WorldWideScience

Sample records for electric flux tube

  1. J/\\psi-dissociation by a color electric flux tube

    OpenAIRE

    Loh, S.; Greiner, C.; Mosel, U.

    1997-01-01

    We adress the question of how a $c-\\bar{c}$-state (a $J/\\psi $) can be dissociated by the strong color electric fields when moving through a color electric flux tube. The color electric flux tube and the dissociation of the heavy quarkonia state are both described within the Friedberg-Lee color dielectric model. We speculate on the importance of such an effect with respect to the observed $J/\\psi $-suppression in ultrarelativistic heavy ion collisions.

  2. Lifetime of electric flux tubes near the QCD phase transition

    International Nuclear Information System (INIS)

    Faroughy, Cyrus; Shuryak, Edward

    2010-01-01

    Electric flux tubes are a well-known attribute of the quantum chromodynamic (QCD) vacuum in which they manifest confinement of electric color charges. Recently, experimental results appeared which suggest that not only do those objects persist at temperatures T≅T c near the QCD phase transitions, but their decay is suppressed and the resulting clusters in Au-Au collisions are larger than in pp collisions (i.e., in vacuum). This correlates well with recent theoretical scenarios that view the QCD matter in the T≅T c region as a dual-magnetic plasma dominated by color-magnetic monopoles. In this view, the flux tubes are stabilized by dual-magnetic currents and are described by dual magnetohydrodynamics (DMHD). In this article, we calculate classically the dissipative effects in the flux tube. Such effects are associated with rescattering and finite conductivity of the matter. We derive the DMHD solution in the presence of dissipation and then estimate the lifetime of the electric flux tubes. The conclusion of this study is that a classical treatment leads to too short of a lifetime for the flux tubes.

  3. Duality of the magnetic flux tube and electric current descriptions magnetospheric plasma and energy flow

    International Nuclear Information System (INIS)

    Atkinson, G.

    1981-01-01

    The duality between electric current and magnetic flux tubes is outlined for the magnetosphere. Magnetic flux tubes are regarded as fluid elements subjected to various stresses. Current closure then becomes the dual of stress balance, and Poynting vector energy flow a dual of J x E dissipation. The stresses acting on a flux tube are magnetic stresses, which correspond to currents at a distance, and plasma stresses, which correspond to local currents. The duality between current and stress is traced for ionospheric ion drag forces, solar wind stresses at the magnetopause, inertial effects, and the effects of energetic plasma on flux tubes. The stress balance and dual current systems are outlined for idealized magnetospheres of increasing complexity. For a simple magnetosphere with no convective flow, the balance stresses are solar wind pressure and neutral sheet plasma pressure. The corresponding current systems are the Chapman-Ferraro magnetopause currents and the magetotail current system. The introduction of convective flow introduces further stresses: ionospheric ion drag. Alfven layer shielding, and an imbalance in day-night magnetic stresses due to transport of flux tubes to the nightside by the solar wind. These stresses balance, and hence the corresponding additional currents (the ionospheric Pedersen current and the electrojets, the partial ring current, and two other current systems from the magnetopause and tail) must form a closed current system and do so by the region I and II field-aligned currents of Iijima and Potemra. The energy flow in the above models is described in terms of both Poynting vectors and the above current systems. Temporal variations examined are (1) an increase in dayside merging and/or nightside reconnection, (2) an increase in the energy density of plasma in the plasma sheet, (3) an increase in ionospheric conductivity, and (4) an increase in solar wind pressure

  4. Flux Tube Dynamics in the Dual Superconductor

    International Nuclear Information System (INIS)

    Lampert, M.; Svetitsky, B.

    1999-01-01

    We have studied plasma oscillations in a flux tube created in a dual superconductor. The theory contains an Abelian gauge field coupled magnetically to a Higgs field that confines electric charge via the dual Meissner effect. Starting from a static flux tube configuration, with electric charges at either end, we release a fluid of electric charges in the system that accelerate and screen the electric field. The weakening of the electric field allows the flux tube to collapse, and the inertia of the charges forces it open again. We investigate both Type I and Type II superconductors, with plasma frequencies both above and below the threshold for radiation into the Higgs vacuum. (The parameters appropriate to QCD are in the Type II regime; the plasma frequency depends on the mass taken for the fluid constituents.) The coupling of the plasma oscillations to the Higgs field making up the flux tube is the main new feature in our work

  5. Flux tubes at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Cea, Paolo [INFN, Sezione di Bari,Via G. Amendola 173, I-70126 Bari (Italy); Dipartimento di Fisica dell’Università di Bari,Via G. Amendola 173, I-70126 Bari (Italy); Cosmai, Leonardo [INFN, Sezione di Bari,Via G. Amendola 173, I-70126 Bari (Italy); Cuteri, Francesca; Papa, Alessandro [Dipartimento di Fisica, Università della Calabria & INFN-Cosenza,Ponte Bucci, cubo 31C, I-87036 Rende (Cosenza) (Italy)

    2016-06-07

    The chromoelectric field generated by a static quark-antiquark pair, with its peculiar tube-like shape, can be nicely described, at zero temperature, within the dual superconductor scenario for the QCD confining vacuum. In this work we investigate, by lattice Monte Carlo simulations of the SU(3) pure gauge theory, the fate of chromoelectric flux tubes across the deconfinement transition. We find that, if the distance between the static sources is kept fixed at about 0.76 fm ≃1.6/√σ and the temperature is increased towards and above the deconfinement temperature T{sub c}, the amplitude of the field inside the flux tube gets smaller, while the shape of the flux tube does not vary appreciably across deconfinement. This scenario with flux-tube “evaporation” above T{sub c} has no correspondence in ordinary (type-II) superconductivity, where instead the transition to the phase with normal conductivity is characterized by a divergent fattening of flux tubes as the transition temperature is approached from below. We present also some evidence about the existence of flux-tube structures in the magnetic sector of the theory in the deconfined phase.

  6. Observation of a Coulomb flux tube

    Science.gov (United States)

    Greensite, Jeff; Chung, Kristian

    2018-03-01

    In Coulomb gauge there is a longitudinal color electric field associated with a static quark-antiquark pair. We have measured the spatial distribution of this field, and find that it falls off exponentially with transverse distance from a line joining the two quarks. In other words there is a Coulomb flux tube, with a width that is somewhat smaller than that of the minimal energy flux tube associated with the asymptotic string tension. A confinement criterion for gauge theories with matter fields is also proposed.

  7. Physics of magnetic flux tubes

    CERN Document Server

    Ryutova, Margarita

    2015-01-01

    This book is the first account of the physics of magnetic flux tubes from their fundamental properties to collective phenomena in an ensembles of flux tubes. The physics of magnetic flux tubes is absolutely vital for understanding fundamental physical processes in the solar atmosphere shaped and governed by magnetic fields. High-resolution and high cadence observations from recent space and  ground-based instruments taken simultaneously at different heights and temperatures not only show the ubiquity of filamentary structure formation but also allow to study how various events are interconnected by system of magnetic flux tubes. The book covers both theory and observations. Theoretical models presented in analytical and phenomenological forms are tailored for practical applications. These are welded with state-of-the-art observations from early decisive ones to the most recent data that open a new phase-space for exploring the Sun and sun-like stars. Concept of magnetic flux tubes is central to various magn...

  8. Models of Flux Tubes from Constrained Relaxation

    Indian Academy of Sciences (India)

    tribpo

    Equilibria corresponding to the energy extrema while conserving these invariants for parallel flows yield three classes of ... parallel heat flux, due to the boundary condition Β · n = 0, that the total energy, is conserved. In all HR, K, S, and the total mass, ... Zero net current flux tubes are qualitatively similar to the flux tube with ...

  9. Solitary wave propagation in solar flux tubes

    International Nuclear Information System (INIS)

    Erdelyi, Robert; Fedun, Viktor

    2006-01-01

    The aim of the present work is to investigate the excitation, time-dependent dynamic evolution, and interaction of nonlinear propagating (i.e., solitary) waves on vertical cylindrical magnetic flux tubes in compressible solar atmospheric plasma. The axisymmetric flux tube has a field strength of 1000 G at its footpoint, which is typical for photospheric regions. Nonlinear waves that develop into solitary waves are excited by a footpoint driver. The propagation of the nonlinear signal is investigated by solving numerically a set of fully nonlinear 2.0D magnetohydrodynamic (MHD) equations in cylindrical coordinates. For the initial conditions, axisymmetric solutions of the linear dispersion relation for wave modes in a magnetic flux tube are applied. In the present case, we focus on the sausage mode only. The dispersion relation is solved numerically for a range of plasma parameters. The equilibrium state is perturbed by a Gaussian at the flux tube footpoint. Two solitary solutions are found by solving the full nonlinear MHD equations. First, the nonlinear wave propagation with external sound speed is investigated. Next, the solitary wave propagating close to the tube speed, also found in the numerical solution, is studied. In contrast to previous analytical and numerical works, here no approximations were made to find the solitary solutions. A natural application of the present study may be spicule formation in the low chromosphere. Future possible improvements in modeling and the relevance of the photospheric chromospheric transition region coupling by spicules is suggested

  10. Models of Flux Tubes from Constrained Relaxation

    Indian Academy of Sciences (India)

    tribpo

    J. Astrophys. Astr. (2000) 21, 299 302. Models of Flux Tubes from Constrained Relaxation. Α. Mangalam* & V. Krishan†, Indian Institute of Astrophysics, Koramangala,. Bangalore 560 034, India. *e mail: mangalam @ iiap. ernet. in. † e mail: vinod@iiap.ernet.in. Abstract. We study the relaxation of a compressible plasma to ...

  11. Color magnetic flux tubes in dense QCD

    International Nuclear Information System (INIS)

    Eto, Minoru; Nitta, Muneto

    2009-01-01

    QCD is expected to be in the color-flavor locking phase in high baryon density, which exhibits color superconductivity. The most fundamental topological objects in the color superconductor are non-Abelian vortices which are topologically stable color magnetic flux tubes. We present numerical solutions of the color magnetic flux tube for diverse choices of the coupling constants based on the Ginzburg-Landau Lagrangian. We also analytically study its asymptotic profiles and find that they are different from the case of usual superconductors. We propose the width of color magnetic fluxes and find that it is larger than naive expectation of the Compton wavelength of the massive gluon when the gluon mass is larger than the scalar mass.

  12. Dynamical Processes in Flux Tubes and their Role in ...

    Indian Academy of Sciences (India)

    We model the dynamical interaction between magnetic flux tubes and granules in the solar photosphere which leads to the excitation of transverse (kink) and longitudinal (sausage) tube waves. The investigation is motivated by the interpretation of network oscillations in terms of flux tube waves. The calculations show that ...

  13. Properties of Flux Tubes and the Relation with Solar Irradiance ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... At the solar surface the magnetic field is bundled into discrete elements of concentrated flux, often referred to as magnetic flux tubes, which cover only a small fraction of the solar surface. Flux tubes span a whole spectrum of sizes, ranging from sunspots to features well below the best currently obtainable ...

  14. Simulations of fully deformed oscillating flux tubes

    Science.gov (United States)

    Karampelas, K.; Van Doorsselaere, T.

    2018-02-01

    Context. In recent years, a number of numerical studies have been focusing on the significance of the Kelvin-Helmholtz instability in the dynamics of oscillating coronal loops. This process enhances the transfer of energy into smaller scales, and has been connected with heating of coronal loops, when dissipation mechanisms, such as resistivity, are considered. However, the turbulent layer is expected near the outer regions of the loops. Therefore, the effects of wave heating are expected to be confined to the loop's external layers, leaving their denser inner parts without a heating mechanism. Aim. In the current work we aim to study the spatial evolution of wave heating effects from a footpoint driven standing kink wave in a coronal loop. Methods: Using the MPI-AMRVAC code, we performed ideal, three dimensional magnetohydrodynamic simulations of footpoint driven transverse oscillations of a cold, straight coronal flux tube, embedded in a hotter environment. We have also constructed forward models for our simulation using the FoMo code. Results: The developed transverse wave induced Kelvin-Helmholtz (TWIKH) rolls expand throughout the tube cross-section, and cover it entirely. This turbulence significantly alters the initial density profile, leading to a fully deformed cross section. As a consequence, the resistive and viscous heating rate both increase over the entire loop cross section. The resistive heating rate takes its maximum values near the footpoints, while the viscous heating rate at the apex. Conclusions: We conclude that even a monoperiodic driver can spread wave heating over the whole loop cross section, potentially providing a heating source in the inner loop region. Despite the loop's fully deformed structure, forward modelling still shows the structure appearing as a loop. A movie attached to Fig. 1 is available at http://https://www.aanda.org

  15. Benchmarking gyrokinetic simulations in a toroidal flux-tube

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Parker, S. E.; Wan, W. [University of Colorado at Boulder, Boulder, Colorado 80309 (United States); Bravenec, R. [Fourth-State Research, Austin, Texas 78704 (United States)

    2013-09-15

    A flux-tube model is implemented in the global turbulence code GEM [Y. Chen and S. E. Parker, J. Comput. Phys. 220, 839 (2007)] in order to facilitate benchmarking with Eulerian codes. The global GEM assumes the magnetic equilibrium to be completely given. The initial flux-tube implementation simply selects a radial location as the center of the flux-tube and a radial size of the flux-tube, sets all equilibrium quantities (B, ∇B, etc.) to be equal to the values at the center of the flux-tube, and retains only a linear radial profile of the safety factor needed for boundary conditions. This implementation shows disagreement with Eulerian codes in linear simulations. An alternative flux-tube model based on a complete local equilibrium solution of the Grad-Shafranov equation [J. Candy, Plasma Phys. Controlled Fusion 51, 105009 (2009)] is then implemented. This results in better agreement between Eulerian codes and the particle-in-cell (PIC) method. The PIC algorithm based on the v{sub ||}-formalism [J. Reynders, Ph.D. dissertation, Princeton University, 1992] and the gyrokinetic ion/fluid electron hybrid model with kinetic electron closure [Y. Chan and S. E. Parker, Phys. Plasmas 18, 055703 (2011)] are also implemented in the flux-tube geometry and compared with the direct method for both the ion temperature gradient driven modes and the kinetic ballooning modes.

  16. Structure of sunspot penumbrae - Fallen magnetic flux tubes

    Science.gov (United States)

    Wentzel, Donat G.

    1992-01-01

    A model is presented of a sunspot penumbra involving magnetic flux tubes that have fallen into the photosphere and float there. An upwelling at the inner end of a fallen tube continuously provides additional gas. This gas flows along and lengthens the tube and is observable as the Evershed flow. Fallen flux tubes may appear as bright streaks near the upwelling, but they become dark filaments further out. The model is corroborated by recent optical high-resolution magnetic data regarding the penumbral filaments, by the 12-micron magnetic measurements relevant to the height of the temperature minimum, and by photographs of the umbra/penumbra boundary.

  17. Fluting Modes in Transversely Nonuniform Solar Flux Tubes

    Science.gov (United States)

    Soler, Roberto

    2017-12-01

    Magnetohydrodynamic waves of different types are frequently observed in magnetic flux tubes of the solar atmosphere and are often modeled using simple models. In the standard flux tube model made of a straight uniform tube with an abrupt boundary, transverse wave modes are classified according to their azimuthal wavenumber, m. Sausage (m = 0) and kink (m = 1) modes produce pulsations of the cross section and transverse oscillations of tube axis, respectively. Both sausage and kink modes have been observed in the solar atmosphere. Fluting (m≥slant 2) modes produce perturbations that are essentially confined around the boundary of the tube, I.e., they have a strong surface-like character. Unlike sausage and kink modes, the detection of fluting modes remains elusive. Here we show that the inclusion of transverse inhomogeneity in the flux tube model dramatically affects the properties of fluting modes. Even in a thin tube, kink and fluting modes are no longer degenerate in frequency when the tube has a smooth boundary. In addition, fluting modes become heavily damped by resonant absorption in a timescale shorter than the oscillation period. The perturbations loose their global shape and their distinctive surface-like appearance. As a consequence of that, we argue that nonuniform flux tubes with smooth boundaries may not be able to support fluting-like perturbations as coherent, global modes.

  18. MHD Sausage Waves in Compressible Magnetically Twisted Flux Tubes

    Science.gov (United States)

    Fedun, Viktor

    Recent high-resolution satellites clearly prove the existence of various types of theoretically predicted MHD waves in solar atmospheric magnetic structures (loops, arcades ets). Oscillations of magnetic flux tubes are of great importance as they contain information about the geometry and fine structure of the flux tubes. In this work we study the details of the effects caused by the presence of magnetic twist in flux tubes. The propagation of surface and body linear MHD modes in a twisted magnetic flux tube embedded in a magnetically twisted plasma environment is considered. We derive and analytically solve the linear governing equations of wave propagation for sausage surface and body modes of a magnetically-twisted compressible flux tube embedded in a compressible uniformly-magnetized plasma environment in cylindrical geometry in terms of Kummer's functions. Numerical solutions for the phase velocity are obtained for a wide range of wavenumbers and for varying magnetic twist. The effect of magnetic twist on the period of oscillations of sausage surface modes for different values of the wavenumber and vertical magnetic field strength is calculated for representative photospheric and coronal conditions. These results generalize and extend previous studies of MHD waves obtained for incompressible or compressible but non-twisted flux tubes. It is found that magnetic twist may change the period of sausage surface waves by the order of a few per cent when compared to counterparts in straight non-twisted flux tubes. This information will be most relevant, when high-resolution observations are used for diagnostic exploration of MHD wave guides in analogy to solar-interior studies by means of global eigenoscillations in helioseismology. Further detailed analysis is necessary in order to find the dispersion relation for more realistic cases, where the magnetic twist diminishes with distance from the tube. Finally, observational relevances will be discussed in light of the

  19. Formation and dynamics of a solar eruptive flux tube

    Science.gov (United States)

    Inoue, Satoshi; Kusano, Kanya; Büchner, Jörg; Skála, Jan

    2018-01-01

    Solar eruptions are well-known drivers of extreme space weather, which can greatly disturb the Earth's magnetosphere and ionosphere. The triggering process and initial dynamics of these eruptions are still an area of intense study. Here we perform a magnetohydrodynamic simulation taking into account the observed photospheric magnetic field to reveal the dynamics of a solar eruption in a real magnetic environment. In our simulation, we confirmed that tether-cutting reconnection occurring locally above the polarity inversion line creates a twisted flux tube, which is lifted into a toroidal unstable area where it loses equilibrium, destroying the force-free state, and driving the eruption. Consequently, a more highly twisted flux tube is built up during this initial phase, which can be further accelerated even when it returns to a stable area. We suggest that a nonlinear positive feedback process between the flux tube evolution and reconnection is the key to ensure this extra acceleration.

  20. Dynamical Processes in Flux Tubes and their Role in ...

    Indian Academy of Sciences (India)

    tribpo

    tubes and granules in the solar photosphere which leads to the excitation of transverse (kink) and longitudinal ... the energy flux in transverse waves is calculated and the implications for chromospheric heating are ... highly dynamical state, due to the buffeting effect of random convective motions. (e.g., Müller 1983; Muller et ...

  1. Guided flows in coronal magnetic flux tubes

    Science.gov (United States)

    Petralia, A.; Reale, F.; Testa, P.

    2018-01-01

    Context. There is evidence that coronal plasma flows break down into fragments and become laminar. Aims: We investigate this effect by modelling flows confined along magnetic channels. Methods: We consider a full magnetohydrodynamic (MHD) model of a solar atmosphere box with a dipole magnetic field. We compare the propagation of a cylindrical flow perfectly aligned with the field to that of another flow with a slight misalignment. We assume a flow speed of 200 km s-1 and an ambient magnetic field of 30 G. Results: We find that although the aligned flow maintains its cylindrical symmetry while it travels along the magnetic tube, the misaligned one is rapidly squashed on one side, becoming laminar and eventually fragmented because of the interaction and back-reaction of the magnetic field. This model could explain an observation made by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory of erupted fragments that fall back onto the solar surface as thin and elongated strands and end up in a hedge-like configuration. Conclusions: The initial alignment of plasma flow plays an important role in determining the possible laminar structure and fragmentation of flows while they travel along magnetic channels. Movies are available in electronic form at http://www.aanda.org

  2. Demystifying Electric Flux and Gauss's Law

    Science.gov (United States)

    McManus, Jeff

    2017-01-01

    Many physics students have experienced the difficulty of internalizing concepts in electrostatics. After studying concrete, measurable details in mechanics, they are challenged by abstract ideas such as electric fields, flux, Gauss's law, and electric potential. There are a few well-known hands-on activities that help students get experience with…

  3. The flow distribution in the parallel tubes of the cavity receiver under variable heat flux

    International Nuclear Information System (INIS)

    Hao, Yun; Wang, Yueshe; Hu, Tian

    2016-01-01

    Highlights: • An experimental loop is built to find the flow distribution in the parallel tubes. • With the concentration of heat flux, two-phase flow makes distribution more uneven. • The total flow rate is chosen appropriately for a wider heat flux distribution. • A suitable system pressure is essential for the optimization of flow distribution. - Abstract: As an optical component of tower solar thermal power station, the heliostat mirror reflects sunlight to one point of the heated surface in the solar cavity receiver, called as one-point focusing system. The radiation heat flux concentrated in the cavity receiver is always non-uniform temporally and spatially, which may lead to extremely local over-heat on the receiver evaporation panels. In this paper, an electrical heated evaporating experimental loop, including five parallel vertical tubes, is set up to evaluate the hydrodynamic characteristics of evaporation panels in a solar cavity receiver under various non-uniform heat flux. The influence of the heat flux concentration ratio, total flow rate, and system pressure on the flow distribution of parallel tubes is discussed. It is found that the flow distribution becomes significantly worse with the increase of heat flux and concentration ratio; and as the system pressure decreased, the flow distribution is improved. It is extremely important to obtain these interesting findings for the safe and stable operation of solar cavity receiver, and can also provide valuable references for the design and optimization of operating parameters solar tower power station system.

  4. Nonlinear wave time dependent dynamic evolution in solar flux tubes

    Science.gov (United States)

    Fedun, V.; Erdelyi, R.

    2005-12-01

    The aim of the present work is to investigate the excitation, time dependent dynamic evolution and interaction of weakly nonlinear propagating (i.e. solitary) waves on vertical cylindrical magnetic flux tubes in a compressible solar atmospheric plasma. The axisymmetric flux tube has a field strength of 1000 G at its footpoint what is typical for photospheric regions. Solitons are excited by a footpoint driver. The propagation of the nonlinear signal is investigated by solving numerically a set of fully nonlinear 2D MHD equations in cylindrical coordinates. For the initial conditions the solutions of the linear dispersion relation for wave modes (in the present case we focus on the sausage mode) in a magnetic flux tube is applied. This dispersion relation is solved numerically for a range of plasma parameters. We compare our results with the works of Roberts [1], Wilson [2] (dispersion relation), Molotovshchikov [3] (nonlinear slow sausage waves) and Weisshaar [4] (numerical solutions of the Leibovich-Prichard-Roberts equation). (1) We found solitary solutions and investigate solitary propagating with external sound speed by solving the full MHD equations. (2) We also found a solitary wave propagating with the tube speed. A natural application of our studies may be spicule formation in the chromosphere, as suggested by Roberts [5], where it was demonstrated theoretically, that a solar photospheric magnetic flux tube can support the propagation of solitons governed by the Benjamin-Ono (slow mode) equations. Future possible improvements in modeling and the relevance of the photospheric chromospheric transition region coupling by spicules is suggested. [1] B. Roberts and A. Webb, Sol. Phys., 1978, v. 56, p. 5 [2] P.R. Wilson, Astron. Astrophys., 1980, v. 87, p. 121 [3] A.L. Molotovshchikov and M.S. Ruderman, Sol. Phys., 1987, v. 109, p. 247 [4] E. Weisshaar, Phys. Fluids A, 1989, v. 1(8), p. 1406 [5] B. Roberts and A. Mangeney, Royal Astronomical Society, Monthly

  5. Critical heat flux variations on CANDU calandria tube surface

    Energy Technology Data Exchange (ETDEWEB)

    Behdadi, A.; Luxat, J.C., E-mail: behdada@mcmaster.ca, E-mail: luxatj@mcmaster.ca [McMaster Univ., Engineering Physics Dept., Hamilton, Ontario (Canada)

    2012-07-01

    Heavy water moderator surrounding each fuel channel is one of the important safety features in CANDU reactors since it provides an in-situ passive heat sink for the fuel in situations where other engineered means of heat removal from fuel channels have failed. In a critical break LOCA scenario, fuel cooling becomes severely degraded due to rapid flow reduction in the affected flow pass of the heat transport system. This can result in pressure tubes experiencing significant heat-up during early stages of the accident when coolant pressure is still high, thereby causing uniform thermal creep strain (ballooning) of the pressure tube (PT) into contact with its calandria tube (CT). The contact of the hot PT with the CT causes rapid redistribution of stored heat from the PT to CT and a large heat flux spike from the CT to the moderator fluid. For conditions where subcooling of the moderator fluid is low, this heat flux spike can cause dryout of the CT. This can detrimentally affect channel integrity if the CT post-dryout temperature becomes sufficiently high to result in continued thermal creep strain deformation of both the PT and the CT. The focus of this work is to develop a mechanistic model to predict Critical Heat Flux (CHF) on the CT surface following a contact with its pressure tube. A mechanistic CHF model is applied based on a concept of wall dry patch formation, prevention of rewetting and subsequent dry patch spreading. Results have been compared to an empirical correlation and a good agreement has been obtained. The model has been used to predict the spatial variation of CHF over a cylinder with dimensions of CANDU CT. (author)

  6. Generation Mechanism for Interlinked Flux Tubes on the Magnetopause

    Science.gov (United States)

    Farinas Perez, G.; Cardoso, F. R.; Sibeck, D.; Gonzalez, W. D.; Facskó, G.; Coxon, J. C.; Pembroke, A. D.

    2018-02-01

    We use a global magnetohydrodynamics simulation to analyze transient magnetic reconnection processes at the magnetopause. The solar wind conditions have been kept constant, and an interplanetary magnetic field with large duskward BY and southward BZ components has been imposed. Five flux transfer events (FTEs) with clear bipolar magnetic field signatures have been observed. We observed a peculiar structure defined as interlinked flux tubes (IFTs) in the first and fourth FTE, which had very different generation mechanisms. The first FTE originates as an IFTs and remains with this configuration until its final moment. However, the fourth FTE develops as a classical flux rope but changes its 3-D magnetic configuration to that of IFTs. This work studies the mechanism for generating IFTs. The growth of the resistive tearing instability has been identified as the cause for the first IFTs formation. We believe that the instability has been triggered by the accumulation of interplanetary magnetic field at the subsolar point where the grid resolution is very high. The evidence shows that two new reconnection lines form northward and southward of the subsolar region. The IFTs have been generated with all the classical signatures of a single flux rope. The other IFTs detected in the fourth FTE developed as a result of magnetic reconnection inside its complex and twisted magnetic fields, which leads to a change in the magnetic configuration from a flux rope of twisted magnetic field lines to IFTs.

  7. Maximum allowable heat flux for a submerged horizontal tube bundle

    International Nuclear Information System (INIS)

    McEligot, D.M.

    1995-01-01

    For application to industrial heating of large pools by immersed heat exchangers, the socalled maximum allowable (or open-quotes criticalclose quotes) heat flux is studied for unconfined tube bundles aligned horizontally in a pool without forced flow. In general, we are considering boiling after the pool reaches its saturation temperature rather than sub-cooled pool boiling which should occur during early stages of transient operation. A combination of literature review and simple approximate analysis has been used. To date our main conclusion is that estimates of q inch chf are highly uncertain for this configuration

  8. Measurements of absorbed heat flux and water-side heat transfer coefficient in water wall tubes

    Science.gov (United States)

    Taler, Jan; Taler, Dawid; Kowal, Andrzej

    2011-04-01

    The tubular type instrument (flux tube) was developed to identify boundary conditions in water wall tubes of steam boilers. The meter is constructed from a short length of eccentric tube containing four thermocouples on the fire side below the inner and outer surfaces of the tube. The fifth thermocouple is located at the rear of the tube on the casing side of the water-wall tube. The boundary conditions on the outer and inner surfaces of the water flux-tube are determined based on temperature measurements at the interior locations. Four K-type sheathed thermocouples of 1 mm in diameter, are inserted into holes, which are parallel to the tube axis. The non-linear least squares problem is solved numerically using the Levenberg-Marquardt method. The heat transfer conditions in adjacent boiler tubes have no impact on the temperature distribution in the flux tubes.

  9. Critical heat flux in CANDU moderator following a pressure tube to calandria tube contact - part I

    International Nuclear Information System (INIS)

    Behdadi, A.; Luxat, J.C.

    2011-01-01

    Heavy water moderator surrounding each fuel channel is one of the important features in CANDU reactors that act as a heat sink for the fuel in the situations where other means of heat removal fail. In the critical break LOCA scenario, fuel cooling becomes severely degraded due to rapid flow reduction in the affected flow pass of the heat transport system. This can result in pressure tubes experiencing significant heat-up while coolant pressure is still high, thereby causing uniform thermal creep strain (ballooning) of the pressure tube (PT) into contact with its calandria tube (CT). The contact of the hot PT with the CT causes rapid redistribution of stored heat from the PT to CT and a large spike in heat flux from the CT to the moderator fluid. For lower subcooling conditions of the moderator, this heat flux spike can cause dryout of the CT. This can detrimentally affect channel integrity if the CT post-dryout temperature becomes sufficiently high to result in thermal creep strain deformation. The focus of this research is to develop a mechanistic model to predict Critical Heat Flux (CHF) on the CT surface following a contact with its pressure tube. A COMSOL multi-physics model using a two-dimensional transient fluid-thermal analysis of the CT surface undergoing heat up is used to predict flow and temperature profile on the CT surface. A mechanistic CHF model is to be proposed based on a concept of wall dry patch formation, prevention of rewetting and subsequent dry patch spreading. (author)

  10. Influence of test tube material on subcooled flow boiling critical heat flux in short vertical tube

    International Nuclear Information System (INIS)

    Hata, Koichi; Shiotsu, Masahiro; Noda, Nobuaki

    2007-01-01

    The steady state subcooled flow boiling critical heat flux (CHF) for the flow velocities (u=4.0 to 13.3 m/s), the inlet subcoolings (ΔT sub,in =48.6 to 154.7 K), the inlet pressure (P in =735.2 to 969.0 kPa) and the increasing heat input (Q 0 exp(t/τ), τ=10, 20 and 33.3 s) are systematically measured with the experimental water loop. The 304 Stainless Steel (SUS304) test tube of inner diameter (d=6 mm), heated length (L=66 mm) and L/d=11 with the inner surface of rough finished (Surface roughness, Ra=3.18 μm), the Cupro Nickel (Cu-Ni 30%) test tube of d=6 mm, L=60 mm and L/d=10 with Ra=0.18 μm and the Platinum (Pt) test tubes of d=3 and 6 mm, L=66.5 and 69.6 mm, and L/d=22.2 and 11.6 respectively with Ra=0.45 μm are used in this work. The CHF data for the SUS304, Cu-Ni 30% and Pt test tubes were compared with SUS304 ones for the wide ranges of d and L/d previously obtained and the values calculated by the authors' published steady state CHF correlations against outlet and inlet subcoolings. The influence of the test tube material on CHF is investigated into details and the dominant mechanism of subcooled flow boiling critical heat flux is discussed. (author)

  11. Influence of Test Tube Material on Subcooled Flow Boiling Critical Heat Flux in Short Vertical Tube

    International Nuclear Information System (INIS)

    Koichi Hata; Masahiro Shiotsu; Nobuaki Noda

    2006-01-01

    The steady state subcooled flow boiling critical heat flux (CHF) for the flow velocities (u = 4.0 to 13.3 m/s), the inlet subcooling (ΔT sub,in = 48.6 to 154.7 K), the inlet pressure (P in = 735.2 to 969.0 kPa) and the increasing heat input (Q 0 exp(t/t), t = 10, 20 and 33.3 s) are systematically measured with the experimental water loop. The 304 Stainless Steel (SUS304) test tubes of inner diameters (d = 6 mm), heated lengths (L = 66 mm) and L/d = 11 with the inner surface of rough finished (Surface roughness, R a = 3.18 μm), the Cupro Nickel (Cu-Ni 30%) test tubes of d = 6 mm, L = 60 mm and L/d = 10 with R a = 0.18 μm and the Platinum (Pt) test tubes of d = 3 and 6 mm, L = 66.5 and 69.6 mm, and L/d 22.2 and 11.6 respectively with R a = 0.45 μm are used in this work. The CHF data for the SUS304, Cu-Ni 30% and Pt test tubes were compared with SUS304 ones for the wide ranges of d and L/d previously obtained and the values calculated by the authors' published steady state CHF correlations against outlet and inlet subcooling. The influence of the test tube material on CHF is investigated into details and the dominant mechanism of subcooled flow boiling critical heat flux is discussed. (authors)

  12. Flux tubes in U(1) - Do they attract or repel each other?

    International Nuclear Information System (INIS)

    Zach, M.; Faber, M.; Skala, P.

    1998-01-01

    The dually transformed path integral of four-dimensional U(1) lattice gauge theory is used for a numerical investigation of multiply charged systems and the interaction between flux tubes. For this aim, it is convenient to implement periodically closed flux tubes (torelons) in the dual formulation. We calculate the free energy as well as the total electro-magnetic energy of doubly charged flux tubes as a function of the coupling β. The main results are that the string tension scales proportionally to the charge (contrary to the Coulomb potential) and in the range 0.9<β<1.0 we find a clear signal for attraction between flux tubes. (orig.)

  13. Evaluation of Unknown Tube Well Depth Using Electrical Resistivity Method

    Directory of Open Access Journals (Sweden)

    Zainal Abidin Mohd Hazreek

    2017-01-01

    Full Text Available Electrical resistivity method has increasingly adopted in engineering, environmental, mining and archaeological studies. Systematic and proper studies of unknown civil engineering structure evaluation particularly on tube well depth was rarely being established. Conventionally, camera test or string with weight approach has been used to evaluate unknown tube well depth thus exposed to several restriction due to its expensive and time consuming. Hence, this study focused on evaluation of unknown tube well depth using indirect test with particular reference to electrical resistivity method (ERM.A single spread line of electrical resistivity survey was performed using ABEM SAS 4000 equipment set based on Wenner and Pole-dipole array in line with the tube well position. Electrical resistivity raw data was processed using RES2DINV software producing electrical resistivity tomography (ERT of the subsurface profile studied. Then, electrical resistivity value (ERV obtained from RES2DINV analyses (ERT was extracted and analysed using plotted graph (depth versus ERV specifically at tube well position based on electrical resistivity spread line performed. It was found that both array have shown some good similarity results in term of tube well depth (20 m thus able to verify the result interpreted. Both array have shown some good similarity of ERV representing groundwater (ERV = 10 – 100 Ωm and soil with water (ERV > 100 Ωm at depth of 0 – 20 m and >20 m respectively. All those interpretation have shown good agreement based on verification thru established ERV of earth materials references, geological map and nearest available boreholes data. Hence, this study has shown that the application of ERM was applicable in evaluation of unknown tube well depth which efficient in term of cost, time and environmental sustainable.

  14. The nonlinear gyro-kinetic flux tube code GKW

    Science.gov (United States)

    Peeters, A. G.; Camenen, Y.; Casson, F. J.; Hornsby, W. A.; Snodin, A. P.; Strintzi, D.; Szepesi, G.

    2009-12-01

    A new nonlinear gyro-kinetic flux tube code (GKW) for the simulation of micro instabilities and turbulence in magnetic confinement plasmas is presented in this paper. The code incorporates all physics effects that can be expected from a state of the art gyro-kinetic simulation code in the local limit: kinetic electrons, electromagnetic effects, collisions, full general geometry with a coupling to a MHD equilibrium code, and E×B shearing. In addition the physics of plasma rotation has been implemented through a formulation of the gyro-kinetic equation in the co-moving system. The gyro-kinetic model is five-dimensional and requires a massive parallel approach. GKW has been parallelised using MPI and scales well up to 8192+ cores. The paper presents the set of equations solved, the numerical methods, the code structure, and the essential benchmarks. Program summaryProgram title: GKW Catalogue identifier: AEES_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEES_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL v3 No. of lines in distributed program, including test data, etc.: 29 998 No. of bytes in distributed program, including test data, etc.: 206 943 Distribution format: tar.gz Programming language: Fortran 95 Computer: Not computer specific Operating system: Any for which a Fortran 95 compiler is available Has the code been vectorised or parallelised?: Yes. The program can efficiently utilise 8192+ processors, depending on problem and available computer. 128 processors is reasonable for a typical nonlinear kinetic run on the latest x86-64 machines. RAM:˜128 MB-1 GB for a linear run; 25 GB for typical nonlinear kinetic run (30 million grid points) Classification: 19.8, 19.9, 19.11 External routines: None required, although the functionality of the program is somewhat limited without a MPI implementation (preferably MPI-2) and the FFTW3 library. Nature of problem: Five

  15. Intermittent energy bursts and recurrent topological change of a twisting magnetic flux tube

    International Nuclear Information System (INIS)

    Amo, Hiroyoshi; Sato, Tetsuya; Kageyama, Akira.

    1994-09-01

    When continuously twisted, a magnetic flux tube suffers a large kink distortion in the middle part of the tube, like a knot-of-tension instability of a bundle of twisted rubber strings, and reconnection is triggered starting with the twisted field lines and quickly proceeding to the untwisted field lines at the twist-untwist boundary, whereby a giant burst-like energy release takes place. Subsequently, bursts occur intermittently and reconnection advances deeper into the untwisted region. Then, a companion pair of the linked twist-untwist flux tubes reconnect with each other to return to the original axisymmetric tube. The process is thus repeatable. (author)

  16. Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field

    Directory of Open Access Journals (Sweden)

    N. V. Erkaev

    2002-01-01

    Full Text Available Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.

  17. Two-dimensional equilibrium in coronal magnetostatic flux tubes: an accurate equilibrium solver

    NARCIS (Netherlands)

    Belien, A. J. C.; Poedts, S.; Goedbloed, J. P.

    1997-01-01

    To study linearized magnetohydrodynamic (MHD) waves, continuous spectra, and instabilities in coronal magnetic flux tubes that are anchored in dense chromospheric and photospheric regions, a two-dimensional numerical code, called PARIS, has been developed. PARIS solves the pertinent nonlinear

  18. New constraint on effective field theories of the QCD flux tube

    Science.gov (United States)

    Baker, M.

    2016-03-01

    Effective magnetic S U (N ) gauge theory with classical ZN flux tubes of intrinsic width 1/M is an effective field theory of the long-distance quark-antiquark interaction in S U (N ) Yang-Mills theory. Long-wavelength fluctuations of the ZN vortices of this theory lead to an effective string theory. In this paper, we clarify the connection between effective field theory and effective string theory, and we propose a new constraint on these vortices. We first examine the impact of string fluctuations on the classical dual superconductor description of confinement. At interquark distances R ˜1/M , the classical action for a straight flux tube determines the heavy quark potentials. At distances R ≫1/M , fluctuations of the flux tube axis x ˜ give rise to an effective string theory with an action Seff(x ˜), the classical action for a curved flux tube, evaluated in the limit 1/M →0 . This action is equal to the Nambu-Goto action. These conclusions are independent of the details of the ZN flux tube. Further, we assume the QCD flux tube satisfies the additional constraint, ∫0∞r d r T/θθ(r ) r2=0 , where T/θθ(r ) r2 is the value of the θ θ component of the stress tensor at a distance r from the axis of an infinite flux tube. Under this constraint, the string tension σ equals the force on a quark in the chromoelectric field E → of an infinite straight flux tube, and the Nambu-Goto action can be represented in terms of the chromodynamic fields of effective magnetic S U (N ) gauge theory, yielding a field theory interpretation of effective string theory.

  19. Neutron fluxes and spectra of the neutron guide tubes in the upgraded JRR-3

    International Nuclear Information System (INIS)

    Kawabata, Y.; Suzuki, M.; Tsuruno, A.; Onishi, N.

    1992-01-01

    A cold neutron source with two thermal and three cold neutron guide tubes has been installed in the upgraded JRR-3. Neutron fluxes, time-of-flight spectra and the gain of the cold neutron source were measured at the end of the neutron guide tubes. The neutron beam distributions were found by neutron radiography films. (orig.)

  20. Inner tubes cutting method by electrical arc saw

    International Nuclear Information System (INIS)

    Thome, P.

    1990-01-01

    The research program deals on the definition of tools used for dismantling steam generator tubes bundle of PWR and on tool used for cutting pipes of great diameter by using the process of cutting by electrical arc saw. The remote tools are used for cutting by the interior pipes of contamined circuits [fr

  1. Sausage instabilities on top of kinking lengthening current-carrying magnetic flux tubes

    Science.gov (United States)

    von der Linden, Jens; You, Setthivoine

    2017-05-01

    We theoretically explore the possibility of sausage instabilities developing on top of a kink instability in lengthening current-carrying magnetic flux tubes. Observations indicate that the dynamics of magnetic flux tubes in our cosmos and terrestrial experiments can involve topological changes faster than time scales predicted by resistive magnetohydrodynamics. Recent laboratory experiments suggest that hierarchies of instabilities, such as kink and Rayleigh-Taylor, could be responsible for initiating fast topological changes by locally accessing two-fluid and kinetic regimes. Sausage instabilities can also provide this coupling mechanism between disparate scales. Flux tube experiments can be classified by the flux tube's evolution in a configuration space described by a normalized inverse aspect-ratio k ¯ and current-to-magnetic flux ratio λ ¯ . A lengthening current-carrying magnetic flux tube traverses this k ¯ - λ ¯ space and crosses stability boundaries. We derive a single general criterion for the onset of the sausage and kink instabilities in idealized magnetic flux tubes with core and skin currents. The criterion indicates a dependence of the stability boundaries on current profiles and shows overlapping kink and sausage unstable regions in the k ¯ - λ ¯ space with two free parameters. Numerical investigation of the stability criterion reduces the number of free parameters to a single one that describes the current profile and confirms the overlapping sausage and kink unstable regions in k ¯ - λ ¯ space. A lengthening, ideal current-carrying magnetic flux tube can therefore become sausage unstable after it becomes kink unstable.

  2. A new method for estimating heat flux in superheater and reheater tubes

    Energy Technology Data Exchange (ETDEWEB)

    Purbolaksono, J. [Department of Mechanical Engineering, Universiti Tenaga Nasional, km 7 Jalan Kajang-Puchong, Kajang 43009, Selangor (Malaysia)], E-mail: judha@uniten.edu.my; Khinani, A.; Rashid, A.Z.; Ali, A.A. [Department of Mechanical Engineering, Universiti Tenaga Nasional, km 7 Jalan Kajang-Puchong, Kajang 43009, Selangor (Malaysia); Ahmad, J. [Kapar Energy Ventures Sdn Bhd, Jalan Tok Muda, Kapar 42200, Selangor (Malaysia); Nordin, N.F. [TNB Research Sdn Bhd, No. 1 Lorong Air Hitam, Kajang 43000, Selangor (Malaysia)

    2009-10-15

    In this paper a procedure on how to estimate the heat flux in superheater and reheater tubes utilizing the empirical formula and the finite element modeling is proposed. An iterative procedure consisting of empirical formulae and numerical simulation is used to determine heat flux as both temperature and scale thickness increase over period of time. Estimation results of the heat flux over period of time for two different design temperatures of the steam and different heat transfer parameters are presented.

  3. Heat transfer and critical heat flux in a spiral flow in an asymmetrical heated tube; Transfert thermique et flux critique dans un ecoulement helicoidal en tube chauffe asymetriquement

    Energy Technology Data Exchange (ETDEWEB)

    Boscary, J. [CEA Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Direction des Sciences de la Matiere]|[Association Euratom-CEA, Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    1997-03-01

    The design of plasma facing components is crucial for plasma performance in next fusion reactors. These elements will be submitted to very high heat flux. They will be actively water-cooled by swirl tubes in the subcooled boiling regime. High heat flux experiments were conducted in order to analyse the heat transfer and to evaluate the critical heat flux. Water-cooled mock-ups were one-side heated by an electron beam gun for different thermal-hydraulic conditions. The critical heat flux was detected by an original method based on the isotherm modification on the heated surface. The wall heat transfer law including forced convection and subcooled boiling regimes was established. Numerical calculations of the material heat transfer conduction allowed the non-homogeneous distribution of the wall temperature and of the wall heat flux to be evaluated. The critical heat flux value was defined as the wall maximum heat flux. A critical heat flux model based on the liquid sublayer dryout under a vapor blanket was established. A good agreement with test results was found. (author) 197 refs.

  4. Heat transfer and critical heat flux in a asymmetrically heated tube helicoidal flow; Transfert thermique et flux critique dans un ecoulement helicoidal en tube chauffe asymetriquement

    Energy Technology Data Exchange (ETDEWEB)

    Boscary, J.

    1995-10-01

    The design of plasma facing components is crucial for plasma performance in next fusion reactors. These elements will be submitted to very high heat flux. They will be actively water-cooled by swirl tubes in the subcooled boiling regime. High heat flux experiments were conducted in order to analyse the heat transfer and to evaluate the critical heat flux. Water-cooled mock-ups were one-side heated by an electron beam gun for different thermal-hydraulic conditions. The critical heat flux was detected by an original method based on the isotherm modification on the heated surface. The wall heat transfer law including forced convection and subcooled boiling regimes was established. Numerical calculations of the material heat transfer conduction allowed the non-homogeneous distribution of the wall temperature and of the wall heat flux to be evaluated. The critical heat flux value was defined as the wall maximum heat flux. A critical heat flux model based on the liquid sublayer dryout under a vapor blanket was established. A good agreement with test results was found. (author). 198 refs., 126 figs., 21 tabs.

  5. Sausage MHD Waves in Incompressible Flux Tubes with Twisted Magnetic Fields

    Science.gov (United States)

    Erdélyi, Robert; Fedun, Viktor

    2006-10-01

    Twisted magnetic flux tubes are of considerable interest because of their natural occurrence from the Sun’s interior, throughout the solar atmosphere and interplanetary space up to a wide range of applicabilities to astrophysical plasmas. The aim of the present work is to obtain analytically a dispersion equation of linear wave propagation in twisted incompressible cylindrical magnetic waveguides and find appropriate solutions for surface, body and pseudobody sausage modes (i.e. m = 0) of a twisted magnetic flux tube embedded in an incompressible but also magnetically twisted plasma. Asymptotic solutions are derived in long- and short-wavelength approximations. General solutions of the dispersion equation for intermediate wavelengths are obtained numerically. We found, that in case of a constant, but non-zero azimuthal component of the equilibrium magnetic field outside the flux tube the index ν of Bessel functions in the dispersion relation is not integer any more in general. This gives rise to a rich mode-structure of degenerated magneto-acoustic waves in solar flux tubes. In a particular case of a uniform magnetic twist the total pressure is found to be constant across the boundary of the flux tube. Finally, the effect of magnetic twist on oscillation periods is estimated under solar atmospheric conditions. It was found that a magnetic twist will increase, in general, the periods of waves approximately by a few percent when compared to their untwisted counterparts.

  6. An investigation of the effect of axial heat-flux distribution on critical heat flux in tubes

    International Nuclear Information System (INIS)

    Yang, J.; Groeneveld, D.C.; Cheng, S.C.; Leung, L.K.H.; El Nakla, M.A.

    2004-01-01

    The effect of axial heat flux distribution (AFD) on critical heat flux (CHF) in tubes was investigated. CHF measurements were obtained with three HFC-134a cooled vertical tubes. One of these tubes was axially uniform-heated. The other two tubes exhibited non-uniform axial power profile and were also tested in reversed positions providing four different profiles. In general, the observed AFD effect on critical power is small at high inlet subcoolings. At low inlet subcoolings, the critical power for the inlet-peak profile is up to 15% higher than that for the outlet-peak profile. A local conditions analysis showed that the AFD has the strongest effect on CHF at high dryout qualities. CHF values for non-uniform AFDs could be 50% lower than those for the uniform AFD. The AFD effect on CHF becomes diminished with decreasing dryout quality. Four different approaches to account for the effect of AFD on CHF were assessed against the experimental values from the current experiment. The boiling-length-average heat-flux approach with the boiling-length starting point at the onset of annular flow provided the best prediction of the critical power and the CHF location. (author)

  7. Nonlinear fast sausage waves in homogeneous magnetic flux tubes

    Science.gov (United States)

    Mikhalyaev, Badma B.; Ruderman, Michael S.

    2015-12-01

    > We consider fast sausage waves in straight homogeneous magnetic tubes. The plasma motion is described by the ideal magnetohydrodynamic equations in the cold plasma approximation. We derive the nonlinear Schrödinger equation describing the nonlinear evolution of an envelope of a carrier wave. The coefficients of this equation are expressed in terms Bessel and modified Bessel functions. They are calculated numerically for various values of parameters. In particular, we show that the criterion for the onset of the modulational or Benjamin-Fair instability is satisfied. The implication of the obtained results for solar physics is discussed.

  8. The flux tube paradigm and its role in MHD turbulence in the solar atmosphere

    Science.gov (United States)

    Matthaeus, W. H.; Greco, A.; Servidio, S.; Wan, M.; Osman, K.; Ruffolo, D. J.

    2011-12-01

    Descriptions of magnetic field and plasma structures in terms of flux tubes, plasmoids and other bundles of magnetic field lines are familiar in the vocabulary of observational and theoretical space physics. "Spaghetti models" and flux ropes are well known examples. Flux tubes and families of field lines can also be defined in a medium that admits magnetic fluctuations, including strong MHD turbulence, but their behavior can become complicated. In 3D fluctuations the smooth flux tube description itself becomes in some sense unstable, as nearby field lines diverge and flux surfaces shred. This lends complexity to the structure of flux tubes, and can give rise to temporarily trapped field lines and charged test particle trajectories, with immediate implications for transport, e.g., of solar energetic particles. The properties of the turbulent magnetic field can also be strongly influenced by the dynamics of turbulence. Large scale self organizing behavior, or inverse cascade, can enhance very long wavelength structure, favoring Bohm scaling of diffusion coefficients. Meanwhile smaller scale flux tube structures are integral features of the inertial range of turbulence, giving rise to a cellularization of the plasma due to rapid dynamical relaxation processes. These drive the turbulent system locally towards low-acceleration states, including Alfvenic, Beltrami and force-free states. Cell boundaries are natural positions for formation of near discontinuous boundaries, where dynamical activity can be enhanced. A primary example is appearance of numerous discontinuities and active reconnection sites in turbulence, which appear to support a wide distribution of reconnection rates associated with coherent current structures. These discontinuities are also potential sites of enhanced heating, as expected in Kolmogorov's Refined Similarity Hypothesis. All of these features are related to self organization, cascade and intermittency of the turbulence. Examples of these

  9. Studies on the instrumentation of a beam-tube medium flux reactor

    International Nuclear Information System (INIS)

    Axmann, A.; Pollet, J.L.; Queudot, J.

    1979-01-01

    In the years 1977/78, the ad hoc commitee for medium-flux reactor development of the Federal Ministry for Research and Technology developed constructional concepts for a medium-flux reactor to be utilized by beam tube experiments. The HMI has elaborated contributions for discussions of the subject of instrumentation, in particular for experiments in solid state physics. These contributions are contained in the report. (orig./RW) [de

  10. Surprisingly low frequency attenuation effects in long tubes when measuring turbulent fluxes at tall towers

    DEFF Research Database (Denmark)

    Ibrom, Andreas; Brændholt, Andreas; Pilegaard, Kim

    2016-01-01

    that the concentration signal was hardly biased during the ca 10 s travel through the tube. Due to the larger turbulence time scales at large measurement heights the low-pass correction was for the majority of the measurements water vapour the tube attenuation was massive, which had, however, a positive effect...... by reducing both the water vapour dilution correction and the cross sensitivity effects on the N2O and CO flux measurements. Here we present the set-up of the concentration step change experiment and its results and compare them with recently developed theories for the behaviour of gases in turbulent tube......The eddy covariance technique relies on the fast and accurate measurement of gas concentration fluctuations. While for some gasses robust and compact sensors are available, measurement of, e.g., non CO2 greenhouse gas fluxes is often performed with sensitive equipment that cannot be run on a tower...

  11. Design and use of the ORNL HFIR [High Flux Isotope Reactor] pneumatic tube irradiation systems

    International Nuclear Information System (INIS)

    Dyer, F.F.; Emery, J.F.; Robinson, L.; Teasley, N.A.

    1987-01-01

    A second pneumatic tube that was recently installed in the High Flux Isotope Reactor for neutron activation analysis is described. Although not yet tested, the system is expected to have a thermal neutron flux of about 1.5 x 10 14 cm -2 s -1 . A delayed neutron counter is an integral part of the pneumatic tube, and all of the hardware is present to enable automated use of the counter. The system is operated with a Gould programmable controller that is programmed with an IBM personal computer. Automation of any mode of operation, including the delayed neutron counter, will only require a nominal amount of software development. Except for the lack of a hot cell, the irradiation facility has all of the advantageous features of an older pneumatic tube that has been in operation for 17 years. The design of the system and some applications and methods of operation are described

  12. Correlation of critical heat flux data for uniform tubes

    Energy Technology Data Exchange (ETDEWEB)

    Jafri, T.; Dougherty, T.J.; Yang, B.W. [Columbia Univ., New York, NY (United States)

    1995-09-01

    A data base of more than 10,000 critical heat flux (CHF) data points has been compiled and analyzed. Two regimes of CHF are observed which will be referred to as the high CHF regime and the low CHF regime. In the high CHF regime, for pressures less than 110 bar, CHF (q{sub c}) is a determined by local conditions and is adequately represented by q{sub c} = (1.2/D{sup 1/2}) exp[-{gamma}(GX{sub t}){sup 1/2}] where the parameter {gamma} is an increasing function of pressure only, X{sub t} the true mass fraction of steam, and all units are metric but the heat flux is in MWm{sup -2}. A simple kinetic model has been developed to estimate X{sub t} as a function of G, X, X{sub i}, and X{sub O}, where X{sub i} is the inlet quality and X{sub O} represents the quality at the Onset of Significant Vaporization (OSV) which is estimated from the Saha-Zuber (S-Z) correlation. The model is based on a rate equation for vaporization suggested by, and consistent with, the S-Z correlation and contains no adjustable parameters. When X{sub i}X{sub O}, X{sub t} depends on X{sub i}, a nonlocal variable, and, in this case, CHF, although determined by local conditions, obeys a nonlocal correlation. This model appears to be satisfactory for pressures less than 110 bar, where the S-Z correlation is known to be reliable. Above 110 bar the method of calculating X{sub O}, and consequently X{sub t}, appears to fail, so this approach can not be applied to high pressure CHF data. Above 35 bar, the bulk of the available data lies in the high CHF regime while, at pressures less than 35 bar, almost all of the available data lie in the low CHF regime and appear to be nonlocal.

  13. 3D Laboratory Measurements of Forces, Flows, and Collimation in Arched Flux Tubes

    Science.gov (United States)

    Haw, Magnus; Bellan, Paul

    2016-10-01

    Fully 3D, vector MHD force measurements from an arched, current carrying flux tube (flux rope) are presented. The experiment consists of two arched plasma-filled flux ropes each powered by a capacitor bank. The two loops are partially overlapped, as in a Venn diagram, and collide and reconnect during their evolution. B-field data is taken on the lower plasma arch using a 54 channel B-dot probe. 3D volumetric data is acquired by placing the probe at 2700 locations and taking 5 plasma shots at each location. The resulting data set gives high resolution (2cm, 10ns) volumetric B-field data with high reproducibility (deviation of 3% between shots). Taking the curl of the measured 3D B-field gives current densities (J) in good agreement with measured capacitor bank current. The JxB forces calculated from the data have a strong axial component at the base of the current channel and are shown to scale linearly with axial gradients in current density. Assuming force balance in the flux tube minor radius direction, we infer near-Alfvenic axial flows from the footpoint regions which are consistent with the measured axial forces. Flux tube collimation is observed in conjunction with these axial flows. These dynamic processes are relevant to the stability and dynamics of coronal loops. Supported provided by NSF, AFOSR.

