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Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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1

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Wednesday, 25 November 2009 00:00 Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

2

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

3

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

4

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

5

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

6

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

7

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

8

Probing the spin polarization of current by soft x-ray imaging of current-induced magnetic vortex dynamics  

SciTech Connect

Time-resolved soft X-ray transmission microscopy is applied to image the current-induced resonant dynamics of the magnetic vortex core realized in a micron-sized Permalloy disk. The high spatial resolution better than 25 nm enables us to observe the resonant motion of the vortex core. The result also provides the spin polarization of the current to be 0.67 {+-} 0.16 for Permalloy by fitting the experimental results with an analytical model in the framework of the spin-transfer torque.

Kasai, Shinya; Fischer, Peter; Im, Mi-Young; Yamada, Keisuke; Nakatani, Yoshinobu; Kobayashi, Kensuke; Kohno, Hiroshi; Ono, Teruo

2008-12-09T23:59:59.000Z

9

Vortex Dynamics in NanoScale Materials  

NLE Websites -- All DOE Office Websites (Extended Search)

Into the Vortex: Dynamics in Nanoscale Materials Into the Vortex: Dynamics in Nanoscale Materials Micron and nanosized magnets are of great interest for their potential applications in new electronic devices, such as magnetic random access memories. As the size of magnets is reduced to a 1-micron scale and below, the boundaries (surfaces, perimeters, etc) of the objects begin to profoundly influence both the static and dynamic behavior of the materials. Researchers from Argonne's Materials Science Division (MSD), Center for Nanoscale Materials (CNM), and Advanced Photon Source (APS) have recently examined the dynamics of 3- to 7-micron-diameter NiFe alloy disks with a combination of theoretical calculations and a new time-resolved magnetic imaging technique using synchrotron-based x-ray photoemission electron

10

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Magnetic Vortex Core Reversal by Low-Field Excitations Magnetic Vortex Core Reversal by Low-Field Excitations Print Wednesday, 28 March 2007 00:00 In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

11

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Low-Field Excitations Print Magnetic Vortex Core Reversal by Low-Field Excitations Print In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

12

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Low-Field Excitations Print Magnetic Vortex Core Reversal by Low-Field Excitations Print In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

13

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Low-Field Excitations Print Magnetic Vortex Core Reversal by Low-Field Excitations Print In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

14

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

new materials with new switching mechanisms. Uncovered by basic research into the fundamentals of magnetism, one such candidate consists of miniscule magnetic vortices like...

15

Argonne CNM Highlight: Biofunctionalized magnetic-vortex microdiscs for  

NLE Websites -- All DOE Office Websites (Extended Search)

Biofunctionalized magnetic-vortex microdiscs for targeted cancer-cell destruction Biofunctionalized magnetic-vortex microdiscs for targeted cancer-cell destruction Magnetic microdisks Reflection optical microscope image of a dried suspension of the discs prepared via magnetron sputtering and optical lithography. Magnetic spin vortex Model of magnetic-vortex spin distribution in a disc. Users from Argonne's Materials Science Division and University of Chicago's Pritzker School of Medicine, working collaboratively on a user science project with CNM's Nanobio Interfaces Group, have discovered that nanostructured magnetic materials offer exciting avenues for probing cell mechanics, activating mechanosensitive ion channels, and advancing potential cancer therapies. Their new report describes an approach based on interfacing cells with lithographically defined microdiscs (1-micron

16

Vortex dynamics : a window into the properties of type-II superconductors  

E-Print Network (OSTI)

DIEGO Vortex Dynamics: A Window Into the Properties of Type-DISSERTATION Vortex Dynamics: A Window Into the Propertiesa ?lm deposits on the window through which the laser beam

Taylor, Benjamin Jeremy

2006-01-01T23:59:59.000Z

17

Vortex driven flame dynamics and combustion instability  

E-Print Network (OSTI)

Combustion instability in premixed combustors mostly arises due to the coupling between heat release rate dynamics and system acoustics. It is crucial to understand the instability mechanisms to design reliable, high ...

Altay, Hurrem Murat

2005-01-01T23:59:59.000Z

18

Simulations of 2D magnetic electron drift vortex mode turbulence in plasmas  

E-Print Network (OSTI)

Simulations are performed to investigate turbulent properties of nonlinearly interacting two-dimensional (2D) magnetic electron drift vortex (MEDV) modes in a nonuniform unmagnetized plasma. The relevant nonlinear equations governing the dynamics of the MEDV modes are the wave magnetic field and electron temperature perturbations in the presence of the equilibrium density and temperature gradients. The important nonlinearities come from the advection of the electron fluid velocity perturbation and the electron temperature, as well as from the nonlinear electron Lorentz force. Computer simulations of the governing equations for the nonlinear MEDV modes reveal the generation of streamer-like electron flows, such that the corresponding gradients in the direction of the inhomogeneities tend to flatten out. By contrast, the gradients in an orthogonal direction vary rapidly. Consequently, the inertial range energy spectrum in decaying MEDV mode turbulence exhibits a much steeper anisotropic spectral index. The magn...

Shaikh, Dastgeer

2008-01-01T23:59:59.000Z

19

Method for the detection of a magnetic field utilizing a magnetic vortex  

SciTech Connect

The determination of the strength of an in-plane magnetic field utilizing one or more magnetically-soft, ferromagnetic member, having a shape, size and material whereas a single magnetic vortex is formed at remanence in each ferromagnetic member. The preferred shape is a thin circle, or dot. Multiple ferromagnetic members can also be stacked on-top of each other and separated by a non-magnetic spacer. The resulting sensor is hysteresis free. The sensor's sensitivity, and magnetic saturation characteristics may be easily tuned by simply altering the material, size, shape, or a combination thereof to match the desired sensitivity and saturation characteristics. The sensor is self-resetting at remanence and therefore does not require any pinning techniques.

Novosad, Valentyn (Chicago, IL); Buchanan, Kristen (Batavia, IL)

2010-04-13T23:59:59.000Z

20

The Splitting of the Stratospheric Polar Vortex in the Southern Hemisphere, September 2002: Dynamical Evolution  

Science Conference Proceedings (OSTI)

The polar vortex of the Southern Hemisphere (SH) split dramatically during September 2002. The large-scale dynamical effects were manifest throughout the stratosphere and upper troposphere, corresponding to two distinct cyclonic centers in the ...

Andrew J. Charlton; Alan O’Neill; William A. Lahoz; Paul Berrisford

2005-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Jovian Dynamics. Part II: The Genesis and Equilibration of Vortex Sets  

Science Conference Proceedings (OSTI)

To extend studies of the dynamics of thin atmospheric layers, the generation and equilibration of multiple anticyclonic vortex sets associated with long solitary baroclinic Rossby waves are examined numerically using a primitive equation model ...

G. P. Williams

2002-04-01T23:59:59.000Z

22

The Uses and Limitations of Contour Advection as a Technique for Examining Arctic Vortex Dynamics  

Science Conference Proceedings (OSTI)

A contour advection technique, contour advection with surgery (CAS), is applied to the Northern Hemisphere Arctic vortex during several dynamically active periods in midwinter and at several different levels in the stratosphere. The ability of ...

Michael N. Baker; Derek M. Cunnold

2001-08-01T23:59:59.000Z

23

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong...

24

Evidence of small-scale magnetic concentrations dragged by vortex motion of solar photospheric plasma  

E-Print Network (OSTI)

Vortex-type motions have been measured by tracking bright points in high-resolution observations of the solar photosphere. These small-scale motions are thought to be determinant in the evolution of magnetic footpoints and their interaction with plasma and therefore likely to play a role in heating the upper solar atmosphere by twisting magnetic flux tubes. We report the observation of magnetic concentrations being dragged towards the center of a convective vortex motion in the solar photosphere from high-resolution ground-based and space-borne data. We describe this event by analyzing a series of images at different solar atmospheric layers. By computing horizontal proper motions, we detect a vortex whose center appears to be the draining point for the magnetic concentrations detected in magnetograms and well-correlated with the locations of bright points seen in G-band and CN images.

Balmaceda, L; Palacios, J; Cabello, I; Domingo, V

2010-01-01T23:59:59.000Z

25

Original articles: Vortex states in axially symmetric superconductors in applied magnetic field  

Science Conference Proceedings (OSTI)

We solve analytically the linearized Ginzburg-Landau (GL) equation in the presence of an uniform magnetic field with cylindrical boundary conditions. The solution of the non-linear GL equation is provided as an expansion in the basis of linearized solutions. ... Keywords: Axial magnetic field, Mesoscopic superconductivity, Nonlinear Ginzburg-Landau equation, Vortex

Andrei Ludu; Milorad V. Miloševi?; Francois M. Peeters

2012-03-01T23:59:59.000Z

26

Dissipative dynamics of vortex arrays in trapped Bose-condensed gases: neutron stars physics on $?$K scale  

E-Print Network (OSTI)

We develop a theory of dissipative dynamics of large vortex arrays in trapped Bose-condensed gases. We show that in a static trap the interaction of the vortex array with thermal excitations leads to a non-exponential decay of the vortex structure, and the characteristic lifetime depends on the initial density of vortices. Drawing an analogy with physics of pulsar glitches, we propose an experiment which employs the heating of the thermal cloud in the course of the decay of the vortex array as a tool for a non-destructive study of the vortex dynamics.

P. O. Fedichev; A. E. Muryshev

2000-04-17T23:59:59.000Z

27

Linear Dynamics of the Multiple-Vortex Phenomenon in Tornadoes  

Science Conference Proceedings (OSTI)

The reason for existence of two separate unstable modes, previously described by Gall for flows in vortex simulators, is explored. When the energy equation for an unstable disturbance is considered, it is clear that the most unstable wave must be ...

Robert L. Gall

1985-04-01T23:59:59.000Z

28

Switching a magnetic vortex by interlayer coupling in epitaxially grown Co/Cu/Py/Cu(001) trilayer disks  

SciTech Connect

Epitaxial Py/Cu/Co/Cu(001) trilayers were patterned into micron sized disks and imaged using element-specific photoemission electron microscopy. By varying the Cu spacer layer thickness, we study how the coupling between the two magnetic layers influences the formation of magnetic vortex states. We find that while the Py and Co disks form magnetic vortex domains when the interlayer coupling is ferromagnetic, the magnetic vortex domains of the Py and Co disks break into anti-parallel aligned multidomains when the interlayer coupling is antiferromagnetic. We explain this result in terms of magnetic flux closure between the Py and Co layers for the antiferromagnetic coupling case.

Wu, J.; Carlton, D.; Oelker, E.; Park, J. S.; Jin, E.; Arenholz, E.; Scholl, A.; Hwang, C.; Bokor, J.; Qiu, Z Q

2010-07-16T23:59:59.000Z

29

Observation of coupled vortex gyrations by 70-ps-time and 20-nm-space- resolved full-field magnetic transmission soft x-ray microscopy  

SciTech Connect

We employed time-and space-resolved full-field magnetic transmission soft x-ray microscopy to observe vortex-core gyrations in a pair of dipolar-coupled vortex-state Permalloy (Ni{sub 80}Fe{sub 20}) disks. The 70 ps temporal and 20 nm spatial resolution of the microscope enabled us to simultaneously measure vortex gyrations in both disks and to resolve the phases and amplitudes of both vortex-core positions. We observed their correlation for a specific vortex-state configuration. This work provides a robust and direct method of studying vortex gyrations in dipolar-coupled vortex oscillators.

Jung, Hyunsung; Yu, Young-Sang; Lee, Ki-Suk; Im, Mi-Young; Fischer, Peter; Bocklage, Lars; Vogel, Andreas; Bolte, Markus; Meier, Guido; Kim, Sang-Koog

2010-09-01T23:59:59.000Z

30

Dynamic Switching of the Spin Circulation in Tapered Magnetic Nanodisks  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamic Switching of the Spin Dynamic Switching of the Spin Circulation in Tapered Magnetic Nanodisks Dynamic Switching of the Spin Circulation in Tapered Magnetic Nanodisks Print Monday, 22 April 2013 12:09 fischer-magnetic vortices Ferromagnetic NiFe disks (500-nm-wide and 20-nm-thick), were fabricated by e-beam lithography onto a waveguide structure. Field pulses, generated by launching current pulses into the waveguide trigger the magnetization dynamics in the elements. Using the soft x-ray microscope XM-1 providing 25-nm spatial resolution, circularly polarized soft x-rays give rise to XMCD contrast which allows to record an image of the in-plane circulation of the magnetic vortex. The topology of vortices-areas where there is a spinning motion around an imaginary axis-is a physical phenomenon which is found across a large

31

Magnetic soft x-ray microscopy-imaging fast spin dynamics inmagnetic nanostructures  

SciTech Connect

Magnetic soft X-ray microscopy combines 15nm spatial resolution with 70ps time resolution and elemental sensitivity. Fresnel zone plates are used as X-ray optics and X-ray magnetic circular dichroism serves as magnetic contrast mechanism. Thus scientifically interesting and technologically relevant low dimensional nanomagnetic systems can be imaged at fundamental length and ultrafast time scales in a unique way. Studies include magnetization reversal in magnetic multilayers, nanopatterned systems, vortex dynamics in nanoelements and spin current induced phenomena.

Fischer, Peter; Kim, Dong-Hyun; Mesler, Brooke L.; Chao, Weilun; Sakdinawat, Anne E.; Anderson, Erik H.

2007-06-01T23:59:59.000Z

32

Probabilistic Evaluation of the Dynamics and Predictability of the Mesoscale Convective Vortex of 10–13 June 2003  

Science Conference Proceedings (OSTI)

This study examines the dynamics and predictability of the mesoscale convective vortex (MCV) of 10–13 June 2003 through ensemble forecasting. The MCV of interest developed from a preexisting upper-level disturbance over the southwest United ...

Daniel P. Hawblitzel; Fuqing Zhang; Zhiyong Meng; Christopher A. Davis

2007-04-01T23:59:59.000Z

33

Nonlinear dynamics of drift structures in a magnetized dissipative plasma  

SciTech Connect

A study is made of the nonlinear dynamics of solitary vortex structures in an inhomogeneous magnetized dissipative plasma. A nonlinear transport equation for long-wavelength drift wave structures is derived with allowance for the nonuniformity of the plasma density and temperature equilibria, as well as the magnetic and collisional viscosity of the medium and its friction. The dynamic equation describes two types of nonlinearity: scalar (due to the temperature inhomogeneity) and vector (due to the convectively polarized motion of the particles of the medium). The equation is fourth order in the spatial derivatives, in contrast to the second-order Hasegawa-Mima equations. An analytic steady solution to the nonlinear equation is obtained that describes a new type of solitary dipole vortex. The nonlinear dynamic equation is integrated numerically. A new algorithm and a new finite difference scheme for solving the equation are proposed, and it is proved that the solution so obtained is unique. The equation is used to investigate how the initially steady dipole vortex constructed here behaves unsteadily under the action of the factors just mentioned. Numerical simulations revealed that the role of the vector nonlinearity is twofold: it helps the dispersion or the scalar nonlinearity (depending on their magnitude) to ensure the mutual equilibrium and, thereby, promote self-organization of the vortical structures. It is shown that dispersion breaks the initial dipole vortex into a set of tightly packed, smaller scale, less intense monopole vortices-alternating cyclones and anticyclones. When the dispersion of the evolving initial dipole vortex is weak, the scalar nonlinearity symmetrically breaks a cyclone-anticyclone pair into a cyclone and an anticyclone, which are independent of one another and have essentially the same intensity, shape, and size. The stronger the dispersion, the more anisotropic the process whereby the structures break: the anticyclone is more intense and localized, while the cyclone is less intense and has a larger size. In the course of further evolution, the cyclone persists for a relatively longer time, while the anticyclone breaks into small-scale vortices and dissipation hastens this process. It is found that the relaxation of the vortex by viscous dissipation differs in character from that by the frictional force. The time scale on which the vortex is damped depends strongly on its typical size: larger scale vortices are longer lived structures. It is shown that, as the instability develops, the initial vortex is amplified and the lifetime of the dipole pair components-cyclone and anticyclone-becomes longer. As time elapses, small-scale noise is generated in the system, and the spatial structure of the perturbation potential becomes irregular. The pattern of interaction of solitary vortex structures among themselves and with the medium shows that they can take part in strong drift turbulence and anomalous transport of heat and matter in an inhomogeneous magnetized plasma.

Aburjania, G. D.; Rogava, D. L. [Tbilisi State University, I. Vekua Institute of Applied Mathematics (Georgia); Kharshiladze, O. A. [Ivane Javakhishvili Tbilisi State University (Georgia)

2011-06-15T23:59:59.000Z

34

Magnetic Blockade Mechanism for Quantum Nucleation of Superconducting Vortex-Antivortex Pairs in Zero External Magnetic Field  

E-Print Network (OSTI)

We propose a magnetic dual of the Coulomb blockade effect for quantum nucleation of flux vortex pairs in high-Tc superconducting (HTS) films and grain boundaries in zero applied field. The magnetic blockade instability occurs at {\\theta} = {\\pi}, where {\\theta} is the "vacuum" or theta angle. The {\\theta} term has recently been discussed in the context of several other systems, including charge and spin density waves, topological insulators, the quantum Hall effect, and spontaneous CP violation. Our model predicts a sharp pair creation threshold current at {\\theta} = {\\pi}, analogous to the Coulomb blockade voltage of a tunnel junction, and explains the observed thickness dependence of critical currents in HTS coated conductors. We use the Schr\\"odinger equation to compute the evolving macrostate amplitudes, coupled by a generalized tunneling matrix element. The simulations yield excellent quantitative agreement with measured voltage-current characteristics of bi-crystal and other HTS grain boundary junctions. The model also predicts non-sinusoidal behavior in the voltage oscillations resulting from time-correlated vortex tunneling.

J. H. Miller Jr.; A. I. Wijesinghe

2011-10-12T23:59:59.000Z

35

Impact of a vortex ring on a density interface using a regularized inviscid vortex sheet method  

Science Conference Proceedings (OSTI)

A new, fully three-dimensional, vortex-in-cell method designed to follow the unsteady motion of inviscid vortex sheets with or without small (Boussinesq) density discontinuities is presented. As is common in front-tracking methods, the vortex sheet is ... Keywords: Density discontinuity, Stratified flow, Vortex methods, Vortex sheet dynamics, Vortex-in-cell

Mark J. Stock; Werner J. A. Dahm; Grétar Tryggvason

2008-11-01T23:59:59.000Z

36

On the dynamics of flame edges in diffusion-flame/vortex interactions  

Science Conference Proceedings (OSTI)

We analyze the local flame extinction and reignition of a counterflow diffusion flame perturbed by a laminar vortex ring. Local flame extinction leads to the appearance of flame edges separating the burning and extinguished regions of the distorted mixing layer. The dynamics of these edges is modeled based on previous numerical results, with heat release effects fully taken into account, which provide the propagation velocity of triple and edge flames in terms of the upstream unperturbed value of the scalar dissipation. The temporal evolution of the mixing layer is determined using the classical mixture fraction approach, with both unsteady and curvature effects taken into account. Although variable density effects play an important role in exothermic reacting mixing layers, in this paper the description of the mixing layer is carried out using the constant density approximation, leading to a simplified analytical description of the flow field. The mathematical model reveals the relevant nondimensional parameters governing diffusion-flame/vortex interactions and provides the parameter range for the more relevant regime of local flame extinction followed by reignition via flame edges. Despite the simplicity of the model, the results show very good agreement with previously published experimental results. (author)

Hermanns, Miguel; Linan, Amable [Departamento de Motopropulsion y Termofluidodinamica, Universidad Politecnica de Madrid, Pza. Cardenal Cisneros 3, 28040 Madrid (Spain); Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

2007-04-15T23:59:59.000Z

37

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

38

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

39

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

40

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Reply to "Comment on 'Vortex-assisted photon counts and their magnetic field dependence in single-photon superconducting detectors'"  

SciTech Connect

The vortex crossing rate in thin current-biased superconducting strips, calculated within the London approach employing the concept of a vortex as a particle, is very sensitive to the cutoff at the vortex core size. To account properly for the vortex core, one needs to use microscopic theory.

Bulaevskii, L.N.; Graf, Matthias; Kogan, Vladimir G.

2012-07-16T23:59:59.000Z

42

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic...

43

Vortex lattices in layered superconductors  

Science Conference Proceedings (OSTI)

We study vortex lattices in a superconductor--normal-metal superlattice in a parallel magnetic field. Distorted lattices, resulting from the shear deformations along the layers, are found to be unstable. Under field variation, nonequilibrium configurations undergo an infinite sequence of continuous transitions, typical for soft lattices. The equilibrium vortex arrangement is always a lattice of isocell triangles, without shear.

Prokic, V. (Department of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade (Yugoslavia)); Davidovic, D. (Department of Physics and Astronomy, The Johns Hopkins University, Bloomberg Center, Baltimore, Maryland 21218 (United States) Institute of Physics, P.O. Box 57, 11001 Belgrade (Yugoslavia)); Dobrosavljevic-Grujic, L. (Institute of Physics, P.O. Box 57, 11001 Belgrade (Yugoslavia))

1995-03-01T23:59:59.000Z

44

Identification of vortexes obstructing the dynamo mechanism in laboratory experiments  

E-Print Network (OSTI)

The magnetohydrodynamic dynamo effect explains the generation of self-sustained magnetic fields in electrically conducting flows, especially in geo- and astrophysical environments. Yet the details of this mechanism are still unknown, e.g., how and to which extent the geometry, the fluid topology, the forcing mechanism and the turbulence can have a negative effect on this process. We report on numerical simulations carried out in spherical geometry, analyzing the predicted velocity flow with the so-called Singular Value Decomposition, a powerful technique that allows us to precisely identify vortexes in the flow which would be difficult to characterize with conventional spectral methods. We then quantify the contribution of these vortexes to the growth rate of the magnetic energy in the system. We identify an axisymmetric vortex, whose rotational direction changes periodically in time, and whose dynamics are decoupled from those of the large scale background flow, is detrimental for the dynamo effect. A compar...

Limone, Angelo; Forest, Cary B; Jenko, Frank

2013-01-01T23:59:59.000Z

45

Vortex dynamics : a window into the properties of type-II superconductors  

E-Print Network (OSTI)

3. Electrical resistivity & Electric ?eld-current densityof magnetization, electrical resistivity, and speci?c heatdirection. II.B.3 Electrical resistivity & Electric ?eld-

Taylor, Benjamin Jeremy

2006-01-01T23:59:59.000Z

46

Multiscale dynamics of solar magnetic structures  

E-Print Network (OSTI)

Multiscale topological complexity of solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying this dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al., 2007) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of Grassberger - Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

Vadim M. Uritsky; Joseph M. Davila

2011-11-21T23:59:59.000Z

47

Vortex methods and vortex statistics  

SciTech Connect

Vortex methods originated from the observation that in incompressible, inviscid, isentropic flow vorticity (or, more accurately, circulation) is a conserved quantity, as can be readily deduced from the absence of tangential stresses. Thus if the vorticity is known at time t = 0, one can deduce the flow at a later time by simply following it around. In this narrow context, a vortex method is a numerical method that makes use of this observation. Even more generally, the analysis of vortex methods leads, to problems that are closely related to problems in quantum physics and field theory, as well as in harmonic analysis. A broad enough definition of vortex methods ends up by encompassing much of science. Even the purely computational aspects of vortex methods encompass a range of ideas for which vorticity may not be the best unifying theme. The author restricts himself in these lectures to a special class of numerical vortex methods, those that are based on a Lagrangian transport of vorticity in hydrodynamics by smoothed particles (``blobs``) and those whose understanding contributes to the understanding of blob methods. Vortex methods for inviscid flow lead to systems of ordinary differential equations that can be readily clothed in Hamiltonian form, both in three and two space dimensions, and they can preserve exactly a number of invariants of the Euler equations, including topological invariants. Their viscous versions resemble Langevin equations. As a result, they provide a very useful cartoon of statistical hydrodynamics, i.e., of turbulence, one that can to some extent be analyzed analytically and more importantly, explored numerically, with important implications also for superfluids, superconductors, and even polymers. In the authors view, vortex ``blob`` methods provide the most promising path to the understanding of these phenomena.

Chorin, A.J.

1993-05-01T23:59:59.000Z

48

Nonlinear motion of coupled magnetic vortices in ferromagnetic/non-magnetic/ferromagnetic trilayer  

SciTech Connect

We have investigated a coupled motion of two vortex cores in ferromagnetic/nonmagnetic/ferromagnetic trilayer cynliders by means of micromagnetic simulation. Dynamic motion of two vortex with parallel and antiparallel relative chiralities of curling spins around the vortex cores have been examined after excitation by 1-ns pulsed external field. With systematic variation in non-magnetic spacer layer thickness from 0 to 20 nm, the coupling between two cores becomes significant as the spacer becomes thinner. Significant coupling leads to a nonlinear chaotic coupled motion of two vortex cores for the parallel chiralities and a faster coupled gyrotropic oscillation for the antiparallel chiralities.

Jun, Su-Hyeong; Shim, Je-Ho; Oh, Suhk-Kun; Yu, Seong-Cho; Kim, Dong-Hyun; Mesler, Brooke; Fischer, Peter

2009-07-05T23:59:59.000Z

49

Spontaneous Symmetry-Breaking and the Vortex Lattice ...  

Science Conference Proceedings (OSTI)

... The magnetic vortex lattice of Type-II superconductors, as a quasi ... morphology in single-crystals of pure niobium, a 'conventional' superconductor. ...

50

Overview of magnetic nonlinear beam dynamics in the RHIC  

SciTech Connect

In this article we review our studies of nonlinear beam dynamics due to the nonlinear magnetic field errors in the Relativistic Heavy Ion Collider (RHIC). Nonlinear magnetic field errors, including magnetic field errors in interaction regions (IRs), chromatic sextupoles, and sextupole components from arc main dipoles are discussed. Their effects on beam dynamics and beam dynamic aperture are evaluated. The online methods to measure and correct the IR nonlinear field errors, second order chromaticities, and horizontal third order resonance are presented. The overall strategy for nonlinear corrections in RHIC is discussed.

Luo,Y.; Bai, M.; Beebe-Wang, J.; Bengtsson, J.; Calaga, R.; Fischer, W.; Jain, A.; Pilat, f.; Ptitsyn, V.; Malitsky, N.; Robert-Demolaize, g.; Satogata, T.; Tepikian, S.; Tomas, R.; Trbojevic, D.

2009-05-04T23:59:59.000Z

51

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Imaging of Antiferromagnetic Vortex States Print Direct Imaging of Antiferromagnetic Vortex States Print Magnetic materials are characterized by the ordering of electron spins, with nearest-neighbor spins parallel to each other in ferromagnetic (FM) materials and antiparallel to each other in antiferromagnetic (AFM) materials. As the size of a magnetic system is reduced to micron scale, it has been shown that the spins in an FM microstructure can curl around to form a magnetic vortex state. While there has been intensive activity in the study of vortex states in FM disks, there has been no direct observation of such states in an AFM microstructure, although theory predicts many interesting and unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic disk structures using x-ray magnetic linear dichroism (XMLD) and photoemission electron microscopy (PEEM) at ALS Beamlines 4.0.2 and 11.0.1 , respectively. The experiments observed two types of AFM vortices, one of which has no analogue in FM vortices.

52

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Imaging of Antiferromagnetic Vortex States Print Direct Imaging of Antiferromagnetic Vortex States Print Magnetic materials are characterized by the ordering of electron spins, with nearest-neighbor spins parallel to each other in ferromagnetic (FM) materials and antiparallel to each other in antiferromagnetic (AFM) materials. As the size of a magnetic system is reduced to micron scale, it has been shown that the spins in an FM microstructure can curl around to form a magnetic vortex state. While there has been intensive activity in the study of vortex states in FM disks, there has been no direct observation of such states in an AFM microstructure, although theory predicts many interesting and unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic disk structures using x-ray magnetic linear dichroism (XMLD) and photoemission electron microscopy (PEEM) at ALS Beamlines 4.0.2 and 11.0.1 , respectively. The experiments observed two types of AFM vortices, one of which has no analogue in FM vortices.

53

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Imaging of Antiferromagnetic Vortex States Print Direct Imaging of Antiferromagnetic Vortex States Print Magnetic materials are characterized by the ordering of electron spins, with nearest-neighbor spins parallel to each other in ferromagnetic (FM) materials and antiparallel to each other in antiferromagnetic (AFM) materials. As the size of a magnetic system is reduced to micron scale, it has been shown that the spins in an FM microstructure can curl around to form a magnetic vortex state. While there has been intensive activity in the study of vortex states in FM disks, there has been no direct observation of such states in an AFM microstructure, although theory predicts many interesting and unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic disk structures using x-ray magnetic linear dichroism (XMLD) and photoemission electron microscopy (PEEM) at ALS Beamlines 4.0.2 and 11.0.1 , respectively. The experiments observed two types of AFM vortices, one of which has no analogue in FM vortices.

54

Brownian dynamics of charged particles in a constant magnetic field  

SciTech Connect

Numerical algorithms are proposed for simulating the Brownian dynamics of charged particles in an external magnetic field, taking into account the Brownian motion of charged particles, damping effect, and the effect of magnetic field self-consistently. Performance of these algorithms is tested in terms of their accuracy and long-time stability by using a three-dimensional Brownian oscillator model with constant magnetic field. Step-by-step recipes for implementing these algorithms are given in detail. It is expected that these algorithms can be directly used to study particle dynamics in various dispersed systems in the presence of a magnetic field, including polymer solutions, colloidal suspensions, and, particularly, complex (dusty) plasmas. The proposed algorithms can also be used as thermostat in the usual molecular dynamics simulation in the presence of magnetic field.

Hou, L. J.; Piel, A. [IEAP, Christian-Albrechts Universitaet, D-24118 Kiel (Germany); Miskovic, Z. L. [Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Shukla, P. K. [Institut fuer Theoretische Physik IV, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2009-05-15T23:59:59.000Z

55

Vortex Energy | Open Energy Information  

Open Energy Info (EERE)

by expanding it. Vortex Energy is a company located in Germany . References "Vortex Energy" Retrieved from "http:en.openei.orgwindex.php?titleVortexEnergy&oldid352892...

56

Persistence of Metastable Vortex Lattice Domains in MgB2 in the Presence of Vortex Motion  

Science Conference Proceedings (OSTI)

Recently, extensive vortex lattice metastability was reported in MgB2 in connection with a second-order rotational phase transition. However, the mechanism responsible for these well-ordered metastable vortex lattice phases is not well understood. Using small-angle neutron scattering, we studied the vortex lattice in MgB2 as it was driven from a metastable to the ground state through a series of small changes in the applied magnetic field. Our results show that metastable vortex lattice domains persist in the presence of substantial vortex motion and directly demonstrate that the metastability is not due to vortex pinning. Instead, we propose that it is due to the jamming of counterrotated vortex lattice domains which prevents a rotation to the ground state orientation.

Rastovski, Catherine [University of Notre Dame, IN; Schlesinger, Kimberly [University of Notre Dame, IN; Gannon, William J [Northwestern University, Evanston; Dewhurst, Charles [Institut Laue-Langevin (ILL); Debeer-Schmitt, Lisa M [ORNL; Zhigadlo, Nikolai [ETH Zurich, Switzerland; Karpinski, Janusz [ETH Zurich, Switzerland; Eskildsen, Morten [University of Notre Dame, IN

2013-01-01T23:59:59.000Z

57

Stratospheric Sudden Warmings as Self-Tuning Resonances. Part I: Vortex Splitting Events  

Science Conference Proceedings (OSTI)

The fundamental dynamics of “vortex splitting” stratospheric sudden warmings (SSWs), which are known to be predominantly barotropic in nature, are reexamined using an idealized single-layer f-plane model of the polar vortex. The aim is to ...

N. Joss Matthewman; J. G. Esler

2011-11-01T23:59:59.000Z

58

A Theory for Mixed Vortex Rossby–Gravity Waves in Tropical Cyclones  

Science Conference Proceedings (OSTI)

Vortex–Rossby waves (VRWs) and inertial gravity waves (IGWs) have been proposed to explain the propagation of spiral rainbands and the development of dynamical instability in tropical cyclones (TCs). In this study, a theory for mixed vortex–...

Wei Zhong; Da-Lin Zhang; Han-Cheng Lu

2009-11-01T23:59:59.000Z

59

QCD String as Vortex String in Seiberg-Dual Theory  

E-Print Network (OSTI)

We construct a classical vortex string solution in a Seiberg-dual theory of N=1 supersymmetric SO(N_c) QCD which flows to a confining phase. We claim that this vortex string is a QCD string, as previouly argued by M.Strassler. In SO(N_c) QCD, it is known that stable QCD strings exist even in the presence of dynamical quarks. We show that our vortex strings are stable in the Seiberg-dual theory.

Eto, Minoru; Terashima, Seiji

2007-01-01T23:59:59.000Z

60

Magnetic fields and the dynamics of spiral galaxies  

E-Print Network (OSTI)

We investigate the dynamics of magnetic fields in spiral galaxies by performing 3D MHD simulations of galactic discs subject to a spiral potential. Recent hydrodynamic simulations have demonstrated the formation of inter-arm spurs as well as spiral arm molecular clouds provided the ISM model includes a cold HI phase. We find that the main effect of adding a magnetic field to these calculations is to inhibit the formation of structure in the disc. However, provided a cold phase is included, spurs and spiral arm clumps are still present if $\\beta \\gtrsim 0.1$ in the cold gas. A caveat to two phase calculations though is that by assuming a uniform initial distribution, $\\beta \\gtrsim 10$ in the warm gas, emphasizing that models with more consistent initial conditions and thermodynamics are required. Our simulations with only warm gas do not show such structure, irrespective of the magnetic field strength. Furthermore, we find that the introduction of a cold HI phase naturally produces the observed degree of disorder in the magnetic field, which is again absent from simulations using only warm gas. Whilst the global magnetic field follows the large scale gas flow, the magnetic field also contains a substantial random component that is produced by the velocity dispersion induced in the cold gas during the passage through a spiral shock. Without any cold gas, the magnetic field in the warm phase remains relatively well ordered apart from becoming compressed in the spiral shocks. Our results provide a natural explanation for the observed high proportions of disordered magnetic field in spiral galaxies and we thus predict that the relative strengths of the random and ordered components of the magnetic field observed in spiral galaxies will depend on the dynamics of spiral shocks.

C. L. Dobbs; D. J. Price

2007-10-18T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Direct observation of Oersted-field-induced magnetization dynamics in magnetic nanostripes  

Science Conference Proceedings (OSTI)

We have used time-resolved x-ray photoemission electron microscopy to investigate the magnetization dynamics induced by nanosecond current pulses in NiFe/Cu/Co nanostripes. A large tilt of the NiFe magnetization in the direction transverse to the stripe is observed during the pulses. We show that this effect cannot be quantitatively understood from the amplitude of the Oersted field and the shape anisotropy. High-frequency oscillations observed at the onset of the pulses are attributed to precessional motion of the NiFe magnetization about the effective field. We discuss the possible origins of the large magnetization tilt and the potential implications of the static and dynamic effects of the Oersted field on current-induced domain-wall motion in such stripes.

Uhlir, V. [Institut Neel, Centre national de la recherche scientifique and Universite Joseph Fourier, BP166, F-38042 Grenoble (France); Institute of Physical Engineering, Brno University of Technology, CZ-61669 Brno (Czech Republic); Pizzini, S.; Rougemaille, N.; Ranno, L.; Fruchart, O.; Wagner, E.; Vogel, J. [Institut Neel, Centre national de la recherche scientifique and Universite Joseph Fourier, BP166, F-38042 Grenoble (France); Cros, V. [Unite Mixte de Physique CNRS-Thales, Route departementale 128, F-91767 Palaiseau Cedex (France); Jimenez, E.; Camarero, J. [Departamento Fisica de la Materia Condensada, Instituto ''Nicolas Cabrera'' and Instituto Madrileno de Estudios Avanzados-Nanociencia, Campus Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Urbanek, M. [Institute of Physical Engineering, Brno University of Technology, CZ-61669 Brno (Czech Republic); Gaudin, G. [SPINTEC, UMR8191 CEA/CNRS/UJF/Grenoble INP, INAC, F-38045 Grenoble (France); Tieg, C. [European Synchrotron Radiation Facility, BP200, F-38043 Grenoble (France); Sirotti, F. [Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, F-91192 Gif-sur-Yvette (France)

2011-01-15T23:59:59.000Z

62

DYNAMICS OF CHROMOSPHERIC UPFLOWS AND UNDERLYING MAGNETIC FIELDS  

SciTech Connect

We used H{alpha}-0.1 nm and magnetic field (at 1.56{mu}) data obtained with the New Solar Telescope to study the origin of the disk counterparts to type II spicules, so-called rapid blueshifted excursions (RBEs). The high time cadence of our chromospheric (10 s) and magnetic field (45 s) data allowed us to generate x-t plots using slits parallel to the spines of the RBEs. These plots, along with potential field extrapolation, led us to suggest that the occurrence of RBEs is generally correlated with the appearance of new, mixed, or unipolar fields in close proximity to network fields. RBEs show a tendency to occur at the interface between large-scale fields and small-scale dynamic magnetic loops and thus are likely to be associated with the existence of a magnetic canopy. Detection of kinked and/or inverse {sup Y-}shaped RBEs further confirm this conclusion.

Yurchyshyn, V.; Abramenko, V.; Goode, P. [Big Bear Solar Observatory, New Jersey Institute of Technology, Big Bear City, CA 92314 (United States)] [Big Bear Solar Observatory, New Jersey Institute of Technology, Big Bear City, CA 92314 (United States)

2013-04-10T23:59:59.000Z

63

Twisted vortex state  

E-Print Network (OSTI)

We study a twisted vortex bundle where quantized vortices form helices circling around the axis of the bundle in a "force-free" configuration. Such a state is created by injecting vortices into rotating vortex-free superfluid. Using continuum theory we determine the structure and the relaxation of the twisted state. This is confirmed by numerical calculations. We also present experimental evidence of the twisted vortex state in superfluid 3He-B.

V. B. Eltsov; A. P. Finne; R. Hanninen; J. Kopu; M. Krusius; M. Tsubota; E. V. Thuneberg

2006-02-28T23:59:59.000Z

64

Spinor Bose gases: Explorations of symmetries, magnetism and quantum dynamics  

E-Print Network (OSTI)

Spinor Bose gases form a family of quantum fluids manifesting both magnetic order and superfluidity. This article reviews experimental and theoretical progress in understanding the static and dynamic properties of these fluids. The connection between system properties and the rotational symmetry properties of the atomic states and their interactions are investigated. Following a review of the experimental techniques used for characterizing spinor gases, their mean-field and many-body ground states, both in isolation and under the application of symmetry-breaking external fields, are discussed. These states serve as the starting point for understanding low-energy dynamics, spin textures and topological defects, effects of magnetic dipole interactions, and various non-equilibrium collective spin-mixing phenomena. The paper aims to form connections and establish coherence among the vast range of works on spinor Bose gases, so as to point to open questions and future research opportunities.

Stamper-Kurn, Dan M

2012-01-01T23:59:59.000Z

65

Improved vortex reactor system  

DOE Patents (OSTI)

An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

Diebold, James P. (Lakewood, CO); Scahill, John W. (Evergreen, CO)

1995-01-01T23:59:59.000Z

66

Superconducting magnetic energy storage for electric power system dynamic stabilization  

DOE Green Energy (OSTI)

A Superconducting Magnetic Energy Storage (SMES) system is being developed at the Los Alamos Scientific Laboratory (LASL) for a dynamic stabilizer to be installed in the Bonneville Power Administration (BPA) power system at Tacoma, Washington, by 1982. This unit will be an alternate stabilization method to the dc modulator now used to stabilize the 900 mile, ac intertie between BPA and Southern California. The generation control systems' response to the constantly occuring, small-load and voltage changes can result in negatively damped, low-frequency power oscillations. The dc modulator provides stabilization by fast load control of the High-Voltage dc (HVDC). The SMES unit consists of a 30-MJ solenoid, a 10 MW convertor, a liquid helium dewar and auxiliary systems which operate independent of the HVDC system. The SMES dynamic stabilizer design is presented with status information about the superconducting coil, the converter and other components of the SMES dynamic stabilizer summarized.

