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Sample records for fair-ddx double diffusion

  1. FAIR-DDX, Double Diffusion Cross-Sections Scattering Matrix Generated from ENDF/B-4 or JENDL-2

    International Nuclear Information System (INIS)

    Minami, Kazuyoshi; Yamano, Naoki

    2001-01-01

    1 - Description of program or function: FAIR-DDX produces double differential (energy and angle) cross sections (DDX) in the form of group-to-group scattering matrices using the evaluated nuclear data libraries JENDL-2 or ENDF/B-IV. The DDX form is useful for verification of the evaluated data, such as the inelastic scattering, through comparison with the experimental DDX values. 2 - Method of solution: DDX uses the file 4 data (angular distribution of secondary neutrons) and the energy and momentum conservation laws. For continuum region reactions, file 5 (energy spectrum of secondary neutrons) is used. To express the angular distribution of secondary neutrons in group-to-group scattering matrices FAIR-DDX adopts a direct angular representation method. 3 - Restrictions on the complexity of the problem: The maximum number of energy groups is 200

  2. The double-diffusive modon

    Science.gov (United States)

    Radko, Timour

    Fully developed two-dimensional salt-finger convection is characterized by the appearance of coherent dipolar eddies which carry relatively fresh and cold fluid upward and salty and warm fluid downward. Such structures are prevalent in the regime in which density stratification is close to neutral and the salt-finger instability is extremely vigorous. The structure and translation velocities of modons are discussed in terms of the asymptotic expansion in which the background density ratio approaches unity. It is argued that the vertical salt flux is driven primarily by double-diffusive modons, which makes it possible to derive explicit expressions for the mixing rates of temperature and salinity as a function of their background gradients. Predictions of the proposed mixing model are successfully tested by direct numerical simulations.

  3. Double diffusivity model under stochastic forcing

    Science.gov (United States)

    Chattopadhyay, Amit K.; Aifantis, Elias C.

    2017-05-01

    The "double diffusivity" model was proposed in the late 1970s, and reworked in the early 1980s, as a continuum counterpart to existing discrete models of diffusion corresponding to high diffusivity paths, such as grain boundaries and dislocation lines. It was later rejuvenated in the 1990s to interpret experimental results on diffusion in polycrystalline and nanocrystalline specimens where grain boundaries and triple grain boundary junctions act as high diffusivity paths. Technically, the model pans out as a system of coupled Fick-type diffusion equations to represent "regular" and "high" diffusivity paths with "source terms" accounting for the mass exchange between the two paths. The model remit was extended by analogy to describe flow in porous media with double porosity, as well as to model heat conduction in media with two nonequilibrium local temperature baths, e.g., ion and electron baths. Uncoupling of the two partial differential equations leads to a higher-ordered diffusion equation, solutions of which could be obtained in terms of classical diffusion equation solutions. Similar equations could also be derived within an "internal length" gradient (ILG) mechanics formulation applied to diffusion problems, i.e., by introducing nonlocal effects, together with inertia and viscosity, in a mechanics based formulation of diffusion theory. While being remarkably successful in studies related to various aspects of transport in inhomogeneous media with deterministic microstructures and nanostructures, its implications in the presence of stochasticity have not yet been considered. This issue becomes particularly important in the case of diffusion in nanopolycrystals whose deterministic ILG-based theoretical calculations predict a relaxation time that is only about one-tenth of the actual experimentally verified time scale. This article provides the "missing link" in this estimation by adding a vital element in the ILG structure, that of stochasticity, that takes into

  4. Conventions and nomenclature for double diffusion encoding NMR and MRI

    DEFF Research Database (Denmark)

    Shemesh, Noam; Jespersen, Sune N; Alexander, Daniel C

    2015-01-01

    , such as double diffusion encoding (DDE) NMR and MRI, may provide novel quantifiable metrics that are less easily inferred from conventional diffusion acquisitions. Despite the growing interest on the topic, the terminology for the pulse sequences, their parameters, and the metrics that can be derived from them...

  5. Rate Theory for Correlated Processes: Double Jumps in Adatom Diffusion

    DEFF Research Database (Denmark)

    Jacobsen, J.; Jacobsen, Karsten Wedel; Sethna, J.

    1997-01-01

    We study the rate of activated motion over multiple barriers, in particular the correlated double jump of an adatom diffusing on a missing-row reconstructed platinum (110) surface. We develop a transition path theory, showing that the activation energy is given by the minimum-energy trajectory...... which succeeds in the double jump. We explicitly calculate this trajectory within an effective-medium molecular dynamics simulation. A cusp in the acceptance region leads to a root T prefactor for the activated rate of double jumps. Theory and numerical results agree....

  6. Diffusion thermopower of a serial double quantum dot

    International Nuclear Information System (INIS)

    Thierschmann, H; Henke, M; Knorr, J; Maier, L; Buhmann, H; Molenkamp, L W; Heyn, C; Hansen, W

    2013-01-01

    We have experimentally studied the diffusion thermopower of a serial double quantum dot, defined electrostatically in a GaAs/AlGaAs heterostructure. We present the thermopower stability diagram for a temperature difference ΔT = (20 ± 10) mK across the device and find a maximum thermovoltage signal of several μV in the vicinity of the triple points. Along a constant energy axis in this regime, the data show a characteristic pattern which is in agreement with Mott's relation and can be well understood within a model of sequential transport. (paper)

  7. Double Diffusive Natural Convection in a Nuclear Waste Repository

    International Nuclear Information System (INIS)

    Y. Hao; J. Nitao; T.A. Buscheck; Y. Sun

    2006-01-01

    In this study, we conduct a two-dimensional numerical analysis of double diffusive natural convection in an emplacement drift for a nuclear waste repository. In-drift heat and moisture transport is driven by combined thermal- and compositional-induced buoyancy forces. Numerical results demonstrate buoyancy-driven convective flow patterns and configurations during both repository heat-up and cool-down phases. It is also shown that boundary conditions, particularly on the drip-shield surface, have strong impacts on the in-drift convective flow and transport

  8. Double-diffusive translation of Earth's inner core

    Science.gov (United States)

    Deguen, R.; Alboussiére, T.; Labrosse, S.

    2018-03-01

    The hemispherical asymmetry of the inner core has been interpreted as resulting form a high-viscosity mode of inner core convection, consisting in a translation of the inner core. A thermally driven translation, as originally proposed, is unlikely if the currently favoured high values of the thermal conductivity of iron at core conditions are correct. We consider here the possibility that inner core translation results from an unstable compositional gradient, which would develop either because the light elements present in the core become increasingly incompatible as the inner core grows, or because of a possibly positive feedback of the development of the F-layer on inner core convection. Though the magnitude of the destabilising effect of the compositional field is predicted to be similar to or smaller than the stabilising effect of the thermal field, the huge difference between thermal and chemical diffusivities implies that double-diffusive instabilities can still arise even if the net buoyancy increases upward. Using linear stability analysis and numerical simulations, we demonstrate that a translation mode can indeed exist if the compositional field is destabilising, even if the temperature profile is subadiabatic, and irrespectively of the relative magnitudes of the composition and potential temperature gradients. The existence of this double diffusive mode of translation requires that the following conditions are met: (i) the compositional profile within the inner core is destabilising, and remains so for a duration longer than the destabilisation timescale (on the order of 200 My, but strongly dependent on the magnitude of the initial perturbation); and (ii) the inner core viscosity is sufficiently large, the required value being a strongly increasing function of the inner core size (e.g. 1017 Pa.s when the inner core was 200 km in radius, and ≃ 3 × 1021 Pa.s at the current inner core size). If these conditions are met, the predicted inner core

  9. Single-particle thermal diffusion of charged colloids: Double-layer theory in a temperature gradient

    NARCIS (Netherlands)

    Dhont, J.K.G.; Briels, Willem J.

    2008-01-01

    The double-layer contribution to the single-particle thermal diffusion coefficient of charged, spherical colloids with arbitrary double-layer thickness is calculated and compared to experiments. The calculation is based on an extension of the Debye-Hückel theory for the double-layer structure that

  10. Numerical simulation of diffuse double layer around microporous electrodes based on the Poisson–Boltzmann equation

    International Nuclear Information System (INIS)

    Kitazumi, Yuki; Shirai, Osamu; Yamamoto, Masahiro; Kano, Kenji

    2013-01-01

    Graphical abstract: - Highlights: • Diffuse double layers overlap with each other in the micropore. • The overlapping of the diffuse double layer affects the double layer capacitance. • The electric field becomes weak in the micropore. • The electroneutrality is unsatisfactory in the micropore. - Abstract: The structure of the diffuse double layer around a nm-sized micropore on porous electrodes has been studied by numerical simulation using the Poisson–Boltzmann equation. The double layer capacitance of the microporous electrode strongly depends on the electrode potential, the electrolyte concentration, and the size of the micropore. The potential and the electrolyte concentration dependence of the capacitance is different from that of the planner electrode based on the Gouy's theory. The overlapping of the diffuse double layer becomes conspicuous in the micropore. The overlapped diffuse double layer provides the mild electric field. The intensified electric field exists at the rim of the orifice of the micropore because of the expansion of the diffuse double layers. The characteristic features of microporous electrodes are caused by the heterogeneity of the electric field around the micropores

  11. Double-diffusive mixed convection in a lid-driven cavity with non ...

    Indian Academy of Sciences (India)

    S SIVASANKARAN

    2017-11-11

    Nov 11, 2017 ... transfer are solved using the finite-volume method. The numerical ... Keywords. Mixed convection; double diffusion; non-uniform heating; lid-driven cavity. 1. ... exhaustive research due to its importance in various engi- neering ...

  12. Ionic diffusion in the double layer at model electrode/molten salt interfaces

    International Nuclear Information System (INIS)

    Tankeshwar, K.; Tosi, M.P.

    1991-08-01

    The anisotropic ionic diffusion coefficients in model electrochemical cells in the molten-salt regime for the electrolyte are evaluated from the ionic density profiles reported in simulation work of Grout and coworkers. A local description of the diffusion processes for counterions and coions in the electrical double layer is obtained from the data. (author). 10 refs, 1 fig., 1 tab

  13. CALCULATIONS OF DOUBLE IMPURITY DIFFUSION IN INTEGRATED CIRCUIT PRODUCTION

    Directory of Open Access Journals (Sweden)

    V. A. Bondarev

    2005-01-01

    Full Text Available Analytical formulae for calculating simultaneous diffusion of two impurities in silicon are presented. The formulae are based on analytical solutions of diffusion equations that have been obtained for the first time by the author while using some special mathematical functions. In contrast to usual formal mathematical approaches, new functions are determined in the process of investigation of real physical models. Algorithms involve some important relations from thermodynamics of irreversible processes and also variational thermodynamic functionals that were previously obtained by the author for transfer processes. Calculations considerably reduce the time required for development of new integrated circuits. 

  14. Double-diffusive natural convection in an enclosure filled with nanofluid using ISPH method

    Directory of Open Access Journals (Sweden)

    Abdelraheem M. Aly

    2016-12-01

    Full Text Available The double-diffusive natural convection in an enclosure filled with nanofluid is studied using ISPH method. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. In addition the thermal energy equations include regular diffusion and cross-diffusion terms. In ISPH algorithm, a semi implicit velocity correction procedure is utilized and the pressure is implicitly evaluated by solving pressure Poisson equation. The results are presented with flow configurations, isotherms, concentration and nanoparticle volume fraction contours and average Nusselt and Sherwood numbers for different cases. The results from this investigation are well validated and have favorable comparisons with previously published results. It is found that, among all cases, a good natural convection can be obtained by considering the double diffusive case. An increase in Soret number accompanied by a decrease in Dufour number results in an increase in average Nusselt number and a decrease in average Sherwood number.

  15. From convection rolls to finger convection in double-diffusive turbulence

    NARCIS (Netherlands)

    Yang, Yantao; Verzicco, Roberto; Lohse, Detlef

    2015-01-01

    Double-diffusive convection (DDC), which is the buoyancy-driven flow with fluid density depending on two scalar components, is ubiquitous in many natural and engineering environments. Of great interests are scalars’ transfer rate and flow structures. Here we systematically investigate DDC flow

  16. Fifth-order amplitude equation for traveling waves in isothermal double diffusive convection

    International Nuclear Information System (INIS)

    Mendoza, S.; Becerril, R.

    2009-01-01

    Third-order amplitude equations for isothermal double diffusive convection are known to hold the tricritical condition all along the oscillatory branch, predicting that stable traveling waves exist Only at the onset of the instability. In order to properly describe stable traveling waves, we perform a fifth-order calculation and present explicitly the corresponding amplitude equation.

  17. Method of moments approach to pricing double barrier contracts in polynomial jump-diffusion models

    NARCIS (Netherlands)

    Eriksson, B.; Pistorius, M.

    2011-01-01

    Abstract: We present a method of moments approach to pricing double barrier contracts when the underlying is modelled by a polynomial jump-diffusion. By general principles the price is linked to certain infinite dimensional linear programming problems. Subsequently approximating these by finite

  18. Diffusion barrier performance of novel Ti/TaN double layers for Cu metallization

    International Nuclear Information System (INIS)

    Zhou, Y.M.; He, M.Z.; Xie, Z.

    2014-01-01

    Highlights: • Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum. • The Ti/TaN double layers improved the adhesion with Cu thin films and showed good diffusion barrier between Cu and SiO 2 /Si up to the annealing condition. • The failure mechanism of Ti/TaN bi-layer is similar with the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si. - Abstract: Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum better than 1 × 10 −3 Pa. Ti/TaN double layers were formed on SiO 2 /Si substrates by DC magnetron sputtering and then the properties of Cu/Ti/TaN/SiO 2 /Si film stacks were studied. It was found that the Ti/TaN double layers provide good diffusion barrier between Cu and SiO 2 /Si up to 750 °C for 30 min. The XRD, Auger and EDS results show that the Cu–Si compounds like Cu 3 Si were formed by Cu diffusion through Ti/TaN barrier for the 800 °C annealed samples. It seems that the improved diffusion barrier property of Cu/Ti/TaN/SiO 2 /Si stack is due to the diffusion of nitrogen along the grain boundaries in Ti layer, which would decrease the defects in Ti film and block the diffusion path for Cu diffusion with increasing annealing temperature. The failure mechanism of Ti/TaN bi-layer is similar to the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si

  19. Improving Breakdown Behavior by Substrate Bias in a Novel Double Epi-layer Lateral Double Diffused MOS Transistor

    International Nuclear Information System (INIS)

    Li Qi; Wang Wei-Dong; Liu Yun; Wei Xue-Ming

    2012-01-01

    A new lateral double diffused MOS (LDMOS) transistor with a double epitaxial layer formed by an n-type substrate and a p-type epitaxial layer is reported (DEL LDMOS). The mechanism of the improved breakdown characteristic is that the high electric field around the drain is reduced by substrate reverse bias, which causes the redistribution of the bulk electric field in the drift region, and the vertical blocking voltage is shared by the drain side and the source side. The numerical results indicate that the trade-off between breakdown voltage and on-resistance of the proposed device is improved greatly in comparison to that of the conventional LDMOS. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Ammonia Diffusion through Nalophan Double Bags: Effect of Concentration Gradient Reduction

    Science.gov (United States)

    Capelli, Laura; Boiardi, Emanuela; Del Rosso, Renato

    2014-01-01

    The ammonia loss through Nalophan bags has been studied. The losses observed for storage conditions and times as allowed by the reference standard for dynamic olfactometry (EN 13725:2003) indicate that odour concentration values due to the presence of small molecules may be significantly underestimated if samples are not analysed immediately after sampling. A diffusion model was used in order to study diffusion through the bag. The study discusses the effect of concentration gradient (ΔC) across the polymeric membrane of the analyte. The ΔC was controlled by using a setup bag called “double bags.” Experimental data show a reduction of ammonia percentage losses due to the effect of the external multibarrier. The expedient of the double bag loaded with the same gas mixture allows a reduced diffusion of ammonia into the inner bag. Comparing the inner bag losses with those of the single bag stored in the same conditions (T, P, u) and with equal geometrical characteristics (S/V, z), it was observed that the inner bag of the double bag displays a 16% loss while the single bag displays a 37% loss. Acting on the ΔC it is possible to achieve a gross reduction of 57% in the ammonia leakage due to diffusion. PMID:25506608

  1. Ammonia diffusion through Nalophan double bags: effect of concentration gradient reduction.

    Science.gov (United States)

    Sironi, Selena; Eusebio, Lidia; Capelli, Laura; Boiardi, Emanuela; Del Rosso, Renato

    2014-01-01

    The ammonia loss through Nalophan bags has been studied. The losses observed for storage conditions and times as allowed by the reference standard for dynamic olfactometry (EN 13725:2003) indicate that odour concentration values due to the presence of small molecules may be significantly underestimated if samples are not analysed immediately after sampling. A diffusion model was used in order to study diffusion through the bag. The study discusses the effect of concentration gradient (ΔC) across the polymeric membrane of the analyte. The ΔC was controlled by using a setup bag called "double bags." Experimental data show a reduction of ammonia percentage losses due to the effect of the external multibarrier. The expedient of the double bag loaded with the same gas mixture allows a reduced diffusion of ammonia into the inner bag. Comparing the inner bag losses with those of the single bag stored in the same conditions (T, P, u) and with equal geometrical characteristics (S/V, z), it was observed that the inner bag of the double bag displays a 16% loss while the single bag displays a 37% loss. Acting on the ΔC it is possible to achieve a gross reduction of 57% in the ammonia leakage due to diffusion.

  2. Effects of radial diffuser hydraulic design on a double-suction centrifugal pump

    Science.gov (United States)

    Hou, H. C.; Zhang, Y. X.; Xu, C.; Zhang, J. Y.; Li, Z. L.

    2016-05-01

    In order to study effects of radial diffuser on hydraulic performance of crude oil pump, the steady CFD numerical method is applied and one large double-suction oil pump running in long-distance pipeline is considered. The research focuses on analysing the influence of its diffuser vane profile on hydraulic performance of oil pump. The four different types of cylindrical vane have been designed by in-house codes mainly including double arcs (DA), triple arcs (TA), equiangular spiral line (ES) and linear variable angle spiral line (LVS). During design process diffuser vane angles at inlet and outlet are tentatively given within a certain range and then the wrapping angle of the four types of diffuser vanes can be calculated automatically. Under the given inlet and outlet angles, the linear variable angle spiral line profile has the biggest wrapping angle and profile length which is good to delay channel diffusion but bring more friction hydraulic loss. Finally the vane camber line is thickened at the certain uniform thickness distribution and the 3D diffuser models are generated. The whole flow passage of oil pump with different types of diffusers under various flow rate conditions are numerically simulated based on RNG k-ɛ turbulent model and SIMPLEC algorithm. The numerical results show that different types of diffusers can bring about great difference on the hydraulic performance of oil pump, of which the ES profile diffuser with its proper setting angle shows the best hydraulic performance and its inner flow field is improved obviously. Compared with the head data from model sample, all designed diffusers can make a certain improvement on head characteristic. At the large flow rate conditions the hydraulic efficiency increases obviously and the best efficiency point shift to the large flow rate range. The ES profile diffuser embodies the better advantages on pump performance which can be explained theoretically that the diffuser actually acts as a diffusion

  3. Double cortex’ sign on FDG-PET/CT in diffuse band heterotopia

    International Nuclear Information System (INIS)

    Tripathi, Madhavi; Tripathi, Manjari; Kumar, Ganesh; Malhotra, Arun; Bal, Chandra Sekhar

    2013-01-01

    F-18 Fluorodeoxyglucose (FDG) Positron emission tomography/Computed Tomography (PET/CT) has come to play an increasingly important role for the pre-surgical evaluation of drug resistant epilepsy and complements Magnetic Resonance Imaging (MRI) in the evaluation of grey matter heterotopias. This case illustrates the characteristic pattern of metabolic abnormality in diffuse band heterotopia (DBH) which is otherwise called double cortex syndrome. The presence of metabolic activity in the heterotopic inner cortical band and in the overlying true cortex gives rise to the ‘double cortex’ sign on FDG-PET, concurrent CT provides a good anato-metabolic coregistration

  4. Double cortex’ sign on FDG-PET/CT in diffuse band heterotopia

    Science.gov (United States)

    Tripathi, Madhavi; Tripathi, Manjari; Kumar, Ganesh; Malhotra, Arun; Bal, Chandra Sekhar

    2013-01-01

    F-18 Fluorodeoxyglucose (FDG) Positron emission tomography/Computed Tomography (PET/CT) has come to play an increasingly important role for the pre-surgical evaluation of drug resistant epilepsy and complements Magnetic Resonance Imaging (MRI) in the evaluation of grey matter heterotopias. This case illustrates the characteristic pattern of metabolic abnormality in diffuse band heterotopia (DBH) which is otherwise called double cortex syndrome. The presence of metabolic activity in the heterotopic inner cortical band and in the overlying true cortex gives rise to the ‘double cortex’ sign on FDG-PET, concurrent CT provides a good anato-metabolic coregistration. PMID:24379541

  5. Analytical and numerical investigation of double diffusion in thermally anisotropy multilayer porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Bennacer, R. [Neuville sur Oise, LEEVAM 5 mail Gay Lussac, Cergy-Pontoise Cedex (France); Mohamad, A.A. [CEERE University of Calgary, Department of Mechanical and Manufacturing Engineering, Calgary, Alberta (Canada); Ganaoui, M.El [Faculte des Sciences et Techniques de Limoges, Limoges (France)

    2005-02-01

    Double-diffusive natural convection within a multilayer anisotropic porous medium is studied numerically and analytically. The domain composed of two horizontal porous layers is subjected to a uniform horizontal heat flux and a vertical mass flux, where only the lower one is thermally anisotropic. Darcy model with classical Boussinesq approximation is used in formulating the mathematical model. The effect of thermal anisotropy and the relative width of the two layers on the flow and transfers is illustrated with characterising the transitions from the diffusive to the convective solution. Results were well compared with respect to a developed analytical approach, based on a parallel flow approximation for thermally anisotropic multilayer media. (orig.)

  6. Chaotic dynamics of large-scale double-diffusive convection in a porous medium

    Science.gov (United States)

    Kondo, Shutaro; Gotoda, Hiroshi; Miyano, Takaya; Tokuda, Isao T.

    2018-02-01

    We have studied chaotic dynamics of large-scale double-diffusive convection of a viscoelastic fluid in a porous medium from the viewpoint of dynamical systems theory. A fifth-order nonlinear dynamical system modeling the double-diffusive convection is theoretically obtained by incorporating the Darcy-Brinkman equation into transport equations through a physical dimensionless parameter representing porosity. We clearly show that the chaotic convective motion becomes much more complicated with increasing porosity. The degree of dynamic instability during chaotic convective motion is quantified by two important measures: the network entropy of the degree distribution in the horizontal visibility graph and the Kaplan-Yorke dimension in terms of Lyapunov exponents. We also present an interesting on-off intermittent phenomenon in the probability distribution of time intervals exhibiting nearly complete synchronization.

  7. Three-dimensional flow of Prandtl fluid with Cattaneo-Christov double diffusion

    Science.gov (United States)

    Hayat, Tasawar; Aziz, Arsalan; Muhammad, Taseer; Alsaedi, Ahmed

    2018-06-01

    This research paper intends to investigate the 3D flow of Prandtl liquid in the existence of improved heat conduction and mass diffusion models. Flow is created by considering linearly bidirectional stretchable sheet. Thermal and concentration diffusions are considered by employing Cattaneo-Christov double diffusion models. Boundary layer approach has been used to simplify the governing PDEs. Suitable nondimensional similarity variables correspond to strong nonlinear ODEs. Optimal homotopy analysis method (OHAM) is employed for solutions development. The role of various pertinent variables on temperature and concentration are analyzed through graphs. The physical quantities such as surface drag coefficients and heat and mass transfer rates at the wall are also plotted and discussed. Our results indicate that the temperature and concentration are decreasing functions of thermal and concentration relaxation parameters respectively.

  8. Role of Rayleigh numbers on characteristics of double diffusive salt fingers

    Science.gov (United States)

    Rehman, F.; Singh, O. P.

    2018-05-01

    Double diffusion convection, driven by two constituents of the fluid with different molecular diffusivity, is widely applied in oceanography and large number of other fields like astrophysics, geology, chemistry and metallurgy. In case of ocean, heat (T) and salinity (S) are the two components with varying diffusivity, where heat diffuses hundred times faster than salt. Component (T) stabilizes the system whereas components (S) destabilizes the system with overall density remains stable and forms the rising and sinking fingers known as salt fingers. Recent observations suggest that salt finger characteristics such as growth rates, wavenumber, and fluxes are strongly depending on the Rayleigh numbers as major driving force. In this paper, we corroborate this observation with the help of experiments, numerical simulations and linear theory. An eigenvalue expression for growth rate is derived from the linearized governing equations with explicit dependence on Rayleigh numbers, density stability ratio, Prandtl number and diffusivity ratio. Expressions for fastest growing fingers are also derived as a function various non-dimensional parameter. The predicted results corroborate well with the data reported from the field measurements, experiments and numerical simulations.

  9. An axisymmetric non-hydrostatic model for double-diffusive water systems

    Science.gov (United States)

    Hilgersom, Koen; Zijlema, Marcel; van de Giesen, Nick

    2018-02-01

    The three-dimensional (3-D) modelling of water systems involving double-diffusive processes is challenging due to the large computation times required to solve the flow and transport of constituents. In 3-D systems that approach axisymmetry around a central location, computation times can be reduced by applying a 2-D axisymmetric model set-up. This article applies the Reynolds-averaged Navier-Stokes equations described in cylindrical coordinates and integrates them to guarantee mass and momentum conservation. The discretized equations are presented in a way that a Cartesian finite-volume model can be easily extended to the developed framework, which is demonstrated by the implementation into a non-hydrostatic free-surface flow model. This model employs temperature- and salinity-dependent densities, molecular diffusivities, and kinematic viscosity. One quantitative case study, based on an analytical solution derived for the radial expansion of a dense water layer, and two qualitative case studies demonstrate a good behaviour of the model for seepage inflows with contrasting salinities and temperatures. Four case studies with respect to double-diffusive processes in a stratified water body demonstrate that turbulent flows are not yet correctly modelled near the interfaces and that an advanced turbulence model is required.

  10. Properties of diffusive systems near a saddle point: application to a quartic double well

    CERN Document Server

    Battezzati, M

    2003-01-01

    This paper aims at the analysis of diffusive properties of unidimensional mechanical systems in the environment of maxima and minima of the potential. It begins with a study of the properties of the singular solutions of the Hamilton-Jacobi-Yasue equation in the above-mentioned environment, in both strong or very small frictional forces. For the quartic symmetrical double-well potential, approximate solutions are found for local validity and the diffusion operator is then calculated in the limits of deep wells and small temperature, the regime being supposed to be aperiodic, with high or moderate values of frictional coefficient. This equation is proved to be nonunique. This operator is then reduced to second order by imposing suitable boundary conditions. Thus an appropriate eigenvalue equation is obtained to describe stationary states in the environment of extremal points of the potential energy function. The main interest of this work relies upon the fact that transition times between wells mainly depend u...

  11. Model and Comparative Study for Flow of Viscoelastic Nanofluids with Cattaneo-Christov Double Diffusion.

    Directory of Open Access Journals (Sweden)

    Tasawar Hayat

    Full Text Available Here two classes of viscoelastic fluids have been analyzed in the presence of Cattaneo-Christov double diffusion expressions of heat and mass transfer. A linearly stretched sheet has been used to create the flow. Thermal and concentration diffusions are characterized firstly by introducing Cattaneo-Christov fluxes. Novel features regarding Brownian motion and thermophoresis are retained. The conversion of nonlinear partial differential system to nonlinear ordinary differential system has been taken into place by using suitable transformations. The resulting nonlinear systems have been solved via convergent approach. Graphs have been sketched in order to investigate how the velocity, temperature and concentration profiles are affected by distinct physical flow parameters. Numerical values of skin friction coefficient and heat and mass transfer rates at the wall are also computed and discussed. Our observations demonstrate that the temperature and concentration fields are decreasing functions of thermal and concentration relaxation parameters.

  12. Double-diffusive convection in a Darcy porous medium saturated with a couple-stress fluid

    International Nuclear Information System (INIS)

    Malashetty, M S; Kollur, Premila; Pal, Dulal

    2010-01-01

    The onset of double-diffusive convection in a couple-stress fluid-saturated horizontal porous layer is studied using linear and weak nonlinear stability analyses. The modified Darcy equation that includes the time derivative term and the inertia term is used to model the momentum equation. The expressions for stationary, oscillatory and finite-amplitude Rayleigh number are obtained as a function of the governing parameters. The effect of couple-stress parameter, solute Rayleigh number, Vadasz number and diffusivity ratio on stationary, oscillatory and finite-amplitude convection is shown graphically. It is found that the couple-stress parameter and the solute Rayleigh number have a stabilizing effect on stationary, oscillatory and finite-amplitude convection. The diffusivity ratio has a destabilizing effect in the case of stationary and finite-amplitude modes, with a dual effect in the case of oscillatory convection. The Vadasz number advances the onset of oscillatory convection. The heat and mass transfer decreases with an increase in the values of couple-stress parameter and diffusivity ratio, while both increase with an increase in the value of the solute Rayleigh number.

  13. Double-tagged fluorescent bacterial bioreporter for the study of polycyclic aromatic hydrocarbon diffusion and bioavailability.

    Science.gov (United States)

    Tecon, Robin; Binggeli, Olivier; van der Meer, Jan R

    2009-09-01

    Bacterial degradation of polycyclic aromatic hydrocarbons (PAHs), ubiquitous contaminants from oil and coal, is typically limited by poor accessibility of the contaminant to the bacteria. In order to measure PAH availability in complex systems, we designed a number of diffusion-based assays with a double-tagged bacterial reporter strain Burkholderia sartisoli RP037-mChe. The reporter strain is capable of mineralizing phenanthrene (PHE) and induces the expression of enhanced green fluorescent protein (eGFP) as a function of the PAH flux to the cell. At the same time, it produces a second autofluorescent protein (mCherry) in constitutive manner. Quantitative epifluorescence imaging was deployed in order to record reporter signals as a function of PAH availability. The reporter strain expressed eGFP proportionally to dosages of naphthalene or PHE in batch liquid cultures. To detect PAH diffusion from solid materials the reporter cells were embedded in 2 cm-sized agarose gel patches, and fluorescence was recorded over time for both markers as a function of distance to the PAH source. eGFP fluorescence gradients measured on known amounts of naphthalene or PHE served as calibration for quantifying PAH availability from contaminated soils. To detect reporter gene expression at even smaller diffusion distances, we mixed and immobilized cells with contaminated soils in an agarose gel. eGFP fluorescence measurements confirmed gel patch diffusion results that exposure to 2-3 mg lampblack soil gave four times higher expression than to material contaminated with 10 or 1 (mg PHE) g(-1).

  14. Double-tagged fluorescent bacterial bioreporter for the study of polycyclic aromatic hydrocarbon diffusion and bioavailability

    Energy Technology Data Exchange (ETDEWEB)

    Tecon, R.; Binggeli, O.; van der Meer, J.R. [University of Lausanne, Lausanne (Switzerland). Dept. of Fundamental Microbiology

    2009-09-15

    Bacterial degradation of polycyclic aromatic hydrocarbons (PAHs), ubiquitous contaminants from oil and coal, is typically limited by poor accessibility of the contaminant to the bacteria. In order to measure PAH availability in complex systems, we designed a number of diffusion-based assays with a double-tagged bacterial reporter strain Burkholderia sartisoli RP037-mChe. The reporter strain is capable of mineralizing phenanthrene (PHE) and induces the expression of enhanced green fluorescent protein (eGFP) as a function of the PAH flux to the cell. At the same time, it produces a second autofluorescent protein (mCherry) in constitutive manner. Quantitative epifluorescence imaging was deployed in order to record reporter signals as a function of PAH availability. The reporter strain expressed eGFP proportionally to dosages of naphthalene or PHE in batch liquid cultures. To detect PAH diffusion from solid materials the reporter cells were embedded in 2 cm-sized agarose gel patches, and fluorescence was recorded over time for both markers as a function of distance to the PAH source. eGFP fluorescence gradients measured on known amounts of naphthalene or PHE served as calibration for quantifying PAH availability from contaminated soils. To detect reporter gene expression at even smaller diffusion distances, we mixed and immobilized cells with contaminated soils in an agarose gel. eGFP fluorescence measurements confirmed gel patch diffusion results that exposure to 2-3 mg lampblack soil gave four times higher expression than to material contaminated with 10 or 1 (mg PHE) g{sup -1}.

  15. Soret-driven double diffusive magneto-convection in couple stress liquid

    Directory of Open Access Journals (Sweden)

    Mishra P.

    2012-07-01

    Full Text Available The stability analysis of Soret driven double diffusive convection for electrically conducting couple stress liquid is investigated theoretically. The couple stress liquid is confined between two horizontal surfaces and a constant vertical magnetic field is applied across the surfaces. Linear stability analysis is used to investigate the effect of various parameters on the onset of convection. Effect of magnetic field on the onset of convection is presented by means of Chandrasekhar number. The problem is analyzed as a function of Chandrasekhar number (Q, positive and negative Soret parameter (S r and couple stress parameter (C, mainly. The results show that the Q, both positive and negative Sr and C delay the onset of convection. The effect of other parameters is also discussed in paper and shown by graphs.

  16. Control strategy on the double-diffusive convection in a nanofluid layer with internal heat generation

    Science.gov (United States)

    Mokhtar, N. F. M.; Khalid, I. K.; Siri, Z.; Ibrahim, Z. B.; Gani, S. S. A.

    2017-10-01

    The influences of feedback control and internal heat source on the onset of Rayleigh-Bénard convection in a horizontal nanofluid layer is studied analytically due to Soret and Dufour parameters. The confining boundaries of the nanofluid layer (bottom boundary-top boundary) are assumed to be free-free, rigid-free, and rigid-rigid, with a source of heat from below. Linear stability theory is applied, and the eigenvalue solution is obtained numerically using the Galerkin technique. Focusing on the stationary convection, it is shown that there is a positive thermal resistance in the presence of feedback control on the onset of double-diffusive convection, while there is a positive thermal efficiency in the existence of internal heat generation. The possibilities of suppress or augment of the Rayleigh-Bénard convection in a nanofluid layer are also discussed in detail.

  17. Analysis of forced convective modified Burgers liquid flow considering Cattaneo-Christov double diffusion

    Science.gov (United States)

    Waqas, M.; Hayat, T.; Shehzad, S. A.; Alsaedi, A.

    2018-03-01

    A mathematical model is formulated to characterize the non-Fourier and Fick's double diffusive models of heat and mass in moving flow of modified Burger's liquid. Temperature-dependent conductivity of liquid is taken into account. The concept of stratification is utilized to govern the equations of energy and mass species. The idea of boundary layer theory is employed to obtain the mathematical model of considered physical problem. The obtained partial differential system is converted into ordinary ones with the help of relevant variables. The homotopic concept lead to the convergent solutions of governing expressions. Convergence is attained and acceptable values are certified by expressing the so called ℏ -curves and numerical benchmark. Several graphs are made for different values of physical constraints to explore the mechanism of heat and mass transportation. We explored that the liquid temperature and concentration are retard for the larger thermal/concentration relaxation time constraint.

  18. Electrodeposition of Polymer Nanostructures using Three Diffuse Double Layers: Polymerization beyond the Liquid/Liquid Interfaces

    Science.gov (United States)

    Divya, Velpula; Sangaranarayanan, M. V.

    2018-04-01

    Nanostructured conducting polymers have received immense attention during the past few decades on account of their phenomenal usefulness in diverse contexts, while the interface between two immiscible liquids is of great interest in chemical and biological applications. Here we propose a novel Electrode(solid)/Electrolyte(aqueous)/Electrolyte(organic) Interfacial assembly for the synthesis of polymeric nanostructures using a novel concept of three diffuse double layers. There exist remarkable differences between the morphologies of the polymers synthesized using the conventional electrode/electrolyte method and that of the new approach. In contrast to the commonly employed electrodeposition at liquid/liquid interfaces, these polymer modified electrodes can be directly employed in diverse applications such as sensors, supercapacitors etc.

  19. Effect of the Wavy permeable Interface on Double Diffusive Natural Convection in a Partially Porous Cavity

    Directory of Open Access Journals (Sweden)

    R Mehdaoui

    2016-09-01

    Full Text Available Two-dimensional, double diffusion, natural convection in a partially porous cavity satured with a binary fluid is investigated numerically. Multiple motions are driven by the external temperature and concentration differences imposed across vertical walls. The wavy interface between fluid and porous layer is horizontal. The equations which describe the fluid flow and heat and mass transfer are described by the Navier-Stokes equations (fluid region, Darcy-Brinkman equation (porous region and energy and mass equations. The finite element method was applied to solve the governing equations. The fluid flow and heat and mass transfer has been investigated for different values of the amplitude and the wave number of the interface and the buoyancy ratio. The results obtained in the form of isotherms, stream lines, isoconcentrations and the Nusselt and Sherwood numbers; show that the wavy interface has a significant effect on the flow and heat and mass transfer.

  20. The onset of double diffusive convection in a viscoelastic fluid-saturated porous layer with non-equilibrium model.

    Directory of Open Access Journals (Sweden)

    Zhixin Yang

    Full Text Available The onset of double diffusive convection in a viscoelastic fluid-saturated porous layer is studied when the fluid and solid phase are not in local thermal equilibrium. The modified Darcy model is used for the momentum equation and a two-field model is used for energy equation each representing the fluid and solid phases separately. The effect of thermal non-equilibrium on the onset of double diffusive convection is discussed. The critical Rayleigh number and the corresponding wave number for the exchange of stability and over-stability are obtained, and the onset criterion for stationary and oscillatory convection is derived analytically and discussed numerically.

  1. Diffuse electric double layer in planar nanostructures due to Fermi-Dirac statistics

    International Nuclear Information System (INIS)

    Drab, Mitja; Kralj-Iglič, Veronika

    2016-01-01

    A double nanocapacitor modelled by two equally charged planar surfaces that confine oppositely charged quanta subjected to Fermi-Dirac statistics is considered theoretically. A global thermodynamic equilibrium was found by minimization of the Helmholtz free energy satisfying constraints that require electroneutrality and fixed total number of confined quanta. The solution obtained by using the Euler–Lagrange method yields self–consistent quantities: distribution of quanta within the pore, electric potential, equilibrium free energy and differential capacitance. Within real values, a rigorous numerical solution and an approximate analytical solution for electrons in the low temperature limit was found. The Fermi–Dirac constraints on the wave functions in the nanopore induced an effect of a diffuse electrical double layer near both charged surfaces. This effect is comparable to the corresponding effect of entropy at finite temperatures and for classical particles, as described by the acknowledged Poisson–Boltzmann theory. At small distances and small surface charges, the electrons are almost evenly distributed within the pore, while at larger distances they condense to the charged surfaces, shielding the electric field. The force between the charged surfaces is repulsive and monotonously decreases with increasing distance between surfaces. The energies stored in the nanocapacitor are up to ≃ 50 eV/nm"2.

  2. Numerical simulation of double-diffusive mixed convective flow in rectangular enclosure with insulated moving lid

    Energy Technology Data Exchange (ETDEWEB)

    Teamah, M.A. [Faculty of Engineering, Alexandria University, Mech. Eng. Dept, Alexandria (Egypt); El-Maghlany, W.M. [Faculty of Engineering, Suez Canal University, Ismailia (Egypt)

    2010-09-15

    The present study is concerned with the mixed convection in a rectangular lid-driven cavity under the combined buoyancy effects of thermal and mass diffusion. Double-diffusive convective flow in a rectangular enclosure with moving upper surface is studied numerically. Both upper and lower surfaces are being insulated and impermeable. Constant different temperatures and concentration are imposed along the vertical walls of the enclosure, steady state laminar regime is considered. The transport equations for continuity, momentum, energy and spices transfer are solved. The numerical results are reported for the effect of Richardson number, Lewis number, and buoyancy ratio on the iso-contours of stream line, temperature, and concentration. In addition, the predicted results for both local and average Nusselt and Sherwood numbers are presented and discussed for various parametric conditions. This study was done for 0.1 <= Le <= 50 and Prandtl number Pr = 0.7. Through out the study the Grashof number and aspect ratio are kept constant at 10{sup 4} and 2 respectively and -10 <= N <= 10, while Richardson number has been varied from 0.01 to 10 to simulate forced convection dominated flow, mixed convection and natural convection dominated flow. (authors)

  3. Investigations on the double gas diffusion backing layer for performance improvement of self-humidified proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Kong, Im Mo; Jung, Aeri; Kim, Min Soo

    2016-01-01

    Highlights: • The performance of self-humidified PEMFCs can be improved with double GDBL. • The effect of double GDBL on water retention capability and membrane hydration was investigated. • In addition to HFR and EIS measurements, numerical analysis was conducted. • Optimized design of double GDBL for self-humidified PEMFC was investigated. • This study provides an inspiration on how to design the double GDBL. - Abstract: In order to simplify the system configuration and downsize the volume, a proton exchange membrane fuel cell (PEMFC) needs to be operated in a self-humidified mode without any external humidifiers. However, in self-humidified PEMFCs, relatively low cell performance is a problem to be solved. In our previous study, a gas diffusion layer (GDL) containing double gas diffusion backing layer (GDBL) coated by single micro porous layer (MPL) was introduced and its effect on the cell performance was evaluated. In the present study, the effect of the double GDBL was investigated by measuring high frequency resistance (HFR) and electrochemical impedance spectroscopy (EIS). In the experiments, the HFR value was remarkably reduced, while the diameter of semicircle of EIS was increased. It means that the membrane hydration was improved due to enhanced water retention capability of the GDL despite of interrupted gas diffusion. The result of numerical analysis also showed that the water retention capability of GDL can be improved with proper structure design of double GDBL. Based on the result, optimized design of double GDBL for water retention was obtained numerically. The result of this study provides useful information on the structural design of GDBL for self-humidified PEMFCs.

  4. Microfluidic preparation and self diffusion PFG-NMR analysis of monodisperse water-in-oil-in-water double emulsions.

    Science.gov (United States)

    Hughes, Eric; Maan, Abid Aslam; Acquistapace, Simone; Burbidge, Adam; Johns, Michael L; Gunes, Deniz Z; Clausen, Pascal; Syrbe, Axel; Hugo, Julien; Schroen, Karin; Miralles, Vincent; Atkins, Tim; Gray, Richard; Homewood, Philip; Zick, Klaus

    2013-01-01

    Monodisperse water-in-oil-in-water (WOW) double emulsions have been prepared using microfluidic glass devices designed and built primarily from off the shelf components. The systems were easy to assemble and use. They were capable of producing double emulsions with an outer droplet size from 100 to 40 μm. Depending on how the devices were operated, double emulsions containing either single or multiple water droplets could be produced. Pulsed-field gradient self-diffusion NMR experiments have been performed on the monodisperse water-in-oil-in-water double emulsions to obtain information on the inner water droplet diameter and the distribution of the water in the different phases of the double emulsion. This has been achieved by applying regularization methods to the self-diffusion data. Using these methods the stability of the double emulsions to osmotic pressure imbalance has been followed by observing the change in the size of the inner water droplets over time. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Diffusion

    International Nuclear Information System (INIS)

    Kubaschewski, O.

    1983-01-01

    The diffusion rate values of titanium, its compounds and alloys are summarized and tabulated. The individual chemical diffusion coefficients and self-diffusion coefficients of certain isotopes are given. Experimental methods are listed which were used for the determination of diffusion coefficients. Some values have been taken over from other studies. Also given are graphs showing the temperature dependences of diffusion and changes in the diffusion coefficient with concentration changes

  6. Stability considerations and a double-diffusive convection model for solar ponds

    Energy Technology Data Exchange (ETDEWEB)

    Lin, E.I.H.; Sha, W.T.; Soo, S.L.

    1979-04-01

    A brief survey is made on the basic principles, current designs and economic advantages of salinity-gradient solar ponds as solar collectors and reservoirs. Solar ponds are well-suited for various AIPH (agricultural and industrial process heat) applications, and as annual storage devices for space heating and cooling. The benefit of an efficient pond is demonstrated via a preliminary economic analysis which suggests the idea of energy farming as a profitable alternative for land usage in the face of rising fuel cost. The economy and reliability of solar-pond operation depend crucially on the stability of the nonconvective gradient zone against disturbances such as generated by a severe weather condition. Attention is focused on the subject of stability, and pertinent existing results are summarized and discussed. Details of the derivation of three-dimensional stability criteria for thermohaline convection with linear gradients are presented. Ten key questions pertaining to stability are posed, whose answers must be sought through extensive analytical and numerical studies. Possible methods of approach toward enhancing solar-pond stability are also discussed. For the numerical studies of pond behavior and stability characteristics, a double-diffusive convection model is proposed. The model can be constructed by extending the three-dimensional thermohydrodynamic computer code COMMIX-SA, following the necessary steps outlined; computational plans are described. Similarities exist between the halothermocline and the thermocline storage systems, and an extended COMMIX-SA will be a valuable tool for the investigation of both.

  7. A global ocean climatological atlas of the Turner angle: implications for double-diffusion and water-mass structure

    Science.gov (United States)

    You, Yuzhu

    2002-11-01

    The 1994 Levitus climatological atlas is used to calculate the Turner angle (named after J. Stewart Turner) to examine which oceanic water masses are favorable for double-diffusion in the form of diffusive convection or salt-fingering and which are doubly stable. This atlas complements the Levitus climatology. It reveals the major double-diffusive signals associated with large-scale water-mass structure. In total, about 44% of the oceans display double-diffusion, of which 30% is salt-fingering and 14% is diffusive double-diffusion. Results show that various central and deep waters are favorable for salt-fingering. The former is due to positive evaporation minus precipitation, and the latter is due to thermohaline circulation, i.e. the southward spreading of relatively warm, salty North Atlantic Deep Water (NADW) overlying cold, fresh Antarctic Bottom Water. In the northern Indian Ocean and eastern North Atlantic, favorable conditions for salt-fingering are found throughout the water column. The Red Sea (including the Persian Gulf) and Mediterranean Sea are the sources of warm, salty water for the ocean. As consequence, temperature and salinity in these outflow regions both decrease from the sea surface to the bottom. On the other hand, ocean currents are in general sluggish in these regions. In the polar and subpolar regions of Arctic and Antarctic, Okhotsk Sea, Gulf of Alaska, the subpolar gyre of the North Pacific, the Labrador Sea, and the Norwegian Sea, the upper layer water is favorable for diffusive convection because of high latitude surface cooling and ice melting. Weak and shallow diffusive convection is also found throughout tropical regions and the Bay of Bengal. The former is due to excessive precipitation over evaporation and rain cooling, and the latter is due to both precipitation and river runoff. Diffusive convection in the ocean's interior is unique to the South Atlantic between Antarctic Intermediate Water and upper NADW (uNADW). It is the

  8. Effect of cavity inclination on a temperature and concentration controlled double diffusive convection at ice plate melting

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, M.; Ishikura, T. [Akita University, Department of Mechanical Engineering, Akita (Japan); Beer, H. [Technische Unversitat Darmstadt, Institut fur Technische Thermodynamik, Darmstadt (Germany)

    2005-03-01

    This paper is concerned with the double diffusive convection due to the melting of an ice plate into a calcium chloride aqueous solution inside a rectangular cavity. It is mainly considered the effect of the cavity inclination {theta} on the melting rate and the mean melting Nusselt- and Sherwood-numbers, experimentally as well as numerically. The ice plate melts spontaneously with decreasing temperature at the melting front even if initially there does not exist a temperature difference between the ice and the liquid. The concentration- and temperature-gradients near the melting front induce double diffusive convection in the liquid, which will affect the melting rate. Experiments reveal that the mean melting mass increases monotonically with increasing cavity inclination. The numerical analysis based on the laminar assumption predicts well the melting mass in the range of {theta}=0-90 , however, under-predicts the melting mass in the range of {theta}=90-180 as compared with the experimental results. (orig.)

  9. Characteristics of Superjunction Lateral-Double-Diffusion Metal Oxide Semiconductor Field Effect Transistor and Degradation after Electrical Stress

    Science.gov (United States)

    Lin, Jyh‑Ling; Lin, Ming‑Jang; Lin, Li‑Jheng

    2006-04-01

    The superjunction lateral double diffusion metal oxide semiconductor field effect has recently received considerable attention. Introducing heavily doped p-type strips to the n-type drift region increases the horizontal depletion capability. Consequently, the doping concentration of the drift region is higher and the conduction resistance is lower than those of conventional lateral-double-diffusion metal oxide semiconductor field effect transistors (LDMOSFETs). These characteristics may increase breakdown voltage (\\mathit{BV}) and reduce specific on-resistance (Ron,sp). In this study, we focus on the electrical characteristics of conventional LDMOSFETs on silicon bulk, silicon-on-insulator (SOI) LDMOSFETs and superjunction LDMOSFETs after bias stress. Additionally, the \\mathit{BV} and Ron,sp of superjunction LDMOSFETs with different N/P drift region widths and different dosages are discussed. Simulation tools, including two-dimensional (2-D) TSPREM-4/MEDICI and three-dimensional (3-D) DAVINCI, were employed to determine the device characteristics.

  10. On a Five-Dimensional Chaotic System Arising from Double-Diffusive Convection in a Fluid Layer

    Directory of Open Access Journals (Sweden)

    R. Idris

    2013-01-01

    Full Text Available A chaotic system arising from double-diffusive convection in a fluid layer is investigated in this paper based on the theory of dynamical systems. A five-dimensional model of chaotic system is obtained using the Galerkin truncated approximation. The results showed that the transition from steady convection to chaos via a Hopf bifurcation produced a limit cycle which may be associated with a homoclinic explosion at a slightly subcritical value of the Rayleigh number.

  11. Orientationally invariant metrics of apparent compartment eccentricity from double pulsed field gradient diffusion experiments

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Lundell, Henrik; Sønderby, Casper Kaae

    2013-01-01

    Pulsed field gradient diffusion sequences (PFG) with multiple diffusion encoding blocks have been indicated to offer new microstructural tissue information, such as the ability to detect nonspherical compartment shapes in macroscopically isotropic samples, i.e. samples with negligible directional...

  12. Double-hit lymphomas constitute a highly aggressive subgroup in diffuse large B-cell lymphomas in the era of rituximab.

    Science.gov (United States)

    Kobayashi, Tsutomu; Tsutsumi, Yasuhiko; Sakamoto, Natsumi; Nagoshi, Hisao; Yamamoto-Sugitani, Mio; Shimura, Yuji; Mizutani, Shinsuke; Matsumoto, Yosuke; Nishida, Kazuhiro; Horiike, Shigeo; Asano, Naoko; Nakamura, Shigeo; Kuroda, Junya; Taniwaki, Masafumi

    2012-11-01

    The incorporation of rituximab in immunochemotherapy has improved treatment outcomes for diffuse large B-cell lymphoma, but the prognosis for some diffuse large B-cell lymphomas remains dismal. Identification of adverse prognostic subgroups is essential for the choice of appropriate therapeutic strategy. We retrospectively investigated the impact of so-called 'double-hit' cytogenetic abnormalities, i.e. cytogenetic abnormalities involving c-MYC co-existing with other poor prognostic cytogenetic abnormalities involving BCL2, BCL6 or BACH2, on treatment outcomes for 93 consecutive diffuse large B-cell lymphoma patients. According to the revised international prognostic index, no patients were cytogenetically diagnosed with double-hit lymphomas in the 'very good' risk group or in the 'good' risk group, while 5 of 33 patients had double-hit lymphomas in the 'poor' risk group. All the double-hit lymphoma patients possessed both nodal and extranodal involvement. The overall complete response rate was 89.3%, overall survival 87.1% and progression-free survival 75.8% over 2 years (median observation period: 644 days). The complete response rates were 93.2% for the non-double-hit lymphoma patients and 40.0% for the double-hit lymphoma patients. Significantly longer progression-free survival and overall survival were observed for the 'very good' and the 'good' risk patients than for the 'poor' risk patients. Moreover, the progression-free survival of double-hit lymphoma was significantly shorter than that of the non-double-hit lymphoma 'poor' risk patients (P = 0.016). In addition, the overall survival of the double-hit lymphoma patients also tended to be shorter than that of the non-double-hit lymphoma 'poor' risk group. The diagnosis of double-hit lymphoma can help discriminate a subgroup of highly aggressive diffuse large B-cell lymphomas and indicate the need for the development of novel therapeutic strategies for double-hit lymphoma.

  13. SOUND TRANSMISSION LOSS OF A DOUBLE-LEAF PARTITION WITH MICRO-PERFORATED PLATE INSERTION UNDER DIFFUSE FIELD INCIDENCE

    Directory of Open Access Journals (Sweden)

    A. Putra

    2013-06-01

    Full Text Available In noise control applications, a double-leaf partition has been applied widely as a lightweight structure for noise insulation, such as in car doors, train bodies, and aircraft fuselages. Unfortunately, the insulation performance deteriorates significantly at mass-air-mass resonance due to coupling between the panels and the air in the gap. This paper investigates the effect of a micro-perforated panel (MPP, inserted in the conventional double-panel partition, on sound transmission loss at troublesome resonant frequencies. It is found that the transmission loss improves at this resonance if the MPP is located at a distance of less than half that of the air gap. A mathematical model is derived for the diffuse field incidence of acoustic loading.

