Science.gov

Sample records for magnetic body forces

  1. Probing Gravitational Sensitivity in Biological Systems Using Magnetic Body Forces

    NASA Technical Reports Server (NTRS)

    Guevorkian, Karine; Wurzel, Sam; Mihalusova, Mariana; Valles, Jim

    2003-01-01

    At Brown University, we are developing the use of magnetic body forces as a means to simulate variable gravity body forces on biological systems. This tool promises new means to probe gravi-sensing and the gravi-response of biological systems. It also has the potential as a technique for screening future systems for space flight experiments.

  2. Interaction Forces Between Multiple Bodies in a Magnetic Field

    NASA Technical Reports Server (NTRS)

    Joffe, Benjamin

    1996-01-01

    Some of the results from experiments to determine the interaction forces between multiple bodies in a magnetic field are presented in this paper. It is shown how the force values and the force directions depend on the configuration of the bodies, their relative positions to each other, and the vector of the primary magnetic field. A number of efficient new automatic loading and assembly machines, as well as manipulators and robots, have been created based on the relationship between bodies and magnetic fields. A few of these patented magnetic devices are presented. The concepts involved open a new way to design universal grippers for robot and other kinds of mechanisms for the manipulation of objects. Some of these concepts can be used for space applications.

  3. Lorentz Body Force Induced by Traveling Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.

    2003-01-01

    The Lorentz force induced by a traveling magnetic field (TMF) in a cylindrical container has been calculated. The force can be used to control flow in dectrically conducting melts and the direction of the magnetic field and resulting flow can be reversed. A TMF can be used to partially cancel flow driven by buoyancy. The penetration of the field into the cylinder decreases as the frequency increases, and there exists an optimal value of frequency for which the resulting force is a maximum. Expressions for the Lorentz force in the limiting cases of low frequency and infinite cylinder are also given and compared to the numerical calculations.

  4. Nonlinear oscillation of a rigid body over high- Tc superconductors supported by electro-magnetic forces

    NASA Astrophysics Data System (ADS)

    Sugiura, T.; Ogawa, S.; Ura, H.

    2005-10-01

    Characteristics of high- Tc superconducting levitation systems are no contact support and stable levitation without control. They can be applied to supporting mechanisms in machines, such as linear-drives and magnetically levitated trains. But small damping due to noncontact support and nonlinearity in the magnetic force can easily cause complicated phenomena of nonlinear dynamics. This research deals with nonlinear oscillation of a rigid bar supported at its both ends by electro-magnetic forces between superconductors and permanent magnets as a simple modeling of the above application. Deriving the equation of motion, we discussed an effect of nonlinearity in the magnetic force on dynamics of the levitated body: occurrence of combination resonance in the asymmetrical system. Numerical analyses and experiments were also carried out, and their results confirmed the above theoretical prediction.

  5. On the "force-free surface " of the magnetized celestial bodies

    E-print Network

    Epp, V

    2015-01-01

    The field of a uniformly magnetized rotating sphere is studied with special attention to the surface where the electric and magnetic fields are orthogonal to each other. The equation of this surface, valid at arbitrary distances from the rotating magnetized sphere, is obtained. Inside the light cylinder this surface can be considered as a force-free surface, i.e. as a place where the particles with strong radiation damping can be trapped due to their energy loss. Outside the light cylinder this surface makes just a geometric locus which moves with a superlight velocity around the axis of rotation. The 2- and 3-dimensional plots of the force-free surface are constructed. Estimation of influence of the centrifugal force on the particle dynamics is made. It is shown, that in case of strong magnetic field the centrifugal force is negligible small everywhere except a narrow neighbourhood of the light cylinder.

  6. Three-body forces

    SciTech Connect

    Friar, J.L.

    1982-01-01

    Three-body forces are defined and their properties discussed. Evidence for such forces in the trinucleon bound states and scattering reactions is reviewed. The binding energy defects of the trinucleon bound states, the /sup 3/He charge density, the Phillips line for doublet n-d scattering lengths, and three-nucleon breakup reactions are discussed, together with the possible influence of three-body forces on these observables.

  7. Magnetic Forces, and Devices

    E-print Network

    Cruz-Pol, Sandra L.

    /10/spintronics-discover-could-lead-to- magnetic-batteries.php Applica'ons Motors Transformers MRI current element Forces on a Charge EQFe = Analogous to the electric force: We have magnetic Torque on a Current Loop in a Magnetic Field CD Motor Magne'c Torque and Moment The torque

  8. Casimir force on amplifying bodies

    E-print Network

    Agnes Sambale; Dirk-Gunnar Welsch; Stefan Yoshi Buhmann; Ho Trung Dung

    2009-02-23

    Based on a unified approach to macroscopic QED that allows for the inclusion of amplification in a limited space and frequency range, we study the Casimir force as a Lorentz force on an arbitrary partially amplifying system of linearly locally responding (isotropic) magnetoelectric bodies. We demonstrate that the force on a weakly polarisable/magnetisable amplifying object in the presence of a purely absorbing environment can be expressed as a sum over the Casimir--Polder forces on the excited atoms inside the body. As an example, the resonant force between a plate consisting of a dilute gas of excited atoms and a perfect mirror is calculated.

  9. Magnetic force microscopy

    PubMed Central

    Passeri, Daniele; Dong, Chunhua; Reggente, Melania; Angeloni, Livia; Barteri, Mario; Scaramuzzo, Francesca A; De Angelis, Francesca; Marinelli, Fiorenzo; Antonelli, Flavia; Rinaldi, Federica; Marianecci, Carlotta; Carafa, Maria; Sorbo, Angela; Sordi, Daniela; Arends, Isabel WCE; Rossi, Marco

    2014-01-01

    Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells. PMID:25050758

  10. Modeling the Sedimentation of Red Blood Cells in Flow under Strong External Magnetic Body Force using a Lattice Boltzmann Fictitious Domain Method

    SciTech Connect

    Shi, Xing; Lin, Guang

    2014-11-01

    To model the sedimentation of the red blood cell (RBC) in a square duct and a circular pipe, the recently developed technique derived from the lattice Boltzmann method and the distributed Lagrange multiplier/fictitious domain method (LBM-DLM/FD) is extended to employ the mesoscopic network model for simulations of the sedimentation of the RBC in flow. The flow is simulated by the lattice Boltzmann method with a strong magnetic body force, while the network model is used for modeling RBC deformation. The fluid-RBC interactions are enforced by the Lagrange multiplier. The sedimentation of the RBC in a square duct and a circular pipe is simulated, revealing the capacity of the current method for modeling the sedimentation of RBC in various flows. Numerical results illustrate that that the terminal setting velocity increases with the increment of the exerted body force. The deformation of the RBC has significant effect on the terminal setting velocity due to the change of the frontal area. The larger the exerted force is, the smaller the frontal area and the larger deformation of the RBC are.

  11. Magnetic Force Microscopy in Liquids.

    PubMed

    Ares, Pablo; Jaafar, Miriam; Gil, Adriana; Gómez-Herrero, Julio; Asenjo, Agustina

    2015-09-01

    In this work, the use of magnetic force microscopy (MFM) to acquire images of magnetic nanostructures in liquid environments is presented. Optimization of the MFM signal acquisition in liquid media is performed and it is applied to characterize the magnetic signal of magnetite nanoparticles. The ability for detecting magnetic nanostructures along with the well-known capabilities of atomic force microscopy in liquids suggests potential applications in fields such as nanomedicine, nanobiotechnology, or nanocatalysis. PMID:26150330

  12. PAMM header will be provided by the publisher Magnetic Force Formulae for Magnets at Small Distances

    E-print Network

    Popovic, Nikola

    PAMM header will be provided by the publisher Magnetic Force Formulae for Magnets at Small-04103 Leipzig, Germany In [7], the magnetic force on subregions of rigid magnetized bodies was studied on the underlying crystalline lattice structure L. It originates from contributions of magnetic dipole

  13. Identification and reconstruction of elastic body forces

    NASA Astrophysics Data System (ADS)

    Alves, Carlos J. S.; Martins, Nuno F. M.; Roberty, Nilson C.

    2014-05-01

    We address the identification and reconstruction of 2D elastostatic and elastodynamic body forces from pairs of displacement and traction boundary data. As in the scalar acoustic case, an elastic body force cannot be fully identified from a single boundary measurement. We present some partial identification results for a single and multiple boundary measurements. We show that full identification can be obtained by considering boundary measurements along a full set of frequencies. We present and test two numerical methods for retrieving the body force.

  14. Magnetic Resonance Force Microscope Development

    SciTech Connect

    Hammel, P.C.; Zhang, Z.; Suh, B.J.; Roukes, M.L.; Midzor, M.; Wigen, P.E.; Childress, J.R.

    1999-06-03

    Our objectives were to develop the Magnetic Resonance Force Microscope (MRFM) into an instrument capable of scientific studies of buried structures in technologically and scientifically important electronic materials such as magnetic multilayer materials. This work resulted in the successful demonstration of MRFM-detected ferromagnetic resonance (FMR) as a microscopic characterization tool for thin magnetic films. Strong FMR spectra obtained from microscopic Co thin films (500 and 1000 angstroms thick and 40 x 200 microns in lateral extent) allowed us to observe variations in sample inhomogeneity and magnetic anisotropy field. We demonstrated lateral imaging in microscopic FMR for the first time using a novel approach employing a spatially selective local field generated by a small magnetically polarized spherical crystallite of yttrium iron garnet. These successful applications of the MRFM in materials studies provided the basis for our successful proposal to DOE/BES to employ the MRF M in studies of buried interfaces in magnetic materials.

  15. An assessment of body force representations for compressor stall simulation

    E-print Network

    Kerner, Jonathan (Jonathan H.)

    2010-01-01

    This thesis examines an axial compressor body force representation constructed from 3D CFD calculations. The radial distribution of body forces is compared to that of a body force representation based on axisymmetric ...

  16. Three-body critical Casimir forces

    E-print Network

    T. G. Mattos; L. Harnau; S. Dietrich

    2015-03-03

    Within mean-field theory we calculate universal scaling functions associated with critical Casimir forces for a system consisting of three parallel cylindrical colloids immersed in a near-critical binary liquid mixture. For several geometrical arrangements and boundary conditions at the surfaces of the colloids we study the force between two colloidal particles along their center-to-center axis, analyzing the influence of the presence of a third particle on that force. Upon changing temperature or the relative positions of the particles we observe interesting features such as a change of sign of this force caused by the presence of the third particle. We determine the three-body component of the forces acting on one of the colloids by subtracting the pairwise forces from the total force. The three-body contribution to the total critical Casimir force turns out to be more pronounced for small surface-to-surface distances between the colloids as well as for temperatures close to criticality. Moreover we compare our results with similar ones for other physical systems such as three atoms interacting via van der Waals forces.

  17. Investigation of a cuboidal permanent magnet’s force exerted on a robotic capsule

    PubMed Central

    Yang, Wan’an; Tang, Chengbing; Qin, Fengqing

    2014-01-01

    To control and drive a robotic capsule accurately from outside a patient’s body, we present a schema in which the capsule enclosing the imaging device, circuits, batteries, etc is looped by a permanent magnet ring that acts as an actuator. A cuboidal permanent magnet situated outside the patient’s body attracts or pushes the magnet ring from different directions to make the capsule move or rotate. A mathematic model of attractive or repulsive force that the cuboidal magnet exerts on the magnet ring is presented for accurate calculation of force. The experiments showed that the measuring force was in agreement with the theoretical one, and the relations between the dimensions of the cuboidal magnet and force are useful to produce a cuboidal magnet with optimal shape to get appropriate force. PMID:25170283

  18. Cryogenic magnetic force microscope M. Rosemana)

    E-print Network

    Grütter, Peter

    Cryogenic magnetic force microscope M. Rosemana) and P. Gru¨tter Centre for the Physics for publication 27 June 2000 We describe our cryogenic magnetic force microscope, operating between 4.2 and 300 K

  19. Three Body Force in Peripheral $N?$ Scattering

    E-print Network

    R. Higa; M. R. Robilotta

    1999-08-19

    The exchange of a single pion does not contribute to $N\\alpha$ scattering, due to the isoscalar nature of the target. Therefore peripheral $N\\alpha$ scattering may be used to probe existing models for the two-pion exchange component of the $NN$ potential. In a recent work we have considered this possibility using an effective $N\\alpha$ interaction based on two-body forces only. In the present communication we discuss the role played by the two-pion exchange three-nucleon force, since its range is comparable to the two-pion exchange potential (TPEP).

  20. Optimizing magnetization orientation of permanent magnets for maximal gradient force

    NASA Astrophysics Data System (ADS)

    Kruusing, Arvi

    2001-09-01

    The force exercised on a permanent magnet (PM) in a nonuniform field (gradient force) is dependent on the magnetization orientation of the magnet. In this paper, it is shown theoretically that the gradient force is greatest when the magnetization through the magnet, or at least at its surface, is collinear with the external field. The formulae for calculating the force between an axis-symmetric optimal magnet and a coaxial axis-symmetric coil are presented. Using the finite element method (FEM), calculations of the magnetic field distribution of an optimal cylindrical magnet and some its approximations are performed. The forces between these magnets and a pancake coil are computed and compared. For a system consisting of a magnet with a height of 1 unit and a diameter of 2 units and magnetization invariant in field and an annular pancake coil with a diameter of 2.4 units, a thickness of 0.2 units, an inner diameter of 0.4 units and a distance from the magnet of 0.2 units, the force on the optimal magnet was 1.44 times greater than the force on an axially magnetized magnet of the same size and magnetization magnitude. The optimal magnetization may be approximated by magnetization inclined at a constant angle to the axis and by a combination of axially and radially magnetized sections. With magnetization at a constant angle to the axis in the axis plane, the force was greatest when the angle was about 45°, being 1.38-fold compared to the force on an axially magnetized magnet. When the magnet was composed of an axially magnetized cylindrical core and a radially magnetized outer ring, the force was greatest when the volume of the core was approximately equal to the volume of the ring, being 1.26-fold compared to the force on an axially magnetized magnet. The optimal magnet and its approximations also provided a reduced stray field. A short review of methods of the fabrication of permanent magnets (PMs) with a continuous variation of the magnetization orientation and with radial magnetization orientation is given. The results of this study can be used to design linear electromagnetic (micro)actuators.

  1. Force sensor using changes in magnetic flux

    NASA Technical Reports Server (NTRS)

    Pickens, Herman L. (Inventor); Richard, James A. (Inventor)

    2012-01-01

    A force sensor includes a magnetostrictive material and a magnetic field generator positioned in proximity thereto. A magnetic field is induced in and surrounding the magnetostrictive material such that lines of magnetic flux pass through the magnetostrictive material. A sensor positioned in the vicinity of the magnetostrictive material measures changes in one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux.

  2. Equivalent body-force model for magnetostrictive transduction in EMATs

    NASA Astrophysics Data System (ADS)

    Nagy, Peter B.; Ribichini, Remo

    2015-03-01

    Electromagnetic Acoustic Transducers (EMATs) are an attractive alternative to standard piezoelectric probes in those applications where couplant fluid cannot be used, i.e. high speed or high temperature testing, or when specific wave-modes have to be excited. When used on ferromagnetic samples, EMATs generate elastic waves through three different transduction mechanisms: the Lorentz force, the magnetization force and magnetostriction. The modeling of such phenomena has drawn the attention of several researchers, leading to different physical formalizations, especially for magnetostriction, being the most complex mechanism. This work presents a physics-based model for tangential bias field magnetostrictive EMATs employing surface tractions equivalent to the inertia body forces caused by magnetostrictive strains. This type of modeling had been previously used to validate a Finite Element model for normal bias field EMATs and here is extended to the tangential bias field configuration. Moreover, it is shown that the proposed model is equivalent to a recently developed method using the spatial convolution integral of body forces with Green's tensor to model elastic wave generation in a solid half-space.

  3. Verifying Magnetic Force on a Conductor

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2011-01-01

    The laboratory measurement of the magnetic force acting on a straight wire of length "l" carrying a current of intensity "i" in a magnetic field "B" is usually made using current balances, which are offered by various physics apparatus suppliers' catalogues. These balances require an adequate magnet and commonly allow only the measurement of the…

  4. 7/15 Force current 1/7 FORCE ON A CURRENT IN A MAGNETIC FIELD

    E-print Network

    Gustafsson, Torgny

    7/15 Force current 1/7 FORCE ON A CURRENT IN A MAGNETIC FIELD PURPOSE: To study the force exerted in a magnetic field B, it experiences a magnetic force, called the Lorentz force, F qvBsin , (1) which results of the electrons with the ions, the wire itself experiences a magnetic force due to the interaction of the current

  5. Superconducting magnets for whole body magnetic resonance imaging

    SciTech Connect

    Murphy, M.F.

    1989-03-01

    Superconducting magnets have achieved preeminence in the magnetic resonance imaging (MRI) industry. Further growth in this market will depend on reducing system costs, extending medical applications, and easing the present siting problem. New magnet designs from Oxford address these issues. Compact magnets are economical to build and operate. Two 4 Tesla whole body magnets for research in magnetic resonance spectroscopy (MRS) are now in operation. Active-Shield magnets, by drastically reducing the magnetic fringe fields, will allow MRI systems with superconducting magnets to be located in previously inaccessible sites.

  6. Magnetic force and work: an accessible example

    NASA Astrophysics Data System (ADS)

    Gates, Joshua

    2014-05-01

    Despite their physics instructors’ arguments to the contrary, introductory students can observe situations in which there seems to be compelling evidence for magnetic force doing work. The counterarguments are often highly technical and require physics knowledge beyond the experience of novice students, however. A simple example is presented which can illustrate that all may not be what it seems when energy transfer and the magnetic force are involved. Excel and Python simulations of the process are also provided.

  7. Current-modulating magnetic force microscope probe

    SciTech Connect

    Wang, Frank Z.; Helian, Na; Clegg, Warwick W; Windmill, James F. C.; Jenkins, David

    2001-06-01

    A new current-modulating probe for the magnetic force microscope (MFM) is proposed in this article. The magnetic field, which will be used to interact with a magnetic specimen{close_quote}s stray field, is induced on the sharp tip of the conical magnetic core surrounded by a microfabricated single turn conductive coil. The reciprocity principle is used to obtain the force acting on the probe due to the specimen{close_quote}s stray field when scanned over a magnetic specimen. The magnetic field intensity is adjustable by control of the applied current. Images of specimens have been modeled using this probe. The suitability to different specimens is seen to be the biggest advantage of this scheme over the conventional probe designs. {copyright} 2001 American Institute of Physics.

  8. Dual integrals in small strain elasticity with body forces

    NASA Astrophysics Data System (ADS)

    Lubarda, Vlado A.; Markenscoff, Xanthippi

    2008-01-01

    Dual integrals of small strain elasticity are derived and related to the energy release rates associated with a defect motion in the presence of body forces. A modified energy momentum tensor is used, which includes a work term due to body forces, and which yields simple expressions for the configurational forces in terms of the J, L, and M integrals. Since the complementary potential energy does not include body forces explicitly, the complementary energy momentum tensor has the same structure as in the elasticity without body forces. The expressions for the nonconserved J, L, and M integrals, and their duals, are related to the volume integrals whose integrands depend on body forces and their gradients. If body forces are spatially uniform, the conservation laws J=J=0 hold for both 2D and 3D problems, and L=L=0 for the antiplane strain problems. The conservation law M=Mˆ=0 holds if body forces are absent, or if they are homogeneous functions of particular degree in spatial coordinates. To cite this article: V.A. Lubarda, X. Markenscoff, C. R. Mecanique 336 (2008).

  9. Levitation forces in bearingless permanent magnet motors

    SciTech Connect

    Amrhein, W.; Silber, S.; Nenninger, K.

    1999-09-01

    Bearingless motors combine brushless AC-motors with active magnetic bearings by the integration of two separate winding systems (torque and radial levitation force windings with different pole pairs) in one housing. This paper gives an insight into the influences of the motor design on the levitation force and torque generation. It is shown that especially for machines with small air gaps it can be very important to choose the right design parameters. Increasing the permanent magnet height in order to increase the motor torque can result in a remarkable reduction of radial forces. The interrelationships are discussed on the basis of Maxwell and Lorentz forces acting upon the stator surface. The investigations are presented for a bearingless low cost motor, suited for pump, fan or blower applications. The presented motor needs only four coils for operation.

  10. Treatment of body forces in boundary element design sensitivity analysis

    NASA Technical Reports Server (NTRS)

    Saigal, Sunil; Kane, James H.; Aithal, R.; Cheng, Jizu

    1989-01-01

    The inclusion of body forces has received a good deal of attention in boundary element research. The consideration of such forces is essential in the desgin of high performance components such as fan and turbine disks in a gas turbine engine. Due to their critical performance requirements, optimal shapes are often desired for these components. The boundary element method (BEM) offers the possibility of being an efficient method for such iterative analysis as shape optimization. The implicit-differentiation of the boundary integral equations is performed to obtain the sensitivity equations. The body forces are accounted for by either the particular integrals for uniform body forces or by a surface integration for non-uniform body forces. The corresponding sensitivity equations for both these cases are presented. The validity of present formulations is established through a close agreement with exact analytical results.

  11. One-Piece Force-Transducer Body

    NASA Technical Reports Server (NTRS)

    Meyer, R. A.

    1986-01-01

    Rugged unit designed to operate in severe environment. Forcetransducer body designed for measurement of loads on specimens tested in hydrogen gas at temperatures up to 2,000 degree F (1,090 degree C). Body has symmetrical radial-shear-beam configuration and machined in one piece from bar stock.

  12. The effect of magnetophoresis and Brownian diffusion on the levitation of bodies in a magnetic fluid

    NASA Astrophysics Data System (ADS)

    Bashtovoi, V. G.; Polevikov, V. K.; Suprun, A. E.; Stroots, A. V.; Beresnev, S. A.

    2008-06-01

    New aspects related to the redistribution of magnetic particles concentration in a magnetic fluid caused by magnetophoresis and Brownian diffusion in a nonuniform magnetic field are considered. These aspects deal with the influence of these processes on the pressure redistribution and levitation of bodies in a magnetic fluid. It is shown that due to these processes the pressure force acting on bodies changes significantly with time and can be reduced dozens of percent if compared to a homogenous fluid. Figs 5, Refs 5.

  13. Magnetic Force and Work: An Accessible Example

    ERIC Educational Resources Information Center

    Gates, Joshua

    2014-01-01

    Despite their physics instructors' arguments to the contrary, introductory students can observe situations in which there seems to be compelling evidence for magnetic force doing work. The counterarguments are often highly technical and require physics knowledge beyond the experience of novice students, however. A simple example is presented…

  14. Dynamical friction force exerted on spherical bodies

    E-print Network

    O. Esquivel; B. Fuchs

    2007-04-30

    We present a rigorous calculation of the dynamical friction force exerted on a spherical massive perturber moving through an infinite homogenous system of field stars. By calculating the shape and mass of the polarization cloud induced by the perturber in the background system, which decelerates the motion of the perturber, we recover Chandrasekhar's drag force law with a modified Coulomb logarithm. As concrete examples we calculate the drag force exerted on a Plummer sphere or a sphere with the density distribution of a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.

  15. Magnetic Forces and DNA Mechanics in Multiplexed Magnetic Tweezers

    PubMed Central

    van Loenhout, Marijn T. J.; Burnham, Daniel R.; Dekker, Cees

    2012-01-01

    Magnetic tweezers (MT) are a powerful tool for the study of DNA-enzyme interactions. Both the magnet-based manipulation and the camera-based detection used in MT are well suited for multiplexed measurements. Here, we systematically address challenges related to scaling of multiplexed magnetic tweezers (MMT) towards high levels of parallelization where large numbers of molecules (say 103) are addressed in the same amount of time required by a single-molecule measurement. We apply offline analysis of recorded images and show that this approach provides a scalable solution for parallel tracking of the xyz-positions of many beads simultaneously. We employ a large field-of-view imaging system to address many DNA-bead tethers in parallel. We model the 3D magnetic field generated by the magnets and derive the magnetic force experienced by DNA-bead tethers across the large field of view from first principles. We furthermore experimentally demonstrate that a DNA-bead tether subject to a rotating magnetic field describes a bicircular, Limaçon rotation pattern and that an analysis of this pattern simultaneously yields information about the force angle and the position of attachment of the DNA on the bead. Finally, we apply MMT in the high-throughput investigation of the distribution of the induced magnetic moment, the position of attachment of DNA on the beads, and DNA flexibility. The methods described herein pave the way to kilo-molecule level magnetic tweezers experiments. PMID:22870220

  16. Modeling Forces on the Human Body.

    ERIC Educational Resources Information Center

    Pagonis, Vasilis; Drake, Russel; Morgan, Michael; Peters, Todd; Riddle, Chris; Rollins, Karen

    1999-01-01

    Presents five models of the human body as a mechanical system which can be used in introductory physics courses: human arms as levers, humans falling from small heights, a model of the human back, collisions during football, and the rotating gymnast. Gives ideas for discussions and activities, including Interactive Physics (TM) simulations. (WRM)

  17. Forces and moments on a slender, cavitating body

    SciTech Connect

    Hailey, C.E.; Clark, E.L.; Buffington, R.J.

    1988-01-01

    Recently a numerical code has been developed at Sandia National Laboratories to predict the pitching moment, normal force, and axial force of a slender, supercavitating shape. The potential flow about the body and cavity is calculated using an axial distribution of source/sink elements. The cavity surface is assumed to be a constant pressure streamline, extending beyond the base of the model. Slender body approximation is used to model the crossflow for small angles of attack. A significant extension of previous work in cavitation flow is the inclusion of laminar and turbulent boundary layer solutions on the body. Predictions with this code, for axial force at zero angle of attack, show good agreement with experiments. There are virtually no published data availble with which to benchmark the pitching moment and normal force predictions. An experiment was designed to measure forces and moments on a supercavitation shape. The primary reason for the test was to obtain much needed data to benchmark the hydrodynamic force and moment predictions. Since the numerical prediction is for super cavitating shapes at very small cavitation numbers, the experiment was designed to be a ventilated cavity test. This paper describes the experimental procedure used to measure the pitching moment, axial and normal forces, and base pressure on a slender body with a ventilated cavity. Limited results are presented for pitching moment and normal force. 5 refs., 7 figs.

  18. Magnetic force on a magnetic particle within a high gradient magnetic separator

    NASA Astrophysics Data System (ADS)

    Baik, S. K.; Ha, D. W.; Kwon, J. M.; Lee, Y. J.; Ko, R. K.

    2013-01-01

    HGMS (High Gradient Magnetic Separator) uses matrix to make high magnetic field gradient so that ferro- or para-magnetic particles can be attracted to them by high magnetic force. The magnetic force generated by the field gradient is several thousand times larger than that by background magnetic field alone. So the HGMS shows excellent performance compared with other magnetic separators. These matrixes are usually composed of stainless steel wires having high magnetization characteristics. This paper deals with superconducting HGMS which is aimed for purifying waste water by using stainless steel matrix. Background magnetic field up to 6 T is generated by a superconducting solenoid and the stainless steel matrixes are arranged inside of the solenoid. Based on magnetic field calculated by FEM (Finite Element Method), we could calculate magnetic force acting on a magnetic particle such as hematite and maghemite consisting of major impurities in the condenser water of a thermal power station.

  19. MICROFLARE ACTIVITY DRIVEN BY FORCED MAGNETIC RECONNECTION

    SciTech Connect

    Jess, D. B.; Mathioudakis, M.; Crockett, P. J.; Keenan, F. P.; Browning, P. K.

    2010-03-20

    High cadence, multiwavelength, optical observations of a solar active region, obtained with the Swedish Solar Telescope, are presented. Two magnetic bright points are seen to separate in opposite directions at a constant velocity of 2.8 km s{sup -1}. After a separation distance of {approx}4400 km is reached, multiple Ellerman bombs are observed in both H{alpha} and Ca-K images. As a result of the Ellerman bombs, periodic velocity perturbations in the vicinity of the magnetic neutral line, derived from simultaneous Michelson Doppler Imager data, are generated with amplitude {+-}6 km s{sup -1} and wavelength {approx}1000 km. The velocity oscillations are followed by an impulsive brightening visible in H{alpha} and Ca-K, with a peak intensity enhancement of 63%. We interpret these velocity perturbations as the magnetic field deformation necessary to trigger forced reconnection. A time delay of {approx}3 minutes between the H{alpha}-wing and Ca-K observations indicates that the observed magnetic reconnection occurs at a height of {approx}200 km above the solar surface. These observations are consistent with theoretical predictions and provide the first observational evidence of microflare activity driven by forced magnetic reconnection.

  20. Nonlinear regimes of forced magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Vekstein, G.; Kusano, K.

    2015-09-01

    This letter presents a self-consistent description of nonlinear forced magnetic reconnection in Taylor's model of this process. If external boundary perturbation is strong enough, nonlinearity in the current sheet evolution becomes important before resistive effects come into play. This terminates the current sheet shrinking that takes place at the linear stage and brings about its nonlinear equilibrium with a finite thickness. Then, in theory, this equilibrium is destroyed by a finite plasma resistivity during the skin-time, and further reconnection proceeds in the Rutherford regime. However, realization of such a scenario is unlikely because of the plasmoid instability, which is fast enough to develop before the transition to the Rutherford phase occurs. The suggested analytical theory is entirely different from all previous studies and provides proper interpretation of the presently available numerical simulations of nonlinear forced magnetic reconnection.