  14. Critical heat flux for downward-facing pool boiling on CANDU calandria tube surface

    Energy Technology Data Exchange (ETDEWEB)

    Behdadi, Azin, E-mail: behdada@mcmaster.ca; Talebi, Farshad; Luxat, John

    2017-04-15

    Highlights: • Pressure tube-calandria tube contact may challenge fuel channel integrity in CANDU. • Critical heat flux variation is predicted on the outer surface of CANDU calandria tube. • A two-phase boundary layer flow driven by buoyancy is modeled on the surface. • Different slip ratios and flow regimes are considered inside the boundary layer. • Subcooling effects are added to the model using wall heat flux partitioning. - Abstract: One accident scenario in CANDU reactors that can challenge the integrity of the primary pressure boundary is a loss of coolant accident, referred to as critical break LOCA, in which the pressure tube (PT) can undergo thermal creep strain deformation and contact its calandria tube (CT). In such case, rapid redistribution of stored heat from PT to CT, leads to a large spike in heat flux to the moderator which can cause bubble accumulation and dryout on the CT surface. A challenge to fuel channel integrity is posed if critical heat flux occurs on the surface of the CT and results in sustained film boiling. If the post-dryout temperature becomes sufficiently high then continued creep strain of the PT and CT may lead to fuel channel failure. In this study, a mechanistic model is developed to predict the critical heat flux variations along the downward facing outer surface of CT. The hydrodynamic model considers a liquid macrolayer beneath an elongated vapor slug on the surface. Local dryout is postulated to occur whenever the fresh liquid supply to the macrolayer is not sufficient to compensate for the liquid depletion. A boundary layer analysis is performed, treating the two phase motion as an external buoyancy driven flow. The model shows good agreement with the available experimental data and has been modified to take into account the effect of subcooling.

  15. Measurements of Plasma Jets and Collimated Flux Tubes that are the Precursors of Spheromak Self-organization

    Science.gov (United States)

    Bellan, P. M.; You, S.; Yun, G. S.

    2007-06-01

    A magnetized planar coaxial plasma gun is used to study the physics of spheromak formation. Eight magnetic flux tubes spanning from the cathode to the anode electrode are first filled with plasma by a rapid MHD pumping mechanism which ingests plasma from nozzles at the wall. The ingested plasma convects toroidal flux and the pile-up of this flux in the flux tube causes the flux tube to become collimated. The eight collimated flux tubes first have the shape of spider legs, but then merge to form a central column jet. This jet lengthens, continuing to ingest plasma from the wall sources, and becomes kink unstable. At a later stage the root of the jet can break off from the electrode and this detachment has been identified as being associated with a sausage instability. The sausage instability takes place during the nonlinear stage of the kinking. The above statements are based on experimental observations and have been reconciled with MHD models.

  16. Critical heat flux during natural convective boiling in inclined tubes submerged in saturated liquids

    International Nuclear Information System (INIS)

    Liu Zhenhua; Yang Ronghua

    2005-01-01

    An experimental study was carried out to improve and expand understanding of boiling phenomena and the critical heat flux (CHF) during natural convective boiling in uniformly heated inclined tubes submerged in a pool of saturated liquids under atmospheric pressure. The test conditions were as follows: inter diameters of the test tubes ranged from 0.9 to 8.0 mm; heated lengths ranged from 100 to 400 mm, and inclination angles varied from 30 o to vertical position. The test fluids were water and R-11. The experimental results showed that the CHF decreases with the increasing ratio of the tube length to the tube diameter, and with the reducing of the inclination angle. A semi-theoretical correlation, which originally used for the CHF during natural convective boiling in vertical tubes, was modified to predict the CHF occurs in the inclined tubes. The modified correlation agreed reasonably well with the present experimental data and other CHF data for narrow inclined annular tubes

  17. Correlation between the critical heat flux and the fractal surface roughness of zirconium alloy tubes

    International Nuclear Information System (INIS)

    Fong, R.W.L.; McRae, G.A.; Coleman, C.E.; Nitheanandan, T.; Sanderson, D.B.

    1999-10-01

    In CANDU fuel channels, Zircaloy calandria tubes isolate the hot pressure tubes from the cool heavy water moderator. The heavy-water moderator provides a backup heat sink during some postulated loss-of-coolant accidents. The decay heat from the fuel is transferred to the moderator to ensure fuel channel integrity during emergencies. Moderator temperature requirements are specified to ensure that the transfer of decay heat does not exceed the critical heat flux (CHF) on the outside surface of the calandria tube. An enhanced CHF provides increases in safety margin. Pool boiling experiments indicate the CHF is enhanced with glass-peening of the outside surface of the calandria tubes. The objective of this study was to evaluate the surface characteristics of glass-peened tubes and relate these characteristics to CHF. The micro-topologies of the tube surfaces were analysed using stereo-pair micrographs obtained from scanning electron microscopy (SEM) and photogrammetry techniques. A linear relationship correlated the CHF as a function of the 'fractal' surface roughness of the tubes. (author)

  18. Computation of Electromagnetic Torque in a Double Rotor Switched Reluctance Motor Using Flux Tube Methods

    Directory of Open Access Journals (Sweden)

    Mohammad Hamiruce Marhaban

    2012-10-01

    Full Text Available With their highly robust nature and simple design, switched reluctance machines are finding their way into numerous modern day applications. However, they produce oscillatory torque that generates torque ripple and mechanical vibrations. A double rotor structure to maximize the flux linkage and thereby increase the torque generating capability is proposed. As the machine operates close to saturation, the torque computation depends heavily on the energy conversion as the rotor rolls over the stator for a fixed pole pitch. The flux linkage characteristics are highly non-linear, hence estimation of the magnetic and mechanical parameters is extremely cumbersome. Magnetic circuit analysis by interpretation of the number of flux tubes using integration techniques at different positions of the machine to develop the flux linkage characteristics of the double rotor structure is presented. Computation of the inductances during the movement of rotor from unaligned to aligned is crucial in determining the generated torque. Relevant equations of calculations for inductance and flux linkages in the aligned, partially aligned and unaligned positions are computed. The partially aligned computation is based on the average on two intermediate positions, namely the 1/4th aligned and 3/4th aligned conditions. The static torque characteristics based on the energy conversion principles are used to compute the torque value. Results from simulation and experiments used for performance evaluation of the proposed flux tube analysis for computation of the electro-magnetic torque are presented.

  19. Fluctuations of the baryonic flux-tube junction from effective string theory

    International Nuclear Information System (INIS)

    Pfeuffer, Melanie; Bali, Gunnar S.; Panero, Marco

    2009-01-01

    In quenched QCD, where the dynamic creation of quark-antiquark pairs out of the vacuum is neglected, a confined baryonic system composed of three static quarks exhibits stringlike behavior at large interquark separation, with the formation of flux tubes characterized by the geometry of the so-called Y ansatz. We study the fluctuations of the junction of the three flux tubes, assuming the dynamics to be governed by an effective bosonic string model. We show that the asymptotic behavior of the effective width of the junction grows logarithmically with the distance between the sources, with the coefficient depending on the number of joining strings, on the dimension of spacetime and on the string tension.

  20. Heat transfer coefficient in pool boiling for an electrically heated tube at various inclinations

    International Nuclear Information System (INIS)

    Fahmy, A.S.A.; Mariy, A.H.; Mahmoud, S.I.; Ibrahim, N.A.

    1987-01-01

    An experimental investigation is carried out study the behaviour of heat transfer in pool boiling from a vertical and inclined heated tube at atmospheric pressure. An imperial correlation joining the different parameters affecting the heat transfer coefficient in pool boiling for an electrically heated tube at various inclinations is developed. Two test sections (zircaloy-4 and stainless steel) of 16 n n outer diameter and 120 nm length are investigated. Four levels of heat flux are used for heating the two lest sections (e.g. 381, 518, 721 and 929 k.watt/n 2). The maximum surface temperature achieved is 146.5 degree c for both materials, and the maximum bulk temperature is 95 degree C. It is found that the average heat transfer coefficient is inversely proportional with heated length l, where it reaches a constant value in the horizontal position. The heat transfer coefficient curves at various inclinations with respect to the heated tube length pass around one point which is defined as limit length

  1. Stability of interlinked neutron vortex and proton flux tube arrays in a neutron star: equilibrium configurations

    Science.gov (United States)

    Drummond, L. V.; Melatos, A.

    2017-12-01

    Three-dimensional, Gross-Pitaevskii equation (GPE) simulations are presented of the interaction between neutron superfluid vortices and proton superconductor flux tubes in a rotating, harmonic trap, representing an idealized model of the outer core of a neutron star. Low-energy states of the neutron condensate are calculated by evolving the GPE in imaginary time in the presence of a prescribed, static, rectilinear flux tube array. The calculations are carried out as a function of the angle between the global magnetic and rotation axes, and the amplitude and sign of the current-current and density couplings between the neutron and proton condensates. It is found that the system is frustrated by the competition between vortex-vortex repulsion and vortex-flux-tube attraction (pinning), leading to the formation of vortex tangles and 'glassy' behaviour characterized by multiple metastable states spaced closely in energy. The dimensionless parameters in the simulations are ordered as one expects in a neutron star, but the dynamic range is many orders of magnitude smaller than in reality, so caution must be exercised when assessing the astrophysical implications. Nevertheless, the results suggest that tangled vorticity may be endemic in neutron star outer cores.

  2. Magnetic swirls and associated fast magnetoacoustic kink waves in a solar chromospheric flux tube

    Science.gov (United States)

    Murawski, K.; Kayshap, P.; Srivastava, A. K.; Pascoe, D. J.; Jelínek, P.; Kuźma, B.; Fedun, V.

    2018-02-01

    We perform numerical simulations of impulsively generated magnetic swirls in an isolated flux tube that is rooted in the solar photosphere. These swirls are triggered by an initial pulse in a horizontal component of the velocity. The initial pulse is launched either (a) centrally, within the localized magnetic flux tube or (b) off-central, in the ambient medium. The evolution and dynamics of the flux tube are described by three-dimensional, ideal magnetohydrodynamic equations. These equations are numerically solved to reveal that in case (a) dipole-like swirls associated with the fast magnetoacoustic kink and m = 1 Alfvén waves are generated. In case (b), the fast magnetoacoustic kink and m = 0 Alfvén modes are excited. In both these cases, the excited fast magnetoacoustic kink and Alfvén waves consist of a similar flow pattern and magnetic shells are also generated with clockwise and counter-clockwise rotating plasma within them, which can be the proxy of dipole-shaped chromospheric swirls. The complex dynamics of vortices and wave perturbations reveals the channelling of sufficient amount of energy to fulfil energy losses in the chromosphere (˜104 W m-1) and in the corona (˜102 W m-1). Some of these numerical findings are reminiscent of signatures in recent observational data.

  3. A comparison of critical heat flux in tubes and bilaterally heated annuli

    Energy Technology Data Exchange (ETDEWEB)

    Doerffer, S.; Groeneveld, D.C.; Cheng, S.C. [Univ. of Ottawa (Canada)

    1995-09-01

    This paper examines the critical heat flux (CHF) behaviour for annular flow in bilaterally heated annuli and compares it to that in tubes and unilaterally heated annuli. It was found that the differences in CHF between bilaterally and unilaterally heated annuli or tubes strongly depend on pressure and quality. the CHF in bilaterally heated annuli can be predicted by tube CHF prediction methods for the simultaneous CHF occurrence at both surfaces, and the following flow conditions: pressure 7-10 MPa, mass flux 0.5-4.0 Mg/m{sup 2}s and critical quality 0.23-0.9. The effect on CHF of the outer-to-inner surface heat flux ratio, was also examined. The prediction of CHF for bilaterally heated annuli was based on the droplet-diffusion model proposed by Kirillov and Smogalev. While their model refers only to CHF occurrence at the inner surface, we extended it to cases where CHF occurs at the outer surface, and simultaneously at both surfaces, thus covering all cases of CHF occurrence in bilaterally heated annuli. From the annuli CHF data of Becker and Letzter, we derived empirical functions required by the model. the proposed equations provide good accuracy for the CHF data used in this study. Moreover, the equations can predict conditions at which CHF occurs simultaneously at both surfaces. Also, this method can be used for cases with only one heated surface.

  4. Propagation and Dispersion of Sausage Wave Trains in Magnetic Flux Tubes

    Science.gov (United States)

    Oliver, R.; Ruderman, M. S.; Terradas, J.

    2015-06-01

    A localized perturbation of a magnetic flux tube produces wave trains that disperse as they propagate along the tube, where the extent of dispersion depends on the physical properties of the magnetic structure, on the length of the initial excitation, and on its nature (e.g., transverse or axisymmetric). In Oliver et al. we considered a transverse initial perturbation, whereas the temporal evolution of an axisymmetric one is examined here. In both papers we use a method based on Fourier integrals to solve the initial value problem. We find that the propagating wave train undergoes stronger attenuation for longer axisymmetric (or shorter transverse) perturbations, while the internal to external density ratio has a smaller effect on the attenuation. Moreover, for parameter values typical of coronal loops axisymmetric (transverse) wave trains travel at a speed 0.75-1 (1.2) times the Alfvén speed of the magnetic tube. In both cases, the wave train passage at a fixed position of the magnetic tube gives rise to oscillations with periods of the order of seconds, with axisymmetric disturbances causing more oscillations than transverse ones. To test the detectability of propagating transverse or axisymmetric wave packets in magnetic tubes of the solar atmosphere (e.g., coronal loops, spicules, or prominence threads) a forward modeling of the perturbations must be carried out.

  5. PROPAGATION AND DISPERSION OF SAUSAGE WAVE TRAINS IN MAGNETIC FLUX TUBES

    International Nuclear Information System (INIS)

    Oliver, R.; Terradas, J.; Ruderman, M. S.

    2015-01-01

    A localized perturbation of a magnetic flux tube produces wave trains that disperse as they propagate along the tube, where the extent of dispersion depends on the physical properties of the magnetic structure, on the length of the initial excitation, and on its nature (e.g., transverse or axisymmetric). In Oliver et al. we considered a transverse initial perturbation, whereas the temporal evolution of an axisymmetric one is examined here. In both papers we use a method based on Fourier integrals to solve the initial value problem. We find that the propagating wave train undergoes stronger attenuation for longer axisymmetric (or shorter transverse) perturbations, while the internal to external density ratio has a smaller effect on the attenuation. Moreover, for parameter values typical of coronal loops axisymmetric (transverse) wave trains travel at a speed 0.75–1 (1.2) times the Alfvén speed of the magnetic tube. In both cases, the wave train passage at a fixed position of the magnetic tube gives rise to oscillations with periods of the order of seconds, with axisymmetric disturbances causing more oscillations than transverse ones. To test the detectability of propagating transverse or axisymmetric wave packets in magnetic tubes of the solar atmosphere (e.g., coronal loops, spicules, or prominence threads) a forward modeling of the perturbations must be carried out

  6. PROPAGATION AND DISPERSION OF SAUSAGE WAVE TRAINS IN MAGNETIC FLUX TUBES

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, R.; Terradas, J. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Ruderman, M. S., E-mail: ramon.oliver@uib.es [School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2015-06-10

    A localized perturbation of a magnetic flux tube produces wave trains that disperse as they propagate along the tube, where the extent of dispersion depends on the physical properties of the magnetic structure, on the length of the initial excitation, and on its nature (e.g., transverse or axisymmetric). In Oliver et al. we considered a transverse initial perturbation, whereas the temporal evolution of an axisymmetric one is examined here. In both papers we use a method based on Fourier integrals to solve the initial value problem. We find that the propagating wave train undergoes stronger attenuation for longer axisymmetric (or shorter transverse) perturbations, while the internal to external density ratio has a smaller effect on the attenuation. Moreover, for parameter values typical of coronal loops axisymmetric (transverse) wave trains travel at a speed 0.75–1 (1.2) times the Alfvén speed of the magnetic tube. In both cases, the wave train passage at a fixed position of the magnetic tube gives rise to oscillations with periods of the order of seconds, with axisymmetric disturbances causing more oscillations than transverse ones. To test the detectability of propagating transverse or axisymmetric wave packets in magnetic tubes of the solar atmosphere (e.g., coronal loops, spicules, or prominence threads) a forward modeling of the perturbations must be carried out.

  7. Spectropolarimetric Evidence for a Siphon Flow along an Emerging Magnetic Flux Tube

    Energy Technology Data Exchange (ETDEWEB)

    Requerey, Iker S.; Cobo, B. Ruiz [Instituto de Astrofísica de Canarias, Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Iniesta, J. C. Del Toro; Suárez, D. Orozco [Instituto de Astrofísica de Andalucía (CSIC), Apdo. de Correos 3004, E-18080 Granada (Spain); Rodríguez, J. Blanco [Grupo de Astronomía y Ciencias del Espacio, Universidad de Valencia, E-46980 Paterna, Valencia (Spain); Solanki, S. K.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Riethmüller, T. L.; Noort, M. van [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Schmidt, W. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, D-79104 Freiburg (Germany); Pillet, V. Martínez [National Solar Observatory, 3665 Discovery Drive, Boulder, CO 80303 (United States); Knölker, M., E-mail: iker@iac.es [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States)

    2017-03-01

    We study the dynamics and topology of an emerging magnetic flux concentration using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board the sunrise balloon-borne solar observatory. We obtain the full vector magnetic field and the line of sight (LOS) velocity through inversions of the Fe i line at 525.02 nm with the SPINOR code. The derived vector magnetic field is used to trace magnetic field lines. Two magnetic flux concentrations with different polarities and LOS velocities are found to be connected by a group of arch-shaped magnetic field lines. The positive polarity footpoint is weaker (1100 G) and displays an upflow, while the negative polarity footpoint is stronger (2200 G) and shows a downflow. This configuration is naturally interpreted as a siphon flow along an arched magnetic flux tube.

  8. Switching process between bistable positons of multiquantum flux tubes in a thin-film type I superconductor

    International Nuclear Information System (INIS)

    Parisi, J.; Huebener, R.P.; Muhlemeier, B.

    1983-01-01

    A superconducting memory device based on a bistable vortex position represents an interesting storage medium for future Josephson computers. In order to study the operational mode of such a single-flux quantum memory cell, we use as a model system multiquantum flux tubes in a thin-film type I superconductor (Pb). By employing high-resolution stroboscopic magnetooptical flux detection, we are able to globally visualize both spatial and temporal behavior of rapidly switching individual flux tubes. All experimental results agree reasonably well with theoretical model considerations of the energy balance during the elementary switching process

  9. GENERATION OF MAGNETOHYDRODYNAMIC WAVES IN LOW SOLAR ATMOSPHERIC FLUX TUBES BY PHOTOSPHERIC MOTIONS

    International Nuclear Information System (INIS)

    Mumford, S. J.; Fedun, V.; Erdélyi, R.

    2015-01-01

    Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale magnetic flux tubes are generated via the interaction of granulation motion and the background magnetic field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a magnetic flux tube embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy flux. The wave energy flux distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total flux) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon flux surface radius

  10. Generation of Magnetohydrodynamic Waves in Low Solar Atmospheric Flux Tubes by Photospheric Motions

    Science.gov (United States)

    Mumford, S. J.; Fedun, V.; Erdélyi, R.

    2015-01-01

    Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale magnetic flux tubes are generated via the interaction of granulation motion and the background magnetic field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a magnetic flux tube embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy flux. The wave energy flux distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total flux) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon flux surface radius.

  11. GENERATION OF MAGNETOHYDRODYNAMIC WAVES IN LOW SOLAR ATMOSPHERIC FLUX TUBES BY PHOTOSPHERIC MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mumford, S. J.; Fedun, V.; Erdélyi, R., E-mail: s.mumford@sheffield.ac.uk [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH UK (United Kingdom)

    2015-01-20

    Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale magnetic flux tubes are generated via the interaction of granulation motion and the background magnetic field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a magnetic flux tube embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy flux. The wave energy flux distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total flux) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon flux surface radius.

  12. Sunspots and the physics of magnetic flux tubes. III - Aerodynamic lift

    Science.gov (United States)

    Parker, E. N.

    1979-01-01

    The aerodynamic lift exerted on a magnetic flux tube by the asymmetric flow around the two sides of the tube is calculated as part of an investigation of the physics of solar flux tubes. The general hydrodynamic forces on a rigid circular cylinder in a nonuniform flow of an ideal fluid are derived from the first derivatives of the velocity field. Aerodynamic lift in a radial nonuniform flow is found to act in the direction of the flow, toward the region of increased flow velocity, while in a shear flow, lift is perpendicular to the free stream and directed toward increasing flow velocity. For a general, three dimensional, large-scale stationary incompressible equilibrium flow, an expression is also derived relating the lift per unit length to the dynamical pressure, cylinder radius and the gradient of the free-stream velocity. Evidence from an asymmetric airfoil in a uniform flow indicates that lift is enhanced in a real fluid in the presence of turbulence.

  13. A study on the critical heat flux for annuli and round tubes under low pressure conditions

    International Nuclear Information System (INIS)

    Park, Jae Wook

    1997-02-01

    This study aims to reveal the characteristics of the critical heat flux (CHF) of internally heated concentric annuli and vertical round tubes in low-pressure and low-flow (LPLF) conditions. Although many efforts have been devote to the subject of the CHF during the last forty years, the information on the CHF phenomenon for LPLF conditions is still very limited. The applicable ranges of the CHF correlations for annuli and round tubes are concentrate on the operating conditions of nuclear power plant (NPP), namely high-pressure and high-flow (HPHF) conditions. these facts promoted to collect the reliable CHF data for LPLF conditions for both annuli and round tubes. The critical heat flux data for vertical flow boiling of water in annuli and round tubes at low pressures and low mass fluxes show the following trends: The observed CHF mechanism for annuli was changed in the order of flooding, churn-to-annular flow transition, and local dryout under a large bubble in churn flow as the flow rate was increased from zero to higher values. The observed parametric trends for annuli are consistent with the previous understanding except that the CHF for downward flow is considerably lower (up to 40%) than that for upward flow. The critical quality is much lower than that for round tubes at the same inlet conditions. The observed parametric trends for round tubes are generally consistent with the previous understanding except for system pressure an tube diameter effect. For the system pressure effect, it is observed that the pressure effect is complicated but not so large, whereas the existing CHF correlations do not present the parametric trend exactly. For tube diameter effect, the decreasing trends of CHF with respect to tube diameter was the general understanding so far, but in this region the CHF show a increasing trend of tube diameter. The prediction and the parametric trend analyses are performed by two view points, I.e., for fixed inlet conditions and for local

  14. The dynamic evolution of active-region-scale magnetic flux tubes in the turbulent solar convective envelope

    Science.gov (United States)

    Weber, Maria Ann

    2014-12-01

    The Sun exhibits cyclic properties of its large-scale magnetic field on the order of sigma22 years, with a ˜11 year frequency of sunspot occurrence. These sunspots, or active regions, are the centers of magnetically driven phenomena such as flares and coronal mass ejections. Volatile solar magnetic events directed toward the Earth pose a threat to human activities and our increasingly technological society. As such, the origin and nature of solar magnetic flux emergence is a topic of global concern. Sunspots are observable manifestations of solar magnetic fields, thus providing a photospheric link to the deep-seated dynamo mechanism. However, the manner by which bundles of magnetic field, or flux tubes, traverse the convection zone to eventual emergence at the solar surface is not well understood. To provide a connection between dynamo-generated magnetic fields and sunspots, I have performed simulations of magnetic flux emergence through the bulk of a turbulent, solar convective envelope by employing a thin flux tube model subject to interaction with flows taken from a hydrodynamic convection simulation computed through the Anelastic Spherical Harmonic (ASH) code. The convective velocity field interacts with the flux tube through the drag force it experiences as it traverses through the convecting medium. Through performing these simulations, much insight has been gained about the influence of turbulent solar-like convection on the flux emergence process and resulting active region properties. I find that the dynamic evolution of flux tubes change from convection dominated to magnetic buoyancy dominated as the initial field strength of the flux tubes increases from 15 kG to 100 kG. Additionally, active-region-scale flux tubes of 40 kG and greater exhibit properties similar to those of active regions on the Sun, such as: tilt angles, rotation rates, and morphological asymmetries. The joint effect of the Coriolis force and helical motions present in convective

  15. External glass peening of zircaloy calandria tubes to increase the critical heat flux

    International Nuclear Information System (INIS)

    Fong, R.W.L.; Coleman, C.E.; Nitheanandan, T.; Kroeger, V.D.; Moyer, R.G.; Sanderson, D.B.; Root, J.H.; Rogge, R.B.

    1997-12-01

    Glass-peening the outside surfaces of Zircaloy calandria tubes increases the nucleation sites available for boiling heat transfer and has been demonstrated to enhance the critical heat flux (CHF) in pool-boiling experiments. The objective of this study is to optimise the heat-transfer enhancement by glass peening while ensuring that the microstructure of the peened tube is acceptable for reactor use. Pool-boiling tests were done using small Zircaloy tubes with as-received ('smooth') surfaces and variously peened surfaces, to evaluate two peening parameters, glass-bead size and the coverage of peened surface. Our results showed that the maximum enhancement of CHF (by 60% compared with as-received tubes) was obtained using a glass-bead size of 90-125 μm with a coverage of 100%. The CHF enhancement was found to be insensitive to glass-bead size over a wide range (from 60-90 μm to 125-180 μm). Using a fixed glass-bead size of 125-180 μm to evaluate the influence of peening coverage, the maximum effect on the CHF response was obtained with a coverage of 1 00%. The microstructures of the peened tubes were evaluated using light microscopy, X-ray and neutron diffraction, and mechanical tests. After peening, the microstructure in the subsurface layer (-30 μm) consisted of deformed α-Zr grains, and the crystallographic texture of the grains changed slightly. After stress-relieving at 500 degrees C for 1 h, some recrystallisation had occurred and the residual strains remaining in the tube were low. The tensile and burst properties of glass-peened and stress-relieved tubes were similar to those of as-received tubes. The microstructures introduced by peening and stress relieving were judged to have little effect on creep and growth behaviour. Since there are no deleterious consequences of the glass-peening treatment, the peened and stress-relieved tubes are found to be acceptable for reactor use. (author)

  16. An Analytical Model for Prediction of Magnetic Flux Leakage from Surface Defects in Ferromagnetic Tubes

    Directory of Open Access Journals (Sweden)

    Suresh V.

    2016-02-01

    Full Text Available In this paper, an analytical model is proposed to predict magnetic flux leakage (MFL signals from the surface defects in ferromagnetic tubes. The analytical expression consists of elliptic integrals of first kind based on the magnetic dipole model. The radial (Bz component of leakage fields is computed from the cylindrical holes in ferromagnetic tubes. The effectiveness of the model has been studied by analyzing MFL signals as a function of the defect parameters and lift-off. The model predicted results are verified with experimental results and a good agreement is observed between the analytical and the experimental results. This analytical expression could be used for quick prediction of MFL signals and also input data for defect reconstructions in inverse MFL problem.

  17. Sunspots and the physics of magnetic flux tubes. III. Aerodynamic lift

    International Nuclear Information System (INIS)

    Parker, E.N.

    1979-01-01

    The aerodynamic lift on a rigid circular cylinder of radius a in a nonuniform free stream is calculated to first order in the derivatives of the free-stream velocity, u(r). The lift per unit length, is of the order of the dynamical pressure 1/2rhou 2 times (a 2 /u 2 ) vertical-bardelu 2 vertical-bar. The results have application to the motion of flux tubes in the Sun. Illustrative examples are provided in subsequent papers of this series

  18. NUMERICAL SIMULATIONS OF PLASMA DYNAMICS IN THE VICINITY OF A RETRACTING FLUX TUBE

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Roger B.; Longcope, Dana W.; McKenzie, David E. [Montana State University P.O. Box 173840 Bozeman, MT 59717-3840 (United States)

    2016-11-01

    In a previous paper, we presented an analytical, zero- β model for supra-arcade downflows in which a retracting flux tube deforms the surrounding magnetic field, constricting the flow of plasma along affected field lines and, in some cases, forcing the plasma to exhibit collimated shocks. Here we present a numerical simulation based on the same model construction—a retracting flux tube is treated as a rigid boundary around which the plasma is forced to flow and the magnetic field and plasma evolve according to the governing equations of magnetohydrodynamics. We find that the collimated shocks described in our previous study are recovered for plasma β in the range of 0 ≤ β ≲ 1, while for 1 ≲ β the behavior is similar to the simpler hydrodynamic case, with classical bow shocks forming when the acoustic Mach number approaches or exceeds unity. Furthermore, we find that while the plasma β is important for identifying the various types of behaviors, more important still is the Alfvén Mach number, which, if large, implies that the bulk kinetic energy of the fluid exceeds the internal energy of the magnetic field, thereby leading to the formation of unconfined, fast-mode magnetosonic shocks, even in the limit of small β .

  19. Interactions between vortex tubes and magnetic-flux rings at high kinetic and magnetic Reynolds numbers

    Science.gov (United States)

    Kivotides, Demosthenes

    2018-03-01

    The interactions between vortex tubes and magnetic-flux rings in incompressible magnetohydrodynamics are investigated at high kinetic and magnetic Reynolds numbers, and over a wide range of the interaction parameter. The latter is a measure of the turnover time of the large-scale fluid motions in units of the magnetic damping time, or of the strength of the Lorentz force in units of the inertial force. The small interaction parameter results, which are related to kinematic turbulent dynamo studies, indicate the evolution of magnetic rings into flattened spirals wrapped around the vortex tubes. This process is also observed at intermediate interaction parameter values, only now the Lorentz force creates new vortical structures at the magnetic spiral edges, which have a striking solenoid vortex-line structure, and endow the flattened magnetic-spiral surfaces with a curvature. At high interaction parameter values, the decisive physical factor is Lorentz force effects. The latter create two (adjacent to the magnetic ring) vortex rings that reconnect with the vortex tube by forming an intriguing, serpentinelike, vortex-line structure, and generate, in turn, two new magnetic rings, adjacent to the initial one. In this regime, the morphologies of the vorticity and magnetic field structures are similar. The effects of these structures on kinetic and magnetic energy spectra, as well as on the direction of energy transfer between flow and magnetic fields, are also indicated.

  20. Propagation and dispersion of transverse wave trains in magnetic flux tubes

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, R.; Terradas, J. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Ruderman, M. S., E-mail: ramon.oliver@uib.es [School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2014-07-01

    The dispersion of small-amplitude, impulsively excited wave trains propagating along a magnetic flux tube is investigated. The initial disturbance is a localized transverse displacement of the tube that excites a fast kink wave packet. The spatial and temporal evolution of the perturbed variables (density, plasma displacement, velocity, ...) is given by an analytical expression containing an integral that is computed numerically. We find that the dispersion of fast kink wave trains is more important for shorter initial disturbances (i.e., more concentrated in the longitudinal direction) and for larger density ratios (i.e., for larger contrasts of the tube density with respect to the environment density). This type of excitation generates a wave train whose signature at a fixed position along a coronal loop is a short event (duration ≅ 20 s) in which the velocity and density oscillate very rapidly with typical periods of the order of a few seconds. The oscillatory period is not constant but gradually declines during the course of this event. Peak values of the velocity are of the order of 10 km s{sup –1} and are accompanied by maximum density variations of the order of 10%-15% the unperturbed loop density.

  1. Closed flux tubes and their string description in D=3 1 SU(N) gauge theories

    International Nuclear Information System (INIS)

    Athenodorou, Andreas; Bringoltz, Barak; Teper, Michael

    2010-08-01

    We calculate the energy spectrum of a confining flux tube that is closed around a spatial torus, as a function of its length l. We do so for various SU(N) gauge theories in 3+1 dimensions, and for various values of spin, parity and longitudinal momentum. We are able to present usefully accurate results for about 20 of the lightest such states, for a range of l that begins close to the (finite volume) deconfining phase transition at l√σ ∝ 1.6, and extends up to l√σ∝6 (where σ is the string tension). We find that most of these low-lying states are well described by the spectrum of the Nambu-Goto free string theory in flat space-time. Remarkably, this is so not only at the larger values of l, where the gap between the ground state energy and the low-lying excitations becomes small compared to the mass gap, but also down to much shorter lengths where these excitation energies become large compared to √σ, the flux-tube no longer 'looks' anything like a thin string, and an expansion of the effective string action in powers of 1/l no longer converges. All this is for flux in the fundamental representation. We also calculate the k=2 (anti)symmetric ground states and these show larger corrections at small l. So far all this closely resembles our earlier findings in 2+1 dimensions. However, and in contrast to the situation in D=2+1, we also find that there are some states, with J P =0 - quantum numbers, that show large deviations from the Nambu-Goto spectrum. We investigate the possibility that (some of) these states may encode the massive modes associated with the internal structure of the flux tube, and we discuss how the precocious free string behaviour of most states constrains the effective string action, on which much interesting theoretical progress has recently been made. (orig.)

  2. Assembly and Delivery of Rabbit Capsules for Irradiation of Silicon Carbide Cladding Tube Specimens in the High Flux Isotope Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Koyanagi, Takaaki [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Petrie, Christian M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-01

    Neutron irradiation of silicon carbide (SiC)-based fuel cladding under a high radial heat flux presents a critical challenge for SiC cladding concepts in light water reactors (LWRs). Fission heating in the fuel provides a high heat flux through the cladding, which, combined with the degraded thermal conductivity of SiC under irradiation, results in a large temperature gradient through the thickness of the cladding. The strong temperature dependence of swelling in SiC creates a complex stress profile in SiCbased cladding tubes as a result of differential swelling. The Nuclear Science User Facilities (NSUF) Program within the US Department of Energy Office of Nuclear Energy is supporting research efforts to improve the scientific understanding of the effects of irradiation on SiC cladding tubes. Ultimately, the results of this project will provide experimental validation of multi-physics models for SiC-based fuel cladding during LWR operation. The first objective of this project is to irradiate tube specimens using a previously developed design that allows for irradiation testing of miniature SiC tube specimens subjected to a high radial heat flux. The previous “rabbit” capsule design uses the gamma heating in the core of the High Flux Isotope Reactor (HFIR) to drive a high heat flux through the cladding tube specimens. A compressible aluminum foil allows for a constant thermal contact conductance between the cladding tubes and the rabbit housing despite swelling of the SiC tubes. To allow separation of the effects of irradiation from those due to differential swelling under a high heat flux, a new design was developed under the NSUF program. This design allows for irradiation of similar SiC cladding tube specimens without a high radial heat flux. This report briefly describes the irradiation experiment design concepts, summarizes the irradiation test matrix, and reports on the successful delivery of six rabbit capsules to the HFIR. Rabbits of both low and high

  3. Influence of Electric Fields and Conductivity on Pollen Tube Growth assessed via Electrical Lab-on-Chip

    Science.gov (United States)

    Agudelo, Carlos; Packirisamy, Muthukumaran; Geitmann, Anja

    2016-01-01

    Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and processed in the pollen tube is still poorly understood. Evidence for electrical guidance in particular is vague and highly contradictory. To generate reproducible experimental conditions for the investigation of the effect of electric fields on pollen tube growth we developed an Electrical Lab-on-Chip (ELoC). Pollen from the species Camellia displayed differential sensitivity to electric fields depending on whether the entire cell or only its growing tip was exposed. The response to DC fields was dramatically higher than that to AC fields of the same strength. However, AC fields were found to restore and even promote pollen growth. Surprisingly, the pollen tube response correlated with the conductivity of the growth medium under different AC frequencies—consistent with the notion that the effect of the field on pollen tube growth may be mediated via its effect on the motion of ions. PMID:26804186

  4. Influence of Electric Fields and Conductivity on Pollen Tube Growth assessed via Electrical Lab-on-Chip.

    Science.gov (United States)

    Agudelo, Carlos; Packirisamy, Muthukumaran; Geitmann, Anja

    2016-01-25

    Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and processed in the pollen tube is still poorly understood. Evidence for electrical guidance in particular is vague and highly contradictory. To generate reproducible experimental conditions for the investigation of the effect of electric fields on pollen tube growth we developed an Electrical Lab-on-Chip (ELoC). Pollen from the species Camellia displayed differential sensitivity to electric fields depending on whether the entire cell or only its growing tip was exposed. The response to DC fields was dramatically higher than that to AC fields of the same strength. However, AC fields were found to restore and even promote pollen growth. Surprisingly, the pollen tube response correlated with the conductivity of the growth medium under different AC frequencies--consistent with the notion that the effect of the field on pollen tube growth may be mediated via its effect on the motion of ions.

  5. Upstream magnetospheric ion flux tube within a magnetic cloud: Wind/STICS

    Science.gov (United States)

    Posner, Arik; Liemohn, Michael W.; Zurbuchen, Thomas H.

    2003-03-01

    We present a case study of a remarkable upstream O+ and N+ ion outflow event. We present observational evidence for spatially structured outflow of these Low Charge State Heavy Ions (LCSHIs) of magnetospheric origin along a small reconnected field line region within the framework of a magnetic cloud of an ICME. From the particles' in situ 3D distribution function we conclude that in this case the interaction of the outflow with the bow shock is small. We conclude further that the gyrophases of outflowing ions at the reconnection point are randomly distributed. This leads to the formation of a flux tube with a specific geometry. In particular, the outflow reveals spatial dispersion and non-gyrotropy. This result has implications for the size of the dayside reconnection site.

  6. Turbulent Heat Transfer Behavior of Nanofluid in a Circular Tube Heated under Constant Heat Flux

    Directory of Open Access Journals (Sweden)

    Shuichi Torii

    2010-01-01

    Full Text Available The aim of the present study is to disclose the forced convective heat transport phenomenon of nanofluids inside a horizontal circular tube subject to a constant and uniform heat flux at the wall. Consideration is given to the effect of the inclusion of nanoparticles on heat transfer enhancement, thermal conductivity, viscosity, and pressure loss in the turbulent flow region. It is found that (i heat transfer enhancement is caused by suspending nanoparticles and becomes more pronounced with the increase of the particle volume fraction, (ii its augmentation is affected by three different nanofluids employed here, and (iii the presence of particles produces adverse effects on viscosity and pressure loss that also increases with the particle volume fraction.

  7. Meson emissions from quark-gluon plasma through formation and fission of chromoelectric flux tubes

    International Nuclear Information System (INIS)

    Matsui, T.; Banerjee, B.; Glendenning, N.K.

    1983-06-01

    In the present work we study a facet of the plasma evolution, the formation and radiation of mesons at the surface of hog plasma. The surface meson radiation would play two important roles. First, it may carry some information about the pre-freezeout stage of the plasma evolution. Second, it causes a pressure decrease at the surface that works against the expansion. In the extreme, the plasma may extinct very rapidly by the surface meson radiation without collective expansion. It is very unclear how the incident quark degrees of freedom is converted into mesonic degrees of freedom and how the color confinement works in such a process. We have studied the problem by fully employing the chromoelectric flux tube model. We found that their parametrization is quite unsatisfactory and is actually incompatible with a dynamical description of color confinement. We briefly recapitulate our treatments and findings

  8. Critical heat flux and transition boiling characteristics for a sodium-heated steam generator tube for LMFBR applications

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, S.; Holmes, D.H.

    1977-04-01

    An experimental program was conducted to characterize critical heat flux (CHF) in a sodium-heated steam generator tube model at a proposed PLBR steam generator design pressure of 7.2 MPa. Water was circulated vertically upward in the tube and the heating sodium was flowing counter-current downward. The experimental ranges were: mass flux, 110 to 1490 kg/s.m/sup 2/ (0.08 to 1.10 10/sup 6/ lbm/h.ft/sup 2/); critical heat flux, 0.16 to 1.86 MW/m/sup 2/ (0.05 to 0.59 10/sup 6/ Btu/h.ft/sup 2/); and critical quality, 0.48 to 1.0. The CHF phenomenon for the experimental conditions is determined to be dryout as opposed to departure from nucleate boiling (DNB). The data are divided into high- and low-mass flux regions.

  9. On the look-up tables for the critical heat flux in tubes (history and problems)

    Energy Technology Data Exchange (ETDEWEB)

    Kirillov, P.L.; Smogalev, I.P. [Institute of Physics and Power Engineering, Kaluga (Russian Federation)

    1995-09-01

    The complication of critical heat flux (CHF) problem for boiling in channels is caused by the large number of variable factors and the variety of two-phase flows. The existence of several hundreds of correlations for the prediction of CHF demonstrates the unsatisfactory state of this problem. The phenomenological CHF models can provide only the qualitative predictions of CHF primarily in annular-dispersed flow. The CHF look-up tables covered the results of numerous experiments received more recognition in the last 15 years. These tables are based on the statistical averaging of CHF values for each range of pressure, mass flux and quality. The CHF values for regions, where no experimental data is available, are obtained by extrapolation. The correction of these tables to account for the diameter effect is a complicated problem. There are ranges of conditions where the simple correlations cannot produce the reliable results. Therefore, diameter effect on CHF needs additional study. The modification of look-up table data for CHF in tubes to predict CHF in rod bundles must include a method which to take into account the nonuniformity of quality in a rod bundle cross section.

  10. Simulation of the space-time evolution of color-flux tubes (guidelines to the TERMITE program)

    International Nuclear Information System (INIS)

    Dyrek, A.

    1990-08-01

    We give the description of the computer program which simulates boost-invariant evolution of color-flux tubes in high-energy processes. The program provides a graphic demonstration of space-time trajectories of created particles and can also be used as Monte-Carlo generator of events. (author)

  11. Width and string tension of the flux tube in SU(2) lattice gauge theory at high temperature

    Science.gov (United States)

    Chagdaa, S.; Galsandorj, E.; Laermann, E.; Purev, B.

    2018-02-01

    We study the profiles of the flux tube between a static quark and an antiquark in quenched SU(2) lattice gauge theory at temperatures around the deconfinement phase transition. The physical width of the flux tube and the string tension have been determined from the transverse profiles and the q\\bar{q} potential, respectively. Exploiting the computational power of a GPU accelerator in our flux tube investigation, we achieve much higher statistics through which we can increase the signal to noise ratio of our observables in the simulation. This has allowed the investigation of larger lattices as well as larger separations between the quarks than in our previous work. The improved accuracy gives us better results for the width and the string tension. The physical width of the flux tube increases with the temperature up to around T c while keeping its increasing dependence on the q\\bar{q} separation. The string tension results are compared for two different sizes of the lattice. As the lattice becomes larger and finer together with the improved precision, the temperature dependent string tension tends to have a smaller value than the previous one.

  12. Flux tubes and the type-I/type-II transition in a superconductor coupled to a superfluid

    International Nuclear Information System (INIS)

    Alford, Mark G.; Good, Gerald

    2008-01-01

    We analyze magnetic-flux tubes at zero temperature in a superconductor that is coupled to a superfluid via both density and gradient ('entrainment') interactions. The example we have in mind is high-density nuclear matter, which is a proton superconductor and a neutron superfluid, but our treatment is general and simple, modeling the interactions as a Ginzburg-Landau effective theory with four-fermion couplings, including only s-wave pairing. We numerically solve the field equations for flux tubes with an arbitrary number of flux quanta and compare their energies. This allows us to map the type-I/type-II transition in the superconductor, which occurs at the conventional κ≡λ/ξ=1/√(2) if the condensates are uncoupled. We find that a density coupling between the condensates raises the critical κ and, for a sufficiently high neutron density, resolves the type-I/type-II transition line into an infinite number of bands corresponding to 'type-II(n)' phases, in which n, the number of quanta in the favored flux tube, steps from 1 to infinity. For lower neutron density, the coupling creates spinodal regions around the type-I/type-II boundary, in which metastable flux configurations are possible. We find that a gradient coupling between the condensates lowers the critical κ and creates spinodal regions. These exotic phenomena may not occur in nuclear matter, which is thought to be deep in the type-II region but might be observed in condensed-matter systems

  13. Electrical properties of various types of straw tubes considered for the LHCb outer tracker

    CERN Document Server

    Gromov, V

    2001-01-01

    Because of the appreciable length (up to 3.6 m) of the straw tube modules of the Outer Tracker, transmission line effects will have impact on their operational properties. These effects were clearly observed in a 1.6 m long prototype. A few types of straw tubes have been examined from the point of view of electrical properties, with emphasis on the study of signal transmission and cross-talk.

  14. Nonperturbative quantization ‘a la Heisenberg for non-Abelian gauge theories: two-equation approximation. Applications: a flux tube solution and a scalar model of glueball

    Directory of Open Access Journals (Sweden)

    Dzhunushaliev Vladimir

    2017-01-01

    Full Text Available The nonperturbative quantization technique à la Heisenberg is applied for the SU(3 gauge theory. The operator Yang-Mills equation and corresponding infinite set of equations for all Green’s functions are considered. Gauge degrees of freedom are splitted into two groups: (1 Aμa ∈ SU (2 × U(1 ⊂ SU(3; (2 coset degrees of freedom SU(3/SU(2 × U(1. Using some assumptions about 2- and 4-point Green’s functions, the infinite set of equations is truncated to two equations. The first equation is the SU(2 × U(1 Yang-Mills equation, and the second equation describes a gluon condensate formed by coset fields. A flux tube solution describing longitudinal color electric fields stretched between quark and antiquark located at the ± infinities is obtained. It is shown that the dual Meissner effect appears in this solution: the electric field is pushed out from the gluon condensate.

  15. Irradiation of Wrought FeCrAl Tubes in the High Flux Isotope Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Linton, Kory D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Petrie, Christian M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-01

    The Advanced Fuels Campaign within the Nuclear Technology Research and Development program of the Department of Energy Office of Nuclear Energy is seeking to improve the accident tolerance of light water reactors. Alumina-forming ferritic alloys (e.g., FeCrAl) are one of the leading candidate materials for fuel cladding to replace traditional zirconium alloys because of the superior oxidation resistance of FeCrAl. However, there are still some unresolved questions regarding irradiation effects on the microstructure and mechanical properties of FeCrAl at end-of-life dose levels. In particular, there are concerns related to irradiation-induced embrittlement of FeCrAl alloys due to secondary phase formation. To address this issue, Oak Ridge National Laboratory has developed a new experimental design to irradiate shortened cladding tube specimens with representative 17×17 array pressurized water reactor diameter and thickness in the High Flux Isotope Reactor (HFIR) under relevant temperatures (300–350°C). Post-irradiation examination will include studies of dimensional change, microstructural changes, and mechanical performance. This report briefly summarizes the capsule design concept and the irradiation test matrix for six rabbit capsules. Each rabbit contains two FeCrAl alloy tube specimens. The specimens include Generation I and Generation II FeCrAl alloys with varying processing conditions, Cr concentrations, and minor alloying elements. The rabbits were successfully assembled, welded, evaluated, and delivered to the HFIR along with a complete quality assurance fabrication package. Pictures of the rabbit assembly process and detailed dimensional inspection of select specimens are included in this report. The rabbits were inserted into HFIR starting in cycle 472 (May 2017).

  16. THE BEHAVIOR OF TRANSVERSE WAVES IN NONUNIFORM SOLAR FLUX TUBES. I. COMPARISON OF IDEAL AND RESISTIVE RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume; Oliver, Ramón [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Goossens, Marcel, E-mail: roberto.soler@uib.es [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven (Belgium)

    2013-11-10

    Magnetohydrodynamic (MHD) waves are ubiquitously observed in the solar atmosphere. Kink waves are a type of transverse MHD waves in magnetic flux tubes that are damped due to resonant absorption. The theoretical study of kink MHD waves in solar flux tubes is usually based on the simplification that the transverse variation of density is confined to a nonuniform layer much thinner than the radius of the tube, i.e., the so-called thin boundary approximation. Here, we develop a general analytic method to compute the dispersion relation and the eigenfunctions of ideal MHD waves in pressureless flux tubes with transversely nonuniform layers of arbitrary thickness. Results for kink waves are produced and compared with fully numerical resistive MHD eigenvalue computations in the limit of small resistivity. We find that the frequency and resonant damping rate are the same in both ideal and resistive cases. The actual results for thick nonuniform layers deviate from the behavior predicted in the thin boundary approximation and strongly depend on the shape of the nonuniform layer. The eigenfunctions in ideal MHD are very different from those in resistive MHD. The ideal eigenfunctions display a global character regardless of the thickness of the nonuniform layer, while the resistive eigenfunctions are localized around the resonance and are indistinguishable from those of ordinary resistive Alfvén modes. Consequently, the spatial distribution of wave energy in the ideal and resistive cases is dramatically different. This poses a fundamental theoretical problem with clear observational consequences.

  17. Magnetic trapping of energetic particles on open dayside boundary layer flux tubes

    International Nuclear Information System (INIS)

    Cowley, S.W.H.; Lewis, Z.V.

    1990-01-01

    Both simple as well as detailed empirical magnetic models of the Earth's dayside magnetosphere suggest that field lines near the magnetopause boundary in the noon quadrant (∼ 09:00 to ∼ 15:00 M.L.T.) possess an unusual property due to the compressive effect of the impinging solar wind flow, namely that the equatorial region represents a local maximum in the magnetic field strength, and not a minimum as elsewhere in the magnetosphere. In this region the field lines can therefore support two distinct particle populations, those which bounce across the equator between mirror points on either side, and those which are trapped about the off-equatorial field strength minima and are confined to one side of the equator. When these field lines become magnetically open due to the occurrence of magnetic reconnection at the equatorial magnetopause, the former particles will rapidly escape into the magnetosheath by field-aligned flow, while the latter population may be sustained within the boundary layer over many bounce periods, as the flux tubes contract and move tailward. Consequently, trapped distributions of energetic particles may commonly occur on open field lines in the dayside boundary layer in the noon quadrant, particularly at high latitudes. The existence of such particles is thus not an infallible indicator of the presence of closed magnetic field lines in this region. At earlier and later local times, however, the boundary layer field lines revert to possessing a minimum in the field strength at the equator. (author)

  18. MAGNETOHYDRODYNAMIC KINK WAVES IN NONUNIFORM SOLAR FLUX TUBES: PHASE MIXING AND ENERGY CASCADE TO SMALL SCALES

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume, E-mail: roberto.soler@uib.es [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2015-04-10

    Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or magnetic field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.

  19. Kink-induced full and failed eruptions of two coupled flux tubes of the same filament

    Science.gov (United States)

    Dechev, M.; Koleva, K.; Duchlev, P.

    2018-02-01

    In this work, we report results from the study of a filament/prominence eruption on 2014 May 4. This eruption belongs to the class of rarely reported causally linked eruptions of two coupled flux tubes (FTs) of a quiet region filament. We made a comparative analysis based on multiwave observations from Solar Dynamics Observatory (SDO) and Solar Terrestrial Relations Observatory (STEREO) A and B combining the high temporal and spatial data taken from three different viewpoints. The main results of the study are as follows: (1) The source of the eruptive prominence consists of two coupled FTs located near the eastern limb: top-located one (FT1) and bottom-located one (FT2). (2) FT1 and FT2 had the same helicity, i.e. left-handed twist and writhe. Their untwisting motion during eruption suggests that kink instability seems to act. (3) The kinematic evolution of the FT1 suggests a slow successful eruption that was associated with a slow CME. (4) The FT2 exhibited failed kinked eruption with a non-radial propagation followed by its reformation. This eruption was accompanied of apparent mass draining in the legs, flare-ribbons and post-flare EUV arcade.

  20. Prediction of forced convective heat transfer and critical heat flux for subcooled water flowing in miniature tubes

    Science.gov (United States)

    Shibahara, Makoto; Fukuda, Katsuya; Liu, Qiusheng; Hata, Koichi

    2018-02-01

    The heat transfer characteristics of forced convection for subcooled water in small tubes were clarified using the commercial computational fluid dynamic (CFD) code, PHENICS ver. 2013. The analytical model consists of a platinum tube (the heated section) and a stainless tube (the non-heated section). Since the platinum tube was heated by direct current in the authors' previous experiments, a uniform heat flux with the exponential function was given as a boundary condition in the numerical simulation. Two inner diameters of the tubes were considered: 1.0 and 2.0 mm. The upward flow velocities ranged from 2 to 16 m/s and the inlet temperature ranged from 298 to 343 K. The numerical results showed that the difference between the surface temperature and the bulk temperature was in good agreement with the experimental data at each heat flux. The numerical model was extended to the liquid sublayer analysis for the CHF prediction and was evaluated by comparing its results with the experimental data. It was postulated that the CHF occurs when the fluid temperature near the heated wall exceeds the saturated temperature, based on Celata et al.'s superheated layer vapor replenishment (SLVR) model. The suggested prediction method was in good agreement with the experimental data and with other CHF data in literature within ±25%.

  1. On magnetohydrodynamic thermal instabilities in magnetic flux tubes. [in plane parallel stellar atmosphere in LTE and hydrostatic equilibrium

    Science.gov (United States)

    Massaglia, S.; Ferrari, A.; Bodo, G.; Kalkofen, W.; Rosner, R.

    1985-01-01

    The stability of current-driven filamentary modes in magnetic flux tubes embedded in a plane-parallel atmosphere in LTE and in hydrostatic equilibrium is discussed. Within the tube, energy transport by radiation only is considered. The dominant contribution to the opacity is due to H- ions and H atoms (in the Paschen continuum). A region in the parameter space of the equilibrium configuration in which the instability is effective is delimited, and the relevance of this process for the formation of structured coronae in late-type stars and accretion disks is discussed.

  2. Miniature X-ray Tube for Electric Brachytherapy using Carbon Nanotube Field Emitter

    International Nuclear Information System (INIS)

    Heo, Sung Hwan; Kim, Hyun Jin; Ha, Jun Mok; Cho, Sung Oh

    2011-01-01

    An electric brachytherapy using a miniature x-ray tube has a major advantage to reduce the x-ray exposure of human body during the cancer radiation therapy by optimal positioning of x-ray radiation source and treatment objectives. In the view of a smaller electronic x-ray source, the CNT field emitter based xray tube can be more minimized than thermionic filament emitter based one because of a simple power supplier connection of cold field emission in diode type as well as a higher electron emission brightness of CNT. This abstract is for introducing the design of a prototype CNT field emitter based miniature x-ray tube. We have vacuum sealed CNT miniature x-ray tube with 7∼10 mm diameter, and characteristics of electron emission and x-ray transportation using MCNP5 code are surveyed

  3. Critical heat flux experiments in a circular tube with heavy water and light water. (AWBA Development Program)

    International Nuclear Information System (INIS)

    Williams, C.L.; Beus, S.G.

    1980-05-01

    Experiments were performed to establish the critical heat flux (CHF) characteristics of heavy water and light water. Testing was performed with the up-flow of heavy and of light water within a 0.3744 inch inside diameter circular tube with 72.3 inches of heated length. Comparisons were made between heavy water and light water critical heat flux levels for the same local equilibrium quality at CHF, operating pressure, and nominal mass velocity. Results showed that heavy water CHF values were, on the average, 8 percent below the light water CHF values

  4. The development of an auto-sealing system using an electrically shrinkable tube under a low-pressure condition

    Energy Technology Data Exchange (ETDEWEB)

    Okano, Yoshihiro; Kitagawa, Takao [NKK Corp, Tsu, Mie (Japan); Shoji, Norio [NKK Corp., Yokohama (Japan); Namioka, Toshiyuki [Nippon Kokan Koji Corp., Yokohama (Japan). Research and Development Dept.; Komura, Minoru [Nitto Denko Corp., Fukaya, Saitama (Japan)

    1997-04-01

    This article describes the development of a system to create high quality, automatic sealing of field joints of polyethylene coated pipelines. The system uses a combination of an electrically heated shrinkable tube and a low-pressure chamber. The self-heating shrinkable tube includes electric heater wires that heat when connected to electricity. A method was developed to eliminate air trapped between the tube and the steel pipe by shrinking the tube under a low-pressure condition. The low-pressure condition was automatic and easily attained by using a vacuum chamber. It was verified that the system produced high quality sealing of the field joints.

  5. Lava tube shatter rings and their correlation with lava flux increases at Kīlauea Volcano, Hawai‘i

    Science.gov (United States)

    Orr, T.R.

    2011-01-01

    Shatter rings are circular to elliptical volcanic features, typically tens of meters in diameter, which form over active lava tubes. They are typified by an upraised rim of blocky rubble and a central depression. Prior to this study, shatter rings had not been observed forming, and, thus, were interpreted in many ways. This paper describes the process of formation for shatter rings observed at Kīlauea Volcano during November 2005–July 2006. During this period, tilt data, time-lapse images, and field observations showed that episodic tilt changes at the nearby Pu‘u ‘Ō‘ō cone, the shallow magmatic source reservoir, were directly related to fluctuations in the level of lava in the active lava tube, with periods of deflation at Pu‘u ‘Ō‘ō correlating with increases in the level of the lava stream surface. Increases in lava level are interpreted as increases in lava flux, and were coincident with lava breakouts from shatter rings constructed over the lava tube. The repetitive behavior of the lava flux changes, inferred from the nearly continuous tilt oscillations, suggests that shatter rings form from the repeated rise and fall of a portion of a lava tube roof. The locations of shatter rings along the active lava tube suggest that they form where there is an abrupt decrease in flow velocity through the tube, e.g., large increase in tube width, abrupt decrease in tube slope, and (or) sudden change in tube direction. To conserve volume, this necessitates an abrupt increase in lava stream depth and causes over-pressurization of the tube. More than a hundred shatter rings have been identified on volcanoes on Hawai‘i and Maui, and dozens have been reported from basaltic lava fields in Iceland, Australia, Italy, Samoa, and the mainland United States. A quick study of other basaltic lava fields worldwide, using freely available satellite imagery, suggests that they might be even more common than previously thought. If so, this confirms that episodic

  6. Linear magnetic motor/generator. [to generate electric energy using magnetic flux for spacecraft power supply

    Science.gov (United States)

    Studer, P. A. (Inventor)

    1982-01-01

    A linear magnetic motor/generator is disclosed which uses magnetic flux to provide mechanical motion or electrical energy. The linear magnetic motor/generator includes an axially movable actuator mechanism. A permament magnet mechanism defines a first magnetic flux path which passes through a first end portion of the actuator mechanism. Another permament magnet mechanism defines a second magnetic flux path which passes through a second end portion of the actuator mechanism. A drive coil defines a third magnetic flux path passing through a third central portion of the actuator mechanism. A drive coil selectively adds magnetic flux to and subtracts magnetic flux from magnetic flux flowing in the first and second magnetic flux path.