  14. Numerical simulation of nonstationary dissipative structures in 3D double-diffusive convection at large Rayleigh numbers

    Science.gov (United States)

    Kozitskiy, Sergey

    2018-05-01

    Numerical simulation of nonstationary dissipative structures in 3D double-diffusive convection has been performed by using the previously derived system of complex Ginzburg-Landau type amplitude equations, valid in a neighborhood of Hopf bifurcation points. Simulation has shown that the state of spatiotemporal chaos develops in the system. It has the form of nonstationary structures that depend on the parameters of the system. The shape of structures does not depend on the initial conditions, and a limited number of spectral components participate in their formation.

  15. Numerical investigation of double diffusive buoyancy forces induced natural convection in a cavity partially heated and cooled from sidewalls

    Directory of Open Access Journals (Sweden)

    Rasoul Nikbakhti

    2016-03-01

    Full Text Available This paper deals with a numerical investigation of double-diffusive natural convective heat and mass transfer in a cavity filled with Newtonian fluid. The active parts of two vertical walls of the cavity are maintained at fixed but different temperatures and concentrations, while the other two walls, as well as inactive areas of the sidewalls, are considered to be adiabatic and impermeable to mass transfer. The length of the thermally active part equals half of the height. The non-dimensional forms of governing transport equations that describe double-diffusive natural convection for two-dimensional incompressible flow are functions of temperature or energy, concentration, vorticity, and stream-function. The coupled differential equations are discretized via FDM (Finite Difference Method. The Successive-Over-Relaxation (SOR method is used in the solution of the stream function equation. The analysis has been done for an enclosure with different aspect ratios ranging from 0.5 to 11 for three different combinations of partially active sections. The results are presented graphically in terms of streamlines, isotherms and isoconcentrations. In addition, the heat and mass transfer rate in the cavity is measured in terms of the average Nusselt and Sherwood numbers for various parameters including thermal Grashof number, Lewis number, buoyancy ratio and aspect ratio. It is revealed that the placement order of partially thermally active walls and the buoyancy ratio influence significantly the flow pattern and the corresponding heat and mass transfer performance in the cavity.

  16. Kinetics of intercalation of fluorescent probes in magnesium–aluminium layered double hydroxide within a multiscale reaction–diffusion framework

    Science.gov (United States)

    Saliba, Daniel

    2016-01-01

    We report the synthesis of magnesium–aluminium layered double hydroxide (LDH) using a reaction–diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium–aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using in situ steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH. This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’. PMID:27698034

  17. Kinetics of intercalation of fluorescent probes in magnesium-aluminium layered double hydroxide within a multiscale reaction-diffusion framework

    Science.gov (United States)

    Saliba, Daniel; Al-Ghoul, Mazen

    2016-11-01

    We report the synthesis of magnesium-aluminium layered double hydroxide (LDH) using a reaction-diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium-aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using in situ steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  18. A double isotope technique for the detection of diffuse liver disease

    International Nuclear Information System (INIS)

    McCready, V.R.; Seelentag, W.W.; Lillicrap, S.C.; Royal Mardsen Hospital, Sutton, Surrey

    1978-01-01

    Radioisotope, ultrasound and CT X-ray scanning are all moderately successful in diagnosing focal abnormalities of the liver. However, the diagnosis of diffuse disease remains difficult or impossible in spite of recent advances in imaging and biochemical techniques. This paper investigates the possibility of using two radioactive compounds which detect different aspects of liver function to determine the presence of diffuse disease. Normal patients and patients with obvious metastases were studied after an injection of a mixture of Tc 99m sulphur colloid and Gallium 67 citrate. Measurements of the absolute and relative uptake in the liver were made within one hour and at 48 hours using a quantitative dual probe system and a collimated dual detector system. The Tc 99m:Ga-67 ratio was calculated. The ratio for abnormals ranged from 1.5-3.9 mean=2.5 and the normals ranged from 3.67-6.25 (mean=4.5). The technique shows promise in the detection of diffuse disease. (author)

  19. Disruption of Aneuploidy and Senescence Induced by Aurora Inhibition Promotes Intrinsic Apoptosis in Double Hit or Double Expressor Diffuse Large B-cell Lymphomas.

    Science.gov (United States)

    Islam, Shariful; Qi, Wenqing; Morales, Carla; Cooke, Laurence; Spier, Catherine; Weterings, Eric; Mahadevan, Daruka

    2017-10-01

    Double hit (DH) or double expressor (DE) diffuse large B-cell lymphomas (DLBCL) are aggressive non-Hodgkin's lymphomas (NHL) with translocations and/or overexpressions of MYC and BCL-2 , which are difficult to treat. Aurora kinase (AK) inhibition with alisertib in DH/DE-DLBCL induces cell death in ∼30%, while ∼70% are aneuploid and senescent cells (AASC), a mitotic escape mechanism contributing to drug resistance. These AASCs elaborated a high metabolic rate by increased AKT/mTOR and ERK/MAPK activity via BTK signaling through the chronic active B-cell receptor (BCR) pathway. Combinations of alisertib + ibrutinib or alisertib + ibrutinib + rituximab significantly reduced AASCs with enhanced intrinsic cell death. Inhibition of AK + BTK reduced phosphorylation of AKT/mTOR and ERK-1/2, upregulated phospho-H2A-X and Chk-2 (DNA damage), reduced Bcl-6, and decreased Bcl-2 and Bcl-xL and induced apoptosis by PARP cleavage. In a DE-DLBCL SCID mouse xenograft model, ibrutinib alone was inactive, while alisertib + ibrutinib was additive with a tumor growth inhibition (TGI) rate of ∼25%. However, TGI for ibrutinib + rituximab was ∼50% to 60%. In contrast, triple therapy showed a TGI rate of >90%. Kaplan-Meier survival analysis showed that 67% of mice were alive at day 89 with triple therapy versus 20% with ibrutinib + rituximab. All treatments were well tolerated with no changes in body weights. A novel triple therapy consisting of alisertib + ibrutinib + rituximab inhibits AASCs induced by AK inhibition in DH/DE-DLBCL leading to a significant antiproliferative signal, enhanced intrinsic apoptosis and may be of therapeutic potential in these lymphomas. Mol Cancer Ther; 16(10); 2083-93. ©2017 AACR . ©2017 American Association for Cancer Research.

  20. Irradiation of cells by single and double pulses of high intensity radiation: oxygen sensitization and diffusion kinetics

    International Nuclear Information System (INIS)

    Epp, E.R.; Ling, C.C.; Weiss, H.

    1976-01-01

    This paper discusses advances made on both experimental and theoretical approaches involving single and double pulses of high intensity ionizing radiation delivered to cultured bacterial and mammalian cells where the effect of oxygen is concerned. Information gained on the lifetime of oxygen-sensitive species suspected to be produced in critical molecules in irradiated cells and perhaps intimately related to the still unknown mechanisms of oxygen sensitization is described. The diffusion characteristics of oxygen at the cellular level obtained from experimental data are discussed. Current knowledge on intracellular radiolytic oxygen depletion is also presented. Future work on the use of high intensity pulsed radiation as a tool in cellular radiobiological research is outlined. It is expected that obtaining knowledge of the time available for damaged molecules to enter into chemical reactions may lead to insights into the mechanisms of radiation injury in cells, such as those involved in the oxygen effect. (Auth.)

  1. Unsteady magnetohydrodynamics mixed convection flow in a rotating medium with double diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Jiann, Lim Yeou; Ismail, Zulkhibri; Khan, Ilyas; Shafie, Sharidan [Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia)

    2015-05-15

    Exact solutions of an unsteady Magnetohydrodynamics (MHD) flow over an impulsively started vertical plate in a rotating medium are presented. The effects of thermal radiative and thermal diffusion on the fluid flow are also considered. The governing equations are modelled and solved for velocity, temperature and concentration using Laplace transforms technique. Expressions of velocity, temperature and concentration profiles are obtained and their numerical results are presented graphically. Skin friction, Sherwood number and Nusselt number are also computed and presented in tabular forms. The determined solutions can generate a large class of solutions as special cases corresponding to different motions with technical relevance. The results obtained herein may be used to verify the validation of obtained numerical solutions for more complicated fluid flow problems.

  2. Simultaneous fingering, double-diffusive convection, and thermal plumes derived from autocatalytic exothermic reaction fronts

    Science.gov (United States)

    Eskew, Matthew W.; Harrison, Jason; Simoyi, Reuben H.

    2016-11-01

    Oxidation reactions of thiourea by chlorite in a Hele-Shaw cell are excitable, autocatalytic, exothermic, and generate a lateral instability upon being triggered by the autocatalyst. Reagent concentrations used to develop convective instabilities delivered a temperature jump at the wave front of 2.1 K. The reaction zone was 2 mm and due to normal cooling after the wave front, this generated a spike rather than the standard well-studied front propagation. The reaction front has solutal and thermal contributions to density changes that act in opposite directions due to the existence of a positive isothermal density change in the reaction. The competition between these effects generates thermal plumes. The fascinating feature of this system is the coexistence of plumes and fingering in the same solution which alternate in frequency as the front propagates, generating hot and cold spots within the Hele-Shaw cell, and subsequently spatiotemporal inhomogeneities. The small ΔT at the wave front generated thermocapillary convection which competed effectively with thermogravitational forces at low Eötvös Numbers. A simplified reaction-diffusion-convection model was derived for the system. Plume formation is heavily dependent on boundary effects from the cell dimensions. This work was supported by Grant No. CHE-1056366 from the NSF and a Research Professor Grant from the University of KwaZulu-Natal.

  3. Cattaneo-Christov double-diffusion theory for three-dimensional flow of viscoelastic nanofluid with the effect of heat generation/absorption

    Science.gov (United States)

    Hayat, Tasawar; Qayyum, Sajid; Shehzad, Sabir Ali; Alsaedi, Ahmed

    2018-03-01

    The present research article focuses on three-dimensional flow of viscoelastic(second grade) nanofluid in the presence of Cattaneo-Christov double-diffusion theory. Flow caused is due to stretching sheet. Characteristics of heat transfer are interpreted by considering the heat generation/absorption. Nanofluid theory comprises of Brownian motion and thermophoresis. Cattaneo-Christov double-diffusion theory is introduced in the energy and concentration expressions. Such diffusions are developed as a part of formulating the thermal and solutal relaxation times framework. Suitable variables are implemented for the conversion of partial differential systems into a sets of ordinary differential equations. The transformed expressions have been explored through homotopic algorithm. Behavior of sundry variables on the velocities, temperature and concentration are scrutinized graphically. Numerical values of skin friction coefficients are also calculated and examined. Here thermal field enhances for heat generation parameter while reverse situation is noticed for heat absorption parameter.

  4. Experimental study on the self-humidification effect in proton exchange membrane fuel cells containing double gas diffusion backing layer

    International Nuclear Information System (INIS)

    Kong, Im Mo; Choi, Jong Won; Kim, Sung Il; Lee, Eun Sook; Kim, Min Soo

    2015-01-01

    Highlights: • Investigated self-humidification effect of structurally modified GDBLs in PEMFCs. • One conventional and two modified GDLs were prepared. • Structural design of the GDBLs significantly affected self-humidification. • Stacking was found to have negligible effect on self-humidification. • It can be applied readily to self-humidified PEMFCs. - Abstract: Adequate hydration of the membrane is required to ensure high proton conductivity in proton exchange membrane fuel cells (PEMFCs), which, in turn, is required for achieving high cell performances. While external humidifiers are typically used to humidify the supplied air in conventional systems, their use increases the complexity, weight, volume, and parasitic power loss in fuel cell systems, rendering them unviable in some systems, particularly for portable applications. In this study, the structure of a gas diffusion backing layer (GDBL) was modified to enhance the self-humidification effect in PEMFCs. Three types of GDLs were prepared for the experiments: a conventional GDL (GDL-A with uniform single GDBL) and two modified GDLs (GDL-A′B with uniform double GDBL and GDL-A′C with heterogeneous double GDBLs). In order to evaluate the effect of stacking and structural design on the self-humidification characteristics, some characteristics of the GDLs such as contact angle, resistance, and vapor permeation rate were measured. The electrochemical performances of the fuel cells were also measured at various relative humidity (RH) and stoichiometric ratio (SR) conditions. The results showed that stacking had a negligible effect, whereas the structural design of the GDBL had a significant effect on self-humidification. The self-humidification effect and the cell performance were improved significantly in the structurally modified GDBL. In addition, considering the actual field conditions and the results of the present study, it was concluded that the structural modifications made to the GDBL would

  5. Double-diffusive mixed convection in the slot ventilated enclosure with different arrangements of supplying air flow ports

    Directory of Open Access Journals (Sweden)

    Heng-Sheng Cheng

    2015-03-01

    Full Text Available Steady double-diffusive mixed convection in an enclosure with side venting and discrete heat and contaminant sources is numerically studied under supplying upside and returning downside (STRB mode and returning upside and supplying downside mode (RTSB, respectively. The parameters governing the fluid flow include the Grashof number Gr (102–106, Reynolds number Re (100–500, supplying or returning distance H 1/HT (0–2, Prandtl number Pr (0.7, buoyancy ratio N, and Schmidt number Sc. Effects of Gr, Re, and H 1/HT on the flow patterns, thermal, and species transports were numerically investigated concerning STRB and RTSB modes. Fluid flow, heat, and species transports in the enclosure are visualized and analyzed by the contours of stream function, heat function, and mass function, respectively. Air age was also presented to evaluate the freshness of the enclosed fluid. Averaged Nusselt number of the heat source and Sherwood number of the contaminant source are power-law correlated with Gr, Re, and H 1/HT for two ventilation modes, respectively. The correlations demonstrate that the ratio of averaged Nusselt number to Sherwood number was approximately approaching unity, independent of ventilation modes and values of H 1/HT . This investigation could benefit the future design of room ventilation and thermal removals from the electronic chips.

  6. Double-diffusive convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability

    Energy Technology Data Exchange (ETDEWEB)

    Vincze, Miklos; Borcia, Ion; Harlander, Uwe [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology (BTU) Cottbus-Senftenberg, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Gal, Patrice Le, E-mail: vincze.m@lecso.elte.hu [Institut de Recherche sur les Phénomènes Hors Equilibre, CNRS—Aix-Marseille University—Ecole Centrale Marseille, 49 rue F. Joliot-Curie, F-13384 Marseille (France)

    2016-12-15

    A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry data and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non-stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can lead to development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense. (paper)

  7. Non-Equilibrium Thermodynamic Analysis of Double Diffusive, Nanofluid Forced Convection in Catalytic Microreactors with Radiation Effects

    Directory of Open Access Journals (Sweden)

    Lilian Govone

    2017-12-01

    Full Text Available This paper presents a theoretical investigation of the second law performance of double diffusive forced convection in microreactors with the inclusion of nanofluid and radiation effects. The investigated microreactors consist of a single microchannel, fully filled by a porous medium. The transport of heat and mass are analysed by including the thick walls and a first order, catalytic chemical reaction on the internal surfaces of the microchannel. Two sets of thermal boundary conditions are considered on the external surfaces of the microchannel; (1 constant temperature and (2 constant heat flux boundary condition on the lower wall and convective boundary condition on the upper wall. The local thermal non-equilibrium approach is taken to thermally analyse the porous section of the system. The mass dispersion equation is coupled with the transport of heat in the nanofluid flow through consideration of Soret effect. The problem is analytically solved and illustrations of the temperature fields, Nusselt number, total entropy generation rate and performance evaluation criterion (PEC are provided. It is shown that the radiation effect tends to modify the thermal behaviour within the porous section of the system. The radiation parameter also reduces the overall temperature of the system. It is further demonstrated that, expectedly, the nanoparticles reduce the temperature of the system and increase the Nusselt number. The total entropy generation rate and consequently PEC shows a strong relation with radiation parameter and volumetric concentration of nanoparticles.

  8. Double-diffusive convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability

    International Nuclear Information System (INIS)

    Vincze, Miklos; Borcia, Ion; Harlander, Uwe; Gal, Patrice Le

    2016-01-01

    A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry data and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non-stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can lead to development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense. (paper)

  9. A novel planar vertical double-diffused metal-oxide-semiconductor field-effect transistor with inhomogeneous floating islands

    Institute of Scientific and Technical Information of China (English)

    Ren Min; Li Ze-Hong; Liu Xiao-Long; Xie Jia-Xiong; Deng Guang-Min; Zhang Bo

    2011-01-01

    A novel planar vertical double-diffused metal-oxide-semiconductor (VDMOS) structure with an ultra-low specific on-resistance (Ron,sp),whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region,is proposed.The theoretical limit of its Ron,sp is deduced,the influence of structure parameters on the breakdown voltage (BV) and Ron,sp are investigated,and the optimized results with BV of 83 V and Ron,sp of 54 mΩ.mm2 are obtained.Simulations show that the inhomogencous-floating-islands metal-oxide-semiconductor field-effect transistor (MOSFET)has a superior “Ron,sp/BV” trade-off to the conventional VDMOS (a 38% reduction of Ron,sp with the same BV) and the homogeneous-floating-islands MOSFET (a 10% reduction of Ron,sp with the same BV).The inhomogeneous-floatingislands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET.Its reverse recovery peak current,reverse recovery time and reverse recovery charge are about 50,80 and 40% of those of the superjunction MOSFET,respectively.

  10. A novel planar vertical double-diffused metal-oxide-semiconductor field-effect transistor with inhomogeneous floating islands

    International Nuclear Information System (INIS)

    Ren Min; Li Ze-Hong; Liu Xiao-Long; Xie Jia-Xiong; Deng Guang-Min; Zhang Bo

    2011-01-01

    A novel planar vertical double-diffused metal-oxide-semiconductor (VDMOS) structure with an ultra-low specific on-resistance (R on,sp ), whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region, is proposed. The theoretical limit of its R on,sp is deduced, the influence of structure parameters on the breakdown voltage (BV) and R on,sp are investigated, and the optimized results with BV of 83 V and R on,sp of 54 mΩ·mm 2 are obtained. Simulations show that the inhomogeneous-floating-islands metal-oxide-semiconductor field-effect transistor (MOSFET) has a superior 'R on,sp /BV' trade-off to the conventional VDMOS (a 38% reduction of R on,sp with the same BV) and the homogeneous-floating-islands MOSFET (a 10% reduction of R on,sp with the same BV). The inhomogeneous-floating-islands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET. Its reverse recovery peak current, reverse recovery time and reverse recovery charge are about 50, 80 and 40% of those of the superjunction MOSFET, respectively. (interdisciplinary physics and related areas of science and technology)

  11. Ultrafast atomic layer-by-layer oxygen vacancy-exchange diffusion in double-perovskite LnBaCo2O5.5+δ thin films.

    Science.gov (United States)

    Bao, Shanyong; Ma, Chunrui; Chen, Garry; Xu, Xing; Enriquez, Erik; Chen, Chonglin; Zhang, Yamei; Bettis, Jerry L; Whangbo, Myung-Hwan; Dong, Chuang; Zhang, Qingyu

    2014-04-22

    Surface exchange and oxygen vacancy diffusion dynamics were studied in double-perovskites LnBaCo2O5.5+δ (LnBCO) single-crystalline thin films (Ln = Er, Pr; -0.5 atoms in the LnBCO thin films is taking the layer by layer oxygen-vacancy-exchange mechanism. The first principles density functional theory calculations indicate that hydrogen atoms are present in LnBCO as bound to oxygen forming O-H bonds. This unprecedented oscillation phenomenon provides the first direct experimental evidence of the layer by layer oxygen vacancy exchange diffusion mechanism.

  12. A general framework to quantify the effect of restricted diffusion on the NMR signal with applications to double pulsed field gradient NMR experiments.

    Science.gov (United States)

    Ozarslan, Evren; Shemesh, Noam; Basser, Peter J

    2009-03-14

    Based on a description introduced by Robertson, Grebenkov recently introduced a powerful formalism to represent the diffusion-attenuated NMR signal for simple pore geometries such as slabs, cylinders, and spheres analytically. In this work, we extend this multiple correlation function formalism by allowing for possible variations in the direction of the magnetic field gradient waveform. This extension is necessary, for example, to incorporate the effects of imaging gradients in diffusion-weighted NMR imaging scans and in characterizing anisotropy at different length scales via double pulsed field gradient (PFG) experiments. In cylindrical and spherical pores, respectively, two- and three-dimensional vector operators are employed whose form is deduced from Grebenkov's results via elementary operator algebra for the case of cylinders and the Wigner-Eckart theorem for the case of spheres. The theory was validated by comparison with known findings and with experimental double-PFG data obtained from water-filled microcapillaries.

  13. A general framework to quantify the effect of restricted diffusion on the NMR signal with applications to double pulsed field gradient NMR experiments

    Science.gov (United States)

    Özarslan, Evren; Shemesh, Noam; Basser, Peter J.

    2009-03-01

    Based on a description introduced by Robertson, Grebenkov recently introduced a powerful formalism to represent the diffusion-attenuated NMR signal for simple pore geometries such as slabs, cylinders, and spheres analytically. In this work, we extend this multiple correlation function formalism by allowing for possible variations in the direction of the magnetic field gradient waveform. This extension is necessary, for example, to incorporate the effects of imaging gradients in diffusion-weighted NMR imaging scans and in characterizing anisotropy at different length scales via double pulsed field gradient (PFG) experiments. In cylindrical and spherical pores, respectively, two- and three-dimensional vector operators are employed whose form is deduced from Grebenkov's results via elementary operator algebra for the case of cylinders and the Wigner-Eckart theorem for the case of spheres. The theory was validated by comparison with known findings and with experimental double-PFG data obtained from water-filled microcapillaries.

  14. The fortran programme for the calculation of the absorption and double scattering corrections in cross-section measurements with fast neutrons using the monte Carlo method (1963); Programme fortran pour le calcul des corrections d'absorption et de double diffusion dans les mesures de sections efficaces pour les neutrons rapides par la methode de monte-carlo (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    A calculation for double scattering and absorption corrections in fast neutron scattering experiments using Monte-Carlo method is given. Application to cylindrical target is presented in FORTRAN symbolic language. (author) [French] Un calcul des corrections de double diffusion et d'absorption dans les experiences de diffusion de neutrons rapides par la methode de Monte-Carlo est presente. L'application au cas d'une cible cylindrique est traitee en langage symbolique FORTRAN. (auteur)

  15. Thromboembolic events associated with single balloon-, double balloon-, and stent-assisted coil embolization of asymptomatic unruptured cerebral aneurysms: evaluation with diffusion-weighted MR imaging

    International Nuclear Information System (INIS)

    Takigawa, Tomoji; Suzuki, Kensuke; Sugiura, Yoshiki; Suzuki, Ryotaro; Takano, Issei; Shimizu, Nobuyuki; Tanaka, Yoshihiro; Hyodo, Akio

    2014-01-01

    The introduction of the balloon remodeling and stent-assisted technique has revolutionized the approach to coil embolization for wide-neck aneurysms. The purpose of this study was to determine the frequency of thromboembolic events associated with single balloon-assisted, double balloon-assisted, and stent-assisted coil embolization for asymptomatic unruptured aneurysms. A retrospective review was undertaken by 119 patients undergoing coiling with an adjunctive technique for unruptured saccular aneurysms (64 single balloon, 12 double balloon, 43 stent assisted). All underwent diffusion-weighted imaging (DWI) within 24 h after the procedure. DWI showed hyperintense lesions in 48 (40 %) patients, and ten (21 %) of these patients incurred neurological deterioration (permanent, two; transient, eight). Hyperintense lesions were detected significantly more often in procedures with the double balloon-assisted technique (7/12, 58 %) than with the single balloon-assisted technique (16/64, 25 %, p = 0.05). Occurrence of new lesions was significantly higher with the use of stent-assisted technique (25/43, 58 %) than with the single balloon-assisted technique (p = 0.001). Symptomatic ischemic rates were similar between the three groups. The increased number of microcatheters was significantly related to the DWI abnormalities (two microcatheters, 15/63 (23.8 %); three microcatheters, 20/41 (48.8 %) (p = 0.008); four microcatheters, 12/15 (80 %) (p = 0.001)). Thromboembolic events detected on DWI related to coil embolization for unruptured aneurysms are relatively common, especially in association with the double balloon-assisted and stent-assisted techniques. Furthermore, the number of microcatheters is highly correlated with DWI abnormalities. The high rate of thromboembolic events suggests the need for evaluation of platelet reactivity and the addition or change of antiplatelet agents. (orig.)

  16. A comparison of ionizing radiation and high field stress effects in n-channel power vertical double-diffused metal-oxide-semiconductor field-effect transistors

    International Nuclear Information System (INIS)

    Park, Mun-Soo; Na, Inmook; Wie, Chu R.

    2005-01-01

    n-channel power vertical double-diffused metal-oxide-semiconductor field-effect-transistor (VDMOSFET) devices were subjected to a high electric field stress or to a x-ray radiation. The current-voltage and capacitance-voltage measurements show that the channel-side interface and the drain-side interface are affected differently in the case of high electric field stress, whereas the interfaces are nearly uniformly affected in the case of x-ray radiation. This paper also shows that for the gated diode structure of VDMOSFET, the direct-current current-voltage technique measures only the drain-side interface; the subthreshold current-voltage technique measures only the channel-side interface; and the capacitance-voltage technique measures both interfaces simultaneously and clearly distinguishes the two interfaces. The capacitance-voltage technique is suggested to be a good quantitative method to examine both interface regions by a single measurement

  17. Prediction of the moments in advection-diffusion lattice Boltzmann method. II. Attenuation of the boundary layers via double-Λ bounce-back flux scheme

    Science.gov (United States)

    Ginzburg, Irina

    2017-01-01

    to vanish or attenuate the disparity of the modeled transport coefficients with the equilibrium weights without any modification of the BB rule, we propose to use the two-relaxation-times collision operator with free-tunable product of two eigenfunctions Λ . Two different values Λv and Λb are assigned for bulk and boundary nodes, respectively. The rationale behind this is that Λv is adjustable for stability, accuracy, or other purposes, while the corresponding Λb(Λv) controls the primary accommodation effects. Two distinguished but similar functional relations Λb(Λv) are constructed analytically: they preserve advection velocity in parabolic profile, exactly in the two-dimensional channel and very accurately in a three-dimensional cylindrical capillary. For any velocity-weight stencil, the (local) double-Λ BB scheme produces quasi-identical solutions with the (nonlocal) specular-forward reflection for first four moments in a channel. In a capillary, this strategy allows for the accurate modeling of the Taylor-dispersion and non-Gaussian effects. As illustrative example, it is shown that in the flow around a circular obstacle, the double-Λ scheme may also vanish the dependency of mean velocity on the velocity weight; the required value for Λb(Λv) can be identified in a few bisection iterations in given geometry. A positive solution for Λb(Λv) may not exist in pure diffusion, but a sufficiently small value of Λb significantly reduces the disparity in diffusion coefficient with the mass weight in ducts and in the presence of rectangular obstacles. Although Λb also controls the effective position of straight or curved boundaries, the double-Λ scheme deals with the lower-order effects. Its idea and construction may help understanding and amelioration of the anomalous, zero- and first-order behavior of the macroscopic solution in the presence of the bulk and boundary or interface discontinuities, commonly found in multiphase flow and heterogeneous

  18. Numerical and experimental investigation of nonsteady state, natural laminar double diffusive convection on heating surfaces of different geometry; Numerische und experimentelle Untersuchung der instationaeren, natuerlichen, laminaren doppelt diffusen Konvektion an Heizflaechen unterschiedlicher Geometrie

    Energy Technology Data Exchange (ETDEWEB)

    Dosch, J

    1991-12-31

    The aim of this work is the development of a numerical process independent of the geometry of the flow space. The temperature, concentration and speed fields set up with double diffusive convection should be determined by this and their effect on heat transfer should be determined. The numerical process should be used for non-steady state double diffusive convection in various geometries. The results should be verified experimentally with the aid of holographic interferometry. (orig./IHL) [Deutsch] Ziel der vorliegenden Arbeit ist die Entwicklung eines von der Geometrie des Stroemungsraumes unabhaengigen numerischen Verfahrens. Mit ihm sollen die sich bei doppelt diffusiver Konvektion einstellenden Temperatur-, Konzentrations- und Geschwindigkeitsfelder bestimmt und deren Einfluss auf die Waermeuebertragung ermittelt werden. Das numerische Verfahren soll auf die instationaere doppelt diffusive Konvektion in verschiedenen Geometrien angewendet werden. Die Ergebnisse sollen experimentell mit Hilfe der holographischen Interferometrie verifiziert werden. (orig./IHL)

  19. Effect of Internal Heat Source on the Onset of Double-Diffusive Convection in a Rotating Nanofluid Layer with Feedback Control Strategy

    Directory of Open Access Journals (Sweden)

    I. K. Khalid

    2017-01-01

    Full Text Available A linear stability analysis has been carried out to examine the effect of internal heat source on the onset of Rayleigh–Bénard convection in a rotating nanofluid layer with double diffusive coefficients, namely, Soret and Dufour, in the presence of feedback control. The system is heated from below and the model used for the nanofluid layer incorporates the effects of thermophoresis and Brownian motion. Three types of bounding systems of the model have been considered which are as follows: both the lower and upper bounding surfaces are free, the lower is rigid and the upper is free, and both of them are rigid. The eigenvalue equations of the perturbed state were obtained from a normal mode analysis and solved using the Galerkin method. It is found that the effect of internal heat source and Soret parameter destabilizes the nanofluid layer system while increasing the Coriolis force, feedback control, and Dufour parameter helps to postpone the onset of convection. Elevating the modified density ratio hastens the instability in the system and there is no significant effect of modified particle density in a nanofluid system.

  20. Optimization of Vertical Double-Diffused Metal-Oxide Semiconductor (VDMOS) Power Transistor Structure for Use in High Frequencies and Medical Devices.

    Science.gov (United States)

    Farhadi, Rozita; Farhadi, Bita

    2014-01-01

    Power transistors, such as the vertical, double-diffused, metal-oxide semiconductor (VDMOS), are used extensively in the amplifier circuits of medical devices. The aim of this research was to construct a VDMOS power transistor with an optimized structure to enhance the operation of medical devices. First, boron was implanted in silicon by implanting unclamped inductive switching (UIS) and a Faraday shield. The Faraday shield was implanted in order to replace the gate-field parasitic capacitor on the entry part of the device. Also, implanting the UIS was used in order to decrease the effect of parasitic bipolar junction transistor (BJT) of the VDMOS power transistor. The research tool used in this study was Silvaco software. By decreasing the transistor entry resistance in the optimized VDMOS structure, power losses and noise at the entry of the transistor were decreased, and, by increasing the breakdown voltage, the lifetime of the VDMOS transistor lifetime was increased, which resulted in increasing drain flow and decreasing Ron. This consequently resulted in enhancing the operation of high-frequency medical devices that use transistors, such as Radio Frequency (RF) and electrocardiograph machines.

  1. Ultra-low specific on-resistance high-voltage vertical double diffusion metal–oxide–semiconductor field-effect transistor with continuous electron accumulation layer

    International Nuclear Information System (INIS)

    Ma Da; Luo Xiao-Rong; Wei Jie; Tan Qiao; Zhou Kun; Wu Jun-Feng

    2016-01-01

    A new ultra-low specific on-resistance (R on,sp ) vertical double diffusion metal–oxide–semiconductor field-effect transistor (VDMOS) with continuous electron accumulation (CEA) layer, denoted as CEA-VDMOS, is proposed and its new current transport mechanism is investigated. It features a trench gate directly extended to the drain, which includes two PN junctions. In on-state, the electron accumulation layers are formed along the sides of the extended gate and introduce two continuous low-resistance current paths from the source to the drain in a cell pitch. This mechanism not only dramatically reduces the R on,sp but also makes the R on,sp almost independent of the n-pillar doping concentration (N n ). In off-state, the depletion between the n-pillar and p-pillar within the extended trench gate increases the N n , and further reduces the R on,sp . Especially, the two PN junctions within the trench gate support a high gate–drain voltage in the off-state and on-state, respectively. However, the extended gate increases the gate capacitance and thus weakens the dynamic performance to some extent. Therefore, the CEA-VDMOS is more suitable for low and medium frequencies application. Simulation indicates that the CEA-VDMOS reduces the R on,sp by 80% compared with the conventional super-junction VDMOS (CSJ-VDMOS) at the same high breakdown voltage (BV). (paper)

  2. Variation in the electrical properties of 100 V/100 A rated mesh and stripe TDMOSFETs (trench double-diffused MOSFETs) for motor drive applications

    Energy Technology Data Exchange (ETDEWEB)

    Na, Kyoung-Il; Kah, Dong-Ha; Kim, Sang-Gi; Koo, Jin-Gun; Kim, Jong-Dae; Yang, Yil-Suk; Lee, Jin-Ho [Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    The vertical power metal-oxide semiconductor field-effect transistors (MOSFETs) with deep trench structures are the most promising candidates to overcome the trade-off relationship between the ON-resistance (R{sub ON}) and the blocking voltage (BV{sub DS}). Especially, 100 V/100 A rated trench power MOSFETs are used in components of many power systems, such as motors and LED lighting drive ICs, DC-DC converters in electric vehicles, and so on. In this work, we studied variations of the electrical characteristics, such as threshold voltage (V{sub TH}), BV{sub DS}, and drain current drivability, with p-well doping concentration via the SILVACO simulator. From simulation results, we found the BV{sub DS} and the drain current (I{sub D}) as functions of the p-well doping concentration at an ion implantation energy of 80 keV. With increasing of p-well doping concentration in the guard ring region, both V{sub TH} and BV{sub DS} slowly increased, but I{sub D} decreased, because the boron lateral diffusion during the fabrication process below gate trench region affected the doping concentration of the p-body at the active region. Additionally, 100 V/100 A rated trench double-diffused MOSFETs (TDMOSFETs) with meshes and stripes were successfully developed by using a silicon deep etching process. The variations in the electrical properties, such as V{sub TH}, BV{sub DS}, and drain current drivability, of the two different kinds of fabricated devices, with cell design and density in TDMOSFETs were also studied. The BV{sub DS} and the V{sub TH} in the stripe-type TDMOSFET were 110 and 3 V, respectively. However, the V{sub TH} of mesh-type device was smaller 0.5 V than that of stripe-type because of corner effect. The BV{sub DS} improved about 20 V compared to stripe-type TDMOSFET due to edge termination, and the maximum drain current (I{sub D.MAX}) was improved by about 10% due to an increase in the gate width at the same chip size. These effects were reflected in devices with

  3. Variation in the electrical properties of 100 V/100 A rated mesh and stripe TDMOSFETs (trench double-diffused MOSFETs) for motor drive applications

    International Nuclear Information System (INIS)

    Na, Kyoung-Il; Kah, Dong-Ha; Kim, Sang-Gi; Koo, Jin-Gun; Kim, Jong-Dae; Yang, Yil-Suk; Lee, Jin-Ho

    2012-01-01

    The vertical power metal-oxide semiconductor field-effect transistors (MOSFETs) with deep trench structures are the most promising candidates to overcome the trade-off relationship between the ON-resistance (R ON ) and the blocking voltage (BV DS ). Especially, 100 V/100 A rated trench power MOSFETs are used in components of many power systems, such as motors and LED lighting drive ICs, DC-DC converters in electric vehicles, and so on. In this work, we studied variations of the electrical characteristics, such as threshold voltage (V TH ), BV DS , and drain current drivability, with p-well doping concentration via the SILVACO simulator. From simulation results, we found the BV DS and the drain current (I D ) as functions of the p-well doping concentration at an ion implantation energy of 80 keV. With increasing of p-well doping concentration in the guard ring region, both V TH and BV DS slowly increased, but I D decreased, because the boron lateral diffusion during the fabrication process below gate trench region affected the doping concentration of the p-body at the active region. Additionally, 100 V/100 A rated trench double-diffused MOSFETs (TDMOSFETs) with meshes and stripes were successfully developed by using a silicon deep etching process. The variations in the electrical properties, such as V TH , BV DS , and drain current drivability, of the two different kinds of fabricated devices, with cell design and density in TDMOSFETs were also studied. The BV DS and the V TH in the stripe-type TDMOSFET were 110 and 3 V, respectively. However, the V TH of mesh-type device was smaller 0.5 V than that of stripe-type because of corner effect. The BV DS improved about 20 V compared to stripe-type TDMOSFET due to edge termination, and the maximum drain current (I D.MAX ) was improved by about 10% due to an increase in the gate width at the same chip size. These effects were reflected in devices with different cell densities. When the cell density was increased, however

  4. Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS)

    International Nuclear Information System (INIS)

    Kretzschmar, M.; Hainc, N.; Studler, U.; Bieri, O.; Miska, M.; Wiewiorski, M.; Valderrabano, V.

    2015-01-01

    The purpose of this study was to characterize the collagen component of repair tissue (RT) of the talus after autologous matrix-induced chondrogenesis (AMIC) using quantitative T2 and diffusion-weighted imaging. Mean T2 values and diffusion coefficients of AMIC-RT and normal cartilage of the talus of 25 patients with posttraumatic osteochondral lesions and AMIC repair were compared in a cross-sectional design using partially spoiled steady-state free precession (pSSFP) for T2 quantification, and diffusion-weighted double-echo steady-state (dwDESS) for diffusion measurement. RT and cartilage were graded with modified Noyes and MOCART scores on morphological sequences. An association between follow-up interval and quantitative MRI measures was assessed using multivariate regression, after stratifying the cohort according to time interval between surgery and MRI. Mean T2 of the AMIC-RT and cartilage were 43.1 ms and 39.1 ms, respectively (p = 0.26). Mean diffusivity of the RT (1.76 μm 2 /ms) was significantly higher compared to normal cartilage (1.46 μm 2 /ms) (p = 0.0092). No correlation was found between morphological and quantitative parameters. RT diffusivity was lowest in the subgroup with follow-up >28 months (p = 0.027). Compared to T2-mapping, dwDESS demonstrated greater sensitivity in detecting differences in the collagen matrix between AMIC-RT and cartilage. Decreased diffusivity in patients with longer follow-up times may indicate an increased matrix organization of RT. (orig.)

  5. Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS)

    Energy Technology Data Exchange (ETDEWEB)

    Kretzschmar, M.; Hainc, N.; Studler, U. [University Hospital Basel, Department of Radiology, Basel (Switzerland); Bieri, O. [University Hospital Basel, Division of Radiological Physics, Basel (Switzerland); Miska, M. [University Hospital, Department of Orthopedics, Heidelberg (Germany); Wiewiorski, M.; Valderrabano, V. [University Hospital Basel, Department of Orthopedic Surgery, Basel (Switzerland)

    2015-04-01

    The purpose of this study was to characterize the collagen component of repair tissue (RT) of the talus after autologous matrix-induced chondrogenesis (AMIC) using quantitative T2 and diffusion-weighted imaging. Mean T2 values and diffusion coefficients of AMIC-RT and normal cartilage of the talus of 25 patients with posttraumatic osteochondral lesions and AMIC repair were compared in a cross-sectional design using partially spoiled steady-state free precession (pSSFP) for T2 quantification, and diffusion-weighted double-echo steady-state (dwDESS) for diffusion measurement. RT and cartilage were graded with modified Noyes and MOCART scores on morphological sequences. An association between follow-up interval and quantitative MRI measures was assessed using multivariate regression, after stratifying the cohort according to time interval between surgery and MRI. Mean T2 of the AMIC-RT and cartilage were 43.1 ms and 39.1 ms, respectively (p = 0.26). Mean diffusivity of the RT (1.76 μm{sup 2}/ms) was significantly higher compared to normal cartilage (1.46 μm{sup 2}/ms) (p = 0.0092). No correlation was found between morphological and quantitative parameters. RT diffusivity was lowest in the subgroup with follow-up >28 months (p = 0.027). Compared to T2-mapping, dwDESS demonstrated greater sensitivity in detecting differences in the collagen matrix between AMIC-RT and cartilage. Decreased diffusivity in patients with longer follow-up times may indicate an increased matrix organization of RT. (orig.)

  6. Finite Volume Scheme for Double Convection-Diffusion Exchange of Solutes in Bicarbonate High-Flux Hollow-Fiber Dialyzer Therapy

    Directory of Open Access Journals (Sweden)

    Kodwo Annan

    2012-01-01

    Full Text Available The efficiency of a high-flux dialyzer in terms of buffering and toxic solute removal largely depends on the ability to use convection-diffusion mechanism inside the membrane. A two-dimensional transient convection-diffusion model coupled with acid-base correction term was developed. A finite volume technique was used to discretize the model and to numerically simulate it using MATLAB software tool. We observed that small solute concentration gradients peaked and were large enough to activate solute diffusion process in the membrane. While CO2 concentration gradients diminished from their maxima and shifted toward the end of the membrane, concentration gradients peaked at the same position. Also, CO2 concentration decreased rapidly within the first 47 minutes while optimal concentration was achieved within 30 minutes of the therapy. Abnormally high diffusion fluxes were observed near the blood-membrane interface that increased diffusion driving force and enhanced the overall diffusive process. While convective flux dominated total flux during the dialysis session, there was a continuous interference between convection and diffusion fluxes that call for the need to seek minimal interference between these two mechanisms. This is critical for the effective design and operation of high-flux dialyzers.

  7. Diffusion test of probe nuclei 111In(111Cd) in the compounds: LaBaMn2O6 'Double Perovskites' for measurements using PAC spectroscopy

    International Nuclear Information System (INIS)

    Nascimento, Natália M.; Bosch-Santos, Brianna; Sciarreta, Beatriz A.; Carbonari, Artur W.; Sandalo, Danilo S.

    2017-01-01

    Double perovskites of type LaBaMn 2 O 6 and LaBaCo 2 O 6 were made using two processes, sol-gel synthesis and solid state reaction, in order to identify which of the methods is best for insertion and diffusion of the 111 In test core ( 111 Cd) used for perturbed gamma-gamma angular correlation (PAC) spectroscopy measurements. The test core diffusion were performed with thermal treatments in air and at temperatures of 550 ° C, 650 ° C and 750 ° C. By the analysis of the results, the synthesis by Sol-Gel is more efficient for the insertion of the radioactive material, together with the heat treatment at 650 ° C. The advantage of this method is that the radioactive material can be added to the compounds of the synthesis process, even in the solid state reaction method the radioactive material can only be inserted after the ready compound

  8. Nonlinear Cross-Diffusion with Size Exclusion

    KAUST Repository

    Burger, Martin; Di Francesco, Marco; Pietschmann, Jan-Frederik; Schlake, Bä rbel

    2010-01-01

    The aim of this paper is to investigate the mathematical properties of a continuum model for diffusion of multiple species incorporating size exclusion effects. The system for two species leads to nonlinear cross-diffusion terms with double

  9. Double-beam optical method and apparatus for measuring thermal diffusivity and other molecular dynamic processes in utilizing the transient thermal lens effect

    International Nuclear Information System (INIS)

    Gupta, A.; Hong, S.; Moacanin, J.

    1981-01-01

    A method and apparatus for measuring thermal diffusivity and molecular relaxation processes in a sample material utilizing two light beams, one being a pulsed laser light beam for forming a thermal lens in the sample material, and the other being a relatively low power probe light beam for measuring changes in the refractive index of the sample material during formation and dissipation of the thermal lens. More specifically, a sample material is irradiated by relatively high power, short pulses from a dye laser. Energy from the pulses is absorbed by the sample material, thereby forming a thermal lens in the area of absorption. The pulse repetition rate is chosen so that the thermal lens is substantially dissipated by the time the next pulse reaches the sample material. A probe light beam, which in a specific embodiment is a relatively low power, continuous wave (Cw) laser beam, irradiates the thermal lens formed in the sample material. The intensity characteristics of the probe light beam subsequent to irradiation of the thermal lens is related to changes in the refractive index of the sample material as the thermal lens is formed and dissipated. A plot of the changes in refractive index as a function of time during formation of the thermal lens as reflected by changes in intensity of the probe beam, provides a curve related to molecular relaxation characteristics of the material, and a plot during dissipation of the thermal lens provides a curve related to the thermal diffusivity of the sample material

  10. Migration and head penetration of Vitamin-E diffused cemented polyethylene cup compared to standard cemented cup in total hip arthroplasty: study protocol for a randomised, double-blind, controlled trial (E1 HIP).

    Science.gov (United States)

    Sköldenberg, Olof; Rysinska, Agata; Chammout, Ghazi; Salemyr, Mats; Muren, Olle; Bodén, Henrik; Eisler, Thomas

    2016-07-07

    In vitro, Vitamin-E-diffused, highly cross-linked polyethylene (PE) has been shown to have superior wear resistance and improved mechanical properties when compared to those of standard highly cross-linked PE liners used in total hip arthroplasty (THA). The aim of the study is to evaluate the safety of a new cemented acetabular cup with Vitamin-E-doped PE regarding migration, head penetration and clinical results. In this single-centre, double-blinded, randomised controlled trial, we will include 50 patients with primary hip osteoarthritis scheduled for THA and randomise them in a 1:1 ratio to a cemented cup with either argon gas-sterilised PE (control group) or Vitamin-E-diffused PE (vitamin-e group). All patients and the assessor of the primary outcome will be blinded and the same uncemented stem will be used for all participants. The primary end point will be proximal migration of the cup at 2 years after surgery measured with radiostereometry. Secondary end points include proximal migration at other follow-ups, total migration, femoral head penetration, clinical outcome scores and hip-related complications. Patients will be followed up at 3 months and at 1, 2, 5 and 10 years postoperatively. Results will be analysed using 95% CIs for the effect size. A regression model will also be used to adjust for stratification factors. The ethical committee at Karolinska Institutet has approved the study. The first results from the study will be disseminated to the medical community via presentations and publications in relevant medical journals when the last patient included has been followed up for 2 years. NCT02254980. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  11. Modelos de dupla camada difusa de Gouy-Chapman e Stern aplicados a latossolos ácricos paulistas Gouy-chapman and Stern diffuse double layer models applied to acric oxisols from the state São Paulo - Brazil

    Directory of Open Access Journals (Sweden)

    L.R.F. Alleoni

    1994-08-01

    Full Text Available Modelos teóricos da dupla camada difusa de Gouy-Chapman e de Stern foram aplicados a um latossolo variação Una ácrico, de Guaira e a dois latossolos roxos ácricos, localizados em Ribeirão Preto e Guaíra, cidades ao norte do Estado de São Paulo, onde solos com caráter ácrico ocupam vasta área nas quais são cultivadas várias culturas de interesse econômico. Na concentração mais elevada do eletrólito suporte (KCl 0,1N, os dados obtidos em laboratório adaptaram-se melhor ao modelo de Stern. Entretanto, nas menores concentrações (KCl 0,01 e 0,001N, correspondentes a valores mais comuns encontrados em solos altamente intemperizados, o modelo de Gouy-Chapman representou melhor a variação da densidade superficial de carga com o potencial elétrico das amostras estudadas.Theoretical models of Gouy-Chapman and Stern, referred to diffuse double layer, were applied to three acric Oxisols, two named dusky red latosol and one Una variant latosol, from the São Paulo State - Brazil. Samples were collected in Ribeirão Preto and Guaira, regions of large occurrence of these soils, supporting many economic crops. In the highest concentration of the electrolyte (KC1 0.1N, the obtained values were better related to the Stern model. On the other hand, in more dilluted solutions (KC1 0.01 and 0.001N, corresponding to more usual ionic strenght of highly weathered soils, the variation of surface charge density of the samples with electric potential was in better agreement with the Gouy-Chapman theory.

  12. Complex dynamics in double-diffusive convection

    Energy Technology Data Exchange (ETDEWEB)

    Meca, Esteban; Ramirez-Piscina, Laureano [Universitat Politecnica de Catalunya, Departament de Fisica Aplicada, Barcelona (Spain); Mercader, Isabel; Batiste, Oriol [Universitat Politecnica de Catalunya, Departament de Fisica Aplicada, Barcelona (Spain)

    2004-11-01

    The dynamics of a small Prandtl number binary mixture in a laterally heated cavity is studied numerically. By combining temporal integration, steady state solving and linear stability analysis of the full PDE equations, we have been able to locate and characterize a codimension-three degenerate Takens-Bogdanov point whose unfolding describes the dynamics of the system for a certain range of Rayleigh numbers and separation ratios near S=-1. (orig.)

  13. Double diffusive conjugate heat transfer: Part I

    Science.gov (United States)

    Azeem, Soudagar, Manzoor Elahi M.

    2018-05-01

    The present work is undertaken to investigate the effect of solid wall being placed at left of square cavity filled with porous medium. The presence of a solid wall in the porous medium turns the situation into a conjugate heat transfer problem. The boundary conditions are such that the left vertical surface is maintained at highest temperature and concentration whereas right vertical surface at lowest temperature and concentration in the medium. The top and bottom surfaces are adiabatic. The additional conduction equation along with the regular momentum and energy equations of porous medium are solved in an iterative manner with the help of finite element method. It is seen that the heat and mass transfer rate is lesser due to smaller thermal and concentration gradients.

  14. Advanced manufacturing: Technology diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Tesar, A.

    1995-12-01

    In this paper we examine how manufacturing technology diffuses rom the developers of technology across national borders to those who do not have the capability or resources to develop advanced technology on their own. None of the wide variety of technology diffusion mechanisms discussed in this paper are new, yet the opportunities to apply these mechanisms are growing. A dramatic increase in technology diffusion occurred over the last decade. The two major trends which probably drive this increase are a worldwide inclination towards ``freer`` markets and diminishing isolation. Technology is most rapidly diffusing from the US In fact, the US is supplying technology for the rest of the world. The value of the technology supplied by the US more than doubled from 1985 to 1992 (see the Introduction for details). History shows us that technology diffusion is inevitable. It is the rates at which technologies diffuse to other countries which can vary considerably. Manufacturers in these countries are increasingly able to absorb technology. Their manufacturing efficiency is expected to progress as technology becomes increasingly available and utilized.

  15. Study of the background of the neutrinoless double {beta} decay with the detector NEMO 2: contribution arising from the radon diffusion and internal pollution of the source {sup 214}Bi have been estimated; Etude du bruit de fond de la double-desintegration {beta} sans emission de neutrino dans le detecteur NEMO 2: contribution du radon ambiant et mesure de la pollution interne de la source en {sup 214}Bi

    Energy Technology Data Exchange (ETDEWEB)

    Mauger, F.

    1995-02-01

    The NEMO experiment is designed to understand the nature of the neutrino by studying the double beta decay of Mo-100 which is related to the Majorana neutrino effective mass. In this kind of experiment a good understanding of the different sources of background is crucial as only few events are expected per year at the required level of sensitivity. In this thesis we present the main theoretical and experimental aspects of the measurement of the neutrinoless double beta decay of Mo-100 with the prototype detector NEMO2. The goal of this study is to obtain a realistic interpretation of the few events detected at high energy in the two-electron channel as a background to neutrinoless double beta decay. In particular, the contribution arising from Bi-214 has been investigated. These events have been selected and analysed by means of the beta-alpha decays of Bi-214 into Pb-210. The events are characterized by a delayed track in the wire chamber and the corresponding signal is rather clean. The study has demonstrated the diffusion of Rn-222 into the detector and its contribution to Bi-214 pollution has been estimated. A measurement of the Bi-214 internal contamination of the source has been made as well as an estimation of the Bi-214 deposit due to Rn-222. As a result of this study it appears that, under the conditions of the NEMO2 experiment, the Bi and Rn contributions are of the same order of magnitude as the background induced at high energy by two-neutrino double beta decay. In conclusion, the backgrounds of the neutrinoless double beta decay of Mo-100 are well understood in the NEMO2 experiment leading to an extrapolation for the NEMO3 experiment. (authors).

  16. Double Trouble

    NARCIS (Netherlands)

    Elsaesser, Thomas; Kievit, Robert; Simons, Jan

    1994-01-01

    Double Trouble highlights the career of Dutch scriptwriter and television producer Chiem van Houweninge, well-known for his long-running TV comedy series and as author of episodes for TV detective series. Double Trouble gives Van Houweninge's own views on writing and filming in television prime

  17. Conservative diffusions

    International Nuclear Information System (INIS)

    Carlen, E.A.

    1984-01-01

    In Nelson's stochastic mechanics, quantum phenomena are described in terms of diffusions instead of wave functions. These diffusions are formally given by stochastic differential equations with extremely singular coefficients. Using PDE methods, we prove the existence of solutions. This reult provides a rigorous basis for stochastic mechanics. (orig.)

