obtained experimental measurements.

  3. Propagation of SLF/ELF electromagnetic waves

    CERN Document Server

    Pan, Weiyan

    2014-01-01

    This book deals with the SLF/ELF wave propagation, an important branch of electromagnetic theory. The SLF/ELF wave propagation theory is well applied in earthquake electromagnetic radiation, submarine communication, thunderstorm detection, and geophysical prospecting and diagnostics. The propagation of SLF/ELF electromagnetic waves is introduced in various media like the earth-ionospheric waveguide, ionospheric plasma, sea water, earth, and the boundary between two different media or the stratified media. Applications in the earthquake electromagnetic radiation and the submarine communications are also addressed. This book is intended for scientists and engineers in the fields of radio propagation and EM theory and applications. Prof. Pan is a professor at China Research Institute of Radiowave Propagation in Qingdao (China). Dr. Li is a professor at Zhejiang University in Hangzhou (China).

  4. Directionality and Orientation Effects on the Resistance to Propagating Shear Failure

    Science.gov (United States)

    Leis, B. N.; Barbaro, F. J.; Gray, J. M.

    Hydrocarbon pipelines transporting compressible products like methane or high-vapor-pressure (HVP) liquids under supercritical conditions can be susceptible to long-propagating failures. As the unplanned release of such hydrocarbons can lead to significant pollution and/or the horrific potential of explosion and/or a very large fire, design criteria to preclude such failures were essential to environmental and public safety. Thus, technology was developed to establish the minimum arrest requirements to avoid such failures shortly after this design concern was evident. Soon after this technology emerged in the early 1970sit became evident that its predictions were increasinglynon-conservative as the toughness of line-pipe steel increased. A second potentially critical factor for what was a one-dimensional technology was that changes in steel processing led to directional dependence in both the flow and fracture properties. While recognized, this dependence was tacitly ignored in quantifying arrest, as were early observations that indicated propagating shear failure was controlled by plastic collapse rather than by fracture processes.

  5. Environmentally assisted cracking in light water reactors annual report January - December 2005.

    Energy Technology Data Exchange (ETDEWEB)

    Alexandreanu, B.; Chen, Y.; Chopra, O. K.; Chung, H. M.; Gruber, E. E.; Shack, W. J.; Soppet, W. K.

    2007-08-31

    This report summarizes work performed from January to December 2005 by Argonne National Laboratory on fatigue and environmentally assisted cracking in light water reactors (LWRs). Existing statistical models for estimating the fatigue life of carbon and low-alloy steels and austenitic stainless steels (SSs) as a function of material, loading, and environmental conditions were updated. Also, the ASME Code fatigue adjustment factors of 2 on stress and 20 on life were critically reviewed to assess the possible conservatism in the current choice of the margins. An approach, based on an environmental fatigue correction factor, for incorporating the effects of LWR environments into ASME Section III fatigue evaluations is discussed. The susceptibility of austenitic stainless steels and their welds to irradiation-assisted stress corrosion cracking (IASCC) is being evaluated as a function of the fluence level, water chemistry, material chemistry, and fabrication history. For this task, crack growth rate (CGR) tests and slow strain rate tensile (SSRT) tests are being conducted on various austenitic SSs irradiated in the Halden boiling water reactor. The SSRT tests are currently focused on investigating the effects of the grain boundary engineering process on the IASCC of the austenitic SSs. The CGR tests were conducted on Type 316 SSs irradiated to 0.45-3.0 dpa, and on sensitized Type 304 SS and SS weld heat-affected-zone material irradiated to 2.16 dpa. The CGR tests on materials irradiated to 2.16 dpa were followed by a fracture toughness test in a water environment. The effects of material composition, irradiation, and water chemistry on growth rates are discussed. The susceptibility of austenitic SS core internals to IASCC and void swelling is also being evaluated for pressurized water reactors. Both SSRT tests and microstructural examinations are being conducted on specimens irradiated in the BOR-60 reactor in Russia to doses up to 20 dpa. Crack growth rate data

  6. Propagation and spatiotemporal coupling characteristics of ultra-short Gaussian vortex pulse

    Science.gov (United States)

    Nie, Jianye; Liu, Guodong; Zhang, Rongzhu

    2018-05-01

    Based on Collins diffraction integral formula, the propagation equation of ultra-short Gaussian vortex pulse beam has been derived. Using the equation, the intensity distribution variations of vortex pulse in the propagation process are calculated. Specially, the spatiotemporal coupling characteristics of ultra-short vortex beams are discussed in detail. The results show that some key parameters, such as transverse distance, transmission distance, pulse width and topological charge number will influence the spatiotemporal coupling characteristics significantly. With the increasing of transverse distance, the waveforms of the pulses distort obviously. And when transmission distance is far than 50 mm, the distribution curve of transverse intensity gradually changes into a Gaussian type. In addition, initial pulse width will affect the distribution of light field, however, when initial pulse width is larger than 3 fs, the spatiotemporal coupling effect will be insignificant. Topological charge number does not affect the time delay characteristics, since with the increasing of topological charge number, the waveform of the pulse distorts gradually but the time delay does not occur.

  7. Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

    International Nuclear Information System (INIS)

    Mario Agio

    2002-01-01

    This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser

  8. Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Agio, Mario [Iowa State Univ., Ames, IA (United States)

    2002-12-31

    This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser.

  9. Influence of excitation light rejection on forward model mismatch in optical tomography

    International Nuclear Information System (INIS)

    Hwang, K; Pan, T; Joshi, A; Rasmussen, J C; Bangerth, W; Sevick-Muraca, E M

    2006-01-01

    Fluorescence enhanced tomography for molecular imaging requires low background for detection and accurate image reconstruction. In this contribution, we show that excitation light leakage is responsible for elevated background and can be minimized with the use of gradient index (GRIN) lenses when using fibre optics to collect propagated fluorescence light from tissue or other biological media. We show that the model mismatch between frequency-domain photon migration (FDPM) measurements and the diffusion approximation prediction is decreased when GRIN lenses are placed prior to the interference filters to provide efficient excitation light rejection. Furthermore, model mismatch is correlated to the degree of excitation light leakage. This work demonstrates the importance of proper light filtering when designing fluorescence optical imaging and tomography

  10. Proceedings of the Twenty-First NASA Propagation Experiments Meeting (NAPEX XXI) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

    Science.gov (United States)

    Golshan, Nasser (Editor)

    1997-01-01

    The NASA Propagation Experimenters (NAPEX) meeting is convened each year to discuss studies supported by the NASA Propagation Program. Representatives from the satellite communications industry, academia and government who have an interest in space-ground radio wave propagation are invited to NAPEX meetings for discussions and exchange of information. The reports delivered at this meeting by program managers and investigators present recent activities and future plans. This forum provides an opportunity for peer discussion of work in progress, timely dissemination of propagation results, and close interaction with the satellite communications industry. NAPEX XXI took place in El Segundo, California on June 11-12, 1997 and consisted of three sessions. Session 1, entitled "ACTS Propagation Study Results & Outcome " covered the results of 20 station-years of Ka-band radio-wave propagation experiments. Session 11, 'Ka-band Propagation Studies and Models,' provided the latest developments in modeling, and analysis of experimental results about radio wave propagation phenomena for design of Ka-band satellite communications systems. Session 111, 'Propagation Research Topics,' covered a diverse range of propagation topics of interest to the space community, including overviews of handbooks and databases on radio wave propagation. The ACTS Propagation Studies miniworkshop was held on June 13, 1997 and consisted of a technical session in the morning and a plenary session in the afternoon. The morning session covered updates on the status of the ACTS Project & Propagation Program, engineering support for ACTS Propagation Terminals, and the Data Center. The plenary session made specific recommendations for the future direction of the program.

  11. Asymbiotic in vitro seed propagation of Dendrobium.

    Science.gov (United States)

    Teixeira da Silva, Jaime A; Tsavkelova, Elena A; Ng, Tzi Bun; Parthibhan, S; Dobránszki, Judit; Cardoso, Jean Carlos; Rao, M V; Zeng, Songjun

    2015-10-01

    The ability to germinate orchids from seeds in vitro presents a useful and viable method for the propagation of valuable germplasm, maintaining the genetic heterogeneity inherent in seeds. Given the ornamental and medicinal importance of many species within the genus Dendrobium, this review explores in vitro techniques for their asymbiotic seed germination. The influence of abiotic factors (such as temperature and light), methods of sterilization, composition of basal media, and supplementation with organic additives and plant growth regulators are discussed in context to achieve successful seed germination, protocorm formation, and further seedling growth and development. This review provides both a basis for the selection of optimal conditions, and a platform for the discovery of better ones, that would allow the development of new protocols and the exploration of new hypotheses for germination and conservation of Dendrobium seeds and seedlings.