  1. Dynamical friction force exerted on spherical bodies

    NASA Astrophysics Data System (ADS)

    Esquivel, O.; Fuchs, B.

    2008-12-01

    Following a wave-mechanical treatment we calculate the drag force exerted by an infinite homogeneous background of stars on a perturber as it makes its way through the system. We recover Chandrasekhar's classical dynamical friction (DF) law with a modified Coulomb logarithm. We take into account a range of models that encompasses all plausible density distributions for satellite galaxies by considering the DF exerted on a Plummer sphere and a perturber having a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.

  2. Magnetic-enhanced normal force of magnetorheological fluids

    NASA Astrophysics Data System (ADS)

    Yao, Xing-Yan; Yu, Miao; Fu, Jie

    2015-03-01

    In this study, the static and dynamic normal forces of magnetorheological (MR) fluids with and without shearing were investigated by using an advanced commercial rheometer. The effects of time history, shear rate, and temperature under sweeping magnetic field on the normal force of MR fluids were systematically studied. Moreover, the influence of shear stress, gap distance, and the comparison of static and dynamic normal force in various magnetic field were also studied. The experimental results indicated that the normal force of MR fluids largely depend on magnetic field, more than 170% normal force increased when the magnetic field increases from 0 to 1 T. This behavior can be regard as the magnetic field-dependent of normal force, moreover, the mechanism of interaction between the magnetic field and normal force was investigated by microstructure analysis. The results show that the gap distance changes step-wise with increasing the magnetic field instead of continue increase. When imposing shearing, three regions can be found in the relationship between normal forces and shear rate, the normal force first decreases to a minimum value and then increases by increasing shear rates. The temperature effect of the normal forces is also measured and the normal force would increase with increasing of temperature. Comparing between with static and dynamic normal force shows that the dynamic normal force is larger than static normal force. And the average normal force is also larger than the shear stress. Finally, a normal force was calculated based on the magnetic field energy theory.

  3. Novel magnetic tips developed for the switching magnetization magnetic force microscopy.

    SciTech Connect

    Cambel, V.; Elias, P.; Gregusova, D.; Fedor, J.; Martaus, J.; Karapetrov, G.; Novosad, V.; Kostic, I.; Materials Science Division; Slovak Academy of Sciences

    2010-07-01

    Using micromagnetic calculations we search for optimal magnetic properties of novel magnetic tips to be used for a Switching Magnetization Magnetic Force Microscopy (SM-MFM), a novel technique based on two-pass scanning with reversed tip magnetization. Within the technique the sum of two scans images local atomic forces and their difference maps the local magnetic forces. The tip magnetization is switched during the scanning by a small magnetic field. The technology of novel low-coercitive magnetic tips is proposed. For best performance the tips must exhibit low magnetic moment, low switching field, and single-domain state at remanence. Such tips are equipped with Permalloy objects of a precise shape that are defined on their tilted sides. We calculate switching fields of such tips by solving the micromagnetic problem to find the optimum shape and dimensions of the Permalloy objects located on the tips. Among them, hexagon was found as the best shape for the tips.

  4. Secondary resonance magnetic force microscopy using an external magnetic field for characterization of magnetic thin films

    NASA Astrophysics Data System (ADS)

    Liu, Dongzi; Mo, Kangxin; Ding, Xidong; Zhao, Liangbing; Lin, Guocong; Zhang, Yueli; Chen, Dihu

    2015-09-01

    A bimodal magnetic force microscopy (MFM) that uses an external magnetic field for the detection and imaging of magnetic thin films is developed. By applying the external modulation magnetic field, the vibration of a cantilever probe is excited by its magnetic tip at its higher eigenmode. Using magnetic nanoparticle samples, the capacity of the technique which allows single-pass imaging of topography and magnetic forces is demonstrated. For the detection of magnetic properties of thin film materials, its signal-to-noise ratio and sensitivity are demonstrated to be superior to conventional MFM in lift mode. The secondary resonance MFM technique provides a promising tool for the characterization of nanoscale magnetic properties of various materials, especially of magnetic thin films with weak magnetism.

  5. Magnetic dynamos in accreting planetary bodies

    NASA Astrophysics Data System (ADS)

    Golabek, Gregor; Labrosse, Stéphane; Gerya, Taras; Morishima, Ryuji; Tackley, Paul

    2013-04-01

    Laboratory measurements revealed ancient remanent magnetization in meteorites [1] indicating the activity of magnetic dynamos in the corresponding meteorite parent body. To study under which circumstances dynamo activity is possible, we use a new methodology to simulate the internal evolution of a planetary body during accretion and differentiation. Using the N-body code PKDGRAV [2] we simulate the accretion of planetary embryos from an initial annulus of several thousand planetesimals. The growth history of the largest resulting planetary embryo is used as an input for the thermomechanical 2D code I2ELVIS [3]. The thermomechanical model takes recent parametrizations of impact processes [4] and of the magnetic dynamo [5] into account. It was pointed out that impacts can not only deposit heat deep into the target body, which is later buried by ejecta of further impacts [6], but also that impacts expose in the crater region originally deep-seated layers, thus cooling the interior [7]. This combination of impact effects becomes even more important when we consider that planetesimals of all masses contribute to planetary accretion. This leads occasionally to collisions between bodies with large ratios between impactor and target mass. Thus, all these processes can be expected to have a profound effect on the thermal evolution during the epoch of planetary accretion and may have implications for the magnetic dynamo activity. Results show that late-formed planetesimals do not experience silicate melting and avoid thermal alteration, whereas in early-formed bodies accretion and iron core growth occur almost simultaneously and a highly variable magnetic dynamo can operate in the interior of these bodies. [1] Weiss, B.P. et al., Science, 322, 713-716, 2008. [2] Richardson, D. C. et al., Icarus, 143, 45-59, 2000. [3] Gerya, T.V and Yuen, D.J., Phys. Earth Planet. Int., 163, 83-105, 2007. [4] Monteux, J. et al., Geophys. Res. Lett., 34, L24201, 2007. [5] Aubert, J. et al., Geophys. J. Int., 179, 1414-1428, 2009. [6] Safronov, V.S., Icarus, 33, 3-12, 1978. [7] Davies, G.F., in: Origin of the Earth, ed. H.E. Newsom, J.H. Jones, Oxford Un. Press, 175-194, 1990.

  6. Three-body forces and shell structure in calcium isotopes

    E-print Network

    Jason D. Holt; Takaharu Otsuka; Achim Schwenk; Toshio Suzuki

    2012-07-02

    Understanding and predicting the formation of shell structure from nuclear forces is a central challenge for nuclear physics. While the magic numbers N=2,8,20 are generally well understood, N=28 is the first standard magic number that is not reproduced in microscopic theories with two-nucleon forces. In this Letter, we show that three-nucleon forces give rise to repulsive interactions between two valence neutrons that are key to explain 48Ca as a magic nucleus, with a high 2+ excitation energy and a concentrated magnetic dipole transition strength. The repulsive three-nucleon mechanism improves the agreement with experimental binding energies.

  7. Turbofan flowfield simulation using Euler equations with body forces

    NASA Technical Reports Server (NTRS)

    Pankajakshan, Ramesh; Arabshahi, Abdollah; Whitfield, David L.

    1993-01-01

    A method for flow computations around ducted propfans is presented. The approach is to use the body force terms in the three-dimensional Euler equations to model the propeller. Numerical solutions are compared with experimental data for three ducted propfan configurations for different flow conditions.

  8. http://topex.ucsd.edu/body_force/ Response of an Elastic Half Space to an Arbitrary 3-D Vector Body Force

    E-print Network

    Sandwell, David T.

    - 1 - http://topex.ucsd.edu/body_force/ Response of an Elastic Half Space to an Arbitrary 3-D Vector Body Force (Copyright 2002, Bridget R. Smith and David T. Sandwell) We wish to calculate the displacement vector u(x,y,z) on the surface of the Earth due to a vector body force at depth. The approach

  9. Magnetic resonance imaging of the body

    SciTech Connect

    Higgins, C.B.; Hricak, H.

    1987-01-01

    This text provides reference to magnetic resonance imaging (MRI) of the body. Beginning with explanatory chapters on the physics, instrumentation, and interpretation of MRI, it proceeds to the normal anatomy of the neck, thorax, abdomen, and pelvis. Other chapters cover magnetic resonance imaging of blood flow, the larynx, the lymph nodes, and the spine, as well as MRI in obstetrics. The text features detailed coverage of magnetic resonance imaging of numerous disorders and disease states, including neck disease, thoracic disease; breast disease; congenital and acquired heart disease; vascular disease; diseases of the liver, pancreas, and spleen; diseases of the kidney, adrenals, and retroperitoneum; diseases of the male and female pelvis; and musculoskeletal diseases. Chapters on the biological and environmental hazards of MRI, the current clinical status of MRI in comparison to other imaging modalities, and economic considerations are also included.

  10. Collision of viscoelastic bodies: Rigorous derivation of dissipative force

    E-print Network

    Denis S. Goldobin; Eugeniy A. Susloparov; Anastasiya V. Pimenova; Nikolai V. Brilliantov

    2015-01-13

    We report a new theory of dissipative forces acting between colliding viscoelastic bodies. The impact velocity is assumed not to be large, to avoid plastic deformations and fragmentation at the impact. The bodies may be of an arbitrary convex shape and of different materials. We develop a mathematically rigorous perturbation scheme to solve the continuum mechanics equation that deals with both displacement and displacement rate fields and accounts for the dissipation in the bulk of the material. The perturbative solution of this equation allows to go beyond the previously used quasi-static approximation and obtain the dissipative force. This force does not suffer from the physical inconsistencies of the latter approximation and depends on particle deformation and deformation rate.

  11. Collision of viscoelastic bodies: Rigorous derivation of dissipative force.

    PubMed

    Goldobin, Denis S; Susloparov, Eugeniy A; Pimenova, Anastasiya V; Brilliantov, Nikolai V

    2015-06-01

    We report a new theory of dissipative forces acting between colliding viscoelastic bodies. The impact velocity is assumed not to be large to neglect plastic deformations in the material and propagation of sound waves. We consider the general case of bodies of an arbitrary convex shape and of different materials. We develop a mathematically rigorous perturbation scheme to solve the continuum mechanics equations that deal with both displacement and displacement rate fields and accounts for the dissipation in the bulk of the material. The perturbative solution of these equations allows to go beyond the previously used quasi-static approximation and obtain the dissipative force. The derived force does not suffer from the inconsistencies of the quasi-static approximation, like the violation of the third Newton's law for the case of different materials, and depends on particle deformation and deformation rate. PMID:26087916

  12. Electric and Magnetic Forces between Parallel-Wire Conductors.

    ERIC Educational Resources Information Center

    Morton, N.

    1979-01-01

    Discusses electric and magnetic forces between parallel-wire conductors and derives, in a simple fashion, order of magnitude estimates of the ratio of the likely electrostatic and electromagnetic forces for a simple parallel-wire balance. (Author/HM)

  13. May the Magnetic Force Be with You

    ERIC Educational Resources Information Center

    Wilcox, Jesse; Richey, Lindsey R.

    2012-01-01

    Although most elementary students have had experiences with magnets, they generally have misconceptions about magnetism (Driver et al. 1994; Burgoon, Heddle, and Duran 2010). For example, students may think magnets can attract all metals or that larger magnets are stronger than smaller magnets. Students often confuse magnets with magnetic

  14. Mitigated-force carriage for high magnetic field environments

    DOEpatents

    Ludtka, Gerard M.; Ludtka, Gail M.; Wilgen, John B.; Murphy, Bart L.

    2015-05-19

    A carriage for high magnetic field environments includes a plurality of work-piece separators disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla for supporting and separating a plurality of work-pieces by a preselected, essentially equal spacing, so that, as a first work-piece is inserted into the magnetic field, a second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

  15. Force measurements in magnetic bearings using fiber optic strain gauges 

    E-print Network

    Raymer, Stephen Geoffrey

    2000-01-01

    The research presented here develops a new method for measuring forces in magnetic bearings. Fiber-optic strain gauges (FOSGs) mounted to the side of the magnet poles are used to detect the small levels of strain that the ...

  16. The force on a body in active matter

    E-print Network

    Wen Yan; John F. Brady

    2015-10-27

    We present a general theory for determining the force (and torque) exerted on a boundary (or body) in active matter. The theory extends the description of passive Brownian colloids to self-propelled active particles and applies for all ratios of the thermal energy $k_BT$ to the swimmer's activity $k_sT_s = \\zeta U_0^2\\tau_R/6$, where $\\zeta$ is the Stokes drag coefficient, $U_0$ is the swim speed and $\\tau_R$ is the reorientation time of the active particles. The theory has a natural microscopic length scale over which concentration and orientation distributions are confined near boundaries, but the microscopic length does not appear in the force. The swim pressure emerges naturally and dominates the behavior when the boundary size is large compared to the swimmer's run length $\\ell = U_0\\tau_R$. The theory is used to predict the motion of bodies of all sizes immersed in active matter.

  17. Three-body system in leading order Effective Field Theory without three-body forces

    E-print Network

    B. Blankleider; J. Gegelia

    2000-09-05

    The use of leading order effective field theory (EFT) to describe neutron-deuteron scattering leads to integral equations that have unusual behaviour: when only two-body interactions are included, the scattering amplitude does not approach a limit when the cutoff used to solve the equations is removed. It has recently been shown that this cutoff dependence can be eliminated by the careful inclusion of a three-body force. In this paper we show that the cutoff dependence is just a reflection of the fact that the aforementioned integral equations admit an infinite number of solutions amongst which only one corresponds to the physical scattering amplitude. We show how to numerically extract the physical scattering amplitude from the general solution and in this way explicitly demonstrate that the amplitude for a particle scattering off a two-body bound state, in leading order EFT, is in fact determined entirely by two-body forces.

  18. Performance enhancement of a Lorentz force velocimeter using a buoyancy-compensated magnet system

    NASA Astrophysics Data System (ADS)

    Ebert, R.; Leineweber, J.; Resagk, C.

    2015-07-01

    Lorentz force velocimetry (LFV) is a highly feasible method for measuring flow rate in a pipe or a duct. This method has been established for liquid metal flows but also for electrolytes such as saltwater. A decrease in electrical conductivity of the medium causes a decrease of the Lorentz force which needs to be resolved, affecting the accuracy of the measurement. We use an electrical force compensation (EFC) balance for the determination of the tiny force signals in a test channel filled with electrolyte solution. It is used in a 90°-rotated orientation with a magnet system hanging vertically on its load bar. The thin coupling elements of its parallel guiding system limit the mass of the magnets to 1?kg. To overcome this restriction, which limits the magnetic flux density and hence the Lorentz forces, a weight force compensation mechanism is developed. Therefore, different methods such as air bearing are conceivable, but for the elimination of additional horizontal force components which would disturb the force signal, only compensation by lift force provided by buoyancy is reasonable. We present a swimming body setup that will allow larger magnet systems than before, because a large amount of the weight force will be compensated by this lift force. Thus the implementation of this concept has to be made with respect to hydrodynamical and mechanical stability. This is necessary to avoid overturning of the swimming body setup and to prevent inelastic deformation. Additionally, the issue will be presented and discussed whether thermal convection around the lifting body diminishes the signal-to-noise ratio (SNR) significantly or not.

  19. MAGNETIC FIELD CONFINEMENT IN THE SOLAR CORONA. I. FORCE-FREE MAGNETIC FIELDS B. Fornberg,2

    E-print Network

    Fornberg, Bengt

    MAGNETIC FIELD CONFINEMENT IN THE SOLAR CORONA. I. FORCE-FREE MAGNETIC FIELDS N. Flyer,1 B Axisymmetric force-free magnetic fields external to a unit sphere are studied as solutions to boundary value to the formation of an azimuthal rope of twisted magnetic field embedded within the global field, and to the energy

  20. Lateral restoring force on a magnet levitated above a superconductor

    NASA Technical Reports Server (NTRS)

    Davis, L. C.

    1990-01-01

    The lateral restoring force on a magnet levitated above a superconductor is calculated as a function of displacement from its original position at rest using Bean's critical-state model to describe flux pinning. The force is linear for small displacements and saturates at large displacements. In the absence of edge effects the force always attracts the magnet to its original position. Thus it is a restoring force that contributes to the stability of the levitated magnet. In the case of a thick superconductor slab, the origin of the force is a magnetic dipole layer consisting of positive and negative supercurrents induced on the trailing side of the magnet. The qualitative behavior is consistent with experiments reported to date. Effects due to the finite thickness of the superconductor slab and the granular nature of high-Tc materials are also considered.

  1. A flow simulation study of protein solution under magnetic forces

    NASA Astrophysics Data System (ADS)

    Okada, Hidehiko; Hirota, Noriyuki; Matsumoto, Shinji; Wada, Hitoshi

    2013-02-01

    We have developed a superconducting magnet system generating magnetic forces able to compensate gravity and suppress convection of diamagnetic protein solution from which protein crystals precipitate. A simulation model has been proposed to elucidate the motion of protein solutions and search for the optimal conditions of the crystal formation process. This model incorporates general, non-uniform magnetic forces as external forces, while the previous models involve only simple, uniform magnetic forces. The simulation results indicate that the vertical component can suppress the convection of protein solution, while the horizontal component induces minimal convection. We, therefore, need to take into account the both components when considering the formation of protein crystals under magnetic forces.

  2. Relativity and electromagnetism: The force on a magnetic monopole

    NASA Astrophysics Data System (ADS)

    Rindler, Wolfgang

    1989-11-01

    On the occasion of the 100th anniversary of the first publication, by Oliver Heaviside, of what is now known as the Lorentz force law in electromagnetic theory, the analogous force law for magnetic monopoles is examined. Its relevance and limitations in calculating the force and torque on small current loops are discussed, and both its heuristic and practical uses are demonstrated.

  3. Effect of permanent-magnet irregularities in levitation force measurements.

    SciTech Connect

    Hull, J. R.

    1999-10-14

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a nonnegligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analog of Earnshaw's theorem, in which at the field-cooling position the vertical stiffness is equal to the sum of the horizontal stiffnesses, independent of angular distribution of magnetic moments within the PM.

  4. Response of a Viscoelastic Layered Half-space to an Arbitrary 3-D Vector Body Force

    E-print Network

    Sandwell, David T.

    Response of a Viscoelastic Layered Half-space to an Arbitrary 3-D Vector Body Force (Copyright 2003 elastic half-space to an arbitrary 3-D vector body force [Smith and Sandwell, 2003], we now wish to extend that our solutions will be prepared in the Fourier domain. The method follows: i.) Develop the body force

  5. Demonstration: levitating globe comparing a magnetic force with the force of gravity; Geiger counter, sources.

    E-print Network

    Boal, David

    Demonstration: levitating globe comparing a magnetic force with the force of gravity; Geiger interaction - gravity. Gravity As you know from high school physics, the gravitational force between two with G = 6.67 x 10-11 Nm2/kg2. The proportionality constant G is a universal constant applying to all

  6. Magnetic force of piezoelectric cantilever energy harvesters with external magnetic field

    NASA Astrophysics Data System (ADS)

    Tan, D.; Leng, Y. G.; Gao, Y. J.

    2015-11-01

    In piezoelectric cantilever energy harvesters with external magnetic field, one of the difficulties is the impact of the external magnetic field or magnetic force on vibration response and energy harvesting efficiency. Here we use the magnetizing current and magnetic dipoles approaches to analyze the magnetic force. The two calculation models are proposed for the energy harvesters. The calculation results of the two methods are compared with a set of experimental data. It has been proved that errors are produced with both methods while the magnet interval is sufficiently small. However, the calculation result achieved from magnetic dipoles approach is closer to experimental measurements than the one of magnetizing current approach. Consequently, the magnetic dipoles approach can be chosen preferably to calculate the magnetic force of piezoelectric cantilever energy harvesters with external magnetic field.

  7. Distortion of magnetic field and magnetic force of a brushless dc motor due to deformed rubber magnet

    NASA Astrophysics Data System (ADS)

    Lee, C. J.; Jang, G. H.

    2008-04-01

    This paper investigates the distortion of magnetic field of a brushless dc (BLDC) motor due to deformed rubber magnet. Global or local deformation of rubber magnet in the BLDC motor is mathematically modeled by using the Fourier series. Distorted magnetic field is calculated by using the finite element method, and unbalanced magnetic force is calculated by using the Maxwell stress tensor. When the rubber magnet is globally or locally deformed, the unbalanced magnetic force has the frequencies with the first harmonic and the harmonics of slot number ±1. However, the harmonic deformation with multiple of common divisor of pole and slot does not generate unbalanced magnetic force due to the rotational symmetry.

  8. Postactivation potentiation: upper body force development changes after maximal force intervention.

    PubMed

    Farup, Jean; Sørensen, Henrik

    2010-07-01

    The neuromuscular phenomenon postactivation potentiation can possibly be used to increase the rate of force development (RFD) and maximal power (Pmax). Various intervention protocols have been examined with varying results. Maximal intervention protocols using 1 repetition maximum (1RM) have been examined in earlier studies in the lower body with positive results, but no studies have investigated maximal protocols on the upper body. Using maximal protocols would furthermore eliminate the uncertainties when expressing intensity as either numbers of RM or percentage of 1RM and hence emphasize standardization. Thus, the aim of this study was to examine the force development characteristics in the upper body after a maximal bench-press intervention. Eight strength trained male athletes performed an intervention protocol consisting of 5x 1RM in the bench press. Pre and post the intervention, a test consisting of either an isometric maximal voluntary contraction or a bench throw was completed to measure isometric RFD (iRFD) or Pmax, respectively. Statistical significance was accepted at p body using the exact same intervention. It could be speculated if different activation levels in the upper body vs. the lower body could explain the conflicting results. In conclusion, to elicit postactivation potentiation in the upper body, an intervention of maximal intensity is not warranted. The practical applications of these results are that coaches and athletes should be careful to implement maximal resistance to elicit a potentiation until further studies have been conducted in this area. PMID:20543739

  9. Classical diamagnetism, magnetic interaction energies, and repulsive forces in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Essén, H.

    2011-05-01

    The Bohr-van Leeuwen theorem is often summarized as saying that there is no classical magnetic susceptibility, in particular no diamagnetism. This is seriously misleading. The theorem assumes position-dependent interactions but this is not required by classical physics. Since the work of Darwin in 1920 it has been known that the magnetism due to classical charged point particles can only be described by allowing velocity-dependent interactions in the Lagrangian. Legendre transformation to an approximate Hamiltonian can give an estimate of the Darwin diamagnetism for a system of charged point particles. Comparison with experiment, however, requires knowledge of the number of classically behaving electrons in the sample. A new repulsive effective many-body force, which should be relevant in plasmas, is predicted by the Hamiltonian.

  10. LABORATORY V MAGNETIC FIELDS AND FORCES

    E-print Network

    Minnesota, University of

    , and to store data for computers. Magnetism also allows us to explore the structure of the Universe, the atomic structure of materials, and the quark structure of elementary particles. The magnetic interaction can best

  11. LABORATORY VI MAGNETIC FIELDS AND FORCES

    E-print Network

    Minnesota, University of

    of the universe, the atomic structure of materials, and the quark structure of elementary particles. Magnetic of the human brain, and storing information in computers. Magnetism also allows us to explore the structure

  12. Mitigated-force carriage for high magnetic field environments

    SciTech Connect

    Ludtka, Gerard M; Ludtka, Gail M; Wilgen, John B; Murphy, Bart L

    2014-05-20

    A carriage for high magnetic field environments includes a first work-piece holding means for holding a first work-piece, the first work-piece holding means being disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla. The first work-piece holding means is further disposed in operable connection with a second work-piece holding means for holding a second work-piece so that, as the first work-piece is inserted into the magnetic field, the second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

  13. Experimental studies of protozoan response to intense magnetic fields and forces

    NASA Astrophysics Data System (ADS)

    Guevorkian, Karine

    Intense static magnetic fields of up to 31 Tesla were used as a novel tool to manipulate the swimming mechanics of unicellular organisms. It is shown that homogenous magnetic fields alter the swimming trajectories of the single cell protozoan Paramecium caudatum, by aligning them parallel to the applied field. Immobile neutrally buoyant paramecia also oriented in magnetic fields with similar rates as the motile ones. It was established that the magneto-orientation is mostly due to the magnetic torques acting on rigid structures in the cell body and therefore the response is a non-biological, passive response. From the orientation rate of paramecia in various magnetic field strengths, the average anisotropy of the diamagnetic susceptibility of the cell was estimated. It has also been demonstrated that magnetic forces can be used to create increased, decreased and even inverted simulated gravity environments for the investigation of the gravi-responses of single cells. Since the mechanisms by which Earth's gravity affects cell functioning are still not fully understood, a number of methods to simulate different strength gravity environments, such as centrifugation, have been employed. Exploiting the ability to exert magnetic forces on weakly diamagnetic constituents of the cells, we were able to vary the gravity from -8 g to 10 g, where g is Earth's gravity. Investigations of the swimming response of paramecia in these simulated gravities revealed that they actively regulate their swimming speed to oppose the external force. This result is in agreement with centrifugation experiments, confirming the credibility of the technique. Moreover, the Paramecium's swimming ceased in simulated gravity of 10 g, indicating a maximum possible propulsion force of 0.7 nN. The magnetic force technique to simulate gravity is the only earthbound technique that can create increased and decreased simulated gravities in the same experimental setup. These findings establish a general technique for applying continuously variable forces to cells or cell populations suitable for exploring their force transduction mechanisms.

  14. Design and construction of a magnetic force microscope 

    E-print Network

    Khandekar, Sameer Sudhakar

    2005-08-29

    A magnetic force microscope (MFM) is a special type of scanning force microscope which measures the stray field above a ferromagnetic sample with the help of a ferromagnetic cantilever. The aim of this project was to design and build a MFM head...

  15. Magnetic levitation of metamaterial bodies enhanced with magnetostatic surface resonances

    E-print Network

    Urzhumov, Yaroslav; Bingham, Chris; Padilla, Willie; Smith, David R

    2011-01-01

    We propose that macroscopic objects built from negative-permeability metamaterials may experience resonantly enhanced magnetic force in low-frequency magnetic fields. Resonant enhancement of the time-averaged force originates from magnetostatic surface resonances (MSR) which are analogous to the electrostatic resonances of negative-permittivity particles, well known as surface plasmon resonances in optics. We generalize the classical problem of MSR of a homogeneous object to include anisotropic metamaterials, and consider the most extreme case of anisotropy where the permeability is negative in one direction but positive in the others. It is shown that deeply subwavelength objects made of such indefinite (hyperbolic) media exhibit a pronounced magnetic dipole resonance that couples strongly to uniform or weakly inhomogeneous magnetic field and provides strong enhancement of the magnetic force, enabling applications such as enhanced magnetic levitation.

  16. Extending the range for force calibration in magnetic tweezers.

    PubMed

    Daldrop, Peter; Brutzer, Hergen; Huhle, Alexander; Kauert, Dominik J; Seidel, Ralf

    2015-05-19

    Magnetic tweezers are a wide-spread tool used to study the mechanics and the function of a large variety of biomolecules and biomolecular machines. This tool uses a magnetic particle and a strong magnetic field gradient to apply defined forces to the molecule of interest. Forces are typically quantified by analyzing the lateral fluctuations of the biomolecule-tethered particle in the direction perpendicular to the applied force. Since the magnetic field pins the anisotropy axis of the particle, the lateral fluctuations follow the geometry of a pendulum with a short pendulum length along and a long pendulum length perpendicular to the field lines. Typically, the short pendulum geometry is used for force calibration by power-spectral-density (PSD) analysis, because the movement of the bead in this direction can be approximated by a simple translational motion. Here, we provide a detailed analysis of the fluctuations according to the long pendulum geometry and show that for this direction, both the translational and the rotational motions of the particle have to be considered. We provide analytical formulas for the PSD of this coupled system that agree well with PSDs obtained in experiments and simulations and that finally allow a faithful quantification of the magnetic force for the long pendulum geometry. We furthermore demonstrate that this methodology allows the calibration of much larger forces than the short pendulum geometry in a tether-length-dependent manner. In addition, the accuracy of determination of the absolute force is improved. Our force calibration based on the long pendulum geometry will facilitate high-resolution magnetic-tweezers experiments that rely on short molecules and large forces, as well as highly parallelized measurements that use low frame rates. PMID:25992733

  17. Fundamental study of phosphor separation by controlling magnetic force

    NASA Astrophysics Data System (ADS)

    Wada, Kohei; Mishima, Fumihito; Akiyama, Yoko; Nishijima, Shigehiro

    2013-11-01

    The phosphor wastes consist of phosphors with different emission colors, green (LAP), red (YOX), blue (BAM) and white (HP). It is required to recover and reuse the rare earth phosphors with high market value. In this study, we tried to separate the phosphor using the magnetic separation by HTS bulk magnet utilizing the differences of magnetic susceptibility by the type of phosphors. We succeeded in the successive separation of HP with low market value from YOX and BAM including the rare earth using the magnetic Archimedes method. In this method, vertical and radial components of the magnetic force were used.