Turner, R.

1979-01-01T23:59:59.000Z

67

Superconducting Magnetic Energy Storage for electric power system dynamic stabilization  

DOE Green Energy (OSTI)

A Superconducting Magnetic Energy Storage (SMES) system is being developed at the Los Alamos Scientific Laboratory (LASL) for a dynamic stabilizer to be installed in the Bonneville Power Administration (BPA) power system at Tacoma, Washington, by 1982. This unit will be an alternate stabilization method to the dc modulator now used to stabilize the 900 mile, ac intertie between BPA and Southern California. The generation control systems' response to the constantly occurring, small-load and voltage changes can result in negatively damped, low-frequency power oscillations. The dc modulator provides stabilization by fast load control of the High-Voltage dc (HVDC). The SMES unit consists of a 30-MJ solenoid, a 10-MW convertor, a liquid helium dewar, and auxiliary systems which operate independent of the HVDC system. The SMES dynamic stabilizer design is presented and status information is given about the superconducting coil, the converter, and other components of the SMES dynamic stabilizer.

Turner, R.D.

1979-01-01T23:59:59.000Z

68

Magnetic moment type of lifting from particle dynamics to Vlasov-Maxwell dynamics  

E-Print Network (OSTI)

Techniques for coordinate changes that depend on both dependent and independent variables are developed and applied to the Maxwell-Vlasov Hamiltonian theory. Particle coordinate changes with a new velocity variable dependent on the magnetic field, with spatial coordinates unchanged, are lifted to transform the noncanonical Poisson bracket and, thus, the field Hamiltonian structure of the Vlasov-Maxwell equation. Several examples are given including magnetic coordinates, where the velocity is decomposed into components parallel and perpendicular to the local magnetic field, and the case of spherical velocity coordinates. An example of the lifting procedure is performed to obtain a simplified version of gyrokinetics, where the magnetic moment is used as a coordinate and the dynamics is reduced by elimination of the electric field energy in the Hamiltonian.

P. J. Morrison; M. Vittot; Loic de Guillebon

2012-12-12T23:59:59.000Z

69

Structure of quantum vortex tangle in He-4 counterflow turbulence  

E-Print Network (OSTI)

The main goal of this paper is to present a comprehensive characterization of well developed vortex tangles in a turbulent counterflow in quantum fluids (with a laminar normal fluid component). We analyze extensive numerical simulations using the vortex filament method, solving the full Biot-Savart equations for the vortex dynamics in a wide range of temperatures and counter-flow velocities. In addition to a detailed analysis of traditional characteristics such as vortex line density, anisotropic and curvature parameters of the vortex tangle, we stress other dynamical and statistical characteristics which are either much less studied or even unstudied. The latter include reconnection rates, mean mutual friction forces, drift velocities and the probability distribution functions of various tangle parameters: the loop length, the line curvature, the mean curvature of loops with a given length, etc. During these studies we compare the three main reconnection procedures which are widely used in the literature, and identify which properties are strongly affected by the choice of the reconnection criteria and which of them are practically insensitive to the reconnection procedure. The conclusion is that the vortex filament method in the framework of the Biot-Savart equation sufficiently robust and well suited for the description of the steady state vortex tangle in a quantum counterflow. The Local-Induction Approximation to this equation may be successfully used to analytically establish relationships between mean characteristics of the stochastic vortex tangle.

Luiza Kondaurova; Victor L'vov; Anna Pomyalov; Itamar Procaccia

2013-06-26T23:59:59.000Z

70

Electron trapping by a current vortex F. Bentosela, a;b P. Exner, c;d and V.A. Zagrebnov a;b  

E-Print Network (OSTI)

with the magnetic field due to an electric current forming a localized rotationally symmetric vortex. We show simpler example involves a Pauli electron interacting with a flux tube modelling a vortex magnetic field field Ansatz. To illustrate this point we analyze in this letter the situation where the vortex current

71

VORTEX.PDF  

NLE Websites -- All DOE Office Websites (Extended Search)

vortex generator. Figure 5. The fan in its plenum-a two-speed stove fan mounted in a plywood box. It provides a vacuum at the top of the generator. The ruler is six inches long....

72

Improved vortex reactor system  

DOE Patents (OSTI)

An improved vortex reactor system is described for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor. 12 figs.

Diebold, J.P.; Scahill, J.W.

1995-05-09T23:59:59.000Z

73

A numerical study of steady-state vortex configurations and vortex pinning in type-II superconductors  

E-Print Network (OSTI)

In part I, a numerical study of the mixed states in a mesoscopic type-II superconducting cylinder is described. Steady-state configurations and transient behavior of the magnetic vortices for various values of the applied magnetic field H are presented. Transitions between different multi-vortex states as H is changed is demonstrated by abrupt changes in vortex configurations and jumps in the B vs H plot. An efficient scheme to determine the equilibrium vortex configuration in a mesoscopic system at any given applied field, not limited to the symmetry of the system, is devised and demonstrated. In part II, a superconducting thin film is subject to a non-uniform magnetic field from a vertical magnetic dipole, consisting of two magnetic monopoles of opposite charges. For a film with constant thickness and with no pins, it has been found that the film carries two pairs of vortex-antivortex in the steady state in the imposed flux range of 2.15 < (Phi)+ < 2.90 (in units of flux quantum) and no vortex at all for (Phi)+ <= 2.15. Transitions from a superconducting state with 3 pairs of vortex-antivortex to one with 2 pairs, where a pair of vortex-antivortex annihilates, have been observed in the pseudo-time sequence. With a perturbation with antidots (holes), vortexantivortex pair has been created for lower magnetic fluxes down to (Phi)+ = 1.3. In the sample of size 16(Xi) x 16(Xi), the attraction force between the vortex and antivortex always dominates over the pinning force, so that they eventually come out of pins, move toward each other, and annihilate each other. The annihilation rate, measured with time taken for the annihilation, is reduced noticeably by the increase of the distance between pins, or the increase in the pin size. A simulation of the magnetic vortex pinning in the sample of size 32(Xi) x 32(Xi) suggests we are likely to achieve pinning of the vortex-antivortex pair with the sample size around this and vortex-antivortex separation of 22(Xi). Using this sample as a template, the maximum density of pinned vortices achievable is calculates to be about 7.6 x 10^14 vortices/m2 for (Xi) =~ 1.6A°.

Kim, Sangbum

2004-12-01T23:59:59.000Z

74

Structure and Dynamics of the Sun's Open Magnetic Field  

E-Print Network (OSTI)

The solar magnetic field is the primary agent that drives solar activity and couples the Sun to the Heliosphere. Although the details of this coupling depend on the quantitative properties of the field, many important aspects of the corona - solar wind connection can be understood by considering only the general topological properties of those regions on the Sun where the field extends from the photosphere out to interplanetary space, the so-called open field regions that are usually observed as coronal holes. From the simple assumptions that underlie the standard quasi-steady corona-wind theoretical models, and that are likely to hold for the Sun, as well, we derive two conjectures on the possible structure and dynamics of coronal holes: (1) Coronal holes are unique in that every unipolar region on the photosphere can contain at most one coronal hole. (2) Coronal holes of nested polarity regions must themselves be nested. Magnetic reconnection plays the central role in enforcing these constraints on the field topology. From these conjectures we derive additional properties for the topology of open field regions, and propose several observational predictions for both the slowly varying and transient corona/solar wind.

S. K. Antiochos; C. R. DeVore; J. T. Karpen; Z. Mikic

2007-05-30T23:59:59.000Z

75

Vortex formation of a Bose-Einstein condensate in a rotating deep optical lattice  

Science Conference Proceedings (OSTI)

We study the dynamics of vortex nucleation and lattice formation in a Bose-Einstein condensate in a rotating square optical lattice by numerical simulations of the Gross-Pitaevskii equation. Different dynamical regimes of vortex nucleation are found, depending on the depth and period of the optical lattice. We make an extensive comparison with the experiments by R. A. Williams et al.[Phys. Rev. Lett. 104, 050404 (2010)], especially focusing on the issues of the critical rotation frequency for the first vortex nucleation and the vortex number as a function of rotation frequency.

Kato, Akira; Nakano, Yuki; Kasamatsu, Kenichi; Matsui, Tetsuo [Department of Physics, Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan)

2011-11-15T23:59:59.000Z

76

Sliding contacts and the dynamics of magnetic tape transport  

E-Print Network (OSTI)

Voice coil motor housing Permanent magnet Coil Fig. 7.1: a)motor ( VCM) The VCM consists of a stationary permanent magnet,

Raeymaekers, Bart

2007-01-01T23:59:59.000Z

77

Nuclear magnetic resonance studies of macroscopic morphology and dynamics  

Science Conference Proceedings (OSTI)

Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utility of a number of new and novel techniques using ideal systems primarily as a proof of principle. By taking advantage of the analogy between NMR imaging and diffraction, one may simplify the experiments necessary for characterizing the statistical properties of the sample morphology. For a sample composed of many small features, e.g. a porous medium, the NMR diffraction techniques take advantage of both the narrow spatial range and spatial isotropy of the sample`s density autocorrelation function to obtain high resolution structural information in considerably less time than that required by conventional NMR imaging approaches. The time savings of the technique indicates that NMR diffraction is capable of finer spatial resolution than conventional NMR imaging techniques. Radio frequency NMR imaging with a coaxial resonator represents the first use of cylindrically symmetric field gradients in imaging. The apparatus as built has achieved resolution at the micron level for water samples, and has the potential to be very useful in the imaging of circularly symmetric systems. The study of displacement probability densities in flow through a random porous medium has revealed the presence of features related to the interconnectedness of the void volumes. The pulsed gradient techniques used have proven successful at measuring flow properties for time and length scales considerably shorter than those studied by more conventional techniques.

Barrall, G.A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Materials Science Div.

1995-09-01T23:59:59.000Z

78

Vortex operators in gauge field theories  

SciTech Connect

Several related aspects of the 't Hooft vortex operator are studied. The current picture of the vacuum of quantum chromodynamics, the idea of dual field theories, and the idea of the vortex operator are reviewed first. The Abelian vortex operator written in terms of elementary fields and the calculation of its Green's functions are considered. A two-dimensional solvable model of a Dirac string is presented. The expression of the Green's functions more neatly in terms of Wu and Yang's geometrical idea of sections is addressed. The renormalization of the Green's functions of two kinds of Abelian looplike operators, the Wilson loop and the vortex operator, is studied; for both operators only an overall multiplicative renormalization is needed. In the case of the vortex this involves a surprising cancellation. Next, the dependence of the Green's functions of the Wilson and 't Hooft operators on the nature of the vacuum is discussed. The cluster properties of the Green's functions are emphasized. It is seen that the vortex operator in a massive Abelian theory always has surface-like clustering. The form of Green's functions in terms of Feynman graphs is the same in Higgs and symmetric phases; the difference appears in the sum over all tadpole trees. Finally, systems having fields in the fundamental representation are considered. When these fields enter only weakly into the dynamics, a vortex-like operator is anticipated. Any such operator can no longer be local looplike, but must have commutators at long range. A U(1) lattice gauge theory with two matter fields, one singly charged (fundamental) and one doubly charged (adjoint), is examined. When the fundamental field is weakly coupled, the expected phase transitions are found. When it is strongly coupled, the operator still appears to be a good order parameter, a discontinuous change in its behavior leads to a new phase transition. 18 figures.

Polchinski, J.

1980-07-01T23:59:59.000Z

79

Direct observation of dynamics of single spinning dust grains in weakly magnetized complex plasma  

SciTech Connect

The rotational dynamics of single dust grains in a weak magnetic field is investigated on a kinetic level. Experiments reveal spin-up of spherical dust grains and alignment of their magnetic moments parallel to the magnetic induction vector. The angular velocity of spinning prolate grains varies as magnetic induction increases to 250 G. Spinning dust grains are found to flip over only when the magnetic field magnitude is changing. The results demonstrate that dusty plasma has paramagnetic properties. Qualitative interpretations are proposed to explain newly discovered phenomena.

Dzlieva, E. S.; Karasev, V. Yu., E-mail: plasmadust@yandex.ru [St. Petersburg State University, Institute of Physics (Russian Federation); Petrov, O. F. [Russian Academy of Sciences, Institute for High Energy Densities, Joint Institute for High Temperatures (Russian Federation)

2012-01-15T23:59:59.000Z

80

MAGMA DYNAMICS IN GABBROIC SILLS, KAROO, SOUTH AFRICA: CONSTRAINTS FROM MAGNETIC INVESTIGATIONS AND MAGNETIC FABRICS.  

E-Print Network (OSTI)

??Gabbroic rocks in sills commonly display well organized magnetic fabrics that are generally attributed to magma flow. Yet in a number of cases, magnetic fabrics… (more)

Marsh, Michael C.

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Current Controller with Defined Dynamic Behavior for an Interior Permanent Magnet  

E-Print Network (OSTI)

Current Controller with Defined Dynamic Behavior for an Interior Permanent Magnet Synchronous Motor saturation and changing motor parameters. In this paper a current control scheme is presented that ensures combustion vehicles already provide. Today's modern HEV and EV mostly include interior permanent magnet

Noé, Reinhold

82

Dynamic Analysis and Control of an Energy Storage Flywheel Rotor with Active Magnetic Bearings  

Science Conference Proceedings (OSTI)

Flywheel energy storage is a promising technology for providing intermediate energy storage. An energy storage flywheel is supported by active magnetic bearings (AMBs) to achieve high speed running and increase energy efficiency of the energy storage ... Keywords: Flywheel, Energy Storage, Magnetic Bearing, Rotor Dynamics

Zhang Kai; Dai Xingjian; Zhang Xiaozhang

2010-12-01T23:59:59.000Z

83

Magnetic and electric contributions to the energy loss in a dynamical QCD medium  

E-Print Network (OSTI)

The computation of radiative energy loss in a finite size QCD medium with dynamical constituents is a key ingredient for obtaining reliable predictions for jet quenching in ultra-relativistic heavy ion collisions. It was previously shown that energy loss in dynamical QCD medium is significantly higher compared to static QCD medium. To understand this difference, we here analyze magnetic and electric contributions to energy loss in dynamical QCD medium. We find that the significantly higher energy loss in the dynamical case is entirely due to appearance of magnetic contribution in the dynamical medium. While for asymptotically high energies, the energy loss in static and dynamical medium approach the same value, we find that the physical origin of the energy loss in these two cases is different.

Magdalena Djordjevic

2011-05-21T23:59:59.000Z

84

Effect of self-magnetic fields on the nonlinear dynamics of relativistic electron beam with virtual cathode  

Science Conference Proceedings (OSTI)

The report is devoted to the results of the numerical study of the virtual cathode (VC) formation conditions in the relativistic electron beam (REB) under the influence of the self-magnetic and external axial magnetic fields. The azimuthal instability of the relativistic electron beam leading to the formation of the vortex electron structure in the system was found out. This instability is determined by the influence of the self-magnetic fields of the relativistic electron beam, and it leads to the decrease of the critical value of the electron beam current (current when the non-stationary virtual cathode is formed in the drift space). The typical dependencies of the critical current on the external uniform magnetic field value were discovered. The effect of the beam thickness on the virtual cathode formation conditions was also analyzed.

Hramov, A. E.; Koronovskii, A. A. [Saratov State University, Astrakhanskaja 83, Saratov 410012, Russia Saratov State Technical University, Politechnicheskaja 77, Saratov 410028 (Russian Federation); Kurkin, S. A. [Saratov State University, Astrakhanskaja 83, Saratov 410012 (Russian Federation); Filatova, A. E. [Saratov State Technical University, Politechnicheskaja 77, Saratov 410028 (Russian Federation)

2012-11-15T23:59:59.000Z

85

Variable residence time vortex combustor  

DOE Patents (OSTI)

A variable residence time vortex combustor including a primary combustion chamber for containing a combustion vortex, and a plurality of louvres peripherally disposed about the primary combustion chamber and longitudinally distributed along its primary axis. The louvres are inclined to impel air about the primary combustion chamber to cool its interior surfaces and to impel air inwardly to assist in driving the combustion vortex in a first rotational direction and to feed combustion in the primary combustion chamber. The vortex combustor also includes a second combustion chamber having a secondary zone and a narrowed waist region in the primary combustion chamber interconnecting the output of the primary combustion chamber with the secondary zone for passing only lower density particles and trapping higher density particles in the combustion vortex in the primary combustion chamber for substantial combustion.

Melconian, Jerry O. (76 Beaver Rd., Reading, MA 01867)

1987-01-01T23:59:59.000Z

86

Studying Nanoscale Magnetism and its Dynamics with Soft X-ray Microscopy  

Science Conference Proceedings (OSTI)

Magnetic soft X-ray microscopy allows for imaging magnetic structures at a spatial resolution down to 15nm and a time resolution in the sub-100ps regime. Inherent elemental specificity can be used to image the magnetic response of individual components such as layers in multilayered systems. This review highlights current achievements and discusses the future potential of magnetic soft X-ray microscopy at fsec X-ray sources where snapshot images of ultrafast spin dynamics with a spatial resolution below 10nm will become feasible.

Mccall, Monnikue M; Fischer, Peter

2008-05-01T23:59:59.000Z

87

Dynamics of Bianchi I Universe with Magnetized Anisotropic Dark Energy  

E-Print Network (OSTI)

We study Bianchi type $I$ cosmological model in the presence of magnetized anisotropic dark energy. The energy-momentum tensor consists of anisotropic fluid with anisotropic EoS $p=\\omega{\\rho}$ and a uniform magnetic field of energy density $\\rho_B$. We obtain exact solutions to the field equations using the condition that expansion is proportional to the shear scalar. The physical behavior of the model is discussed with and without magnetic field. We conclude that universe model as well as anisotropic fluid do not approach isotropy through the evolution of the universe.

M. Sharif; M. Zubair

2010-05-25T23:59:59.000Z

88

Dynamics of Bianchi I Universe with Magnetized Anisotropic Dark Energy  

E-Print Network (OSTI)

We study Bianchi type $I$ cosmological model in the presence of magnetized anisotropic dark energy. The energy-momentum tensor consists of anisotropic fluid with anisotropic EoS $p=\\omega{\\rho}$ and a uniform magnetic field of energy density $\\rho_B$. We obtain exact solutions to the field equations using the condition that expansion is proportional to the shear scalar. The physical behavior of the model is discussed with and without magnetic field. We conclude that universe model as well as anisotropic fluid do not approach isotropy through the evolution of the universe.

Sharif, M

2010-01-01T23:59:59.000Z

89

Low NOx Advanced Vortex Combustor  

SciTech Connect

A lean-premixed advanced vortex combustor (AVC) has been developed and tested. The natural gas fueled AVC was tested at the U.S. Department of Energy’s National Energy Technology Laboratory in Morgantown, WV. All testing was performed at elevated pressures and inlet temperatures and at lean fuel-air ratios representative of industrial gas turbines. The improved AVC design exhibited simultaneous NOx /CO/unburned hydrocarbon (UHC) emissions of 4/4/0 ppmv (all emissions corrected to 15% O2 dry). The design also achieved less than 3 ppmv NOx with combustion efficiencies in excess of 99.5%. The design demonstrated marked acoustic dynamic stability over a wide range of operating conditions, which potentially makes this approach significantly more attractive than other lean-premixed combustion approaches. In addition, the measured 1.75% pressure drop is significantly lower than conventional gas turbine combustors, which could translate into an overall gas turbine cycle efficiency improvement. The relatively high velocities and low pressure drop achievable with this technology make the AVC approach an attractive alternative for syngas fuel applications.

Edmonds, R.G. (Ramgen Power Systems, Inc., Bellevue, WA); Williams, J.T. (Ramgen Power Systems, Inc., Bellevue, WA); Steele, R.C. (EPRI); Straub, D.L.; Casleton, K.H.; Bining, Avtar (California Energy Commission, Sacramento, CA)

2008-05-01T23:59:59.000Z

90

Vortex–Vortex Interactions in the Winter Stratosphere  

Science Conference Proceedings (OSTI)

This paper examines the interaction of oppositely signed vortices in the compressible (non-Boussinesq) quasigeostrophic system, with a view to understanding vortex interactions in the polar winter stratosphere. A series of simplifying ...

R. K. Scott; D. G. Dritschel

2006-02-01T23:59:59.000Z

91

Seismology of the Sun : Inference of Thermal, Dynamic and Magnetic Field Structures of the Interior  

E-Print Network (OSTI)

Recent overwhelming evidences show that the sun strongly influences the Earth's climate and environment. Moreover existence of life on this Earth mainly depends upon the sun's energy. Hence, understanding of physics of the sun, especially the thermal, dynamic and magnetic field structures of its interior, is very important. Recently, from the ground and space based observations, it is discovered that sun oscillates near 5 min periodicity in millions of modes. This discovery heralded a new era in solar physics and a separate branch called helioseismology or seismology of the sun has started. Before the advent of helioseismology, sun's thermal structure of the interior was understood from the evolutionary solution of stellar structure equations that mimicked the present age, mass and radius of the sun. Whereas solution of MHD equations yielded internal dynamics and magnetic field structure of the sun's interior. In this presentation, I review the thermal, dynamic and magnetic field structures of the sun's inter...

Hiremath, K M

2012-01-01T23:59:59.000Z

92

Core Dynamics: Magnetic Instabilities Department of Mathematics, University of Glasgow  

E-Print Network (OSTI)

state to a perturba- tion is an essential one in fluid dynamics since it can give significant insight extract energy from the mean field, so the generation mechanism may have a second sink of energy energy without reconnecting field lines and can therefore exist in a perfectly conducting fluid

Fearn, David R.

93

Structure and Evolution of the Large-Scale Flow and an Embedded Upper-Tropospheric Cyclonic Vortex over Northeast Brazil  

Science Conference Proceedings (OSTI)

Horizontal structure and evolution of large-scale flow and an embedded synoptic-scale cyclonic vortex over northeast Brazil as separate systems and dynamical interaction between them are studied at 200 hPa. A quasi-stationary cyclonic vortex with ...

S. K. Mishra; V. B. Rao; M. A. Gan

2001-07-01T23:59:59.000Z

94

A robust forced dynamic sliding mode minimum energy position controller for permanent magnet synchronous motor drives  

Science Conference Proceedings (OSTI)

As a contribution towards improving the environment, a new position controller for vector controlled electric drives employing permanent magnet synchronous motors (PMSM) is presented that achieves approximately 27% less frictional energy loss than a ... Keywords: forced dynamic control, minimum energy manoeuvres, sliding mode control, synchronous motor drives

Stephen J. Dodds; Gunaratnam. Sooriyakumar; Roy Perryman

2008-04-01T23:59:59.000Z

95

Dynamic Reduction of a CH4/Air Chemical Mechanism Appropriate...  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamic Reduction of a CH4Air Chemical Mechanism Appropriate for Investigating Vortex Flame Interactions Title Dynamic Reduction of a CH4Air Chemical Mechanism Appropriate for...

96

Dynamic Phase Transitions In The Spin-2 Ising System Under An Oscillating Magnetic Field Within The Effective-Field Theory  

SciTech Connect

The dynamic phase transitions are studied in the spin-2 Ising model under a time-dependent oscillating magnetic field by using the effective-field theory with correlations. The effective-field dynamic equation is derived by employing the Glauber transition rates and the phases in the system are obtained by solving this dynamic equation. The nature (first- or second-order) of the dynamic phase transition is characterized by investigating the thermal behavior of the dynamic order parameter and the dynamic phase transition temperatures are obtained. The dynamic phase diagrams are presented in (T/zJ, h/zJ) plane.

Ertas, Mehmet; Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Deviren, Bayram [Department of Physics, Nevsehir University, 50300 Nevsehir (Turkey)

2010-12-23T23:59:59.000Z

97

Observable Vortex Properties in Finite Temperature Bose Gases  

E-Print Network (OSTI)

We study the dynamics of vortices in finite temperature atomic Bose-Einstein condensates, focussing on decay rates, precession frequencies and core brightness, motivated by a recent experiment (Freilich et al. Science 329, 1182 (2010)) in which real-time dynamics of a single vortex was observed. Using the ZNG formalism based on a dissipative Gross-Pitaevskii equation for the condensate coupled to a semi-classical Boltzmann equation for the thermal cloud, we find a rapid nonlinear increase of both the decay rate and precession frequency with increasing temperatures. The increase, which is dominated by the dynamical condensate-thermal coupling is also dependent on the intrinsic thermal cloud collisional dynamics; the precession frequency also varies with the initial radial coordinate. The integrated thermal cloud density in the vortex core is for the most part independent of the position of the vortex (except when it is near the condensate edge) with its value increasing with temperature. This could potentially be used as a variant to the method of Coddington et al. (Phys. Rev. A 70, 063607 (2004)) for experimentally determining the temperature.

A. J. Allen; E. Zaremba; C. F. Barenghi; N. P. Proukakis

2012-10-30T23:59:59.000Z

98

Nielsen-Olesen vortex in varying-alpha theories  

E-Print Network (OSTI)

We consider soliton solutions to Bekenstein's theory, for which the fine structure constant $\\alpha=e^2/(4\\pi\\hbar c)$ is allowed to vary due to the presence of a dielectric field pervading the vacuum. More specifically we investigate the effects of a varying $\\alpha$ upon a complex scalar field with a U(1) electromagnetic gauge symmetry subject to spontaneous symmetry breaking. We find vortex solutions to this theory, similar to the Nielsen-Olesen vortex. Near the vortex core the electric charge is typically much larger than far away from the string, lending these strings a superconducting flavour. In general the dielectric field coats the usual local string with a global string envelope. We discuss the cosmological implications of networks of such strings, with particular emphasis on their ability to generate inhomogeneous recombination scenarios. We also consider the possibility of the dielectric being a charged free field. Even though the vacuum of such a field is trivial, we find that the dielectric arranges itself in the shape of a local string, with a quantized magnetic flux at the core -- presumably borrowing these topological features from the underlying Nielsen-Olesen vortex.

J. Magueijo; H. Sandvik; T. W. B. Kibble

2001-01-15T23:59:59.000Z

99

Pseudo Slice Energy Spread in Dynamics of Electron Beams Moving through Magnetic Bends  

E-Print Network (OSTI)

In the previous canonical formulation of beam dynamics for an electron bunch moving ultrarelativistically through magnetic bending systems, we have shown that the transverse dynamics equation for a particle in the bunch has a driving term which behaves as the centrifugal force caused by the particle's initial potential energy due to collective particle interactions within the bunch. As a result, the initial potential energy at the entrance of a bending system, which we call pseudo (kinetic) energy, is indistinguishable from the usual kinetic energy offset from the design energy in its perturbation to particle optics through dispersion and momentum compaction. In this paper, in identifying this centrifugal force on particles as the remnant of the CSR cancellation effect in transverse particle dynamics, we show how the dynamics equation in terms of the canonical momentum for beam motion on a curved orbit is related to the Panofsky-Wenzel theorem for wakefields for beam motion on a straight path. It is shown tha...

Li, Rui

2014-01-01T23:59:59.000Z

100

Vortex ice in nanostructured superconductors  

SciTech Connect

We demonstrate using numerical simulations of nanostructured superconductors that it is possible to realize vortex ice states that are analogous to square and kagome ice. The system can be brought into a state that obeys either global or local ice rules by applying an external current according to an annealing protocol. We explore the breakdown of the ice rules due to disorder in the nanostructure array and show that in square ice, topological defects appear along grain boundaries, while in kagome ice, individual defects appear. We argue that the vortex system offers significant advantages over other artificial ice systems.

Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory; Libal, Andras J [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Dynamics of the Solar Magnetic Network. II. Heating the Magnetized Chromosphere  

E-Print Network (OSTI)

We consider recent observations of the chromospheric network, and argue that the bright network grains observed in the Ca II H & K lines are heated by an as yet unidentified quasi-steady process. We propose that the heating is caused by dissipation of short-period magnetoacoustic waves in magnetic flux tubes (periods less than 100 s). Magnetohydrodynamic (MHD) models of such waves are presented. We consider wave generation in the network due to two separate processes: (a) by transverse motions at the base of the flux tube; and (b) by the absorption of acoustic waves generated in the ambient medium. We find that the former mechanism leads to an efficient heating of the chromosphere by slow magnetoacoustic waves propagating along magnetic field lines. This heating is produced by shock waves with a horizontal size of a few hundred kilometers. In contrast, acoustic waves excited in the ambient medium are converted into transverse fast modes that travel rapidly through the flux tube and do not form shocks, unless the acoustic sources are located within 100 km from the tube axis. We conclude that the magnetic network may be heated by magnetoacoustic waves that are generated in or near the flux tubes.

S. S. Hasan; A. A. van Ballegooijen

2008-02-24T23:59:59.000Z

102

Observation of Laser Induced Magnetization Dynamics in Co/Pd Multilayers with Coherent X-ray Scattering  

SciTech Connect

We report on time-resolved coherent x-ray scattering experiments of laser induced magnetization dynamics in Co/Pd multilayers with a high repetition rate optical pump x-ray probe setup. Starting from a multi-domain ground state, the magnetization is uniformly reduced after excitation by an intense 50 fs laser pulse. Using the normalized time correlation, we study the magnetization recovery on a picosecond timescale. The dynamic scattering intensity is separated into an elastic portion at length scales above 65 nm which retains memory of the initial domain magnetization, and a fluctuating portion at smaller length scales corresponding to domain boundary motion during recovery.

Wu, Benny

2012-04-05T23:59:59.000Z

103

Influence of intergranular exchange coupling on the magnetization dynamics of CoCrPt:SiO{sub 2} granular media  

Science Conference Proceedings (OSTI)

We investigate the effect of Co{sup +} irradiation on the magnetization dynamics of CoCrPt:SiO{sub 2} granular media. Increasing irradiation levels reduce the saturation magnetization and effective anisotropy, which decrease the intrinsic magnetization precession frequency. Furthermore, increasing intergranular exchange coupling results in a qualitative change in the behavior of the magnetic material from a collection of individual grains to a homogeneous thin film, as evidenced in both the switching behavior and dynamics. The frequency change cannot be explained by single crystal macrospin modeling, and can only be reproduced by the inclusion of the dipolar effects and anisotropy distribution inherent in a granular medium.

Brandt, R.; Schmidt, H. [School of Engineering, University of California-Santa Cruz, 1156 High Street, Santa Cruz, California 95064 (United States); Tibus, S. [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Institute of Physics, Chemnitz University of Technology, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Springer, F. [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Fassbender, J. [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden (Germany); Rohrmann, H. [OC Oerlikon Balzers AG, LI-9496 Balzers (Liechtenstein); Albrecht, M. [Institute of Physics, Chemnitz University of Technology, Reichenhainer Str. 70, 09126 Chemnitz (Germany)

2012-08-01T23:59:59.000Z

104

Magnetic vortices for a Ginzburg-Landau type energy with discontinuous constraint. II  

E-Print Network (OSTI)

We study vortex nucleation for minimizers of a Ginzburg-Landau energy with discontinuous constraint. For applied magnetic fields comparable with the first critical field of vortex nucleation, we determine the limiting vorticities.

Hassen Aydi; Ayman Kachmar

2008-07-08T23:59:59.000Z

105

Contributions of the wall boundary layer to the formation of the counter-rotating vortex pair in transverse jets  

E-Print Network (OSTI)

Using high-resolution 3-D vortex simulations, this study seeks a mechanistic understanding of vorticity dynamics in transverse jets at a finite Reynolds number. A full no-slip boundary condition, rigorously formulated in ...

Schlegel, Fabrice

106

Effect of Electric and Magnetic Fields on Spin Dynamics in the Resonant Electric Dipole Moment Experiment  

E-Print Network (OSTI)

A buildup of the vertical polarization in the resonant electric dipole moment (EDM) experiment [Y. F. Orlov, W. M. Morse, and Y. K. Semertzidis, Phys. Rev. Lett. 96, 214802 (2006)] is affected by a horizontal electric field in the particle rest frame oscillating at a resonant frequency. This field is defined by the Lorentz transformation of an oscillating longitudinal electric field and a uniform vertical magnetic one. The effect of a longitudinal electric field is significant, while the contribution from a magnetic field caused by forced coherent longitudinal oscillations of particles is dominant. The effect of electric field on the spin dynamics was not taken into account in previous calculations. This effect is considerable and leads to decreasing the EDM effect for the deuteron and increasing it for the proton. The formula for resonance strengths in the EDM experiment has been derived. The spin dynamics has been calculated.

Alexander J. Silenko

2006-04-11T23:59:59.000Z

107

Vortex Ring Dyons of the SU(2) Yang-Mills-Higgs Model  

Science Conference Proceedings (OSTI)

We present an axially symmetric vortex ring dyons solutions of the SU(2) Yang-Mills-Higgs theory. These vortex rings carry electric charges that are determined by a parameter, -1{<=}{eta}{<=}1. They possess vanishing magnetic charge and are located at a ring centered around the z-axis where the Higgs field vanishes. These stationary vortex ring dyon solutions possess finite energy but they do not satisfy the first order Bogomol'nyi equations. In the Bogomol'nyi-Prasad-Sommerfield (BPS) limit where the Higgs field potential is zero, the time component of the gauge field is parallel to the Higgs field in isospace. The total energy, net electric charge and diameter of the vortex ring increase exponentially to infinity when {eta} approaches {+-}1. On the contrary, when {lambda} = 1, all these three values reach their critical value as {eta} approaches {+-}1.

Lim, Kok-Geng; Teh, Rosy; Wong, Khai-Ming [School of Physics, Universiti Sains Malaysia 11800 USM Penang (Malaysia)

2011-03-30T23:59:59.000Z

108

Transformed Eliassen Balanced Vortex Model  

Science Conference Proceedings (OSTI)

We consider the axisymmetric balanced flow occurring in a thermally forced vortex in which the frictional inflow is confined to a thin boundary layer. Above the boundary layer the absolute angular momentum ½fR2=rv+½fr2 is conserved. We refer to R ...

Wayne H. Schubert; James J. Hack

1983-06-01T23:59:59.000Z

109

Axial dipolar dynamo action in the Taylor-Green vortex  

E-Print Network (OSTI)

We present a numerical study of the magnetic field generated by the Taylor-Green vortex. We show that periodic boundary conditions can be used to mimic realistic boundary conditions by prescribing the symmetries of the velocity and magnetic fields. This gives insight in some problems of central interest for dynamos: the possible effect of velocity fluctuations on the dynamo threshold, the role of boundary conditions on the threshold and on the geometry of the magnetic field generated by dynamo action. In particular, we show that an axial dipolar dynamo similar to the one observed in a recent experiment can be obtained with an appropriate choice of the symmetries of the magnetic field. The nonlinear saturation is studied and a simple model explaining the magnetic Prandtl number dependence of the super/sub critical nature of the dynamo transition is given.

Giorgio Krstulovic; Gentien Thorner; Julien-Piera Vest; Stephan Fauve; Marc Brachet

2011-09-19T23:59:59.000Z

110

Influence of induced axial magnetic field on plasma dynamics and radiative characteristics of Z pinches  

SciTech Connect

The influence of an induced axial magnetic field on plasma dynamics and radiative characteristics of Z pinches is investigated. An axial magnetic field was induced in a novel Z-pinch load: a double planar wire array with skewed wires (DPWAsk), which represents a planar wire array in an open magnetic configuration. The induced axial magnetic field suppressed magneto-Rayleigh-Taylor (MRT) instabilities (with m = 0 and m = 1 instability modes) in the Z-pinch plasma. The influence of the initial axial magnetic field on the structure of the plasma column at stagnation was manifested through the formation of a more uniform plasma column compared to a standard double planar wire array (DPWA) load [V. L. Kantsyrev et al., Phys. Plasmas 15, 030704 (2008)]. The DPWAsk load is characterized by suppression of MRT instabilities and by the formation of the sub-keV radiation pulse that occurs before the main x-ray peak. Gradients in plasma parameters along the cathode-anode gap were observed and analyzed for DPWAsk loads made from low atomic number Z (Al) and mid-Z (brass) wires.

Kantsyrev, V. L.; Esaulov, A. A.; Safronova, A. S.; Osborne, G. C.; Shrestha, I.; Weller, M. E.; Stafford, A.; Shlyaptseva, V. V. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Velikovich, A. L. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Rudakov, L. I. [Icarus Research Inc., Bethesda, Maryland 20824 (United States); Williamson, K. M. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Plasma Engineering Research Laboratory, Texas A and M University, Corpus Christi, TX 78412 (United States)

2011-10-15T23:59:59.000Z

111

Abstract--This paper presents an analysis by which the dynamic performances of a permanent magnet synchronous  

E-Print Network (OSTI)

; Permanent magnet synchronous motor; Speed control; Fuzzy; Sliding Mode. I. INTRODUCTION As a resultAbstract-- This paper presents an analysis by which the dynamic performances of a permanent magnet synchronous motor (PMSM) motor is controlled through a hysteresis current loop and an outer speed loop

Paris-Sud XI, Université de

112

Hairpin vortex formation, a case study for unsteady visualization.  

SciTech Connect

To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plateboundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.

Fischer, P. F.; Papka, M. E.; Szymanski, M.; Tufo, H. M.

1999-08-10T23:59:59.000Z

113

Simulations of Dual-Vortex Interaction within Environmental Shear  

Science Conference Proceedings (OSTI)

For over a century it has been known that each vortex in a multiple vortex configuration will move in response to the other vortices. However, despite advances since that time, the complexities of multiple vortex scenarios when sheared ...

Robert E. Hart; Jenni L. Evans

1999-11-01T23:59:59.000Z

114

Polarization radiation of vortex electrons with large orbital angular momentum  

E-Print Network (OSTI)

Vortex electrons, - freely propagating electrons whose wavefunction has helical wavefronts, - could become a novel tool in the physics of electromagnetic radiation. They carry a non-zero intrinsic orbital angular momentum (OAM) $\\ell$ with respect to the propagation axis and, for \\ell \\gg 1, a large OAM-induced magnetic moment, \\mu ~ \\ell \\mu_B (\\mu_B is the Bohr magneton), which influences the radiation of electromagnetic waves. Here, we consider in detail the OAM-induced effects by such electrons in two forms of polarization radiation, namely in Cherenkov radiation and transition radiation. Thanks to the large \\ell, we can neglect quantum or spin-induced effects, which are of the order of \\hbar \\omega/E_e \\ll 1, but retain the magnetic moment contribution \\ell \\hbar \\omega/E_e \\lesssim 1, which makes the quasiclassical approach to polarization radiation applicable. We discuss the magnetic moment contribution to polarization radiation, which has never been experimentally observed, and study how its visibility depends on the kinematical parameters and the medium permittivity. In particular, it is shown that this contribution can, in principle, be detected in azimuthally non-symmetrical problems, for example when vortex electrons obliquely cross a metallic screen (transition radiation) or move nearby it (diffraction radiation). We predict a left-right angular asymmetry of the transition radiation (in the plane where the charge radiation distributions would stay symmetric), which appears due to an effective interference between the charge radiation field and the magnetic moment one. Numerical values of this asymmetry for vortex electrons with E_e = 300keV and \\ell = O(100-1000) are O(0.1-1%), and we argue that this effect could be detected with existing technology. The finite conductivity of the target and frequency dispersion play the crucial roles in these predictions.

Igor P. Ivanov; Dmitry V. Karlovets

2013-05-28T23:59:59.000Z

115

Acceleration and dynamics of an electron in the degenerate and magnetized plasma elliptical waveguide  

SciTech Connect

The dynamics and energy gain of an electron in the field of a transverse magnetic wave propagating inside an elliptical degenerate plasma waveguide is analytically investigated by finding the field components of the TM{sub mr} mode in this waveguide. Besides, by solving the relativistic momentum and energy equations the deflection angle and the acceleration gradient of the electron in the waveguide are obtained. Furthermore, the field components of the hybrid mode and the transferred power in the presence of the magnetic field in this waveguide are found. Also by applying the boundary conditions at the plasma-conductor interface, we calculate the dispersion relation. It is shown that the cutoff frequency of this mode is dependent on the plasma density but independent of the magnetic field. Then, a single-electron model for numerical calculations of the electron deflection angle and acceleration gradient inside the magnetized plasma-filled elliptical waveguide is generally presented to be used as a cascading process for the acceleration purposes.