  12. Statistics of light deflection in a random two-phase medium

    International Nuclear Information System (INIS)

    Sviridov, A P

    2007-01-01

    The statistics of the angles of light deflection during its propagation in a random two-phase medium with randomly oriented phase interfaces is considered within the framework of geometrical optics. The probabilities of finding a randomly walking photon in different phases of the inhomogeneous medium are calculated. Analytic expressions are obtained for the scattering phase function and the scattering phase matrix which relates the Stokes vector of the incident light beam with the Stokes vectors of deflected beams. (special issue devoted to multiple radiation scattering in random media)

  13. Self-action of Bessel wave packets in a system of coupled light guides and formation of light bullets

    Energy Technology Data Exchange (ETDEWEB)

    Balakin, A. A., E-mail: balakin.alexey@yandex.ru; Mironov, V. A.; Skobelev, S. A., E-mail: sk.sa1981@gmail.com [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2017-01-15

    The self-action of two-dimensional and three-dimensional Bessel wave packets in a system of coupled light guides is considered using the discrete nonlinear Schrödinger equation. The features of the self-action of such wave fields are related to their initial strong spatial inhomogeneity. The numerical simulation shows that for the field amplitude exceeding a critical value, the development of an instability typical of a medium with the cubic nonlinearity is observed. Various regimes are studied: the self-channeling of a wave beam in one light guide at powers not strongly exceeding a critical value, the formation of the “kaleidoscopic” picture of a wave packet during the propagation of higher-power radiation along a stratified medium, the formation of light bullets during competition between self-focusing and modulation instabilities in the case of three-dimensional wave packets, etc. In the problem of laser pulse shortening, the situation is considered when the wave-field stratification in the transverse direction dominates. This process is accompanied by the self-compression of laser pulses in well enough separated light guides. The efficiency of conversion of the initial Bessel field distribution to two flying parallel light bullets is about 50%.

  14. 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.

  15. 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

  16. 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

  17. Higher-order amplitude squeezing of photons propagating through a semiconductor

    International Nuclear Information System (INIS)

    Nguyen Ba An.

    1996-12-01

    Photon amplitude K th power squeezing is studied when the coherent photon propagates through a semiconductor containing the exciton. If the exciton is prepared initially in a coherent state, the photon may become amplitude K th power squeezed. It is shown that, in the short-time limit, the photon squeezing in the P direction does not appear at all while that in the X direction is possible for all the amplitude power K. In the latter case, the amount of squeezing is larger for higher power K. Dependences on all the system parameters as well as on the output light detection moment are investigated in detail. (author). 14 refs, 8 figs

  18. On the cosmological propagation of high energy particles in magnetic fields

    International Nuclear Information System (INIS)

    Alves Batista, Rafael

    2015-04-01

    intergalactic magnetic fields on the propagation of UHECRs was analyzed. It is shown that magnetic fields are crucial for the propagation of cosmic rays, and the lack of knowledge about their properties can spoil the possibilities of identifying individual sources of UHECRs. The prospects for UHECR astronomy are discussed in light of these results. The second part of this work concerns the propagation of VHEGRs in the universe. Gamma rays interact with pervasive photon fields creating electron-positron pairs which scatter background photons, in a process known as electromagnetic cascade. The electron-positron pairs can provide valuable information about the intervening magnetic fields, including the possibility of constraining the strength of these fields. A new Monte Carlo code for propagating VHEGRs in the universe was developed, based on the code structure of CRPropa. This code was applied to the study of pair halos from blazars under the assumption of different magnetic field configurations. The results suggest that the observation of pair halos can provide important clues on the strength of intergalactic magnetic fields, as well as the maximal energy attainable by VHEGR sources.

  19. Controlling the emission and propagation of light with nano-plasmonic metamaterials and metasurfaces

    Science.gov (United States)

    Ni, Xingjie

    Metamaterials---artificially structured materials with engineered electromagnetic properties---have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities. Metasurfaces are subwavelength thin metamaterial layers to introduce unusual properties do not exist in nature. They can play a fundamental role in generating synthetic scattering diagrams of macroscopic objects. Optical metamaterials and metasurfaces have enabled unprecedented flexibility in manipulating light waves and producing new functionalities. We have studied various topics in this field, from designs to potential applications. We experimentally demonstrated the world's first optical metasurface which is capable of precisely manipulating light in arbitrary ways over a broad range of near-infrared light, which could make possible of many optical innovations such as more powerful microscopes, telecommunications and computers. We proposed the first hyperbolic metasurface, which consist of a highly anisotropic material layer and an isotropic material layer can support Dyakonov surface waves that have hyperbolic dispersion. This type of metasurfaces support a broadband singularity in the photonic density of states, which opens up another possibility to engineer the spontaneous emission efficiency. We also developed a set of parallel simulation tools which can handle a variety of problems in nanophotonics and plasmonics. Especially, we established an on-line research environment for the research community with six tools, which deliver a cloud computing service with no demand for either any powerful computational hardware or any additional software installations and cover a range of tasks including the design and simulation of complex transformation optics devices and optical metamaterials.

  20. 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.

  1. The light wave flow effect in a plane-parallel layer with a quasi-zero refractive index under the action of bounded light beams

    International Nuclear Information System (INIS)

    Gadomsky, O. N.; Shchukarev, I. A.

    2016-01-01

    It is shown that external optical radiation in the 450–1200 nm range can be efficiently transformed under the action of bounded light beams to a surface wave that propagates along the external and internal boundaries of a plane-parallel layer with a quasi-zero refractive index. Reflection regimes with complex and real angles of refraction in the layer are considered. The layer with a quasi-zero refractive index in this boundary problem is located on a highly reflective metal substrate; it is shown that the uniform low reflection of light is achieved in the wavelength range under study.

  2. Characteristics of shock propagation in high-strength cement mortar

    Science.gov (United States)

    Wang, Zhanjiang; Li, Xiaolan; Zhang, Ruoqi

    2001-06-01

    Planar impact experiments have been performed on high-strength cement mortar to determine characteristics of shock propagation.The experiments were conducted on a light-gas gun,and permanent-magnet particle velocity gages were used to obtain the sand of 0.5 3.5mm size.A bulk density of 2.31g/cm^3,and a compressive and tensile strength of 82MPa and 7.8MPa,respectively,were determined.Three kinds of experimental techniques were used,including the reverse ballistic configuration.These techniques effectively averaged the measured dynamic compression state over a sensibly large volume of the test sample.The impact velocities were controlled over a range of approximately 80m/s to 0.83km/s.Hugoniot equation of state data were obtained for the material over a pressure range of approximately 0.2 2.0GPa,and its nonlinear constitutive relation were analyzed.The experiment results show that,in higher pressure range provided in the experiment,the shock wave in the material splits into two components of an elastic and a plastic,with the Hugoniot elastic limit 0.4 0.5GPa and the precursor velocity about 4.7km/s,and the material presents a very strong nonlinear dynamic response,and its shock amplitude will greatly decrease in propagation.

  3. Sustainable LED Fluorescent Light Replacement Technology

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2011-09-30

    Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life: Environmental Impact Review – Designs are comparable

  4. Propagating separable equalities in an MDD store

    DEFF Research Database (Denmark)

    Hadzic, Tarik; Hooker, John N.; Tiedemann, Peter

    2008-01-01

    We present a propagator that achieves MDD consistency for a separable equality over an MDD (multivalued decision diagram) store in pseudo-polynomial time. We integrate the propagator into a constraint solver based on an MDD store introduced in [1]. Our experiments show that the new propagator pro...... provides substantial computational advantage over propagation of two inequality constraints, and that the advantage increases when the maximum width of the MDD store increases....

  5. Injection and waveguiding properties in SU8 nanotubes for sub-wavelength regime propagation and nanophotonics integration

    Science.gov (United States)

    Bigeon, John; Huby, Nolwenn; Duvail, Jean-Luc; Bêche, Bruno

    2014-04-01

    We report photonic concepts related to injection and sub-wavelength propagation in nanotubes, an unusual but promising geometry for highly integrated photonic devices. Theoretical simulation by the finite domain time-dependent (FDTD) method was first used to determine the features of the direct light injection and sub-wavelength propagation regime within nanotubes. Then, the injection into nanotubes of SU8, a photoresist used for integrated photonics, was successfully achieved by using polymer microlensed fibers with a sub-micronic radius of curvature, as theoretically expected from FDTD simulations. The propagation losses in a single SU8 nanotube were determined by using a comprehensive set-up and a protocol for optical characterization. The attenuation coefficient has been evaluated at 1.25 dB mm-1 by a cut-back method transposed to such nanostructures. The mechanisms responsible for losses in nanotubes were identified with FDTD theoretical support. Both injection and cut-back methods developed here are compatible with any sub-micronic structures. This work on SU8 nanotubes suggests broader perspectives for future nanophotonics.