  18. Sensitive magnetic force detection with a carbon nanotube resonator

    SciTech Connect

    Willick, Kyle; Haapamaki, Chris; Baugh, Jonathan

    2014-03-21

    We propose a technique for sensitive magnetic point force detection using a suspended carbon nanotube (CNT) mechanical resonator combined with a magnetic field gradient generated by a ferromagnetic gate electrode. Numerical calculations of the mechanical resonance frequency show that single Bohr magneton changes in the magnetic state of an individual magnetic molecule grafted to the CNT can translate to detectable frequency shifts, on the order of a few kHz. The dependences of the resonator response to device parameters such as length, tension, CNT diameter, and gate voltage are explored and optimal operating conditions are identified. A signal-to-noise analysis shows that, in principle, magnetic switching at the level of a single Bohr magneton can be read out in a single shot on timescales as short as 10??s. This force sensor should enable new studies of spin dynamics in isolated single molecule magnets, free from the crystalline or ensemble settings typically studied.

  19. The use of electromagnetic body forces to enhance the quality of laser welds

    NASA Astrophysics Data System (ADS)

    Ambrosy, Guenter; Berger, P.; Huegel, H.; Lindenau, D.

    2003-11-01

    The use of electromagnetic body forces in laser beam welding of aluminum alloys is a new method to shape the geometry and to enhance the quality of the weld seams. In this new approach, electromagnetic volume forces are utilized by applying magnetic fields and electric currents of various origins. Acting in the liquid metal, they directly affect the flow field and can lead to favourable conditions for the melt dynamics and energy coupling. Numerous welds with full and partial penetration using both CO2 and Nd:YAG lasers demonstrate that this method directly influences the seam geometry and top-bead topography as well as the penetration depth and the evolution of pores and cracks. In the case of full penetration, it is also possible to lift or to lower the weld pool. The method, therefore, can be used to shape the geometry and to enhance the quality of the weld seam. Depending on the orientation of an external magnetic field, significant impacts are achieved in CO2 welding, even without an external current: the shape of the cross-sectional area can be increased of up to 50% and also the seam width is changed. Whereas for such conditions with Nd:YAG lasers no significant effect could be observed, it turned out that, when an external electric current is applied, similar effects are present with both wavelengths. In further investigations, the effect of electromagnetic body forces resulting from the interaction of an external current and its self-induced magnetic field was studied. Hereby, the current was fed into the workpiece via a tungsten electrode or a filler wire. The resulting phenomena are the same independent from wavelength and means of current feed.

  20. Nuclear Physics A 760 (2005) 110138 Nave dimensional analysis for three-body forces

    E-print Network

    Weise, Wolfram

    2005-01-01

    Nuclear Physics A 760 (2005) 110­138 Naïve dimensional analysis for three-body forces without pions" effective field theory of nuclear physics, I extend and systematise the power-counting of three-body forces short-range forces produce shallow two-particle bound states, and in particular for the "pionless

  1. EXPERIMENTAL BENCHMARKING OF THE MAGNETIZED FRICTION FORCE.

    SciTech Connect

    FEDOTOV, A.V.; GALNANDER, B.; LITVINENKO, V.N.; LOFNES, T.; SIDORIN, A.O.; SMIRNOV, A.V.; ZIEMANN, V.

    2005-09-18

    High-energy electron cooling, presently considered as essential tool for several applications in high-energy and nuclear physics, requires accurate description of the friction force. A series of measurements were performed at CELSIUS with the goal to provide accurate data needed for the benchmarking of theories and simulations. Some results of accurate comparison of experimental data with the friction force formulas are presented.

  2. Force Measurements in Magnetic Suspension and Balance System

    NASA Technical Reports Server (NTRS)

    Kuzin, Alexander; Shapovalov, George; Prohorov, Nikolay

    1996-01-01

    The description of an infrared telemetry system for measurement of drag forces in Magnetic Suspension and Balance Systems (MSBS) is presented. This system includes a drag force sensor, electronic pack and transmitter placed in the model which is of special construction, and receiver with a microprocessor-based measuring device, placed outside of the test section. Piezosensitive resonators as sensitive elements and non-magnetic steel as the material for the force sensor are used. The main features of the proposed system for load measurements are discussed and the main characteristics are presented.

  3. Magnetic forces in high-Tc superconducting bearings

    NASA Technical Reports Server (NTRS)

    Moon, F. C.

    1991-01-01

    In September 1987, researchers at Cornell levitated a small rotor on superconducting bearings at 10,000 rpm. In April 1989, a speed of 120,000 rpm was achieved in a passive bearing with no active control. The bearing material used was YBa2Cu307. There is no evidence that the rotation speed has any significant effect on the lift force. Magnetic force measurements between a permanent rare-earth magnet and high T(sub c) superconducting material versus vertical and lateral displacements were made. A large hysteresis loop results for large displacements, while minor loops result for small displacements. These minor loops seem to give a slope proportional to the magnetic stiffness, and are probably indicative of flux pinning forces. Experiments of rotary speed versus time show a linear decay in a vacuum. Measurements of magnetic dipole over a high-T(sub c) superconducting disc of YBCO show that the lateral vibrations of levitated rotors were measured which indicates that transverse flux motion in the superconductor will create dissipation. As a result of these force measurements, an optimum shape for the superconductor bearing pads which gives good lateral and axial stability was designed. Recent force measurements on melt-quench processed superconductors indicate a substantial increase in levitation force and magnetic stiffness over free sintered materials. As a result, application of high-T(sub c) superconducting bearings are beginning to show great promise at this time.

  4. LABORATORY V MAGNETIC FIELDS AND FORCES

    E-print Network

    Minnesota, University of

    , the atomic structure of materials, and the quark structure of elementary particles. In this set of laboratory, and to store analog and digital data. Magnetism also allows us to explore the structure of the Universe

  5. A magnetic gradient induced force in NMR restricted diffusion experiments

    SciTech Connect

    Ghadirian, Bahman; Stait-Gardner, Tim; Castillo, Reynaldo; Price, William S.

    2014-03-28

    We predict that the phase cancellation of a precessing magnetisation field carried by a diffusing species in a bounded geometry under certain nuclear magnetic resonance pulsed magnetic field gradient sequences results in a small force over typically micrometre length scales. Our calculations reveal that the total magnetisation energy in a pore under the influence of a pulsed gradient will be distance-dependent thus resulting in a force acting on the boundary. It is shown that this effect of the magnetisation of diffusing particles will appear as either an attractive or repulsive force depending on the geometry of the pore and magnetic properties of the material. A detailed analysis is performed for the case of a pulsed gradient spin-echo experiment on parallel planes. It is shown that the force decays exponentially in terms of the spin-spin relaxation. The proof is based on classical electrodynamics. An application of this effect to soft matter is suggested.

  6. Magnetic forces in high-T(sub c) superconducting bearings

    NASA Technical Reports Server (NTRS)

    Moon, F. C.

    1990-01-01

    In September 1987 research at Cornell levitated a small rotor on superconducting bearing at 10,000 rpm. In April 1989 a speed of 120,000 rpm was achieved in a passive bearing with no active control. The bearing material used was YBa2Cu3O7. There is no evidence that the rotation speed has any significant effect on the lift force. Magnetic force measurements between a permanent rare-earth magnet and high T(sub c) superconducting material versus vertical and lateral displacements were made. A large hysteresis loop results for large displacements, while minor loops result for small displacements. These minor loops seem to give a slope proportional to the magnetic stiffness, and are probably indicative of flux pinning forces. Experiments of rotary speed versus time show a linear decay in a vacuum. Measurements of magnetic drag forces of a magnetic dipole over a high-T(sub c) superconducting disc of YBCO show that the drag force reaches a constant value, independent of the speed. Dampling of lateral vibrations of levitated rotors were measured which indicates that transverse flux motion in the superconductor will create dissipation. As a result of these force measurements, an optimum shape for the superconductor bearing pads which gives good lateral and axial stability was designed. Recent force measurements on melt-quench processed superconductors indicate a substantial increase in levitation force and magnetic stiffness over free sintered materials. As a result, application of high-T(sub c) superconducting bearings are beginning to show great promise at this time.

  7. Levitation forces of a bulk YBCO superconductor in gradient varying magnetic fields

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Gong, Y. M.; Wang, G.; Zhou, D. J.; Zhao, L. F.; Zhang, Y.; Zhao, Y.

    2015-09-01

    The levitation forces of a bulk YBCO superconductor in gradient varying high and low magnetic fields generated from a superconducting magnet were investigated. The magnetic field intensity of the superconducting magnet was measured when the exciting current was 90 A. The magnetic field gradient and magnetic force field were both calculated. The YBCO bulk was cooled by liquid nitrogen in field-cooling (FC) and zero-field-cooling (ZFC) condition. The results showed that the levitation forces increased with increasing the magnetic field intensity. Moreover, the levitation forces were more dependent on magnetic field gradient and magnetic force field than magnetic field intensity.

  8. Manipulation and sorting of magnetic particles by a magnetic force microscope on a microfluidic magnetic trap platform

    E-print Network

    Donahue, Michael J.

    magnetic particles remains an essential method for revealing information about molecular motors, protein1 Manipulation and sorting of magnetic particles by a magnetic force microscope on a microfluidic magnetic trap platform Elizabeth Mirowski, John Moreland, Arthur Zhang and Stephen E. Russek Electronics

  9. Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient

    PubMed Central

    Yamane, Yuta; Hemmatiyan, Shayan; Ieda, Jun'ichi; Maekawa, Sadamichi; Sinova, Jairo

    2014-01-01

    Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter ? that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient. PMID:25365971

  10. Many-body forces, isospin asymmetry and dense hyperonic matter

    E-print Network

    R. O. Gomes; V. Dexheimer; S. Schramm; C. A. Z. Vascconcellos

    2015-04-10

    The equation of state (EoS) of asymmetric nuclear matter at high densities is a key topic for the description of matter inside neutron stars. The determination of the properties of asymmetric nuclear matter, such as the symmetry energy ($a_{sym}$) and the slope of the symmetry energy ($L_0$) at saturation density, has been exaustively studied in order to better constrain the nuclear matter EoS. However, differently from symmetric matter properties that are reasonably constrained, the symmetry energy and its slope still large uncertainties in their experimental values. Regarding this subject, some studies point towards small values of the slope of the symmetry energy, while others suggest rather higher values. Such a lack of agreement raised a certain debate in the scientific community. In this paper, we aim to analyse the role of these properties on the behavior of asymmetric hyperonic matter. Using the formalism presented in Ref. (R.O. Gomes et al 2014}, which considers many-body forces contributions in the meson-baryon coupling, we calculate the EoS of asymmetric hyperonic matter and apply it to describe hyperonic matter and hyperon stars.

  11. Many-body central force potentials for tungsten

    NASA Astrophysics Data System (ADS)

    Bonny, G.; Terentyev, D.; Bakaev, A.; Grigorev, P.; Van Neck, D.

    2014-07-01

    Tungsten and tungsten-based alloys are the primary candidate materials for plasma facing components in fusion reactors. The exposure to high-energy radiation, however, severely degrades the performance and lifetime limits of the in-vessel components. In an effort to better understand the mechanisms driving the materials' degradation at the atomic level, large-scale atomistic simulations are performed to complement experimental investigations. At the core of such simulations lies the interatomic potential, on which all subsequent results hinge. In this work we review 19 central force many-body potentials and benchmark their performance against experiments and density functional theory (DFT) calculations. As basic features we consider the relative lattice stability, elastic constants and point-defect properties. In addition, we also investigate extended lattice defects, namely: free surfaces, symmetric tilt grain boundaries, the 1/2<1?1?1>{1?1?0} and 1/2<1?1?1> {1?1?2} stacking fault energy profiles and the 1/2<1?1?1> screw dislocation core. We also provide the Peierls stress for the 1/2<1?1?1> edge and screw dislocations as well as the glide path of the latter at zero Kelvin. The presented results serve as an initial guide and reference list for both the modelling of atomically-driven phenomena in bcc tungsten, and the further development of its potentials.

  12. Vertical and lateral forces when a permanent magnet above a superconductor traverses in arbitrary directions

    NASA Astrophysics Data System (ADS)

    Yang, Yong

    2008-12-01

    In an actual levitation system composed of high temperature superconductors (HTSs) and permanent magnets (PMs), the levitating bodies may traverse in arbitrary directions. Many previous researchers assumed that the levitating bodies moved in a vertical direction or a lateral direction in order to simplify the problem. In this paper, the vertical and lateral forces acting on the PM are calculated by the modified frozen-image method when a PM above an HTS traverses in arbitrary directions. In order to study the effects of the movement directions on the vertical and lateral forces, comparisons of the forces that act on a PM traversing in a tilted direction with those that act on a PM traversing in a vertical direction or a lateral direction have been presented.

  13. Design and optimization of force-reduced high field magnets

    NASA Astrophysics Data System (ADS)

    Rembeczki, Szabolcs

    High field magnets have many important applications in different areas of research, in the power industry and also for military purposes. For example, high field magnets are particularly useful in: material sciences, high energy physics, plasma physics (as fusion magnets), high power applications (as energy storage devices), and space applications (in propulsion systems). One of the main issues with high-field magnets is the presence of very large electromagnetic stresses that must be counteracted and therefore require heavy support structures. In superconducting magnets, the problems caused by Lorentz forces are further complicated by the fact that superconductors for high field applications are pressure sensitive. The current carrying capacity is greatly reduced under stress and strain (especially in the case of Nb 3Sn and the new high temperature superconductors) so the reduction of the acting forces is of even greater importance. Different force-reduced magnet concepts have been studied in the past, both numerical and analytical methods have been used to solve this problem. The developed concepts are based on such complex winding geometries that the realization and manufacturing of such coils is extremely difficult and these concepts are mainly of theoretical interest. In the presented research, a novel concept for force-reduced magnets has been developed and analyzed which is easy to realize and therefore is of practical interest. The analysis has been performed with a new methodology, which does not require the time consuming finite element calculations. The developed computer models describe the 3-dimensional winding configuration by sets of filaments (filamentary approximation). This approach is much faster than finite element analysis and therefore allows rapid optimization of concepts. The method has been extensively tested on geometries of force-reduced solenoids where even analytical solutions exist. As a further cross check, the developed computer codes have been tested against qualified finite element codes and found to be in excellent agreement. The developed concept of force-reduced coils is directly applicable to pulsed magnets and a conceptual design of a 25 Tesla magnet has been developed. Although no experimental proof was possible within the scope of this research, there is strong evidence to believe that the developed concept is also applicable to superconducting magnets operating in a constant current mode.

  14. Local nonlinear rf forces in inhomogeneous magnetized plasmas

    SciTech Connect

    Chen, Jiale; Gao, Zhe

    2014-06-15

    The local nonlinear forces induced by radio frequency (rf) waves are derived in inhomogeneous magnetized plasmas, where the inhomogeneity exists in the rf fields, in the static magnetic field as well as in the equilibrium density and temperature. The local parallel force is completely resonant, but a novel component dependent on those inhomogeneities is obtained as the result of the inhomogeneous transport of parallel resonant-absorbed momentum by the nonlinear perpendicular drift flux. In the local poloidal force, the component induced by the inhomogeneity of rf power absorption is also confirmed and it can be recognized as the residual effect from the incomplete cancellation between the rate of the diamagnetic poloidal momentum gain and the Lorentz force due to the radial diffusion-like flux. The compact expression for radial force is also obtained for the first time, whose nonresonant component is expressed as the sum of the ponderomotive force on particles and the gradients of the nonresonant perpendicular pressure and of the nonresonant momentum flux due to the finite temperature effect. Numerical calculations in a 1-D slab model show that the resonant component dependent on the inhomogeneities may be significant when the ion absorption dominates the resonant wave-particle interaction. A quantitative estimation shows that the novel component in the parallel force is important to understand the experiments of the ion-cyclotron-frequency mode-conversion flow drive.

  15. [Mobilization of intraocular foreign bodies by magnetic resonance tomography].

    PubMed

    Kremmer, S; Schiefer, U; Wilhelm, H; Zrenner, E

    1996-03-01

    A 49-year-old patient suffered from a binocular perforating trauma with metal foreign bodies in 1974. During an MRI examination in 1992 for a lumbar spine herniation a metal foreign body was mobilised from the deeper vitreal and retinal area, now causing optical disturbances freely floating in the anterior vitreous. Refusing an operation, the patient, an electrical engineer, tried himself to remove the foreign body out of the optical axis by exposing his head to the electro-magnetic field of an induction coil (pulsed magnetic induction B at t0 of 0.26 Tesla). The foreign body was split into multiple small parts no longer disturbing the patient. To early detect a siderosis regular ophthalmological controls including ERG are necessary. This example stresses that even small intraocular metal foreign bodies are a contraindication for the usually applied field strength of MRI examinations. PMID:8699779

  16. Magnetic versus mechanical expansion with different force thresholds and points of force application.

    PubMed

    Vardimon, A D; Graber, T M; Voss, L R; Verrusio, E

    1987-12-01

    The effects of force magnitude (high versus low) and point of force application (teeth versus direct palatal endosseous pins) on palatal expansion treatment were studied on four juvenile female Macaca fascicularis monkeys. Three subjects received one of the following appliances: (1) conventional type jackscrew maxillary plate bonded to the posterior teeth with a high force magnitude of 2033 g, (2) a similar tooth-borne appliance but with rare earth repulsive magnets having a low force of 258 g, or (3) a specially designed palatal acrylic appliance pinned directly to the palatal shelves also utilizing rare earth repulsive magnets with a low force of 258 g. A fourth animal, the control, received a passive sham appliance bonded to the abutment teeth. Spatial changes of dental markers and facial implants were studied radiographically. In the low force, magnetically induced appliances, treatment was longer (95 days for the palatally pinned appliance and 135 days for the bonded tooth-borne appliance). The force radiated superolaterally, dissipating in the zygomaticofrontal suture, and the overjet significantly increased because of the marked widening of the incisive and transverse sutures. With the conventional jackscrew high-force appliance bonded to the teeth, the treatment lasted 33 days. A diastema developed between the incisors and the force was transmitted superolaterally and then transmedially, thus causing fractures in the nasal complex and other iatrogenic sequelae. The palatally pinned magnetic appliance induced bodily tooth movement, the greatest increase in intermolar distance, and a superior repositioning of the maxillopalatine region. The latter two effects were caused by selective excitation of the transverse suture over the premaxillary suture. Symmetry decreased with remoteness from the point of application. These results suggest reduction of the conventional force by up to eightfold--a level supplied by the rare earth magnets. Extrapolating from these results, the slow palatal expansion regimen for the treatment of Class III malocclusions with maxillary transverse deficiency is preferred at an early age (not more than 6 years). In the event of a suture disorder, the use of direct forces to the palate might be considered. PMID:3318395

  17. THE MEAN ELECTROMOTIVE FORCE RESULTING FROM MAGNETIC BUOYANCY INSTABILITY

    SciTech Connect

    Davies, C. R.; Hughes, D. W. E-mail: d.w.hughes@leeds.ac.uk

    2011-02-01

    Motivated both by considerations of the generation of large-scale astrophysical magnetic fields and by potential problems with mean magnetic field generation by turbulent convection, we investigate the mean electromotive force (emf) resulting from the magnetic buoyancy instability of a rotating layer of stratified magnetic field, considering both unidirectional and sheared fields. We discuss why the traditional decomposition into {alpha} and {beta} effects is inappropriate in this case, and that it is only consideration of the entire mean emf that is meaningful. By considering a weighted average of the unstable linear eigenmodes, and averaging over the horizontal plane, we obtain depth-dependent emfs. For the simplified case of isothermal, ideal MHD, we are able to obtain an analytic expression for the emf; more generally, the emf has to be determined numerically. We calculate how the emf depends on the various parameters of the problem, particularly the rotation rate and the latitude of the magnetic layer.

  18. Magnetization relaxation and geometric forces in a Bose ferromagnet.

    PubMed

    Armaitis, J; Stoof, H T C; Duine, R A

    2013-06-28

    We construct the hydrodynamic theory for spin-1/2 Bose gases at arbitrary temperatures. This theory describes the coupling between the magnetization and the normal and superfluid components of the gas. In particular, our theory contains the geometric forces on the particles that arise from their spin's adiabatic following of the magnetization texture. The phenomenological parameters of the hydrodynamic theory are calculated in the Bogoliubov approximation and using the Boltzmann equation in the relaxation-time approximation. We consider the topological Hall effect due to the presence of a Skyrmion, and show that this effect manifests itself in the collective modes of the system. The dissipative coupling between the magnetization and the normal component is shown to give rise to magnetization relaxation that is fourth order in spatial gradients of the magnetization direction. PMID:23848850

  19. The mean electromotive force resulting from magnetic buoyancy instability

    E-print Network

    Davies, C R

    2010-01-01

    Motivated both by considerations of the generation of large-scale astrophysical magnetic fields and by potential problems with mean magnetic field generation by turbulent convection, we investigate the mean electromotive force (emf) resulting from the magnetic buoyancy instability of a rotating layer of stratified magnetic field, considering both unidirectional and sheared fields. We discuss why the traditional decomposition into $\\alpha$ and $\\beta$ effects is inappropriate in this case, and that it is only consideration of the entire mean emf that is meaningful. By considering a weighted average of the unstable linear eigenmodes, and averaging over the horizontal plane, we obtain depth-dependent emfs. For the simplified case of isothermal, ideal MHD we are able to obtain an analytic expression for the emf; more generally the emf has to be determined numerically. We calculate how the emf depends on the various parameters of the problem, particularly the rotation rate and the latitude of the magnetic layer.

  20. Three-axis force actuator for a magnetic bearing

    NASA Technical Reports Server (NTRS)

    Gondhalekar, Vijay (Inventor)

    1998-01-01

    This invention features a three-axis force actuator that axially, radially and rotatably supports a bearing member for frictionless rotation about an axis of rotation generally coincident with a Z-axis. Also featured is a magnetic bearing having such an actuator. The actuator includes an inner member, a magnetic member and a pole assembly having a ring member and four pole extending therefrom. The poles are equi-angular spaced from each other and radially spaced about the Z-axis. The inner member extends along the Z-axis and is a highly magnetic permeable material. The magnetic member is formed about the inner member outer surface, extends along the Z-axis and is configured so one magnetic pole polarity is located at its outer surface and the other polarity pole is located at its inner surface. Preferably, the magnetic member is a radially magnetized permanent magnet. The inner surface of the ring member is magnetically coupled to the magnetic member and a face of each pole is coupled to the bearing member. The magnetic member, the pole assembly, the inner member and the bearing member cooperate to generate a magnetic field that radially and rotatably supports a rotating member secured to the bearing member. The actuator further includes a plurality of electromagnetic coils. Preferably, a coil is formed about each pole and at least 2 coils are formed about the inner member. When energized, the electromagnetic coils generate a modulated magnetic field that stabilizes the rotating member in the desired operational position.

  1. Disentangling the magnetic force noise contribution in LISA Pathfinder

    NASA Astrophysics Data System (ADS)

    Armano, M.; Audley, H.; Auger, G.; Baird, J.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Bursi, A.; Caleno, M.; Cavalleri, A.; Cesarini, A.; Cruise, M.; Danzmann, K.; Diepholz, I.; Dolesi, R.; Dunbar, N.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E.; Freschi, M.; Gallegos, J.; García Marirrodriga, C.; Gerndt, R.; Gesa, L. I.; Gibert, F.; Giardini, D.; Giusteri, R.; Grimani, C.; Harrison, I.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hueller, M.; Huesler, J.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johlander, B.; Karnesis, N.; Kaune, B.; Korsakova, N.; Killow, C.; Lloro, I.; Maarschalkerweerd, R.; Madden, S.; Mance, D.; Martín, V.; Martin-Porqueras, F.; Mateos, I.; McNamara, P.; Mendes, J.; Mendes, L.; Moroni, A.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Pivato, P.; Plagnol, E.; Prat, P.; Ragnit, U.; Ramos-Castro, J.; Reiche, J.; Romera Perez, J. A.; Robertson, D.; Rozemeijer, H.; Russano, G.; Sarra, P.; Schleicher, A.; Slutsky, J.; Sopuerta, C. F.; Sumner, T.; Texier, D.; Thorpe, J.; Trenkel, C.; Tu, H. B.; Vitale, S.; Wanner, G.; Ward, H.; Waschke, S.; Wass, P.; Wealthy, D.; Wen, S.; Weber, W.; Wittchen, A.; Zanoni, C.; Ziegler, T.; Zweifel, P.

    2015-05-01

    Magnetically-induced forces on the inertial masses on-board LISA Pathfinder are expected to be one of the dominant contributions to the mission noise budget, accounting for up to 40%. The origin of this disturbance is the coupling of the residual magnetization and susceptibility of the test masses with the environmental magnetic field. In order to fully understand this important part of the noise model, a set of coils and magnetometers are integrated as a part of the diagnostics subsystem. During operations a sequence of magnetic excitations will be applied to precisely determine the coupling of the magnetic environment to the test mass displacement using the on-board magnetometers. Since no direct measurement of the magnetic field in the test mass position will be available, an extrapolation of the magnetic measurements to the test mass position will be carried out as a part of the data analysis activities. In this paper we show the first results on the magnetic experiments during an end- to-end LISA Pathfinder simulation, and we describe the methods under development to map the magnetic field on-board.

  2. On the unsteady-motion theory of magnetic forces for maglev

    SciTech Connect

    Chen, S.S.; Zhu, S.; Cai, Y.

    1996-02-01

    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.

  3. Interactions between internal forces, body stiffness, and fluid environment in a neuromechanical model of lamprey swimming

    PubMed Central

    Tytell, Eric D.; Hsu, Chia-Yu; Williams, Thelma L.; Cohen, Avis H.; Fauci, Lisa J.

    2010-01-01

    Animal movements result from a complex balance of many different forces. Muscles produce force to move the body; the body has inertial, elastic, and damping properties that may aid or oppose the muscle force; and the environment produces reaction forces back on the body. The actual motion is an emergent property of these interactions. To examine the roles of body stiffness, muscle activation, and fluid environment for swimming animals, a computational model of a lamprey was developed. The model uses an immersed boundary framework that fully couples the Navier–Stokes equations of fluid dynamics with an actuated, elastic body model. This is the first model at a Reynolds number appropriate for a swimming fish that captures the complete fluid-structure interaction, in which the body deforms according to both internal muscular forces and external fluid forces. Results indicate that identical muscle activation patterns can produce different kinematics depending on body stiffness, and the optimal value of stiffness for maximum acceleration is different from that for maximum steady swimming speed. Additionally, negative muscle work, observed in many fishes, emerges at higher tail beat frequencies without sensory input and may contribute to energy efficiency. Swimming fishes that can tune their body stiffness by appropriately timed muscle contractions may therefore be able to optimize the passive dynamics of their bodies to maximize peak acceleration or swimming speed. PMID:21037110

  4. Magnetic Study of Paris Meteorite: a Partially Differentiated Parent Body?

    NASA Astrophysics Data System (ADS)

    Cournède, C.; Gattacceca, J.; Rochette, P.; Zanda, B.

    2011-12-01

    The Paris meteorite is a unique carbonaceous CM chondrite find with almost no traces of terrestrial weathering [1]. Contrary to others CM chondrites, that contain abundant magnetite formed during aqueous alteration on their parent body, Paris is characterized by the coexistence of magnetite and abundant metallic Fe-Ni. We conducted a magnetic study (magnetic properties and paleomagnetism) of several oriented samples of this meteorite, with masses ranging from several mg up to 17 g. Preliminary rock magnetism results confirm that Paris has a magnetic mineralogy that is notably different from that of other CM chondrites, with a dominant FeNi metal, and minor magnetite. This corroborate that Paris suffered less aqueous alteration than other CM chondrites. Anisotropy of magnetic susceptibility shows that Paris is also one of the most anisotropic CM chondrite, and that it has a homogeneous fabric at least at the centimeter-scale. The comparison of the remanent magnetization obtained for metal-rich and magnetite-rich samples may have provided constraints on the magnetic fields present before and after accretion respectively. Unfortunately, paleomagnetic data show that the meteorite has been exposed to strong artificial magnetic field (magnet), precluding the study of the possible soft natural magnetization carried by FeNi. However, a high-coercivity magnetization is still preserved in the meteorite. It is homogeneous in direction and intensity at the scale of the meteorite. We interpret it as a pre-terrestrial component acquired on the parent body in a field on 3 ± 1 ?T (estimated with the method described in [2]). In view of its coercivity (up to 120 mT) we suppose that this magnetization is carried by fine-grained magnetite (although thermal and chemical demagnetization experiments are needed to confirm this hypothesis). In this case, because crystallization of magnetite likely occurred several Myr after the formation of the solar system [3], i.e. after the possible existence of strong solar and nebular magnetic fields, the paleofield had to be generated by the parent body. In view of its intensity, this paleofield may have been an internally generated field, pointing to a partially differentiated parent body with a convecting metallic core. Such process has recently been proposed for the parent body of CV chondrites [4, 5]. [1] Zanda et al., 2010. Meteoritics Planetary Sci., 45, 222-222. [2] Gattacceca and Rochette, 2004. EPSL, 227, 377-393 [3] Petitat and Gounelle, 2010. LPSC, abstract #1673. [4] Carporzen et al., 2011. Proc. National Acad. Sci., 108, 6386-6389. [5] Elkins-Tanton et al., 2011. Earth Planet . Sci. Lett., 305, 1-10.

  5. Energy buildup in sheared force-free magnetic fields

    NASA Technical Reports Server (NTRS)

    Wolfson, Richard; Low, Boon C.