Abdoli-Arani, A.; Jazi, B. [Department of Photonics, Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Shokri, B. [Physics Department and Laser-Plasma Research Institute, G. C. Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

2013-02-15T23:59:59.000Z

116

The structure and dynamics of self-assembling colloidal monolayers in oscillating magnetic fields  

E-Print Network (OSTI)

Many fascinating phenomena such as large-scale collective flows, enhanced fluid mixing and pattern formation have been observed in so-called active fluids, which are composed of particles that can absorb energy and dissipate it into the fluid medium. For active particles immersed in liquids, fluid-mediated viscous stresses can play an important role on the emergence of collective behavior. Here, we experimentally investigate their role in the dynamics of self-assembling magnetically-driven colloidal particles which can rapidly form organized hexagonal structures. We find that viscous stresses reduce hexagonal ordering, generate smaller clusters, and significantly decrease the rate of cluster formation, all while holding the system at constant number density. Furthermore, we show that time and length scales of cluster formation depend on the Mason number (Mn), or ratio of viscous to magnetic forces, scaling as t / Mn and L / Mn^(1/2). Our results suggest that viscous stresses hinder collective behavior in a se...

Koser, Alison E; Arratia, Paulo E

2013-01-01T23:59:59.000Z

117

Dynamic magnetic shield for the CLAS12 central TOF detector photomultiplier tubes  

SciTech Connect

The Central Time-of-Flight detector for the Jefferson Laboratory 12-GeV upgrade is being designed with linear-focused photomultiplier tubes that require a robust magnetic shield against the CLAS12 main 5-T solenoid fringe fields of 100 mT (1 kG). Theoretical consideration of a ferromagnetic cylinder in an axial field has demonstrated that its shielding capability decreases with increasing length. This observation has been confirmed with finite element analysis using Poisson model software. Several shields composed of coaxial ferromagnetic cylinders have been studied. All difficulties caused by saturation effects were overcome with a novel dynamical shield, which utilizes a demagnetizing solenoid between the shielding cylinders. Basic dynamical shields for ordinary linear-focused 2-in. photomultiplier tubes were designed and tested both with models and experimental prototypes at different external field and demagnetizing current values. Our shield design reduces the 1 kG external axial field by a factor of 5000.

V. Baturin, V. Burkert, D.S. Carman, L. Elouadrhyri, D. Grilli, D. Kashy, E. Pasyuk, L. Quettier, B. Wieland

2012-02-01T23:59:59.000Z

118

THE DYNAMICS OF THE SOLAR MAGNETIC FIELD: POLARITY REVERSALS, BUTTERFLY DIAGRAM, AND QUASI-BIENNIAL OSCILLATIONS  

SciTech Connect

The spatio-temporal dynamics of the solar magnetic field has been investigated by using NSO/Kitt Peak magnetic synoptic maps covering the period 1976 August-2003 September. The field radial component, for each heliographic latitude, has been decomposed in intrinsic mode functions through the Empirical Mode Decomposition in order to investigate the time evolution of the various characteristic oscillating modes at different latitudes. The same technique has also been applied on synoptic maps of the meridional and east-west components, which were derived from the observed line-of-sight projection of the field by using the differential rotation. Results obtained for the {approx}22 yr cycle, related to the polarity inversions of the large-scale dipolar field, show an antisymmetric behavior with respect to the equator in all the field components and a marked poleward flux migration in the radial and meridional components (from about -35 Degree-Sign and +35 Degree-Sign in the southern and northern hemispheres, respectively). The quasi-biennial oscillations (QBOs) are also identified as a fundamental timescale of variability of the magnetic field and associated with poleward magnetic flux migration from low latitudes around the maximum and descending phase of the solar cycle. Moreover, signs of an equatorward drift, at a {approx}2 yr rate, seem to appear in the radial and toroidal components. Hence, the QBO patterns suggest a link to a dynamo action. Finally, the high-frequency component of the magnetic field, at timescales less than 1 yr, provides the most energetic contribution and it is associated with the outbreaks of the bipolar regions on the solar surface.

Vecchio, A.; Meduri, D.; Carbone, V. [Dipartimento di Fisica, Universita della Calabria, 87036 Rende (Italy); Laurenza, M.; Storini, M., E-mail: vecchio@fis.unical.it [INAF/IFSI-Roma, Via del Fosso del Cavaliere 100, 00133 Roma (Italy)

2012-04-10T23:59:59.000Z

119

The idea of vortex energy  

E-Print Network (OSTI)

This work formulates and gives grounds for general principles and theorems that question the energy function doctrine and its quantum version as a genuine law of nature without borders of adequacy. The emphasis is on the domain where the energy of systems is conserved -- I argue that only in its tiny part the energy is in the kinetic, potential and thermal forms describable by a generalized thermodynamic potential, whereas otherwise the conserved energy constitutes a whole linked to vortex forces, and can be a factor of things like persistent currents and dark matter.

V. E. Shapiro

2011-09-12T23:59:59.000Z

120

Aging memory and glassiness of a driven vortex , Guohong Li1  

E-Print Network (OSTI)

1 Aging memory and glassiness of a driven vortex system. Xu Du1 , Guohong Li1 , Eva Y. Andrei1 , M memory, aging and nonlinear-dynamics. Glasses[1-11], interfaces[12] and fractures are some examples[13 the deviation from equilibrium. After removing the force, the system ages with time and its subsequent response

Andrei, Eva Y.

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they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
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121

MAGNETIC NEUTRON SCATTERING  

SciTech Connect

Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern science, ranging from large-scale structures and dynamics of polymers and biological systems, to electronic properties of today's technological materials. Neutron scattering developed into a vast field, encompassing many different experimental techniques aimed at exploring different aspects of matter's atomic structure and dynamics. Modern magnetic neutron scattering includes several specialized techniques designed for specific studies and/or particular classes of materials. Among these are magnetic reflectometry aimed at investigating surfaces, interfaces, and multilayers, small-angle scattering for the large-scale structures, such as a vortex lattice in a superconductor, and neutron spin-echo spectroscopy for glasses and polymers. Each of these techniques and many others offer exciting opportunities for examining magnetism and warrant extensive reviews, but the aim of this chapter is not to survey how different neutron-scattering methods are used to examine magnetic properties of different materials. Here, we concentrate on reviewing the basics of the magnetic neutron scattering, and on the recent developments in applying one of the oldest methods, the triple axis spectroscopy, that still is among the most extensively used ones. The developments discussed here are new and have not been coherently reviewed. Chapter 2 of this book reviews magnetic small-angle scattering, and modern techniques of neutron magnetic reflectometry are discussed in Chapter 3.

ZALIZNYAK,I.A.; LEE,S.H.

2004-07-30T23:59:59.000Z

122

Stable optical vortex solitons in pair plasmas  

Science Conference Proceedings (OSTI)

It is shown that the pair plasmas with small temperature asymmetry can support existence of localized as well as delocalized optical vortex solitons. Coexistence of such solitons is possible due to peculiar form of saturating nonlinearity which has a focusing-defocusing nature--for weak amplitudes being focusing becoming defocusing for higher amplitudes. It is shown that delocalized vortex soliton is stable in entire region of its existence while single- and multicharged localized vortex solitons are unstable for low amplitudes and become stable for relativistic amplitudes.

Berezhiani, V. I.; Shatashvili, N. L. [Plasma Physics Department, Andronikashvili Institute of Physics, Tbilisi 0177 (Georgia); Department of Physics, Faculty of Exact and Natural Sciences, Javakhishvili Tbilisi State University, Tbilisi 0128 (Georgia); Mahajan, S. M. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

2010-05-15T23:59:59.000Z

123

Dynamics of nuclear polarization in InGaAs quantum dots in a transverse magnetic field  

SciTech Connect

The time-resolved Hanle effect is examined for negatively charged InGaAs/GaAs quantum dots. Experimental data are analyzed by using an original approach to separate behavior of the longitudinal and transverse components of nuclear polarization. This made it possible to determine the rise and decay times of each component of nuclear polarization and their dependence on transverse magnetic field strength. The rise and decay times of the longitudinal component of nuclear polarization (parallel to the applied field) were found to be almost equal (approximately 5 ms). An analysis of the transverse component of nuclear polarization shows that the corresponding rise and decay times differ widely and strongly depend on magnetic field strength, increasing from a few to tens of milliseconds with an applied field between 20 and 100 mT. Current phenomenological models fail to explain the observed behavior of nuclear polarization. To find an explanation, an adequate theory of spin dynamics should be developed for the nuclear spin system of a quantum dot under conditions of strong quadrupole splitting.

Verbin, S. Yu., E-mail: syuv54@mail.ru; Gerlovin, I. Ya.; Ignatiev, I. V., E-mail: ivan_ignatiev@mail.ru; Kuznetsova, M. S.; Cherbunin, R. V. [St. Petersburg State University, Spin Optics Laboratory (Russian Federation); Flisinski, K.; Yakovlev, D. R.; Bayer, M. [Technische Universitaet Dortmund (Germany)

2012-04-15T23:59:59.000Z

124

The structure and dynamics of self-assembling colloidal monolayers in oscillating magnetic fields  

E-Print Network (OSTI)

Many fascinating phenomena such as large-scale collective flows, enhanced fluid mixing and pattern formation have been observed in so-called active fluids, which are composed of particles that can absorb energy and dissipate it into the fluid medium. For active particles immersed in liquids, fluid-mediated viscous stresses can play an important role on the emergence of collective behavior. Here, we experimentally investigate their role in the dynamics of self-assembling magnetically-driven colloidal particles which can rapidly form organized hexagonal structures. We find that viscous stresses reduce hexagonal ordering, generate smaller clusters, and significantly decrease the rate of cluster formation, all while holding the system at constant number density. Furthermore, we show that time and length scales of cluster formation depend on the Mason number (Mn), or ratio of viscous to magnetic forces, scaling as t / Mn and L / Mn^(1/2). Our results suggest that viscous stresses hinder collective behavior in a self-assembling colloidal system.

Alison E. Koser; Nathan C. Keim; Paulo E. Arratia

2013-11-18T23:59:59.000Z

125

Dynamics of lipid bilayers from comparative analysis of 2 nuclear magnetic resonance relaxation data as a function  

E-Print Network (OSTI)

to the predominant mechanisms of nuclear spin relax- ation in lipid bilayers. To critically test various dDynamics of lipid bilayers from comparative analysis of 2 H and 13 C nuclear magnetic resonance September 1997 Analysis of the nuclear spin relaxation rates of lipid membranes provides a powerful means

Brown, Michael F.

126

Self-consistent modeling of the dynamic evolution of magnetic island growth in the presence of stabilizing ECCD  

E-Print Network (OSTI)

The most promising technique for the control of neoclassical tearing modes in tokamak experiments is the compensation of the missing bootstrap current with electron-cyclotron current drive. In this frame, the dynamics of magnetic islands has been studied extensively in terms of the modified Rutherford equation, including the presence of current drive, either analytically described or computed by numerical methods. In this article, a self-consistent model for the dynamic evolution of the magnetic island and the driven current is derived, which takes into account the island's magnetic topology and its effect on the current drive. The model combines the modified Rutherford equation with a ray-tracing approach to electron-cyclotron wave propagation and absorption. Numerical results exhibit a decrease in the time required for complete stabilization with respect to the conventional computation (not taking into account the island geometry), which increases with increasing initial island size and radial misalignment ...

Chatziantonaki, Ioanna; Isliker, Heinz; Vlahos, Loukas

2013-01-01T23:59:59.000Z

127

Characterization of The Dalles Dam Spillbay 6 Vortex Using Surface Entrained Sensor Fish Device: Preliminary Report  

DOE Green Energy (OSTI)

This document summarizes the pilot study to characterize The Dalles Dam Spillbay 6 vortex using a surface entrained Sensor Fish device. It was conducted by Pacific Northwest National Laboratory (PNNL) on April 13 and 14, 2006. The total spill was controlled at approximately 110 kcfs, the forebay elevation was 157.89 ft, and the discharge of Bay 6 at the tested gate opening of 14 ft was approximately 18 kcfs. The objectives of the full study are to (1) develop baseline conditions for the detailed analysis of Sensor Fish measurements by deploying Sensor Fish in different surface locations in the vortex periphery; (2) observe the entrainment pattern and extract hydraulic data of interest such as acceleration, rotation, pressure, and estimated velocity of Sensor Fish or drogues; (3) integrate the experimental results with companion computational fluid dynamics (CFD) simulations and inertial particle tracking studies. A total of 12 Sensor Fish were released in the surface at upstream edge, left edge, downstream edge, and the core of the vortex at Bay 6. Because of the high discharge, the vortex patterns at the test condition were less consistent than the patterns observed at lower discharges. Compared with the Sensor Fish released at mid-bay at Bay 6, Sensor Fish released from the surface at the vortex experienced higher pressure fluctuations, a larger percentage of severe events, and much more rapid angular velocities.

Deng, Zhiqun; Richmond, Marshall C.; Carlson, Thomas J.

2006-06-22T23:59:59.000Z

128

Vortex Breakdown in Atmospheric Columnar Vortices  

Science Conference Proceedings (OSTI)

Vortex breakdown occurs in tornadoes and waterspouts. This phenomenon may give information on the state and future behavior of those whirlwinds. Because of the rarity of recorded events, archival sources are consulted for qualitative descriptions ...

H. J. Lugt

1989-12-01T23:59:59.000Z

129

Bubble Behavior in a Taylor Vortex  

E-Print Network (OSTI)

We present an experimental study on the behavior of bubbles captured in a Taylor vortex. The gap between a rotating inner cylinder and a stationary outer cylinder is filled with a Newtonian mineral oil. Beyond a critical ...

Deng, Rensheng

130

Barotropic Vortex Evolution on a Beta Plane  

Science Conference Proceedings (OSTI)

A barotropic, primitive equation (shallow water) model is used on the beta plane to investigate the influence of divergence, total relative angular momentum (RAM) and advective nonlinearities on the evolution of a hurricane-like vortex. The ...

Lloyd J. Shapiro; Katsuyuki V. Ooyama

1990-01-01T23:59:59.000Z

131

Vortex Hydro Energy - National Renewable Energy Laboratory  

Vortex Hydro Energy, LLC Michael M. Bernitsas Ph.D., CEO and CTO Gus Simiao MSE, MBA, Dir. of Business Development NREL’s 20th Annual, Industry Growth Forum

132

Vortex-Driven Sensitivity in Deformation Flow  

Science Conference Proceedings (OSTI)

A sensitivity mechanism for the interaction of two vortices in a two-dimensional deformation background flow is explored. A nonlinear model describing the vortex interaction up to a critical merging distance is developed. This model shows that in ...

Zhiyuan Liu; Paul J. Roebber

2008-12-01T23:59:59.000Z

133

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

a magnetic vortex are not actually swirling around the core. What they can do is flip in place, and the core-defined as the area where spins point out of the plane-can be...

134

COMPARISON OF FORCE-FREE CORONAL MAGNETIC FIELD MODELING USING VECTOR FIELDS FROM HINODE AND SOLAR DYNAMICS OBSERVATORY  

Science Conference Proceedings (OSTI)

Photospheric magnetic vector maps from two different instruments are used to model the nonlinear force-free coronal magnetic field above an active region. We use vector maps inferred from polarization measurements of the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (HMI) and the Solar Optical Telescope's Spectropolarimeter (SP) on board Hinode. Besides basing our model calculations on HMI data, we use both SP data of original resolution and scaled down to the resolution of HMI. This allows us to compare the model results based on data from different instruments and to investigate how a binning of high-resolution data affects the model outcome. The resulting three-dimensional magnetic fields are compared in terms of magnetic energy content and magnetic topology. We find stronger magnetic fields in the SP data, translating into a higher total magnetic energy of the SP models. The net Lorentz forces of the HMI and SP lower boundaries verify their force-free compatibility. We find substantial differences in the absolute estimates of the magnetic field energy but similar relative estimates, e.g., the fraction of excess energy and of the flux shared by distinct areas. The location and extension of neighboring connectivity domains differ and the SP model fields tend to be higher and more vertical. Hence, conclusions about the magnetic connectivity based on force-free field models are to be drawn with caution. We find that the deviations of the model solution when based on the lower-resolution SP data are small compared to the differences of the solutions based on data from different instruments.

Thalmann, J. K.; Tiwari, S. K.; Wiegelmann, T., E-mail: thalmann@mps.mpg.de [Max-Plank-Institut fuer Sonnensystemforschung, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau (Germany)

2013-05-20T23:59:59.000Z

135

Nonlinear Motion of a Shallow Water Barotropic Vortex  

Science Conference Proceedings (OSTI)

Nonlinear motions of a shallow water barotropic vortex on a ? plane differ substantially from the analogous linear motions. The nonlinear model described here, in which wavenumber 1–3 asymmetries interact with each other and the mean vortex, ...

H. E. Willoughby

1994-12-01T23:59:59.000Z

136

Interactions between a Submesoscale Anticyclonic Vortex and a Front  

Science Conference Proceedings (OSTI)

The evolution of a submesoscale anticyclonic vortex was observed by high-frequency Doppler radio current meters and satellite radiometers. The vortex formed between two large cyclones to the southwest of Oahu, Hawaii. The radius of the core was ...

Cédric Chavanne; Pierre Flament; Klaus-Werner Gurgel

2010-08-01T23:59:59.000Z

137

A Highly Configurable Vortex Initialization Method for Tropical Cyclones  

Science Conference Proceedings (OSTI)

A highly configurable vortex initialization methodology has been constructed in order to permit manipulation of the initial vortex structure in numerical models of tropical cyclones. By using distinct specifications of the flow in the boundary ...

Eric D. Rappin; David S. Nolan; Sharanya J. Majumdar

138

Case Study of an Orographically Induced Mesoscale Vortex (Denver Cyclone)  

Science Conference Proceedings (OSTI)

Observations taken during the Convection Initiation and Downburst Experiment (CINDE) are used to describe the formation and structure of an orographically induced mesoscale vortex that frequently occurs in northeastern Colorado. This vortex, ...

J. M. Wilczak; T. W. Christian

1990-05-01T23:59:59.000Z

139

A Highly Configurable Vortex Initialization Method for Tropical Cyclones  

Science Conference Proceedings (OSTI)

A highly configurable vortex initialization methodology has been constructed in order to permit manipulation of the initial vortex structure in numerical models of tropical cyclones. By using distinct specifications of the flow in the boundary ...

Eric D. Rappin; David S. Nolan; Sharanya J. Majumdar

2013-10-01T23:59:59.000Z

140

Studies of transition metal and overlayers dynamics and magnetism by HE and spin-polarized metastable HE beam spectroscopies  

DOE Green Energy (OSTI)

Experimental results for the investigation of quantum delocalization of hydrogen on the Pd(111) surface; the investigation of the structural and dynamical trends in the growth of Cu overlayers on Pd(111) surface; and the investigation of the magnetic structure of the NiO(111) surface using spin-polarized metastable He beam scattering are included in this paper. Planned research is also discussed.

El-Batanouny, M.

1992-01-16T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Proposed Detection of Dynamically Oriented Nuclei by Acoustic Nuclear Magnetic Resonance  

Science Conference Proceedings (OSTI)

It is proposed that acoustic nuclear magnetic resonance be used to detect steady?state nuclear orientation achieved by the Jeffries Abragam effect. This is a new scheme for double magnetic resonance (ADMR) in contrast with conventional DMR

Mary Duns Scotus Breitbart; W. A. Barker

1967-01-01T23:59:59.000Z

142

Stabilization of vortex solitons in nonlocal nonlinear media  

SciTech Connect

We study the evolution of vortex solitons in optical media with a nonlocal nonlinear response. We employ a modulation theory for the vortex parameters based on an averaged Lagrangian, and analyze the azimuthal evolution of both the vortex width and diffractive radiation. We describe analytically the physical mechanism for vortex stabilization due to the long-range nonlocal nonlinear response, the effect observed earlier in numerical simulations only.

Minzoni, Antonmaria A. [Fenomenos Nonlineales y Mecanica (FENOMEC), Department of Mathematics and Mechanics, Instituto de Investigacion en Matematicas Aplicadas y Sistemas, Universidad Nacional Autonoma de Mexico, 01000 Mexico D.F. (Mexico); Smyth, Noel F. [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Worthy, Annette L. [School of Mathematics and Applied Statistics, University of Wollongong, Wollongong NSW 2522 (Australia); Kivshar, Yuri S. [Nonlinear Physics Center, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2007-12-15T23:59:59.000Z

143

Dynamic high pressure process for fabricating superconducting and permanent magnetic materials  

DOE Patents (OSTI)

Shock wave formation of superconductive ceramic oxide electric and magnetic circuit elements with improved microstructures and mechanical properties. 10 figs.

Nellis, W.J.; Maple, M.B.; Geballe, T.H.

1987-10-23T23:59:59.000Z

144

Vortex Hydro Energy LLC | Open Energy Information  

Open Energy Info (EERE)

Hydro Energy LLC Hydro Energy LLC Jump to: navigation, search Name Vortex Hydro Energy LLC Address 4870 West Clark Rd Suite 108 Place Ypsilanti Zip 48197 Sector Marine and Hydrokinetic Phone number 734.971.4020 Website http://www.vortexhydroenergy.c Region United States LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This company is listed in the Marine and Hydrokinetic Technology Database. This company is involved in the following MHK Projects: Marine Hydrodynamics Laboratory at the University of Michigan This company is involved in the following MHK Technologies: Vortex Induced Vibrations Aquatic Clean Energy VIVACE This article is a stub. You can help OpenEI by expanding it. Retrieved from "http://en.openei.org/w/index.php?title=Vortex_Hydro_Energy_LLC&oldid=678497

145

A Study of Premixed Propagating Flame Vortex Interaction  

Science Conference Proceedings (OSTI)

Experimental data is presented for the interaction between a propagating flame and a simple vortex flow field structure generated in the wake of solid obstacles. The interaction between gas movement and obstacles creates vortex shedding forming a simple ... Keywords: Combustion, Flame/Vortex, PIV, Visualization

G. K. Hargrave; S. Jarvis

2006-04-01T23:59:59.000Z

146

Soft X-Ray Imaging of spin dynamics at high spatial and temporalresolution  

Science Conference Proceedings (OSTI)

Soft X-ray microscopy provides element specific magnetic imaging with a spatial resolution down to 15nm. At XM-1, the full-field soft X-ray microscope at the Advanced Light Source in Berkeley, a stroboscopic pump and probe setup has been developed to study fast magnetization dynamics in ferromagnetic elements with a time resolution of 70ps which is set by the width of the X-ray pulses from the synchrotron. Results obtained with a 2 {micro}m x 4 {micro}m x 45nm rectangular permalloy sample exhibiting a seven domain Landau pattern reveal dynamics up to several nsec after the exciting magnetic field pulse. Domain wall motion, a gyrotropic vortex motion, and a coupling between vortices in the rectangular geometry are observed.

Mesler, Brooke L.; Fischer, Peter; Chao, Weilun; Anderson, Erik H.

2007-06-01T23:59:59.000Z

147

Random walk of magnetic field lines in dynamical turbulence: A field line tracing method. I. Slab turbulence  

SciTech Connect

To study the wandering of magnetic field lines is an important subject in theoretical physics. Results of field line random walk theories can be applied in plasma physics as well as astrophysics. Previous investigations are based on magnetostatic models. These models have been used in analytical work as well as in computer simulations to warrant mathematical and numerical tractability. To replace the magnetostatic model by a dynamical turbulence model is a difficult task. In the present article, a field line tracing method is used to describe field line wandering in dynamical magnetic turbulence. As examples different models are employed, namely, the plasma wave model, the damping model of dynamical turbulence, and the random sweeping model. It is demonstrated that the choice of the turbulence model has a very strong influence on the field line structure. It seems that if dynamical turbulence effects are included, Markovian diffusion can be found for other forms of the wave spectrum as in the magnetostatic model. Therefore, the results of the present paper are useful to specify turbulence models. As a further application we consider charged particle transport at early times.

Shalchi, A. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

2010-08-15T23:59:59.000Z

148

Dynamic Contrast-Enhanced Magnetic Resonance Imaging of the Metastatic Potential of Melanoma Xenografts  

SciTech Connect

Purpose: Gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been suggested as a useful noninvasive method for characterizing the physiologic microenvironment of tumors. In the present study, we investigated whether Gd-DTPA-based DCE-MRI has the potential to provide biomarkers for hypoxia-associated metastatic dissemination. Methods and Materials: C-10 and D-12 melanoma xenografts were used as experimental tumor models. Pimonidazole was used as a hypoxia marker. A total of 60 tumors were imaged, and parametric images of K{sup trans} (volume transfer constant of Gd-DTPA) and v{sub e} (fractional distribution volume of Gd-DTPA) were produced by pharmacokinetic analysis of the DCE-MRI series. The host mice were killed immediately after DCE-MRI, and the primary tumor and the lungs were resected and prepared for histologic assessment of the fraction of pimonidazole-positive hypoxic tissue and the presence of lung metastases, respectively. Results: Metastases were found in 11 of 26 mice with C-10 tumors and 14 of 34 mice with D-12 tumors. The primary tumors of the metastatic-positive mice had a greater fraction of hypoxic tissue (p = 0.00031, C-10; p < 0.00001, D-12), a lower median K{sup trans} (p = 0.0011, C-10; p < 0.00001, D-12), and a lower median v{sub e} (p = 0.014, C-10; p = 0.016, D-12) than the primary tumors of the metastatic-negative mice. Conclusions: These findings support the clinical attempts to establish DCE-MRI as a method for providing biomarkers for tumor aggressiveness and suggests that primary tumors characterized by low K{sup trans} and low v{sub e} values could have a high probability of hypoxia-associated metastatic spread.

Ovrebo, Kirsti Marie; Ellingsen, Christine; Galappathi, Kanthi [Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo (Norway); Rofstad, Einar K., E-mail: einar.k.rofstad@rr-research.no [Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo (Norway)

2012-05-01T23:59:59.000Z

149

Evaluation of multiple dynamic initialization schemes for tropical cyclone prediction  

Science Conference Proceedings (OSTI)

Three different dynamic initialization schemes for tropical cyclone (TC) prediction in numerical prediction systems are described and evaluated. The first scheme involves the removal of the analyzed vortex, followed by insertion of a dynamically-...

Eric A. Hendricks; Melinda S. Peng; Tim Li

150

3D-vortex labyrinths in the near field of solid-state microchip laser  

E-Print Network (OSTI)

The spatiotemporal vortex lattices generated in high Fresnel number solid-state microchip lasers are studied in connection with Talbot phenomenon generic to spatially periodic electromagnetic fields. The spatial layout of light field is obtained via dynamical model based on Maxwell-Bloch equations for class-B laser, discrete Fox-Lee map with relaxation of inversion and static model based on superposition of copropagating Gaussian beams. The spatial patterns observed experimentally and obtained numerically are interpreted as nonlinear superposition of vortices with helicoidal phase dislocations. The usage of vortex labyrinths and Talbot lattices as optical dipole traps for neutral atoms is considered for the wavelength of trapping radiation in the range 0.98 $\\div$ 2.79 $\\mu m$. The separable optical trapping potential is mounted as a sum of array of vortex lines and additional parabolic subtrap. The factorization of macroscopic wavefunction have led to analytical solution of Gross-Pitaevski equation for ground state of ensemble of quantum particles trapped in vortex labyrinth and in spatially - periodic array of Gaussian beams.

A. Yu. Okulov

2007-01-21T23:59:59.000Z

151

Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients  

SciTech Connect

We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

Qamar, Anisa; Ata-ur-Rahman [Institute of Physics and Electronics, University of Peshawar, Khyber Pakhtoon Khwa 25000 (Pakistan); National Center for Physics Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2012-05-15T23:59:59.000Z

152

2884 IEEE TRANSACTIONS ON MAGNETICS, VOL. 41, NO. 10, OCTOBER 2005 Dynamics of the Oil-Air Interface in Hard Disk Drive  

E-Print Network (OSTI)

of a "herringbone" (HB). The HB grooves move relative to the smooth stator and act as a stalled oil pump. When2884 IEEE TRANSACTIONS ON MAGNETICS, VOL. 41, NO. 10, OCTOBER 2005 Dynamics of the Oil of the oil-air interface (OAI) (also called meniscus) of the fluid dynamic bearings of hard disk drives, par

Dellar, Paul J.

153

Dynamic high pressure process for fabricating superconducting and permanent magnetic materials  

DOE Patents (OSTI)

Shock waves directed on thin layers of materials is used to form superconducting and permanent magnetic materials with improved microstructures. 9 figs.

Nellis, W.J.; Maple, M.B.; Geballe, T.H.

1986-12-04T23:59:59.000Z

154

Entanglement of a Quantum Optical Elliptic Vortex  

E-Print Network (OSTI)

We calculate the entanglement of a generalized elliptical vortex formed by quantized radiation field, using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Abir Bandyopadhyay; Shashi Prabhakar; Ravindra Pratap Singh

2010-10-19T23:59:59.000Z

155

Entanglement of Quantum Optical Elliptic Vortex  

E-Print Network (OSTI)

We calculate the entanglement of a generalized elliptical vortex formed by quantized radiation field, using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Bandyopadhyay, Abir; Singh, Ravindra Pratap

2010-01-01T23:59:59.000Z

156

Controlled Vortex Breakdown on Modified Delta Wings  

Science Conference Proceedings (OSTI)

This paper studies the effect of perturbation to the breakdown of the leading-edge vortices over delta wings. The passive perturbation in the normal direction is achieved by installing the hemisphere-like bulges on the delta wing along the projection ... Keywords: Bulge perturbation, Delta wing, Vortex breakdown

S. Srigrarom; N. Lewpiriyawong

2007-08-01T23:59:59.000Z

157

The Tornadic Vortex Signature: An Update  

Science Conference Proceedings (OSTI)

A tornadic vortex signature (TVS) is a degraded Doppler velocity signature of a tornado that occurs when the core region of a tornado is smaller than the half-power beamwidth of the sampling Doppler radar. Soon after the TVS was discovered in the ...

Rodger A. Brown; Vincent T. Wood

2012-04-01T23:59:59.000Z

158

Energy harvesting using vortex-induced vibrations of tensioned cables  

E-Print Network (OSTI)

The development of energy harvesting systems based on fluid/structure interactions is part of the global search for innovative tools to produce renewable energy. In this paper, the possibility to harvest energy from a flow using vortex-induced vibrations (VIV) of a tensioned flexible cable is analyzed. The fluid loading on the vibrating solid and resulting dynamics are computed using an appropriate wake-oscillator model, allowing one to perform a systematic parametric study of the efficiency. The generic case of an elastically-mounted rigid cylinder is first investigated, before considering an infinite cable with two different types of energy harvesting : a uniformly spanwise distributed harvesting and then a periodic distribution of discrete harvesting devices. The maximum harvesting efficiency is of the same order for each configuration and is always reached when the solid body and its wake are in a frequency lock-in state.

Grouthier, Clement; de Langre, Emmanuel

2012-01-01T23:59:59.000Z

159

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

of stoichiometry on vortex flame interactions [31] Pember,Rosalik, M . E . , Combust. Flame, 112(3):342-358 (1998).of stoichiometry on vortex flame interactions [15] Mueller,

Tonse, Shaheen R.

2011-01-01T23:59:59.000Z

160

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

of stoichiometry on vortex flame interactions [31] Pember,Rosalik, M . E . , Combust. Flame, 112(3):342-358 (1998).of stoichiometry on vortex flame interactions [15] Mueller,

Bell, John B.; Brown, Nancy J.; Day, Marcus S.; Frenklach, Michael; Grcar, Joseph F.; Tonse, Shaheen R.

1999-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Contour Dynamics of Tornado-like Vortices  

Science Conference Proceedings (OSTI)

Contour dynamics (CD) is applied to study the mechanism responsible for the breakup of an isolated tornado-like vortex into multiple vortices, the nonlinear interaction between a tornado and its parent storm, and the impact of tornadoes, which ...

Shian-Jiann Lin

1992-09-01T23:59:59.000Z

162

magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

I I Painless Physics Articles BEAM COOLING August 2, 1996 By Leila Belkora, Office of Public Affairs ACCELERATION August 16, 1996 By Dave Finley, Accelerator Division Head RF August 30, 1996 By Pat Colestock, Accelerator Division FIXED TARGET PHYSICS September 20, 1996 By Peter H. Garbincius, Physics Section FIXED TARGET PHYSICS PART DEUX October 16, 1996 By Peter H. Garbincius, Physics Section and Leila Belkora, Office of Public Affaris CROSS SECTION November 1, 1996 By Doreen Wackeroth, Theoretical Physics Edited by Leila Belkora, Office of Public Affaris MAGNETS PART I November 15, 1996 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs MAGNETS PART II January 10, 1997 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs

163

Quantum dynamics and magneto-structural correlations in molecule based magnets  

E-Print Network (OSTI)

the S 4 site symmetry. 3.3.3 Heat Capacity of Ni 4 and Zndisplays polycrystalline heat capacity (C P (T)) data for Ni105 vii Chapter Three Heat Capacity Studies of Magnetic

Beedle, Christopher Craig

2010-01-01T23:59:59.000Z

164

A Vortex Contactor for Carbon Dioxide Separations  

NLE Websites -- All DOE Office Websites (Extended Search)

Vortex Contactor for Carbon Dioxide Separations Vortex Contactor for Carbon Dioxide Separations Kevin T. Raterman (ratekt@inel.gov; 208-526-5444) Michael McKellar (mgq@inel.gov; 208-526-1346) Anna Podgorney (poloak@inel.gov; 208-526-0064) Douglas Stacey (stacde@inel.gov; 208-526-3938) Terry Turner (tdt@inel.gov; 208-526-8623) Idaho National Engineering and Environmental Laboratory P.O. Box 1625 Idaho Falls, Idaho 83415-2110 Brian Stokes (bxs9@pge.com; 415-972-5591) John Vranicar (jjv2@pge.com; 415-972-5591) Pacific Gas & Electric Company 123 Mission Street San Francisco, CA 94105 Introduction Many analysts 1,2,3 identify carbon dioxide (CO 2 ) capture and separation as a major roadblock in efforts to cost effectively mitigate greenhouse gas emissions via sequestration. An assessment 4 conducted by the International Energy Agency (IEA)

165

Vortex formation during rf heating of plasma  

SciTech Connect

Experiments on a test plasma show that the linear theory of waveguide coupling to slow plasma waves begins to break down if the rf power flux exceeds approx. 30 W/cm/sup 2/. Probe measurements reveal that within 30 ..mu..s an undulation appears in the surface plasma near the mouth of the twin waveguide. This surface readjustment is part of a vortex, or off-center convective cell, driven by asymmetric rf heating of the plasma column.

Motley, R.W.

1980-05-01T23:59:59.000Z

166

Vortex flow visualization using tetrahedral cell subdivision  

Science Conference Proceedings (OSTI)

Proposes an effective technique for searching for critical points, which are points at which the velocity vector is zero. The previous method, using tetrahedral-cell subdivision, often generates multiple critical points in a hexahedral cell, and this ... Keywords: Newton's method, critical point searching technique, hexahedral cell, linear interpolation function, multiple critical points, numerical integration scheme, precise position calculation, tetrahedral cell subdivision, trilinear interpolation function, velocity vector, vortex flow visualization, vortices

A. Doi; S. Suzuki; K. Koyamada; S. Sannakanishi

1997-10-01T23:59:59.000Z

167

Dynamic T{sub 2}-mapping during magnetic resonance guided high intensity focused ultrasound ablation of bone marrow  

Science Conference Proceedings (OSTI)

Focal bone tumor treatments include amputation, limb-sparing surgical excision with bone reconstruction, and high-dose external-beam radiation therapy. Magnetic resonance guided high intensity focused ultrasound (MR-HIFU) is an effective non-invasive thermotherapy for palliative management of bone metastases pain. MR thermometry (MRT) measures the proton resonance frequency shift (PRFS) of water molecules and produces accurate (<1 Degree-Sign C) and dynamic (<5s) thermal maps in soft tissues. PRFS-MRT is ineffective in fatty tissues such as yellow bone marrow and, since accurate temperature measurements are required in the bone to ensure adequate thermal dose, MR-HIFU is not indicated for primary bone tumor treatments. Magnetic relaxation times are sensitive to lipid temperature and we hypothesize that bone marrow temperature can be determined accurately by measuring changes in T{sub 2}, since T{sub 2} increases linearly in fat during heating. T{sub 2}-mapping using dual echo times during a dynamic turbo spin-echo pulse sequence enabled rapid measurement of T{sub 2}. Calibration of T{sub 2}-based thermal maps involved heating the marrow in a bovine femur and simultaneously measuring T{sub 2} and temperature with a thermocouple. A positive T{sub 2} temperature dependence in bone marrow of 20 ms/ Degree-Sign C was observed. Dynamic T{sub 2}-mapping should enable accurate temperature monitoring during MR-HIFU treatment of bone marrow and shows promise for improving the safety and reducing the invasiveness of pediatric bone tumor treatments.

Waspe, Adam C.; Looi, Thomas; Mougenot, Charles; Amaral, Joao; Temple, Michael; Sivaloganathan, Siv; Drake, James M. [Centre for Image Guided Innovation and Therapeutic Intervention, The Hospital for Sick Children, Toronto, ON, M5G 1X8 (Canada); Philips Healthcare Canada, Markham, ON, L6C 2S3 (Canada); Centre for Image Guided Innovation and Therapeutic Intervention, The Hospital for Sick Children, Toronto, ON, M5G 1X8 (Canada); Department of Applied Mathematics, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada); Centre for Image Guided Innovation and Therapeutic Intervention, The Hospital for Sick Children, Toronto, ON, M5G 1X8 (Canada)

2012-11-28T23:59:59.000Z

168

Effect of NO on extinction and re-ignition of vortex-perturbed hydrogen flames.  

DOE Green Energy (OSTI)

The catalytic effect of nitric oxide (NO) on the dynamics of extinction and re-ignition of a vortex-perturbed non-premixed hydrogen-air flame is studied in a counterflow burner. A diffusion flame is established with counterflowing streams of nitrogen-diluted hydrogen at ambient temperature and air heated to a range of temperatures that brackets the auto-ignition temperature. Localized extinction is induced by impulsively driving a fuel-side toroidal vortex into the steady flame, and the recovery of the extinguished region is monitored by planar laser-induced fluorescence (PLIF) of the hydroxyl radical (OH). The dynamics of flame recovery depend on the air temperature and fuel concentration, and four different recovery modes are identified. These modes involve combinations of edge-flame propagation and the expansion of an auto-ignition kernel that forms within the extinguished region. The addition of a small amount of NO significantly alters the re-ignition process by shifting the balance between chain-termination and chain-propagation reactions to enhance auto-ignition. The ignition enhancement by this catalytic effect causes a shift in the conditions that govern the recovery modes. In addition, the effects of NO concentration and vortex strength on the flame recovery are examined. Direct numerical simulations of the flame-vortex interaction with and without NO doping show how the small amount of OH produced by NO-catalyzed reactions has a significant impact on the development of an auto-ignition kernel. This joint experimental and numerical study provides detailed insight into the interaction between transient flows and ignition processes.

Yoo, Chun Sang; Chen, Jacqueline H.; Frank, Jonathan H.; Lee, Uen Do (KITECH, Cheonan, Chungnam, South Korea)

2009-01-01T23:59:59.000Z

169

Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects  

SciTech Connect

Topics covered are: anomalous transport and E Ã? B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.