  6. Handbook of advanced lighting technology

    CERN Document Server

    Sun, Ching-Cherng; Zissis, Georges; Ma, Ruiqing

    2017-01-01

    The Handbook of Advanced Lighting Technology is a major reference work on the subject of light source science and technology, with particular focus on solid-state light sources – LEDs and OLEDs – and the development of 'smart' or 'intelligent' lighting systems; and the integration of advanced light sources, sensors, and adaptive control architectures to provide tailored illumination which is 'fit to purpose.' The concept of smart lighting goes hand-in-hand with the development of solid-state light sources, which offer levels of control not previously available with conventional lighting systems. This has impact not only at the scale of the individual user, but also at an environmental and wider economic level. These advances have enabled and motivated significant research activity on the human factors of lighting, particularly related to the impact of lighting on healthcare and education, and the Handbook provides detailed reviews of work in these areas. The potential applications for smart lighting span ...

  7. Reliable LED Lighting Technologies: Key Factors and Procurement Guidance

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Lynn; Arquit Niederberger, Anne

    2015-10-08

    Abstract— Lighting systems have the ability to transform the economic and educational infrastructure of disadvantaged communities, and eradicating “light poverty” has become one of the primary goals of the International Year of Light 2015. Solid-state lighting (SSL) technology, based on light-emitting diode (LED) light sources, has emerged as the next generation of lighting technology, with a current global market penetration of roughly 5%. This paper will report on recent research on understanding SSL lighting system reliability (failure modes, environmental stressors, electrical power quality); discuss the implications of SSL technology reliability for providing lighting services; and suggest practical approaches to ensure SSL reliability to benefit humanity. Among the key findings from this work is that LED sources can be extremely reliable, withstanding a broad range of environmental stresses without failure. Nonetheless, SSL lighting systems can have a negative impact on electrical power reliability, as well as on the affordability of lighting services, without attention to the quality of the accompanying power infrastructure. It is therefore critical to ensure that the performance of the power supply electronics used in lighting systems is matched to the quality of the power source, when evaluating energy efficient lighting choices.

  8. Propagating the missing bacteriophages: a large bacteriophage in a new class

    Directory of Open Access Journals (Sweden)

    Hardies Stephen C

    2007-02-01

    Full Text Available Abstract The number of successful propagations/isolations of soil-borne bacteriophages is small in comparison to the number of bacteriophages observed by microscopy (great plaque count anomaly. As one resolution of the great plaque count anomaly, we use propagation in ultra-dilute agarose gels to isolate a Bacillus thuringiensis bacteriophage with a large head (95 nm in diameter, tail (486 × 26 nm, corkscrew-like tail fibers (187 × 10 nm and genome (221 Kb that cannot be detected by the usual procedures of microbiology. This new bacteriophage, called 0305φ8-36 (first number is month/year of isolation; remaining two numbers identify the host and bacteriophage, has a high dependence of plaque size on the concentration of a supporting agarose gel. Bacteriophage 0305φ8-36 does not propagate in the traditional gels used for bacteriophage plaque formation and also does not produce visible lysis of liquid cultures. Bacteriophage 0305φ8-36 aggregates and, during de novo isolation from the environment, is likely to be invisible to procedures of physical detection that use either filtration or centrifugal pelleting to remove bacteria. Bacteriophage 0305φ8-36 is in a new genomic class, based on genes for both structural components and DNA packaging ATPase. Thus, knowledge of environmental virus diversity is expanded with prospect of greater future expansion.

  9. 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

  10. Statistical Physics and Light-Front Quantization

    Energy Technology Data Exchange (ETDEWEB)

    Raufeisen, J

    2004-08-12

    Light-front quantization has important advantages for describing relativistic statistical systems, particularly systems for which boost invariance is essential, such as the fireball created in a heavy ion collisions. In this paper the authors develop light-front field theory at finite temperature and density with special attention to quantum chromodynamics. They construct the most general form of the statistical operator allowed by the Poincare algebra and show that there are no zero-mode related problems when describing phase transitions. They then demonstrate a direct connection between densities in light-front thermal field theory and the parton distributions measured in hard scattering experiments. The approach thus generalizes the concept of a parton distribution to finite temperature. In light-front quantization, the gauge-invariant Green's functions of a quark in a medium can be defined in terms of just 2-component spinors and have a much simpler spinor structure than the equal-time fermion propagator. From the Green's function, the authors introduce the new concept of a light-front density matrix, whose matrix elements are related to forward and to off-diagonal parton distributions. Furthermore, they explain how thermodynamic quantities can be calculated in discretized light-cone quantization, which is applicable at high chemical potential and is not plagued by the fermion-doubling problems.

  11. Fatigue Crack Propagation Behavior of RC Beams Strengthened with CFRP under High Temperature and High Humidity Environment

    Directory of Open Access Journals (Sweden)

    Dongyang Li

    2017-01-01

    Full Text Available Numerical and experimental methods were applied to investigate fatigue crack propagation behavior of reinforced concrete (RC beams strengthened with a new type carbon fiber reinforced polymer (CFRP named as carbon fiber laminate (CFL subjected to hot-wet environment. J-integral of a central crack in the strengthened beam under three-point bending load was calculated by ABAQUS. In finite element model, simulation of CFL-concrete interface was based on the bilinear cohesive zone model under hot-wet environment and indoor atmosphere. And, then, fatigue crack propagation tests were carried out under high temperature and high humidity (50°C, 95% R · H environment pretreatment and indoor atmosphere (23°C, 78% R · H to obtain a-N curves and crack propagation rate, da/dN, of the strengthened beams. Paris-Erdogan formula was developed based on the numerical analysis and environmental fatigue tests.

  12. Biogeography of photosynthetic light-harvesting genes in marine phytoplankton.

    Directory of Open Access Journals (Sweden)

    Thomas S Bibby

    Full Text Available BACKGROUND: Photosynthetic light-harvesting proteins are the mechanism by which energy enters the marine ecosystem. The dominant prokaryotic photoautotrophs are the cyanobacterial genera Prochlorococcus and Synechococcus that are defined by two distinct light-harvesting systems, chlorophyll-bound protein complexes or phycobilin-bound protein complexes, respectively. Here, we use the Global Ocean Sampling (GOS Project as a unique and powerful tool to analyze the environmental diversity of photosynthetic light-harvesting genes in relation to available metadata including geographical location and physical and chemical environmental parameters. METHODS: All light-harvesting gene fragments and their metadata were obtained from the GOS database, aligned using ClustalX and classified phylogenetically. Each sequence has a name indicative of its geographic location; subsequent biogeographical analysis was performed by correlating light-harvesting gene budgets for each GOS station with surface chlorophyll concentration. CONCLUSION/SIGNIFICANCE: Using the GOS data, we have mapped the biogeography of light-harvesting genes in marine cyanobacteria on ocean-basin scales and show that an environmental gradient exists in which chlorophyll concentration is correlated to diversity of light-harvesting systems. Three functionally distinct types of light-harvesting genes are defined: (1 the phycobilisome (PBS genes of Synechococcus; (2 the pcb genes of Prochlorococcus; and (3 the iron-stress-induced (isiA genes present in some marine Synechococcus. At low chlorophyll concentrations, where nutrients are limited, the Pcb-type light-harvesting system shows greater genetic diversity; whereas at high chlorophyll concentrations, where nutrients are abundant, the PBS-type light-harvesting system shows higher genetic diversity. We interpret this as an environmental selection of specific photosynthetic strategy. Importantly, the unique light-harvesting system isiA is found

  13. Fatigue crack layer propagation in silicon-iron

    Science.gov (United States)

    Birol, Y.; Welsch, G.; Chudnovsky, A.

    1986-01-01

    Fatigue crack propagation in metal is almost always accompanied by plastic deformation unless conditions strongly favor brittle fracture. The analysis of the plastic zone is crucial to the understanding of crack propagation behavior as it governs the crack growth kinetics. This research was undertaken to study the fatigue crack propagation in a silicon iron alloy. Kinetic and plasticity aspects of fatigue crack propagation in the alloy were obtained, including the characterization of damage evolution.