  18. Fractional Diffusion Equations and Anomalous Diffusion

    Science.gov (United States)

    Evangelista, Luiz Roberto; Kaminski Lenzi, Ervin

    2018-01-01

    Preface; 1. Mathematical preliminaries; 2. A survey of the fractional calculus; 3. From normal to anomalous diffusion; 4. Fractional diffusion equations: elementary applications; 5. Fractional diffusion equations: surface effects; 6. Fractional nonlinear diffusion equation; 7. Anomalous diffusion: anisotropic case; 8. Fractional Schrödinger equations; 9. Anomalous diffusion and impedance spectroscopy; 10. The Poisson–Nernst–Planck anomalous (PNPA) models; References; Index.

  19. Double Chooz

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Christian [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

    2006-05-15

    The goal of the Double Chooz reactor neutrino experiment is to search for the neutrino mixing parameter {theta}{sub 13}. Double Chooz will use two identical detectors at 150 m and 1.05 km distance from the reactor cores. The near detector is used to monitor the reactor {nu}-bar {sub e} flux while the second is dedicated to the search for a deviation from the expected (1/distance){sup 2} behavior. This two detector concept will allow a relative normalization systematic error of ca. 0.6 %. The expected sensitivity for sin{sup 2}2{theta}{sub 13} is then in the range 0.02 - 0.03 after three years of data taking. The antineutrinos will be detected in a liquid scintillator through the capture on protons followed by a gamma cascade, produced by the neutron capture on Gd.

  20. Double supergeometry

    Energy Technology Data Exchange (ETDEWEB)

    Cederwall, Martin [Division for Theoretical Physics, Department of Physics, Chalmers University of Technology,SE 412 96 Gothenburg (Sweden)

    2016-06-27

    A geometry of superspace corresponding to double field theory is developed, with type I I supergravity in D=10 as the main example. The formalism is based on an orthosymplectic extension OSp(d,d|2s) of the continuous T-duality group. Covariance under generalised super-diffeomorphisms is manifest. Ordinary superspace is obtained as a solution of the orthosymplectic section condition. A systematic study of curved superspace Bianchi identities is performed, and a relation to a double pure spinor superfield cohomology is established. A Ramond-Ramond superfield is constructed as an infinite-dimensional orthosymplectic spinor. Such objects in minimal orbits under the OSp supergroup (“pure spinors”) define super-sections.

  1. Double ambidexterity

    DEFF Research Database (Denmark)

    Kaulio, Matti; Thorén, Kent; Rohrbeck, René

    2017-01-01

    We leverage the business model innovation and ambidexterity literature to investigate a contradictory case, the Swedish-Finnish Telecom operator TeliaSonera. Despite being challenged by three major disruptions, the company not only still exists but also enjoys remarkably good financial performance....... Building on extant archival data and interviews, we carefully identify and map 26 organizational responses during 1992–2016. We find that the firm has overcome three critical phases by experimenting and pioneering with portfolios of business models and/or technological innovations. We describe...... this behaviour as double ambidexterity. We use an in-depth case study to conceptualize double ambidexterity and discuss its impact on the business's survival and enduring success....

  2. Diffusion bonding

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1976-01-01

    A method is described for joining beryllium to beryllium by diffusion bonding. At least one surface portion of at least two beryllium pieces is coated with nickel. A coated surface portion is positioned in a contiguous relationship with another surface portion and subjected to an environment having an atmosphere at a pressure lower than ambient pressure. A force is applied on the beryllium pieces for causing the contiguous surface portions to abut against each other. The contiguous surface portions are heated to a maximum temperature less than the melting temperature of the beryllium, and the applied force is decreased while increasing the temperature after attaining a temperature substantially above room temperature. A portion of the applied force is maintained at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions

  3. Multipassage diffuser

    International Nuclear Information System (INIS)

    Lalis, A.; Rouviere, R.; Simon, G.

    1976-01-01

    A multipassage diffuser having 2p passages comprises a leak-tight cylindrical enclosure closed by a top cover and a bottom end-wall, parallel porous tubes which are rigidly assembled in sectors between tube plates and through which the gas mixture flows, the tube sectors being disposed at uniform intervals on the periphery of the enclosure. The top tube plates are rigidly fixed to an annular header having the shape of a half-torus and adapted to communicate with the tubes of the corresponding sector. Each passage is constituted by a plurality of juxtaposed sectors in which the mixture circulates in the same direction, the header being divided into p portions limited by radial partition-walls and each constituting two adjacent passages. The diffuser is provided beneath the bottom end-wall with p-1 leak-tight chambers each adapted to open into two different portions of the header, and with two collector-chambers each fitted with a nozzle for introducing the gas mixture and discharging the fraction of the undiffused mixture. By means of a central orifice formed in the bottom end-wall the enclosure communicates with a shaft for discharging the diffused fraction of the gas mixture

  4. Quantum diffusion

    International Nuclear Information System (INIS)

    Habib, S.

    1994-01-01

    We consider a simple quantum system subjected to a classical random force. Under certain conditions it is shown that the noise-averaged Wigner function of the system follows an integro-differential stochastic Liouville equation. In the simple case of polynomial noise-couplings this equation reduces to a generalized Fokker-Planck form. With nonlinear noise injection new ''quantum diffusion'' terms rise that have no counterpart in the classical case. Two special examples that are not of a Fokker-Planck form are discussed: the first with a localized noise source and the other with a spatially modulated noise source

  5. Hereditary Diffuse Gastric Cancer

    Science.gov (United States)

    ... Hereditary Diffuse Gastric Cancer Request Permissions Hereditary Diffuse Gastric Cancer Approved by the Cancer.Net Editorial Board , 10/2017 What is hereditary diffuse gastric cancer? Hereditary diffuse gastric cancer (HDGC) is a rare ...

  6. Progress in MOSFET double-layer metalization

    Science.gov (United States)

    Gassaway, J. D.; Trotter, J. D.; Wade, T. E.

    1980-01-01

    Report describes one-year research effort in VLSL fabrication. Four activities are described: theoretical study of two-dimensional diffusion in SOS (silicon-on-sapphire); setup of sputtering system, furnaces, and photolithography equipment; experiments on double layer metal; and investigation of two-dimensional modeling of MOSFET's (metal-oxide-semiconductor field-effect transistors).

  7. Ion diffusion in compacted bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Lehikoinen, J. [VTT Chemical Technology, Espoo (Finland)

    1999-03-01

    In the study, a two-dimensional molecular-level diffusion model, based on a modified form of the Gouy-Chapman (GC) theory of the electrical double layers, for hydrated ionic species in compacted bentonite was developed. The modifications to the GC theory, which forms the very kernel of the diffusion model, stem from various non-conventional features: ionic hydration, dielectric saturation, finite ion-sizes and specific adsorption. The principal objectives of the study were met. With the aid of the consistent diffusion model, it is a relatively simple matter to explain the experimentally observed macroscopic exclusion for anions as well as the postulated, but greatly controversial, surface diffusion for cations. From purely theoretical grounds, it was possible to show that the apparent diffusivities of cations, anions and neutral molecules (i) do not exhibit order-or-magnitude differences, and (ii) are practically independent of the solution ionic strength used and, consequently, of the distribution coefficient, K{sub d}, unless they experience specific binding onto the substrate surface. It was also of interest to investigate the equilibrium anionic concentration distribution in the pore geometry of the GMM model as a function of the solution ionic strength, and to briefly speculate its consequences to diffusion. An explicit account of the filter-plate effect was taken by developing a computerised macroscopic diffusion model, which is based upon the very robust and efficient Laplace Transform Finite-Difference technique. Finally, the inherent limitations as well as the potential fields of applications of the models were addressed. (orig.) 45 refs.

  8. Ion diffusion in compacted bentonite

    International Nuclear Information System (INIS)

    Lehikoinen, J.

    1999-03-01

    In the study, a two-dimensional molecular-level diffusion model, based on a modified form of the Gouy-Chapman (GC) theory of the electrical double layers, for hydrated ionic species in compacted bentonite was developed. The modifications to the GC theory, which forms the very kernel of the diffusion model, stem from various non-conventional features: ionic hydration, dielectric saturation, finite ion-sizes and specific adsorption. The principal objectives of the study were met. With the aid of the consistent diffusion model, it is a relatively simple matter to explain the experimentally observed macroscopic exclusion for anions as well as the postulated, but greatly controversial, surface diffusion for cations. From purely theoretical grounds, it was possible to show that the apparent diffusivities of cations, anions and neutral molecules (i) do not exhibit order-or-magnitude differences, and (ii) are practically independent of the solution ionic strength used and, consequently, of the distribution coefficient, K d , unless they experience specific binding onto the substrate surface. It was also of interest to investigate the equilibrium anionic concentration distribution in the pore geometry of the GMM model as a function of the solution ionic strength, and to briefly speculate its consequences to diffusion. An explicit account of the filter-plate effect was taken by developing a computerised macroscopic diffusion model, which is based upon the very robust and efficient Laplace Transform Finite-Difference technique. Finally, the inherent limitations as well as the potential fields of applications of the models were addressed. (orig.)

  9. Double inflation

    International Nuclear Information System (INIS)

    Silk, J.; Turner, M.S.

    1986-04-01

    The Zel'dovich spectrum of adiabatic density perturbations is a generic prediction of inflation. There is increasing evidence that when the spectrum is normalized by observational data on small scales, there is not enough power on large scales to account for the observed large-scale structure in the Universe. Decoupling the spectrum on large and small scales could solve this problem. As a means of decoupling the large and small scales we propose double inflation (i.e., two episodes of inflation). In this scenario the spectrum on large scales is determined by the first episode of inflation and those on small scales by a second episode of inflation. We present three models for such a scenario. By nearly saturating the large angular-scale cosmic microwave anisotropy bound, we can easily account for the observed large-scale structure. We take the perturbations on small scales to be very large, deltarho/rho approx. = 0.1 to 0.01, which results in the production of primordial black holes (PBHs), early formation of structure, reionization of the Universe, and a rich array of astrophysical events. The Ω-problem is also addressed by our scenario. Allowing the density perturbations produced by the second episode of inflation to be large also lessens the fine-tuning required in the scalar potential and makes reheating much easier. We briefly speculate on the possibility that the second episode of inflation proceeds through the nucleation of bubbles, which today manifest themselves as empty bubbles whose surfaces are covered with galaxies. 37 refs., 1 fig

  10. Double Outlet Right Ventricle

    Science.gov (United States)

    ... Right Ventricle Menu Topics Topics FAQs Double Outlet Right Ventricle Double outlet right ventricle (DORV) is a rare form of congenital heart disease. En español Double outlet right ventricle (DORV) is a rare form of congenital ...

  11. Computational Analysis on Performance of Thermal Energy Storage (TES) Diffuser

    Science.gov (United States)

    Adib, M. A. H. M.; Adnan, F.; Ismail, A. R.; Kardigama, K.; Salaam, H. A.; Ahmad, Z.; Johari, N. H.; Anuar, Z.; Azmi, N. S. N.

    2012-09-01

    Application of thermal energy storage (TES) system reduces cost and energy consumption. The performance of the overall operation is affected by diffuser design. In this study, computational analysis is used to determine the thermocline thickness. Three dimensional simulations with different tank height-to-diameter ratio (HD), diffuser opening and the effect of difference number of diffuser holes are investigated. Medium HD tanks simulations with double ring octagonal diffuser show good thermocline behavior and clear distinction between warm and cold water. The result show, the best performance of thermocline thickness during 50% time charging occur in medium tank with height-to-diameter ratio of 4.0 and double ring octagonal diffuser with 48 holes (9mm opening ~ 60%) acceptable compared to diffuser with 6mm ~ 40% and 12mm ~ 80% opening. The conclusion is computational analysis method are very useful in the study on performance of thermal energy storage (TES).

  12. Computational Analysis on Performance of Thermal Energy Storage (TES) Diffuser

    International Nuclear Information System (INIS)

    Adib, M A H M; Ismail, A R; Kardigama, K; Salaam, H A; Ahmad, Z; Johari, N H; Anuar, Z; Azmi, N S N; Adnan, F

    2012-01-01

    Application of thermal energy storage (TES) system reduces cost and energy consumption. The performance of the overall operation is affected by diffuser design. In this study, computational analysis is used to determine the thermocline thickness. Three dimensional simulations with different tank height-to-diameter ratio (HD), diffuser opening and the effect of difference number of diffuser holes are investigated. Medium HD tanks simulations with double ring octagonal diffuser show good thermocline behavior and clear distinction between warm and cold water. The result show, the best performance of thermocline thickness during 50% time charging occur in medium tank with height-to-diameter ratio of 4.0 and double ring octagonal diffuser with 48 holes (9mm opening ∼ 60%) acceptable compared to diffuser with 6mm ∼ 40% and 12mm ∼ 80% opening. The conclusion is computational analysis method are very useful in the study on performance of thermal energy storage (TES).

  13. Diffusion archeology for diffusion progression history reconstruction.

    Science.gov (United States)

    Sefer, Emre; Kingsford, Carl

    2016-11-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring - perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial diffusion data. Here, we tackle the problem of reconstructing a diffusion history from one or more snapshots of the diffusion state. This ability can be invaluable to learn when certain computer nodes are infected or which people are the initial disease spreaders to control future diffusions. We formulate this problem over discrete-time SEIRS-type diffusion models in terms of maximum likelihood. We design methods that are based on submodularity and a novel prize-collecting dominating-set vertex cover (PCDSVC) relaxation that can identify likely diffusion steps with some provable performance guarantees. Our methods are the first to be able to reconstruct complete diffusion histories accurately in real and simulated situations. As a special case, they can also identify the initial spreaders better than the existing methods for that problem. Our results for both meme and contaminant diffusion show that the partial diffusion data problem can be overcome with proper modeling and methods, and that hidden temporal characteristics of diffusion can be predicted from limited data.

  14. Double hard scattering without double counting

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [VU Univ. Amsterdam (Netherlands). NIKHEF Theory Group; Schoenwald, Kay [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2017-02-15

    Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

  15. Double hard scattering without double counting

    International Nuclear Information System (INIS)

    Diehl, Markus; Gaunt, Jonathan R.

    2017-02-01

    Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

  16. Diffuse hemangioma of the colon

    International Nuclear Information System (INIS)

    Reis, J.; Caseiro-Alves, F.; Cruz, L.; Moreira, A.; Rebelo, O.

    1995-01-01

    We report two cases of diffuse hemangioma of the colon in adolescent patients. One patient had multiple phleboliths at the lower pelvis identified with plain radiographs of the abdomen. Several aspects were seen on double-contrast enema: luminal narrowing, colonic-wall thickening and submucosal colonic masses that changed in appearance with the degree of colonic distension. Angiography was inconclusive in one case. Use of CT and MR provided relevant information regarding the true extent of the disease, but MR was superior in demonstrating unequivocally the vascular nature of the lesions. (orig.)

  17. Excess Entropy and Diffusivity

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Excess Entropy and Diffusivity. Excess entropy scaling of diffusivity (Rosenfeld,1977). Analogous relationships also exist for viscosity and thermal conductivity.

  18. Diffusing diffusivity: Rotational diffusion in two and three dimensions

    Science.gov (United States)

    Jain, Rohit; Sebastian, K. L.

    2017-06-01

    We consider the problem of calculating the probability distribution function (pdf) of angular displacement for rotational diffusion in a crowded, rearranging medium. We use the diffusing diffusivity model and following our previous work on translational diffusion [R. Jain and K. L. Sebastian, J. Phys. Chem. B 120, 3988 (2016)], we show that the problem can be reduced to that of calculating the survival probability of a particle undergoing Brownian motion, in the presence of a sink. We use the approach to calculate the pdf for the rotational motion in two and three dimensions. We also propose new dimensionless, time dependent parameters, αr o t ,2 D and αr o t ,3 D, which can be used to analyze the experimental/simulation data to find the extent of deviation from the normal behavior, i.e., constant diffusivity, and obtain explicit analytical expressions for them, within our model.

  19. Diffusion in solids

    International Nuclear Information System (INIS)

    Tiwari, G.P.; Kale, G.B.; Patil, R.V.

    1999-01-01

    The article presents a brief survey of process of diffusion in solids. It is emphasised that the essence of diffusion is the mass transfer through the atomic jumps. To begin with formal equations for diffusion coefficient are presented. This is followed by discussions on mechanisms of diffusion. Except for solutes which form interstitial solid solution, diffusion in majority of cases is mediated through exchange of sites between an atom and its neighbouring vacancy. Various vacancy parameters such as activation volume, correlation factor, mass effect etc are discussed and their role in establishing the mode of diffusion is delineated. The contribution of dislocations and grain boundaries in diffusion process is brought out. The experimental determination of different types of diffusion coefficients are described. Finally, the pervasive nature of diffusion process in number of commercial processes is outlined to show the importance of diffusion studies in materials science and technology. (author)

  20. Diffusion archeology for diffusion progression history reconstruction

    OpenAIRE

    Sefer, Emre; Kingsford, Carl

    2015-01-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring — perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial d...

  1. Nonlinear Cross-Diffusion with Size Exclusion

    KAUST Repository

    Burger, Martin

    2010-01-01

    The aim of this paper is to investigate the mathematical properties of a continuum model for diffusion of multiple species incorporating size exclusion effects. The system for two species leads to nonlinear cross-diffusion terms with double degeneracy, which creates significant novel challenges in the analysis of the system. We prove global existence of weak solutions and well-posedness of strong solutions close to equilibrium. We further study some asymptotics of the model, and in particular we characterize the large-time behavior of solutions. 2010 © Society for Industrial and Applied Mathematics.

  2. Tiny Molybdenites Tell Diffusion Tales

    Science.gov (United States)

    Stein, H. J.; Hannah, J. L.

    2014-12-01

    Diffusion invokes micron-scale exchange during crystal growth and dissolution in magma chambers on short time-scales. Fundamental to interpreting such data are assumptions on magma-fluid dynamics at all scales. Nevertheless, elemental diffusion profiles are used to estimate time scales for magma storage, eruption, and recharge. An underutilized timepiece to evaluate diffusion and 3D mobility of magmatic fluids is high-precision Re-Os dating of molybdenite. With spatially unique molybdenite samples from a young ore system (e.g., 1 Ma) and a double Os spike, analytical errors of 1-3 ka unambiguously separate events in time. Re-Os ages show that hydrous shallow magma chambers locally recharge and expel Cu-Mo-Au-silica as superimposed stockwork vein networks at time scales less than a few thousand years [1]. Re-Os ages provide diffusion rates controlled by a dynamic crystal mush, accumulation and expulsion of metalliferous fluid, and magma reorganization after explosive crystallization events. Importantly, this approach has broad application far from ore deposits. Here, we use Re-Os dating of molybdenite to assess time scales for generating and diffusing metals through the deep crust. To maximize opportunity for chemical diffusion, we use a continental-scale Sveconorwegian mylonite zone for the study area. A geologically constrained suite of molybdenite samples was acquired from quarry exposures. Molybdenite, previously unreported, is extremely scarce. Tiny but telling molybdenites include samples from like occurrences to assure geologic accuracy in Re-Os ages. Ages range from mid-Mesoproterozoic to mid-Neoproterozoic, and correspond to early metamorphic dehydration of a regionally widespread biotite-rich gneiss, localized melting of gneiss to form cm-m-scale K-feldspar ± quartz pods, development of vapor-rich, vuggy mm stringers that serve as volatile collection surfaces in felsic leucosomes, and low-angle (relative to foliation) cross-cutting cm-scale quartz veins

  3. International double taxation

    OpenAIRE

    Körbl, Hugo

    2012-01-01

    1 Summary This thesis deals with the issue of international double taxation of income and capital and methods for its solution. International double taxation is an issue which states began to deal with in the late 19th century. This interest intensified after the First World War when also the League of Nations (predecessor of the United Nations) began to deal with international double taxation. Most attention the phenomenon of double taxation of income and capital with an international elemen...

  4. Spin-diffusions and diffusive molecular dynamics

    Science.gov (United States)

    Farmer, Brittan; Luskin, Mitchell; Plecháč, Petr; Simpson, Gideon

    2017-12-01

    Metastable configurations in condensed matter typically fluctuate about local energy minima at the femtosecond time scale before transitioning between local minima after nanoseconds or microseconds. This vast scale separation limits the applicability of classical molecular dynamics (MD) methods and has spurned the development of a host of approximate algorithms. One recently proposed method is diffusive MD which aims at integrating a system of ordinary differential equations describing the likelihood of occupancy by one of two species, in the case of a binary alloy, while quasistatically evolving the locations of the atoms. While diffusive MD has shown itself to be efficient and provide agreement with observations, it is fundamentally a model, with unclear connections to classical MD. In this work, we formulate a spin-diffusion stochastic process and show how it can be connected to diffusive MD. The spin-diffusion model couples a classical overdamped Langevin equation to a kinetic Monte Carlo model for exchange amongst the species of a binary alloy. Under suitable assumptions and approximations, spin-diffusion can be shown to lead to diffusive MD type models. The key assumptions and approximations include a well-defined time scale separation, a choice of spin-exchange rates, a low temperature approximation, and a mean field type approximation. We derive several models from different assumptions and show their relationship to diffusive MD. Differences and similarities amongst the models are explored in a simple test problem.

  5. Molecular dynamics and diffusion a compilation

    CERN Document Server

    Fisher, David

    2013-01-01

    The molecular dynamics technique was developed in the 1960s as the outgrowth of attempts to model complicated systems by using either a) direct physical simulation or (following the great success of Monte Carlo methods) by b) using computer techniques. Computer simulation soon won out over clumsy physical simulation, and the ever-increasing speed and sophistication of computers has naturally made molecular dynamics simulation into a more and more successful technique. One of its most popular applications is the study of diffusion, and some experts now even claim that molecular dynamics simulation is, in the case of situations involving well-characterised elements and structures, more accurate than experimental measurement. The present double volume includes a compilation (over 600 items) of predicted solid-state diffusion data, for all of the major materials groups, dating back nearly four decades. The double volume also includes some original papers: "Determination of the Activation Energy for Formation and ...

  6. Diffusion test of probe nuclei {sup 111}In({sup 111}Cd) in the compounds: LaBaMn{sub 2}O{sub 6} 'Double Perovskites' for measurements using PAC spectroscopy; Teste de difusão do núcleo de prova {sup 111}In({sup 111}Cd) nos compostos: LaBaMn{sub 2}0{sub 6} e LaBaCo{sub 2}0{sub 6} 'double perovskites' para a realização de medições utilizando a espectroscopia PAC

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Natália M.; Bosch-Santos, Brianna; Sciarreta, Beatriz A.; Carbonari, Artur W., E-mail: nat_mn1@hotmail.com [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Sandalo, Danilo S. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil)

    2017-07-01

    Double perovskites of type LaBaMn{sub 2}O{sub 6} and LaBaCo{sub 2}O{sub 6} were made using two processes, sol-gel synthesis and solid state reaction, in order to identify which of the methods is best for insertion and diffusion of the {sup 111}In test core ({sup 111}Cd) used for perturbed gamma-gamma angular correlation (PAC) spectroscopy measurements. The test core diffusion were performed with thermal treatments in air and at temperatures of 550 ° C, 650 ° C and 750 ° C. By the analysis of the results, the synthesis by Sol-Gel is more efficient for the insertion of the radioactive material, together with the heat treatment at 650 ° C. The advantage of this method is that the radioactive material can be added to the compounds of the synthesis process, even in the solid state reaction method the radioactive material can only be inserted after the ready compound.

  7. Blocking Radial Diffusion in a Double-Waved Hamiltonian Model

    International Nuclear Information System (INIS)

    Martins, Caroline G L; De Carvalho, R Egydio; Marcus, F A; Caldas, I L

    2011-01-01

    A non-twist Hamiltonian system perturbed by two waves with particular wave numbers can present Robust Tori, barriers created by the vanishing of the perturbing Hamiltonian at some defined positions. When Robust Tori exist, any trajectory in phase space passing close to them is blocked by emergent invariant curves that prevent the chaotic transport. We analyze the breaking up of the RT as well the transport dependence on the wave numbers and on the wave amplitudes. Moreover, we report the chaotic web formation in the phase space and how this pattern influences the transport.

  8. Double-diffusive convection of compressible rotating Walters' (B ...

    African Journals Online (AJOL)

    user

    Mathematical Formulation of the Problem and Perturbation Equations ...... Rayleigh number for the onset of instability via a state of pure oscillations, it suffices to find conditions for which ..... Cambridge University Press, Cambridge, UK.

  9. Double-diffusive convection of compressible rotating Walters' (B ...

    African Journals Online (AJOL)

    user

    A great number of applications of such a flow in geophysics are found in a ... We have considered an infinite, horizontal, compressible electrically conducting Walters' (Model B′) fluid layer of .... Linearized stability theory and normal mode analysis .... boundaries the boundary conditions are (see Chandrasekhar, 1981). 2.

  10. Diapycnal Transport and Pattern Formation in Double-Diffusive Convection

    Science.gov (United States)

    2015-12-01

    carried out only over the geostrophic interior. By virtue of (2.55), we further simplify (2.58) to * int 0dlw M = ∇∫ . (2.59) The final step is the...The processes discussed in this study could be affected by the nonlinearities of the equation of state (e.g., McDougall 1987). Thus, the quantitative...nonlinear equation of state given in McDougall et al. (2003). Model geometry consisted of a volume comprising 320 grid points in the zonal and 256

  11. Double layers in space

    International Nuclear Information System (INIS)

    Carlqvist, P.

    1982-07-01

    For more than a decade it has been realised that electrostatic double layers are likely to occur in space. We briefly discuss the theoretical background of such double layers. Most of the paper is devoted to an account of the observational evidence for double layers in the ionosphere and magnetosphere of the Earth. Several different experiments are reviewed including rocket and satellite measurements and ground based observations. It is concluded that the observational evidence for double layers in space is very strong. The experimental results indicate that double layers with widely different properties may exist in space. (Author)

  12. Double layers in space

    International Nuclear Information System (INIS)

    Carlqvist, P.

    1982-01-01

    For more than a decade it has been realised that electrostatic double layers are likely to occur in space. The author briefly discusses the theoretical background of such double layers. Most of the paper is devoted to an account of the observational evidence for double layers in the ionosphere and magnetosphere of the Earth. Several different experiments are reviewed including rocket and satellite measurements and ground based observations. It is concluded that the observational evidence for double layers in space is very strong. The experimental results indicate that double layers with widely different properties may exist in space. (Auth.)

  13. Double-double effect and coordination number

    International Nuclear Information System (INIS)

    Mioduski, T.

    1992-01-01

    The original method of interpretation together with its theoretical foundations is developed, making it possible to use location and direction of the double-double (tetrad) effect within the Ln and An series to determine the coordination number (CN) complexes of the f-block elements. The method is applied for potentiometric and radiometric equilibrium studies. It has been pointed and that the decisive factor for the direction of the double-double effect in the case of the Gibbs energy variations is a difference in the CN of the f-element ion between the reaction product complex and that for the reaction substrate the ''regular'' effect for a given tetrad is accompanied by decrease in the CN while the ''reverse'' effect by increase in the CN. (author). 122 refs, 5 tabs, 8 figs

  14. Diffusion in reactor materials

    International Nuclear Information System (INIS)

    Fedorov, G.B.; Smirnov, E.A.

    1984-01-01

    The monograph contains a brief description of the principles underlying the theory of diffusion, as well as modern methods of studying diffusion. Data on self-diffusion and diffusion of impurities in a nuclear fuel and fissionable materials (uranium, plutonium, thorium, zirconium, titanium, hafnium, niobium, molybdenum, tungsten, beryllium, etc.) is presented. Anomalous diffusion, diffusion of components, and interdiffusion in binary and ternary alloys were examined. The monograph presents the most recent reference material on diffusion. It is intended for a wide range of researchers working in the field of diffusion in metals and alloys and attempting to discover new materials for application in nuclear engineering. It will also be useful for teachers, research scholars and students of physical metallurgy

  15. Diffusion in flowing gas

    International Nuclear Information System (INIS)

    Reus, K.W.

    1979-01-01

    This thesis is concerned with the back-diffusion method of calculating the mutual diffusion coefficient of two gases. The applicability of this method for measuring diffusion coefficients at temperatures up to 1300 K is considered. A further aim of the work was to make a contribution to the description of the interatomic potential energy of noble gases at higher energies as a function of the internuclear distance. This was achieved with the measured diffusion coefficients, especially with those for high temperatures. (Auth.)

  16. Diffusion Under Geometrical Constraint

    OpenAIRE

    Ogawa, Naohisa

    2014-01-01

    Here we discus the diffusion of particles in a curved tube. This kind of transport phenomenon is observed in biological cells and porous media. To solve such a problem, we discuss the three dimensional diffusion equation with a confining wall forming a thinner tube. We find that the curvature appears in a effective diffusion coefficient for such a quasi-one-dimensional system. As an application to higher dimensional case, we discuss the diffusion in a curved surface with ...

  17. Diffuse ceiling ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen

    Diffuse ceiling ventilation is an innovative ventilation concept where the suspended ceiling serves as air diffuser to supply fresh air into the room. Compared with conventional ventilation systems, diffuse ceiling ventilation can significantly reduce or even eliminate draught risk due to the low...

  18. Thermal diffusion (1963); Diffusion thermique (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Lemarechal, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    This report brings together the essential principles of thermal diffusion in the liquid and gaseous phases. The macroscopic and molecular aspects of the thermal diffusion constant are reviewed, as well as the various measurement method; the most important developments however concern the operation of the CLUSIUS and DICKEL thermo-gravitational column and its applications. (author) [French] Ce rapport rassemble les principes essentiels de la diffusion thermique en phase liquide et en phase gazeuse. Les aspects macroscopique et moleculaire de la constante de diffusion thermique sont passes en revue ainsi que ses differentes methodes de mesure; mais les developpements les plus importants concernent le fonctionnement de ls colonne thermogravitationnelle de CLUSIUS et DICKEL et ses applications. (auteur)

  19. Fractional diffusion equations and anomalous diffusion

    CERN Document Server

    Evangelista, Luiz Roberto

    2018-01-01

    Anomalous diffusion has been detected in a wide variety of scenarios, from fractal media, systems with memory, transport processes in porous media, to fluctuations of financial markets, tumour growth, and complex fluids. Providing a contemporary treatment of this process, this book examines the recent literature on anomalous diffusion and covers a rich class of problems in which surface effects are important, offering detailed mathematical tools of usual and fractional calculus for a wide audience of scientists and graduate students in physics, mathematics, chemistry and engineering. Including the basic mathematical tools needed to understand the rules for operating with the fractional derivatives and fractional differential equations, this self-contained text presents the possibility of using fractional diffusion equations with anomalous diffusion phenomena to propose powerful mathematical models for a large variety of fundamental and practical problems in a fast-growing field of research.

  20. Terahertz double-exponential model for adsorption of volatile organic compounds in active carbon

    International Nuclear Information System (INIS)

    Zhu, Jing; Zhan, Honglei; Miao, Xinyang; Zhao, Kun; Zhou, Qiong

    2017-01-01

    In terms of the evaluation of the diffusion-controlled adsorption and diffused rate, a mathematical model was built on the basis of the double-exponential kinetics model and terahertz amplitude in this letter. The double-exponential-THz model described the two-step mechanism controlled by diffusion. A rapid step involves external and internal diffusion, followed by a slow step controlled by intraparticle diffusion. The concentration gradient of the molecules promoted the organic molecules rapidly diffusing to the external surface of adsorbent. The solute molecules then transferred across the liquid film. Intraparticle diffusion began and was determined by the molecular sizes, as well as affinities between organics and activated carbon. (paper)

  1. Diffusion in molybdenum disilicide

    International Nuclear Information System (INIS)

    Salamon, M.; Mehrer, H.

    2005-01-01

    The diffusion behaviour of the high-temperature material molybdenum disilicide (MoSi 2 ) was completely unknown until recently. In this paper we present studies of Mo self-diffusion and compare our present results with our already published studies of Si and Ge diffusion in MoSi 2 . Self-diffusion of molybdenum in monocrystalline MoSi 2 was studied by the radiotracer technique using the radioisotope 99 Mo. Deposition of the radiotracer and serial sectioning after the diffusion anneals to determine the concentration-depth profiles was performed using a sputtering device. Diffusion of Mo is a very slow process. In the entire temperature region investigated (1437 to 2173 K), the 99 Mo diffusivities in both principal directions of the tetragonal MoSi 2 crystals obey Arrhenius laws, where the diffusion perpendicular to the tetragonal axis is faster by two to three orders of magnitude than parallel to it. The activation enthalpies for diffusion perpendicular and parallel to the tetragonal axis are Q perpendicular to = 468 kJ mol -1 (4.85 eV) and Q parallel = 586 kJ mol -1 (6.07 eV), respectively. Diffusion of Si and its homologous element Ge is fast and is mediated by thermal vacancies of the Si sublattice of MoSi 2 . The diffusion of Mo is by several orders of magnitude slower than the diffusion of Si and Ge. This large difference suggests that Si and Mo diffusion are decoupled and that the diffusion of Mo likely takes place via vacancies on the Mo sublattice. (orig.)

  2. Observing Double Stars

    Science.gov (United States)

    Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

    2012-05-01

    Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

  3. Formation of double layers

    International Nuclear Information System (INIS)

    Leung, P.; Wong, A.Y.; Quon, B.H.

    1981-01-01

    Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

  4. How I treat double-hit lymphoma.

    Science.gov (United States)

    Friedberg, Jonathan W

    2017-08-03

    The 2016 revision of the World Health Organization (WHO) classification for lymphoma has included a new category of lymphoma, separate from diffuse large B-cell lymphoma, termed high-grade B-cell lymphoma with translocations involving myc and bcl-2 or bcl-6 . These lymphomas, which occur in hit lymphomas (or triple-hit lymphomas if all 3 rearrangements are present). It is important to differentiate these lymphomas from the larger group of double-expressor lymphomas, which have increased expression of MYC and BCL-2 and/or BCL-6 by immunohistochemistry, by using variable cutoff percentages to define positivity. Patients with double-hit lymphomas have a poor prognosis when treated with standard chemoimmunotherapy and have increased risk of central nervous system involvement and progression. Double-hit lymphomas may arise as a consequence of the transformation of the underlying indolent lymphoma. There are no published prospective trials in double-hit lymphoma, however retrospective studies strongly suggest that aggressive induction regimens may confer a superior outcome. In this article, I review my approach to the evaluation and treatment of double-hit lymphoma, with an eye toward future clinical trials incorporating rational targeted agents into the therapeutic armamentarium. © 2017 by The American Society of Hematology.

  5. Metric diffusion along foliations

    CERN Document Server

    Walczak, Szymon M

    2017-01-01

    Up-to-date research in metric diffusion along compact foliations is presented in this book. Beginning with fundamentals from the optimal transportation theory and the theory of foliations; this book moves on to cover Wasserstein distance, Kantorovich Duality Theorem, and the metrization of the weak topology by the Wasserstein distance. Metric diffusion is defined, the topology of the metric space is studied and the limits of diffused metrics along compact foliations are discussed. Essentials on foliations, holonomy, heat diffusion, and compact foliations are detailed and vital technical lemmas are proved to aide understanding. Graduate students and researchers in geometry, topology and dynamics of foliations and laminations will find this supplement useful as it presents facts about the metric diffusion along non-compact foliation and provides a full description of the limit for metrics diffused along foliation with at least one compact leaf on the two dimensions.

  6. Double deflation and aggregation

    NARCIS (Netherlands)

    Dietzenbacher, Erik; Hoen, A.R.

    Published input-output tables in constant prices are relatively scarce. Therefore, input-output tables often have to be deflated by the practitioners themselves. The method of double deflation is used predominantly for this purpose. The present paper shows that the double-deflation method is subject

  7. Correlated diffusion imaging

    International Nuclear Information System (INIS)

    Wong, Alexander; Glaister, Jeffrey; Cameron, Andrew; Haider, Masoom

    2013-01-01

    Prostate cancer is one of the leading causes of cancer death in the male population. Fortunately, the prognosis is excellent if detected at an early stage. Hence, the detection and localization of prostate cancer is crucial for diagnosis, as well as treatment via targeted focal therapy. New imaging techniques can potentially be invaluable tools for improving prostate cancer detection and localization. In this study, we introduce a new form of diffusion magnetic resonance imaging called correlated diffusion imaging, where the tissue being imaged is characterized by the joint correlation of diffusion signal attenuation across multiple gradient pulse strengths and timings. By taking into account signal attenuation at different water diffusion motion sensitivities, correlated diffusion imaging can provide improved delineation between cancerous tissue and healthy tissue when compared to existing diffusion imaging modalities. Quantitative evaluation using receiver operating characteristic (ROC) curve analysis, tissue class separability analysis, and visual assessment by an expert radiologist were performed to study correlated diffusion imaging for the task of prostate cancer diagnosis. These results are compared with that obtained using T2-weighted imaging and standard diffusion imaging (via the apparent diffusion coefficient (ADC)). Experimental results suggest that correlated diffusion imaging provide improved delineation between healthy and cancerous tissue and may have potential as a diagnostic tool for cancer detection and localization in the prostate gland. A new form of diffusion magnetic resonance imaging called correlated diffusion imaging (CDI) was developed for the purpose of aiding radiologists in cancer detection and localization in the prostate gland. Preliminary results show CDI shows considerable promise as a diagnostic aid for radiologists in the detection and localization of prostate cancer

  8. Gaseous diffusion system

    International Nuclear Information System (INIS)

    Garrett, G.A.; Shacter, J.

    1978-01-01

    A gaseous diffusion system is described comprising a plurality of diffusers connected in cascade to form a series of stages, each of the diffusers having a porous partition dividing it into a high pressure chamber and a low pressure chamber, and means for combining a portion of the enriched gas from a succeeding stage with a portion of the enriched gas from the low pressure chamber of each stage and feeding it into one extremity of the high pressure chamber thereof

  9. Diffusion of I{sup -}, Cs{sup +}, and Sr{sup 2+} in compacted bentonite - Anion exclusion and surface diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Eriksen, T.E.; Jansson, Mats [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Nuclear Chemistry

    1996-11-01

    The diffusion of I, Cs and Sr ions in bentonite compacted to a dry density of 1.8 gr/cm{sup 3} and saturated with two groundwaters of different ionic strength have been studied experimentally using the through diffusion technique. The I{sup -} diffusivity and diffusion porosity were found to be concentration independent in the concentration range exp(-8) to exp(-2) mol/dm{sup 3}. The diffusion porosity, being only a fraction of the water porosity for normal groundwaters, is strongly ionic strength dependent due to anion exclusion. The dependence of the diffusion of Cs{sup +} and Sr{sup 2+} on the sorption intensity is accommodated by a model encompassing diffusion of the sorbed cations within the electrical double layer next to the mineral surface in addition to diffusion in the pore water. 18 refs, 12 figs.

  10. Inpainting using airy diffusion

    Science.gov (United States)

    Lorduy Hernandez, Sara

    2015-09-01

    One inpainting procedure based on Airy diffusion is proposed, implemented via Maple and applied to some digital images. Airy diffusion is a partial differential equation with spatial derivatives of third order in contrast with the usual diffusion with spatial derivatives of second order. Airy diffusion generates the Airy semigroup in terms of the Airy functions which can be rewritten in terms of Bessel functions. The Airy diffusion can be used to smooth an image with the corresponding noise elimination via convolution. Also the Airy diffusion can be used to erase objects from an image. We build an algorithm using the Maple package ImageTools and such algorithm is tested using some images. Our results using Airy diffusion are compared with the similar results using standard diffusion. We observe that Airy diffusion generates powerful filters for image processing which could be incorporated in the usual packages for image processing such as ImageJ and Photoshop. Also is interesting to consider the possibility to incorporate the Airy filters as applications for smartphones and smart-glasses.

  11. Diffusion in compacted betonite

    International Nuclear Information System (INIS)

    Muurinen, A.; Rantanen, J.

    1985-01-01

    The objective of this report is to collect the literature bearing on the diffusion in compacted betonite, which has been suggested as possible buffer material for the disposal of spent fuel. Diffusion in a porous, water-saturated material is usually described as diffusion in the pore-water where sorption on the solid matter can delay the migration in the instationary state. There are also models which take into consideration that the sorbed molecules can also move while being sorbed. Diffusion experiments in compacted bentonite have been reported by many authors. Gases, anions, cations and actinides have been used as diffusing molecules. The report collects the results and the information on the measurement methods. On the basis of the results can be concluded that different particles possibly follow different diffusion mechanisms. The parameters which affect the diffusion seem to be for example the size, the electric charge and the sorption properties of the diffusing molecule. The report also suggest the parameters to be used in the diffusion calculation of the safety analyses of spent fuel disposal. (author)

  12. On the solution of reaction-diffusion equations with double diffusivity

    Directory of Open Access Journals (Sweden)

    B. D. Aggarwala

    1987-01-01

    Full Text Available In this paper, solution of a pair of Coupled Partial Differential equations is derived. These equations arise in the solution of problems of flow of homogeneous liquids in fissured rocks and heat conduction involving two temperatures. These equations have been considered by Hill and Aifantis, but the technique we use appears to be simpler and more direct, and some new results are derived. Also, discussion about the propagation of initial discontinuities is given and illustrated with graphs of some special cases.

  13. Double layer effects in the electroreduction of transition metal ions

    Czech Academy of Sciences Publication Activity Database

    Fawcett, W. R.; Hromadová, Magdaléna

    2008-01-01

    Roč. 12, č. 4 (2008), s. 347-351 ISSN 1432-8488 R&D Projects: GA AV ČR KJB400400603; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : sphere electrode reactions * crystal gold electrodes * diffuse double - layer Subject RIV: CG - Electrochemistry Impact factor: 1.597, year: 2008

  14. Effect of turbulent flow on the double electric layer

    International Nuclear Information System (INIS)

    Rutten, F. van.

    1978-01-01

    The existence of the double electric layer could explain the local deposition of corrosion products in water cooled reactors. It is shown that turbulent flow tends to drive the ions away from the wall, disturbs the diffuse layer and enables the electric field to extend further into the liquid phase. This electric field attracts the particles to the walls by electrophoresis [fr

  15. The electric double layer put to work : thermal physics at electrochemical interfaces

    NARCIS (Netherlands)

    Janssen, M.A.

    2017-01-01

    Where charged electrode surfaces meet fluids that contain mobile ions, so-called electric double layers (EDLs) form to screen the electric surface charge by a diffuse cloud of counterionic charge in the fluid phase. This double layer has been studied for over a century and is of paramount importance

  16. Discrimination of thermal diffusivity

    NARCIS (Netherlands)

    Bergmann Tiest, W.M.; Kappers, A.M.L.

    2009-01-01

    Materials such as wood or metal which are at equal temperatures are perceived to be of different ‘coldness’ due to differences in thermal properties, such as the thermal diffusivity. The thermal diffusivity of a material is a parameter that controls the rate with which heat is extracted from the

  17. Diffusion Based Photon Mapping

    DEFF Research Database (Denmark)

    Schjøth, Lars; Fogh Olsen, Ole; Sporring, Jon

    2007-01-01

    . To address this problem we introduce a novel photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way we preserve the important illumination features......, while eliminating noise. We call our method diffusion based photon mapping....

  18. Diffusion Based Photon Mapping

    DEFF Research Database (Denmark)

    Schjøth, Lars; Olsen, Ole Fogh; Sporring, Jon

    2006-01-01

    . To address this problem we introduce a novel photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way we preserve the important illumination features......, while eliminating noise. We call our method diffusion based photon mapping....

  19. Adaptation and Cultural Diffusion.

    Science.gov (United States)

    Ormrod, Richard K.

    1992-01-01

    Explores the role of adaptation in cultural diffusion. Explains that adaptation theory recognizes the lack of independence between innovations and their environmental settings. Discusses testing and selection, modification, motivation, and cognition. Suggests that adaptation effects are pervasive in cultural diffusion but require a broader, more…

  20. Modelling of Innovation Diffusion

    Directory of Open Access Journals (Sweden)

    Arkadiusz Kijek

    2010-01-01

    Full Text Available Since the publication of the Bass model in 1969, research on the modelling of the diffusion of innovation resulted in a vast body of scientific literature consisting of articles, books, and studies of real-world applications of this model. The main objective of the diffusion model is to describe a pattern of spread of innovation among potential adopters in terms of a mathematical function of time. This paper assesses the state-of-the-art in mathematical models of innovation diffusion and procedures for estimating their parameters. Moreover, theoretical issues related to the models presented are supplemented with empirical research. The purpose of the research is to explore the extent to which the diffusion of broadband Internet users in 29 OECD countries can be adequately described by three diffusion models, i.e. the Bass model, logistic model and dynamic model. The results of this research are ambiguous and do not indicate which model best describes the diffusion pattern of broadband Internet users but in terms of the results presented, in most cases the dynamic model is inappropriate for describing the diffusion pattern. Issues related to the further development of innovation diffusion models are discussed and some recommendations are given. (original abstract

  1. Thermal diffusion (1963)

    International Nuclear Information System (INIS)

    Lemarechal, A.

    1963-01-01

    This report brings together the essential principles of thermal diffusion in the liquid and gaseous phases. The macroscopic and molecular aspects of the thermal diffusion constant are reviewed, as well as the various measurement method; the most important developments however concern the operation of the CLUSIUS and DICKEL thermo-gravitational column and its applications. (author) [fr

  2. Diffusion of Botulinum Toxins

    Directory of Open Access Journals (Sweden)

    Matthew A. Brodsky

    2012-08-01

    Full Text Available Background: It is generally agreed that diffusion of botulinum toxin occurs, but the extent of the spread and its clinical importance are disputed. Many factors have been suggested to play a role but which have the most clinical relevance is a subject of much discussion.Methods: This review discusses the variables affecting diffusion, including protein composition and molecular size as well as injection factors (e.g., volume, dose, injection method. It also discusses data on diffusion from comparative studies in animal models and human clinical trials that illustrate differences between the available botulinum toxin products (onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and rimabotulinumtoxinB.Results: Neither molecular weight nor the presence of complexing proteins appears to affect diffusion; however, injection volume, concentration, and dose all play roles and are modifiable. Both animal and human studies show that botulinum toxin products are not interchangeable, and that some products are associated with greater diffusion and higher rates of diffusion-related adverse events than others.Discussion: Each of the botulinum toxins is a unique pharmacologic entity. A working knowledge of the different serotypes is essential to avoid unwanted diffusion-related adverse events. In addition, clinicians should be aware that the factors influencing diffusion may range from properties intrinsic to the drug to accurate muscle selection as well as dilution, volume, and dose injected.

  3. Congenital maxillary double lip

    Directory of Open Access Journals (Sweden)

    Dinesh Singh Chauhan

    2012-01-01

    Full Text Available Double lip, also referred to as "macrocheilia," is a rare anomaly which affects the upper lip more commonly than the lower lip. It consists of a fold of excess or redundant hypertrophic tissue on the mucosal side of the lip. The congenital double lip is believed to be present at birth and becomes more prominent after eruption of teeth. It affects esthetics and also interferes with speech and mastication. Simple surgical excision produces good functional and cosmetic results. We report a case of a non-syndromic congenital maxillary double lip in a 21-year-old male patient.

  4. Diffusion in Coulomb crystals.

    Science.gov (United States)

    Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

    2011-07-01

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

  5. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  6. Degenerate nonlinear diffusion equations

    CERN Document Server

    Favini, Angelo

    2012-01-01

    The aim of these notes is to include in a uniform presentation style several topics related to the theory of degenerate nonlinear diffusion equations, treated in the mathematical framework of evolution equations with multivalued m-accretive operators in Hilbert spaces. The problems concern nonlinear parabolic equations involving two cases of degeneracy. More precisely, one case is due to the vanishing of the time derivative coefficient and the other is provided by the vanishing of the diffusion coefficient on subsets of positive measure of the domain. From the mathematical point of view the results presented in these notes can be considered as general results in the theory of degenerate nonlinear diffusion equations. However, this work does not seek to present an exhaustive study of degenerate diffusion equations, but rather to emphasize some rigorous and efficient techniques for approaching various problems involving degenerate nonlinear diffusion equations, such as well-posedness, periodic solutions, asympt...

  7. Oxygen diffusion in monazite

    Science.gov (United States)

    Cherniak, D. J.; Zhang, X. Y.; Nakamura, M.; Watson, E. B.

    2004-09-01

    We report measurements of oxygen diffusion in natural monazites under both dry, 1-atm conditions and hydrothermal conditions. For dry experiments, 18O-enriched CePO4 powder and monazite crystals were sealed in Ag-Pd capsules with a solid buffer (to buffer at NNO) and annealed in 1-atm furnaces. Hydrothermal runs were conducted in cold-seal pressure vessels, where monazite grains were encapsulated with 18O-enriched water. Following the diffusion anneals, oxygen concentration profiles were measured with Nuclear Reaction Analysis (NRA) using the reaction 18O(p,α)15N. Over the temperature range 850-1100 °C, the Arrhenius relation determined for dry diffusion experiments on monazite is given by: Under wet conditions at 100 MPa water pressure, over the temperature range 700-880 °C, oxygen diffusion can be described by the Arrhenius relationship: Oxygen diffusion under hydrothermal conditions has a significantly lower activation energy for diffusion than under dry conditions, as has been found the case for many other minerals, both silicate and nonsilicate. Given these differences in activation energies, the differences between dry and wet diffusion rates increase with lower temperatures; for example, at 600 °C, dry diffusion will be more than 4 orders of magnitude slower than diffusion under hydrothermal conditions. These disparate diffusivities will result in pronounced differences in the degree of retentivity of oxygen isotope signatures. For instance, under dry conditions (presumably rare in the crust) and high lower-crustal temperatures (∼800 °C), monazite cores of 70-μm radii will preserve O isotope ratios for about 500,000 years; by comparison, they would be retained at this temperature under wet conditions for about 15,000 years.

  8. Pion double charge exchange

    International Nuclear Information System (INIS)

    Cooper, M.D.

    1978-01-01

    The pion double charge exchange data on the oxygen isotopes is reviewed and new data on 9 Be, 12 C, 24 Mg, and 28 Si are presented. Where theoretical calculations exist, they are compared to the data. 9 references

  9. Neutrinoless double beta decay

    Indian Academy of Sciences (India)

    2012-10-06

    Oct 6, 2012 ... Anyhow, the 'multi-isotope' ansatz is needed to compensate for matrix element ... The neccessary half-life requirement to touch this ... site energy depositions (like double beta decay) and multiple site interactions (most of.

  10. Project Half Double

    DEFF Research Database (Denmark)

    Svejvig, Per; Ehlers, Michael; Adland, Karoline Thorp

    activities carried out within the framework of the projects. The formal part of Project Half Double was initiated in June 2015. We started out by developing, refining and testing the Half Double methodology on seven pilot projects in the first phase of the project, which will end June 2016. The current......Project Half Double has a clear mission to succeed in finding a project methodology that can increase the success rate of our projects while increasing the speed at which we generate new ideas and develop new products and services. Chaos and complexity should be seen as a basic condition...... and as an opportunity rather than a threat and a risk. We are convinced that by doing so, we can strengthen Denmark’s competitiveness and play an important role in the battle for jobs and future welfare. The overall goal is to deliver “projects in half the time with double the impact”, where projects in half the time...

  11. Project Half Double

    DEFF Research Database (Denmark)

    Svejvig, Per; Gerstrøm, Anna; Frederiksen, Signe Hedeboe

    The Half Double mission: Project Half Double has a clear mission. We want to succeed in finding a project methodology that can increase the success rate of our projects while increasing the development speed of new products and services. We are convinced that by doing so we can strengthen...... the competitiveness of Denmark and play an important role in the battle for jobs and future welfare. The overall goal is to deliver “Projects in half the time with double the impact” where projects in half the time should be understood as half the time to impact (benefit realization, effect is achieved......) and not as half the time for project execution. The Half Double project journey: It all began in May 2013 when we asked ourselves: How do we create a new and radical project paradigm that can create successful projects? Today we are a movement of hundreds of passionate project people, and it grows larger...

  12. Double beta decay: experiments

    International Nuclear Information System (INIS)

    Fiorini, Ettore

    2006-01-01

    The results obtained so far and those of the running experiments on neutrinoless double beta decay are reviewed. The plans for second generation experiments, the techniques to be adopted and the expected sensitivities are compared and discussed

  13. A double layer review

    International Nuclear Information System (INIS)

    Block, L.P.

    1977-06-01

    A review of the main results on electrostatic double layers (sometimes called space charge layers or sheaths) obtained from theory, and laboratory and space experiments up to the spring of 1977 is given. By means of barium jets and satellite probes, double layers have now been found at the altitudes, earlier predicted theoretically. The general potential distribution above the auroral zone, suggested by inverted V-events and electric field reversals, is corroborated. (author)

  14. Diffuse interstellar clouds

    International Nuclear Information System (INIS)

    Black, J.H.

    1987-01-01

    The author defines and discusses the nature of diffuse interstellar clouds. He discusses how they contribute to the general extinction of starlight. The atomic and molecular species that have been identified in the ultraviolet, visible, and near infrared regions of the spectrum of a diffuse cloud are presented. The author illustrates some of the practical considerations that affect absorption line observations of interstellar atoms and molecules. Various aspects of the theoretical description of diffuse clouds required for a full interpretation of the observations are discussed

  15. Infrared diffuse interstellar bands

    Science.gov (United States)

    Galazutdinov, G. A.; Lee, Jae-Joon; Han, Inwoo; Lee, Byeong-Cheol; Valyavin, G.; Krełowski, J.