Alexei Y. Pankin; Arnold H. Kritz

2011-07-19T23:59:59.000Z

170

Nanoscale strain-induced pair suppression as a vortex-pinning mechanism in high- temperature superconductors  

SciTech Connect

Boosting large-scale superconductor applications require nanostructured conductors with artificial pinning centres immobilizing quantized vortices at high temperature and magnetic fields. Here we demonstrate a highly effective mechanism of artificial pinning centers in solution-derived high-temperature superconductor nanocomposites through generation of nanostrained regions where Cooper pair formation is suppressed. The nanostrained regions identified from transmission electron microscopy devise a very high concentration of partial dislocations associated with intergrowths generated between the randomly oriented nanodots and the epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} matrix. Consequently, an outstanding vortex-pinning enhancement correlated to the nanostrain is demonstrated for four types of randomly oriented nanodot, and a unique evolution towards an isotropic vortex-pinning behaviour, even in the effective anisotropy, is achieved as the nanostrain turns isotropic. We suggest a new vortex-pinning mechanism based on the bond-contraction pairing model, where pair formation is quenched under tensile strain, forming new and effective core-pinning regions.

Llordes, Anna [ICMAB, Barcelona, Spain; Palau, A. [ICMAB, Barcelona, Spain; Gazquez, J. [Oak Ridge National Laboratory (ORNL); Coll, M. [ICMAB, Barcelona, Spain; Vlad, R. [ICMAB, Barcelona, Spain; Pomar, A. [ICMAB, Barcelona, Spain; Arbiol, Jordi [ICMAB, Barcelona, Spain; Guzman, Roger [ICMAB, Barcelona, Spain; Ye, S. [ICMAB, Barcelona, Spain; Rouco, V [ICMAB, Barcelona, Spain; Sandiumenge, Felip [ICMAB, Barcelona, Spain; Ricart, Susagna [ICMAB, Barcelona, Spain; Puig, Teresa [ICMAB, Barcelona, Spain; Varela del Arco, Maria [ORNL; Chataigner, D. [CRISMAT, Caen, France; Vanacken, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Gutierrez, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Moschalkov, V. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Deutscher, G. [Tel Aviv University; Magen Dominguez, Cesar [ORNL; Obradors, Xavier [ICMAB, Barcelona, Spain

2012-01-01T23:59:59.000Z

171

Dynamic high pressure process for fabricating superconducting and permanent magnetic materials  

DOE Patents (OSTI)

Shock wave formation of thin layers of materials with improved superconducting and permanent magnetic properties and improved microstructures is disclosed. The material fabrication system includes a sandwiched structure including a powder material placed between two solid members to enable explosive shock consolidation. The two solid members are precooled to about 80--100 K to reduce the residual temperatures attained as a result of the shock wave treatment, and thereby increase the quench rate of the consolidated powder. 9 figs.

Nellis, W.J.; Geballe, T.H.; Maple, M.B.

1990-03-13T23:59:59.000Z

172

Dynamic high pressure process for fabricating superconducting and permanent magnetic materials  

DOE Patents (OSTI)

Shock wave formation of thin layers of materials with improved superconducting and permanent magnetic properties and improved microstructures. The material fabrication system includes a sandwiched structure including a powder material placed between two solid members to enable explosive shock consolidation. The two solid members are precooled to about 80.degree.-100.degree. K. to reduce the residual temperatures attained as a result of the shock wave treatment, and thereby increase the quench rate of the consolidated powder.

Nellis, William J. (Berkeley, CA); Geballe, Theodore H. (Woodside, CA); Maple, M. Brian (Del Mar, CA)

1990-01-01T23:59:59.000Z

173

Exact analysis of particle dynamics in combined field of finite duration laser pulse and static axial magnetic field  

Science Conference Proceedings (OSTI)

Dynamics of a charged particle is studied in the field of a relativistically intense linearly polarized finite duration laser pulse in the presence of a static axial magnetic field. For a finite duration laser pulse whose temporal shape is defined by Gaussian profile, exact analytical expressions are derived for the particle trajectory, momentum, and energy as function of laser phase. From the solutions, it is shown that, unlike for the monochromatic plane wave case, resonant phase locking time between the particle and laser pulse is finite. The net energy transferred to the particle does not increase monotonically but tends to saturate. It is further shown that appropriate tuning of cyclotron frequency of the particle with the characteristic frequency in the pulse spectrum can lead to the generation of accelerated particles with variable energies in MeV-TeV range.

Sagar, Vikram; Sengupta, Sudip; Kaw, Predhiman [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2012-11-15T23:59:59.000Z

174

Gauge turbulence, topological defect dynamics, and condensation in Higgs models  

E-Print Network (OSTI)

The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appear in the gauge field which are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixed point of the far-from-equilibrium dynamical evolution, signalled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang-Mills fields and potential mechanisms how confinement and condensation in non-abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.

Thomas Gasenzer; Larry McLerran; Jan M. Pawlowski; Dénes Sexty

2013-07-19T23:59:59.000Z

175

Helicoidal vortex model for wind turbine aeroelastic simulation  

Science Conference Proceedings (OSTI)

The vortex method has been extended to account for blade flexibility, which is a potential source of unsteadiness in the flow past a wind turbine rotor. The code has been validated previously under the assumption of rigid blades. The aerodynamics method ... Keywords: Blade flexibility, Steady and unsteady flows, Tower interference, Vortex model

Jean-Jacques Chattot

2007-06-01T23:59:59.000Z

176

Finned Tube With Vortex Generators For A Heat Exchanger.  

DOE Patents (OSTI)

A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at least one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

Sohal, Monohar S. (Idaho Falls, ID); O' Brien, James E. (Idaho Falls, ID)

2004-09-14T23:59:59.000Z

177

Finned Tube With Vortex Generators For A Heat Exchanger.  

DOE Patents (OSTI)

A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

Sohal, Manohar S. (Idaho Falls, ID); O' Brien, James E. (Idaho Falls, ID)

2005-12-20T23:59:59.000Z

178

An Investigation of a Three-Dimensional Asymmetric Vortex  

Science Conference Proceedings (OSTI)

A three-dimensional numerical simulation is presented for the asymmetric vortex motion which occurs in a Ward-type vortex chamber. The initial state is taken to be one of axisymmetric irrotational flow where the flow enters through the sides at ...

Richard Rotunno

1984-01-01T23:59:59.000Z

179

Gravity waves from vortex dipoles and jets  

E-Print Network (OSTI)

The dissertation first investigates gravity wave generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model. Several initially balanced and localized jets induced by vortex dipoles are examined here. Within these dipoles, inertia-gravity waves with intrinsic frequencies 1-2 times the Coriolis parameter are simulated in the jet exit region. The ray tracing analysis reveals strong variation of wave characteristics along ray paths. The dependence of wave amplitude on the Rossby number is examined through experiments in which the two vortices are initially separated by a large distance but subsequently approach each other and form a vortex dipole with an associated amplifying localized jet. The amplitude of stationary gravity waves in the simulations with a 90-km grid spacing increases nearly linearly with the square of the Rossby number but significantly more rapidly when smaller grid spacing is used. To further address the source mechanism of the gravity waves within the vortex dipole, a linear numerical framework is developed based on the framework proposed by Plougonven and Zhang (2007). Using the nonlinearly balanced fields as the basic state and driven by three types of large scale forcing, the vorticity, divergence and thermodynamic forcing, this linear model is utilized to obtain linear wave responses. The wave packets in the linear responses compare reasonably well with the MM5 simulated gravity waves. It is suggested that the vorticity forcing is the leading contribution to both gravity waves in the jet exit region and the ascent/descent feature in the jet core. This linear model is also adopted to study inertia-gravity waves in the vicinity of a baroclinic jet during the life cycle of an idealized baroclinic wave. It is found that the thermodynamic forcing and the vorticity forcing are equally important to the gravity waves in the low stratosphere, but the divergence forcing is again playing a lesser role. Two groups of wave packets are present in the linear responses; their sources appear to locate either near the surface front or near the middle/upper tropospheric jet.

Wang, Shuguang

2008-08-01T23:59:59.000Z

180

Stability of an optical vortex in a circular nematic cell  

SciTech Connect

The stability of an optical vortex in a cell with a circular cross section containing a nematic liquid crystal is studied. A modulation theory based on an averaged Lagrangian formulation is developed to study this stability. It is found that the vortex is stable unless the radius of the cell is very small, nearly the width of the vortex itself. Based on the analysis of a stationary vortex, the stability of a low-amplitude vortex in a large cell under the influence of its orbital angular momentum and the repelling effect of the cell boundary are studied. The predictions of this modulation theory are found to be in excellent agreement with numerical simulations.

Minzoni, Antonmaria A. [Fenomenos Nonlineales y Mecanica (FENOMEC), Departamento de Matematicas y Mecanica, Instituto de Investigacion en Matematicas Aplicadas y Sistemas, Universidad Nacional Autonoma de Mexico, 01000 Mexico D.F. (Mexico); Smyth, Noel F. [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Xu Zhiyong [Nonlinear Physics Center, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2010-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics  

Science Conference Proceedings (OSTI)

In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the ase of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors.

Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V.; /Fermilab

2012-05-01T23:59:59.000Z

182

Nuclear Magnetic Resonance Investigation of Dynamics in Poly(Ethylene Oxide) Based Lithium Polyether-ester-sulfonate Ionomers  

SciTech Connect

Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies of both the polymer and lithium ions in the lower ion content samples indicate that the polymer segmental motion and lithium ion hopping motion are correlated even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample due to the presence of ionic aggregation. Details about the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.

Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

2012-01-07T23:59:59.000Z

183

Tornadogenesis with and without a Dynamic Pipe Effect  

Science Conference Proceedings (OSTI)

A dynamic pipe effect (DPE) has been used previously to explain the descent from aloft of tornadic vortex signatures (TVSs), and presumably embryonic tornadoes, prior to the near-ground spinup of the tornado. But for many tornadoes the TVS ...

R. Jeffrey Trapp; Robert Davies-Jones

1997-01-01T23:59:59.000Z

184

MHK Technologies/Vortex Induced Vibrations Aquatic Clean Energy VIVACE |  

Open Energy Info (EERE)

Vortex Induced Vibrations Aquatic Clean Energy VIVACE Vortex Induced Vibrations Aquatic Clean Energy VIVACE < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage Vortex Induced Vibrations Aquatic Clean Energy VIVACE.jpg Technology Profile Primary Organization Vortex Hydro Energy LLC Project(s) where this technology is utilized *MHK Projects/Marine Hydrodynamics Laboratory at the University of Michigan Technology Resource Click here Current/Tidal Technology Type Click here Reciprocating Device Technology Readiness Level Click here TRL 4: Proof of Concept Technology Description The VIVACE (Vortex Induced Vibrations Aquatic Clean Energy) device is based on the extensively studied phenomenon of Vortex Induced Vibrations (VIV), which was first observed five-hundred years ago by Leonardo DaVinci in the form of 'Aeolian Tones.' VIV results from vortices forming and shedding on the downstream side of a bluff body in a current. Vortex shedding alternates from one side to the other, thereby creating a vibration or oscillation. The VIV phenomenon is non-linear, which means it can produce useful energy at high efficiency over a wide range of current speeds and directions.This converter is unlike any existing technology, as it does not use turbines, propellers, or dams. VIVACE converts the horizontal hydrokinetic energy of currents into cylinder mechanical energy. The latter is then converted to electricity through electric power generators.

185

Ferroelectric nanostructure having switchable multi-stable vortex states  

DOE Patents (OSTI)

A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

Naumov, Ivan I. (Fayetteville, AR); Bellaiche, Laurent M. (Fayetteville, AR); Prosandeev, Sergey A. (Fayetteville, AR); Ponomareva, Inna V. (Fayetteville, AR); Kornev, Igor A. (Fayetteville, AR)

2009-09-22T23:59:59.000Z

186

Magnetic turbulence suppression by a helical mode in a cylindrical geometry  

Science Conference Proceedings (OSTI)

To study processes involved in a helical structure formation in reversed field pinch devices, the scaling of a turbulent boundary layer width associated with a vortex structure having large shears of magnetic field and flow is obtained for reduced magnetohydrodynamics. The coherent vortex, with its flow and magnetic shears, interacts with Alfven turbulence, forming a turbulent boundary layer at the edge of the vortex. The layer arises from the balance between turbulence diffusion rates and shearing rates and suppresses the turbulence in the structure. The suppression of turbulence impedes relaxation of the coherent vortex profiles, leading to long coherence times. The scaling of the boundary layer width reveals that both magnetic shear and flow shear can effectively suppress magnetic turbulence.

Kim, J.-H.; Terry, P. W. [Department of Physics and Center for Momentum Transport and Flow Organization, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2012-12-15T23:59:59.000Z

187

Dynamic  

Office of Legacy Management (LM)

Dynamic Dynamic , and Static , Res.ponse of the Government Oil Shale Mine at ' , . , Rifle, Colorado, to the Rulison Event. , . ; . . DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. p ( y c - - a 2-1 0 -4- REPORT AT (29-2) 914 USBM 1 0 0 1 UNITED STATES DEPARTMENT O F THE I NTERIOR BUREAU OF MINES e s.09 P. L. R U S S E L L RESEARCH D l RECTOR Februory 2, lB7O DYNAMIC AND STATIC RESPONSE 'OF THE GOVERNMENT OIL SHALE MINE A T RIFLE, COLORADO, T O THE, RULISON EVENT ORDER FROM CFSTl A S ~ B ~ &J C / This page intentionally left blank CONTENTS Page . . . . . . . . . . . . . . . . . . . . . . . . . H i s t o r i c . a l Des c r i p t i o n 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 3

188

Vortex flow around the bases of obstacles  

E-Print Network (OSTI)

.2 The horseshoe . vortex formed by a separating turbulent boundary layer 5.3 Scour around obstacles in an erodible bed 114 116 117 . ·4 References Uf'l() I:!~oLtlecl F,'obL.efl):' Llr:cl ~u.g5el:dto/J~ fer ju.iLt(t' wc"..,I" 11 2 119 Figures (vi... , are shmm in figUre 2.3.4. It can be seen that there is a rather high le,el of turbulence in the tunnel free stream. This is poss:l.bly due to the extra screens placed upstream of the \\'lorking section. At the higher speeds used this turbulence...

Baker, Christopher James

1979-02-06T23:59:59.000Z

189

The multiple vortex nature of tropical cyclogenesis  

E-Print Network (OSTI)

This thesis contains an observational analysis of the genesis of Tropical Storm Allison (2001). Using a paradigm of tropical cyclone formation as the superposition of potential vorticity (PV) anomalies, the importance of different scales of PV merger to various aspects of Allison?s formation is discussed. While only the case of Allison is discussed in great detail, other studies have also documented PV superposition on various scales, and superposition could be important for most tropical cyclones. Preceding Allison?s genesis, PV superposition on the large scale destabilized the atmosphere and increased low-level cyclonic vorticity. This presented a more favorable environment for the formation of MCV-type PV anomalies and smaller, surface-based, meso-?-scale vortices. Although these vortices eventually merged to form a more concentrated vortex with stronger surface pressure gradients, the merger happened well after landfall of Allison and no strengthening ensued. The unstable, vorticity-rich environment was also favorable for the development of even smaller, meso-?-scale vortices that accompanied deep convective cells within one of Allison?s meso-?-scale vortices. The observations herein suggest that the meso-?- scale convective cells and vortices are the respective source of PV production and building blocks for the meso-?-scale vortices. Finally, this thesis discusses issues related to the multiple vortex nature of tropical cyclone formation. For instance, the tracking of developing tropical cyclones is greatly complicated by the presence of multiple vortices. For these cases, the paradigm of a single cyclone center is inappropriate and alternative tracking methods are introduced.

Sippel, Jason Allen

2004-12-01T23:59:59.000Z

190

MHK Technologies/SeaUrchin Vortex Reaction Turbine | Open Energy  

Open Energy Info (EERE)

SeaUrchin Vortex Reaction Turbine SeaUrchin Vortex Reaction Turbine < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage SeaUrchin Vortex Reaction Turbine.jpg Technology Profile Primary Organization Elemental Energy Technologies Limited ABN 46 128 491 903 Technology Resource Click here Current Technology Type Click here Axial Flow Turbine Technology Readiness Level Click here TRL 4 Proof of Concept Technology Description A revolutionary vortex reaction turbine branded the SeaUrchin an advanced third generation marine turbine technology capable of delivering inexpensive small to large scale baseload or predictable electricity by harnessing the kinetic energy of free flowing ocean currents tides and rivers Technology Dimensions Device Testing Date Submitted 55:15.2

191

Baroclinic Transition of a Long-Lived Mesoscale Convective Vortex  

Science Conference Proceedings (OSTI)

The period 5–15 June 2003, during the field phase of the Bow Echo and Mesoscale Convective Vortex (MCV) Experiment (BAMEX), was noteworthy for the wide variety of mesoscale convective systems (MCSs) that occurred. Of particular interest was a ...

Thomas J. Galarneau Jr.; Lance F. Bosart; Christopher A. Davis; Ron McTaggart-Cowan

2009-02-01T23:59:59.000Z

192

Reexamining the Vertical Development of Tornadic Vortex Signatures in Supercells  

Science Conference Proceedings (OSTI)

Observations from a hybrid phased-array Doppler radar, the Mobile Weather Radar, 2005 X-band, Phased-Array (MWR-05XP), were used to investigate the vertical development of tornadic vortex signatures (TVSs) during supercell tornadogenesis. Data ...

Michael M. French; Howard B. Bluestein; Ivan PopStefanija; Chad A. Baldi; Robert T. Bluth

193

Inertia–Gravity Waves Generated within a Dipole Vortex  

Science Conference Proceedings (OSTI)

Vortex dipoles provide a simple representation of localized atmospheric jets. Numerical simulations of a synoptic-scale dipole in surface potential temperature are considered in a rotating, stratified fluid with approximately uniform potential ...

Chris Snyder; David J. Muraki; Riwal Plougonven; Fuqing Zhang

2007-12-01T23:59:59.000Z

194

Ozone Chemistry during the 2002 Antarctic Vortex Split  

Science Conference Proceedings (OSTI)

In September 2002, the Antarctic polar vortex was disturbed, and it split into two parts caused by an unusually early stratospheric major warming. This study discusses the chemical consequences of this event using the Chemical Lagrangian Model of ...

Jens-Uwe Grooß; Paul Konopka; Rolf Müller

2005-03-01T23:59:59.000Z

195

Assimilating Vortex Position with an Ensemble Kalman Filter  

Science Conference Proceedings (OSTI)

Observations of hurricane position, which in practice might be available from satellite or radar imagery, can be easily assimilated with an ensemble Kalman filter (EnKF) given an operator that computes the position of the vortex in the background ...

Yongsheng Chen; Chris Snyder

2007-05-01T23:59:59.000Z

196

Spontaneous Imbalance and Hybrid Vortex–Gravity Structures  

Science Conference Proceedings (OSTI)

After reviewing the background, this article discusses the recently discovered examples of hybrid propagating structures consisting of vortex dipoles and comoving gravity waves undergoing wave capture. It is shown how these examples fall outside ...

Michael E. McIntyre

2009-05-01T23:59:59.000Z

197

Some Aspects of Vortex Structure Related to Tropical Cyclone Motion  

Science Conference Proceedings (OSTI)

Some effect of tropical cyclone structure on the vortex motion are examined in a nondivergent, barotropic numerical model with no basic current. As suggested earlier by DeMaria, the initial maximum wind speed has little effect on the track. ...

Michael Fiorino; Russell L. Elsberry

1989-04-01T23:59:59.000Z

198

Closed cycle steam turbine system with liquid vortex pump  

SciTech Connect

A closed cycle steam generating system is described comprising a steam boiler, and a steam turbine includes a vacuum pump of the liquid vortex type for condensing the exhaust steam from the turbine, a feedwater pump being employed for returning the condensate to the boiler. The tank of the vortex pump is maintained filled with water and the pressure in the tank is regulated automatically to maintain a predetermined value thereof.

Brown, K.D.

1976-08-10T23:59:59.000Z

199

Nonclassicality of vortex Airy beams in the Wigner representation  

Science Conference Proceedings (OSTI)

The Wigner distribution function (WDF) of a vortex Airy beam is calculated analytically. The WDF provides intuitive pictures of the intriguing features of vorticity in phase space. The nonclassical property of the vortex Airy beam and the Airy beam is analyzed through the negative parts of the WDF. The study shows that destructive interference of certain classical waves can mimic nonclassical lights such as those due to quantum effects.

Chen Ruipin [School of Sciences, Zhejiang A and F University, Lin'an, Zhejiang Province 311300 (China); Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ooi, C. H. Raymond [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2011-10-15T23:59:59.000Z

200

Depinning of a superfluid vortex line by Kelvin waves  

E-Print Network (OSTI)

We measure the interaction of a single superfluid vortex with surface irregularities. While vortex pinning in superconductors usually becomes weaker at higher temperatures, we find the opposite behavior. The pinning steadily increases throughout our measurement range, from 0.15Tc to over 0.5Tc. We also find that moving the other end of the vortex decreases the pinning, so we propose Kelvin waves along the vortex as a depinning mechanism. PACS numbers: 67.40.Vs, 74.60.Ge Pinning sites can trap vortices in a variety of systems. In superconductors, where vortex motion leads to nonzero resistance, a vast amount of work has been devoted to preventing such motion by introducing defects. Experimental work has shown that defects comparable in size to the vortex core make effective pin centers, and that straight [1] or splayed [2] line defects can increase the pin strength. Yet the mechanisms by which vortices interact with pin sites remain unresolved. Experimentally, pinning in superconductors becomes weaker as

L. A. K. Donev; L. Hough; R. J. Zieve

2001-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydration Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics Simulation E. Mamontov,* ,† D. J. Wesolowski, ‡ L. Vlcek, § P. T. Cummings, §,| J. Rosenqvist, ‡ W. Wang, ⊥ and D. R. Cole ‡ Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6473, Chemical Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110, Department of Chemical Engineering, Vanderbilt UniVersity, NashVille, Tennessee 37235-1604, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6496, and EnVironmental Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6036 ReceiVed: December 20, 2007; ReVised Manuscript ReceiVed: June 4, 2008 The high energy resolution, coupled with the wide dynamic range, of the new backscattering

202

Quantitative Determination of Chemical Processes by Dynamic Nuclear Polarization Enhanced Nuclear Magnetic Resonance Spectroscopy  

E-Print Network (OSTI)

Dissolution dynamic nuclear polarization (DNP) provides several orders of magnitude of NMR signal enhancement by converting the much larger electron spin polarization to nuclear spin polarization. Polarization occurs at low temperature (1.4K) and is followed by quickly dissolving the sample for room temperature NMR detection. DNP is generally applicable to almost any small molecules and can polarize various nuclei including 1H, 19F and 13C. The large signal from DNP enhancement reduces the limit of detection to micromolar or sub-micromolar concentration in a single scan. Since DNP enhancement often provides the only source for the observable signal, it enables tracking of the polarization flow. Therefore, DNP is ideal for studying chemical processes. Here, quantitative tools are developed to separate kinetics and spin relaxation, as well as to obtain structural information from these measurements. Techniques needed for analyzing DNP polarized sample are different from those used in conventional NMR because a large, yet non-renewable hyperpolarization is available. Using small flip angle pulse excitation, the hyperpolarization can still be divided into multiple scans. Based on this principle, a scheme is presented that allows reconstruction of indirect spectral dimensions similarly to conventional 2D NMR. Additionally, small flip angle pulses can be used to obtain a succession of scans separated in time. A model describing the combined effects of the evolution of a chemical process and of spin-lattice relaxation is shown. Applied to a Diels-Alder reaction, it permitted measuring kinetics along with the effects of auto- and cross-relaxation. DNP polarization of small molecules also shows significant promise for studying protein-ligand interaction. The binding of fluorinated ligands to the protease trypsin was studied through the observation of various NMR parameter changes, such as line width, signal intensity and chemical shift of the ligands. Intermolecular polarization transfer from hyperpolarized ligand to protein can further provide information about the binding pocket of the protein. As an alternative to direct observation of protein signal, a model is presented to describe a two-step intermolecular polarization transfer between competitively binding ligands mediated through the common binding pocket of the protein. The solutions of this model relate the evolution of signal intensities to the intermolecular cross relaxation rates, which depend on individual distances in the binding epitope. In summary, DNP provides incomparable sensitivity, speed and selectivity to NMR. Quantitative models such as those discussed here enable taking full advantage of these benefits for the study of chemical processes.

Zeng, Haifeng

2012-05-01T23:59:59.000Z

203

Systems and methods for creation of conducting networks of magnetic particles through dynamic self-assembly process  

DOE Patents (OSTI)

Self-assembly of magnetic microparticles in AC magnetic fields. Excitation of the system by an AC magnetic field provides a variety of patterns that can be controlled by adjusting the frequency and the amplitude of the field. At low particle densities the low-frequency magnetic excitation favors cluster phase formation, while high frequency excitation favors chains and netlike structures. For denser configurations, an abrupt transition to the network phase was obtained.

Snezhko, Oleksiy (Woodridge, IL); Aronson, Igor (Darien, IL); Kwok, Wai-Kwong (Downers Grove, IL)

2011-01-25T23:59:59.000Z

204

Scaling analysis and application: Phase diagram of magnetic nanorings and elliptical nanoparticles  

Science Conference Proceedings (OSTI)

The magnetic properties of single-domain nanoparticles with different geometric shapes, crystalline anisotropies, and lattice structures are investigated. A recently proposed scaling approach is shown to be universal and in agreement with dimensional analysis coupled with the assumption of incomplete self-similarity. It is used to obtain phase diagrams of magnetic nanoparticles featuring three competing configurations: in-plane ferromagnetism, out-of-plane ferromagnetism, and vortex formation. The influence of the vortex core on the scaling behavior and phase diagram is analyzed. Three-dimensional phase diagrams are obtained for cylindrical nanorings depending on their height and outer and inner radii. The triple points in these phase diagrams are shown to be in a linear relationship with the inner radius of the ring. Elliptically shaped magnetic nanoparticles are also studied. A new parametrization for double vortex configurations is proposed, and regions in the phase diagram where the double vortex is a stable ground state are identified.

Zhang Wen; Singh, Rohit; Bray-Ali, Noah; Haas, Stephan [Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089 (United States)

2008-04-01T23:59:59.000Z

205

Nanoscale strain-induced pair suppression as a source of vortex pinning in high-temperature superconductors  

SciTech Connect

Boosting large-scale superconductor applications require nanostructured conductors with artificial pinning centres immobilizing quantized vortices at high temperature and magnetic fields. Here we demonstrate a highly effective mechanism of artificial pinning centres in solution-derived high-temperature superconductor nanocomposites through generation of nanostrained regions where Cooper pair formation is suppressed. The nanostrained regions identified from transmission electron microscopy devise a very high concentration of partial dislocations associated with intergrowths generated between the randomly oriented nanodots and the epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} matrix. Consequently, an outstanding vortex-pinning enhancement correlated to the nanostrain is demonstrated for four types of randomly oriented nanodot, and a unique evolution towards an isotropic vortex-pinning behaviour, even in the effective anisotropy, is achieved as the nanostrain turns isotropic. We suggest a new vortex-pinning mechanism based on the bond-contraction pairing model, where pair formation is quenched under tensile strain, forming new and effective core-pinning regions.

Llordes, A. [ICMAB, Barcelona, Spain; Palau, A. [ICMAB, Barcelona, Spain; Vlad, R. [ICMAB, Barcelona, Spain; Pomar, A. [ICMAB, Barcelona, Spain; Arbiol, Jordi [ICMAB, Barcelona, Spain; Guzman, Roger [ICMAB, Barcelona, Spain; Gazquez Alabart, Jaume [ORNL; Varela del Arco, Maria [ORNL; Sandiumenge, Felip [ICMAB, Barcelona, Spain; Ricart, Susagna [ICMAB, Barcelona, Spain; Puig, Teresa [ICMAB, Barcelona, Spain; Chataigner, D. [CRISMAT, Caen, France; Vanacken, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Gutierrez, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Deutscher, G. [Tel Aviv University; Moschalkov, V. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Obradors, Xavier [ICMAB, Barcelona, Spain

2012-01-01T23:59:59.000Z

206

Barotropic Simulation of Large-Scale Mixing in the Antarctic Polar Vortex  

Science Conference Proceedings (OSTI)

Theory and observations suggest that the Antarctic polar vortex is relatively isolated from midlatitudes, although others have interpreted the observations to indicate that there is substantial mixing from the interior of the vortex into middle ...

Kenneth P. Bowman

1993-09-01T23:59:59.000Z

207

Generation and Propagation of Inertia–Gravity Waves from Vortex Dipoles and Jets  

Science Conference Proceedings (OSTI)

This study investigates gravity wave generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model. Two types of initially balanced and localized jets induced by vortex dipoles are examined here. ...

Shuguang Wang; Fuqing Zhang; Chris Snyder

2009-05-01T23:59:59.000Z

208

Influence of a Strong Bottom Slope on the Evolution of a Surface-Intensified Vortex  

Science Conference Proceedings (OSTI)

The authors investigate the influence of steep bottom topography on the propagation of a vortex in a two-layer quasigeostrophic model. The vortex is intensified in the upper layer and the planetary beta effect is taken into account.

Virginie Thierry; Yves Morel

1999-05-01T23:59:59.000Z

209

St-Onge, G., and J.S. Stoner. 2011. Paleomagnetism near the North Magnetic Pole: A unique vantage point for understanding the dynamics of the geomagnetic field and its secular  

E-Print Network (OSTI)

vantage point for understanding the dynamics of the geomagnetic field and its secular variationsOmagNeTiSm Near The NOrTh magNeTiC pOle a unique Vantage point for understanding the Dynamics of the geomagnetic Field and its Secular Variations abSTraCT. Along with the dramatic decrease in global geomagnetic field

210

Combining the vortex-in-cell and parallel fast multipole methods for efficient domain decomposition simulations  

Science Conference Proceedings (OSTI)

A new combination of vortex-in-cell and parallel fast multipole methods is presented which allows to efficiently simulate, in parallel, unbounded and half-unbounded vortical flows (flows with one flat wall). In the classical vortex-in-cell (VIC) method, ... Keywords: Incompressible flows, Lagrangian methods, Parallel fast multipole method, Particle methods, Unbounded flows, Unsteady flows, Vortex methods, Vortex-in-cell method, Wall-bounded flows

Roger Cocle; Grégoire Winckelmans; Goéric Daeninck

2008-02-01T23:59:59.000Z

211

Simulations of Dynamics and Transport during the September 2002 Antarctic Major Warming  

Science Conference Proceedings (OSTI)

A mechanistic model simulation initialized on 14 September 2002, forced by 100-hPa geopotential heights from Met Office analyses, reproduced the dynamical features of the 2002 Antarctic major warming. The vortex split on 25 September; recovery ...

Gloria L. Manney; Joseph L. Sabutis; Douglas R. Allen; William A. Lahoz; Adam A. Scaife; Cora E. Randall; Steven Pawson; Barbara Naujokat; Richard Swinbank

2005-03-01T23:59:59.000Z

212

The Data Vortex, an All Optical Path Multicomputer Interconnection Network  

E-Print Network (OSTI)

All optical path interconnection networks employing dense wavelength division multiplexing can provide vast improvements in supercomputer performance. However, the lack of efficient optical buffering requires investigation of new topologies and routing techniques. This paper introduces and evaluates the Data Vortex optical switching architecture which uses cylindrical routing paths as a packet buffering alternative. In addition, the impact of the number of angles on the overall network performance is studied through simulation. Using optimal topology configurations, the Data Vortex is compared to two existing switching architectures—butterfly and omega networks. The three networks are compared in terms of throughput, accepted traffic ratio, and average packet latency. The Data Vortex is shown to exhibit comparable latency and a higher acceptance rate (2x at 50 percent load) than the butterfly and omega topologies.

Cory Hawkins; Benjamin A. Small; D. Scott Wills; Keren Bergman

2007-01-01T23:59:59.000Z

213

Low Head, Vortex Induced Vibrations River Energy Converter  

DOE Green Energy (OSTI)

Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing and utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.

Bernitsas, Michael B.; Dritz, Tad

2006-06-30T23:59:59.000Z

214

Shock-compressible-vortex interactions: Computing approximate post-shock fields  

E-Print Network (OSTI)

Shock-compressible-vortex interactions: Computing approximate post-shock fields G.K. O'Reilly and D of the passage of a planar shock through a steady compressible vortex is developed. To compute the approximate post-shock fields, the steady pre-shock vortex is decomposed into a sum of frozen sinusoidal modes

Barr, Al

215

Non-Contact Haptic Feedback Using Air Vortex Rings Sidhant Gupta1,2  

E-Print Network (OSTI)

regions of the human body. Author Keywords Non-contact haptic feedback; air vortex rings ACM1 AirWave: Non-Contact Haptic Feedback Using Air Vortex Rings Sidhant Gupta1,2 , Dan Morris1 feedback into such interaction. In this work, we explore the use of air vortex rings for this purpose

Rajamani, Sriram K.

216

Berry's Phase, Josephson's Equation, and the Dynamics of Weak Link Superconductors and Their Vortices  

E-Print Network (OSTI)

We examine the dynamical consequences of Berry's phase for Josephson junctions, junction arrays, and their vortices. Josephson's equation and the related phase slip voltages are shown to be uneffected by Berry's phase. In an annular Josephson junction, Berry's phase is seen to generate a new current drive on a vortex. In the continuum limit, vortex dynamics in a 2D array is shown to map onto that of a 2D film. A Hall sign anomaly is expected in arrays; and the merits of arrays for studies of disorder on vortex motion is discussed.

Frank Gaitan; Subodh R. Shenoy

1995-05-19T23:59:59.000Z

217

Wigner function and entanglement of generalized quantum optical vortex  

E-Print Network (OSTI)

We calculate the Wigner quasiprobability distribution function of the quantum elliptical vortex (QEV), produced by coupling squeezed coherent states of two modes . The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to the coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. We calculate the entanglement of such generalized elliptical vortex formed by quantized radiation field (QEV), using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Bandyopadhyay, Abir; Singh, R P

2011-01-01T23:59:59.000Z

218

Propagation of an arbitrary vortex pair through an astigmatic optical system and determination of its net topological charge  

E-Print Network (OSTI)

We embed a pair of vortices with different topological charges in a Gaussian beam and study its evolution through an astigmatic optical system, a tilted lens. The propagation dynamics is explained by a closed-form analytical expression. Furthermore, we show that a careful examination of the intensity distribution at a predicted position past the lens can provide us with the net charge present in the beam. To the best of our knowledge, our method is the first non-interferometric technique to measure the net charge of an arbitrary vortex pair. Our experimental results are in close agreement with the theoretical predictions.

Reddy, Salla Gangi; Aadhi, A; Banerji, J; Singh, R P

2013-01-01T23:59:59.000Z

219

On the Onset Vortex of the Summer Monsoon  

Science Conference Proceedings (OSTI)

In this paper we examine the evolution of the low-level flow over the Arabian Sea during the onset of the summer monsoon. A detailed examination of the onset vortex that forms over the Arabian Sea just prior to the commencement of heavy rains ...

T. N. Krishnamurti; Philip Ardanuy; Y. Ramanathan; Richard Pasch

1981-02-01T23:59:59.000Z

220

Blade-Vortex Interactions in High Pressure Steam Turbines  

E-Print Network (OSTI)

A detailed experimental and numerical investigation of the transport of streamwise (passage) vortices in high-pressure axial turbines and their interaction with the downstream blade rows was performed. The results indicate large variations in the downstream flow field, notably the development of the secondary flows. The mechanism of passage vortex transport was studied in two differently configured high-pressure turbine stages. In the first configuration, the blades are radially stacked while the second configuration features three-dimensionally stacked high-pressure steam turbine blading. The stator hub passage vortex is chopped by the downstream blade row in a similar way to the wake. The bowed vortex tube near the inlet to the rotor appeared to develop two counter-rotating legs extending back to the leading edges of the adjacent blades. These were termed the suction side leg and the pressure side leg. The two legs of the incoming passage vortex then convect with the respective velocities on the blade surfaces. The results are discussed for the radially stacked turbine and the 3-D turbine separately.

Venkata Siva Prasad Chaluvadi

2000-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Linear and nonlinear dynamics of current-driven waves in dusty plasmas  

SciTech Connect

The linear and nonlinear dynamics of a recently proposed plasma mode of dusty plasma is studied using kappa distribution for electrons. This electrostatic wave can propagate in the plasma due to the sheared flow of electrons and ions parallel to the external magnetic field in the presence of stationary dust. The coupling of this wave with the usual drift wave and ion acoustic wave is investigated. D'Angelo's mode is also modified in the presence of superthermal electrons. In the nonlinear regime, the wave can give rise to dipolar vortex structures if the shear in flow is weaker and tripolar vortices if the flow has steeper gradient. The results have been applied to Saturn's magnetosphere corresponding to negatively charged dust grains. But the theoretical model is applicable for positively charged dust as well. This work will be useful for future observations and studies of dusty environments of planets and comets.

Ahmad, Ali [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Ali Shan, S.; Haque, Q. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Saleem, H. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan)

2012-09-15T23:59:59.000Z

222

Small Water-Property Transporting Eddies: Statistical Outliers in the Hydrographic Data of the POLYMODE Local Dynamics Experiment  

Science Conference Proceedings (OSTI)

Hydrographic measurements from the POLYMODE Local Dynamics Experiment (LDE; 31°N, 69.5°W; May–July 1978) are examined for highly anomalous, outlying observations of salinity, oxygen and vortex stretching on isopycnal surfaces. The methodology ...

Eric J. Lindstrom; Bruce A. Taft

1986-03-01T23:59:59.000Z

223

Anomalous electron trapping by magnetic flux tubes and electric current vortices  

E-Print Network (OSTI)

Anomalous electron trapping by magnetic flux tubes and electric current vortices F. Bentosela, a current vortex in the plane. In this case the flux is zero; there is a pair of bound states for a weak with a nonhomogeneous magnetic field B , and investigate the corresponding Pauli Hamiltonian. We prove a lower bound

224

Effect of point-like disorder on the vortex phase diagram in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8-{delta}} in oblique field.  

Science Conference Proceedings (OSTI)

The phase diagram of vortex matter in the layered superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8-{delta}} exposed to a magnetic field oblique to the crystalline c-axis contains two first order transition (FOT) lines. The first, H{sub FOT}{sup m}, separates the vortex solid from the vortex liquid, the second, H{sub FOT}{sup ct}, separates the combined lattice state in the vortex solid from a tilted lattice state. The angular dependence of H{sub FOT}{sup m} in the tilted lattice region follows the anisotropic Ginzburg-Landau model, allowing for the determination of the anisotropy factor {gamma}{sub eff} and the contribution of magnetic coupling to the mutual interaction of 'pancake' vortices in the crossed lattice limit. The later parameter is directly related to the in-plane penetration depth {lambda}{sub ab}. We investigate the evolution of the phase diagram of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8-{delta}} in oblique fields with point-like disorder, introduced by irradiation with 2.3 MeV electrons. Apart from the depression of T{sub c}, point-like disorder induces an increase of {gamma}{sub eff} and a depression of the superfluid density.

Konczykowski, M.; van der Beek, C. J.; Mosser, V.; Koshelev, A. E.; Li, M.; Kes, P. H. (Materials Science Division); (Ecole Polytechnique); (ITRON); (Leiden Univ.)