  14. Propagation Properties of Airy Beam through Periodic Slab System with Negative Index Materials

    Directory of Open Access Journals (Sweden)

    Long Jin

    2018-01-01

    Full Text Available Based on light transfer matrix and electric field vector equation, the evolution of Airy beam propagating in periodic slab system with three negative index materials (NIMs and its transmission mechanism are investigated. The intensity profiles on emergent surface of periodic slab system and side view of Airy beam propagating in each right handed material (RHM and double negative material (DNM unit including lossless and losses DNMs are discussed. It is revealed that the self-recovery Airy beam can be achieved in long distance by using lossless periodic slab system as long as the negative refractive index nl=-nr and each unit length L=Z. As to losses slab system contained DNMs, the smaller the collision frequencies are, the better the Airy beam quality is formed. It is expected that the proposed manner of beam transmission and corresponding conclusions can be useful for extension applications of optical control, especially for optical communication and optical encryption technique.

  15. 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

  16. Final generic environmental statement on the use of recycle plutonium in mixed oxide fuel in light water cooled reactors. Volume 3

    International Nuclear Information System (INIS)

    1976-08-01

    An assessment is presented of the health, safety and environmental effects of the entire light water reactor fuel cycle, considering the comparative effects of three major alternatives: no recycle, recycle of uranium only, and recycle of both uranium and plutonium. The assessment covers the period from 1975 through the year 2000 and includes the cumulative effects for the entire period as well as projections for specific years. Topics discussed include: the light water reactor with plutonium recycle; mixed oxide fuel fabrication; reprocessing plant operations; supporting uranium fuel cycle; transportation of radioactive materials; radioactive waste management; storage of plutonium; radiological health assessment; extended spent fuel storage; and blending of plutonium and uranium at reprocessing plants

  17. Slow light enhanced optical nonlinearity in a silicon photonic crystal coupled-resonator optical waveguide.

    Science.gov (United States)

    Matsuda, Nobuyuki; Kato, Takumi; Harada, Ken-Ichi; Takesue, Hiroki; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya

    2011-10-10

    We demonstrate highly enhanced optical nonlinearity in a coupled-resonator optical waveguide (CROW) in a four-wave mixing experiment. Using a CROW consisting of 200 coupled resonators based on width-modulated photonic crystal nanocavities in a line defect, we obtained an effective nonlinear constant exceeding 10,000 /W/m, thanks to slow light propagation combined with a strong spatial confinement of light achieved by the wavelength-sized cavities.

  18. Projecting light beams with 3D waveguide arrays

    Science.gov (United States)

    Crespi, Andrea; Bragheri, Francesca

    2017-01-01

    Free-space light beams with complex intensity patterns, or non-trivial phase structure, are demanded in diverse fields, ranging from classical and quantum optical communications, to manipulation and imaging of microparticles and cells. Static or dynamic spatial light modulators, acting on the phase or intensity of an incoming light wave, are the conventional choices to produce beams with such non-trivial characteristics. However, interfacing these devices with optical fibers or integrated optical circuits often requires difficult alignment or cumbersome optical setups. Here we explore theoretically and with numerical simulations the potentialities of directly using the output of engineered three-dimensional waveguide arrays, illuminated with linearly polarized light, to project light beams with peculiar structures. We investigate through a collection of illustrative configurations the far field distribution, showing the possibility to achieve orbital angular momentum, or to produce elaborate intensity or phase patterns with several singularity points. We also simulate the propagation of the projected beam, showing the possibility to concentrate light. We note that these devices should be at reach of current technology, thus perspectives are open for the generation of complex free-space optical beams from integrated waveguide circuits.

  19. Analysis of light propagation in quasiregular and hybrid Rudin-Shapiro one-dimensional photonic crystals with superconducting layers

    Science.gov (United States)

    Gómez-Urrea, H. A.; Escorcia-García, J.; Duque, C. A.; Mora-Ramos, M. E.

    2017-11-01

    The transmittance spectrum of a one-dimensional hybrid photonic crystal built from the suitable arrangement of periodic and quasiregular Rudin-Shapiro heterolayers that include superconducting slabs is investigated. The four-layer Rudin-Shapiro structure is designed with three lossless dielectric layers and a low-temperature superconductor one. The dielectric function of the superconducting layer is modeled by the two-fluid Gorter-Casimir theory, and the transmittance is calculated with the use of the transfer matrix method. The obtained results reveal the presence of a cut-off frequency fc - a forbidden frequency band for propagation - that can be manipulated by changing the width of the superconducting layer, the temperature and the order of the Rudin-Shapiro sequence. In addition, the spatial distribution of the electric field amplitude for the propagating TM modes is also discussed. It is found that the maximum of localized electric field relative intensity - which reaches a value of several tens - corresponds to the frequency values above to the cut-off frequency, at which, the effective dielectric function of the hybrid unit cell becomes zero. The proposed structure could be another possible system for optical device design for temperature-dependent optical devices such as stop-band filters, or as bolometers.

  20. Stopping light in its tracks

    Science.gov (United States)

    Eggleton, B. J.; Martijn de Sterke, C.; Slusher, R. E.; Krug, Peter A.; Sipe, J. E.

    1996-12-01

    To control the speed of a light pulse without absorbing its photons, or distorting its shape, is a challenging problem. However, this has been accomplished using fiber gratings, as part of a joint research program of the University of Sydney, the Australian Photonics Research Centre, Lucent Technologies, and the University of Toronto. The gratings are written in the optical fiber's core by directing a UV beam onto it via a periodic phase mask. Through a photochemical process still not well-understood, the periodic intensity pattern burns a permanent index of refraction change in the core.1-2 In our experiments, we use gratings with a period of about 350 nm chosen to reflect light at 1.05 u m and a length of 5.5 cm.3 Because the grating has over 150,000 periods, an index change of only 0.0003 is sufficient to limit the transmission to less than 30 dB on resonance. Essentially no light is transmitted by such a grating at the Bragg resonance; yet a nanometer away, light propagates through as if the grating were absent. As we tune away from resonance, the light's group velocity increases from zero to c/n (where c is the speed of light in a vacuum and n=1.46 is the refractive index of the core of the fiber), leading to a dispersion about 100,000 times larger than that of bare fiber. Gratings can thus slow down a pulse of light, but at the price of tearing it apart.4 At high light intensities a nonlinearly, with the index of refraction increasing with intensity.5 In the center of the pulse, where the intensity is the highest, the index is thus raised the most. Since regions of high index attract light, the nonlinearity acts as a "glue," counteracting the strong dispersive effects of the grating.

  1. Performance of new generation pole light

    International Nuclear Information System (INIS)

    Foo, K C; Karunanithi, S; Thio, G

    2013-01-01

    This paper describes the design and implementation of a standalone photovoltaic power supply which caters for garden lighting scheme. New Generation Pole Light (NGPL) consists of three parts which are light dependent resistor (LDR) and pyroelectric infrared (PIR) sensors, microcontroller and light emitting diode (LED) and finally, solar charging system. During the night, LED is switched on with two operating modes which are ultra-bright lighting for a predetermine period (when human presence is detected) and dim lighting. Meanwhile, LED is switched off at day time and solar charging system will recover the capacity of discharged battery. NGPL provides portable, sustainable, environmental friendly and requires minimal maintenance for outdoor lighting scheme for both urban and rural areas.

  2. HPLC-DAD-ESI/MS identification of light harvesting and light screening pigments in the lake sediments at Edmonson Point.

    Science.gov (United States)

    Giovannetti, Rita; Alibabaei, Leila; Zannotti, Marco; Ferraro, Stefano; Petetta, Laura

    2013-01-01

    The composition of sedimentary pigments in the Antarctic lake at Edmonson Point has been investigated and compared with the aim to provide a useful analytical method for pigments separation and identification, providing reference data for future assessment of possible changes in environmental conditions. Reversed phase high performance liquid chromatography (HPLC) with electrospray-mass spectrometry (ESI-MS) detection and diode array detection (DAD) has been used to identify light screening and light harvesting pigments. The results are discussed in terms of local environmental conditions.

  3. Omnidirectional narrow optical filters for circularly polarized light in a nanocomposite structurally chiral medium.

    Science.gov (United States)

    Avendaño, Carlos G; Palomares, Laura O

    2018-04-20

    We consider the propagation of electromagnetic waves throughout a nanocomposite structurally chiral medium consisting of metallic nanoballs randomly dispersed in a structurally chiral material whose dielectric properties can be represented by a resonant effective uniaxial tensor. It is found that an omnidirectional narrow pass band and two omnidirectional narrow band gaps are created in the blue optical spectrum for right and left circularly polarized light, as well as narrow reflection bands for right circularly polarized light that can be controlled by varying the light incidence angle and the filling fraction of metallic inclusions.