    2017-05-01

    We present high-resolution (R ˜ 45 000) profiles of 14 diffuse interstellar bands in the ˜1.45 to ˜2.45 μm range based on spectra obtained with the Immersion Grating INfrared Spectrograph at the McDonald Observatory. The revised list of diffuse bands with accurately estimated rest wavelengths includes six new features. The diffuse band at 15 268.2 Å demonstrates a very symmetric profile shape and thus can serve as a reference for finding the 'interstellar correction' to the rest wavelength frame in the H range, which suffers from a lack of known atomic/molecular lines.

  16. Self diffusion in tungsten

    International Nuclear Information System (INIS)

    Mundy, J.N.; Rothman, S.J.; Lam, N.Q.; Nowicki, L.J.; Hoff, H.A.

    1978-01-01

    The lack of understanding of self-diffusion in Group VI metals together with the wide scatter in the measured values of tungsten self-diffusion has prompted the present measurements to be made over a wide temperature range (1/2Tsub(m) to Tsub(m)). The diffusion coefficients have been measured in the temperature range 1430-2630 0 C. The present measurements show non-linear Arrhenius behavior but a reliable two-exponential fit of the data should await further measurements. (Auth.)

  17. Correlation effects in diffusion: a new approach

    International Nuclear Information System (INIS)

    Benoist, Pierre; Lafore, Pierre; Bocquet, J.-L.

    1975-11-01

    All the methods used up to now to solve the correlation problems are approximate: they do not allow the defect causing the migration to walk to infinity in the crystal. The new method of the present study enables to solve rigorously the correlation problems with the use of double Laplace-Fourier transforms. The method yields both: a compact formulation of all the problems previously treated by other investigators; a solution for problems still unresolved (influence of vacancy concentration on the correlation factor for self diffusion) or too much sophisticated to be treated by the previous methods (dissociated interstitial...) [fr

  18. Distributed order reaction-diffusion systems associated with Caputo derivatives

    Science.gov (United States)

    Saxena, R. K.; Mathai, A. M.; Haubold, H. J.

    2014-08-01

    This paper deals with the investigation of the solution of an unified fractional reaction-diffusion equation of distributed order associated with the Caputo derivatives as the time-derivative and Riesz-Feller fractional derivative as the space-derivative. The solution is derived by the application of the joint Laplace and Fourier transforms in compact and closed form in terms of the H-function. The results derived are of general nature and include the results investigated earlier by other authors, notably by Mainardi et al. ["The fundamental solution of the space-time fractional diffusion equation," Fractional Calculus Appl. Anal. 4, 153-202 (2001); Mainardi et al. "Fox H-functions in fractional diffusion," J. Comput. Appl. Math. 178, 321-331 (2005)] for the fundamental solution of the space-time fractional equation, including Haubold et al. ["Solutions of reaction-diffusion equations in terms of the H-function," Bull. Astron. Soc. India 35, 681-689 (2007)] and Saxena et al. ["Fractional reaction-diffusion equations," Astrophys. Space Sci. 305, 289-296 (2006a)] for fractional reaction-diffusion equations. The advantage of using the Riesz-Feller derivative lies in the fact that the solution of the fractional reaction-diffusion equation, containing this derivative, includes the fundamental solution for space-time fractional diffusion, which itself is a generalization of fractional diffusion, space-time fraction diffusion, and time-fractional diffusion, see Schneider and Wyss ["Fractional diffusion and wave equations," J. Math. Phys. 30, 134-144 (1989)]. These specialized types of diffusion can be interpreted as spatial probability density functions evolving in time and are expressible in terms of the H-function in compact forms. The convergence conditions for the double series occurring in the solutions are investigated. It is interesting to observe that the double series comes out to be a special case of the Srivastava-Daoust hypergeometric function of two variables

  19. Diffusion of Wilson loops

    International Nuclear Information System (INIS)

    Brzoska, A.M.; Lenz, F.; Thies, M.; Negele, J.W.

    2005-01-01

    A phenomenological analysis of the distribution of Wilson loops in SU(2) Yang-Mills theory is presented in which Wilson loop distributions are described as the result of a diffusion process on the group manifold. It is shown that, in the absence of forces, diffusion implies Casimir scaling and, conversely, exact Casimir scaling implies free diffusion. Screening processes occur if diffusion takes place in a potential. The crucial distinction between screening of fundamental and adjoint loops is formulated as a symmetry property related to the center symmetry of the underlying gauge theory. The results are expressed in terms of an effective Wilson loop action and compared with various limits of SU(2) Yang-Mills theory

  20. Diffusion between evolving interfaces

    International Nuclear Information System (INIS)

    Juntunen, Janne; Merikoski, Juha

    2010-01-01

    Diffusion in an evolving environment is studied by continuous-time Monte Carlo simulations. Diffusion is modeled by continuous-time random walkers on a lattice, in a dynamic environment provided by bubbles between two one-dimensional interfaces driven symmetrically towards each other. For one-dimensional random walkers constrained by the interfaces, the bubble size distribution dominates diffusion. For two-dimensional random walkers, it is also controlled by the topography and dynamics of the interfaces. The results of the one-dimensional case are recovered in the limit where the interfaces are strongly driven. Even with simple hard-core repulsion between the interfaces and the particles, diffusion is found to depend strongly on the details of the dynamical rules of particles close to the interfaces.

  1. On Diffusion and Permeation

    KAUST Repository

    Peppin, Stephen S. L.

    2009-01-01

    concentrations they form a nearly rigid porous glass through which the fluid permeates. The theoretically determined pressure drop is nonlinear in the diffusion regime and linear in the permeation regime, in quantitative agreement with experimental measurements

  2. Diffusing Best Practices

    DEFF Research Database (Denmark)

    Pries-Heje, Jan; Baskerville, Richard

    2014-01-01

    approach. The study context is a design case in which an organization desires to diffuse its best practices across different groups. The design goal is embodied in organizational mechanisms to achieve this diffusion. The study used Theory of Planned Behavior (TPB) as a kernel theory. The artifacts...... resulting from the design were two-day training workshops conceptually anchored to TBP. The design theory was evaluated through execution of eight diffusion workshops involving three different groups in the same company. The findings indicate that the match between the practice and the context materialized...... that the behavior will be effective). These two factors were especially critical if the source context of the best practice is qualitatively different from the target context into which the organization is seeking to diffuse the best practice....

  3. Detection of diffusible substances

    Energy Technology Data Exchange (ETDEWEB)

    Warembourg, M [Lille-1 Univ., 59 - Villeneuve-d' Ascq (France)

    1976-12-01

    The different steps of a radioautographic technique for the detection of diffusible substances are described. Using this radioautographic method, the topographic distribution of estradiol-concentrating neurons was studied in the nervous system and pituitary of the ovariectomized mouse and guinea-pig. A relatively good morphological preservation of structures can be ascertained on sections from unfixed, unembedded tissues prepared at low temperatures and kept-under relatively low humidity. The translocation or extraction of diffusible substances is avoided by directly mounting of frozen sections on dried photographic emulsion. Since no solvent is used, this technique excludes the major sources of diffusion artifacts and permits to be in favourable conditions for the localization of diffusible substances.

  4. On Diffusion and Permeation

    KAUST Repository

    Peppin, Stephen S. L.

    2009-01-01

    Diffusion and permeation are discussed within the context of irreversible thermodynamics. A new expression for the generalized Stokes-Einstein equation is obtained which links the permeability to the diffusivity of a two-component solution and contains the poroelastic Biot-Willis coefficient. The theory is illustrated by predicting the concentration and pressure profiles during the filtration of a protein solution. At low concentrations the proteins diffuse independently while at higher concentrations they form a nearly rigid porous glass through which the fluid permeates. The theoretically determined pressure drop is nonlinear in the diffusion regime and linear in the permeation regime, in quantitative agreement with experimental measurements. © 2009 Walter de Gruyter, Berlin, New York.

  5. Drift-Diffusion Equation

    Directory of Open Access Journals (Sweden)

    K. Banoo

    1998-01-01

    equation in the discrete momentum space. This is shown to be similar to the conventional drift-diffusion equation except that it is a more rigorous solution to the Boltzmann equation because the current and carrier densities are resolved into M×1 vectors, where M is the number of modes in the discrete momentum space. The mobility and diffusion coefficient become M×M matrices which connect the M momentum space modes. This approach is demonstrated by simulating electron transport in bulk silicon.

  6. Now consider diffusion

    International Nuclear Information System (INIS)

    Dungey, J.W.

    1984-01-01

    The authors want to talk about future work, but first he will reply to Stan Cowley's comment on his naivety in believing in the whole story to 99% confidence in '65, when he knew about Fairfield's results. Does it matter whether you make the right judgment about theories? Yes, it does, particularly for experimentalists perhaps, but also for theorists. The work you do later depends on the judgment you've made on previous work. People have wasted a lot of time developing on insecure or even wrong foundations. Now for future work. One mild surprise the authors have had is that they haven't heard more about diffusion, in two contexts. Gordon Rostoker is yet to come and he may talk about particles getting into the magnetosphere by diffusion. Lots of noise is observed and so diffusion must happen. If time had not been short, the authors were planning to discuss in a handwaving way what sort of diffusion mechanisms one might consider. The other aspect of diffusion he was going to talk about is at the other end of things and is velocity diffusion, which is involved in anomalous resistivity

  7. Double-disc gate valve

    International Nuclear Information System (INIS)

    Wheatley, S.J.

    1979-01-01

    The invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewith, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separation of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve

  8. Aristotle and Double Effect

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2014-01-01

    There are some interesting similarities between Aristotle’s ‘mixed actions’ in Book III of the Nicomachean Ethics and the actions often thought to be justifiable with the Doctrine of Double Effect. Here I analyse these similarities by comparing Aristotle’s examples of mixed actions with standard...... cases from the literature on double effect such as, amongst others, strategic bombing, the trolley problem, and craniotomy. I find that, despite some common features such as the dilemmatic structure and the inevitability of a bad effect, Aristotle’s mixed actions do not count as cases justifiable...... through application of the Doctrine of Double Effect because they fail to meet the crucial necessary condition of the Doctrine according to which the bad effect can only be a merely foreseen side- effect and not an intended means....

  9. Coulomb double helical structure

    Science.gov (United States)

    Kamimura, Tetsuo; Ishihara, Osamu

    2012-01-01

    Structures of Coulomb clusters formed by dust particles in a plasma are studied by numerical simulation. Our study reveals the presence of various types of self-organized structures of a cluster confined in a prolate spheroidal electrostatic potential. The stable configurations depend on a prolateness parameter for the confining potential as well as on the number of dust particles in a cluster. One-dimensional string, two-dimensional zigzag structure and three-dimensional double helical structure are found as a result of the transition controlled by the prolateness parameter. The formation of stable double helical structures resulted from the transition associated with the instability of angular perturbations on double strings. Analytical perturbation study supports the findings of numerical simulations.

  10. John Deakin: Double Exposures

    Directory of Open Access Journals (Sweden)

    Paul Rousseau

    2015-11-01

    Full Text Available In this series of short films made by Jonathan Law, the art historian James Boaden, and the curator of The John Deakin Archive, Paul Rousseau, discuss the double-exposure images made by the photographer John Deakin (1912-1972 in the 1950s and 1960s. The films ask you, firstly, to look closely at the images being discussed. Each one begins with a sustained and intense shot of a single image before opening up to a wide-ranging discussion about Deakin, double exposures, and photography.

  11. Double Photoionization Near Threshold

    Science.gov (United States)

    Wehlitz, Ralf

    2007-01-01

    The threshold region of the double-photoionization cross section is of particular interest because both ejected electrons move slowly in the Coulomb field of the residual ion. Near threshold both electrons have time to interact with each other and with the residual ion. Also, different theoretical models compete to describe the double-photoionization cross section in the threshold region. We have investigated that cross section for lithium and beryllium and have analyzed our data with respect to the latest results in the Coulomb-dipole theory. We find that our data support the idea of a Coulomb-dipole interaction.

  12. Double Chooz experiment

    International Nuclear Information System (INIS)

    Palomares, C.

    2009-01-01

    Double Chooz will use two identical detectors at different distances from the Chooz nuclear power station to search for a non-vanishing value of θ 13 , and, hopefully, to open the way to experiments aspiring to discover CP violation in the leptonic sector. The far detector is expected to be operative by the end of 2009. Installation of the near detector will occur in 2010. Double Chooz has the capacity to exclude sin 2 (2θ 13 ) 31 2 = 2.5 x 10 -3 eV 2 with three years of data running both near and far detectors. (author)

  13. Double-helix stellarator

    International Nuclear Information System (INIS)

    Moroz, P.E.

    1997-09-01

    A new stellarator configuration, the Double-Helix Stellarator (DHS), is introduced. This novel configuration features a double-helix center post as the only helical element of the stellarator coil system. The DHS configuration has many unique characteristics. One of them is the extreme low plasma aspect ratio, A ∼ 1--1.2. Other advantages include a high enclosed volume, appreciable rotational transform, and a possibility of extreme-high-β MHD equilibria. Moreover, the DHS features improved transport characteristics caused by the absence of the magnetic field ripple on the outboard of the torus. Compactness, simplicity and modularity of the coil system add to the DHS advantages for fusion applications

  14. Lead diffusion in monazite

    International Nuclear Information System (INIS)

    Gardes, E.

    2006-06-01

    Proper knowledge of the diffusion rates of lead in monazite is necessary to understand the U-Th-Pb age anomalies of this mineral, which is one of the most used in geochronology after zircon. Diffusion experiments were performed in NdPO 4 monocrystals and in Nd 0.66 Ca 0.17 Th 0.17 PO 4 polycrystals from Nd 0.66 Pb 0.17 Th 0.17 PO 4 thin films to investigate Pb 2+ + Th 4+ ↔ 2 Nd 3+ and Pb 2+ ↔ Ca 2+ exchanges. Diffusion annealings were run between 1200 and 1500 Celsius degrees, at room pressure, for durations ranging from one hour to one month. The diffusion profiles were analysed using TEM (transmission electronic microscopy) and RBS (Rutherford backscattering spectroscopy). The diffusivities extracted for Pb 2+ + Th 4+ ↔ 2 Nd 3+ exchange follow an Arrhenius law with parameters E equals 509 ± 24 kJ mol -1 and log(D 0 (m 2 s -1 )) equals -3.41 ± 0.77. Preliminary data for Pb 2+ ↔ Ca 2+ exchange are in agreement with this result. The extrapolation of our data to crustal temperatures yields very slow diffusivities. For instance, the time necessary for a 50 μm grain to lose all of its lead at 800 Celsius degrees is greater than the age of the Earth. From these results and other evidence from the literature, we conclude that most of the perturbations in U-Th-Pb ages of monazite cannot be attributed to lead diffusion, but rather to interactions with fluids. (author)

  15. The anisotropy of Hf diffusion in α-Zr

    International Nuclear Information System (INIS)

    Hood, G.M.; Zou, H.; Roy, J.A.; Schultz, R.J.; Matsuura, N.; Jackson, J.A.

    1995-07-01

    Hf diffusion coefficients (D) have been measured in the temperature interval 870-1100 K, in directions parallel (D pa ) and perpendicular (D pe ) to the c-axis of double-faced, single crystal specimens of both high-purity (HP) and nominally pure (NP) α-Zr single crystals. The diffusion profiles were measured by secondary ion mass spectrometry. Hf diffusion in HP α-Zr is characterised by an activation energy of about 3.0 eV and a pre-exponential factor of about 10 -5 m 2 /s. The anisotropy ratio, D pa /D pe is ∼ 1.0 for the NP specimens. A dependence of D on diffusion time/depth is indicated for some NP experiments on NP Zr. (author). 7 refs., 2 tabs., 3 figs

  16. Self- and zinc diffusion in gallium antimonide

    International Nuclear Information System (INIS)

    Nicols, Samuel Piers

    2002-01-01

    The technological age has in large part been driven by the applications of semiconductors, and most notably by silicon. Our lives have been thoroughly changed by devices using the broad range of semiconductor technology developed over the past forty years. Much of the technological development has its foundation in research carried out on the different semiconductors whose properties can be exploited to make transistors, lasers, and many other devices. While the technological focus has largely been on silicon, many other semiconductor systems have applications in industry and offer formidable academic challenges. Diffusion studies belong to the most basic studies in semiconductors, important from both an application as well as research standpoint. Diffusion processes govern the junctions formed for device applications. As the device dimensions are decreased and the dopant concentrations increased, keeping pace with Moore's Law, a deeper understanding of diffusion is necessary to establish and maintain the sharp dopant profiles engineered for optimal device performance. From an academic viewpoint, diffusion in semiconductors allows for the study of point defects. Very few techniques exist which allow for the extraction of as much information of their properties. This study focuses on diffusion in the semiconductor gallium antimonide (GaSb). As will become clear, this compound semiconductor proves to be a powerful one for investigating both self- and foreign atom diffusion. While the results have direct applications for work on GaSb devices, the results should also be taken in the broader context of III-V semiconductors. Results here can be compared and contrasted to results in systems such as GaAs and even GaN, indicating trends within this common group of semiconductors. The results also have direct importance for ternary and quaternary semiconductor systems used in devices such as high speed InP/GaAsSb/InP double heterojunction bipolar transistors (DHBT

  17. Diffusion Influenced Adsorption Kinetics.

    Science.gov (United States)

    Miura, Toshiaki; Seki, Kazuhiko

    2015-08-27

    When the kinetics of adsorption is influenced by the diffusive flow of solutes, the solute concentration at the surface is influenced by the surface coverage of solutes, which is given by the Langmuir-Hinshelwood adsorption equation. The diffusion equation with the boundary condition given by the Langmuir-Hinshelwood adsorption equation leads to the nonlinear integro-differential equation for the surface coverage. In this paper, we solved the nonlinear integro-differential equation using the Grünwald-Letnikov formula developed to solve fractional kinetics. Guided by the numerical results, analytical expressions for the upper and lower bounds of the exact numerical results were obtained. The upper and lower bounds were close to the exact numerical results in the diffusion- and reaction-controlled limits, respectively. We examined the validity of the two simple analytical expressions obtained in the diffusion-controlled limit. The results were generalized to include the effect of dispersive diffusion. We also investigated the effect of molecular rearrangement of anisotropic molecules on surface coverage.

  18. Bicarbonate diffusion through mucus.

    Science.gov (United States)

    Livingston, E H; Miller, J; Engel, E

    1995-09-01

    The mucus layer overlying duodenal epithelium maintains a pH gradient against high luminal acid concentrations. Despite these adverse conditions, epithelial surface pH remains close to neutrality. The exact nature of the gradient-forming barrier remains unknown. The barrier consists of mucus into which HCO3- is secreted. Quantification of the ability of HCO3- to establish and maintain the gradient depends on accurate measurement of this ion's diffusion coefficient through mucus. We describe new experimental and mathematical methods for diffusion measurement and report diffusion coefficients for HCO3- diffusion through saline, 5% mucin solutions, and rat duodenal mucus. The diffusion coefficients were 20.2 +/- 0.10, 3.02 +/- 0.31, and 1.81 +/- 0.12 x 10(-6) cm2/s, respectively. Modeling of the mucobicarbonate layer with this latter value suggests that for conditions of high luminal acid strength the neutralization of acid by HCO3- occurs just above the epithelial surface. Under these conditions the model predicts that fluid convection toward the lumen could be important in maintaining the pH gradient. In support of this hypothesis we were able to demonstrate a net luminal fluid flux of 5 microliters.min-1.cm-2 after perfusion of 0.15 N HCl in the rat duodenum.

  19. Double aortic arch

    Science.gov (United States)

    Surgery can be done to fix double aortic arch. The surgeon ties off the smaller branch and separates it from the larger branch. Then the surgeon closes the ends of the aorta with stitches. This relieves pressure on the esophagus and windpipe.

  20. Singapore's double festival

    Energy Technology Data Exchange (ETDEWEB)

    Fraser, Gordon

    1990-09-15

    Coinciding with celebrations for the nation's 25th anniversary, the 25th International Conference on High Energy Physics, held in Singapore from 2-8 August, was itself a double festival, with the Standard Model of contemporary physics and CERN's new LEP electron-positron collider providing the twin themes.

  1. Layered double hydroxides

    DEFF Research Database (Denmark)

    López Rayo, Sandra; Imran, Ahmad; Hansen, Hans Chr. Bruun

    2017-01-01

    A novel zinc (Zn) fertilizer concept based on Zn doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthetized, their chemical composition was analyzed and their nutrient release was studied in buffered solutions with different pH values. Uptake...

  2. Double Beta Decay Experiments

    International Nuclear Information System (INIS)

    Piepke, A.

    2005-01-01

    The experimental observation of neutrino oscillations and thus neutrino mass and mixing gives a first hint at new particle physics. The absolute values of the neutrino mass and the properties of neutrinos under CP-conjugation remain unknown. The experimental investigation of the nuclear double beta decay is one of the key techniques for solving these open problems

  3. Tensor estimation for double-pulsed diffusional kurtosis imaging.

    Science.gov (United States)

    Shaw, Calvin B; Hui, Edward S; Helpern, Joseph A; Jensen, Jens H

    2017-07-01

    Double-pulsed diffusional kurtosis imaging (DP-DKI) represents the double diffusion encoding (DDE) MRI signal in terms of six-dimensional (6D) diffusion and kurtosis tensors. Here a method for estimating these tensors from experimental data is described. A standard numerical algorithm for tensor estimation from conventional (i.e. single diffusion encoding) diffusional kurtosis imaging (DKI) data is generalized to DP-DKI. This algorithm is based on a weighted least squares (WLS) fit of the signal model to the data combined with constraints designed to minimize unphysical parameter estimates. The numerical algorithm then takes the form of a quadratic programming problem. The principal change required to adapt the conventional DKI fitting algorithm to DP-DKI is replacing the three-dimensional diffusion and kurtosis tensors with the 6D tensors needed for DP-DKI. In this way, the 6D diffusion and kurtosis tensors for DP-DKI can be conveniently estimated from DDE data by using constrained WLS, providing a practical means for condensing DDE measurements into well-defined mathematical constructs that may be useful for interpreting and applying DDE MRI. Data from healthy volunteers for brain are used to demonstrate the DP-DKI tensor estimation algorithm. In particular, representative parametric maps of selected tensor-derived rotational invariants are presented. Copyright © 2017 John Wiley & Sons, Ltd.

  4. Cesium diffusion in graphite

    International Nuclear Information System (INIS)

    Evans, R.B. III; Davis, W. Jr.; Sutton, A.L. Jr.

    1980-05-01

    Experiments on diffusion of 137 Cs in five types of graphite were performed. The document provides a completion of the report that was started and includes a presentation of all of the diffusion data, previously unpublished. Except for data on mass transfer of 137 Cs in the Hawker-Siddeley graphite, analyses of experimental results were initiated but not completed. The mass transfer process of cesium in HS-1-1 graphite at 600 to 1000 0 C in a helium atmosphere is essentially pure diffusion wherein values of (E/epsilon) and ΔE of the equation D/epsilon = (D/epsilon) 0 exp [-ΔE/RT] are about 4 x 10 -2 cm 2 /s and 30 kcal/mole, respectively

  5. Apparatus for diffusion separation

    International Nuclear Information System (INIS)

    Nierenberg, W.A.; Pontius, R.B.

    1976-01-01

    The method of testing the separation efficiency of porous permeable membranes is described which comprises causing a stream of a gaseous mixture to flow into contact with one face of a finely porous permeable membrane under such conditions that a major fraction of the mixture diffuses through the membrane, maintaining a rectangular cross section of the gaseous stream so flowing past said membrane, continuously recirculating the gas that diffuses through said membrane and continuously withdrawing the gas that does not diffuse through said membrane and maintaining the volume of said recirculating gas constant by continuously introducing into said continuously recirculating gas stream a mass of gas equivalent to that which is continuously withdrawn from said gas stream and comparing the concentrations of the light component in the entering gas, the withdrawn gas and the recirculated gas in order to determine the efficiency of said membrane

  6. Diffusion in flexible pipes

    Energy Technology Data Exchange (ETDEWEB)

    Brogaard Kristensen, S.

    2000-06-01

    This report describes the work done on modelling and simulation of the complex diffusion of gas through the wall of a flexible pipe. The diffusion and thus the pressure in annulus depends strongly on the diffusion and solubility parameters of the gas-polymer system and on the degree of blocking of the outer surface of the inner liner due to pressure reinforcements. The report evaluates the basis modelling required to describe the complex geometries and flow patterns. Qualitatively results of temperature and concentration profiles are shown in the report. For the program to serve any modelling purpose in 'real life' the results need to be validated and possibly the model needs corrections. Hopefully, a full-scale test of a flexible pipe will provide the required temperatures and pressures in annulus to validate the models. (EHS)

  7. Distributed Control Diffusion

    DEFF Research Database (Denmark)

    Schultz, Ulrik Pagh

    2007-01-01

    . Programming a modular, self-reconfigurable robot is however a complicated task: the robot is essentially a real-time, distributed embedded system, where control and communication paths often are tightly coupled to the current physical configuration of the robot. To facilitate the task of programming modular....... This approach allows the programmer to dynamically distribute behaviors throughout a robot and moreover provides a partial abstraction over the concrete physical shape of the robot. We have implemented a prototype of a distributed control diffusion system for the ATRON modular, self-reconfigurable robot......, self-reconfigurable robots, we present the concept of distributed control diffusion: distributed queries are used to identify modules that play a specific role in the robot, and behaviors that implement specific control strategies are diffused throughout the robot based on these role assignments...

  8. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

    cooling capacity, energy saving, low investment cost and low noise level; while the limitations include condensation risk and the limit on the room geometry. Furthermore, the crucial design parameters are summarized and their effects on the system performance are discussed. In addition to the stand...... is not well structured with this system. These become the motivations in developing the design guide. This design guide aims to establish a systematic understanding of diffuse ceiling ventilation and provide assistance in designing of such a system. The guide is targeted at design engineers, architects...... and manufacturers and the users of diffuse ceiling technology. The design guide introduces the principle and key characteristics of room air distribution with diffuse ceiling ventilation. It provides an overview of potential benefit and limitations of this technology. The benefits include high thermal comfort, high...

  9. Diffusion and mass transfer

    CERN Document Server

    Vrentas, James S

    2013-01-01

    The book first covers the five elements necessary to formulate and solve mass transfer problems, that is, conservation laws and field equations, boundary conditions, constitutive equations, parameters in constitutive equations, and mathematical methods that can be used to solve the partial differential equations commonly encountered in mass transfer problems. Jump balances, Green’s function solution methods, and the free-volume theory for the prediction of self-diffusion coefficients for polymer–solvent systems are among the topics covered. The authors then use those elements to analyze a wide variety of mass transfer problems, including bubble dissolution, polymer sorption and desorption, dispersion, impurity migration in plastic containers, and utilization of polymers in drug delivery. The text offers detailed solutions, along with some theoretical aspects, for numerous processes including viscoelastic diffusion, moving boundary problems, diffusion and reaction, membrane transport, wave behavior, sedime...

  10. Diffusion in flexible pipes

    Energy Technology Data Exchange (ETDEWEB)

    Brogaard Kristensen, S

    2000-06-01

    This report describes the work done on modelling and simulation of the complex diffusion of gas through the wall of a flexible pipe. The diffusion and thus the pressure in annulus depends strongly on the diffusion and solubility parameters of the gas-polymer system and on the degree of blocking of the outer surface of the inner liner due to pressure reinforcements. The report evaluates the basis modelling required to describe the complex geometries and flow patterns. Qualitatively results of temperature and concentration profiles are shown in the report. For the program to serve any modelling purpose in 'real life' the results need to be validated and possibly the model needs corrections. Hopefully, a full-scale test of a flexible pipe will provide the required temperatures and pressures in annulus to validate the models. (EHS)

  11. Thermal Diffusivity and Thermal Conductivity of Dispersed Glass Sphere Composites Over a Range of Volume Fractions

    Science.gov (United States)

    Carson, James K.

    2018-06-01

    Glass spheres are often used as filler materials for composites. Comparatively few articles in the literature have been devoted to the measurement or modelling of thermal properties of composites containing glass spheres, and there does not appear to be any reported data on the measurement of thermal diffusivities over a range of filler volume fractions. In this study, the thermal diffusivities of guar-gel/glass sphere composites were measured using a transient comparative method. The addition of the glass beads to the gel increased the thermal diffusivity of the composite, more than doubling the thermal diffusivity of the composite relative to the diffusivity of the gel at the maximum glass volume fraction of approximately 0.57. Thermal conductivities of the composites were derived from the thermal diffusivity measurements, measured densities and estimated specific heat capacities of the composites. Two approaches to modelling the effective thermal diffusivity were considered.

  12. The Trouble with Diffusion

    Directory of Open Access Journals (Sweden)

    R.T. DeHoff

    2002-09-01

    Full Text Available The phenomenological formalism, which yields Fick's Laws for diffusion in single phase multicomponent systems, is widely accepted as the basis for the mathematical description of diffusion. This paper focuses on problems associated with this formalism. This mode of description of the process is cumbersome, defining as it does matrices of interdiffusion coefficients (the central material properties that require a large experimental investment for their evaluation in three component systems, and, indeed cannot be evaluated for systems with more than three components. It is also argued that the physical meaning of the numerical values of these properties with respect to the atom motions in the system remains unknown. The attempt to understand the physical content of the diffusion coefficients in the phenomenological formalism has been the central fundamental problem in the theory of diffusion in crystalline alloys. The observation by Kirkendall that the crystal lattice moves during diffusion led Darken to develop the concept of intrinsic diffusion, i.e., atom motion relative to the crystal lattice. Darken and his successors sought to relate the diffusion coefficients computed for intrinsic fluxes to those obtained from the motion of radioactive tracers in chemically homogeneous samples which directly report the jump frequencies of the atoms as a function of composition and temperature. This theoretical connection between tracer, intrinsic and interdiffusion behavior would provide the basis for understanding the physical content of interdiffusion coefficients. Definitive tests of the resulting theoretical connection have been carried out for a number of binary systems for which all three kinds of observations are available. In a number of systems predictions of intrinsic coefficients from tracer data do not agree with measured values although predictions of interdiffusion coefficients appear to give reasonable agreement. Thus, the complete

  13. Nonlinear diffusion equations

    CERN Document Server

    Wu Zhuo Qun; Li Hui Lai; Zhao Jun Ning

    2001-01-01

    Nonlinear diffusion equations, an important class of parabolic equations, come from a variety of diffusion phenomena which appear widely in nature. They are suggested as mathematical models of physical problems in many fields, such as filtration, phase transition, biochemistry and dynamics of biological groups. In many cases, the equations possess degeneracy or singularity. The appearance of degeneracy or singularity makes the study more involved and challenging. Many new ideas and methods have been developed to overcome the special difficulties caused by the degeneracy and singularity, which

  14. Phase transformation and diffusion

    CERN Document Server

    Kale, G B; Dey, G K

    2008-01-01

    Given that the basic purpose of all research in materials science and technology is to tailor the properties of materials to suit specific applications, phase transformations are the natural key to the fine-tuning of the structural, mechanical and corrosion properties. A basic understanding of the kinetics and mechanisms of phase transformation is therefore of vital importance. Apart from a few cases involving crystallographic martensitic transformations, all phase transformations are mediated by diffusion. Thus, proper control and understanding of the process of diffusion during nucleation, g

  15. Ambipolar diffusion in plasma

    International Nuclear Information System (INIS)

    Silva, T.L. da.

    1987-01-01

    Is this thesis, a numerical method for the solution of the linear diffusion equation for a plasma containing two types of ions, with the possibility of charge exchange, has been developed. It has been shown that the decay time of the electron and ion densities is much smaller than that in a plasma containing only a single type of ion. A non-linear diffusion equation, which includes the effects of an external electric field varying linearly in time, to describe a slightly ionized plasma has also been developed. It has been verified that the decay of the electron density in the presence of such an electric field is very slow. (author)

  16. Diffuse axonal injury: detection of changes in anisotropy of water diffusion by diffusion-weighted imaging

    International Nuclear Information System (INIS)

    Chan, J.H.M.; Tsui, E.Y.K.; Yuen, M.K.; Peh, W.C.G.; Fong, D.; Fok, K.F.; Leung, K.M.; Fung, K.K.L.

    2003-01-01

    Myelinated axons of white matter demonstrate prominent directional differences in water diffusion. We performed diffusion-weighted imaging on ten patients with head injury to explore the feasibility of using water diffusion anisotropy for quantitating diffuse axonal injury. We showed significant decrease in diffusion anisotropy indices in areas with or without signal abnormality on T2 and T2*-weighted images. We conclude that the water diffusion anisotropy index a potentially useful, sensitive and quantitative way of diagnosing and assessing patients with diffuse axonal injury. (orig.)

  17. Double quick, double click reversible peptide "stapling".

    Science.gov (United States)

    Grison, Claire M; Burslem, George M; Miles, Jennifer A; Pilsl, Ludwig K A; Yeo, David J; Imani, Zeynab; Warriner, Stuart L; Webb, Michael E; Wilson, Andrew J

    2017-07-01

    The development of constrained peptides for inhibition of protein-protein interactions is an emerging strategy in chemical biology and drug discovery. This manuscript introduces a versatile, rapid and reversible approach to constrain peptides in a bioactive helical conformation using BID and RNase S peptides as models. Dibromomaleimide is used to constrain BID and RNase S peptide sequence variants bearing cysteine (Cys) or homocysteine ( h Cys) amino acids spaced at i and i + 4 positions by double substitution. The constraint can be readily removed by displacement of the maleimide using excess thiol. This new constraining methodology results in enhanced α-helical conformation (BID and RNase S peptide) as demonstrated by circular dichroism and molecular dynamics simulations, resistance to proteolysis (BID) as demonstrated by trypsin proteolysis experiments and retained or enhanced potency of inhibition for Bcl-2 family protein-protein interactions (BID), or greater capability to restore the hydrolytic activity of the RNAse S protein (RNase S peptide). Finally, use of a dibromomaleimide functionalized with an alkyne permits further divergent functionalization through alkyne-azide cycloaddition chemistry on the constrained peptide with fluorescein, oligoethylene glycol or biotin groups to facilitate biophysical and cellular analyses. Hence this methodology may extend the scope and accessibility of peptide stapling.

  18. Anisotropy in "isotropic diffusion" measurements due to nongaussian diffusion

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Olesen, Jonas Lynge; Ianuş, Andrada

    2017-01-01

    Designing novel diffusion-weighted NMR and MRI pulse sequences aiming to probe tissue microstructure with techniques extending beyond the conventional Stejskal-Tanner family is currently of broad interest. One such technique, multidimensional diffusion MRI, has been recently proposed to afford...... model-free decomposition of diffusion signal kurtosis into terms originating from either ensemble variance of isotropic diffusivity or microscopic diffusion anisotropy. This ability rests on the assumption that diffusion can be described as a sum of multiple Gaussian compartments, but this is often...

  19. diffusive phase separation

    Directory of Open Access Journals (Sweden)

    Nobuyuki Kenmochi

    1996-01-01

    w is constrained to have double obstacles σ*≤w≤σ* (i.e., σ* and σ* are the threshold values of w. The objective of this paper is to discuss the semigroup {S(t} associated with the phase separation model, and construct its global attractor.

  20. Diffusion in building wakes

    International Nuclear Information System (INIS)

    Ramsdell, J.V.

    1988-03-01

    Straight-line Gaussian models adequately describe atmospheric diffusion for many applications. They have been modified for use in estimating diffusion in building wakes by adding terms that include projected building area and by redefining the diffusion coefficients so that the coefficients have minimum values that are related to building dimensions. In a recent study, Ramsdell reviewed the building-wake dispersion models used by the Nuclear Regulatory Commission (NRC) in its control room habitability assessments. The review included comparison of model estimates of centerline concentrations with concentrations observed in experiments at seven nuclear reactors. In general, the models are conservative in that they tend to predict concentrations that are greater than those actually observed. However, the models show little skill in accounting for variations in the observed concentrations. Subsequently, the experimental data and multiples linear regression techniques have been used to develop a new building wake diffusion model. This paper describes the new building wake model and compares it with other models. 8 refs., 2 figs

  1. Osmosis and Diffusion

    Science.gov (United States)

    Sack, Jeff

    2005-01-01

    OsmoBeaker is a CD-ROM designed to enhance the learning of diffusion and osmosis by presenting interactive experimentation to the student. The software provides several computer simulations that take the student through different scenarios with cells, having different concentrations of solutes in them.

  2. Diffusion Based Photon Mapping

    DEFF Research Database (Denmark)

    Schjøth, Lars; Sporring, Jon; Fogh Olsen, Ole

    2008-01-01

    . To address this problem, we introduce a photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way, we preserve important illumination features, while...

  3. Bronnen van diffuse bodembelasting

    NARCIS (Netherlands)

    Lijzen JPA; Ekelenkamp A; LBG; DGM/BO

    1995-01-01

    The aim of this study was to support the policy on preventive soil protection with information on the diffuse (non-local) emissions to soil and the influence on future soil quality. This study is related to inventories on (potential) sources of local soil pollution (e.g. industrial areas,

  4. Diffusion in glass

    Energy Technology Data Exchange (ETDEWEB)

    Mubarak, A S

    1991-12-31

    Rutherford backscattering spectromertry technique (RBS) was used to characterize and investigate the depth distribution profiles of Ca-impurities of Ca-doped soda-time glass. The purposely added Ca-impurities were introduced inti the glass matrix by a normal ion exchange diffusion process. The measurements and analysis were performed using 2 MeV {sup 2}He{sup +} ions supplied from the University of Jordan Van de Graff acceierator (JOVAG). The normalized concetration versus depth profile distributions for the Ca-imourities were determined, both theoretically and experimentally. The theoretical treatment was carried out by setting up and soiving the diffusion equation under the conditions of the experiment. The resulting profiles are characterized by a compiementary error function. the theoretical treeatment was extended to include the various methods of enhancing the diffusion process, e.g. using an electric field. The diffusion coefficient, assumed constant, of the Ca-impurities exchanged in the soda-lime glass was determined to be 1.23 x 10{sup 13} cm{sup 2}/s. A comparison between theoretically and experimentally determined profiles is made and commented at, where several conclusions are drawn and suggestions for future work are mentioned. (author). 38 refs., 21 figs., 10 Tabs.

  5. Diffusion or bulk flow

    DEFF Research Database (Denmark)

    Schulz, Alexander

    2015-01-01

    is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...

  6. Multienergy anomalous diffuse scattering

    Czech Academy of Sciences Publication Activity Database

    Kopecký, Miloš; Fábry, Jan; Kub, Jiří; Lausi, A.; Busetto, E.

    2008-01-01

    Roč. 100, č. 19 (2008), 195504/1-195504/4 ISSN 0031-9007 R&D Projects: GA AV ČR IAA100100529 Institutional research plan: CEZ:AV0Z10100523 Keywords : diffuse scattering * x-rays * structure determination Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.180, year: 2008

  7. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

    with conventional ventilation systems (mixing or displacement ventilation), diffuse ceiling ventilation can significantly reduce or even eliminate draught risk in the occupied zone. Moreover, this ventilation system presents a promising opportunity for energy saving, because of the low pressure loss, extended free...

  8. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Heiselberg, Per; Nielsen, Peter V.

    2014-01-01

    As a novel air distribution system, diffuse ceiling ventilation combines the suspended acoustic ceiling with ventilation supply. Due to the low-impulse supply from the large ceiling area, the system does not generate draught when supplying cold air. However, heat sources play an important role...

  9. Diffusion in ceramics

    CERN Document Server

    Pelleg, Joshua

    2016-01-01

    This textbook provides an introduction to changes that occur in solids such as ceramics, mainly at high temperatures, which are diffusion controlled, as well as presenting research data. Such changes are related to the kinetics of various reactions such as precipitation, oxidation and phase transformations, but are also related to some mechanical changes, such as creep. The book is composed of two parts, beginning with a look at the basics of diffusion according to Fick's Laws. Solutions of Fick’s second law for constant D, diffusion in grain boundaries and dislocations are presented along with a look at the atomistic approach for the random motion of atoms. In the second part, the author discusses diffusion in several technologically important ceramics. The ceramics selected are monolithic single phase ones, including: A12O3, SiC, MgO, ZrO2 and Si3N4. Of these, three refer to oxide ceramics (alumina, magnesia and zirconia). Carbide based ceramics are represented by the technologically very important Si-ca...

  10. Subatmospheric double containment system

    International Nuclear Information System (INIS)

    Gans, D. Jr.; Noble, J.H.

    1978-01-01

    A reinforced concrete double wall nuclear containment structure with each wall including an essentially impervious membrane or liner and porous concrete filling the annulus between the two walls is described. The interior of the structure is maintained at subatmospheric pressure, and the annulus between the two walls is maintained at a subatmospheric pressure intermediate between that of the interior and the surrounding atmospheric pressure, during normal operation. In the event of an accident within the containment structure the interior pressure may exceed atmospheric pressure, but leakage from the interior to the annulus between the double walls will not result in the pressure of the annulus exceeding atmospheric pressure so that there is no net outleakage from the containment structure

  11. Double rupture disc experience

    International Nuclear Information System (INIS)

    1979-01-01

    Result of these observations, comparisons and evaluations can be summarized in the following list of concerns regarding the use of double rupture discs coupled to the liquid space of a steam generator that is subjected to a large leak sodium water reaction event. Single rupture disc show delayed collapse characteristics in LLTR Series I and double disc assemblies are presumed to be more complex with additional delay before opening to give pressure relief. Delayed failure increases pressures in the IHTS and must be adequately covered by design requirements. With CRBR design, the first disc may fail only partially reducing the loading on the second disc with the result that relief performance may not meet requirements

  12. Gravitational double layers

    International Nuclear Information System (INIS)

    Senovilla, José M M

    2014-01-01

    I analyze the properties of thin shells through which the scalar curvature R is discontinuous in gravity theories with Lagrangian F(R) = R − 2Λ + αR 2 on the bulk. These shells/domain walls are of a new kind because they possess, in addition to the standard energy–momentum tensor, an external energy flux vector, an external scalar pressure/tension and, most exotic of all, another energy–momentum contribution resembling classical dipole distributions on a shell: a double layer. I prove that all these contributions are necessary to make the entire energy–momentum tensor divergence-free. This is the first known occurrence of such a type of double layer in a gravity theory. I present explicit examples in constant-curvature five-dimensional bulks, with a brief study of their properties: new physical behaviors arise. (fast track communications)

  13. The double Laplacian growth

    International Nuclear Information System (INIS)

    Loutsenko, I.; Yermolayeva, O.

    2008-06-01

    The dynamics of the idealized Laplacian growth (or the Hele-Shaw problem) can be approximated by the Poiselle flow which in appropriate units takes the form of the Darcy law. In this paper we account for the liquid inertia in the Hele-Shaw problem at zero surface tension limit. The Laplace dynamics for the pressure is extended here with one more for the velocity potential for which we call this growth process the Double Laplacian. The application of the conformal mappings technique leads to doubled dynamics for both the conformal map and the complex potential, which is presented in the paper for the radial and the planar growth. We apply the stability analysis and discuss the integrability for the stated problem. (author)

  14. Algebra of Majorana doubling.

    Science.gov (United States)

    Lee, Jaehoon; Wilczek, Frank

    2013-11-27

    Motivated by the problem of identifying Majorana mode operators at junctions, we analyze a basic algebraic structure leading to a doubled spectrum. For general (nonlinear) interactions the emergent mode creation operator is highly nonlinear in the original effective mode operators, and therefore also in the underlying electron creation and destruction operators. This phenomenon could open up new possibilities for controlled dynamical manipulation of the modes. We briefly compare and contrast related issues in the Pfaffian quantum Hall state.

  15. Twisted quantum doubles

    Directory of Open Access Journals (Sweden)

    Daijiro Fukuda

    2004-01-01

    Full Text Available Using diagrammatic pictures of tensor contractions, we consider a Hopf algebra (Aop⊗ℛλA** twisted by an element ℛλ∈A*⊗Aop corresponding to a Hopf algebra morphism λ:A→A. We show that this Hopf algebra is quasitriangular with the universal R-matrix coming from ℛλ when λ2=idA, generalizing the quantum double construction which corresponds to the case λ=idA.

  16. New nonlinear-laser properties of ferroelectric Nd3+:Ba2NaNb5O15 - cw stimulated emission (4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 ), collinear and diffuse self-frequency doubling and summation

    International Nuclear Information System (INIS)

    Kaminskii, Alexandr A; Jaque, D; Garsia, Sole J; Capmany, J; Bagayev, S N; Ueda, Ken-ichi

    1999-01-01

    A new cw laser with self-frequency doubling and summation of 1-μm oscillation ( 4 F 3/2 → 4 I 11/2 ) was constructed on the basis of an orthorhombic Nd 3+ :Ba 2 NaNb 5 O 15 crystal. The 4 F 3/2 → 4 I 13/2 inter-Stark transition was used to excite cw 1.3-μm stimulated emission from this ferroelectric. (letters to the editor)

  17. Oxygen diffusion in zircon

    Science.gov (United States)

    Watson, E. B.; Cherniak, D. J.

    1997-05-01

    Oxygen diffusion in natural, non-metamict zircon was characterized under both dry and water-present conditions at temperatures ranging from 765°C to 1500°C. Dry experiments were performed at atmospheric pressure by encapsulating polished zircon samples with a fine powder of 18O-enriched quartz and annealing the sealed capsules in air. Hydrothermal runs were conducted in cold-seal pressure vessels (7-70 MPa) or a piston cylinder apparatus (400-1000 MPa) on zircon samples encapsulated with both 18O-enriched quartz and 18O water. Diffusive-uptake profiles of 18O were measured in all samples with a particle accelerator, using the 18O(p, α) 15N reaction. For dry experimental conditions at 1100-1500°C, the resulting oxygen diffusivities (24 in all) are well described by: D dry (m 2/s) = 1.33 × 10 -4exp(-53920/T) There is no suggestion of diffusive anisotropy. Under wet conditions at 925°C, oxygen diffusion shows little or no dependence upon P H 2O in the range 7-1000 MPa, and is insensitive to total pressure as well. The results of 27 wet experiments at 767-1160°C and 7-1000 MPa can be described a single Arrhenius relationship: D wet (m 2/s) = 5.5 × 10 -12exp(-25280/T) The insensitivity of oxygen diffusion to P H 2O means that applications to geologic problems can be pursued knowing only whether the system of interest was 'wet' (i.e., P H 2O > 7MPa ) or 'dry'. Under dry conditions (presumably rare in the crust), zircons are extremely retentive of their oxygen isotopic signatures, to the extent that δ 18O would be perturbed at the center of a 200 μm zircon only during an extraordinarily hot and protracted event (e.g., 65 Ma at 900°C). Under wet conditions, δ 18O may or may not be retained in the central regions of individual crystals, cores or overgrowth rims, depending upon the specific thermal history of the system.

  18. The Pearson diffusions: A class of statistically tractable diffusion processes

    DEFF Research Database (Denmark)

    Forman, Julie Lyng; Sørensen, Michael

    The Pearson diffusions is a flexible class of diffusions defined by having linear drift and quadratic squared diffusion coefficient. It is demonstrated that for this class explicit statistical inference is feasible. Explicit optimal martingale estimating func- tions are found, and the corresponding...

  19. Ac-induced disruption of the doubleDs structure in tomato

    NARCIS (Netherlands)

    Rommens, Caius M.T.; Biezen, Erik A. van der; Ouwerkerk, Pieter B.F.; Nijkamp, H. John J.; Hille, Jacques

    1991-01-01

    The maize doubleDs element is stably maintained in the tomato genome. Upon the subsequent introduction of Ac into a plant containing doubleDs, disruption of the doubleDs structure and DNA rearrangements at the site of the doubleDs element were observed. No indications were obtained for excision of

  20. Urban diffusion problems

    International Nuclear Information System (INIS)

    Hanna, S.R.

    1976-01-01

    It is hoped that urban diffusion models of air pollutants can eventually confidently be used to make major decisions, such as in planning the layout of a new industrial park, determining the effects of a new highway on air quality, or estimating the results of a new automobile emissions exhaust system. The urban diffusion model itself should be able to account for point, line, and area sources, and the local aerodynamic effects of street canyons and building wakes. Removal or transformations due to dry or wet deposition and chemical reactions are often important. It would be best if the model included meteorological parameters such as wind speed and temperature as dependent variables, since these parameters vary significantly when air passes from rural surfaces over urban surfaces

  1. Diffused Religion and Prayer

    Directory of Open Access Journals (Sweden)

    Roberto Cipriani

    2011-06-01

    Full Text Available It is quite likely that the origins of prayer are to be found in ancient mourning and bereavement rites. Primeval ritual prayer was codified and handed down socially to become a deep-rooted feature of people’s cultural behavior, so much so, that it may surface again several years later, in the face of death, danger, need, even in the case of relapse from faith and religious practice. Modes of prayer depend on religious experience, on relations between personal prayer and political action, between prayer and forgiveness, and between prayer and approaches to religions. Various forms of prayer exist, from the covert-hidden to the overt-manifest kind. How can they be investigated? How can one, for instance, explore mental prayer? These issues regard the canon of diffused religion and, therefore, of diffused prayer.

  2. Magnetic diffuse scattering

    International Nuclear Information System (INIS)

    Cable, J.W.

    1987-01-01

    The diffuse scattering of neutrons from magnetic materials provides unique and important information regarding the spatial correlations of the atoms and the spins. Such measurements have been extensively applied to magnetically ordered systems, such as the ferromagnetic binary alloys, for which the observed correlations describe the magnetic moment fluctuations associated with local environment effects. With the advent of polarization analysis, these techniques are increasingly being applied to study disordered paramagnetic systems such as the spin-glasses and the diluted magnetic semiconductors. The spin-pair correlations obtained are essential in understanding the exchange interactions of such systems. In this paper, we describe recent neutron diffuse scattering results on the atom-pair and spin-pair correlations in some of these disordered magnetic systems. 56 refs

  3. Diffusion in heterogeneous lattices

    Czech Academy of Sciences Publication Activity Database

    Tarasenko, Alexander; Jastrabík, Lubomír

    2010-01-01

    Roč. 256, č. 17 (2010), s. 5137-5144 ISSN 0169-4332 R&D Projects: GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : lattice- gas systems * diffusion * Monte Carlo simulations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.795, year: 2010

  4. Diffusion bonding techniques

    International Nuclear Information System (INIS)

    Peters, R.D.

    1978-01-01

    The applications of diffusion bonding at the General Electric Neutron Devices Department are briefly discussed, with particular emphasis on the gold/gold or gold/indium joints made between metallized alumina ceramic parts in the vacuum switch tube and the crystal resonator programs. Fixtures which use the differential expansion of dissimilar metals are described and compared to one that uses hydraulic pressure to apply the necessary bonding force

  5. Enrichment by diffusion

    International Nuclear Information System (INIS)

    Mezin, M.

    1976-01-01

    The report presents an introduction to general basic principles of the gaseous diffusion process for the separation of uranium isotopes. Dealt with are: a) theoretical background and basic considerations of separation work and production costs, b) construction of a single separation stage and a multistage plant, c) the components of a plant and the optimization factors, d) cost factors. The text is illustrated by instructive diagrammes and flow charts. (RB) [de

  6. Surface diffusion of sorbed radionuclides

    International Nuclear Information System (INIS)

    Berry, J.A.; Bond, K.A.

    1991-01-01

    Surface diffusion has in the past been invoked to explain rates of radionuclide migration which were greater than those predicted. Results were generally open to interpretation but the possible existence of surface diffusion, whereby sorbed radionuclides could potentially migrate at much enhanced rates, necessitated investigation. In this work through-diffusion experiments have shown that although surface diffusion does exist for some nuclides, the magnitude of the phenomenon is not sufficient to affect repository safety assessment modelling. (author)

  7. Diffusion in cladding materials

    International Nuclear Information System (INIS)

    Anand, M.S.; Pande, B.M.; Agarwala, R.P.