    1992-01-01

    Photospheric displacement of the footpoints of solar magnetic field lines results in shearing and twisting of the field, and consequently in the buildup of electric currents and magnetic free energy in the corona. The sudden release of this free energy may be the origin of eruptive events like coronal mass ejections, prominence eruptions, and flares. An important question is whether such an energy release may be accompanied by the opening of magnetic field lines that were previously closed, for such open field lines can provide a route for matter frozen into the field to escape the sun altogether. This paper presents the results of numerical calculations showing that opening of the magnetic field is permitted energetically, in that it is possible to build up more free energy in a sheared, closed, force-free magnetic field than is in a related magnetic configuration having both closed and open field lines. Whether or not the closed force-free field attains enough energy to become partially open depends on the form of the shear profile; the results presented compare the energy buildup for different shear profiles. Implications for solar activity are discussed briefly.

  6. Paramagnetic Beads and Magnetically Mediated Strain Enhance Cardiomyogenesis in Mouse Embryoid Bodies

    PubMed Central

    Geuss, Laura R.; Wu, Douglas C.; Ramamoorthy, Divya; Alford, Corinne D.; Suggs, Laura J.

    2014-01-01

    Mechanical forces play an important role in proper embryologic development, and similarly such forces can directly impact pluripotency and differentiation of mouse embryonic stem cells (mESC) in vitro. In addition, manipulation of the embryoid body (EB) microenvironment, such as by incorporation of microspheres or microparticles, can similarly influence fate determination. In this study, we developed a mechanical stimulation regimen using permanent neodymium magnets to magnetically attract cells within an EB. Arginine-Glycine-Aspartic Acid (RGD)-conjugated paramagnetic beads were incorporated into the interior of the EBs during aggregation, allowing us to exert force on individual cells using short-term magnetization. EBs were stimulated for one hour at different magnetic field strengths, subsequently exerting a range of force intensity on the cells at different stages of early EB development. Our results demonstrated that following exposure to a 0.2 Tesla magnetic field, ESCs respond to magnetically mediated strain by activating Protein Kinase A (PKA) and increasing phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) expression. The timing of stimulation can also be tailored to guide ESC differentiation: the combination of bone morphogenetic protein 4 (BMP4) supplementation with one hour of magnetic attraction on Day 3 enhances cardiomyogenesis by increasing contractile activity and the percentage of sarcomeric ?-actin-expressing cells compared to control samples with BMP4 alone. Interestingly, we also observed that the beads alone had some impact on differentiation by increasingly slightly, albeit not significantly, the percentage of cardiomyocytes. Together these results suggest that magnetically mediated strain can be used to enhance the percentage of mouse ESC-derived cardiomyocytes over current differentiation protocols. PMID:25501004

  7. Restoration the domain structure from magnetic force microscopy image

    NASA Astrophysics Data System (ADS)

    Wu, Dongping; Lou, Yuanfu; Wei, Fulin; Wei, Dan

    2012-04-01

    This contribution gives an approximation method to calculate the stray field of the scanning plane from the magnetic force microscopy (MFM) force gradient image. Before calculation, a Butterworth low-pass filter has been used to remove a part of the noise of the image. The discrete Fourier transform (DFT) method has been used to calculate the magnetic potential of the film surface. It shows that the potential is not correct because the low-frequency noise has been enlarged. The approximation method gives a better result of the potential and proves that the MFM force gradient of the perpendicular component image also gives the perpendicular component of the stray field. Supposing that the distance between the tip and the sample is as small as near zero, the force gradient image also gives the magnetic charge distribution of the film surface. So if the orientation of the film from hysteresis loop is known, then the domain structure of the film can be determined. For perpendicular orientation, the absolution value of the perpendicular component of stray field gives the domain and domain wall position. For in-plane orientation, the absolution value of in-plane component of stray field gives the domain and domain wall position.

  8. Magnetic nasal foreign bodies: a result of fashion mania.

    PubMed

    Karkos, P D; Karagama, Y G; Manivasagam, A; El Badawey, M Reda

    2003-12-01

    The fashion of body piercing among adults has encouraged children to have similar procedures or imitate them by applying small magnets to sustain the jewelery used in piercing in position [Emerg. Med. J. 19 (2002) 71]. We present cases of children who have placed magnets on their nasal alae that became misplaced on to the nasal septum causing severe pain and in some cases nasal bleeding and septal perforation. We describe management of these cases. PMID:14643479

  9. Height and body composition determine arm propulsive force in youth swimmers independent of a maturation stage.

    PubMed

    Moura, Tatiane; Costa, Manoel; Oliveira, Saulo; Júnior, Marcos Barbosa; Ritti-Dias, Raphael; Santos, Marcos

    2014-09-29

    The aim of this study was to examine the relationship between anthropometric variables, body composition and propulsive force in swimmers aged 9-17 years. Anthropometric characteristics (body height and mass, sitting height, arm span, arm muscle area and body composition) and the propulsive force of the arm (tethered swimming test) were evaluated in 56 competitive male swimmers. Tanner's stages of genital maturation (P1-5) were used. The data analysis included correlations and multiple linear regression. The propulsive force of the arm was correlated with body height (r = 0.34; p =0.013), arm span (r = 0.29; p =0.042), sitting height (r = 0.36; p =0.009), % body fat (r = 0.33; p =0.016), lean body mass (r = 0.34; p =0.015) and arm muscle area (r = 0.31; p =0.026). Using multiple linear regression models, the percent body fat and height were identified as significant predictors of the propulsive force of the arm after controlling for the maturation stage. This model explained 22% (R2 = 0.22) of associations. In conclusion, the propulsive force of swimmers was related to body height and percent body fat. PMID:25414760

  10. Height and Body Composition Determine Arm Propulsive Force in Youth Swimmers Independent of a Maturation Stage

    PubMed Central

    Moura, Tatiane; Costa, Manoel; Oliveira, Saulo; Júnior, Marcos Barbosa; Ritti-Dias, Raphael; Santos, Marcos

    2014-01-01

    The aim of this study was to examine the relationship between anthropometric variables, body composition and propulsive force in swimmers aged 9–17 years. Anthropometric characteristics (body height and mass, sitting height, arm span, arm muscle area and body composition) and the propulsive force of the arm (tethered swimming test) were evaluated in 56 competitive male swimmers. Tanner’s stages of genital maturation (P1–5) were used. The data analysis included correlations and multiple linear regression. The propulsive force of the arm was correlated with body height (r = 0.34; p =0.013), arm span (r = 0.29; p =0.042), sitting height (r = 0.36; p =0.009), % body fat (r = 0.33; p =0.016), lean body mass (r = 0.34; p =0.015) and arm muscle area (r = 0.31; p =0.026). Using multiple linear regression models, the percent body fat and height were identified as significant predictors of the propulsive force of the arm after controlling for the maturation stage. This model explained 22% (R2 = 0.22) of associations. In conclusion, the propulsive force of swimmers was related to body height and percent body fat. PMID:25414760

  11. Magnetic force micropiston: An integrated force/microfluidic device for the application of compressive forces in a confined environment

    NASA Astrophysics Data System (ADS)

    Fisher, J. K.; Kleckner, N.

    2014-02-01

    Cellular biology takes place inside confining spaces. For example, bacteria grow in crevices, red blood cells squeeze through capillaries, and chromosomes replicate inside the nucleus. Frequently, the extent of this confinement varies. Bacteria grow longer and divide, red blood cells move through smaller and smaller passages as they travel to capillary beds, and replication doubles the amount of DNA inside the nucleus. This increase in confinement, either due to a decrease in the available space or an increase in the amount of material contained in a constant volume, has the potential to squeeze and stress objects in ways that may lead to changes in morphology, dynamics, and ultimately biological function. Here, we describe a device developed to probe the interplay between confinement and the mechanical properties of cells and cellular structures, and forces that arise due to changes in a structure's state. In this system, the manipulation of a magnetic bead exerts a compressive force upon a target contained in the confining space of a microfluidic channel. This magnetic force microfluidic piston is constructed in such a way that we can measure (a) target compliance and changes in compliance as induced by changes in buffer, extract, or biochemical composition, (b) target expansion force generated by changes in the same parameters, and (c) the effects of compression stress on a target's structure and function. Beyond these issues, our system has general applicability to a variety of questions requiring the combination of mechanical forces, confinement, and optical imaging.

  12. Analytical equation of state with three-body forces: Application to noble gases

    SciTech Connect

    Río, Fernando del Díaz-Herrera, Enrique; Guzmán, Orlando; Moreno-Razo, José Antonio; Ramos, J. Eloy

    2013-11-14

    We developed an explicit equation of state (EOS) for small non polar molecules by means of an effective two-body potential. The average effect of three-body forces was incorporated as a perturbation, which results in rescaled values for the parameters of the two-body potential. These values replace the original ones in the EOS corresponding to the two-body interaction. We applied this procedure to the heavier noble gases and used a modified Kihara function with an effective Axilrod-Teller-Muto (ATM) term to represent the two- and three-body forces. We also performed molecular dynamics simulations with two- and three-body forces. There was good agreement between predicted, simulated, and experimental thermodynamic properties of neon, argon, krypton, and xenon, up to twice the critical density and up to five times the critical temperature. In order to achieve 1% accuracy of the pressure at liquid densities, the EOS must incorporate the effect of ATM forces. The ATM factor in the rescaled two-body energy is most important at temperatures around and lower than the critical one. Nonetheless, the rescaling of two-body diameter cannot be neglected at liquid-like densities even at high temperature. This methodology can be extended straightforwardly to deal with other two- and three-body potentials. It could also be used for other nonpolar substances where a spherical two-body potential is still a reasonable coarse-grain approximation.

  13. Analytical equation of state with three-body forces: application to noble gases.

    PubMed

    del Río, Fernando; Díaz-Herrera, Enrique; Guzmán, Orlando; Moreno-Razo, José Antonio; Ramos, J Eloy

    2013-11-14

    We developed an explicit equation of state (EOS) for small non polar molecules by means of an effective two-body potential. The average effect of three-body forces was incorporated as a perturbation, which results in rescaled values for the parameters of the two-body potential. These values replace the original ones in the EOS corresponding to the two-body interaction. We applied this procedure to the heavier noble gases and used a modified Kihara function with an effective Axilrod-Teller-Muto (ATM) term to represent the two- and three-body forces. We also performed molecular dynamics simulations with two- and three-body forces. There was good agreement between predicted, simulated, and experimental thermodynamic properties of neon, argon, krypton, and xenon, up to twice the critical density and up to five times the critical temperature. In order to achieve 1% accuracy of the pressure at liquid densities, the EOS must incorporate the effect of ATM forces. The ATM factor in the rescaled two-body energy is most important at temperatures around and lower than the critical one. Nonetheless, the rescaling of two-body diameter cannot be neglected at liquid-like densities even at high temperature. This methodology can be extended straightforwardly to deal with other two- and three-body potentials. It could also be used for other nonpolar substances where a spherical two-body potential is still a reasonable coarse-grain approximation. PMID:24320280

  14. On the unsteady-motion theory of magnetic forces for maglev

    SciTech Connect

    Chen, S.S.; Zhu, S.; Cai, Y.

    1993-11-01

    Motion-dependent magnetic forces are the key elements in the study of magnetically levitated vehicle (maglev) system dynamics. In the past, most maglev-system designs were based on a quasisteady-motion theory of magnetic forces. This report presents an experimental and analytical study that will enhance our 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.

  15. Prediction of forces and moments on finned bodies at high angle of attack in transonic flow

    SciTech Connect

    Oberkampf, W. L.

    1981-04-01

    This report describes a theoretical method for the prediction of fin forces and moments on bodies at high angle of attack in subsonic and transonic flow. The body is assumed to be a circular cylinder with cruciform fins (or wings) of arbitrary planform. The body can have an arbitrary roll (or bank) angle, and each fin can have individual control deflection. The method combines a body vortex flow model and lifting surface theory to predict the normal force distribution over each fin surface. Extensive comparisons are made between theory and experiment for various planform fins. A description of the use of the computer program that implements the method is given.

  16. Force analysis of magnetic bearings with power-saving controls

    NASA Technical Reports Server (NTRS)

    Johnson, Dexter; Brown, Gerald V.; Inman, Daniel J.

    1992-01-01

    Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. For most operating conditions, the existence of the bias current requires more power than alternative methods that do not use conventional bias. Two such methods are examined which diminish or eliminate bias current. In the typical bias control scheme it is found that for a harmonic control force command into a voltage limited transconductance amplifier, the desired force output is obtained only up to certain combinations of force amplitude and frequency. Above these values, the force amplitude is reduced and a phase lag occurs. The power saving alternative control schemes typically exhibit such deficiencies at even lower command frequencies and amplitudes. To assess the severity of these effects, a time history analysis of the force output is performed for the bias method and the alternative methods. Results of the analysis show that the alternative approaches may be viable. The various control methods examined were mathematically modeled using nondimensionalized variables to facilitate comparison of the various methods.

  17. Apparatus having reduced mechanical forces for supporting high magnetic fields

    DOEpatents

    Prueitt, Melvin L. (Los Alamos, NM); Mueller, Fred M. (Los Alamos, NM); Smith, James L. (Los Alamos, NM)

    1991-01-01

    The present invention identifies several configurations of conducting elements capable of supporting extremely high magnetic fields suitable for plasma confinement, wherein forces experienced by the conducting elements are significantly reduced over those which are present as a result of the generation of such high fields by conventional techniques. It is anticipated that the use of superconducting materials will both permit the attainment of such high fields and further permit such fields to be generated with vastly improved efficiency.

  18. A spaceship with a thruster - one body, one force

    E-print Network

    Dudley, S C; Dudley, Scott C.; Serna, Mario A.

    2004-01-01

    A spaceship with one thruster producing a constant magnitude force is analyzed for various initial conditions. This elementary problem, with one object acted upon by one force, has value as a challenge to one's physical intuition and in demonstrating the benefits and limitations of dimensional analysis. In addition, the problem can serve to introduce a student to special functions, provide a mechanical model for Fresnel integrals and the associated Cornu spiral, or be used as an example in a numerical methods course. The problem has some interesting and perhaps unexpected features.

  19. Microscopic Three-Body Force Effect on Nucleon-Nucleon Cross Sections in Symmetric Nuclear Matter

    NASA Astrophysics Data System (ADS)

    Zhang, Hong-Fei; Zuo, Wei; Lombardo, Umberto; Li, Zeng-Hua; Li, Jun-Qing

    2008-11-01

    We provide a microscopic calculation of neutron-proton and proton-proton cross sections in symmetric nuclear matter at various densities, using the Brueckner Hartree Fock approximation scheme with the Argonne V14 potential including the contribution of microscopic three-body force. We investigate separately the effects of three-body force on the effective mass and on the scattering amplitude. In the present calculation, the rearrangement contribution of three-body force is considered, which will reduce the neutron and proton effective mass, and depress the amplitude of cross section. The effect of three body force is shown to be repulsive, especially in high densities and large momenta, which will suppress the cross section markedly.

  20. Experimental investigation of side force control on cone-cylinder slender bodies with flexible micro balloon actuators

    E-print Network

    Leu, Tzong-Shyng "Jeremy"

    Experimental investigation of side force control on cone-cylinder slender bodies with flexible; accepted 31 December 2004 Abstract Side forces on slender bodies of revolution at medium to high angles a slender body are believed to be the principle cause of the side forces. Under some flight conditions

  1. Three-body forces and proton-rich nuclei.

    PubMed

    Holt, J D; Menéndez, J; Schwenk, A

    2013-01-11

    We present the first study of three-nucleon (3N) forces for proton-rich nuclei along the N=8 and N=20 isotones. Our results for the ground-state energies and proton separation energies are in very good agreement with experiment where available, and with the empirical isobaric multiplet mass equation. We predict the spectra for all N=8 and N=20 isotones to the proton dripline, which agree well with experiment for 18Ne, 19Na, 20Mg and 42Ti. In all other cases, we provide first predictions based on nuclear forces. Our results are also very promising for studying isospin symmetry breaking in medium-mass nuclei based on chiral effective field theory. PMID:23383896

  2. Three-Body Forces and Proton-Rich Nuclei

    SciTech Connect

    Holt, Jason D; Menendez, J.

    2013-01-01

    We present the first study of three-nucleon (3N) forces for proton-rich nuclei along the N 8 and N 20 isotones. Our results for the ground-state energies and proton separation energies are in very good agreement with experiment where available, and with the empirical isobaric multiplet mass equation. We predict the spectra for all N 8 and N 20 isotones to the proton dripline, which agree well with experiment for 18Ne, 19Na, 20Mg and 42Ti. In all other cases, we provide first predictions based on nuclear forces. Our results are also very promising for studying isospin symmetry breaking in medium-mass nuclei based on chiral effective field theory.

  3. http://topex.ucsd.edu/body_force Analytic and Numeric Tests of Fourier Deformation Model

    E-print Network

    Sandwell, David T.

    http://topex.ucsd.edu/body_force 1 Analytic and Numeric Tests of Fourier Deformation Model model vi.) Example of time-dependence for viscoelastic San Andreas model #12;http://topex.ucsd.edu/body of these faulting behaviors for our Fourier-derived fault solution. In order to form a double-couple dislocation, we

  4. The Aerodynamic Forces on Slender Plane- and Cruciform-Wing and Body Combinations

    NASA Technical Reports Server (NTRS)

    Spreiter, John R

    1950-01-01

    The load distribution, forces, and moments are calculated theoretically for inclined slender wing-body combinations consisting of a slender body of revolution and either a plane or cruciform arrangement of low-aspect-ratio pointed wings. The results are applicable at subsonic and transonic speeds, and at supersonic speeds, provided the entire wing-body combination lies near the center of the Mach cone.

  5. Magnetic evidence for a partially differentiated carbonaceous chondrite parent body

    PubMed Central

    Carporzen, Laurent; Weiss, Benjamin P.; Elkins-Tanton, Linda T.; Shuster, David L.; Ebel, Denton; Gattacceca, Jérôme

    2011-01-01

    The textures of chondritic meteorites demonstrate that they are not the products of planetary melting processes. This has long been interpreted as evidence that chondrite parent bodies never experienced large-scale melting. As a result, the paleomagnetism of the CV carbonaceous chondrite Allende, most of which was acquired after accretion of the parent body, has been a long-standing mystery. The possibility of a core dynamo like that known for achondrite parent bodies has been discounted because chondrite parent bodies are assumed to be undifferentiated. Resolution of this conundrum requires a determination of the age and timescale over which Allende acquired its magnetization. Here, we report that Allende’s magnetization was acquired over several million years (Ma) during metasomatism on the parent planetesimal in a >  ? 20 ?T field up to approximately 9—10 Ma after solar system formation. This field was present too recently and directionally stable for too long to have been generated by the protoplanetary disk or young Sun. The field intensity is in the range expected for planetesimal core dynamos, suggesting that CV chondrites are derived from the outer, unmelted layer of a partially differentiated body with a convecting metallic core.

  6. Magnetic force microscopy of alternating magnetic field gradient by frequency modulation of tip oscillation

    NASA Astrophysics Data System (ADS)

    Saito, H.; Ikeya, H.; Egawa, G.; Ishio, S.; Yoshimura, S.

    2009-04-01

    A new magnetic force microscopy (MFM) technique for measuring alternating magnetic field (ac magnetic field) was proposed by using frequency modulation (FM) phenomenon of tip oscillation. We detected a narrowband FM phenomenon in the tip oscillation of a high-coercivity MFM tip by applying an ac magnetic field to the tip by using a metal-in-gap (MIG) type ring head. In the experiment, the MFM tip was driven at a constant frequency fc near the resonant frequency of the cantilever by a piezoelectric element, and the ac magnetic field with a frequency fm up to 10 kHz was applied to the MFM tip. Two sideband spectra with a frequency of fc±fm were observed by applying ac magnetic field. The intensity of sideband spectra increased linearly with increasing applied current value of the MIG head. It was observed that FM occurred from the analysis of frequency spectra of the MFM signals. This FM phenomenon is caused by the force applied on the cantilever by the field gradient of the head. The FM phenomenon is understood by solving the differential equation for the harmonic oscillator of which the effective spring constant is changed periodically by ac magnetic field. The FM phenomenon can be used for imaging ac magnetic fields.

  7. Particle energization in a chaotic force-free magnetic field

    NASA Astrophysics Data System (ADS)

    Li, Xiaocan; Li, Gang; Dasgupta, Brahmananda

    2015-04-01

    A force-free field (FFF) is believed to be a reasonable description of the solar corona and in general a good approximation for low-beta plasma. The equations describing the magnetic field of FFF is similar to the ABC fluid equations which has been demonstrated to be chaotic. This implies that charged particles will experience chaotic magnetic field in the corona. Here, we study particle energization in a time-dependent FFF using a test particle approach. An inductive electric field is introduced by turbulent motions of plasma parcels. We find efficient particle acceleration with power-law like particle energy spectra. The power-law indices depend on the amplitude of plasma parcel velocity field and the spatial scales of the magnetic field fluctuation. The spectra are similar for different particle species. This model provide a possible mechanism for seed population generation for particle acceleration by, e.g., CME-driven shocks. Generalization of our results to certain non-force-free-field (NFFF) is straightforward as the sum of two or multiple FFFs naturally yield NFFF.

  8. Probing cellular traction forces with magnetic nanowires and microfabricated force sensor This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-print Network

    Chen, Christopher S.

    nanowires' for separating and positioning cells in suspension under the control of external magnetic fieldsProbing cellular traction forces with magnetic nanowires and microfabricated force sensor arrays.1088/0957-4484/23/7/075101 Probing cellular traction forces with magnetic nanowires and microfabricated force sensor arrays Yi

  9. Variable force, eddy-current or magnetic damper

    NASA Technical Reports Server (NTRS)

    Cunningham, R. E. (inventor)

    1985-01-01

    An object of the invention is to provide variable damping for resonant vibrations which may occur at different rotational speeds in the range of rpms in which a rotating machine is operated. A variable force damper in accordance with the invention includes a rotating mass carried on a shaft which is supported by a bearing in a resilient cage. The cage is attached to a support plate whose rim extends into an annular groove in a housing. Variable damping is effected by tabs of electrically conducting nonmagnetic material which extend radially from the cage. The tabs at an index position lie between the pole face of respective C shaped magnets. The magnets are attached by cantilever spring members to the housing.

  10. Drag measurements on a laminar-flow body of revolution in the 13-inch magnetic suspension and balance system

    NASA Technical Reports Server (NTRS)

    Dress, David A.

    1989-01-01

    Low speed wind tunnel drag force measurements were taken on a laminar flow body of revolution free of support interference. This body was tested at zero incidence in the NASA Langley 13 in. Magnetic Suspension and Balance System (MSBS). The primary objective of these tests was to substantiate the drag force measuring capabilities of the 13 in. MSBS. The drag force calibrations and wind-on repeatability data provide a means of assessing these capabilities. Additional investigations include: (1) the effects of fixing transition; (2) the effects of fins installed in the tail; and (3) surface flow visualization using both liquid crystals and oil flow. Also two simple drag prediction codes were used to assess their usefulness in estimating overall body drag.

  11. Lower body predictors of glenohumeral compressive force in high school baseball pitchers.

    PubMed

    Keeley, David W; Oliver, Gretchen D; Dougherty, Christopher P; Torry, Michael R

    2015-06-01

    The purpose of this study was to better understand how lower body kinematics relate to peak glenohumeral compressive force and develop a regression model accounting for variability in peak glenohumeral compressive force. Data were collected for 34 pitchers. Average peak glenohumeral compressive force was 1.72% ± 33% body weight (1334.9 N ± 257.5). Correlation coefficients revealed 5 kinematic variables correlated to peak glenohumeral compressive force (P < .01, ? = .025). Regression models indicated 78.5% of the variance in peak glenohumeral compressive force (R2 = .785, P < .01) was explained by stride length, lateral pelvis flexion at maximum external rotation, and axial pelvis rotation velocity at release. These results indicate peak glenohumeral compressive force increases with a combination of decreased stride length, increased pelvic tilt at maximum external rotation toward the throwing arm side, and increased pelvis axial rotation velocity at release. Thus, it may be possible to decrease peak glenohumeral compressive force by optimizing the movements of the lower body while pitching. Focus should be on both training and conditioning the lower extremity in an effort to increase stride length, increase pelvis tilt toward the glove hand side at maximum external rotation, and decrease pelvis axial rotation at release. PMID:25734579

  12. Low-temperature high-resolution magnetic force microscopy using a quartz tuning fork

    E-print Network

    Chandrasekhar, Venkat

    heat dissipation. Using a tuning fork as a force transducer in a MFM overcomes many of the drawbacksLow-temperature high-resolution magnetic force microscopy using a quartz tuning fork Yongho Seo August 2005 We have developed a low-temperature high resolution magnetic force microscope MFM using

  13. How Can Magnetic Forces Do Work? Investigating the Problem with Students

    ERIC Educational Resources Information Center

    Onorato, Pasquale; De Ambrosis, Anna

    2013-01-01

    We present a sequence of activities aimed at promoting both learning about magnetic forces and students' reflection about the conceptual bridge between magnetic forces on a moving charge and on a current-carrying wire in a magnetic field. The activity sequence, designed for students in high school or on introductory physics courses, has been…

  14. The effect of power-law body forces on a thermally driven flow between concentric rotating spheres

    NASA Technical Reports Server (NTRS)

    Macaraeg, M. G.

    1986-01-01

    A numerical study is conducted to determine the effect of power-law body forces on a thermally-driven axisymmetric flow field confined between concentric co-rotating spheres. This study is motivated by Spacelab geophysical fluid-flow experiments, which use an electrostatic force on a dielectric fluid to simulate gravity; this force exhibits a (1/r)sup 5 distribution. Meridional velocity is found to increase when the electrostatic body force is imposed, relative to when the body force is uniform. Correlation among flow fields with uniform, inverse-square, and inverse-quintic force fields is obtained using a modified Grashof number.

  15. The effect of power law body forces on a thermally-driven flow between concentric rotating spheres

    NASA Technical Reports Server (NTRS)

    Macaraeg, M. G.

    1985-01-01

    A numerical study is conducted to determine the effect of power-law body forces on a thermally-driven axisymmetric flow field confined between concentric co-rotating spheres. This study is motivated by Spacelab geophysical fluid-flow experiments, which use an electrostatic force on a dielectric fluid to simulate gravity; this force exhibits a (1/r)sup 5 distribution. Meridional velocity is found to increase when the electrostatic body force is imposed, relative to when the body force is uniform. Correlation among flow fields with uniform, inverse-square, and inverse-quintic force fields is obtained using a modified Grashof number.

  16. Magnetic force microscopy of magnetic domains in UMn2Ge2

    NASA Astrophysics Data System (ADS)

    Berg, Morgann; de Lozanne, Alex; Baumbach, Ryan E.; Kim, Jeehoon; Bauer, Eric D.; Thompson, Joe D.; Ronning, Filip

    2014-03-01

    UMn2Ge2, a distant cousin to the heavy-fermion compound URu2Si2, is a ternary intermetallic compound with a tetragonal crystal structure of type ThCr2Si2 and with space group I4/mmm. Local U and Mn moments in UMn2Ge2 order on their respective sublattices at temperatures near 100 and 380 K, respectively. Previous high-pressure x-ray diffraction and Kerr rotation angle measurements point to structural and magnetic phase transitions that reflect the competition between U and Mn spins at low temperatures. As U moments order with a reduction in temperature, they are predicted to align the Mn moments along the c-axis, altering the anisotropy of the material and the easy axis direction. A reduction of inter-atomic distances between the U and Mn atoms is also projected to induce hybridization between uranium 5f and manganese 3d states, leading to a delocalization of magnetic moments and reduction in magnetization. We use a variable temperature atomic force microscope in magnetic force microscopy (MFM) mode to obtain some initial images of magnetic domains in UMn2Ge2. Room temperature MFM images display branching magnetic domains with uniaxial anisotropy. Supported by NSF grant DMR-0810119.

  17. Effects of body force on transient poroelastic consolidation due to groundwater pumping

    NASA Astrophysics Data System (ADS)

    Tseng, Chung-Min; Tsai, Tung-Lin; Huang, Liang-Hsiung

    2008-06-01

    By applying linear poro-elasticity theory, the body force effect on steady soil consolidation, i.e., settlement, caused by constant water table depression due to groundwater pumping was investigated. The result shows that when the soil is soft or thick, or both, neglecting the body force effect can lead to severe underestimation of soil displacement and incremental effective stress. However, the transient response of soil consolidation was not analyzed. In addition, the water table depression due to groundwater pumping in fact varies with time. In this study, the body force effect on transient consolidation of soil subjected to variable water table depression is further examined. A poroelastic consolidation numerical model is developed herein to conduct this examination.

  18. Resistance force of a shock absorber using magnetic functional fluids containing both micrometer-sized and nanometer-sized magnetic particles

    NASA Astrophysics Data System (ADS)

    Hayashi, Koichi; Yamada, Takatomo; Ido, Yasushi

    In this paper, properties of resistance force of a shock absorber using magnetic functional fluids having both micrometer- and nanometer-sized magnetic particles are reported. The resistance force can be controlled by changing strength of the magnetic field applied to the magnetic functional fluid. The resistance force is influenced by the mixture ratio of the micrometer- to the nanometer-sized magnetic particles.