  7. Sunspots and the physics of magnetic flux tubes. IV. Aerodynamic lift on a thin cylinder in convective flows

    International Nuclear Information System (INIS)

    Tsinganos, K.C.

    1979-01-01

    The aerodynamic lift exerted on a long circular cylinder immersed in a convective flow pattern in an ideal fluid is calculated to establish the equilibrium position of the cylinder. The calculations establish the surprising result that the cylinder is pushed out of the upwellings and the downdrafts of the convective cell, into a location midway between them.The implications for the intense magnetic flux tubes in the convection beneath the surface of the Sun are considered

  8. Sunspots and the physics of magnetic flux tubes. IV - Aerodynamic lift on a thin cylinder in convective flows

    Science.gov (United States)

    Tsinganos, K. C.

    1979-01-01

    The aerodynamic lift exerted on a long circular cylinder immersed in a convective flow pattern in an ideal fluid is calculated to establish the equilibrium position of the cylinder. The calculations establish the surprising result that the cylinder is pushed out the upwellings and the downdrafts of the convective cell, into a location midway between them. The implications for the intense magnetic flux tubes in the convection beneath the surface of the sun are considered.

  9. Critical heat flux characteristics of R-113 boiling two-phase flow in twisted-tape-inserted tubes

    International Nuclear Information System (INIS)

    Lee, Sangr-Youl; Inoue, Akira; Takahashi, Minoru

    1995-01-01

    This paper presents experimental data on the critical heat flux (CHF) in twisted-tape-inserted tubes over a wide quality range of -0.25 to 0.8. The influences of quality, twist ratio, mass velocity, and clearance between the twisted tape and tube inner wall on CHF were investigated. In the subcooled region, it was observed, using an infrared thermoviewer, that CHF was initiated locally at the wall near the twisted tape. Consequently, twisted tape insertion with small tape-wall clearance decreased CHF to below the value in the empty tubes at a low flow rate. This decrease was found to be avoidable by adjusting the clearance. In the net quality region, CHF in the twisted-tape-inserted tubes increased with increasing flow rate contrary to the case of the empty tubes. However, CHF in the net quality region was also decreased by insertion of twisted tapes with high twist ratio (loosely twisted tapes) at a very low flow rate. (author)

  10. Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event

    Directory of Open Access Journals (Sweden)

    K. A. McWilliams

    2000-12-01

    Full Text Available Line-of-sight Doppler velocities from the SuperDARN CUTLASS HF radar pair have been combined to produce the first two-dimensional vector measurements of the convection pattern throughout the ionospheric footprint of a flux transfer event (a pulsed ionospheric flow, or PIF. Very stable and moderate interplanetary magnetic field conditions, along with a preceding prolonged period of northward interplanetary magnetic field, allow a detailed study of the spatial and the temporal evolution of the ionospheric response to magnetic reconnection. The flux tube footprint is tracked for half an hour across six hours of local time in the auroral zone, from magnetic local noon to dusk. The motion of the footprint of the newly reconnected flux tube is compared with the ionospheric convection velocity. Two primary intervals in the PIF's evolution have been determined. For the first half of its lifetime in the radar field of view the phase speed of the PIF is highly variable and the mean speed is nearly twice the ionospheric convection speed. For the final half of its lifetime the phase velocity becomes much less variable and slows down to the ionospheric convection velocity. The evolution of the flux tube in the magnetosphere has been studied using magnetic field, magnetopause and magnetosheath models. The data are consistent with an interval of azimuthally propagating magnetopause reconnection, in a manner consonant with a peeling of magnetic flux from the magnetopause, followed by an interval of anti-sunward convection of reconnected flux tubes.Key words: Magnetospheric physics (magnetosphere · ionosphere interactions; plasma convection; solar wind · magnetosphere interactions

  11. Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event

    Directory of Open Access Journals (Sweden)

    K. A. McWilliams

    Full Text Available Line-of-sight Doppler velocities from the SuperDARN CUTLASS HF radar pair have been combined to produce the first two-dimensional vector measurements of the convection pattern throughout the ionospheric footprint of a flux transfer event (a pulsed ionospheric flow, or PIF. Very stable and moderate interplanetary magnetic field conditions, along with a preceding prolonged period of northward interplanetary magnetic field, allow a detailed study of the spatial and the temporal evolution of the ionospheric response to magnetic reconnection. The flux tube footprint is tracked for half an hour across six hours of local time in the auroral zone, from magnetic local noon to dusk. The motion of the footprint of the newly reconnected flux tube is compared with the ionospheric convection velocity. Two primary intervals in the PIF's evolution have been determined. For the first half of its lifetime in the radar field of view the phase speed of the PIF is highly variable and the mean speed is nearly twice the ionospheric convection speed. For the final half of its lifetime the phase velocity becomes much less variable and slows down to the ionospheric convection velocity. The evolution of the flux tube in the magnetosphere has been studied using magnetic field, magnetopause and magnetosheath models. The data are consistent with an interval of azimuthally propagating magnetopause reconnection, in a manner consonant with a peeling of magnetic flux from the magnetopause, followed by an interval of anti-sunward convection of reconnected flux tubes.

    Key words: Magnetospheric physics (magnetosphere · ionosphere interactions; plasma convection; solar wind · magnetosphere interactions

  12. Enhancement of magnetic flux distribution in a DC superconducting electric motor

    International Nuclear Information System (INIS)

    Hamid, N A; Ewe, L S; Chin, K M

    2013-01-01

    Most motor designs require an air gap between the rotor and stator to enable the armature to rotate freely. The interaction of magnetic flux from rotor and stator within the air gap will provide the thrust for rotational motion. Thus, the understanding of magnetic flux in the vicinity of the air gap is very important to mathematically calculate the magnetic flux generated in the area. In this work, a finite element analysis was employed to study the behavior of the magnetic flux in view of designing a synchronous DC superconducting electric motor. The analysis provides an ideal magnetic flux distribution within the components of the motor. From the flux plot analysis, it indicates that flux losses are mainly in the forms of leakage and fringe effect. The analysis also shows that the flux density is high at the area around the air gap and the rotor. The high flux density will provide a high force area that enables the rotor to rotate. In contrast, the other parts of the motor body do not show high flux density indicating low distribution of flux. Consequently, a bench top model of a DC superconducting motor was developed where by motor with a 2-pole type winding was chosen. Each field coil was designed with a racetrack-shaped double pancake wound using DI-BSCCO Bi-2223 superconducting tapes. The performance and energy efficiency of the superconducting motor was superior when compared to the conventional motor with similar capacity.

  13. Flux estimation algorithms for electric drives: a comparative study

    OpenAIRE

    Koteich , Mohamad

    2016-01-01

    International audience; This paper reviews the stator flux estimation algorithms applied to the alternating current motor drives. The so-called voltage model estimation, which consists of integrating the back-electromotive force signal, is addressed. However, in practice , the pure integration is prone to drift problems due to noises, measurement error, stator resistance uncertainty and unknown initial conditions. This limitation becomes more restrictive at low speed operation. Several soluti...

  14. Radiant and convective heat transfer for flow of a transparent gas in a short tube with prescribed sinusoidal wall heat flux

    International Nuclear Information System (INIS)

    de Lemos, M.J.S.

    1982-01-01

    The present analysis accounts for radiant and convective heat transfer for a transparent fluid flowing in a short tube with prescribed wall heat flux. The heat flux distribution used was of sine shape with maximum at the middle of the tube. Such a solution is the approximate one for axial power in a nuclear reactor. The solutions for the tube wall and gas bulk temperatures were obtained by successive substitutions for the wall and gas balance energy equations. The results show a decrease of 30% for the maximum wall temperature using black surface (e = 1). In this same case, the increasing in the gas temperature shows a decrease of 58%

  15. Influence of the Coriolis force on flux tubes rising through the solar convection zone

    International Nuclear Information System (INIS)

    Choudhuri, A.R.; Gilman, P.A.

    1987-01-01

    In order to study the effect of the Coriolis force due to solar rotation on rising magnetic flux, the authors consider a flux ring, azimuthally symmetric around the rotation axis, starting from rest at the bottom of the convection zone, and then follow the trajectory of the flux ring as it rises. If it is assumed that the flux ring remains azimuthally symmetric during its ascent, then the problem can be described essentially in terms of two parameters: the value of the initial magnetic field in the ring when it starts, and the effective drag experienced by it. For field strengths at the bottom of the convection zone of order 10,000 G or less, it is found that the Coriolis force plays a dominant role and flux rings starting from low latitudes at the bottom are deflected and emerge at latitudes significantly poleward of sunspot zones. 40 references

  16. A data set of critical heat flux of boiling R-12 in uniformly heated vertical tubes under transient conditions

    International Nuclear Information System (INIS)

    Celata, G.P.; Cumo, M.; D'Annibale, F.; Farello, G.E.

    1989-01-01

    A critical heat flux (CHF) data set under transient conditions employing R-12 as the test fluid is provided. Transients were carried out by varying one, two or three parameters among flow rate, pressure and thermal power, taking care of investigating all possible combinations. The- parameters not interested by the variation were kept constant during the test. Reference steady-state CHF tests were conducted in a wide experimental range and presented here. The employed test section is a stainless steel tube (7.72 mm ID, 9.52 mm OD) heatedby the direct passage of a DC current

  17. Mechanism of subcooled water flow boiling critical heat flux in a circular tube at high liquid Reynolds number

    International Nuclear Information System (INIS)

    Hata, K.; Fukuda, K.; Masuzaki, S.

    2014-01-01

    The subcooled boiling heat transfer and the steady state critical heat flux (CHF) in a vertical circular tube for the flow velocities (u=3.95 to 30.80 m/s) are systematically measured by the experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The SUS304 test tube of inner diameter (d=6 mm) and heated length (L=59.5 mm) is used in this work. The outer surface temperatures of the SUS304 test tube with heating are observed by an infrared thermal imaging camera and a video camera. The subcooled boiling heat transfers for SUS304 test tube are compared with the values calculated by other workers' correlations for the subcooled boiling heat transfer. The influence of flow velocity on the subcooled boiling heat transfer and the CHF is investigated into details based on the experimental data. Nucleate boiling surface superheats at the CHF are close to the lower limit of the heterogeneous spontaneous nucleation temperature and the homogeneous spontaneous nucleation temperature. The dominant mechanism of the subcooled flow boiling CHF on the SUS304 circular tube is discussed at high liquid Reynolds number. On the other hand, theoretical equations for k-ε turbulence model in a circular tube of a 3 mm in diameter and a 526 mm long are numerically solved for heating of water on heated section of a 3 mm in diameter and a 67 mm long with various thicknesses of conductive sub-layer by using PHOENICS code under the same conditions as the experimental ones previously obtained considering the temperature dependence of thermo-physical properties concerned. The Platinum (Pt) test tube of inner diameter (d=3 mm) and heated length (L=66.5 mm) was used in this experiment. The thicknesses of conductive sub-layer from non-boiling regime to CHF are clarified. The thicknesses of conductive sub-layer at the CHF point are evaluated for various flow velocities. The experimental values of the CHF are also compared with the corresponding

  18. Magnetic Flux Rope Shredding By a Hyperbolic Flux Tube: The Detrimental Effects of Magnetic Topology on Solar Eruptions

    International Nuclear Information System (INIS)

    Chintzoglou, Georgios; Vourlidas, Angelos; Savcheva, Antonia; Tassev, Svetlin; Beltran, Samuel Tun; Stenborg, Guillermo

    2017-01-01

    We present the analysis of an unusual failed eruption captured in high cadence and in many wavelengths during the observing campaign in support of the Very high Angular resolution Ultraviolet Telescope ( VAULT2.0 ) sounding rocket launch. The refurbished VAULT2.0 is a Ly α ( λ 1216 Å) spectroheliograph launched on 2014 September 30. The campaign targeted active region NOAA AR 12172 and was closely coordinated with the Hinode and IRIS missions and several ground-based observatories (NSO/IBIS, SOLIS, and BBSO). A filament eruption accompanied by a low-level flaring event (at the GOES C-class level) occurred around the VAULT2.0 launch. No coronal mass ejection was observed. The eruption and its source region, however, were recorded by the campaign instruments in many atmospheric heights ranging from the photosphere to the corona in high cadence and spatial resolution. This is a rare occasion that enabled us to perform a comprehensive investigation on a failed eruption. We find that a rising Magnetic Flux Rope (MFR)-like structure was destroyed during its interaction with the ambient magnetic field, creating downflows of cool plasma and diffuse hot coronal structures reminiscent of “cusps.” We employ magnetofrictional simulations to show that the magnetic topology of the ambient field is responsible for the destruction of the MFR. Our unique observations suggest that the magnetic topology of the corona is a key ingredient for a successful eruption.

  19. Magnetic Flux Rope Shredding By a Hyperbolic Flux Tube: The Detrimental Effects of Magnetic Topology on Solar Eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Chintzoglou, Georgios [Lockheed Martin Solar and Astrophysics Laboratory, 3176 Porter Drive, Palo Alto, CA 94304 (United States); Vourlidas, Angelos [The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Savcheva, Antonia; Tassev, Svetlin [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Beltran, Samuel Tun; Stenborg, Guillermo, E-mail: gchintzo@lmsal.com [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2017-07-10

    We present the analysis of an unusual failed eruption captured in high cadence and in many wavelengths during the observing campaign in support of the Very high Angular resolution Ultraviolet Telescope ( VAULT2.0 ) sounding rocket launch. The refurbished VAULT2.0 is a Ly α ( λ 1216 Å) spectroheliograph launched on 2014 September 30. The campaign targeted active region NOAA AR 12172 and was closely coordinated with the Hinode and IRIS missions and several ground-based observatories (NSO/IBIS, SOLIS, and BBSO). A filament eruption accompanied by a low-level flaring event (at the GOES C-class level) occurred around the VAULT2.0 launch. No coronal mass ejection was observed. The eruption and its source region, however, were recorded by the campaign instruments in many atmospheric heights ranging from the photosphere to the corona in high cadence and spatial resolution. This is a rare occasion that enabled us to perform a comprehensive investigation on a failed eruption. We find that a rising Magnetic Flux Rope (MFR)-like structure was destroyed during its interaction with the ambient magnetic field, creating downflows of cool plasma and diffuse hot coronal structures reminiscent of “cusps.” We employ magnetofrictional simulations to show that the magnetic topology of the ambient field is responsible for the destruction of the MFR. Our unique observations suggest that the magnetic topology of the corona is a key ingredient for a successful eruption.

  20. Magnetic Flux Rope Shredding By a Hyperbolic Flux Tube: The Detrimental Effects of Magnetic Topology on Solar Eruptions

    Science.gov (United States)

    Chintzoglou, Georgios; Vourlidas, Angelos; Savcheva, Antonia; Tassev, Svetlin; Tun Beltran, Samuel; Stenborg, Guillermo

    2017-07-01

    We present the analysis of an unusual failed eruption captured in high cadence and in many wavelengths during the observing campaign in support of the Very high Angular resolution Ultraviolet Telescope (VAULT2.0) sounding rocket launch. The refurbished VAULT2.0 is a Lyα (λ 1216 Å) spectroheliograph launched on 2014 September 30. The campaign targeted active region NOAA AR 12172 and was closely coordinated with the Hinode and IRIS missions and several ground-based observatories (NSO/IBIS, SOLIS, and BBSO). A filament eruption accompanied by a low-level flaring event (at the GOES C-class level) occurred around the VAULT2.0 launch. No coronal mass ejection was observed. The eruption and its source region, however, were recorded by the campaign instruments in many atmospheric heights ranging from the photosphere to the corona in high cadence and spatial resolution. This is a rare occasion that enabled us to perform a comprehensive investigation on a failed eruption. We find that a rising Magnetic Flux Rope (MFR)-like structure was destroyed during its interaction with the ambient magnetic field, creating downflows of cool plasma and diffuse hot coronal structures reminiscent of “cusps.” We employ magnetofrictional simulations to show that the magnetic topology of the ambient field is responsible for the destruction of the MFR. Our unique observations suggest that the magnetic topology of the corona is a key ingredient for a successful eruption.

  1. Electrical conductivity and electron cyclotron current drive efficiencies for non-circular flux surfaces in tokamaks

    International Nuclear Information System (INIS)

    O'Brien, M.R.

    1989-01-01

    As is well known, the presence of electron trapping can strongly reduce the electrical conductivity and rf current drive efficiencies of tokamak plasmas. For example, the conductivity (in the low collisionality limit) of a flux surface with inverse aspect ratio ε=0.1 is approximately one half of the Spitzer conductivity (σ sp )for uniform magnetic fields. Previous estimates of these effects have assumed that the variation of magnetic field strength around a flux surface is given by the standard form for circular flux surfaces. (author) 11 refs., 4 figs

  2. Neutron flux determination at the horizontal beam tubes of the Rossendorf research reactor RFR

    International Nuclear Information System (INIS)

    Stephan, I.; Schneider, B.; Boehmer, B.; Boehme, K.; Mehner, H.C.

    1992-01-01

    To characterize the irradiation possibilities of the RFR, in particular the values concerning the steel tubes, diffusion- and transport-theoretical calculations have been made and supported by experiments. The measurements also served to provide secured data for the experts on the ad hoc committee ''Rossendorf Research Reactor'' to assess the neutron situation of German research reactors. (orig.) [de

  3. Closed flux tubes and their string description in D=3+1 SU(N) gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Athenodorou, Andreas [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Bringoltz, Barak [Washington Univ., Seattle, WA (United States). Dept. of Physics; Teper, Michael [Oxford Univ. (United Kingdom). Centre for Theoretical Physics

    2010-08-15

    We calculate the energy spectrum of a confining flux tube that is closed around a spatial torus, as a function of its length l. We do so for various SU(N) gauge theories in 3+1 dimensions, and for various values of spin, parity and longitudinal momentum. We are able to present usefully accurate results for about 20 of the lightest such states, for a range of l that begins close to the (finite volume) deconfining phase transition at l{radical}{sigma} {proportional_to} 1.6, and extends up to l{radical}{sigma}{proportional_to}6 (where {sigma} is the string tension). We find that most of these low-lying states are well described by the spectrum of the Nambu-Goto free string theory in flat space-time. Remarkably, this is so not only at the larger values of l, where the gap between the ground state energy and the low-lying excitations becomes small compared to the mass gap, but also down to much shorter lengths where these excitation energies become large compared to {radical}{sigma}, the flux-tube no longer 'looks' anything like a thin string, and an expansion of the effective string action in powers of 1/l no longer converges. All this is for flux in the fundamental representation. We also calculate the k=2 (anti)symmetric ground states and these show larger corrections at small l. So far all this closely resembles our earlier findings in 2+1 dimensions. However, and in contrast to the situation in D=2+1, we also find that there are some states, with J{sup P}=0{sup -} quantum numbers, that show large deviations from the Nambu-Goto spectrum. We investigate the possibility that (some of) these states may encode the massive modes associated with the internal structure of the flux tube, and we discuss how the precocious free string behaviour of most states constrains the effective string action, on which much interesting theoretical progress has recently been made. (orig.)

  4. Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Petrie, Christian M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Koyanagi, Takaaki [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McDuffee, Joel L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Deck, Christian P. [General Atomics, San Diego, CA (United States); Katoh, Yutai [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-04

    The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300–350 °C under a representative high heat flux (~0.66 MW/m2) during one cycle of irradiation in an un-instrumented “rabbit” capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansion of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. Furthermore, the success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.

  5. Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

    Science.gov (United States)

    Petrie, Christian M.; Koyanagi, Takaaki; McDuffee, Joel L.; Deck, Christian P.; Katoh, Yutai; Terrani, Kurt A.

    2017-08-01

    The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300-350 °C under a representative high heat flux (∼0.66 MW/m2) during one cycle of irradiation in an un-instrumented ;rabbit; capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansion of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. The success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.

  6. Thermohydraulics in rod bundles and critical heat flux in transient conditions in a tube

    International Nuclear Information System (INIS)

    Courtaud, M.; Roumy, R.

    1975-01-01

    After the determination of the scaling factor of Stevens's similitude for the pressure range of pressurized water vectors by comparison of critical heat flux data in from and in water, some examples of studies performed with freon are shown. The efficiency of the mixing vanes of spacer grids has been determined on the mixing phenomenon in single phase on critical heat flux. A calculation performed with the code FLICA using subchannel analysis on freon data transposed in water is in good agreement with the experiment. The influence of the number of spacer grids has been also shown. Critical heat fluxes have been determined in water at 140 bar in steady state and transient conditions on two tubular test sections. During the transient tests the flow rate was reduced by half in 0.5 seconds and the reincreased heat flux and inlet temperature remaining constant. These tests have shown the validity of the method which consists in using a critical heat flux correlation determined in steady state conditions applied with local transient conditions of enthalpy and mass velocity computed with the FLICA code [fr

  7. Thermalhydraulic behavior of electrically heated rod during a critical heat flux transient

    International Nuclear Information System (INIS)

    Lima, Rita de Cassia Fernandes de; Carajilescov, Pedro

    1997-01-01

    In nuclear reactors, the occurrence of critical heat flux leads to fuel rod overheating with clad fusion and radioactive products leakage. To predict the effects of such phenomenon, experiments are performed using electrically heated rods to simulate operational and accidental conditions of nuclear fuel rods. In the present work, a theoretical analysis of the drying and rewetting front propagation is performed during a critical heat flux experiment, starting with the application of slope of electrical power from steady state condition. After the occurrence of critical heat flux, the drying front propagation is predicted. After a few seconds, a power cut is considered and the rewetting front behavior is analytically observed. Studies done with several values of coolant mass flow rate show that this variable has more influence on the drying front velocity than on the rewetting one. (author)

  8. Effect of neutron flux on the frequency dependencies of electrical conductivity of silicon nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Huseynov, E.; Garibli, A., E-mail: elchin.huse@yahoo.com [National Nuclear Research Center, Department of Nanotechnology and Radiation Material Science, 1073, Inshaatchilar pr. 4, Baku (Azerbaijan)

    2016-11-01

    It has been reviewed the frequency dependencies of electrical conductivity of nanoparticles affected by neutron flux at different times and initial state, at various constant temperatures such as 100, 200, 300 and 400 K. Measurements have been carried out at each temperature at the different 97 values of frequency in the 1 Hz - 1 MHz range. From interdependence between real and imaginary parts of electrical conductivity it has been determined the type of conductivity. Moreover, in the work it is given the mechanism of electrical conductivity according to the obtained results. (Author)

  9. Critical heat flux of water in vertical tubes with an upper plenum and a closed bottom

    International Nuclear Information System (INIS)

    Kim, Hong Chae; Baek, Won Pil; Chang, Soon Heung

    2000-01-01

    An experimental study is conducted for vertical round tubes with an upper plenum and a closed bottom to investigate CHF behavior and CHF onset location under the counter-current condition. The measured CHF values are well predicted by general Wallis type flooding correlations. A 1-D steady state analytical flooding model for thermosyphon by El-Genk and Saber was assessed with the data and the liquid film thickness at the liquid entrance was calculated. The CHF onset position becomes different with L/D and D, and liquid entrance geometry affects only CHF values not CHF onset positions

  10. Drift flux model as approximation of two fluid model for two phase dispersed and slug flow in tube

    Energy Technology Data Exchange (ETDEWEB)

    Nigmatulin, R.I.

    1995-09-01

    The analysis of one-dimensional schematizing for non-steady two-phase dispersed and slug flow in tube is presented. Quasi-static approximation, when inertia forces because of the accelerations of the phases may be neglected, is considered. Gas-liquid bubbly and slug vertical upward flows are analyzed. Non-trivial theoretical equations for slip velocity for these flows are derived. Juxtaposition of the derived equations for slip velocity with the famous Zuber-Findlay correlation as cross correlation coefficients is criticized. The generalization of non-steady drift flux Wallis theory taking into account influence of wall friction on the bubbly or slug flows for kinematical waves is considered.

  11. Closed flux tubes and their string description in D=2+1 SU(N) gauge theories

    International Nuclear Information System (INIS)

    Athenodorou, Andreas; Bringoltz, Barak; Teper, Michael

    2011-08-01

    We carry out lattice calculations of the spectrum of confining flux tubes that wind around a spatial torus of variable length l, in 2+1 dimensions. We compare the energies of the lowest ∝30 states to the free string Nambu-Goto model and to recent results on the universal properties of effective string actions. Our most useful calculations are in SU(6) at a small lattice spacing, which we check is very close to the N→ ∞ continuum limit. We find that the energies, E n (l), are remarkably close to the predictions of the free string Nambu-Goto model, even well below the critical length at which the expansion of the Nambu-Goto energy in powers of 1/l 2 diverges and the series needs to be resummed. Our analysis of the ground state supports the universality of the O(1/l) and the O(1/l 3 ) corrections to σl, and we find that the deviations from Nambu-Goto at small l prefer a leading correction that is O(1/l 7 ), consistent with theoretical expectations. We find that the low-lying states that contain a single phonon excitation are also consistent with the leading O(1/l 7 ) correction dominating down to the smallest values of l. By contrast our analysis of the other light excited states clearly shows that for these states the corrections at smaller l resum to a much smaller effective power. Finally, and in contrast to our recent calculations in D=3+1, we find no evidence for the presence of any non-stringy states that could indicate the excitation of massive flux tube modes. (orig.)

  12. Closed flux tubes and their string description in D=2+1 SU(N) gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Athenodorou, Andreas [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Bringoltz, Barak [The Israeli Institute for Advanced Research (IIAR), Rehovot (Israel); Teper, Michael [Oxford Univ. (United Kingdom). Rudolf Peierls Centre for Theoretical Physics

    2011-08-15

    We carry out lattice calculations of the spectrum of confining flux tubes that wind around a spatial torus of variable length l, in 2+1 dimensions. We compare the energies of the lowest {proportional_to}30 states to the free string Nambu-Goto model and to recent results on the universal properties of effective string actions. Our most useful calculations are in SU(6) at a small lattice spacing, which we check is very close to the N{yields} {infinity} continuum limit. We find that the energies, E{sub n}(l), are remarkably close to the predictions of the free string Nambu-Goto model, even well below the critical length at which the expansion of the Nambu-Goto energy in powers of 1/l{sup 2} diverges and the series needs to be resummed. Our analysis of the ground state supports the universality of the O(1/l) and the O(1/l{sup 3}) corrections to {sigma}l, and we find that the deviations from Nambu-Goto at small l prefer a leading correction that is O(1/l{sup 7}), consistent with theoretical expectations. We find that the low-lying states that contain a single phonon excitation are also consistent with the leading O(1/l{sup 7}) correction dominating down to the smallest values of l. By contrast our analysis of the other light excited states clearly shows that for these states the corrections at smaller l resum to a much smaller effective power. Finally, and in contrast to our recent calculations in D=3+1, we find no evidence for the presence of any non-stringy states that could indicate the excitation of massive flux tube modes. (orig.)

  13. Thermalhydraulic behavior of electrically heated rods during critical heat flux transients

    International Nuclear Information System (INIS)

    Lima, Rita de Cassia Fernandes de

    1997-01-01

    In nuclear reactors, the occurrence of critical heat flux leads to fuel rod overheating with clad fusion and radioactive products leakage. To predict the effects of such phenomenon, experiments are performed utilizing heated rods to simulate operational and accidental conditions of nuclear fuel rods, with special attention to the phenomenon of boiling crisis. The use of mechanisms which detect the abrupt temperature rise allows the electric power switch off. These facts prevent the test section from damage. During the critical heat flux phenomenon the axial heat conduction becomes very important. The study of the dryout and rewetting fronts yields the analysis, planning and following of critical heat flux experiments. These facts are important during the reflooding of nuclear cores at severe accidents. In the present work it is performed a theoretical analysis of the drying and rewetting front propagation during a critical heat flux experiment, starting with the application of an electrical power step or power slope from steady state condition. After the occurrence of critical heat flux, it is predicted the drying front propagation. After a few seconds, a power cut is considered and the rewetting front behavior is analytically observed. In all these transients the coolant pressure is 13,5 MPa. For one of them, comparisons are done with a pressure of 8,00 MPa. Mass flow and enthalpy influences on the fronts velocities are also analysed. These results show that mass flow has more importance on the drying front velocities whereas the pressure alters strongly the rewetting ones. (author)

  14. Critical heat flux in bottom heated two-phase thermosyphon. Improvement in critical heat flux due to concentric tube; Katan shuchu kanetsugata niso netsu syphon no genkai netsu ryusoku. Nijukan ni yoru genkai netsu ryusoku no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Monde, M.; Mitsutake, Y. [Saga University, Saga (Japan). Faculty of Science and Engineering

    2000-02-25

    An experiment has been carried out to elucidate the critical heat flux (CHF) of an open two-phase thermosyphon with a bottom heated chamber in which heat is absorbed by evaporation of liquid. Another objective is to enhance the CHF using a concentric-tube by which counter-current flow of vapor and liquid in the throat of the chamber can be controlled well. The CHF data are measured for the saturated liquid of R 113 at a different pressure and different configuration of concentric tubes. The CHF data without the inner tube are in good agreement with the existing correlation and analytical result. The CHF increases by as much as several times of the CHF without the inner tube with an increase in the inner tube diameter up to a certain diameter of the inner tube and then decreases continuously as the inner tube diameter approaches the outer tube diameter. The optimum diameter of inner tube exists at which the CHF is maximum. (author)

  15. A flux-mnemonic permanent magnet brushless motor for electric vehicles

    Science.gov (United States)

    Yu, Chuang; Chau, K. T.; Liu, Xinhua; Jiang, J. Z.

    2008-04-01

    In this paper, a new permanent magnet (PM) brushless motor is proposed for electric vehicles. The key is to incorporate the concept of memory motors, namely, the online tunable flux-mnemonic PMs, into the stator doubly fed doubly salient PM motor, hence achieving effective air-gap flux control. By further employing the outer-rotor and double-layer-stator topology, the proposed motor takes the definite advantages of compact structure, low armature reaction, and direct-drive capability. Increasingly, this motor can offer the unique features of pole dropping and pole reversing. Finite element analysis and, hence, computer simulation are given to verify the validity of the proposed motor.

  16. Calcium and electrical signaling in arterial endothelial tubes: New insights into cellular physiology and cardiovascular function.

    Science.gov (United States)

    Behringer, Erik J

    2017-04-01

    The integral role of the endothelium during the coordination of blood flow throughout vascular resistance networks has been recognized for several decades now. Early examination of the distinct anatomy and physiology of the endothelium as a signaling conduit along the vascular wall has prompted development and application of an intact endothelial "tube" study model isolated from rodent skeletal muscle resistance arteries. Vasodilatory signals such as increased endothelial cell (EC) Ca 2+ ([Ca 2+ ] i ) and hyperpolarization take place in single ECs while shared between electrically coupled ECs through gap junctions up to distances of millimeters (≥2 mm). The small- and intermediate-conductance Ca 2+ activated K + (SK C a /IK C a or K C a 2.3/K C a 3.1) channels function at the interface of Ca 2+ signaling and hyperpolarization; a bidirectional relationship whereby increases in [Ca 2+ ] i activate SK C a /IK C a channels to produce hyperpolarization and vice versa. Further, the spatial domain of hyperpolarization among electrically coupled ECs can be finely tuned via incremental modulation of SK C a /IK C a channels to balance the strength of local and conducted electrical signals underlying vasomotor activity. Multifunctional properties of the voltage-insensitive SK C a /IK C a channels of resistance artery endothelium may be employed for therapy during the aging process and development of vascular disease. © 2016 John Wiley & Sons Ltd.

  17. High-energy x-ray detection of G359.89–0.08 (SGR A–E): magnetic flux tube emission powered by cosmic rays?

    DEFF Research Database (Denmark)

    Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.

    2014-01-01

    of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A–E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps Te...

  18. Advanced AC permanent magnet axial flux disc motor for electric passenger vehicle

    Science.gov (United States)

    Kliman, G. B.

    1982-01-01

    An ac permanent magnet axial flux disc motor was developed to operate with a thyristor load commutated inverter as part of an electric vehicle drive system. The motor was required to deliver 29.8 kW (40 hp) peak and 10.4 kW (14 hp) average with a maximum speed of 11,000 rpm. It was also required to run at leading power factor to commutate the inverter. Three motors were built.

  19. Estimation of electrical conductivity distribution within the human head from magnetic flux density measurement

    Science.gov (United States)

    Gao, Nuo; Zhu, S. A.; He, Bin

    2005-06-01

    We have developed a new algorithm for magnetic resonance electrical impedance tomography (MREIT), which uses only one component of the magnetic flux density to reconstruct the electrical conductivity distribution within the body. The radial basis function (RBF) network and simplex method are used in the present approach to estimate the conductivity distribution by minimizing the errors between the 'measured' and model-predicted magnetic flux densities. Computer simulations were conducted in a realistic-geometry head model to test the feasibility of the proposed approach. Single-variable and three-variable simulations were performed to estimate the brain-skull conductivity ratio and the conductivity values of the brain, skull and scalp layers. When SNR = 15 for magnetic flux density measurements with the target skull-to-brain conductivity ratio being 1/15, the relative error (RE) between the target and estimated conductivity was 0.0737 ± 0.0746 in the single-variable simulations. In the three-variable simulations, the RE was 0.1676 ± 0.0317. Effects of electrode position uncertainty were also assessed by computer simulations. The present promising results suggest the feasibility of estimating important conductivity values within the head from noninvasive magnetic flux density measurements.

  20. Effects of Oxidation and fractal surface roughness on the wettability and critical heat flux of glass-peened zirconium alloy tubes

    International Nuclear Information System (INIS)

    Fong, R.W.L.; Nitheanandan, T.; Bullock, C.D.; Slater, L.F.; McRae, G.A.

    2003-05-01

    Glass-bead peening the outside surfaces of zirconium alloy tubes has been shown to increase the Critical Heat Flux (CHF) in pool boiling of water. The CHF is found to correlate with the fractal roughness of the metal tube surfaces. In this study on the effect of oxidation on glass-peened surfaces, test measurements for CHF, surface wettability and roughness have been evaluated using various glass-peened and oxidized zirconium alloy tubes. The results show that oxidation changes the solid-liquid contact angle (i.e., decreases wettability of the metal-oxide surface), but does not change the fractal surface roughness, appreciably. Thus, oxidation of the glass-peened surfaces of zirconium alloy tubes is not expected to degrade the CHF enhancement obtained by glass-bead peening. (author)

  1. Cyclic Parameter Refinement of 4S-10 Hybrid Flux-Switching Motor for Lightweight Electric Vehicle

    Science.gov (United States)

    Rani, J. Abd; Sulaiman, E.; Kumar, R.

    2017-08-01

    A great deal of attention has been given to the reduction of lighting the vehicle because the lighter the vehicle the energy consumption is comparatively low. Hence, the lightweight electric vehicle was introduced for lower carbon footprint and the sizing of the vehicle itself. One of the components to reduce the weight of the vehicle is the propulsion system which comprised of electric motor functioning as the source of torque to drive the propulsion system of the machine. This paper presents the refinement methodology for the optimized design of the 4S-10P E-Core hybrid excitation flux switching motor. The purpose of the refinement methodology is to improve the torque production of the optimized motor. The result of the successful improvement of the torque production is justifiable for a lightweight electric vehicle to drive the propulsion system.

  2. Pulled microcapillary tube resonators with electrical readout for mass sensing applications.

    Science.gov (United States)

    Lee, Donghyuk; Kim, Joonhui; Cho, Nam-Joon; Kang, Taewook; Kauh, Sangken; Lee, Jungchul

    2016-10-03

    This paper reports a microfabrication-free approach to make hollow channel mass sensors by pulling a glass capillary and suspending it on top of a machined jig. A part of the pulled section makes simple contact with an actuation node and a quartz tuning fork (QTF) which acts as a sensing node. The two nodes define a pulled micro capillary tube resonator (PμTR) simply supported at two contacts. While a piezo actuator beneath the actuation node excites the PμTR, the QTF senses the resonance frequency of the PμTR. The proposed concept was validated by electrical and optical measurements of resonant spectra of PμTR. Then, different liquid samples including water, ethanol, glycerol, and their binary mixtures were introduced into the PμTR and the resonance frequency of the PμTR was measured as a function of liquid density. Density responsivity of -3,088 Hz-g -1  cm 3 obtained is comparable to those of microfabricated hollow resonators. With a micro droplet generation chip configured in series with the PμTR, size distribution of oil droplets suspended in water was successfully measured with the radius resolution of 31 nm at the average droplet radius, 28.47 μm. Overall, typical off-the-shelf parts simply constitute a resonant mass sensing system along with a convenient electrical readout.

  3. The sunspot cycle and solar magnetic fields. I - The mechanism as inferred from observation. II - The interaction of flux tubes with the convection zone

    Science.gov (United States)

    Giovanelli, R. G.

    The first part of the present work notes that solar magnetic and velocity field observations can be used to derive the course of events in the solar cycle; such observations differ from those of conventional dynamo theories in the matters of polar field reversal, the sunspot cycle, and the torsional oscillation. In the second part, the mechanisms of interaction between flux tubes or ropes and the convection zone are examined for their relevance to the sunspot cycle. The mechanisms encompass floating, transport, and the penetration of gas from outside the tubes. All previous studies are noted to contain one or more major errors, rendering their conclusions invalid. These errors invariably involve the assumption that Archimede's principle is applicable to flux ropes, that gas entry can be disregarded, or, in some cases, that floating criteria substantially depend on local phenomena. Attention is given to: (1) the transport of flux tubes by the slow poleward motions, and to the even slower systems that carry tube extensions downwards to depths of about 150 Mm and then equatorwards; (2) their magnetic field strengths; and (3) the amplitudes of the torsional oscillation. All major cycle observations are concluded to be accounted for by the novel dynamo mechanism discussed.

  4. Design and market considerations for axial flux superconducting electric machine design

    Science.gov (United States)

    Ainslie, M. D.; George, A.; Shaw, R.; Dawson, L.; Winfield, A.; Steketee, M.; Stockley, S.

    2014-05-01

    In this paper, the authors investigate a number of design and market considerations for an axial flux superconducting electric machine design that uses high temperature superconductors. The axial flux machine design is assumed to utilise high temperature superconductors in both wire (stator winding) and bulk (rotor field) forms, to operate over a temperature range of 65-77 K, and to have a power output in the range from 10s of kW up to 1 MW (typical for axial flux machines), with approximately 2-3 T as the peak trapped field in the bulk superconductors. The authors firstly investigate the applicability of this type of machine as a generator in small- and medium-sized wind turbines, including the current and forecasted market and pricing for conventional turbines. Next, a study is also carried out on the machine's applicability as an in-wheel hub motor for electric vehicles. Some recommendations for future applications are made based on the outcome of these two studies. Finally, the cost of YBCO-based superconducting (2G HTS) wire is analysed with respect to competing wire technologies and compared with current conventional material costs and current wire costs for both 1G and 2G HTS are still too great to be economically feasible for such superconducting devices.

  5. Flux

    DEFF Research Database (Denmark)

    Ravn, Ib

    . FLUX betegner en flyden eller strømmen, dvs. dynamik. Forstår man livet som proces og udvikling i stedet for som ting og mekanik, får man et andet billede af det gode liv end det, som den velkendte vestlige mekanicisme lægger op til. Dynamisk forstået indebærer det gode liv den bedst mulige...... kanalisering af den flux eller energi, der strømmer igennem os og giver sig til kende i vore daglige aktiviteter. Skal vores tanker, handlinger, arbejde, samvær og politiske liv organiseres efter stramme og faste regelsæt, uden slinger i valsen? Eller skal de tværtimod forløbe ganske uhindret af regler og bånd...

  6. Optimization of electrical parameters of windings used in axial flux electrical machines

    International Nuclear Information System (INIS)

    Uhrik, M.

    2012-01-01

    This paper deals with shape optimization of windings used in electrical machines with disc type construction. These machines have short axial length what makes them suitable for use in small wind-power turbines or in-wheel traction drives. Disc type construction of stator offers more possibilities for winding arrangements than are available in classical machines with cylindrical construction. To find out the best winding arrangement for the novel disc type machine construction a series of analytical calculations, simulations and experimental measurements were performed. (Authors)

  7. Neuromuscular electrical stimulation efficacy in acute stroke feeding tube-dependent dysphagia during inpatient rehabilitation.

    Science.gov (United States)

    Kushner, David S; Peters, Kenneth; Eroglu, Stacy Thomashaw; Perless-Carroll, Melissa; Johnson-Greene, Douglas

    2013-06-01

    The aim of this study was to compare the efficacy of neuromuscular electrical stimulation (NMES) in addition to traditional dysphagia therapy (TDT) including progressive resistance training (PRT) with that of TDT/PRT alone during inpatient rehabilitation for treatment of feeding tube-dependent dysphagia in patients who have had an acute stroke. This study is an inpatient rehabilitation case-control study involving 92 patients who have had an acute stroke with initial Functional Oral Intake Scale (FOIS) scores of 3 or lower and profound to severe feeding tube-dependent dysphagia. Sixty-five patients, the NMES group, received NMES with TDT/PRT, and 27 patients, the case-control group, received only TDT/PRT. Treatment occurred in hourly sessions daily for a mean ± SD of 18 ± 3 days. χ(2) Analyses/t tests revealed no significant statistical differences between the groups for age (t = -0.85; P = 0.40), sex (χ(2) = 0.05; P = 0.94), and stroke location (χ(2) = 4.2; P = 0.24). A Mann-Whitney U test revealed a statistically significant difference between the groups for the initial FOIS score (z = -2.4; P = 0.015), with the NMES group having worse initial scores with a mean rank of 42.64 and the case-control TDT/PRT group having a mean rank of 55.8. The main outcome measure was the comparison of the FOIS scores after treatment. The mean ± SD FOIS score after NMES with TDT/PRT treatment was 5.1 ± 1.8 compared with 3.3 ± 2.2 in the case-control TDT/PRT group. The mean gain for the NMES group was 4.4 points; and for the case-control group, 2.4 points. Significant improvement in swallowing performance was found for the NMES group compared with the TDT/PRT group (z = 3.64; P rehabilitation in reducing feeding tube-dependent dysphagia in patients who have had an acute stroke.

  8. Control of a Dual-Stator Flux-Modulated Motor for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Xinhua Guo

    2016-07-01

    Full Text Available This paper presents the control strategies for a novel dual-stator flux-modulated (DSFM motor for application in electric vehicles (EVs. The DSFM motor can be applied to EVs because of its simple winding structure, high reliability, and its use of two stators and rotating modulation steels in the air gap. Moreover, it outperforms conventional brushless doubly-fed machines in terms of control performance. Two stator-current-oriented vector controls with different excitation in the primary winding, direct and alternating current excitation, are designed, simulated, and evaluated on a custom-made DSFM prototype allowing the decoupled control of torque. The stable speed response and available current characteristics strongly validate the feasibility of the two control methods. Furthermore, the proposed control methods can be employed in other applications of flux-modulated motors.

  9. A theoretical computerized study for the electrical conductivity of arterial pulsatile blood flow by an elastic tube model.

    Science.gov (United States)

    Shen, Hua; Zhu, Yong; Qin, Kai-Rong

    2016-12-01

    The electrical conductivity of pulsatile blood flow in arteries is an important factor for the application of the electrical impedance measurement system in clinical settings. The electrical conductivity of pulsatile blood flow depends not only on blood-flow-induced red blood cell (RBC) orientation and deformation but also on artery wall motion. Numerous studies have investigated the conductivity of pulsatile blood based on a rigid tube model, in which the effects of wall motion on blood conductivity are not considered. In this study, integrating Ling and Atabek's local flow theory and Maxwell-Fricke theory, we develop an elastic tube model to explore the effects of wall motion as well as blood flow velocity on blood conductivity. The simulation results suggest that wall motion, rather than blood flow velocity, is the primary factor that affects the conductivity of flowing blood in arteries. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  10. A Novel Concept of Short-Flux Path Switched Reluctance Motor for Electrical Vehicles

    Directory of Open Access Journals (Sweden)

    Milan Diko

    2015-01-01

    Full Text Available This paper deals with the design of a novel Switched Reluctance Motor (SRM with short flux path for electrical vehicles. Design consists of the segmented water cooled stator with the toroidal winding and the rotor with salient poles also in a form of segments. The SRM dimensions have been calculated on the base of input requirements. The static and dynamic parameters of SRM are obtained from simulation models based on Finite element method and torque, power versus speed characteristics are presented.

  11. Stability of interlinked neutron vortex and proton flux-tube arrays in a neutron star - II. Far-from-equilibrium dynamics

    Science.gov (United States)

    Drummond, L. V.; Melatos, A.

    2018-03-01

    The equilibrium configurations of neutron superfluid vortices interacting with proton superconductor flux tubes in a rotating, harmonic trap are non-trivial in general, when the magnetorotational symmetry is broken. A non-zero angle θ between the magnetic and rotation axes leads to tangled vorticity due to competition between vortex-vortex repulsion and vortex-flux-tube pinning. Here, we investigate the far-from-equilibrium behaviour of the vortices, as the trap decelerates, by solving the time-dependent, stochastic, Gross-Pitaevskii equation numerically in three dimensions. The numerical simulations reveal new vortex behaviours. Key geometrical attributes of the evolving vortex tangle are characterized, as is the degree to which pinning impedes the deceleration of the neutron condensate as a function of η, the pinning strength, and θ. The simulated system is a partial analogue of the outer core of a decelerating neutron star, albeit in a very different parameter regime.

  12. Influence of neutron flux, frequency and temperature to electrical impedance of nano silica particles

    Directory of Open Access Journals (Sweden)

    Elchin Huseynov

    2014-11-01

    Full Text Available We studied electric impedance of SiO2 nanomaterial at its initial state and after being exposed to continuous neutron irradiation for up to 20 hours. In doing so we employed a flux of neutrons of 2x1013 n⋅cm−2s−1 while the frequency and temperature ranges amounted to 0,09 – 2.3 MHz and 100 – 400 K correspondingly. Analysis in terms of the Cole-Cole expression revealed that with increasing irradiation period the polarization and relaxation times decrease as a result of combination of nanoparticles. Moreover, it is demonstrated that the electric conductivity of samples, on the other hand, increases with the increasing irradiation period. At low temperatures formations of clusters at three distinct states with different energies were resolved.

  13. Anomalous B-H behaviour of electrical steels at very low flux density

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Stan [Wolfson Centre for Magnetics, School of Engineering, Cardiff University, Cardiff CF24 3AA (United Kingdom)], E-mail: ZurekS@cardiff.ac.uk; Al-Naemi, Faris; Moses, Anthony J.; Marketos, Philip [Wolfson Centre for Magnetics, School of Engineering, Cardiff University, Cardiff CF24 3AA (United Kingdom)

    2008-10-15

    The behaviour of ferromagnetic materials under very low magnetic field was investigated more than a century ago by Lord Rayleigh. However, it has been shown since that the so-called Rayleigh law fails for very low magnetic fields, although the explanation for this phenomenon was not given. An anomalous B-H behaviour at very low alternating peak flux density in conventional grain-oriented (GO) and non-oriented (NO) electrical steels is reported. It has been found that the initial permeability is constant for all the measured frequencies (from 20 to 400 Hz) at peak flux density below 0.1 mT, and in this region the magnetisation is almost reversible (for both GO and NO). At higher flux density the B-H loops become visibly irreversible, with a relatively narrow (for GO) or very wide (for NO) transition region. For GO the B-H loop becomes visibly 'distorted' for all frequencies at around 2 mT. The eddy current loss calculated from the so-called 'classical' equation gives values higher than the measured total losses at lower frequencies. Both these measured results are difficult to explain.

  14. Anomalous B-H behaviour of electrical steels at very low flux density

    International Nuclear Information System (INIS)

    Zurek, Stan; Al-Naemi, Faris; Moses, Anthony J.; Marketos, Philip

    2008-01-01

    The behaviour of ferromagnetic materials under very low magnetic field was investigated more than a century ago by Lord Rayleigh. However, it has been shown since that the so-called Rayleigh law fails for very low magnetic fields, although the explanation for this phenomenon was not given. An anomalous B-H behaviour at very low alternating peak flux density in conventional grain-oriented (GO) and non-oriented (NO) electrical steels is reported. It has been found that the initial permeability is constant for all the measured frequencies (from 20 to 400 Hz) at peak flux density below 0.1 mT, and in this region the magnetisation is almost reversible (for both GO and NO). At higher flux density the B-H loops become visibly irreversible, with a relatively narrow (for GO) or very wide (for NO) transition region. For GO the B-H loop becomes visibly 'distorted' for all frequencies at around 2 mT. The eddy current loss calculated from the so-called 'classical' equation gives values higher than the measured total losses at lower frequencies. Both these measured results are difficult to explain

  15. Design comparison of single phase outer and inner-rotor hybrid excitation flux switching motor for hybrid electric vehicles

    Science.gov (United States)

    Mazlan, Mohamed Mubin Aizat; Sulaiman, Erwan; Husin, Zhafir Aizat; Othman, Syed Muhammad Naufal Syed; Khan, Faisal

    2015-05-01

    In hybrid excitation machines (HEMs), there are two main flux sources which are permanent magnet (PM) and field excitation coil (FEC). These HEMs have better features when compared with the interior permanent magnet synchronous machines (IPMSM) used in conventional hybrid electric vehicles (HEVs). Since all flux sources including PM, FEC and armature coils are located on the stator core, the rotor becomes a single piece structure similar with switch reluctance machine (SRM). The combined flux generated by PM and FEC established more excitation fluxes that are required to produce much higher torque of the motor. In addition, variable DC FEC can control the flux capabilities of the motor, thus the machine can be applied for high-speed motor drive system. In this paper, the comparisons of single-phase 8S-4P outer and inner rotor hybrid excitation flux switching machine (HEFSM) are presented. Initially, design procedures of the HEFSM including parts drawing, materials and conditions setting, and properties setting are explained. Flux comparisons analysis is performed to investigate the flux capabilities at various current densities. Then the flux linkages of PM with DC FEC of various DC FEC current densities are examined. Finally torque performances are analyzed at various armature and FEC current densities for both designs. As a result, the outer-rotor HEFSM has higher flux linkage of PM with DC FEC and higher average torque of approximately 10% when compared with inner-rotor HEFSM.

  16. A New Energy-Based Method for 3-D Finite-Element Nonlinear Flux Linkage computation of Electrical Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

    2011-01-01

    This paper presents a new method for computation of the nonlinear flux linkage in 3-D finite-element models (FEMs) of electrical machines. Accurate computation of the nonlinear flux linkage in 3-D FEM is not an easy task. Compared to the existing energy-perturbation method, the new technique......-perturbation method. The new method proposed is validated using experimental results on two different permanent magnet machines....

  17. Large-scale management of electric grids - Power flux control in an electric network; Gestion des reseaux electriques a grande echelle. Controle des flux de puissance d'un reseau electrique

    Energy Technology Data Exchange (ETDEWEB)

    Lalou, M. J. [EIA-FR, Fribourg (Switzerland); Affolter, J.-F. [HEIG-VD, Yverdon-les-Bains (Switzerland)

    2010-07-01

    Security of supply in electricity networks is a major industrial challenge for the future. It involves power generation, transmission and distribution altogether. Networks gradually approach saturation. This article presents an optimal real-time management method of power flux in an electricity network equipped with FACTS and phase measuring devices. FACTS have to be gradually introduced, however not earlier than in 10 years time, as the reliability of data transmission for their control is currently not high enough, considering the order of magnitude of the involved electric power.

  18. Control of adverse effects of explosive blasting in mines by using shock tube (non-electric) initiation systems and its future challenges

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, P.D. [Maharashtra Explosives Ltd., Nagpur (India)

    2000-04-01

    Every kind of blasting in mines produces some adverse effects on environment, such as ground vibration, noise, fly rock etc. Presently, for restricting these adverse effects, use of shock tube (non-electric) initiation systems are gaining momentum. There are some inherent shortcomings of this initiation system regarding chances of misfires. This paper discusses the various adverse effects of blasting, advantages of shock tube initiation system and the shortcomings of shock tube initiation system regarding chances of misfire and how misfire arises out of failure of shock tube initiation system is different and more dangerous than the misfire occurring due to failure of conventional system (with detonating fuse and cord relays). 1 tab.

  19. Combination of helical ferritic-steel inserts and flux-tube-expansion divertor for the heat control in tokamak DEMO reactor

    International Nuclear Information System (INIS)

    Takizuka, T.; Tokunaga, S.; Hoshino, K.; Shimizu, K.; Asakura, N.

    2015-01-01

    Edge localized modes (ELMs) in the H-mode operation of tokamak reactors may be suppressed/mitigated by the resonant magnetic perturbation (RMP), but RMP coils are considered incompatible with DEMO reactors under the strong neutron flux. We propose an innovative concept of the RMP without installing coils but inserting ferritic steels of the helical configuration. Helically perturbed field is naturally formed in the axisymmetric toroidal field through the helical ferritic steel inserts (FSIs). When ELMs are avoided, large stationary heat load on divertor plates can be reduced by adopting a flux-tube-expansion (FTE) divertor like an X divertor. Separatrix shape and divertor-plate inclination are similar to those of a simple long-leg divertor configuration. Combination of the helical FSIs and the FTE divertor is a suitable method for the heat control to avoid transient ELM heat pulse and to reduce stationary divertor heat load in a tokamak DEMO reactor

  20. Effect of the surface film electric resistance on eddy current detectability of surface cracks in Alloy 600 tubes

    International Nuclear Information System (INIS)

    Saario, T.; Paine, J.P.N.

    1995-01-01

    The most widely used technique for NDE of steam generator tubing is eddy current. This technique can reliably detect cracks grown in sodium hydroxide environment only at depths greater than 50% through wall. However, cracking caused by thiosulphate solutions have been detected and sized at shallower depths. The disparity has been proposed to be caused by the different electric resistance of the crack wall surface films and corrosion products in the cracks formed in different environments. This work was undertaken to clarify the role of surface film electric resistance on the disparity found in eddy current detectability of surface cracks in alloy 600 tubes. The proposed model explaining the above mentioned disparity is the following. The detectability of tightly closed cracks by the eddy current technique depends on the electric resistance of the surface films of the crack walls. The nature and resistance of the films which form on the crack walls during operation depends on the composition of the solution inside the crack and close to the crack location. During cooling down of the steam generator, because of contraction and loss of internal pressurization, the cracks are rather tightly closed so that exchange of electrolyte and thus changes in the film properties become difficult. As a result, the surface condition prevailing at high temperature is preserved. If the environment is such that the films formed on the crack walls under operating conditions have low electric resistance, eddy current technique will fail to indicate these cracks or will underestimate the size of these cracks. However, if the electric resistance of the films is high, a tightly closed crack will resemble an open crack and will be easily indicated and correctly sized by eddy current technique

  1. Frequency spectra from current vs. magnetic flux density measurements for mobile phones and other electrical appliances.

    Science.gov (United States)

    Straume, Aksel; Johnsson, Anders; Oftedal, Gunnhild; Wilén, Jonna

    2007-10-01

    The frequency spectra of electromagnetic fields have to be determined to evaluate human exposure in accordance to ICNIRP guidelines. In the literature, comparisons with magnetic field guidelines have been performed by using the frequency distribution of the current drawn from the battery. In the present study we compared the frequency spectrum in the range 217 Hz to 2.4 kHz of the magnetic flux density measured near the surface of a mobile phone with the frequency spectrum of the supply current. By using the multiple frequency rule, recommended in the ICNIRP guidelines, we estimated the magnetic field exposure in the two cases. Similar measurements and estimations were done for an electric drill, a hair dryer, and a fluorescent desk lamp. All the devices have a basic frequency of 50 Hz, and the frequency spectra were evaluated up to 550 Hz. We also mapped the magnetic field in 3D around three mobile phones. The frequency distributions obtained from the two measurement methods are not equal. The frequency content of the current leads to an overestimation of the magnetic field exposure by a factor up to 2.2 for the mobile phone. For the drill, the hair dryer, and the fluorescent lamp, the supply current signal underestimated the exposure by a factor up to 2.3. In conclusion, an accurate exposure evaluation requires the magnetic flux density spectrum of the device to be measured directly. There was no indication that the devices studied would exceed the reference levels at the working distances normally used.