    1992-01-01

    Aluminium has been used as a cladding material in most research reactors because its low neutron absorption cross section and ease of fabrication. However, it is not suitable for cladding in power reactors and as such zircaloy-2 is normally used as a clad because it can withstand high temperature. It has low neutron absorption cross section, good oxidation, corrosion, creep properties and possesses good mechanical strength. With the passage of time, further development in this branch of science took place and designers started looking for better neutron economy and less hydrogen pickup in PHW reactors. The motion of fission products in the cladding material could pose a problem after long operation. In order to understand their behaviour under reactor environment, it is essential to study first the diffusion under normal conditions. These studies will throw light on the interaction of defects with impurities which would in turn help in understanding the mechanism of diffusion. In this article, it is intended to discuss the diffusion behaviour of impurities in cladding materials.(i.e. aluminium, zircaloy-2, zirconium-niobium alloy etc.). (author). 94 refs., 4 figs., 3 tabs

  8. The Double Star mission

    Directory of Open Access Journals (Sweden)

    Liu

    2005-11-01

    Full Text Available The Double Star Programme (DSP was first proposed by China in March, 1997 at the Fragrant Hill Workshop on Space Science, Beijing, organized by the Chinese Academy of Science. It is the first mission in collaboration between China and ESA. The mission is made of two spacecraft to investigate the magnetospheric global processes and their response to the interplanetary disturbances in conjunction with the Cluster mission. The first spacecraft, TC-1 (Tan Ce means "Explorer", was launched on 29 December 2003, and the second one, TC-2, on 25 July 2004 on board two Chinese Long March 2C rockets. TC-1 was injected in an equatorial orbit of 570x79000 km altitude with a 28° inclination and TC-2 in a polar orbit of 560x38000 km altitude. The orbits have been designed to complement the Cluster mission by maximizing the time when both Cluster and Double Star are in the same scientific regions. The two missions allow simultaneous observations of the Earth magnetosphere from six points in space. To facilitate the comparison of data, half of the Double Star payload is made of spare or duplicates of the Cluster instruments; the other half is made of Chinese instruments. The science operations are coordinated by the Chinese DSP Scientific Operations Centre (DSOC in Beijing and the European Payload Operations Service (EPOS at RAL, UK. The spacecraft and ground segment operations are performed by the DSP Operations and Management Centre (DOMC and DSOC in China, using three ground station, in Beijing, Shanghai and Villafranca.

  9. Solute diffusivity in undisturbed soil

    DEFF Research Database (Denmark)

    Lægdsmand, Mette; Møldrup, Per; Schjønning, Per

    2012-01-01

    Solute diffusivity in soil plays a major role in many important processes with relation to plant growth and environmental issues. Soil solute diffusivity is affected by the volumetric water content as well as the morphological characteristics of water-filled pores. The solute diffusivity in intact...

  10. Double your money

    International Nuclear Information System (INIS)

    Moxon, Suzanne

    1998-01-01

    The government-owned Hydro-Quebec was instructed to take certain actions, one of which was to increase profits. The company has published a report describing its plans for 1998-2002. The company expects to increase sales and double its income over the five years. Hydro-Quebec (which produces or purchases 97% of the electricity consumed in the province) will freeze prices until April 2002. Environmental considerations and liaison with local communities are included in the 5-year plan. The company expects to invest c$1.2B in international markets over the five years and C$20M per year are earmarked for research. (UK)

  11. Layered double hydroxides

    DEFF Research Database (Denmark)

    López Rayo, Sandra; Imran, Ahmad; Hansen, Hans Chr. Bruun

    2017-01-01

    A novel zinc (Zn) fertilizer concept based on Zn doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthetized, their chemical composition was analyzed and their nutrient release was studied in buffered solutions with different pH values. Uptake...... equation showing maximum release at pH 5.2, reaching approximately 45% of the total Zn content. The Zn concentrations in the plants receiving the LDHs were between 2- and 9.5-fold higher than those in plants without Zn addition. A positive effect of the LDHs was also found in soil. This work documents...

  12. Double sodium rubidium molybdates

    International Nuclear Information System (INIS)

    Mokhoseev, M.V.; Khal'baeva, K.M.; Khajkina, E.G.; Ogurtsov, A.M.

    1990-01-01

    According to ceramic technique double sodium-rubidium molybdates of the compositions Rb 2-x Na x MoO 4 (0.5≤x≤0.67) and Na 3 Rb(MoO 4 ) 2 have been prepared. It is ascertained that Rb 2-x Na x MoO 4 is crystallized in glaserite structural type (trigonal crystal system, sp.gr. P3m1, Z=2) and melts incongruently at 640 deg C. Na 3 Rb(MoO 4 ) 2 at room temperature is unstable and gradually decomposes into Na 2 MoO 4 and Rb 2-x Na x MoO 4

  13. Double profunda brachii artery

    OpenAIRE

    Gavishiddappa A Hadimani; Jyoti V Hadimani; Ishwar B Bagoji; Shardha Bai Rathod; Balappa M Bannur

    2016-01-01

    Brachial artery (BA) is a continuation of the axillary artery at the lower border of teres major. In the cubital fossa, BA divides into radial artery and ulnar artery as terminal branches. Large branch given from the BA in the upper part is profunda brachii artery. In the present case, we noticed double profunda brachii that arises from the BA. They are profunda brachii artery 1 and profunda brachii artery 2. Profunda brachii artery 1 arises in the proximal part of the BA and profunda brachii...

  14. Diffusion of Zonal Variables Using Node-Centered Diffusion Solver

    Energy Technology Data Exchange (ETDEWEB)

    Yang, T B

    2007-08-06

    Tom Kaiser [1] has done some preliminary work to use the node-centered diffusion solver (originally developed by T. Palmer [2]) in Kull for diffusion of zonal variables such as electron temperature. To avoid numerical diffusion, Tom used a scheme developed by Shestakov et al. [3] and found their scheme could, in the vicinity of steep gradients, decouple nearest-neighbor zonal sub-meshes leading to 'alternating-zone' (red-black mode) errors. Tom extended their scheme to couple the sub-meshes with appropriate chosen artificial diffusion and thereby solved the 'alternating-zone' problem. Because the choice of the artificial diffusion coefficient could be very delicate, it is desirable to use a scheme that does not require the artificial diffusion but still able to avoid both numerical diffusion and the 'alternating-zone' problem. In this document we present such a scheme.

  15. Diffusion of anions and cations in compacted sodium bentonite

    International Nuclear Information System (INIS)

    Muurinen, A.

    1994-02-01

    The thesis presents the results of studies on the diffusion mechanisms of anions and cations in compacted sodium bentonite, which is planned to be used as a buffer material in nuclear waste disposal in Finland. The diffusivities and sorption factors were determined by tracer experiments. The pore volume accessible to chloride, here defined as effective porosity, was determined as a function of bentonite density and electrolyte concentration in water, and the Stern-Gouy double-layer model was used to explain the observed anion exclusion. The sorption of Cs + and Sr 2+ was studied in loose and compacted bentonite samples as a function of the electrolyte concentration in solution. In order to obtain evidence of the diffusion of exchangeable cations, defined as surface diffusion, the diffusivities of Cs + and Sr 2+ in compacted bentonite were studied as a function of the sorption factor, which was varied by electrolyte concentration in solution. The measurements were performed both by a non-steady state method and by a through-diffusion method. (89 refs., 35 fig., 4 tab.)

  16. Application of impulsive methods to the study of diffusion in solid state alloys

    International Nuclear Information System (INIS)

    Belaidouni, Said

    1979-01-01

    This research thesis deals with the field of high temperature melt environments, and more particularly with the determination of the contribution of different steps of the electrochemical reaction (charge transfer, transport of electro-active species, variation of the electrode surface condition). The use of metal electrodes highlighted the importance of phenomena of diffusion in the metal. This leaded to the use of impulsive methods to determine solid-state transport properties. After a presentation of the theoretical processing of impulsive methods (cell potential, transport equations, double-layer charge), and a discussion of the diffusion in metal alloys (diffusion flow, diffusion coefficients, grain boundary diffusion), the author reports an experimental investigation (installation and measurement equipment) and discusses the obtained results (alloy thermodynamics, diffusion studied by the deposition method, impulsive methods with potentiostatic or galvano-static pulses) [fr

  17. Diffusion slowdown in the nanostructured liquid Ga-Sn alloy

    International Nuclear Information System (INIS)

    Podorozhkin, Dmitri Y.; Charnaya, Elena V.; Lee, Min Kai; Chang, Lieh-Jeng; Haase, Juergen; Michel, Dieter; Kumzerov, Yurii A.; Fokin, Alexsandr V.

    2015-01-01

    The diffusion of gallium in liquid Ga-Sn alloy embedded into different porous silica matrices was studied by NMR. Spin relaxation was measured for two gallium isotopes, 71 Ga and 69 Ga, at two magnetic fields. Pronounced rise of quadrupole contribution to relaxation was observed for the nanostructured alloy which increased with decreasing the pore size. The correlation time of atomic mobility was evaluated and found to be much larger than in the relevant bulk melt which evidenced a pronounced diffusion slowdown in the Ga-Sn alloy under nanoconfinement. It is shown that the diffusion was slower by a factor of 30 for the alloy within 7 nm pores. The spectral densities of electric field gradients at zero frequency were found to double for the finest pores. The Knight shift was found to decrease but slightly for the nanostructured alloy. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Firewalls from double purity

    Science.gov (United States)

    Bousso, Raphael

    2013-10-01

    The firewall paradox is often presented as arising from double entanglement, but I argue that more generally the paradox is double purity. Near-horizon modes are purified by the interior, in the infalling vacuum. Hence, they cannot also be pure alone, or in combination with any third system, as demanded by unitarity. This conflict arises independently of the Page time, for entangled and for pure states. It implies that identifications of Hilbert spaces cannot resolve the paradox. Traditional complementarity requires the unitary identification of infalling matter with a scrambled subsystem of the Hawking radiation. Extending this map to the infalling vacuum overdetermines the out-state. More general complementarity maps (“A=RB,” “ER=EPR”) necessarily fail when the near-horizon zone is pure. I argue that pure-zone states span the microcanonical ensemble, and that this suffices to make the horizon a special place. I advocate that the ability to detect the horizon locally, rather than the degree or probability of violence, is what makes firewalls problematic. Conversely, if the production of matter at the horizon can be dynamically understood and shown to be consistent, then firewalls do not constitute a violation of the equivalence principle.

  19. Particle diffusion in a spheromak

    International Nuclear Information System (INIS)

    Meyerhofer, D.D.; Levinton, F.M.; Yamada, M.

    1988-01-01

    The local carbon particle diffusion coefficient was measured in the Proto S-1/C spheromak using a test particle injection scheme. When the plasma was not in a force-free Taylor state, and when there were pressure gradients in the plasma, the particle diffusion was five times that predicted by Bohm and was consistent with collisional drift wave diffusion. The diffusion appears to be driven by correlations of the fluctuating electric field and density. During the decay phase of the discharge when the plasma was in the Taylor state, the diffusion coefficient of the carbon was classical. 23 refs., 4 figs

  20. Advanced diffusion processes and phenomena

    CERN Document Server

    Öchsner, Andreas; Belova, Irina

    2014-01-01

    This topical volume on Advanced Diffusion Processes and Phenomena addresses diffusion in a wider sense of not only mass diffusion but also heat diffusion in fluids and solids. Both diffusion phenomena play an important role in the characterization of engineering materials and corresponding structures. Understanding these different transport phenomena at many levels, from atomistic to macro, has therefore long attracted the attention of many researchers in materials science and engineering and related disciplines. The present topical volume captures a representative cross-section of some of the

  1. Measuring methods of matrix diffusion

    International Nuclear Information System (INIS)

    Muurinen, A.; Valkiainen, M.

    1988-03-01

    In Finland the spent nuclear fuel is planned to be disposed of at large depths in crystalline bedrock. The radionuclides which are dissolved in the groundwater may be able to diffuse into the micropores of the porous rock matrix and thus be withdrawn from the flowing water in the fractures. This phenomenon is called matrix diffusion. A review over matrix diffusion is presented in the study. The main interest is directed to the diffusion of non-sorbing species. The review covers diffusion experiments and measurements of porosity, pore size, specific surface area and water permeability

  2. Ferroelectric Nd3+:SrxBa1-x(NbO3)2-a new nonlinear laser crystal: cw 1-μm stimulated emission (4F3/2→4I11/2) and diffuse self-frequency doubling

    International Nuclear Information System (INIS)

    Kaminskii, Alexandr A; Garsia, Sole J; Jaque, D; Capmany, J; Bagayev, S N

    1998-01-01

    Stimulated emission as a result of the inter-Stark transition in the 1-μm 4 F 3/2 → 4 I 11/2 channel of Nd 3+ ions was excited for the first time in an acentric disordered Sr x Ba 1-x (NbO 3 ) 2 (x∼0.6) crystal. The low-threshold lasing of this crystal at the 1.0626 μm wavelength was accompanied by diffuse intracavity generation of the second harmonic. (letters to the editor)

  3. Use and abuse of diffusion

    International Nuclear Information System (INIS)

    Kwiotek, A.; Grzywna, Z.J.

    2005-01-01

    Diffusion in a bounded region (or diffusive mass transport) can be seen from at least three platforms: - chemistry of he Fick's equation; - chemical engineering. To pose a particular problem we have to provide some additional conditions (initial conditions, boundary conditions and further). As we understood it in all cases diffusion is considered in an open region (in other words in one phase). Chemical engineering however brings an idea of 'diffusion' between phases. We claim that there isn't diffusion between phases. One can only consider mass transport between phases. Mass transport (or transfer in chemical engineering jargon) from one phase to another composes of: diffusion in first phase partition at an interface diffusion in second phase. (author)

  4. Diffusion in amorphous media

    Science.gov (United States)

    Iotov, Mihail S.

    The goals of this research are twofold: First, to develop methods and tools for studying problems in chemistry, material science and biology, as well as accurate prediction of the properties of structures and materials of importance to those fields. Second, use those tools to apply the methods to practical problems. In terms of methodology development this thesis focuses on two topics: One: Development of a massively parallel computer program to perform electronic, atomic, molecular levels simulations of problems in chemistry, material science and biology. This computer program uses existing and emerging hardware platforms and parallel tools and is based on decades long research in computer modeling and algorithms. We report on that development in Chapter 3. Two: Development of tools for Molecular Dynamics simulation and methods and tools for course-grained meso-scale modeling of transport properties and especially diffusion of gas penetrants in polymers. We have formulated a new method for extracting coarse-grained information from short (0.2-0.5 nanoseconds [ns]) MD simulations and use this in a meso-scale simulation to calculate diffusion constants in polymer matrices. This is a grid-based method, which calculates the average probability of each grid point of being a void and performs constrained and biased Monte Carlo (MC) dynamics to reach much longer time regimes than possible in MD. The MC method mimics the three regimes of mean square deviation (MSD) behavior seen in MD, thus accounting for the proper mobility of the voids and the compressibility of the polymer matrix. Theoretical discussions and justification for the method is presented in chapter 6. Initial results on He diffusion in a low-density polyethylene (PE) matrix are presented in chapter 7. The behavior at different temperatures follows closely the trend observed from calibrating long term MD for this particular system.

  5. Diffusion in silicon isotope heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Silvestri, Hughes Howland [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    The simultaneous diffusion of Si and the dopants B, P, and As has been studied by the use of a multilayer structure of isotopically enriched Si. This structure, consisting of 5 pairs of 120 nm thick natural Si and 28Si enriched layers, enables the observation of 30Si self-diffusion from the natural layers into the 28Si enriched layers, as well as dopant diffusion from an implanted source in an amorphous Si cap layer, via Secondary Ion Mass Spectrometry (SIMS). The dopant diffusion created regions of the multilayer structure that were extrinsic at the diffusion temperatures. In these regions, the Fermi level shift due to the extrinsic condition altered the concentration and charge state of the native defects involved in the diffusion process, which affected the dopant and self-diffusion. The simultaneously recorded diffusion profiles enabled the modeling of the coupled dopant and self-diffusion. From the modeling of the simultaneous diffusion, the dopant diffusion mechanisms, the native defect charge states, and the self- and dopant diffusion coefficients can be determined. This information is necessary to enhance the physical modeling of dopant diffusion in Si. It is of particular interest to the modeling of future electronic Si devices, where the nanometer-scale features have created the need for precise physical models of atomic diffusion in Si. The modeling of the experimental profiles of simultaneous diffusion of B and Si under p-type extrinsic conditions revealed that both species are mediated by neutral and singly, positively charged Si self-interstitials. The diffusion of As and Si under extrinsic n-type conditions yielded a model consisting of the interstitialcy and vacancy mechanisms of diffusion via singly negatively charged self-interstitials and neutral vacancies. The simultaneous diffusion of P and Si has been modeled on the basis of neutral and singly negatively charged self-interstitials and neutral and singly

  6. Planar Dirac diffusion

    International Nuclear Information System (INIS)

    Leo, Stefano de; Rotelli, Pietro

    2009-01-01

    We present the results of the planar diffusion of a Dirac particle by step and barrier potentials, when the incoming wave impinges at an arbitrary angle with the potential. Except for right-angle incidence this process is characterized by the appearance of spin flip terms. For the step potential, spin flip occurs for both transmitted and reflected waves. However, we find no spin flip in the transmitted barrier result. This is surprising because the barrier result may be derived directly from a two-step calculation. We demonstrate that the spin flip cancellation indeed occurs for each ''particle'' (wave packet) contribution. (orig.)

  7. Radon diffusion chamber

    International Nuclear Information System (INIS)

    Pretzsch, G.; Boerner, E.; Lehmann, R.; Sarenio, O.

    1986-01-01

    The invention relates to the detection of radioactive gases emitting alpha particles like radon, thoron and their alpha-decaying daughters by means of a diffusion chamber with a passive detector, preferably with a solid state track detector. In the chamber above and towards the detector there is a single metallized electret with negative polarity. The distance between electret and detector corresponds to the range of the alpha particles of radon daughters in air at the most. The electret collects the positively charged daughters and functions as surface source. The electret increases the sensitivity by the factor 4

  8. Diffuse esophageal spasm

    International Nuclear Information System (INIS)

    Ott, D.J.; Chen, Y.M.; Hewson, E.G.; Richter, J.E.; Wu, W.C.; Gelfand, D.W.; Castell, D.O.

    1988-01-01

    Radiologic and manometric findings were correlated in 17 patients with diffuse esophageal spasm (DES). All patients initially had chest pain and/or dysphagia and had a manometric diagnosis of DES. Mean percentage of normal peristalsis manometrically was 46% (range, 20%-80%). Based on radiologic examination, an esophageal motor disorder consistent with DES was diagnosed in 12 of 17 patients, and there was one misinterpretation of achalasia. Radiologic detection was not related significantly to the percentage of peristalsis seen on manometric examination. Mean esophageal wall thickness as measured radiographically in patients with DES was 2.6 mm, compared with 2.5 mm in 17 individuals with normal results of manometry

  9. Elemental diffusion in stars

    International Nuclear Information System (INIS)

    Michaud, Georges; Montmerle, Thierry

    1977-01-01

    This paper is dealing with the origin of the elements in the universe. The scheme of nucleosynthesis is kept to explain the stellar generation of helium, carbon, etc... from the initial hydrogen; but a nonlinear theory is then elaborated to account for the anomalous abundances which were observed. The chemical elements would diffuse throughout the outer layers of a star under the action of the opposite forces of gravitation and radiation. This theory, with completing the nucleosynthesis, would contribute to give a consistent scheme of the elemental origin and abundances [fr

  10. Double Degenerate Stars

    International Nuclear Information System (INIS)

    Xin-Lian, Luo; Hua, Bai; Lei, Zhao

    2008-01-01

    Regardless of the formation mechanism, an exotic object, the double degenerate star (DDS), is introduced and investigated, which is composed of baryonic matter and some unknown fermion dark matter. Different from the simple white dwarfs (WDs), there is additional gravitational force provided by the unknown fermion component inside DDSs, which may strongly affect the structure and the stability of such kind of objects. Many possible and strange observational phenomena connecting with them are concisely discussed. Similar to the normal WD, this object can also experience thermonuclear explosion as type Ia supernova explosion when DDS's mass exceeds the maximum mass that can be supported by electron degeneracy pressure. However, since the total mass of baryonic matter can be much lower than that of WD at Chandrasekhar mass limit, the peak luminosity should be much dimmer than what we expect before, which may throw a slight shadow on the standard candle of SN Ia in the research of cosmology. (general)

  11. Double photoionization of strontium

    Energy Technology Data Exchange (ETDEWEB)

    Sokell, Emma; Grimm, Michael; Sheridan, Paul, E-mail: emma.sokell@ucd.i [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

    2010-02-01

    Resonant triple-differential cross-section (TDCS) measurements have been used to study the double photoionization process in strontium. Two sets of measurements were made at the photon energy of the 4p {yields} 4d resonance. The coplanar geometry was used and the fixed analyser, positioned at -90{sup 0} to the main axis of polarization of the photons, detected electrons with {approx}65% of the available excess energy. The mutual angle between the two electrons had a range just short of 90 {yields} 270{sup 0}. The TDCS exhibit unexpected lobes at a mutual angle of 180{sup 0}. Comparison with other measurements made with the same geometry but with different sharings of the available energy indicate that these TDCS all show the unexpected lobe. Some possible explanations for the lobe are considered.

  12. Double-Skin Facade

    DEFF Research Database (Denmark)

    Kalyanova, Olena

    favored by companies and their employees. To bring the reduction of energy use in these buildings application of suitable tools and methods is necessary to achieve successful design solutions. Earlier work on the topic of DSF modelling was examined from various publications. As a result, the main...... IEA Annex 34/43, subtask E "Double-Skin Facade". The results of empirical validation are discussed in this work. Discussion and analysis of experimental results is carried out. It has lead to hypothesis of recirculation flow phenomenon in the DSF cavity. Finally, a suggestion of a new numerical model...... is developed to account for recirculation flow appearance in the DSF cavity. The model is based on a simple mass balance between the boundary layer flow and the main flow in the cavity....

  13. Deconvoluting double Doppler spectra

    International Nuclear Information System (INIS)

    Ho, K.F.; Beling, C.D.; Fung, S.; Chan, K.L.; Tang, H.W.

    2001-01-01

    The successful deconvolution of data from double Doppler broadening of annihilation radiation (D-DBAR) spectroscopy is a promising area of endeavour aimed at producing momentum distributions of a quality comparable to those of the angular correlation technique. The deconvolution procedure we test in the present study is the constrained generalized least square method. Trials with computer simulated DDBAR spectra are generated and deconvoluted in order to find the best form of regularizer and the regularization parameter. For these trials the Neumann (reflective) boundary condition is used to give a single matrix operation in Fourier space. Experimental D-DBAR spectra are also subject to the same type of deconvolution after having carried out a background subtraction and using a symmetrize resolution function obtained from an 85 Sr source with wide coincidence windows. (orig.)

  14. Beyond the double banana

    DEFF Research Database (Denmark)

    Rosenzweig, Ivana; Fogarasi, András; Johnsen, Birger

    2014-01-01

    PURPOSE: To investigate whether extending the 10-20 array with 6 electrodes in the inferior temporal chain and constructing computed montages increases the diagnostic value of ictal EEG activity originating in the temporal lobe. In addition, the accuracy of computer-assisted spectral source......). Spectral source analysis used source montage to calculate density spectral array, defining the earliest oscillatory onset. From this, phase maps were calculated for localization. The reference standard was the decision of the multidisciplinary epilepsy surgery team on the seizure onset zone. Clinical...... performance was compared with the double banana (longitudinal bipolar montage, 10-20 array). RESULTS: Adding the inferior temporal electrode chain, computed montages (reference free, common average, and source derivation), and voltage maps significantly increased the sensitivity. Phase maps had the highest...

  15. Double-mode pulsation

    International Nuclear Information System (INIS)

    Cox, A.N.

    1982-01-01

    Double mode pulsation is a very pervasive phenomenon in stars all over the Hertzsprung-Russell diagram. In order of increasing radius, examples are: ZZ Ceti stars, the sun, the delta Scuti stars, RR Lyrae variables, the β Cephei variables and those related to them, Cepheids, and maybe even the Mira stars. These many modes have been interpreted as both radial and nonradial modes, but in many cases the actual mode has not been clearly identified. Yellow giants seem to be the most simple pulsators with a large majority of the RR Lyrae variables and Cepheids showing only one pulsation period. We limit this review to those very few cases for classical Cepheids and RR Lyrae variables which display two modes. For these we know many facts about these stars, but the actual cause of the pulsation in two modes simultaneously remains unknown

  16. Dual double field theory

    Energy Technology Data Exchange (ETDEWEB)

    Bergshoeff, Eric A. [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands); Hohm, Olaf [Simons Center for Geometry and Physics, Stony Brook University,Stony Brook, NY 11794-3636 (United States); Penas, Victor A. [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands); Riccioni, Fabio [INFN - Sezione di Roma, Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy)

    2016-06-06

    We present the dual formulation of double field theory at the linearized level. This is a classically equivalent theory describing the duals of the dilaton, the Kalb-Ramond field and the graviton in a T-duality or O(D,D) covariant way. In agreement with previous proposals, the resulting theory encodes fields in mixed Young-tableau representations, combining them into an antisymmetric 4-tensor under O(D,D). In contrast to previous proposals, the theory also requires an antisymmetric 2-tensor and a singlet, which are not all pure gauge. The need for these additional fields is analogous to a similar phenomenon for “exotic' dualizations, and we clarify this by comparing with the dualizations of the component fields. We close with some speculative remarks on the significance of these observations for the full non-linear theory yet to be constructed.

  17. Double profunda brachii artery

    Directory of Open Access Journals (Sweden)

    Gavishiddappa A Hadimani

    2016-01-01

    Full Text Available Brachial artery (BA is a continuation of the axillary artery at the lower border of teres major. In the cubital fossa, BA divides into radial artery and ulnar artery as terminal branches. Large branch given from the BA in the upper part is profunda brachii artery. In the present case, we noticed double profunda brachii that arises from the BA. They are profunda brachii artery 1 and profunda brachii artery 2. Profunda brachii artery 1 arises in the proximal part of the BA and profunda brachii artery 2 arises distal to the profunda brachii artery 1. Both the arteries run inferolaterally in the spiral groove along with radial nerve. Variations of profunda brachii artery are important during harvesting of the lateral arm flaps and may lead to inadvertent injury during percutaneous arterial catheterization or injection of drugs.

  18. GENERALIZED DOUBLE PARETO SHRINKAGE.

    Science.gov (United States)

    Armagan, Artin; Dunson, David B; Lee, Jaeyong

    2013-01-01

    We propose a generalized double Pareto prior for Bayesian shrinkage estimation and inferences in linear models. The prior can be obtained via a scale mixture of Laplace or normal distributions, forming a bridge between the Laplace and Normal-Jeffreys' priors. While it has a spike at zero like the Laplace density, it also has a Student's t -like tail behavior. Bayesian computation is straightforward via a simple Gibbs sampling algorithm. We investigate the properties of the maximum a posteriori estimator, as sparse estimation plays an important role in many problems, reveal connections with some well-established regularization procedures, and show some asymptotic results. The performance of the prior is tested through simulations and an application.

  19. Double optical gating

    Science.gov (United States)

    Gilbertson, Steve

    The observation and control of dynamics in atomic and molecular targets requires the use of laser pulses with duration less than the characteristic timescale of the process which is to be manipulated. For electron dynamics, this time scale is on the order of attoseconds where 1 attosecond = 10 -18 seconds. In order to generate pulses on this time scale, different gating methods have been proposed. The idea is to extract or "gate" a single pulse from an attosecond pulse train and switch off all the other pulses. While previous methods have had some success, they are very difficult to implement and so far very few labs have access to these unique light sources. The purpose of this work is to introduce a new method, called double optical gating (DOG), and to demonstrate its effectiveness at generating high contrast single isolated attosecond pulses from multi-cycle lasers. First, the method is described in detail and is investigated in the spectral domain. The resulting attosecond pulses produced are then temporally characterized through attosecond streaking. A second method of gating, called generalized double optical gating (GDOG), is also introduced. This method allows attosecond pulse generation directly from a carrier-envelope phase un-stabilized laser system for the first time. Next the methods of DOG and GDOG are implemented in attosecond applications like high flux pulses and extreme broadband spectrum generation. Finally, the attosecond pulses themselves are used in experiments. First, an attosecond/femtosecond cross correlation is used for characterization of spatial and temporal properties of femtosecond pulses. Then, an attosecond pump, femtosecond probe experiment is conducted to observe and control electron dynamics in helium for the first time.

  20. Diffusion in Solids Fundamentals, Methods, Materials, Diffusion-Controlled Processes

    CERN Document Server

    Mehrer, Helmut

    2007-01-01

    Diffusion is a vital topic in solid-state physics and chemistry, physical metallurgy and materials science. Diffusion processes are ubiquitous in solids at elevated temperatures. A thorough understanding of diffusion in materials is crucial for materials development and engineering. This book first gives an account of the central aspects of diffusion in solids, for which the necessary background is a course in solid state physics. It then provides easy access to important information about diffuson in metals, alloys, semiconductors, ion-conducting materials, glasses and nanomaterials. Several diffusion-controlled phenomena, including ionic conduction, grain-boundary and dislocation pipe diffusion, are considered as well. Graduate students in solid-state physics, physical metallurgy, materials science, physical and inorganic chemistry or geophysics will benefit from this book as will physicists, chemists, metallurgists, materials engineers in academic and industrial research laboratories.

  1. Apparatus for diffusion separation

    International Nuclear Information System (INIS)

    Nierenberg, W.A.

    1976-01-01

    A diffuser separator apparatus is described which comprises a plurality of flow channels in a single stage. Each of said channels has an inlet port and an outlet port and a constant cross sectional area between said ports. At least a portion of the defining surface of each of said channels is a diffusion separation membrane, and each of said channels is a different cross sectional area. Means are provided for connecting said channels in series so that each successive channel of said series has a smaller cross sectional area than the previous channel of said series. Also provided are a source of gaseous mixture, individual means for flowing said gaseous mixture to the inlet port of each of said channels, gas receiving and analyzing means, individual means for flowing gas passing from each of said outlet ports and means for flowing gas passing through said membranes to said receiving and analyzing means, and individual means for connecting the outlet port of each channel with the inlet port of the channel having the next smaller cross sectional area

  2. The diffusion of microfinance.

    Science.gov (United States)

    Banerjee, Abhijit; Chandrasekhar, Arun G; Duflo, Esther; Jackson, Matthew O

    2013-07-26

    To study the impact of the choice of injection points in the diffusion of a new product in a society, we developed a model of word-of-mouth diffusion and then applied it to data on social networks and participation in a newly available microfinance loan program in 43 Indian villages. Our model allows us to distinguish information passing among neighbors from direct influence of neighbors' participation decisions, as well as information passing by participants versus nonparticipants. The model estimates suggest that participants are seven times as likely to pass information compared to informed nonparticipants, but information passed by nonparticipants still accounts for roughly one-third of eventual participation. An informed household is not more likely to participate if its informed friends participate. We then propose two new measures of how effective a given household would be as an injection point. We show that the centrality of the injection points according to these measures constitutes a strong and significant predictor of eventual village-level participation.

  3. Diffuse infiltrative lung disease

    International Nuclear Information System (INIS)

    Niden, A.H.; Mishkin, F.S.

    1984-01-01

    The authors discuss their approach to the diagnosis and management of patients with DILD. Gallium scans play a central role in this process. Not only do they help them decide whom to biopsy, but also where to biopsy. The scans can be used for the early detection of disease in a high-risk population, for following the progression and regression of disease, for the regulation of medication, and for the evaluation of therapy. Bronchoalveolar lung lavage appears to be equally sensitive. However, patients are less willing to undergo repeated fiberoptic bronchoscopies than lung scans. Both tests may prove useful, one complementing the other. Gallium imaging has also been utilized by the authors in select patients with questionable diffuse lung infiltrates roentgenographically or with a normal chest roentgenogram, chronic respiratory symptoms, and abnormal pulmonary function studies. An abnormal gallium lung scan in these clinical situations helps them select which patients have a diffuse active pulmonary process meriting transbronchial biopsies. This has proven to be of particular value in the management of older patients

  4. Rare transformation to double hit lymphoma in Waldenstrom's macroglobulinemia.

    Science.gov (United States)

    Okolo, Onyemaechi N; Johnson, Ariel C; Yun, Seongseok; Arnold, Stacy J; Anwer, Faiz

    2017-08-01

    Waldenström macroglobulinemia (WM) is a lymphoproliferative lymphoma that is characterized by monoclonal immunoglobulin M (IgM) protein and bone marrow infiltration. Its incidence is rare and rarer still is its ability to transform to a B-cell lymphoma, particularly the aggressive diffuse large B-cell lymphoma, which bodes a poor prognosis. When transformation includes mutations of MYC, BCL-2 and/or BCL-6, it is known as a 'double hit' or 'triple hit' lymphoma respectively. This paper presents a rare case of WM with mutations positive for MYC and BCL2, making it a case of double hit B-cell lymphoplasmacytic lymphoma with plasmatic differentiation without morphological transformation to aggressive histology like DLBCL. The paper also broadens to include discussions on current topics in the classification, diagnosis, possible causes of transformation, and treatment of WM, including transformation to double hit lymphoma. The significance of this case lies in that the presence of double hit lymphoma-like genetic mutations in WM have not been previously described in the literature and potentially such changes are harbinger of extra-nodal presentation, aggressive growth, and possibly poor prognosis, if data from other double-hit lymphoma are extrapolated.

  5. Etiological aspects of double monsters.

    Science.gov (United States)

    Jaschevatzky, O E; Goldman, B; Kampf, D; Wexler, H; Grünstein, S

    1980-06-01

    Four cases of double monsters are reported, including a rare case of craniofacial duplication (diprosopus). Based on the findings observed, etiological factors of these malformations are discussed. We suggest that exogenous (environmental) factors such as habits, way of life or religious practices of certain populations can influence the development of double monsters.

  6. Confinement and diffusion in tokamaks

    International Nuclear Information System (INIS)

    McWilliams, R.

    1988-01-01

    The effect of electric field fluctuations on confinement and diffusion in tokamak is discussed. Based on the experimentally determined cross-field turbolent diffusion coefficient, D∼3.7*cT e /eB(δn i /n i ) rms which is also derived by a simple theory, the cross-field diffusion time, tp=a 2 /D, is calculated and compared to experimental results from 51 tokamak for standard Ohmic operation

  7. Diffuse scattering of neutrons

    International Nuclear Information System (INIS)

    Novion, C.H. de.

    1981-02-01

    The use of neutron scattering to study atomic disorder in metals and alloys is described. The diffuse elastic scattering of neutrons by a perfect crystal lattice leads to a diffraction spectrum with only Bragg spreads. the existence of disorder in the crystal results in intensity and position modifications to these spreads, and above all, to the appearance of a low intensity scatter between Bragg peaks. The elastic scattering of neutrons is treated in this text, i.e. by measuring the number of scattered neutrons having the same energy as the incident neutrons. Such measurements yield information on the static disorder in the crystal and time average fluctuations in composition and atomic displacements [fr

  8. Diffuse lung disease: Pneumoconioses

    International Nuclear Information System (INIS)

    McLoud, T.C.

    1987-01-01

    This paper begins with a discussion of the 1980 International Labour Organization classification of the pneumoconioses. Emphasis is on the common pneumoconioses, that is, silicosis, coalworker's pneumoconiosis, and asbestos-related pleural and parenchymal disease. Examples of the five radiographic forms of silicosis-simple and complicated silicosis, Caplan syndrome, silicotuberculosis, and acute silicosis- are presented, and the differential diagnoses are discussed. Discussion of asbestos-related disease included pleural manifestations such as plaques, diffuse pleural thickening, and asbestos pleural effusion as well as asbestosis and malignancies associated with asbestos exposure, such as bronchogenic carcinoma and malignant mesothelioma. Although the standard radiographic findings are stressed, the use of CT in the diagnosis of pneumoconiosis and the staging of dust-related malignancies is also discussed

  9. On Diffusive Climatological Models.

    Science.gov (United States)

    Griffel, D. H.; Drazin, P. G.

    1981-11-01

    A simple, zonally and annually averaged, energy-balance climatological model with diffusive heat transport and nonlinear albedo feedback is solved numerically. Some parameters of the model are varied, one by one, to find the resultant effects on the steady solution representing the climate. In particular, the outward radiation flux, the insulation distribution and the albedo parameterization are varied. We have found an accurate yet simple analytic expression for the mean annual insolation as a function of latitude and the obliquity of the Earth's rotation axis; this has enabled us to consider the effects of the oscillation of the obliquity. We have used a continuous albedo function which fits the observed values; it considerably reduces the sensitivity of the model. Climatic cycles, calculated by solving the time-dependent equation when parameters change slowly and periodically, are compared qualitatively with paleoclimatic records.

  10. Diffuse parenchymal lung disease

    Directory of Open Access Journals (Sweden)

    Sara Tomassetti

    2017-04-01

    Full Text Available Between September 2015 and August 2016 there were >1500 publications in the field of diffuse parenchymal lung diseases (DPLDs. For the Clinical Year in Review session at the European Respiratory Society Congress that was held in London, UK, in September 2016, we selected only five articles. This selection, made from the enormous number of published papers, does not include all the relevant studies that will significantly impact our knowledge in the field of DPLDs in the near future. This review article provides our personal view on the following topics: early diagnosis of idiopathic pulmonary fibrosis, current knowledge on the multidisciplinary team diagnosis of DPLDs and the diagnostic role of transbronchial cryobiopsy in this diagnostic setting, insights on the new entity of interstitial pneumonia with autoimmune features, and new therapeutic approaches for scleroderma-related interstitial lung disease.

  11. Convergence of Nelson diffusions

    International Nuclear Information System (INIS)

    Dell'Antonio, G.; Posilicano, A.

    1991-01-01

    Let ψ t , ψ t n , n≥1, be solutions of Schroedinger equations with potentials form-bounded by -1/2 Δ and initial data in H 1 (R d ). Let P, P n , n≥1, be the probability measures on the path space Ω=C(R + , R d ) given by the corresponding Nelson diffusions. We show that if {ψ t n } n≥1 converges to ψ t in H 2 (R d ), uniformly in t over compact intervals, then {P n } n≥1 converges to P in total variation. Moreover, if the potentials are in the Kato class K d , we show that the above result follows from H 1 -convergence of initial data, and K d -convergence of potentials. (orig.)

  12. Hereditary diffuse gastric cancer

    DEFF Research Database (Denmark)

    van der Post, Rachel S; Vogelaar, Ingrid P; Carneiro, Fátima

    2015-01-01

    Germline CDH1 mutations confer a high lifetime risk of developing diffuse gastric (DGC) and lobular breast cancer (LBC). A multidisciplinary workshop was organised to discuss genetic testing, surgery, surveillance strategies, pathology reporting and the patient's perspective on multiple aspects......, including diet post gastrectomy. The updated guidelines include revised CDH1 testing criteria (taking into account first-degree and second-degree relatives): (1) families with two or more patients with gastric cancer at any age, one confirmed DGC; (2) individuals with DGC before the age of 40 and (3...... the high mortality associated with invasive disease, prophylactic total gastrectomy at a centre of expertise is advised for individuals with pathogenic CDH1 mutations. Breast cancer surveillance with annual breast MRI starting at age 30 for women with a CDH1 mutation is recommended. Standardised endoscopic...

  13. The diffuse interstellar medium

    Science.gov (United States)

    Cox, Donald P.

    1990-01-01

    The last 20 years of the efforts to understand the diffuse ISM are reviewed, with recent changes of fundamental aspects being highlighted. Attention is given to the interstellar pressure and its components, the weight of the ISM, the midplane pressure contributions, and pressure contributions at 1 kpc. What velocity dispersions, cosmic ray pressure, and magnetic field pressure that can be expected for a gas in a high magnetic field environment is addressed. The intercloud medium is described, with reference to the work of Cox and Slavin (1989). Various caveats are discussed and a number of areas for future investigation are identified. Steps that could be taken toward a successful phase segregation model are discussed.

  14. Nonlocal diffusion and applications

    CERN Document Server

    Bucur, Claudia

    2016-01-01

    Working in the fractional Laplace framework, this book provides models and theorems related to nonlocal diffusion phenomena. In addition to a simple probabilistic interpretation, some applications to water waves, crystal dislocations, nonlocal phase transitions, nonlocal minimal surfaces and Schrödinger equations are given. Furthermore, an example of an s-harmonic function, its harmonic extension and some insight into a fractional version of a classical conjecture due to De Giorgi are presented. Although the aim is primarily to gather some introductory material concerning applications of the fractional Laplacian, some of the proofs and results are new. The work is entirely self-contained, and readers who wish to pursue related subjects of interest are invited to consult the rich bibliography for guidance.

  15. Contribution to the study of transverse turbulent diffusion in streams

    International Nuclear Information System (INIS)

    Masson, Olivier

    1991-01-01

    In this research our objective is to study the turbulent diffusion in a water flow, in particular the transverse diffusion. According to formulae reviewed in literature the diffusion coefficients (K) may be expressed as a function of several velocity parameters. A synthetic formula depending on a macro-scale length of turbulence L x and a turbulent intensity √(u' 2 ) is proposed: K = β.L x .U-bar.(√(u' 2 /U-bar)) 2 . In order to validate this expression we performed two in situ experiments (one in a wide river and the other in an irrigation canal) with a double set of measurements: turbulent velocities and concentrations of a diffusing tracer. The first set gives us usable data in our formula. The results, compared with values available in literature, give a good agreement. Moreover it appears that it is possible to roughly divide the data in two groups according to (1) the cross section shape and (2) the bed roughness. The second set allows us to evaluate a global turbulent mixing coefficient. The coefficients calculated by the two methods are in accordance so our formula is validated. Nevertheless some problems appear because of what is called secondary currents and coherent structures as those seen above bed cracks in the Garonne river. Those phenomenon may play a major part upon turbulent diffusion in real streams. Although they were made conspicuous by an analysis of transverse velocity component, it has not been yet possible to quantify their effects. (author) [fr

  16. Diffusion behavior for Se and Zr in sodium-bentonite

    International Nuclear Information System (INIS)

    Sato, Haruo; Yui, Mikazu; Yoshikawa, Hideki

    1995-01-01

    Apparent diffusion coefficients for Se and Zr in bentonite were measured by in-diffusion method at room temperature using water-saturated sodium-bentonite, Kunigel V1 reg-sign containing 50wt% Na-smectite as a major mineral was used as the bentonite material. The experiments were carried out in the dry density range of 400--1,800 kg/m 3 . Bentonite samples were immersed with distilled water and saturated before the experiments. The experiments for Se were carried out under N 2 atmospheric condition (O 2 : 2.5ppm). Those for Zr were carried out under aerobic condition. The apparent diffusion coefficients decrease with increasing density of the bentonite. Since dominant species of Se in the pore water is predicted to be SeO 3 2- , Se may be retarded by anion-exclusion because of negative charge on the surface of the bentonite and little sorption. The dominant species of Zr in the porewater is predicted to be Zr(OH) 5 - or HZrO 3 - . Distribution coefficient measured for Zr on the bentonite was about 1.0 m 3 /kg from batch experiments. Therefore, the retardation may be caused by combination of the sorption and the anion-exclusion. A modeling for the diffusion mechanisms in the bentonite were discussed based on an electric double layer theory. Comparison between the apparent diffusion coefficients predicted by the model and the measured ones shows a good agreement

  17. MHD diffuser model test program

    Energy Technology Data Exchange (ETDEWEB)

    Idzorek, J J

    1976-07-01

    Experimental results of the aerodynamic performance of seven candidate diffusers are presented to assist in determining their suitability for joining an MHD channel to a steam generator at minimum spacing. The three dimensional diffusers varied in area ratio from 2 to 3.8 and wall half angle from 2 to 5 degrees. The program consisted of five phases: (1) tailoring a diffuser inlet nozzle to a 15 percent blockage; (2) comparison of isolated diffusers at enthalpy ratios 0.5 to 1.0 with respect to separation characteristics and pressure recovery coefficients; (3) recording the optimum diffuser exit flow distribution; (4) recording the internal flow distribution within the steam generator when attached to the diffuser; and (5) observing isolated diffuser exhaust dynamic characteristics. The 2 and 2-1/3 degree half angle rectangular diffusers showed recovery coefficients equal to 0.48 with no evidence of flow separation or instability. Diffusion at angles greater than these produced flow instabilities and with angles greater than 3 degrees random flow separation and reattachment.

  18. MHD diffuser model test program

    International Nuclear Information System (INIS)

    Idzorek, J.J.

    1976-07-01

    Experimental results of the aerodynamic performance of seven candidate diffusers are presented to assist in determining their suitability for joining an MHD channel to a steam generator at minimum spacing. The three dimensional diffusers varied in area ratio from 2 to 3.8 and wall half angle from 2 to 5 degrees. The program consisted of five phases: (1) tailoring a diffuser inlet nozzle to a 15 percent blockage; (2) comparison of isolated diffusers at enthalpy ratios 0.5 to 1.0 with respect to separation characteristics and pressure recovery coefficients; (3) recording the optimum diffuser exit flow distribution; (4) recording the internal flow distribution within the steam generator when attached to the diffuser; and (5) observing isolated diffuser exhaust dynamic characteristics. The 2 and 2-1/3 degree half angle rectangular diffusers showed recovery coefficients equal to 0.48 with no evidence of flow separation or instability. Diffusion at angles greater than these produced flow instabilities and with angles greater than 3 degrees random flow separation and reattachment

  19. Diffusion rates for elevated releases

    International Nuclear Information System (INIS)

    Ramsdell, J.V.

    1983-11-01

    A search of the literature related to diffusion from elevated sources has determined that an adequate data base exists for use in developing parameterizations for estimating diffusion rates for material released from free standing stacks at nuclear power plants. A review of published data analyses indicates that a new parameterization of horizontal diffusion rates specifically for elevated releases is not likely to significantly change the magnitudes of horizontal diffusion coefficients on the average. However, the uncertainties associated with horizontal diffusion coefficient estimates under any given set of atmospheric conditions could be reduced by a new parameterization. Similarly, a new parameterization of vertical diffusion rates would be unlikely to significantly alter the magnitudes of diffusion coefficients for unstable atmospheric conditons. However, for neutral and stable atmospheric conditions, a new parameterization of vertical diffusion rates might increase vertical diffusion coefficients significantly. The increase would move ground-level time-integrated concentration maxima closer to the plant and would increase the maxima. 55 references, 2 figures, 4 tables

  20. Diffuse scattering in Ih ice

    International Nuclear Information System (INIS)

    Wehinger, Björn; Krisch, Michael; Bosak, Alexeï; Chernyshov, Dmitry; Bulat, Sergey; Ezhov, Victor

    2014-01-01

    Single crystals of ice Ih, extracted from the subglacial Lake Vostok accretion ice layer (3621 m depth) were investigated by means of diffuse x-ray scattering and inelastic x-ray scattering. The diffuse scattering was identified as mainly inelastic and rationalized in the frame of ab initio calculations for the ordered ice XI approximant. Together with Monte-Carlo modelling, our data allowed reconsidering previously available neutron diffuse scattering data of heavy ice as the sum of thermal diffuse scattering and static disorder contribution. (paper)

  1. Diffusion of condenser water discharge

    International Nuclear Information System (INIS)

    Iwakiri, Toshio

    1977-01-01

    Thermal and nuclear power stations in Japan are mostly located in coastal area, and the cooling water is discharged into sea as warm water. Recently, large interest is taken in this matter, and it is desirable to predict the diffusion of warm discharge accurately and to take effective measures for lowering the temperature. As for the methods of predicting the diffusion of warm discharge, simplified estimation, mathematical analysis and hydrographical model experiment are used corresponding to objects and conditions. As for the measures to lower temperature, the method of discharging warm water into deep sea bottom was confirmed to be very effective. In this paper, the phenomena of diffusion of warm discharge in sea, the methods of predicting the diffusion of warm discharge, and the deep sea discharge as the measure for lowering temperature are outlined. The factors concerning the diffusion of warm discharge in sea are the conditions of discharge, topography and sea state, and the diffusion is roughly divided into mixing diffusion in the vicinity of warm water outlet and eddy diffusion in distant region. It is difficult to change artificially the conditions of diffusion in distant region, and the measures of raising the rate of dilution in near region are effective, therefore the deep sea discharge is adopted. (Kako, I.)

  2. Diffusion effects in undulator radiation

    Directory of Open Access Journals (Sweden)

    Ilya Agapov

    2014-11-01

    Full Text Available Quantum diffusion effects in undulator radiation in semiclassical approximation are considered. Short-term effects on the electron beam motion are discussed and it is shown that approaches based on diffusion approximation with drift-diffusion coefficients derived from undulator or bending magnet radiation spectrum, and on Poisson statistics with radiation spectrum defined by the local beding field, all lead to similar results in terms of electron energy spread for cases of practical interest. An analytical estimate of the influence of quantum diffusion on the undulator radiation spectrum is derived.

  3. Sodium diffusion in boroaluminosilicate glasses

    DEFF Research Database (Denmark)

    Smedskjaer, Morten M.; Zheng, Qiuju; Mauro, John C.

    2011-01-01

    of isothermal sodium diffusion in BAS glasses by ion exchange, inward diffusion, and tracer diffusion experiments. By varying the [SiO2]/[Al2O3] ratio of the glasses, different structural regimes of sodium behavior are accessed. We show that the mobility of the sodium ions decreases with increasing [SiO2]/[Al2O......Understanding the fundamentals of alkali diffusion in boroaluminosilicate (BAS) glasses is of critical importance for advanced glass applications, e.g., the production of chemically strengthened glass covers for personal electronic devices. Here, we investigate the composition dependence...

  4. Double Charge Exchange Reactions and Double Beta Decay

    Science.gov (United States)

    Auerbach, N.

    2018-05-01

    The subject of this presentation is at the forefront of nuclear physics, namely double beta decay. In particular one is most interested in the neutrinoless process of double beta decay, when the decay proceeds without the emission of two neutrinos. The observation of such decay would mean that the lepton conservation symmetry is violated and that the neutrinos are of Majorana type, meaning that they are their own anti-particles. The life time of this process has two unknowns, the mass of the neutrino and the nuclear matrix element. Determining the nuclear matrix element and knowing the cross-section well will set limits on the neutrino mass. There is a concentrated effort among the nuclear physics community to calculate this matrix element. Usually these matrix elements are a very small part of the total strength of the transition operators involved in the process. There is no simple way to “calibrate” the nuclear double beta decay matrix element. The double beta decay is a double charge exchange process, therefore it is proposed that double charge exchange reactions using ion projectiles on nuclei that are candidates for double beta decay, will provide additional necessary information about the nuclear matrix elements.

  5. Turing instability in reaction-diffusion systems with nonlinear diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Zemskov, E. P., E-mail: zemskov@ccas.ru [Russian Academy of Sciences, Dorodnicyn Computing Center (Russian Federation)

    2013-10-15

    The Turing instability is studied in two-component reaction-diffusion systems with nonlinear diffusion terms, and the regions in parametric space where Turing patterns can form are determined. The boundaries between super- and subcritical bifurcations are found. Calculations are performed for one-dimensional brusselator and oregonator models.

  6. Double chambered right ventricle

    International Nuclear Information System (INIS)

    Cho, Chul Koo; Yu, Yun Jeong; Yeon, Kyung Mo; Han, Man Chung

    1983-01-01

    Fourteen cases of double chambered right ventricle were diagnosed angiographically and of these nine cases were confirmed after operation and autopsy at Seoul National University Hospital in recent four years since 1979. The clinical and radiological findings with the emphasis on the cinecardiographic findings were analysed. The summaries of the analysis are as follows: 1. Among 14 cases, 6 cases were male and 8 cases were female. Age distribution was from 4 years to 36 years. 2. In chest x-ray findings, pulmonary vascularity was increased in 8 cases, decreased in 4 cases, and normal in 2 cases. Cardiomegaly was observed in 8 cases and other showed normal heart size. 3. In cinecardiography, 11 cases had interventricular septal defect. Among these 11 cases, VSD located in proximal high pressure chamber was in 2 cases and located in distal low pressure chamber was in 9 cases. 4. The location of aberrant muscle bundle in sinus portion of right ventricle was in 8 cases. In the rest 6 cases, the aberrant muscle bundle was located below the infundibulum of right ventricle. 5. For accurate diagnosis and differential diagnosis with other congenital cardiac anomalies such as Tetralogy of Fallot or isolated pulmonic stenosis, biplane cineangiography and catheterization is an essential procedure

  7. Double chambered right ventricle

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chul Koo; Yu, Yun Jeong; Yeon, Kyung Mo; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1983-12-15

    Fourteen cases of double chambered right ventricle were diagnosed angiographically and of these nine cases were confirmed after operation and autopsy at Seoul National University Hospital in recent four years since 1979. The clinical and radiological findings with the emphasis on the cinecardiographic findings were analysed. The summaries of the analysis are as follows: 1. Among 14 cases, 6 cases were male and 8 cases were female. Age distribution was from 4 years to 36 years. 2. In chest x-ray findings, pulmonary vascularity was increased in 8 cases, decreased in 4 cases, and normal in 2 cases. Cardiomegaly was observed in 8 cases and other showed normal heart size. 3. In cinecardiography, 11 cases had interventricular septal defect. Among these 11 cases, VSD located in proximal high pressure chamber was in 2 cases and located in distal low pressure chamber was in 9 cases. 4. The location of aberrant muscle bundle in sinus portion of right ventricle was in 8 cases. In the rest 6 cases, the aberrant muscle bundle was located below the infundibulum of right ventricle. 5. For accurate diagnosis and differential diagnosis with other congenital cardiac anomalies such as Tetralogy of Fallot or isolated pulmonic stenosis, biplane cineangiography and catheterization is an essential procedure.