  4. Photon and energy propagation in Cd Se quantum dot systems

    International Nuclear Information System (INIS)

    Alves, Guilherme A.; Santos, Erasto J.; Monte, Adamo F.G.

    2011-01-01

    Full text. Photon propagation is a crucial process in a wide type of optical materials being responsible for the dynamics and excitation spreading. The addition of Cd Se quantum dots (QDs) into a polystyrene (PS) matrix introduces new properties in the polymeric matrix making this new system a good candidate for improvement in light- emitting devices. A confocal microscope was adapted to scan the spatial distribution of emitted luminescence from the sample surface. Energy transfer processes could be associated with the photon propagation provided by the measured luminescence spatial distribution. We proposed that this energy propagation is caused by the photons capture and emission between the dots and besides other mechanics such as electronic transfer, hopping and resonance. This dynamic process can be understood by the spatial migration of excited states. These facts demonstrate the great importance of the energy transfer, absorption and capture processes in a QD system for the improvement of optical electronic devices. It has been found that re-absorption by ground and excited states plays an important role for the energy propagation. The investigation have been done for a wide range of inter-dot distance in such a way that we could observe how the energy transfer behaves according to this distance. We observed that the photon migration length (PML) increases by increasing the QD concentration and reaches the highest value for a given QD concentration, i.e., for a specific inter-dot distance. However, above this concentration the PML starts to decrease. This behavior indicates that the inter-dots distance is crucial in order to get the highest energy flux inside the sample. Thus, by measuring the PML and its wavelength dependence it is possible to understand the whole dynamics in the QD/PS system. All the processes verified so far give us the possibility to classify the QD/PS system as a good candidate to be employed in an optical QD-based device

  5. Hybrid light transport model based bioluminescence tomography reconstruction for early gastric cancer detection

    Science.gov (United States)

    Chen, Xueli; Liang, Jimin; Hu, Hao; Qu, Xiaochao; Yang, Defu; Chen, Duofang; Zhu, Shouping; Tian, Jie

    2012-03-01

    Gastric cancer is the second cause of cancer-related death in the world, and it remains difficult to cure because it has been in late-stage once that is found. Early gastric cancer detection becomes an effective approach to decrease the gastric cancer mortality. Bioluminescence tomography (BLT) has been applied to detect early liver cancer and prostate cancer metastasis. However, the gastric cancer commonly originates from the gastric mucosa and grows outwards. The bioluminescent light will pass through a non-scattering region constructed by gastric pouch when it transports in tissues. Thus, the current BLT reconstruction algorithms based on the approximation model of radiative transfer equation are not optimal to handle this problem. To address the gastric cancer specific problem, this paper presents a novel reconstruction algorithm that uses a hybrid light transport model to describe the bioluminescent light propagation in tissues. The radiosity theory integrated with the diffusion equation to form the hybrid light transport model is utilized to describe light propagation in the non-scattering region. After the finite element discretization, the hybrid light transport model is converted into a minimization problem which fuses an l1 norm based regularization term to reveal the sparsity of bioluminescent source distribution. The performance of the reconstruction algorithm is first demonstrated with a digital mouse based simulation with the reconstruction error less than 1mm. An in situ gastric cancer-bearing nude mouse based experiment is then conducted. The primary result reveals the ability of the novel BLT reconstruction algorithm in early gastric cancer detection.

  6. 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...

  7. Potential environmental impacts of light-emitting diodes (LEDs): metallic resources, toxicity, and hazardous waste classification.

    Science.gov (United States)

    Lim, Seong-Rin; Kang, Daniel; Ogunseitan, Oladele A; Schoenung, Julie M

    2011-01-01

    Light-emitting diodes (LEDs) are advertised as environmentally friendly because they are energy efficient and mercury-free. This study aimed to determine if LEDs engender other forms of environmental and human health impacts, and to characterize variation across different LEDs based on color and intensity. The objectives are as follows: (i) to use standardized leachability tests to examine whether LEDs are to be categorized as hazardous waste under existing United States federal and California state regulations; and (ii) to use material life cycle impact and hazard assessment methods to evaluate resource depletion and toxicity potentials of LEDs based on their metallic constituents. According to federal standards, LEDs are not hazardous except for low-intensity red LEDs, which leached Pb at levels exceeding regulatory limits (186 mg/L; regulatory limit: 5). However, according to California regulations, excessive levels of copper (up to 3892 mg/kg; limit: 2500), Pb (up to 8103 mg/kg; limit: 1000), nickel (up to 4797 mg/kg; limit: 2000), or silver (up to 721 mg/kg; limit: 500) render all except low-intensity yellow LEDs hazardous. The environmental burden associated with resource depletion potentials derives primarily from gold and silver, whereas the burden from toxicity potentials is associated primarily with arsenic, copper, nickel, lead, iron, and silver. Establishing benchmark levels of these substances can help manufacturers implement design for environment through informed materials substitution, can motivate recyclers and waste management teams to recognize resource value and occupational hazards, and can inform policymakers who establish waste management policies for LEDs.

  8. Propagators for gauge-invariant observables in cosmology

    Science.gov (United States)

    Fröb, Markus B.; Lima, William C. C.

    2018-05-01

    We make a proposal for gauge-invariant observables in perturbative quantum gravity in cosmological spacetimes, building on the recent work of Brunetti et al (2016 J. High Energy Phys. JHEP08(2016)032). These observables are relational, and are obtained by evaluating the field operator in a field-dependent coordinate system. We show that it is possible to define this coordinate system such that the non-localities inherent in any higher-order observable in quantum gravity are causal, i.e. the value of the gauge-invariant observable at a point x only depends on the metric and inflation perturbations in the past light cone of x. We then construct propagators for the metric and inflaton perturbations in a gauge adapted to that coordinate system, which simplifies the calculation of loop corrections, and give explicit expressions for relevant cases: matter- and radiation-dominated eras and slow-roll inflation.

  9. Time-resolved broadband analysis of slow-light propagation and superluminal transmission of electromagnetic waves in three-dimensional photonic crystals

    NARCIS (Netherlands)

    Gómez Rivas, J.; Farré Benet, A.; Niehusmann, J.; Haring Bolivar, P.; Kurz, H.

    2005-01-01

    A time-resolved analysis of the amplitude and phase of THz pulses propagating through three-dimensional photonic crystals is presented. Single-cycle pulses of THz radiation allow measurements over a wide frequency range, spanning more than an octave below, at and above the bandgap of strongly

  10. Vulnerability of countries to food-production crises propagating in the virtual water trade network

    Science.gov (United States)

    Tamea, S.; Laio, F.; Ridolfi, L.

    2015-12-01

    In recent years, the international trade of food and agricultural commodities has undergone a marked increase of exchanged volumes and an expansion of the trade network. This globalization of trade has both positive and negative effects, but the interconnectedness and external dependency of countries generate complex dynamics which are often difficult to understand and model. In this study we consider the volume of water used for the production of agricultural commodities, virtually exchanged among countries through commodity trade, i.e. the virtual water trade. Then, we set up a parsimonious mechanistic model describing the propagation, into the global trade network, of food-production crises generated locally by a social, economic or environmental event (such as war, economic crisis, drought, pest). The model, accounting for the network structure and the virtual water balance of all countries, bases on rules derived from observed virtual water flows and on data-based and statistically verified assumption. It is also tested on real case studies that prove its capability to capture the main features of crises propagation. The model is then employed as the basis for the development of an index of country vulnerability, measuring the exposure of countries to crises propagating in the virtual water trade network. Results of the analysis are discussed within the context of socio-economic and environmental conditions of countries, showing that not only water-scarce, but also wealthy and globalized countries, are among the most vulnerable to external crises. The temporal analysis for the period 1986-2011 reveals that the global average vulnerability has strongly increased over time, confirming the increased exposure of countries to external crises which may occur in the virtual water trade network.

  11. Environmental justice and environmental inequalities: A European perspective

    International Nuclear Information System (INIS)

    Laurent, Eloi

    2010-03-01

    In this paper, I highlight a pressing issue facing current and future social policies in the EU: the articulation between social justice and environmental concerns. European social policies have only recently acknowledged the need to integrate the notions of environmental justice and environmental inequalities, which have been part of the US policy arsenal for almost two decades. Indeed, challenges to equality and fairness in the environmental domain are many and growing in Europe. After having defined environmental justice and environmental inequalities in the light of historical developments and recent literature, I address two dimensions of those challenges for the EU: vulnerability and exposure to environmental risk; social fairness in environmental taxation. I finally offer some thoughts on the importance of the justice approach to environmental issues in order to conceive legitimate 'socio-ecological policies' able to change in the long run not only behaviours but attitudes of citizens towards the environment. (author)

  12. NLO error propagation exercise: statistical results

    International Nuclear Information System (INIS)

    Pack, D.J.; Downing, D.J.