  2. On-line mechanical tube cleaning for steam electric power plants. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-18

    In July 1991, Superior I.D. Tube Cleaners, Inc. (SIDTEC{trademark}) received a grant through the Department of Energy and the Energy Related Invention Program to conduct a long term demonstration of a proprietary technology for on-line mechanical condenser tube cleaning in thermal Power plants on open or once-through cooling water systems where the warmed condenser cooling water is discharged through a canal. The purpose of the demonstration was to confirm and establish the use of this mechanical method as an alternative to the application of chemical biocides in condenser cooling water for the control of biofouling, the growth of micro-organisms which can reduce a unit`s operating efficiency. The SIDTEC on-line mechanical tube cleaner, the Rocket{trademark}, is used to physically remove accumulated deposits on the water side of the main steam condenser, and the non-intrusive tube cleaner recovery system, the Skimmer{trademark}, is used to recover and recirculate tube cleaners. The periodic circulation of tube cleaners can maintain optimum condenser cleanliness and improve unit heat rate. Thermal power plants which discharge condenser cooling water through a canal now have a viable alternative to the chemical treatment of condenser cooling water, whether the principal foulant is biofouling, chemical scaling, silting, or a combination of the three. At prices competitive with scale inhibitors, and a fraction of competing mechanical systems, this technology is provided as a service requiring no capital investment; minimal retrofit modifications to plant structures or equipment; can be installed and maintained without a unit shutdown; does not add any restrictions in the cooling water system; and is environmentally benign.

  3. Gradient-driven flux-tube simulations of ion temperature gradient turbulence close to the non-linear threshold

    Energy Technology Data Exchange (ETDEWEB)

    Peeters, A. G.; Rath, F.; Buchholz, R.; Grosshauser, S. R.; Strintzi, D.; Weikl, A. [Physics Department, University of Bayreuth, Universitätsstrasse 30, Bayreuth (Germany); Camenen, Y. [Aix Marseille Univ, CNRS, PIIM, UMR 7345, Marseille (France); Candy, J. [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Casson, F. J. [CCFE, Culham Science Centre, Abingdon OX14 3DB, Oxon (United Kingdom); Hornsby, W. A. [Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2 85748 Garching (Germany)

    2016-08-15

    It is shown that Ion Temperature Gradient turbulence close to the threshold exhibits a long time behaviour, with smaller heat fluxes at later times. This reduction is connected with the slow growth of long wave length zonal flows, and consequently, the numerical dissipation on these flows must be sufficiently small. Close to the nonlinear threshold for turbulence generation, a relatively small dissipation can maintain a turbulent state with a sizeable heat flux, through the damping of the zonal flow. Lowering the dissipation causes the turbulence, for temperature gradients close to the threshold, to be subdued. The heat flux then does not go smoothly to zero when the threshold is approached from above. Rather, a finite minimum heat flux is obtained below which no fully developed turbulent state exists. The threshold value of the temperature gradient length at which this finite heat flux is obtained is up to 30% larger compared with the threshold value obtained by extrapolating the heat flux to zero, and the cyclone base case is found to be nonlinearly stable. Transport is subdued when a fully developed staircase structure in the E × B shearing rate forms. Just above the threshold, an incomplete staircase develops, and transport is mediated by avalanche structures which propagate through the marginally stable regions.

  4. Propagation of Torsional Alfvén Waves from the Photosphere to the Corona: Reflection, Transmission, and Heating in Expanding Flux Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume; Oliver, Ramón; Ballester, José Luis, E-mail: roberto.soler@uib.es [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2017-05-01

    It has been proposed that Alfvén waves play an important role in the energy propagation through the solar atmospheric plasma and its heating. Here we theoretically investigate the propagation of torsional Alfvén waves in magnetic flux tubes expanding from the photosphere up to the low corona and explore the reflection, transmission, and dissipation of wave energy. We use a realistic variation of the plasma properties and the magnetic field strength with height. Dissipation by ion–neutral collisions in the chromosphere is included using a multifluid partially ionized plasma model. Considering the stationary state, we assume that the waves are driven below the photosphere and propagate to the corona, while they are partially reflected and damped in the chromosphere and transition region. The results reveal the existence of three different propagation regimes depending on the wave frequency: low frequencies are reflected back to the photosphere, intermediate frequencies are transmitted to the corona, and high frequencies are completely damped in the chromosphere. The frequency of maximum transmissivity depends on the magnetic field expansion rate and the atmospheric model, but is typically in the range of 0.04–0.3 Hz. Magnetic field expansion favors the transmission of waves to the corona and lowers the reflectivity of the chromosphere and transition region compared to the case with a straight field. As a consequence, the chromospheric heating due to ion–neutral dissipation systematically decreases when the expansion rate of the magnetic flux tube increases.

  5. AN EXPERIMENTAL STUDY FOR HEAT TRANSFER ENHANCEMENT BY LAMINAR FORCED CONVECTION FROM HORIZONTAL AND INCLINED TUBE HEATED WITH CONSTANT HEAT FLUX, USING TWO TYPES OF POROUS MEDIA

    Directory of Open Access Journals (Sweden)

    Thamir K. Jassem

    2015-02-01

    Full Text Available An experimental forced laminar study was presented in this research for an air flowing through a circular channel for different angles ( ,30o,45o,60o, the channel was heated at constant heat flux , the channel also was packed with steel and glass spheres respectively . The tests were done for three values of Peclets number (2111.71,3945.42,4575.47 with changing the heat flux for each case and five times for each number.The results showed that the dimensionless temperature distribution  will decrease with increasing the dimensionless channel length for all cases with changing Peclet number, heat flux and inclination angles, and its lowest value will be for glass spheres at highest flux, while at lower flux for , and the decreasing in dimensionless temperature was closed for both types of packed at other inclination angles.The study declared that the local Nusselt number decreases with increasing the dimensionless length of the channel for both packeds and for different applied heat flux, also through this study it was declared that the average Nusselt increases as Peclet number increases for both packed. Its value for the glass spheres is greater than the steel spheres with percentage (98.3% at small Peclet, and percentage (97.2% at large Peclet number for the horizontal tube, and (98.3% at small Peclet number and (97.8% at large Peclet number at  .Through this study its was found that average Nusselt number increases along the channel as the heat flux increases, because the bulk temperature will increase as the flow proceeds toward the end of the channel , so the heat transfer coefficient will increase.  It was declared from this study that in the case of the steel packed the heat transfer will occur mainly by conduction, while in the case of glass packed the heat transfer will occur mainly by laminar forced convection, where the lowest Nusselt number (Nu=3.8 was found when the pipe is horizontal and lowest heat flux and lowest Peclet number.  

  6. Calorimeter probes for measuring high thermal flux. [in electric-arc jet facilities for planetary entry heating simulation

    Science.gov (United States)

    Russell, L. D.

    1979-01-01

    The paper describes expendable, slug-type calorimeter probes developed for measuring high heat-flux levels of 10-30 kW/sq cm in electric-arc jet facilities. The probes are constructed with thin tungsten caps mounted on Teflon bodies; the temperature of the back surface of the tungsten cap is measured, and its rate of change gives the steady-state, absorbed heat flux as the calorimeter probe heats to destruction when inserted into the arc jet. It is concluded that the simple construction of these probes allows them to be expendable and heated to destruction to obtain a measurable temperature slope at high heating rates.

  7. The Funnel Geometry of Open Flux Tubes in the Low Solar Corona Constrained by O VI and Ne VIII Outflow

    Science.gov (United States)

    Byhring, Hanne S.; Esser, Ruth; Lie-Svendsen, Oystein

    2008-01-01

    Model calculations show that observed outflow velocities of order 7-10 km/s of C IV and O VI ions, and 15-20 km/s of Ne VIII ions, are not only consistent with models of the solar wind from coronas holes, but also place unique constraints on the degree of flow tube expansion as well as the location of the expansion in the transition region/lower corona.

  8. The Role of the Velocity Gradient in Laminar Convective Heat Transfer through a Tube with a Uniform Wall Heat Flux

    Science.gov (United States)

    Wang, Liang-Bi; Zhang, Qiang; Li, Xiao-Xia

    2009-01-01

    This paper aims to contribute to a better understanding of convective heat transfer. For this purpose, the reason why thermal diffusivity should be placed before the Laplacian operator of the heat flux, and the role of the velocity gradient in convective heat transfer are analysed. The background to these analyses is that, when the energy…

  9. Study on divertor particle and heat fluxes from electric probe measurements during ELMy H-modes in KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Bak, Jun-Gyo, E-mail: jgbak@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, Heung-Su [National Fusion Research Institute, Daejeon (Korea, Republic of); Bae, Min-Keun; Chung, Kyu-Sun [Hanyang University, Seoul (Korea, Republic of); Hong, Suk-Ho [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    Highlights: • The characteristics of the particle and heat fluxes were investigated during ELMs in H-modes under the LSN configuration in the KSTAR tokamak.. • There was relation between the ELM amplitude and the ELM frequency as ΔW{sub ELM}/W{sub TOT} ∝ 1/f{sub ELM} in the range of f{sub ELM} ≤ 200 Hz. • The trends of the peak amplitude of the divertor flux near the OSP during ELMs due to the ELM mitigation and the plasma shaping were investigated. • The ELMs were mitigated by MP field, SMBI and ECH. The ELM mitigations due to the MP field and the SMBI were stronger than one due to the ECH. • Finally, the particle flux, evaluated at the far scrape-off layer (SOL) region, was estimated to less than 1% of the divertor particle flux. - Abstract: The characteristics of the divertor particle and heat fluxes are investigated during ELM bursts in ELMy H-mode plasmas with the lower single null (LSN) configuration in Korea Superconducting Tokamak Advanced Research (KSTAR). The particle and heat fluxes are evaluated from the electric probe measurements at the divertor region. It is found that the peak amplitude of the divertor flux during an ELM burst obtained near the outer strike point (OSP) decreases up to about 20% as the ELM frequency increases by a factor of ∼6.5 due to the ELM mitigation and the plasma shaping, which is similar to the trend of the amplitude versus the frequency of the ELM observed in other tokamaks. The ELMs are mitigated by using several methods as magnetic perturbation (MP) field, supersonic molecular beam injection (SMBI) and electron cyclotron heating (ECH) at the edge region. In addition, the particle flux, evaluated at the far scrape-off layer (SOL) region, is less than 1% of the divertor particle flux. In this work, results from the experimental investigations of particle and heat fluxes during ELM bursts from the electric probe measurements at the divertor and far SOL regions are presented.

  10. Event-by-event mean {p}_{{\\rm{T}}} fluctuations and transverse size of color flux tube generated in p-p collisions at \\sqrt{s} = 0.90 TeV

    Science.gov (United States)

    Osada, Takeshi; Ishihara, Masamichi

    2018-01-01

    We propose a novel phenomenological model of mean transverse momentum fluctuations based on the geometrical scaling hypothesis. Bose-Einstein correlations between two gluons generated from an identical color flux tube are taken into account as a source of the fluctuation. We calculate an event-by-event fluctuation measure \\sqrt{{C}m}/ and show that ALICE data observed at \\sqrt{s}=0.90 TeV for p+p collisions are reproduced. By fitting our model to the experimental data, we evaluate the transverse size of the color flux tube as a function of the multiplicity.

  11. Macromixing hydrodynamic study in draft-tube airlift reactors using electrical resistance tomography.

    Science.gov (United States)

    Gumery, Farouza; Ein-Mozaffari, Farhad; Dahman, Yaser

    2011-02-01

    The present study summarizes results of mixing characteristics in a draft tube airlift bioreactor using ERT. This technique offers the possibility for noninvasive and nonintrusive visualization of flow fields in the bioreactor and has rarely been utilized previously to analyze operating parameters and mixing characteristics in this type of bioreactors. Several operating parameters and geometric characteristics were examined. In general, results showed that the increase in superficial gas velocity corresponds to an increase in energy applied and thus, to a decrease in mixing time. This generally corresponded to an increase in liquid circulation velocity and shear rate values. Bottom clearances and draft tube diameters affected flow resistance and frictional losses. The influence of sparger configurations on mixing time and liquid circulation velocity was significant due to their effect on gas distribution. However, the effect of sparger configuration on shear rate was not significant, with 20% reduction in shear rates using the cross-shaped sparger. Fluid viscosity showed a marked influence on both mixing times and circulation velocity especially in the coalescing media of sugar and xanthan gum (XG) solutions. Results from this work will help to develop a clear pattern for operation and mixing that can help to improve several industrial processes, especially the ones related to emerging fields of technology such as the biotechnology industry.

  12. The kink instability in infinite cylindrical flux tubes - Eigenvalues for power-law twist profiles. [in stellar atmospheres

    Science.gov (United States)

    Craig, I. J. D.; Robb, T. D.; Sneyd, A. D.; Mcclymont, A. N.

    1990-01-01

    Simple, accurate methods of calculating ideal MHD instability eigenvalues for infinitely long cylindrical tubes with twist function T(r) are developed. The results show that the most rapidly growing and energetic instabilities occur in the Gold-Hoyle v = 0 field, with the instability progressively weakening with increasing v. However, the maximum force eigenvalue is always small, so that even in the Gold-Hoyle case only a small proportion of the available magnetic energy can be released in the linear phase. The results also confirm that the linear pinch is remarkably weak yet relatively resistant to line-tying. It is shown that the weakness of the force eigenvalue implies that the influence of uniform gas pressure on stability is negligible. Implications for the energy-release mechanism in solar flares are discussed.

  13. Comparative study of water boiling in a vertical tube under temperature-controlled or heat-flux-controlled boundary conditions

    International Nuclear Information System (INIS)

    Carbajo, J.J.

    1983-03-01

    The Simulant Boiling Flow Visualization (SBFV) loop is an experimental facility where natural-convection boiling of water was accomplished in a transparent vertical tube by using hot glycerine; thus, direct observation was possible. As a result, heating was obtained through a temperature-controlled rather than a power-controlled boundary condition. To compare the SBFV data with previous experiments using a stainless steel test section and a power-controlled boundary condition, a comparative study of the effect on water boiling with the two different boundary conditions was performed. The computer program LOOP-W was used for this purpose. This program has been used successfully in analyzing data from the SBFV, and it was modified so that analogous cases could be run with the two different boundary conditions

  14. High-Energy X-Ray Detection of G359.89-0.08 (SGR A-E): Magnetic Flux Tube Emission Powered by Cosmic Rays?

    Science.gov (United States)

    Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; hide

    2014-01-01

    We report the first detection of high-energy X-ray (E (is) greater than 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to approximately 50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index gamma approximately equals 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is F(sub X) = (2.0 +/- 0.1) × 10(exp -12)erg cm(-2) s(-1) , corresponding to an unabsorbed X-ray luminosity L(sub X) = (2.6+/-0.8)×10(exp 34) erg s(-1) assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A-E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to (is) approximately 100 kyr) with low surface brightness and radii up to (is) approximately 30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.

  15. Do Membranes Dream of Electric Tubes? Advanced Membranes Using Carbon Nanotube - Polymer Nanocomposites

    Science.gov (United States)

    de Lannoy, Charles-Francois Pedro Claude Karolek Ghislain

    Membrane technologies represent an energy efficient, effective solution for treating municipal and commercial waters/wastewaters. Membranes are predominantly polymer-based and despite steady advances in polymeric materials, they continue to suffer from operational problems including biofouling and breakages. This work addresses these two disparate problems by developing novel CNT-polymer nanocomposite materials that contain variously functionalized carbon nanotubes (fCNTs) in low quantities (phase and linked through ionic associations in polymer matrices showed significant (50%) increases in Young's modulus for certain CNT functionalizations and derivatization percent. Membranes formed with high surface electrical conductivity demonstrated almost complete resistance to biofouling (> 95%) in long-term bacterially challenged experiments. CNTs and polymer mixtures that lacked covalent or ionic bonds were susceptible to significant (up to 10%) loss of CNTs during membrane non-solvent gelation and aggressive chemical cleaning treatment. Functionalized carbon nanotubes endow polymer membranes with their unique strength and electrically conductive properties. These added properties were demonstrated to greatly improve membrane operational efficiency and membrane longevity. CNT-polymer nanocomposite membranes offer low-energy, high-efficiency, and long-lifetime alternatives to traditional polymer membranes. With further advances in polymeric nanomaterials, membrane technology has the potential for wide applicability across many fields outside of water filtration and desalination.

  16. Facile Fabrication of Electrically Conductive Low-Density Polyethylene/Carbon Fiber Tubes for Novel Smart Materials via Multiaxial Orientation.

    Science.gov (United States)

    Li, Yijun; Nie, Min; Wang, Qi

    2018-01-10

    Electromechanical sensors are indispensable components in functional devices and robotics application. However, the fabrication of the sensors still maintains a challenging issue that high percolation threshold and easy failure of conductive network are derived from uniaxial orientation of conductive fillers in practical melt processing. Herein, we reported a facile fabrication method to prepare a multiaxial low-density polyethylene (LDPE)/carbon fibers (CFs) tube with bidirectional controllable electrical conductivity and sensitive strain-responsive performance via rotation extrusion technology. The multidimensional helical flow is confirmed in the reverse rotation extrusion, and the CFs readily respond to the flow field leading to a multiaxial orientation in the LDPE matrix. In contrast to uniaxial LDPE/CF composites, which perform a "head to head" conjunction, multiaxial-orientated CF networks exhibit a unique multilayer structure in which the CFs with distinct orientation direction intersect in the interface, endowing the LDPE/CF composites with a low percolation threshold (15 wt %) to those of the uniaxial ones (∼35 wt %). The angles between two axes play a vital role in determining the density of the conductive networks in the interface, which is predominant in tuning the bending-responsive behaviors with a gauge factor range from 12.5 to 56.3 and the corresponding linear respond region from ∼15 to ∼1%. Such a superior performance of conductive LDPE/CF tube confirms that the design of multiaxial orientation paves a novel way to facile fabrication of advanced cost-effective CF-based smart materials, shedding light on promising applications such as smart materials and intelligent engineering monitoring.

  17. Investigation of SOL parameters and divertor particle flux from electric probe measurements in KSTAR

    International Nuclear Information System (INIS)

    Bak, J.G.; Kim, H.S.; Bae, M.K.; Juhn, J.W.; Seo, D.C.; Bang, E.N.; Shim, S.B.; Chung, K.S.; Lee, H.J.; Hong, S.H.

    2015-01-01

    The upstream scrape-off layer (SOL) profiles and downstream particle fluxes are measured with a fast reciprocating Langmuir probe assembly (FRLPA) at the outboard mid-plane and a fixed edge Langmuir probe array (ELPA) at divertor region, respectively in the KSTAR. It is found that the SOL has a two-layer structure in the outboard wall-limited (OWL) ohmic and L-mode: a near SOL (∼5 mm zone) with a narrow feature and a far SOL with a broader profile. The near SOL width evaluated from the SOL profiles in the OWL plasmas is comparable to the scaling for the L-mode divertor plasmas in the JET and AUG. In the SOL profiles and the divertor particle flux profile during the ELMy H-modes, the characteristic e-folding lengths of electron temperature, plasma density and particle flux during an ELM phase are about two times larger than ones at the inter ELM

  18. Phase diagrams and radial distribution of the electric field components of coaxial discharges with outer dielectric tube at different wave modes

    International Nuclear Information System (INIS)

    Neichev, Z; Benova, E; Gamero, A; Sola, A

    2007-01-01

    The purpose of this work is to investigate phase diagrams and electric field radial distribution of coaxial discharges, sustained by a traveling electromagnetic wave, assuming finite and infinite thickness of the discharge chamber in the model. The calculations are made for azimuthally symmetric and dipolar wave modes. The phase diagrams and the radial profiles of the electric field at various thicknesses of the outer dielectric tube of the chamber and different discharge conditions are obtained. For the purpose of low pressure coaxial plasma modelling, radial profiles of the electric field at different discharge conditions have been investigated experimentally and compared with the theoretical results

  19. Heating and reconnection of the emerging magnetic flux-tubes and the role of the interchange instability

    International Nuclear Information System (INIS)

    Uchida, Y.; Sakurai, T.

    1977-01-01

    In this paper it is proposed that the basic behaviors of newly-emerged magnetic regions (NEMR) as seen in EUV and soft X-rays from space are interpreted by the interchange instability of the magnetic field of NEMR in the global situation surrounding it. It is shown that the situation with the NEMR is unstable against the interchange instability, and a continual relaxation to the lower energy state, or a continual invasion of the magnetic flux of the NEMR to the ambient region in the form of fine bundles or thin sheets, will take place in a short time scale of tau 1 approximately L/Vsub(A) following the change in the boundary condition at the photosphere. The second and the final relaxation is shown to be the enhanced Joule dissipation in a time scale of hours to several days occurring in the thin current sheets on the interface of this intermingled structure which is distributed in a large volume. This hypothesis may provide an explanation for the heating of NEMR to an X-ray emitting temperature, which is otherwise rather difficult to explain. The observed fast reconnection without appreciable flares (except for some smaller brightenings) is another aspect which can be explained in the present hypothesis. Namely, since the situation with the NEMR is unstable for the interchange from the beginning, the stressed configuration is relaxed before storing appreciable energy in the form of magnetic stress and therefore without a drastic release of a large amount of stored stress energy in the form of a flare. (Auth.)

  20. Electrical Transport Properties of Single-Crystalline β-Zn4Sb3 Prepared Through the Zn-Sn Mixed-Flux Method

    Science.gov (United States)

    Liu, Hongxia; Deng, Shuping; Shen, Lanxian; Wang, Jinsong; Feng, Cheng; Deng, Shukang

    2017-03-01

    β-Zn4Sb3 is a promising p-type thermoelectric material for utilization in moderate temperatures. This study prepares a group of single-crystalline β-Zn4Sb3 samples using the Zn-Sn mixed-flux method based on the stoichiometric ratios of Zn4+ x Sb3Sn y . The effect of Zn-to-Sn proportion in the flux on the structure and electrical transport properties is investigated. All samples are strip-shaped single crystals of different sizes. The actual Zn content of the present samples is improved (>3.9) compared with that of the samples prepared through the Sn flux method. Larger lattice parameters are also obtained. The carrier concentration of all the samples is in the order of over 1019 cm-3. With increasing Sn rate in the flux, this carrier concentration decreases, whereas mobility is significantly enhanced. The electrical conductivity and Seebeck coefficients of all the samples exhibit a behavior that of a degenerate semiconductor transport. Electrical conductivity initially increases and then decreases as the Sn ratio in the flux increases. The electrical conductivity of the x: y = 5:1 sample reaches 6.45 × 104 S m-1 at 300 K. Benefitting from the electrical conductivity and Seebeck coefficient, the flux proportion of the x: y = 7:1 sample finally achieves the highest power factor value of 1.4 × 10-3 W m-1 K-2 at 598 K.

  1. Comparison between measured and computed magnetic flux density distribution of simulated transformer core joints assembled from grain-oriented and non-oriented electrical steel

    Science.gov (United States)

    Shahrouzi, Hamid; Moses, Anthony J.; Anderson, Philip I.; Li, Guobao; Hu, Zhuochao

    2018-04-01

    The flux distribution in an overlapped linear joint constructed in the central region of an Epstein Square was studied experimentally and results compared with those obtained using a computational magnetic field solver. High permeability grain-oriented (GO) and low permeability non-oriented (NO) electrical steels were compared at a nominal core flux density of 1.60 T at 50 Hz. It was found that the experimental results only agreed well at flux densities at which the reluctance of different paths of the flux are similar. Also it was revealed that the flux becomes more uniform when the working point of the electrical steel is close to the knee point of the B-H curve of the steel.

  2. Design study and performance analysis of 12S-14P field excitation flux switching motor for hybrid electric vehicle

    Science.gov (United States)

    Husin, Zhafir Aizat; Sulaiman, Erwan; Khan, Faisal; Mazlan, Mohamed Mubin Aizat; Othman, Syed Muhammad Naufal Syed

    2015-05-01

    This paper presents a new structure of 12slot-14pole field excitation flux switching motor (FEFSM) as an alternative candidate of non-Permanent Magnet (PM) machine for HEV drives. Design study, performance analysis and optimization of field excitation flux switching machine with non-rare-earth magnet for hybrid electric vehicle drive applications is done. The stator of projected machine consists of iron core made of electromagnetic steels, armature coils and field excitation coils as the only field mmf source. The rotor is consisted of only stack of iron and hence, it is reliable and appropriate for high speed operation. The design target is a machine with the maximum torque, power and power density, more than 210Nm, 123kW and 3.5kW/kg, respectively, which competes with interior permanent magnet synchronous machine used in existing hybrid electric vehicle. Some design feasibility studies on FEFSM based on 2D-FEA and deterministic optimization method will be applied to design the proposed machine.

  3. Electrical properties and flux performance of composite ceramic hydrogen separation membranes

    DEFF Research Database (Denmark)

    Fish, J.S.; Ricote, Sandrine; O'Hayre, R.

    2015-01-01

    with an effective medium approach incorporating a term for the heterojunctions between the two phases. Hydrogen fluxes of 0.004-0.008 μmol cm-2 s-1 are obtained for a 50 volume% STN95 membrane sample (1 mm thickness) at 600-800 °C using dry argon as a sweep gas. Upon adding palladium layers as catalysts more than...... conductivities of 0.01-0.06 S cm-1 are obtained in moist (+1% H2O) H2/inert gas from 600-800 °C for 50 volume% STN95. With increasing STN95 content (60 and 70 volume%), conductivity increases by 5-10 times, but displays a semiconductor-type dependence, even at 70 volume% STN95. The conductivity is modeled...... a five-fold increase is observed in the hydrogen flux, 0.025-0.026 μmol cm-2 s-1, over the same temperature range. Hydrogen flux is not observed for membranes made from the 60 and 70% STN95 samples....

  4. Time Lapse Electrical Resistivity to Connect Evapotranspiration and Groundwater Fluxes in the Critical Zone

    Science.gov (United States)

    Jarvis, S. K.; Harmon, R. E.; Barnard, H. R.; Randall, J.; Singha, K.

    2017-12-01

    The critical zone (CZ)—an open system extending from canopy top to the base of groundwater—is a highly dynamic and heterogeneous environment. In forested terrain, trees make up a large component of the CZ. This work aims to quantify the connection between vegetation and subsurface water storage at a hillslope scale within a forested watershed in the H.J. Andrews Experimental Forest, Oregon. To identify the mechanism(s) controlling the connection at the hillslope scale, we observe patterns in electrical conductivity using 2D-time lapse-DC resistivity. To compare inversions through time a representative error model was determined using L-curve criterion. Inverted data show high spatial variability in ground electrical conductivity and variation at both diel and seasonal timescales. These changes are most pronounced in areas corresponding to dense vegetation. The diel pattern in electrical conductivity is also observed in monitored sap flow sensors, water-level gauges, tensiometers, and sediment thermal probes. To quantify the temporal connection between these data over the course of the growing season a cross correlation analysis was conducted. Preliminary data show that over the course of the growing season transpiration becomes decoupled from both groundwater and soil moisture. Further decomposition of the inverted time lapse data will highlight spatial variability in electrical conductivity providing insight into the where, when, and how(s) of tree-modified subsurface storage.

  5. Experimental and numerical determination of temperature gradients for a single tube alkali metal thermal-to-electric converter cell

    Science.gov (United States)

    Wright, S.

    2001-01-01

    This paper presents the results from the experimental and numerical determination of shell temperature gradients for a single tube AMTEC cell evaluated under simulated deep space operating conditions.

  6. Electric-gun studies of conductors in high magnetic fields and experiments in dynamic flux compression

    Science.gov (United States)

    Osher, J. E.; Chau, H. H.; Lee, R. S.; Tipton, R. E.; Weingart, R. C.

    1989-07-01

    The devices we call electric guns operate by discharging a fast capacitor bank through a thin, metallic bridge-foil load. The explosion of the foil and the accompanying magnetic forces acting on the bridge-foil plasma accelerate a thin flyer plate of dielectric material initially placed on top of the bridge foil. In hypervelocity impact studies with the linear electric gun, a thin, flat flyer is punched out of a cover sheet of dielectric (or dielectric/metallic composite) material by the explosion of the bridge foil and accelerated down a short barrel to impact on a target. In the coaxial gun, a cylindrical bridge foil is used to implode a cylindrical dielectric or dielectric/metallic composite (liner) flyer to produce a high peak compression through axial convergence. In this paper we discuss the range of currents, their rate of rise, and the magnetic fields attained by our fast capacitor banks, which supply power to the electric gun to explode the bridge foil. Also included is a brief study of the change of resistance of the bridge-foil element as a function of time for various flyer mass loadings for the linear geometry of the gun. The change in resistance can be viewed as a type of opening switch for pulsed-power applications.

  7. An utilization of liquid sublayer dryout mechanism in predicting critical heat flux under low pressure and low velocity conditions in round tubes

    International Nuclear Information System (INIS)

    Lee, Kwang-Won; Baik, Se-Jin; Ro, Tae-Sun

    2000-01-01

    From a theoretical assessment of extensive critical heat flux (CHF) data under low pressure and low velocity (LPLV) conditions, it was found out that lots of CHF data would not be well predicted by a normal annular film dryout (AFD) mechanism, although their flow patterns were identified as annular-mist flow. To predict these CHF data, a liquid sublayer dryout (LSD) mechanism has been newly utilized in developing the mechanistic CHF model based on each identified CHF mechanism. This mechanism postulates that the CHF occurrence is caused by dryout of the thin liquid sublayer resulting from the annular film separation or breaking down due to nucleate boiling in annular film or hydrodynamic fluctuation. In principle, this mechanism well supports the experimental evidence of residual film flow rate at the CHF location, which can not be explained by the AFD mechanism. For a comparative assessment of each mechanism, the CHF model based on the LSD mechanism is developed together with that based on the AFD mechanism. The validation of these models is performed on the 1406 CHF data points ranging over P=0.1-2 MPa, G=4-499 kg m -2 s -1 , L/D=4-402. This model validation shows that 1055 and 231 CHF data are predicted within ±30 error bound by the LSD mechanism and the AFD mechanism, respectively. However, some CHF data whose critical qualities are <0.4 or whose tube length-to-diameter ratios are <70 are considerably overestimated by the CHF model based on the LSD mechanism. These overestimations seem to be caused by an inadequate CHF mechanism classification and an insufficient consideration of the flow instability effect on CHF. Further studies for a new classification criterion screening the CHF data affected by flow instabilities as well as a new bubble detachment model for LPLV conditions, are needed to improve the model accuracy.

  8. Copper ion fluxes through the floating water bridge under strong electric potential.

    Science.gov (United States)

    Giuliani, Livio; D'Emilia, Enrico; Lisi, Antonella; Grimaldi, Settimio; Brizhik, Larissa; Del Giudice, Emilio

    2015-01-01

    We have performed a series of experiments applying high voltage between two electrodes, immersed in two beakers containing bidistilled water in a way similar to experiments conducted by Fuchs and collaborators, which showed that a water bridge can be formed between the two containers. We also observed the formation of water bridge. Moreover, choosing different pairs of electrodes depending on the material they are made up of, we observed that copper ions flow can pass along the bridge if the negative electrode is made up of copper. We show that the direction of the flux not only depends on the applied electrostatic field but on the relative electronegativity of the electrodes too. These results open new perspectives in understanding the properties of water. We suggest a possible explanation of the obtained results.

  9. Influence of Different Rotor Teeth Shapes on the Performance of Flux Switching Permanent Magnet Machines Used for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Jing Zhao

    2014-12-01

    Full Text Available This paper investigated a 12-slot/11-pole flux switching permanent magnet (FSPM machine used for electric vehicles (EVs. Five novel rotor teeth shapes are proposed and researched to reduce the cogging torque and torque ripple of the FSPM machine. These rotor teeth shapes are notched teeth, stepped teeth, eccentric teeth, combination of notched and stepped teeth, and combination of notched and eccentric teeth. They are applied on the rotor and optimized, respectively. The influences of different rotor teeth shapes on cogging torque, torque ripple and electromagnetic torque are analyzed by the 2-D finite-element method (FEM. Then, the performance of FSPMs with different rotor teeth shapes are compared and evaluated comprehensively from the points of view of cogging torque, torque ripple, electromagnetic torque, flux linkage, back electromotive force (EMF, and so on. The results show that the presented rotor teeth shapes, especially the combination of stepped and notched teeth, can greatly reduce the cogging torque and torque ripple with only slight changes in the average electromagnetic torque.

  10. The Control of Fluxes of Electric Power in Networks by Means of Phase-switching Booster Transformers

    Directory of Open Access Journals (Sweden)

    Govorov F.P.

    2016-12-01

    Full Text Available roblems of increasing the efficiency of the operation of electrical networks based on the utilization of booster transformers (BT with electronic control, applied on the base of active elements in smart electric grids of power systems and giving the function of automatic correction of the parameters of the network, assuring the conditions of optimal common operation are studied in the paper. The mathematic model of the processes in the electric networks with booster transformer has been developed; the opportunity of control by means of the phase-switching BT for power fluxes in the networks has been established. It has been shown that for the groups of switching the windings 1-5 of BT occurs additional consumption of power from the supply network, but for the groups 7-11 its recuperation to the load network. Respectively, switching the windings of BT to the group 1-5 assures the shift of load current to the direction of lag, but in the case of switching to the group 7-11 – towards the outrunning. Wherein, for the groups of switching 10-11 and 1-2 one can observe the increasing of the voltage at the output of BT, but for the groups 7-8 and 4-5 it is decreasing. Based on the analysis of the results of research the diagram and constructive models of the transformer have been proposed. The quasi-stationary and transient regimes were investigated and the conditions of reliable operation at these the regimes have been determined. The ways for increasing the efficient common operation for the transformer and network in the case of switching the thyristors into the circuit of the primary winding of the transformer have been proposed.

  11. An electric field induced in the retina and brain at threshold magnetic flux density causing magnetophosphenes.

    Science.gov (United States)

    Hirata, Akimasa; Takano, Yukinori; Fujiwara, Osamu; Dovan, Thanh; Kavet, Robert

    2011-07-07

    For magnetic field exposures at extremely low frequencies, the electrostimulatory response with the lowest threshold is the magnetophosphene, a response that corresponds to an adult exposed to a 20 Hz magnetic field of nominally 8.14 mT. In the IEEE standard C95.6 (2002), the corresponding in situ field in the retinal locus of an adult-sized ellipsoidal was calculated to be 53 mV m(-1). However, the associated dose in the retina and brain at a high level of resolution in anatomically correct human models is incompletely characterized. Furthermore, the dose maxima in tissue computed with voxel human models are prone to staircasing errors, particularly for the low-frequency dosimetry. In the analyses presented in this paper, analytical and quasi-static finite-difference time-domain (FDTD) solutions were first compared for a three-layer sphere exposed to a uniform 50 Hz magnetic field. Staircasing errors in the FDTD results were observed at the tissue interface, and were greatest at the skin-air boundary. The 99th percentile value was within 3% of the analytic maximum, depending on model resolution, and thus may be considered a close approximation of the analytic maximum. For the adult anatomical model, TARO, exposed to a uniform magnetic field, the differences in the 99th percentile value of in situ electric fields for 2 mm and 1 mm voxel models were at most several per cent. For various human models exposed at the magnetophosphene threshold at three orthogonal field orientations, the in situ electric field in the brain was between 10% and 70% greater than the analytical IEEE threshold of 53 mV m(-1), and in the retina was lower by roughly 50% for two horizontal orientations (anterior-posterior and lateral), and greater by about 15% for a vertically oriented field. Considering a reduction factor or safety factors of several folds applied to electrostimulatory thresholds, the 99th percentile dose to a tissue calculated with voxel human models may be used as an

  12. An electric field induced in the retina and brain at threshold magnetic flux density causing magnetophosphenes

    International Nuclear Information System (INIS)

    Hirata, Akimasa; Takano, Yukinori; Fujiwara, Osamu; Dovan, Thanh; Kavet, Robert

    2011-01-01

    For magnetic field exposures at extremely low frequencies, the electrostimulatory response with the lowest threshold is the magnetophosphene, a response that corresponds to an adult exposed to a 20 Hz magnetic field of nominally 8.14 mT. In the IEEE standard C95.6 (2002), the corresponding in situ field in the retinal locus of an adult-sized ellipsoidal was calculated to be 53 mV m -1 . However, the associated dose in the retina and brain at a high level of resolution in anatomically correct human models is incompletely characterized. Furthermore, the dose maxima in tissue computed with voxel human models are prone to staircasing errors, particularly for the low-frequency dosimetry. In the analyses presented in this paper, analytical and quasi-static finite-difference time-domain (FDTD) solutions were first compared for a three-layer sphere exposed to a uniform 50 Hz magnetic field. Staircasing errors in the FDTD results were observed at the tissue interface, and were greatest at the skin-air boundary. The 99th percentile value was within 3% of the analytic maximum, depending on model resolution, and thus may be considered a close approximation of the analytic maximum. For the adult anatomical model, TARO, exposed to a uniform magnetic field, the differences in the 99th percentile value of in situ electric fields for 2 mm and 1 mm voxel models were at most several per cent. For various human models exposed at the magnetophosphene threshold at three orthogonal field orientations, the in situ electric field in the brain was between 10% and 70% greater than the analytical IEEE threshold of 53 mV m -1 , and in the retina was lower by roughly 50% for two horizontal orientations (anterior-posterior and lateral), and greater by about 15% for a vertically oriented field. Considering a reduction factor or safety factors of several folds applied to electrostimulatory thresholds, the 99th percentile dose to a tissue calculated with voxel human models may be used as an

  13. Numerical Study of Thermo-Fluid Features of Electrically Conducting Fluids in Tube Bank Heat Exchangers Exposed to Uniform Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jin Ho; Kang, Namcheol [Kyungpook Nat’l Univ., Daegu (Korea, Republic of)

    2017-10-15

    When an electrically conducting fluid flows through a staggered tube bank, the heat transfer and fluid flow features are changed by the externally introduced magnetic field. This study provides a numerical investigation of this phenomenon. Heat and fluid flows are investigated for unsteady laminar flows at Reynolds numbers of 50 and 100 with the Hartmann number gradually increasing from zero to 100. As the Hartmann number increases, and owing to the effects of the introduced magnetic field, the velocity boundary layer near the tube wall is thinned, the flow separation is delayed downstream, and the shrinkage of a recirculation zone formed near the rear side is observed. Based on these thermo-fluid deformations, the resulting changes in the local and average Nusselt number are investigated.

  14. Description and operating performance of a parallel-rail electric-arc system with helium driver gas for the Langley 6-inch expansion tube

    Science.gov (United States)

    Moore, J. A.

    1976-01-01

    A parallel-rail arc-discharge system to heat and pressurize the initial helium driver gas of the Langley 6-inch expansion tube is described. This system was designed for a 2.44-m-long driver vessel rated at 138 MPa, with a distance between rails of 20.3 cm. Electric energy was obtained from a capacitor storage system rated at 12,000 V with a maximum energy of 5 MJ. Tests were performed over a range of energy from 1.74 MJ to the maximum value. The operating experience and system performance are discussed, along with results from a limited number of expansion-tube tests with air and carbon dioxide as test gases.

  15. Investigation of a Co-Axial Dual-Mechanical Ports Flux-Switching Permanent Magnet Machine for Hybrid Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Wei Hua

    2015-12-01

    Full Text Available In this paper, a co-axial dual-mechanical ports flux-switching permanent magnet (CADMP-FSPM machine for hybrid electric vehicles (HEVs is proposed and investigated, which is comprised of two conventional co-axial FSPM machines, namely one high-speed inner rotor machine and one low-speed outer rotor machine and a non-magnetic ring sandwiched in between. Firstly, the topology and operation principle of the CADMP-FSPM machine are introduced; secondly, the control system of the proposed electronically-controlled continuously-variable transmission (E-CVT system is given; thirdly, the key design specifications of the CADMP-FSPM machine are determined based on a conventional dual-mechanical ports (DMP machine with a wound inner rotor. Fourthly, the performances of the CADMP-FSPM machine and the normal DMP machine under the same overall volume are compared, and the results indicate that the CADMP-FSPM machine has advantages over the conventional DMP machine in the elimination of brushes and slip rings, improved thermal dissipation conditions for the inner rotor, direct-driven operation, more flexible modes, lower cogging torque and torque ripple, lower total harmonic distortion (THD values of phase PM flux linkage and phase electro-motive force (EMF, higher torque output capability and is suitable for the E-CVT systems. Finally, the pros and cons of the CADMP-FSPM machine are highlighted. This paper lays a theoretical foundation for further research on CADMP-FSPM machines used for HEVs.

  16. photomultiplier tubes

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  17. photomultiplier tube

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  18. The effect of gate voltage on the electrical transport properties in the contacts of C60 to carbon nano tube leads

    International Nuclear Information System (INIS)

    Shokri, A. A.; Nikzad, Sh.

    2012-01-01

    In this paper, we examined the effect of gate voltage, bias voltage, contact geometries and the different bond lengths on the electrical transport properties in a nano structure consisting of C 60 molecule attached to two semi-infinite leads made of single wall carbon nano tubes in the coherent regime. Our calculation was based on the Green's function method within nearest-neighbour tight-binding approximation. After the calculation was of transmission, the electrical current was obtained by the Landauer-Buttiker formula. Next, the effect of the mentioned factors was investigated in the nano structure. The application of the present results may be useful in designing devices based on molecular electronics in nano scale.

  19. Analysed a defective of the machine for a cap-tube nuclear fuel element ME-27 from its electricity point of view

    International Nuclear Information System (INIS)

    Achmad Suntoro

    2009-01-01

    It has been analysed a defective of the machine for a cap-tube nuclear fuel element ME-27 from its electricity point of view. The machine uses magnetic force resistance welding technique. A short circuit was happened within the machine because the nut for tightening high voltage cable for welding transformer was broken so that the cable touched the machine body and produced the short circuit. This condition made both the primary circuit breaker in the building down and produced high voltage pulse induction to the electronic circuit within the machine so that one of its electronic components was defective. This case becomes warnings on how important of tightening a nut according to its strength specification (using wrench torque) and the necessity of voltage transient limitation circuit to be installed. Both of the warnings are necessary for any equipment consuming high electric current oriented such as the ME-27 machine. (author)

  20. Functionalized Multi walled Carbon Nano tubes-Reinforced Viny lester/Epoxy Blend Based Nano composites: Enhanced Mechanical, Thermal, and Electrical Properties

    International Nuclear Information System (INIS)

    Praharaj, A. P.; Behera, D.; Bastia, T. K.; Rout, A. K.

    2015-01-01

    This paper presents a study on the mechanical, thermal, and electrical characterization of a new class of low cost multiphase nano composites consisting of Vinyl ester resin/epoxy (VER/EP) blend (40:60 w/w) reinforced with amine functionalized multi walled carbon nano tubes (f-MWCNTs). Five different sets of VER/EP nano composites are fabricated with addition of 0, 1, 3, 5, and 7 wt.% of f-MWCNTs. A detailed investigation of mechanical properties like tensile strength, impact strength, Young’s modulus, and hardness, thermal properties like thermogravimetric analysis (TGA) and thermal conductivity, electrical properties like dielectric strength, dielectric constant, and electrical conductivity, and corrosive and swelling properties of the nano composites has been carried out. Here, we report significant improvement in all the above properties of the fabricated nano composites with nano filler (f-MWCNTs) addition compared to the virgin blend (0 wt. nano filler loading). The properties are best observed in case of 5 wt.% nano filler loading with gradual deterioration thereafter which may be due to the nucleating tendency of the nano filler particles. Thus the above nano composites could be a preferable candidate for a wide range of structural, thermal, electrical, and solvent based applications.

  1. Physics of magnetic flux ropes

    Science.gov (United States)

    Russell, C. T.; Priest, E. R.; Lee, L. C.

    The present work encompasses papers on the structure, waves, and instabilities of magnetic flux ropes (MFRs), photospheric flux tubes (PFTs), the structure and heating of coronal loops, solar prominences, coronal mass ejections and magnetic clouds, flux ropes in planetary ionospheres, the magnetopause, magnetospheric field-aligned currents and flux tubes, and the magnetotail. Attention is given to the equilibrium of MFRs, resistive instability, magnetic reconnection and turbulence in current sheets, dynamical effects and energy transport in intense flux tubes, waves in solar PFTs, twisted flux ropes in the solar corona, an electrodynamical model of solar flares, filament cooling and condensation in a sheared magnetic field, the magnetopause, the generation of twisted MFRs during magnetic reconnection, ionospheric flux ropes above the South Pole, substorms and MFR structures, evidence for flux ropes in the earth magnetotail, and MFRs in 3D MHD simulations.

  2. Heat Exchanger Tube Inspection of Nuclear Power Plants using IRIS Technique

    International Nuclear Information System (INIS)

    Yoon, Byung Sik; Yang, Seung Han; Song, Seok Yoon; Kim, Yong Sik; Lee, Hee Jong

    2005-01-01

    Inspection of heat exchange tubing include steam generator of nuclear power plant mostly performed with eddy current method. Recently, various inspection technique is available such as remote field eddy current, flux leakage and ultrasonic methods. Each of these techniques has its merits and limitations. Electromagnetic techniques are very useful to locate areas of concern but sizing is hard because of the difficult interpretation of an electric signature. On the other hand, ultrasonic methods are very accurate in measuring wall loss damage, and are reliable for detecting cracks. Additionally ultrasound methods is not affected by support plates or tube sheets and variation of electrical conductivity or permeability. Ultrasound data is also easier to analyze since the data displayed is generally the remaining wall thickness. It should be emphasized that ultrasound is an important tool for sizing defects in tubing. In addition, it can be used in situations where eddy current or remote field eddy current is not reliable, or as a flaw assessment tool to supplement the electromagnetic data. The need to develop specialized ultrasonic tools for tubing inspection was necessary considering the limitations of electromagnetic techniques to some common inspection problems. These problems the sizing of wall loss in carbon steel tubes near the tube sheet or support plate, sizing internal erosion damage, and crack detection. This paper will present an IRIS(Internal Rotating Inspection System) ultrasonic tube inspection technique for heat exchanger tubing in nuclear power plant and verify inspection reliability for artificial flaw embedded to condenser tube

  3. Feeding Tubes

    Science.gov (United States)

    ... the TPN. Tubes Used for Enteral Feeds NG (Nasogastric Tube) A flexible tube is placed via the nose, ... portion of the small intestine Naso – nose NG – Nasogastric Tube -ostomy – new opening Percutaneous – through the skin PEJ – ...

  4. Effect of Tube Pitch on Pool Boiling Heat Transfer of Vertical Tube Bundle

    International Nuclear Information System (INIS)

    Kang, Myeong Gie

    2016-01-01

    Summarizing the previous results it can be stated that heat transfer coefficients are highly dependent on the tube pitch and the heat flux of the relevant tube. The published results are mostly about the horizontal tubes. However, there are many heat exchangers consisting of vertical tubes like AP600. Therefore, the focus of the present study is an identification of the effects of a tube pitch as well as the heat flux of a relevant tube on the heat transfer of a tube bundle installed vertically. When the heat flux is increased many bubbles are generating due to the increase of the nucleation sites. The bubbles become coalescing with the nearby bubbles and generates big bunches of bubbles on the tube surface. This prevents the access of the liquid to the surface and deteriorates heat transfer. The bubble coalescence is competing with the mechanisms enhancing heat transfer. The pitch was varied from 28.5 mm to 95 mm and the heat flux of the nearby tube was changed from 0 to 90kW/m 2 . The enhancement of the heat transfer is clearly observed when the heat flux of the nearby tube becomes larger and the heat flux of the upper tube is less than 40kW/m 2 . The effect of the tube pitch on heat transfer is negligible as the value of DP/ is increased more than 4.

  5. Optimal Design of an Axial-Flux Permanent-Magnet Middle Motor Integrated in a Cycloidal Reducer for a Pedal Electric Cycle

    OpenAIRE

    Yang, Yee-Pien; Jiang, Jia-Ming

    2015-01-01

    This paper proposes an optimal design of a middle motor integrated into a mid-drive unit for pedal electric cycles. This middle motor is an axial-flux permanent magnet brushless DC motor with a stator plate. Facing this plate is a rotor plate that acts as an eccentric component of a cycloidal reducer next to the stator. Both the middle motor and cycloidal reducer are easily installed on the same axle of the bike crankset. In the preliminary design, driving requirements are used to make the mi...

  6. The effect of SiC powder mixing electrical discharge machining on white layer thickness, heat flux and fatigue life of AISI D2 die steel

    Directory of Open Access Journals (Sweden)

    Ahmed Al-Khazraji

    2016-09-01

    Full Text Available This paper deals with studying the effect of powder mixing electrical discharge machining (PMEDM parameters using copper and graphite electrodes on the white layer thickness (WLT, the total heat flux generated and the fatigue life. Response surface methodology (RSM was used to plan and design the experimental work matrices for two groups of experiments: for the first EDM group, kerosene dielectric was used alone, whereas the second was treated by adding the SiC micro powders mixing to dielectric fluid (PMEDM. The total heat flux generated and fatigue lives after EDM and PMEDM models were developed by FEM using ANSYS 15.0 software. The graphite electrodes gave a total heat flux higher than copper electrodes by 82.4%, while using the SiC powder and graphite electrodes gave a higher total heat flux than copper electrodes by 91.5%. The lowest WLT values of 5.0 µm and 5.57 µm are reached at a high current and low current with low pulse on time using the copper and graphite electrodes and the SiC powder, respectively. This means that there is an improvement in WLT by 134% and 110%, respectively, when compared with the use of same electrodes and kerosene dielectric alone. The graphite electrodes with PMEDM and SiC powder improved the experimental fatigue safety factor by 7.30% compared with the use of copper electrodes and by 14.61% and 18.61% compared with results using the kerosene dielectric alone with copper and graphite electrodes, respectively.

  7. An application of liquid sublayer dryout mechanism to the prediction of critical heat flux under low pressure and low velocity conditions in round tubes

    International Nuclear Information System (INIS)

    Lee, Kwang-Won; Yang, Jae-Young; Baik, Se-Jin

    1997-01-01

    Based on several experimental evidences for nucleate boiling in annular film and the existence of residual liquid film flow rate at the critical heat flux (CHF) location, the liquid sublayer dryout (LSD) mechanism under annular film is firstly introduced to evaluate the CHF data at low pressure and low velocity (LPLV) conditions, which would not be predicted by a normal annular film dryout (AFD) model. In this study, the CHF occurrence due to annular film separation or breaking down is phenomenologically modelled by applying the LSD mechanism to this situation. In this LSD mechanism, the liquid sublayer thickness, the incoming liquid velocity to the liquid sublayer, and the axial distance from the onset of annular flow to the CHF location are used as the phenomena-controlling parameters. From the model validation on the 1406 CHF data points ranging over P = 0.1 - 2 MPa, G = 4 - 499 kg/m 2 s, L/D = 4 - 402, most of CHF data (more than 1000 points) are predicted within ±30% error bounds by the LSD mechanism. However, some calculation results that critical qualities are less than 0.4 are considerably overestimated by this mechanism. These overpredictions seem to be caused by inadequate CHF mechanism classification criteria and an insufficient consideration of the flow instability effect on CHF. Further studies for a new classification criterion screening the CHF data affected by flow instabilities and a new bubble detachment model for LPLV conditions are needed to improve the model accuracy. (author)

  8. Electricity

    Indian Academy of Sciences (India)

    AC power generation, its transmission and distribution. The well known observations made by Oersted that an electric current produces a magnetic field led a number of researchers to investigate whether the converse was true i.e. whether electric current can be produced from a magnetic field. Michael Faraday of England ...

  9. Growth of NBT-BT single crystals by flux method and their structural, morphological and electrical characterizations

    Science.gov (United States)

    Kanuru, Sreenadha Rao; Baskar, K.; Dhanasekaran, R.; Kumar, Binay

    2016-05-01

    In this paper, one of the important, eco-friendly polycrystalline material, (1-x)(Na0.5Bi0.5)TiO3 (NBT) - xBaTiO3 (BT) of different compositions (x=0.07, 0.06 and 0.05 wt%) around the morphotropic phase boundary (MPB) were synthesized by solid state reaction technique. And the single crystals with 13×7×7 mm3, 12×12×7 mm3 and 10×7×4 mm3 dimensions were grown by self flux method. The morphology, crystal structure and unit-cell parameters have been studied and the monoclinic phase has been identified for 0.07 wt% of BT. Higher BT concentration changes the crystal habit and the mechanism has been studied clearly. Raman spectroscopy at room-temperature confirms the presence of functional groups. The quality of the as grown single crystals was examined by high resolution x-ray diffraction analysis. The dielectric properties of the as grown crystals were investigated in the frequency range of 20 Hz-2 MHz from room temperature to 450 °C. The broad dielectric peak and frequency dispersion demonstrates the relaxor behavior of grown crystals. The dielectric constant (εr), transition temperature (Tm), and depolarization temperature (Td) of the grown crystals are found to be comparatively good. The diffusive factor (γ) from Curie-Weiss law confirms the as grown NBT-BT single crystals are relaxor in nature.

  10. Thermo-electric pump

    International Nuclear Information System (INIS)

    Georges, J.-L.; Veyret, J.-F.

    1973-01-01

    Description is given of a thermo-pump for electrically conductive liquid fluids, e.g. for a liquid metal such as sodium. This pump is characterized in that the piping for the circulation of the conductive liquid is constituted by a plurality of conduits defined by two co-axial cylinders and two walls parallel to their axis. Each conduit limited outside by a magnet, inside by a mild-iron tube, and laterally by two materials forming a thermocouple. The electric current generated by that thermo-couple and the magnetic flux generated by the magnets both loop the loop through an outer cylindrical nickel shell. This can be applied to sodium circulation loops for testing nuclear fuel elements [fr

  11. Developmental Axon Stretch Stimulates Neuron Growth While Maintaining Normal Electrical Activity, Intracellular Calcium Flux, and Somatic Morphology

    Directory of Open Access Journals (Sweden)

    Joseph R Loverde

    2015-08-01

    Full Text Available Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18 % applied over 5 minutes. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25 % strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury.

  12. Developmental axon stretch stimulates neuron growth while maintaining normal electrical activity, intracellular calcium flux, and somatic morphology.

    Science.gov (United States)

    Loverde, Joseph R; Pfister, Bryan J

    2015-01-01

    Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18% applied over 5 min. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25% strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury.

  13. Electricity

    Indian Academy of Sciences (India)

    which removes the heat produced In the core and the colis. I represents an Isolator which is a kind of. 'switch' used to isolate the station from the grid. Note the huge Insulators (marked I) that are used. The steel structures marked S support the conductors through insulators (courtesy: Kirloskar Electric Company, Bangalore).

  14. Experimental study of heat transfer for parallel flow in tube bundles with constant heat flux and for medium Prandtl numbers; Etude experimentale du transfert de chaleur dans des faisceaux tubulaires en ecoulement parallele pour une densite de flux thermique constante dans le domaine des nombres de Prandtl moyens

    Energy Technology Data Exchange (ETDEWEB)

    Rieger, M. [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    The heat transfer parameters were determined experimentally in electrically heated tube bundles for turbulent flow parallel to the axis. The tubes were arranged in a pattern of equilateral triangles. The ratios of the distance between the axes of the tubes to their external diameter were 1.60 and 1.25 in the two test sections studied. The experiments were carried out with distilled water and with a mixture of 60 per cent ethylene glycol and 40 per cent water. The values obtained for the Prandtl numbers in this way fell within the range from 2.3 to 18. The Reynolds numbers were varied between 10{sup 4} and 2.10{sup 5}. The relation between the mean heat transfer coefficients and the friction factor in the tube bundles was found from the experiments as: Nu = [Re Pr {zeta}/8]/[1+{radical}({zeta}/8) 8.8 (Pr-1.3) Pr{sup -0.22}]. The experimentally determined mean Nusselt numbers were also given by the following function: Nu = (0.0122 + 0.00245 p/d) Re{sup 0.86} Pr{sup 0.4}, with a maximum deviation of {+-}4 per cent. For certain local Nusselt numbers, deviations of up to 20 per cent with respect to the relations given were observed. (author) [French] Dans des faisceaux tubulaires a chauffage electrique parcourus par un ecoulement turbulent parallele a l'axe, on a determine experimentalement les parametres du transfert de chaleur. Les centres des sections droites des tubes etaient des sommets de triangles equilateraux. Les rapports de la distance a l'axe des tubes et leur diametre exterieur dans les deux veines de mesure etudiees etaient de 1.60 et 1.25. Des essais furent effectues avec de l'eau distillee ainsi qu'avec un melange de 60 pour cent de glycol ethylenique et 40 pour cent d'eau. Les valeurs des nombres de Prandtl obtenues ainsi etaient situees entre 2.3 a 18. On a fait varier les nombres de Reynolds entre 10{sup 4} et 2.10{sup 5}. La relation entre les nombres caracteristiques de transfert de chaleur moyens et la perte de charge dans

  15. Observational Evidence for Rising Penumbral Flux Tubes?

    Czech Academy of Sciences Publication Activity Database

    Jurčák, Jan; Sobotka, Michal

    2007-01-01

    Roč. 241, č. 2 (2007), s. 223-233 ISSN 0038-0938 R&D Projects: GA AV ČR IAA3003404; GA ČR GA205/04/2129 Institutional research plan: CEZ:AV0Z10030501 Keywords : Sun * sunspots * magnetic field Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.479, year: 2007

  16. Models of Flux Tubes from Constrained Relaxation

    Indian Academy of Sciences (India)

    Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately.