  19. Development of Swimming Human Simulation Model Considering Rigid Body Dynamics and Unsteady Fluid Force for Whole Body

    NASA Astrophysics Data System (ADS)

    Nakashima, Motomu; Satou, Ken; Miura, Yasufumi

    The purpose of this study is to develop a swimming human simulation model considering rigid body dynamics and unsteady fluid force for the whole body, which will be utilized to analyze various dynamical problems in human swimming. First, the modeling methods and their formulations for the human body and the fluid force are respectively described. Second, experiments to identify the coefficients of the normal drag and the added mass are conducted by use of an experimental setup, in which a limb model rotates in the water, and its rotating angle and the bending moment at the root are measured. As the result of the identification, the present model for the fluid force was found to have satisfactory performance in order to represent the unsteady fluctuations of the experimental data, although it has 10% error. Third, a simulation for the gliding position is conducted in order to identify the tangential drag coefficient. Finally, a simulation example of standard six beat front crawl swimming is shown. The swimming speed of the simulation became a reasonable value, indicating the validity of the present simulation model, although it is 7.5% lower than the actual swimming.

  20. Magnetic resonance force microscopy and a solid state quantum computer.

    SciTech Connect

    Pelekhov, D. V.; Martin, I.; Suter, A.; Reagor, D. W.; Hammel, P. C.

    2001-01-01

    A Quantum Computer (QC) is a device that utilizes the principles of Quantum Mechanics to perform computations. Such a machine would be capable of accomplishing tasks not achievable by means of any conventional digital computer, for instance factoring large numbers. Currently it appears that the QC architecture based on an array of spin quantum bits (qubits) embedded in a solid-state matrix is one of the most promising approaches to fabrication of a scalable QC. However, the fabrication and operation of a Solid State Quantum Computer (SSQC) presents very formidable challenges; primary amongst these are: (1) the characterization and control of the fabrication process of the device during its construction and (2) the readout of the computational result. Magnetic Resonance Force Microscopy (MRFM)--a novel scanning probe technique based on mechanical detection of magnetic resonance-provides an attractive means of addressing these requirements. The sensitivity of the MRFM significantly exceeds that of conventional magnetic resonance measurement methods, and it has the potential for single electron spin detection. Moreover, the MRFM is capable of true 3D subsurface imaging. These features will make MRFM an invaluable tool for the implementation of a spin-based QC. Here we present the general principles of MRFM operation, the current status of its development and indicate future directions for its improvement.

  1. Locating and quantifying ceramic body armor impact forces on a compliant torso using acceleration mapping

    NASA Astrophysics Data System (ADS)

    Cardi, Adam A.; Adams, Douglas E.; Walsh, Shawn

    2006-03-01

    This research experimentally implements a new method to identify the location and magnitude of a single impulsive excitation to ceramic body armor, which is supported on a compliant torso. The method could easily be extended to other flexibly supported components that undergo rigid body dynamics. Impact loads are identified in two steps. First, the location of the impact force is determined from time domain acceleration responses by comparing them to an array of reference acceleration time histories. Then based on the estimated location, reference frequency response functions are used to reconstruct the input force in the frequency domain through a least squares inverse problem. Experimental results demonstrate the validity of this method at both low energy excitations, which are produced by a medium modally-tuned impact hammer, and at high energy excitations, which are produced by dropping rods with masses up to 0.6 kilograms from a height of 2 meters. The maximum error in the estimated location or magnitude for the low energy excitations on the 10 cm square ceramic body armor was 7.07 mm with an average error of 1.09 mm. In comparing the estimated force for the low energy excitations to the force recorded by the transducer in the modal impact hammer, the maximum error in the predicted force amplitude was 6.78 percent and the maximum error in the predicted impulse was 6.44 percent. For the high energy excitations, which produced accelerations at the measurement locations up to 50 times greater than that of the low energy excitations, the maximum error in the predicted location of the input force was 15 mm with an average error of 6.64 mm. There was no force transducer to capture the input force on the body armor from the rod, but from non-energy-dissipative projectile motion equations the validity of the solutions was confirmed by comparing the impulses.

  2. Magnetic force acting on a magnetic dipole over a superconducting thin film

    SciTech Connect

    Wei, J.C.; Chen, J.L.; Horng, L.; Yang, T.J.

    1996-12-01

    The magnetostatic interaction energy and corresponding magnetic force acting on a magnetic point dipole placed above a type-II thin superconducting film in the mixed state with a single vortex are calculated using electromagnetics coupled with the London theory of superconductivity. If a vortex is trapped by a circular defect of radius {ital b}{lt}{Lambda}, the magnetic forces, caused by the vortex, differ from the results of free from defect pinning by the factor (1{minus}{ital b}/{Lambda}), where {Lambda} is the effective penetration depth. The possibility of formation of the vortex in the thin film only in the field of the magnetic point dipole is investigated. The critical position of the dipole for creating the first vortex under the electromagnetic pinning of a circular defect and that position in the absence of defect pinning are obtained for comparison. In particular, in the limit of {ital a}/{Lambda}{gt}1, where {ital a} is the separation between the dipole and the thin film, the only difference between two results is in the cutoff length, i.e., in the case of a circular defect the only difference in the critical position calculation is the cutoff at radius {ital b} rather than at coherence length {xi}. The pinning force of a single vortex by a circular defect is also calculated. Further, we investigate the conditions of the vortex creation for various cases (including the first, second, and third vortices) for a free of pinning center in the examining region. It is found that the creation of a new single vortex in the thin film causes an abrupt change in vertical levitation force: the force changed discontinuously. {copyright} {ital 1996 The American Physical Society.}

  3. Apparatus for storing high magnetic fields having reduced mechanical forces and reduced magnetic pollution

    DOEpatents

    Prueitt, Melvin L. (Los Alamos, NM); Mueller, Fred M. (Los Alamos, NM); Smith, James L. (Los Alamos, NM)

    1991-01-01

    The present invention identifies several configurations of conducting elements capable of storing extremely high magnetic fields for the purpose of energy storage or for other uses, wherein forces experienced by the conducting elements and the magnetic field pollution produced at locations away from the configuration are both significantly reduced over those which are present as a result of the generation of such high fields by currently proposed techniques. It is anticipated that the use of superconducting materials will both permit the attainment of such high fields and further permit such fields to be generated with vastly improved efficiency.

  4. Apparatus for storing high magnetic fields having reduced mechanical forces and reduced magnetic pollution

    DOEpatents

    Prueitt, M.L.; Mueller, F.M.; Smith, J.L.

    1991-04-09

    The present invention identifies several configurations of conducting elements capable of storing extremely high magnetic fields for the purpose of energy storage or for other uses, wherein forces experienced by the conducting elements and the magnetic field pollution produced at locations away from the configuration are both significantly reduced over those which are present as a result of the generation of such high fields by currently proposed techniques. It is anticipated that the use of superconducting materials will both permit the attainment of such high fields and further permit such fields to be generated with vastly improved efficiency. 15 figures.

  5. Three-Body Forces Produced by a Similarity Renormalization Group Transformation in a Simple Model

    E-print Network

    Bogner, S K; Perry, R J

    2007-01-01

    A simple class of unitary renormalization group transformations that force hamiltonians towards a band-diagonal form produce few-body interactions in which low- and high-energy states are decoupled, which can greatly simplify many-body calculations. One such transformation has been applied to phenomenological and effective field theory nucleon-nucleon interactions with success, but further progress requires consistent treatment of at least the three-nucleon interaction. In this paper we demonstrate in an extremely simple model how these renormalization group transformations consistently evolve two- and three-body interactions towards band-diagonal form, and introduce a diagrammatic approach that generalizes to the realistic nuclear problem.

  6. Wing and body motion and aerodynamic and leg forces during take-off in droneflies

    PubMed Central

    Chen, Mao Wei; Zhang, Yan Lai; Sun, Mao

    2013-01-01

    Here, we present a detailed analysis of the take-off mechanics in droneflies performing voluntary take-offs. Wing and body kinematics of the insects during take-off were measured using high-speed video techniques. Based on the measured data, the inertia force acting on the insect was computed and the aerodynamic force of the wings was calculated by the method of computational fluid dynamics. Subtracting the aerodynamic force and the weight from the inertia force gave the leg force. In take-off, a dronefly increases its stroke amplitude gradually in the first 10–14 wingbeats and becomes airborne at about the 12th wingbeat. The aerodynamic force increases monotonously from zero to a value a little larger than its weight, and the leg force decreases monotonously from a value equal to its weight to zero, showing that the droneflies do not jump and only use aerodynamic force of flapping wings to lift themselves into the air. Compared with take-offs in insects in previous studies, in which a very large force (5–10 times of the weight) generated either by jumping legs (locusts, milkweed bugs and fruit flies) or by the ‘fling’ mechanism of the wing pair (butterflies) is used in a short time, the take-off in the droneflies is relatively slow but smoother. PMID:24132205

  7. Wing and body motion and aerodynamic and leg forces during take-off in droneflies.

    PubMed

    Chen, Mao Wei; Zhang, Yan Lai; Sun, Mao

    2013-12-01

    Here, we present a detailed analysis of the take-off mechanics in droneflies performing voluntary take-offs. Wing and body kinematics of the insects during take-off were measured using high-speed video techniques. Based on the measured data, the inertia force acting on the insect was computed and the aerodynamic force of the wings was calculated by the method of computational fluid dynamics. Subtracting the aerodynamic force and the weight from the inertia force gave the leg force. In take-off, a dronefly increases its stroke amplitude gradually in the first 10-14 wingbeats and becomes airborne at about the 12th wingbeat. The aerodynamic force increases monotonously from zero to a value a little larger than its weight, and the leg force decreases monotonously from a value equal to its weight to zero, showing that the droneflies do not jump and only use aerodynamic force of flapping wings to lift themselves into the air. Compared with take-offs in insects in previous studies, in which a very large force (5-10 times of the weight) generated either by jumping legs (locusts, milkweed bugs and fruit flies) or by the 'fling' mechanism of the wing pair (butterflies) is used in a short time, the take-off in the droneflies is relatively slow but smoother. PMID:24132205

  8. Control of a three-dimensional magnetic force generated from a magnetic navigation system to precisely manipulate the locomotion of a magnetic microrobot

    NASA Astrophysics Data System (ADS)

    Nam, J. K.; Jeon, S. M.; Lee, W. S.; Jang, G. H.

    2015-05-01

    We propose a method to generate a three-dimensional (3D) magnetic force to manipulate a magnetic microrobot in various environments by using a magnetic navigation system. The proposed method is based on the control of the magnetic force with respect to the change in the magnetization direction of the microrobot and an external magnetic flux gradient. We derived the nonlinear constraint equations which can determine the required direction of the uniform magnetic fields and magnetic gradients to generate the 3D magnetic force of a microrobot. The solutions of the equations were calculated using a geometrical analysis of the equations without any singular point. The proposed methodology was verified on 3D planar environments considering gravitational force, and we also conducted an experiment in a 3D water-filled tubular environment to verify the possibility of the clinical application in human blood vessels.

  9. Levitation force on a permanent magnet over a superconducting plane: Modified critical-state model

    SciTech Connect

    Yang, Z.J.

    1997-08-01

    The authors consider a model system of a permanent magnet above a semi-infinite superconductor. They introduce a modified critical-state model, and carry out derivations of the levitation force acting on the magnet. A key feature of the modification allows the current density to be less than the critical value. The theoretical results show an exponential relationship between the force and the distance. Analytical expressions are developed for permanent magnets in the form of a point dipole, a tip of a magnetic force microscope, and a cylindrical magnet. In the latter case, the exponential relationship has been observed in numerous experiments but without previous interpretation.

  10. Relationship between morbidity and body mass index of mariners in the Japan Maritime Self-Defense Force Fleet Escort Force.

    PubMed

    Okamoto, Y; Miyazaki, N; Kurumagawa, H; Fujino, K; Mori, K; Shimizu, S; Ishikawa, K

    2001-08-01

    To establish a practical weight management program for mariners in the Japan Maritime Self-Defense Force (JMSDF) Fleet Escort Force, the relationship between morbidity and body mass index (BMI) was studied. To estimate morbidity, 10 medical problems were used as indices (hyperlipidemia, hyperuricemia, diabetes mellitus, lung disease, heart disease, upper gastrointestinal tract disease, hypertension, renal disease, liver disease, and anemia). A curvilinear relationship was found between morbidity and BMI, in which a BMI of 17.5 was associated with the lowest morbidity. This curvilinear pattern was more complex than a curve reported previously for Japanese civilians. Using the present curve and aiming for a BMI of 17.5 will help in the design and implementation of a practical management program for health promotion in the JMSDF. PMID:11515316

  11. The explosion of chiral many-body forces: How to deal with it?

    NASA Astrophysics Data System (ADS)

    Machleidt, R.

    2015-02-01

    During the past two decades, it has been demonstrated that chiral effective field theory represents a powerful tool to deal with nuclear forces in a systematic and model- independent way. Two-, three-, and four-nucleon forces have been derived up to next-to-next-to- next-to-leading order (N3LO) and (partially) applied in nuclear few- and many-body systems- with, in general, a good deal of success. But in spite of these achievements, we are still faced with some great challenges. Among them is the problem of a proper renormalization of the two- nucleon potential. Another issue are the subleading many-body forces, where the "explosion" of the number of terms with increasing order and the order-by-order convergence are reasons for concern. In this talk, I will mainly focus on the latter topic.

  12. A preliminary investigation of the dynamic force-calibration of a magnetic suspension and balance system

    NASA Technical Reports Server (NTRS)

    Goodyer, M. J.

    1985-01-01

    The aerodynamic forces and moments acting upon a magnetically suspended wind tunnel model are derived from calibrations of suspension electro magnet currents against known forces. As an alternative to the conventional calibration method of applying steady forces to the model, early experiences with dynamic calibration are outlined, that is a calibration obtained by oscillating a model in suspension and deriving a force/current relationship from its inertia force and the unsteady components of currents. Advantages of dynamic calibration are speed and simplicity. The two methods of calibration applied to one force component show good agreement.

  13. Optical response of magnetic fluorescent microspheres used for force spectroscopy in the evanescent field.

    PubMed

    Bijamov, Alex; Shubitidze, Fridon; Oliver, Piercen M; Vezenov, Dmitri V

    2010-07-20

    Force spectroscopy based on magnetic tweezers is a powerful technique for manipulating single biomolecules and studying their interactions. The resolution in magnetic probe displacement, however, needs to be commensurate with molecular sizes. To achieve the desirable sensitivity in tracking displacements of the magnetic probe, some recent approaches have combined magnetic tweezers with total internal reflection fluorescence microscopy. In this situation, a typical force probe is a polymer microsphere containing two types of optically active components: a pure absorber (magnetic nanoparticles for providing the pulling force) and a luminophore (semiconducting nanoparticles or organic dyes for fluorescent imaging). To assess the system's capability fully with regard to tracking the position of the force probe with subnanometer accuracy, we developed a body-of-revolution formulation of the method of auxiliary sources (BOR-MAS) to simulate the absorption, scattering, and fluorescence of microscopic spheres in an evanescent electromagnetic field. The theoretical formulation uses the axial symmetry of the system to reduce the dimensionality of the modeling problem and produces excellent agreement with the reported experimental data on forward scattering intensity. Using the BOR-MAS numerical model, we investigated the probe detection sensitivity for a high numerical aperture objective. The analysis of both backscattering and fluorescence observation modes shows that the total intensity of the bead image decays exponentially with the distance from the surface (or the length of a biomolecule). Our investigations demonstrate that the decay lengths of observable optical power are smaller than the penetration depth of the unperturbed excitation evanescent wave. In addition, our numerical modeling results illustrate that the expected sensitivity for the decay length changes with the angle of incidence, tracking the theoretical penetration depth for a two-media model, and is sensitive to the bead size. The BOR-MAS methodology developed in this work for near-field modeling of bead-tracking experiments fully describes the fundamental photonic response of microscopic BOR probes at the subwavelength level and can be used for future improvements in the design of these probes or in the setup of bead-tracking experiments. PMID:20486724

  14. Effect of three-body forces on response functions in infinite neutron matter

    E-print Network

    D. Davesne; J. W. Holt; A. Pastore; J. Navarro

    2014-11-12

    We study the impact of three-body forces on the response functions of cold neutron matter. These response functions are determined in the random phase approximation (RPA) from a residual interaction expressed in terms of Landau parameters. Special attention is paid to the non-central part, including all terms allowed by the relevant symmetries. Using Landau parameters derived from realistic nuclear two- and three-body forces grounded in chiral effective field theory, we find that the three-body term has a strong impact on the excited states of the system and in the static and long-wavelength limit of the response functions for which a new exact formula is established.

  15. Local stress and heat flux in atomistic systems involving three-body forces.

    PubMed

    Chen, Youping

    2006-02-01

    Local densities of fundamental physical quantities, including stress and heat flux fields, are formulated for atomistic systems involving three-body forces. The obtained formulas are calculable within an atomistic simulation, in consistent with the conservation equations of thermodynamics of continuum, and can be applied to systems with general two- and three-body interaction forces. It is hoped that this work may correct some misuse of inappropriate formulas of stress and heat flux in the literature, may clarify the definition of site energy of many-body potentials, and may serve as an analytical link between an atomistic model and a continuum theory. Physical meanings of the obtained formulas, their relation with virial theorem and heat theorem, and the applicability are discussed. PMID:16468857

  16. Formation of magnetic discontinuities through superposition of force-free magnetic fields: Periodic boundaries

    SciTech Connect

    Kumar, Dinesh; Bhattacharyya, R.; Smolarkiewicz, P. K.

    2013-11-15

    In ideal magnetohydrodynamics characterized by an infinite electrical conductivity, the magnetic flux across an arbitrary fluid surface is conserved in time. The magnetofluid then can be partitioned into contiguous subvolumes of fluid, each of which entraps its own subsystem of magnetic flux. During dynamical evolution of the magnetofluid, these subvolumes press into each other; and in the process, two such subvolumes may come into direct contact while ejecting a third interstitial subvolume. Depending on the orientations of magnetic fields of the two interacting subvolumes, the magnetic field at the common surface of interaction may become discontinuous and a current sheet is formed there. This process of current sheet formation and their subsequent decay is believed to be a plausible mechanism for coronal heating and may also be responsible for various eruptive phenomena at the solar corona. In this work, we explore this theoretical concept through numerical simulations of a viscous, incompressible magnetofluid characterized by infinite electrical conductivity. In particular, we show that if the initial magnetic field is prescribed by superposition of two linear force-free fields with different torsion coefficients, then formation of current sheets are numerically realizable in the neighborhood of magnetic nulls.

  17. The magnetic resonance force microscope: A new microscopic probe of magnetic materials

    SciTech Connect

    Hammel, P.C.; Zhang, Z.; Midzor, M.; Roukes, M.L.; Wigen, P.E.; Childress, J.R.

    1997-08-06

    The magnetic resonance force microscope (MRFM) marries the techniques of magnetic resonance imaging (MRI) and atomic force microscopy (AFM), to produce a three-dimensional imaging instrument with high, potentially atomic-scale, resolution. The principle of the MRFM has been successfully demonstrated in numerous experiments. By virtue of its unique capabilities the MRFM shows promise to make important contributions in fields ranging from three-dimensional materials characterization to bio-molecular structure determination. Here the authors focus on its application to the characterization and study of layered magnetic materials; the ability to illuminate the properties of buried interfaces in such materials is a particularly important goal. While sensitivity and spatial resolution are currently still far from their theoretical limits, they are nonetheless comparable to or superior to that achievable in conventional MRI. Further improvement of the MRFM will involve operation at lower temperature, application of larger field gradients, introduction of advanced mechanical resonators and improved reduction of the spurious coupling when the magnet is on the resonator.

  18. Revealing bending and force in a soft body through a plant root inspired approach

    PubMed Central

    Lucarotti, Chiara; Totaro, Massimo; Sadeghi, Ali; Mazzolai, Barbara; Beccai, Lucia

    2015-01-01

    An emerging challenge in soft robotics research is to reveal mechanical solicitations in a soft body. Nature provides amazing clues to develop unconventional components that are capable of compliant interactions with the environment and living beings, avoiding mechanical and algorithmic complexity of robotic design. We inspire from plant-root mechanoperception and develop a strategy able to reveal bending and applied force in a soft body with only two sensing elements of the same kind, and a null computational effort. The stretching processes that lead to opposite tissue deformations on the two sides of the root wall are emulated with two tactile sensing elements, made of soft and stretchable materials, which conform to reversible changes in the shape of the body they are built in and follow its deformations. Comparing the two sensory responses, we can discriminate the concave and the convex side of the bent body. Hence, we propose a new strategy to reveal in a soft body the maximum bending angle (or the maximum deflection) and the externally applied force according to the body's mechanical configuration. PMID:25739743

  19. Revealing bending and force in a soft body through a plant root inspired approach

    NASA Astrophysics Data System (ADS)

    Lucarotti, Chiara; Totaro, Massimo; Sadeghi, Ali; Mazzolai, Barbara; Beccai, Lucia

    2015-03-01

    An emerging challenge in soft robotics research is to reveal mechanical solicitations in a soft body. Nature provides amazing clues to develop unconventional components that are capable of compliant interactions with the environment and living beings, avoiding mechanical and algorithmic complexity of robotic design. We inspire from plant-root mechanoperception and develop a strategy able to reveal bending and applied force in a soft body with only two sensing elements of the same kind, and a null computational effort. The stretching processes that lead to opposite tissue deformations on the two sides of the root wall are emulated with two tactile sensing elements, made of soft and stretchable materials, which conform to reversible changes in the shape of the body they are built in and follow its deformations. Comparing the two sensory responses, we can discriminate the concave and the convex side of the bent body. Hence, we propose a new strategy to reveal in a soft body the maximum bending angle (or the maximum deflection) and the externally applied force according to the body's mechanical configuration.

  20. Specialized probes with nanowhisker structures for high resolution magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Zhukov, M. V.; Belousov, K. I.; Mozharov, A. M.; Mukhin, I. S.; Golubok, A. O.

    2015-11-01

    Creation and study of specialized nanowhisker probes with magnetic coating are performed for high-precision imaging of various objects by means of atomic force and magnetic force microscopy. Thin layers of Ni and Co are deposited on the surface of nanowhisker structures to perform visualization of magnetic fields on the sample surface, in particular, structure of pits on a hard disk drive (HDD). It is revealed that probes with nanowhisker structures covered with magnetic coating due to their high aspect ratio demonstrate a higher spatial resolution and contrast of magnetic fields visualization in comparison with standard magnetic probes.

  1. LA-UR-97-40 Magnetic Resonance Force Microscopy With a

    E-print Network

    Hammel, P. Chris

    sin(2fmt)^z. The total magnetic field at the sample is B = [Bbar + B0 + Bm]^z. Here, we neglect which provides a ramped bias field B0^z; and a modulation coil [12] which produces a field Bm(t) = BmLA-UR-97-40 Magnetic Resonance Force Microscopy With a Ferromagnetic Tip Mounted on the Force

  2. The Effect of Field Representation on Student Responses to Magnetic Force Questions

    E-print Network

    Heckler, Andrew F.

    particle and report three findings from a series of tests administered to introductory physics students, first studied by Maloney, that a magnetic pole exerts a force on a charged particle, regardless of itsThe Effect of Field Representation on Student Responses to Magnetic Force Questions Thomas M

  3. Force production mechanisms of a tangential jet on bodies at high alpha

    NASA Technical Reports Server (NTRS)

    Font, G. I.

    1992-01-01

    This work explores the mechanisms by which tangential slot blowing creates forces on a body at a high angle of attack. The study is conducted numerically by solving the three-dimensional, compressible-flow Navier-Stokes equations. A tangent-ogive cylinder configuration is used with the blowing slot located both on the nose and on the cylindrical part of the body. The angle of attack used is 30 deg., the Mach no. is 0.2 and the Reynolds no., based on diameter, is 52,000. Several conclusions were made concerning the physical mechanisms by which the jet interacts with the ambient flowfield to produce a side force: (1) A centrifugal force component is created at the wall due to the momentum of the jet being forced to follow the curvature of the surface. (2) A large amount of vorticity is added to the flowfield by the jet. In the region of the slot, the vorticity has the effect of inducing circulation around the body. Downstream of the slot, the vorticity alters the strength of the nose vortices. (3) The position of the nose vortices can be altered to the jet changing the location of separation. And (4), the jet has the ability to excite unstable behavior producing a global change in the character of the flow.

  4. Benchmarking numerical predictions with force and moment measurements on slender, supercavitating bodies

    SciTech Connect

    Hailey, C.E.; Clark, E.L.; Cole, J.K.

    1991-01-01

    High-speed water-entry is a very complex, dynamic process. As a first attempt at modeling the process, a numerical solution was developed at Sandia National Laboratories for predicting the forces and moments acting on a body with a steady supercavity, that is, a cavity which extends beyond the base of the body. The solution is limited to supercavities on slender, axisymmetric bodies at small angles of attack. Limited data were available with which to benchmark the axial force predictions at zero angle of attack. Even less data were available with which to benchmark the pitching moment and normal force predictions at nonzero angles of attack. A water tunnel test was conducted to obtain force and moment data on a slender shape. This test produced limited data because of waterproofing problems with the balance. A new balance was designed and a second water tunnel test was conducted at Tracor Hydronautics, Inc. This paper describes the numerical solution, the experimental equipment and test procedures, and the results of the second test. 8 refs., 11 figs.

  5. Application of superconductivity for magnetic force control in medical and industrial fields

    NASA Astrophysics Data System (ADS)

    Nishijima, S.

    2008-09-01

    The magnetic force control technique has expanded the applied field with developing a superconductivity because a high magnetic field and a high magnetic field gradient can be produced using the superconducting magnet. The magnetic force control technique has been applied to industrial fields such as recycling of abrasives, removing ferromagnetic particles from powdered products and purifying waste water. The technique is also applied to the drug delivery system as the medical application. Open gradient of magnetic separation was used for the recycling of the abrasives in wasted slurry from solar battery factory. For the removing the ferromagnetic particles from powdered products the magnetic filters were designed not to be blocked with the aggregated powder. In the water purification system, the superconducting high gradient magnetic separation was employed. For the magnetic drug delivery system the superconducting bulk magnet was used to navigate the nanometer-sized ferromagnetic particles in the blood vessel.

  6. Flow and Force Equations for a Body Revolving in a Fluid

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1930-01-01

    Part I gives a general method for finding the steady-flow velocity relative to a body in plane curvilinear motion, whence the pressure is found by Bernoulli's energy principle. Integration of the pressure supplies basic formulas for the zonal forces and moments on the revolving body. Part II, applying this steady-flow method, finds the velocity and pressure at all points of the flow inside and outside an ellipsoid and some of its limiting forms, and graphs those quantities for the latter forms. Part III finds the pressure, and thence the zonal force and moment, on hulls in plane curvilinear flight. Part IV derives general equations for the resultant fluid forces and moments on trisymmetrical bodies moving through a perfect fluid, and in some cases compares the moment values with those found for bodies moving in air. Part V furnishes ready formulas for potential coefficients and inertia coefficients for an ellipsoid and its limiting forms. Thence are derived tables giving numerical values of those coefficients for a comprehensive range of shapes.

  7. Development of a Force Measurement Device for Lower-Body Muscular Strength Measuring of Skaters

    NASA Astrophysics Data System (ADS)

    Kim, Dong Ki; Lee, Jeong Tae

    This paper presents a force measurement system that can measure a lower-body muscular strength of skaters. The precise measurement and analysis of the left and right lower-body strength of skaters is necessary, because a left/right lower-body strength balance is helpful to improve the athletes' performance and to protect them from injury. The system is constructed with a skate sliding board, a couple of sensor-units with load cell, indicator and control box, guard, force pad, and support bracket. The developed force measurement system is calibrated by the calibration setup, and the uncertainty of the force sensing unit on the left is within 0.087% and the uncertainty of the force sensing unit on the right is within 0.109%. In order to check the feasibility of the developed measurement device, a kinematic analysis is conducted with skater. As a result, the subject shows the deviation of left and right of 12.1 N with respect to average strength and 39.1 N with respect to the maximum strength. This evaluation results are reliable enough to make it possible to measure a lower-body muscular strength of skaters. The use of this measurement system will be expected to correct the posture of skaters and record the sports dynamics data for each athlete. It is believed that through the development of this equipment, skaters in elementary, middle, high schools, colleges, and the professional level have the systematic training to compete with world-class skaters.

  8. Magnetic levitation force measurement on high [Tc] superconducting ceramic/polymer composites

    SciTech Connect

    Unsworth, J.; Du, Jia; Crosby, B.J. ); Macfarlane, J.C. )

    1993-01-01

    An experimental study of magnetic levitation force for 0--3 and 3--3 superconducting ceramic/polymer composites is presented. A simple, inexpensive force versus distance measurement technique is described. The measurements of force against distance or magnetic field show strong hysteretic behavior, which is similar to the sintered superconductor ceramics and is consistent with the hysteresis in magnetization of superconductor. The volume fraction dependence and sample thickness dependence of the levitation forces are also studied for 0--3 composites. Results suggest that the new composite materials are most suitable for levitation applications.

  9. Axial force imparted by a current-free magnetically expanding plasma

    SciTech Connect

    Takahashi, Kazunori; Lafleur, Trevor; Charles, Christine; Alexander, Peter; Boswell, Rod W.