2010-12-01T23:59:59.000Z

225

MHK Technologies/Vortex Oscillation | Open Energy Information  

Open Energy Info (EERE)

Oscillation Oscillation < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage Vortex Oscillation.jpg Technology Profile Primary Organization Vortex Oscillation Technology Ltd Technology Resource Click here Current Technology Type Click here Attenuator Technology Readiness Level Click here TRL 1 3 Discovery Concept Def Early Stage Dev Design Engineering Technology Description If cylinder or another body is fixed on a moving bonding this force can set the body or its separate parts into oscillation e g elastic slat If the system of mechanical energy output is organized correctly this device can be considered as generator Technology Dimensions Device Testing Date Submitted 08:12.7 << Return to the MHK database homepage Retrieved from

226

Electrodynamics of Magnetars III: Pair Creation Processes in an Ultrastrong Magnetic Field and Particle Heating in a Dynamic Magnetosphere  

E-Print Network (OSTI)

We consider the details of the QED processes that create electron-positron pairs in magnetic fields approaching and exceeding 10^{14} G. The formation of free and bound pairs is addressed, and the importance of positronium dissociation by thermal X-rays is noted. We calculate the collision cross section between an X-ray and a gamma ray, and point out a resonance in the cross section when the gamma ray is close to the threshold for pair conversion. We also discuss how the pair creation rate in the open-field circuit and the outer magnetosphere can be strongly enhanced by instabilities near the light cylinder. When the current has a strong fluctuating component, a cascade develops. We examine the details of particle heating, and show that a high rate of pair creation can be sustained close to the star, but only if the spin period is shorter than several seconds. The dissipation rate in this turbulent state can easily accommodate the observed radio output of the transient radio-emitting magnetars, and even their infrared emission. Finally, we outline how a very high rate of pair creation on the open magnetic field lines can help to stabilize a static twist in the closed magnetosphere and to regulate the loss of magnetic helicity by reconnection at the light cylinder.

Christopher Thompson

2008-02-19T23:59:59.000Z

227

Time--Distance Helioseismology Data Analysis Pipeline for Helioseismic and Magnetic Imager onboard Solar Dynamics Observatory (SDO/HMI) and Its Initial Results  

E-Print Network (OSTI)

The Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI) provides continuous full-disk observations of solar oscillations. We develop a data-analysis pipeline based on the time-distance helioseismology method to measure acoustic travel times using HMI Doppler-shift observations, and infer solar interior properties by inverting these measurements. The pipeline is used for routine production of near-real-time full-disk maps of subsurface wave-speed perturbations and horizontal flow velocities for depths ranging from 0 to 20 Mm, every eight hours. In addition, Carrington synoptic maps for the subsurface properties are made from these full-disk maps. The pipeline can also be used for selected target areas and time periods. We explain details of the pipeline organization and procedures, including processing of the HMI Doppler observations, measurements of the travel times, inversions, and constructions of the full-disk and synoptic maps. Some initial results from the pipeline, includin...

Zhao, J; Bogart, R S; Parchevsky, K V; Birch, A C; Duvall, T L; Beck, J G; Kosovichev, A G; Scherrer, P H

2011-01-01T23:59:59.000Z

228

Engineering Nanocolumnar Defect Configurations for Optimized Vortex Pinning in High Temperature Superconducting Nanocomposite Wires  

SciTech Connect

High temperature superconducting (HTS), coated conductor wires based on nanocomposite films containing self-assembled, insulating BaZrO3 (BZO) nanocolumnar defects have previously been reported to exhibit enhanced vortex pinning. Here, we report on microstructural design via control of BZO nanocolumns density in YBa2Cu3O7- (YBCO)+BZO nancomposite films to achieve the highest critical current density, Jc(H, ,T). X-ray diffraction and microstructural examination shows increasing number density of epitaxial BZO nanocolumns in the highly cube-textured YBCO matrix with increasing nominal BZO additions. Transport property measurement reveals that an increase in BZO content upto 4 vol% is required to sustain the highest pinning and Jc performance as the magnetic field increases. By growing thicker, single-layer nanocomposite films (~4 m) with controlled density of BZO columnar defects, the critical current (Ic) of ~1000 A/cm at 77 K, self-field and the minimum Ic of 455 A/cm at 65 K and 3 T for all magnetic field orientations were obtained. This is the highest Ic reported to date for films on metallic templates which are the basis for the 2nd generation, coated conductor-based HTS wires.

Wee, Sung Hun [ORNL; Zuev, Yuri L [ORNL; Cantoni, Claudia [ORNL; Goyal, Amit [ORNL; Ahuja, Raj [Waukesha Electric Systems Inc.; Abiade, J. [North Carolina A& T State University

2013-01-01T23:59:59.000Z

229

Designing Permanent Magnet Machines for Ferrofluid Immersion  

Science Conference Proceedings (OSTI)

Symposium, Magnetic Materials for Energy Applications -III ... associated costs, and reliability, with thermal and dynamic effects requiring adequate clearance.

230

Annihilation of vortex dipole in an Oblate Bose-Einstein Condensate  

E-Print Network (OSTI)

We theoretically explore the annihilation of vortex dipole, generated when an obstacle moves through a condensate, in an oblate Bose-Einstein Condensate and the possible reasons for the annihilation. We show that the grey soliton, which results from vortex dipole annihilation, is lower in energy than the vortex dipole. We also investigate the annihilation events numerically and observe annihilation occurs only when the vortex dipole overtake the obstacle. Further more, we find that the adding noise reduces the probability of annihilation events. This may explain the lack of annihilation events in experimental realizations.

Prabhakar, Shashi; Gautam, S; Angom, D

2013-01-01T23:59:59.000Z

231

Numerical Simulation of Flame-Vortex Interactions in Natural and Synthetic Gas Mixtures .  

E-Print Network (OSTI)

??The interactions between laminar premixed flames and counter-rotating vortex pairs in natural and synthetic gas mixtures have been computationally investigated through the use of Direct… (more)

Weiler, Justin D.

2004-01-01T23:59:59.000Z

232

MAGNETIC PROPERTIES OF THE ALS BOOSTER SYNCHROTRON ENGINEERING MODEL MAGNETS  

E-Print Network (OSTI)

Dynamic Aperture of the ALS Booster Synchrotron." presented25953 MAGNETIC PROPERTIES OF TIIE ALS BOOSTER SYNCIIROlRONMagnetic Measurements of the ALS Booster Dipole Engineering

Keller, R.

2010-01-01T23:59:59.000Z

233

Description of Selected Algorithms and Implementation Details of a Concept-Demonstration Aircraft VOrtex Spacing System (AVOSS)  

Science Conference Proceedings (OSTI)

A ground-based system has been developed to demonstrate the feasibility of automating the process of collecting relevant weather data, predicting wake vortex behavior from a data base of aircraft, prescribing safe wake vortex spacing criteria, estimating ...

Hinton David A.

2001-06-01T23:59:59.000Z

234

Cloud-Resolving Simulations of Mesoscale Vortex Intensification and Its Effect on a Serial Mesoscale Convective System  

Science Conference Proceedings (OSTI)

The authors performed numerical simulations of the 27–28 May 1998 mesoscale convective vortex (MCV) and mesoscale convective system (MCS) to understand how the MCV modulated the convection, and how the convection intensified the vortex. The fifth-...

Christopher A. Davis; Stanley B. Trier

2002-12-01T23:59:59.000Z

235

Complex Crystallization Dynamics in Amorphous Germanium ...  

Science Conference Proceedings (OSTI)

We used dynamic transmission electron microscopy [2] to study in situ this fast dynamics ... of Magnetism in Multiferroic Heterostructures and Low-power Devices ...

236

Synoptic-scale nonlinear stationary magnetized Rossby waves in the ionospheric E-layer  

Science Conference Proceedings (OSTI)

Magnetized Rossby waves are produced by a dynamo electric field and represent the ionospheric generalization of tropospheric Rossby waves in a rotating atmosphere with a spatially inhomogeneous geomagnetic field. They are described by the modified Charney-Obukhov equation with a Poisson-bracket convective nonlinearity. This type of equation has solutions in the form of synoptic-scale nonlinear solitary dipole vortex structures of 1000-3000 km in diameter. With the use of equivalence conditions, various stationary nonlinear solutions are obtained and investigated analytically. The basic characteristics of stationary vortex structures for magnetized Rossby waves are investigate000.

Kaladze, T. D. [Tbilisi State University, I. Vekua Institute of Applied Mathematics (Georgia); Horton, W. [University of Texas at Austin, Institute for Fusion Studies (United States)

2006-12-15T23:59:59.000Z

237

Solution of linear problems of the uniform motion of a vortex source in a multilayer fluid  

Science Conference Proceedings (OSTI)

A method of solving linear problems of the uniform motion of a vortex source in a multilayer fluid having an arbitrary finite number of layers is proposed. As an example, the problem of the motion of a vortex source of given intensity in a three-layer fluid is solved. Formulas for the complex velocities and hydrodynamic reactions are obtained.

Gorlov, S.I.

1995-11-01T23:59:59.000Z

238

Generalized London free energy for high-Tc vortex lattices Ian Affleck  

E-Print Network (OSTI)

Generalized London free energy for high-Tc vortex lattices Ian Affleck Department of Physics-1829 97 50402-4 The London free energy provides a very simple way of studying the vortex lattice that this effect can arise from additional quartic derivative terms in the Ginzburg-Landau GL free energy4­7 or

Franz, Marcel

239

Combustion in Meso-scale Vortex Chambers Ming-hsun Wu*  

E-Print Network (OSTI)

1 Combustion in Meso-scale Vortex Chambers Ming-hsun Wu* , Yanxing Wang, Vigor Yang and Richard A) #12;2 COMBUSTION IN MESO-SCALE VORTEX CHAMBERS Ming-hsun Wu, Yanxing Wang, Vigor Yang and Richard A with the chemical energy varying from 25 to 174W. For the largest combustion volume, hydrogen and hydrocarbons

Yang, Vigor

240

Research on Vortex Unstablity Caused by Bending Deformation of Drilling Bar in BTA Deep Hole Machining  

Science Conference Proceedings (OSTI)

Vortex and unstability of bending boring bar caused by cutting fluid force are researched, with Timoshenko beam model and mated vibration model, based on which machining quality of BTA deep hole drilling and tools life can be promoted in practice. Linear ... Keywords: deep hole boring, boring bar, Timoshenko beam, mating vibration, vortex motion stability

Zhanqi Hu; Wu Zhao

2009-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

On a Graphics Hardware-Based Vortex Detection and Visualization System  

Science Conference Proceedings (OSTI)

We present a graphics hardware-based system for interactive denoising, vortex detection, and visualization of vector data. No intermediate results need to be read back by the application once the vector field has been loaded onto the graphics adapter. ... Keywords: Flow visualization, Graphics hardware, Vortex detection

S. Stegmaier; T. Ertl

2005-04-01T23:59:59.000Z

242

Dynamic and Stagnating Plasma Flow Leading to Magnetic-Flux-Tube Collimation S. You, G. S. Yun, and P. M. Bellan  

E-Print Network (OSTI)

) of the observed structures. We propose that the collimation of any, initially flared, current-carrying magnetic-flux the flared current profile drives axial plasma flows along the flux tube; the flows convect frozen-in magnetic flux from strong magnetic field regions to weak magnetic field regions; flow stagnation then piles

243

Wigner distribution function and entanglement of generalized quantum optical vortex  

E-Print Network (OSTI)

We calculate the Wigner (quasi)probability distribution function of the quantum optical elliptical vortex (QEV), generated by coupling squeezed vacuum states of two modes. The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to the coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. We compute the entanglement of such QEV formed by non-classical radiation field, using Wigner function. We report a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Abir Bandyopadhyay; Shashi Prabhakar; R. P. Singh

2011-01-25T23:59:59.000Z

244

Vortex nozzle for segmenting and transporting metal chips from turning operations  

DOE Patents (OSTI)

Apparatus for collecting, segmenting and conveying metal chips from machining operations utilizes a compressed gas driven vortex nozzle for receiving the chip and twisting it to cause the chip to segment through the application of torsional forces to the chip. The vortex nozzle is open ended and generally tubular in shape with a converging inlet end, a constant diameter throat section and a diverging exhaust end. Compressed gas is discharged through angled vortex ports in the nozzle throat section to create vortex flow in the nozzle and through an annular inlet at the entrance to the converging inlet end to create suction at the nozzle inlet and cause ambient air to enter the nozzle. The vortex flow in the nozzle causes the metal chip to segment and the segments thus formed to pass out of the discharge end of the nozzle where they are collected, cleaned and compacted as needed.

Bieg, L.F.

1993-04-20T23:59:59.000Z

245

Vortex nozzle for segmenting and transporting metal chips from turning operations  

DOE Patents (OSTI)

This invention is comprised of an apparatus for collecting, segmenting and conveying metal chips from machining operations which utilizes a compressed gas driven vortex nozzle for receiving the chip and twisting it to cause the chip to segment through the application of torsional forces to the chip. The vortex nozzle is open ended and generally tubular in shape with a converging inlet end, a constant diameter throat section and a diverging exhaust end. Compressed gas is discharged through angled vortex ports in the nozzle throat section to create vortex flow in the nozzle and through an annular inlet at the entrance to the converging inlet end to create suction at the nozzle inlet and cause ambient air to enter the nozzle. The vortex flow in the nozzle causes the metal chip to segment and the segments thus formed to pass out of the discharge end of the nozzle where they are collected, cleaned and compacted as needed.

Bieg, L.F.

1992-12-31T23:59:59.000Z

246

Swift J1644+57 gone MAD: the case for dynamically-important magnetic flux threading the black hole in a jetted tidal disruption event  

E-Print Network (OSTI)

The unusual transient Swift J1644+57 likely resulted from a collimated relativistic jet powered by accretion onto a massive black hole (BH) following the tidal disruption (TD) of a star. Several mysteries cloud the interpretation of this event: (1) extreme flaring and `plateau' shape of the X-ray/gamma-ray light curve during the first 10 days after the gamma-ray trigger; (2) unexpected rebrightening of the forward shock radio emission months after trigger; (3) no obvious evidence for jet precession, despite misalignment typically expected between the angular momentum of the accretion disk and BH; (4) recent abrupt shut-off in jet X-ray emission after 1.5 years. Here we show that all of these seemingly disparate mysteries are naturally resolved by one assumption: the presence of strong magnetic flux Phi threading the BH. Initially, Phi is weak relative to high fall-back mass accretion rate, Mdot, and the disk and jets precess about the BH axis = our line of sight. As Mdot drops, Phi becomes dynamically important and leads to a magnetically-arrested disk (MAD). MAD naturally aligns disk and jet axis along the BH spin axis, but only after a violent rearrangement phase (jet wobbling). This explains the erratic light curve at early times and the lack of precession at later times. We use our model for Swift J1644+57 to constrain BH and disrupted star properties, finding that a solar-mass main sequence star disrupted by a relatively low mass, M~10^5-10^6 Msun, BH is consistent with the data, while a WD disruption (though still possible) is disfavored. The magnetic flux required to power Swift J1644+57 is too large to be supplied by the star itself, but it could be collected from a quiescent `fossil' accretion disk present in the galactic nucleus prior to the TD. The presence (lack of) of such a fossil disk could be a deciding factor in what TD events are accompanied by powerful jets.[abridged

Alexander Tchekhovskoy; Brian D. Metzger; Dimitrios Giannios; Luke Zoltan Kelley

2013-01-09T23:59:59.000Z

247

Heat Transfer Enhancement in Separated and Vortex Flows  

SciTech Connect

This document summarizes the research performance done at the Heat Transfer Laboratory of the University of Minnesota on heat transfer and energy separation in separated and vortex flow supported by DOE in the period September 1, 1998--August 31, 2003. Unsteady and complicated flow structures in separated or vortex flows are the main reason for a poor understanding of heat transfer under such conditions. The research from the University of Minnesota focused on the following important aspects of understanding such flows: (1) Heat/mass transfer from a circular cylinder; (2) study of energy separation and heat transfer in free jet flows and shear layers; and (3) study of energy separation on the surface and in the wake of a cylinder in crossflow. The current study used three different experimental setups to accomplish these goals. A wind tunnel and a liquid tunnel using water and mixtures of ethylene glycol and water, is used for the study of prandtl number effect with uniform heat flux from the circular cylinder. A high velocity air jet is used to study energy separation in free jets. A high speed wind tunnel, same as used for the first part, is utilized for energy separation effects on the surface and in the wake of the circular cylinder. The final outcome of this study is a substantial advancement in this research area.

Richard J. Goldstein

2004-05-27T23:59:59.000Z

248

Predictive Capability for Strongly Correlated Systems: Mott Transition in MnO, Multielectron Magnetic Moments, and Dynamics Effects in Correlated Materials  

SciTech Connect

There are classes of materials that are important to DOE and to the science and technology community, generically referred to as strongly correlated electron systems (SCES), which have proven very difficult to understand and to simulate in a material-specific manner. These range from actinides, which are central to the DOE mission, to transition metal oxides, which include the most promising components of new spin electronics applications as well as the high temperature superconductors, to intermetallic compounds whose heavy fermion characteristics and quantum critical behavior has given rise to some of the most active areas in condensed matter theory. The objective of the CMSN cooperative research team was to focus on the application of these new methodologies to the specific issue of Mott transitions, multi-electron magnetic moments, and dynamical properties correlated materials. Working towards this goal, the W&M team extended its first-principles phaseless auxiliary-field quantum Monte Carlo (AFQMC) method to accurately calculate structural phase transitions and excited states.

Krakauer, Henry; Zhang, Shiwei

2013-02-21T23:59:59.000Z

249

Studies of transition metal and overlayers dynamics and magnetism by HE and spin-polarized metastable HE beam spectroscopies. Technical progress report, 1 October, 1990--30 September, 1991  

DOE Green Energy (OSTI)

Experimental results for the investigation of quantum delocalization of hydrogen on the Pd(111) surface; the investigation of the structural and dynamical trends in the growth of Cu overlayers on Pd(111) surface; and the investigation of the magnetic structure of the NiO(111) surface using spin-polarized metastable He beam scattering are included in this paper. Planned research is also discussed.

El-Batanouny, M.

1992-01-16T23:59:59.000Z

250

An adaptive mesh method for the simulation of Blade Vortex Interaction  

E-Print Network (OSTI)

An adaptive mesh method for the simulation of parallel ics. Blade Vortex Interaction (BV1) with an active Trailing Edge Flap (TEF) is presented. The two-dimensional 1111-steady problem is solved by a higher order upwind Euler method for an unstructured mesh. A local mesh adaptation technique is employed to maintain vortex strength by capturing the details of the convecting vortex. The computational technique does not require any assumption on the vortex structure, and, therefore is suitable for close interaction of the vortex and the blade. The adaptive method is based on cell subdivisions and allows for frequent mesh adaptation due to its fast speed. To demonstrate the reduction of numerical dissipation of a vortex via mesh adaptation, we first consider a simple case with a convecting vortex in freestream. Finally, we apply tile techniques to examine the effectiveness of an active TEF on BVI in reducing the pressure perturbations at the airfoil leading edge. For the boundary motion due to TEF deployment, a local recessing procedure is utilized to maintain mesh quality by avoiding distorted mesh elements near the flap.

Kim, Kyu-Sup

1998-01-01T23:59:59.000Z

251

Dynamics of a global string with large Higgs boson mass  

E-Print Network (OSTI)

We consider a self-gravitating string generated by a global vortex solution in general relativity. We investigate the Einstein and field equations of a global vortex in the region of its central line and at a distance from the centre of the order of the inverse of its Higgs boson mass. By combining the two we establish by a limiting process of large Higgs mass the dynamics of a self-gravitating global string. Under our assumptions the presence of gravitation restricts the world sheet of the global string to be totally geodesic.

C. Charmousis; B. Boisseau; B. Linet

1997-08-01T23:59:59.000Z

252

Vortex Diode Analysis and Testing for Fluoride Salt-Cooled High-Temperature Reactors  

SciTech Connect

Fluidic diodes are presently being considered for use in several fluoride salt-cooled high-temperature reactor designs. A fluidic diode is a passive device that acts as a leaky check valve. These devices are installed in emergency heat removal systems that are designed to passively remove reactor decay heat using natural circulation. The direct reactor auxiliary cooling system (DRACS) uses DRACS salt-to-salt heat exchangers (DHXs) that operate in a path parallel to the core flow. Because of this geometry, under normal operating conditions some flow bypasses the core and flows through the DHX. A flow diode, operating in reverse direction, is-used to minimize this flow when the primary coolant pumps are in operation, while allowing forward flow through the DHX under natural circulation conditions. The DRACSs reject the core decay heat to the environment under loss-of-flow accident conditions and as such are a reactor safety feature. Fluidic diodes have not previously been used in an operating reactor system, and therefore their characteristics must be quantified to ensure successful operation. This report parametrically examines multiple design parameters of a vortex-type fluidic diode to determine the size of diode needed to reject a particular amount of decay heat. Additional calculations were performed to size a scaled diode that could be tested in the Oak Ridge National Laboratory Liquid Salt Flow Loop. These parametric studies have shown that a 152.4 mm diode could be used as a test article in that facility. A design for this diode is developed, and changes to the loop that will be necessary to test the diode are discussed. Initial testing of a scaled flow diode has been carried out in a water loop. The 150 mm diode design discussed above was modified to improve performance, and the final design tested was a 171.45 mm diameter vortex diode. The results of this testing indicate that diodicities of about 20 can be obtained for diodes of this size. Experimental results show similar trends as the computational fluid dynamics (CFD) results presented in this report; however, some differences exist that will need to be assessed in future studies. The results of this testing will be used to improve the diode design to be tested in the liquid salt loop system.

Yoder Jr, Graydon L [ORNL; Elkassabgi, Yousri M. [Texas A& M University, Kingsville; De Leon, Gerardo I. [Texas A& M University, Kingsville; Fetterly, Caitlin N. [Texas A& M University, Kingsville; Ramos, Jorge A. [Texas A& M University, Kingsville; Cunningham, Richard Burns [University of Tennessee, Knoxville (UTK)

2012-02-01T23:59:59.000Z

253

Gauge Dynamics and Topological Insulators  

E-Print Network (OSTI)

A non-abelian magnetic field in Yang-Mills theory induces the formation of a "W-boson" vortex lattice. We study the propagation of fundamental fermions in the presence of this lattice in 2+1 dimensions. We show that the spectrum for massless fermions contains four topologically-protected Dirac points with non-zero Bloch momentum. For massive fermions, we compute topological invariants of the band structure and show that it is possible to realise a Z2 topological insulator within Yang-Mills theory.

Benjamin Béri; David Tong; Kenny Wong

2013-05-10T23:59:59.000Z

254

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy

2012-09-16T23:59:59.000Z

255

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

Tsoy, L A; Komarov, A G; Tsoy, A N

2012-01-01T23:59:59.000Z

256

The Kinematics of a Midlatitude, Continental Mesoscale Convective System and Its Mesoscale Vortex  

Science Conference Proceedings (OSTI)

The authors present a unique, scale-discriminating study of the environment-relative circulations within a mesoscale convective system (MCS) and mesoscale convective vortex (MCV). The MCS, a leading convective line and trailing stratiform region ...

Jason C. Knievel; Richard H. Johnson

2002-07-01T23:59:59.000Z

257

Wave–Current Interaction: A Comparison of Radiation-Stress and Vortex-Force Representations  

Science Conference Proceedings (OSTI)

The vortex-force representation of the wave-averaged effects on currents is compared to the radiation-stress representation in a scaling regime appropriate to coastal and shelf waters. Three-dimensional and vertically integrated expressions for ...

E. M. Lane; J. M. Restrepo; J. C. McWilliams

2007-05-01T23:59:59.000Z

258

Evidence against an Antarctic Stratospheric Vortex Split during the Periods of Pre-IGY Temperature Measurements  

Science Conference Proceedings (OSTI)

Historic upper-air observations from Antarctica are inspected to investigate the uniqueness of the vortex split in the Antarctic spring of 2002. No comprehensive meteorological observations are available prior to the International Geophysical ...

Barbara Naujokat; Howard K. Roscoe

2005-03-01T23:59:59.000Z

259

Midtropospheric Anticyclonic Vortex Street Associated with a Cloud Band near a Cold Front  

Science Conference Proceedings (OSTI)

The characteristics and formation mechanism of an anticyclonic vortex street of meso-? scale, which appeared near a cold front around the Ryukyu Islands, Japan, on 11 April 1995, were examined by an analysis of observational data, a numerical ...

Eizi Toyoda; Hiroshi Niino; Kazuhisa Tsuboki; Ryuji Kimura; Masanori Yoshizaki

1999-08-01T23:59:59.000Z

260

Ensemble Forecasting of Tropical Cyclone Motion Using a Barotropic Model. Part II: Perturbations of the Vortex  

Science Conference Proceedings (OSTI)

In Part I of this study, the technique of ensemble forecasting is applied to the problem of tropical cyclone motion prediction by perturbing the environmental flow. In this part, the focus is shifted to perturbation of the vortex structure. The ...

Kevin K. W. Cheung; Johnny C. L. Chan

1999-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Structure of a Midtropospheric Vortex Induced by a Mesoscale Convective System  

Science Conference Proceedings (OSTI)

On 9 June 1988 a mesoscale (200-km diameter) convectively generated vortex (MCV) passed through the Colorado wind-profiling network. The generating convective system, which was too small to meet Maddox’s mesoscale convective complex criteria, ...

Diana L. Bartels; John M. Brown; Edward I. Tollerud

1997-02-01T23:59:59.000Z

262

A Vortex-Based Perspective of Eastern Pacific Tropical Cyclone Formation  

Science Conference Proceedings (OSTI)

Tropical cyclone formation over the eastern Pacific during 2005 and 2006 was examined using primarily global operational analyses from the National Centers for Environmental Prediction. This paper represents a “vortex view” of genesis, adding to ...

Christopher Davis; Chris Snyder; Anthony C. Didlake Jr.

2008-07-01T23:59:59.000Z

263

Observations of a Storm Containing Misocyclones, Downbursts, and Horizontal Vortex Circulations  

Science Conference Proceedings (OSTI)

On 30 June 1982, a multicellular storm in Colorado produced four downbursts, three misocyclones, a miso-anticyclone, and horizontal vortex circulations within a relatively small area of the storm. Weather events associated with this storm ...

Cathy J. Kessinger; David B. Parsons; James W. Wilson

1988-10-01T23:59:59.000Z

264

The Role of Vortex and Environment Errors in Genesis Forecasts of Hurricanes Danielle and Karl (2010)  

Science Conference Proceedings (OSTI)

An ensemble of Weather Research and Forecasting Model (WRF) forecasts initialized from a cycling ensemble Kalman filter (EnKF) system is used to evaluate the sensitivity of Hurricanes Danielle and Karl’s (2010) genesis forecasts to vortex and ...

Ryan D. Torn; David Cook

2013-01-01T23:59:59.000Z

265

An Analytic Vortex Initialization Technique for Idealized Tropical Cyclone Studies in AGCMs  

Science Conference Proceedings (OSTI)

The paper discusses the design of idealized tropical cyclone experiments in atmospheric general circulation models (AGCMs). The evolution of an initially weak, warm-core vortex is investigated over a 10-day period with varying initial conditions ...

Kevin A. Reed; Christiane Jablonowski

2011-02-01T23:59:59.000Z

266

The Garden City, Kansas, Storm during VORTEX 95. Part II: The Wall Cloud and Tornado  

Science Conference Proceedings (OSTI)

On 16 May 1995, a supercell storm produced an F1 tornado near Garden City, Kansas, during VORTEX (Verification of the Origins of Rotation in Tornadoes Experiment). This event provided the first opportunity to synthesize data collected by a new ...

Roger M. Wakimoto; Chinghwang Liu

1998-02-01T23:59:59.000Z

267

The Effect of Tropospheric Jet Latitude on Coupling between the Stratospheric Polar Vortex and the Troposphere  

Science Conference Proceedings (OSTI)

A dry general circulation model is used to investigate how coupling between the stratospheric polar vortex and the extratropical tropospheric circulation depends on the latitude of the tropospheric jet. The tropospheric response to an identical ...

Chaim I. Garfinkel; Darryn W. Waugh; Edwin P. Gerber

2013-03-01T23:59:59.000Z

268

The Role of Multiple Vortex Tornado Structure in Causing Storm Researcher Fatalities  

Science Conference Proceedings (OSTI)

A large and violent tornado/multiple vortex mesocyclone (MVMC) / tornado tracked east and northeastward near El Reno, Oklahoma on 31-May-2013, causing eight fatalities, including storm-chasers/researchers attempting to deploy in-situ instrumentation. Sub-...

Joshua Wurman; Karen Kosiba; Paul Robinson; Tim Marshall

269

A Concentrated Outbreak of Tornadoes, Downbursts and Microbursts, and Implications Regarding Vortex Classification  

Science Conference Proceedings (OSTI)

A remarkable case of severe weather occurred near Springfield, Illinois on 6 August 1977. Aerial and ground surveys revealed that 17 cyclonic vortices an anticyclonic vortex, 10 downbursts and 19 microbursts occurred in a limited (20 km × 40 km) ...

Gregory S. Forbes; Roger M. Wakimoto

1983-01-01T23:59:59.000Z

270

Mesoscale Convective Vortex Formation in a Weakly Sheared Moist Neutral Environment  

Science Conference Proceedings (OSTI)

Idealized simulations of a diabatic Rossby vortex (DRV) in an initially moist neutral baroclinic environment are performed using the fifth-generation National Center for Atmospheric Research–Pennsylvania State University (NCAR–PSU) Mesoscale ...

Robert J. Conzemius; Richard W. Moore; Michael T. Montgomery; Christopher A. Davis

2007-05-01T23:59:59.000Z

271

Intense Vortex Motion on the Beta Plane: Development of the Beta Gyres  

Science Conference Proceedings (OSTI)

An analytical theory is presented for the self-induced translation of an intense vortex relative to a uniform background flow on the ? plane. The equivalent barotropic approximation is used to formulate the initial value problem within a polar ...

Georgi G. Sutyrin; Glenn R. Flierl

1994-03-01T23:59:59.000Z

272

Interaction of a Baroclinic Vortex with Background Shear: Application to Hurricane Movement  

Science Conference Proceedings (OSTI)

Most extant studies of tropical cyclone movement consider a barotropic vortex on a ? plane. However, observations have shown that real tropical cyclones are strongly baroclinic, with broad anticyclones aloft. Also, the distribution of the large-...

Chun-Chieh Wu; Kerry A. Emanuel

1993-01-01T23:59:59.000Z

273

Verification of RUC 0–1-h Forecasts and SPC Mesoscale Analyses Using VORTEX2 Soundings  

Science Conference Proceedings (OSTI)

This study uses radiosonde observations obtained during the second phase of the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) to verify base-state variables and severe-weather-related parameters calculated from Rapid ...

Michael C. Coniglio

2012-06-01T23:59:59.000Z

274

The Gradient Genesis of Stratospheric Trace Species in the Subtropics and around the Polar Vortex  

Science Conference Proceedings (OSTI)

Mechanisms that control the formation and decay of meridional gradients in stratospheric trace species in the subtropics and around the polar vortex are investigated using a gradient genesis equation that uses mass-weighted isentropic zonal ...

Kazuyuki Miyazaki; Toshiki Iwasaki

2008-02-01T23:59:59.000Z

275

A Mesoscale Vortex Couplet Observed in the Trailing Anvil of a Multicellular Convective Complex  

Science Conference Proceedings (OSTI)

Observations collected during the Oklahoma–Kansas PRE-STORM experiment are used to document the evolution and structure of a mesoscale vortex couplet that developed in the mesoscale convective system that occurred on 16–17 June 1985. The ...

Johannes Verlinde; William R. Cotton

1990-05-01T23:59:59.000Z

276

Parametric Representation of the Primary Hurricane Vortex. Part II: A New Family of Sectionally Continuous Profiles  

Science Conference Proceedings (OSTI)

For applications such as windstorm underwriting or storm-surge forecasting, hurricane wind profiles are often approximated by continuous functions that are zero at the vortex center, increase to a maximum in the eyewall, and then decrease ...

H. E. Willoughby; R. W. R. Darling; M. E. Rahn

2006-04-01T23:59:59.000Z

277

Influence of Balanced Motions on Heavy Precipitation within a Long-Lived Convectively Generated Vortex  

Science Conference Proceedings (OSTI)

The forcing of heavy precipitation within a long-lived convectively generated mesoscale vortex (MCV) is investigated with the aid of diagnoses from Rapid Update Cycle gridded analyses. Organized convection within the MCV followed a distinct ...

Stanley B. Trier; Christopher A. Davis

2002-04-01T23:59:59.000Z

278

Source of Gravity Waves within a Vortex-Dipole Jet Revealed by a Linear Model  

Science Conference Proceedings (OSTI)

This study develops a linear numerical model to address the source mechanism of the gravity waves generated within a vortex dipole simulated in a fully nonlinear nonhydrostatic mesoscale model. The background flow for this linear model is ...

Shuguang Wang; Fuqing Zhang

2010-05-01T23:59:59.000Z

279

Submonthly Polar Vortex Variability and Stratosphere–Troposphere Coupling in the Arctic  

Science Conference Proceedings (OSTI)

A principal component analysis is performed to characterize intraseasonal variability in the boreal stratospheric polar vortex. In contrast to previous studies, the current analysis examines daily zonal-mean variability within a limited spatial ...

Robert X. Black; Brent A. McDaniel

2009-11-01T23:59:59.000Z

280

A New Parametric Model of Vortex Tangential-Wind Profiles: Development, Testing, and Verification  

Science Conference Proceedings (OSTI)

A new parametric model of vortex tangential-wind profiles is presented that is primarily designed to depict realistic-looking tangential wind profiles such as those in intense atmospheric vortices arising in dust devils, waterspouts, tornadoes, ...

Vincent T. Wood; Luther W. White

2011-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Maximum Likelihood Estimates of Vortex Parameters from Simulated Coherent Doppler Lidar Data  

Science Conference Proceedings (OSTI)

The performance of pulsed coherent Doppler lidar in estimating aircraft trailing wake vortices by scanning across the aircraft flight track is evaluated using Monte Carlo lidar simulations of a simple vortex pair in both a nonturbulent and ...

Rod Frehlich; Robert Sharman

2005-02-01T23:59:59.000Z

282

An Observational Study of the Final Breakdown of the Southern Hemisphere Stratospheric Vortex in 2002  

Science Conference Proceedings (OSTI)

The 2002 Southern Hemisphere final warming occurred early, following an unusually active winter and the first recorded major warming in the Antarctic. The breakdown of the stratospheric polar vortex in October and November 2002 is examined using ...

Yvan J. Orsolini; Cora E. Randall; Gloria L. Manney; Douglas R. Allen

2005-03-01T23:59:59.000Z

283

A Subtropical Oceanic Mesoscale Convective Vortex Observed during SoWMEX/TiMREX  

Science Conference Proceedings (OSTI)

This study examines a subtropical oceanic mesoscale convective vortex (MCV) that occurred from 1800 UTC 4 June to 1200 UTC 6 June 2008 during intensive observing period (IOP) 6 of the Southwest Monsoon Experiment (SoWMEX) and the Terrain-...

Hsiao-Wei Lai; Christopher A. Davis; Ben Jong-Dao Jou

2011-08-01T23:59:59.000Z

284

Enhancement of vortex induced forces and motion through surface roughness control  

SciTech Connect

Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

Bernitsas, Michael M. (Saline, MI); Raghavan, Kamaldev (Houston, TX)

2011-11-01T23:59:59.000Z

285

Vortex Lattice Structures of a Bose-Einstein Condensate in a Rotating Lattice Potential  

E-Print Network (OSTI)

We study vortex lattice structures of a trapped Bose-Einstein condensate in a rotating lattice potential by numerically solving the time-dependent Gross-Pitaevskii equation. By rotating the lattice potential, we observe the transition from the Abrikosov vortex lattice to the pinned lattice. We investigate the transition of the vortex lattice structure by changing conditions such as angular velocity, intensity, and lattice constant of the rotating lattice potential. PACS numbers: 03.75.Lm, 03.75.Kk Quantized vortices are one of the most characteristic manifestations of superfluidity associated with a Bose-Einstein condensate (BEC) in atomic gases. By rotating anisotropic trap potentials, several experimental groups observed formation of triangular Abrikosov lattices of vortices in rotating BECs 1,2,3. Microscopic mechanism of the vortex lattice formation has been extensively studied both analytically and numerically using the Gross-Pitaevskii (GP) equation for the condensate wavefunction 4,5,6,7,8,9,10,11. More recently, the vortex phase diagrams of a BEC in rotating lattice potentials have attracted theoretical attention, since one expects vortex pinning and structural phase transition of vortex lattice structures 12,13,14. Recently, a rotating lattice has been experimentally realized at JILA, makinig use of a laser beam passing through a rotating mask 12. Stimulated by the recent JILA experiment, in this paper, we study vortex lattice structures of a BEC in a rotating triangular lattice potential created by blue-detuned laser beams. We numerically solve the two-dimensional Gross-Pitaevskii (GP) equa-T. Sato, T. Ishiyama and T. Nikuni Fig. 1. Density profile (a) and Structure factor profile (b) of BEC in the lattice potential. The lattice potential geometry is triangular lattice at a/aho = 2.2 and ?/aho = 0.65. tion in a frame rotationg with anguler velocity ?: (i ? ?)¯h ??(r,t)

Toshihiro Sato; Tomohiko Ishiyama; Tetsuro Nikuni

2006-01-01T23:59:59.000Z

286

MATHEMATICAL MODELS OF HYSTERESIS (DYNAMIC PROBLEMS IN HYSTERESIS)  

SciTech Connect

This research has further advanced the current state of the art in the areas of dynamic aspects of hysteresis and nonlinear large scale magnetization dynamics. The results of this research will find important engineering applications in the areas of magnetic data storage technology and the emerging technology of “spintronics”. Our research efforts have been focused on the following tasks: • Study of fast (pulse) precessional switching of magnetization in magnetic materials. • Analysis of critical fields and critical angles for precessional switching of magnetization. • Development of inverse problem approach to the design of magnetic field pulses for precessional switching of magnetization. • Study of magnetization dynamics induced by spin polarized current injection. • Construction of complete stability diagrams for spin polarized current induced magnetization dynamics. • Development of the averaging technique for the analysis of the slow time scale magnetization dynamics. • Study of thermal effects on magnetization dynamics by using the theory of stochastic processes on graphs.

Professor Isaak Mayergoyz

2006-08-21T23:59:59.000Z

287

Near-Surface Vortex Structure in a Tornado and in a Sub-Tornado-Strength, Convective-Storm Vortex Observed by a Mobile, W-Band Radar During VORTEX2  

Science Conference Proceedings (OSTI)

As part of the VORTEX2 field campaign, a very high-resolution, mobile, W-band Doppler radar collected near-surface (?200 m AGL) observations in an EF-0 tornado near Tribune, Kansas on 25 May 2010 and in sub-tornado-strength vortices near Prospect ...

Robin L. Tanamachi; Howard B. Bluestein; Ming Xue; Wen-Chau Lee; Krzysztof A. Orzel; Stephen J. Frasier; Roger M. Wakimoto

288

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

289

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

290

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

291

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

292

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

293

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

294

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

295

Magnetic Reconnection  

SciTech Connect

We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two- uid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also brie y discussed.

Masaaki Yamada, Russell Kulsrud and Hantao Ji

2009-09-17T23:59:59.000Z

296

ANALYTICAL STUDY OF SOME ASPECTS OF VORTEX TUBES FOR GAS-PHASE FISSION HEATING  

DOE Green Energy (OSTI)

Several problems connected with vortex cavity reactors were studied analytically. They include, the generation of high-strength vortices by utilization of bleed through a porous tube wall to stabilize the shear layer on the wall; the nuclear criticality problem; the suitability of various compounds of plutonium as gaseous fissionable materials; and the problem of retaining the fission fragments within the vortex tube. It is concluded that the shear layer on the vortex tube wall can be stabilized if a mass flow greater than or equal to the vortex through flow is bled through the porous wall, and that the tangential Mach numbers which can be obtained are then slightly more than one-half the inviscid values. Beryllium oxide or graphite-moderated reactors of reasonable size and weight can attain criticality if the product of the hydrogen pressure in the vortex core and the maximum value of the ratio of fissionable gas density to hydrogen density in the tube is greater than about 100 atm. The reactor weights are then in the order of 10,000 lb or less. Of the several compounds of plutonium considered as gaseous fuel carriers, plutonium trifluoride and plutonium tribromide appear to be the most promising. It is probable that they can be held in gaseous form in hydrogen, under the desired concentrations. The rate of loss of fission fragments from the vortex tube can be reduced to a small fraction of the rate of their generation by making the vortex tubes about twice the minimum size that is allowable for satisfactory retention of the fissionable material. (auth)

Kerrebrock, J.L.; Lafyatis, P.G.