  17. SURFACE ALFVEN WAVES IN SOLAR FLUX TUBES

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Andries, J.; Soler, R.; Van Doorsselaere, T. [Centre for Plasma Astrophysics, Department of Mathematics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Arregui, I.; Terradas, J., E-mail: marcel.goossens@wis.kuleuven.be [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2012-07-10

    Magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. Alfven waves and magneto-sonic waves are particular classes of MHD waves. These wave modes are clearly different and have pure properties in uniform plasmas of infinite extent only. Due to plasma non-uniformity, MHD waves have mixed properties and cannot be classified as pure Alfven or magneto-sonic waves. However, vorticity is a quantity unequivocally related to Alfven waves as compression is for magneto-sonic waves. Here, we investigate MHD waves superimposed on a one-dimensional non-uniform straight cylinder with constant magnetic field. For a piecewise constant density profile, we find that the fundamental radial modes of the non-axisymmetric waves have the same properties as surface Alfven waves at a true discontinuity in density. Contrary to the classic Alfven waves in a uniform plasma of infinite extent, vorticity is zero everywhere except at the cylinder boundary. If the discontinuity in density is replaced with a continuous variation of density, vorticity is spread out over the whole interval with non-uniform density. The fundamental radial modes of the non-axisymmetric waves do not need compression to exist unlike the radial overtones. In thin magnetic cylinders, the fundamental radial modes of the non-axisymmetric waves with phase velocities between the internal and the external Alfven velocities can be considered as surface Alfven waves. On the contrary, the radial overtones can be related to fast-like magneto-sonic modes.

  18. Particle acceleration in relativistic magnetic flux-merging events

    Science.gov (United States)

    Lyutikov, Maxim; Sironi, Lorenzo; Komissarov, Serguei S.; Porth, Oliver

    2017-12-01

    Using analytical and numerical methods (fluid and particle-in-cell simulations) we study a number of model problems involving merger of magnetic flux tubes in relativistic magnetically dominated plasma. Mergers of current-carrying flux tubes (exemplified by the two-dimensional `ABC' structures) and zero-total-current magnetic flux tubes are considered. In all cases regimes of spontaneous and driven evolution are investigated. We identify two stages of particle acceleration during flux mergers: (i) fast explosive prompt X-point collapse and (ii) ensuing island merger. The fastest acceleration occurs during the initial catastrophic X-point collapse, with the reconnection electric field of the order of the magnetic field. During the X-point collapse, particles are accelerated by charge-starved electric fields, which can reach (and even exceed) values of the local magnetic field. The explosive stage of reconnection produces non-thermal power-law tails with slopes that depend on the average magnetization . For plasma magnetization 2$ the spectrum power-law index is 2$ ; in this case the maximal energy depends linearly on the size of the reconnecting islands. For higher magnetization, 2$ , the spectra are hard, , yet the maximal energy \\text{max}$ can still exceed the average magnetic energy per particle, , by orders of magnitude (if is not too close to unity). The X-point collapse stage is followed by magnetic island merger that dissipates a large fraction of the initial magnetic energy in a regime of forced magnetic reconnection, further accelerating the particles, but proceeds at a slower reconnection rate.

  19. Optimal Design of an Axial-Flux Permanent-Magnet Middle Motor Integrated in a Cycloidal Reducer for a Pedal Electric Cycle

    Directory of Open Access Journals (Sweden)

    Yee-Pien Yang

    2015-12-01

    Full Text Available This paper proposes an optimal design of a middle motor integrated into a mid-drive unit for pedal electric cycles. This middle motor is an axial-flux permanent magnet brushless DC motor with a stator plate. Facing this plate is a rotor plate that acts as an eccentric component of a cycloidal reducer next to the stator. Both the middle motor and cycloidal reducer are easily installed on the same axle of the bike crankset. In the preliminary design, driving requirements are used to make the middle motor specifications. The numbers of stator slots and magnet poles on the rotor were chosen to achieve the best winding factor, and the winding layout was determined accordingly. A one-dimensional magnetic circuit model of the middle motor was built, and its shape was optimized utilizing a multifunctional optimization system tool. Finally, the resulting design was verified and refined by a finite element analysis. A prototype of the middle motor was fabricated with a stator made of a soft magnetic composite and integrated with a cycloidal reducer. Experimental results show that the motor has a sinusoidal back electromotive force. Additionally, it is easily controlled by sinusoidal currents with acceptable torque and speed curves.

  20. Failure analysis of boiler tube

    International Nuclear Information System (INIS)

    Mehmood, K.; Siddiqui, A.R.

    2007-01-01

    Boiler tubes are energy conversion components where heat energy is used to convert water into high pressure superheated steam, which is then delivered to a turbine for electric power generation in thermal power plants or to run plant and machineries in a process or manufacturing industry. It was reported that one of the tubes of a fire-tube boiler used in a local industry had leakage after the formation of pits at the external surface of the tube. The inner side of the fire tube was working with hot flue gasses with a pressure of 10 Kg/cm/sup 2/ and temperature 225 degree C. The outside of the tube was surrounded by feed water. The purpose of this study was to determine the cause of pits developed at the external surface of the failed boiler tube sample. In the present work boiler tube samples of steel grade ASTM AI61/ASTM A192 were analyzed using metallographic analysis, chemical analysis, and mechanical testing. It was concluded that the appearance of defects on the boiler tube sample indicates cavitation type corrosion failure. Cavitation damage superficially resembled pitting, but surface appeared considerably rougher and had many closely spaced pits. (author)

  1. Improving the calandria tubes for CANDU reactors

    International Nuclear Information System (INIS)

    Coleman, C.E.; Fong, R.W.L.; Doubt, G.L.

    1997-01-01

    CANDU calandria tubes are made from annealed Zircaloy-2 sheet formed into a cylinder and welded along its length to make the tube. The current calandria tubes have given exemplary service for many years. With more stringent regulations and the need to accommodate warm cooling water in tropical countries, we started a development program to increase the margins for failure during postulated accidents. These improvements involve increasing the tube strength and optimising the heat-transfer from an excessively hot fuel channel to the cool moderator. If the postulated accident involves a pressure tube break, it would be desirable if the calandria tube withstood the full pressure of the heat-transport system. The weakest link in current calandria tubes is the weld. Thickening the weld can increase the strength by 20% while seamless tubes can be 45% stronger than current tubes. The latter tubes can hold full system pressure for many hours without failure. If during the postulated accident the fuel and pressure tube become excessively hot but do not touch the calandria tube, the radiant heat loss must be maximised. Current calandria tubes have an absorptivity (emissivity) of about 0.2. To protect the fuel and the fuel channel we have devised a finish to the inside surface of the calandria tube that increases the emissivity to 0.7. If during the postulated accident the hot pressure tube touches the cool calandria tube, the contact conductance and the critical heat flux must be optimised to ensure nucleate boiling of the moderator at the outside surface of the calandria tube and therefore efficient exploitation of the moderator as a heat sink. In laboratory tests small ridges on the inside surface and roughening of the outside surface have been shown to increase the margins against failure and increase the possible moderator temperatures thus providing the opportunity to decrease the cost of the moderator heat-exchange system and remove restrictions on reactor operation in

  2. Fields Of View Of X-Ray-Telescope Collimator Tubes

    Science.gov (United States)

    Safren, Harvey G.

    1992-01-01

    Results of theoretical analysis conducted to determine fields of view and irradiation patterns of collimator tubes of various shapes indicates, while background flux incident on surface at outlet of tube determined by ratio between diameter and length, shape of tube important in screening out background radiation.

  3. Ear Tubes

    Science.gov (United States)

    ... of the ear drum or eustachian tube, Down Syndrome, cleft palate, and barotrauma (injury to the middle ear caused by a reduction of air pressure, ... specialist) may be warranted if you or your child has experienced repeated ... fluid in the middle ear, barotrauma, or have an anatomic abnormality that ...

  4. High flux compact neutron generators

    International Nuclear Information System (INIS)

    Reijonen, J.; Lou, T.-P.; Tolmachoff, B.; Leung, K.-N.; Verbeke, J.; Vujic, J.

    2001-01-01

    Compact high flux neutron generators are developed at the Lawrence Berkeley National Laboratory. The neutron production is based on D-D or D-T reaction. The deuterium or tritium ions are produced from plasma using either a 2 MHz or 13.56 MHz radio frequency (RF) discharge. RF-discharge yields high fraction of atomic species in the beam which enables higher neutron output. In the first tube design, the ion beam is formed using a multiple hole accelerator column. The beam is accelerated to energy of 80 keV by means of a three-electrode extraction system. The ion beam then impinges on a titanium target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated. The MCNP computation code has predicted a neutron flux of ∼10 11 n/s for the D-D reaction at beam intensity of 1.5 A at 150 kV. The neutron flux measurements of this tube design will be presented. Recently new compact high flux tubes are being developed which can be used for various applications. These tubes also utilize RF-discharge for plasma generation. The design of these tubes and the first measurements will be discussed in this presentation

  5. Growth and Accumulation of Secondary Metabolites in Perilla as Affected by Photosynthetic Photon Flux Density and Electrical Conductivity of the Nutrient Solution

    Directory of Open Access Journals (Sweden)

    Na Lu

    2017-05-01

    Full Text Available The global demand for medicinal plants is increasing. The quality of plants grown outdoors, however, is difficult to control. Myriad environmental factors influence plant growth and directly impact biosynthetic pathways, thus affecting the secondary metabolism of bioactive compounds. Plant factories use artificial lighting to increase the quality of medicinal plants and stabilize production. Photosynthetic photon flux density (PPFD and electrical conductivity (EC of nutrient solutions are two important factors that substantially influence perilla (Perilla frutescens, Labiatae plant growth and quality. To identify suitable levels of PPFD and EC for perilla plants grown in a plant factory, the growth, photosynthesis, and accumulation of secondary metabolites in red and green perilla plants were measured at PPFD values of 100, 200, and 300 μmol m-2 s-1 in nutrient solutions with EC values of 1.0, 2.0, and 3.0 dS m-1. The results showed significant interactive effects between PPFD and EC for both the fresh and dry weights of green perilla, but not for red perilla. The fresh and dry weights of shoots and leafy areas were affected more by EC than by PPFD in green perilla, whereas they were affected more by PPFD than by EC in red perilla. Leaf net photosynthetic rates were increased as PPFD increased in both perilla varieties, regardless of EC. The perillaldehyde concentration (mg g-1 in red perilla was unaffected by the treatments, but accumulation in plants (mg per plant was significantly enhanced as the weight of dry leaves increased. Perillaldehyde concentrations in green perilla showed significant differences between combinations of the highest PPFD with the highest EC and the lowest PPFD with the lowest EC. Rosmarinic acid concentration (mg g-1 was increased in a combination of low EC and high PPFD conditions. Optimal cultivation conditions of red and green perilla in plant factory will be discussed in terms of plant growth and contents of

  6. Neutron tubes

    Science.gov (United States)

    Leung, Ka-Ngo [Hercules, CA; Lou, Tak Pui [Berkeley, CA; Reijonen, Jani [Oakland, CA

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  7. Source Terms for HFIR Beam Tube Shielding Analyses, and a Complete Shielding Analysis of the HB-3 Tube

    Energy Technology Data Exchange (ETDEWEB)

    Bucholz, J.A.

    2000-07-01

    The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory is in the midst of a massive upgrade program to enhance experimental facilities. The reactor presently has four horizontal experimental beam tubes, all of which will be replaced or redesigned. The HB-2 beam tube will be enlarged to support more guide tubes, while the HB-4 beam tube will soon include a cold neutron source.

  8. Source Terms for HFIR Beam Tube Shielding Analyses, and a Complete Shielding Analysis of the HB-3 Tube

    International Nuclear Information System (INIS)

    Bucholz, J.A.

    2000-01-01

    The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory is in the midst of a massive upgrade program to enhance experimental facilities. The reactor presently has four horizontal experimental beam tubes, all of which will be replaced or redesigned. The HB-2 beam tube will be enlarged to support more guide tubes, while the HB-4 beam tube will soon include a cold neutron source

  9. A Flue Gas Tube for Thermoelectric Generator

    DEFF Research Database (Denmark)

    2013-01-01

    The invention relates to a flue gas tube (FGT) (1) for generation of thermoelectric power having thermoelectric elements (8) that are integrated in the tube. The FTG may be used in combined heat and power (CHP) system (13) to produce directly electricity from waste heat from, e.g. a biomass boiler....... The CHP system may also be operated in a heating or cooling mode, thus being able to heat or cool water by feeding electricity to the system....

  10. Eddy current measurement of remote tube positions in CANDU reactors

    International Nuclear Information System (INIS)

    Craig, S.T.; Krause, T.W.; Luloff, B.V.; Schankula, J.J.

    2004-01-01

    Regular NDE inspections of CANDU reactors are made by inserting probes into one of 380 pressure tubes that traverse the core. Each pressure tube is surrounded by a gas annulus and contained in a calandria tube. Separation between the pressure tube and calandria tubes is maintained by four spacers. Moderator water surrounds the calandria tubes. Auxiliary tubular assemblies within the moderator run perpendicular to the pressure tube for the injection of neutron poison and for mounting flux detectors. Laboratory tests have demonstrated the use of remote field eddy currents to measure the distance between the pressure tube and auxiliary tubes. Implementation uses coils from two appropriately separated probes in existing inspection heads. These coils are the transmit coil used for sensing the spacers and the receive coil from a probe used to measure the gap between the pressure tube and its surrounding calandria tube. The axis of the transmit coil is aligned with the axis of the pressure tube. The receive coil axis is perpendicular to the transmit coil, and located near the inner diameter of the pressure tube. Although the coil spacing and orientation are not ideal, laboratory tests have demonstrated repeatable measurements under conditions of varying liftoff, pressure tube wall thickness and diameter, and gap between pressure tube and calandria tube. The experimental conditions, test cases, and results are presented. (author)

  11. Neutron flux measurement by mobile detectors

    International Nuclear Information System (INIS)

    Verchain, M.

    1987-01-01

    Various incore instrumentation systems and their technological evolution are first reviewed. Then, for 1300 MWe PWR nuclear power plant, temperature and neutron flux measurement are described. Mobile fission chambers, with their large measuring range and accurate location allow a good knowledge of the core. Other incore measures are possible because of flux detector thimble tubes inserted in the reactor core [fr

  12. Physics of magnetic flux ropes. Geophysical Monograph, No. 58

    International Nuclear Information System (INIS)

    Russell, C.T.; Priest, E.R.; Lee, L.C.

    1990-01-01

    The present work encompasses papers on the structure, waves, and instabilities of magnetic flux ropes (MFRs), photospheric flux tubes (PFTs), the structure and heating of coronal loops, solar prominences, coronal mass ejections and magnetic clouds, flux ropes in planetary ionospheres, the magnetopause, magnetospheric field-aligned currents and flux tubes, and the magnetotail. Attention is given to the equilibrium of MFRs, resistive instability, magnetic reconnection and turbulence in current sheets, dynamical effects and energy transport in intense flux tubes, waves in solar PFTs, twisted flux ropes in the solar corona, an electrodynamical model of solar flares, filament cooling and condensation in a sheared magnetic field, the magnetopause, the generation of twisted MFRs during magnetic reconnection, ionospheric flux ropes above the South Pole, substorms and MFR structures, evidence for flux ropes in the earth magnetotail, and MFRs in 3D MHD simulations

  13. Heat transfer enhancement with elliptical tube under turbulent flow TiO2-water nanofluid

    Directory of Open Access Journals (Sweden)

    Hussein Adnan M.

    2016-01-01

    Full Text Available Heat transfer and friction characteristics were numerically investigated, employing elliptical tube to increase the heat transfer rate with a minimum increase of pressure drop. The flow rate of the tube was in a range of Reynolds number between 10000 and 100000. FLUENT software is used to solve the governing equation of CFD (continuity, momentum and energy by means of a finite volume method (FVM. The electrical heater is connected around the elliptical tube to apply uniform heat flux (3000 W/m2 as a boundary condition. Four different volume concentrations in the range of 0.25% to 1% and different TiO2 nanoparticle diameters in the range of 27 nm to 50 nm, dispersed in water are utilized. The CFD numerical results indicate that the elliptical tube can enhance heat transfer and friction factor by approximately 9% and 6% than the circular tube respectively. The results show that the Nusselt number and friction factor increase with decreasing diameters but increasing volume concentrations of nanoparticles.

  14. Experimental tests of FTE theories. [Flux Transfer Event

    Science.gov (United States)

    Sonnerup, B. U. O.

    1988-01-01

    A brief overview is presented of a number of qualitative geometrical models as well as simulation models of flux transfer events (FTEs) and an attempt is made to identify critical observational tests that would help discriminate between these models. These tests are concerned with flux tube orientation, speed and structure. Available single and multiple spacecraft observations are discussed in the context of these tests. Particular attention is given to the problem of determining flux-tube orientation and speed from a single spacecraft.

  15. The relation between reconnected flux, the parallel electric field, and the reconnection rate in a three-dimensional kinetic simulation of magnetic reconnection

    International Nuclear Information System (INIS)

    Wendel, D. E.; Olson, D. K.; Hesse, M.; Kuznetsova, M.; Adrian, M. L.; Aunai, N.; Karimabadi, H.; Daughton, W.

    2013-01-01

    We investigate the distribution of parallel electric fields and their relationship to the location and rate of magnetic reconnection in a large particle-in-cell simulation of 3D turbulent magnetic reconnection with open boundary conditions. The simulation's guide field geometry inhibits the formation of simple topological features such as null points. Therefore, we derive the location of potential changes in magnetic connectivity by finding the field lines that experience a large relative change between their endpoints, i.e., the quasi-separatrix layer. We find a good correspondence between the locus of changes in magnetic connectivity or the quasi-separatrix layer and the map of large gradients in the integrated parallel electric field (or quasi-potential). Furthermore, we investigate the distribution of the parallel electric field along the reconnecting field lines. We find the reconnection rate is controlled by only the low-amplitude, zeroth and first–order trends in the parallel electric field while the contribution from fluctuations of the parallel electric field, such as electron holes, is negligible. The results impact the determination of reconnection sites and reconnection rates in models and in situ spacecraft observations of 3D turbulent reconnection. It is difficult through direct observation to isolate the loci of the reconnection parallel electric field amidst the large amplitude fluctuations. However, we demonstrate that a positive slope of the running sum of the parallel electric field along the field line as a function of field line length indicates where reconnection is occurring along the field line

  16. Tracheostomy tube - eating

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000464.htm Tracheostomy tube - eating To use the sharing features on ... when you swallow foods or liquids. Eating and Tracheostomy Tubes When you get your tracheostomy tube, or ...

  17. Eustachian tube patency

    Science.gov (United States)

    Eustachian tube patency refers to how much the eustachian tube is open. The eustachian tube runs between the middle ear and the throat. It controls the pressure behind the eardrum and middle ear space. This helps keep ...

  18. Heat exchanger tube mounts

    Science.gov (United States)

    Wolowodiuk, W.; Anelli, J.; Dawson, B.E.

    1974-01-01

    A heat exchanger in which tubes are secured to a tube sheet by internal bore welding is described. The tubes may be moved into place in preparation for welding with comparatively little trouble. A number of segmented tube support plates are provided which allow a considerable portion of each of the tubes to be moved laterally after the end thereof has been positioned in preparation for internal bore welding to the tube sheet. (auth)

  19. Characteristics of the JRR-3M neutron guide tubes

    International Nuclear Information System (INIS)

    Suzuki, Masatoshi; Ichikawa, Hiroki; Kawabata, Yuji.

    1993-01-01

    Large scale neutron guide tubes have been installed in the upgraded JRR-3 (Japan Research Reactor No.3, JRR-3M). The total length of the guide tubes is 232m. The neutron fluxes and spectra were measured at the end of the neutron guide tubes. The neutron fluxes of thermal neutron guide tubes with characteristic wavelength of 2A are 1.2 x 10 8 n/cm 2 · s. The neutron fluxes of cold guide tubes are 1.4 x 10 8 n/cm 2 · s with characteristic wavelength of 4A and 2.0 x 10 8 n/cm 2 · s with 6A when the cold neutron source is operated. The neutron spectra measured by time-of-flight method agree well with their designed ones. (author)

  20. photomultiplier tube

    CERN Multimedia

    A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  1. photomultiplier tube

    CERN Multimedia

    Philips. 150AVP. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  2. Tube holding system

    International Nuclear Information System (INIS)

    Cunningham, R.C.

    1978-01-01

    A tube holding rig is described for the lateral support of tubes arranged in tight parcels in a heat exchanger. This tube holding rig includes not less than two tube supporting assemblies, with a space between them, located crosswise with respect to the tubes, each supporting assembly comprising a first set of parallel components in contact with the tubes, whilst a second set of components is also in contact with the tubes. These two sets of parts together define apertures through which the tubes pass [fr

  3. Burnout in a channel with non-uniform circumferential heat flux

    International Nuclear Information System (INIS)

    Lee, D.H.

    1966-03-01

    Burnout experiments are reported for uniform flux and circumferential flux tilt (maximum/average flux about 1.25) with tubes and annuli, all the experiments having uniform axial heating. These show similar results, the burnout power with flux tilt being within 10% of that with uniform flux. For the same mean exit steam quality, the local maximum flux is higher than the predicted burnout value and generally a better prediction is obtained using the average flux. (author)

  4. Tubes, Mono Jets, Squeeze Out and CME

    Energy Technology Data Exchange (ETDEWEB)

    Longacre, R. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-10-23

    Glasma Flux Tubes, Mono Jets with squeeze out flow around them plus the Chiral Magnetic Effect(CME) are physical phenomenon that generate two particle correlation with respect to the reaction plane in mid-central 20% to 30% Au-Au collision √sNN = 200.0 GeV measured at RHIC.

  5. Numerical investigation of heat transfer in annulus laminar flow of multi tubes-in-tube helical coil

    Science.gov (United States)

    Nada, S. A.; Elattar, H. F.; Fouda, A.; Refaey, H. A.

    2018-03-01

    In the present study, a CFD analysis using ANSYS-FLUENT 14.5 CFD package is used to investigate the characteristics of heat transfer of laminar flow in annulus formed by multi tubes in tube helically coiled heat exchanger. The numerical results are validated by comparison with previous experimental data and fair agreements were existed. The influences of the design and operation parameters such as heat flux, Reynolds numbers and annulus geometry on the heat transfer characteristics are investigated. Different annulus of different numbers of inner tubes, specifically 1, 2, 3, 4 and 5 tubes, are tested. The Results showed that for all the studied annulus, the heat flux has no effect on the Nusselt number and compactness parameter. The annulus formed by using five inner tubes showed the best heat transfer performance and compactness parameter. Correlation of predicting Nusselt number in terms of Reynolds number and number of inner tubes are presented.

  6. Effect of B+ Flux on the electrical activation of ultra-shallow B+ implants in Ge

    DEFF Research Database (Denmark)

    Yates, B.R.; Darby, B.L.; Petersen, Dirch Hjorth

    2012-01-01

    The residual implanted dose of ultra-shallow B+ implants in Ge was characterized using elastic recoil detection and was determined to correlate well with simulations with a dose loss of 23% due to ion backscattering for 2 keV implants in Ge. The electrical characterization of ultra-shallow B+ imp...

  7. Modelling of time delay of electrical breakdown for nitrogen-filled tubes at pressures of 6.6 and 13.3 mbar in the increase region of the memory curve

    International Nuclear Information System (INIS)

    Nesic, N T; Ristic, G S; Pejovic, M M; Karamarkovic, J P

    2008-01-01

    Experimentally measured electrical breakdown time delay data versus the afterglow period (representing 'memory curves') for nitrogen-filled tubes at pressures of 6.6 and 13.3 mbar have been shown. The influence of N( 4 S) nitrogen atoms on secondary electron emission from the cathode (the SEE process) in late afterglow has been discussed. N( 4 S) atom concentration decay over relaxation time τ, N( 4 S)(τ), has been analysed by a numerical model and two analytical models. N( 4 S) decay analytical models are combined with different yield models that describe the SEE process by N( 4 S) and these combinations are employed to fit the experimental data. It has been shown that in late afterglow solving of very simple analytical equations instead of numerical solving of partial differential equations for N( 4 S)(τ) fitting can be used and that the combination of the first and the second order of the SEE process by N( 4 S) in yield modelling should be used in the case of 13.3 mbar pressure.

  8. Four-collector flux sensor

    International Nuclear Information System (INIS)

    Wiegand, W.J. Jr.; Bullis, R.H.; Mongeon, R.J.

    1980-01-01

    A flowmeter based on ion drift techniques was developed for measuring the rate of flow of a fluid through a given cross-section. Ion collectors are positioned on each side of an immediately adjacent to ion source. When air flows axially through the region in which ions are produced and appropriate electric fields are maintained between the collectors, an electric current flows to each collector due to the net motion of the ions. The electric currents and voltages and other parameters which define the flow are combined in an electric circuit so that the flux of the fluid can be determined. (DN)

  9. Ceramic accelerating tube of the improved construction

    International Nuclear Information System (INIS)

    Vasserman, S.B.; Kazarezov, I.V.; Pokhlebenin, E.I.; Shirokov, V.V.

    1976-01-01

    An improved ceramic accelerating tube is designed. The electrodes are made of copper and covar which provides for maintaining the geometry of the electrodes at thermal-compression welding and obviates the need for machanical treatment of the envelope after welding. Employment of the insulators with a finned surface from the vacuum side by two times increases the electric strength of the accelerating tube, as compared to the insulators with a smooth surface. The accelerating tube envelope can withstand the pulsed voltages of 1.5 MV at a pulse duration of 6 μs and a repetition rate of 100 Hz within two hours

  10. Interaction of p modes with a collection of thin magnetic tubes

    Science.gov (United States)

    Jain, R.; Gascoyne, A.; Hindman, B. W.

    2011-08-01

    We investigate the net effect of a multitude of thin magnetic tubes on the energy of ambient acoustic p modes. A p mode, when incident on a thin magnetic flux tube, excites magnetohydrodynamic (MHD) tube waves. These tube waves propagate vertically along the flux tube carrying away energy from the p-mode cavity resulting in the absorption of incident p-mode energy. We calculate the absorption arising from the excitation of sausage MHD waves within a collection of many non-interacting magnetic flux tubes with differing plasma properties. We find that the shape and magnitude of the absorption, when compared with the observationally measured absorption, favours a model with a maximum-flux boundary condition applied at the photosphere and a narrow distribution of plasma β in an ensemble with mean β value between 0.5 and 1.

  11. Boiling on a tube bundle: heat transfer, pressure drop and flow patterns

    International Nuclear Information System (INIS)

    Agostini, F.

    2008-07-01

    The complexity of the two-phase flow in a tube bundle presents important problems in the design and understanding of the physical phenomena taking place. The working conditions of an evaporator depend largely on the dynamics of the two-phase flow that in turn influence the heat exchange and the pressure drop of the system. A characterization of the flow dynamics, and possibly the identification of the flow pattern in the tube bundle, is thus expected to lead to a better understanding of the phenomena and to reveal on the mechanisms governing the tube bundle. Therefore, the present study aims at providing further insights into two-phase bundle flow through a new visualization system able to provide for the first time a view of the flow in the core of a tube bundle. In addition, the measurement of the light attenuation of a laser beam through the two-phase flow and measurement of the high frequency pressure fluctuations with a piezo-electric pressure transducer are used to characterize the flow. The design and the validation of this new instrumentation also provided a method for the detection of dry-out in tube bundles. This was achieved by a laser attenuation technique, flow visualization, and estimation of the power spectrum of the pressure fluctuation. The current investigation includes results for two different refrigerants, R134a and R236fa, three saturations temperatures T sat = 5, 10 and 15 °C, mass velocities ranging from 4 to 40 kg/sm² in adiabatic and diabatic conditions (several heat fluxes). Measurement of the local heat transfer coefficient and two-phase frictional pressure drop were obtained and utilized to improve the current prediction methods. The heat transfer and pressure drop data were supported by extensive characterization of the two-phase flow, which was to improve the understanding of the two-phase flow occurring in tube bundles. (author)

  12. Boiling on a tube bundle: heat transfer, pressure drop and flow patterns

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, F.

    2008-07-15

    The complexity of the two-phase flow in a tube bundle presents important problems in the design and understanding of the physical phenomena taking place. The working conditions of an evaporator depend largely on the dynamics of the two-phase flow that in turn influence the heat exchange and the pressure drop of the system. A characterization of the flow dynamics, and possibly the identification of the flow pattern in the tube bundle, is thus expected to lead to a better understanding of the phenomena and to reveal on the mechanisms governing the tube bundle. Therefore, the present study aims at providing further insights into two-phase bundle flow through a new visualization system able to provide for the first time a view of the flow in the core of a tube bundle. In addition, the measurement of the light attenuation of a laser beam through the two-phase flow and measurement of the high frequency pressure fluctuations with a piezo-electric pressure transducer are used to characterize the flow. The design and the validation of this new instrumentation also provided a method for the detection of dry-out in tube bundles. This was achieved by a laser attenuation technique, flow visualization, and estimation of the power spectrum of the pressure fluctuation. The current investigation includes results for two different refrigerants, R134a and R236fa, three saturations temperatures T{sub sat} = 5, 10 and 15 °C, mass velocities ranging from 4 to 40 kg/sm² in adiabatic and diabatic conditions (several heat fluxes). Measurement of the local heat transfer coefficient and two-phase frictional pressure drop were obtained and utilized to improve the current prediction methods. The heat transfer and pressure drop data were supported by extensive characterization of the two-phase flow, which was to improve the understanding of the two-phase flow occurring in tube bundles. (author)

  13. A scanning drift tube apparatus for spatiotemporal mapping of electron swarms

    Energy Technology Data Exchange (ETDEWEB)

    Korolov, I.; Vass, M.; Donkó, Z., E-mail: donko.zoltan@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Bastykova, N. Kh. [Institute of Experimental and Theoretical Physics, al-Farabi Kazakh National University, 96a Tole Bi, Almaty 050012 (Kazakhstan)

    2016-06-15

    A “scanning” drift tube apparatus, capable of mapping of the spatiotemporal evolution of electron swarms, developing between two plane electrodes under the effect of a homogeneous electric field, is presented. The electron swarms are initiated by photoelectron pulses and the temporal distributions of the electron flux are recorded while the electrode gap length (at a fixed electric field strength) is varied. Operation of the system is tested and verified with argon gas; the measured data are used for the evaluation of the electron bulk drift velocity. The experimental results for the space-time maps of the electron swarms — presented here for the first time — also allow clear observation of deviations from hydrodynamic transport. The swarm maps are also reproduced by particle simulations.

  14. Thermal and mechanical behavior of APWR-claddings under critical heat flux conditions

    International Nuclear Information System (INIS)

    Diegele, E.; Rust, K.

    1986-10-01

    Helical grid spacers, such as three or six helical fins as integral part of the claddings, are regarded as a more convenient design for the very tight lattice of an advanced pressurized water reactor (APWR) than grid spacers usually used. Furthermore, it is expected that this spacer design allows an increased safety margin against the critical heat flux (CHF), the knowledge of which is important for design, licensing, and operation of water cooled reactors. To address the distribution of the heat flux density at the outer circumference of the cladding geometry under investigation, the temperature fields in claddings without as well with fins were calculated taking into consideration nuclear and electrically heated rods. Besides the thermal behavior of the claddings, the magnitude and distribution of thermal stresses were determined additionally. A locally increased surface heat flux up to about 40 percent was calculated for the fin bases of nuclear as well as indirect electrically heated claddings with six such helical fins. For all investigated cases, the VON MISES stresses are clearly lower than 200 MPa, implying that no plastic deformations are to be expected. The aim of this theoretical analysis is to allow a qualitative assessment of the finned tube conception and to support experimental investigations concerning the critical heat flux. (orig.) [de

  15. Electrical Researches of Henry Cavendish

    Science.gov (United States)

    Clerk Maxwell, James; Cavendish, Henry

    2010-05-01

    Introduction; Account of Cavendish's writings on electricity; 1. First published papers on electricity; 2. Preliminary propositions; 3. Appendix; 4. Thoughts concerning electricity; 5. Account of the experiments; 6. Second published paper on electricity; 7. Experiments in 1771; 8. Experiments in 1772; 9. Index to electrical experiments, 1773; 10. Measures; 11. Experiments with the artificial torpedo; 12. Resistance to electricity; 13. Calibration of tubes; 14. Resistance of copper wire; 15. Result; 16. Results; Notes by the editor; Index.

  16. Thermodynamic analysis of a pulse tube engine

    International Nuclear Information System (INIS)

    Moldenhauer, Stefan; Thess, André; Holtmann, Christoph; Fernández-Aballí, Carlos

    2013-01-01

    Highlights: ► Numerical model of the pulse tube engine process. ► Proof that the heat transfer in the pulse tube is out of phase with the gas velocity. ► Proof that a free piston operation is possible. ► Clarifying the thermodynamic working principle of the pulse tube engine. ► Studying the influence of design parameters on the engine performance. - Abstract: The pulse tube engine is an innovative simple heat engine based on the pulse tube process used in cryogenic cooling applications. The working principle involves the conversion of applied heat energy into mechanical power, thereby enabling it to be used for electrical power generation. Furthermore, this device offers an opportunity for its wide use in energy harvesting and waste heat recovery. A numerical model has been developed to study the thermodynamic cycle and thereby help to design an experimental engine. Using the object-oriented modeling language Modelica, the engine was divided into components on which the conservation equations for mass, momentum and energy were applied. These components were linked via exchanged mass and enthalpy. The resulting differential equations for the thermodynamic properties were integrated numerically. The model was validated using the measured performance of a pulse tube engine. The transient behavior of the pulse tube engine’s underlying thermodynamic properties could be evaluated and studied under different operating conditions. The model was used to explore the pulse tube engine process and investigate the influence of design parameters.

  17. Heat transfer in laminar flow for a finned double - tube

    International Nuclear Information System (INIS)

    Colle, S.

    1977-01-01

    An analitical study of the steady-state heat transfer in laminar flow in finned double-tube heat exchangers is presented. The fins are plane, straight and continous, equally spaced and are fixed over the external surface of the inner tube. A constant peripheral temperature distribution is assumed to apply over the inner tube surface and each fin, and a constant peripheral heat flux is assumed to apply over the outer tube surface, while the overall heat flux is suposed to be uniform in the longitudinal direction of the duct. The prediction of the thermal performance of the finned double-tube is made by means of the relationship between the Nusselt number, the boundary conditions and the geometric characteristcs of the duct. (author) [pt

  18. Liquid crystal modified photonic crystal fiber (LC-PCF) fabricated with an un-cured SU-8 photoresist sealing technique for electrical flux measurement.

    Science.gov (United States)

    Kuo, Shu-Ming; Huang, Yu-Wen; Yeh, Szu-Ming; Cheng, Wood-Hi; Lin, Che-Hsin

    2011-09-12

    The optical transmission properties of photonic crystal fibers (PCFs) can be manipulated by modifying the pattern arrangement of the air channels within them. This paper presents a novel MEMS-based technique for modifying the optical transmission properties of commercial photonic-crystal fiber (PCF) by selectively filling the voids within the fiber structure with liquid crystals. In the proposed approach, an un-cured SU-8 ring pattern with a thickness of 5 μm is fabricated using a novel stamping method. The PCF is then brought into contact with the SU-8 pattern and an infra-red (IR) laser beam is passed through the fiber in order to soften the SU-8 surface; thereby selectively sealing some of the air channels with molten SU-8. Liquid crystals (LCs) are then infiltrated into the un-sealed holes in the PCF via capillary effects in order to modify the transmission properties of the PCF. Two selectively-filled PCFs are fabricated, namely an inner-ring LC-PCF and a single-line LC-PCF, respectively. It is shown that the two LC-PCFs exhibit significantly different optical behaviors. The practical applicability of the proposed selective-filling approach is demonstrated by fabricating an electric field sensor. The experimental results show that the sensor has the ability to measure electric fields with an intensity of up to 40 kV/cm.

  19. Numerical simulation and experimental results of horizontal tube falling film generator working in a NH3-LiNO3 absorption refrigeration system

    International Nuclear Information System (INIS)

    Herrera, J.V.; Garcia-Valladares, O.; Gomez, V.H.; Best, R.

    2010-01-01

    This paper describes the work made at the Centro de Investigacion en Energia in the development of an absorption refrigeration system for cooling and refrigeration applications with a capacity of 10 kW. The single effect unit utilizes ammonia-lithium nitrate as working pair and it is air cooled. The generator is a falling film type with horizontal tubes where the heating oil flows inside the tube bank and the ammonia-lithium nitrate solution flows as a falling film on the tube outside, where it is heated and ammonia vapor is generated. The generator consists of tree columns and four rows per column of horizontal tubes. The system was tested at controlled conditions with heating oil obtained from an electric resistance heating loop. A numerical model of the horizontal falling film generator was developed that divided the system into three different thermal elements: the flow inside the tube, the heat conduction in the tube wall and the falling film solution flow. The mathematical model was tested and validated with experimental data and a study of the influence of the heat transfer coefficient for ammonia-lithium nitrate solution in the numerical model was carried out. A comparison between experimental and numerical data for the heat flux in the system and the temperature profiles in the oil and solution flows shown a good degree of correlation.

  20. Tracheostomy tube - speaking

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000465.htm Tracheostomy tube - speaking To use the sharing features on ... are even speaking devices that can help you. Tracheostomy Tubes and Speaking Air passing through vocal cords ( ...

  1. X-ray tubes

    International Nuclear Information System (INIS)

    Young, R.W.

    1979-01-01

    A form of x-ray tube is described which provides satisfactory focussing of the electron beam when the beam extends for several feet from gun to target. Such a tube can be used for computerised tomographic scanning. (UK)

  2. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  3. Jejunostomy feeding tube

    Science.gov (United States)

    ... may replace the tube every now and then. Cleaning the Skin Around the J-tube To clean ... this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial ...

  4. Crystallography, magnetic susceptibility, heat capacity, and electrical resistivity of heavy-fermion LiV2O4 single crystals grown using a self-flux technique

    Science.gov (United States)

    Das, S.; Zong, X.; Niazi, A.; Ellern, A.; Yan, J. Q.; Johnston, D. C.

    2007-08-01

    Magnetically pure spinel compound LiV2O4 is a rare d -electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy-fermion behavior in the pure material. In addition, it is known that small concentrations (<1mol%) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report flux growth of LiV2O4 and preliminary measurements to help resolve these questions. The magnetic susceptibility of some as-grown crystals show a Curie-like upturn at low temperatures, showing the presence of magnetic defects within the spinel structure. The magnetic defects could be removed in some of the crystals by annealing them at 700°C . A very high specific heat coefficient γ=450mJ/molK2 was obtained at a temperature of 1.8K for a crystal containing a magnetic defect concentration ndefect=0.5mol% . A crystal with ndefect=0.01mol% showed a residual resistivity ratio of 50.

  5. Muon detector for the measurement of muon flux and lifetime of atmospheric muons

    International Nuclear Information System (INIS)

    Sidhu, Ragandeep Singh; Simrandeep Kaur; Bhatnagar, V.; Singh, J.B.

    2017-01-01

    For the present study, muon detector (consisting of four plastic scintillator paddles well equipped with DAQ) to i) measure the muon flux and ii) measure the lifetime of the atmospheric muons have been used. Measurement of lifetime of muons is a classic experiment to measure the time dilation in muons. The muon detector consisting of four scintillator paddles (forming a cuboidal geometry) is connected to PMT tubes from where we get an electrical signal whenever the muon passes. For the case of flux measurement, the coincidence signal is received from the upper and lower scintillator paddle. In the case of lifetime measurement, the muon of low energy decays into an electron (positron) and an antineutron (neutrino). The coincidence signal in this case is received from the top and the two side paddles. The major components of the muon detector are the part of Quark Net experiments developed by Fermilab which have been installed and setup at Panjab University

  6. Experimental Investigation of Average Heat-Transfer and Friction Coefficients for Air Flowing in Circular Tubes Having Square-Thread-Type Roughness

    Science.gov (United States)

    Sams, E. W.

    1952-01-01

    An investigation of forced-convection heat transfer and associated pressure drops was conducted with air flowing through electrically heated Inconel tubes having various degrees of square-thread-type roughness, an inside diameter of 1/2 inch, and a length of 24 inches. were obtained for tubes having conventional roughness ratios (height of thread/radius of tube) of 0 (smooth tube), 0.016, 0.025, and 0.037 over ranges of bulk Reynolds numbers up to 350,000, average inside-tube-wall temperatures up to 1950deg R, and heat-flux densities up to 115,000 Btu per hour per square foot. Data The experimental data showed that both heat transfer and friction increased with increase in surface roughness, becoming more pronounced with increase in Reynolds number; for a given roughness, both heat transfer and friction were also influenced by the tube wall-to-bulk temperature ratio. Good correlation of the heat-transfer data for all the tubes investigated was obtained by use of a modification of the conventional Nusselt correlation parameters wherein the mass velocity in the Reynolds number was replaced by the product of air density evaluated at the average film temperature and the so-called friction velocity; in addition, the physical properties of air were evaluated at the average film temperature. The isothermal friction data for the rough tubes, when plotted in the conventional manner, resulted in curves similar to those obtained by other investigators; that is, the curve for a given roughness breaks away from the Blasius line (representing turbulent flow in smooth tubes) at some value of Reynolds number, which decreases with increase in surface roughness, and then becomes a horizontal line (friction coefficient independent of Reynolds number). A comparison of the friction data for the rough tubes used herein indicated that the conventional roughness ratio is not an adequate measure of relative roughness for tubes having a square-thread-type element. The present data, as well

  7. Microwave discharges in capillary tubes

    International Nuclear Information System (INIS)

    Dervisevic, Emil

    1984-01-01

    This research thesis aims at being a contribution to the study of microwave discharge by a surface wave, and more precisely focusses on the discharge in capillary tubes filled with argon. The author first present theoretical models which describe, on the one hand, the propagation of the surface wave along the plasma column, and, on the other hand, longitudinal and radial profiles of the main discharge characteristics. The second part addresses the study of the influence of parameters (gas pressure and tube radius) on discharge operation and characteristics. Laws of similitude as well as empirical relationships between argon I and argon II emission line intensities, electron density, and electric field in the plasma have been established [fr

  8. Nasogastric and feeding tubes.

    Science.gov (United States)

    Gharib, Ahmed M; Stern, Eric J; Sherbin, Vandy L; Rohrmann, Charles A

    1996-05-01

    Preview The authors' experience in a radiology department suggested to them that there is a wide range of beliefs among practitioners regarding proper placement of nasogastric and feeding tubes. Improper positioning can cause serious problems, as they explain. Indications for different tube positions, complications of incorrect tube placement, and directions for proper positioning are discussed and illustrated.

  9. X-ray tube transformer

    International Nuclear Information System (INIS)

    1980-01-01

    An X-ray generator is described which comprises a transmission line transformer including an electrical conductor with a cavity and a second electrical conductor including helical windings disposed along a longitudinal axis within the cavity of the first conductor. The windings have a pitch which varies per unit length along the axis. There is dielectric material in the cavity for insulation and to couple electromagnetically the two conductors in response to an electric current flowing through the conductors, which have an impedance between them; this varies with distance along the axis of the helix of the second conductor. An X-ray tube is disposed along the longitudinal axis within the cavity, for radiating X-rays. The invention increases the voltage of applied voltage pulses at the remote tube-head with a transformer formed by using a spiral delay line geometry to give a tapered-impedance coaxial high voltage multiplier for pulse voltage operation. This transformer is smaller and lighter than previous designs for the same high peak voltage and power ratings. This is important because the penetration capabilities of Flash X-ray equipment increase with voltage, particularly in heavy materials such as steel. (U.K.)

  10. Electric Motor-Generator for a Hybrid Electric Vehicle

    OpenAIRE

    Odvářka, Erik; Mebarki, Abdeslam; Gerada, David; Brown, Neil; Ondrůšek, Čestmír

    2009-01-01

    Several topologies of electrical machines can be used to meet requirements for application in a hybrid electric vehicle. This paper describes process of an electric motor-generator selection, considering electromagnetic, thermal and basic control design. The requested electrical machine must develop 45 kW in continuous operation at 1300 rpm with field weakening capability up to 2500 rpm. Both radial and axial flux topologies are considered as potential candidates. A family of axial flux machi...

  11. Interplanetary dust fluxes, solar and galactic cosmic rays

    International Nuclear Information System (INIS)

    Bel'skij, S.A.

    1978-01-01

    The role of dust fluxes in cosmic ray (CR) propagation in the interplanetary space is investigated. Global effects arising in the interaction of CR with magnetic and electric fields of a sporadic meteor cloud or of all meteor fluxes as a whole are discussed. The local effects arising in the interaction of CR with magnetic and electric fields of separate meteor fluxes are also considered. It is shown that an increase in the CR intensity during the maximum activity of meteor fluxes confirms the supposition on the CR acceleration in electric fields of meteor fluxes

  12. Axial flux permanent magnet brushless machines

    CERN Document Server

    Gieras, Jacek F; Kamper, Maarten J

    2008-01-01

    Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators

  13. 21 CFR 868.5800 - Tracheostomy tube and tube cuff.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tracheostomy tube and tube cuff. 868.5800 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5800 Tracheostomy tube and tube cuff. (a) Identification. A tracheostomy tube and tube cuff is a device intended to be placed into a...

  14. A novel investigation of heat transfer characteristics in rifled tubes

    Science.gov (United States)

    Jegan, C. Dhayananth; Azhagesan, N.

    2017-12-01

    The experimental investigation of heat transfer of water flowing in a rifled tube was explored at different pressures and at various operating conditions in a rifled tube heat exchanger. The specifications for the inner and outer diameters of the inner tube are 25.8 and 50.6 mm, respectively. The working fluids used in shell side and tube side are cold and hot water. The rifled tube was made of the stainless steel with 4 ribs, 50.6 mm outer diameter, 0.775 mm rib height, 58o helix angle and the length 1500 mm. The effect of pressure, wall heat flux and friction factor were discussed. The results confirm that even at low pressures the rifled tubes has an obvious enhancement in heat transfer compared with smooth tube. Results depicts that the Nusselt number increases with Reynolds number and the friction factor decreases with increase in Reynolds number and the heat transfer rate is higher for the rifled tube when compared to smooth tube, because of strong swirl flow due to centrifugal action. It also confirms that, the friction factor obtained from the rifled tube is significantly higher than that of smooth tube.

  15. A novel investigation of heat transfer characteristics in rifled tubes

    Science.gov (United States)

    Jegan, C. Dhayananth; Azhagesan, N.

    2018-05-01

    The experimental investigation of heat transfer of water flowing in a rifled tube was explored at different pressures and at various operating conditions in a rifled tube heat exchanger. The specifications for the inner and outer diameters of the inner tube are 25.8 and 50.6 mm, respectively. The working fluids used in shell side and tube side are cold and hot water. The rifled tube was made of the stainless steel with 4 ribs, 50.6 mm outer diameter, 0.775 mm rib height, 58o helix angle and the length 1500 mm. The effect of pressure, wall heat flux and friction factor were discussed. The results confirm that even at low pressures the rifled tubes has an obvious enhancement in heat transfer compared with smooth tube. Results depicts that the Nusselt number increases with Reynolds number and the friction factor decreases with increase in Reynolds number and the heat transfer rate is higher for the rifled tube when compared to smooth tube, because of strong swirl flow due to centrifugal action. It also confirms that, the friction factor obtained from the rifled tube is significantly higher than that of smooth tube.

  16. The cracking of pressure tubes in the Pickering reactor

    International Nuclear Information System (INIS)

    Ross-Ross, P.A.

    1978-01-01

    Small cracks in 17 of the 390 pressure tubes in Unit 3 of the 2056 MW (electrical) Pickering Generating Station and of 52 tubes in Unit 4, resulted in each of these units being out of service for many months. The cracks originated at areas of extremely high residual tensile stress produced by improper positioning of the rolling tool used during construction to join the pressure tube to its end-fitting. The mechanism of failure was delayed hydrogen cracking. (author)

  17. Stabilization Strategies for Drift Tube Linacs

    CERN Document Server

    AUTHOR|(CDS)2085420; Lamehi Rashti, Mohammad

    The average axial electric fields in drift tube linac cavities are known to be sensitive with respect to the perturbation errors. Postcoupler is a powerful stabilizer devices that is used to reduce this sensitivity of average axial field. Postcouplers are the cylindrical rod which is extended from cavity wall toward the drift tube without touching the drift tube surface. Postcouplers need to be adjusted to the right length to stabilize the average axial field. Although postcouplers are used successfully in many projects, there is no straightforward procedure for postcouplers adjustment and it has been done almost based on trial and errors. In this thesis, the physics and characteristics of postcouplers has been studied by using an equivalent circuit model and 3D finite element method calculations. Finally, a straightforward and accurate method to adjust postcouplers has been concluded. The method has been verified by using experimental measurements on CERN Linac4 drift tube linac cavities.

  18. Critical flux determination by flux-stepping

    DEFF Research Database (Denmark)

    Beier, Søren; Jonsson, Gunnar Eigil

    2010-01-01

    In membrane filtration related scientific literature, often step-by-step determined critical fluxes are reported. Using a dynamic microfiltration device, it is shown that critical fluxes determined from two different flux-stepping methods are dependent upon operational parameters such as step......, such values are more or less useless in itself as critical flux predictors, and constant flux verification experiments have to be conducted to check if the determined critical fluxes call predict sustainable flux regimes. However, it is shown that using the step-by-step predicted critical fluxes as start...

  19. Eddy current technique applied to automated tube profilometry

    International Nuclear Information System (INIS)

    Dobbeni, D.; Melsen, C. van

    1982-01-01

    The use of eddy current methods in the first totally automated pre-service inspection of the internal diameter of PWR steam generator tubes is described. The technique was developed at Laborelec, the Belgian Laboratory of the Electricity Supply Industry. Details are given of the data acquisition system and of the automated manipulator. Representative tube profiles are illustrated. (U.K.)

  20. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... YouTube Videos >> NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration ... Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Embedded video for NEI YouTube Videos: ...

  1. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... YouTube Videos > NEI YouTube Videos: Amblyopia NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia ... of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Embedded video for NEI YouTube Videos: Amblyopia ...

  2. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... NEI YouTube Videos > NEI YouTube Videos: Amblyopia NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration ... Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Embedded video for NEI YouTube Videos: ...

  3. An Overview of Flux Pumps for HTS Coils

    OpenAIRE

    Coombs, Timothy Arthur; Geng, Jianzhao; Fu, L; Matsuda, K

    2016-01-01

    High-Tc superconducting (HTS) flux pumps are capable of injecting flux into closed HTS magnets without electrical contact. It is becoming a promising alternative of current source in powering HTS coils. This paper reviews the recent progress in flux pumps for HTS coil magnets. Different types of HTS flux pumps are introduced. The physics of these flux pumps are explained and comparisons are made. J. Geng would like to acknowledge Cambridge Trust for offering Cambridge International Scholar...

  4. Advanced pressure tube sampling tools

    International Nuclear Information System (INIS)

    Wittich, K.C.; King, J.M.

    2002-01-01

    Deuterium concentration is an important parameter that must be assessed to evaluate the Fitness for service of CANDU pressure tubes. In-reactor pressure tube sampling allows accurate deuterium concentration assessment to be made without the expenses associated with fuel channel removal. This technology, which AECL has developed over the past fifteen years, has become the standard method for deuterium concentration assessment. AECL is developing a multi-head tool that would reduce in-reactor handling overhead by allowing one tool to sequentially sample at all four axial pressure tube locations before removal from the reactor. Four sets of independent cutting heads, like those on the existing sampling tools, facilitate this incorporating proven technology demonstrated in over 1400 in-reactor samples taken to date. The multi-head tool is delivered by AECL's Advanced Delivery Machine or other similar delivery machines. Further, AECL has developed an automated sample handling system that receives and processes the tool once out of the reactor. This system retrieves samples from the tool, dries, weighs and places them in labelled vials which are then directed into shielded shipping flasks. The multi-head wet sampling tool and the automated sample handling system are based on proven technology and offer continued savings and dose reduction to utilities in a competitive electricity market. (author)

  5. Lunar Lava Tube Sensing

    Science.gov (United States)

    York, Cheryl Lynn; Walden, Bryce; Billings, Thomas L.; Reeder, P. Douglas

    1992-01-01

    Large (greater than 300 m diameter) lava tube caverns appear to exist on the Moon and could provide substantial safety and cost benefits for lunar bases. Over 40 m of basalt and regolith constitute the lava tube roof and would protect both construction and operations. Constant temperatures of -20 C reduce thermal stress on structures and machines. Base designs need not incorporate heavy shielding, so lightweight materials can be used and construction can be expedited. Identification and characterization of lava tube caverns can be incorporated into current precursor lunar mission plans. Some searches can even be done from Earth. Specific recommendations for lunar lava tube search and exploration are (1) an Earth-based radar interferometer, (2) an Earth-penetrating radar (EPR) orbiter, (3) kinetic penetrators for lunar lava tube confirmation, (4) a 'Moon Bat' hovering rocket vehicle, and (5) the use of other proposed landers and orbiters to help find lunar lava tubes.

  6. Steam generator tube performance

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1983-08-01

    A review of the performance of steam generator tubes in 110 water-cooled nuclear power reactors showed that tubes were plugged at 46 (42 percent) of the reactors. The number of tubes removed from service increased from 1900 (0.14 percent) in 1980 to 4692 (0.30 percent) in 1981. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that used all-volatile treatment since start-up. At one reactor a large number of degraded tubes were repaired by sleeving which is expected to become an important method of tube repair in the future

  7. Effect of heated length on the Critical Heat Flux of subcooled flow boiling. 2. Effective heated length under axially nonuniform heating condition

    International Nuclear Information System (INIS)

    Kinoshita, Hidetaka; Yoshida, Takuya; Nariai, Hideki; Inasaka, Fujio

    1998-01-01

    Effect of heated length on the Critical Heat Flux (CHF) of subcooled flow boiling with water was experimentally investigated by using direct current heated tube made of stainless steel a part of whose wall thickness was axially cut for realizing nonuniform heat flux condition. The higher enhancement of the CHF was derived for shorter tube length. The effective heated length was determined for the tube under axially nonuniform heat flux condition. When the lower heat flux part below the Net Vapor Generation (NVG) heat flux exists at the middle of tube length, then the effective heated length becomes the tube length downstream the lower heat flux parts. However, when the lower heat flux part is above the NVG, then the effective heated length is full tube length. (author)

  8. R245fa Flow Boiling inside a 4.2 mm ID Microfin Tube

    Science.gov (United States)

    Longo, G. A.; Mancin, S.; Righetti, G.; Zilio, C.

    2017-11-01

    This paper presents the R245fa flow boiling heat transfer and pressure drop measurements inside a mini microfin tube with internal diameter at the fin tip of 4.2 mm, having 40 fins, 0.15 mm high with a helix angle of 18°. The tube was brazed inside a copper plate and electrically heated from the bottom. Sixteen T-type thermocouples are located in the copper plate to monitor the wall temperature. The experimental measurements were carried out at constant mean saturation temperature of 30 °C, by varying the refrigerant mass velocity between 100 kg m-2 s-1 and 300 kg m-2 s-1, the vapour quality from 0.15 to 0.95, at two different heat fluxes: 30 and 60 kW m-2. The experimental results are presented in terms of two-phase heat transfer coefficient, onset dryout vapour quality, and frictional pressure drop. Moreover, the experimental measurements are compared against the most updated models for boiling heat transfer coefficient and frictional pressure drop estimations available in the open literature for microfin tubes.