    1985-09-01

    Error propagation is the extrapolation and cumulation of uncertainty (variance) above total amounts of special nuclear material, for example, uranium or 235 U, that are present in a defined location at a given time. The uncertainty results from the inevitable inexactness of individual measurements of weight, uranium concentration, 235 U enrichment, etc. The extrapolated and cumulated uncertainty leads directly to quantified limits of error on inventory differences (LEIDs) for such material. The NLO error propagation exercise was planned as a field demonstration of the utilization of statistical error propagation methodology at the Feed Materials Production Center in Fernald, Ohio from April 1 to July 1, 1983 in a single material balance area formed specially for the exercise. Major elements of the error propagation methodology were: variance approximation by Taylor Series expansion; variance cumulation by uncorrelated primary error sources as suggested by Jaech; random effects ANOVA model estimation of variance effects (systematic error); provision for inclusion of process variance in addition to measurement variance; and exclusion of static material. The methodology was applied to material balance area transactions from the indicated time period through a FORTRAN computer code developed specifically for this purpose on the NLO HP-3000 computer. This paper contains a complete description of the error propagation methodology and a full summary of the numerical results of applying the methodlogy in the field demonstration. The error propagation LEIDs did encompass the actual uranium and 235 U inventory differences. Further, one can see that error propagation actually provides guidance for reducing inventory differences and LEIDs in future time periods

  13. Environmental Remediation Science at Beamline X26A at the National Synchrotron Light Source- Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bertsch, Paul [Univ. of Kentucky, Lexington, KY (United States)

    2013-11-07

    The goal of this project was to provide support for an advanced X-ray microspectroscopy facility at the National Synchrotron Light Source, Brookhaven National Laboratory. This facility is operated by the University of Chicago and the University of Kentucky. The facility is available to researchers at both institutions as well as researchers around the globe through the general user program. This facility was successfully supported during the project period. It provided access to advanced X-ray microanalysis techniques which lead to fundamental advances in understanding the behavior of contaminants and geochemistry that is applicable to environmental remediation of DOE legacy sites as well as contaminated sites around the United States and beyond.

  14. Near-field imaging of out-of-plane light scattering in photonic crystal slabs

    DEFF Research Database (Denmark)

    Volkov, Valentyn; Bozhevolnyi, Sergey; Taillaert, Dirk

    2003-01-01

    A collection scanning near-field optical microscope (SNOM) is used to image the propagating of light at telecommunication wavelengths (1520-1570 nm) along photonic crystal (PC) slabs, which combine slab waveguides with in-plane PCs consisting of one- and two-dimensional gratings. The efficient out...

  15. HPLC-DAD-ESI/MS Identification of Light Harvesting and Light Screening Pigments in the Lake Sediments at Edmonson Point

    Directory of Open Access Journals (Sweden)

    Rita Giovannetti

    2013-01-01

    Full Text Available The composition of sedimentary pigments in the Antarctic lake at Edmonson Point has been investigated and compared with the aim to provide a useful analytical method for pigments separation and identification, providing reference data for future assessment of possible changes in environmental conditions. Reversed phase high performance liquid chromatography (HPLC with electrospray-mass spectrometry (ESI-MS detection and diode array detection (DAD has been used to identify light screening and light harvesting pigments. The results are discussed in terms of local environmental conditions.

  16. Phase-resolved pulse propagation through metallic photonic crystal slabs: plasmonic slow light

    Science.gov (United States)

    Schönhardt, Anja; Nau, Dietmar; Bauer, Christina; Christ, André; Gräbeldinger, Hedi; Giessen, Harald

    2017-03-01

    We characterized the electromagnetic field of ultra-short laser pulses after propagation through metallic photonic crystal structures featuring photonic and plasmonic resonances. The complete pulse information, i.e. the envelope and phase of the electromagnetic field, was measured using the technique of cross-correlation frequency resolved optical gating. In good agreement, measurements and scattering matrix simulations show a dispersive behaviour of the spectral phase at the position of the resonances. Asymmetric Fano-type resonances go along with asymmetric phase characteristics. Furthermore, the spectral phase is used to calculate the dispersion of the sample and possible applications in dispersion compensation are investigated. Group refractive indices of 700 and 70 and group delay dispersion values of 90 000 fs2 and 5000 fs2 are achieved in transverse electric and transverse magnetic polarization, respectively. The behaviour of extinction and spectral phase can be understood from an intuitive model using the complex transmission amplitude. An associated depiction in the complex plane is a useful approach in this context. This method promises to be valuable also in photonic crystal and filter design, for example, with regards to the symmetrization of the resonances. This article is part of the themed issue 'New horizons for nanophotonics'.

  17. Effect of Aspect Ratio on the Light Output of Scintillators

    CERN Document Server

    Pauwels, Kristof; Gundacker, S.; Knapitsch, A.; Lecoq, P.

    2012-01-01

    The influence of the geometry of the scintillators is presented in this paper. We focus on the effect of narrowing down the section of crystals that have a given length. The light output of a set of crystals with very similar scintillating properties but different geometries measured with several coupling/wrapping configurations is provided. We observe that crystals shaped in thin rods have a lower light output as compared to bulk or sliced crystals. The effect of unpolishing the crystal faces is also investigated, and it is shown that highest light outputs are not necessarily obtained with crystals having all faces polished. Simulation results based on a realistic model of the crystal that implements light scattering on the crystal edges are in agreement with the experimental data. Fine-tuning of this model would allow us to further explore the details of light propagation in scintillators and would be highly valuable to fast timing detection and highly granular detectors.

  18. One-way propagation of bulk states and robust edge states in photonic crystals with broken inversion and time-reversal symmetries

    Science.gov (United States)

    Lu, Jin-Cheng; Chen, Xiao-Dong; Deng, Wei-Min; Chen, Min; Dong, Jian-Wen

    2018-07-01

    The valley is a flexible degree of freedom for light manipulation in photonic systems. In this work, we introduce the valley concept in magnetic photonic crystals with broken inversion symmetry. One-way propagation of bulk states is demonstrated by exploiting the pseudo-gap where bulk states only exist at one single valley. In addition, the transition between Hall and valley-Hall nontrivial topological phases is also studied in terms of the competition between the broken inversion and time-reversal symmetries. At the photonic boundary between two topologically distinct photonic crystals, we illustrate the one-way propagation of edge states and demonstrate their robustness against defects.

  19. Rapid Vegetative Propagation Method for Carob

    OpenAIRE

    Hamide GUBBUK; Esma GUNES; Tomas AYALA-SILVA; Sezai ERCISLI

    2011-01-01

    Most of fruit species are propagated by vegetative methods such as budding, grafting, cutting, suckering, layering etc. to avoid heterozygocity. Carob trees (Ceratonia siliqua L.) are of highly economical value and are among the most difficult to propagate fruit species. In the study, air-layering propagation method was investigated first time to compare wild and cultivated (�Sisam�) carob types. In the experiment, one year old carob limbs were air-layered on coco peat medium by wrapping with...

  20. Development of a wind farm noise propagation prediction model - project progress to date

    International Nuclear Information System (INIS)

    Robinson, P.; Bullmore, A.; Bass, J.; Sloth, E.

    1998-01-01

    This paper describes a twelve month measurement campaign which is part of a European project (CEC Project JOR3-CT95-0051) with the aim to substantially reduce the uncertainties involved in predicting environmentally radiated noise levels from wind farms (1). This will be achieved by comparing noise levels measure at varying distances from single and multiple sources over differing complexities of terrain with those predicted using a number of currently adopted sound propagation models. Specific objectives within the project are to: establish the important parameters controlling the propagation of wind farm noise to the far field; develop a planning tool for predicting wind farm noise emission levels under practically encountered conditions; place confidence limits on the upper and lower bounds of the noise levels predicted, thus enabling developers to quantify the risk whether noise emission from wind farms will cause nuisance to nearby residents. (Author)

  1. Upgrading environmental radiation data: health physics society committee report HPSR-1 (1980)

    International Nuclear Information System (INIS)

    1980-08-01

    This report is a collection of nine individual Health Physics Society subcommittee reports on different aspects of environmental radiation data associated with nuclear power plants. The subcommittee reports include: Environmental Radiation Monitoring Objectives, Definition of Critical Pathways and Radionuclides for Population Radiation Exposure at Nuclear Power Stations, Propagation of Uncertainties in Environmental Pathway Dose Models, Detection of Changes in Environmental Levels Due to Nuclear Power Plants, Quality Assurance for Environmental Monitoring Programs, Reporting of Environmental Radiation Measurements Data, Statistical Methods for Environmental Radiation Data Interpretation, Effective Communication with the Public, Environmental Radiological Surveillance-Mechanisms for Information Exchange

  2. Motion-free hybrid design laser beam propagation analyzer using a digital micromirror device and a variable focus liquid lens.