1958-07-21T23:59:59.000Z

297

SOLAR MAGNETIZED 'TORNADOES': RELATION TO FILAMENTS  

Science Conference Proceedings (OSTI)

Solar magnetized 'tornadoes', a phenomenon discovered in the solar atmosphere, appear as tornado-like structures in the corona but are rooted in the photosphere. Like other solar phenomena, solar tornadoes are a feature of magnetized plasma and therefore differ distinctly from terrestrial tornadoes. Here we report the first analysis of solar 'tornadoes' (two papers which focused on different aspects of solar tornadoes were published in the Astrophysical Journal Letters and Nature, respectively, during the revision of this Letter). A detailed case study of two events indicates that they are rotating vertical magnetic structures probably driven by underlying vortex flows in the photosphere. They usually exist as a group and are related to filaments/prominences, another important solar phenomenon whose formation and eruption are still mysteries. Solar tornadoes may play a distinct role in the supply of mass and twists to filaments. These findings could lead to a new explanation of filament formation and eruption.

Su Yang; Veronig, Astrid; Temmer, Manuela [IGAM-Kanzelhoehe Observatory, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Wang Tongjiang [Department of Physics, Catholic University of America, Washington, DC 20064 (United States); Gan Weiqun, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2012-09-10T23:59:59.000Z

298

UNIVERSITY OF CALIFORNIA, SAN DIEGO Experiments on Vortex Symmetrization in Magnetized Electron Plasma Columns  

E-Print Network (OSTI)

. Soloshenko IA et al (2000) Plasma Phys Reports 26:792 22. Laroussi M, Mendis DA, Rosenberg M (2003) New J

California at San Diego, University of

299

Statistical Behavior of Formation Process of Magnetic Vortex State in Ni80Fe20 Nanodisks  

E-Print Network (OSTI)

This work was supported by the Director, Office of Science,Office of Basic Energy Sciences, Materials Sciences and

Im, Mi-Young

2011-01-01T23:59:59.000Z

300

Neutron spin echo spectroscopy and membrane dynamics in ...  

Science Conference Proceedings (OSTI)

... incoherent-quasi-elastic scattering nuclear magnetic resonance etc. ... Page 11. Membrane dynamics – theory for bending - Helfrich bending energy ...

2013-06-17T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Increase of pinning with temperature for a single vortex line in superfluid helium  

E-Print Network (OSTI)

While vortex pinning in superconductors usually becomes weaker at higher temperatures, we find the opposite behavior for a single vortex line in superfluid 4 He. The pinning steadily increases over our entire measurement range, from 0.15Tc to over 0.5Tc. We propose Kelvin waves along the vortex as a depinning mechanism with the observed temperature behavior. PACS numbers: 67.40.Vs, 74.60.Ge Pinning sites can trap vortices in a variety of systems. In superconductors, where vortex motion leads to non-zero resistance, a vast amount of work has been devoted to preventing such motion by introducing defects. Experimental work has shown that defects comparable in size to the vortex core make effective pin centers, and that straight [1] or splayed [2] line defects can increase the pin strength. Yet the mechanisms by which vortices interact with pin sites remain unresolved. Experimentally, pinning becomes weaker as temperature increases, in accord with the general assumption that depinning

L. A. K. Donev; L. Hough; R. J. Zieve

2000-01-01T23:59:59.000Z

302

OTEC cold water pipe design for problems caused by vortex-excited oscillations  

DOE Green Energy (OSTI)

Vortex-excited oscillations of marine structures result in reduced fatigue life, large hydrodynamic forces and induced stresses, and sometimes lead to structural damage and to diestructive failures. The cold water pipe of an OTEC plant is nominally a bluff, flexible cylinder with a large aspect ratio (L/D = length/diameter), and is likely to be susceptible to resonant vortex-excited oscillations. The objective of this report is to survey recent results pertaining to the vortex-excited oscillations of structures in general and to consider the application of these findings to the design of the OTEC cold water pipe. Practical design calculations are given as examples throughout the various sections of the report. This report is limited in scope to the problems of vortex shedding from bluff, flexible structures in steady currents and the resulting vortex-excited oscillations. The effects of flow non-uniformities, surface roughness of the cylinder, and inclination to the incident flow are considered in addition to the case of a smooth cyliner in a uniform stream. Emphasis is placed upon design procedures, hydrodynamic coefficients applicable in practice, and the specification of structural response parameters relevant to the OTEC cold water pipe. There are important problems associated with in shedding of vortices from cylinders in waves and from the combined action of waves and currents, but these complex fluid/structure interactions are not considered in this report.

Griffin, O. M.

1980-03-14T23:59:59.000Z

303

RESEARCH ARTICLE Dynamic wind loads and wake characteristics of a wind turbine  

E-Print Network (OSTI)

RESEARCH ARTICLE Dynamic wind loads and wake characteristics of a wind turbine model of the unsteady vortex and turbulent flow structures in the near wake of a horizontal axis wind turbine model.e., aerodynamic forces and bending moments) acting on the wind turbine model by using a high-sensitive force

Hu, Hui

304

Vortex combustor for low NOX emissions when burning lean premixed high hydrogen content fuel  

Science Conference Proceedings (OSTI)

A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

Steele, Robert C; Edmonds, Ryan G; Williams, Joseph T; Baldwin, Stephen P

2012-11-20T23:59:59.000Z

305

Mitigation of Wind Turbine/Vortex Interaction Using Disturbance Accommodating Control  

DOE Green Energy (OSTI)

Wind turbines, a competitive source of emission-free electricity, are being designed with diameters and hub heights approaching 100 m, to further reduce the cost of the energy they produce. At this height above the ground, the wind turbine is exposed to atmospheric phenomena such as low-level jets, gravity waves, and Kelvin-Helmholtz instabilities, which are not currently modeled in wind turbine design codes. These atmospheric phenomena can generate coherent turbulence that causes high cyclic loads on wind turbine blades. These fluctuating loads lead to fatigue damage accumulation and blade lifetime reduction. Advanced control was used to mitigate vortex-induced blade cyclic loading. A full-state feedback controller that incorporates more detailed vortex inputs achieved significantly greater blade load reduction. Blade loads attributed to vortex passage, then, can be reduced through advanced control, and further reductions appear feasible.

Hand, M. M.

2003-12-01T23:59:59.000Z

306

Vortex combustor for low NOx emissions when burning lean premixed high hydrogen content fuel  

DOE Patents (OSTI)

A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

Steele, Robert C. (Woodinville, WA); Edmonds, Ryan G. (Renton, WA); Williams, Joseph T. (Kirkland, WA); Baldwin, Stephen P. (Winchester, MA)

2009-10-20T23:59:59.000Z

307

Phase-Field Simulations of a Simple Voltage-Controlled Magnetic ...  

Science Conference Proceedings (OSTI)

The voltage-induced magnetization and/or magnetic domain switching dynamics in ... Our results offer a promising new way towards future high-performance ...

308

Verification of the Origins of Rotation in Tornadoes Experiment: VORTEX  

Science Conference Proceedings (OSTI)

This paper describes the Verification of the Origins of Rotation in Tornadoes Experiment planned for 1994 and 1995 to evaluate a set of hypotheses pertaining to tornadogenesis and tornado dynamics. Observations of state variables will be obtained ...

Erik N. Rasmussen; Jerry M. Straka; Robert Davies-Jones; Charles A. Doswell III; Frederick H. Carr; Michael D. Eilts; Donald R. MacGorman

1994-06-01T23:59:59.000Z

309

Particle filtering with Lagrangian data in a point vortex model  

E-Print Network (OSTI)

Particle filtering is a technique used for state estimation from noisy measurements. In fluid dynamics, a popular problem called Lagrangian data assimilation (LaDA) uses Lagrangian measurements in the form of tracer positions ...

Mitra, Subhadeep

2012-01-01T23:59:59.000Z

310

Vortex Street Dynamics: The Selection Mechanism for the Areas and Locations of Jupiter’s Vortices  

Science Conference Proceedings (OSTI)

With the exception of the Great Red Spot, Jupiter’s long-lived vortices are not isolated, but occur in east–west rows. Each row is centered about a westward-going jet stream with anticyclones on the poleward side and cyclones on the equatorial. ...

Tom Humphreys; Philip S. Marcus

2007-04-01T23:59:59.000Z

311

Numerical and analytical studies of two-dimensional vortex pair dynamics in unstratified and stratified environments  

E-Print Network (OSTI)

J. Fluid Mech. , 347, Garten, J. F. , Arendt, S. , Fritts,environments. J. Fluid Mech. , Garten, J. F. , Werne, J. ,the generated vorticity (Garten et al. , 2001). In addition

Brandt, Laura Katherine

2009-01-01T23:59:59.000Z

312

Dynamics of topological light states in spiraling structures  

E-Print Network (OSTI)

We expose a mechanism for the dynamical generation and control of light states with diverse topologies in spiraling guiding structures. Specifically, we show that spiraling shallow refractive index landscapes induce coupling and periodic energy exchange between states with different topological charges. Such a resonant effect enables excitation of optical vortices by vortex-free inputs and allows the output topological charge of the beam to be controlled. The presence of nonlinearity results in a strong asymmetrization of the resonant curves and a shift of the resonant frequencies. Resonant vortex dynamic generation, including revivals, is shown to be possible not only in waveguides mediated by total internal reflection but also in Bragg-guiding hollow-core geometries.

Kartashov, Yaroslav V; Torner, Lluis

2013-01-01T23:59:59.000Z

313

DYNAMIC APERTURE OF THE ALS BOOSTER SYNCHROTRON  

E-Print Network (OSTI)

Nelson, "Magnetic Properties of the ALS noosler Synchrotron23,1989 Dynamic Aperture of the ALS Booster Synchrotron C.H.DYNAMIC APERTURE OF TIlE ALS BOOSTER SYNCIIROlRON· CharI""

Kim, C.H.

2010-01-01T23:59:59.000Z

314

HAWT performance with dynamic stall  

DOE Green Energy (OSTI)

In this report we calculated the effects of flow nonuniformities (wing shear, tower wake, yaw, and large-scale turbulence) on the performance of a horizontal axis wind turbine, accounting for dynamic stall. We modified the PROP program to incorporate and compare these effects with the uniform flow case. The MIT model, which predicts dynamic lift coefficients substantially higher than the static maximum values and includes a crude model of the vortex roll-off phenomenon, represented dynamic stall. As associated model for drag was also used. The dynamic stall model was tested against experimental data for three typical reduced frequencies. Good instantaneous correlation was obtained. The effects of nonuniformities with and without the dynamic stall were calculated using the Westinghouse Mod O and Enertech 44/25 turbines. Modeling the dynamic stall has little effect on performance. Furthermore, the performance with nonuniform flow differed only slightly from the uniform flow case. Thus the now PROP model provides a powerful general capability to handle nonuniform flows.

Hibbs, B.D.

1986-02-01T23:59:59.000Z

315

Superconducting Magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

magnet technology has allowed physicists to attain higher energies in circular accelerators. One can obtain higher magnetic fields because there is no resistance in a...

316

Linear and Nonlinear Vortex Motion in an Asymmetric Balance Shallow Water Model  

Science Conference Proceedings (OSTI)

This work extends asymmetric balance (AB) theory to the beta plane (?-AB). The physical problem examined is the motion of a coherent vortex on a beta plane in a finite depth fluid in the absence of an environmental steering flow. A useful ...

Michael T. Montgomery; J. Dominique Möller; Christopher T. Nicklas

1999-03-01T23:59:59.000Z

317

The Effect of Vorticity-Profile Shape on the Instability of a Two-Dimensional Vortex  

Science Conference Proceedings (OSTI)

A simple linear numerical model is used to study the effect of the shape of the vertical vorticity profile on the stability characteristics of a two-dimensional vortex. In all cases, the basic-state vorticity is confined to an annulus. It is ...

Jerry L. Steffens

1988-01-01T23:59:59.000Z

318

Stability of a Two-Layer Quasigeostrophic Vortex over Axisymmetric Localized Topography  

Science Conference Proceedings (OSTI)

The stability of a quasigeostrophic vortex over a radially symmetric topographic feature (elevation or depression) in a two-layer ocean on the f plane is examined. This article’s concern is with compensated vortices, that is, those in which the ...

E. S. Benilov

2005-01-01T23:59:59.000Z

319

Indirect Combustion Noise: Experimental Investigation of the Vortex Sound Generation in a Choked  

E-Print Network (OSTI)

Indirect Combustion Noise: Experimental Investigation of the Vortex Sound Generation in a Choked-27 April 2012, Nantes, France 2315 #12;Combustion noise in gas turbines consists of direct noise related to the unsteady combustion process itself and indirect noise. As known, indirect noise is produced when entropy

Paris-Sud XI, Université de

320

Longitudinally Dependent Ozone Increase in the Antarctic Polar Vortex Revealed by Balloon and Satellite Observations  

Science Conference Proceedings (OSTI)

The horizontal structure of processes causing increases in ozone in the Antarctic polar vortex was examined using data measured in 2003 from an ozonesonde observation campaign at Syowa Station (39.6°E, 69.0°S) and from the Improved Limb ...

K. Sato; Y. Tomikawa; G. Hashida; T. Yamanouchi; H. Nakajima; T. Sugita

2009-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Ozone Forecasts of the Stratospheric Polar Vortex–Splitting Event in September 2002  

Science Conference Proceedings (OSTI)

The Southern Hemisphere major warming event in September 2002 has led to a breakup of the vortex in the middle and higher stratosphere and to a corresponding splitting of the ozone hole. Daily 3D ozone forecasts, produced at the Royal Netherlands ...

Henk Eskes; Arjo Segers; Peter van Velthoven

2005-03-01T23:59:59.000Z

322

Genesis of the Goshen County, Wyoming, Tornado on 5 June 2009 during VORTEX2  

Science Conference Proceedings (OSTI)

The genesis of a strong and long-lived tornado observed during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) in Goshen County, Wyoming, on 5 June 2009 is studied. Mobile radar, mobile mesonet, rawinsonde, and ...

Karen Kosiba; Joshua Wurman; Yvette Richardson; Paul Markowski; Paul Robinson; James Marquis

2013-04-01T23:59:59.000Z

323

Generation and Stability of a Quasi-Permanent Vortex in the Lofoten Basin  

Science Conference Proceedings (OSTI)

In the Nordic seas the Lofoten Basin is a region of high mesoscale activity. The generation mechanism and the conditions for the stability of a quasi-permanent vortex in the center of the Lofoten Basin are studied with a high-resolution ocean ...

Armin Köhl

2007-11-01T23:59:59.000Z

324

Asymptotic and numerical analysis of an inviscid bounded vortex flow at low Mach number  

Science Conference Proceedings (OSTI)

The inviscid low Mach number compressible flow developing from a plane incompressible vortex with constant density in a bounded domain is studied. A reference solution for this model flow is obtained by two-time scale asymptotic development in the zero ... Keywords: Asymptotic development, Compressible low Mach number flow, Explicit Roe scheme, Implicit scheme, WENO and high-order-compact schemes

Anne Cadiou; Lionel Le Penven; Marc Buffat

2008-09-01T23:59:59.000Z

325

Study of a Heavy Rain Vortex Formed over the Eastern Flank of the Tibetan Plateau  

Science Conference Proceedings (OSTI)

A case of the heavy rain vortex which occurred during the period 14–15 July 1979 is studied using a limited-area mesoscale numerical model. This is a representative example of a group of warm southwest vortices that often form over the eastern ...

Bin Wang; Isidoro Orlanski

1987-07-01T23:59:59.000Z

326

The Final Warming Date of the Antarctic Polar Vortex and Influences on its Interannual Variability  

Science Conference Proceedings (OSTI)

More than 40 years of radiosonde data from two Antarctic stations are examined for changes in the date of the final stratospheric warming that occurs each year as the vortex breaks up in spring/summer. A new measure of this date is derived that ...

Joanna D. Haigh; Howard K. Roscoe

2009-11-01T23:59:59.000Z

327

The Second Verification of the Origins of Rotation in Tornadoes Experiment: VORTEX2  

Science Conference Proceedings (OSTI)

The second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2), which had its field phases in May and June of 2009 and 2010, was designed to explore i) the physical processes of tornadogenesis, maintenance, and demise; ii) the ...

Joshua Wurman; David Dowell; Yvette Richardson; Paul Markowski; Erik Rasmussen; Donald Burgess; Louis Wicker; Howard B. Bluestein

2012-08-01T23:59:59.000Z

328

Effective field theory for two-species bosons in an optical lattice: Multiple order, the Nambu-Goldstone bosons, the Higgs mode and vortex lattice  

E-Print Network (OSTI)

In the previous papers, we studied the bosonic t-J mode and derived an effective field theory, which is a kind of quantum XY model. The bosonic t-J model is expected to be realized by experiments of two-component cold atoms in an optical lattice. In this paper, we consider a similar XY model that describes phase diagram of the t-J model with a mass difference. Phase diagram and critical behavior of the quantum XY model are clarified by means of the Monte-Carlo simulations. Effective field theory that describes the phase structure and low-energy excitations of the quantum XY model is derived. Nambu-Goldstone bosons and the Higgs mode are studied by using the effective field theory and interesting findings are obtained for the system with multiple order, i.e., Bose-Einstein condensations and pseudo-spin symmetry. We also investigate physical properties of the quantum XY model in an effective magnetic field that is realized by rotating the optical lattice, etc. We show that low-energy states of the system strongly depend on the strength of the "magnetic field". For some specific strength of the magnetic field, vortex lattice forms and the correlation function of the bosons exhibits solid like behavior, which is a kind of Bose-Einstein condensation.

Y. Kuno; K. Suzuki; I. Ichinose

2013-06-10T23:59:59.000Z

329

THz Dynamic Nuclear Polarization NMR  

E-Print Network (OSTI)

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The ...

Nanni, Emilio Alessandro

330

Air entrainment by a plunging jet under intermittent vortex conditions  

E-Print Network (OSTI)

This fluid dynamic video entry to the 2011 APS-DFD Gallery of Fluid Motion details the transient evolution of the free surface surrounding the impact region of a low-viscosity laminar liquid jet as it enters a quiescent pool. The close-up images depict the destabilization and breakup of the annular air gap and the subsequent entrainment of bubbles into the bulk liquid.

Kim, Kevin Jin; Li, Kevin; Kiger, Ken T

2011-01-01T23:59:59.000Z

331

Tropical Cyclone Initialization with a Spherical High-Order Filter and an Idealized Three-Dimensional Bogus Vortex  

Science Conference Proceedings (OSTI)

A tropical cyclone initialization method with an idealized three-dimensional bogus vortex of an analytic empirical formula is presented for the track and intensity prediction. The procedure in the new method consists of four steps: the separation ...

In-Hyuk Kwon; Hyeong-Bin Cheong

2010-04-01T23:59:59.000Z

332

Observations of a Terrain-Forced Mesoscale Vortex and Canyon Drainage Flows along the Front Range of Colorado  

Science Conference Proceedings (OSTI)

Observations taken during the February 1991 Atmospheric Studies in Complex Terrain (ASCOT) Winter Validation Study are used to describe the wind field associated with a terrain-forced mesoscale vortex and thermally forced canyon drainage flows ...

David H. Levinson; Robert M. Banta

1995-07-01T23:59:59.000Z

333

Convection-Allowing and Convection-Parameterizing Ensemble Forecasts of a Mesoscale Convective Vortex and Associated Severe Weather Environment  

Science Conference Proceedings (OSTI)

An analysis of a regional severe weather outbreak that was related to a mesoscale convective vortex (MCV) is performed. The MCV-spawning mesoscale convection system (MCS) formed in northwest Kansas along the southern periphery of a large cutoff ...

Adam J. Clark; William A. Gallus Jr.; Ming Xue; Fanyou Kong

2010-08-01T23:59:59.000Z

334

A Spatial Filter Approach to Evaluating the Role of Convection on the Evolution of a Mesoscale Vortex  

Science Conference Proceedings (OSTI)

A new spatial filter is proposed that exploits a spectral gap in power between the convective scale and the system (“vortex”) scale during tropical cyclone (TC) genesis simulations. Using this spatial separation, this study analyzes idealized ...

Glenn A. Creighton; Robert E. Hart; Philip Cunningham

2013-07-01T23:59:59.000Z

335

Turbulence process domination under the combined forcings of wind stress, the Langmuir vortex force, and surface cooling  

Science Conference Proceedings (OSTI)

Turbulence in the ocean surface layer is generated by time-varying combinations of destabilizing surface buoyancy flux, wind stress forcing, and wave forcing through a vortex force associated with the surface wave field. Observations of time- and ...

A. E. Gargett; C. E. Grosch

336

Observations of a Squall Line and Its Near Environment Using High-Frequency Rawinsonde Launches during VORTEX2  

Science Conference Proceedings (OSTI)

Rawinsonde data were collected before and during passage of a squall line in Oklahoma on 15 May 2009 during the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2). Nine soundings were released within 3 h, allowing ...

George H. Bryan; Matthew D. Parker

2010-11-01T23:59:59.000Z

337

Variation in the Stratospheric Aerosol Associated with the North Cyclonic Polar Vortex as Measured by the SAM II Satellite Sensor  

Science Conference Proceedings (OSTI)

Aerosol extinction data obtained by the Stratospheric Aerosol Measurement II (SAM II) satellite instrument during the 1979/80 Northern Hemisphere winter season have been analyzed in relation to the cyclonic polar vortex. A synoptic approach has ...

G. S. Kent; C. R. Trepte; U. O. Farrukh; M. P. McCormick

1985-07-01T23:59:59.000Z

338

Dynamics of quantum spin liquid and spin solid phases in IPA-CuCl3 under an applied magnetic field studied with neutron scattering  

SciTech Connect

Inelastic and elastic neutron scattering is used to study spin correlations in the quasi-one-dimensional quantum antiferromagnet IPA-CuCl3 in strong applied magnetic fields. A condensation of magnons and commensurate transverse long-range ordering is observe at a critical field Hc=9.5 T. The field dependencies of the energies and polarizations of all magnon branches are investigated both below and above the transition point. Their dispersion is measured across the entire one-dimensional Brillouin zone in magnetic fields up to 14 T. The critical wave vector of magnon spectrum truncation Masuda et al., Phys. Rev. Lett. 96, 047210 2006 is found to shift from hc0,35 at HHC to hc=0.25 for HHC. A drastic reduction of magnon bandwidths in the ordered phase Garlea et al., Phys. Rev. Lett. 98, 167202 2007 is observed and studied in detail. New features of the spectrum, presumably related to this bandwidth collapse, are observed just above the transition field.

Zheludev, Andrey I [ORNL; Garlea, Vasile O [ORNL; Masuda, T. [Yokohama City University, Japan; Manaka, H. [Kagoshima University, Kagoshima JAPAN; Regnault, L.-P. [CEA, Grenoble, France; Ressouche, E. [CEA, Grenoble, France; Grenier, B. [CEA, Grenoble, France; Chung, J.-H. [National Institute of Standards and Technology (NIST); Qiu, Y. [National Institute of Standards and Technology (NIST); Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Kiefer, K. [Hahn-Meitner Institut, Berlin, Germany; Boehm, Martin [Institut Laue-Langevin (ILL)

2007-01-01T23:59:59.000Z

339

Photo of the Week: Controlling Chaos with Magnetic Fields | Department of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Controlling Chaos with Magnetic Fields Controlling Chaos with Magnetic Fields Photo of the Week: Controlling Chaos with Magnetic Fields January 18, 2013 - 11:26am Addthis This artistic rendition of "spin vortices" illustrates tiny magnetic vortices that spin according to the polarization of each disk's vortex core. At Argonne National Laboratory, scientists are using alternating magnetic fields to control the behavior of these spin vortices, which are small dots made of iron and nickel. The experiments will help to create new, more efficient magnetic devices -- like the random access memory (RAM) in the device you are using to look at this very photo. Learn more about spin vortices. | Photo courtesy of Sander Munster, Dresden University of Technology.

340

Brett Parker | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

Brett Parker Brett Parker Recent Presentations "BNL Direct Wind Magnets," (pdf) presentation dedicated to the memory of Pat Thompson given at the 22nd Magnet Technology Conference (MT22), September 11 - 16, 2011, Marseille, France A Review of BNL Direct-Wind Superconducting IR Magnet Experience, (pdf) presented at the 30th Advanced ICFA Beam Dynamics Workshop on High Luminosity e+e- Collisions, October 13 - 16, 2003, Stanford, California The Serpentine Coil Design for BEPC-II Superconducting IR Magnets, (pdf) presented at the "Mini-Workshop on BEPC-II IR Design", January 12 - 16, 2004, Beijing, P.R. China Ma nufacture of a Superconducting Octupole Magnet for the ALPHA Experiment at CERN using the Direct Wind Machine Presentations Prior to 2004 Superconducting Final Focus Magnet Issues (pdf), presented at

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Heat transfer in a two-pass internally ribbed turbine blade coolant channel with cylindrical vortex generators  

DOE Green Energy (OSTI)

The effect of vortex generators on the mass (heat) transfer from the ribbed passage of a two pass turbine blade coolant channel is investigated with the intent of optimizing the vortex generator geometry so that significant enhancements in mass/heat transfer can be achieved. In the experimental configuration considered, ribs are mounted on two opposite walls; all four walls along each pass are active and have mass transfer from their surfaces but the ribs are non-participating. Mass transfer measurements, in the form of Sherwood number ratios, are made along the centerline and in selected inter-rib modules. Results are presented for Reynolds number in the range of 5,000 to 40,000, pitch to rib height ratios of 10.5 and 21, and vortex generator-rib spacing to rib height ratios of 0.55, and 1.5. Centerline and spanwise averaged Sherwood number ratios are presented along with contours of the Sherwood number ratios. Results indicate that the vortex generators induce substantial increases in the local mass transfer rates, particularly along the side walls, and modest increases in the average mass transfer rates. The vortex generators have the effect of making the inter-rib profiles along the ribbed walls more uniform. Along the side walls, horse-shoe vortices that characterize the vortex generator wake are associated with significant mass transfer enhancements. The wake effects and the levels of enhancement decrease somewhat with increasing Reynolds number and decreasing pitch.

Hibbs, R.; Acharya, S.; Chen, Y. [Louisiana State Univ., Baton Rouge, LA (United States)] [and others

1995-12-31T23:59:59.000Z

342

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes II. Stationary Black Holes  

E-Print Network (OSTI)

When one splits spacetime into space plus time, the Weyl curvature tensor (which equals the Riemann tensor in vacuum) splits into two spatial, symmetric, traceless tensors: the tidal field $E$, which produces tidal forces, and the frame-drag field $B$, which produces differential frame dragging. In recent papers, we and colleagues have introduced ways to visualize these two fields: tidal tendex lines (integral curves of the three eigenvector fields of $E$) and their tendicities (eigenvalues of these eigenvector fields); and the corresponding entities for the frame-drag field: frame-drag vortex lines and their vorticities. These entities fully characterize the vacuum Riemann tensor. In this paper, we compute and depict the tendex and vortex lines, and their tendicities and vorticities, outside the horizons of stationary (Schwarzschild and Kerr) black holes; and we introduce and depict the black holes' horizon tendicity and vorticity (the normal-normal components of $E$ and $B$ on the horizon). For Schwarzschil...

Zhang, Fan; Nichols, David A; Chen, Yanbei; Lovelace, Geoffrey; Matthews, Keith D; Owen, Robert; Thorne, Kip S

2012-01-01T23:59:59.000Z

343

Magnetic Properties of New Layered Triangular-lattice Compound ...  

Science Conference Proceedings (OSTI)

Abstract Scope, We report on the static and dynamic magnetic properties of ..... Relationship Between Volatile Functionality and Explosivity of Pulverized Coal.

344

Numerical evidence of breaking of vortex lines in an ideal fluid  

E-Print Network (OSTI)

Emergence of singularity of vorticity at a single point, not related to any symmetry of the initial distribution, has been demonstrated numerically for the first time. Behavior of the maximum of vorticity near the point of collapse closely follows the dependence 1/(t0-t), where t0 is the time of collapse. This agrees with the interpretation of collapse in an ideal incompressible fluid as of the process of vortex lines breaking.

Kuznetsov, E A; Zheligovsky, V A

2001-01-01T23:59:59.000Z

345

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes II. Stationary Black Holes  

E-Print Network (OSTI)

When one splits spacetime into space plus time, the Weyl curvature tensor (which equals the Riemann tensor in vacuum) splits into two spatial, symmetric, traceless tensors: the tidal field $E$, which produces tidal forces, and the frame-drag field $B$, which produces differential frame dragging. In recent papers, we and colleagues have introduced ways to visualize these two fields: tidal tendex lines (integral curves of the three eigenvector fields of $E$) and their tendicities (eigenvalues of these eigenvector fields); and the corresponding entities for the frame-drag field: frame-drag vortex lines and their vorticities. These entities fully characterize the vacuum Riemann tensor. In this paper, we compute and depict the tendex and vortex lines, and their tendicities and vorticities, outside the horizons of stationary (Schwarzschild and Kerr) black holes; and we introduce and depict the black holes' horizon tendicity and vorticity (the normal-normal components of $E$ and $B$ on the horizon). For Schwarzschild and Kerr black holes, the horizon tendicity is proportional to the horizon's intrinsic scalar curvature, and the horizon vorticity is proportional to an extrinsic scalar curvature. We show that, for horizon-penetrating time slices, all these entities ($E$, $B$, the tendex lines and vortex lines, the lines' tendicities and vorticities, and the horizon tendicities and vorticities) are affected only weakly by changes of slicing and changes of spatial coordinates, within those slicing and coordinate choices that are commonly used for black holes. [Abstract is abbreviated.

Fan Zhang; Aaron Zimmerman; David A. Nichols; Yanbei Chen; Geoffrey Lovelace; Keith D. Matthews; Robert Owen; Kip S. Thorne

2012-08-15T23:59:59.000Z

346

Magnetic Storms  

Science Conference Proceedings (OSTI)

... magnetic reversal. As there is no predictive science of geomagnetism, we currently lack even simple forecasts. Our scientific ...

2010-10-05T23:59:59.000Z

347

Magnetic Imaging  

Science Conference Proceedings (OSTI)

... data-storage and permanent magnets with increased energy products, in ... Optimization of future materials, including improved yields, requires an ...

2012-10-02T23:59:59.000Z

348

Magnetic Properties  

Science Conference Proceedings (OSTI)

...Since the discovery of high-temperature superconductors in 1986 (Ref 10), the demonstration of magnetic flux exclusion

349

Synthesis and magnetic reversal of bi-conical Ni nanostructures  

SciTech Connect

Template synthesis in polyethylene terephthalate (PET) membranes has been used to grow hour glass shaped nickel nanowires with a constriction in the range of tens of nanometers at the center. Anisotropic magnetoresistance measurements have been performed on a single nanowire to follow magnetization reversal of the structure. The results are explained via 3D micromagnetic simulations showing the appearance of a complex vortex state close to the constriction whose propagation depends on the angle between the cone axis and the applied field. The interest of this original growth process for spintronics is discussed.

Biziere, N. [Laboratoire des Solides Irradies, CEA/CNRS/Ecole Polytechnique, Ecole Polytechnique, 91128 Palaiseau Cedex (France); CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France); Lassalle Ballier, R.; Viret, M. [Service de Physique de l' Etat Condense, DSM/IRAMIS/SPEC, CEA Saclay URA CNRS 2464, 91191 Gif-Sur-Yvette Cedex (France); Clochard, M. C.; Wade, T. L.; Wegrowe, J. E. [Laboratoire des Solides Irradies, CEA/CNRS/Ecole Polytechnique, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Balanzat, E. [CIMAP, Unite Mixte CEA-CNRS-ENSICAEN, F-14070 Caen Cedex 5 (France)

2011-09-15T23:59:59.000Z

350

Direct observation of a magnetic Bose glass  

Science Conference Proceedings (OSTI)

A Bose glass is a novel state of matter that emerges in systems of interacting bosons in the presence of quenched disorder. At sufficiently low temperatures, disorder-free bosons are subject to so-called Bose-Einstein condensation (BEC). BEC can involve atoms in liquid 4He, laser-cooled ions in magnetic traps,2 Cooper pairs in superconductors, or magnons in magnetic systems. Due to peculiarities of Bose statistics, particles lose their individuality and occupy a unique quantum-mechanical state. The wave function of this condensate establishes long-range quantum phase coherence across a macroscopic sample. This, in turn, spawns unique quantum phenomena such as superfluity,5 Josephson effect6 and vortex matter. For repulsive bosons, quenched disorder disrupts the condensate and interferes with phase coherence. The result is a peculiar glassy state with only short-range phase correlations. While some experimental evidence of this was found in ultracold atoms,9 novel high-temperature superconductors,10 and quantum magnets,11, 12 none of the studies were direct. The key characteristic, namely the wave function of the condensate disrupted by disorder on the microscopic scale, remained inaccessible. Hereby we report a direct neutron diffraction observation of short range correlations of the BEC order parameter in a magnetic Bose glass. This phase is realized in the quantum spin ladder compound IPA-Cu(Cl0.96Br0.04)3, where disorder is induced by random chemical substitution.

Hong, Tao [ORNL; Zheludev, Andrey I [ORNL; Manaka, H. [Kagoshima University, Kagoshima JAPAN; Regnault, L.-P. [CEA, Grenoble, France

2010-01-01T23:59:59.000Z

351

From Fundamentals to Nanoscale Dynamics  

Science Conference Proceedings (OSTI)

This text book gives a comprehensive account of magnetism, one of the oldest yet most vibrant fields of physics. It spans the historical development, the physical foundations and the continuing research underlying the subject. The book covers both the classical and quantum mechanical aspects of magnetism and novel experimental techniques. Perhaps uniquely, it discusses spin transport and magnetization dynamics phenomena associated with atomically and spin engineered nano-structures against the backdrop of spintronics and magnetic storage and memory applications. The book is for students, and serves as a reference for scientists in academia and research laboratories.

Stohr, J.; Siegmann, H.C.

2007-08-08T23:59:59.000Z

352

Accuracy of magnetic energy computations  

E-Print Network (OSTI)

For magnetically driven events, the magnetic energy of the system is the prime energy reservoir that fuels the dynamical evolution. In the solar context, the free energy is one of the main indicators used in space weather forecasts to predict the eruptivity of active regions. A trustworthy estimation of the magnetic energy is therefore needed in three-dimensional models of the solar atmosphere, eg in coronal fields reconstructions or numerical simulations. The expression of the energy of a system as the sum of its potential energy and its free energy (Thomson's theorem) is strictly valid when the magnetic field is exactly solenoidal. For numerical realizations on a discrete grid, this property may be only approximately fulfilled. We show that the imperfect solenoidality induces terms in the energy that can lead to misinterpreting the amount of free energy present in a magnetic configuration. We consider a decomposition of the energy in solenoidal and nonsolenoidal parts which allows the unambiguous estimation...

Valori, G; Pariat, E; Masson, S

2013-01-01T23:59:59.000Z

353

Magnetic Materials  

Science Conference Proceedings (OSTI)

Oct 27, 2009 ... Extreme magnetic fields (>2 tesla), especially when combined with temperature, are being shown to revolutionize materials processing and ...

354

Principles of equilibrium statistical mechanics revisited: The idea of vortex energy  

E-Print Network (OSTI)

We show that the law of energy conservation with the fact of matter stability imply the existence of energy complementary to that given by the function of states of interacting systems and treated, with the environment, the function of states of interacting extended systems. The complementary energy, we called it vortex, is integral, not quantized, and causes trends contrary to that prescribed by equilibrium statistical mechanics. We formulate its principles and theorems, and question traditional insights in thermodynamics, entropy law, phase transitions, persistent currents, Brownian motion.

V. E. Shapiro

2013-05-21T23:59:59.000Z

355

Interconversion of dark soliton and Josephson vortex in a quasi-1D long Bose Josephson junction  

E-Print Network (OSTI)

Dark soliton (DS) and Josephson vortex (JV) in quasi-1D long Bose Josephson junction (BJJ) can be interconverted by tuning Josephson coupling. Rates of the interconversion as well as of the thermally activated phase-slip effect, resulting in the JV switching its vorticity, have been evaluated. The role of quantum phase-slip in creating superposition of JVs with opposite vorticities as a qubit is discussed as well. Utilization of the JV for controlled and coherent transfer of atomic Bose-Einstein condensate (BEC) is suggested.

V. M. Kaurov; A. B. Kuklov

2003-12-03T23:59:59.000Z

356

Superconducting Magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

Mit Hilfe der Technologie supraleitender Magnete lassen sich in Mit Hilfe der Technologie supraleitender Magnete lassen sich in Ringbeschleunigern höhere Energien erreichen. Weil supraleitende Spulen keinen elektrischen Widerstand aufweisen, können damit stärkere Magnetfelder erzeugt werden. In normal leitenden Elektromagneten wird - wegen des elektrischen Widerstands der Drähte - die Spule aufgeheizt. Auf diese Weise geht sehr viel Energie in Form von Wärme verloren, was die Energiekosten dieser Magnete in die Höhe treibt. Supraleitende Spulen erlauben es, Magnete grosser Feldstärke unter günstigen Bedingungen zu betreiben und damit die Energiekosten zu senken. Durch den Einbau supraleitender Spulen in den Ringbeschleuniger von Fermilab konnte dessen Energie verdoppelt werden.Auch der im Bau befindliche "Large Hadron Collider" am CERN wird supraleitende Magnete

357

Magnetic nanotubes  

DOE Patents (OSTI)

A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

Matsui, Hiroshi (Glen Rock, NJ); Matsunaga, Tadashi (Tokyo, JP)

2010-11-16T23:59:59.000Z

358

Combustion of pulverized coal in vortex structures. Final report, October 1, 1993--December 31, 1995  

Science Conference Proceedings (OSTI)

The objectives of the project were: (i) to understand the effects of heating one of the streams on the characteristics of shear layers, (ii) to investigate the changes in the characteristics of large scale vortex structures in the shear layer caused by the introduction of inert solid particles in one of the feed streams; (iii) to understand the effects of pyrolyzing solids on the shear layer behavior; and (iv) to study the effects of combustion of particles and their pyrolysis products on the shear layer structure, heat release rate, and pollutant emission characteristics. An experimental facility for generating two-dimensional shear layers containing vortex structures has been designed and fabricated. The experimental facility is essentially a low speed wind tunnel designed to (i) provide two gas streams, initially with uniform velocity profiles and isotropic turbulence, mixing at the end of a splitter plate, (ii) introduce vorticity by passively perturbing one of the streams, (iii) allow heating of one of the streams to temperatures high enough to cause pyrolysis of coal particles, and (iv) provide a natural gas flame in one of the streams to result in ignition and burning of coal particles.

Gollahalli, S.R.; Butuk, N.

1996-03-01T23:59:59.000Z

359

Nuclear Magnetic Resonance Laboratory  

Science Conference Proceedings (OSTI)

Nuclear Magnetic Resonance Laboratory. ... A 600 MHz Nuclear Magnetic Resonance Spectrometer. Analytical Data Compilation Reference Materials. ...

2012-10-01T23:59:59.000Z

360

Soft magnetic lithography and giant magnetoresistance in superconducting/ferromagnetic hybrids.  

Science Conference Proceedings (OSTI)

We demonstrate an approach to create a tunable pinning potential in a superconducting/ferromagnetic (SC/FM) hybrid, allowing the switching of their electronic properties through the application of a small magnetic field. Using direct magneto-optical imaging, macroscopic transport, and magnetic measurements, we show that the alignment of stripe domains in the ferromagnet provides a remarkable directionality for the superconducting vortex motion. An analysis of the anisotropic flux motion demonstrates a substantial critical current anisotropy in the superconductor. The possibility of aligning stable lattices of stripe domains in select directions using in-plane magnetic fields allows the realization of soft magnetic lithography for efficient manipulation of supercurrent flow in SC/FM bilayers. Furthermore, in our samples we observed a pronounced magnetoresistance effect yielding 4 orders of magnitude resistivity change in a few millitesla in-plane field.