  9. The Aphrodite boiling crisis program. Analysis of CHF tests performed on a vertical tube

    International Nuclear Information System (INIS)

    Souyri, A.; Conan, S.; Portesse, A.; Tremblay, D.

    1992-09-01

    In order to develop a comprehensive modelling of the boiling crisis phenomenon, the APHRODITE experimental program has been set up at ELECTRICITE DE FRANCE. Aiming at a better mechanistic understanding of this phenomenon, this program will investigate the influence of the experimental conditions (among which the mockup geometry and the boundary conditions) and the two-phase flow patterns via void fraction distributions. It has involved the construction of a R12 test loop, which can deliver a large thermal-hydraulic parameter ranges, and the development of a gamma-ray tomograph. The first experiments have been carried out on a vertical Inconel tube, 6 meters long with a bore diameter of 13 mm and a thickness of 0.5 mm. This electrically heated test section is heavily instrumented with 168 thermocouples welded along the tube, on its outer surface. After a refined calibration of the experimental procedure, a critical heat flux data bank has been collected within large pressure, mass velocity and critical steam quality ranges. These results are firstly compared with other CHF data obtained in similar conditions. Then several empirical correlations and a theoretical model for similar prediction in tubes are tested against these data

  10. Electrical modeling of X-Ray tubes used in fluoroscopy systems with the objective of minimizing radiation transmitted to patients; Modelagem eletrica dos tubos de raios-X utilizados em sistemas de fluoroscopia com o objetivo de minimizar a radiacao transmitida ao paciente

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Raghunatha Faria; Oliveira, Bruno Andrade de; Souza, Euzebio de, E-mail: raghunathafaria@gmail.com, E-mail: brunodoliver90@hotmail.com, E-mail: euzebio.souza@prof.unibh.br [Centro Universitario de Belo Horizonte (UniBH), Belo Horizonte, MG (Brazil)

    2017-09-01

    The purpose of this article was to demonstrate the processes and parameters that are necessary for the operation of all X-rays in the use in fluoroscopy technique, the constructive part of the High Voltage Generator and the X-ray tube and how the X-ray release occurs to the patient during the examination, the condition of how the current and potential difference generates the X-rays incident to the patient during the procedure and what unnecessary exposure to such rays may be detrimental in amounts that do not add an image to the examination. In this way, a proposal was made for the electric modeling of an X-ray tube, in which it addressed an alternative to minimize the radiation that passes through the patient without generating useful images. (author)

  11. Manual tube welding torch

    International Nuclear Information System (INIS)

    Kiefer, J.H.; Smith, D.J.

    1981-01-01

    In a welding torch which fits over a tube intermediate the ends thereof for welding the juncture between the tube and a boss on the back side of a tube plate, a split housing encloses a tungsten electrode, a filler wire duct and a fiber optic bundle arranged to observe the welding process. A shielding gas duct is provided in the housing. A screw is provided for setting electrode/work distance. Difficult remote tube welding operations can be performed with the apparatus. (author)

  12. Steam generator tube performance

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1984-10-01

    A review of the performance of steam generator tubes in 116 water-cooled nuclear power reactors showed that tubes were plugged at 54 (46 percent) of the reactors. The number of tubes removed from service decreased from 4 692 (0.30 percent) in 1981 to 3 222 (0.20 percent) in 1982. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that have used only volatile treatment, with or without condensate demineralization

  13. Wound tube heat exchanger

    Science.gov (United States)

    Ecker, Amir L.

    1983-01-01

    What is disclosed is a wound tube heat exchanger in which a plurality of tubes having flattened areas are held contiguous adjacent flattened areas of tubes by a plurality of windings to give a double walled heat exchanger. The plurality of windings serve as a plurality of effective force vectors holding the conduits contiguous heat conducting walls of another conduit and result in highly efficient heat transfer. The resulting heat exchange bundle is economical and can be coiled into the desired shape. Also disclosed are specific embodiments such as the one in which the tubes are expanded against their windings after being coiled to insure highly efficient heat transfer.

  14. Sapphire tube pressure vessel

    Science.gov (United States)

    Outwater, John O.

    2000-01-01

    A pressure vessel is provided for observing corrosive fluids at high temperatures and pressures. A transparent Teflon bag contains the corrosive fluid and provides an inert barrier. The Teflon bag is placed within a sapphire tube, which forms a pressure boundary. The tube is received within a pipe including a viewing window. The combination of the Teflon bag, sapphire tube and pipe provides a strong and inert pressure vessel. In an alternative embodiment, tie rods connect together compression fittings at opposite ends of the sapphire tube.

  15. Fuel nozzle tube retention

    Energy Technology Data Exchange (ETDEWEB)

    Cihlar, David William; Melton, Patrick Benedict

    2017-02-28

    A system for retaining a fuel nozzle premix tube includes a retention plate and a premix tube which extends downstream from an outlet of a premix passage defined along an aft side of a fuel plenum body. The premix tube includes an inlet end and a spring support feature which is disposed proximate to the inlet end. The premix tube extends through the retention plate. The spring retention feature is disposed between an aft side of the fuel plenum and the retention plate. The system further includes a spring which extends between the spring retention feature and the retention plate.

  16. Rotating flux compressor for energy conversion

    International Nuclear Information System (INIS)

    Chowdhuri, P.; Linton, T.W.; Phillips, J.A.

    1983-01-01

    The rotating flux compressor (RFC) converts rotational kinetic energy into an electrical output pulse which would have higher energy than the electrical energy initially stored in the compressor. An RFC has been designed in which wedge-shaped rotor blades pass through the air gaps between successive turns of a solenoid, the stator. Magnetic flux is generated by pulsing the stator solenoids when the inductance is a maximum, i.e., when the flux fills the stator-solenoid volume. Connecting the solenoid across a load conserves the flux which is compressed within the small volume surrounding the stator periphery when the rotor blades cut into the free space between the stator plates, creating a minimum-inductance condition. The unique features of this design are: (1) no electrical connections (brushes) to the rotor; (2) no conventional windings; and (3) no maintenance. The device has been tested up to 5000 rpm of rotor speed

  17. Stability of a laminar flame front propagating within a tube

    Energy Technology Data Exchange (ETDEWEB)

    Salamandra, G.D.; Maiorov, N.I.

    1983-01-01

    This study examines the deformation of a flame propagating in a semi-closed horizontal tube under the action of perturbations artifically created on the flame surface by brief action of a transverse electrical field on the combustion zone. The experiments were performed in a tube with square section 36 x 36 mm, with electrodes on the upper and lower walls for application of an electric field to the combustion zone. A high negative voltage was applied to the upper electrode for a regulated time interval, with the lower electrode grounded. Concludes that development of artificially created perturbations on the surface of a flame propagating in a semiclosed horizontal tube has been observed; the magnitude of the perturbations increases by an exponential law; fine scale perturbations on the flame surface are suppressed by coarse scale perturbations; and the stable curved form of the flame front in the tube is ensured by the stabilizing action of the tube walls.

  18. Steam generator tube failures

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

  19. Steam generator tube failures

    International Nuclear Information System (INIS)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service

  20. Chest Tube Thoracostomy

    Science.gov (United States)

    ... in the space around the lungs (called a pleural effusion) . A chest tube may also be needed when a patient has ... or chest CT are also done to evaluate pleural fluid. If the X-ray shows a need for a chest tube to drain fluid or air, the procedure is ...

  1. Ventricular tachycardia following tube thoracotomy.

    Science.gov (United States)

    Hibbert, Benjamin; Lim, Toon Wei; Hibbert, Rebecca; Green, Martin; Gollob, Michael H; Davis, Darryl R

    2010-10-01

    Arrhythmias provoked by tube thoracotomy are a rare complication. We report a ventricular tachycardia after chest tube insertion for a device-related pneumothorax. Sinus rhythm was restored only by removal of the chest tube and insertion of a pliable pleural drain. Identification of the chest tube as an arrhythmic trigger following tube thoracotomy is essential in definitive management of refractory arrhythmias.

  2. Advanced Ultrasupercritical (AUSC) Tube Membrane Panel Development

    Energy Technology Data Exchange (ETDEWEB)

    Pschirer, James [Alstom Power Inc., Windsor, CT (United States); Burgess, Joshua [Alstom Power Inc., Windsor, CT (United States); Schrecengost, Robert [Alstom Power Inc., Windsor, CT (United States)

    2017-08-16

    Alstom Power Inc., a wholly owned subsidiary of the General Electric Company (GE), has completed the project “Advanced Ultrasupercritical (AUSC) Tube Membrane Panel Development” under U.S. Department of Energy (DOE) Award Number DE-FE0024076. This project was part of DOE’s Novel Crosscutting Research and Development to Support Advanced Energy Systems program. AUSC Tube Membrane Panel Development was a two and one half year project to develop and verify the manufacturability and serviceability of welded tube membrane panels made from high performance materials suitable for the AUSC steam cycles, defined as high pressure steam turbine inlet conditions of 700-760°C (1292-1400°F) and 24.5-35MPa (3500-5000psi). The difficulty of this challenge lies in the fact that the membrane-welded construction imposes demands on the materials that are unlike any that exist in other parts of the boiler. Tube membrane panels have been designed, fabricated, and installed in boilers for over 50 years with relatively favorable experience when fabricated from carbon and Cr-Mo low alloy steels. The AUSC steam cycle requires membrane tube panels fabricated from materials that have not been used in a weldment with metal temperatures in the range of 582-610°C (1080-1130°F). Fabrication materials chosen for the tubing were Grade 92 and HR6W. Grade 92 is a creep strength enhanced ferritic Cr-Mo alloy and HR6W is a high nickel alloy. Once the materials were chosen, GE performed the engineering design of the panels, prepared shop manufacturing drawings, and developed manufacturing and inspection plans. After the materials were purchased, GE manufactured and inspected the tube membrane panels, determined if post fabrication heat treatment of the tube membrane panels was needed, performed pre- and post-weld heat treatment on the Grade 92 panels, conducted final nondestructive inspection of any heat treated tube membrane panels, conducted destructive inspection of the completed tube

  3. Molybdenum Tube Characterization report

    Energy Technology Data Exchange (ETDEWEB)

    Beaux II, Miles Frank [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Usov, Igor Olegovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-07

    Chemical vapor deposition (CVD) techniques have been utilized to produce free-standing molybdenum tubes with the end goal of nuclear fuel clad applications. In order to produce tubes with properties desirable for this application, deposition rates were lowered requiring long deposition durations on the order of 50 hours. Standard CVD methods as well as fluidized-bed CVD (FBCVD) methods were applied towards these objectives. Characterization of the tubes produced in this manner revealed material suitable for fuel clad applications, but lacking necessary uniformity across the length of the tubes. The production of freestanding Mo tubes that possess the desired properties across their entire length represents an engineering challenge that can be overcome in a next iteration of the deposition system.

  4. Categorising YouTube

    DEFF Research Database (Denmark)

    Simonsen, Thomas Mosebo

    2011-01-01

    This article provides a genre analytical approach to creating a typology of the User Generated Content (UGC) of YouTube. The article investigates the construction of navigation processes on the YouTube website. It suggests a pragmatic genre approach that is expanded through a focus on YouTube’s...... technological affordances. Through an analysis of the different pragmatic contexts of YouTube, it is argued that a taxonomic understanding of YouTube must be analysed in regards to the vacillation of a user-driven bottom-up folksonomy and a hierarchical browsing system that emphasises a culture of competition...... and which favours the already popular content of YouTube. With this taxonomic approach, the UGC videos are registered and analysed in terms of empirically based observations. The article identifies various UGC categories and their principal characteristics. Furthermore, general tendencies of the UGC within...

  5. CFD simulations of heat transfer in internally helically ribbed tubes

    Directory of Open Access Journals (Sweden)

    Majewski Karol

    2016-06-01

    Full Text Available Heating surfaces in power boilers are exposed to very high heat flux. For evaporator protection against overheating, internally helically ribbed tubes are used. The intensification of the heat transfer and the maintenance of the thin water layer in the intercostal space, using ribbed tubes, enables better protection of the power boiler evaporator than smooth pipes. Extended inner surface changes flow and thermal conditions by influencing the linear pressure drop and heat transfer coefficient. This paper presents equations that are used to determine the heat transfer coefficient. The results of total heat transfer, obtained from CFD simulations, for two types of internally ribbed and plain tubes are also presented.

  6. Neutron noise to detect BWR-4 in-core instrument tube vibrations and impacting

    International Nuclear Information System (INIS)

    Fry, D.N.; Kryter, R.C.; Mathis, M.V.; Mott, J.E.; Robinson, J.C.

    1979-01-01

    Noise analysis was used to investigate in-core instrument tube vibrations in boiling water reactor-4 (BWR-4)-type reactors. Neutron noise signals from in-core fission chambers and acoustic noise signals from externally mounted accelerometers were used in these studies. The results show that neutron noise can be used to detect vibration and, more important, impacting of instrument tubes against adjacent fuel channel boxes. Externally mounted accelerometers detect impacting but not rubbing of instrument tubes against fuel channel boxes. Accelerometers can monitor impacting only on the particular instrument tube where the accelerometer is mounted. Surveillance for instrument tube impacts can be accomplished using standard BWR-4 in-core power range neutron flux detectors at all instrument tube locations containing these detectors. Ex-vessel accelerometers can then be used to monitor instrument tubes that lack power range neutron flux detectors. However, noise on axial flux profiles obtained with movable in-core detectors is not a reliable indicator of impacting because the recorder used to plot the flux profiles does not respond adequately to the noise frequency generated by impacting. Neutron noise signatures show that modification of the bypass cooling by plugging preexisting holes and drilling new holes in the fuel assembly lower tie plate greatly reduces instrument tube vibration and eliminates impacting of instrument tubes against fuel boxes

  7. CHF prediction in rod bundles using round tube data

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Wallen F.; Veloso, Maria A.F.; Pereira, Cláubia; Costa, Antonella L., E-mail: wallenfds@yahoo.com.br, E-mail: mdora@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-07-01

    The present work concerns the use of 1995 CHF table for uniformly heated round tubes, developed jointly by Canadian and Russian researchers, for the prediction of critical heat fluxes in rod bundles geometries. Comparisons between measured and calculated critical heat fluxes indicate that this table could be applied to rod bundles provided that a suitable correction factor is employed. The tolerance limits associated with the departure from nucleate boiling ratio (DNBR) are evaluated by using statistical analysis. (author)

  8. A model for correlating burnout in round tubes

    International Nuclear Information System (INIS)

    Kirby, G.J.

    1966-09-01

    A model is presented which represents the film flow rate in the climbing film regime of boiling two phase flow. By calculating the dryout point burnout heat fluxes for round tubes both uniformly and non-uniformly heated axially have been predicted with accuracies as good as the best empirical correlations. The model is used to investigate the effect of varying flux profile as well as the other system describing parameters. (author)

  9. Boiling on a tube bundle: heat transfer, pressure drop and flow patterns

    International Nuclear Information System (INIS)

    Royen Van, E.

    2011-11-01

    The complexity of two-phase flow boiling on a tube bundle presents many challenges to the understanding of the physical phenomena taking place. It is important to quantify these numerous heat flow mechanisms in order to better describe the performance of tube bundles as a function of the operational conditions. In the present study, the bundle boiling facility at the Laboratory of Heat and Mass Transfer (LTCM) was modified to obtain high-speed videos to characterise the two-phase regimes and some bubble dynamics of the boiling process. It was then used to measure heat transfer on single tubes and in bundle boiling conditions. Pressure drop measurements were also made during adiabatic and diabatic bundle conditions. New enhanced boiling tubes from Wolverine Tube Inc. (Turbo-B5) and the Wieland-Werke AG (Gewa-B5) were investigated using R134a and R236fa as test fluids. The tests were carried out at saturation temperatures T sat of 5 °C and 15 °C, mass flow rates from 4 to 35 kg/m 2 s and heat fluxes from 15 to 70 kW/m 2 , typical of actual operating conditions. The flow pattern investigation was conducted using visual observations from a borescope inserted in the middle of the bundle. Measurements of the light attenuation of a laser beam through the intertube two-phase flow and local pressure fluctuations with piezo-electric pressure transducers were also taken to further help in characterising the complex flow. Pressure drop measurements and data reduction procedures were revised and used to develop new, improved frictional pressure drop prediction methods for adiabatic and diabatic two-phase conditions. The physical phenomena governing the enhanced tube evaporation process and their effects on the performance of tube bundles were investigated and insight gained. A new method based on a theoretical analysis of thin film evaporation was used to propose a new correlating parameter. A large new database of local heat transfer coefficients were obtained and then

  10. Electric machines with axial magnetic flux

    Science.gov (United States)

    Nuca, I.; Ambros, T.; Burduniuc, M.; Deaconu, S. I.; Turcanu, A.

    2018-01-01

    The paper contains information on the performance of axial machines compared to cylindrical ones. At the same time, various constructive schemes of synchronous electromechanical converters with permanent magnets and asynchronous with short-circuited rotor are presented. In the developed constructions, the aim is to maximize the usage of the material of the stator windings. The design elements of the axial machine magnetic system are presented. The FEMM application depicted the array of the magnetic field of an axial machine.

  11. String/flux tube duality on the light cone

    International Nuclear Information System (INIS)

    Brower, Richard C.; Tan, C.-I; Thorn, Charles B.

    2006-01-01

    The equivalence of quantum field theory and string theory as exemplified by the AdS/CFT correspondence is explored from the point of view of light cone quantization. On the string side we discuss the light cone version of the static string connecting a heavy external quark source to a heavy external antiquark source, together with small oscillations about the static string configuration. On the field theory side we analyze the weak/strong coupling transition in a ladder diagram model of the quark-antiquark system, also from the point of view of the light cone. Our results are completely consistent with those obtained by more standard covariant methods in the limit of infinitely massive quarks

  12. Properties of Flux Tubes and the Relation with Solar Irradiance ...

    Indian Academy of Sciences (India)

    tribpo

    Temporal evolution of the emergent radiation of a vertical cut through the solar atmosphere using a 2D MHD model of the solar granulation (Gadun et al. 2000). The x axis covers roughly 4 Mm. As expected, these simulations show an increased contrast in the core of a spectral line (right panel) compared to the continuum ...

  13. Dynamical Processes in Flux Tubes and their Role in ...

    Indian Academy of Sciences (India)

    tribpo

    , Vol. 263. (ed.) Rutten, R. J. and Severino, G. (Kluwer: Acad. Publ.), p. 453. Nördlund, Ä., Brandenburg, Α., Jennings, R. L., Rieutord, M., Ruokainen, J., Stein, R. F.,. Tuominen, I. 1992, Astrophys. J., 392, 647. Spruit, Η. C. 1981, Astr. Astrophys., ...

  14. A Laboratory Astrophysical Jet to Study Canonical Flux Tubes

    Energy Technology Data Exchange (ETDEWEB)

    You, Setthivoine [Univ. of Washington, Seattle, WA (United States)

    2017-12-20

    Understanding the interaction between plasma flows and magnetic fields remains a fundamental problem in plasma physics, with important applications to astrophysics, fusion energy, and advanced space propulsion. For example, flows are of primary importance in astrophysical jets even if it is not fully understood how jets become so long without becoming unstable. Theories for the origin of magnetic fields in the cosmos rely on flowing charged fluids that should generate magnetic fields, yet this remains to be demonstrated experimentally. Fusion energy reactors can be made smaller with flows that improve stability and confinement. Advanced space propulsion could be more efficient with collimated and stable plasma flows through magnetic nozzles but must eventually detach from the nozzle. In all these cases, there appears to be a spontaneous emergence of flowing and/or magnetic structures, suggesting a form of self-organization in plasmas. Beyond satisfying simple intellectual curiosity, understanding plasma self-organization could enable the development of methods to control plasma structures for fusion energy, space propulsion, and other applications. The research project has therefore built a theory and an experiment to investigate the interaction between magnetic fields and plasma flows. The theory is called canonical field theory for short, and the experiment is called Mochi after a rice cake filled with surprising, yet delicious fillings.

  15. Dynamical Processes in Flux Tubes and their Role in ...

    Indian Academy of Sciences (India)

    Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately.

  16. Unsteady two dimensional multiphysical simulation on the radiating calandria tube under the subcooling boundary condition

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Se Myong [Kunsan National Univ., Kunsan (Korea, Republic of); Kim, Hyoung Tae [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Inside the Calandria tubes in the moderator system of a heavy water reactor, there are pressure tubes undergoing high pressure and temperature. If the cooling water dries out due to the local film boiling at the outer tube boundary, the excessive heat flux can deform the pressure tube to even contact with outer Calandria tube. To limit the subcooling for the avoidance of dryout condition in a CANDU reactor, a suitable experiment should be proposed such as Ref.. In this study, we simulated this experiment in 2 D with COMSOL Multi physics.

  17. Electrical and electronic principles

    CERN Document Server

    Knight, S A

    1991-01-01

    Electrical and Electronic Principles, 2, Second Edition covers the syllabus requirements of BTEC Unit U86/329, including the principles of control systems and elements of data transmission. The book first tackles series and parallel circuits, electrical networks, and capacitors and capacitance. Discussions focus on flux density, electric force, permittivity, Kirchhoff's laws, superposition theorem, arrangement of resistors, internal resistance, and powers in a circuit. The text then takes a look at capacitors in circuit, magnetism and magnetization, electromagnetic induction, and alternating v

  18. Isolated Fallopian Tube Torsion

    Directory of Open Access Journals (Sweden)

    S. Kardakis

    2013-01-01

    Full Text Available Isolated torsion of the Fallopian tube is a rare gynecological cause of acute lower abdominal pain, and diagnosis is difficult. There are no pathognomonic symptoms; clinical, imaging, or laboratory findings. A preoperative ultrasound showing tubular adnexal masses of heterogeneous echogenicity with cystic component is often present. Diagnosis can rarely be made before operation, and laparoscopy is necessary to establish the diagnosis. Unfortunately, surgery often is performed too late for tube conservation. Isolated Fallopian tube torsion should be suspected in case of acute pelvic pain, and prompt intervention is necessary.

  19. Automation in tube finishing bay

    International Nuclear Information System (INIS)

    Bhatnagar, Prateek; Satyadev, B.; Raghuraman, S.; Syama Sundara Rao, B.

    1997-01-01

    Automation concept in tube finishing bay, introduced after the final pass annealing of PHWR tubes resulted in integration of number of sub-systems in synchronisation with each other to produce final cut fuel tubes of specified length, tube finish etc. The tube finishing bay which was physically segregated into four distinct areas: 1. tube spreader and stacking area, 2. I.D. sand blasting area, 3. end conditioning, wad blowing, end capping and O.D. wet grinding area, 4. tube inspection, tube cutting and stacking area has been studied

  20. Method of specifying and verifying the characteristics of rotating anode X-ray tubes and X-ray tube assemblies used in medical diagnosis

    International Nuclear Information System (INIS)

    1981-01-01

    Under the direction of the Light Electrical Engineering Standards Committee, a British Standard method has been prepared for specifying and verifying the electrical, thermal and loading characteristics of rotating anode X-ray tubes and X-ray tube assemblies used in medical diagnosis. This standard is intended to provide a common basis for the indication of data of rotating anode X-ray tubes and X-ray tube assemblies and to facilitate the application of radiographic ratings by the user, basing these on standardized conditions as given in the accompanying documents. (U.K.)

  1. X-ray tube

    International Nuclear Information System (INIS)

    Webley, R.S.

    1975-01-01

    The object of the invention described is to provide an X-ray tube providing a scanned X-ray output which does not require a scanned electron beam. This is obtained by an X-ray tube including an anode which is rotatable about an axis, and a source of a beam of energy, for example an electron beam, arranged to impinge on a surface of the anode to generate X-radiation substantially at the region of incidence on the anode surface. The anode is rotatable about the axis to move the region of incidence over the surface. The anode is so shaped that the rotation causes the region of incidence to move in a predetermined manner relative to fixed parts of the tube so that the generated X-radiation is scanned in a predetermined manner relative to the tube. (UK)

  2. Tube Alinement for Machining

    Science.gov (United States)

    Garcia, J.

    1984-01-01

    Tool with stepped shoulders alines tubes for machining in preparation for welding. Alinement with machine tool axis accurate to within 5 mils (0.13mm) and completed much faster than visual setup by machinist.

  3. Steam generator tube performance

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1982-04-01

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1980. Tube defects occurred at 38% of the 97 reactors surveyed. This is a marginal improvement over 1979 when defects occurred at 41% of the reactors. The number of failed tubes was also lower, 0.14% of the tubes in service in 1980 compared with 0.20% of those in service in 1979. Analysis of the causes of these failures indicates that stress corrosion cracking was the leading failure mechanism. Reactors that used all-volatile treatment of secondary water, with or without full-flow condensate demineralization since start-up showed the lowest incidence of corrosion-related defects

  4. Ear tube insertion

    Science.gov (United States)

    ... mastoiditis) or the brain, or that damages nearby nerves Injury to the ear after sudden changes in ... does not heal after the tube falls out. Most of the time, these problems DO NOT last long. They also ...

  5. Tube Feeding Troubleshooting Guide

    Science.gov (United States)

    ... the diameter is measured in units known as French sizes, or “Fr”; a low profile tube also ... your quality of life. You are encouraged to speak with your physician, dietitian, home care company, or ...

  6. Growth of zircaloy 4 under neutron flux

    International Nuclear Information System (INIS)

    Morize, P.; Baicry, J.; Morlot, G.; Sciers, P.; Lehmann, D.

    1982-06-01

    Between 300 and 385 0 C, and under neutron fluxes between 0.5 and 2.10 14 n/cm 2 /s, the growth of zircaloy tubes is nil in the plane perpendicular to the axis, and can be represented by the equation: Δl/l=4.6610 -14 (phit)sup(0.49) in the axial direction. In the area investigated, neither the irradiation temperature nor the instantaneous flux has any effect on the metallurgical state (relieved or recrystallized) [fr

  7. Magnesium tube hydroforming

    Energy Technology Data Exchange (ETDEWEB)

    Liewald, M.; Pop, R. [Institute for Metal Forming Technology (IFU), Stuttgart (Germany)

    2008-04-15

    Magnesium alloys reveal a good strength-to-weight ratio in the family of lightweight metals and gains potential to provide up to 30% mass savings compared to aluminium and up to 75 % compared to steel. The use of sheet magnesium alloys for auto body applications is however limited due to the relatively low formability at room temperature. Within the scope of this paper, extruded magnesium tubes, which are suitable for hydroforming applications, have been investigated. Results obtained at room temperature using magnesium AZ31 tubes show that circumferential strains are limited to a maximal value of 4%. In order to examine the influence of the forming temperature on tube formability, investigations have been carried out with a new die set for hot internal high pressure (IHP) forming at temperatures up to 400 C. Earlier investigations with magnesium AZ31 tubes have shown that fractures occur along the welding line at tubes extruded over a spider die, whereby a non-uniform expansion at bursting with an elongation value of 24% can be observed. A maximum circumferential strain of approx. 60% could be attained when seamless, mechanically pre-expanded and annealed tubes of the same alloy have been used. The effect of annealing time on materials forming properties shows a fine grained structure for sufficient annealing times as well as deterioration with a large increase at same time. Hence, seamless ZM21 tubes have been used in the current investigations. With these tubes, an increased tensile fracture strain of 116% at 350 C is observed as against 19% at 20 C, obtained by tensile testing of milled specimens from the extruded tubes. This behaviour is also seen under the condition of tool contact during the IHP forming process. To determine the maximum circumferential strain at different forming temperatures and strain rates, the tubes are initially bulged in a die with square cross-section under plane stress conditions. Thereafter, the tubes are calibrated by using an

  8. Power vacuum tubes handbook

    CERN Document Server

    Whitaker, Jerry

    2012-01-01

    Providing examples of applications, Power Vacuum Tubes Handbook, Third Edition examines the underlying technology of each type of power vacuum tube device in common use today. The author presents basic principles, reports on new development efforts, and discusses implementation and maintenance considerations. Supporting mathematical equations and extensive technical illustrations and schematic diagrams help readers understand the material. Translate Principles into Specific Applications This one-stop reference is a hands-on guide for engineering personnel involved in the design, specification,

  9. Evolution of magnetic flux ropes associated with flux transfer events and interplanetary magnetic clouds

    International Nuclear Information System (INIS)

    Wei, C.Q.; Lee, L.C.; Wang, S.; Akasofu, S.I.

    1991-01-01

    Spacecraft observations suggest that flux transfer events and interplanetary magnetic clouds may be associated with magnetic flux ropes which are magnetic flux tubes containing helical magnetic field lines. In the magnetic flux ropes, the azimuthal magnetic field (B θ ) is superposed on the axial field (B z ). In this paper the time evolution of a localized magnetic flux rope is studied. A two-dimensional compressible magnetohydrodynamic simulation code with a cylindrical symmetry is developed to study the wave modes associated with the evolution of flux ropes. It is found that in the initial phase both the fast magnetosonic wave and the Alfven wave are developed in the flux rope. After this initial phase, the Alfven wave becomes the dominant wave mode for the evolution of the magnetic flux rope and the radial expansion velocity of the flux rope is found to be negligible. Numerical results further show that even for a large initial azimuthal component of the magnetic field (B θ ≅ 1-4 B z ) the propagation velocity along the axial direction of the flux rope remains to be the Alfven velocity. Diagnoses show that after the initial phase the transverse kinetic energy equals the transverse magnetic energy, which is characteristic of the Alfven mode. It is also found that the localized magnetic flux rope tends to evolve into two separate magnetic ropes propagating in opposite directions. The simulation results are used to study the evolution of magnetic flux ropes associated with flux transfer events observed at the Earth's dayside magnetopause and magnetic clouds in the interplanetary space

  10. Dynamics of tubes in fluid with tube-baffle interaction

    International Nuclear Information System (INIS)

    Chen, S.S.; Jendrzejczyk, J.A.; Wambsganss, M.W.

    1983-09-01

    Three series of tests are performed to evaluate the effects of tube to tube-support-plate (TSP) clearance on tube dynamic characteristics and instability phenomena for tube arrays in crossflow. Test results show that, for relatively large clearances, tubes may possess TSP-inactive modes in which the tubes rattle inside some of the tube-support-plate holes, and that the natural frequencies of TSP-inactive modes are lower than those of TSP-active modes, in which the support plates provide knife-edge type support. Tube response characteristics associated with TSP-inactive modes are sensitive to tube-to-TSP clearance, TSP thickness, excitation amplitude, tube alignment, and the fluid inside the clearance. In addition, tube response is intrinsically nonlinear, with the dominance of TSP-inactive or TSP-active modes depending on the magnitudes of different system parameters. In general, such a system is difficult to model; only a full-scale test can provide all the necessary characteristics. A tube array supported by TSPs with relatively large clearances may be subjected to dynamic instability in some of the TSP-inactive modes; tube response characteristics and impact forces on TSPs for a tube row are studied in detail in this report. Tube displacements associated with the instability of a TSP-inactive mode are small; however, impacts of the tube against TSPs may result in significant damage in a relatively short time. 52 figures

  11. Electroacoustic control of Rijke tube instability

    Science.gov (United States)

    Zhang, Yumin; Huang, Lixi

    2017-11-01

    Unsteady heat release coupled with pressure fluctuation triggers the thermoacoustic instability which may damage a combustion chamber severely. This study demonstrates an electroacoustic control approach of suppressing the thermoacoustic instability in a Rijke tube by altering the wall boundary condition. An electrically shunted loudspeaker driver device is connected as a side-branch to the main tube via a small aperture. Tests in an impedance tube show that this device has sound absorption coefficient up to 40% under normal incidence from 100 Hz to 400 Hz, namely over two octaves. Experimental result demonstrates that such a broadband acoustic performance can effectively eliminate the Rijke-tube instability from 94 Hz to 378 Hz (when the tube length varies from 1.8 m to 0.9 m, the first mode frequency for the former is 94 Hz and the second mode frequency for the latter is 378 Hz). Theoretical investigation reveals that the devices act as a damper draining out sound energy through a tiny hole to eliminate the instability. Finally, it is also estimated based on the experimental data that small amount of sound energy is actually absorbed when the system undergoes a transition from the unstable to stable state if the contrpaol is activated. When the system is actually stabilized, no sound is radiated so no sound energy needs to be absorbed by the control device.

  12. Switching X-Ray Tubes Remotely

    Science.gov (United States)

    Bulthuis, Ronald V.

    1990-01-01

    Convenient switch and relay circuit reduces risk of accidents. Proposed switching circuit for x-ray inspection system enables operator to change electrical connections to x-ray tubes remotely. Operator simply flips switch on conveniently-located selector box to change x-ray heads. Indicator lights on selector box show whether 160 or 320-kV head connected. Relays in changeover box provides proper voltages and coolants. Chance of making wrong connections and damaging equipment eliminated.

  13. Dryout in sodium-heated helically-coiled steam generator tubes

    International Nuclear Information System (INIS)

    Tomita, Y.; Kosugi, T.; Kubota, J.; Nakajima, K.; Tsuchiya, T.

    1984-01-01

    Experimental research on the dryout phenomenon in sodium heated, helically coiled steam generator tubes was carried out. The fluctuation of the tube wall temperature caused by dryout was measured with thermocouples installed in the center of the tube wall. Empirical correlations of dryout quality were developed as functions of critical heat flux, water mass velocity and saturation pressure. These correlations confirmed that the design criterion of the MONJU steam generator was reasonable. (author)

  14. Neutron flux enhancement in the NRAD reactor

    International Nuclear Information System (INIS)

    Weeks, A.A.; Heidel, C.C.; Imel, G.R.

    1988-01-01

    In 1987 a series of experiments were conducted at the NRAD reactor facility at Argonne National Laboratory - West (ANL-W) to investigate the possibility of increasing the thermal neutron content at the end of the reactor's east beam tube through the use of hydrogenous flux traps. It was desired to increase the thermal flux for a series of experiments to be performed in the east radiography cell, in which the enhanced flux was required in a relatively small volume. Hence, it was feasible to attempt to focus the cross section of the beam to a smaller area. Two flux traps were constructed from unborated polypropylene and tested to determine their effectiveness. Both traps were open to the entire cross-sectional area of the neutron beam (as it emerges from the wall and enters the beam room). The sides then converged such that at the end of the trap the beam would be 'focused' to a greater intensity. The differences in the two flux traps were primarily in length, and hence angle to the beam as the inlet and outlet cross-sectional areas were held constant. The experiments have contributed to the design of a flux trap in which a thermal flux of nearly 10 9 was obtained, with an enhancement of 6.61

  15. Gastrostomy feeding tube - pump - child

    Science.gov (United States)

    ... tube feeding; PEG tube care; Feeding - gastrostomy tube - pump; G-tube - pump; Gastrostomy button - pump; Bard Button - pump; MIC-KEY - pump ... Gather supplies: Feeding pump (electronic or battery powered) Feeding ... pump (includes a feeding bag, drip chamber, roller clamp, ...

  16. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... search for current job openings visit HHS USAJobs Home >> NEI YouTube Videos >> NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia Animations Blindness Cataract ...

  17. Radon flux measurement methodologies

    International Nuclear Information System (INIS)

    Nielson, K.K.; Rogers, V.C.

    1984-01-01

    Five methods for measuring radon fluxes are evaluated: the accumulator can, a small charcoal sampler, a large-area charcoal sampler, the ''Big Louie'' charcoal sampler, and the charcoal tent sampler. An experimental comparison of the five flux measurement techniques was also conducted. Excellent agreement was obtained between the measured radon fluxes and fluxes predicted from radium and emanation measurements

  18. Strongly-Heated Gas Flow in Parallel Tube Rotation

    Directory of Open Access Journals (Sweden)

    Shuichi Torii

    1998-01-01

    Full Text Available A numerical analysis is performed to study thermal transport phenomena in gas flow through a strongly heated tube whose axis is in parallel with the rotational axis. The velocity and temperature fields prevail when fluid flows in a rotating tube with uniform heat flux on the tube wall. The two-equation k-ω turbulence and t2¯-εt heat transfer models are employed to determine turbulent viscosity and eddy diffusivity for heat, respectively. The governing boundary-layer equations are discritized by means of a control volume finitedifference techniques. It is found that the Coriolis and centrifugal (or centripetal forces cause fluid flow and heat transfer performance in the parallel-rotation system to be drastically different from those in the stationary case. Consequently, even if a tube rotating around a parallel axis is heated with high heat flux whose level causes a laminarizing flow in the stationary tube case, both the turbulent kinetic energy and the temperature variance remain over the pipe cross section, resulting in the suppression of an attenuation in heat transfer performance. In other words, an increase in tube rotation suppresses laminarization of gas flow.

  19. Burnout heat flux in natural flow boiling

    International Nuclear Information System (INIS)

    Helal, M.M.; Darwish, M.A.; Mahmoud, S.I.

    1978-01-01

    Twenty runs of experiments were conducted to determine the critical heat flux for natural flow boiling with water flowing upwards through annuli of centrally heated stainless steel tube. The test section has concentric heated tube of 14mm diameter and heated lengthes of 15 and 25 cm. The outside surface of the annulus was formed by various glass tubes of 17.25, 20 and 25.9mm diameter. System pressure is atmospheric. Inlet subcooling varied from 18 to 5 0 C. Obtained critical heat flux varied from 24.46 to 62.9 watts/cm 2 . A number of parameters having dominant influence on the critical heat flux and hydrodynamic instability (flow and pressure oscillations) preceeding the burnout have been studied. These parameters are mass flow rate, mass velocity, throttling, channel geometry (diameters ratio, length to diameter ratio, and test section length), and inlet subcooling. Flow regimes before and at the moments of burnout were observed, discussed, and compared with the existing physical model of burnout

  20. Hideout in steam generator tube deposits

    International Nuclear Information System (INIS)

    Balakrishnan, P.V.; Franklin, K.J.; Turner, C.W.

    1998-05-01

    Hideout in deposits on steam generator tubes was studied using tubes coated with magnetite. Hideout from sodium chloride solutions at 279 degrees C was followed using an on-line high-temperature conductivity probe, as well as by chemical analysis of solution samples from the autoclave in which the studies were done. Significant hideout was observed only at a heat flux greater than 200 kW/m 2 , corresponding to a temperature drop greater than 2 degrees C across the deposits. The concentration factor resulting from the hideout increased highly non-linearly with the heat flux (varying as high as the fourth power of the heat flux). The decrease in the apparent concentration factor with increasing deposit thickness suggested that the pores in the deposit were occupied by a mixture of steam and water, which is consistent with the conclusion from the thermal conductivity measurements on deposits in a separate study. Analyses of the deposits after the hideout tests showed no evidence of any hidden-out solute species, probably due to the concentrations being very near the detection limits and to their escape from the deposit as the tests were being ended. This study showed that hideout in deposits may concentrate solutes in the steam generator bulk water by a factor as high as 2 x 10 3 . Corrosion was evident under the deposit in some tests, with some chromium enrichment on the surface of the tube. Chromium enrichment usually indicates an acidic environment, but the mobility required of chromium to become incorporated into the thick magnetite deposit may indicate corrosion under an alkaline environment. An alkaline environment could result from preferential accumulation of sodium in the solution in the deposit during the hideout process. (author)

  1. Development of a discharge-heated plasma tube

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Byung Heon; Jin, J. T.; Nam, S. M.; Lee, S. M.; Choi, H. L.; Ko, D. K.; Kim, S. H.; Lee, Y. B.; Choi, Y. S.; Lee, J. M.; Lee, C. K.; Lee, H. G.; Lee, H. C.; Jung, S. M.; Kim, Y. J.; Choi, G. S.; Son, N. G

    1999-12-01

    A discharge-heated type plasma tube was designed and constructed. The structure of the laser plasma tube was designed to be easy in maintenance. The inside plasma tube was made of a high purity alumina and the thermal insulator tube was made of a porous alumina. The electrode made of tungsten was chosen for the endurance of high discharge voltage. AR coated windows were used as laser windows. A proto-type laser plasma tube was tested with a pulse modulator. An average laser output power was 32 W at the discharge voltage of 28 kV, the electric input power of 4.6 kW, and the pulse repetition rates of 10 kHz. (author)

  2. Categorising YouTube

    Directory of Open Access Journals (Sweden)

    Thomas Mosebo Simonsen

    2011-09-01

    Full Text Available This article provides a genre analytical approach to creating a typology of the User Generated Content (UGC of YouTube. The article investigates the construction of navigationprocesses on the YouTube website. It suggests a pragmatic genre approach that is expanded through a focus on YouTube’s technological affordances. Through an analysis of the different pragmatic contexts of YouTube, it is argued that a taxonomic understanding of YouTube must be analysed in regards to the vacillation of a user-driven bottom-up folksonomy and a hierarchical browsing system that emphasises a culture of competition and which favours the already popular content of YouTube. With this taxonomic approach, the UGC videos are registered and analysed in terms of empirically based observations. The article identifies various UGC categories and their principal characteristics. Furthermore, general tendencies of the UGC within the interacting relationship of new and old genres are discussed. It is argued that the utility of a conventional categorical system is primarily of analytical and theoretical interest rather than as a practical instrument.

  3. Characteristics and theory of operation of the controlatron neutron tube

    International Nuclear Information System (INIS)

    Volk, R.D.

    1977-01-01

    The Controlatron (or Type 26E) neutron tube was developed by General Electric under contract to Sandia Laboratories in 1961 to be used in a neutron activation analysis experiment on the lunar surface. It was subsequently employed as a very stable laboratory neutron source for neutron detector calibration within the ERDA complex. The Controlatron is a gas filled neutron tube using a titanium target, Penning type cold cathode ion source, and self-contained reservoir. The general theory of operation of this type of neutron tube utilizing the D-T nuclear reaction is presented

  4. Gas laser tube and method of fabricating same

    International Nuclear Information System (INIS)

    Garman, L.E.

    1975-01-01

    An improved gas laser tube is fabricated by counter boring the ends of a tubular aluminum extrusion having an inner tubular portion supported from an outer tubular portion via the intermediary of a plurality of radially directed support vanes or legs. Metallic transverse walls are sealed across the ends of the tubular extrusion to define the ends of a gas tight metallic envelope. An electrically insulative glow discharge tube is axially disposed within and supported by the inner tubular portion of the extrusion in axial alignment with an optical resonator of the laser tube. (U.S.)

  5. Fill tube fitted spheres

    International Nuclear Information System (INIS)

    Ives, B.H.

    1981-01-01

    The high temperature diffusion technique for fuel filling of some future direct drive cryogenic ICF targets may be unacceptable. The following describes a technique of fitting a 1 mm diameter x 6 μm thick glass microsphere with an approx. 50 μm O.D. glass fill tube. The process of laser drilling a 50 μm diameter hole in the microsphere wall, technique for making the epoxy joint between the sphere and fill tube, as well as the assembly procedure are also discussed

  6. Steam generator tube vibration study

    International Nuclear Information System (INIS)

    Enderlin, W.I.

    1986-01-01

    Chemical cleaning has been proposed to remove magnetite buildup in some pressurized water reactor steam generators. The US Nuclear Regulatory Commission (NRC) has expressed concern that such cleaning would combine with the tube denting caused by magnetite formation to enlarge tube/tube support plate clearances, increasing the level of flow-induced vibrations that could lead to unacceptably high tube wear and failure rates. In support of NRC, the Pacific Northwest Laboratory investigated whether such increased clearances would exacerbate tube fretting wear. Using a full-length scale model of a steam generator tube bundle, flow tests were conducted at an instrumented location through clearances representing as-built and post-cleaned tube conditions. Test results indicated little potential for increased tube wear as a result of chemical cleaning, under normal operating conditions at tube support locations similar to that tested

  7. Diamond Microchannel Heat Sink Designs For High Heat Flux Thermal Control

    National Research Council Canada - National Science Library

    Corbin, Michael

    2002-01-01

    ...) are expected in laser slabs and power amplifier tube collectors. These impressive heat flux levels frequently combine with strict operating temperature requirements to further compound the thermal control problem...

  8. Flux trapping during field reversal in a field reversed theta pinch

    International Nuclear Information System (INIS)

    Milroy, R.D.; Hoffman, A.L.; Slough, J.T.; Harding, D.G.

    1983-01-01

    In this paper we present new results from both numerical and experimental studies of the formation of the conducting sheath near the tube wall and its effectiveness in trapping bias flux during field reversal

  9. Inviscid flux-splitting algorithms for real gases with non-equilibrium chemistry

    Science.gov (United States)

    Shuen, Jian-Shun; Liou, Meng-Sing; Van Leer, Bram

    1990-01-01

    Formulations of inviscid flux splitting algorithms for chemical nonequilibrium gases are presented. A chemical system for air dissociation and recombination is described. Numerical results for one-dimensional shock tube and nozzle flows of air in chemical nonequilibrium are examined.

  10. Al/ oil nanofluids inside annular tube: an experimental study on convective heat transfer and pressure drop

    Science.gov (United States)

    Jafarimoghaddam, Amin; Aberoumand, Sadegh; Javaherdeh, Kourosh; Arani, Ali Akbar Abbasian; Jafarimoghaddam, Reza

    2017-10-01

    In this work, an experimental study on nanofluid preparation stability, thermo-physical properties, heat transfer performance and friction factor of Al/ Oil nanofluids has been carried out. Electrical Explosion Wire (E.E.W) which is one of the most reliable one-step techniques for nanofluids preparation has been used. An annular tube has been considered as the test section in which the outer tube was subject to a uniform heat flux boundary condition of about 204 W. The utilized nanofluids were prepared in three different volume concentrations of 0.011%, 0.044% and 0.171%. A wide range of parameters such as Reynolds number Prandtl number, viscosity, thermal conductivity, density, specific heat, convective heat transfer coefficient, Nusselt number and the friction factor have been studied. The experiment was conducted in relatively low Reynolds numbers of less than 160 and within a hydrodynamically fully-developed regime. According to the results, thermal conductivity, density and viscosity increased depending on the volume concentrations and working temperatures while the specific heat declined. More importantly, it was observed that convective heat transfer coefficient and Nusselt number enhanced by 28.6% and 16.4%, respectively, for the highest volume concentration. Finally, the friction factor (which plays an important role in the pumping power) was found to be increased around 18% in the volume fraction of 0.171%.

  11. Al/ oil nanofluids inside annular tube: an experimental study on convective heat transfer and pressure drop

    Science.gov (United States)

    Jafarimoghaddam, Amin; Aberoumand, Sadegh; Javaherdeh, Kourosh; Arani, Ali Akbar Abbasian; Jafarimoghaddam, Reza

    2018-04-01

    In this work, an experimental study on nanofluid preparation stability, thermo-physical properties, heat transfer performance and friction factor of Al/ Oil nanofluids has been carried out. Electrical Explosion Wire ( E.E.W) which is one of the most reliable one-step techniques for nanofluids preparation has been used. An annular tube has been considered as the test section in which the outer tube was subject to a uniform heat flux boundary condition of about 204 W. The utilized nanofluids were prepared in three different volume concentrations of 0.011%, 0.044% and 0.171%. A wide range of parameters such as Reynolds number Prandtl number, viscosity, thermal conductivity, density, specific heat, convective heat transfer coefficient, Nusselt number and the friction factor have been studied. The experiment was conducted in relatively low Reynolds numbers of less than 160 and within a hydrodynamically fully-developed regime. According to the results, thermal conductivity, density and viscosity increased depending on the volume concentrations and working temperatures while the specific heat declined. More importantly, it was observed that convective heat transfer coefficient and Nusselt number enhanced by 28.6% and 16.4%, respectively, for the highest volume concentration. Finally, the friction factor (which plays an important role in the pumping power) was found to be increased around 18% in the volume fraction of 0.171%.

  12. Misdirected minitracheostomy tube

    Directory of Open Access Journals (Sweden)

    Ajmer Singh

    2017-01-01

    Full Text Available We report a patient who after an uneventful coronary artery bypass graft surgery and left ventricular aneurysmorrhaphy developed intracerebral hemorrhage and subsequently required minitracheostomy. Chest X-ray showed misdirected minitracheostomy tube facing upward toward the laryngeal opening which was repositioned using bronchoscope.

  13. A New Resonance Tube

    Science.gov (United States)

    Bates, Alan

    2017-01-01

    The measurement of the speed of sound in air with the resonance tube is a popular experiment that often yields accurate results. One approach is to hold a vibrating tuning fork over an air column that is partially immersed in water. The column is raised and lowered in the water until the generated standing wave produces resonance: this occurs at…

  14. Thoughts of accelerator tubes

    International Nuclear Information System (INIS)

    Larson, J.D.

    1977-01-01

    A brief, subjective review is given of mechanisms that may be limiting electrostatic accelerator tubes to present levels of performance. Suggestions are made for attacking these limitations with the purpose of stimulating the thinking of designers and users of electrostatic accelerators

  15. Thoughts of accelerator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Larson, J D

    1977-01-01

    A brief, subjective review is given of mechanisms that may be limiting electrostatic accelerator tubes to present levels of performance. Suggestions are made for attacking these limitations with the purpose of stimulating the thinking of designers and users of electrostatic accelerators.

  16. Eustachian Tube Dysfunction

    Science.gov (United States)

    ... When it is inflated, the balloon opens a pathway for mucus and air to flow through the tube. This can help it function properly. FDA warning The U.S. Food and Drug Administration (FDA) advises against the use of ear candles. ...

  17. Tube-dwelling invertebrates

    NARCIS (Netherlands)

    Hölker, Franz; Vanni, Michael J.; Kuiper, Jan J.; Meile, Christof; Grossart, Hans Peter; Stief, Peter; Adrian, Rita; Lorke, Andreas; Dellwig, Olaf; Brand, Andreas; Hupfer, Michael; Mooij, Wolf M.; Nützmann, Gunnar; Lewandowski, Jörg

    2015-01-01

    There is ample evidence that tube-dwelling invertebrates such as chironomids significantly alter multiple important ecosystem functions, particularly in shallow lakes. Chironomids pump large water volumes, and associated suspended and dissolved substances, through the sediment and thereby compete

  18. Chest tube insertion

    Science.gov (United States)

    ... of your chest cavity. This is called the pleural space. It is done to allow your lungs to fully expand. ... pneumothorax ) Fluid buildup in the chest (called a pleural ... in the esophagus (the tube that allows food to go from the mouth ...

  19. Energy and energy flux in axisymmetric slow and fast waves

    Science.gov (United States)

    Moreels, M. G.; Van Doorsselaere, T.; Grant, S. D. T.; Jess, D. B.; Goossens, M.

    2015-06-01

    Aims: We aim to calculate the kinetic, magnetic, thermal, and total energy densities and the flux of energy in axisymmetric sausage modes. The resulting equations should contain as few parameters as possible to facilitate applicability for different observations. Methods: The background equilibrium is a one-dimensional cylindrical flux tube model with a piecewise constant radial density profile. This enables us to use linearised magnetohydrodynamic equations to calculate the energy densities and the flux of energy for axisymmetric sausage modes. Results: The equations used to calculate the energy densities and the flux of energy in axisymmetric sausage modes depend on the radius of the flux tube, the equilibrium sound and Alfvén speeds, the density of the plasma, the period and phase speed of the wave, and the radial or longitudinal components of the Lagrangian displacement at the flux tube boundary. Approximate relations for limiting cases of propagating slow and fast sausage modes are also obtained. We also obtained the dispersive first-order correction term to the phase speed for both the fundamental slow body mode under coronal conditions and the slow surface mode under photospheric conditions. Appendix A is available in electronic form at http://www.aanda.org

  20. A comparison of the CHF between tubes and annuli under PWR thermal-hydraulic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Herer, C. [RRAMATOME EP/TC, Paris (France); Souyri, A. [EdF DER/RNE/TTA, Chatou (France); Garnier, J. [CEA DRN/DTP/STR/LETC, Grenoble (France)

    1995-09-01

    Critical Heat Flux (CHF) tests were carried out in three tubes with inside diameters of 8, 13, and 19.2 mm and in two annuli with an inner tube of 9.5 mm and an outer tube of 13 or 19.2 mm. All axial heat flux distributions in the test sections were uniform. The coolant fluid was Refrigerant 12 (Freon-12) under PWR thermal-hydraulic conditions (equivalent water conditions - Pressure: 7 to 20 MPa, Mass Velocity: 1000 to 6000 kg/m2/s, Local Quality: -75% to +45%). The effect of tube diameter is correlated for qualities under 15%. The change from the tube to the annulus configuration is correctly taken into account by the equivalent hydraulic diameter. Useful information is also provided concerning the effect of a cold wall in an annulus.

  1. Clustering of Emerging Flux

    Science.gov (United States)

    Ruzmaikin, A.

    1997-01-01

    Observations show that newly emerging flux tends to appear on the Solar surface at sites where there is flux already. This results in clustering of solar activity. Standard dynamo theories do not predict this effect.

  2. Military Curricula for Vocational & Technical Education. Basic Electricity and Electronics. CANTRAC A-100-0010. Module 21: Basic Transistor Theory; Module 21T: Multi-Element Vacuum Tubes. Study Booklet.

    Science.gov (United States)

    Chief of Naval Education and Training Support, Pensacola, FL.

    This set of individualized learning modules on transistor theory is one in a series of modules for a course in basic electricity and electronics. The course is one of a number of military-developed curriculum packages selected for adaptation to vocational instructional and curriculum development in a civilian setting. Two modules are included in…

  3. Surface Flux Modeling for Air Quality Applications

    Directory of Open Access Journals (Sweden)

    Limei Ran

    2011-08-01

    Full Text Available For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic compounds, can be upward into the air as well as downward to the surface and therefore should be modeled as bi-directional fluxes. Model parameterizations of dry deposition in air quality models have been represented by simple electrical resistance analogs for almost 30 years. Uncertainties in surface flux modeling in global to mesoscale models are being slowly reduced as more field measurements provide constraints on parameterizations. However, at the same time, more chemical species are being added to surface flux models as air quality models are expanded to include more complex chemistry and are being applied to a wider array of environmental issues. Since surface flux measurements of many of these chemicals are still lacking, resistances are usually parameterized using simple scaling by water or lipid solubility and reactivity. Advances in recent years have included bi-directional flux algorithms that require a shift from pre-computation of deposition velocities to fully integrated surface flux calculations within air quality models. Improved modeling of the stomatal component of chemical surface fluxes has resulted from improved evapotranspiration modeling in land surface models and closer integration between meteorology and air quality models. Satellite-derived land use characterization and vegetation products and indices are improving model representation of spatial and temporal variations in surface flux processes. This review describes the current state of chemical dry deposition modeling, recent progress in bi-directional flux modeling, synergistic model development research with field measurements, and coupling with meteorological land surface models.

  4. An analytical study of critical heat flux in natural convective boiling in ...

    African Journals Online (AJOL)

    An analytical study of critical heat flux in natural convective boiling in a vertical tube. ... by this model are explained and compared with similar existing experimental works. The effects of working fluids, working pressure, and tube geometry are mainly explained and compared to verify the basic performance of the model.

  5. Prediction of critical heat flux for water in uniformly heated vertical ...

    African Journals Online (AJOL)

    This paper includes the prediction of critical heat flux (CHF) for uniformly heated vertical porous coated tubes at pressures between 0,1 to 0,7 MPa. In this study, we use a total of 742 data points of CHF for water in uniformly heated vertical porous coated tubes obtained from literature. Accuracy of correlations was estimated ...