    Science.gov (United States)

    Sheikh, Mumtaz; Riza, Nabeel A

    2010-06-01

    To the best of our knowledge, we propose the first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL). Unlike prior analyzers that require profiling the beam at multiple locations along the light propagation axis, the proposed analyzer profiles the beam at the same plane for multiple values of the ECVFL focal length, thus eliminating beam profiler assembly motion. In addition to measuring standard Gaussian beam parameters, the analyzer can also be used to measure the M(2) beam propagation parameter of a multimode beam. Proof-of-concept beam parameter measurements with the proposed analyzer are successfully conducted for a 633 nm laser beam. Given the all-digital nature of the DMD-based profiling and all-analog motion-free nature of the ECVFL beam focus control, the proposed analyzer versus prior art promises better repeatability, speed, and reliability.

  3. Gigavolt Bound free Transitions Driven by Extreme Light

    Science.gov (United States)

    2016-05-12

    photoelectron spectrum in the ultra-relativistic limit of tunneling ionization is strongly af- fected by wave -particle resonance and finite spot-size...generation. The red area represents the confocal region of an extreme light laser pulse propagating from left to right. Electrons ionized from low...envelope. This is determined by monitoring the number of ionization FIG. 3: Benchmarking the two-step model in the plane wave limit, with a = 36, Z = 18

  4. 3D characterization of the forces in optical traps based on counter-propagation beams shaped by a spatial light modulator

    DEFF Research Database (Denmark)

    Kristensen, M. V.; Lindballe, T.; Kylling, A.

    2010-01-01

    An experimental characterization of the 3D forces, acting on a trapped polystyrene bead in a counter-propagating beam geometry, is reported. Using a single optical trap with a large working distance (in the BioPhotonics Workstation), we simultaneously measure the transverse and longitudinal...... trapping force constants. Two different methods were used: The Drag force method and the Equipartition method. We show that the counterpropagating beams traps are simple harmonic for small displacements. The force constants reveal a transverse asymmetry as - = 9.7 pN/µm and + = 11.3 pN/µm (at a total laser...... power of 2x35 mW) for displacements in opposite directions. The Equipartition method is limited by mechanical noise and is shown to be applicable only when the total laser power in a single 10 µm counter-propagating trap is below 2x20 mW....

  5. On the power propagation time of a graph

    OpenAIRE

    Bozeman, Chassidy

    2016-01-01

    In this paper, we give Nordhaus-Gaddum upper and lower bounds on the sum of the power propagation time of a graph and its complement, and we consider the effects of edge subdivisions and edge contractions on the power propagation time of a graph. We also study a generalization of power propagation time, known as $k-$power propagation time, by characterizing all simple graphs on $n$ vertices whose $k-$power propagation time is $n-1$ or $n-2$ (for $k\\geq 1$) and $n-3$ (for $k\\geq 2$). We determ...

  6. Chromatic characterization of a three-channel colorimeter using back-propagation neural networks

    Science.gov (United States)

    Pardo, P. J.; Pérez, A. L.; Suero, M. I.

    2004-09-01

    This work describes a method for the chromatic characterization of a three-channel colorimeter of recent design and construction dedicated to color vision research. The colorimeter consists of two fixed monochromators and a third monochromator interchangeable with a cathode ray tube or any other external light source. Back-propagation neural networks were used for the chromatic characterization to establish the relationship between each monochromator's input parameters and the tristimulus values of each chromatic stimulus generated. The results showed the effectiveness of this type of neural-network-based system for the chromatic characterization of the stimuli produced by any monochromator.

  7. Light scattering by rough surfaces for increase of absorption of low band gap light in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kloppstech, Konstantin; Knabe, Sebastian; Bauer, Gottfried H. [Institute of Physics, Carl von Ossietzky University Oldenburg (Germany)

    2011-07-01

    Scattering of low band gap light for the increase of the absorption of low band gap photons is commonly formulated in phenomenological magnitudes such as haze factors resulting from experiments at particular scattering media. We have formulated analytically and described by numerical simulations the scattering of light by the interaction of photons with rough surfaces based on wave numbers of photons k{sub {lambda}} and wave numbers of the topological surface contour k{sub s} that has been derived in 2 dimensions via AFM analyses of the contour function h(x,y) of the scattering medium, e.g. a glassy diffusor. We have distinguished two regimes: i) k{sub {lambda}}propagation at phase border between different media, and ii) k{sub {lambda}}{proportional_to}k{sub s}, where the propagation of photons after scattering has been formulated on Huygens' Principle with generation of spherical waves at the respective position h(x,y). The experimental scattering of photons with different wavelengths - recorded with a standard type goniometer - are compared with the simulation of numerically generated far field results in dependence of distance r from the scattering medium and scattering angle {beta}. In particular for the wave optical approach we find a ''scattering function'' that contains the contour function h(x,y) however that substantially departs from its puristic Fourier Transform.

  8. Determination of plasma velocity from light fluctuations in a cutting torch

    International Nuclear Information System (INIS)

    Prevosto, L.; Mancinelli, B.; Kelly, H.

    2009-01-01

    Measurements of plasma velocities in a 30 A high energy density cutting torch are reported. The velocity diagnostic is based on the analysis of the light fluctuations emitted by the arc which are assumed to propagate with the flow velocity. These light fluctuations originate from plasma temperature and plasma density fluctuations mainly due to hydrodynamic instabilities. Fast photodiodes are employed as the light sensors. The arc core velocity was obtained from spectrally filtered light fluctuations measurements using a band-pass filter to detect light emission fluctuations emitted only from the arc axis. Maximum plasma jet velocities of 5000 m s -1 close to the nozzle exit and about 2000 m s -1 close to the anode were found. The obtained velocity values are in good agreement with those values predicted by a numerical code for a similar torch to that employed in this work.

  9. Diffraction-based study of fatigue crack initiation and propagation in aerospace aluminum alloys

    Science.gov (United States)

    Gupta, Vipul K.

    The crack initiation sites and microstructure-sensitive growth of small fatigue cracks are experimentally characterized in two precipitation-hardened aluminum alloys, 7075-T651 and 7050-T7451, stressed in ambient temperature moist-air (warm-humid) and -50°C dry N2 (cold-dry) environmental conditions. Backscattered electron imaging (BSE) and energy dispersive spectroscopy (EDS) of the fracture surfaces showed that Fe-Cu rich constituent particle clusters are the most common initiation sites within both alloys stressed in either environment. The crack growth within each alloy, on average, was observed to be slowed in the cold-dry environment than in the warm-humid environment, but only at longer crack lengths. Although no overwhelming effects of grain boundaries and grain orientations on small-crack growth were observed, crack growth data showed local fluctuations within individual grains. These observations are understood as crack propagation through the underlying substructure at the crack surface and frequent interaction with low/high-angle grain and subgrain boundaries, during cyclic loading, and, are further attributed to periodic changes in crack propagation path and multiple occurrences of crack-branching observed in the current study. SEM-based stereology in combination with electron backscattered diffraction (EBSD) established fatigue crack surface crystallography within the region from ˜1 to 50 mum of crack initiating particle clusters. Fatigue crack facets were parallel to a wide variety of crystallographic planes, with pole orientations distributed broadly across the irreducible stereographic triangle between the {001} and {101}-poles within both warm-humid and cold-dry environments. The results indicate environmentally affected fatigue cracking in both cases, given the similarity between the observed morphology and crystallography with that of a variety of aerospace aluminum alloys cracked in the presence of moist-air. There was no evidence of

  10. Vacuum Polarization Tensor for QED in the Light Front Gauge

    International Nuclear Information System (INIS)

    Suzuki, A.T.; Soriano, L.A.; Bolzan, J.D.; Sales, J.H.O.

    2012-01-01

    The use of light front coordinates in quantum field theories (QFT) always brought some problems and controversies. In this work we explore some aspects of its formalism with respect to the employment of dimensional regularization in the computation of the photon's self-energy at the one-loop level and how the fermion propagator has an important role in the outcoming results. (author)

  11. 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

  12. Propagation testing multi-cell batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Orendorff, Christopher J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lamb, Joshua [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Steele, Leigh Anna Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Spangler, Scott Wilmer [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-10-01

    Propagation of single point or single cell failures in multi-cell batteries is a significant concern as batteries increase in scale for a variety of civilian and military applications. This report describes the procedure for testing failure propagation along with some representative test results to highlight the potential outcomes for different battery types and designs.