    2012-08-15

    The axial force imparted from a magnetically expanding, current-free, radiofrequency plasma is directly measured. For an argon gas flow rate of 25 sccm and an effective rf input power of {approx}800W, a maximum force of {approx}6mN is obtained; {approx}3mN of which is transmitted via the expanding magnetic field. The measured forces are reasonably compared with a simple fluid model associated with the measured electron pressure. The model suggests that the total force is the sum of an electron pressure inside the source and a Lorentz force due to the electron diamagnetic drift current and the applied radial magnetic field. It is shown that the Lorentz force is greatest near the magnetic nozzle surface where the radial pressure gradient is largest.

  10. A short model excitation of an asymmetric force free superconducting transmission line magnet

    SciTech Connect

    Wake, M.; Sato, H.; Carcagno, R.; Foster, W.; Hays, S.; Kashikhin, V.; Oleck, A.; Piekarz, H.; Rabehl, R,; /Fermilab

    2005-09-01

    A short model of asymmetric force free magnet with single beam aperture was tested at Fermilab together with the excitation test of VLHC transmission line magnet. The design concept of asymmetric force free superconducting magnet was verified by the test. The testing reached up to 104 kA current and no indication of force imbalance was observed. Since the model magnet length was only 10cm, A 0.75m model was constructed and tested at KEK with low current to ensure the validity of the design. The cool down and the excitation at KEK were also successful finding very small thermal contraction of the conductor and reasonable field homogeneity.

  11. On the Inertial Force Experienced by a Solid Body Undergoing Rotation about Two Axes

    SciTech Connect

    Christov, I. C.; Christov, C. I.

    2009-10-29

    The theory of rigid body motion is used to derive the governing equations, in terms of the Eulerian angles, of a top rotating about two axes. Then, a formula for the 'lifting' component of the net inertial force (as function of the angle of inclination, the top's two angular velocities and its moments of inertia) is derived for a particular motion termed constrained nutation. In a distinguished limit, the critical value of the angle of inclination, i.e., the value for which the vertical component of the net inertial force acting on the top overcomes the weight of the rotating system, is calculated.

  12. Nuclear pairing from bare interaction: Two and three-body chiral forces

    SciTech Connect

    Finelli, Paolo

    2012-10-20

    In a recent paper the {sup 1}S{sub 0} pairing gap in isospin-symmetric nuclear matter and finite nuclei has been investigated starting from the chiral nucleon-nucleon potential at the N{sup 3}LO order in the two-body sector and the N{sup 2}LO order in the three-body sector. To include realistic nuclear forces in RHB (Relativistic Hartree Bolgoliubov) calculations we relied on a separable representation of the pairing interaction. In this paper we would like to show recent results concerning isotonic chains with N= 28,50,82.

  13. Preliminary investigation of force-reduced superconducting magnet configurations for advanced technology applications

    SciTech Connect

    Bouillard, J.X.

    1992-12-01

    The feasibility of new high-field low specific weight superconducting magnet designs using force-free fields is being explored analytically and numerically. This report attempts to assess the technical viability of force-free field concepts to produce high-field, low specific weight and large bore volume magnets, which could promote the use of high temperature superconductors. Several force-free/force-reduced magnet configurations are first reviewed, then discussed and assessed. Force-free magnetic fields, fields for which the current flows parallel to the field, have well-known mathematical solutions extending upon infinite domains. These solutions, however, are no longer force-free everywhere for finite geometries. In this preliminary study, force-free solutions such as the Lundquist solutions truncated to a size where the internal field of the coil matches an externally cylindrical magnetic field (also called a Lundquist coil) are numerically modeled and explored. Significant force-reduction for such coils was calculated, which may have some importance for the design of lighter toroidal magnets used in thermonuclear fusion power generation, superconducting magnetic energy storage (SMES), and mobile MHD power generation and propulsion.

  14. GravitoMagnetic force in modified Newtonian dynamics

    SciTech Connect

    Exirifard, Qasem

    2013-08-01

    We introduce the Gauge Vector-Tensor (GVT) theory by extending the AQUAL's approach to the GravitoElectroMagnetism (GEM) approximation of gravity. GVT is a generally covariant theory of gravity composed of a pseudo Riemannian metric and two U(1) gauge connections that reproduces MOND in the limit of very weak gravitational fields while remains consistent with the Einstein-Hilbert gravity in the limit of strong and Newtonian gravitational fields. GVT also provides a simple framework to study the GEM approximation to gravity. We illustrate that the gravitomagnetic force at the edge of a galaxy can be in accord with either GVT or ?CDM but not both. We also study the physics of the GVT theory around the gravitational saddle point of the Sun and Jupiter system. We notice that the conclusive refusal of the GVT theory demands measuring either both of the gravitoelectric and gravitomagnetic fields inside the Sun-Jupiter MOND window, or the gravitoelectric field inside two different solar GVT MOND windows. The GVT theory, however, will be favored by observing an anomaly in the gravitoelectric field inside a single MOND window.

  15. Does Using a Visual-Representation Tool Foster Students' Ability to Identify Forces and Construct Free-Body Diagrams?

    ERIC Educational Resources Information Center

    Savinainen, Antti; Makynen, Asko; Nieminen, Pasi; Viiri, Jouni

    2013-01-01

    Earlier research has shown that after physics instruction, many students have difficulties with the force concept, and with constructing free-body diagrams (FBDs). It has been suggested that treating forces as interactions could help students to identify forces as well as to construct the correct FBDs. While there is evidence that identifying…

  16. Evaporation From Heated Water Bodies: Predicting Combined Forced Plus Free Convection

    NASA Astrophysics Data System (ADS)

    Adams, E. Eric; Cosler, Douglas J.; Helfrich, Karl R.

    1990-03-01

    Recent measurements at the National Geothermal Test Facility at East Mesa, California, and the Savannah River Plant, South Carolina, have spurred a renewed look at evaporation from heated water bodies. Theoretical analyses are provided for each of four evaporation regimes that could be experienced at heated ponds, ranging from free convective layers to forced convective layers. Differences among regimes are highlighted by calculations appropriate for the Savannah River site where water temperatures reach 70°C and underscore the difficulty in finding a single evaporation equation to adequately cover the entire range. Consequently, a new equation is developed which combines free and forced convection in a different manner from previous equations: evaporation is computed as the square root of the sum of the squares of the respective components. The new equation and several existing equations are compared with evaporation measured at water bodies at the Savannah River and the East Mesa sites.

  17. SELF-GRAVITATING BODY WITH AN INTERNAL MAGNETIC FIELD. I. NEW ANALYTICAL EQUILIBRIA

    SciTech Connect

    Aly, J.-J.; Amari, T.

    2012-05-01

    We construct exact analytical solutions of the equations describing the equilibrium of a self-gravitating magnetized fluid body, possibly rigidly rotating, by superposing two solutions of finite energy defined in the whole space, one describing a non-magnetized gravitating equilibrium (ST1) and the other describing a magnetized non-gravitating equilibrium (ST2). A large number of ST1s can be found in the literature and directly used for our constructions, and we thus concentrate on ST2s, which are difficult to obtain. We derive some of their general properties and exhibit two explicit classes of axisymmetric 'elementary' such equilibria. The first one is extracted from the stellar models proposed by Prendergast and by Kutvitskii and Solov'ev, respectively. The second one is constructed by using Palumbo's theory of isodynamic equilibria, for which the magnetic pressure is constant on each flux surface. Both types of ST2s have their magnetic field confined within a bounded region, respectively, of spherical and toroidal shapes. A much more general ST2 can be obtained by juxtaposing n+q elementary ST2s, with n of the first type and q of the second type, in such a way that the magnetic regions do not pairwise overlap. The specific equilibria we obtain by superposition thus have no external field extending to infinity, and may be three dimensional (3D), which invalidates a recent nonexistence conjecture. Moreover, they may be arranged to contain force-free regions. Our superposition method can be considered as a 3D generalization of the axisymmetric splitting method previously developed by Kutvitskii and Solov'ev.

  18. Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy

    E-print Network

    Hammel, P. Chris

    Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy B. J. Suh, P resonance FMR 2 has been demonstrated. Each of these has advantages for micro- scopic imaging in magnetic the spatial origin of a particular contribu- tion to the FMR signal. Magnetic resonance imaging employs

  19. Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump.

    PubMed

    Pai, C N; Shinshi, T; Shimokohbe, A

    2010-01-01

    Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response. PMID:20839658

  20. Transient Body Force Effects on the Dryout and Rewet of a Heated Capillary Structure.

    NASA Astrophysics Data System (ADS)

    Reagan, Michael Kevin

    1994-01-01

    A transient, one-dimensional numerical code was developed to model the liquid flow in a non-uniformly heated, axial square groove. The groove was subjected to transient body forces up to approximately 0.51 m/s^2 . Axial variation in meniscus levels, shear stress and heat transfer between the groove wall and the liquid, axial conduction through the liquid, evaporation and body forces were accounted for in the model. Dryout and rewet of the groove was allowed; the front location was determined using conservation of mass and linear extrapolation. A physical experiment was performed with a stainless steel plate into which eight square grooves were machined. Ethanol was used as the working liquid. One end of the plate was tilted relative to the other end and this tilt was varied with time, thereby providing the transient body force. The depth of the ethanol in the groove, and the dryout and rewet front locations, were experimentally measured. Within the uncertainty of the measurements, the numerical results from the code predicted the correct movement of liquid within the groove structure and also the correct position of the dryout and rewet fronts.

  1. Transient body force effects on the dryout and rewet of a heated capillary structure

    NASA Astrophysics Data System (ADS)

    Reagan, Michael K.

    1994-04-01

    A transient, one-dimensional numerical code was developed to model the liquid flow in a non-uniformly heated, axial square groove. The groove was subjected to transient body forces up to approximately 0.51 m/s sq. Axial variation in meniscus levels, shear stress and heat transfer between the groove wall and the liquid, axial conduction through the liquid, evaporation and body forces were accounted for in the model. Dryout and rewet of the groove were allowed; the front location was determined using conservation of mass and linear extrapolation. A physical experiment was performed with a stainless steel plate into which eight square grooves were machined. Ethanol was used as the working liquid. One end of the plate was tilted relative to the other end and this tilt was varied with time, thereby providing the transient body force. The depth of the ethanol in the groove, and the dryout and rewet front locations, were experimentally measured. Within the uncertainty of the measurements, the numerical results from the code predicted the correct movement of liquid within the groove structure and also the correct position of the dryout and rewet fronts.

  2. The c-term of the TM 3-body Force: to be or not to be

    E-print Network

    H. Kamada; D. Hueber; A. Nogga

    1999-04-22

    In Faddeev calculations of ^3Hwe study the dependence of the binding on the three nucleon force. We adopt the 2 pi -exchange Tucson-Melbourne three-nucleon force and investigate phenomenologically the dependence on the strength of the individual three-body force operators (a -, b -, c - and d -terms). While the a -term provides a tiny contribution the b - and d -terms provides a tiny contribution the b - and d -terms are important to gain the experimental binding energy. We find two solutions for the c -term, one around the value used in the Tucson-Melbourne model and a new one close to zero, which supports the recentrecommendation of chiral perturbation theory that the short-range c -term should be dropped.

  3. A new method for correcting a force transmission error due to magnetic effects in a magnetic levitation densimeter

    NASA Astrophysics Data System (ADS)

    Kano, Yuya; Kayukawa, Yohei; Fujii, Kenichi; Sato, Haruki

    2007-03-01

    The magnetic levitation densimeter is one of the most accurate methods to measure fluid density in a wide range of temperature and pressure. For the existing commercially available densimeter, a relative measurement uncertainty of density is about 0.03%. One of the largest parts of the uncertainty is caused by magnetism of materials around the magnetic coupling in the densimeter, such as a sample fluid under test and a pressure cell. These magnetic effects cause a force transmission error in the magnetic coupling, which is composed of a permanent magnet in the sample fluid and an electromagnet suspended from an electronic balance placed under ambient temperature and pressure. For the existing densimeter, the force transmission error induces an uncertainty of around 0.01% in density. In the present study, the force transmission error is quantitatively investigated by the finite element method (FEM). Reliability of the FEM analysis was confirmed through a comparison with the experimental data measured by using the densimeter established at the National Metrology Institute of Japan (NMIJ). It is found from the FEM results that the density measurement error caused by the force transmission error can be reduced by controlling the permanent magnet at the same vertical position in every measurement state. In addition, the force transmission error linearly changes with the magnetic force acting on the electromagnet when the vertical position of the permanent magnet is constant. On the basis of these FEM results, the authors propose a correction method for the force transmission error by using a dual-sinker type of densimeter.

  4. Effects of three-nucleon forces and two-body currents on Gamow-Teller strengths.

    PubMed

    Ekström, A; Jansen, G R; Wendt, K A; Hagen, G; Papenbrock, T; Bacca, S; Carlsson, B; Gazit, D

    2014-12-31

    We optimize chiral interactions at next-to-next-to leading order to observables in two- and three-nucleon systems and compute Gamow-Teller transitions in 14C and (22,24)O using consistent two-body currents. We compute spectra of the daughter nuclei 14N and (22,24)F via an isospin-breaking coupled-cluster technique, with several predictions. The two-body currents reduce the Ikeda sum rule, corresponding to a quenching factor q2?0.84-0.92 of the axial-vector coupling. The half-life of 14C depends on the energy of the first excited 1+ state, the three-nucleon force, and the two-body current. PMID:25615316

  5. Magnetic Levitation Force Measurement System at Any Low Temperatures From 20 K To 300 K

    NASA Astrophysics Data System (ADS)

    Celik, Sukru; Guner, S. Baris; Coskun, Elvan

    2015-03-01

    Most of the magnetic levitation force measurements in previous studies were performed at liquid nitrogen temperatures. For the levitation force of MgB2 and iron based superconducting samples, magnetic levitation force measurement system is needed. In this study, magnetic levitation force measurement system was designed. In this system, beside vertical force versus vertical motion, lateral and vertical force versus lateral motion measurements, the vertical force versus temperature at the fixed distance between permanent magnet PM - superconducting sample SS and the vertical force versus time measurements were performed at any temperatures from 20 K to 300 K. Thanks to these measurements, the temperature dependence, time dependence, and the distance (magnetic field) and temperature dependences of SS can be investigated. On the other hand, the magnetic stiffness MS measurements can be performed in this system. Using the measurement of MS at different temperature in the range, MS dependence on temperature can be investigated. These measurements at any temperatures in the range help to the superconductivity properties to be characterized. This work was supported by TUBTAK-the Scientific and technological research council of Turkey under project of MFAG - 110T622. This system was applied to the Turkish patent institute with the Application Number of 2013/13638 on 22/11/2013.

  6. Concentric Magnetic Structures for Magnetophoretic Bead Collection, Cell Trapping and Analysis of Cell Morphological Changes Caused by Local Magnetic Forces

    PubMed Central

    Huang, Chen-Yu; Wei, Zung-Hang

    2015-01-01

    Concentric magnetic structures (ring and square) with domain wall (DW) pinning geometry are designed for biological manipulation. Magnetic beads collection was firstly demonstrated to analyse the local magnetic field generated by DWs and the effective regions to capture magnetic targets of size 1 ?m. Primary mouse embryonic fibroblasts (MEFs) are magnetically labeled by internalizing poly (styrene sulfonic acid) stabilized magnetic nanoparticles (PSS-MNPs) and then are selectively trapped by head-to-tail DWs (HH DWs) or tail-to-tail DWs (TT DWs) to be arranged into linear shape or cross shape. The morphologies and the nuclear geometry of the cells growing on two kinds of concentric magnetic structures are shown to be distinctive. The intracellular magnetic forces generated by the local magnetic field of DWs are found to influence the behaviour of cells. PMID:26270332

  7. Investigation of Body Force Effects on Flow Boiling Critical Heat Flux

    NASA Technical Reports Server (NTRS)

    Zhang, Hui; Mudawar, Issam; Hasan, Mohammad M.

    2002-01-01

    The bubble coalescence and interfacial instabilities that are important to modeling critical heat flux (CHF) in reduced-gravity systems can be sensitive to even minute body forces. Understanding these complex phenomena is vital to the design and safe implementation of two-phase thermal management loops proposed for space and planetary-based thermal systems. While reduced gravity conditions cannot be accurately simulated in 1g ground-based experiments, such experiments can help isolate the effects of the various forces (body force, surface tension force and inertia) which influence flow boiling CHF. In this project, the effects of the component of body force perpendicular to a heated wall were examined by conducting 1g flow boiling experiments at different orientations. FC-72 liquid was boiled along one wall of a transparent rectangular flow channel that permitted photographic study of the vapor-liquid interface at conditions approaching CHF. High-speed video imaging was employed to capture dominant CHF mechanisms. Six different CHF regimes were identified: Wavy Vapor Layer, Pool Boiling, Stratification, Vapor Counterflow, Vapor Stagnation, and Separated Concurrent Vapor Flow. CHF showed great sensitivity to orientation for flow velocities below 0.2 m/s, where very small CHF values where measured, especially with downflow and downward-facing heated wall orientations. High flow velocities dampened the effects of orientation considerably. Figure I shows representative images for the different CHF regimes. The Wavy Vapor Layer regime was dominant for all high velocities and most orientations, while all other regimes were encountered at low velocities, in the downflow and/or downward-facing heated wall orientations. The Interfacial Lift-off model was modified to predict the effects of orientation on CHF for the dominant Wavy Vapor Layer regime. The photographic study captured a fairly continuous wavy vapor layer travelling along the heated wall while permitting liquid contact only in wetting fronts, located in the troughs of the interfacial waves. CHF commenced when wetting fronts near the outlet were lifted off the wall. The Interfacial Lift-off model is shown to be an effective tool for predicting the effects of body force on CHF at high velocities.

  8. Relations Between Lower Body Isometric Muscle Force Characteristics and Start Performance in Elite Male Sprint Swimmers

    PubMed Central

    Bereti?, Igor; ?urovi?, Marko; Oki?i?, Tomislav; DOPSAJ, Milivoj

    2013-01-01

    The aim of the present study was twofold. The first aim was to examine the influence of absolute and relative lower body muscle force on kinematic component which determine the start performance. The second aim was to create multiregressional model which could use as a tool for swimming coaches with the purpose to start performance control and improvement. Twenty seven high-level trained male competitive swimmers all members of the Serbian National Youth and Senior Swimming Team (Age = 21.1 ± 4.3 yrs., Height = 1. 89 ± 0.10 m, Weight = 81.6 ± 8.4 kg, 50m freestyle - long course = 24.36 ± 0.86 s) performed two trials of standing leg extensors isometric muscle force testing and three swimming start trials corresponding to 10m distance. The average start time significantly correlated with variables of leg extensors maximum voluntary force (Fmax, r = -0.559, p = 0.002), leg extensors relative muscle voluntary force (Frel, r = -0.727, p < 0.001), leg extensors specific rate of force development (RFD50%, r = -0.338, p = 0.047) and leg extensors relative value of specific rate of force development (RFD50%rel, r = -0.402, p = 0.040). Regression equation for t10m prediction was defined by following variables: maximum voluntary isometric force of leg extensors muscles at absolute and relative level (Fmax and Frel), as well as a specific rate of force development of the same muscle groups (RFD50% and RFD50%rel) at absolute and relative level too with 74.4% of explained variance. Contractile abilities indicators of the leg extensors muscles included consideration: Fmax, RFD50%, Frel and RFD50%rel showed significant correlation with swimming start times on 10m. Additionally, the results suggest that swimmers, who possess greater isometric maximum force and specific rate of force development at absolute and relative levels, tend to be able to swim faster on initial 10m swim start perforamnce. Key Points In high-level male swimmers: Leg extensors maximum voluntary force, leg exten-sors relative value of maximum muscle voluntary force, leg extensors specific rate of force develop-ment and leg extensors relative value of specific rate of force development positively associated with the start time measured on 10m-mark. Time at 10m-mark was not associated with legs ex-tensors basic level of rate of force development at absolute and relative level. Obtained multi-regressional model is defined by variables which measure the development of maxi-mum voluntary isometric leg extensor muscle force on the absolute and relative level, as well as vari-ables which measure the development of specific explosive force of the same muscle group on abso-lute and relative level, this could use as a tool for swimming coaches to control the direction and ex-tent of development of a given force characteristics for providing conditions for start improvement in highly trained elite male sprint swimmers. PMID:24421722

  9. Nonlinear force-free modeling of the solar coronal magnetic field

    E-print Network

    T. Wiegelmann

    2008-01-18

    The coronal magnetic field is an important quantity because the magnetic field dominates the structure of the solar corona. Unfortunately direct measurements of coronal magnetic fields are usually not available. The photospheric magnetic field is measured routinely with vector magnetographs. These photospheric measurements are extrapolated into the solar corona. The extrapolated coronal magnetic field depends on assumptions regarding the coronal plasma, e.g. force-freeness. Force-free means that all non-magnetic forces like pressure gradients and gravity are neglected. This approach is well justified in the solar corona due to the low plasma beta. One has to take care, however, about ambiguities, noise and non-magnetic forces in the photosphere, where the magnetic field vector is measured. Here we review different numerical methods for a nonlinear force-free coronal magnetic field extrapolation: Grad-Rubin codes, upward integration method, MHD-relaxation, optimization and the boundary element approach. We briefly discuss the main features of the different methods and concentrate mainly on recently developed new codes.

  10. Task III: Development of an Effective Computational Methodology for Body Force Representation of High-speed Rotor 37

    NASA Technical Reports Server (NTRS)

    Tan, Choon-Sooi; Suder, Kenneth (Technical Monitor)

    2003-01-01

    A framework for an effective computational methodology for characterizing the stability and the impact of distortion in high-speed multi-stage compressor is being developed. The methodology consists of using a few isolated-blade row Navier-Stokes solutions for each blade row to construct a body force database. The purpose of the body force database is to replace each blade row in a multi-stage compressor by a body force distribution to produce same pressure rise and flow turning. To do this, each body force database is generated in such a way that it can respond to the changes in local flow conditions. Once the database is generated, no hrther Navier-Stokes computations are necessary. The process is repeated for every blade row in the multi-stage compressor. The body forces are then embedded as source terms in an Euler solver. The method is developed to have the capability to compute the performance in a flow that has radial as well as circumferential non-uniformity with a length scale larger than a blade pitch; thus it can potentially be used to characterize the stability of a compressor under design. It is these two latter features as well as the accompanying procedure to obtain the body force representation that distinguish the present methodology from the streamline curvature method. The overall computational procedures have been developed. A dimensional analysis was carried out to determine the local flow conditions for parameterizing the magnitudes of the local body force representation of blade rows. An Euler solver was modified to embed the body forces as source terms. The results from the dimensional analysis show that the body forces can be parameterized in terms of the two relative flow angles, the relative Mach number, and the Reynolds number. For flow in a high-speed transonic blade row, they can be parameterized in terms of the local relative Mach number alone.

  11. Magnetic levitation force of semi-infinite type-II superconductors

    SciTech Connect

    Coffey, M.W.

    1995-10-01

    The levitation force acting on a point magnetic dipole above a semi-infinite type-II superconductor in both the Meissner and mixed states is studied. A formalism is developed for axisymmetric problems using London theory. The magnetostatic interaction energy and corresponding force can be put into closed form for such problems for arbitrary height of the magnetic point source. The results for stray fields have ready application to magnetic-force microscopy (MFM) with point probes. The results are useful for a range of experiments including the low-temperature MFM imaging of vortices and decoration measurements. Special cases include earlier results and previous approximations are obviated.

  12. FORCE-FREENESS OF SOLAR MAGNETIC FIELDS IN THE PHOTOSPHERE Q1 Y.-J. Moon,1,2

    E-print Network

    FORCE-FREENESS OF SOLAR MAGNETIC FIELDS IN THE PHOTOSPHERE Q1 Y.-J. Moon,1,2 G. S. Choe,3 H. S. Yun It is widely believed that solar magnetic fields are force-free in the solar corona but not in the solar photo- sphere at all. In order to examine the force-freeness of active region magnetic fields

  13. Static Stern-Gerlach effect in magnetic force microscopy G. P. Berman,1

    E-print Network

    Hammel, P. Chris

    . The whole system is placed in a uniform external magnetic field, B0. We assume that B0 is large enough, k in the direction of B0 the positive z-direction in Fig. 1 . The magnetic field, B0, also induces a magnetic momentStatic Stern-Gerlach effect in magnetic force microscopy G. P. Berman,1 G. D. Doolen,1 P. C. Hammel

  14. Torsional resonance mode magnetic force microscopy: enabling higher lateral resolution magnetic imaging without topography-related effects.

    PubMed

    Kaidatzis, A; García-Martín, J M

    2013-04-26

    We present experimental work that reveals the benefits of performing magnetic force microscopy measurements employing the torsional resonance mode of cantilever oscillation. This approach provides two clear advantages: the ability of performing magnetic imaging without topography-related interference and the significant lateral resolution improvement (approximately 15%). We believe that this work demonstrates a significant improvement to a versatile magnetic imaging technique widely used in academia and in industry. PMID:23535607

  15. Study of ac-plane Magnetic Microstructure of Fe3GeTe2 Using Magnetic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Leon Brito, Neliza; Bauer, Eric D.; Ronning, Filip; Thompson, Joe D.; Movshovich, Roman

    2015-03-01

    In the quest to develop design principles governing high performance rare earth-free ferromagnets our group has focused on materials where electronic correlations and crystal environment lead to high magnetic anisotropy. The present study concentrates its efforts on one of these materials, the layered itinerant ferromagnet Fe3GeTe2, which has a high degree of magnetic anisotropy and an easy magnetization direction along the c-axis. Magnetic force microscopy was used to observe the ground state magnetic microstructure of the a-c plane, and its evolution in an external magnetic field along the b-axis. We built a ``surface magnetization loop'' based on the MFM data from -5 Tesla to +5 Tesla. We will discuss our results in view of the bulk magnetization data obtained with a superconducting quantum interference device magnetometer. Work at LANL was performed under the auspices of the U.S. DOE and supported by the LDRD program.

  16. Aerodynamic force generation, performance and control of body orientation during gliding in sugar gliders (Petaurus breviceps).

    PubMed

    Bishop, Kristin L

    2007-08-01

    Gliding has often been discussed in the literature as a possible precursor to powered flight in vertebrates, but few studies exist on the mechanics of gliding in living animals. In this study I analyzed the 3D kinematics of sugar gliders (Petaurus breviceps) during short glides in an enclosed space. Short segments of the glide were captured on video, and the positions of marked anatomical landmarks were used to compute linear distances and angles, as well as whole body velocities and accelerations. From the whole body accelerations I estimated the aerodynamic forces generated by the animals. I computed the correlations between movements of the limbs and body rotations to examine the control of orientation during flight. Finally, I compared these results to those of my earlier study on the similarly sized and distantly related southern flying squirrel (Glaucomys volans). The sugar gliders in this study accelerated downward slightly (1.0+/-0.5 m s(-2)), and also accelerated forward (2.1+/-0.6 m s(-2)) in all but one trial, indicating that the body weight was not fully supported by aerodynamic forces and that some of the lift produced forward acceleration rather than just balancing body weight. The gliders used high angles of attack (44.15+/-3.12 degrees ), far higher than the angles at which airplane wings would stall, yet generated higher lift coefficients (1.48+/-0.18) than would be expected for a stalled wing. Movements of the limbs were strongly correlated with body rotations, suggesting that sugar gliders make extensive use of limb movements to control their orientation during gliding flight. In addition, among individuals, different limb movements were associated with a given body rotation, suggesting that individual variation exists in the control of body rotations. Under similar conditions, flying squirrels generated higher lift coefficients and lower drag coefficients than sugar gliders, yet had only marginally shallower glides. Flying squirrels have a number of morphological specializations not shared by sugar gliders that may help to explain their greater lift generating performance. PMID:17644674

  17. Quantitative magnetic resonance (QMR) measurement of changes in body composition of neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The survival of low birth weight pigs in particular may depend on energy stores in the body. QMR (quantitative magnetic resonance) is a new approach to measuring total body fat, lean and water. These measurements are based on quantifying protons associated with lipid and water molecules in the body...

  18. Dual-body magnetic helical robot for drilling and cargo delivery in human blood vessels

    NASA Astrophysics Data System (ADS)

    Lee, Wonseo; Jeon, Seungmun; Nam, Jaekwang; Jang, Gunhee

    2015-05-01

    We propose a novel dual-body magnetic helical robot (DMHR) manipulated by a magnetic navigation system. The proposed DMHR can generate helical motions to navigate in human blood vessels and to drill blood clots by an external rotating magnetic field. It can also generate release motions which are relative rotational motions between dual-bodies to release the carrying cargos to a target region by controlling the magnitude of an external magnetic field. Constraint equations were derived to selectively manipulate helical and release motions by controlling external magnetic fields. The DMHR was prototyped and various experiments were conducted to demonstrate its motions and verify its manipulation methods.

  19. A Magnetic Resonance Force Microscopy Quantum Computer with Tellurium Donors in Silicon

    E-print Network

    G. P. Berman; G. D. Doolen; V. I. Tsifrinovich

    2000-03-18

    We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines the well-developed silicon technology with expected advances in MRFM.

  20. Magnetic Force Driven Nanogenerators as a Noncontact Energy Harvester and Sensor

    E-print Network

    Wang, Zhong L.