  8. Double Tracks closure report

    International Nuclear Information System (INIS)

    1997-06-01

    This report describes the remediation activities performed and the results of postremediation radiation surveys conducted at the Double Tracks site, located on Range 71 North, of the Nellis Air Force Range (NAFR) in southern Nevada. This remediation was conducted from June to August 1996 in accordance with the Interim Corrective Action Plan (ICAP) to remediate the site to an acceptable risk to human health and the environment. Soil with a total transuranic activity greater than 200 picoCuries per gram (pCi/g) was excavated, shipped to the Nevada Test Site (NTS), and disposed at the Area 3 Radioactive Waste Management Site (RWMS). A total of 52.3 grams of plutonium (Pu) with an activity of 5.12 Curies was disposed. The concrete pad at ground zero (GZ) was broken up, placed in a Sealand reg-sign container, and shipped to the NTS Area 6 decontamination pad. Additionally, approximately 10 m 3 (350 ft 3 ) of soil containing small chips of concrete was shipped to the NTS Area 6 decontamination pad. The concrete and soil/concrete mixture will be further characterized prior to disposal. At the time this report was written, characterization samples were being collected, with analytical results expected in January 1997. It is anticipated that the material will be disposed in mid-1997. This remediation is an interim action because final cleanup levels have not been established

  9. Double Beta Decay

    International Nuclear Information System (INIS)

    Fiorini, Ettore

    2008-01-01

    The importance of neutrinoless Double Beta Decay (DBD) is stressed in view of the recent results of experiments on neutrino oscillations which indicate that the difference between the squared masses of two neutrinos of different flavours is finite [For a recent review including neutrino properties and recent results see: Review of Particle Physics, J. of Phys. G: Nuclear and Particle Physics 33, 1]. As a consequence the mass of at least one neutrino has to be different from zero and it becomes imperative to determine its absolute value. The various experimental techniques to search for DBD are discussed together with the difficult problems of the evaluation of the corresponding nuclear matrix elements. The upper limits on neutrino mass coming from the results of the various experiments are reported together with the indication for a non zero value by one of them not confirmed so far. The two presently running experiments on neutrinoless DBD are briefly described together with the already approved or designed second generation searches aiming to reach the values on the absolute neutrino mass indicated by the results on neutrino oscillations

  10. Analyzing Double Image Illusion through Double Indiscernibility and Lattice Theory

    Directory of Open Access Journals (Sweden)

    Kohei Sonoda

    2011-10-01

    Full Text Available The figure-ground division plays a fundamental role in all image perceptions. Although there are a lot of studies about extraction of a figure such as detection of edges or grouping of texture, there are few discussions about a relationship between obtained figure and ground. We focused on double image illusions having two complementary relationships be- tween figure and ground and analyzed them. We divided the double image illusions according to two different interpretations and using these divisions we extracted and analyzed their logical structures by lattices derived from rough sets that we had developed. As a result we discovered unusual logical structures in double image illusions.

  11. The mechanism of Turing pattern formation in a positive feedback system with cross diffusion

    International Nuclear Information System (INIS)

    Yang, Xiyan; Liu, Tuoqi; Zhang, Jiajun; Zhou, Tianshou

    2014-01-01

    In this paper, we analyze a reaction–diffusion (R–D) system with a double negative feedback loop and find cases where self diffusion alone cannot lead to Turing pattern formation but cross diffusion can. Specifically, we first derive a set of sufficient conditions for Turing instability by performing linear stability analysis, then plot two bifurcation diagrams that specifically identify Turing regions in the parameter phase plane, and finally numerically demonstrate representative Turing patterns according to the theoretical predictions. Our analysis combined with previous studies actually implies an interesting fact that Turing patterns can be generated not only in a class of monostable R–D systems where cross diffusion is not necessary but also in a class of bistable R–D systems where cross diffusion is necessary. In addition, our model would be a good candidate for experimentally testing Turing pattern formation from the viewpoint of synthetic biology. (paper)

  12. Single-molecule diffusion and conformational dynamics by spatial integration of temporal fluctuations

    KAUST Repository

    Serag, Maged F.

    2014-10-06

    Single-molecule localization and tracking has been used to translate spatiotemporal information of individual molecules to map their diffusion behaviours. However, accurate analysis of diffusion behaviours and including other parameters, such as the conformation and size of molecules, remain as limitations to the method. Here, we report a method that addresses the limitations of existing single-molecular localization methods. The method is based on temporal tracking of the cumulative area occupied by molecules. These temporal fluctuations are tied to molecular size, rates of diffusion and conformational changes. By analysing fluorescent nanospheres and double-stranded DNA molecules of different lengths and topological forms, we demonstrate that our cumulative-area method surpasses the conventional single-molecule localization method in terms of the accuracy of determined diffusion coefficients. Furthermore, the cumulative-area method provides conformational relaxation times of structurally flexible chains along with diffusion coefficients, which together are relevant to work in a wide spectrum of scientific fields.

  13. Microstructural development of diffusion-brazed austenitic stainless steel to magnesium alloy using a nickel interlayer

    International Nuclear Information System (INIS)

    Elthalabawy, Waled M.; Khan, Tahir I.

    2010-01-01

    The differences in physical and metallurgical properties of stainless steels and magnesium alloys make them difficult to join using conventional fusion welding processes. Therefore, the diffusion brazing of 316L steel to magnesium alloy (AZ31) was performed using a double stage bonding process. To join these dissimilar alloys, the solid-state diffusion bonding of 316L steel to a Ni interlayer was carried out at 900 deg. C followed by diffusion brazing to AZ31 at 510 deg. C. Metallographic and compositional analyses show that a metallurgical bond was achieved with a shear strength of 54 MPa. However, during the diffusion brazing stage B 2 intermetallic compounds form within the joint and these intermetallics are pushed ahead of the solid/liquid interface during isothermal solidification of the joint. These intermetallics had a detrimental effect on joint strengths when the joint was held at the diffusion brazing temperature for longer than 20 min.

  14. Single-molecule diffusion and conformational dynamics by spatial integration of temporal fluctuations

    KAUST Repository

    Serag, Maged F.; Abadi, Maram; Habuchi, Satoshi

    2014-01-01

    Single-molecule localization and tracking has been used to translate spatiotemporal information of individual molecules to map their diffusion behaviours. However, accurate analysis of diffusion behaviours and including other parameters, such as the conformation and size of molecules, remain as limitations to the method. Here, we report a method that addresses the limitations of existing single-molecular localization methods. The method is based on temporal tracking of the cumulative area occupied by molecules. These temporal fluctuations are tied to molecular size, rates of diffusion and conformational changes. By analysing fluorescent nanospheres and double-stranded DNA molecules of different lengths and topological forms, we demonstrate that our cumulative-area method surpasses the conventional single-molecule localization method in terms of the accuracy of determined diffusion coefficients. Furthermore, the cumulative-area method provides conformational relaxation times of structurally flexible chains along with diffusion coefficients, which together are relevant to work in a wide spectrum of scientific fields.

  15. Models of diffuse solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Boland, John; Ridley, Barbara [Centre for Industrial and Applied Mathematics, University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, SA 5095 (Australia); Brown, Bruce [Department of Statistics and Applied Probability, National University of Singapore, Singapore 117546 (Singapore)

    2008-04-15

    For some locations both global and diffuse solar radiation are measured. However, for many locations, only global is measured, or inferred from satellite data. For modelling solar energy applications, the amount of radiation on a tilted surface is needed. Since only the direct component on a tilted surface can be calculated from trigonometry, we need to have diffuse on the horizontal available. There are regression relationships for estimating the diffuse on a tilted surface from diffuse on the horizontal. Models for estimating the diffuse radiation on the horizontal from horizontal global that have been developed in Europe or North America have proved to be inadequate for Australia [Spencer JW. A comparison of methods for estimating hourly diffuse solar radiation from global solar radiation. Sol Energy 1982; 29(1): 19-32]. Boland et al. [Modelling the diffuse fraction of global solar radiation on a horizontal surface. Environmetrics 2001; 12: 103-16] developed a validated model for Australian conditions. We detail our recent advances in developing the theoretical framework for the approach reported therein, particularly the use of the logistic function instead of piecewise linear or simple nonlinear functions. Additionally, we have also constructed a method, using quadratic programming, for identifying values that are likely to be erroneous. This allows us to eliminate outliers in diffuse radiation values, the data most prone to errors in measurement. (author)

  16. Osmosis and Diffusion Conceptual Assessment

    Science.gov (United States)

    Fisher, Kathleen M.; Williams, Kathy S.; Lineback, Jennifer Evarts

    2011-01-01

    Biology student mastery regarding the mechanisms of diffusion and osmosis is difficult to achieve. To monitor comprehension of these processes among students at a large public university, we developed and validated an 18-item Osmosis and Diffusion Conceptual Assessment (ODCA). This assessment includes two-tiered items, some adopted or modified…

  17. The diffusion of constitutional rights

    NARCIS (Netherlands)

    Goderis, B.V.G.; Versteeg, M.

    Constitutions are commonly regarded as uniquely national products, shaped by domestic ideals and politics. This paper develops and empirically investigates a novel hypothesis, which is that constitutions are also shaped by transnational influence, or “diffusion.” Constitutional rights can diffuse

  18. Diffusion measurements by Raman spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Shapiro, Alexander; Berg, Rolf W.

    Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt......Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt...

  19. Consequences of Diffusion of Innovations.

    Science.gov (United States)

    Goss, Kevin F.

    1979-01-01

    The article traces evolution of diffusion theory; illustrates undesirable consequences in a cross-cultural setting, reviews criticisms of several scholars; considers distributional effects and unanticipated consequences for potential ameliorative impact on diffusion theory; and codifies these factors into a framework for research into consequences…

  20. Enhancement of diffusers BRDF accuracy

    Science.gov (United States)

    Otter, Gerard; Bazalgette Courrèges-Lacoste, Gregory; van Brug, Hedser; Schaarsberg, Jos Groote; Delwart, Steven; del Bello, Umberto

    2017-11-01

    This paper reports the result of an ESA study conducted at TNO to investigate properties of various diffusers. Diffusers are widely used in space instruments as part of the on-board absolute calibration. Knowledge of the behaviour of the diffuser is therefore most important. From measurements of launched instruments in-orbit it has been discovered that when a diffuser is used in the vacuum of space the BRDF can change with respect to the one in ambient conditions. This is called the air/vacuum effect and has been simulated in this study by measuring the BRDF in a laboratory in ambient as well as vacuum conditions. Another studied effect is related to the design parameters of the optical system and the scattering properties of the diffuser. The effect is called Spectral Features and is a noise like structure superimposed on the diffuser BRDF. Modern space spectrometers, which have high spectral resolution and/or a small field of view (high spatial resolution) are suffering from this effect. The choice of diffuser can be very critical with respect to the required absolute radiometric calibration of an instrument. Even if the Spectral Features are small it can influence the error budget of the retrieval algorithms for the level 2 products. in this presentation diffuser trade-off results are presented and the Spectral Features model applied to the optical configuration of the MERIS instrument is compared to in-flight measurements of MERIS.

  1. Solutions of diffusion equations in two-dimensional cylindrical geometry by series expansions

    International Nuclear Information System (INIS)

    Ohtani, Nobuo

    1976-01-01

    A solution of the multi-group multi-regional diffusion equation in two-dimensional cylindrical (rho-z) geometry is obtained in the form of a regionwise double series composed of Bessel and trigonometrical functions. The diffusion equation is multiplied by weighting functions, which satisfy the homogeneous part of the diffusion equation, and the products are integrated over the region for obtaining the equations to determine the fluxes and their normal derivatives at the region boundaries. Multiplying the diffusion equation by each function of the set used for the flux expansion, then integrating the products, the coefficients of the double series of the flux inside each region are calculated using the boundary values obtained above. Since the convergence of the series thus obtained is slow especially near the region boundaries, a method for improving the convergence has been developed. The double series of the flux is separated into two parts. The normal derivative at the region boundary of the first part is zero, and that of the second part takes the value which is obtained in the first stage of this method. The second part is replaced by a continuous function, and the flux is represented by the sum of the continuous function and the double series. A sample critical problem of a two-group two-region system is numerically studied. The results show that the present method yields very accurately the flux integrals in each region with only a small number of expansion terms. (auth.)

  2. Passing to the limit in a Wasserstein gradient flow : from diffusion to reaction

    NARCIS (Netherlands)

    Arnrich, S.; Mielke, A.; Peletier, M.A.; Savaré, G.; Veneroni, M.

    2012-01-01

    We study a singular-limit problem arising in the modelling of chemical reactions. At finite e > 0, the system is described by a Fokker-Planck convection-diffusion equation with a double-well convection potential. This potential is scaled by 1 / e and in the limit e --> 0, the solution concentrates

  3. Z₂-double cyclic codes

    OpenAIRE

    Borges, J.

    2014-01-01

    A binary linear code C is a Z2-double cyclic code if the set of coordinates can be partitioned into two subsets such that any cyclic shift of the coordinates of both subsets leaves invariant the code. These codes can be identified as submodules of the Z2[x]-module Z2[x]/(x^r − 1) × Z2[x]/(x^s − 1). We determine the structure of Z2-double cyclic codes giving the generator polynomials of these codes. The related polynomial representation of Z2-double cyclic codes and its duals, and the relation...

  4. Aspects of the doubled worldsheet

    Energy Technology Data Exchange (ETDEWEB)

    Driezen, Sibylle; Sevrin, Alexander; Thompson, Daniel C. [Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)

    2016-12-16

    We clarify the relation between various approaches to the manifestly T-duality symmetric string. We explain in detail how the PST covariant doubled string arises from an unusual gauge fixing. We pay careful attention to the role of “spectator” fields in this process and also show how the T-duality invariant doubled dilaton emerges naturally. We extend these ideas to non-Abelian T-duality and show they give rise to the duality invariant formalism based on the semi-Abelian Drinfeld Double. We then develop the N=(0,1) supersymmetric duality invariant formalism.

  5. Addimer diffusions on Si(100)

    International Nuclear Information System (INIS)

    Lee, Gun Do; Wang, C. Z.; Lu, Z. Y.; Ho, K. M.

    1999-01-01

    The diffusion pathways along the trough and between the trough and the dimer row on the Si(100) surface are investigated by tight-binding molecular dynamics calculations using the environment dependent tight-binding silicon potential and by ab initio calculations using the Car-Parrinello method. The studies discover new diffusion pathways consisting of rotation of addimer. The calculated energy barrier are in excellent agreement with experiment. The rotational diffusion pathway between the trough and the dimer row is much more energetically favorable than other diffusion pathways by parallel and perpendicular addimer. The new pathway along the trough is nearly same as the energy barrier of the diffusion pathway by dissociation of the addimer

  6. Application of polycrystalline diffusion barriers

    International Nuclear Information System (INIS)

    Tsymbal, V.A.; Kolupaev, I.N.

    2010-01-01

    Degradation of contacts of the electronic equipment at the raised temperatures is connected with active diffusion redistribution of components contact - metalized systems (CMS) and phase production on interphase borders. One of systems diffusion barriers (DB) are polycrystalline silicide a film, in particular silicides of the titan. Reception disilicide the titan (TiSi 2 ) which on the parameters is demanded for conditions of microelectronics from known silicides of system Ti-Si, is possible as a result of direct reaction of a film of the titan and a substrate of silicon, and at sedimentation of layer Ti-Si demanded stoichiometric structure. Simultaneously there is specific problem polycrystalline diffusion a barrier (PDB): the polycrystalline provides structural balance and metastability film disilicide, but leaves in it borders of grains - easy local ways of diffusion. In clause the analysis diffusion permeability polycrystalline and polyphase DB is made and recommendations for practical methods of increase of blocking properties PDB are made.

  7. Diffusion in membranes: Toward a two-dimensional diffusion map

    Directory of Open Access Journals (Sweden)

    Toppozini Laura

    2015-01-01

    Full Text Available For decades, quasi-elastic neutron scattering has been the prime tool for studying molecular diffusion in membranes over relevant nanometer distances. These experiments are essential to our current understanding of molecular dynamics of lipids, proteins and membrane-active molecules. Recently, we presented experimental evidence from X-ray diffraction and quasi-elastic neutron scattering demonstrating that ethanol enhances the permeability of membranes. At the QENS 2014/WINS 2014 conference we presented a novel technique to measure diffusion across membranes employing 2-dimensional quasi-elastic neutron scattering. We present results from our preliminary analysis of an experiment on the cold neutron multi-chopper spectrometer LET at ISIS, where we studied the self-diffusion of water molecules along lipid membranes and have the possibility of studying the diffusion in membranes. By preparing highly oriented membrane stacks and aligning them horizontally in the spectrometer, our aim is to distinguish between lateral and transmembrane diffusion. Diffusion may also be measured at different locations in the membranes, such as the water layer and the hydrocarbon membrane core. With a complete analysis of the data, 2-dimensional mapping will enable us to determine diffusion channels of water and ethanol molecules to quantitatively determine nanoscale membrane permeability.

  8. The magnetic diffusion of neutrons; La diffusion magnetique des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, W C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The purpose of this report is to examine briefly the diffusion of neutrons by substances, particularly by crystals containing permanent atomic or ionic magnetic moments. In other words we shall deal with ferromagnetic, antiferromagnetic, ferrimagnetic or paramagnetic crystals, but first it is necessary to touch on nuclear diffusion of neutrons. We shall start with the interaction of the neutron with a single diffusion centre; the results will then be applied to the magnetic interactions of the neutron with the satellite electrons of the atom; finally we shall discuss the diffusion of neutrons by crystals. (author) [French] Le but de ce rapport est d'examiner, brievement, la diffusion des neutrons par les substances, et surtout, par des cristaux qui contiennent des moments magnetiques atomiques ou ioniques permanents. C'est-a-dire que nous nous interesserons aux cristaux ferromagnetiques, antiferromagnetiques, ferrimagnetiques ou paramagnetiques; il nous faut cependant rappeler d'abord la diffusion nucleaire des neutrons. Nous commencerons par l'interaction du neutron avec un seul centre diffuseur; puis les resultats seront appliques aux interactions magnetiques du neutron avec les electrons satellites de l'atome; enfin nous discuterons la diffusion des neutrons par les cristaux. (auteur)

  9. Multidimensional diffusion processes

    CERN Document Server

    Stroock, Daniel W

    1997-01-01

    From the reviews: "… Both the Markov-process approach and the Itô approach … have been immensely successful in diffusion theory. The Stroock-Varadhan book, developed from the historic 1969 papers by its authors, presents the martingale-problem approach as a more powerful - and, in certain regards, more intrinsic-means of studying the foundations of the subject. […] … the authors make the uncompromising decision not "to proselytise by intimidating the reader with myriad examples demonstrating the full scope of the techniques", but rather to persuade the reader "with a careful treatment of just one problem to which they apply". […] Most of the main tools of stochastic-processes theory are used, ..but it is the formidable combination of probability theory with analysis … which is the core of the work. […] I have emphasized the great importance of the Stroock-Varadhan book. It contains a lot more than I have indicated; in particular, its many exercises conain much interesting material. For immediat...

  10. Performance of active feedforward control systems in non-ideal, synthesized diffuse sound fields.

    Science.gov (United States)

    Misol, Malte; Bloch, Christian; Monner, Hans Peter; Sinapius, Michael

    2014-04-01

    The acoustic performance of passive or active panel structures is usually tested in sound transmission loss facilities. A reverberant sending room, equipped with one or a number of independent sound sources, is used to generate a diffuse sound field excitation which acts as a disturbance source on the structure under investigation. The spatial correlation and coherence of such a synthesized non-ideal diffuse-sound-field excitation, however, might deviate significantly from the ideal case. This has consequences for the operation of an active feedforward control system which heavily relies on the acquisition of coherent disturbance source information. This work, therefore, evaluates the spatial correlation and coherence of ideal and non-ideal diffuse sound fields and considers the implications on the performance of a feedforward control system. The system under consideration is an aircraft-typical double panel system, equipped with an active sidewall panel (lining), which is realized in a transmission loss facility. Experimental results for different numbers of sound sources in the reverberation room are compared to simulation results of a comparable generic double panel system excited by an ideal diffuse sound field. It is shown that the number of statistically independent noise sources acting on the primary structure of the double panel system depends not only on the type of diffuse sound field but also on the sample lengths of the processed signals. The experimental results show that the number of reference sensors required for a defined control performance exhibits an inverse relationship to control filter length.

  11. Diffusive instabilities in hyperbolic reaction-diffusion equations

    Science.gov (United States)

    Zemskov, Evgeny P.; Horsthemke, Werner

    2016-03-01

    We investigate two-variable reaction-diffusion systems of the hyperbolic type. A linear stability analysis is performed, and the conditions for diffusion-driven instabilities are derived. Two basic types of eigenvalues, real and complex, are described. Dispersion curves for both types of eigenvalues are plotted and their behavior is analyzed. The real case is related to the Turing instability, and the complex one corresponds to the wave instability. We emphasize the interesting feature that the wave instability in the hyperbolic equations occurs in two-variable systems, whereas in the parabolic case one needs three reaction-diffusion equations.

  12. A large deformation viscoelastic model for double-network hydrogels

    Science.gov (United States)

    Mao, Yunwei; Lin, Shaoting; Zhao, Xuanhe; Anand, Lallit

    2017-03-01

    We present a large deformation viscoelasticity model for recently synthesized double network hydrogels which consist of a covalently-crosslinked polyacrylamide network with long chains, and an ionically-crosslinked alginate network with short chains. Such double-network gels are highly stretchable and at the same time tough, because when stretched the crosslinks in the ionically-crosslinked alginate network rupture which results in distributed internal microdamage which dissipates a substantial amount of energy, while the configurational entropy of the covalently-crosslinked polyacrylamide network allows the gel to return to its original configuration after deformation. In addition to the large hysteresis during loading and unloading, these double network hydrogels also exhibit a substantial rate-sensitive response during loading, but exhibit almost no rate-sensitivity during unloading. These features of large hysteresis and asymmetric rate-sensitivity are quite different from the response of conventional hydrogels. We limit our attention to modeling the complex viscoelastic response of such hydrogels under isothermal conditions. Our model is restricted in the sense that we have limited our attention to conditions under which one might neglect any diffusion of the water in the hydrogel - as might occur when the gel has a uniform initial value of the concentration of water, and the mobility of the water molecules in the gel is low relative to the time scale of the mechanical deformation. We also do not attempt to model the final fracture of such double-network hydrogels.

  13. NTERACTION BETWEEN SURFACE CHARGE PHENOMENA AND MULTI-SPECIES DIFFUSION IN CEMENT BASED MATERIALS

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2008-01-01

    Measurements strongly indicate that the ‘inner’ surface of the microscopic structure of cement based materials has a fixed negative charge. This charge contributes to the formation of so-called electrical double layers. In the case of cement based materials the ionic species located in such layers...... are typically potassium -, sodium - and calcium ions. Due to the high specific surface area of hydrated cement, a large amount of ions can be located in theses double layers even if the surface charge is relatively low. The attraction force, caused by the fixed surface charge on ions located close to surfaces......, is one possible explanation for the observed low global diffusion rates in the pore system of positively charged ions compared to the negatively charged ones. Here it is of interest to simulate the multi ionic diffusion behavior when assigning positively charged ions a comparably lower diffusion constant...

  14. Alignment in double capture processes

    International Nuclear Information System (INIS)

    Moretto-Capelle, P.; Benhenni, M.; Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.

    1993-01-01

    The electron spectra emitted when a double capture occurs in N 7+ +He and Ne 8+ +He systems at 10 qkeV collisional energy, allow us to determine the angular distributions of the 3 ell 3 ell ' lines through a special spectra fitting procedure which includes interferences between neighbouring states. It is found that the doubly excited states populated in double capture processes are generally aligned

  15. Alignment in double capture processes

    Energy Technology Data Exchange (ETDEWEB)

    Moretto-Capelle, P.; Benhenni, M.; Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A. (IRSAMC, URA CNRS 770, Univ. Paul Sabatier, 118 rte de Narbonne, 31062 Toulouse Cedex (France))

    1993-06-05

    The electron spectra emitted when a double capture occurs in N[sup 7+]+He and Ne[sup 8+]+He systems at 10 qkeV collisional energy, allow us to determine the angular distributions of the 3[ell]3[ell] [prime] lines through a special spectra fitting procedure which includes interferences between neighbouring states. It is found that the doubly excited states populated in double capture processes are generally aligned.

  16. Methods of Mitigating Double Taxation

    OpenAIRE

    Lindhe, Tobias

    2002-01-01

    This paper presents a comprehensive overview of existing methods of mitigating double taxation of corporate income within a standard cost of capital model. Two of the most well-known and most utilized methods, the imputation and the split rate systems, do not mitigate double taxation in corporations where the marginal investment is financed with retained earnings. However, all methods are effective when the marginal investment is financed with new share issues. The corporate tax rate, fiscal ...

  17. Decades with four double triodes

    International Nuclear Information System (INIS)

    Wahl, R.

    1952-01-01

    Decades with four double triodes The described decade consists of four double triodes and four crystals germanium; which has the following characteristics: - Attack in negative impulses. - Sensitivity 12 volts ± 40 % for signals of 1 μs about. - Time of resolution 2,5 μs. - Voltage 250 v ± 40 %. - heating 6,3 v ± 40 %. - Tolerance on the values of the elements of installation 10%. (author) [fr

  18. Double layers above the aurora

    International Nuclear Information System (INIS)

    Temerin, M.; Mozer, F.S.

    1987-01-01

    Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through the shock can be several kV and is comparable to the total potential needed to produce auroral acceleration. Instabilities associated with the shock may generate obliquely propagating Alfven waves, which may accelerate electrons to produce flickering auroras. The flickering aurora provides evidence that the electrostatic shock may have large temporal fluctuations. The other kind of double layer is the small-amplitude double layer found in regions of upward flowing in beams, often in association with electrostatic ion cyclotron waves. The parallel and perpendicular electric fields in these structures are comparable in magnitude. The associated potentials are a few eV. Since many such double layers are found in regions of upward flowing ion beams, the combined potential drop through a set of these double layers can be substantial

  19. Global effects of double layers

    International Nuclear Information System (INIS)

    Raad, M.A.

    1984-12-01

    Locally the formation of an electrostatic double layer in a current carrying plasma leads to a direct acceleration of particles which may penetrate far into the surrounding medium. The potential across the double layer, giving this acceleration, must be maintained by the external system and is a basic parameter for the local to global coupling. The double layer potential is associated with an electric field parallel to the magnetic field. In general this leads to a magnetohydrodynamic relaxation of the surrounding medium providing the influx of energy which is dissipated by the double layer. The double layer potential is limited as is the maximum possible rate of energy influx. If the global response of the external medium can be represented by an external circuit and if an equivalent circuit element can be found to represent the double layer, for example a negative resistance for intermediate time scales, it is possible to give a description of the dynamics and stability of the whole system. (Author)

  20. Diffusion tensor optical coherence tomography

    Science.gov (United States)

    Marks, Daniel L.; Blackmon, Richard L.; Oldenburg, Amy L.

    2018-01-01

    In situ measurements of diffusive particle transport provide insight into tissue architecture, drug delivery, and cellular function. Analogous to diffusion-tensor magnetic resonance imaging (DT-MRI), where the anisotropic diffusion of water molecules is mapped on the millimeter scale to elucidate the fibrous structure of tissue, here we propose diffusion-tensor optical coherence tomography (DT-OCT) for measuring directional diffusivity and flow of optically scattering particles within tissue. Because DT-OCT is sensitive to the sub-resolution motion of Brownian particles as they are constrained by tissue macromolecules, it has the potential to quantify nanoporous anisotropic tissue structure at micrometer resolution as relevant to extracellular matrices, neurons, and capillaries. Here we derive the principles of DT-OCT, relating the detected optical signal from a minimum of six probe beams with the six unique diffusion tensor and three flow vector components. The optimal geometry of the probe beams is determined given a finite numerical aperture, and a high-speed hardware implementation is proposed. Finally, Monte Carlo simulations are employed to assess the ability of the proposed DT-OCT system to quantify anisotropic diffusion of nanoparticles in a collagen matrix, an extracellular constituent that is known to become highly aligned during tumor development.

  1. Macrolides for diffuse panbronchiolitis.

    Science.gov (United States)

    Lin, Xiufang; Lu, Jing; Yang, Ming; Dong, Bi Rong; Wu, Hong Mei

    2015-01-25

    Diffuse panbronchiolitis (DPB) is a chronic airways disease predominantly affecting East Asians. Macrolides, a class of antibiotics, have been used as the main treatment for DPB, based on evidence from retrospective and non-randomised studies. To assess the efficacy and safety of macrolides for DPB. We searched CENTRAL (2014, Issue 6), MEDLINE (1966 to July week 1, 2014), EMBASE (1974 to July 2014), Chinese Biomedical Literature Database (CBM) (1978 to July 2014), China National Knowledge Infrastructure (CNKI) (1974 to July 2014), KoreaMed (1997 to July 2014) and Database of Japana Centra Revuo Medicina (1983 to July 2014). Randomised controlled trials (RCTs) or quasi-RCTs assessing the effect of macrolides for DPB. Two review authors independently assessed study quality and subsequent risk of bias according to The Cochrane Collaboration's tool for assessing risk of bias. The primary outcomes were five-year survival rate, lung function and clinical response. We used risk ratios (RR) for individual trial results in the data analysis and measured all outcomes with 95% confidence intervals (CI). Only one RCT (19 participants) with significant methodological limitations was included in this review. It found that the computerised tomography images of all participants treated with a long-term, low-dose macrolide (erythromycin) improved from baseline, while the images of 71.4% of participants in the control group (with no treatment) worsened and 28.6% remained unchanged. Adverse effects were not reported. This review was previously published in 2010 and 2013. For this 2014 update, we identified no new trials for inclusion or exclusion. There is little evidence for macrolides in the treatment of DPB. We are therefore unable to make any new recommendations. It may be reasonable to use low-dose macrolides soon after diagnosis is made and to continue this treatment for at least six months, according to current guidelines.

  2. Moessbauer effect and vacancy diffusion

    International Nuclear Information System (INIS)

    Gunther, L.

    1976-01-01

    A dynamical theory of vacancy diffusion which was motivated by the need to explain recent experimental results for the Moessbauer spectra of Fe in Cu, Fe in Au and Fe in Al is presented. Diffusion in these systems is dominated by the vacancy mechanism, which involves strong correlations between successive jumps. The theory developed by Singwi and Sjoelander for the Moessbauer spectrum of a diffusing nucleus is therefore not applicable. The inverse of the normalized Moessbauer spectrum evaluated at zero frequency is introduced as a useful means of comparing experimental with theoretical spectral widths

  3. Simulation of multivariate diffusion bridges

    DEFF Research Database (Denmark)

    Bladt, Mogens; Finch, Samuel; Sørensen, Michael

    We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental role in simulation-based likelihood and Bayesian inference for stochastic differential equations. By a novel application of classical coupling methods, the new approach generalizes a previously...... proposed simulation method for one-dimensional bridges to the mulit-variate setting. First a method of simulating approzimate, but often very accurate, diffusion bridges is proposed. These approximate bridges are used as proposal for easily implementable MCMC algorithms that produce exact diffusion bridges...

  4. Self diffusion in isotopic fluid

    International Nuclear Information System (INIS)

    Tankeshwar, K.

    1991-01-01

    Expressions for the second and fourth frequency sum rules of the velocity auto-correlation function have been obtained for an isotopic fluid. These expressions and Mori memory function formalism have been used to study the influence of the particle mass and mole fraction on the self diffusion coefficient. Our results confirm the weak mass dependence of the self diffusion. The influence of the mole fraction of the light particles on the self diffusion constant has been found to increase for the larger particle mass. (author). 17 refs, 1 fig., 2 tabs

  5. Muon diffusion in noble metals

    International Nuclear Information System (INIS)

    Schillaci, M.E.; Bokema, C.; Heffner, R.H.; Hutson, R.L.; Leon, M.; Olsen, C.E.; Dodds, S.A.; MacLaughlin, D.E.; Richards, P.M.

    1983-01-01

    Diffusion-induced muon depolarization in dilute AgGd and AgEr were measured in the temperature range 200-700 K and have thereby determined the muon diffusion parameters in Ag. The diffusion parameters for μ + in Cu, Ag, and Au are compared with those of hydrogen. For Ag and Au, the μ + parameters are similar to those of hydrogen, whereas for Cu, the μ + parameters are much smaller. Lattice-activated tunneling and over-barrier hopping are investigated with computational models. 15 references, 1 figure, 2 tables

  6. Muon diffusion in noble metals

    International Nuclear Information System (INIS)

    Schillaci, M.E.; Boekema, C.; Heffner, R.H.; Hutson, R.L.; Leon, M.; Olsen, C.E.; Dodds, S.A.; MacLaughlin, D.E.; Richards, P.M.

    1982-01-01

    Diffusion-induced muon depolarization was measured in dilute AgGd and AgEr in the temperature range 200 to 700 0 K and have thereby determined the muon diffusion parameters in Ag. The diffusion parameters for μ + in Cu, Ag, and Au are compared with those of hydrogen. For Ag and Au, the μ + parameters are similar to those of hydrogen, whereas for Cu, the μ + parameters are much smaller. Lattice-activated tunneling and over-barrier hopping are investigated with computational models

  7. Genetics Home Reference: hereditary diffuse gastric cancer

    Science.gov (United States)

    ... Health Conditions Hereditary diffuse gastric cancer Hereditary diffuse gastric cancer Printable PDF Open All Close All Enable Javascript ... Diffuse Gastric Cancer MedlinePlus Encyclopedia: Gastric Cancer National Cancer ... Option Overview General Information from MedlinePlus ( ...

  8. Improved diffuser for augmenting a wind turbine

    Science.gov (United States)

    Foreman, K.M.; Gilbert, B.L.

    A diffuser for augmenting a wind turbine having means for energizing the boundary layer at several locations along the diffuser walls is improved by the addition of a short collar extending radially outward from the outlet of the diffuser.

  9. Identification of the primary motor cortex: value of T2 echo-planar imaging, diffusion-weighted imaging and quantitative apparent diffusion coefficient measurement at 3 T

    International Nuclear Information System (INIS)

    Dincer, Alp; Erzen, Canan; Oezyurt, Onur; Pamir, M.N.

    2010-01-01

    To investigate the primary motor cortex (PMC) concerning T2 shortening on T2 echo-planar imaging (EPI-T2) and the double-layer sign on diffusion-weighted imaging (DWI), and also to measure its apparent diffusion coefficient (ADC). 3-T MR DWI was performed in 134 adult volunteers and 64 patients. T2 shortening was graded as hypointense or isointense compared with the signal of the superior frontal cortex (SFC). The double-layer sign of the PMC was graded as present or absent. Both findings (T2 shortening and double-layer sign) were evaluated independently by two authors. ADC of the PMC and the SFC were calculated using manually selected ROIs. T2 shortening was found in 131 adults and 62 patients by author 1 and in 132 adults and 61 patients by author 2 (κ = 0.96 and 0.91). The double-layer sign was found in 131 adults and 61 patients by author 1 and in 127 adults and 58 patients by author 2 (κ = 0.94 and 0.91). ADC values of the PMC and the SFC were different for all subjects (p < 0.01). T2 shortening and/or the double-layer sign on 3-T MR can be used to locate the PMC. The difference in ADC values between PMC and SFC is a distinguishing feature. (orig.)

  10. System for tissue characterization using synchronous detection of diffuse reflectance

    International Nuclear Information System (INIS)

    Morales Lopez, Orestes M.; Stolik Isakina, Suren; La Rosa Vazquez, Jose Manuel de; Valor Reed, Alma

    2016-01-01

    The development of a system for the characterization of tissues optical properties in-vivo by synchronous detection of diffuse reflectance is presented. The system comprises an exploring probe with a linear spatial arrangement of optical fibers coupled to six lasers of 650 nm wavelength and a photodiode. The system also includes a preamplifier circuit for the photodiode, a driver for the amplitude modulation of the light signal of the lasers with optical power monitoring, a digital phase splitter for reference signal generation, an amplifying circuit with digitally switch able gain, a double phase demodulation circuit, an Arduino, and a control interface developed in LabVIEW. (Author)

  11. DNS: Diffuse scattering neutron time-of-flight spectrometer

    Directory of Open Access Journals (Sweden)

    Yixi Su

    2015-08-01

    Full Text Available DNS is a versatile diffuse scattering instrument with polarisation analysis operated by the Jülich Centre for Neutron Science (JCNS, Forschungszentrum Jülich GmbH, outstation at the Heinz Maier-Leibnitz Zentrum (MLZ. Compact design, a large double-focusing PG monochromator and a highly efficient supermirror-based polarizer provide a polarized neutron flux of about 107 n cm-2 s-1. DNS is used for the studies of highly frustrated spin systems, strongly correlated electrons, emergent functional materials and soft condensed matter.

  12. Cumulant expansions for measuring water exchange using diffusion MRI

    Science.gov (United States)

    Ning, Lipeng; Nilsson, Markus; Lasič, Samo; Westin, Carl-Fredrik; Rathi, Yogesh

    2018-02-01

    The rate of water exchange across cell membranes is a parameter of biological interest and can be measured by diffusion magnetic resonance imaging (dMRI). In this work, we investigate a stochastic model for the diffusion-and-exchange of water molecules. This model provides a general solution for the temporal evolution of dMRI signal using any type of gradient waveform, thereby generalizing the signal expressions for the Kärger model. Moreover, we also derive a general nth order cumulant expansion of the dMRI signal accounting for water exchange, which has not been explored in earlier studies. Based on this analytical expression, we compute the cumulant expansion for dMRI signals for the special case of single diffusion encoding (SDE) and double diffusion encoding (DDE) sequences. Our results provide a theoretical guideline on optimizing experimental parameters for SDE and DDE sequences, respectively. Moreover, we show that DDE signals are more sensitive to water exchange at short-time scale but provide less attenuation at long-time scale than SDE signals. Our theoretical analysis is also validated using Monte Carlo simulations on synthetic structures.

  13. Energy and variance budgets of a diffusive staircase with implications for heat flux scaling

    Science.gov (United States)

    Hieronymus, M.; Carpenter, J. R.

    2016-02-01

    Diffusive convection, the mode of double-diffusive convection that occur when both temperature and salinity increase with increasing depth, is commonplace throughout the high latitude oceans and diffusive staircases constitute an important heat transport process in the Arctic Ocean. Heat and buoyancy fluxes through these staircases are often estimated using flux laws deduced either from laboratory experiments, or from simplified energy or variance budgets. We have done direct numerical simulations of double-diffusive convection at a range of Rayleigh numbers and quantified the energy and variance budgets in detail. This allows us to compare the fluxes in our simulations to those derived using known flux laws and to quantify how well the simplified energy and variance budgets approximate the full budgets. The fluxes are found to agree well with earlier estimates at high Rayleigh numbers, but we find large deviations at low Rayleigh numbers. The close ties between the heat and buoyancy fluxes and the budgets of thermal variance and energy have been utilized to derive heat flux scaling laws in the field of thermal convection. The result is the so called GL-theory, which has been found to give accurate heat flux scaling laws in a very wide parameter range. Diffusive convection has many similarities to thermal convection and an extension of the GL-theory to diffusive convection is also presented and its predictions are compared to the results from our numerical simulations.

  14. Transverse single-file diffusion and enhanced longitudinal diffusion near a subcritical bifurcation

    Science.gov (United States)

    Dessup, Tommy; Coste, Christophe; Saint Jean, Michel

    2018-05-01

    A quasi-one-dimensional system of repelling particles undergoes a configurational phase transition when the transverse confining potential decreases. Below a threshold, it becomes energetically favorable for the system to adopt one of two staggered raw patterns, symmetric with respect to the system axis. This transition is a subcritical pitchfork bifurcation for short range interactions. As a consequence, the homogeneous zigzag pattern is unstable in a finite zigzag amplitude range [hC 1,hC 2] . We exhibit strong qualitative effects of the subcriticality on the thermal motions of the particles. When the zigzag amplitude is close enough to the limits hC 1 and hC 2, a transverse vibrational soft mode occurs which induces a strongly subdiffusive behavior of the transverse fluctuations, similar to single-file diffusion. On the contrary, the longitudinal fluctuations are enhanced, with a diffusion coefficient which is more than doubled. Conversely, a simple measurement of the thermal fluctuations allows a precise determination of the bifurcation thresholds.

  15. Diffuse-charge dynamics of ionic liquids in electrochemical systems.

    Science.gov (United States)

    Zhao, Hui

    2011-11-01

    We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our simple scaling analysis suggests that the length scale √(λ*(D)l*(c)) accurately characterizes the double-layer structure of ionic liquids with strong electrostatic correlations where l*(c) is the electrostatic correlation length (in contrast, the Debye screening length λ*(D) is the primary double-layer length for electrolytes) and the response time of λ(D)(*3/2)L*/(D*l(c)(1/2)) (not λ*(D)L*/D* that is the primary charging time of electrolytes) is the correct charging time scale of ionic liquids with strong electrostatic correlations where D* is the diffusivity and L* is the separation length of the cell. With these two new scales, data of both electric potential versus distance from the electrode and the total diffuse charge versus time collapse onto each individual master curve in the presence of strong electrostatic correlations. In addition, the dependance of the total diffuse charge on steric effects, short-range correlations, and driving voltages is thoroughly examined. The results from the asymptotic analysis are compared favorably with those from full numerical simulations. Finally, the absorption of excess salt by the double layer creates a depletion region outside the double layer. Such salt depletion may bring a correction to the leading order terms and break down the weakly nonlinear

  16. Atmospheric turbulence and diffusion research

    International Nuclear Information System (INIS)

    Hosker, R.P. Jr.

    1993-01-01

    The Atmospheric Turbulence and Diffusion Division (well known in the atmospheric dispersion community as the Atmospheric Turbulence and Diffusion Laboratory, ATDL) is one of several field facilities of NOAAs Air Resources Laboratory, headquartered in Silver Spring, Maryland. The laboratory conducts research on matters of atmospheric diffusion and turbulent exchange, concerning air quality. ATDD focuses attention on the physics of the lower atmosphere, with special emphasis on the processes contributing to atmospheric transport, dispersion, deposition, and air-surface exchange, and on the development of predictive capabilities using the results of this research. Research is directed toward issues of national and global importance related to the missions of DOE, to DOE's Oak Ridge Field Office, and to NOAA. The program is divided into four major projects: plume transport and diffusion in the planetary boundary layer, complex topography, canopy micrometeorology, and air-surface exchange

  17. Diffusion mechanisms in intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Larikov, L N [ANU, Inst. Metallofiziki, Kiev (Ukraine)

    1992-08-01

    Recent research aimed at the identification of the principal mechanisms of diffusion in intermetallics is reviewed. In particular, attention is given to the effect of the type of interatomic bond on the contribution of different mechanisms to diffusion in ordered metallic compounds. Results of an analysis of experimental determinations of diffusion coefficients D(A) and D(B) in binary intermetallics (CuZn, Cu3Sn, AuCd, AgZn, AgMg, InSb, GaSb, AlSb, Fe3Al, FeAl, FeAl3, Ni3Al, Ni3Nb, FeSn, FeSn2, Ni3Sn2, Ni3Sn4, Co3Sn2, CoSn, CoSn2, and CoGa) are presented, and it is shown that the D(A)/D(B) ratio differs substantially for different diffusion mechanisms. 60 refs.

  18. Diffusion of single oxidation pond

    Directory of Open Access Journals (Sweden)

    Song Ruo-Yuan

    2016-01-01

    Full Text Available The hydraulic characteristic of an oxidation pond was studied by the tracer experiment, and an empirical formula of Peclet number was obtained, which can be well applied to the model of plug flow reactor with longitudinal diffusion.

  19. Computational Diffusion MRI : MICCAI Workshop

    CERN Document Server

    Grussu, Francesco; Ning, Lipeng; Tax, Chantal; Veraart, Jelle

    2018-01-01

    This volume presents the latest developments in the highly active and rapidly growing field of diffusion MRI. The reader will find numerous contributions covering a broad range of topics, from the mathematical foundations of the diffusion process and signal generation, to new computational methods and estimation techniques for the in-vivo recovery of microstructural and connectivity features, as well as frontline applications in neuroscience research and clinical practice. These proceedings contain the papers presented at the 2017 MICCAI Workshop on Computational Diffusion MRI (CDMRI’17) held in Québec, Canada on September 10, 2017, sharing new perspectives on the most recent research challenges for those currently working in the field, but also offering a valuable starting point for anyone interested in learning computational techniques in diffusion MRI. This book includes rigorous mathematical derivations, a large number of rich, full-colour visualisations and clinically relevant results. As such, it wil...

  20. Diffusion from cylindrical waste forms

    International Nuclear Information System (INIS)

    Thomas, G.F.

    1985-05-01

    The diffusion of a single component material from a finite cylindrical waste form, initially containing a uniform concentration of the material, is investigated. Under the condition that the cylinder is maintained in a well-stirred bath, expressions for the fractional inventory leached and the leach rate are derived with allowance for the possible permanent immobilization of the diffusant through its decay to a stable product and/or its irreversible reaction with the waste form matrix. The usefulness of the reported results in nuclear waste disposal applications is emphasized. The results reported herein are related to those previously derived at Oak Ridge National Laboratory by Bell and Nestor. A numerical scheme involving the partial decoupling of nested infinite summations and the use of rapidly converging rational approximants is recommended for the efficient implementation of the expressions derived to obtain reliable estimates of the bulk diffusion constant and the rate constant describing the diffusant-waste form interaction from laboratory data

  1. Diffusion coefficient for anomalous transport

    International Nuclear Information System (INIS)

    1986-01-01

    A report on the progress towards the goal of estimating the diffusion coefficient for anomalous transport is given. The gyrokinetic theory is used to identify different time and length scale inherent to the characteristics of plasmas which exhibit anomalous transport

  2. Diffusion formation and psychiatric diseases

    International Nuclear Information System (INIS)

    Reith, W.; Kulikovski, J.

    2015-01-01

    The basic principle behind diffusion is Brownian motion. The diffusion parameters obtained in a clinical association provide information on the spatial distribution of water molecule mobility and, therefore, evidence of the morphological integrity of the white and grey matters of the brain. In recent years functional magnetic resonance imaging (fMRI) could contribute to obtaining a detailed understanding of the cortical and subcortical cerebral networks. Diffusion tensor imaging (DTI) investigations can demonstrate the extent of anisotropy and the fiber pathways in so-called parametric images. For example, in Alzheimer's disease DTI reveals a reduced structural connectivity between the posterior cingulum and the hippocampus. This article shows examples of the application of diffusion-weighted imaging (DWI) in psychiatric disorders. (orig.) [de

  3. First-Principles Investigation of Adsorption and Diffusion of Ions on Pristine, Defective and B-doped Graphene

    Directory of Open Access Journals (Sweden)

    Wei Wan

    2015-09-01

    Full Text Available We performed first-principles calculations to reveal the possibility of applying pristine, defective, and B-doped graphene in feasible negative electrode materials of ion batteries. It is found that the barriers for ions are too high to diffuse through the original graphene, however the reduced barriers are obtained by introducing defects (single vacancy, double vacancy, Stone–Wales defect in the graphene. Among the three types of defects, the systems with a double vacancy could provide the lowest barriers of 1.49 and 6.08 eV for Li and Na, respectively. Furthermore, for all kinds of B-doped graphene with the vacancy, the systems with a double vacancy could also provide the lowest adsorption energies and diffusion barriers. Therefore, undoped and B-doped graphene with a double vacancy turn out to be the most promising candidates that can replace pristine graphene for anode materials in ion batteries.

  4. Congenital double-double lip: A rare case report

    Directory of Open Access Journals (Sweden)

    Swati Phore

    2017-01-01

    Full Text Available A double lip is a rare anomaly characterized by a horizontal fold of redundant mucosal tissue that is situated proximal to the vermilion border. It may be either congenital or acquired and has no gender or race predilection. It occurs most often in the upper lip, although both upper and lower lips are occasionally involved. Surgical intervention (simple excision produces good functional and cosmetic results. In this report, a case of a nonsyndromic congenital maxillary double upper lip and lower lip, both are described. Double lip is of special interest in dental profession as a dental surgeon is normally the first one to diagnose this rare and uncommon condition. Authors hereby discuss a very rare condition in which both upper and lower lips are involved.

  5. Decades with four double triodes; Decades a quatre doubles triodes

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, R [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1952-07-01

    Decades with four double triodes The described decade consists of four double triodes and four crystals germanium; which has the following characteristics: - Attack in negative impulses. - Sensitivity 12 volts {+-} 40 % for signals of 1 {mu}s about. - Time of resolution 2,5 {mu}s. - Voltage 250 v {+-} 40 %. - heating 6,3 v {+-} 40 %. - Tolerance on the values of the elements of installation 10%. (author) [French] La decade decrite comprend quatre doubles triodes et quatre cristaux germanium; elle a les caracteristiques suivantes: - Attaque en impulsions negatives. - Sensiblite 12 volts {+-} 40 % pour des signaux de 1 {mu}s environ. - Temps de resolution 2,5 {mu}s. - Alimentation 250 v {+-} 40 %. - Chauffage 6,3 v {+-} 40 %. - Tolerance sur les valeurs des elements de montage l0 %. (auteur)

  6. Anomalous diffusion in chaotic scattering

    International Nuclear Information System (INIS)

    Srokowski, T.; Ploszajczak, M.

    1994-01-01

    The anomalous diffusion is found for peripheral collision of atomic nuclei described in the framework of the molecular dynamics. Similarly as for chaotic billiards, the long free paths are the source of the long-time correlations and the anomalous diffusion. Consequences of this finding for the energy dissipation in deep-inelastic collisions and the dynamics of fission in hot nuclei are discussed (authors). 30 refs., 2 figs

  7. Diffusion processes and memory effects

    International Nuclear Information System (INIS)

    Mokshin, Anatolii V; Yulmetyev, Renat M; Haenggi, Peter

    2005-01-01

    We report the results of the numerical estimation of statistical memory effects in diffusion for two various systems: Lennard-Jones fluids and the model of the Brownian particle in a one-dimensional harmonic lattice. We have found the relation between the diffusion coefficient and the non-Markovity parameter, which is linear for the Lennard-Jones systems in liquid state. The relation between the memory measure and the excess entropy is also discussed here

  8. Reliability Modeling of Double Beam Bridge Crane

    Science.gov (United States)

    Han, Zhu; Tong, Yifei; Luan, Jiahui; Xiangdong, Li

    2018-05-01

    This paper briefly described the structure of double beam bridge crane and the basic parameters of double beam bridge crane are defined. According to the structure and system division of double beam bridge crane, the reliability architecture of double beam bridge crane system is proposed, and the reliability mathematical model is constructed.

  9. Diffusion through statically compacted clay

    International Nuclear Information System (INIS)

    Ho, C.L.; Shebl, M.A.A.

    1994-01-01

    This paper presents experimental work on the effect of compaction on contaminant flow through clay liners. The experimental program included evaluation of soil properties, compaction, permeability and solute diffusion. A permeameter was built of non reactive materials to test samples compacted at different water contents and compactive efforts. The flow of a permeating solute, LiCl, was monitored. Effluent samples were collected for solute concentration measurements. The concentrations were measured by performing atomic adsorption tests. The analyzed results showed different diffusion characteristics when compaction conditions changed. At each compactive effort, permeability decreased as molding water content increased. Consequently, transit time (measured at relative concentration 50%) increased and diffusivity decreased. As compactive effort increased for soils compacted dry of optimum, permeability and diffusion decreased. On the other hand, as compactive effort increased for soils compacted wet of optimum, permeability and diffusivity increased. Tortuosity factor was indirectly measured from the diffusion and retardation rate. Tortuosity factor also decreased as placement water content was increased from dry of optimum to wet of optimum. Then decreases were more pronounced for low compactive effort tests. 27 refs., 7 figs., 5 tabs

  10. Diffusion MRI findings in phenylketonuria

    Energy Technology Data Exchange (ETDEWEB)

    Sener, R.N. [Dept. of Radiology, Ege Univ. Hospital, Izmir (Turkey)

    2003-12-01

    Two patients with phenylketonuria were studied who were under dietary control since infancy, and who were mentally normal. Diffusion MRI was obtained using a spin-echo, echo-planar sequence with a gradient strength of 30 mT/m at 1.5 T. A trace sequence (TR=5700 ms, and TE=139 ms) was used, acquired in 22 s. Heavily diffusion-weighted (b=1000 mm{sup 2}/s) images, and the apparent diffusion coefficient (ADC) values from automatically generated ADC maps were studied. There were two different patterns in these two patients, restricted and increased diffusion patterns. Restricted diffusion pattern consisted of high-signal on b=1000 s/mm{sup 2} images with low ADC values ranging from 0.46 to 0.57 x 10{sup -3} mm{sup 2}/s. Increased diffusion pattern consisted of normal b=1000 s/mm{sup 2} images with high ADC values ranging from 1.37 to 1.63 x 10{sup -3} mm{sup 2}/s. It is likely that these values reflected presence of two different histopathological changes in phenylketonuria or reflected different stages of the same disease. (orig.)