Vlasko-Vlasov, V.; Welp, U.; Imre, A.; Rosenmann, D.; Pearson, J.; Kwok, W. K.

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Cyclotron Resonances in Electron Cloud Dynamics  

Science Conference Proceedings (OSTI)

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lbstripes" found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The existence of the resonances has been confirmed in experiments at PEP-II. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations and experimental observations, the reason for the bunch-length dependence, and details of the dynamics are discussed here.

Celata, C. M.; Furman, Miguel A.; Vay, J.-L.; Ng, J. S.T.; Grote, D. P.; Pivi, M. T. F.; Wang, L. F.

2009-04-29T23:59:59.000Z

362

Cyclotron Resonances in Electron Cloud Dynamics  

Science Conference Proceedings (OSTI)

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where l{sub b} stripes' of multipactoring found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations, the reason for the bunch-length dependence, and details of the dynamics will be discussed.

Celata, C M; Furman, M A; Vay, J L; Grote, D P; Ng, J T; Pivi, M F; Wang, L F

2009-05-05T23:59:59.000Z

363

Effects of Magnetic Field on the Turbulent Wake of a Cylinder in MHD Channel Flow  

SciTech Connect

Results from a free-surface MHD flow experiment are presented detailing the modi cation of vortices in the wake of a circular cylinder with its axis parallel to the applied magnetic fi eld. Experiments were performed with a Reynolds number near Re ~ 104 as the interaction parameter, N = |j x#2; B| / |? (? ? ?), was increased through unity. By concurrently sampling the downstream fluid velocity at sixteen cross-stream locations in the wake, it was possible to extract an ensemble of azimuthal velocity profi les as a function of radius for vortices shed by the cylinder at varying strengths of magnetic field. Results indicate a signi cant change in vortex radius and rotation as N is increased. The lack of deviations from the vortex velocity pro file at high magnetic fi elds suggests the absence of small-scale turbulent features. By sampling the wake at three locations downstream in subsequent experiments, the decay of the vortices was examined and the effective viscosity was found to decrease as N-049±0.4. This reduction in effective viscosity is due to the modi cation of the small-scale eddies by the magnetic fi eld. The slope of the energy spectrum was observed to change from a k-1.8 power-law at low N to a k-3.5 power-law for N > 1. Together, these results suggest the flow smoothly transitioned to a quasi-two-dimensional state in the range 0 < N < 1.

John Rhoads, Eric Edlund and Hantao Ji

2013-04-17T23:59:59.000Z

364

Learning About Magnets!  

NLE Websites -- All DOE Office Websites (Extended Search)

the the National High Magnetic Field Laboratory Learning About Name A magnet is a material or object that creates a magnetic fi eld. This fi eld is invisible, but it creates a force that can "attract" or "repel" other magnets and magnetic materials, like iron or nickel. What is a Magnet? This bar magnet is a permanent magnet. Permanent magnets can be found in the Earth as rocks and metals. Magnets have

365

Tracking Waves and Vortex Nucleation in Excitable Systems with Anomalous Dispersion N. Manz, C.T. Hamik, and O. Steinbock  

E-Print Network (OSTI)

Tracking Waves and Vortex Nucleation in Excitable Systems with Anomalous Dispersion N. Manz, C of the underlying anomalous dispersion relation. DOI: 10.1103/PhysRevLett.92.248301 PACS numbers: 82.40.Ck, 05.45.­a and physicochemical systems [1,2]. Important examples include neuronal and cardiac tissue as well as gas discharge

Steinbock, Oliver

366

Optimizing the WSR-88D Mesocyclone/Tornadic Vortex Signature Algorithm Using WATADS—A Case Study  

Science Conference Proceedings (OSTI)

A tornado outbreak occurred in east-central Minnesota around 0000 UTC 22 July 1995, within 80 km of the KMPX WSR-88D, at the Minneapolis–Chanhassen Weather Service Forecast Office (WSFO). The WSR-88D Mesocyclone/Tornadic Vortex Signature ...

Gregory A. Tipton; Eric D. Howieson; John A. Margraf; Robert R. Lee

1998-06-01T23:59:59.000Z

367

ECMWF Analyses and Forecasts of Stratospheric Winter Polar Vortex Breakup: September 2002 in the Southern Hemisphere and Related Events  

Science Conference Proceedings (OSTI)

Breakup of the polar stratospheric vortex in the Northern Hemisphere is an event that is known to be predictable for up to a week or so ahead. This is illustrated using data from the 45-yr ECMWF Re-Analysis (ERA-40) for the sudden warmings of ...

Adrian Simmons; Mariano Hortal; Graeme Kelly; Anthony McNally; Agathe Untch; Sakari Uppala

2005-03-01T23:59:59.000Z

368

Soliton trains and vortex streets as a form of Cerenkov radiation in trapped Bose-Einstein condensates  

Science Conference Proceedings (OSTI)

We numerically study the nucleation of gray solitons and vortex-antivortex pairs created by a moving impurity in, respectively, 1D and 2D Bose-Einstein condensates (BECs) confined by a parabolic potential. The simulations emulate the motion of a localized ... Keywords: Bose-Einstein condensation, Matter waves, Nucleation, Solitons, Vortices

R. Carretero-González; P. G. Kevrekidis; D. J. Frantzeskakis; B. A. Malomed; S. Nandi; A. R. Bishop

2007-03-01T23:59:59.000Z

369

Vortex Rossby Waves in a Numerically Simulated Tropical Cyclone. Part II: The Role in Tropical Cyclone Structure and Intensity Changes  

Science Conference Proceedings (OSTI)

In Part I, the author analyzed the asymmetric structure in the inner core of a numerically simulated tropical cyclone and found that the asymmetry near the eyewall in the mid–lower troposphere is dominated by wavenumber-1 and -2 vortex Rossby ...

Yuqing Wang

2002-04-01T23:59:59.000Z

370

Neutrino magnetic moment in a magnetized plasma  

E-Print Network (OSTI)

The contribution of a magnetized plasma to the neutrino magnetic moment is calculated. It is shown that only part of the additional neutrino energy in magnetized plasma connecting with its spin and magnetic field strength defines the neutrino magnetic moment. It is found that the presence of magnetized plasma does not lead to the considerable increase of the neutrino magnetic moment in contrast to the results presented in literature previously.

N. V. Mikheev; E. N. Narynskaya

2010-11-08T23:59:59.000Z

371

Characterization of waste tire incineration in a prototype vortexing fluidized bed combustor  

Science Conference Proceedings (OSTI)

To investigate the characteristics of incinerating waste tires in a prototype vortexing fluidized bed combustor, performance tests were conducted with two sizes of waste tire fragments. The results from the combustion experiments showed that increasing the tire particle size caused less of the volatiles to be burned in the freeboard and thus lowered freeboard temperature. Uniform bed temperature could also be achieved by increasing the size of the tire particles. Variations in the secondary and tertiary air rates simultaneously affected the swirling intensity and the axial gas velocity in the freeboard, and thus resulted in the variations in ash elutriation, combustion efficiency, and pollutant emissions for the combustion systems. 21 refs., 17 figs., 1 tab.

Teng, H.; Chyang, C.S.; Shang, S.H.; Ho, J.A. [Chung Yuan Christian Univ., Chung-Li (Taiwan, Province of China)

1997-01-01T23:59:59.000Z

372

Effects of surface roughness and vortex generators on the LS(1)-0417MOD airfoil  

DOE Green Energy (OSTI)

An 18-inch constant-chord model of the LS(l)-0417MOD airfoil section was tested under two dimensional steady state conditions ate University 7{times}10 Subsonic Wind Tunnel. The objective was to document section lift and moment characteristics model and air flow conditions. Surface pressure data was acquired at {minus}60{degrees} through + 230{degrees} geometric angles of attack, at a nominal 1 million Reynolds number. Cases with and without leading edge grit roughness were investigated. The leading edge mulated blade conditions in the field. Additionally, surface pressure data were acquired for Reynolds numbers of 1.5 and 2.0 million, with and without leading edge grit roughness; the angle of attack was limited to a {minus}20{degrees} to 40{degrees} range. In general, results showed lift curve slope sensitivities to Reynolds number and roughness. The maximum lift coefficient was reduced as much as 29% by leading edge roughness. Moment coefficient showed little sensitivity to roughness beyond 50{degrees} angle of attack, but the expected decambering effect of a thicker boundary layer with roughness did show at lower angles. Tests were also conducted with vortex generators located at the 30% chord location on the upper surface only, at 1 and 1.5 million Reynolds numbers, with and without leading edge grit roughness. In general, with leading edge grit roughness applied, the vortex generators restored 85 percent of the baseline level of maximum lift coefficient but with a more sudden stall break and at a higher angle of attack than the baseline.

Reuss, R.L.; Hoffman, M.J.; Gregorek, G.M. [Ohio State Univ., Columbus, OH (United States)

1995-12-01T23:59:59.000Z

373

SUPERCONDUCTING MAGNETIC ENERGY STORAGE  

E-Print Network (OSTI)

Scale Superconducting Magnetic Energy Storage Plant", IEEEfor SlIperconducting Magnetic Energy Storage Unit", inSuperconducting Magnetic Energy Storage Plant, Advances in

Hassenzahl, W.

2011-01-01T23:59:59.000Z

374

Magnetization Characterization Laboratory  

Science Conference Proceedings (OSTI)

... use of magnetic materials for motors, generators, transformers ... all depend on the specific magnetic characteristics of ... For example, a magnet used in ...

2012-10-23T23:59:59.000Z

375

MAGNETIC GRID  

DOE Patents (OSTI)

An electronic grid is designed employing magnetic forces for controlling the passage of charged particles. The grid is particularly applicable to use in gas-filled tubes such as ignitrons. thyratrons, etc., since the magnetic grid action is impartial to the polarity of the charged particles and, accordingly. the sheath effects encountered with electrostatic grids are not present. The grid comprises a conductor having sections spaced apart and extending in substantially opposite directions in the same plane, the ends of the conductor being adapted for connection to a current source.

Post, R.F.

1960-08-01T23:59:59.000Z

376

Satellite Data Assimilation in Numerical Weather Prediction Models. Part II: Uses of Rain-Affected Radiances from Microwave Observations for Hurricane Vortex Analysis  

Science Conference Proceedings (OSTI)

A hybrid variational scheme (HVAR) is developed to produce the vortex analysis associated with tropical storms. This scheme allows for direct assimilation of rain-affected radiances from satellite microwave instruments. In the HVAR, the ...

Fuzhong Weng; Tong Zhu; Banghua Yan

2007-11-01T23:59:59.000Z

377

Questions about Magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

off just the north (or just the south) end of a magnet? Are magnets stronger than gravity? Hold a magnet in the air. Place a nail against it. The magnet holds the nail up...

378

Knot energy in unstretching ergodic magnetic flux tubes  

E-Print Network (OSTI)

Recently Titov et al [ApJ \\textbf{693},(2009) and ApJ (2007)] have made use of a covariant model to investigate magnetic reconnection of astrophysical plasmas. Earlier R Ricca [Phys Rev A (1991)] has used another covariant formalism, to investigated vortex filaments and solitons. This formalism, called Ricci rotation coefficients (RRC), is applied here, to the Chui and Moffatt [PRSA (1995)] knotted magnetic flux tube (MFT) Riemann metric in the case of vanishing stretch. It is shown that, the vanishing of some components of the (RRC) leads to unstretching knotted tubes. Computing of magnetic knot energy in terms of the RCC, shows that, uniform, unstretching and constant cross-section tubes leads to a marginal dynamo action over magnetic surfaces. Recent investigation on the role of stretching in plasma dynamo action showed that in diffusive media [Phys Plasma \\textbf{14} (2008)], unstretching unknotted tubes would not support fast dynamo action. This result was generalized here to much more general knotted MF...

de Andrade, Garcia

2009-01-01T23:59:59.000Z

379

magnets2  

NLE Websites -- All DOE Office Websites (Extended Search)

II II Painless Physics Articles BEAM COOLING August 2, 1996 By Leila Belkora, Office of Public Affairs ACCELERATION August 16, 1996 By Dave Finley, Accelerator Division Head RF August 30, 1996 By Pat Colestock, Accelerator Division FIXED TARGET PHYSICS September 20, 1996 By Peter H. Garbincius, Physics Section FIXED TARGET PHYSICS PART DEUX October 16, 1996 By Peter H. Garbincius, Physics Section and Leila Belkora, Office of Public Affaris CROSS SECTION November 1, 1996 By Doreen Wackeroth, Theoretical Physics Edited by Leila Belkora, Office of Public Affaris MAGNETS PART I November 15, 1996 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs MAGNETS PART II January 10, 1997 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs

380

On the unsteady-motion theory of magnetic forces for maglev  

DOE Green Energy (OSTI)

Motion-dependent magnetic forces are the key elements in the study of magnetically levitated vehicle (maglev) system dynamics. This paper presents an experimental and analytical study that will enhance their understanding of the role of unsteady-motion-dependent magnetic forces and demonstrate an experimental technique that can be used to measure those unsteady magnetic forces directly. The experimental technique provides a useful tool to measure motion-dependent magnetic forces for the prediction and control of maglev systems.

Chen, S.S.; Zhu, S.; Cai, Y. [Argonne National Lab., IL (United States). Energy Technology Div.

1996-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Reduced gravity rankine cycle design and optimization with passive vortex phase separation  

E-Print Network (OSTI)

Liquid-metal Rankine power conversion systems (PCS) coupled with a fission reactor remain an attractive option for space power applications because system specific power and efficiency is very favorable for plant designs of 100 kW(e) or higher. Potential drawbacks to the technology in a reduced gravity environment include two-phase fluid management processes such as liquid-vapor phase separation. The most critical location for phase separation is at the boiler exit where only vapor must be sent to the turbine because blade erosion occurs from high velocity liquid droplets entrained by vapor flow. Previous studies have proposed that rotary separators be used to separate the liquid and vapor from a two phase mixture. However these devices have complex turbo machinery, require kilowatts of power and are untested for high vapor flow conditions. The Interphase Transport Phenomena (ITP) laboratory has developed a low-power, passive microgravity vortex phase separator (MVS) which has already proven to be an essential component of two-phase systems operating in low gravity environments. This thesis presents results from flight experiments where a Rankine cycle was operated in a reduced gravity environment for the first time by utilizing the MVS for liquid and vapor phase separation. The MVS was able to operate under saturated conditions and adjust to system transients as it would in the Rankine cycle by controlling the amount of liquid and vapor within the device. A new model is developed for the MVS to predict separation performance at high vapor flow conditions for sizing the separator at the boiler, condenser, and turbine locations within the cycle by using a volume limiting method. This model factors in the following separator characteristics: mass, pumping power, and available buffer volume for system transients. The study is concluded with overall Rankine efficiency and performance changes due to adding vortex phase separation and a schematic of the Rankine cycle with the integration of the MVS is presented. The results from this thesis indicate the thermal to electric efficiency and specific mass of the cycle can be improved by using the MVS to separate the two phases instead of a rotary separator.

Supak, Kevin Robert

2007-12-01T23:59:59.000Z

382

Reduced gravity Rankine cycle system design and optimization study with passive vortex phase separation  

E-Print Network (OSTI)

Liquid-metal Rankine power conversion systems (PCS) coupled with a fission reactor remain an attractive option for space power applications because system specific power and efficiency is very favorable for plant designs of 100 kW(e) or higher. Potential drawbacks to the technology in a reduced gravity environment include two-phase fluid management processes such as liquid-vapor phase separation. The most critical location for phase separation is at the boiler exit where only vapor must be sent to the turbine because blade erosion occurs from high velocity liquid droplets entrained by vapor flow. Previous studies have proposed that rotary separators be used to separate the liquid and vapor from a two phase mixture. However these devices have complex turbo machinery, require kilowatts of power and are untested for high vapor flow conditions. The Interphase Transport Phenomena (ITP) laboratory has developed a low-power, passive microgravity vortex phase separator (MVS) which has already proven to be an essential component of two-phase systems operating in low gravity environments. This thesis presents results from flight experiments where a Rankine cycle was operated in a reduced gravity environment for the first time by utilizing the MVS for liquid and vapor phase separation. The MVS was able to operate under saturated conditions and adjust to system transients as it would in the Rankine cycle by controlling the amount of liquid and vapor within the device. A new model is developed for the MVS to predict separation performance at high vapor flow conditions for sizing the separator at the boiler, condenser, and turbine locations within the cycle by using a volume limiting method. This model factors in the following separator characteristics: mass, pumping power, and available buffer volume for system transients. The study is concluded with overall Rankine efficiency and performance changes due to adding vortex phase separation and a schematic of the Rankine cycle with the integration of the MVS is presented. The results from this thesis indicate the thermal to electric efficiency and specific mass of the cycle can be improved by using the MVS to separate the two phases instead of a rotary separator.

Supak, Kevin Robert

2007-12-01T23:59:59.000Z

383

Magnetic properties of the nucleon in a uniform background field  

E-Print Network (OSTI)

We present results for the magnetic moment and magnetic polarisability of the neutron and the magnetic moment of the proton. These results are calculated using the uniform background field method on 32^3 x 64 dynamical QCD lattices provided by the PACS-CS collaboration as part of the ILDG. We use a uniform background magnetic field quantised by the periodic spatial volume. We investigate ways to improve the effective energy plots used to calculate magnetic polarisabilities, including the use of correlation matrix techniques with various source smearings.

Thomas Primer; Waseem Kamleh; Derek Leinweber; Matthias Burkardt

2013-07-05T23:59:59.000Z

384

Solid-State Dynamic Nuclear Polarization at 263 GHz: Spectrometer Design and Experimental Results  

E-Print Network (OSTI)

Dynamic Nuclear Polarization (DNP) experiments transfer polarization from electron spins to nuclear spins with microwave irradiation of the electron spins for enhanced sensitivity in nuclear magnetic resonance (NMR) ...

Rosay, Melanie

385

Effects of surface roughness and vortex generators on the NACA 4415 airfoil  

DOE Green Energy (OSTI)

Wind turbines in the field can be subjected to many and varying wind conditions, including high winds with rotor locked or with yaw excursions. In some cases the rotor blades may be subjected to unusually large angles of attack that possibly result in unexpected loads and deflections. To better understand loadings at unusual angles of attack, a wind tunnel test was performed. An 18-inch constant chord model of the NACA 4415 airfoil section was tested under two dimensional steady state conditions in the Ohio State University Aeronautical and Astronautical Research Laboratory (OSU/AARL) 7 x 10 Subsonic Wind Tunnel (7 x 10). The objective of these tests was to document section lift and moment characteristics under various model and air flow conditions. These included a normal angle of attack range of {minus}20{degree} to +40{degree}, an extended angle of attack range of {minus}60{degree} to +230{degree}, applications of leading edge grit roughness (LEGR), and use of vortex generators (VGs), all at chord Reynolds numbers as high as possible for the particular model configuration. To realistically satisfy these conditions the 7 x 10 offered a tunnel-height-to-model-chord ratio of 6.7, suggesting low interference effects even at the relatively high lift and drag conditions expected during the test. Significantly, it also provided chord Reynolds numbers up to 2.0 million. 167 figs., 13 tabs.

Reuss, R.L.; Hoffman, M.J.; Gregorek, G.M. [Ohio State Univ., Columbus, OH (United States)

1995-12-01T23:59:59.000Z

386

Winding numbers and scaling tilts from random vortex-antivortex pairs  

E-Print Network (OSTI)

I show that random distributions of vortex-antivortex pairs (rather than of individual vortices) lead to scaling of typical winding numbers W trapped inside a loop of circumference C with the square root of C when the expected winding numbers are large. Such scaling is consistent with the Kibble-Zurek mechanism (KZM). By contrast, distribution of individual vortices with randomly assigned topological charges would result in the dispersion of W scaling with the square root of the area inside C. Scaling of the dispersion of W and of the probability of detection of non-zero W with C can be also studied for loops so small that non-zero windings are rare. In this case I show a doubling of the scaling of dispersion with C when compared to the scaling of dispersion in the large W regime. Moreover, probability of trapping of a non-zero W becomes, in this case, proportional to the area subtended by C (hence, to the square of circumference). This quadruples, as compared with large winding numbers regime, the exponent in the power law dependence of the frequency of trapping of W=+1 or W=-1 on C. Such change of the power law exponent by a FACTOR OF FOUR implies quadrupling of the scaling of the frequency of winding number trapping with the quench rate, and is of key importance for experimental tests of KZM.

Wojciech H. Zurek

2013-05-21T23:59:59.000Z

387

Dislocation Dynamics  

Science Conference Proceedings (OSTI)

Mar 7, 2013 ... Recent Progress in Dislocation Dynamics: Sylvie Aubry1; Athanasios Arsenlis1; Wei Cai2; Steve Fitzgerald3; 1LLNL; 2Stanford University; ...

388

C17: Voltage Impulse Induced Bistable Magnetization Switching and ...  

Science Conference Proceedings (OSTI)

Non-violate dynamic magnetization switch was also realized by voltage impulse ... Concentric Nanoparticles Embedded in Low Temperature Synthesized TiO2 Films .... F2: Development of the On-Line Mechanical Property Prediction System for ... Sintered Nd-Fe-B Magnets by Transmission Electron Microscopy Analysis.

389

Waves of magnetic moment and generation of waves by neutron beam in quantum magnetized plasma  

E-Print Network (OSTI)

This paper is devoted to studying of dispersion of waves in the magnetized plasma with the spin and exploring of new methods of the generation wave in the plasma. We consider the dispersion of waves, existed in the plasma in consequence of dynamic of the magnetic moments. It is shown there are nine new waves in the magnetized plasma because of the magnetic moments dynamic. We show there are instabilities at propagation of the neutron beam through the plasma. Increments of instabilities caused by neutron beam are calculated. For studying of this effects we generalize and use the method of the many-particle quantum hydrodynamics. Described processes can play important role at calculation of the stability and the safeness of the nuclear reactors and the studying of the processes in the atmosphere of the neutron stars.

P. A. Andreev; L. S. Kuz'menkov

2011-09-15T23:59:59.000Z

390

Magnet innovations for linacs  

Science Conference Proceedings (OSTI)

It is possible to produce large magnetic fields at the aperture of permanent magnet quadrupoles, even when the magnetic aperture is very small. That, combined with their compactness, makes permanent magnet quadrupoles very powerful components of small aperture linacs. Results will be presented about past and present work on both fixed and variable strength permanent magnets suitable for use in and around linacs.

Halbach, K.

1986-06-01T23:59:59.000Z

391

Superconducting magnet  

DOE Patents (OSTI)

A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.

Satti, John A. (Naperville, IL)

1980-01-01T23:59:59.000Z

392

Magnetics and the body  

NLE Websites -- All DOE Office Websites (Extended Search)

no magnetic "charges"), such as from electromagnets. Magnetic fields are measured in Tesla (T) or Gauss (G). The Tesla is a very large unit (1 T 10,000 G). Most large magnets...

393

Learning About Magnets!  

NLE Websites -- All DOE Office Websites (Extended Search)

the National High Magnetic Field Laboratory Learning About Name A magnet is a material or object that creates a magnetic fi eld. This fi eld is invisible, but it creates a force...

394

ALS superbend magnet system  

E-Print Network (OSTI)

ALS Superbend Magnet System J. Zbasnik † , S. T. Wang †† ,of a High-Field Magnet for the ALS,” Transactions AppliedRefrigeration options for the ALS Superbend dipole magnets”,

2000-01-01T23:59:59.000Z

395

Helical Magnets Project | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

RHIC, the basic construction unit is a superconducting dipole magnet producing a four tesla dipole field that rotates through 360 degrees in a length of 2.4 meters. The magnets...

396

Cyclotron Resonances in Electron Cloud Dynamics  

SciTech Connect

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lb<< 2pi c/omega c (with lb = bunch length, omega c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the electron cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor ~;;3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined vertical density"stripes" found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The existence of the resonances has been confirmed in experiments at PEP-II. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations and experimental observations, the reason for the bunch-length dependence, and details of the dynamics are discussed here.

Celata, C. M.; Furman, Miguel A.; Vay, J.-L.; Ng, J. S.T.; Grote, D. P.; Pivi, M. T. F.; Wang, L. F.

2009-04-29T23:59:59.000Z

397

Cyclotron Resonances in Electron Cloud Dynamics  

SciTech Connect

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where l{sub b} << 2{pi}{omega}{sub c}, (l{sub b} = bunch duration, {omega}{sub c} = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor {approx} 3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined density 'stripes' of multipactoring found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations, the reason for the bunch-length dependence, and details of the dynamics will be discussed.

Celata, C M; Furman, M A; Vay, J L; Grote, D P; Ng, J T; Pivi, M F; Wang, L F

2009-05-05T23:59:59.000Z

398

SUPERCONDUCTING MAGNETIC ENERGY STORAGE  

E-Print Network (OSTI)

Superconducting 30-MJ Energy Storage Coil", Proc. 19 80 ASC,Superconducting Magnetic Energy Storage Plant", IEEE Trans.SlIperconducting Magnetic Energy Storage Unit", in Advances

Hassenzahl, W.

2011-01-01T23:59:59.000Z

399

Magnetization of neutron matter  

SciTech Connect

In this paper, we compute magnetization of neutron matter at strong magnetic field using the lowest order constrained variational (LOCV) technique.

Bigdeli, M. [Department of Physics, Zanjan University, P.O. Box 45195-313, Zanjan (Iran, Islamic Republic of)

2011-09-21T23:59:59.000Z

400

Regenerator for Magnetic Refrigerants  

Ames Laboratory researchers have developed a new magnetic material that can be used at low temperatures (sub liquid hydrogen) for magnetic refrigerators.

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401

Magnetic Materials Group Homepage  

Science Conference Proceedings (OSTI)

... and simulation to become the driving force in ... develop a real-time magnetic domain imaging ... data-storage and permanent magnets with increased ...

2012-12-03T23:59:59.000Z

402

NSLS II: Magnetism  

NLE Websites -- All DOE Office Websites (Extended Search)

spatial ordering of the magnetic moments that is superimposed on the crystal lattice. Why these atomic magnetic moments survive and how they arrange in the solid is the...

403

Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results  

Science Conference Proceedings (OSTI)

A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

O'Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

2002-08-01T23:59:59.000Z

404

Investigation of vortex generators for augmentation of wind turbine power performance  

SciTech Connect

This study focuses on the use of vortex generators (VGs) for performance augmentation of the stall-regulated AWT-26 wind turbine. The goal was to design a VG array which would increase annual energy production (AEP) by increasing power output at moderate wind speeds, without adversely affecting the loads or stall-regulation performance of the turbine. Wind tunnel experiments were conducted at the University of Washington to evaluate the effect of VGs on the AWT-26 blade, which is lofted from National Renewable Energy Laboratory (NREL) S-series airfoils. Based on wind-tunnel results and analysis, a VG array was designed and then tested on the AWT-26 prototype, designated P1. Performance and loads data were measured for P1, both with and without VGs installed. the turbine performance with VGs met most of the design requirements; power output was increased at moderate wind speeds with a negligible effect on peak power. However, VG drag penalties caused a loss in power output for low wind speeds, such that performance with VGs resulted in a net decrease in AEP for sites having annual average wind speeds up to 8.5 m/s. While the present work did not lead to improved AEP for the AWT-2 turbine, it does provide insight into performance augmentation of wind turbines with VGs. The safe design of a VG array for a stall-regulated turbine has been demonstrated, and several issues involving optimal performance with VGs have been identified and addressed. 15 refs., 34 figs., 10 tabs.

Griffin, D.A. [Lynette (R.) and Associates, Seattle, WA (United States)

1996-12-01T23:59:59.000Z

405

Vortex induced vibration for aquatic clean power (VIVACE)NOTE FROM ACM: It has been determined that the author of this article plagiarized the contents from a previously published paper. Therefore ACM has shut off access to this paper.  

Science Conference Proceedings (OSTI)

NOTE FROM ACM: It has been determined that the author of this article plagiarized the contents from a previously published paper. Therefore ACM has shut off access to this paper. The paper by M. K. Raj and B. G. Muthuraj plagiarizes the ... Keywords: VIVACE, reynolds number, undulations, vortex shedding, vortex vibrations

M. K. Raj; B. G. Muthuraj

2011-02-01T23:59:59.000Z

406

Solid effect in magic angle spinning dynamic nuclear polarization  

E-Print Network (OSTI)

For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic ...

Smith, Albert A.

407

Magnetooptical Kerr effect measurements of ultrafast spin dynamics in cobalt nanodots  

Science Conference Proceedings (OSTI)

We present our magnetooptical Kerr effect (MOKE) studies on picosecond spin dynamics in closely spaced rectangular Co dots with sizes ranging from 2×6 ?m2 down to 100 × 300 nm2 under in-plane, picosecond, ... Keywords: Coherent spin dynamics, Kerr effect, femtosecond optical pulses, magnetic nanodots, magnetooptics, picosecond magnetic transients, spintronics

D. Wang; A. Verevkin; R. Sobolewski; R. Adam; A. van der Hart; R. Franchy

2005-07-01T23:59:59.000Z

408

Chiral magnetic effect in lattice QCD with chiral chemical potential  

E-Print Network (OSTI)

We perform a first lattice QCD simulation including two-flavor dynamical fermion with chiral chemical potential. Because the chiral chemical potential gives rise to no sign problem, we can exactly analyze a chirally asymmetric QCD matter by the Monte Carlo simulation. By applying an external magnetic field to this system, we obtain a finite induced current along the magnetic field, which corresponds to the chiral magnetic effect. The obtained induced current is proportional to the magnetic field and to the chiral chemical potential, which is consistent with an analytical prediction.

Yamamoto, Arata

2011-01-01T23:59:59.000Z

409

Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide  

Science Conference Proceedings (OSTI)

Since their discovery by Bednorz and Mueller (1986), high-temperature cuprate superconductors have been the subject of intense experimental research and theoretical work. Despite this large-scale effort, agreement on the mechanism of high-T{sub c} has not been reached. Many theories make their strongest predictions for underdoped superconductors with very low superfluid density n{sub s}/m*. For this dissertation I implemented a scanning Hall probe microscope and used it to study magnetic vortices in newly available single crystals of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} (Liang et al. 1998, 2002). These studies have disproved a promising theory of spin-charge separation, measured the apparent vortex size (an upper bound on the penetration depth {lambda}{sub ab}), and revealed an intriguing phenomenon of ''split'' vortices. Scanning Hall probe microscopy is a non-invasive and direct method for magnetic field imaging. It is one of the few techniques capable of submicron spatial resolution coupled with sub-{Phi}{sub 0} (flux quantum) sensitivity, and it operates over a wide temperature range. Chapter 2 introduces the variable temperature scanning microscope and discusses the scanning Hall probe set-up and scanner characterizations. Chapter 3 details my fabrication of submicron GaAs/AlGaAs Hall probes and discusses noise studies for a range of probe sizes, which suggest that sub-100 nm probes could be made without compromising flux sensitivity. The subsequent chapters detail scanning Hall probe (and SQUID) microscopy studies of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} crystals with T{sub c} {le} 15 K. Chapter 4 describes two experimental tests for visons, essential excitations of a spin-charge separation theory proposed by Senthil and Fisher (2000, 2001b). We searched for predicted hc/e vortices (Wynn et al. 2001) and a vortex memory effect (Bonn et al. 2001) with null results, placing upper bounds on the vison energy inconsistent with the theory. Chapter 5 discusses imaging of isolated vortices as a function of T{sub c}. Vortex images were fit with theoretical magnetic field profiles in order to extract the apparent vortex size. The data for the lowest T{sub c}'s (5 and 6.5 K) show some inhomogeneity and suggest that {lambda}{sub ab} might be larger than predicted by the T{sub c} {proportional_to} n{sub s}(0)/m* relation first suggested by results of Uemura et al. (1989) for underdoped cuprates. Finally, Chapter 6 examines observations of apparent ''partial vortices'' in the crystals. My studies of these features indicate that they are likely split pancake vortex stacks. Qualitatively, these split stacks reveal information about pinning and anisotropy in the samples. Collectively these magnetic imaging studies deepen our knowledge of cuprate superconductivity, especially in the important regime of low superfluid density.

Guikema, Janice Wynn; /SLAC, SSRL

2005-12-02T23:59:59.000Z

410

FLUX EMERGENCE IN A MAGNETIZED CONVECTION ZONE  

Science Conference Proceedings (OSTI)

We study the influence of a dynamo magnetic field on the buoyant rise and emergence of twisted magnetic flux ropes and their influence on the global external magnetic field. We ran three-dimensional MHD numerical simulations using the ASH code (anelastic spherical harmonics) and analyzed the dynamical evolution of such buoyant flux ropes from the bottom of the convection zone until the post-emergence phases. The global nature of this model can only very crudely and inaccurately represent the local dynamics of the buoyant rise of the implanted magnetic structure, but nonetheless allows us to study the influence of global effects, such as self-consistently generated differential rotation and meridional circulation, and of Coriolis forces. Although motivated by the solar context, this model cannot be thought of as a realistic model of the rise of magnetic structures and their emergence in the Sun, where the local dynamics are completely different. The properties of initial phases of the buoyant rise are determined essentially by the flux-rope's properties and the convective flows and consequently are in good agreement with previous studies. However, the effects of the interaction of the background dynamo field become increasingly strong as the flux ropes evolve. During the buoyant rise across the convection zone, the flux-rope's magnetic field strength scales as B{proportional_to}{rho}{sup {alpha}}, with {alpha} {approx}current density is observed to precede flux emergence at all longitudes. The geometry, latitude, and relative orientation of the flux ropes with respect to the background magnetic field influences the resulting rise speeds, zonal flow amplitudes (which develop within the flux ropes), and the corresponding surface signatures. This influences the morphology, duration and amplitude of the surface shearing, and the Poynting flux associated with magnetic flux-rope emergence. The emerged magnetic flux influences the system's global polarity, leading in some cases to a polarity reversal while inhibiting the background dynamo from doing so in others. The emerged magnetic flux is slowly advected poleward while being diffused and assimilated by the background dynamo field.

Pinto, R. F.; Brun, A. S., E-mail: rui.pinto@cea.fr [Laboratoire AIM Paris-Saclay, CEA/Irfu Universite Paris-Diderot CNRS/INSU, F-91191 Gif-sur-Yvette (France)

2013-07-20T23:59:59.000Z

411

Flame-vortex interaction and mixing behaviors of turbulent non-premixed jet flames under acoustic forcing  

SciTech Connect

This study examines the effect of acoustic excitation using forced coaxial air on the flame characteristics of turbulent hydrogen non-premixed flames. A resonance frequency was selected to acoustically excite the coaxial air jet due to its ability to effectively amplify the acoustic amplitude and reduce flame length and NO{sub x} emissions. Acoustic excitation causes the flame length to decrease by 15% and consequently, a 25% reduction in EINO{sub x} is achieved, compared to coaxial air flames without acoustic excitation at the same coaxial air to fuel velocity ratio. Moreover, acoustic excitation induces periodical fluctuation of the coaxial air velocity, thus resulting in slight fluctuation of the fuel velocity. From phase-lock PIV and OH PLIF measurement, the local flow properties at the flame surface were investigated under acoustic forcing. During flame-vortex interaction in the near field region, the entrainment velocity and the flame surface area increased locally near the vortex. This increase in flame surface area and entrainment velocity is believed to be a crucial factor in reducing flame length and NO{sub x} emission in coaxial jet flames with acoustic excitation. Local flame extinction occurred frequently when subjected to an excessive strain rate, indicating that intense mass transfer of fuel and air occurs radially inward at the flame surface. (author)

Kim, Munki; Choi, Youngil; Oh, Jeongseog; Yoon, Youngbin [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea)

2009-12-15T23:59:59.000Z

412

A Detailed Analysis of the Nonlinear Dynamics of the Electric Step Motor J. Reiss, F. Alin*  

E-Print Network (OSTI)

responsible for the torque, motors can be classified as variable reluctance motors, permanent magnet motors magnet on the rotor. In this case, the torque is due to the variable resistance. Permanent magnet motorsA Detailed Analysis of the Nonlinear Dynamics of the Electric Step Motor J. Reiss, F. Alin* , M

Reiss, Josh

413

HTS Magnet Program | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

HTS Magnet Program HTS Magnet Program High Temperature Superconductors (HTS) have the potential to revolutionize the field of superconducting magnets for particle accelerators, energy storage and medical applications. This is because of the fact that as compared to the conventional Low Temperature Superconductors (LTS), the critical current density (Jc ) of HTS falls slowly both: as a function of increasing field, and as a function of increasing temperature These unique properties can be utilized to design and build: HTS magnets that produce very high fields (20 - 50 T) HTS magnets that operate at elevated temperatures (20 - 77 K) This is a significant step forward over the convention LTS magnets which generally operate at a temperature of ~4 K and with field usually limited

414

Nanocomposite Magnets: Transformational Nanostructured Permanent Magnets  

SciTech Connect

Broad Funding Opportunity Announcement Project: GE is using nanomaterials technology to develop advanced magnets that contain fewer rare earth materials than their predecessors. Nanomaterials technology involves manipulating matter at the atomic or molecular scale, which can represent a stumbling block for magnets because it is difficult to create a finely grained magnet at that scale. GE is developing bulk magnets with finely tuned structures using iron-based mixtures that contain 80% less rare earth materials than traditional magnets, which will reduce their overall cost. These magnets will enable further commercialization of HEVs, EVs, and wind turbine generators while enhancing U.S. competitiveness in industries that heavily utilize these alternatives to rare earth minerals.

None

2010-10-01T23:59:59.000Z

415

Summary of HQ01e magnetic measurements  

SciTech Connect

The magnetic measurements of HQ01e, a 1 m long LHC Accelerator Research Program (LARP) high-gradient quadrupole model, were performed at 4.4 K and above 40 K at the magnet test facility of LBNL in July 2011. The 120 mm aperture cos2? Nb{sub 3}Sn magnet was designed with accelerator magnet features including alignment and field quality. Conductor-limited gradient was 195 T/m at 4.4 K. During the measurement, a ramp rate of 10 A/s was used and measurements at the nominal current of 14.2 kA (82% of short-sample limit with a gradient of 160 T/m) were performed using the 250 mm long printed-circuit board rotating probe developed by FNAL. At 14.2 kA, 2.7 units of b{sub 6} and 0.7 units of b{sub 10} were measured. Large persistent current contribution and strong dynamic effects were observed. We analyzed the allowed and non-allowed harmonics obtained during the measurements above 40 K and at the nominal current. Significant change of the skew sextupole occurred between 50 K and 95 K. The allowed multipole and the low-order non-allowed multipoles at the straight section were explained through the rigid displacement of coil blocks with an amplitude less than 100 ?m. We also attempted to correlate the coil asymmetry (a{sub 3} and b{sub 3}) with the measured coil pole azimuthal strain. The dynamic multipole measured at the magnetic straight section varied linearly with the ramp rate of magnet current ranging from 10 A/s to 60 A/s. It was attributed to the inter-strand coupling currents with low crossover resistance. The crossover resistance of the cables at the inner layer of the magnet was estimated to range between 0.2 ?? to 0.7 ??.

Wang, X.; Caspi, S.; Cheng, D. W.; Dietderich, D. R.; Felice, H.; Ferracin, P.; Godeke, A.; Hafalia, A.R.; Joseph, J. M.; Lizarazo, J.; Marchevsky, M.; Sabbi, G. L.; Ghosh, A.; Schmalzle, J.; Wanderer, P.; Ambrosio, G.; Bossert, R.; Chlachidze, G.; DiMarco, J.; Zlobin, A.V.; Milanese, A.; Todesco, E.