    Supporting Information ABSTRACT: Nanogenerator has been a very important energy harvesting technology throughMagnetic Force Driven Nanogenerators as a Noncontact Energy Harvester and Sensor Nuanyang Cui and Nanotechnology, Lanzhou University, Lanzhou 730000, China Beijing National Laboratory for Molecular Sciences

  1. Identification of rotordynamic forces in a flexible rotor system using magnetic bearings 

    E-print Network

    Zutavern, Zachary Scott

    2009-06-02

    Methods are presented for parameter identification of an annular gas seal on a flexiblerotor test rig. Dynamic loads are applied by magnetic bearings (MBs) that support the rotor. MB forces are measured using fiber-optic strain gauges...

  2. Linear stability of a circular Couette flow under a radial thermoelectric body force

    NASA Astrophysics Data System (ADS)

    Yoshikawa, H. N.; Meyer, A.; Crumeyrolle, O.; Mutabazi, I.

    2015-03-01

    The stability of the circular Couette flow of a dielectric fluid is analyzed by a linear perturbation theory. The fluid is confined between two concentric cylindrical electrodes of infinite length with only the inner one rotating. A temperature difference and an alternating electric tension are applied to the electrodes to produce a radial dielectrophoretic body force that can induce convection in the fluid. We examine the effects of superposition of this thermoelectric force with the centrifugal force including its thermal variation. The Earth's gravity is neglected to focus on the situations of a vanishing Grashof number such as microgravity conditions. Depending on the electric field strength and of the temperature difference, critical modes are either axisymmetric or nonaxisymmetric, occurring in either stationary or oscillatory states. An energetic analysis is performed to determine the dominant destabilizing mechanism. When the inner cylinder is hotter than the outer one, the circular Couette flow is destabilized by the centrifugal force for weak and moderate electric fields. The critical mode is steady axisymmetric, except for weak fields within a certain range of the Prandtl number and of the radius ratio of the cylinders, where the mode is oscillatory and axisymmetric. The frequency of this oscillatory mode is correlated with a Brunt-Väisälä frequency due to the stratification of both the density and the electric permittivity of the fluid. Under strong electric fields, the destabilization by the dielectrophoretic force is dominant, leading to oscillatory nonaxisymmetric critical modes with a frequency scaled by the frequency of the inner-cylinder rotation. When the outer cylinder is hotter than the inner one, the instability is again driven by the centrifugal force. The critical mode is axisymmetric and either steady under weak electric fields or oscillatory under strong electric fields. The frequency of the oscillatory mode is also correlated with the Brunt-Väisälä frequency.

  3. Spin-selective Imaging by Magnetic Exchange Force Microscopy Using Ferromagnetic Resonance.

    PubMed

    Sugawara, Yasuhiro; Arima, Eiji; Naitoh, Yoshitaka; Li, Yan Jun

    2014-11-01

    Techniques to analyze the surface of magnetic memory devices with high spatial resolution are very important to develop today's information technology. The magnetic exchange force is an interaction between spins and is very important for analyzing magnetic properties. Magnetic exchange force microscopy (MExFM), which can detect the magnetic exchange force between the magnetic tip and the magnetic surface, has achieved the atomic-resolution imaging of the spin state on anti-ferromagnetic surface of NiO(001) [1]. In MExFM, however, the separation between a structure and a magnetic state on the surface has not been performed.Here, we propose a new MExFM using ferromagnetic resonance to separate the magnetic and non-magnetic tip-sample interaction. In this method, magnetic tip apex is irradiated by the frequency-modulated microwave with the frequency of ferromagnetic resonance. The magnetization of magnetic tip apex is modulated from on resonance to off resonance. Tip-sample interaction is measured with frequency modulation method. Magnetic images are obtained by detecting the modulation component of the frequency shift of the oscillating cantilever using a lock-in amplifier. Topographic images are obtained by the feedback signal for the constant tip-sample interaction. As a magnetic tip, magnetic cantilever tip coated with FePt with a high coercivity was used to detect the magnetic exchange force without an external magnetic field [2]. We performed imaging on antiferromagnetic material NiO(001) surface (Fig. 1(a)) by MExFM using ferromagnetic resonance. We obtained spin selective image in atomic resolution (Fig. 1(b)). This is the first demonstration of magnetization modulation of the magnetic tip apex using ferromagnetic resonance as well as the separation of the magnetic and non-magnetic tip-sample interaction in MExFM.jmicro;63/suppl_1/i11-a/DFU053F1F1DFU053F1Fig. 1.(a) Structure of NiO(001) surface and (b) its image (phase) obtained with MExFM using ferromagnetic resonance. (4 nm x 4 nm). PMID:25359800

  4. Spin-dependent two-body interactions from gravitational self-force computations

    E-print Network

    Donato Bini; Thibault Damour; Andrea Geralico

    2015-10-21

    We analytically compute, through the eight-and-a-half post-Newtonian order and the fourth-order in spin, the gravitational self-force correction to Detweiler's gauge invariant redshift function for a small mass in circular orbit around a Kerr black hole. Using the first law of mechanics for black hole binaries with spin [L.~Blanchet, A.~Buonanno and A.~Le Tiec, Phys.\\ Rev.\\ D {\\bf 87}, 024030 (2013)] we transcribe our results into a knowledge of various spin-dependent couplings, as encoded within the spinning effective-one-body model of T.~Damour and A.~Nagar [Phys.\\ Rev.\\ D {\\bf 90}, 044018 (2014)]. We also compare our analytical results to the (corrected) numerical self-force results of A.~G.~Shah, J.~L.~Friedman and T.~S.~Keidl [Phys.\\ Rev.\\ D {\\bf 86}, 084059 (2012)], from which we show how to directly extract physically relevant spin-dependent couplings.

  5. Constraint Force Equation Methodology for Modeling Multi-Body Stage Separation Dynamics

    NASA Technical Reports Server (NTRS)

    Toniolo, Matthew D.; Tartabini, Paul V.; Pamadi, Bandu N.; Hotchko, Nathaniel

    2008-01-01

    This paper discusses a generalized approach to the multi-body separation problems in a launch vehicle staging environment based on constraint force methodology and its implementation into the Program to Optimize Simulated Trajectories II (POST2), a widely used trajectory design and optimization tool. This development facilitates the inclusion of stage separation analysis into POST2 for seamless end-to-end simulations of launch vehicle trajectories, thus simplifying the overall implementation and providing a range of modeling and optimization capabilities that are standard features in POST2. Analysis and results are presented for two test cases that validate the constraint force equation methodology in a stand-alone mode and its implementation in POST2.

  6. Investigation of the influence of magnetostriction and magnetic forces on transformer core noise and vibration

    NASA Astrophysics Data System (ADS)

    Phophongviwat, Teeraphon

    Transformer noise is of increasing environmental concern so continued efforts are being made by electrical steel and transformer producers to satisfy users by reducing the noise. Magnetostriction and magnetic forces are the main causes of transformer core noise and vibration. Understanding of the relationship from the core material to core structure and core vibration to core noise can help the design of low noise transformer cores. The most appropriate parameter for investigating the relationship between noise and vibration is sound pressure (in the unit of Pascals) in the frequency domain because it is not A-weighted. In this study, the side surfaces of transformer cores were found to emit higher noise than front and top surfaces at low magnetic induction. When the magnetic induction was increased, the effect of magnetic force increased and caused the front surfaces to emit higher noise. For three phase three limb transformer cores, the front surface of the middle limb generated higher noise than the outer limbs due to the effect of T-joint. However this does not translate higher noise level because of the phase difference of the vibration between the limbs. Due to this A-weighted sound power level of three phase, three limb transformer cores were shown to be lower than single phase transformer cores, although at the same cross sectional area and core window size the three phase cores has larger size.. A model, developed to separate the effects of magnetostriction and magnetic forces on transformer core vibration, showed that at low induction, magnetostriction is more significant than magnetic forces. The magnetic forces become more significant than magnetostriction when the induction is increased. Magnetostriction primarily depends on material and stress but magnetic forces principally depend on core building. Louder noise can be generated from a core built with low magnetostriction material than higher magnetostriction if the building tolerances are worse. The effect of magnetic forces on transformer core vibration can be reduced by using a bonding technique..

  7. The health and cost implications of high body mass index in Australian defence force personnel

    PubMed Central

    2012-01-01

    Background Frequent illness and injury among workers with high body mass index (BMI) can raise the costs of employee healthcare and reduce workforce maintenance and productivity. These issues are particularly important in vocational settings such as the military, which require good physical health, regular attendance and teamwork to operate efficiently. The purpose of this study was to compare the incidence of injury and illness, absenteeism, productivity, healthcare usage and administrative outcomes among Australian Defence Force personnel with varying BMI. Methods Personnel were grouped into cohorts according to the following ranges for (BMI): normal (18.5???24.9?kg/m2; n?=?197), overweight (25–29.9?kg/m2; n?=?154) and obese (?30?kg/m2) with restricted body fat (?28% for females, ?24% for males) (n?=?148) and with no restriction on body fat (n?=?180). Medical records for each individual were audited retrospectively to record the incidence of injury and illness, absenteeism, productivity, healthcare usage (i.e., consultation with medical specialists, hospital stays, medical investigations, prescriptions) and administrative outcomes (e.g., discharge from service) over one year. These data were then grouped and compared between the cohorts. Results The prevalence of injury and illness, cost of medical specialist consultations and cost of medical scans were all higher (p?body fat compared with the normal cohort. Within the obese cohort, the prevalence of injury and illness, healthcare usage and productivity were not significantly greater in the obese cohort with no restriction on body fat compared with the cohort with restricted body fat. The number of restricted work days, the rate of re-classification of Medical Employment Classification and the rate of discharge from service were similar between all four cohorts. Conclusions High BMI in the military increases healthcare usage, but does not disrupt workforce maintenance. The greater prevalence of injury and illness, greater healthcare usage and lower productivity in obese Australian Defence Force personnel is not related to higher levels of body fat. PMID:22716068

  8. Verification of a Constraint Force Equation Methodology for Modeling Multi-Body Stage Separation

    NASA Technical Reports Server (NTRS)

    Tartabini, Paul V.; Roithmayr, Carlos; Toniolo, Matthew D.; Karlgaard, Christopher; Pamadi, Bandu N.

    2008-01-01

    This paper discusses the verification of the Constraint Force Equation (CFE) methodology and its implementation in the Program to Optimize Simulated Trajectories II (POST2) for multibody separation problems using three specially designed test cases. The first test case involves two rigid bodies connected by a fixed joint; the second case involves two rigid bodies connected with a universal joint; and the third test case is that of Mach 7 separation of the Hyper-X vehicle. For the first two cases, the POST2/CFE solutions compared well with those obtained using industry standard benchmark codes, namely AUTOLEV and ADAMS. For the Hyper-X case, the POST2/CFE solutions were in reasonable agreement with the flight test data. The CFE implementation in POST2 facilitates the analysis and simulation of stage separation as an integral part of POST2 for seamless end-to-end simulations of launch vehicle trajectories.

  9. Cluster variational method for nuclear matter with the three-body force

    SciTech Connect

    Takano, M.; Togashi, H.; Yamamuro, S.; Nakazato, K.; Suzuki, H.

    2012-11-12

    We report the current status of our project to construct a new nuclear equation of state (EOS), which may be used for supernova numerical simulations, based on the cluster variational method starting from the realistic nuclear Hamiltonian. We also take into account a higher-order correction to the energy of the nuclear three-body force (TBF). The nuclear EOSs with and without the higher-order TBF correction at zero temperature are very close to each other, when parameters are readjusted so as to reproduce the empirical saturation data.

  10. Noninvasive detection of unevenly magnetized permanent magnet of a brushless dc motor by characterizing back electromotive force

    NASA Astrophysics Data System (ADS)

    Lee, C. I.; Jang, G. H.

    2009-04-01

    Uneven magnetization of permanent magnets (PMs) is one of the major sources of unbalanced magnetic force and torque ripple, which excite a brushless dc (BLDC) motor. This paper investigates the frequency contents of the back electromotive force (BEMF) due to the unevenly magnetized PMs in a BLDC motor. The magnetic field of a BLDC motor is solved by using the finite element method, and the BEMF is calculated by differentiating the flux linkage with respect to time. The characteristics of BEMF are investigated by using the spectral analysis. Magnetic flux density of the ideally magnetized PMs has the harmonics of the pole-pair number, but unevenly magnetized PMs generate the additional harmonics. This research shows numerically and experimentally that the frequency components of the BEMF are determined by the least common multiple between the frequency contents of magnetic flux density from the PMs and the slot number per phase. It also shows that the magnetized status of the PMs of a BLDC can be noninvasively identified by monitoring the frequencies and the amplitudes of BEMF.

  11. Limitations of force-free magnetic field extrapolations: Revisiting basic assumptions

    NASA Astrophysics Data System (ADS)

    Peter, H.; Warnecke, J.; Chitta, L. P.; Cameron, R. H.

    2015-12-01

    Context. Force-free extrapolations are widely used to study the magnetic field in the solar corona based on surface measurements. Aims: The extrapolations assume that the ratio of internal energy of the plasma to magnetic energy, the plasma ?, is negligible. Despite the widespread use of this assumption observations, models, and theoretical considerations show that ? is of the order of a few percent to more than 10%, and thus not small. We investigate what consequences this has for the reliability of extrapolation results. Methods: We use basic concepts starting with force and energy balance to infer relations between plasma ? and free magnetic energy to study the direction of currents in the corona with respect to the magnetic field, and to estimate the errors in the free magnetic energy by neglecting effects of the plasma (? ? 1). A comparison with a 3D magneto-hydrodynamics (MHD) model supports our basic considerations. Results: If plasma ? is of the order of the relative free energy (the ratio of the free magnetic energy to the total magnetic energy) then the pressure gradient can balance the Lorentz force. This is the case in solar corona, and therefore the currents are not properly described. In particular, the error in terms of magnetic energy by neglecting the plasma is of the order of the free magnetic energy, so that the latter cannot be reliably determined by an extrapolation. Conclusions: While a force-free extrapolation might capture the magnetic structure and connectivity of the coronal magnetic field, the derived currents and free magnetic energy are not reliable. Thus quantitative results of extrapolations on the location and amount of heating in the corona (through current dissipation) and on the energy storage of the magnetic field (e.g. for eruptive events) are limited.

  12. Three-body force effect on nuclear symmetry energy and single-particle properties of asymmetric nuclear matter

    NASA Astrophysics Data System (ADS)

    Zuo, Wei; Bombaci, Ignazio; Lombardo, Umberto

    2014-02-01

    We present an upgraded review of our microscopic investigation on the single-particle properties and the EOS of isospin asymmetric nuclear matter within the framework of the Brueckner theory extended to include a microscopic three-body force. We pay special attention to the discussion of the three-body force effect and the comparison of our results with the predictions by other ab initio approaches. Three-body force is shown to be necessary for reproducing the empirical saturation properties of symmetric nuclear matter within nonrelativistic microscopic frameworks, and also for extending the hole-line expansion to a wide density range. The three-body force effect on nuclear symmetry energy is repulsive, and it leads to a significant stiffening of the density dependence of symmetry energy at supra-saturation densities. Within the Brueckner approach, the three-body force affects the nucleon s.p. potentials primarily via its rearrangement contribution which is strongly repulsive and momentum-dependent at high densities and high momenta. Both the rearrangement contribution induced by the three-body force and the effect of ground-state correlations are crucial for predicting reliably the single-particle properties within the Brueckner framework.

  13. Magnetic buoyancy force acting on bubbles in nonconducting and diamagnetic fluids under microgravity

    NASA Astrophysics Data System (ADS)

    Wakayama, Nobuko I.

    1997-04-01

    The magnetic buoyancy force acting on a bubble in a one-dimensional magnetic field can be represented as F=(?G-?L)?H(dH/dx)dVolB, where ?G and ?L are the volume magnetic susceptibilities of the gas and liquid, respectively, and H is the magnetic field strength. Since |?L|?|?G| and most liquids are diamagnetic, this expression indicates that the magnetic buoyancy forces act in the direction of increasing magnetic field strength. Because the magnetic buoyancy force in a diamagnetic fluid is small, the motion of bubbles under normal gravity is difficult to study, but microgravity offers the possibility of detailed observations. Using a compact permanent magnet under microgravity conditions, N2 bubbles in pure water (0.01 dyne s/cm2) and in a 69:31 glycerol/water mixture (0.21 dyne s/cm2) were found to move in the direction of increasing H, and to be held stationary at the point of maximum H. The motion of the bubbles was also simulated with a theoretical model and was found to agree with measurements made under microgravity conditions. These results indicate that magnetic buoyancy can be used to control bubble motion. Since most fluids are diamagnetic, magnetic buoyancy can be used to control bubbles in many fluidic devices used in space applications.

  14. Measured force on elongated bodies in a simulated low-Earth orbit environment

    SciTech Connect

    Maldonado, C. A.; Ketsdever, A. D.; Gimelshein, S. F.

    2014-12-09

    An overview of the development of a magnetically filtered atomic oxygen plasma source and the application of the source to study low-Earth orbit drag on elongated bodies is presented. Plasma diagnostics show that the magnetic filter plasma source produces atomic oxygen ions (O{sup +}) with streaming energies equivalent to the relative orbital environment of approximately 5eV and can supply the appropriate density for LEO simulation. Previous research has demonstrated that momentum transfer between ions and metal surfaces is equivalent to the momentum transfer expected for neutral molecules with similar energy, due to charge exchange occurring prior to momentum transfer. Total drag measurements of aluminum cuboid geometries of varying length to diameter ratios immersed in the extracted plasma plume are presented as a function of streaming ion energy.

  15. Many-body Interactions in Magnetic Films and Nanostructures

    SciTech Connect

    Stephen D. Kevan

    2012-12-12

    We describe results supported by DOE grant DE-FG02-04ER46158, which focused on magnetic interaction at surfaces, in thin films, and in metallic nanostructures. We report on three general topics: 1) The Rashba spin splitting at magnetic surfaces of rare earth metals, 2) magnetic nanowires self-assembled on stepped tungsten single crystals, and 3) magnetic interaction in graphene films doped with hydrogen atoms.

  16. Magnetic force microscopy method and apparatus to detect and image currents in integrated circuits

    DOEpatents

    Campbell, Ann. N. (13170-B Central SE #188, Albuquerque, NM 87123); Anderson, Richard E. (2800 Tennessee NE, Albuquerque, NM 87110); Cole, Jr., Edward I. (2116 White Cloud NE, Albuquerque, NM 87112)

    1995-01-01

    A magnetic force microscopy method and improved magnetic tip for detecting and quantifying internal magnetic fields resulting from current of integrated circuits. Detection of the current is used for failure analysis, design verification, and model validation. The interaction of the current on the integrated chip with a magnetic field can be detected using a cantilevered magnetic tip. Enhanced sensitivity for both ac and dc current and voltage detection is achieved with voltage by an ac coupling or a heterodyne technique. The techniques can be used to extract information from analog circuits.

  17. Magnetic force microscopy method and apparatus to detect and image currents in integrated circuits

    DOEpatents

    Campbell, A.N.; Anderson, R.E.; Cole, E.I. Jr.

    1995-11-07

    A magnetic force microscopy method and improved magnetic tip for detecting and quantifying internal magnetic fields resulting from current of integrated circuits are disclosed. Detection of the current is used for failure analysis, design verification, and model validation. The interaction of the current on the integrated chip with a magnetic field can be detected using a cantilevered magnetic tip. Enhanced sensitivity for both ac and dc current and voltage detection is achieved with voltage by an ac coupling or a heterodyne technique. The techniques can be used to extract information from analog circuits. 17 figs.

  18. Alternating Magnetic Field Forces for Satellite Formation Flying

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Nurge, Mark A.; Starr, Stnaley O.

    2012-01-01

    Selected future space missions, such as large aperture telescopes and multi-component interferometers, will require the precise positioning of a number of isolated satellites, yet many of the suggested approaches for providing satellites positioning forces have serious limitations. In this paper we propose a new approach, capable of providing both position and orientation forces, that resolves or alleviates many of these problems. We show that by using alternating fields and currents that finely-controlled forces can be induced on the satellites, which can be individually selected through frequency allocation. We also show, through analysis and experiment, that near field operation is feasible and can provide sufficient force and the necessary degrees of freedom to accurately position and orient small satellites relative to one another. In particular, the case of a telescope with a large number of free mirrors is developed to provide an example of the concept. We. also discuss the far field extension of this concept.

  19. Magnetic damping forces in figure-eight-shaped null-flux coil suspension systems

    SciTech Connect

    He, Jianliang; Coffey, H.

    1997-08-01

    This paper discusses magnetic damping forces in figure-eight-shaped null-flux coil suspension systems, focusing on the Holloman maglev rocket system. The paper also discusses simulating the damping plate, which is attached to the superconducting magnet by two short-circuited loop coils in the guideway. Closed-form formulas for the magnetic damping coefficient as functions of heave-and-sway displacements are derived by using a dynamic circuit model. These formulas are useful for dynamic stability studies.

  20. A long-lived coronal X-ray arcade. [force-free magnetic field analysis

    NASA Technical Reports Server (NTRS)

    Mcguire, J. P.; Tandberg-Hanssen, E.; Krall, K. R.; Wu, S. T.; Smith, J. B., Jr.; Speich, D. M.

    1977-01-01

    A large, long-lived, soft X-ray emitting arch system observed during a Skylab mission is analyzed. The supposition is that these arches owe their stability to the stable coronal magnetic-field configuration. A global constant alpha force-free magnetic field analysis, is used to describe the arches which stayed in the same approximate position for several solar rotations. A marked resemblance is noted between the theoretical magnetic field configuration and the observed X-ray emmitting feature.

  1. Sting-free Unsteady Flowfield, Base Pressure and Force Measurements on Axisymmetric Bluff-Body

    NASA Astrophysics Data System (ADS)

    Higuchi, Hiroshi; Sawada, Hideo; Kato, Hiroyuki; Kunimasu, Tetsuya

    2006-11-01

    To avoid interference of model support, flowfields as well as aerodynamic force and base pressure on blunt short cylinders in axial flow were measured at Re=100,000 with the JAXA 60cm magnetic suspension and balance system. The fineness ratio ranged from 1.27 to 1.79. A digital telemeter system was developed for the base pressure measurement, and the velocity field was obtained using a PIV system. Vortices along separating shear layer and shear layer flappings with or without reattachment on the wall were observed. Downstream the cylinder in the azimuthal plane, PIV snapshots showed large-scale motion of longitudinal vortices. These instantaneous flowfields presented excellent axisymmetry when they were ensemble-averaged. Mean base pressure agreed with the drag variation at different fineness ratios. The present magnetic suspension and balance system allowed evaluation of low frequency unsteady aerodynamic force vector from feedback current to the coils and the detected small model movement. Base pressure fluctuations were compared with the drag fluctuations and discussed in light of overall flowfield phenomena.

  2. On some properties of force-free magnetic fields in infinite regions of space

    NASA Technical Reports Server (NTRS)

    Aly, J. J.

    1984-01-01

    Techniques for solving boundary value problems (BVP) for a force free magnetic field (FFF) in infinite space are presented. A priori inequalities are defined which must be satisfied by the force-free equations. It is shown that upper bounds may be calculated for the magnetic energy of the region provided the value of the magnetic normal component at the boundary of the region can be shown to decay sufficiently fast at infinity. The results are employed to prove a nonexistence theorem for the BVP for the FFF in the spatial region. The implications of the theory for modeling the origins of solar flares are discussed.

  3. Magnetic Circuit Model of PM Motor-Generator to Predict Radial Forces

    NASA Technical Reports Server (NTRS)

    McLallin, Kerry (Technical Monitor); Kascak, Peter E.; Dever, Timothy P.; Jansen, Ralph H.

    2004-01-01

    A magnetic circuit model is developed for a PM motor for flywheel applications. A sample motor is designed and modeled. Motor configuration and selection of materials is discussed, and the choice of winding configuration is described. A magnetic circuit model is described, which includes the stator back iron, rotor yoke, permanent magnets, air gaps and the stator teeth. Iterative solution of this model yields flux linkages, back EMF, torque, power, and radial force at the rotor caused by eccentricity. Calculated radial forces are then used to determine motor negative stiffness.

  4. Characterizing local anisotropy of coercive force in motor laminations with the moving magnet hysteresis comparator

    NASA Astrophysics Data System (ADS)

    Garshelis, I. J.; Crevecoeur, G.

    2014-05-01

    Non oriented silicon steels are widely used within rotating electrical machines and are assumed to have no anisotropy. There exists a need to detect the anisotropic magnetic properties and to evaluate the local changes in magnetic material properties due to manufacturing cutting processes. In this paper, the so called moving magnet hyteresis comparator is applied to non destructively detect directional variations in coercive force in a variety of local regions of rotor and stator laminations of two materials commonly used to construct induction motors cores. Maximum to minimum coercive force ratios were assessed, varying from 1.4 to 1.7.

  5. Forced MHD turbulence in a uniform external magnetic field

    NASA Technical Reports Server (NTRS)

    Hossain, M.; Vahala, G.; Montgomery, D.

    1985-01-01

    Two-dimensional dissipative MHD turbulence is randomly driven at small spatial scales and is studied by numerical simulation in the presence of a strong uniform external magnetic field. A behavior is observed which is apparently distinct from the inverse cascade which prevails in the absence of an external magnetic field. The magnetic spectrum becomes dominated by the three longest wavelength Alfven waves in the system allowed by the boundary conditions: those which, in a box size of edge 2 pi, have wave numbers (kx' ky) = (1, 1), and (1, -1), where the external magnetic field is in the x direction. At any given instant, one of these three modes dominates the vector potential spectrum, but they do not constitute a resonantly coupled triad. Rather, they are apparently coupled by the smaller-scale turbulence.

  6. Phase diagrams of forced magnetic reconnection in Taylor's model

    NASA Astrophysics Data System (ADS)

    Comisso, L.; Grasso, D.; Waelbroeck, F. L.

    2015-10-01

    > , depending on the parameters that characterize the external drive, which have not been considered until now. These features are crucial to understanding the onset and evolution of magnetic reconnection in diverse physical systems.

  7. Dynamics of a Levitron under a periodic magnetic forcing

    NASA Astrophysics Data System (ADS)

    Pérez, Alberto T.; García-Sánchez, Pablo

    2015-02-01

    The Levitron is a toy that consists of a spinning top that levitates over a magnetic base for a few minutes, until air drag decreases the spin rate below a certain limit. Stable levitation, lasting hours or even days, has been achieved for Levitrons that were externally driven by either an air jet or an alternating magnetic field. We report measurements of stable levitation for the latter case. We show that the top precession couples with the frequency of the alternating field, so that the precession period equals the period of the field. In addition, the top rotates around itself with the same period. We present numerical simulations that reproduce the essential features of this dynamics. It is also shown that the magnetic torque that drives the top is due to a misalignment between the magnetic dipole moment and the mechanical axis of the top.

  8. Electromagnetic Forces in a Hybrid Magnetic-Bearing Switched-Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.; Siebert, Mark W.; Ho, Eric J.

    2008-01-01

    Analysis and experimental measurement of the electromagnetic force loads on the hybrid rotor in a novel hybrid magnetic-bearing switched-reluctance motor (MBSRM) have been performed. A MBSRM has the combined characteristics of a switched-reluctance motor and a magnetic bearing. The MBSRM discussed in this report has an eight-pole stator and a six-pole hybrid rotor, which is composed of circular and scalloped lamination segments. The hybrid rotor is levitated using only one set of four stator poles, while a second set of four stator poles imparts torque to the scalloped portion of the rotor, which is driven in a traditional switched reluctance manner by a processor. Static torque and radial force analysis were done for rotor poles that were oriented to achieve maximum and minimum radial force loads on the rotor. The objective is to assess whether simple one-dimensional magnetic circuit analysis is sufficient for preliminary evaluation of this machine, which may exhibit strong three-dimensional electromagnetic field behavior. Two magnetic circuit geometries, approximating the complex topology of the magnetic fields in and around the hybrid rotor, were employed in formulating the electromagnetic radial force equations. Reasonable agreement between the experimental and the theoretical radial force loads predictions was obtained with typical magnetic bearing derating factors applied to the predictions.

  9. Measurement of internal forces in superconducting accelerator magnets with strain gauge transducers

    SciTech Connect

    Goodzeit, C.L.; Anerella, M.D.; Ganetis, G.L.

    1988-01-01

    An improved method has been developed for the measurement of internal forces in superconducting accelerator magnets, in particular the compressive stresses in coils and the end restraint forces on the coils. The transducers have been designed to provide improved sensitivity to purely mechanical strain by using bending mode deflections for sensing the applied loads. Strain gauge resistance measurements are made with a new system that eliminates sources of errors due to spurious resistance changes in interconnecting wiring and solder joints. The design of the transducers and their measurement system is presented along with a discussion of the method of compensation for thermal and magnetic effects, methods of calibration with typical calibration data, and measured effect in actual magnets of the thermal stress changes from cooldown and the Lorentz forces during magnet excitation. 13 figs., 1 tab.

  10. MEMS-based Force-clamp Analysis of the Role of Body Stiffness in C. elegans Touch Sensation

    PubMed Central

    Petzold, Bryan C.; Park, Sung-Jin; Mazzochette, Eileen A.; Goodman, Miriam B.; Pruitt, Beth L.