  11. Diffusion MRI findings in phenylketonuria

    International Nuclear Information System (INIS)

    Sener, R.N.

    2003-01-01

    Two patients with phenylketonuria were studied who were under dietary control since infancy, and who were mentally normal. Diffusion MRI was obtained using a spin-echo, echo-planar sequence with a gradient strength of 30 mT/m at 1.5 T. A trace sequence (TR=5700 ms, and TE=139 ms) was used, acquired in 22 s. Heavily diffusion-weighted (b=1000 mm 2 /s) images, and the apparent diffusion coefficient (ADC) values from automatically generated ADC maps were studied. There were two different patterns in these two patients, restricted and increased diffusion patterns. Restricted diffusion pattern consisted of high-signal on b=1000 s/mm 2 images with low ADC values ranging from 0.46 to 0.57 x 10 -3 mm 2 /s. Increased diffusion pattern consisted of normal b=1000 s/mm 2 images with high ADC values ranging from 1.37 to 1.63 x 10 -3 mm 2 /s. It is likely that these values reflected presence of two different histopathological changes in phenylketonuria or reflected different stages of the same disease. (orig.)

  12. Atmospheric diffusion of large clouds

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, T. V. [Univ. of California, Lawrence Radiation Lab., Livermore, California (United States)

    1967-07-01

    Clouds of pollutants travel within a coordinate system that is fixed to the earth's surface, and they diffuse and grow within a coordinate system fixed to the cloud's center. This paper discusses an approach to predicting the cloud's properties, within the latter coordinate system, on space scales of a few hundred meters to a few hundred kilometers and for time periods of a few days. A numerical cloud diffusion model is presented which starts with a cloud placed arbitrarily within the troposphere. Similarity theories of atmospheric turbulence are used to predict the horizontal diffusivity as a function of initial cloud size, turbulent atmospheric dissipation, and time. Vertical diffusivity is input as a function of time and height. Therefore, diurnal variations of turbulent diffusion in the boundary layer and effects of temperature inversions, etc. can be modeled. Nondiffusive cloud depletion mechanisms, such as dry deposition, washout, and radioactive decay, are also a part of this numerical model. An effluent cloud, produced by a reactor run at the Nuclear Rocket Development Station, Nevada, is discussed in this paper. Measurements on this cloud, for a period of two days, are compared to calculations with the above numerical cloud diffusion model. In general, there is agreement. within a factor of two, for airborne concentrations, cloud horizontal area, surface air concentrations, and dry deposition as airborne concentration decreased by seven orders of magnitude during the two-day period. (author)

  13. Diffusion, confusion and functional MRI

    International Nuclear Information System (INIS)

    Le Bihan, Denis

    2012-01-01

    Diffusion MRI has been introduced in 1985 and has had a very successful life on its own. While it has become a standard for imaging stroke and white matter disorders, the borders between diffusion MRI and the general field of fMRI have always remained fuzzy. First, diffusion MRI has been used to obtain images of brain function, based on the idea that diffusion MRI could also be made sensitive to blood flow, through the intra-voxel incoherent motion (IVIM) concept. Second, the IVIM concept helped better understand the contribution from different vasculature components to the BOLD fMRI signal. Third, it has been shown recently that a genuine fMRI signal can be obtained with diffusion MRI. This 'DfMRI' signal is notably different from the BOLD fMRI signal, especially for its much faster response to brain activation both at onset and offset, which points out to structural changes in the neural tissues, perhaps such as cell swelling, occurring in activated neural tissue. This short article reviews the major steps which have paved the way for this exciting development, underlying how technical progress with MRI equipment has each time been instrumental to expand the horizon of diffusion MRI toward the field of fMRI. (authors)

  14. Lead diffusion in monazite; Diffusion du plomb dans la monazite

    Energy Technology Data Exchange (ETDEWEB)

    Gardes, E

    2006-06-15

    Proper knowledge of the diffusion rates of lead in monazite is necessary to understand the U-Th-Pb age anomalies of this mineral, which is one of the most used in geochronology after zircon. Diffusion experiments were performed in NdPO{sub 4} monocrystals and in Nd{sub 0.66}Ca{sub 0.17}Th{sub 0.17}PO{sub 4} polycrystals from Nd{sub 0.66}Pb{sub 0.17}Th{sub 0.17}PO{sub 4} thin films to investigate Pb{sup 2+} + Th{sup 4+} {r_reversible} 2 Nd{sup 3+} and Pb{sup 2+} {r_reversible} Ca{sup 2+} exchanges. Diffusion annealings were run between 1200 and 1500 Celsius degrees, at room pressure, for durations ranging from one hour to one month. The diffusion profiles were analysed using TEM (transmission electronic microscopy) and RBS (Rutherford backscattering spectroscopy). The diffusivities extracted for Pb{sup 2+} + Th{sup 4+} {r_reversible} 2 Nd{sup 3+} exchange follow an Arrhenius law with parameters E equals 509 {+-} 24 kJ mol{sup -1} and log(D{sub 0} (m{sup 2}s{sup -1})) equals -3.41 {+-} 0.77. Preliminary data for Pb{sup 2+} {r_reversible} Ca{sup 2+} exchange are in agreement with this result. The extrapolation of our data to crustal temperatures yields very slow diffusivities. For instance, the time necessary for a 50 {mu}m grain to lose all of its lead at 800 Celsius degrees is greater than the age of the Earth. From these results and other evidence from the literature, we conclude that most of the perturbations in U-Th-Pb ages of monazite cannot be attributed to lead diffusion, but rather to interactions with fluids. (author)

  15. Prognostic impact of concurrent MYC and BCL6 rearrangements and expression in de novo diffuse large B-cell lymphoma

    DEFF Research Database (Denmark)

    Ye, Qing; Xu-Monette, Zijun Y; Tzankov, Alexandar

    2016-01-01

    Double-hit B-cell lymphoma is a common designation for a group of tumors characterized by concurrent translocations of MYC and BCL2, BCL6, or other genes. The prognosis of concurrent MYC and BCL6 translocations is not well known. In this study, we assessed rearrangements and expression of MYC, BCL2...... frequent in activated B-cell like diffuse large B-cell lymphoma). In summary, diffuse large B-cell lymphoma patients with either MYC/BCL6 rearrangements or MYC/BCL6 co-expression did not always have poorer prognosis; MYC expression levels should be evaluated simultaneously; and double-hit B-cell lymphoma...

  16. Alternate Double Single Track Lines

    Energy Technology Data Exchange (ETDEWEB)

    Moraga Contreras, P.; Grande Andrade, Z.; Castillo Ron, E.

    2016-07-01

    The paper discusses the advantages and shortcomings of alternate double single track (ADST) lines with respect to double track lines for high speed lines. ADST lines consists of sequences of double and single track segments optimally selected in order to reduce the construction and maintenance costs of railway lines and to optimize the timetables used to satisfy a given demand. The single tracks are selected to coincide with expensive segments (tunnels and viaducts) and the double tracks are chosen to coincide with flat areas and only where they are necessary. At the same time, departure times are adjusted for trains to cross at the cheap double track segments. This alternative can be used for new lines and also for existing conventional lines where some new tracks are to be constructed to reduce travel time (increase speed). The ADST proposal is illustrated with some examples of both types (new lines and where conventional lines exist), including the Palencia-Santander, the Santiago-Valparaíso-Viña del Mar and the Dublin-Belfast lines, where very important reductions (90 %) are obtained, especially where a railway infrastructure already exist. (Author)

  17. Synthesis and charge storage properties of double-layered NiSi nanocrystals

    International Nuclear Information System (INIS)

    Yoon, Jong-Hwan

    2010-01-01

    Based on bidirectional diffusion of Ni atoms, double-layered nickel silicide (NiSi) nanocrystals (NCs) for multilevel charge storage were fabricated, and their charge storage properties were examined. The double layer was produced by long-term thermal annealing (for 4 h at 900 o C) of a sandwich structure comprised of a thin Ni film of 0.3 nm sandwiched between two silicon-rich oxide (SiO 1.36 ) layers. Transmission electron microscopic image clearly exhibits a distinct NiSi nanocrystal double layer with a gap of about 7 nm between the mean positions of particle distribution in each NC layer. Capacitance-voltage measurements on the metal/oxide/semiconductor (MOS) capacitors with the double-layered NiSi nanocrystals are shown to have the apparent two plateaus of charge storage, the large memory window of about 9 V and the improved charge retention stability.

  18. On the physics of relativistic double layers

    International Nuclear Information System (INIS)

    Carlqvist, P.

    1982-06-01

    A model of a strong, time-independent, and relativistic double layer is studied. Besides double layers having the electric field parallel to the current the model also describes a certain type of oblique double layers. The 'Langmuir condition' (ratio of ion current density to electron current density) as well as an expression for the potential drop of the double layer are derived. Furthermore, the distribution of charged particles, electric field, and potential within the double layer are clarified and discussed. It is found that the properties of relativistic double layers differ substantially from the properties of corresponding non-relativistic double layers. (Author)

  19. Analytical drift-current threshold voltage model of long-channel double-gate MOSFETs

    International Nuclear Information System (INIS)

    Shih, Chun-Hsing; Wang, Jhong-Sheng

    2009-01-01

    This paper presents a new, physical threshold voltage model to solve the ambiguity in determining the threshold voltage of double-gate (DG) MOSFETs. To avoid the difficulties of the conventional 2ψ B model in nearly undoped DG MOSFETs, this study proposes to define the on–off switching based on the actual roles of the drift and diffusion components in the total drain current. The drift current strongly enhances beyond the threshold voltage, while the diffusion current plays a major role in the subthreshold. The threshold voltage is defined as the drift component that exceeds the diffusion counterpart. From the solutions of Poisson's equation, the drift and diffusion currents of DG MOSFETs are separately formulated to derive the analytical expressions of the threshold voltage and associated threshold current. This model provides a comprehensive description of the switching behavior of DG MOSFET devices, and offers a physical onset threshold current to determine the threshold voltage in practical extraction

  20. Drug diffusion across skin with diffusivity spatially modulated

    Science.gov (United States)

    Montoya Arroyave, Isabel

    2014-05-01

    A diffusion and delivery model of a drug across the skin with diffusivity spatially modulated is formulated and solved analytically using computer algebra. The model is developed using one-dimensional diffusion equation with a diffusivity which is a function of position in the skin; with an initial condition which is describing that the drug is initially contained inside a therapeutic patch; with a boundary condition according to which the change in concentration in the patch is minimal, such that assumption of zero flux at the patch-skin interface is valid; and with other boundary condition according to which the microcirculation in the capillaries just below the dermis carries the drug molecules away from the site at a very fast rate, maintaining the inner concentration at 0. The model is solved analytically by the method of the Laplace transform, with Bromwich integral and residue theorem. The concentration profile of the drug in the skin is expressed as an infinite series of Bessel functions. The corresponding total amount of delivered drug is expressed as an infinite series of decreasing exponentials. Also, the corresponding effective time for the therapeutic patch is determined. All computations were performed using computer algebra software, specifically Maple. The analytical results obtained are important for understanding and improving currentapplications of therapeutic patches. For future research it is interesting to consider more general models of spatial modulation of the diffusivity and the possible application of other computer algebra software such as Mathematica and Maxima.

  1. The double Brewster angle effect

    Science.gov (United States)

    Thirion-Lefevre, Laetitia; Guinvarc'h, Régis

    2018-01-01

    The Double Brewster angle effect (DBE) is an extension of the Brewster angle to double reflection on two orthogonal dielectric surfaces. It results from the combination of two pseudo-Brewster angles occurring in complementary incidence angles domains. It can be observed for a large range of incidence angles provided that double bounces mechanism is present. As a consequence of this effect, we show that the reflection coefficient at VV polarization can be at least 10 dB lower than the reflection coefficient at HH polarization over a wide range of incidence angle - typically from 20 to 70∘. It is experimentally demonstrated using a Synthetic Aperture Radar (SAR) image that this effect can be seen on buildings and forests. For large buildings, the difference can reach more than 20 dB. xml:lang="fr"

  2. Double photoionisation spectra of molecules

    CERN Document Server

    Eland, John

    2017-01-01

    This book contains spectra of the doubly charged positive ions (dications) of some 75 molecules, including the major constituents of terrestrial and planetary atmospheres and prototypes of major chemical groups. It is intended to be a new resource for research in all areas of molecular spectroscopy involving high energy environments, both terrestrial and extra-terrestrial. All the spectra have been produced by photoionisation using laboratory lamps or synchrotron radiation and have been measured using the magnetic bottle time-of-flight technique by coincidence detection of correlated electron pairs. Full references to published work on the same species are given, though for several molecules these are the first published spectra. Double ionisation energies are listed and discussed in relation to the molecular electronic structure of the molecules. A full introduction to the field of molecular double ionisation is included and the mechanisms by which double photoionisation can occur are examined in detail. A p...

  3. Double-polarizating scanning radiometer

    International Nuclear Information System (INIS)

    Mishev, D.N.; Nazyrski, T.G.

    1986-01-01

    The double-polarizating single-channel scanning radiometer comprises the following serial connected parts: a scanning double-polarizating aerial, a block for polarization separation, a radiometer receiver, an analog-to-digit converter and an information flow forming block. The low frequency input of the radiometer receiver is connected with a control block, which is also connected with a first bus of a microprocessor, the second bus of which is connected with the A-D converter. The control input of the scanning double-polarizating aerial is connected with the first microprocessor bus. The control inputs of the block for polarization separation are linked by an electronic switch with the output of the forming block, the input of which is connected to the first input of the control block. The control inputs of the block for polarization separation are connected with the second and the third input of the information flow forming block. 2 cls

  4. Double-plug seismic connector

    International Nuclear Information System (INIS)

    Annoot, I.R.

    1984-01-01

    The double-plug seismic electric connector comprises an elongated insulating body. A male connector plug is at one end of the body and a female connector plug is at the opposite end of the body. Each plug has a pair of male and female contacts. A pair of spaced axial conductors is embedded within the insulating body for interconnecting the opposite male and female contacts. The inner end of a double-wire cable is embedded within the insulating body and each wire inner end is connected to one of the conductors

  5. Identification of the Diffusion Parameter in Nonlocal Steady Diffusion Problems

    Energy Technology Data Exchange (ETDEWEB)

    D’Elia, M., E-mail: mdelia@fsu.edu, E-mail: mdelia@sandia.gov [Sandia National Laboratories (United States); Gunzburger, M. [Florida State University (United States)

    2016-04-15

    The problem of identifying the diffusion parameter appearing in a nonlocal steady diffusion equation is considered. The identification problem is formulated as an optimal control problem having a matching functional as the objective of the control and the parameter function as the control variable. The analysis makes use of a nonlocal vector calculus that allows one to define a variational formulation of the nonlocal problem. In a manner analogous to the local partial differential equations counterpart, we demonstrate, for certain kernel functions, the existence of at least one optimal solution in the space of admissible parameters. We introduce a Galerkin finite element discretization of the optimal control problem and derive a priori error estimates for the approximate state and control variables. Using one-dimensional numerical experiments, we illustrate the theoretical results and show that by using nonlocal models it is possible to estimate non-smooth and discontinuous diffusion parameters.

  6. Investigation of soot formation and temperature field in laminar diffusion flames of LPG-air mixture

    Energy Technology Data Exchange (ETDEWEB)

    Shahad, Haroun A.K.; Mohammed, Yassar K.A. [Babylon Univ., Dept. of Mechanical Engineering, Babylon (Israel)

    2000-11-01

    Soot formation and burnout were studied at atmospheric pressure in co-flowing, axisymmetric buoyant laminar diffusion flames and double flames of liquefied petroleum gases (LPG)-air mixtures. In diffusion flames, two different fuel flow rates were examined. In double flames, three different primary air flow rates were examined. A soot sampling probe and a thermocouple were used to measure the local soot mass concentration and flame temperature, respectively. Flame residence time was predicted using a uniformly accelerated motion model as function of axial distance of the flame. The increase of primary air flow rate was found to suppress the energy transfer from the annular region, at which the soot is produced, to the flame axis. The time required to initiate soot formation at the flame axis becomes longer as the primary air is increased. The trend rate of soot formation was found to be similar along the flame axis in all tested diffusion flames. The increase of primary air by 10% of the stoichiometric air requirement of the fuel results in a 70% reduction in maximum soot concentration. The final exhaust of soot, which is determined by the net effect of soot formation and burnout, is much lower in double flames than that in diffusion flames. (Author)

  7. Evaluation of diffuse-illumination holographic cinematography in a flutter cascade

    Science.gov (United States)

    Decker, A. J.

    1986-01-01

    Since 1979, the Lewis Research Center has examined holographic cinematography for three-dimensional flow visualization. The Nd:YAG lasers used were Q-switched, double-pulsed, and frequency-doubled, operating at 20 pulses per second. The primary subjects for flow visualization were the shock waves produced in two flutter cascades. Flow visualization was by diffuse-illumination, double-exposure, and holographic interferometry. The performances of the lasers, holography, and diffuse-illumination interferometry are evaluated in single-window wind tunnels. The fringe-contrast factor is used to evaluate the results. The effects of turbulence on shock-wave visualization in a transonic flow are discussed. The depth of field for visualization of a turbulent structure is demonstrated to be a measure of the relative density and scale of that structure. Other items discussed are the holographic emulsion, tests of coherence and polarization, effects of windows and diffusers, hologram bleaching, laser configurations, influence and handling of specular reflections, modes of fringe localization, noise sources, and coherence requirements as a function of the pulse energy. Holography and diffuse illumination interferometry are also reviewed.

  8. Diffuse and vascular hepatic diseases; Diffuse und vaskulaere Lebererkrankungen

    Energy Technology Data Exchange (ETDEWEB)

    Kreimeyer, S.; Grenacher, L. [Universitaetsklinikum Heidelberg, Abteilung Diagnostische und Interventionelle Radiologie, Heidelberg (Germany)

    2011-08-15

    In addition to focal liver lesions, diffuse and vascular disorders of the liver represent a wide spectrum of liver diseases which are from the radiological point of view often difficult or nearly impossible to diagnose. Classical diagnostic methods are computed tomography and magnetic resonance imaging in addition to ultrasound. Diffuse parenchymal damage caused by diseases of various etiologies is therefore difficult to evaluate because it often lacks characteristic morphological features. For hepatic steatosis, hemochromatosis/siderosis as an example of a diffuse storage disease and sarcoidosis and candidiasis as infectious/inflammatory diseases, an image-based diagnosis is appropriate in some cases. For most diffuse liver diseases, however only nonspecific changes are visualized. Vascular pathologies of the liver, such as the Budd-Chiari syndrome and portal vein thrombosis, however, can usually be diagnosed very clearly using radiology and there is also a very effective interventional radiological treatment. Chronic diseases very often culminate in liver cirrhosis which is highly associated with an increased risk of liver cancer. (orig.) [German] Neben den fokalen Leberlaesionen stellen diffuse und vaskulaere Lebererkrankungen ein weites Spektrum an Erkrankungen der Leber dar, die radiologisch oft schwer oder gar nicht diagnostizierbar sind. Klassische diagnostische Verfahren sind dabei neben dem Ultraschall die Computertomographie und die Magnetresonanztomographie. Diffuse Parenchymschaeden, bedingt durch Erkrankungen unterschiedlichster Aetiologie, sind deshalb schwierig evaluierbar, weil haeufig charakteristische bildmorphologische Merkmale fehlen. Die Steatosis hepatis, die Haemochromatose/Siderose als Beispiel der Speicherkrankheiten sowie die Sarkoidose und die Candidose als infektioes-entzuendliche Erkrankungen sind einer bildbasierten Diagnosestellung z. T. zugaenglich, bei den meisten diffusen Lebererkrankungen jedoch zeigen sich lediglich unspezifische

  9. Gaseous diffusion -- the enrichment workhorse

    International Nuclear Information System (INIS)

    Shoemaker, J.E. Jr.

    1984-01-01

    Construction of the first large-scale gaseous diffusion facility was started as part of the Manhattan Project in Oak Ridge, Tennessee, in 1943. This facility, code named ''K-25,'' began operation in January 1945 and was fully on stream by September 1945. Four additional process buildings were later added in Oak Ridge as the demand for enriched uranium escalated. New gaseous diffusion plants were constructed at Paducah, Kentucky, and Portsmouth, Ohio, during this period. The three gaseous diffusion plants were the ''workhorses'' which provided the entire enriched uranium demand for the United States during the 1950s and 1960s. As the demand for enriched uranium for military purposes decreased during the early 1960s, power to the diffusion plants was curtailed to reduce production. During the 1960s, as plans for the nuclear power industry were formulated, the role of the diffusion plants gradually changed from providing highly-enriched uranium for the military to providing low-enriched uranium for power reactors

  10. Radionuclide diffusion in soils. III

    International Nuclear Information System (INIS)

    Cipakova, A.; Szabova, T.

    1988-01-01

    Samples were taken of five soil types for determining diffusion coefficients, namely chernozem, illimerized brown soil, degraded chernozem, gleizated brown soil and heavy loamy brown soil. 5 layers of soil having a thickness of 1 cm each were placed in diffusion columns. 20 ml of water with 0.45 MBq 85 Sr of distilled water was poured over the columns. 10 ml of distilled water was poured over the columns every 5 days for monitoring the effect of the amount of precipitation and its distribution - a similarity with rainfall in the driest month, 41 ml of distilled water was then poured over the column every 5 days or 82 ml of distilled water every 10 days - imitating the month with the highest rainfall level. The effect of salts and various concentrations of salt mixtures on the value of the diffusion coefficient were monitored in solutions of NaNO 3 , KNO 3 and Ca(NO 3 ) 2 with added activity 0.45 MGq of 85 SrCl 2 . Diffusion was monitored for 101 days. All measured values are tabulated. The smallest diffusion coefficient was found in chernozem in the presence of H 2 O and the highest value was found in illimerized brown soil in the presence of 0.15 M of KNO 3 . (E.S.). 2 tabs., 10 refs

  11. MAGNETIC QUENCHING OF TURBULENT DIFFUSIVITY: RECONCILING MIXING-LENGTH THEORY ESTIMATES WITH KINEMATIC DYNAMO MODELS OF THE SOLAR CYCLE

    International Nuclear Information System (INIS)

    Munoz-Jaramillo, Andres; Martens, Petrus C. H.; Nandy, Dibyendu

    2011-01-01

    The turbulent magnetic diffusivity in the solar convection zone is one of the most poorly constrained ingredients of mean-field dynamo models. This lack of constraint has previously led to controversy regarding the most appropriate set of parameters, as different assumptions on the value of turbulent diffusivity lead to radically different solar cycle predictions. Typically, the dynamo community uses double-step diffusivity profiles characterized by low values of diffusivity in the bulk of the convection zone. However, these low diffusivity values are not consistent with theoretical estimates based on mixing-length theory, which suggest much higher values for turbulent diffusivity. To make matters worse, kinematic dynamo simulations cannot yield sustainable magnetic cycles using these theoretical estimates. In this work, we show that magnetic cycles become viable if we combine the theoretically estimated diffusivity profile with magnetic quenching of the diffusivity. Furthermore, we find that the main features of this solution can be reproduced by a dynamo simulation using a prescribed (kinematic) diffusivity profile that is based on the spatiotemporal geometric average of the dynamically quenched diffusivity. This bridges the gap between dynamically quenched and kinematic dynamo models, supporting their usage as viable tools for understanding the solar magnetic cycle.

  12. Singularités de la rhéologie de l'air humide saturé et diffusion moléculaire dans les milieux nuageuxSingularities in the rheology of saturated humid air, and molecular diffusion in cloods

    Science.gov (United States)

    Bois, Pierre-Antoine

    Under realistic assumptions, we propose a thermodynamical formalism providing, for the moist-saturated air (cloudy air), a generalized Fick's law. This Fick's law leads to a double diffusive rheology with Dufour effect. The form taken by the energy equation is slightly different from the classical form used in convection problems. We compare the equations with those of the convection in moist unsaturated air (the Dufour effect and all double diffusive effects disappear in this case). As application we demonstrate some consequences of this diffusion in cloudy convection. To cite this article: P.A. Bois, C. R. Mecanique 330 (2002) 627-632.

  13. Diffuse sound field: challenges and misconceptions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    Diffuse sound field is a popular, yet widely misused concept. Although its definition is relatively well established, acousticians use this term for different meanings. The diffuse sound field is defined by a uniform sound pressure distribution (spatial diffusion or homogeneity) and uniform...... tremendously in different chambers because the chambers are non-diffuse in variously different ways. Therefore, good objective measures that can quantify the degree of diffusion and potentially indicate how to fix such problems in reverberation chambers are needed. Acousticians often blend the concept...... of mixing and diffuse sound field. Acousticians often refer diffuse reflections from surfaces to diffuseness in rooms, and vice versa. Subjective aspects of diffuseness have not been much investigated. Finally, ways to realize a diffuse sound field in a finite space are discussed....

  14. Magnetoresistance stories of double perovskites

    Indian Academy of Sciences (India)

    grain surfaces have also been proposed to act as tunnel barriers in Sr2FeMoO6. ... these double perovskites, a gradual decrease in the low-field MR and saturation ... simultaneously, and therefore serious material engineering was needed.

  15. Double Coffee opens in China

    Index Scriptorium Estoniae

    2009-01-01

    Läti suursaadik Ingrida Levrence avas esimese Double Coffee kohviku Hiina pealinnas Pekingi südames. Rahvusvaheline kohvikukett kavatseb laieneda mõne kohviku võrra igal aastal. Seni tegutsetakse Lätis, Eestis, Leedus, Ukrainas ja Valgevenes

  16. Eight Arguments against Double Effect

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    I offer eight arguments against the Doctrine of Double Effect, a normative principle according to which in pursuing the good it is sometimes morally permissible to bring about some evil as a side-effect or merely foreseen consequence: the same evil would not be morally justified as an intended...

  17. A Double-Minded Fractal

    Science.gov (United States)

    Simoson, Andrew J.

    2009-01-01

    This article presents a fun activity of generating a double-minded fractal image for a linear algebra class once the idea of rotation and scaling matrices are introduced. In particular the fractal flip-flops between two words, depending on the level at which the image is viewed. (Contains 5 figures.)

  18. Double standards with radioactive waste

    International Nuclear Information System (INIS)

    Parkinson, A.

    2002-01-01

    The author claims that whether it is short-lived waste from Commonwealth facilities, long-lived plutonium waste from an atomic bomb test site on Aboriginal land, or reactor waste from Lucas Heights, the Australian government applies double standards to suit its own agenda

  19. Constraining neutrinoless double beta decay

    International Nuclear Information System (INIS)

    Dorame, L.; Meloni, D.; Morisi, S.; Peinado, E.; Valle, J.W.F.

    2012-01-01

    A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum-rules (MSR). We show how these theories may constrain the absolute scale of neutrino mass, leading in most of the cases to a lower bound on the neutrinoless double beta decay effective amplitude.

  20. Magnetoresistance stories of double perovskites

    Indian Academy of Sciences (India)

    2015-05-28

    May 28, 2015 ... Tunnelling magnetoresistance (TMR) in polycrystalline double perovskites has been an important research topic for more than a decade now, where the nature of the insulating tunnel barrier is the core issue of debate. Other than the nonmagnetic grain boundaries as conventional tunnel barriers, intragrain ...

  1. Doubled-ended ceramic thyratron

    CERN Multimedia

    1974-01-01

    The double-ended ceramic thyratron CX 1171 B, with its coaxial voltage divider for the SPS. Such a switch, paralleled by three ignitrons in series forms the "thyragnitron" arrangement, and can switch 10 kA, 25 ms pulses, with very fast rise times.

  2. Probing the DNA Structural Requirements for Facilitated Diffusion

    Science.gov (United States)

    2015-01-01

    DNA glycosylases perform a genome-wide search to locate damaged nucleotides among a great excess of undamaged nucleotides. Many glycosylases are capable of facilitated diffusion, whereby multiple sites along the DNA are sampled during a single binding encounter. Electrostatic interactions between positively charged amino acids and the negatively charged phosphate backbone are crucial for facilitated diffusion, but the extent to which diffusing proteins rely on the double-helical structure DNA is not known. Kinetic assays were used to probe the DNA searching mechanism of human alkyladenine DNA glycosylase (AAG) and to test the extent to which diffusion requires B-form duplex DNA. Although AAG excises εA lesions from single-stranded DNA, it is not processive on single-stranded DNA because dissociation is faster than N-glycosidic bond cleavage. However, the AAG complex with single-stranded DNA is sufficiently stable to allow for DNA annealing when a complementary strand is added. This observation provides evidence of nonspecific association of AAG with single-stranded DNA. Single-strand gaps, bubbles, and bent structures do not impede the search by AAG. Instead, these flexible or bent structures lead to the capture of a nearby site of damage that is more efficient than that of a continuous B-form duplex. The ability of AAG to negotiate these helix discontinuities is inconsistent with a sliding mode of diffusion but can be readily explained by a hopping mode that involves microscopic dissociation and reassociation. These experiments provide evidence of relatively long-range hops that allow a searching protein to navigate around DNA binding proteins that would serve as obstacles to a sliding protein. PMID:25495964

  3. Nonlinear Diffusion and Transient Osmosis

    International Nuclear Information System (INIS)

    Igarashi, Akira; Rondoni, Lamberto; Botrugno, Antonio; Pizzi, Marco

    2011-01-01

    We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call ''transient osmosis . We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. Nitrogen diffusion in zirconium nitride

    International Nuclear Information System (INIS)

    Desmaison, J.G.; Smeltzer, W.W.

    1977-01-01

    Nitrogen diffusion in polycrystalline ZrN/sub 0.71-0.79/ spheres, 60 and 90 μm diameter, was studied by the gas-solid exchange technique using 15 N as a tracer at a nitrogen pressure of 220 torr and 1000 to 1200 0 C. These specimens were characterized by chemical analyses, density, lattice parameter, and structural measurements. The tracer diffusion coefficient can be expressed as D* (cm 2 /S) = 3.0 x 10 -10 exp (-23,000/RT). This result, when compared to a previous determination obtained in the same conditions with 254 μm thick plates, confirms that nitrogen transport in this polycrystalline solid at temperatures less than 1200 0 C is associated with a short-circuit diffusion mechanism

  5. Tracer diffusion in ternary alloys

    International Nuclear Information System (INIS)

    Tahir-Kheli, R.A.

    1985-07-01

    An intuitive extension of the theory for diffusion in dynamic binary alloys given in the preceding paper is presented. This theory has also received an independent derivation, based on more formal procedures, by Holdsworth and Elliott. We present Monte Carlo estimates for diffusion correlation factors, fsup(A), fsup(B), and fsup(C) and compare them with the theory. The agreement between the theoretical results and the Monte Carlo estimates for the correlation factors of the slow particles, i.e., fsup(C) and fsup(B), is found to be generally good. In contrast, for the correlation factor, fsup(A), referring to the diffusion coefficient of fast particles in the system, the theoretical results are found to be systematically lower by a small but resolvable margin. It is suggested that this is occasioned by the neglect of spatial constraints on the scattering of coupled tracer-background particle field pairs. (author)

  6. Emissivity of discretized diffusion problems

    International Nuclear Information System (INIS)

    Densmore, Jeffery D.; Davidson, Gregory; Carrington, David B.

    2006-01-01

    The numerical modeling of radiative transfer by the diffusion approximation can produce artificially damped radiation propagation if spatial cells are too optically thick. In this paper, we investigate this nonphysical behavior at external problem boundaries by examining the emissivity of the discretized diffusion approximation. We demonstrate that the standard cell-centered discretization produces an emissivity that is too low for optically thick cells, a situation that leads to the lack of radiation propagation. We then present a modified boundary condition that yields an accurate emissivity regardless of cell size. This modified boundary condition can be used with a deterministic calculation or as part of a hybrid transport-diffusion method for increasing the efficiency of Monte Carlo simulations. We also discuss the range of applicability, as a function of cell size and material properties, when this modified boundary condition is employed in a hybrid technique. With a set of numerical calculations, we demonstrate the accuracy and usefulness of this modified boundary condition

  7. Diffusion in inhomogeneous polymer membranes

    Science.gov (United States)

    Kasargod, Sameer S.; Adib, Farhad; Neogi, P.

    1995-10-01

    The dual mode sorption solubility isotherms assume, and in instances Zimm-Lundberg analysis of the solubilities show, that glassy polymers are heterogeneous and that the distribution of the solute in the polymer is also inhomogeneous. Under some conditions, the heterogeneities cannot be represented as holes. A mathematical model describing diffusion in inhomogeneous polymer membranes is presented using Cahn and Hilliard's gradient theory. The fractional mass uptake is found to be proportional to the fourth root of time rather than the square root, predicted by Fickian diffusion. This type of diffusion is classified as pseudo-Fickian. The model is compared with one experimental result available. A negative value of the persistence factor is obtained and the results are interpreted.

  8. Single Crystal Diffuse Neutron Scattering

    Directory of Open Access Journals (Sweden)

    Richard Welberry

    2018-01-01

    Full Text Available Diffuse neutron scattering has become a valuable tool for investigating local structure in materials ranging from organic molecular crystals containing only light atoms to piezo-ceramics that frequently contain heavy elements. Although neutron sources will never be able to compete with X-rays in terms of the available flux the special properties of neutrons, viz. the ability to explore inelastic scattering events, the fact that scattering lengths do not vary systematically with atomic number and their ability to scatter from magnetic moments, provides strong motivation for developing neutron diffuse scattering methods. In this paper, we compare three different instruments that have been used by us to collect neutron diffuse scattering data. Two of these are on a spallation source and one on a reactor source.

  9. The width of jets in powerful edge-brightened extragalactic double radio sources

    International Nuclear Information System (INIS)

    Banhatti, D.G.

    1987-01-01

    The widths of primary and secondary jets are derived from a sample of 14 double hotspots in powerful extended extragalactic double radio sources. In the model employed, the primary jet extends from the core to the more compact primary hotspot and the secondary jet emerges from the primary hotspot and dissipates to form the diffuse secondary hotspot. Mean values of hotspot size/jet extent imply that the primary and secondary jets, if free, must be 2 0 and > 27 0 wide, respectively. (author)

  10. Information hiding based on double random-phase encoding and public-key cryptography.

    Science.gov (United States)

    Sheng, Yuan; Xin, Zhou; Alam, Mohammed S; Xi, Lu; Xiao-Feng, Li

    2009-03-02

    A novel information hiding method based on double random-phase encoding (DRPE) and Rivest-Shamir-Adleman (RSA) public-key cryptosystem is proposed. In the proposed technique, the inherent diffusion property of DRPE is cleverly utilized to make up the diffusion insufficiency of RSA public-key cryptography, while the RSA cryptosystem is utilized for simultaneous transmission of the cipher text and the two phase-masks, which is not possible under the DRPE technique. This technique combines the complementary advantages of the DPRE and RSA encryption techniques and brings security and convenience for efficient information transmission. Extensive numerical simulation results are presented to verify the performance of the proposed technique.

  11. Innovation Diffusion: Assessment of Strategies within the Diffusion Simulation Game

    Science.gov (United States)

    Enfield, Jacob; Myers, Rodney D.; Lara, Miguel; Frick, Theodore W.

    2012-01-01

    Educators increasingly view the high level of engagement and experiential learning offered by games as a means to promote learning. However, as with any designed learning experience, player experiences should provide an accurate representation of content to be learned. In this study, the authors investigated the DIFFUSION SIMULATION GAME (DSG) to…

  12. Some theoretical aspects of electrostatic double layers

    International Nuclear Information System (INIS)

    Carlqvist, P.

    1978-11-01

    A review is presented of the main results of the theoretical work on electrostatic double layers. The general properties of double layers are first considered. Then the time-independent double layer is discussed. The discussion deals with the potential drop, the thickness, and some necessary criteria for the existence and stability of the layer. As a complement to the study of the timeindependent double layer a few remarks are also made upon the timedependent double layer. Finally the question of how double layers are formed and maintained is treated. Several possible formation mechanisms are considered. (author)

  13. Huang diffuse scattering of neutrons

    International Nuclear Information System (INIS)

    Burkel, E.; Guerard, B. v.; Metzger, H.; Peisl, J.

    1979-01-01

    Huang diffuse neutron scattering was measured for the first time on niobium with interstitially dissolved deuterium as well as on MgO after neutron irradiation and Li 7 F after γ-irradiation. With Huang diffuse scattering the strength and symmetry of the distortion field around lattice defects can be determined. Our results clearly demonstrate that this method is feasible with neutrons. The present results are compared with X-ray experiments and the advantages of using neutrons is discussed in some detail. (orig.)

  14. In situ measurement of diffusivity

    International Nuclear Information System (INIS)

    Berne, F.; Pocachard, J.

    2004-01-01

    The mechanism of molecular diffusion controls the migration of contaminants in very low-permeability porous media, like underground facilities for the storage of hazardous waste. Determining of relevant diffusion coefficients is therefore of prime importance. A few techniques exist for in situ measurement of the quantity, but they suffer from many handicaps (duration, complexity and cost of the experiments). We propose here two innovative methods that have some potential to improve the situation. So far, we have found them feasible on the basis of design calculations and laboratory experiments. This work is presently protected by a patent. (author)

  15. In situ measurement of diffusivity

    International Nuclear Information System (INIS)

    Berne, Ph.; Pocachard, J.

    2005-01-01

    The mechanism of molecular diffusion controls the migration of contaminants in very low-permeability porous media, like underground facilities for the storage of hazardous waste. Determining the relevant diffusion coefficients is, therefore, of prime importance. A few techniques exist for the in situ measurement of that quantity, but they suffer from many handicaps (duration, complexity and cost of the experiments). We propose here two innovative methods that have some potential to improve this situation. So far, we have found them feasible on the basis of design calculations and laboratory experiments. This work is presently protected by a patent. (author)

  16. Oxygen diffusion in cuprate superconductors

    International Nuclear Information System (INIS)

    Routbort, J.L.; Rothman, S.J.

    1995-01-01

    Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La 2-x Sr x CuO 4 , YBa 2 Cu 3 O 7- δ, YBa 2 Cu 4 O 8 , and the Bi 2 Sr 2 Ca n-1 Cu n O 2+4 (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible

  17. Optimization of hydraulic turbine diffuser

    Directory of Open Access Journals (Sweden)

    Moravec Prokop

    2016-01-01

    Full Text Available Hydraulic turbine diffuser recovers pressure energy from residual kinetic energy on turbine runner outlet. Efficiency of this process is especially important for high specific speed turbines, where almost 50% of available head is utilized within diffuser. Magnitude of the coefficient of pressure recovery can be significantly influenced by designing its proper shape. Present paper focuses on mathematical shape optimization method coupled with CFD. First method is based on direct search Nelder-Mead algorithm, while the second method employs adjoint solver and morphing. Results obtained with both methods are discussed and their advantages/disadvantages summarized.

  18. Langevin diffusions on the torus

    DEFF Research Database (Denmark)

    García-Portugués, Eduardo; Sørensen, Michael; Mardia, Kanti V.

    2018-01-01

    We introduce stochastic models for continuous-time evolution of angles and develop their estimation. We focus on studying Langevin diffusions with stationary distributions equal to well-known distributions from directional statistics, since such diffusions can be regarded as toroidal analogues......) a likelihood based on the stationary distribution; (ii) toroidal adaptations of the Euler and Shoji–Ozaki pseudo-likelihoods; (iii) a likelihood based on a specific approximation to the transition density of the wrapped normal process. A simulation study compares, in dimensions one and two, the approximate...

  19. Slaved diffusion in phospholipid bilayers

    Science.gov (United States)

    Zhang, Liangfang; Granick, Steve

    2005-01-01

    The translational diffusion of phospholipids in supported fluid bilayers splits into two populations when polyelectrolytes adsorb at incomplete surface coverage. Spatially resolved measurements using fluorescence correlation spectroscopy show that a slow mode, whose magnitude scales inversely with the degree of polymerization of the adsorbate, coexists with a fast mode characteristic of naked lipid diffusion. Inner and outer leaflets of the bilayer are affected nearly equally. Mobility may vary from spot to spot on the membrane surface, despite the lipid composition being the same. This work offers a mechanism to explain how nanosized domains with reduced mobility arise in lipid membranes. PMID:15967988

  20. Some Aspects of Diffusion Theory

    CERN Document Server

    Pignedoli, A

    2011-01-01

    This title includes: V.C.A. Ferraro: Diffusion of ions in a plasma with applications to the ionosphere; P.C. Kendall: On the diffusion in the atmosphere and ionosphere; F. Henin: Kinetic equations and Brownian motion; T. Kahan: Theorie des reacteurs nucleaires: methodes de resolution perturbationnelles, interactives et variationnelles; C. Cattaneo: Sulla conduzione del calore; C. Agostinelli: Formule di Green per la diffusione del campo magnetico in un fluido elettricamente conduttore; A. Pignedoli: Transformational methods applied to some one-dimensional problems concerning the equations of t

  1. Identification of Y-shaped and O-shaped diffusion regions during magnetic reconnection in a laboratory plasma

    International Nuclear Information System (INIS)

    Yamada, Masaaki; Ji, H.; Hsu, S.; Carter, T.; Kulsrud, R.; Ono, Yasushi; Perkins, F.

    1997-01-01

    Two strikingly different shapes of diffusion regions are identified during magnetic reconnection in a magnetohydrodynamic laboratory plasma. The shapes depend on the third vector component of the reconnecting magnetic fields. Without the third component (anti-parallel or null-helicity reconnection), a thin double-Y shaped diffusion region is identified. In this case, the neutral sheet current profile is accurately measured to be as narrow as the order of the ion gyro-radius. In the presence of an appreciable third component (co-helicity reconnection), an O-shaped diffusion region appears and grows into a spheromak configuration

  2. Spatial Mapping of Translational Diffusion Coefficients Using Diffusion Tensor Imaging: A Mathematical Description.

    Science.gov (United States)

    Shetty, Anil N; Chiang, Sharon; Maletic-Savatic, Mirjana; Kasprian, Gregor; Vannucci, Marina; Lee, Wesley

    2014-01-01

    In this article, we discuss the theoretical background for diffusion weighted imaging and diffusion tensor imaging. Molecular diffusion is a random process involving thermal Brownian motion. In biological tissues, the underlying microstructures restrict the diffusion of water molecules, making diffusion directionally dependent. Water diffusion in tissue is mathematically characterized by the diffusion tensor, the elements of which contain information about the magnitude and direction of diffusion and is a function of the coordinate system. Thus, it is possible to generate contrast in tissue based primarily on diffusion effects. Expressing diffusion in terms of the measured diffusion coefficient (eigenvalue) in any one direction can lead to errors. Nowhere is this more evident than in white matter, due to the preferential orientation of myelin fibers. The directional dependency is removed by diagonalization of the diffusion tensor, which then yields a set of three eigenvalues and eigenvectors, representing the magnitude and direction of the three orthogonal axes of the diffusion ellipsoid, respectively. For example, the eigenvalue corresponding to the eigenvector along the long axis of the fiber corresponds qualitatively to diffusion with least restriction. Determination of the principal values of the diffusion tensor and various anisotropic indices provides structural information. We review the use of diffusion measurements using the modified Stejskal-Tanner diffusion equation. The anisotropy is analyzed by decomposing the diffusion tensor based on symmetrical properties describing the geometry of diffusion tensor. We further describe diffusion tensor properties in visualizing fiber tract organization of the human brain.

  3. Contributions of chemical and diffusive exchange to T1ρ dispersion.

    Science.gov (United States)

    Cobb, Jared Guthrie; Xie, Jingping; Gore, John C

    2013-05-01

    Variations in local magnetic susceptibility may induce magnetic field gradients that affect the signals acquired for MR imaging. Under appropriate diffusion conditions, such fields produce effects similar to slow chemical exchange. These effects may also be found in combination with other chemical exchange processes at multiple time scales. We investigate these effects with simulations and measurements to determine their contributions to rotating frame (R1ρ ) relaxation in model systems. Simulations of diffusive and chemical exchange effects on R1ρ dispersion were performed using the Bloch equations. Additionally, R1ρ dispersion was measured in suspensions of Sephadex and latex beads with varying spin locking fields at 9.4 T. A novel analysis method was used to iteratively fit for apparent chemical and diffusive exchange rates with a model by Chopra et al. Single- and double-inflection points in R1ρ dispersion profiles were observed, respectively, in simulations of slow diffusive exchange alone and when combined with rapid chemical exchange. These simulations were consistent with measurements of R1ρ in latex bead suspensions and small-diameter Sephadex beads that showed single- and double-inflection points, respectively. These observations, along with measurements following changes in temperature and pH, are consistent with the combined effects of slow diffusion and rapid -OH exchange processes. Copyright © 2012 Wiley Periodicals, Inc.

  4. Non-probabilistic solutions of imprecisely defined fractional-order diffusion equations

    International Nuclear Information System (INIS)

    Chakraverty, S.; Tapaswini, Smita

    2014-01-01

    The fractional diffusion equation is one of the most important partial differential equations (PDEs) to model problems in mathematical physics. These PDEs are more practical when those are combined with uncertainties. Accordingly, this paper investigates the numerical solution of a non-probabilistic viz. fuzzy fractional-order diffusion equation subjected to various external forces. A fuzzy diffusion equation having fractional order 0 < α ≤ 1 with fuzzy initial condition is taken into consideration. Fuzziness appearing in the initial conditions is modelled through convex normalized triangular and Gaussian fuzzy numbers. A new computational technique is proposed based on double parametric form of fuzzy numbers to handle the fuzzy fractional diffusion equation. Using the single parametric form of fuzzy numbers, the original fuzzy diffusion equation is converted first into an interval-based fuzzy differential equation. Next, this equation is transformed into crisp form by using the proposed double parametric form of fuzzy numbers. Finally, the same is solved by Adomian decomposition method (ADM) symbolically to obtain the uncertain bounds of the solution. Computed results are depicted in terms of plots. Results obtained by the proposed method are compared with the existing results in special cases. (general)

  5. Enhanced nitrogen removal in single-chamber microbial fuel cells with increased gas diffusion areas

    KAUST Repository

    Yan, Hengjing

    2012-11-23

    Single-chamber microbial fuel cells (MFCs) with nitrifiers pre-enriched at the air cathodes have previously been demonstrated as a passive strategy for integrating nitrogen removal into current-generating bioelectrochemical systems. To further define system design parameters for this strategy, we investigated in this study the effects of oxygen diffusion area and COD/N ratio in continuous-flow reactors. Doubling the gas diffusion area by adding an additional air cathode or a diffusion cloth significantly increased the ammonia and COD removal rates (by up to 115% and 39%), ammonia removal efficiency (by up to 134%), the cell voltage and cathode potentials, and the power densities (by a factor of approximately 2). When the COD/N ratio was lowered from 13 to 3, we found up to 244% higher ammonia removal rate but at least 19% lower ammonia removal efficiency. An increase of COD removal rate by up to 27% was also found when the COD/N ratio was lowered from 11 to 3. The Coulombic efficiency was not affected by the additional air cathode, but decreased by an average of 11% with the addition of a diffusion cloth. Ammonia removal by assimilation was also estimated to understand the ammonia removal mechanism in these systems. These results showed that the doubling of gas diffusion area enhanced N and COD removal rates without compromising electrochemical performance. © 2012 Wiley Periodicals, Inc.

  6. Lightweight Double Neutron Star Found

    Science.gov (United States)

    Kohler, Susanna

    2018-02-01

    More than forty years after the first discovery of a double neutron star, we still havent found many others but a new survey is working to change that.The Hunt for PairsThe observed shift in the Hulse-Taylor binarys orbital period over time as it loses energy to gravitational-wave emission. [Weisberg Taylor, 2004]In 1974, Russell Hulse and Joseph Taylor discovered the first double neutron star: two compact objects locked in a close orbit about each other. Hulse and Taylors measurements of this binarys decaying orbit over subsequent years led to a Nobel prize and the first clear evidence of gravitational waves carrying energy and angular momentum away from massive binaries.Forty years later, we have since confirmed the existence of gravitational waves directly with the Laser Interferometer Gravitational-Wave Observatory (LIGO). Nonetheless, finding and studying pre-merger neutron-star binaries remains a top priority. Observing such systems before they merge reveals crucial information about late-stage stellar evolution, binary interactions, and the types of gravitational-wave signals we expect to find with current and future observatories.Since the Hulse-Taylor binary, weve found a total of 16 additional double neutron-star systems which represents only a tiny fraction of the more than 2,600 pulsars currently known. Recently, however, a large number of pulsar surveys are turning their eyes toward the sky, with a focus on finding more double neutron stars and at least one of them has had success.The pulse profile for PSR J1411+2551 at 327 MHz. [Martinez et al. 2017]A Low-Mass DoubleConducted with the 1,000-foot Arecibo radio telescope in Puerto Rico, the Arecibo 327 MHz Drift Pulsar Survey has enabled the recent discovery of dozens of pulsars and transients. Among them, as reported by Jose Martinez (Max Planck Institute for Radio Astronomy) and coauthors in a recent publication, is PSR J1411+2551: a new double neutron star with one of the lowest masses ever measured

  7. Determination of diffusion coefficients in polypyrrole thin films using a current pulse relaxation method

    Science.gov (United States)

    Penner, Reginald M.; Vandyke, Leon S.; Martin, Charles R.

    1987-01-01

    The current pulse E sub oc relaxation method and its application to the determination of diffusion coefficients in electrochemically synthesized polypyrrole thin films is described. Diffusion coefficients for such films in Et4NBF4 and MeCN are determined for a series of submicron film thicknesses. Measurement of the double-layer capacitance, C sub dl, and the resistance, R sub u, of polypyrrole thin films as a function of potential obtained with the galvanostatic pulse method is reported. Measurements of the electrolyte concentration in reduced polypyrrole films are also presented to aid in the interpretation of the data.

  8. Co-doping with antimony to control phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-02-15

    In germanium, phosphorous and antimony diffuse quickly and as such their transport must be controlled in order to design efficient n-typed doped regions. Here, density functional theory based calculations are used to predict the influence of double donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy were formed. These clusters are energetically stable and can lead to the formation of even larger clusters involving a number of donor atoms around a vacancy, thereby affecting the properties of devices.

  9. A perturbational h4 exponential finite difference scheme for the convective diffusion equation

    International Nuclear Information System (INIS)

    Chen, G.Q.; Gao, Z.; Yang, Z.F.

    1993-01-01

    A perturbational h 4 compact exponential finite difference scheme with diagonally dominant coefficient matrix and upwind effect is developed for the convective diffusion equation. Perturbations of second order are exerted on the convective coefficients and source term of an h 2 exponential finite difference scheme proposed in this paper based on a transformation to eliminate the upwind effect of the convective diffusion equation. Four numerical examples including one- to three-dimensional model equations of fluid flow and a problem of natural convective heat transfer are given to illustrate the excellent behavior of the present exponential schemes. Besides, the h 4 accuracy of the perturbational scheme is verified using double precision arithmetic

  10. Innovation and creativity : Beyond diffusion

    DEFF Research Database (Denmark)

    Michelsen, Anders Ib

    2009-01-01

    of postwar systems theory and introduce Castoriadis' philosophy as an interesting option in this regard. It proceeds in four parts: (a) First, it debates the limits of the commonplace metaphor of diffusion and adoption in today's debate on innovation. (b) Second, it will present aspects of Castoriadis...

  11. Stability of Randomly Switched Diffusions

    DEFF Research Database (Denmark)

    Schiøler, Henrik; Leth, John-Josef; Gholami, Mehdi

    2012-01-01

    This paper provides a sufficient criterion for ε-moment stability (boundedness) and ergodicity for a class of systems comprising a finite set of diffusions among which switching is governed by a continuous time Markov chain. Stability/instability properties for each separate subsystem are assumed...

  12. Evaluating Technology Transfer and Diffusion.

    Science.gov (United States)

    Bozeman, Barry; And Others

    1988-01-01

    Four articles discuss the evaluation of technology transfer and diffusion: (1) "Technology Transfer at the U.S. National Laboratories: A Framework for Evaluation"; (2) "Application of Social Psychological and Evaluation Research: Lessons from Energy Information Programs"; (3) "Technology and Knowledge Transfer in Energy R and D Laboratories: An…

  13. Less Confusion in Diffusion MRI

    NARCIS (Netherlands)

    Tax, CMW

    2016-01-01

    With its unique ability to investigate tissue architecture and microstructure in vivo, diffusion MRI (dMRI) has gained tremendous interest and the society has been continuously triggered to develop novel dMRI image analysis approaches. With the overwhelming amount of strategies currently available

  14. Diffuse and vascular hepatic diseases

    International Nuclear Information System (INIS)

    Kreimeyer, S.; Grenacher, L.