2011-11-28T23:59:59.000Z

416

Tamper resistant magnetic stripes  

DOE Patents (OSTI)

This invention relates to a magnetic stripe comprising a medium in which magnetized particles are suspended and in which the encoded information is recorded by actual physical rotation or alignment of the previously magnetized particles within the flux reversals of the stripe which are 180.degree. opposed in their magnetic polarity. The magnetized particles are suspended in a medium which is solid, or physically rigid, at ambient temperatures but which at moderately elevated temperatures, such as 40.degree. C., is thinable to a viscosity permissive of rotation of the particles therein under applications of moderate external magnetic field strengths within acceptable time limits.

Naylor, Richard Brian (Albuquerque, NM); Sharp, Donald J. (Albuquerque, NM)

1999-01-01T23:59:59.000Z

417

Lensless Imaging of Magnetic Nanostructures  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine....

418

Scaling laws for the tropical cyclone derived from the stationary atmospheric vortex equation  

E-Print Network (OSTI)

We present results of a numerical study of the differential equation governing the stationary states of the two-dimensional planetary atmosphere and magnetized plasma (within the Charney Hasegawa Mima model). The results show an interesting similarity with the morphology of a tropical cyclone. Quantitative comparisons are also favorable and several scaling laws can be formulated connecting the charactersistic physical parameters of the tropical cyclone.

Spineanu, F; Spineanu, Florin; Vlad, Madalina

2006-01-01T23:59:59.000Z

419

Non-Uniform Switching of the Perpendicular Magnetization in a Spin-Torque Magnetic Nanopillar  

SciTech Connect

Time-resolved scanning transmission x-ray microscopy (STXM) measurements were performed to study the current-induced magnetization switching mechanism in nanopillars exhibiting strong perpendicular magnetic anisotropy (PMA). This technique provides both short time (70 ps) and high spatial (25 nm) resolution. Direct imaging of the magnetization demonstrates that, after an incubation time of {approx} 1.3 ns, a 100 x 300 nm{sup 2} ellipsoidal device switches in {approx} 1 ns via a central domain nucleation and opposite propagation of two domain walls towards the edges. High domain wall velocities on the order of 100m/s are measured. Micromagnetic simulations are shown to be in good agreement with experimental results and provide insight into magnetization dynamics during the incubation and reversal period.

Bernstein, David

2011-06-01T23:59:59.000Z

420

MAGNETIC LOOPS IN THE QUIET SUN  

Science Conference Proceedings (OSTI)

We investigate the fine structure of magnetic fields in the atmosphere of the quiet Sun. We use photospheric magnetic field measurements from SUNRISE/IMaX with unprecedented spatial resolution to extrapolate the photospheric magnetic field into higher layers of the solar atmosphere with the help of potential and force-free extrapolation techniques. We find that most magnetic loops that reach into the chromosphere or higher have one footpoint in relatively strong magnetic field regions in the photosphere. Ninety-one percent of the magnetic energy in the mid-chromosphere (at a height of 1 Mm) is in field lines, whose stronger footpoint has a strength of more than 300 G, i.e., above the equipartition field strength with convection. The loops reaching into the chromosphere and corona are also found to be asymmetric in the sense that the weaker footpoint has a strength B < 300 G and is located in the internetwork (IN). Such loops are expected to be strongly dynamic and have short lifetimes, as dictated by the properties of the IN fields.

Wiegelmann, T.; Solanki, S. K.; Barthol, P.; Gandorfer, A. [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Str. 2, 37191 Katlenburg-Lindau (Germany); Borrero, J. M.; Schmidt, W. [Kiepenheuer-Institut fuer Sonnenphysik, Schoeneckstr. 6, 79104 Freiburg (Germany); Pillet, V. MartInez; Bonet, J. A. [Instituto de Astrofisica de Canarias, C/Via Lactea s/n, 38200 La Laguna, Tenerife (Spain); Del Toro Iniesta, J. C. [Instituto de Astrofisica de Andalucia (CSIC), Apartado de Correos 3004, 18080 Granada (Spain); Domingo, V. [Grupo de Astronomia y Ciencias del Espacio, Universidad de Valencia, 46980 Paterna, Valencia (Spain); Knoelker, M. [High Altitude Observatory, National Center for Atmospheric Research Boulder, CO 80307 (United States); Title, A. M., E-mail: wiegelmann@mps.mpg.d [Lockheed Martin Solar and Astrophysics Laboratory, Bldg. 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States)

2010-11-10T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Active magnetic regenerator  

SciTech Connect

The disclosure is directed to an active magnetic regenerator apparatus and method. Brayton, Stirling, Ericsson, and Carnot cycles and the like may be utilized in an active magnetic regenerator to provide efficient refrigeration over relatively large temperature ranges.

Barclay, John A. (Los Alamos, NM); Steyert, William A. (Los Alamos, NM)

1982-01-01T23:59:59.000Z

422

ALS superbend magnet performance  

E-Print Network (OSTI)

ALS Superbend Magnet Performance S. Marks, J. Zbasnik, W.the Advanced Light Source (ALS), with the fourth magnet as ahe Advanced Light Source (ALS) at the Lawrence Berkeley

2001-01-01T23:59:59.000Z

423

LHC Magnet Program | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnet Program Magnet Program The Superconducting Magnet Division is building a number of dipole magnets for the Large Hadron Collider (LHC), which is now under construction at CERN in Geneva, Switzerland. Scheduled to begin operation in 2007, this machine will collide beams of protons with the unprecedented energy of 7 TeV per beam to explore the nature of matter at its most basic level (RHIC can collide beams of protons with energies of 0.25 TeV, but is mostly used to collide heavy ions with energies of 0.1 TeV per nucleon). The magnets are being built as part of the US program, recommended by the High Energy Physics Advisory Panel (HEPAP) and approved by Congress, to contribute to the construction and, later, use of that frontier machine by the US high energy physics community. Fermi National Accelerator Laboratory (FNAL) and

424

Dynamic tariffs  

SciTech Connect

The general theoretical models of dynamic tariffs, such as spot pricing, are extended in this paper to include the issues of optimal response of industrial consumers and the effect of large scale penetration of these tariffs on the utility load curve. If such tariffs are to serve their purpose consumers need to acquire the ability for flexible and dynamic response. While the hardware for this is readily available the theoretical models and software systems are not. These issues are examined and correlated with industrial site studies. A systematic analysis of the effect of significant consumer response on the system load curve is next undertaken. A methodologically sound approach to system load and price forecasting is presented.

David, A.K.; Lee, Y.C.

1989-08-01T23:59:59.000Z

425

Magnetic Materials Staff  

Science Conference Proceedings (OSTI)

... Materials Science and Engineering Division Staff Directory; MML Organization. Contact. Magnetic Materials Group Robert Shull, Group Leader. ...

2012-10-09T23:59:59.000Z

426

Minimum Magnetic Energy Theorem  

E-Print Network (OSTI)

The Thomson's Theorem states that static charge distributions in conductors show up at the conducting surfaces in an equipotential configuration, so that the electrostatic energy is a minimum. In this work we study an analogue statement for magnetic systems: in a given set of conductors, the stored magnetic field energy reaches the minimum value for superficial current distributions so that the magnetic vector potential is tangent to the conductors surfaces. This is the counterpart of Thomson's theorem for the magnetic field.

Fiolhais, M C N

2008-01-01T23:59:59.000Z

427

Superconducting magnet of Aurora  

Science Conference Proceedings (OSTI)

The AURORAsuperconducting magnet system is composed of a cylindrical single?body magnet and a refrigeration system for superconducting coils. The magnet generates B z =1 T on the central orbit at the 150 MeV electron beam injection energy and B z =4.3 T at the 650 MeV storage energy. The diameter of the central orbit is 1 m. Iron poles and yokes are used for shielding the magnetic field

T. Takayama; SHI Accelerator Research Group

1989-01-01T23:59:59.000Z

428

Irreversible magnetic switch  

DOE Patents (OSTI)

This invention is comprised of an irreversible magnetic switch containing a ferromagnetic amorphous metal having a predetermined crystallization temperature in its inductor magnetic path. With the incorporation of such material, the magnetic properties after cooling from a high temperature excursion above its crystallization temperature are only a fraction of the original value. The difference is used to provide a safety feature in the magnetic switch.

Karnowsky, M.M.; Yost, F.G.

1991-12-31T23:59:59.000Z

429

Magnetic Nanoparticle Metrology  

Science Conference Proceedings (OSTI)

... T2 relaxation times, hysteretic energy loss, etc ... Optimization of magnetic nanoparticle synthesis for ... competition between lattice energies and dipolar ...

2012-12-03T23:59:59.000Z

430

Nonlinear dynamics of Kelvin-Helmholtz instability in a finite-width plasma flow  

SciTech Connect

The nonlinear stage of Kelvin-Helmholtz (KH) instability in a finite-width plane-parallel plasma flow is analyzed. The analysis is performed by means of two-dimensional numerical simulations with the use of ideal magnetohydrodynamic equations describing isothermal plasma flows propagating along the magnetic field. The influence of the magnetic field strength, the plasma temperature, and the ratio of the flow width to the width of the transition layer on the formation of vortex layers and large-scale flow perturbations is investigated. It is shown that, if the wavelength of periodic perturbations is shorter than the flow width, the symmetric and antisymmetric modes develop in a qualitatively similar manner. For waves with wavelengths longer than the flow width, the development of such modes is very different due to the mutual influence of the flow boundaries. Analysis of the development of instability at different values of the Alfven Mach number M{sub A} shows that long-lived vortices with a characteristic scale length on the order of the flow width appear in a weak magnetic field for both symmetric and antisymmetric modes; however, the vortex geometries for these modes are different. In a strong magnetic field, M{sub A} {approx} 5, the phase of vortex decay for both types of modes occurs faster than in a weak field; however, in the case of an antisymmetric mode, large-scale perturbations of the flow boundary are retained for a longer time. Analysis of the evolution of the initial disturbance produced by an ensemble of random small perturbations (noise) at different plasma temperatures shows that, for a flow width comparable with the width of the transition region, the development of KH instability is always antisymmetric in character and leads to well-developed large-scale perturbations of the flow as a whole. For a cold plasma with C{sub S} < 0.5U (where C{sub S} is the speed of sound and U is the flow velocity), in contrast to hot plasma with C{sub S} > 0.5U, the development of KH instability leads to the growth of the antisymmetric mode even if the flow width is much larger than the width of the transition region.

Shevelev, M. M.; Burinskaya, T. M., E-mail: tburinsk@iki.rssi.ru [Russian Academy of Sciences, Space Research Institute (Russian Federation)

2013-06-15T23:59:59.000Z

431

QUIESCENT PROMINENCE DYNAMICS OBSERVED WITH THE HINODE SOLAR OPTICAL TELESCOPE. I. TURBULENT UPFLOW PLUMES  

SciTech Connect

Hinode/Solar Optical Telescope (SOT) observations reveal two new dynamic modes in quiescent solar prominences: large-scale (20-50 Mm) 'arches' or 'bubbles' that 'inflate' from below into prominences, and smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are related in that they are always dark in visible-light spectral bands, they rise through the bright prominence emission with approximately constant speeds, and the small-scale upflows are sometimes observed to emanate from the top of the larger bubbles. Here we present detailed kinematic measurements of the small-scale turbulent upflows seen in several prominences in the SOT database. The dark upflows typically initiate vertically from 5 to 10 Mm wide dark cavities between the bottom of the prominence and the top of the chromospheric spicule layer. Small perturbations on the order of 1 Mm or less in size grow on the upper boundaries of cavities to generate plumes up to 4-6 Mm across at their largest widths. All plumes develop highly turbulent profiles, including occasional Kelvin-Helmholtz vortex 'roll-up' of the leading edge. The flows typically rise 10-15 Mm before decelerating to equilibrium. We measure the flowfield characteristics with a manual tracing method and with the Nonlinear Affine Velocity Estimator (NAVE) 'optical flow' code to derive velocity, acceleration, lifetime, and height data for several representative plumes. Maximum initial speeds are in the range of 20-30 km s{sup -1}, which is supersonic for a {approx}10,000 K plasma. The plumes decelerate in the final few Mm of their trajectories resulting in mean ascent speeds of 13-17 km s{sup -1}. Typical lifetimes range from 300 to 1000 s ({approx}5-15 minutes). The area growth rate of the plumes (observed as two-dimensional objects in the plane of the sky) is initially linear and ranges from 20,000 to 30,000 km{sup 2} s{sup -1} reaching maximum projected areas from 2 to 15 Mm{sup 2}. Maximum contrast of the dark flows relative to the bright prominence plasma in SOT images is negative and ranges from -10% for smaller flows to -50% for larger flows. Passive scalar 'cork movies' derived from NAVE measurements show that prominence plasma is entrained by the upflows, helping to counter the ubiquitous downflow streams in the prominence. Plume formation shows no clear temporal periodicity. However, it is common to find 'active cavities' beneath prominences that can spawn many upflows in succession before going dormant. The mean flow recurrence time in these active locations is roughly 300-500 s (5-8 minutes). Locations remain active on timescales of tens of minutes up to several hours. Using a column density ratio measurement and reasonable assumptions on plume and prominence geometries, we estimate that the mass density in the dark cavities is at most 20% of the visible prominence density, implying that a single large plume could supply up to 1% of the mass of a typical quiescent prominence. We hypothesize that the plumes are generated from a Rayleigh-Taylor instability taking place on the boundary between the buoyant cavities and the overlying prominence. Characteristics, such as plume size and frequency, may be modulated by the strength and direction of the cavity magnetic field relative to the prominence magnetic field. We conclude that buoyant plumes are a source of quiescent prominence mass as well as a mechanism by which prominence plasma is advected upward, countering constant gravitational drainage.

Berger, Thomas E.; Slater, Gregory; Hurlburt, Neal; Shine, Richard; Tarbell, Theodore; Title, Alan [Lockheed Martin Solar and Astrophysics Laboratory, B/252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Lites, Bruce W. [High Altitude Observatory, University Center for Atmospheric Research, Boulder, CO (United States); Okamoto, Takenori J.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Magara, Tetsuya; Suematsu, Yoshinori [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Shimizu, Toshifumi, E-mail: berger@lmsal.co [Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510 (Japan)

2010-06-20T23:59:59.000Z

432

Tunable Magnetic Regenerator/Refrigerant  

Magnetic regenerators utilize the magnetocaloric effect--the ability of a magnetic field to reduce the magnetic part of a solid materials entropy, generating heat, and then removing the magnetic field, permitting the reduction of temperature with the ...

433

Magnetic nanohole superlattices  

DOE Patents (OSTI)

A magnetic material is disclosed including a two-dimensional array of carbon atoms and a two-dimensional array of nanoholes patterned in the two-dimensional array of carbon atoms. The magnetic material has long-range magnetic ordering at a temperature below a critical temperature Tc.

Liu, Feng

2013-05-14T23:59:59.000Z

434

Perfusion Estimated With Rapid Dynamic Contrast-Enhanced Magnetic Resonance Imaging Correlates Inversely With Vascular Endothelial Growth Factor Expression and Pimonidazole Staining in Head-and-Neck Cancer: A Pilot Study  

Science Conference Proceedings (OSTI)

Purpose: To analyze, in a pilot study, rapidly acquired dynamic contrast-enhanced (DCE)-MRI data with a general two-compartment exchange tracer kinetic model and correlate parameters obtained with measurements of hypoxia and vascular endothelial growth factor (VEGF) expression in patients with squamous cell carcinoma of the head and neck. Methods and Materials: Eight patients were scanned before surgery. The DCE-MRI data were acquired with 1.5-s temporal resolution and analyzed using the two-compartment exchange tracer kinetic model to obtain estimates of parameters including perfusion and permeability surface area. Twelve to 16 h before surgery, patients received an intravenous injection of pimonidazole. Samples taken during surgery were used to determine the level of pimonidazole staining using immunohistochemistry and VEGF expression using quantitative real-time polymerase chain reaction. Correlations between the biological and imaging data were examined. Results: Of the seven tumors fully analyzed, those that were poorly perfused tended to have high levels of pimonidazole staining (r = -0.79, p = 0.03) and VEGF expression (r = -0.82, p = 0.02). Tumors with low permeability surface area also tended to have high levels of hypoxia (r = -0.75, p = 0.05). Hypoxic tumors also expressed higher levels of VEGF (r = 0.82, p = 0.02). Conclusions: Estimates of perfusion obtained with rapid DCE-MRI data in patients with head-and-neck cancer correlate inversely with pimonidazole staining and VEGF expression.

Donaldson, Stephanie B., E-mail: Stephanie.donaldson@physics.cr.man.ac.uk [School of Cancer and Enabling Sciences, University of Manchester, Manchester (United Kingdom) and North Western Medical Physics, The Christie, Manchester (United Kingdom); Betts, Guy [School of Cancer and Enabling Sciences, University of Manchester, Manchester (United Kingdom); Bonington, Suzanne C. [Department of Radiology, The Christie, Manchester (United Kingdom); Homer, Jarrod J. [School of Cancer and Enabling Sciences, University of Manchester, Manchester (United Kingdom); Department of Otolaryngology-Head-and-Neck Surgery, Manchester Royal Infirmary, Manchester (United Kingdom); Slevin, Nick J. [Department of Clinical Oncology, The Christie, Manchester (United Kingdom); Kershaw, Lucy E.; Valentine, Helen [School of Cancer and Enabling Sciences, University of Manchester, Manchester (United Kingdom); West, Catharine M.L. [School of Cancer and Enabling Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester (United Kingdom); Buckley, David L. [School of Cancer and Enabling Sciences, University of Manchester, Manchester (United Kindgom) and Division of Medical Physics, University of Leeds, Leeds (United Kingdom)

2011-11-15T23:59:59.000Z

435

Magnetic damping for maglev  

DOE Green Energy (OSTI)

Magnetic damping is one of the important parameters to control the response and stability of maglev systems. An experimental study is presented to measure the magnetic damping using a direct method. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters on magnetic damping such as conductivity, gap, excitation frequency, and oscillation amplitude. The experimental technique is capable of measuring all magnetic damping coefficients, some of which can not be measured by an indirect method.

Chen, S.S.; Zhu, S.; Cai, Y.; Rote, D.M. [Argonne National Lab., IL (United States). Energy Technology Div.

1994-12-31T23:59:59.000Z

436

Magnetically attached sputter targets  

DOE Patents (OSTI)

An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

Makowiecki, D.M.; McKernan, M.A.

1994-02-15T23:59:59.000Z

437

An investigation of the Goshen County, Wyoming, tornadic supercell of 5 June 2009 using EnKF assimilation of mobile mesonet and radar observations collected during VORTEX2. Part I: Experiment design and verification of the EnKF analyses  

Science Conference Proceedings (OSTI)

High-resolution Doppler radar velocities and in situ surface observations collected in a tornadic supercell on 5 June 2009 during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) are assimilated into a simulated ...

James Marquis; Yvette Richardson; Paul Markowski; David Dowell; Joshua Wurman; Karen Kosiba; Paul Robinson; Glen Romine

438

Modeling Magnetically Excited and Magnetically Damped Liquid ...  

Science Conference Proceedings (OSTI)

The dynamic interaction of the turbulent flow with the oscillating interface needs to be accounted if it is required to levitate liquid metal of up to few kilograms ...

439

The Dynamics and Predictability of Tropical Cyclones  

E-Print Network (OSTI)

Through methodology unique for tropical cyclones in peer-reviewed literature, this study explores how the dynamics of moist convection affects the predictability of tropical cyclogenesis. Mesoscale models are used to perform short-range ensemble forecasts of a non-developing disturbance in 2004 and Hurricane Humberto in 2007; both of these cases were highly unpredictable. Taking advantage of discrepancies between ensemble members in short-range ensemble forecasts, statistical correlation is used to pinpoint sources of error in forecasts of tropical cyclone formation and intensification. Despite significant differences in methodology, storm environment and development, it is found in both situations that high convective instability (CAPE) and mid-level moisture are two of the most important factors for genesis. In the gulf low, differences in CAPE are related to variance in quasi-geostrophic lift, and in Humberto the differences are related to the degree of interaction between the cyclone and a nearby front. Regardless of the source of CAPE variance, higher CAPE and mid-level moisture combine to yield more active initial convection and more numerous and strong vortical hot towers (VHTs), which incrementally contribute to a stronger vortex. In both cases, strength differences between ensemble members are further amplified by differences in convection that are related to oceanic heat fluxes. Eventually the WISHE mechanism results in even larger ensemble spread, and in the case of Humberto, uncertainty related to the time of landfall drives spread even higher. It is also shown that initial condition differences much smaller than current analysis error can ultimately control whether or not a tropical cyclone forms. Furthermore, even smaller differences govern how the initial vortex is built. Differences in maximum winds and/or vorticity vary nonlinearly with initial condition differences and depend on the timing and intensity of small mesoscale features such as VHTs and cold pools. Finally, the strong sensitivity to initial condition differences in both cases exemplifies the inherent uncertainties in hurricane intensity prediction. This study illustrates the need for implementing advanced data analysis schemes and ensemble prediction systems to provide more accurate and event-dependent probabilistic forecasts.

Sippel, Jason A.

2008-12-01T23:59:59.000Z

440

A Stable Magnetic Background in SU(2) QCD  

E-Print Network (OSTI)

Motivated by the instability of the Savvidy-Nielsen-Olesen (SNO) vacuum we make a systematic search for a stable magnetic background in pure SU(2) QCD. It is shown that Wu-Yang monopole-antimonopole pair is unstable under vacuum fluctuations. However, it is shown that a pair of axially symmetric monopole-antimonopole string configuration is stable, provided the distance between the two strings is small enough (less than a critical value). The existence of a stable monopole-antimonopole string background strongly supports that a magnetic condensation of monopole-antimonopole pairs can indeed generate a dynamical symmetry breaking, and thus a desired magnetic confinement of color, in QCD.

Y. M. Cho; D. G. Pak

2005-10-24T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Passive magnetic bearing element with minimal power losses  

DOE Patents (OSTI)

Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in U.S. Patent No. 5,495,221 entitled "Dynamically Stable Magnetic Suspension/Bearing System." The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity.

Post, Richard F. (Walnut Creek, CA)

1998-01-01T23:59:59.000Z

442

Passive magnetic bearing element with minimal power losses  

DOE Patents (OSTI)

Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in US Patent No. 5,495,221 entitled ``Dynamically Stable Magnetic Suspension/Bearing System.`` The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity. 8 figs.

Post, R.F.

1998-12-08T23:59:59.000Z

443

Quantum Computation with Magnetic Clusters  

E-Print Network (OSTI)

We propose a complete, quantitative quantum computing system which satisfies the five DiVincenzo criteria. The model is based on magnetic clusters with uniaxial anisotropy, where standard, two-state qubits are formed utilizing the two lowest-lying states of an anisotropic potential energy. We outline the quantum dynamics required by quantum computing for single qubit structures, and then define a novel measurement scheme in which qubit sates can be measured by sharp changes in current as voltage across the cluster is varied. We then extend the single qubit description to multiple qubit interactions, facilitated specifically by a new entanglement method which propagates the controlled-NOT (C-NOT) quantum gate.

Daniel D. Dorroh; Serkay Olmez; Jian-Ping Wang

2013-05-17T23:59:59.000Z

444

The influence of vortex pinning and grain boundary structure on critical currents across grain boundaries in YBa{sub 2}Cu{sub 3}O{sub x}.  

SciTech Connect

We have used studies of single grain boundaries in YBCO thin films and bulk bicrystals to study the influence of vortex pinning along a grain boundary on dissipation. The critical current density for transport across grain boundaries in thin films is typically more than an order of magnitude larger than that measured for transport across grain boundaries in bulk samples. For low disorientation angles, the difference in critical current density within the grains that form the boundary can contribute to the substantial differences in current density measured across the boundary. However, substantial differences exist in the critical current density across boundaries in thin film compared to bulk bicrystals even in the higher angle regime in which grain boundary dissipation dominates. The differences in critical current density in this regime can be understood on the basis of vortex pinning along the boundary.

Miller, D. J.

1998-10-27T23:59:59.000Z

445

Imaging nanoscale magnetic structures with polarized soft x-ray photons  

SciTech Connect

Imaging nanoscale magnetic structures and their fast dynamics is scientifically interesting and technologically of highest relevance. The combination of circularly polarized soft X-ray photons which provide a strong X-ray magnetic circular dichroism effect at characteristic X-ray absorption edges, with a high resolution soft X-ray microscope utilizing Fresnel zone plate optics allows to study in a unique way the stochastical behavior in the magnetization reversal process of thin films and the ultrafast dynamics of magnetic vortices and domain walls in confined ferromagnetic structures. Future sources of fsec short and high intense soft X-ray photon pulses hold the promise of magnetic imaging down to fundamental magnetic length and time scales.

Fischer, P.; Im, M.-Y.

2010-01-18T23:59:59.000Z

446

High Field Magnet R&D |Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

High Field Magnet R&D High Field Magnet R&D The Superconducting Magnet Division is developing advanced magnet designs and magnet-related technologies for high field accelerator magnets. We are currently working on magnets for three inter-related programs: High Field Magnets for Muon Collider Papers, Presentations Common Coil Magnets Papers, Presentations Interaction Region Magnets Papers, Presentations High Temperature Superconductor (HTS) Magnets Papers, Presentations This is part of a multi-lab superconducting magnet development program for new accelerator facilities that would be part of the U.S. High Energy Physics program. These programs (@BNL, @FNAL, @LBNL) are quite complimentary to each other, so that magnet designs and technologies developed at one laboratory can be easily transferred to another. The BNL

447

Hydro-Gravitational-Dynamics of Planets and Dark Energy  

E-Print Network (OSTI)

Self-gravitational fluid mechanical methods termed hydro-gravitational-dynamics (HGD) predict plasma fragmentation 0.03 Myr after the turbulent big bang to form protosuperclustervoids, turbulent protosuperclusters, and protogalaxies at the 0.3 Myr transition from plasma to gas. Linear protogalaxyclusters fragment at 0.003 Mpc viscous-inertial scales along turbulent vortex lines or in spirals, as observed. The plasma protogalaxies fragment on transition into white-hot planet-mass gas clouds (PFPs) in million-solar-mass clumps (PGCs) that become globular-star-clusters (GCs) from tidal forces or dark matter (PGCs) by freezing and diffusion into 0.3 Mpc halos with 97% of the galaxy mass. The weakly collisional non-baryonic dark matter diffuses to > Mpc scales and frag-ments to form galaxy cluster halos. Stars and larger planets form by binary mergers of the trillion PFPs per PGC on 0.03 Mpc galaxy accretion disks. Star deaths depend on rates of planet accretion and internal star mixing. Moderate accretion rates produce white dwarfs that evaporate surrounding gas planets by spin-radiation to form planetary nebulae before Supernova Ia events, dimming some events to give systematic distance errors misinterpreted as the dark energy hypothesis and overestimates of the universe age. Failures of standard LCDM cosmological models reflect not only obsolete Jeans 1902 fluid mechanical assumptions, but also failures of standard turbulence models that claim the cascade of turbulent kinetic energy is from large scales to small. Because turbulence is always driven at all scales by inertial-vortex forces the turbulence cascade is always from small scales to large.

Carl H. Gibson; Rudolph E. Schild

2008-08-24T23:59:59.000Z

448

Cool Magnetic Molecules  

NLE Websites -- All DOE Office Websites (Extended Search)

Cool Magnetic Molecules Cool Magnetic Molecules Cool Magnetic Molecules Print Wednesday, 25 May 2011 00:00 Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability to design, assemble, and probe the structure and chemistry of small molecules. An international collaboration of researchers from Spain, Scotland, and the U.S. has utilized ALS Beamline 11.3.1 (small-molecule crystallography) to characterize the design of such "molecular coolers." The work targets the synthesis of molecular cluster compounds containing many unpaired electrons ("nanomagnets") for applications involving enhanced magnetic refrigeration at very low temperatures.

449

Pulse magnetic welder  

DOE Patents (OSTI)

A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.

Christiansen, D.W.; Brown, W.F.

1984-01-01T23:59:59.000Z

450

Magnetic latching solenoid  

DOE Patents (OSTI)

This invention discloses a D.C. magnetic latching solenoid that retains a moving armature in a first or second position by means of a pair of magnets, thereby having a zero-power requirement after actuation. The first or second position is selected by reversing the polarity of the D.C. voltage which is enough to overcome the holding power of either magnet and transfer the armature to an opposite position. The coil is then de-energized.

Marts, Donna J. (Idaho Falls, ID); Richardson, John G. (Idaho Falls, ID); Albano, Richard K. (Idaho Falls, ID); Morrison, Jr., John L. (Idaho Falls, ID)

1995-01-01T23:59:59.000Z

451

Position regulator for spindle of milling machine by embedded magnetic bearings  

Science Conference Proceedings (OSTI)

The goal of this work is to concurrently counter-balance the dynamic cutting force and regulate the spindle position deviation by integrating active magnetic bearing (AMB) technique, fuzzy logic algorithm and an adaptive self-tuning feedback loop. The ... Keywords: Active magnetic bearing, Cutting process, Fuzzy logic algorithm

Nan-Chyuan Tsai; Li-Wen Shih; Rong-Mao Lee

2011-08-01T23:59:59.000Z

452

Magnetically leviated superconducting bearing  

DOE Patents (OSTI)

A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT)

1993-01-01T23:59:59.000Z

453

Nanostructrured Magnetic Materials  

Science Conference Proceedings (OSTI)

Aug 8, 2013 ... The demand for OFF-ON becomes increasingly important as ... The residual magnetic flux density and maximum energy product of the ...

454

Rare Earth Magnets  

Science Conference Proceedings (OSTI)

Mar 6, 2013 ... Performance and Endurance of Nd-Fe-B Sintered Magnets in E-Motor Application Conditions: Martina Moore1; Ralph Sueptitz1; Margitta ...

455

Rare Earth Magnets  

Science Conference Proceedings (OSTI)

Aug 8, 2013 ... Current high performance permanent magnets (PM) for traction motors of (hybrid) electric vehicles use substantial amount of Dy in Nd-Fe-B ...

456

Magnetic Materials and Properties  

Science Conference Proceedings (OSTI)

Aug 5, 2013 ... Following vacuum distillation of the Mg-RE alloy, 98% pure RE metals can be recovered, which are then used to synthesize permanent magnet ...

457

Effects of Combustion-Induced Vortex Breakdown on Flashback Limits of Syngas-Fueled Gas Turbine Combustors  

DOE Green Energy (OSTI)

Turbine combustors of advanced power systems have goals to achieve very low pollutants emissions, fuel variability, and fuel flexibility. Future generation gas turbine combustors should tolerate fuel compositions ranging from natural gas to a broad range of syngas without sacrificing operational advantages and low emission characteristics. Additionally, current designs of advanced turbine combustors use various degrees of swirl and lean premixing for stabilizing flames and controlling high temperature NOx formation zones. However, issues of fuel variability and NOx control through premixing also bring a number of concerns, especially combustor flashback and flame blowout. Flashback is a combustion condition at which the flame propagates upstream against the gas stream into the burner tube. Flashback is a critical issue for premixed combustor designs, because it not only causes serious hardware damages but also increases pollutant emissions. In swirl stabilized lean premixed turbine combustors onset of flashback may occur due to (i) boundary layer flame propagation (critical velocity gradient), (ii) turbulent flame propagation in core flow, (iii) combustion instabilities, and (iv) upstream flame propagation induced by combustion induced vortex breakdown (CIVB). Flashback due to first two foregoing mechanisms is a topic of classical interest and has been studied extensively. Generally, analytical theories and experimental determinations of laminar and turbulent burning velocities model these mechanisms with sufficient precision for design usages. However, the swirling flow complicates the flashback processes in premixed combustions and the first two mechanisms inadequately describe the flashback propensity of most practical combustor designs. The presence of hydrogen in syngas significantly increases the potential for flashback. Due to high laminar burning velocity and low lean flammability limit, hydrogen tends to shift the combustor operating conditions towards flashback regime. Even a small amount of hydrogen in a fuel blend triggers the onset of flashback by altering the kinetics and thermophysical characteristics of the mixture. Additionally, the presence of hydrogen in the fuel mixture modifies the response of the flame to the global effects of stretch and preferential diffusion. Despite its immense importance in fuel flexible combustor design, little is known about the magnitude of fuel effects on CIVB induced flashback mechanism. Hence, this project investigates the effects of syngas compositions on flashback resulting from combustion induced vortex breakdown. The project uses controlled experiments and parametric modeling to understand the velocity field and flame interaction leading to CIVB driven flashback.

Ahsan Choudhuri

2011-03-31T23:59:59.000Z

458

Magnetism Highlights| Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetism Magnetism SHARE Magnetism Highlights 1-5 of 5 Results ARCS maps collaborative magnetic spin behavior in iron telluride December 01, 2011 - Researchers have long thought that magnetism and superconductivity are mutually exclusive. The former typically involves localized atomic electrons. The latter requires freely propagating, itinerant electrons. Unexpected Magnetic Excitations in Doped Insulator Surprise Researchers October 01, 2011 - When doping a disordered magnetic insulator material with atoms of a nonmagnetic material, the conventional wisdom is that the magnetic interactions between the magnetic ions in the material will be weakened. Neutron Analysis Reveals Unique Atomic-Scale Behavior of "Cobalt Blue" September 01, 2011 - Neutron scattering studies of "cobalt blue," a

459

Micromagnetics of the Dynamic Susceptibility for Coupled Permalloy Stripes  

E-Print Network (OSTI)

The dynamic susceptibility of arrays of narrow permalloy stripes (9 mm several m 200 nm) has been investigated using a single-coil broadband susceptibility spectrometer. Disagreement is observed between experimental results and the macroscopic Landau-Lifshitz (LL) model. This model does not take into account the dipolar interaction between magnetic stripes. We have performed micromagnetic calculations that include these dipolar interactions, and have found the resulting frequency dependence of the dynamic susceptibility in the linear regime to be in good agreement with our experimental data. 1 I. INTRODUCTION Fine control of the magnetic susceptibility in the high frequency range (100 MHz { 10 GHz) is required for many industrial applications. For example, obtaining short switching times for magnetic recording applications requires high cut-o frequencies of the real part of the dynamic susceptibility. For other applications, such as microwave devices, ne control of th...

O. Gerardin; J. Ben Youssef; H. Le Gall; N. Vukadinovic; P. M. Jacquart; M. J. Donahue

2000-01-01T23:59:59.000Z

460

BEPC-II Magnet Project | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

BEPC-II Magnet Project BEPC-II Magnet Project Project Overview The BEPC-II magnets are Interaction Region magnets to be used as part of an upgrade to the Beijing Electron Positron Collider. Two magnets will be produced, both of which will be inserted within the solenoidal detector at one of the collision points. Since the best use of the quadrupole focusing in this case requires placing the magnet as close to the collision point as possible, these magnets will be used within the magnetic field of the detector. This constrains the materials that can be used for construction to only non-magnetic materials. It also places severe demands on the structure of the magnet and it's holding supports due to the reaction forces between the solenoid and the magnet. To create the coil pattern for the final magnet, the coils will be

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461

Combined passive magnetic bearing element and vibration damper  

DOE Patents (OSTI)

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium and dampen transversely directed vibrations. Mechanical stabilizers are provided to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. In a improvement over U.S. Pat. No. 5,495,221, a magnetic bearing element is combined with a vibration damping element to provide a single upper stationary dual-function element. The magnetic forces exerted by such an element, enhances levitation of the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations, and suppresses the effects of unbalance or inhibits the onset of whirl-type rotor-dynamic instabilities. Concurrently, this equilibrium is made stable against displacement-dependent drag forces of the rotating object from its equilibrium position.

Post, Richard F. (Walnut Creek, CA)

2001-01-01T23:59:59.000Z

462

Avalanches through windows: Multiscale visualization in magnetic thin films  

E-Print Network (OSTI)

Avalanches through windows: Multiscale visualization in magnetic thin films Alessandro Magni dynamics, but are strongly dependent on the size of the windows chosen. Here we investigate how to properly sub-window of the entire sample. Usually, windows of varying sizes are used, and the distributions

Sethna, James P.

463

Magnetic Reconnection in Plasmas: a Celestial Phenomenon in the Laboratory  

E-Print Network (OSTI)

Solar Wind affects the Earth's environment Space Weather #12;The Earth's Magnetic Shield Before perturbation #12;Coronal Mass Ejections The most powerful explosions in our solar system Can power the US · Conclusions Outline #12;Coronal Mass Ejections Movie from NASA's Solar Dynamics Observatory (SDO) #12;The

464

Passive magnetic bearing configurations  

Science Conference Proceedings (OSTI)

A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

Post, Richard F. (Walnut Creek, CA)

2011-01-25T23:59:59.000Z

465

EXOTIC MAGNETS FOR ACCELERATORS.  

SciTech Connect

Over the last few years, several novel magnet designs have been introduced to meet the requirements of new, high performance accelerators and beam lines. For example, the FAIR project at GSI requires superconducting magnets ramped at high rates ({approx} 4 T/s) in order to achieve the design intensity. Magnets for the RIA and FAIR projects and for the next generation of LHC interaction regions will need to withstand high doses of radiation. Helical magnets are required to maintain and control the polarization of high energy protons at RHIC. In other cases, novel magnets have been designed in response to limited budgets and space. For example, it is planned to use combined function superconducting magnets for the 50 GeV proton transport line at J-PARC to satisfy both budget and performance requirements. Novel coil winding methods have been developed for short, large aperture magnets such as those used in the insertion region upgrade at BEPC. This paper will highlight the novel features of these exotic magnets.

WANDERER, P.

2005-09-18T23:59:59.000Z

466

Excursions in Chemical Dynamics  

E-Print Network (OSTI)

2009). [118] F. A. Cotton, Chemical Applications of GroupExcursions in Chemical Dynamics by Shervin Fatehi AFall 2010 Excursions in Chemical Dynamics Copyright 2010 by

Fatehi, Shervin

2010-01-01T23:59:59.000Z

467

Study of gas flow dynamics in porous and granular media with laser-polarized ¹²?Xe NMR  

E-Print Network (OSTI)

This thesis presents Nuclear Magnetic Resonance (NMR) studies of gas flow dynamics in porous and granular media by using laser-polarized ¹²?Xe . Two different physical processes, the gas transport in porous rock cores and ...

Wang, Ruopeng, 1972-

2005-01-01T23:59:59.000Z

468

Design, synthesis, and characterization of conjugated polymers and functional paramagnetic materials for dynamic nuclear polarization  

E-Print Network (OSTI)

The design, synthesis, and characterization of a series of radicals and biradicals for use as dynamic nuclear polarization (DNP) agents is described. DNP is a method to enhance the S/N-ratio in solid-state nuclear magnetic ...

Dane, Eric Lawrence

2010-01-01T23:59:59.000Z

469

Development of new parameters for structure determination and dynamic investigations on biomacromolecules by NMR  

E-Print Network (OSTI)

Nuclear magnetic resonance (NMR) spectroscopy is unique in the content of structural as well as dynamic information that it can provide at atomic resolution. The aim of this PhD-thesis was to contribute to the understanding ...

Duchardt, Elke, 1975-

2005-01-01T23:59:59.000Z

470

Magnetization of neutron star matter  

E-Print Network (OSTI)

The magnetization of neutron star matter in magnetic fields is studied by employing the FSUGold interaction. It is found that the magnetic susceptibilities of the charged particles (proton, electron and muon) can be larger than that of neutron. The effects of the anomalous magnetic moments (AMM) of each component on the magnetic susceptibility are examined in detail. It is found that the proton and electron AMM affect their respective magnetic susceptibility evidently in strong magnetic fields. In addition, they are the protons instead of the electrons that contribute most significantly to the magnetization of the neutron star matter in a relative weak magnetic field, and the induced magnetic field due to the magnetization can be appear to be very large. Finally, the effect of the density-dependent symmetry energy on the magnetization is discussed.

Dong, Jianmin; Gu, Jianzhong

2013-01-01T23:59:59.000Z