  6. Performance of pressure tubes in CANDU reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, D.; Griffiths, M.; Bickel, G.; Buyers, A.; Coleman, C.; Nordin, H.; St Lawrence, S. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    The pressure tubes in CANDU reactors typically operate for times up to about 30 years prior to refurbishment. The in-reactor performance of Zr-2.5Nb pressure tubes has been evaluated by sampling and periodic inspection. This paper describes the behavior and discusses the factors controlling the behaviour of these components. The Zr–2.5Nb pressure tubes are nominally extruded at 815{sup o}C, cold worked nominally 27%, and stress relieved at 400 {sup o}C for 24 hours, resulting in a structure consisting of elongated grains of hexagonal close-packed alpha-Zr, partially surrounded by a thin network of filaments of body-centred-cubic beta-Zr. These beta-Zr filaments are meta-stable and contain about 20% Nb after extrusion. The stress-relief treatment results in partial decomposition of the beta-Zr filaments with the formation of hexagonal close-packed alpha-phase particles that are low in Nb, surrounded by a Nb-enriched beta-Zr matrix. The material properties of pressure tubes are determined by variations in alpha-phase texture, alpha-phase grain structure, network dislocation density, beta-phase decomposition, and impurity concentration that are a function of manufacturing variables. The pressure tubes operate at temperatures between 250 {sup o}C and 310 {sup o}C with coolant pressures up to about 11 MPa in fast neutron fluxes up to 4 x 10{sup 17} n·m{sup -2}·s{sup -1} (E > 1 MeV) and the properties are modified by these conditions. The properties of the pressure tubes in an operating reactor are therefore a function of both manufacturing and operating condition variables. The ultimate tensile strength, fracture toughness, and delayed hydride-cracking properties (velocity (V) and threshold stress intensity factor (K{sub IH})) change with irradiation, but all reach a nearly limiting value at a fluence of less than 10{sup 25} n·m{sup -2} (E > 1 MeV). At this point the ultimate tensile strength is raised about 200 MPa, toughness is reduced by about 50%, V increases

  7. Optimization of the heat treatment schedule for next european dipole (NED) powder in tube $Nb_{3}Sn$ strand

    CERN Document Server

    Boutboul, T; den Ouden, A; Pedrini, D; Volpini, G

    2009-01-01

    A Nb3Sn strand was successfully developed by the company SMI for Next European Dipole (NED) activity and on the basis of Powder-In-Tube (PIT) method. This strand, after the standard reaction recommended by the firm (84 h @ 675 oC), presents attractive performances as a critical current density in the non-copper part of ~ 2500 A/mm2 for 4.2 K and 12 T applied field, an effective filament diameter of ~ 50 μm and limited flux jumps at low magnetic fields. Heat treatment optimization studies are currently performed at CERN to try to optimize the strand electric abilities. For this purpose, various heat treatment schedules were already investigated with a plateau temperature as low as 625 oC. The preliminary results of these studies are summarized here.

  8. Drift tubes of Linac 2

    CERN Multimedia

    Photographic Service

    1977-01-01

    Being redied for installation, those at the right are for tank 1, those on the left for tank 2. Contrary to Linac 1, which had drift-tubes supported on stems, here the tubes are suspended, for better mechanical stability.

  9. Rubens Flame-Tube Demonstration.

    Science.gov (United States)

    Ficken, George W.; Stephenson, Francis C.

    1979-01-01

    Investigates and explains the phenomenon associated with Rubens flame-tube demonstration, specifically the persistance of flames at regular intervals along the tube for few minutes after the gas is turned off. (GA)

  10. Prospects for stronger calandria tubes

    International Nuclear Information System (INIS)

    Ells, C.E.; Coleman, C.E.; Hosbons, R.R.; Ibrahim, E.F.; Doubt, G.L.

    1990-12-01

    The CANDU calandria tubes, made of seam welded and annealed Zircaloy-2, have given exemplary service in-reactor. Although not designed as a system pressure containment, calandria tubes may remain intact even in the face of pressure tube rupture. One such incident at Pickering Unit 2 demonstrated the economic advantage of such an outcome, and a case can be made for increasing the probability that other calandria tubes would perform in a similar fashion. Various methods of obtaining stronger calandria tubes are available, and reviewed here. When the tubes are internally pressurized, the weld is the weak section of the tube. Increasing the oxygen concentration in the starting sheet, and thickening the weld, are promising routes to a stronger tube

  11. Expansion lyre-shaped tube

    International Nuclear Information System (INIS)

    Andro, Jean.

    1973-01-01

    The invention relates the expansion lyre-shaped tube portions formed in dudgeoned tubular bundles between two bottom plates. An expansion lyre comprises at least two sets of tubes of unequal lengths coplanar and symmetrical with respect to the main tube axis, with connecting portions between the tubes forming said sets. The invention applies to apparatus such as heat exchangers, heaters, superheaters or breeders [fr

  12. U-tube steam generator predictions

    International Nuclear Information System (INIS)

    Hassan, Y.A.; Kalyanasundaram, M.

    1991-01-01

    This paper reports on the development of a RELAP5/MOD2 computer code model for a Model Boiler-2 U-tube steam generator (UTSG) to predict the thermal-hydraulic response of a UTSG during steady-state operation and for a loss-of-feedwater (LOF) transient. Steady-state conditions calculated by RELAP5 are compared with the measured data. The calculated heat transfer from the primary to the secondary side of the steam generator is found to be underpredicted by 30%. The heat transfer correlations used in existing thermal-hydraulic codes are developed for flow inside individual tubes and not for flow around tube bundles. Consequently, the secondary convective heat transfer is not accurately predicted by the codes. A revised version of the RELAP5 code with modified heat transfer correlations reasonably predicts the primary to the secondary heat transfer in bundle environments. Improved heat fluxes and heat transfer coefficients are obtained during steady-state and LOF accident transients. Steady-state behavior of the Semiscale MOD-2C steam generator is also computed with both the original and the revised versions of the code. Good agreement is achieved between the predictions and the test data when the modified heat transfer correlations are utilized

  13. Tracking heat flux sensors for concentrating solar applications

    Science.gov (United States)

    Andraka, Charles E; Diver, Jr., Richard B

    2013-06-11

    Innovative tracking heat flux sensors located at or near the solar collector's focus for centering the concentrated image on a receiver assembly. With flux sensors mounted near a receiver's aperture, the flux gradient near the focus of a dish or trough collector can be used to precisely position the focused solar flux on the receiver. The heat flux sensors comprise two closely-coupled thermocouple junctions with opposing electrical polarity that are separated by a thermal resistor. This arrangement creates an electrical signal proportional to heat flux intensity, and largely independent of temperature. The sensors are thermally grounded to allow a temperature difference to develop across the thermal resistor, and are cooled by a heat sink to maintain an acceptable operating temperature.

  14. A neutron-reflecting conical tube calculation code: FOCUS

    International Nuclear Information System (INIS)

    Shimooke, Takanori; Levine, M.M.

    1976-02-01

    A focalizer, i.e. the neutron-reflecting conical tube is a device to collimate and intensify a beam of neutrons by means of the total reflection. This report describes the code FOCUS for calculating the neutron flux intensity and spectrum emerging from such a device. Complete ''input and output'' procedures are written for the code. The equations and methods used in the code are also explained. In the introduction, a brief description is given on the total reflection of neutrons and on the several devices of the neutron reflecting and conducting tubes. (auth.)

  15. NEI You Tube Videos: Amblyopia

    Science.gov (United States)

    ... NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia Animations Blindness Cataract Convergence Insufficiency Diabetic Eye Disease Dilated Eye Exam Dry Eye For Kids Glaucoma Healthy Vision Tips Leber Congenital Amaurosis Low ...

  16. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia Animations Blindness Cataract Convergence Insufficiency Diabetic Eye Disease Dilated Eye Exam Dry Eye For Kids Glaucoma Healthy Vision Tips Leber Congenital Amaurosis Low ...

  17. Electric Guitar and Violin

    Science.gov (United States)

    Gough, Colin

    Almost all the instruments described in this book have their origins in historical cultures dating back over many centuries. In contrast, the electric guitar and violin are clearly twentieth-century innovations. They are products of the electronics age following invention of the rectifying thermionic valve (tube) by John Ambrose Fleming in 1904, the amplifying triode valve (tube) by Lee de Forest in 1907, and the vacuum-filled amplifying valve (tube) by Irving Langmuir in 1915. By 1916, such valves were already being used in radio receivers, and important advances were being made in microphone, amplifier, and loudspeaker design. This, and the increasingly wide distribution of mains electricity in the 1920s, provided the technology and infrastructure for the development of the electric guitar and violin and their lower-pitched relations - the bass guitar, viola, cello, and string-bass. Although we focus here on the electric guitar and violin, almost everything discussed in this chapter is also relevant to their lower-pitched relations.

  18. Neutron image intensifier tubes

    International Nuclear Information System (INIS)

    Verat, M.; Rougeot, H.; Driard, B.

    1983-01-01

    The most frequently used techniques in neutron radiography employ a neutron converter consisting of either a scintillator or a thin metal sheet. The radiation created by the neutrons exposes a photographic film that is in contact with the converter: in the direct method, the film is exposed during the time that the object is irradiated with neutrons; in the transfer method, the film is exposed after the irradiation of the object with neutrons. In industrial non-destructive testing, when many identical objects have to be checked, these techniques have several disadvantages. Non-destructive testing systems without these disadvantages can be constructed around neutron-image intensifier tubes. A description and the operating characteristics of neutron-image intensifier tubes are given. (Auth.)

  19. Neural tube defects

    Directory of Open Access Journals (Sweden)

    M.E. Marshall

    1981-09-01

    Full Text Available Neural tube defects refer to any defect in the morphogenesis of the neural tube, the most common types being spina bifida and anencephaly. Spina bifida has been recognised in skeletons found in north-eastern Morocco and estimated to have an age of almost 12 000 years. It was also known to the ancient Greek and Arabian physicians who thought that the bony defect was due to the tumour. The term spina bifida was first used by Professor Nicolai Tulp of Amsterdam in 1652. Many other terms have been used to describe this defect, but spina bifida remains the most useful general term, as it describes the separation of the vertebral elements in the midline.

  20. Heat transfer behaviors in round tube with conical ring inserts

    International Nuclear Information System (INIS)

    Promvonge, P.

    2008-01-01

    To increase convection heat transfer in a uniform heat flux tube by a passive method, several conical rings used as turbulators are mounted over the test tube. The effects of the conical ring turbulator inserts on the heat transfer rate and friction factor are experimentally investigated in the present work. Conical rings with three different diameter ratios of the ring to tube diameter (d/D = 0.5, 0.6, 0.7) are introduced in the tests, and for each ratio, the rings are placed with three different arrangements (converging conical ring, referred to as CR array, diverging conical ring, DR array and converging-diverging conical ring, CDR array). In the experiment, cold air at ambient condition for Reynolds numbers in a range of 6000-26,000 is passed through the uniform heat flux circular tube. It is found that the ring to tube diameter ratio and the ring arrays provide a significant effect on the thermal performance of the test tube. The experimental results demonstrate that the use of conical ring inserts leads to a higher heat transfer rate than that of the plain surface tube, and the DR array yields a better heat transfer than the others. The results are also correlated in the form of Nusselt number as a function of Reynolds number, Prandtl number and diameter ratio. An augmentation of up to 197%, 333%, and 237% in Nusselt number is obtained in the turbulent flow for the CR, DR and CDR arrays, respectively, although the effect of using the conical ring causes a substantial increase in friction factor

  1. Front-end electronics for long straw tube systems

    International Nuclear Information System (INIS)

    Paulos, J.J.; Blake, S.L.

    1990-01-01

    This paper addresses several critical issues in the readout of long, small diameter plastic straw tubes for central tracking subsystems. Of particular concern are signal attentuation in long straw tubes and signal reflections which arise from improper termination at the ends of the tube. This work is part of a 12 institution collaboration to design and validate a hybrid central tracking chamber (HCTC) utilizing both straw tube and scintillating fiber components. The HCTC design calls for 4 mm diameter plastic straw tubes spanning the entire central tracking region (6-8 m) with readout electronics at both ends. An electrical isolator may be used at the center of each wire to separate each tube into two electrically isolated regions so as to reduce occupancy by a factor of two. With this scheme, no track is farther than 4 m from the associated readout electronics. The HCTC collaboration includes the participation of researchers at the University of Pennsylvania who have contributed a preamplifier and shaper ship which is used in the simulations presented here. A more complete discussion of the HCTC design can be found in the paper by Dr. Alfred Goshaw

  2. The physical foundation of the reconnection electric field

    Science.gov (United States)

    Hesse, M.; Liu, Y.-H.; Chen, L.-J.; Bessho, N.; Wang, S.; Burch, J. L.; Moretto, T.; Norgren, C.; Genestreti, K. J.; Phan, T. D.; Tenfjord, P.

    2018-03-01

    Magnetic reconnection is a key charged particle transport and energy conversion process in environments ranging from astrophysical systems to laboratory plasmas [Yamada et al., Rev. Mod. Phys. 82, 603-664 (2010)]. Magnetic reconnection facilitates plasma transport by establishing new connections of magnetic flux tubes, and it converts, often explosively, energy stored in the magnetic field to kinetic energy of charged particles [J. L. Burch and J. F. Drake, Am. Sci. 97, 392-299 (2009)]. The intensity of the magnetic reconnection process is measured by the reconnection electric field, which regulates the rate of flux tube connectivity changes. The change of magnetic connectivity occurs in the current layer of the diffusion zone, where the plasma transport is decoupled from the transport of magnetic flux. Here we report on computer simulations and analytic theory to provide a self-consistent understanding of the role of the reconnection electric field, which extends substantially beyond the simple change of magnetic connections. Rather, we find that the reconnection electric field is essential to maintain the current density in the diffusion region, which would otherwise be dissipated by a set of processes. Natural candidates for current dissipation are the average convection of current carriers away from the reconnection region by the outflow of accelerated particles, or the average rotation of the current density by the magnetic field reversal in the vicinity. Instead, we show here that the current dissipation is the result of thermal effects, underlying the statistical interaction of current-carrying particles with the adjacent magnetic field. We find that this interaction serves to redirect the directed acceleration of the reconnection electric field to thermal motion. This thermalization manifests itself in form of quasi-viscous terms in the thermal energy balance of the current layer. This collisionless viscosity, found in the pressure evolution equation

  3. Quantitative experiments on thermal hydraulic characteristics of an annular tube with twisted fins

    International Nuclear Information System (INIS)

    Ezato, Koichiro; Dairaku, Masayuki; Taniguchi, Masaki; Sato, Kazuyoshi; Suzuki, Satoshi; Akiba, Masato

    2003-11-01

    Thermal hydraulic experiments measuring critical heat flux (CHF) and pressure drop of an annular tube with twisted fins, ''annular swirl tube'', has been performed to examine its applicability to the ITER divertor cooling structure. The annular swirl tube consists of two concentric circular tubes, the outer and inner tubes. The outer tube with outer and inner diameters (OD and ID) of 21 mm and 15 mm is made of Cu-alloy that is CuCrZr and oe of candidate materials of the ITER divertor cooling tube. The inner tube with OD of 11 mm and ID of 9 mm is made of stainless steal. It has an external swirl fin with twist ratio (y) of three to enhance its heat transfer performance. In this tube, cooling water flows inside of the inner tube first, and then returns into an annulus between the outer and inner tubes with a swirl flow at an end-return of the cooling tube. The CHF experiments show that no degradation of CHF of the annular swirl tube in comparison with the conventional swirl tube whose dimensions are similar to those of the outer tube of the annular swirl tube. A minimum axial velocity of 7.1 m/s is required to remove the incident heat flux of 28MW/m 2 , the ITER design value. Applicability of the JAERI's correlation for the heat transfer to the annular swirl tube is also demonstrated by comparing the experimental results with those of the numerical analysis. The friction factor correlation for the annular flow with the twisted fins is also proposed for the hydrodynamic design of the ITER vertical target. The least pressure drop at the end-return is obtained by using the hemispherical end-plug. Its radius is the same as that of ID of the outer cooling tube. These results show that thermal-hydraulic performance of the annular swirl tube is promising in application to the cooling structure for the ITER vertical target. (author)

  4. Pressure distribution over tube surfaces of tube bundle subjected to two phase cross flow

    International Nuclear Information System (INIS)

    Sim, Woo Gun

    2013-01-01

    Two phase vapor liquid flows exist in many shell and tube heat exchangers such as condensers, evaporators and nuclear steam generators. To understand the fluid dynamic forces acting on a structure subjected to a two phase flow, it is essential to obtain detailed information about the characteristics of a two phase flow. The characteristics of a two phase flow and the flow parameters were introduced, and then, an experiment was performed to evaluate the pressure loss in the tube bundles and the fluid dynamic force acting on the cylinder owing to the pressure distribution. A two phase flow was pre mixed at the entrance of the test section, and the experiments were undertaken using a normal triangular array of cylinders subjected to a two phase cross flow. The pressure loss along the flow direction in the tube bundles was measured to calculate the two phase friction multiplier, and the multiplier was compared with the analytical value. Furthermore, the circular distributions of the pressure on the cylinders were measured. Based on the distribution and the fundamental theory of two phase flow, the effects of the void fraction and mass flux per unit area on the pressure coefficient and the drag coefficient were evaluated. The drag coefficient was calculated by integrating the measured pressure coefficient and the drag coefficient were evaluated. The drag coefficient was calculated by integrating the measured pressure on the tube by a numerical method. It was found that for low mass fluxes, the measured two phase friction multipliers agree well with the analytical results, and good agreement for the effect of the void fraction on the drag coefficients, as calculated by the measured pressure distributions, is shown qualitatively, as compared to the existing experimental results

  5. Multi-circular flux motor

    Energy Technology Data Exchange (ETDEWEB)

    El-Kharashi, Eyhab Aly, E-mail: EyhabElkharahi@hotmail.com [Faculty of Engineering, Electrical Power and Machines Department, Ain Shams University, 1 El-Sarayat Street, Abdou Basha Square, Abbassia 11517, Cairo (Egypt)

    2011-11-15

    Highlights: {yields} The paper uses the multi-circular rotor in the switched reluctance motor to increase its output torque and its efficiency. {yields} Finite element is used to model the new SRM accurately. {yields} The Matlab/Simulink is used to dynamically model the new SRM. {yields} The paper compares the torque capability of the multi-circular rotor SRM. {yields} The new SRM produces approximately double the torque of its equivalent conventional SRM. - Abstract: The paper introduces a new type of electrical machines which has significantly high output torque. The toothed-rotor in the conventional electrical machine is replaced by a multi-circular rotor to increase the saliency and to shorten the flux loops consequently the output torque increases. The paper presents the design steps of this new type of electrical machine and also examines its performance. In addition, the paper compares the percentage increase in output torque from the proposed new electric machine to its equivalent conventional motor. Then the paper proceeds to discuss the relation between the switching on angle and the maximum speed, the torque ripples, and the efficiency.

  6. CRL X-ray tube

    International Nuclear Information System (INIS)

    Kolchevsky, N.N.; Petrov, P.V.

    2015-01-01

    A novel types of X-ray tubes with refractive lenses are proposed. CRL-R X-ray tube consists of Compound Refractive Lens- CRL and Reflection X-ray tube. CRL acts as X-ray window. CRL-T X-ray consists of CRL and Transmission X-ray tube. CRL acts as target for electron beam. CRL refractive lens acts as filter, collimator, waveguide and focusing lens. Properties and construction of the CRL X-ray tube are discussed. (authors)

  7. CRL X-RAY TUBE

    OpenAIRE

    Kolchevsky, N. N.; Petrov, P. V.

    2015-01-01

    A novel types of X-ray tubes with refractive lenses are proposed. CRL-R X-ray tube consists of Compound Refractive Lens- CRL and Reflection X-ray tube. CRL acts as X-ray window. CRL-T X-ray consists of CRL and Transmission X-ray tube. CRL acts as target for electron beam. CRL refractive lens acts as filter, collimator, waveguide and focusing lens. Properties and construction of the CRL X-ray tube are discussed.

  8. Neutron flux enhancement in the NRAD reactor

    International Nuclear Information System (INIS)

    Weeks, A.A.; Heidel, C.C.; Imel, G.R.

    1988-01-01

    In 1987 a series of experiments were conducted at the NRAD reactor facility at Argonne National Laboratory - West (ANL-W) to investigate the possibility of increasing the thermal neutron content at the end of the reactor's east beam tube through the use of hydrogenous flux traps. It was desired to increase the thermal flux for a series of experiments to be performed in the east radiography cell, in which the enhanced flux was required in a relatively small volume. Hence, it was feasible to attempt to focus the cross section of the beam to a smaller area. Two flux traps were constructed from unborated polypropylene and tested to determine their effectiveness. Both traps were open to the entire cross-sectional area of the neutron beam (as it emerges from the wall and enters the beam room). The sides then converged such that at the end of the trap the beam would be 'focused' to a greater intensity. The differences in the two flux traps were primarily in length, and hence angle to the beam as the inlet and outlet cross-sectional areas were held constant. It should be noted that merely placing a slab of polypropylene in the beam will not yield significant multiplication as neutrons are primarily scattered away

  9. Small-size meshless 50 ps streak tube

    Science.gov (United States)

    Ageeva, N. V.; Andreev, S. V.; Belolipetski, V. S.; Bryukhnevich, G. I.; Greenfield, D. E.; Ivanova, S. R.; Kaverin, A. M.; Khohlova, A. N.; Kuz'menko, E. A.; Levina, G. P.; Makushina, V. A.; Monastyrskiy, M. A.; Schelev, M. Ya.; Semichastnova, Z. M.; Serdyuchenko, Yu. N.; Skaballanovich, T. A.; Sokolov, V. E.

    2008-11-01

    In contrast to the conventional image intensifier with large work area, a streak image tube should possess additional important feature - the comparatively small temporal distortion at the entire work area of the photocathode. With this additional engineering restriction taken into account, a novel small-size meshless streak image tube has been developed by means of numerical optimization. The tube with 25-mm wide work area contains a pair of deflection plates to sweep the electron image along the 25 mm output phosphor screen that is separated by 100 mm from the photocathode. The electron image can be shuttered with a 300 V blanking electric pulse. Electron-optical magnification of the tube is unit; spatial resolution reaches 30 lp/mm over the entire photocathode work area; temporal resolution lies in the 20 - 50 ps range, depending on the accelerating voltage (6 - 15 kV).

  10. Tachyon tube on non BPS D-branes

    International Nuclear Information System (INIS)

    Huang Wunghong

    2004-01-01

    We report our searches for a single tubular tachyonic solution of regular profile on unstable non BPS D3-branes. We first show that some extended Dirac-Born-Infeld tachyon actions in which new contributions are added to avoid the Derrick's no-go theorem still could not have a single regular tube solution. Next we use the Minahan-Zwiebach tachyon action to find the regular tube solutions with circular or elliptic cross section. With a critical electric field, the energy of the tube comes entirely from the D0 and strings, while the energy associated to the tubular D2-brane tension is vanishing. We also show that fluctuation spectrum around the tube solution does not contain tachyonic mode. The results are consistent with the identification of the tubular configuration as a BPS D2-brane. (author)

  11. Experimental Investigation on Heat Transfer of Silver-Oil Nanofluid in Concentric Annular Tube

    Directory of Open Access Journals (Sweden)

    H. Aberoumand

    2015-06-01

    Full Text Available In order to examine the laminar convective heat transfer of nanofluid, experiments carried out using silver-oil nanofluid in a concentric annulus with outer constant heat flux as boundary condition. Silver-oil nanofluid prepared by Electrical Explosion of Wire technique and observed no nanoparticles agglomeration during nanofluid preparation process and carried out experiments. The average size of particles established to 20 nm. Nanofluids with various particle weight fractions of 0.12%wt., 0.36%wt. and 0.72%wt. were employed. The nanofluid flowing between the tubes is heated by an electrical heating coil wrapped around it. The effects of different parameters such as flow Reynolds number, diameter ratio and nanofluid particle concentration on heat transfer coefficient are studied. Results show that, heat transfer coefficient  and Nusselt number increased by using naanofluid instead of pure oil. Maximum enhancement of heat transfer coefficient occurs in 0.72% wt. also results indicate that heat transfer coefficient  increase slightly by using low wt. concentration of nanofluids.

  12. Prediction of critical heat flux for water in uniformly heated vertical ...

    African Journals Online (AJOL)

    critical heat flux for the forced convective boiling in uniformly heated vertical tubes, Int. J. Heat Mass Transfer, Vol. 27 1641–1648. [5] Whalley P.B., Hutchinson P. & Hewitt. G.F., 1974. The calculation of critical heat flux in forced convective boiling, Proceeding of. Fifth International Heat Transfer conference,. Tokyo, 290-294.

  13. Falling film evaporation on a tube bundle with plain and enhanced tubes

    International Nuclear Information System (INIS)

    Habert, M.

    2009-04-01

    The complexities of two-phase flow and evaporation on a tube bundle present important problems in the design of heat exchangers and the understanding of the physical phenomena taking place. The development of structured surfaces to enhance boiling heat transfer and thus reduce the size of evaporators adds another level of complexity to the modeling of such heat exchangers. Horizontal falling film evaporators have the potential to be widely used in large refrigeration systems and heat pumps, in the petrochemical industry and for sea water desalination units, but there is a need to improve the understanding of falling film evaporation mechanisms to provide accurate thermal design methods. The characterization of the effect of enhanced surfaces on the boiling phenomena occurring in falling film evaporators is thus expected to increase and optimize the performance of a tube bundle. In this work, the existing LTCM falling film facility was modified and instrumented to perform falling film evaporation measurements on single tube row and a small tube bundle. Four types of tubes were tested including: a plain tube, an enhanced condensing tube (Gewa-C+LW) and two enhanced boiling tubes (Turbo-EDE2 and Gewa-B4) to extend the existing database. The current investigation includes results for two refrigerants, R134a and R236fa, at a saturation temperature of T sat = 5 °C, liquid film Reynolds numbers ranging from 0 to 3000, at heat fluxes between 20 and 60 kW/m² in pool boiling and falling film configurations. Measurements of the local heat transfer coefficient were obtained and utilized to improve the current prediction methods. Finally, the understanding of the physical phenomena governing the falling film evaporation of liquid refrigerants has been improved. Furthermore, a method for predicting the onset of dry patch formation has been developed and a local heat transfer prediction method for falling film evaporation based on a large experimental database has been proposed

  14. Design and Fabrication of Carbon Nano tube for Medical Application

    International Nuclear Information System (INIS)

    Azniza Abas; Nuzaihan, M.N.; Hafiza, N.; Nazwa, T.

    2011-01-01

    Carbon nano tubes or known as CNTs are allotropes of carbon with a cylindrical nano structure. They exhibit extraordinary strength and unique electrical properties, and are efficient thermal conductors [1]. Due to its ordinary properties this research will based on BIOSENSOR device. Normally these CNTs biosensor are based on an enzyme catalyzed reaction that will produce either electrons or protons. In particular, it is useful in genetic profiling of human diseases, which includes in identifying genes that are expressed in certain diseases such as cancer [2]. This research will based on design and fabricate sensor or device using carbon nano tube and integrate carbon nano tube (CNTs) onto wafer using combination of dichlorophosphate and nano manipulation. Carbon nano tubes device mask are design using AUTOCAD software; there is four mask involved, first mask is Gate Formation,second mask is insulation layer third mask is source and drain and final mask forth mask is used as test channel. For fabrication and optimization of biosensor using carbon nano tube CNT that will be involve both microfabrication and nano fabrication. This process will involve conventional photolithography process, electron beam evaporator, thermal oxidation and wet etching process. To inspect and characterize carbon nano tube electrical properties it will involve tools such as SEM, AFM, Dielectric Analyzer, IV-CV and Semiconductor Parametric Analyzer system. This inspection is very important to produce a perfect profile to produce a good biosensor based on carbon nano tube structure. Preparation of various samples for testing functionality of the device this various samples and conditions will be done to ensure the detection is precise. Conductivity and capacitance effect will be tested electrically to detect the hybridization of the sample. (author)

  15. Electrical resistivity probes

    Science.gov (United States)

    Lee, Ki Ha; Becker, Alex; Faybishenko, Boris A.; Solbau, Ray D.

    2003-10-21

    A miniaturized electrical resistivity (ER) probe based on a known current-voltage (I-V) electrode structure, the Wenner array, is designed for local (point) measurement. A pair of voltage measuring electrodes are positioned between a pair of current carrying electrodes. The electrodes are typically about 1 cm long, separated by 1 cm, so the probe is only about 1 inch long. The electrodes are mounted to a rigid tube with electrical wires in the tube and a sand bag may be placed around the electrodes to protect the electrodes. The probes can be positioned in a borehole or on the surface. The electrodes make contact with the surrounding medium. In a dual mode system, individual probes of a plurality of spaced probes can be used to measure local resistance, i.e. point measurements, but the system can select different probes to make interval measurements between probes and between boreholes.

  16. An investigation on thermal and friction effect produced by friction welding of SA 213 tube to SA 387 tube plate

    Directory of Open Access Journals (Sweden)

    S. Pandia Rajan

    2016-03-01

    Full Text Available The present study investigates the effect of thermal and friction produced in the tube to tube plate during the friction welding process by using a Tungsten carbide external tool. In this process, the fictional welding of SA 213 tube and SA 387 tube plate was done by using an external tool. Modeling of tool and wok piece is done by using Solid works and to study the thermal and frictional effect by using Ansys. In this research work, joining of SA 213 tube to SA 387 tube plate was done by using two different techniques such as with hole [WH] and without hole [WOH]. The stress value of with hole and without hole such as 18,782 MPa and 10,486 MPa respectively and the ultimate heat flux generated with hole and without hole such as 0.80475 W/mm2 and 1.1344 W/mm2 respectively were observed.

  17. Compact neutron flux monitor

    International Nuclear Information System (INIS)

    Madhavi, V.; Phatak, P.R.; Bahadur, C.; Bayala, A.K.; Jakati, R.K.; Sathian, V.

    2003-01-01

    Full text: A compact size neutron flux monitor has been developed incorporating standard boards developed for smart radiation monitors. The sensitivity of the monitors is 0.4cps/nV. It has been tested up to 2075 nV flux with standard neutron sources. It shows convincing results even in high flux areas like 6m away from the accelerator in RMC (Parel) for 106/107 nV. These monitors have a focal and remote display, alarm function with potential free contacts for centralized control and additional provision of connectivity via RS485/Ethernet. This paper describes the construction, working and results of the above flux monitor

  18. Two phase flow instabilities in horizontal straight tube evaporator

    OpenAIRE

    2010-01-01

    Abstract It is essential to ensure the stability of a refrigeration system if the oscillation in evaporation process is the primary cause for the whole system instability. This paper is concerned with an experimental investigation of two phase flow instabilities in a horizontal straight tube evaporator of a refrigeration system. The relationship between pressure drop and mass flow with constant heat flux and evaporation pressure is measured and determined. It is found that there is...

  19. Film Condensation of Steam on Externally Finned Horizontal Tubes.

    Science.gov (United States)

    1985-03-01

    34. 7 e - Fin Height -F - Property Function g - Acceleration of Gravity G - Condensate Flow Rate Gf - Rate of Condensate Formation h - Steam...interaction of gravitational and surface-tension forces lead to complex - three-dimensional flow patterns, which are further dependent on fin spacing, height...and thickness. Other variables include heat flux, vapor shear, tube diameter, fin shape and fuid properties just to name a few. In view ofL the

  20. Ion beam characteristics of a gas filled accelerator tube

    International Nuclear Information System (INIS)

    Berg, R.S.; Bickes, R.W. Jr.; Boers, J.E.; Shope, L.A.

    1980-01-01

    A gas filled tube used to produce a pulsed neutron flux with the D(T, 4 He)n reaction is described. Deuterium and tritium ions generated in a reflex discharge are extracted and accelerated to 100 keV by means of an accelerator electrode onto a deutero-tritide target electrode. The electrodes are designed to focus the ion beam onto the target. Total tube currents consisting of extracted ions, unsuppressed secondary electrons, and ions generated by interactions with the background gas are typically 100mA. Characteristics of the extracted ion beam are discussed. Accelerating voltages greater than 50kV are required to focus the beam through the accelerator aperture for configurations that give beams with the proper energy density at the target. The perveance of the beam is defined. Maximum perveance values are 2 to 10 nanopervs. Tube focussing and neutron production characteristics are described

  1. Video Meteor Fluxes

    Science.gov (United States)

    Campbell-Brown, M. D.; Braid, D.

    2011-01-01

    The flux of meteoroids, or number of meteoroids per unit area per unit time, is critical for calibrating models of meteoroid stream formation and for estimating the hazard to spacecraft from shower and sporadic meteors. Although observations of meteors in the millimetre to centimetre size range are common, flux measurements (particularly for sporadic meteors, which make up the majority of meteoroid flux) are less so. It is necessary to know the collecting area and collection time for a given set of observations, and to correct for observing biases and the sensitivity of the system. Previous measurements of sporadic fluxes are summarized in Figure 1; the values are given as a total number of meteoroids striking the earth in one year to a given limiting mass. The Gr n et al. (1985) flux model is included in the figure for reference. Fluxes for sporadic meteoroids impacting the Earth have been calculated for objects in the centimeter size range using Super-Schmidt observations (Hawkins & Upton, 1958); this study used about 300 meteors, and used only the physical area of overlap of the cameras at 90 km to calculate the flux, corrected for angular speed of meteors, since a large angular speed reduces the maximum brightness of the meteor on the film, and radiant elevation, which takes into account the geometric reduction in flux when the meteors are not perpendicular to the horizontal. They bring up corrections for both partial trails (which tends to increase the collecting area) and incomplete overlap at heights other than 90 km (which tends to decrease it) as effects that will affect the flux, but estimated that the two effects cancelled one another. Halliday et al. (1984) calculated the flux of meteorite-dropping fireballs with fragment masses greater than 50 g, over the physical area of sky accessible to the MORP fireball cameras, counting only observations in clear weather. In the micron size range, LDEF measurements of small craters on spacecraft have been used to

  2. Free compression tube. Applications

    Science.gov (United States)

    Rusu, Ioan

    2012-11-01

    During the flight of vehicles, their propulsion energy must overcome gravity, to ensure the displacement of air masses on vehicle trajectory, to cover both energy losses from the friction between a solid surface and the air and also the kinetic energy of reflected air masses due to the impact with the flying vehicle. The flight optimization by increasing speed and reducing fuel consumption has directed research in the aerodynamics field. The flying vehicles shapes obtained through studies in the wind tunnel provide the optimization of the impact with the air masses and the airflow along the vehicle. By energy balance studies for vehicles in flight, the author Ioan Rusu directed his research in reducing the energy lost at vehicle impact with air masses. In this respect as compared to classical solutions for building flight vehicles aerodynamic surfaces which reduce the impact and friction with air masses, Ioan Rusu has invented a device which he named free compression tube for rockets, registered with the State Office for Inventions and Trademarks of Romania, OSIM, deposit f 2011 0352. Mounted in front of flight vehicles it eliminates significantly the impact and friction of air masses with the vehicle solid. The air masses come into contact with the air inside the free compression tube and the air-solid friction is eliminated and replaced by air to air friction.

  3. Shock tube Multiphase Experiments

    Science.gov (United States)

    Middlebrooks, John; Allen, Roy; Paudel, Manoj; Young, Calvin; Musick, Ben; McFarland, Jacob

    2017-11-01

    Shock driven multiphase instabilities (SDMI) are unique physical phenomena that have far-reaching practical applications in engineering and science. The instability is present in high energy explosions, scramjet combustors, and supernovae events. The SDMI arises when a multiphase interface is impulsively accelerated by the passage of a shockwave. It is similar in development to the Richtmyer-Meshkov (RM) instability however, particle-to-gas coupling is the driving mechanism of the SDMI. As particle effects such as lag and phase change become more prominent, the SDMI's development begins to significantly deviate from the RM instability. We have developed an experiment for studying the SDMI in our shock tube facility. In our experiments, a multiphase interface is created using a laminar jet and flowed into the shock tube where it is accelerated by the passage of a planar shockwave. The interface development is captured using CCD cameras synchronized with planar laser illumination. This talk will give an overview of new experiments conducted to examine the development of a shocked cylindrical multiphase interface. The effects of Atwood number, particle size, and a second acceleration (reshock) of the interface will be discussed.

  4. Design Considerations of Permanent Magnet Transverse Flux Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

    2011-01-01

    Permanent magnet transverse flux machine (PMTFM) is well known for its high torque density and is interested in various direct-drive applications. Due to its complicated 3-D flux components, design and design optimization of a PMTFM is more difficult and time consuming than for radial flux...... electrical machines. This paper addresses two important design considerations for PMTFM—the influence of permanent magnet leakage flux, which plays an important role in the determination of machine output torque, and the leakage inductance. A new simple method to provide a quick estimation of the armature...

  5. Critical heat flux in natural convection cooled TRIGA reactors with hexagonal bundle

    International Nuclear Information System (INIS)

    Yang, J.; Avery, M.; De Angelis, M.; Anderson, M.; Corradini, M.; Feldman, E. E.; Dunn, F. E.; Matos, J. E.

    2012-01-01

    A three-rod bundle Critical Heat Flux (CHF) study at low flow, low pressure, and natural convection condition has been conducted, simulating TRIGA reactors with the hexagonally configured core. The test section is a custom-made trefoil shape tube with three identical fuel pin heater rods located symmetrically inside. The full scale fuel rod is electrically heated with a chopped-cosine axial power profile. CHF experiments were carried out with the following conditions: inlet water subcooling from 30 K to 95 K; pressure from 110 kPa to 230 kPa; mass flux up to 150 kg/m 2 s. About 50 CHF data points were collected and compared with a few existing CHF correlations whose application ranges are close to the testing conditions. Some tests were performed with the forced convection to identify the potential difference between the CHF under the natural convection and forced convection. The relevance of the CHF to test parameters is investigated. (authors)

  6. Analysis of coolant flow in central tube of WWER-440 fuel assemblies

    International Nuclear Information System (INIS)

    Zsiros, G.; Toth, S.; Attila Aszodi, A.

    2011-01-01

    Three dimensional computational fluid dynamics model has been built to investigate the coolant flow in the central tube of the WWER-440 fuel assemblies. The model was verified based on measured data of the Kurchatov Institute. With the model calculations were performed for two fuel assemblies used in PAKS NPP. One of them has symmetrical and another has inclined pin power profile. Ratios of the outlet mass fluxes of the central tube to the inlet mass fluxes of the rod bundle were determined. Heat up ratios of the tube and rod bundle flows were calculated too. Sensitivity of the results on the assembly power distribution, inlet temperature and mass flow rate was investigated. The results of these simulations can be used as boundary conditions of central tube in studies of coolant mixing in fuel assembly heads. (Authors)

  7. Solar Magnetic Flux Ropes

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The most probable initial magnetic configuration of a CME is a flux rope consisting of twisted field lines which fill the whole volume of a dark coronal cavity. The flux ropes can be in stable equilibrium in the coronal magnetic field for weeks and even months, but suddenly they lose their stability and erupt with ...

  8. Bacterial Biofilms in Jones Tubes.

    Science.gov (United States)

    Ahn, Eric S; Hauck, Matthew J; Kirk Harris, Jonathan; Robertson, Charles E; Dailey, Roger A

    To investigate the presence and microbiology of bacterial biofilms on Jones tubes (JTs) by direct visualization with scanning electron microscopy and polymerase chain reaction (PCR) of representative JTs, and to correlate these findings with inflammation and/or infection related to the JT. In this study, prospective case series were performed. JTs were recovered from consecutive patients presenting to clinic for routine cleaning or recurrent irritation/infection. Four tubes were processed for scanning electron microscopy alone to visualize evidence of biofilms. Two tubes underwent PCR alone for bacterial quantification. One tube was divided in half and sent for scanning electron microscopy and PCR. Symptoms related to the JTs were recorded at the time of recovery. Seven tubes were obtained. Five underwent SEM, and 3 out of 5 showed evidence of biofilms (60%). Two of the 3 biofilms demonstrated cocci and the third revealed rods. Three tubes underwent PCR. The predominant bacteria identified were Pseudomonadales (39%), Pseudomonas (16%), and Staphylococcus (14%). Three of the 7 patients (43%) reported irritation and discharge at presentation. Two symptomatic patients, whose tubes were imaged only, revealed biofilms. The third symptomatic patient's tube underwent PCR only, showing predominantly Staphylococcus (56%) and Haemophilus (36%) species. Two of the 4 asymptomatic patients also showed biofilms. All symptomatic patients improved rapidly after tube exchange and steroid antibiotic drops. Bacterial biofilms were variably present on JTs, and did not always correlate with patients' symptoms. Nevertheless, routine JT cleaning is recommended to treat and possibly prevent inflammation caused by biofilms.

  9. YouTube and 'psychiatry'.

    Science.gov (United States)

    Gordon, Robert; Miller, John; Collins, Noel

    2015-12-01

    YouTube is a video-sharing website that is increasingly used to share and disseminate health-related information, particularly among younger people. There are reports that social media sites, such as YouTube, are being used to communicate an anti-psychiatry message but this has never been confirmed in any published analysis of YouTube clip content. This descriptive study revealed that the representation of 'psychiatry' during summer 2012 was predominantly negative. A subsequent smaller re-analysis suggests that the negative portrayal of 'psychiatry' on YouTube is a stable phenomenon. The significance of this and how it could be addressed are discussed.

  10. Radiation-resistant camera tube

    International Nuclear Information System (INIS)

    Kuwahata, Takao; Manabe, Sohei; Makishima, Yasuhiro

    1982-01-01

    It was a long time ago that Toshiba launched on manufacturing black-and-white radiation-resistant camera tubes employing nonbrowning face-plate glass for ITV cameras used in nuclear power plants. Now in compliance with the increasing demand in nuclear power field, the Company is at grips with the development of radiation-resistant single color-camera tubes incorporating a color-stripe filter for color ITV cameras used under radiation environment. Herein represented are the results of experiments on characteristics of materials for single color-camera tubes and prospects for commercialization of the tubes. (author)

  11. X-ray tube monitor apparatus

    International Nuclear Information System (INIS)

    Holland, W.P.; Pellergrino, A.

    1981-01-01

    An x-ray tube with a rotating anode target is provided with a detector of x-rays located outside a port of a housing of the tube and positioned at or near a tangent line to the radiating surface for observing variations in the radiation intensity due to rotation of the target, the variations being pronounced due to the heel effect of the radiation pattern. The x-ray detector can employ a scintillation material and be coupled by a light guide to a photodetector which is removed from the path of the radiation and detects scintillations of the x-ray detector. Alternatively, the photodetector and light pipe may be replaced by a detector of germanium, silicon or an ion chamber which converts x-ray photons directly to an electric current. An electronic unit determines the speed of rotation from the electric signal and can also, by fourier transform and signature analysis techniques, monitor the state of the radiating surface. (author)

  12. Measurement of Periodical Contraction of Cultured Muscle Tube with Laser

    Directory of Open Access Journals (Sweden)

    Jun Takase

    2009-06-01

    Full Text Available Periodical contraction of a cultured muscle tube has been measured with laser in vitro. C2C12 (mouse myoblast cell line was cultured with High-glucose Dulbecco's Modified Eagle's Medium on a dish to make muscle tubes. Differentiation from myoblasts to myotubes was induced with an additional horse serum. Repetitive contraction of the tube was generated by electric pulses lower than sixty volts of amplitude with one milli-second of width through the electrodes of platinum, and observed with a phase-contrast microscope. A laser beam of 632.8 nm wavelength was restricted to 0.096 mm diameter, and applied to the muscle tubes on the bottom of the culture dish. Fluctuating intensity of the transmitted laser beam through the periodically contracting muscle tubes was measured, and its spectrum was analyzed. The analyzed data show that the repetitive contraction is synchronized with stimulation of the periodical electric pulses between 0.2 s and 2 s.

  13. Learning from YouTube [Video Book

    Science.gov (United States)

    Juhasz, Alexandra

    2011-01-01

    YouTube is a mess. YouTube is for amateurs. YouTube dissolves the real. YouTube is host to inconceivable combos. YouTube is best for corporate-made community. YouTube is badly baked. These are a few of the things Media Studies professor Alexandra Juhasz (and her class) learned about YouTube when she set out to investigate what actually happens…

  14. Nitric oxide fluxes from an agricultural soil using a flux-gradient method

    Science.gov (United States)

    Taylor, N. M.; Wagner-Riddle, C.; Thurtell, G. W.; Beauchamp, E. G.

    1999-05-01

    Soil emission of nitric oxide may be a significant source of NOx in rural areas. Agricultural practices may enhance these emissions by addition of nitrogen fertilizers. A system that enables continuous measurement of NO fluxes from agricultural surfaces using the flux-gradient method was developed. Hourly differences in NO concentrations in air sampled at two intake heights (0.6 and 1 m) were determined using a chemiluminescence analyzer. Eddy diffusivities were determined using wind profiles (cup anemometers), and stability corrections calculated using a 5 cm path sonic anemometer. Fast switching of sampling between air intake heights (every 30 s) and determination of concentration values at a frequency of 2 Hz minimized the errors due to fluctuations in background concentration. Low travel times for air samples in the tubing (˜8 s) were estimated to result in small errors in flux values (chemical reactions. The overall resolution of the system was estimated as ˜1 ng N m-2s-1. NO fluxes from a bare soil were measured quasi-continuously from January to June 1995 at Elora, Canada, comprising a total of 1833 hourly values. Daily NO fluxes before nitrogen fertilization were small, increasing after nitrogen fertilizer was added (>10 ng N m-2 s-1). Monthly NO fluxes estimated were similar to those observed in previous studies. The designed system could be easily modified to measure NOx and NO fluxes by using an additional chemiluminescence analyzer. The system also could be adapted to measure fluxes sequentially from various plots, enabling testing of agricultural practices on NO emissions.

  15. An Intraoral Miniature X-ray Tube Based on Carbon Nanotubes for Dental Radiography

    OpenAIRE

    Hyun Jin Kim; Hyun Nam Kim; Hamid Saeed Raza; Han Beom Park; Sung Oh Cho

    2016-01-01

    A miniature X-ray tube based on a carbon-nanotube electron emitter has been employed for the application to a dental radiography. The miniature X-ray tube has an outer diameter of 7 mm and a length of 47 mm. The miniature X-ray tube is operated in a negative high-voltage mode in which the X-ray target is electrically grounded. In addition, X-rays are generated only to the teeth directions using a collimator while X-rays generated to other directions are shielded. Hence, the X-ray tube can be ...

  16. Tube to tube excursive instability - sensitivities and transients

    International Nuclear Information System (INIS)

    Brown, M.; Layland, M.W.

    1980-01-01

    A simple basic analysis of excursive instability in a boiler tube shows how it depends upon operating conditions and physical properties. A detailed mathematical model of an AGR boiler is used to conduct a steady state parameter sensitivity survey. It is possible from this basis to anticipate the effects of changes in operating conditions and changes in design parameters upon tube to tube stability. Dynamic responses of tubes operating near the stability threshold are examined using a mathematical model. Simulated excursions are triggered by imparting small abrupt pressure changes on the boiler inlet pressure. The influences of the magnitude of the pressure change, waterside friction factor and gas side coupling between tubes are examined. (author)

  17. Nasogastric tube syndrome induced by an indwelling long intestinal tube.

    Science.gov (United States)

    Sano, Naoki; Yamamoto, Masayoshi; Nagai, Kentaro; Yamada, Keiichi; Ohkohchi, Nobuhiro

    2016-04-21

    The nasogastric tube (NGT) has become a frequently used device to alleviate gastrointestinal symptoms. Nasogastric tube syndrome (NTS) is an uncommon but potentially life-threatening complication of an indwelling NGT. NTS is characterized by acute upper airway obstruction due to bilateral vocal cord paralysis. We report a case of a 76-year-old man with NTS, induced by an indwelling long intestinal tube. He was admitted to our hospital for treatment of sigmoid colon cancer. He underwent sigmoidectomy to release a bowel obstruction, and had a long intestinal tube inserted to decompress the intestinal tract. He presented acute dyspnea following prolonged intestinal intubation, and bronchoscopy showed bilateral vocal cord paralysis. The NGT was removed immediately, and tracheotomy was performed. The patient was finally discharged in a fully recovered state. NTS be considered in patients complaining of acute upper airway obstruction, not only with a NGT inserted but also with a long intestinal tube.

  18. A New Resonance Tube

    Science.gov (United States)

    Bates, Alan

    2017-12-01

    The measurement of the speed of sound in air with the resonance tube is a popular experiment that often yields accurate results. One approach is to hold a vibrating tuning fork over an air column that is partially immersed in water. The column is raised and lowered in the water until the generated standing wave produces resonance: this occurs at the point where sound is perceived to have maximum loudness, or at the point where the amplitude of the standing wave has maximum value, namely an antinode. An antinode coincides with the position of the tuning fork, beyond the end of the air column, which consequently introduces an end correction. One way to minimize this end correction is to measure the distance between consecutive antinodes.

  19. Piezoelectric Rotary Tube Motor

    Science.gov (United States)

    Fisher, Charles D.; Badescu, Mircea; Braun, David F.; Culhane, Robert

    2011-01-01

    A custom rotary SQUIGGLE(Registered TradeMark) motor has been developed that sets new benchmarks for small motor size, high position resolution, and high torque without gear reduction. Its capabilities cannot be achieved with conventional electromagnetic motors. It consists of piezoelectric plates mounted on a square flexible tube. The plates are actuated via voltage waveforms 90 out of phase at the resonant frequency of the device to create rotary motion. The motors were incorporated into a two-axis postioner that was designed for fiber-fed spectroscopy for ground-based and space-based projects. The positioner enables large-scale celestial object surveys to take place in a practical amount of time.

  20. Pressure tube reactor

    International Nuclear Information System (INIS)

    Matsumoto, Tomoyuki; Fujino, Michihira.

    1980-01-01

    Purpose: To equalize heavy water flow distribution by providing a nozzle for externally injecting heavy water from a vibration preventive plate to the upper portion to feed the heavy water in a pressure tube reactor and swallowing up heavy water in a calandria tank to supply the heavy water to the reactor core above the vibration preventive plate. Constitution: A moderator injection nozzle is mounted on the inner wall of a calandria tank. Heavy water is externally injected above the vibration preventive plate, and heavy water in the calandria tank is swallowed up to supply the heavy water to the core reactor above the vibration preventive plate. Therefore, the heavy water flow distribution can be equalized over the entire reactor core, and the distribution of neutron absorber dissolved in the heavy water is equalized. (Yoshihara, H.)

  1. Primary Fallopian Tube Carcinoma

    Directory of Open Access Journals (Sweden)

    Prasad K Shetty

    2011-01-01

    Full Text Available Primary Fallopian Tube Carcinoma (PFTC is rare and accounts for about 0.3% of all gynecologic cancers. Less than 1500 cases have been reported in the literature. It arises in postmenopausal women and typically presents with abdominal pelvic pain, vaginal bleeding and watery discharge. However, a correct diagnosis is rarely achieved preoperative, and in many cases, the diagnosis is made after incidental surgery for unrelated conditions commonly being ovarian carcinoma . Compared with ovarian carcinoma, PFTC more often presents at early stages, but it has a worse prognosis. PFTC is usually managed in the same manner as ovarian cancer. We report a case of Left PFTC that presented as Left ovarian mass, and we briefly review the literature.

  2. Development and test evaluation of duplex steam reformer tube

    International Nuclear Information System (INIS)

    Allen, D.C.; Meyer, D.J.; Pflasterer, G.R.

    1980-01-01

    For HTR applications involving a steam reformer (SR), it is uncertain whether an intermediate heat exchanger (IHX) is required. There are several system configurations that could be developed for the application of nuclear heat using the steam reformer reaction. The considerations (advantages vs. disadvantages) for each of the system configurations are summarized. The approach that technically and economically appears to be the most attractive, in studies conducted by General Electric, combines the SR process heat exchanger and the IHX in a single component using a duplex tube. A central question concerning the duplex tube concept is whether the design would provide adequate leak monitoring capability and significant reduction in tritium and hydrogen diffusion, while introducing only a small increase in overall temperature difference from the helium to the process gas. A cooperative GE-KFA effort was undertaken to develop, fabricate, test, and evaluate a duplex steam reformer tube. GE was responsible for the development and fabrication of the tube, and KFA was responsible for testing the tube in the EVA I facility at Juelich. Both GE and KFA are evaluating the thermochemical and metallurgical test data. Actual fabrication of the tube was performed by Foster-Wheeler in accordance with the GE design. This paper reviews the highlights of the fabrication development and preliminary evaluation of the test data

  3. Gamma irradiation effect on thermo shrink polyethylene tube: Case study

    International Nuclear Information System (INIS)

    Naurah Mat Isa; Siti Zulaiha Hairaldin; Mohd Yusof Hamzah; Zulkafli Ghazali

    2010-01-01

    The production technology of heat shrinkable tubes is based on the industrial usage of so-called memory effect in some polymers. Many polymers can be rendered heat shrinkable, particularly polyolefins by introducing crosslinking in the polymer backbone. Heat shrinkable tubes and moulded parts provide mechanical and/or chemical and/or electrical protection. . In this work, irradiation from Co-60 was used to impart crosslinking in polymer and thus modify their mechanical and thermal properties. Heat shrinkable or thermo shrink polyethylene (PE) tube with diameter 6.4 mm was selected to evaluate crosslinking behaviour from the gamma irradiation exposure at 5 different doses (120, 140, 160, 200 and 220 kGy). The gel content (%), tensile properties and thermal behavior and stability of the tubes were measured using DSC and TGA. Tubes irradiated at 140 kGy and 160 kGy showed better tensile properties than those at 120, 200 and 220 kGy doses. Maximum percent of crystallization was observed at 160 kGy and temperature required to crystallize is lower than melting temperature due to changes in molecular orientation. Thermal decomposition of the irradiated tubes occurred at 430-450 degree Celsius which is lower than the unirradiated sample. Gel content analysis for samples irradiated at 180-220 kGy yield up to 30 to 40 % gel fraction. Although the gel fractions are higher than other dose, the samples are expected to experience chain scission presumably due to localized gel formation. (author)

  4. Eddy-current inspection of shuttle heat exchanger tube welds

    International Nuclear Information System (INIS)

    Dodd, C.V.; Scott, G.W.; Chitwood, L.D.

    1989-01-01

    This goal of this project was to develop the system necessary to demonstrate in the laboratory that an eddy-current system can inspect the tubes and welds described above, screening for the existence of flaws equal in size to, or larger than, the target flaw. The laboratory system was to include the probe necessary to traverse the tubing, the electronics to drive (i.e., electrically excite) the probe and receive and process signals from it, a data display, data recording and playback devices, and microprocessor software or firmware necessary to operate the system. 5 refs., 9 figs., 2 tabs

  5. Investigations into the dynamic behaviour of finned tube heat exchangers

    International Nuclear Information System (INIS)

    Sandbrink, J.; Stegemann, D.

    1981-01-01

    Atmospheric disturbances due to thunder storms, side wind effects on the shell or ground inversion can impair the heat dissipation of a cooling tower. These effects react on the overall power plant, which is reflected in the varied electrical output. This uncontrolled behaviour has been investigated in detail for the case of a boiling water reactor nuclear power station with indirect natural draught dry cooling and compared with controlled performance. A computer model, which has been checked out by means of experimental investigations on three different types of tube, is presented to describe the dynamic behaviour of finned tube heat exchangers. (orig.) [de

  6. Actively-stabilized photomultiplier tube base for vacuum operation

    International Nuclear Information System (INIS)

    Bryan, M.A; Morris, C.L.; Idzorek, G.C.

    1992-01-01

    An actively stabilized photomultiplier tube (PMT) base design for an Amperex XP-2262B PMT is described. Positive-negative-positive transistors are used as low-impedance current sources to maintain constant voltages on the last three dynodes. This technique results in a highly stable, low-power tube base ideal for use with low-duty-factor beams, such as those found at the Clinton P. Anderson Meson Physics Facility. Furthermore, because of the low power usage of this large design, these bases can be sealed in a heat-conductive, electrically insulating material and used in a vacuum

  7. Neutron accelerator tube having improved ionization section

    International Nuclear Information System (INIS)

    Givens, W.W.

    1982-01-01

    A neutron accelerator tube is described having a target section, an ionization section, and a replenisher section for supplying accelerator gas to the ionization section. The ionization section is located between the target and the replenisher section and includes an ionization chamber adapted to receive accelerator gas from the replenisher section. The ionization section further includes spaced cathodes having opposed active surfaces exposed to the interior of the ionization chamber. An anode is located intermediate the cathodes whereby in response to an applied positive voltage, electrons created by field emission are transmitted between the opposed active surfaces of the cathodes and produce the emission of secondary electrons. The active surface of at least one of the cathodes is formulated of a material having a secondary electron emission factor of at least one cathode member located in the tube adjacent to th replenisher section may have a protuberant portion extending axially into the ionization chamber. The other cathode spaced from the first cathode member in the direction of the target has an aperture therein along the axis of the protuberant portion. An annular magnet extends around the exterior of the ionization chamber and envelops the anode member. Means are provided to establish a high permeability magnetic flux path extending outwardly from the opposed poles from the magnet to the active surfaces of the cathode members

  8. Neutron accelerator tube having improved ionization section

    International Nuclear Information System (INIS)

    Givens, W.W.