    2011-01-01

    In addition to focal liver lesions, diffuse and vascular disorders of the liver represent a wide spectrum of liver diseases which are from the radiological point of view often difficult or nearly impossible to diagnose. Classical diagnostic methods are computed tomography and magnetic resonance imaging in addition to ultrasound. Diffuse parenchymal damage caused by diseases of various etiologies is therefore difficult to evaluate because it often lacks characteristic morphological features. For hepatic steatosis, hemochromatosis/siderosis as an example of a diffuse storage disease and sarcoidosis and candidiasis as infectious/inflammatory diseases, an image-based diagnosis is appropriate in some cases. For most diffuse liver diseases, however only nonspecific changes are visualized. Vascular pathologies of the liver, such as the Budd-Chiari syndrome and portal vein thrombosis, however, can usually be diagnosed very clearly using radiology and there is also a very effective interventional radiological treatment. Chronic diseases very often culminate in liver cirrhosis which is highly associated with an increased risk of liver cancer. (orig.) [de

  15. Memory effects in turbulent diffusion

    International Nuclear Information System (INIS)

    Zagorodny, A.G.; Weiland, J.; Wilhelmsson, H.

    1993-01-01

    A non-Markovian approach is proposed for the derivation of the diffusion coefficient of saturated turbulence. A memory term accounting for nonlocal coherence effects is introduced in a new attempt to describe the transition between weak and strong turbulence. The result compares favourably with recent experiments as well as mode coupling simulations of fusion plasmas. (14 refs.)

  16. Diffusion of hydrogen in yttrium

    International Nuclear Information System (INIS)

    Vorobyov, V.V.; Ryabchikov, L.N.

    1966-01-01

    In this work the diffusion coefficients of hydrogen in yttrium were determined from the rate at which the hydrogen was released from yttrium samples under a vacuum at temperatures of 450 to 850 0 C and from the quantity of hydrogen retained by yttrium at hydrogen pressures below 5 x 10 - 4 mm Hg in the same temperature range

  17. Diffusion of student business incubators

    DEFF Research Database (Denmark)

    Hjortsø, Carsten Nico Portefée; Honig, Benson; Riis, Nina Louise Fynbo

    education. Applying neo-institutional theory, we examine the development of student incubation activities in the field of general state-funded Danish universities. We review institutional pressures from the political sphere that led to the diffusion of student incubation, introducing a three-phase process...

  18. Unexpected consequences of bedload diffusion

    Science.gov (United States)

    Devauchelle, O.; Abramian, A.; Lajeunesse, E.

    2017-12-01

    Sedimentary grains transported as bedload bump and bounce on the rough bed of the river that entrains them. The succession of these random events causes bedload particles to diffuse across the flow, towards the less active areas of the bed. In a fashion reminiscent of that proposed by Parker (1978) for suspended load, this mechanism opposes gravity to maintain the banks of alluvial rivers. In fact, diffusion is so tightly linked to bedload that it appears in the most basic sediment transport experiment--the straight channel we use to calibrate transport laws. Indeed, the fixed sides of the channel cause the flow, and thus the bed shear stress, to vary across the flume. This variation induces bedload diffusion, which in turn deforms the bed. As a consequence, to reliably calibrate a transport law, we need to measure the full profiles of shear stress and bedload transport, rather than bulk-average these quantities. Unfortunately, using a larger channel does not solve the problem, as a large aspect ratio favors the growth of streaks caused by a diffusion-induced instability. Based on these observations, we propose a different design for sediment transport experiments.

  19. Quasilinear diffusion in inhomogeneous plasmas

    International Nuclear Information System (INIS)

    Hooley, D.L.

    1975-05-01

    The problem of inhomogeneous diffusion in a plasma is considered with emphasis on its possible application to relativistic electron beams. A one-dimensional model with a background electrostatic field is used to illustrate the basic approach, which is then extended to a two-dimensional plasma with a background magnetic field. Only preliminary results are available. (U.S.)

  20. Thermal neutron scattering from a hydrogen-metal system in terms of a general multi-sublattice jump diffusion model

    International Nuclear Information System (INIS)

    Kutner, R.; Sosnowska, I.

    1977-01-01

    A Multi-Sublattice Jump Diffusion Model (MSJD) for hydrogen diffusion through interstitial-site lattices is presented. The MSJD approach may, in principle, be considered as an extension of the Rowe et al (J. Phys. Chem. Solids; 32:41 (1971)) model. Jump diffusion to any neighbours with different jump times which may be asymmetric in space is discussed. On the basis of the model a new method of calculating the diffusion tensor is advanced. The quasielastic, double differential cross section for thermal neutron scattering is obtained in terms of the MSJD model. The model can be used for systems in which interstitial jump diffusion of impurity particles occurs. In Part II the theoretical results are compared with those for quasielastic neutron scattering from the αNbHsub(x) system. (author)

  1. Diffusive scattering of electrons by electron holes around injection fronts

    Science.gov (United States)

    Vasko, I. Y.; Agapitov, O. V.; Mozer, F. S.; Artemyev, A. V.; Krasnoselskikh, V. V.; Bonnell, J. W.

    2017-03-01

    Van Allen Probes have detected nonlinear electrostatic spikes around injection fronts in the outer radiation belt. These spikes include electron holes (EH), double layers, and more complicated solitary waves. We show that EHs can efficiently scatter electrons due to their substantial transverse electric fields. Although the electron scattering driven by EHs is diffusive, it cannot be evaluated via the standard quasi-linear theory. We derive analytical formulas describing local electron scattering by a single EH and verify them via test particle simulations. We show that the most efficiently scattered are gyroresonant electrons (crossing EH on a time scale comparable to the local electron gyroperiod). We compute bounce-averaged diffusion coefficients and demonstrate their dependence on the EH spatial distribution (latitudinal extent and spatial filling factor) and individual EH parameters (amplitude of electrostatic potential, velocity, and spatial scales). We show that EHs can drive pitch angle scattering of ≲5 keV electrons at rates 10-2-10-4 s-1 and, hence, can contribute to electron losses and conjugated diffuse aurora brightenings. The momentum and pitch angle scattering rates can be comparable, so that EHs can also provide efficient electron heating. The scattering rates driven by EHs at L shells L ˜ 5-8 are comparable to those due to chorus waves and may exceed those due to electron cyclotron harmonics.

  2. Monocular Elevation Deficiency - Double Elevator Palsy

    Science.gov (United States)

    ... Español Condiciones Chinese Conditions Monocular Elevation Deficiency/ Double Elevator Palsy En Español Read in Chinese What is monocular elevation deficiency (Double Elevator Palsy)? Monocular Elevation Deficiency, also known by the ...

  3. Transition from single to multiple double layers

    International Nuclear Information System (INIS)

    Chan, C.; Hershkowitz, N.

    1982-01-01

    It is shown that laboratory double layers become multiple double layers when the ratio of Debye length to system length is decreased. This result exhibits characteristics described by boundary layer theory

  4. The Double R Theory of Language Comprehension

    National Research Council Canada - National Science Library

    Ball, Jerry

    2004-01-01

    ... (also known as Cognitive Semantics). This technical report explicates the basic principles and assumptions of Double R Grammar and compares Double R Grammar to Chomsky's X-Bar Theory as well as Langacker's Cognitive Linguistic...

  5. Bifurcation structure of successive torus doubling

    International Nuclear Information System (INIS)

    Sekikawa, Munehisa; Inaba, Naohiko; Yoshinaga, Tetsuya; Tsubouchi, Takashi

    2006-01-01

    The authors discuss the 'embryology' of successive torus doubling via the bifurcation theory, and assert that the coupled map of a logistic map and a circle map has a structure capable of generating infinite number of torus doublings

  6. Evolution between self-assembled single and double ring-like nanostructures

    International Nuclear Information System (INIS)

    Lee, J H; Wang, Zh M; Abuwaar, Z Y; Strom, N W; Salamo, G J

    2006-01-01

    The evolution between lattice-matched GaAs/Al 0.3 Ga 0.7 As single and double ring-like nanostructures is studied, with an emphasis on the construction and destruction of the observed outer ring. Using droplet epitaxy, this was achieved by directly controlling the Ga surface diffusion on GaAs(100). Double ring-like nanostructures were observed at relatively low temperatures under a fixed As 4 flux (beam equivalent pressure (BEP) of 6.4 μTorr) and at a fixed temperature under a high As 4 flux. The construction of the outer ring can be controlled through surface diffusion by varying the substrate temperature or the As 4 flux. Single ring-like nanostructures were realized both at relatively high temperatures under a fixed As 4 flux, and at low temperatures under a relatively low As 4 flux

  7. Wright-Fisher diffusion bridges.

    Science.gov (United States)

    Griffiths, Robert C; Jenkins, Paul A; Spanò, Dario

    2017-10-06

    The trajectory of the frequency of an allele which begins at x at time 0 and is known to have frequency z at time T can be modelled by the bridge process of the Wright-Fisher diffusion. Bridges when x=z=0 are particularly interesting because they model the trajectory of the frequency of an allele which appears at a time, then is lost by random drift or mutation after a time T. The coalescent genealogy back in time of a population in a neutral Wright-Fisher diffusion process is well understood. In this paper we obtain a new interpretation of the coalescent genealogy of the population in a bridge from a time t∈(0,T). In a bridge with allele frequencies of 0 at times 0 and T the coalescence structure is that the population coalesces in two directions from t to 0 and t to T such that there is just one lineage of the allele under consideration at times 0 and T. The genealogy in Wright-Fisher diffusion bridges with selection is more complex than in the neutral model, but still with the property of the population branching and coalescing in two directions from time t∈(0,T). The density of the frequency of an allele at time t is expressed in a way that shows coalescence in the two directions. A new algorithm for exact simulation of a neutral Wright-Fisher bridge is derived. This follows from knowing the density of the frequency in a bridge and exact simulation from the Wright-Fisher diffusion. The genealogy of the neutral Wright-Fisher bridge is also modelled by branching Pólya urns, extending a representation in a Wright-Fisher diffusion. This is a new very interesting representation that relates Wright-Fisher bridges to classical urn models in a Bayesian setting. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Turbulent diffusion of small particles

    International Nuclear Information System (INIS)

    Margolin, L.G.

    1977-11-01

    The diffusion of small, spherical, rigid particles suspended in an incompressible turbulent fluid, but not interacting with each other, was studied. As a stochastic process, the turbulent fluid velocity field is assumed to be homogeneous, isotropic and stationary. Assuming the Stokes regime, a particle of equation of motion is used which includes only the effects of Stokes drag and a virtual mass force and an exact solution is found for the particle velocity correlation function, for all times and initial conditions, in terms of a fluid velocity correlation function measured along the motion of the particle. This shows that for times larger than a certain time scale, the particle velocity correlation becomes stationary. The effect of small shears in the fluid velocity was considered, under the additional restrictions of a certain high frequency regime for the turbulence. The shears convected past the particle much faster than the growth of the boundary layer. New force terms due to the presence of such shears are calculated and incorporated into the equation of motion. A perturbation solution to this equation is constructed, and the resultant particle velocity correlation function and diffusion coefficient are calculated. To lowest order, the particle diffusivity is found to be unaltered by the presence of small mean flow shears. The last model treated is one in which particles traverse a turbulent fluid with a large mean velocity. Among other restrictions, linearized form drag is assumed. The diffusion coefficient for such particles was calculated, and found to be much smaller than the passive scalar diffusion coefficient. This agrees within 5 percent with the experimental results of Snyder and Lumley

  9. Diffusion of oxygen in cork.

    Science.gov (United States)

    Lequin, Sonia; Chassagne, David; Karbowiak, Thomas; Simon, Jean-Marc; Paulin, Christian; Bellat, Jean-Pierre

    2012-04-04

    This work reports measurements of effective oxygen diffusion coefficient in raw cork. Kinetics of oxygen transfer through cork is studied at 298 K thanks to a homemade manometric device composed of two gas compartments separated by a cork wafer sample. The first compartment contains oxygen, whereas the second one is kept under dynamic vacuum. The pressure decrease in the first compartment is recorded as a function of time. The effective diffusion coefficient D(eff) is obtained by applying Fick's law to transient state using a numerical method based on finite differences. An analytical model derived from Fick's law applied to steady state is also proposed. Results given by these two methods are in close agreement with each other. The harmonic average of the effective diffusion coefficients obtained from the distribution of 15 cork wafers of 3 mm thickness is 1.1 × 10(-9) m(2) s(-1) with a large distribution over four decades. The statistical analysis of the Gaussian distribution obtained on a 3 mm cork wafer is extrapolated to a 48 mm cork wafer, which length corresponds to a full cork stopper. In this case, the probability density distribution gives a mean value of D(eff) equal to 1.6 × 10(-9) m(2) s(-1). This result shows that it is possible to obtain the effective diffusion coefficient of oxygen through cork from short time (few days) measurements performed on a thin cork wafer, whereas months are required to obtain the diffusion coefficient for a full cork stopper. Permeability and oxygen transfer rate are also calculated for comparison with data from other studies.

  10. Double-compartment wrist arthrography

    International Nuclear Information System (INIS)

    Quinn, S.F.; Pittman, C.; Belsole, R.; Greene, T.L.; Rayhack, J.; Clark, R.A.; King, P.S.

    1987-01-01

    Seventy patients with clinical wrist problems were studied with double-compartment wrist arthrography. Midcarpal and radiocarpal compartment arthrograms were obtained in all patients. Digital subtraction technique was used to subtract out contrast from the first compartmental injection. Digital technique also allowed a dynamic record of each injection, which helped determine sites of intercompartmental communication. Postarthrography exercises recorded on videotape were performed after each injection. There were 34 normal studies. Abnormalities in the other 36 patients included: scapholunate communication (n = 9), lunatotriquetral communication (n = 6), communication with tendon sheaths (n = 4), communication with distal radioulnar compartment (n = 14), abnormal synovium process (n = 9), and communication through the radial or ulnar collateral ligament (n = 3). Double-compartment wrist arthrography may provide additional information for complex problems of the wrist

  11. International and domestic aspects of double taxation

    OpenAIRE

    Murgáčová, Miroslava

    2010-01-01

    International and local aspects of double taxation Abstract The purpose of my thesis is to analyze international double taxation taking into account both local legislation and international aspects. Double taxation is the situation, where the same income (or capital) is subject to the same tax more than once. Mostly, the international double taxation appears when the state of the source of income implies taxes on the income of the non-residents and the state of residence of the income receive...

  12. Impact of the solution ionic strength on strontium diffusion through the Callovo-Oxfordian clayrocks: An experimental and modeling study

    International Nuclear Information System (INIS)

    Savoye, S.; Beaucaire, C.; Grenut, B.; Fayette, A.

    2015-01-01

    Highlights: • HTO and 85 Sr diffusion is studied in clayrocks under increasing ionic strengths. • Sr diffusive flux is 5 times higher than HTO under standard porewater ionic strength. • Sr diffusive flux is reduced when the porewater ionic strength increases. • The Sr diffusive evolution is qualitatively reproduced by a surface diffusion model. - Abstract: Diffusion of cations in clayrocks is widely investigated, because deep clay-rich formations are currently considered as one of the potential host rocks for radioactive waste repositories. However, several authors have already reported that sorbing cations seem to diffuse at rates larger than those predicted by a simple pore diffusion model from their sorption coefficients and from the diffusive flux of non-sorbing water tracers. This process has been attributed to the migration of cations within the electrical double layer, next to the mineral surfaces, called the surface diffusion phenomenon. The aim of this work was to verify whether this “enhanced” cation diffusion compared to neutral species was observed for strontium and, if so, to what extent this effect might vary with the salinity of the synthetic solutions. These questions were addressed by performing batch sorption, through-diffusion and out-diffusion experiments on rock samples from the Callovo-Oxfordian claystone formation (France). The results showed that there was a good agreement of the distribution ratios (R D ) determined on crushed and intact rocks by batch and through-diffusion methods with a R D decrease related to the increase of the sodium concentration, a sorption competitor. Such a trend was also well reproduced by means of a geochemical modeling based on the multi-site ion exchange (MSIE) theory. Moreover, the “enhanced” diffusion for strontium was clearly observed in this study: the Sr diffusive flux was almost five times higher than that for HTO in the cell with the lowest ionic strength, and diminished to less than 1

  13. In vivo P-31 MR diffusion spectroscopy

    International Nuclear Information System (INIS)

    Moonen, C.T.W.; Vanzijl, P.C.M.; LeBihan, D.

    1988-01-01

    This paper discusses the Stejskal-Tanner diffusion spin-echo sequence modified for the in vivo diffusion spectroscopy. The apparent diffusion constant D α was measured as a function of the diffusion time. Contrary to the results in phantom samples, a strong dependency of the D α for phosphocreatine (PCr) in the rat muscle tissue on diffusion time was observed, clearly indicating restricted diffusion effects and allowing an approximation of the size of the restricted volume (8-13 μm). This size fits well with the known dimensions of a normal muscle cell

  14. Diffraction and diffusion in room acoustics

    DEFF Research Database (Denmark)

    Rindel, Jens Holger; Rasmussen, Birgit

    1996-01-01

    Diffraction and diffusion are two phenomena that are both related to the wave nature of sound. Diffraction due to the finite size of reflecting surfaces and the design of single reflectors and reflector arrays are discussed. Diffusion is the result of scattering of sound reflected from surfaces...... that are not plane but curved or irregular. The importance of diffusion has been demonstrated in concert halls. Methods for the design of diffusing surfaces and the development of new types of diffusers are reviewed. Finally, the importance of diffraction and diffusion in room acoustic computer models is discussed....

  15. Bayesian regularization of diffusion tensor images

    DEFF Research Database (Denmark)

    Frandsen, Jesper; Hobolth, Asger; Østergaard, Leif

    2007-01-01

    Diffusion tensor imaging (DTI) is a powerful tool in the study of the course of nerve fibre bundles in the human brain. Using DTI, the local fibre orientation in each image voxel can be described by a diffusion tensor which is constructed from local measurements of diffusion coefficients along...... several directions. The measured diffusion coefficients and thereby the diffusion tensors are subject to noise, leading to possibly flawed representations of the three dimensional fibre bundles. In this paper we develop a Bayesian procedure for regularizing the diffusion tensor field, fully utilizing...

  16. The function of single containment and double containment of PWR nuclear power plant

    International Nuclear Information System (INIS)

    Chen Weijing.

    1985-01-01

    The function and structures of single containment and double containment of PWR nuclear power plant were described briefiy. The dissimilarites of diffent type of containments, which effects the impact of environment are discused. The impact of environment, effected by 'source term', containment gas leak rate and diffusion pattern of the released gas, under different operating condition is analysed. Especially, the impact of environment under LOCA accident is fully analysed

  17. Analysis of tracer tests with multirate diffusion models: recent results and future directions within the WIPP project

    International Nuclear Information System (INIS)

    McKenna, S.A.; Meigs, L.C.; Altman, S.J.; Haggerty, R.

    1998-01-01

    A series of single-well injection-withdrawal (SWIW) and two-well convergent-flow (TWCF) tracer tests were conducted in the Culebra dolomite at the WIPP site in late 1995 and early 1996. Modeling analyses over the past year have focused on reproducing the observed mass-recovery curves and understanding the basis physical processes controlling tracer transport in SWIW and TWCF tests. To date, specific modeling efforts have focused on five SWIW tests and one TWCF pathway at each of two different locations. An inverse parameter-estimation procedure was implemented to model the SWIW and TWCF tests with both traditional and multirate double-porosity formulations. The traditional model assumes a single diffusion rate while the multirate model uses a first-order approximation to model a continuous distribution of diffusion coefficients. Conceptually, the multirate model represents variable matrix block sizes within the Culebra as observed in geologic investigations and also variability in diffusion rates within the matrix blocks as observed with X-ray imaging in the laboratory. Single-rate double-porosity models cannot provide an adequate match to the SWIW data. Multirate double-porosity models provide excellent fits to all five SWIW mass-recovery curves. Models of the TWCF tests show that, at one location, the tracer test can be modeled with both single-rate and multirate double-porosity models. At the other location, only the multi-rate double-porosity model is capable of explaining the test results

  18. Diffusing diffusivity: a new derivation and comparison with simulations

    Indian Academy of Sciences (India)

    Rohit Jain

    active media, where the relation of Eq.(1) is not valid at all times.4–6 ... tional diffusion of dumbbells in 2D porous media of stationary hard ..... reflecting boundary condition at D = 0, i.e., πeq(D) = 1. D0 .... Superdiffusion and viscoelastic vortex flows in a two- .... gator for Free, Linear, and Harmonic Potentials in the. Over- and ...

  19. Oceanic diffusion in the coastal area

    International Nuclear Information System (INIS)

    Rukuda, Masaaki

    1980-03-01

    Described in this paper is the eddy diffusion in the area off Tokai Village investigated by means of dye diffusion experiment and of oceanic observation. In order to assess the oceanic diffusion in coastal areas, improved methods effective in complex field were developed. The oceanic diffusion was separated in two groups, horizontal and vertical diffusion respectively. Both these diffusions are combined and their analysis together is difficult. The oceanic diffusion is thus considered separately. Instantaneous point release is the basis of horizontal diffusion analysis. Continuous release is then the overlap of numerous instantaneous releases. It was shown that the diffusion parameters derived from the results of diffusion experiment or oceanic observation vary widely with time and place and with sea conditions. A simple diffusion equation was developed from the equation of continuity. The results were in good agreement with seasonal mean horizontal distribution of river water in the sea area. The vertical observation in diffusion experiment is difficult and the vertical structure of oceanic condition is complex, so that the research on vertical diffusion generally is not advanced yet. With river water as the tracer, a method of estimating vertical diffusion parameters with a Gaussian model or one-dimensional model was developed. The vertical diffusion near sea bottom was numerically analized with suspended particles in seawater as the tracer. Diffusion was computed for each particle size, and by summing up the vertical distribution of beam attenuation coefficient was estimated. By comparing the results of estimation and those of observation the vertical diffusivity and the particle size distribution at sea bottom could be estimated. (author)

  20. Throughflow and non-uniform heating effects on double diffusive oscillatory convection in a porous medium

    Directory of Open Access Journals (Sweden)

    Palle Kiran

    2016-03-01

    Full Text Available A weak nonlinear oscillatory mode of thermal instability is investigated while deriving a non autonomous complex Ginzburg–Landau equation. Darcy porous medium is considered in the presence of vertical throughflow and time periodic thermal boundaries. Only infinitesimal disturbances are considered. The disturbances in velocity, temperature and solutal fields are treated by a perturbation expansion in powers of amplitude of applied temperature field. The effect of throughflow has either to stabilize or to destabilize the system for stress free and isothermal boundary conditions. Nusselt and Sherwood numbers are obtained numerically and presented the results on heat and mass transfer. It is found that, throughflow and thermal modulation can be used alternatively to control the heat and mass transfer. Further, it is also found that oscillatory flow enhances the heat and mass transfer than stationary flow. Effect of modulation frequency and phase angle on mean Nusselt number is also discussed.

  1. The performance study of oxide by-passed(OB) lateral double diffused MOSFET

    Science.gov (United States)

    Tang, Pan-pan

    2016-10-01

    An SOI LDMOS device structure with Oxide By-passed(OB) was investigated and its breakdown mechanism and characteristic of structure was analyzed. Its performance was verified by 3D numerical simulation with SILVACO TCAD software. The simulated results show that the electrical field element of the device is modulated by the concept of similar Superjunction(SJ) structure. Compared with the SJ LDMOS device, OB LDMOS obtains the same breakdown voltage, simultaneously the specific on-resistance of the OB LDMOS reduces from 3.81mΩ·cm2 to 1.96mΩ·cm2, except for achieving comparable performance and overcoming the high aspect ratio of fabrication structure and the difficulty of accurate concentration match of SJ LDMOS.

  2. Influence of radiation on double conjugate diffusion in a porous cavity

    International Nuclear Information System (INIS)

    Azeem,; Idris, Mohd Yamani Idna; Khan, T. M. Yunus; Badruddin, Irfan Anjum; Nik-Ghazali, N.

    2016-01-01

    The current work highlights the effect of radiation on the conjugate heat and mass transfer in a square porous cavity having a solid wall. The solid wall is placed at the center of cavity. The left surface of cavity is maintained at higher temperature T_w and concentration C_w whereas the right surface is maintained at T_c and C_c such that T_w>T_c and Cw>Cc. The top and bottom surfaces are adiabatic. The governing equations are solved with the help of finite element method by making use of triangular elements. The results are discussed with respect to two different heights of solid wall inside the porous medium along with the radiation parameter.

  3. Influence of radiation on double conjugate diffusion in a porous cavity

    Energy Technology Data Exchange (ETDEWEB)

    Azeem,; Idris, Mohd Yamani Idna [Dept. of Computer System & Technology, University of Malaya, Kuala Lumpur (Malaysia); Khan, T. M. Yunus, E-mail: yunus.tatagar@gmail.com [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Dept. of Mechanical Engineering, BVB College of Engineering & Technology, Hubli (India); Badruddin, Irfan Anjum, E-mail: irfan-magami@Rediffmail.com; Nik-Ghazali, N. [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia)

    2016-05-06

    The current work highlights the effect of radiation on the conjugate heat and mass transfer in a square porous cavity having a solid wall. The solid wall is placed at the center of cavity. The left surface of cavity is maintained at higher temperature T{sub w} and concentration C{sub w} whereas the right surface is maintained at T{sub c} and C{sub c} such that T{sub w}>T{sub c} and Cw>Cc. The top and bottom surfaces are adiabatic. The governing equations are solved with the help of finite element method by making use of triangular elements. The results are discussed with respect to two different heights of solid wall inside the porous medium along with the radiation parameter.

  4. On the resistances of membrane, diffusion boundary layer and double layer in ion exchange membrane transport

    NARCIS (Netherlands)

    Długołȩcki, P.; Ogonowski, P.; Metz, S.J.; Saakes, M.; Nijmeijer, K.; Wessling, M.

    2010-01-01

    Membrane resistances are often measured under direct current conditions using a standard 0.5 M NaCl characterization solution, although several electro-membrane processes (e.g. reverse electrodialysis, electrodialysis, fuel cells, microbial fuel cells and membrane capacitive deionization) operate in

  5. Diffusion coefficients-surface and interfacial tensions - Particular study of some lauryl compounds

    International Nuclear Information System (INIS)

    Morel, Jean-Emile

    1969-01-01

    Two important results of the double lipophilic and hydrophilic character of some heavy organic compounds with a polar group at the end of the chain, were studied: - In a first part, molecular diffusion coefficients were measured in order to prove the micellar aggregation of tri-laurylammonium nitrate in some organic solutions; - In a second part, the tensioactivity of some lauryl compounds (lauric acid, lauric alcohol, mono-laurylamine, etc.), was studied. (author) [fr

  6. Flame structure of methane inverse diffusion flame

    KAUST Repository

    Elbaz, Ayman M.

    2014-07-01

    This paper presents high speed images of OH-PLIF at 10. kHz simultaneously with 2D PIV (particle image velocimetry) measurements collected along the entire length of an inverse diffusion flame with circumferentially arranged methane fuel jets. For a fixed fuel flow rate, the central air jet Re was varied, leading to four air to fuel velocity ratios, namely Vr = 20.7, 29, 37.4 and 49.8. A double flame structure could be observed composed of a lower fuel entrainment region and an upper mixing and intense combustion region. The entrainment region was enveloped by an early OH layer, and then merged through a very thin OH neck to an annular OH layer located at the shear layer of the air jet. The two branches of this annular OH layer broaden as they moved downstream and eventfully merged together. Three types of events were observed common to all flames: breaks, closures and growing kernels. In upstream regions of the flames, the breaks were counterbalanced by flame closures. These breaks in OH signal were found to occur at locations where locally high velocity flows were impinging on the flame. As the Vr increased to 37.4, the OH layers became discontinuous over the downstream region of the flame, and these regions of low or no OH moved upstream. With further increases in Vr, these OH pockets act as flame kernels, growing as they moved downstream, and became the main mechanism for flame re-ignition. Along the flame length, the direction of the two dimensional principle compressive strain rate axis exhibited a preferred orientation of approximately 45° with respect to the flow direction. Moreover, the OH zones were associated with elongated regions of high vorticity. © 2013 Elsevier Inc.

  7. Form of multicomponent Fickian diffusion coefficients matrix

    International Nuclear Information System (INIS)

    Wambui Mutoru, J.; Firoozabadi, Abbas

    2011-01-01

    Highlights: → Irreversible thermodynamics establishes form of multicomponent diffusion coefficients. → Phenomenological coefficients and thermodynamic factors affect sign of diffusion coefficients. → Negative diagonal elements of diffusion coefficients matrix can occur in non-ideal mixtures. → Eigenvalues of the matrix of Fickian diffusion coefficients may not be all real. - Abstract: The form of multicomponent Fickian diffusion coefficients matrix in thermodynamically stable mixtures is established based on the form of phenomenological coefficients and thermodynamic factors. While phenomenological coefficients form a symmetric positive definite matrix, the determinant of thermodynamic factors matrix is positive. As a result, the Fickian diffusion coefficients matrix has a positive determinant, but its elements - including diagonal elements - can be negative. Comprehensive survey of reported diffusion coefficients data for ternary and quaternary mixtures, confirms that invariably the determinant of the Fickian diffusion coefficients matrix is positive.

  8. Tracer surface diffusion on UO2

    International Nuclear Information System (INIS)

    Zhou, S.Y.; Olander, D.R.

    1983-06-01

    Surface diffusion on UO 2 was measured by the spreading of U-234 tracer on the surface of a duplex diffusion couple consisting of wafers of depleted and enriched UO 2 joined by a bond of uranium metal

  9. Diffus lungesygdom hos børn

    DEFF Research Database (Denmark)

    Buchvald, Frederik; Nielsen, Kim G

    2014-01-01

    Diffuse lung disease in children represents a heterogeneous group of respiratory disorders with high morbidity and mortality. Typical features include tachypnoea, failure to thrive, diffuse radiological and histopathological abnormalities. Advances in genetics and pathophysiology, combined...

  10. Enhancing Rotational Diffusion Using Oscillatory Shear

    KAUST Repository

    Leahy, Brian D.; Cheng, Xiang; Ong, Desmond C.; Liddell-Watson, Chekesha; Cohen, Itai

    2013-01-01

    Taylor dispersion - shear-induced enhancement of translational diffusion - is an important phenomenon with applications ranging from pharmacology to geology. Through experiments and simulations, we show that rotational diffusion is also enhanced

  11. Long range diffusion of hydrogen in yttrium

    International Nuclear Information System (INIS)

    Anderson, I.S.; Scherrer, P.; Ross, D.K.

    1989-01-01

    The diffusion of H in single crystals of YH 0.2 is investigated by means of Quasielastic neutron scattering between 593 K and 695 K. Individual jump rates giving rise to long range and local diffusion are determined. (orig.)

  12. Theory and experiments on surface diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Silvestri, W.L.

    1998-11-01

    The following topics were dealt with: adatom formation and self-diffusion on the Ni(100) surface, helium atom scattering measurements, surface-diffusion parameter measurements, embedded atom method calculations.

  13. Solubility and diffusivity of hydrogen in complex materials

    International Nuclear Information System (INIS)

    Kirchheim, R.

    2001-01-01

    A general model based on Statistical Mechanics and Random Walk is presented which allows to describe the behavior of hydrogen in disordered systems, i.e. metallic glasses, amorphous silicon, nanocrystalline metals, deformed metals, disordered metallic solutions, and metallic multi layers. The various systems are specified by a lattice with an appropriate site energy disorder and a distribution of site transitions rates. Lattice sites are filled according to Fermi-Dirac Statistics because double occupancy is excluded. Thus the model is applicable to adsorption on heterogeneous surfaces or solutions of small particles in oxide glasses and polymers. With a given distribution of site energies a relationship between chemical potential (Fermi energy) of hydrogen and its concentration can be derived and compared with experimental results. It is a unique feature of hydrogen that its chemical potential and its diffusion coefficient can be determined rather easily by electrochemical techniques or by measuring partial pressures at moderate temperatures around 300 K. With increasing H-content the sites are usually filled from lower to higher energies. As a consequence Henry's Law is not fulfilled and the diffusion coefficient increases because at high concentrations low energy sites are saturated and additional H-atoms have to perform their random walk through sites of low occupancy or small time of residence, respectively. Some results for metallic glasses, nanocrystalline metals, deformed metals, and metallic multi layers are presented and compared with the model. Thus information on the interaction between defects (dislocations, grain boundaries, distorted tetrahedral sites in glasses) and hydrogen are obtained. For extended defects the diffusion is strongly anisotropic, i.e. it differs in a Pd/Nb-multi layer by a factor of 10 5 for diffusion in plane and out of plane. (orig.)

  14. Double, Double Toil and Trouble: The Melt Inclusion Bubble

    Science.gov (United States)

    Rasmussen, D. J.; Plank, T. A.

    2017-12-01

    Melt inclusions provide a powerful means for probing the depth of magmatic processes and volatile budgets of magmas. Both objectives require that the inclusions accurately record the volatile content of the entrapped melt. However, post-entrapment cooling and diffusive loss of water lead to a decrease in internal pressure, resulting in volatile exsolution (importantly CO2) and vapor bubble growth in inclusions. Several methods have been developed recently that attempt to reconstruct the entrapped CO2 contents, but the methods yield inconsistent results. Here we report on new homogenization experiments and attempt to reconcile inconsistencies in CO2 reconstruction methods. Experiments were conducted on olivine-hosted melt inclusions from Seguam volcano using a piston cylinder apparatus at 500 MPa, 1150-1170 °C, hydrous conditions, and a run duration of 1-2 hours. FTIR analyses of the homogenized inclusions show some diffusive water gain (≤1 wt% excess) relative to unheated inclusions (most 4 wt%). Inclusions from this same sample were previously reconstructed using Raman addition (RA; Moore et al., 2015), and we have constituted the CO2 with two different computational approaches: the ideal gas law (IGL; Shaw et al., 2010) and a bubble growth model (BG; Riker, 2005). CO2 and S contents of heated inclusions are correlated, defining a S-CO2 degassing path. Relative to this empirical degassing path, IGL results are offset to higher CO2 (100s-1000s of ppm) or lower S (100s of ppm), while RA and BG results overlap and are offset to lower CO2 (≤100s of ppm) or higher S (≤100s of ppm). Because S contents of heated and unheated inclusions have similar ranges, we attribute the discrepancy to CO2. High values of CO2 from the IGL correction may be because CO2 diffusion cannot keep pace with bubble growth during rapid cooling upon eruption. Mass balance calculations indicate that a minute amount of carbonate, which could escape detection by Raman, would affect CO2

  15. Sorption kinetics of polycyclic aromatic hydrocarbons removal using granular activated carbon: Intraparticle diffusion coefficients

    International Nuclear Information System (INIS)

    Valderrama, C.; Gamisans, X.; Heras, X. de las; Farran, A.; Cortina, J.L.

    2008-01-01

    Granular activated carbon (GAC) was evaluated as a suitable sorbent for polycyclic aromatic hydrocarbons (PAHs) removal from aqueous solutions. For this purpose, kinetic measurements on the extraction of a family of six PAHs were taken. A morphology study was performed by means of a scanning electron microscopy (SEM) analysis of GAC samples. Analyses of the batch rate data for each PAH were carried out using two kinetic models: the homogenous particle diffusion model (HPDM) and the shell progressive model (SPM). The process was controlled by diffusion rate the solutes (PAHs) that penetrated the reacted layer at PAH concentrations in the range of 0.2-10 mg L -1 . The effective particle diffusion coefficients (D eff ) derived from the two models were determined from the batch rate data. The Weber and Morris intraparticle diffusion model made a double contribution to the surface and pore diffusivities in the sorption process. The D eff values derived from both the HPMD and SPM equations varied from 1.1 x 10 -13 to 6.0 x 10 -14 m 2 s -1 . The simplest model, the pore diffusion model, was applied first for data analysis. The model of the next level of complexity, the surface diffusion model, was applied in order to gain a deeper understanding of the diffusion process. This model is able to explain the data, and the apparent surface diffusivities are in the same order of magnitude as the values for the sorption of functionalized aromatic hydrocarbons (phenols and sulphonates) that are described in the literature

  16. Inverse diffusion theory of photoacoustics

    International Nuclear Information System (INIS)

    Bal, Guillaume; Uhlmann, Gunther

    2010-01-01

    This paper analyzes the reconstruction of diffusion and absorption parameters in an elliptic equation from knowledge of internal data. In the application of photoacoustics, the internal data are the amount of thermal energy deposited by high frequency radiation propagating inside a domain of interest. These data are obtained by solving an inverse wave equation, which is well studied in the literature. We show that knowledge of two internal data based on well-chosen boundary conditions uniquely determines two constitutive parameters in diffusion and Schrödinger equations. Stability of the reconstruction is guaranteed under additional geometric constraints of strict convexity. No geometric constraints are necessary when 2n internal data for well-chosen boundary conditions are available, where n is spatial dimension. The set of well-chosen boundary conditions is characterized in terms of appropriate complex geometrical optics solutions

  17. Massively parallel diffuse optical tomography

    Energy Technology Data Exchange (ETDEWEB)

    Sandusky, John V.; Pitts, Todd A.

    2017-09-05

    Diffuse optical tomography systems and methods are described herein. In a general embodiment, the diffuse optical tomography system comprises a plurality of sensor heads, the plurality of sensor heads comprising respective optical emitter systems and respective sensor systems. A sensor head in the plurality of sensors heads is caused to act as an illuminator, such that its optical emitter system transmits a transillumination beam towards a portion of a sample. Other sensor heads in the plurality of sensor heads act as observers, detecting portions of the transillumination beam that radiate from the sample in the fields of view of the respective sensory systems of the other sensor heads. Thus, sensor heads in the plurality of sensors heads generate sensor data in parallel.

  18. Devil's in the (diffuse) detail

    International Nuclear Information System (INIS)

    Welberry, R.

    2006-07-01

    X-ray crystallography is an important workhorse in the world of solid-state chemistry. However, while it's a powerful tool in determining the average structure in a crystal lattice, conventional crystallography is very limited when it comes to understanding nano-scale disorder within that crystal structure. And when it comes to understanding the properties of many important materials, the devil is in the detail. X-ray diffraction is still one of the keys to understanding this finer scale structure but using it requires a capacity to read between the lines - to understand the diffuse diffraction that most crystallography ignores. Scientists at the Research School of Chemistry are leading the world in this field. Their work on modelling nano-scaled disorder using diffuse diffraction is opening up new possibilities in understanding and modifying many of our most important materials

  19. Information filtering via preferential diffusion

    Science.gov (United States)

    Lü, Linyuan; Liu, Weiping

    2011-06-01

    Recommender systems have shown great potential in addressing the information overload problem, namely helping users in finding interesting and relevant objects within a huge information space. Some physical dynamics, including the heat conduction process and mass or energy diffusion on networks, have recently found applications in personalized recommendation. Most of the previous studies focus overwhelmingly on recommendation accuracy as the only important factor, while overlooking the significance of diversity and novelty that indeed provide the vitality of the system. In this paper, we propose a recommendation algorithm based on the preferential diffusion process on a user-object bipartite network. Numerical analyses on two benchmark data sets, MovieLens and Netflix, indicate that our method outperforms the state-of-the-art methods. Specifically, it can not only provide more accurate recommendations, but also generate more diverse and novel recommendations by accurately recommending unpopular objects.

  20. Oxygen diffusion in cuprate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Routbort, J.L.; Rothman, S.J.

    1995-01-01

    Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La{sub 2}{sub {minus}}{sub {times}}Sr{sub {times}}CuO{sub 4}, YBa{sub 2}Cu{sub 3}O{sub 7}{sub {minus}}{delta}, YBa{sub 2}Cu{sub 4}O{sub 8}, and the Bi{sub 2}Sr{sub 2}Ca{sub n}{sub {minus}}{sub 1}Cu{sub n}O{sub 2}{sub +}{sub 4} (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible.

  1. CT of diffuse pulmonary diseases

    International Nuclear Information System (INIS)

    Itoh, Harumi; Murata, Kiyoshi; Todo, Giro

    1987-01-01

    While the theory of chest radiographic interpretation in diagnosing diffuse pulmonary diseases has not yet been established, X-ray computed tomography (CT), having intrinsic high contrast resolution and improved spatial resolution, has proved to offer important imformation concerning the location and invasion of diffuse pulmonary lesions. This study related to CT-pathologic correlation, focusing on perivascular interstitial space and secondary pulmonary lobule at macroscopic levels. The perivascular interstitial space was thickened as a result of the infiltration of cancer, granulomas, and inflammatory cells. This finding appeared as irregular contour of the blood vessel on CT. Centrilobular nodules were distributed at the tip of the bronchus or pulmonary artery on CT. The distance from the terminal and respiratory bronchioles to the lobular border was 2 to 3 mm. Lobular lesions were delineated as clear margin on CT. Contribution of these CT features to chest radiographic interpretation must await further studies. (Namekawa, K.)

  2. Erbium diffusion in titanium dioxide

    Directory of Open Access Journals (Sweden)

    Louise Basse

    2017-04-01

    Full Text Available The diffusivity of erbium in the anatase phase of titanium dioxide (TiO2 has been studied for various temperatures ranging from 800 °C to 1, 000 °C. Samples of TiO2, with a 10 nm thick buried layer containing 0.5 at% erbium, were fabricated by radio-frequency magnetron sputtering and subsequently heat treated. The erbium concentration profiles were measured by secondary ion mass spectrometry, allowing for determination of the temperature-dependent diffusion coefficients. These were found to follow an Arrhenius law with an activation energy of ( 2.1 ± 0.2 eV. X-ray diffraction revealed that the TiO2 films consisted of polycrystalline grains of size ≈ 100 nm.

  3. Morphological inversion of complex diffusion

    Science.gov (United States)

    Nguyen, V. A. T.; Vural, D. C.

    2017-09-01

    Epidemics, neural cascades, power failures, and many other phenomena can be described by a diffusion process on a network. To identify the causal origins of a spread, it is often necessary to identify the triggering initial node. Here, we define a new morphological operator and use it to detect the origin of a diffusive front, given the final state of a complex network. Our method performs better than algorithms based on distance (closeness) and Jordan centrality. More importantly, our method is applicable regardless of the specifics of the forward model, and therefore can be applied to a wide range of systems such as identifying the patient zero in an epidemic, pinpointing the neuron that triggers a cascade, identifying the original malfunction that causes a catastrophic infrastructure failure, and inferring the ancestral species from which a heterogeneous population evolves.

  4. Boundary fluxes for nonlocal diffusion

    Science.gov (United States)

    Cortazar, Carmen; Elgueta, Manuel; Rossi, Julio D.; Wolanski, Noemi

    We study a nonlocal diffusion operator in a bounded smooth domain prescribing the flux through the boundary. This problem may be seen as a generalization of the usual Neumann problem for the heat equation. First, we prove existence, uniqueness and a comparison principle. Next, we study the behavior of solutions for some prescribed boundary data including blowing up ones. Finally, we look at a nonlinear flux boundary condition.

  5. The generalized Airy diffusion equation

    Directory of Open Access Journals (Sweden)

    Frank M. Cholewinski

    2003-08-01

    Full Text Available Solutions of a generalized Airy diffusion equation and an associated nonlinear partial differential equation are obtained. Trigonometric type functions are derived for a third order generalized radial Euler type operator. An associated complex variable theory and generalized Cauchy-Euler equations are obtained. Further, it is shown that the Airy expansions can be mapped onto the Bessel Calculus of Bochner, Cholewinski and Haimo.

  6. The Diffusion of Military Dictatorships

    OpenAIRE

    Raul Caruso; Ilaria Petrarca; Roberto Ricciuti

    2012-01-01

    We show the existence of a diffusion process of military dictatorships in Sub-Saharan Africa from 1972 through 2007, using panel data probit estimation and a Markov chain transition model. This process is shortly-lived, since we observe an overall trend that reduces the number of military regimes. We also find that Manufacturing share of GDP, Primary share of GDP positively affect the probability of military dictatorship, and Openness to trade, whereas the British colonial origin are negative...

  7. Composite interlayer for diffusion bonding

    International Nuclear Information System (INIS)

    1976-01-01

    A ductile interlayer is described, which is useful for transient liquid phase diffusion bonding of metallic articles; the interlayer consisting of a melting point depressant and a plurality of ductile lamellae which are free from carbides, aluminides and borides. The composition and fabrication of the lamellae, and the process for bonding the metallic articles, depend on the composition of the metals to be bonded, and are exemplified in the specification. (U.K.)

  8. Atmospheric horizontal divergence and diffusion

    International Nuclear Information System (INIS)

    Castans, M.

    1981-01-01

    The action of horizontal divergence on diffusion near the ground is established through.a very simple flow model. The shape of the well-known Pasquill-Gifford-Turner curves, that apparently take account in some way of divergence, is justified. The possibility of explaining the discre--pancies between the conventional straight line model and experimental results, mainly under low-wind-speed satable conditions, is considered. Some hints for further research are made. (auth.)

  9. Diffusion processes in dyed detectors

    International Nuclear Information System (INIS)

    Lferde, M.; Seidel, J.-L.; Monnin, M.

    1982-01-01

    In order to get a better understanding of the dyed and fluorescent track detectors, the diffusion speed of the swelling agent, the sensitization molecules and the dye have been measured under various conditions. It is shown that the sensitization affects the entire detector while dyeing is restricted to the upper and lower layers of the detector. By combining the optimal values of the reactions parameters a higher contrast and sensitivity may be achieved. (author)

  10. Diffuse Cosmic Infrared Background Radiation

    Science.gov (United States)

    Dwek, Eli

    2002-01-01

    The diffuse cosmic infrared background (CIB) consists of the cumulative radiant energy released in the processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In this lecture I will review the observational data that provided the first detections and limits on the CIB, and the theoretical studies explaining the origin of this background. Finally, I will also discuss the relevance of this background to the universe as seen in high energy gamma-rays.

  11. Who is entitled to double effect?

    Science.gov (United States)

    Boyle, J

    1991-10-01

    The doctrine of double effect continues to be an important tool in bioethical casuistry. Its role within the Catholic moral tradition continues, and there is considerable interest in it by contemporary moral philosophers. But problems of justification and correct application remain. I argue that if the traditional Catholic conviction that there are exceptionless norms prohibiting inflicting some kinds of harms on people is correct, then double effect is justified and necessary. The objection that double effect is superfluous is a rejection of that normative conviction, not a refutation of double effect itself. This justification suggests the correct way of applying double effect to controversial cases. But versions of double effect which dispense with the absolutism of the Catholic tradition lack justification and fall to the objection that double effect is an unnecessary complication.

  12. Diffusion in ordered binary solid systems

    International Nuclear Information System (INIS)

    Stolwijk, N.A.

    1980-01-01

    This thesis contains contributions to the field of diffusion in ordered binary solid systems. An extensive experimental investigation of the self diffusion in CoGa is presented. The results of these diffusion measurements strongly suggest that a substantial part of the atomic migration is caused by a new type of defect. A quantitative description of the atomic displacements via this defect is given. Finally computer simulations are presented of diffusion and ordering in binary solid systems. (Auth.)

  13. Strong Stationary Duality for Diffusion Processes

    OpenAIRE

    Fill, James Allen; Lyzinski, Vince

    2014-01-01

    We develop the theory of strong stationary duality for diffusion processes on compact intervals. We analytically derive the generator and boundary behavior of the dual process and recover a central tenet of the classical Markov chain theory in the diffusion setting by linking the separation distance in the primal diffusion to the absorption time in the dual diffusion. We also exhibit our strong stationary dual as the natural limiting process of the strong stationary dual sequence of a well ch...

  14. The Adoption and Diffusion of Service Products

    OpenAIRE

    Myung Joong Kwon

    2003-01-01

    The objective of this paper is to theoretically explore the innovation, adoption and diffusion of service product. A theoretical model of the diffusion of service product is developed that takes account of transportation, waiting and searching casts in the adoption of service product. The main results of the model are; (1) the diffusion of service product is slower than that of the manufacturing equivalent and (2) the delivery or retail distribution service speeds up the diffusion of the manu...

  15. Evaluation of neutron streaming in fast breeder reactor fuel assembly by double heterogeneous modelling

    International Nuclear Information System (INIS)

    Unesaki, Hironobu; Takeda, Toshikazu

    1988-01-01

    Neutron streaming in a fast breeder reactor fuel assembly caused by the double heterogeneity structure is estimated by double heterogeneous modelling. The conventional pin cell model, a two-region subassembly model and the exact pin cluster model are used to take into account the streaming effect caused by the pin cell structure and the surrounding wrapper tube structure. The heterogeneity of wrapper tube and its surrounding sodium is explicitly considered. The streaming effect is evaluated based on Benoist's diffusion coefficient. The total streaming effect caused by the double heterogeneity structure of a fuel subassembly is found to be -0.2 % dk/kk' for k eff , which is almost twice that obtained from the conventional pin cell model of -0.1 % dk/kk'. (author)

  16. Solutes transport in unsaturated double-porosity medium. Modelling by homogenization and applications

    International Nuclear Information System (INIS)

    Tran Ngoc, T.D.

    2008-07-01

    This Ph.D thesis presents the development of the solute transport models in unsaturated double-porosity medium, by using the asymptotic homogenization method. The obtained macroscopic models concern diffusion, diffusion-convection and dispersion-convection, according to the transport regime which is characterized by the non-dimensional numbers. The models consist of two coupled equations that show the local non-equilibrium of concentrations. The double-porosity transport models were numerically implemented using the code COMSOL Multiphysics (finite elements method), and compared with the solution of the same problem at the fine scale. The implementation allows solving the coupled equations in the macro- and micro-porosity domains (two-scale computations). The calculations of the dispersion tensor as a solution of the local boundary value problems, were also conducted. It was shown that the dispersivity depends on the saturation, the physical properties of the macro-porosity domain and the internal structure of the double-porosity medium. Finally, two series of experiments were performed on a physical model of double-porosity that is composed of a periodic assemblage of sintered clay spheres in Hostun sand HN38. The first experiment was a drainage experiment, which was conducted in order to validate the unsaturated flow model. The second series was a dispersion experiment in permanent unsaturated water flow condition (water content measured by gamma ray attenuation technique). A good agreement between the numerical simulations and the experimental observations allows the validation of the developed models. (author)

  17. Diffuse Deckenlüftung

    DEFF Research Database (Denmark)

    Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

    Richtung in den Raum geleitet (daher auch der Namensteil „diffus“). Im Vergleich zu herkömmlichen Lüftungsanlagen (Misch- oder Verdrängungslüftung) kann die diffuse Deckenlüftung das Risiko eines Luftzugs im Raum erheblich reduzieren oder sogar vermeiden. Darüber hinaus bietet diese Lüftungsanlage die...... vielversprechende Möglichkeit, Energie einzusparen. Dies liegt am geringen Druckverlust, an dem längeren Zeitraum der freien Kühlung und dem großen Potenzial der Nachtkühlung. Die Investitionskosten für eine Anlage für die diffuse Deckenlüftung sind 5 bis 10 % geringer als die für herkömmliche Anlagen, da die...... Akustikdecke direkt als Luftverteiler verwendet werden kann. Durch den Einsatz eines Hohlraums für die Luftverteilung fallen zudem auch die Kosten für Luftkanäle niedriger aus. Das Interesse daran, die diffuse Deckenlüftung in Büros und anderen Gewerbegebäuden einzusetzen, wächst aufgrund der Vorteile in Bezug...

  18. Mathematical methods for diffusion MRI processing

    International Nuclear Information System (INIS)

    Lenglet, C.; Lenglet, C.; Sapiro, G.; Campbell, J.S.W.; Pike, G.B.; Campbell, J.S.W.; Siddiqi, K.; Descoteaux, M.; Haro, G.; Wassermann, D.; Deriche, R.; Wassermann, D.; Anwander, A.; Thompson, P.M.

    2009-01-01

    In this article, we review recent mathematical models and computational methods for the processing of diffusion Magnetic Resonance Images, including state-of-the-art reconstruction of diffusion models, cerebral white matter connectivity analysis, and segmentation techniques. We focus on Diffusion Tensor Images (DTI) and Q-Ball Images (QBI). (authors)

  19. On the Aharonov-Bohm diffusion

    International Nuclear Information System (INIS)

    Dasnieres de Veigy, A.; Ouvry, S.; Paris-6 Univ., 75

    1993-07-01

    The diffusion of a charged particle by a singular flux tube is revisited. A simple and rigourous derivation shows that the action of the propagator on an incident plane wave precisely yields the Aharonov-Bohm diffusion amplitude. The forward diffusion is discussed as well as the singularity of the interaction at the position of the flux tube. (orig.)

  20. Oxygen diffusion in glasses and ceramic materials

    International Nuclear Information System (INIS)

    Kolitsch, A.; Richter, E.; Wolf, M.

    1978-10-01

    A survey is given on the published works to study oxygen diffusion in glasses and ceramic materials in the last years. In the first part methods are described for the measurement of oxygen diffusion coefficients and in the second part the published reports on oxygen diffusion in glasses, ceramic and other oxides are discussed. The most important results are summarized in different tables. (author)