  13. Spectral transfer functions of body waves propagating through a stratified medium. Part 1: Basic theory by means of matrix propagators

    International Nuclear Information System (INIS)

    Macia, R.; Correig, A.M.

    1987-01-01

    Seismic wave propagation is described by a second order differential equation for medium displacement. By Fourier transforming with respect to time and space, wave equation transforms into a system of first order linear differential equations for the Fourier transform of displacement and stress. This system of differential equations is solved by means of Matrix Propagator and applied to the propagation of body waves in stratified media. The matrix propagators corresponding to P-SV and SH waves in homogeneous medium are found as an intermediate step to obtain the spectral response of body waves propagating through a stratified medium with homogeneous layers. (author) 14 refs

  14. Fast Heat Pulse Propagation by Turbulence Spreading

    DEFF Research Database (Denmark)

    Naulin, Volker; Juul Rasmussen, Jens; Mantica, Paola

    2009-01-01

    The propagation of a cold pulse initiated by edge cooling in JET is compared to propagation of the heat wave originating from a modulation of the heating source roughly at mid radius. It is found that the propagation of the cold pulse is by far faster than what could be predicted on the basis of ...

  15. Dynamics of the seasonal airborne propagation of Staphylococcus aureus in academic dental clinics.

    Science.gov (United States)

    Bernardo, Wagner Luiz de Carvalho; Silva, Jeferson Júnior da; Höfling, José Francisco; Rosa, Edvaldo Antônio Ribeiro; Boriollo, Marcelo Fabiano Gomes

    2018-04-05

    Staphylococcus aureus strains can be disseminated during dental treatments and occasionally lead to the contamination and infection of patients and dentists, which is an important public health problem. The dynamics of the airborne propagation and the genetic diversity of S. aureus isolated in an academic dental clinic environment were investigated using isoenzyme typing. Materials and MethodsThe isoenzymes of 44 previously reported isolates were obtained from fresh cultures and extracted using glass beads. Nine isoenzymes were investigated using multilocus enzyme electrophoresis (MLEE). The genetic diversity and relationship among the strains (electrophoretic type - ET) were determined using statistics previously described by Nei25 (1972) and the SAHN grouping method (UPGMA algorithm). Clonal pattern analyses indicated a high level of genetic polymorphism occurring among the 33 ETs, which were grouped into five taxa. Each taxon presented one or more clusters that were moderately related and that contained two or more identical/highly related isolates, revealing seasonal airborne propagation in these dental clinic environments. These data suggest the occurrence of active microevolutionary processes in S. aureus as well as the possibility of environmental propagation during a 14-month time span. Such findings are important to show that multiuser academic dental clinics can retain certain strains that are spreadable to different niches.

  16. Light propagation in disordered media: From Maxwell equations to a spherical p-spin model and light condensation effects

    KAUST Repository

    Toth, Laszlo Daniel

    2013-05-01

    The well-known phenomenon of the formation of a Bose-Einstein condensate (BEC), a striking consequence of the Bose-Einstein statistics, has been traditionally linked to an ensemble of ultra-cold gas molecules. However, classical systems can also exhibit condensation effects; in the field of photonics, for example, signatures of this condensation in the mode dynamics (\\'light condensation\\', LC) have been theoretically investigated and experimentally observed in various types of multimode lasers [1,2 and ref. therein]. © 2013 IEEE.

  17. Nonlinear radial propagation of drift wave turbulence

    International Nuclear Information System (INIS)

    Prakash, M.

    1985-01-01

    We study the linear and the nonlinear radial propagation of drift wave energy in an inhomogeneous plasma. The drift mode excited in such a plasma is dispersive in nature. The drift wave energy spreads out symmetrically along the direction of inhomogeneity with a finite group velocity. To study the effect of the nonlinear coupling on the propagation of energy in a collision free plasma, we solve the Hasegawa-Mima equation as a mixed initial boundary-value problem. The solutions of the linearized equation are used to check the reliability of our numerical calculations. Additional checks are also performed on the invariants of the system. Our results reveal that a pulse gets distorted as it propagates through the medium. The peak of the pulse propagates with a finite velocity that depends on the amplitude of the initial pulse. The polarity of propagation depends on the initial parameters of the pulse. We have also studied drift wave propagation in a resistive plasma. The Hasegawa-Wakatani equations are used to investigate this problem

  18. Assessing Light Pollution in China Based on Nighttime Light Imagery

    Directory of Open Access Journals (Sweden)

    Wei Jiang

    2017-02-01

    Full Text Available Rapid urbanization and economic development inevitably lead to light pollution, which has become a universal environmental issue. In order to reveal the spatiotemporal patterns and evolvement rules of light pollution in China, images from 1992 to 2012 were selected from the Defense Meteorological Satellite Program Operational Linescan System (DMSP/OLS and systematically corrected to ensure consistency. Furthermore, we employed a linear regression trend method and nighttime light index method to demonstrate China’s light pollution characteristics across national, regional, and provincial scales, respectively. We found that: (1 China’s light pollution expanded significantly in provincial capital cities over the past 21 years and hot-spots of light pollution were located in the eastern coastal region. The Yangtze River Delta, Pearl River Delta, and Beijing–Tianjin–Hebei regions have formed light pollution stretch areas; (2 China’s light pollution was mainly focused in areas of north China (NC and east China (EC, which, together, accounted for over 50% of the light pollution for the whole country. The fastest growth of light pollution was observed in northwest China (NWC, followed by southwest China (SWC. The growth rates of east China (EC, central China (CC, and northeast China (NEC were stable, while those of north China (NC and south China (SC declined; (3 Light pollution at the provincial scale was mainly located in the Shandong, Guangdong, and Hebei provinces, whereas the fastest growth of light pollution was in Tibet and Hainan. However, light pollution levels in the developed provinces (Hong Kong, Macao, Shanghai, and Tianjin were higher than those of the undeveloped provinces. Similarly, the light pollution heterogeneities of Taiwan, Beijing, and Shanghai were higher than those of undeveloped western provinces.

  19. Temporal Variability of Canopy Light Use Efficiency and its Environmental Controls in a Subtropical Mangrove Wetland

    Science.gov (United States)

    Zhu, X.

    2016-12-01

    Mangrove wetlands play an important role in global carbon cycle due to their strong carbon sequestration resulting from high plant carbon assimilation and low soil respiration. However, temporal variability of carbon sequestration in mangrove wetlands is less understood since carbon processes of mangrove wetlands are influenced by many complicated and concurrent environmental controls including tidal activities, site climate and soil conditions. Canopy light use efficiency (LUE), is the most important plant physiological parameter that can be used to describe the temporal dynamics of canopy photosynthesis, and therefore a better characterization of temporal variability of canopy LUE will improve our understanding in mangrove photosynthesis and carbon balance. One of our aims is to study the temporal variability of canopy LUE and its environmental controls in a subtropical mangrove wetland. Half-hourly canopy LUE is derived from eddy covariance (EC) carbon flux and photosynthesis active radiation observations, and half-hourly environmental controls we measure include temperature, humidity, precipitation, radiation, tidal height, salinity, etc. Another aim is to explore the links between canopy LUE and spectral indices derived from near-surface tower-based remote sensing (normalized difference vegetation index, enhanced vegetation index, photochemical reflectance index, solar-induced chlorophyll fluorescence, etc.), and then identify potential quantitative relationships for developing remote sensing-based estimation methods of canopy LUE. At present, some instruments in our in-situ observation system have not yet been installed (planned in next months) and therefore we don't have enough measurements to support our analysis. However, a preliminary analysis of our historical EC and climate observations in past several years indicates that canopy LUE shows strong temporal variability and is greatly affected by environmental factors such as tidal activity. Detailed and

  20. Universal self-similarity of propagating populations.

    Science.gov (United States)

    Eliazar, Iddo; Klafter, Joseph

    2010-07-01

    This paper explores the universal self-similarity of propagating populations. The following general propagation model is considered: particles are randomly emitted from the origin of a d-dimensional Euclidean space and propagate randomly and independently of each other in space; all particles share a statistically common--yet arbitrary--motion pattern; each particle has its own random propagation parameters--emission epoch, motion frequency, and motion amplitude. The universally self-similar statistics of the particles' displacements and first passage times (FPTs) are analyzed: statistics which are invariant with respect to the details of the displacement and FPT measurements and with respect to the particles' underlying motion pattern. Analysis concludes that the universally self-similar statistics are governed by Poisson processes with power-law intensities and by the Fréchet and Weibull extreme-value laws.