    1981-01-01

    A neutron accelerator tube having a target section, an ionization section, and a replenisher section for supplying accelerator gas to the ionization section. The ionization section is located between the target and the replenisher section and includes an ionization chamber adapted to receive accelerator gas from the replenisher section. The ionization section further includes spaced cathodes having opposed active surfaces exposed to the interior of the ionization chamber. An anode is located intermediate the cathodes whereby in response to an applied positive voltage, electrons created by field emmission are transmitted between the opposed active surfaces of the cathodes and produce the emission of secondary electrons. The active surface of at least one of the cathodes is formulated of a material having a secondary electron emission factor of at least 2. One cathode member located in the tube adjacent to the replenisher section may have a protuberant portion extending axially into the ioization chamber. The other cathode spaced from the first cathode member in the direction of the target has an aperture therein along the axis of the protuberant portion. An annular magnet extends around the exterior of the ionization chamber and envelops the anode member. Means are provided to establish a high permeability magnetic flux path extending outwardly from the opposed poles from the magnet to the active surfaces of the cathode members

  9. Self-sensing concrete-filled FRP tubes using FBG strain sensors

    Science.gov (United States)

    Yan, Xin; Li, Hui

    2007-07-01

    Concrete-filled fiber-reinforced polymer (FRP) tube is a type of newly developed structural column. It behaves brittle failure at its peak strength, and so the health monitoring on the hoop strain of the FRP tube is essential for the life cycle safety of the structure. Herein, three types of FRP tubes including 5-ply tube, 2-ply tube with local reinforcement and FRP-steel composite tube were embedded with the optic fiber Bragg grating (FBG) strain sensors in the inter-ply of FRP or the interface between FRP and steel in the middle height and the hoop direction. The compressive behaviors of the concrete-filled FRP tubes were experimentally studied. The hoop strains of the FRP tubes were recorded in real time using the embedded FBG strain sensors as well as the embedded or surface electric resistance strain gauges. Results indicated that the FBG strain sensors can faithfully record the hoop strains of the FRP tubes in compression as compared with the embedded or surface electric resistance strain gauges, and the strains recorded can reach more than μɛ.

  10. Real Time Flux Control in PM Motors

    Energy Technology Data Exchange (ETDEWEB)

    Otaduy, P.J.

    2005-09-27

    Significant research at the Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) is being conducted to develop ways to increase (1) torque, (2) speed range, and (3) efficiency of traction electric motors for hybrid electric vehicles (HEV) within existing current and voltage bounds. Current is limited by the inverter semiconductor devices' capability and voltage is limited by the stator wire insulation's ability to withstand the maximum back-electromotive force (emf), which occurs at the upper end of the speed range. One research track has been to explore ways to control the path and magnitude of magnetic flux while the motor is operating. The phrase, real time flux control (RTFC), refers to this mode of operation in which system parameters are changed while the motor is operating to improve its performance and speed range. RTFC has potential to meet an increased torque demand by introducing additional flux through the main air gap from an external source. It can augment the speed range by diverting flux away from the main air gap to reduce back-emf at high speeds. Conventional RTFC technology is known as vector control [1]. Vector control decomposes the stator current into two components; one that produces torque and a second that opposes (weakens) the magnetic field generated by the rotor, thereby requiring more overall stator current and reducing the efficiency. Efficiency can be improved by selecting a RTFC method that reduces the back-emf without increasing the average current. This favors methods that use pulse currents or very low currents to achieve field weakening. Foremost in ORNL's effort to develop flux control is the work of J. S. Hsu. Early research [2,3] introduced direct control of air-gap flux in permanent magnet (PM) machines and demonstrated it with a flux-controlled generator. The configuration eliminates the problem of demagnetization because it diverts all the flux from the

  11. Characterization of tube support alloys

    International Nuclear Information System (INIS)

    Vaia, A.R.

    1985-01-01

    The involvement and relationship of carbon steel corrosion products in the tube denting phenomenon promoted an intensive research effort to: 1) understand, reproduce, and arrest the denting process, and 2) evaluate alternative tube support materials to provide additional corrosion resistance. The paper summarizes a corrosion testing program for the verification of type 405 stainless steel under acid or all volatile treatment conditions

  12. Flaming on YouTube

    NARCIS (Netherlands)

    Moor, Peter J.; Heuvelman, A.; Verleur, R.

    2010-01-01

    In this explorative study, flaming on YouTube was studied using surveys of YouTube users. Flaming is defined as displaying hostility by insulting, swearing or using otherwise offensive language. Three general conclusions were drawn. First, although many users said that they themselves do not flame,

  13. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Embedded video for NEI YouTube Videos: Amblyopia NEI Home Contact Us A-Z Site Map NEI on Social Media Information in Spanish (Información en español) Website, ...

  14. 27 CFR 40.352 - Cigarette tubes.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Cigarette tubes. 40.352... OF THE TREASURY (CONTINUED) TOBACCO MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes § 40.352 Cigarette tubes. Cigarette tubes...

  15. Directed flux motor

    Science.gov (United States)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2011-01-01

    A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.

  16. High efficiency fluorescent tubes. An efficient solution for the economical lighting of industrial and tertiary buildings; Les tubes fluorescents haut rendement. Une solution performante pour l'eclairage economique des locaux indutriels et tertiaires

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    Fluorescent lamps are low pressure mercury vapor lamps (discharge lamps). The high efficiency fluorescent tubes have a greater lighting efficiency thanks to the integration of tri-chromatic powders emitting in the three fundamental colors (red, green, blue). Their useful lifetime is exceptionally long (90% of their initial flux after 12000 hours of use), and they require a lower maintenance with respect to the traditional fluorescent tubes. This document presents the characteristics and advantages of high efficiency fluorescent tubes for professional use and their cost and performance with respect to standard fluorescent tubes. (J.S.)

  17. Critical heat flux on micro-structured zircaloy surfaces for flow boiling of water at low pressures

    International Nuclear Information System (INIS)

    Haas, C.; Miassoedov, A.; Schulenberg, T.; Wetzel, T.

    2012-01-01

    The influence of surface structure on critical heat flux for flow boiling of water was investigated for Zircaloy tubes in a vertical annular test section. The objectives were to find suitable surface modification processes for Zircaloy tubes and to test their critical heat flux performance in comparison to the smooth tube. Surface structures with micro-channels, porous layer, oxidized layer, and elevations in micro- and nano-scale were produced on a section of a Zircaloy cladding tube. These modified tubes were tested in an internally heated vertical annulus with a heated length of 326 mm and an inner and outer diameter of 9.5 and 18 mm. The experiments were performed with mass fluxes of 250 and 400 kg/(m 2 s), outlet pressures between 120 and 300 kPa, and constant inlet subcooling enthalpy of 167 kJ/kg. Only a small influence of modified surface structures on critical heat flux was observed for the pressure of 120 kPa in the present test section geometry. However, with increasing pressure the critical heat flux could increase up to 29% using the surface structured tubes with micro-channels, porous and oxidized layers. Capillary effects and increased nucleation site density are assumed to improve the critical heat flux performance. (authors)

  18. Inner surface modification of a tube by magnetic glow-arc plasma source ion implantation

    International Nuclear Information System (INIS)

    Zhang Guling; Chinese Academy of Sciences, Beijing; Wang Jiuli; Feng Wenran; Chen Guangliang; Gu Weichao; Niu Erwu; Fan Songhua; Liu Chizi; Yang Size; Wu Xingfang

    2006-01-01

    A new method named the magnetic glow-arc plasma source ion implantation (MGA-PSII) is proposed for inner surface modification of tubes. In MGA-PSII, under the control of an axial magnetic field, which is generated by an electric coil around the tube sample, glow arc plasma moves spirally into the tube from its two ends. A negative voltage applied on the tube realized its inner surface implantation. Titanium nitride (TiN) films are prepared on the inner surface of a stainless steel tube in diameter 90 mm and length 600 mm. Hardness tests show that the hardness at the tube centre is up to 20 GPa. XRD, XPS and AES analyses demonstrate that good quality of TiN films can be achieved. (authors)

  19. Inner Surface Modification of a Tube by Magnetic Glow-Arc Plasma Source Ion Implantation

    Science.gov (United States)

    Zhang, Gu-Ling; Wang, Jiu-Li; Wu, Xing-Fang; Feng, Wen-Ran; Chen, Guang-Liang; Gu, Wei-Chao; Niu, Er-Wu; Fan, Song-Hua; Liu, Chi-Zi; Yang, Si-Ze

    2006-05-01

    A new method named the magnetic glow-arc plasma source ion implantation (MGA-PSII) is proposed for inner surface modification of tubes. In MGA-PSII, under the control of an axial magnetic field, which is generated by an electric coil around the tube sample, glow arc plasma moves spirally into the tube from its two ends. A negative voltage applied on the tube realized its inner surface implantation. Titanium nitride (TiN) films are prepared on the inner surface of a stainless steel tube in diameter 90 mm and length 600 mm. Hardness tests show that the hardness at the tube centre is up to 20 GPa. XRD, XPS and AES analyses demonstrate that good quality of TiN films can be achieved.

  20. Tokamak disruption heat flux simulator

    International Nuclear Information System (INIS)

    Langhoff, M.; Hess, G.; Gahl, J.; Ingram, R.

    1990-01-01

    A coaxial plasma gun system, operating in the deflagration mode, has been built and fired at the University of New Mexico. This system, powered by a 100 kJ capacitor bank, was designed to give a variable pulse length of approximately 50-100 us. The gun is intended to deliver to a target an energy deposition density of 1 kJ per cm 2 via impact with a deuterium plasma possessing a highly directed energy. This system should simulate on the target, over an area of approximately 10 cm 2 , the heat flux of a tokamak plasma disruption on plasma facing components. Current diagnostics for the system are rather rudimentary but sufficient for determination of plasma pulse characteristics and energy transfer to target. Electrical measurements include bank voltage measured via resistive voltage dividers, and bank current measured via Rogowski coil. The shape of the plasma, its position relative to the target area, and the final impact area, is determined via open-shutter photography and the use of witness plates. Total energy deposited onto targets will be determined through simple calorimetry and careful target mass measurements. Preliminary results describing the ablation of carbon targets exposed to disruption like heat fluxes will be presented as well as a description of the experimental apparatus

  1. HF electronic tubes. Technologies, grid tubes and klystrons

    International Nuclear Information System (INIS)

    Lemoine, Th.

    2009-01-01

    This article gives an overview of the basic technologies of electronic tubes: cathodes, electronic optics, vacuum and high voltage. Then the grid tubes, klystrons and inductive output tubes (IOT) are introduced. Content: 1 - context and classification; 2 - electronic tube technologies: cathodes, electronic optics, magnetic confinement (linear tubes), periodic permanent magnet (PPM) focussing, collectors, depressed collectors; 3 - vacuum technologies: vacuum quality, surface effects and interaction with electrostatic and RF fields, secondary emission, multipactor effect, thermo-electronic emission; 4 - grid tubes: operation of a triode, tetrodes, dynamic operation and classes of use, 'common grid' and 'common cathode' operation, ranges of utilisation and limitations, operation of a tetrode on unadjusted load, lifetime of a tetrode, uses of grid tubes; 5 - klystrons: operation, impact of space charge, multi-cavity klystrons, interaction efficiency, extended interaction klystrons, relation between interaction efficiency, perveance and efficiency, ranges of utilization and power limitations, multi-beam klystrons and sheet beam klystrons, operation on unadjusted load, klystron band pass and lifetime, uses; 6 - IOT: principle of operation, ranges of utilisation and limitations, interaction efficiency and depressed collector IOT, IOT lifetime and uses. (J.S.)

  2. Heat transfer enhancement in a tube using circular cross sectional rings separated from wall

    International Nuclear Information System (INIS)

    Ozceyhan, Veysel; Gunes, Sibel; Buyukalaca, Orhan; Altuntop, Necdet

    2008-01-01

    A numerical study was undertaken for investigating the heat transfer enhancement in a tube with the circular cross sectional rings. The rings were inserted near the tube wall. Five different spacings between the rings were considered as p = d/2, p = d, p = 3d/2, p = 2d and p = 3d. Uniform heat flux was applied to the external surface of the tube and air was selected as working fluid. Numerical calculations were performed with FLUENT 6.1.22 code, in the range of Reynolds number 4475-43725. The results obtained from a smooth tube were compared with those from the studies in literature in order to validate the numerical method. Consequently, the variation of Nusselt number, friction factor and overall enhancement ratios for the tube with rings were presented and the best overall enhancement of 18% was achieved for Re = 15,600 for which the spacing between the rings is 3d

  3. Aeronet Solar Flux

    Data.gov (United States)

    National Aeronautics and Space Administration — SolRad-Net (Solar Radiation Network) is an established network of ground-based sensors providing high-frequency solar flux measurements in quasi-realtime to the...

  4. Flux in Tallinn

    Index Scriptorium Estoniae

    2004-01-01

    Rahvusvahelise elektroonilise kunsti sümpoosioni ISEA2004 klubiõhtu "Flux in Tallinn" klubis Bon Bon. Eestit esindasid Ropotator, Ars Intel Inc., Urmas Puhkan, Joel Tammik, Taavi Tulev (pseud. Wochtzchee). Klubiõhtu koordinaator Andres Lõo

  5. Pulsed Drift Tube Accelerator

    International Nuclear Information System (INIS)

    Faltens, A.

    2004-01-01

    The pulsed drift-tube accelerator (DTA) concept was revived by Joe Kwan and John Staples and is being considered for the HEDP/WDM application. It could be used to reach the full energy or as an intermediate accelerator between the diode and a high gradient accelerator such as multi-beam r.f. In the earliest LBNL HIF proposals and conceptual drivers it was used as an extended injector to reach energies where an induction linac with magnetic quadrupoles is the best choice. For HEDP, because of the very short pulse duration, the DTA could provide an acceleration rate of about 1MV/m. This note is divided into two parts: the first, a design based on existing experience; the second, an optimistic extrapolation. The first accelerates 16 parallel K + beams at a constant line charge density of 0.25(micro) C/m per beam to 10 MeV; the second uses a stripper and charge selector at around 4MeV followed by further acceleration to reach 40 MeV. Both benefit from more compact sources than the present 2MV injector source, although that beam is the basis of the first design and is a viable option. A pulsed drift-tube accelerator was the first major HIF experiment at LBNL. It was designed to produce a 2(micro)s rectangular 1 Ampere C s + beam at 2MeV. It ran comfortably at 1.6MeV for several years, then at lower voltages and currents for other experiments, and remnants of that experiment are in use in present experiments, still running 25 years later. The 1A current, completely equivalent to 1.8A K + , was chosen to be intermediate between the beamlets appropriate for a multi-beam accelerator, and a single beam of, say, 10A, at injection energies. The original driver scenarios using one large beam on each side of the reactor rapidly fell out of favor because of the very high transverse and longitudinal fields from the beam space charge, circa 1MV/cm and 250 kV/cm respectively, near the chamber and because of aberrations in focusing a large diameter beam down to a 1mm radius spot at a

  6. Determining Reactor Neutrino Flux

    OpenAIRE

    Cao, Jun

    2011-01-01

    Flux is an important source of uncertainties for a reactor neutrino experiment. It is determined from thermal power measurements, reactor core simulation, and knowledge of neutrino spectra of fuel isotopes. Past reactor neutrino experiments have determined the flux to (2-3)% precision. Precision measurements of mixing angle $\\theta_{13}$ by reactor neutrino experiments in the coming years will use near-far detector configurations. Most uncertainties from reactor will be canceled out. Understa...

  7. Theoretical magnetic flux emergence

    OpenAIRE

    MacTaggart, David

    2011-01-01

    Magnetic flux emergence is the subject of how magnetic fields from the solar interior can rise and expand into the atmosphere to produce active regions. It is the link that joins dynamics in the convection zone with dynamics in the atmosphere. In this thesis, we study many aspects of magnetic flux emergence through mathematical modelling and computer simulations. Our primary aim is to understand the key physical processes that lie behind emergence. The first chapter intro...

  8. Flux Emergence (Theory)

    Science.gov (United States)

    Cheung, Mark C. M.; Isobe, Hiroaki

    2014-07-01

    Magnetic flux emergence from the solar convection zone into the overlying atmosphere is the driver of a diverse range of phenomena associated with solar activity. In this article, we introduce theoretical concepts central to the study of flux emergence and discuss how the inclusion of different physical effects (e.g., magnetic buoyancy, magnetoconvection, reconnection, magnetic twist, interaction with ambient field) in models impact the evolution of the emerging field and plasma.

  9. Quantitative simulation of a magnetospheric substorm 3. Plasmaspheric electric fields and evolution of the plasmapause

    International Nuclear Information System (INIS)

    Spiro, R.W.; Harel, M.; Wolf, R.A.; Reiff, P.H.

    1981-01-01

    Results of the Rice University substorm simulation have been used to investigate the penetration of substorm-associated electric fields into the plasmasphere. Near 4 R/sub E/ in the equatorial plane, our time dependent electric field model is characterized by eastward components in the dusk-midnight local time sector and westward components after midnight. Except for a small region just before dusk, the model predicts eastward electric field components throughout the daytime sector. The characteristic radial component is directed inward at all local times except for a small region just after dawn. These results compare favorably with available whistler and incoherent-scatter radar measurements obtained during magnetically disturbed periods. By assuming an initial plasmapause shape and by followig the computed E> x B> drift trajectories of plasma flux tubes from that initial boundary we have examined the short term evolution of the plasmapause during the substorm-like event of September 19, 1976. We find that narrow filamentary tails can be drawn out from the plasmasphere near dusk within hours of substorm onset. These tail-like appendages to the plasmasphere subsequently drift rapidly from the dusk sector toward the daytime magnetopause. Investigation of the large-scale time dependent flow of plasma in the evening sector indicates that some mid-latitude plasma flux tubes that drift eastward past the dusk terminator reverse their motion between dusk and midnight and begin to drift westward toward dusk. Such time dependent changes in flow trajectories may be related to the formation of F region ionization troughs

  10. Neutron flux monitoring device

    International Nuclear Information System (INIS)

    Shimazu, Yoichiro.

    1995-01-01

    In a neutron flux monitoring device, there are disposed a neutron flux measuring means for outputting signals in accordance with the intensity of neutron fluxes, a calculation means for calculating a self power density spectrum at a frequency band suitable to an object to be measured based on the output of the neutron flux measuring means, an alarm set value generation means for outputting an alarm set value as a comparative reference, and an alarm judging means for comparing the alarm set value with the outputted value of the calculation means to judge requirement of generating an alarm and generate an alarm in accordance with the result of the judgement. Namely, the time-series of neutron flux signals is put to fourier transformation for a predetermined period of time by the calculation means, and from each of square sums for real number component and imaginary number component for each of the frequencies, a self power density spectrum in the frequency band suitable to the object to be measured is calculated. Then, when the set reference value is exceeded, an alarm is generated. This can reliably prevent generation of erroneous alarm due to neutron flux noises and can accurately generate an alarm at an appropriate time. (N.H.)

  11. Neutron flux monitor

    International Nuclear Information System (INIS)

    Oda, Naotaka.

    1993-01-01

    The device of the present invention greatly saves an analog processing section such as an analog filter and an analog processing circuit. That is, the device of the present invention comprises (1) a neutron flux detection means for detecting neutron fluxed in the reactor, (2) a digital filter means for dividing signals corresponding to the detected neutron fluxes into predetermined frequency band regions, (3) a calculation processing means for applying a calculation processing corresponding to the frequency band regions to the neutron flux detection signals divided by the digital filter means. With such a constitution, since the neutron detection signals are processed by the digital filter means, the accuracy is improved and the change for the property of the filter is facilitated. Further, when a neutron flux level is obtained, a calculation processing corresponding to the frequency band region can be conducted without the analog processing circuit. Accordingly, maintenance and accuracy are improved by greatly decreasing the number of parts. Further, since problems inherent to the analog circuit are solved, neutron fluxes are monitored at high reliability. (I.S.)

  12. Water-storage-tube systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hemker, P.

    1981-12-24

    Passive solar collection/storage/distribution systems were surveyed, designed, fabricated, and mechanically and thermally tested. The types studied were clear and opaque fiberglass tubes, metal tubes with plastic liners, and thermosyphoning tubes. (MHR)

  13. Conditioning and breakdown phenomena in accelerator tubes

    International Nuclear Information System (INIS)

    Skorka, S.J.

    1979-01-01

    Important breakdown mechanisms in accelerator tubes are reviewed, and discharge phenomena in NEC tubes are deduced from the surface appearance of the electrodes and insulators of a used tube. Microphotos of these surfaces are shown

  14. Eddy current signal comparison for tube identification

    Science.gov (United States)

    Glass, S. W.; Vojvodic, R.

    2015-03-01

    Inspection of nuclear power plant steam generator tubes is required to justify continued safe plant operation. The steam generators consist of thousands of tubes with nominal diameters of 15 to 22mm, approximately 1mm wall thickness, and 20 to 30m in length. The tubes are inspected by passing an eddy current probe through the tubes from tube end to tube end. It is critical to know exactly which tube identification (row and column) is associated with each tube's data. This is controlled by a precision manipulator that provides the tube ID to the eddy current system. Historically there have been some instances where the manipulator incorrectly reported the tube ID. This can have serious consequences including lack of inspection of a tube, or if a pluggable indication is detected, the tube is likely to be mis-plugged thereby risking a primary to secondary leak.

  15. mouseTube

    Science.gov (United States)

    Torquet, Nicolas; de Chaumont, Fabrice; Faure, Philippe; Bourgeron, Thomas; Ey, Elodie

    2016-01-01

    Ultrasonic vocalisation is a broadly used proxy to evaluate social communication in mouse models of neuropsychiatric disorders. The efficacy and robustness of testing these models suffer from limited knowledge of the structure and functions of these vocalisations as well as of the way to analyse the data. We created mouseTube , an open database with a web interface, to facilitate sharing and comparison of ultrasonic vocalisations data and metadata attached to a recording file. Metadata describe 1) the acquisition procedure, e.g ., hardware, software, sampling frequency, bit depth; 2) the biological protocol used to elicit ultrasonic vocalisations; 3) the characteristics of the individual emitting ultrasonic vocalisations ( e.g. , strain, sex, age). To promote open science and enable reproducibility, data are made freely available. The website provides searching functions to facilitate the retrieval of recording files of interest. It is designed to enable comparisons of ultrasonic vocalisation emission between strains, protocols or laboratories, as well as to test different analysis algorithms and to search for protocols established to elicit mouse ultrasonic vocalisations. Over the long term, users will be able to download and compare different analysis results for each data file. Such application will boost the knowledge on mouse ultrasonic communication and stimulate sharing and comparison of automatic analysis methods to refine phenotyping techniques in mouse models of neuropsychiatric disorders.

  16. X-ray tube

    International Nuclear Information System (INIS)

    Mayo, B.J.

    1980-01-01

    An x-ray tube in which the x-ray origin is scanned on a circle around the patient, comprises a ring-shaped anode, an electron beam travelling along a circular path being deflected onto the anode at the desired positions. The electron beam path may be in a plane parallel to the anode and perhaps at the same radius. It may be in the same plane as a transmission target/anode and at a greater radius. The anode should extend over at least 180 0 although it may extend to 360 0 . Electrostatic means may be provided to constrain the beam to the circular path and further electrostatic means deflect it to the anode of the beam and ensure it is focused at the point of incidence. Collimators provide a planar fan-shaped beam and the anode may be shaped to attenuate side lobes of the radiation. Electrode collects electrons not deflected. The focal regions may be adjacent or otherwise. Coils may provide periodic focusing to overcome space charge dispersion and dynamic adjustment of the focusing before deflection ensures focusing at target incidence. Focusing may be absent near the deflection region, and current in the coil section near the focal region should be zero. (author)

  17. Stability of a laminar flame front propagating within a tube

    Energy Technology Data Exchange (ETDEWEB)

    Salamandra, G.D.; Maiorov, N.I.

    1983-01-01

    The present study examines the deformation of a flame propagating in a semi-closed horizontal tube under the action of perturbations artificially created on the flame surface by brief action of a transverse electrical field on the combustion zone. The fuel mixture used was a dry methane-air mixture containing 10% CH4, which produced a flame front with relatively low convexity. Flame front propagation was recorded by high-speed photographic methods. Interpretation of the photographs reveals that the magnitude of the perturbations increases by an exponential law; fine scale perturbations on the flame surface are suppressed by coarse scale perturbations, while the stable curved form of the flame front in the tube is ensured by the stabilizing action of the tube walls.

  18. Steam generator tube integrity program. Phase I report

    International Nuclear Information System (INIS)

    Alzheimer, J.M.; Clark, R.A.; Morris, C.J.; Vagins, M.

    1979-09-01

    The results are presented of the pressure tests performed as part of Phase I of the Steam Generator Tube Integrity (SGTI) program at Battelle Pacific Northwest Laboratory. These tests were performed to establish margin-to-failure predictions for mechanically defected Pressurized Water Reactor (PWR) steam generator tubing under operating and accident conditions. Defect geometries tested were selected because they simulate known or expected defects in PWR steam generators. These defect geometries are Electric Discharge Machining (EDM) slots, elliptical wastage, elliptical wastage plus through-wall slot, uniform thinning, denting, denting plus uniform thinning, and denting plus elliptical wastage. All defects were placed in tubing representative of that currently used in PWR steam generators

  19. Flux-flow resistivity of three high-temperature superconductors

    International Nuclear Information System (INIS)

    Cha, Y.S.; Evans, D.J.; Hull, J.R.; Seol, S.Y.

    1996-01-01

    Results of experiments on flux-flow resistivity (the relationship of voltage to current) of three high-temperature superconductors are described. The superconductors are a melt-cast BSCCO 2212 rod, a single filament BSCCO powder-in-tube (PIT) tape, and a multifilament PIT tape. The flux-flow resistivity of these superconductors was measured at three temperatures: 77 K (saturated liquid nitrogen), 87 K (saturated liquid argon), and 67 K (subcooled liquid nitrogen). Implications of the present results for practical applications are discussed

  20. How Giant Magnetospheres Maintain Their Magnetic Flux.

    Science.gov (United States)

    Rymer, A. M.

    2017-12-01

    Magnetic flux lost from a planet must be returned [Maxwell's first law, there are no magnetic monopoles (div(B) = 0)], and the dominant mechanism by which this is achieved is still to be determined. Here we compare a mechanism for magnetic flux return via small-scale plasma circulation. The existence of bi-modal superposed electron distributions at Jupiter and Saturn was a surprise to Voyager researchers [e.g. Sittler et al., 1983] that remains something of a mystery to this day. Electrons are virtually massless and are expected to rapidly thermalize to a single distribution. Observations by the Cassini spacecraft at Saturn have elucidated on the source of the hot electron component - small scale isolated flux tubes (commonly referred to as `injection events') that bubble planetward, returning magnetic flux that had been convected outward by centrifugal forces or stripped away during magnetospheric reconfigurations, such as substorms [Rymer et al., 2008]. Saturn is an ideal place to study injection events; relatively quiescent, aligned magnetic and geographic spins axes and a nice fast rotation rate in comparison to plasma drift speeds. The other magnetospheric laboratories in our solar system (Jupiter, Uranus and Neptune) will be more challenging. In this presentation we describe predictions for how plasma injection will be manifest as a function of magnetic field strength, topology and planetary spin rate and its importance in conservation of magnetic flux globally. Sittler, E. C., Jr., K. W. Ogilvie, and J. D. Scudder, 1983. Survey of low-energy plasma electrons in Saturn's magnetosphere: Voyager 1 and 2, J. Geophys. Res., 88, 8847- 8870. Rymer, A. M., Mauk, B. H. , Hill, T. W., Paranicas, C., Mitchell, D. G., Coates, A. J., Young, D. T. , 2008. Electron circulation in Saturn's magnetosphere. J. Geophys. Res.113, A01201.

  1. Axial Field Electric Motor and Method

    National Research Council Canada - National Science Library

    Cho, Chahee P

    2007-01-01

    .... A hybrid field, brushless, permanent magnet electric motor utilizing a rotor with two sets of permanent magnets oriented such that the flux produced by the two sets of magnets is perpendicular to each...

  2. PEG tubes: dealing with complications.

    Science.gov (United States)

    Malhi, Hardip; Thompson, Rosie

    A percutaneous endoscopic gastronomy tube can be used to deliver nutrition, hydration and medicines directly into the patient's stomach. Patients will require a tube if they are unable to swallow safely, putting them at risk of aspiration of food, drink and medicines into their lungs. It is vital that nurses are aware of the complications that may arise when caring for a patient with a PEG tube. It is equally important that nurses know how to deal with these complications or from where tc seek advice. This article provides a quick troubleshooting guide to help nurses deal with complications that can arise with PEG feeding.

  3. Rigid inflatable gastrostomy tube malposition

    Directory of Open Access Journals (Sweden)

    Timothy E. Murray, MB, MCh, MRCS, FFR

    2017-12-01

    Full Text Available Rigid inflatable gastrostomy (RIG tubes are widely used in contemporary clinical practice for a variety of indications. Insertion of RIG tubes is associated with a high technical success rate and low incidence of mortality. In this case report, a procedural pitfall associated with intraperitoneal-extragastric malposition is described. Rigorous assessment of abdominal radiographs, as well as awareness of the expected appearance of the RIG tube and gastropexy T-fasteners, allows the abdominal radiologist to detect early RIG position in the early postprocedural period. Abdominal radiography is a widely available and inexpensive technique. The high spatial resolution it provides makes it a valuable tool in determining hardware position.

  4. Expansion tube test time predictions

    Science.gov (United States)

    Gourlay, Christopher M.

    1988-01-01

    The interaction of an interface between two gases and strong expansion is investigated and the effect on flow in an expansion tube is examined. Two mechanisms for the unsteady Pitot-pressure fluctuations found in the test section of an expansion tube are proposed. The first mechanism depends on the Rayleigh-Taylor instability of the driver-test gas interface in the presence of a strong expansion. The second mechanism depends on the reflection of the strong expansion from the interface. Predictions compare favorably with experimental results. The theory is expected to be independent of the absolute values of the initial expansion tube filling pressures.

  5. Electrical measuring device for a high temperature reactor

    International Nuclear Information System (INIS)

    Elter, C.; Handel, H.; Schoening, J.; Schmitt, H.

    1982-01-01

    The device for measuring the low or high neutron flux during start-up or at load is accommodated in an armoured guide tube projecting into the floor. A gas-tight capsule is formed as the measuring column with outer dome with a lid solidly connected by a flange to the armoured tube situated on the side wall of the concrete reactor vessel, together with the armoured guide tube. Two shielding shutters prevent the passage of radiation through the armoured tube. (DG) [de

  6. The Open Flux Problem

    International Nuclear Information System (INIS)

    Linker, J. A.; Caplan, R. M.; Downs, C.; Riley, P.; Mikic, Z.; Lionello, R.; Henney, C. J.; Arge, C. N.; Liu, Y.; Derosa, M. L.; Yeates, A.; Owens, M. J.

    2017-01-01

    The heliospheric magnetic field is of pivotal importance in solar and space physics. The field is rooted in the Sun’s photosphere, where it has been observed for many years. Global maps of the solar magnetic field based on full-disk magnetograms are commonly used as boundary conditions for coronal and solar wind models. Two primary observational constraints on the models are (1) the open field regions in the model should approximately correspond to coronal holes (CHs) observed in emission and (2) the magnitude of the open magnetic flux in the model should match that inferred from in situ spacecraft measurements. In this study, we calculate both magnetohydrodynamic and potential field source surface solutions using 14 different magnetic maps produced from five different types of observatory magnetograms, for the time period surrounding 2010 July. We have found that for all of the model/map combinations, models that have CH areas close to observations underestimate the interplanetary magnetic flux, or, conversely, for models to match the interplanetary flux, the modeled open field regions are larger than CHs observed in EUV emission. In an alternative approach, we estimate the open magnetic flux entirely from solar observations by combining automatically detected CHs for Carrington rotation 2098 with observatory synoptic magnetic maps. This approach also underestimates the interplanetary magnetic flux. Our results imply that either typical observatory maps underestimate the Sun’s magnetic flux, or a significant portion of the open magnetic flux is not rooted in regions that are obviously dark in EUV and X-ray emission.

  7. Power Split Strategy for Fuel Cell Hybrid Electric System Stratégie de séparation des flux de puissance pour un système électrique hybride à pile à combustible

    Directory of Open Access Journals (Sweden)

    Di Domenico D.

    2009-11-01

    Full Text Available The power management of a hybrid system composed of a fuel cell, a battery and a DC/DC power converter is developed. A decoupled control strategy is proposed, aimed at balancing the power flow between the stack and the battery and avoiding electrochemical damage due to low oxygen concentration in the fuel cell cathode. The controller is composed of two components. The first controller regulates the compressor, and as a consequence the oxygen supplied to the cathode, via a classic Proportional-Integral controller. The second controller optimally manages the current demanded by the fuel cell and battery via a linear-quadratic control strategy acting on the converter. An Extended Kalman Filter is also designed in order to estimate the battery State of Charge. The closed-loop performance was tested in simulation using a 310th-order system model. Ce papier illustre une stratégie de gestion de puissance pour un système hybride composé d’une pile à combustible, d’une batterie et d’un convertisseur DC/DC. Dans le but d’équilibrer les flux de puissance entre la pile à combustible et la batterie et d’éviter les dégâts causés par une dépression d’oxygène dans le cathode de la pile, un contrôleur découplé est proposé. Ce contrôleur se compose de deux parties. La première, un régulateur proportionnel-intégral, commande le compresseur et, par conséquent, le flux d’oxygène fourni au cathode. La deuxième, un régulateur linéaire-quadratique, gère le courant demandé par la pile à combustible et la batterie. Pour estimer l’état de charge de la batterie, un filtre de Kalman étendu a aussi été conçu. Les performances de la stratégie ont été analysées en simulation avec un modèle de batterie du 310e ordre.

  8. Irradiation creep and growth of zircaloy-4 tubes

    International Nuclear Information System (INIS)

    Lansiart, S.; Darchis, L.; Pelchat, J.

    1990-01-01

    The influence of temperature and fast neutron flux on irradiation creep and growth of stress relieved zircaloy-4 pressurized tubes has been derived from experimental irradiations in NaK, performed up to 2.5 10 25 n.m -2 in the temperature range [280, 350] 0 C. A significant influence of temperature on axial growth has been observed: at 280 0 C the elongation can no longer be expressed as a linear function of fluence as for the 350 0 C irradiation temperature; diametral growth, on the other hand, always appears negligible. Irradiation creep obviously depends on temperature too; the diametral strain (including thermal part) has been modelled as a sum of primary and secondary terms, the former being independent of fluence. For the tubing considered it is observed that the ranking of the different batches, with respect to diametral creep resistance, is the same before and under irradiation. Concerning axial creep strain the stress relieved material behaves as does an isotropic tube. This is not the case of recrystallized zircaloy-4 F, which shows a non negligible axial deformation, related to the diametral creep one, even though this diametral irradiation creep strain is strongly reduced comparatively to that of the stress relieved material. The comparison of the two materials growth rates is more complex since their dependence on temperature and flux differs

  9. Consideration of critical heat flux margin prediction by subcooled or low quality critical heat flux correlations

    International Nuclear Information System (INIS)

    Hejzlar, P.; Todreas, N.E.

    1996-01-01

    The accurate prediction of the critical heat flux (CHF) margin which is a key design parameter in a variety of cooling and heating systems is of high importance. These margins are, for the low quality region, typically expressed in terms of critical heat flux ratios using the direct substitution method. Using a simple example of a heated tube, it is shown that CHF correlations of a certain type often used to predict CHF margins, expressed in this manner, may yield different results, strongly dependent on the correlation in use. It is argued that the application of the heat balance method to such correlations, which leads to expressing the CHF margins in terms of the critical power ratio, may be more appropriate. (orig.)

  10. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... and Aging Program African American Program Training and Jobs Fellowships NEI Summer Intern Program Diversity In Vision ... DIVRO) Student Training Programs To search for current job openings visit HHS USAJobs Home >> NEI YouTube Videos >> ...

  11. Tube-wave seismic imaging

    Science.gov (United States)

    Korneev, Valeri A [LaFayette, CA

    2009-05-05

    The detailed analysis of cross well seismic data for a gas reservoir in Texas revealed two newly detected seismic wave effects, recorded approximately 2000 feet above the reservoir. A tube-wave (150) is initiated in a source well (110) by a source (111), travels in the source well (110), is coupled to a geological feature (140), propagates (151) through the geological feature (140), is coupled back to a tube-wave (152) at a receiver well (120), and is and received by receiver(s) (121) in either the same (110) or a different receiving well (120). The tube-wave has been shown to be extremely sensitive to changes in reservoir characteristics. Tube-waves appear to couple most effectively to reservoirs where the well casing is perforated, allowing direct fluid contact from the interior of a well case to the reservoir.

  12. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... and Aging Program African American Program Training and Jobs Fellowships NEI Summer Intern Program Diversity In Vision ... DIVRO) Student Training Programs To search for current job openings visit HHS USAJobs Home > NEI YouTube Videos > ...

  13. Lunar Core Drive Tubes Summary

    Data.gov (United States)

    National Aeronautics and Space Administration — Contains a brief summary and high resolution imagery from various lunar rock and core drive tubes collected from the Apollo and Luna missions to the moon.

  14. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... questions Clinical Studies Publications Catalog Photos and Images Spanish Language Information Grants and Funding Extramural Research Division ... Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Embedded video ...

  15. Conditioning of NEC accelerator tubes

    International Nuclear Information System (INIS)

    Yntema, J.L.

    1979-01-01

    The conditioning process of NEC tubes was investigated by recording the fluctuations observed with a residual gas analyzer for a fixed mass and a simultaneous recording of the current fluctuations in background pressure

  16. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Disease Education Program Glaucoma Education Program Low Vision Education Program Hispanic/Latino ... To search for current job openings visit HHS USAJobs Home » NEI YouTube ...

  17. Neutron interrogation to identify chemical elements with an ion-tube neutron source (INS)

    International Nuclear Information System (INIS)

    Alvarez, R.A.; Dougan, A.D.; Rowland, M.R.; Wang, T.F.

    1995-01-01

    A non-destructive analysis technique using a portable, electric ion-tube neutron source (INS) and gamma ray detector has been used to identify the key constituent elements in a number of sealed munitions, and from the elemental makeup, infer the types of agent within each. The high energy (14 MeV) and pulsed character of the neutron flux from an INS provide a method of measuring, quantitatively, the oxygen, carbon, and fluorine content of materials in closed containers, as well as the other constituents that can be measured with low-energy neutron probes. The broad range of elements that can be quantitatively measured with INS-based instruments provides a capability of verifying common munition fills; it provides the greatest specificity of any portable neutron-based technique for determining the full matrix of chemical elements in completely unrestricted sample scenarios. The specific capability of quantifying the carbon and oxygen content of materials should led to a fast screening technique which, can discriminate very quickly between high-explosive and chemical agent-filled containers. (author) 12 refs.; 5 figs.; 3 tabs

  18. Eddy current tube testing unit

    International Nuclear Information System (INIS)

    Dufayet, J.P.; Duret, G.

    1975-01-01

    The unit described can check a wide variety of tubes in quick succession and its modular design gives it a high degree of versability. Suitably defined working conditions and specific fittings enable most of the faults encountered in the manufacture of a tube to be detected. By appropriate means of selection based on signal amplitude, phase and frequency analyses it is possible to adapt selection criteria to the seriousness of the different categories of defect [fr

  19. Electronics for proportional drift tubes

    International Nuclear Information System (INIS)

    Fremont, G.; Friend, B.; Mess, K.H.; Schmidt-Parzefall, W.; Tarle, J.C.; Verweij, H.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Geske, K.; Riege, H.; Schuett, J.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Semenov, Y.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration)

    1980-01-01

    An electronic system for the read-out of a large number of proportional drift tubes (16,000) has been designed. This system measures deposited charge and drift-time of the charge of a particle traversing a proportional drift tube. A second event can be accepted during the read-out of the system. Up to 40 typical events can be collected and buffered before a data transfer to a computer is necessary. (orig.)

  20. The YouTube reader

    OpenAIRE

    Snickars, Pelle; Vonderau, Patrick

    2009-01-01

    YouTube has come to epitomize the possibilities of digital culture. With more than seventy million unique users a month and approximately eighty million videos online, this brand-name video distribution platform holds the richest repository of popular culture on the Internet. As the fastest growing site in the history of the Web, YouTube promises endless new opportunities for amateur video, political campaigning, entertainment formats, and viral marketing—a clip culture that has seemed to out...

  1. An investigation on density wave oscillations in helical coiled tubes

    International Nuclear Information System (INIS)

    Yan-long, Z.; Tin-Kuan, C.; Xue-jun, C.; Veziroglu, T.N.

    1990-01-01

    Density wave instability in helical coiled tubes has been systematically observed using high pressure ranging from 3.0 to 10.0 Mpa, mass velocity from 400 to 1200 kg/sm 2 , inlet subcooling from 10 to 120 degrees C and heat flux up to 450 kw/m 2 . In the experimental research the effects of system pressure, mass velocity, heat flux, inlet subcooling, inlet resistence and exit resistence have been studied. The experimental results show that the density wave oscillation occurred at positive slope part to mass velocity versus total pressure drop curve, the phase difference of the density wave oscillation between the inlet and exit flow rate is approximately 180 degrees. Increasing heat flux, the periods of density wave oscillation decreased. The periods are about 1-2 times the residence time of fluid in the heater, about 3-14s. System presure, inlet subcooling, mass velocity, inlet resistance and exit resistence affected the threshold of density wave oscillation. Increasing the system pressure, mass velocity and inlet resistence, the limit heat flux of density wave oscillation increased. Increasing exit resistence, the limit heat flux decreased. The stability boundary diagrams of the system have been found. In this paper the empirical correlations for predicting the threshold of density wave oscillations are presented

  2. Variable-energy drift-tube linacs

    International Nuclear Information System (INIS)

    Swenson, D.A.; Boyd, T.J.; Potter, J.M.; Stovall, J.E.

    1981-01-01

    Practical applications of ion linacs are more viable now than ever before because of the recent development of the radio-frequency quadrupole accelerating structure, as well as other technological advances developed under the Pion Generator for Medical Irradiations program. This report describes a practical technique for varying the energy of drift-tube linacs and thus further broadening the possibilities for linac applications. This technique involves using the post couplers (normally used to flatten and stabilize the electric fields) to create a step in the fields, thus terminating the acceleration process. In the examples given for a 70-MeV accelerator design, when using this technique the energy is continuously variable down to 20 MeV, while maintaining a small energy spread

  3. Radioactivity transport following steam generator tube rupture

    International Nuclear Information System (INIS)

    Hopenfeld, J.

    1985-03-01

    A review of the capabilities of the CITADEL computer code as well as plant experience to project radioactivity releases following a steam generator tube rupture in PWR's shows that certain experimental data are needed for reliable off-site dose predictions. This article defines five parameters which are the key for such predictions and discusses the functional dependence of these parameters on various operational variables. The above parameters can be used in conjunction with CITADEL or they can be inserted in the appropriate equations which then conveniently can be programmed as a subroutine in thermal-hydraulic system codes. A joint Westinghouse, Electric Power Research Institute and Nuclear Regulatory Commission Program aimed at obtaining the five parameters empirically is described

  4. Dermatology on YouTube.

    Science.gov (United States)

    Boyers, Lindsay N; Quest, Tyler; Karimkhani, Chante; Connett, Jessica; Dellavalle, Robert P

    2014-06-15

    YouTube, reaches upwards of six billion users on a monthly basis and is a unique source of information distribution and communication. Although the influence of YouTube on personal health decision-making is well established, this study assessed the type of content and viewership on a broad scope of dermatology related content on YouTube. Select terms (i.e. dermatology, sun protection, skin cancer, skin cancer awareness, and skin conditions) were searched on YouTube. Overall, the results included 100 videos with over 47 million viewers. Advocacy was the most prevalent content type at 24% of the total search results. These 100 videos were "shared" a total of 101,173 times and have driven 6,325 subscriptions to distinct YouTube user pages. Of the total videos, 35% were uploaded by or featured an MD/DO/PhD in dermatology or other specialty/field, 2% FNP/PA, 1% RN, and 62% other. As one of the most trafficked global sites on the Internet, YouTube is a valuable resource for dermatologists, physicians in other specialties, and the general public to share their dermatology-related content and gain subscribers. However, challenges of accessing and determining evidence-based data remain an issue.

  5. Electrical Injuries

    Science.gov (United States)

    ... how quickly you get treatment. Causes of electrical injuries include Lightning strikes Faulty electrical appliances Work-related exposures Contact with household wiring or power lines Accidents in small children, when they bite or suck on electrical cords, ...

  6. The use of laser-induced plasma spectroscopy technique for the characterization of boiler tubes

    International Nuclear Information System (INIS)

    Nicolas, G.; Mateo, M.P.; Yanez, A.

    2007-01-01

    The present work focuses on the characterization of boiler tube walls using laser-induced plasma spectroscopy technique with visual inspection by optical and scanning electron microscopy of the cross-sections of these tubes. In a watertube boiler, water runs through tubes that are surrounded by a heating source. As a result, the water is heated to very high temperatures, causing accumulation of deposits on the inside surfaces of the tubes. These deposits play an important role in the efficiency of the boiler tube because they produce a reduction of the boiler heat rate and an increase in the number of tube failures. The objectives are to determine the thickness and arrangement of deposits located on the highest heat area of the boiler and compare them with tube parts where the heat flux is lower. The major deposits found were copper and magnetite. These deposits come mainly from the boiler feedwater and from the reaction between iron and water, and they do not form on the tube walls at a uniform rate over time. Their amount depends on the areas where they are collected. A Nd:YAG laser operating at 355 nm has been used to perform laser-induced plasma spectra and depth profiles of the deposits

  7. Pool boiling of nanofluids on rough and porous coated tubes: experimental and correlation

    Directory of Open Access Journals (Sweden)

    Cieśliński Janusz T.

    2014-06-01

    Full Text Available The paper deals with pool boiling of water-Al2O3 and water- Cu nanofluids on rough and porous coated horizontal tubes. Commercially available stainless steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate the test heater. The tube surface was roughed with emery paper 360 or polished with abrasive compound. Aluminium porous coatings of 0.15 mm thick with porosity of about 40% were produced by plasma spraying. The experiments were conducted under different absolute operating pressures, i.e., 200, 100, and 10 kPa. Nanoparticles were tested at the concentration of 0.01, 0.1, and 1% by weight. Ultrasonic vibration was used in order to stabilize the dispersion of the nanoparticles. It was observed that independent of operating pressure and roughness of the stainless steel tubes addition of even small amount of nanoparticles augments heat transfer in comparison to boiling of distilled water. Contrary to rough tubes boiling heat transfer coefficient of tested nanofluids on porous coated tubes was lower compared to that for distilled water while boiling on porous coated tubes. A correlation equation for prediction of the average heat transfer coefficient during boiling of nanofluids on smooth, rough and porous coated tubes is proposed. The correlation includes all tested variables in dimensionless form and is valid for low heat flux, i.e., below 100 kW/m2.

  8. Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube

    Directory of Open Access Journals (Sweden)

    JB Sosa

    2015-10-01

    Full Text Available Any hydraulic reaction turbine is installed with a draft tube that impacts widely the entire turbine performance, on which its functions are as follows: drive the flux in appropriate manner after it releases its energy to the runner; recover the suction head by a suction effect; and improve the dynamic energy in the runner outlet. All these functions are strongly linked to the geometric definition of the draft tube. This article proposes a geometric parametrization and analysis of a Francis turbine draft tube. Based on the parametric definition, geometric changes in the draft tube are proposed and the turbine performance is modeled by computational fluid dynamics; the boundary conditions are set by measurements performed in a hydroelectric power plant. This modeling allows us to see the influence of the draft tube shape on the entire turbine performance. The numerical analysis is based on the steady-state solution of the turbine component flows for different guide vanes opening and multiple modified draft tubes. The computational fluid dynamics predictions are validated using hydroelectric plant measurements. The prediction of the turbine performance is successful and it is linked to the draft tube geometric features; therefore, it is possible to obtain a draft tube parameter value that results in a desired turbine performance.

  9. Thermal performance in circular tube fitted with coiled square wires

    International Nuclear Information System (INIS)

    Promvonge, Pongjet

    2008-01-01

    The effects of wires with square cross section forming a coil used as a turbulator on the heat transfer and turbulent flow friction characteristics in a uniform heat flux, circular tube are experimentally investigated in the present work. The experiments are performed for flows with Reynolds numbers ranging from 5000 to 25,000. Two different spring coiled wire pitches are introduced. The results are also compared with those obtained from using a typical coiled circular wire, apart from the smooth tube. The experimental results reveal that the use of coiled square wire turbulators leads to a considerable increase in heat transfer and friction loss over those of a smooth wall tube. The Nusselt number increases with the rise of Reynolds number and the reduction of pitch for both circular and square wire coils. The coiled square wire provides higher heat transfer than the circular one under the same conditions. Also, performance evaluation criteria to assess the real benefits in using both coil wires of the enhanced tube are determined

  10. Study of tube diameter effect on the burnout

    International Nuclear Information System (INIS)

    Levitan, L.L.; Lantsman, F.P.; Dedneva, E.I.

    1981-01-01

    Effect of a tube diameter d on boundary steam content Xsub(b) is experimentally investigated during unwashed liquid wall film drying in the disperse-ring flow regime. For this purpose systematical experimental investigations of the burnout of the second kind in tubes with diameters of 4, 6 and 12 mm have been carried out as well as the other data relating to burnout in tubes with diameter from 4 to 40 mm are used. The investigations have been carried out at water and steam pressures of 4.9-13.7 MPa and mass velocities from 750 to 5000 kg/m 2 xs. It is elucidated that increase in the tube diameter results in reducing the ranges of pressures and mass velocities at which Xsub(b) is independent of heat flux. Quantity dependence Xsub(b)=f(d) has been obtained as well. The best agreement with data from different experiments is observed when taking into account the effect of d on Xsub(b) by means of the following relation: Xsub(b) is proportional to dsup(-0.25). In this case divergence, as a rule, does not exceed 10% [ru

  11. Controlling temperature on pipes with current passage tubes; Maintenir en temperature tuyauteries grace au tube a passage de courant (TPC)

    Energy Technology Data Exchange (ETDEWEB)

    Mauras, Ph.

    1995-12-31

    Electrical solutions for controlling (or tracing) temperature in pipes such as in chemical and food industries, induce very low maintenance costs; the current passage technique consists in charging the pipes: the tube is heated by Joule effect and the fluid is heated by convection. Impedance calculations must include electromagnetic effects between conductors and other close systems. Electricite de France (EDF) has developed a theoretical model, which has been numerically validated; simple sizing rules have been derived

  12. The manufacturing method of pyrographite tubing including those closed from one side and equipment for manufacturing of pyrographite tubing

    International Nuclear Information System (INIS)

    Wlodarski, R.; Nowicki, A.; Pekalska, L.; Szczepankiewicz, C.; Kuznicki, R.; Tulik, J.; Kaczmarek, B.

    1992-01-01

    The method as well as equipment for manufacturing of pyrographite tubing including those closed from one side has been worked out. The method consists in pyrolysis of aliphatic and aromatic hydrocarbons or their mixtures. The process runs under diminished pressure in the temperature range of 1700-2600 K. The layering of graphite is organized on graphite bars having big thermal expansion coefficient. The manufacturing equipment is installed inside an electric furnace. Construction details are described in the patent. 1 fig

  13. Effects of 1- and 2-MeV electrons on photomultiplier tubes

    Science.gov (United States)

    Beatty, M. E., III; Debnam, W. J., Jr.; Meredith, B. D.

    1976-01-01

    Various types of photomultiplier tubes useful for space applications were irradiated with 1- and 2-MeV electrons at Van Allen radiation belt fluxes of 100,000 to 10 millions electrons/sq cm-sec. The increase in the dark current due to electron irradiation was observed at various bias voltages under worst-case conditions (no shielding). Results were presented in the form of dark current plotted against electron flux. All the tubes tested showed extremely large increases in dark current. Tube types 541A, 6217, 6199, and 6903 exhibited the largest increases under irradiation, whereas type 1P22 was affected the least. All the damage observed was transient. The luminescence produced in the optical window probably accounts for a large part of the dark-current increases, but there were some effects possibly due to direct irradiation of the photocathode and dynode chain.

  14. Multi-anode wire straw tube tracker

    International Nuclear Information System (INIS)

    Oh, S.H.; Ebenstein, W.L.; Wang, C.W.

    2011-01-01

    We report on a test of a straw tube detector design having several anode (sense) wires inside a straw tube. The anode wires form a circle inside the tube and are read out independently. This design could solve several shortcomings of the traditional single wire straw tube design such as double hit capability and stereo configuration.

  15. 21 CFR 872.6570 - Impression tube.

    Science.gov (United States)

    2010-04-01

    ... DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6570 Impression tube. (a) Identification. An impression tube is a device consisting of a hollow copper tube intended to take an impression of a single tooth... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Impression tube. 872.6570 Section 872.6570 Food...

  16. 27 CFR 41.35 - Cigarette tubes.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Cigarette tubes. 41.35... OF THE TREASURY (CONTINUED) TOBACCO IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes are taxed at the following rates...

  17. Tubing vs. buckets: a cost comparison

    Science.gov (United States)

    Neil K. Huyler

    1975-01-01

    Equipment investment for tubing-vacuum systems was significantly less than that for bucket systems. Tubing-vacuum systems required about 22 percent less labor input, the major labor input being completed before sap-flow periods. Annual cost of operation was less for tubing-vacuum than the bucket system. Small tubing-vacuum operations showed more profit potential than...

  18. Flow Vaporization of CO{sub 2} in Microchannel Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, Jostein

    2002-07-01

    Carbon dioxide is receiving renewed interest as an efficient and environmentally safe refrigerant in a number of applications, including mobile air conditioning and heat pump systems, and hot water heat pumps. Compact heat exchangers for CO{sub 2} systems are designed with small-diameter tubing. The purpose of this study is therefore to provide a better basis for understanding and predicting heat transfer and pressure drop during flow vaporization of CO{sub 2} in microchannels. The ''unusual'' properties of carbon dioxide give heat transfer and two-phase flow characteristics that are very different from those of conventional refrigerants. Examples of these differences are the much higher pressure, the resulting high vapour density, a very low surface tension, and a low liquid viscosity. High pressure and low surface tension has a major effect on nucleate boiling characteristics, and earlier test data have shown a clear dominance of nucleate boiling even at very high mass flux. Heat transfer tests were conducted in a rig using a flat, extruded aluminium microchannel tube of 540 mm length with 25 channels of 0.81 mm diameter. The horizontal test tube was heated by a water jacket in order to get representative boundary conditions for air-to-refrigerant heat transfer (''fluid heating''). Constant heat flux conditions do not simulate these boundary conditions well, and may give unrealistic behaviour especially in relation to dryout and post-dryout heat transfer. Systematic tests at constant heat flux with single-phase CO{sub 2} flow on the inside generated data that were used in the derivation of a model for water-side beat transfer coefficient. A regression based on these data gave a calibrated equation for water-side heat transfer on the form NuNu(Re,Pr). This equation was then used in later experiments to subtract water-side thermal resistance from the measured overall resistance (1/UA), thereby finding the internal heat

  19. Characterization of Zircaloy-4 tubing procured for fuel cladding research programs

    International Nuclear Information System (INIS)

    Chapman, R.H.

    1976-01-01

    A quantity of Zircaloy-4 tubing [10.92 mm outside diameter by 0.635 mm wall thickness] was purchased specifically for use in a number of related fuel cladding research programs sponsored by the Division of Reactor Safety Research, Nuclear Regulatory Commission (NRC/RSR). Identical tubing (produced simultaneously and from the same ingot) was purchased concurrently by the Electric Power Research Institute (EPRI) for use in similar research programs sponsored by that organization. In this way, source variability and prior fabrication history were eliminated as parameters, thus permitting direct comparison (as far as as-received material properties are concerned) of experimental results from the different programs. The tubing is representative of current reactor technology. Consecutive serial numbers assigned to each tube identify the sequence of the individual tubes through the final tube wall reduction operation. The report presented documents the procurement activities, provides a convenient reference source of manufacturer's data and tubing distribution to the various users, and presents some preliminary characterization data. The latter have been obtained routinely in various research programs and are not complete. Although the number of analyses, tests, and/or examinations performed to date are insufficient to draw statistically valid conclusions with regard to material characterization, the data are expected to be representative of the as-received tubing. It is anticipated that additional characterizations will be performed and reported routinely by the various research programs that use the tubing

  20. Soluble organic nutrient fluxes

    Science.gov (United States)

    Robert G. Qualls; Bruce L. Haines; Wayne Swank

    2014-01-01

    Our objectives in this study were (i) compare fluxes of the dissolved organic nutrients dissolved organic carbon (DOC), DON, and dissolved organic phosphorus (DOP) in a clearcut area and an adjacent mature reference area. (ii) determine whether concentrations of dissolved organic nutrients or inorganic nutrients were greater in clearcut areas than in reference areas,...