    2013-01-01

    Touch is enabled by mechanoreceptor neurons in the skin and plays an essential role in our everyday lives, but is among the least understood of our five basic senses. Force applied to the skin deforms these neurons and activates ion channels within them. Despite the importance of the mechanics of the skin in determining mechanoreceptor neuron deformation and ultimately touch sensation, the role of mechanics in touch sensitivity is poorly understood. Here, we use the model organism Caenorhabditis elegans to directly test the hypothesis that body mechanics modulate touch sensitivity. We demonstrate a microelectromechanical system (MEMS)-based force clamp that can apply calibrated forces to freely crawling C. elegans worms and measure touch-evoked avoidance responses. This approach reveals that wild-type animals sense forces < 1 ?N and indentation depths < 1 ?m. We use both genetic manipulation of the skin and optogenetic modulation of body wall muscles to alter body mechanics. We find that small changes in body stiffness dramatically affect force sensitivity, while having only modest effects on indentation sensitivity. We investigate the theoretical body deformation predicted under applied force and conclude that local mechanical loads induce inward bending deformation of the skin to drive touch sensation in C. elegans. PMID:23598612

  11. Enhanced quality factors and force sensitivity by attaching magnetic beads to cantilevers for atomic force microscopy in liquid

    NASA Astrophysics Data System (ADS)

    Hoof, Sebastian; Nand Gosvami, Nitya; Hoogenboom, Bart W.

    2012-12-01

    Dynamic-mode atomic force microscopy (AFM) in liquid remains complicated due to the strong viscous damping of the cantilever resonance. Here, we show that a high-quality resonance (Q >20) can be achieved in aqueous solution by attaching a microgram-bead at the end of the nanogram-cantilever. The resulting increase in cantilever mass causes the resonance frequency to drop significantly. However, the force sensitivity—as expressed via the minimum detectable force gradient—is hardly affected, because of the enhanced quality factor. Through the enhancement of the quality factor, the attached bead also reduces the relative importance of noise in the deflection detector. It can thus yield an improved signal-to-noise ratio when this detector noise is significant. We describe and analyze these effects for a set-up that includes magnetic actuation of the cantilevers and that can be easily implemented in any AFM system that is compatible with an inverted optical microscope.

  12. A portable Halbach magnet that can be opened and closed without force: The NMR-CUFF

    NASA Astrophysics Data System (ADS)

    Windt, Carel W.; Soltner, Helmut; Dusschoten, Dagmar van; Blümler, Peter

    2011-01-01

    Portable equipment for nuclear magnetic resonance (NMR) is becoming increasingly attractive for use in a variety of applications. One of the main scientific challenges in making NMR portable is the design of light-weight magnets that possess a strong and homogeneous field. Existing NMR magnets can provide such magnetic fields, but only for small samples or in small regions, or are rather heavy. Here we show a simple yet elegant concept for a Halbach-type permanent magnet ring, which can be opened and closed with minimal mechanical force. An analytical solution for an ideal Halbach magnet shows that the magnetic forces cancel if the structure is opened at an angle of 35.3° relative to its poles. A first prototype weighed only 3.1 kg, and provided a flux density of 0.57 T with a homogeneity better than 200 ppm over a spherical volume of 5 mm in diameter without shimming. The force needed to close it was found to be about 20 N. As a demonstration, intact plants were imaged and water (xylem) flow measured. Magnets of this type (NMR-CUFF = Cut-open, Uniform, Force Free) are ideal for portable use and are eminently suited to investigate small or slender objects that are part of a larger or immobile whole, such as branches on a tree, growing fruit on a plant, or non-metallic tubing in industrial installations. This new concept in permanent-magnet design enables the construction of openable, yet strong and homogeneous magnets, which aside from use in NMR or MRI could also be of interest for applications in accelerators, motors, or magnetic bearings.

  13. Prediction of ocean-induced magnetic signals in the satellite observations due to tidal forcing

    NASA Astrophysics Data System (ADS)

    Dostal, J.; Dobslaw, H.; Thomas, M.

    2009-04-01

    An increase in accuracy of the Earth's magnetic field observations by the future SWARM satellite mission strengths the interest of dealing with magnetic signals of small amplitudes but a global support. An example of such a signal is the magnetic field variation induced by global ocean dynamics. Since sea-water is a good electrical conductor, the ocean currents represent electrical currents moving in the main magnetic field. According to the Faraday's law, they induce a secondary magnetic field that is, in principle, observable by ground and satellite observations. Although they are of small amplitudes, they have recently been identified for ocean currents forced by the tidal wave M2. The identification of small magnetic components in the total magnetic signal can be helpt by their numerical prediction. The 2-D theory for computing the magnetic field generated by ocean currents that has been proposed by Tyler et al. (1997) is combined with the ocean tidal flows simulated by the numerical ocean model for circulation and tides (OMCT; Thomas 2002) and used to calculate secondary magnetic field generated by lunar-solar tidal potential for individual tidal waves. Unlike to some recent studies where the ocean currents have been deduced from altimetry data by applying the geostrophic method, the ocean flows calculated by the OMCT approach are forced directly by the lunisolar tidal potential that is deduced from analytical ephemerides. As a result, the method provides the radial component of the ocean-induced magnetic signal at the sea surface and satellite altitude. A comparison with published results by Tyler et al. (2003) and Maus et al. (2004) shows a good agreement in terms of global spatial pattern and magnitude, though some minor differences occur. This new method simplifies the calculation of ocean-induced magnetic fields and allows the prediction of the secondary magnetic fields induced by the complete lunisolar tidal forcing. This numerical approach can be used to estimate the opportunities in detecting ocean-induced magnetic signals in satellite observations.

  14. Extraction of user's navigation commands from upper body force interaction in walker assisted gait

    PubMed Central

    2010-01-01

    Background The advances in technology make possible the incorporation of sensors and actuators in rollators, building safer robots and extending the use of walkers to a more diverse population. This paper presents a new method for the extraction of navigation related components from upper-body force interaction data in walker assisted gait. A filtering architecture is designed to cancel: (i) the high-frequency noise caused by vibrations on the walker's structure due to irregularities on the terrain or walker's wheels and (ii) the cadence related force components caused by user's trunk oscillations during gait. As a result, a third component related to user's navigation commands is distinguished. Results For the cancelation of high-frequency noise, a Benedict-Bordner g-h filter was designed presenting very low values for Kinematic Tracking Error ((2.035 ± 0.358)·10-2 kgf) and delay ((1.897 ± 0.3697)·101ms). A Fourier Linear Combiner filtering architecture was implemented for the adaptive attenuation of about 80% of the cadence related components' energy from force data. This was done without compromising the information contained in the frequencies close to such notch filters. Conclusions The presented methodology offers an effective cancelation of the undesired components from force data, allowing the system to extract in real-time voluntary user's navigation commands. Based on this real-time identification of voluntary user's commands, a classical approach to the control architecture of the robotic walker is being developed, in order to obtain stable and safe user assisted locomotion. PMID:20687921

  15. Approximating edges of source bodies from magnetic or gravity anomalies.

    USGS Publications Warehouse

    Blakely, R.J.; Simpson, R.W.

    1986-01-01

    Cordell and Grauch (1982, 1985) discussed a technique to estimate the location of abrupt lateral changes in magnetization or mass density of upper crustal rocks. The final step of their procedure is to identify maxima on a contoured map of horizontal gradient magnitudes. Attempts to automate their final step. The method begins with gridded magnetic or gravity anomaly data and produces a plan view of inferred boundaries of magnetic or gravity sources. The method applies to both local surveys and to continent-wide compilations of magnetic and gravity data.-from Authors

  16. Crossing in the magnetic force-gap hysteresis curve of magnetic levitation systems with a high- T c superconductor

    NASA Astrophysics Data System (ADS)

    Gou, Xiao-Fan; Zhang, Zhao-Xia

    2010-05-01

    For the magnetic levitation system consisting of a high- T c superconductor and permanent magnet, the relation curve of magnetic force with gap between these two components is known as a hysteresis loop, that is, the approaching and departing portions envelop a complete one, and generally these two portions do not cross each other. However, in some special cases this crossing arises, and makes the complete loop broken. In this paper, by the numerical simulation of the magnetic force-gap curve in large numbers of physical and geometrical parameters, two typical crossings were found. To investigate the crossing and explore its physical causes, for one of the crossings, the current density in the superconductor was further calculated and its magnitude and vector distribution at the gaps nearby where the crossing arises were obtained. Based on these calculation results and an adequate discussion, the conclusion was induced that the crossing in the magnetic force-gap hysteresis curve results from applied magnetic field’s incomplete and insufficient penetrating in superconductor.

  17. Magnetic Field, Force, and Inductance Computations for an Axially Symmetric Solenoid

    NASA Technical Reports Server (NTRS)

    Lane, John E.; Youngquist, Robert C.; Immer, Christopher D.; Simpson, James C.

    2001-01-01

    The pumping of liquid oxygen (LOX) by magnetic fields (B field), using an array of electromagnets, is a current topic of research and development at Kennedy Space Center, FL. Oxygen is paramagnetic so that LOX, like a ferrofluid, can be forced in the direction of a B field gradient. It is well known that liquid oxygen has a sufficient magnetic susceptibility that a strong magnetic gradient can lift it in the earth's gravitational field. It has been proposed that this phenomenon can be utilized in transporting (i.e., pumping) LOX not only on earth, but on Mars and in the weightlessness of space. In order to design and evaluate such a magnetic pumping system, it is essential to compute the magnetic and force fields, as well as inductance, of various types of electromagnets (solenoids). In this application, it is assumed that the solenoids are air wrapped, and that the current is essentially time independent.

  18. Magnetic energy dissipation in force-free jets

    NASA Technical Reports Server (NTRS)

    Choudhuri, Arnab Rai; Konigl, Arieh

    1986-01-01

    It is shown that a magnetic pressure-dominated, supersonic jet which expands or contracts in response to variations in the confining external pressure can dissipate magnetic energy through field-line reconnection as it relaxes to a minimum-energy configuration. In order for a continuous dissipation to occur, the effective reconnection time must be a fraction of the expansion time. The dissipation rate for the axisymmetric minimum-energy field configuration is analytically derived. The results indicate that the field relaxation process could be a viable mechanism for powering the synchrotron emission in extragalactic jets if the reconnection time is substantially shorter than the nominal resistive tearing time in the jet.

  19. Resolving sub-cellular force dynamics using arrays of magnetic microposts

    NASA Astrophysics Data System (ADS)

    Reich, Daniel

    2010-03-01

    The biological response of cells to mechanical forces is integral to both normal cell function and the progression of many diseases, such as hypertensive vascular wall thickening. This likely results from the fact that mechanical stresses can directly affect many cellular processes, including signal transduction, gene expression, growth, differentiation, and survival. The need to understand the relationship between applied forces and the mechanical response of cells as a critical step towards understanding mechanotransduction calls for tools that can apply forces to cells while measuring their contractile response. This talk will describe an approach that simultaneously allows local mechanical stimulation of the adherent surface of a cell and spatially resolved measurement of the local force fields generated throughout the cell in response to this stimulation. Cells are cultured on the top surfaces of arrays of micrometer-scale posts made from a flexible elastomer (PDMS), and the contractile forces generated by an adherent cell bend the posts. Measurements of the displacement of each post allow the contractile force field of the cell to be mapped out with sub-cellular precision. To apply forces to cells, rod- shaped magnetic nanoparticles are embedded in some of the posts so that externally applied magnetic fields selectively deform these ``magnetic posts,'' thereby exerting tunable local, mechanical stresses to the adherent surface of attached cells. Alternatively, magnetic particles bound to or internalized by the cell may be employed to apply forces and torques to the cell. With either approach, measuring the deflection of the surrounding non-magnetic posts probes the full mechanical response of the cell to these stresses. Results that illustrate the temporal dynamics and spatial distribution of the non-local response of fibroblasts and smooth muscle cells to local stresses will be discussed.

  20. Drag measurements on a laminar flow body of revolution in Langley's 13 inch magnetic suspension and balance system. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Dress, David A.

    1988-01-01

    Low-speed wind tunnel drag force measurements were taken on a laminar flow body of revolution free of support interference. This body was tested at zero incidence in the NASA Langley 13 inch Magnetic Suspension and Balance System (MSBS). The primary objective of these tests was to substantiate the drag force measuring capabilities of the 13 inch MSBS. A secondary objective was to obtain support interference free drag measurements on an axisymmetric body of interest. Both objectives were met. The drag force calibrations and wind-on repeatability data provide a means of assessing the drag force measuring capabilities of the 13 inch MSBS. The measured drag coefficients for this body are of interest to researchers actively involved in designing minimum drag fuselage shapes. Additional investigations included: the effects of fixing transition; the effects of fins installed in the tail; surface flow visualizations using both liquid crystals and oil flow; and base pressure measurements using a one-channel telemetry system. Two drag prediction codes were used to assess their usefulness in estimating overall body drag. These theoretical results did not compare well with the measured values because of the following: incorrect or non-existent modeling of a laminar separation bubble on the body and incorrect of non-existent estimates of base pressure drag.

  1. In situ observation of the solution convection induced by magnetic force using photoreaction

    NASA Astrophysics Data System (ADS)

    Koyama, F.; Tanimoto, Y.

    The effects of vertical magnetic fields (?1260 T2/m) on the laser-induced convection of a benzene solution were studied by using a photo-induced coloration reaction of CBr4 and diphenylamine. A green solution, photo-generated at the bottom surface of a vessel, flowed against the magnetic field center. The speed of the solution depended strongly on the intensity and direction of the magnetic force. These effects were discussed in terms of the difference in the magnetic susceptibilities of the green solution and the surrounding one.

  2. Long-lived magnetism from solidification-driven convection on the pallasite parent body

    NASA Astrophysics Data System (ADS)

    Bryson, James F. J.; Nichols, Claire I. O.; Herrero-Albillos, Julia; Kronast, Florian; Kasama, Takeshi; Alimadadi, Hossein; van der Laan, Gerrit; Nimmo, Francis; Harrison, Richard J.

    2015-01-01

    Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven, implying that magnetic activity would have been short-lived. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core is consistent with our measured magnetic field characteristics and cooling rates. Solidification-driven convection was probably common among small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar System.

  3. Long-lived magnetism from solidification-driven convection on the pallasite parent body.

    PubMed

    Bryson, James F J; Nichols, Claire I O; Herrero-Albillos, Julia; Kronast, Florian; Kasama, Takeshi; Alimadadi, Hossein; van der Laan, Gerrit; Nimmo, Francis; Harrison, Richard J

    2015-01-22

    Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven, implying that magnetic activity would have been short-lived. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core is consistent with our measured magnetic field characteristics and cooling rates. Solidification-driven convection was probably common among small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar System. PMID:25612050

  4. A magnetic micro-manipulator for application of three dimensional forces.

    PubMed

    Punyabrahma, P; Jayanth, G R

    2015-02-01

    Magnetic manipulation finds diverse applications in actuation, characterization, and manipulation of micro- and nano-scale samples. This paper presents the design and development of a novel magnetic micro-manipulator for application of three-dimensional forces on a magnetic micro-bead. A simple analytical model is proposed to obtain the forces of interaction between the magnetic micro-manipulator and a magnetic micro-bead. Subsequently, guidelines are proposed to perform systematic design and analysis of the micro-manipulator. The designed micro-manipulator is fabricated and evaluated. The manipulator is experimentally demonstrated to possess an electrical bandwidth of about 1 MHz. The ability of the micro-manipulator to apply both in-plane and out-of-plane forces is demonstrated by actuating permanent-magnet micro-beads attached to micro-cantilever beams. The deformations of the micro-cantilevers are also employed to calibrate the dependence of in-plane and out-of-plane forces on the position of the micro-bead relative to the micro-manipulator. The experimentally obtained dependences are found to agree well with theory. PMID:25725878

  5. Force-detected nuclear magnetic resonance: recent advances and future challenges.

    PubMed

    Poggio, M; Degen, C L

    2010-08-27

    We review recent efforts to detect small numbers of nuclear spins using magnetic resonance force microscopy. Magnetic resonance force microscopy (MRFM) is a scanning probe technique that relies on the mechanical measurement of the weak magnetic force between a microscopic magnet and the magnetic moments in a sample. Spurred by the recent progress in fabricating ultrasensitive force detectors, MRFM has rapidly improved its capability over the last decade. Today it boasts a spin sensitivity that surpasses conventional, inductive nuclear magnetic resonance detectors by about eight orders of magnitude. In this review we touch on the origins of this technique and focus on its recent application to nanoscale nuclear spin ensembles, in particular on the imaging of nanoscale objects with a three-dimensional (3D) spatial resolution better than 10 nm. We consider the experimental advances driving this work and highlight the underlying physical principles and limitations of the method. Finally, we discuss the challenges that must be met in order to advance the technique towards single nuclear spin sensitivity-and perhaps-to 3D microscopy of molecules with atomic resolution. PMID:20671365

  6. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  7. A discrete-forcing immersed boundary method for the fluid-structure interaction of an elastic slender body

    NASA Astrophysics Data System (ADS)

    Lee, Injae; Choi, Haecheon

    2015-01-01

    We present an immersed boundary (IB) method for the simulation of flow around an elastic slender body. The present method is based on the discrete-forcing IB method for a stationary, rigid body proposed by Kim, Kim and Choi (2001) [25]. The discrete-forcing approach is used to relieve the limitation on the computational time step size. The incompressible Navier-Stokes equations are implicitly coupled with the dynamic equation for an elastic slender body motion. The first is solved in the Eulerian coordinate and the latter is described in the Lagrangian coordinate. The elastic slender body is modeled as a thin and flexible solid and is segmented by finite number of thin blocks. Each block is moved by external and internal forces such as the hydrodynamic, elastic and buoyancy forces, where the hydrodynamic force is obtained directly from the discrete forcing used in the IB method. All the spatial derivative terms are discretized with the second-order central difference scheme. The present method is applied to three different fluid-structure interaction problems: flows around a flexible filament, a flapping flag in a free stream, and a flexible flapping wing in normal hovering, respectively. Computations are performed at maximum CFL numbers of 0.75-1. The results obtained agree very well with those from previous studies.

  8. A Hybrid N-Body Code Incorporating Algorithmic Regularization and Post-Newtonian Forces

    E-print Network

    S. Harfst; A. Gualandris; D. Merritt; S. Mikkola

    2008-06-26

    We describe a novel N-body code designed for simulations of the central regions of galaxies containing massive black holes. The code incorporates Mikkola's 'algorithmic' chain regularization scheme including post-Newtonian terms up to PN2.5 order. Stars moving beyond the chain are advanced using a fourth-order integrator with forces computed on a GRAPE board. Performance tests confirm that the hybrid code achieves better energy conservation, in less elapsed time, than the standard scheme and that it reproduces the orbits of stars tightly bound to the black hole with high precision. The hybrid code is applied to two sample problems: the effect of finite-N gravitational fluctuations on the orbits of the S-stars; and inspiral of an intermediate-mass black hole into the galactic center.

  9. Microscopic optical potential with two and three body forces for nucleon-nucleus scattering

    NASA Astrophysics Data System (ADS)

    Gambhir, Y. K.; Gupta, M.; Bhagwat, A.; Haider, W.; Rafi, Sayed; Sharma, M.; Pachouri, D.

    2014-03-01

    The proton - nucleus optical potentials generated by folding the calculated complex, density and energy dependent g- matrices (with and without three-body forces (TBF): Urbana IX (UVIX) and TNI) over the target nucleon density distributions obtained from the relativistic mean field theory, are used for the calculation of the differential cross section d? / d? , polarization Ay , spin rotation function (Q). for 65 and 200 MeV polarized proton incident on 40Ca and 208Pb . The agreement with the experiment is rather impressive. It is found that the inclusion of TBF (Urbana IX )UVIX) and TNI) reduces the strength of the central part of the optical potential in the nuclear interior and affects the calculated spin-orbit potential only marginally and leads to an improvement in the agreement with the corresponding experimental results.

  10. Quantitative nuclear magnetic resonance to measure body composition in infants and children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantitative Nuclear Magnetic Resonance (QMR) is being used in human adults to obtain measures of total body fat (FM) with high precision. The current study assessed a device specially designed to accommodate infants and children between 3 and 50 kg (EchoMRI-AH™). Body composition of 113 infants and...

  11. An Experimental Study on Base Pressure Correction for Bluff-Base Bodies Using Magnetic Suspension and Balance System

    NASA Astrophysics Data System (ADS)

    Tadakuma, Kenji; Aso, Shigeru; Tani, Yasuhiro; Mizoguchi, Yasushi; Okada, Takumi

    An experimental study on validity and improvement of base pressure correction for a bluff-base body with hemisphere nose using MSBS (Magnetic Suspension and Balance System) has been conducted. Force and pressure distribution data on the model base were examined for several parameters; angles of attack 0 7.5º, Reynolds number ReD=7.6×104, with or without a sting and diameters of the sting. These results showed that the base pressure correction using the pressure data near the sting could have validity at the case of 0º of angle of attack only. Besides we could propose a new accurate method to calculate base-pressure axis forces.

  12. General{relativistic free decay of magnetic elds in a spherically symmetric body.

    E-print Network

    in its nonconducting surroundings is sys- tematically studied. The body, considered as a rough model{space electrodynamics the initial value problem for the magnetic eld is formulated. The concept of poloidal and toroidal Typeset using REVTEX 2 #12;I. INTRODUCTION A magnetic eld in an electrically conducting medium at rest

  13. Calculation of levitation forces in permanent magnet-superconductor systems using finite element analysis

    NASA Astrophysics Data System (ADS)

    Camacho, D.; Mora, J.; Fontcuberta, J.; Obradors, X.

    1997-08-01

    In this paper we present calculations of levitation forces between a cylindrical permanent magnet and a cylindrical superconductor using a commercial finite element program. Force limits for zero field cooled and field cooled processes have been obtained using the Meissner effect and the perfect pinning hypothesis, respectively. Comparison of the experimentally determined forces with respect to these limits provides a simple estimation of the sample quality. The hysteretical behavior of the forces has been reproduced assuming a critical state model for the superconductor. Results are compared with experimental data. Excellent agreement has been found for forces measured after zero field cooled process thus allowing us to estimate the critical current of the samples. As a further exploitation of the software capabilities we have investigated the effects of the superconducting sample geometry and the effects of different strategies of flux conditioning to optimize the levitation forces.

  14. Calculation of levitation forces in permanent magnet-superconductor systems using finite element analysis

    SciTech Connect

    Camacho, D.; Mora, J.; Fontcuberta, J.; Obradors, X.

    1997-08-01

    In this paper we present calculations of levitation forces between a cylindrical permanent magnet and a cylindrical superconductor using a commercial finite element program. Force limits for zero field cooled and field cooled processes have been obtained using the Meissner effect and the perfect pinning hypothesis, respectively. Comparison of the experimentally determined forces with respect to these limits provides a simple estimation of the sample quality. The hysteretical behavior of the forces has been reproduced assuming a critical state model for the superconductor. Results are compared with experimental data. Excellent agreement has been found for forces measured after zero field cooled process thus allowing us to estimate the critical current of the samples. As a further exploitation of the software capabilities we have investigated the effects of the superconducting sample geometry and the effects of different strategies of flux conditioning to optimize the levitation forces. {copyright} {ital 1997 American Institute of Physics.}

  15. Morphology and Dynamics of Lithospheric Body Force Instabilities: Sheets, Drips and In-Between

    NASA Astrophysics Data System (ADS)

    Beall, A.; Moresi, L. N.

    2014-12-01

    Foundering of the Earth's lithosphere, and consequent energy and mass flux across the upper boundary layer and mantle interface, is driven locally by gravitational body forces. The related instabilities are usually classified as having sheet-like or drip-like morphologies. The former is associated with whole lithosphere (subduction) or delamination type foundering such as suggested for beneath the southern Sierra-Nevada and the Colorado Plateau, the latter to classic Rayleigh-Taylor instability below an upper layer, suggested to have occurred beneath the Tibetan Plateau and North Island, New Zealand. This dichotomy is non-trivial; classification of phenomena into one or the other is often debated and is difficult to infer from observables. The two morphologies are most likely end-members. Here I refine the dynamics driving morphology selection as a function of rheological lamination and boundary layer Rayleigh number in 2D and 3D, using the finite-element particle-in-cell code Underworld. I explore the influence of morphology on mass flux, topography and crustal deformation as well as deviation from classic 2D scalings. Additionally, tectonic displacement interference with instability development is discussed using basic 3D shear-box style models. By quantifying and describing the theoretical instability dynamics which could result in a plausible range of morphological expressions, I aim to build a general framework which can be paired to the discussion involving firstly, the recognition of varied styles of body force instabilities in the modern Earth and rock record and secondly, to what degree pattern selection impacts boundary layer mass and energy flux.

  16. Bilayer properties of giant magnetic liposomes formed by cationic pyridine amphiphile and probed by active deformation under magnetic forces.

    PubMed

    Petrichenko, O; Erglis, K; C?bers, A; Plotniece, A; Pajuste, K; Béalle, G; Ménager, Ch; Dubois, E; Perzynski, R

    2013-01-01

    We synthesize giant magnetic liposomes by a reverse-phase evaporation method (REV) using a new self-assembling Cationic Pyridine Amphiphile (CPA) derived from 1,4-dihydropyridine as liposome-forming agent and a magnetic ferrofluid based on ?-Fe(2)O(3) nanoparticles. Having in view the potential interest of CPA in targeted transport by magnetic forces, the mechanical elastic properties of such bilayers are here directly investigated in vesicles loaded with magnetic nanoparticles. Bending elastic modulus K(b) ? 0.2 to 5k(B)T and pre-stress ? ? 3.2 to 12.10(-6) erg/cm(2) are deduced from the under-field deformations of the giant magnetic liposomes. The obtained K(b) values are discussed in terms of A. Wurgers's theory. PMID:23359032

  17. Frequency domain multiplexing of force signals with application to magnetic resonance force microscopy

    E-print Network

    Leonardo, Degiorgi

    the noise performance by damping the mechanical oscil- lator using active feedback control.1,2 Depending.e., by putting each signal at a slightly different frequency within the bandwidth of the damped oscillator. We damped micromechanical cantilever, is used to detect multiple force signals simultaneously

  18. Structure formation by a fifth force: N-body versus linear simulations

    SciTech Connect

    Li Baojiu; Zhao Hongsheng

    2009-08-15

    We lay out the frameworks to numerically study the structure formation in both linear and nonlinear regimes in general dark-matter-coupled scalar field models, and give an explicit example where the scalar field serves as a dynamical dark energy. Adopting parameters of the scalar field which yield a realistic cosmic microwave background (CMB) spectrum, we generate the initial conditions for our N-body simulations, which follow the spatial distributions of the dark matter and the scalar field by solving their equations of motion using the multilevel adaptive grid technique. We show that the spatial configuration of the scalar field tracks well the voids and clusters of dark matter. Indeed, the propagation of scalar degree of freedom effectively acts as a fifth force on dark matter particles, whose range and magnitude are determined by the two model parameters ({mu},{gamma}), local dark matter density as well as the background value for the scalar field. The model behaves like the {lambda}CDM paradigm on scales relevant to the CMB spectrum, which are well beyond the probe of the local fifth force and thus not significantly affected by the matter-scalar coupling. On scales comparable or shorter than the range of the local fifth force, the fifth force is perfectly parallel to gravity and their strengths have a fixed ratio 2{gamma}{sup 2} determined by the matter-scalar coupling, provided that the chameleon effect is weak; if on the other hand there is a strong chameleon effect (i.e., the scalar field almost resides at its effective potential minimum everywhere in the space), the fifth force indeed has suppressed effects in high density regions and shows no obvious correlation with gravity, which means that the dark-matter-scalar-field coupling is not simply equivalent to a rescaling of the gravitational constant or the mass of the dark matter particles. We show these spatial distributions and (lack of) correlations at typical redshifts (z=0,1,5.5) in our multigrid million-particle simulations. The viable parameters for the scalar field can be inferred on intermediate or small scales at late times from, e.g., weak lensing and phase space properties, while the predicted Hubble expansion and linearly simulated CMB spectrum are virtually indistinguishable from the standard {lambda}CDM predictions.

  19. Suppression of magnetic levitation force in melt-textured YBa2Cu3O7-x superconductors by a transverse AC magnetic field

    NASA Astrophysics Data System (ADS)

    Rudnev, I. A.; Ermolaev, Yu S.

    2008-02-01

    We have studied experimentally the influence of transverse ac magnetic fields on the levitation force arising between a permanent NdFeB magnet and a bulk melt-textured HTSC YBCO superconducting sample. The axes of superconducting disc and cylindrical magnet were coinciding while the transverse ac magnetic field generated by resistive coil was directed parallel to surface of a disc i.e., perpendicular to the disc axis. We found that application of both impulse and alternative transverse magnetic fields results in suppression of the value of levitation force and its relaxation rate. Namely, the variable magnetic field with amplitude 12 mT, that approximately in 20 times is less than field of a constant magnet, causes suppression of force more than twice. Monotonous behavior of value of levitation force reduction with the increase in transverse magnetic field amplitude was observed. The possible origin of observed phenomenon is discussed.

  20. Fine-tuning of magnetic and microfluidic viscous forces for specific magnetic bead-based immunocomplex formation

    NASA Astrophysics Data System (ADS)

    Cornaglia, M.; Tekin, H. C.; Lehnert, T.; Gijs, M. A. M.

    2013-08-01

    We investigate the working principle of a novel type of microfluidic sandwich immunoassay, as used for the detection of biomarkers. The heterogeneous assay is based on the specific interactions between an array of functionalized superparamagnetic beads and a flow of secondary superparamagnetic beads that carry the antigens and are simultaneously used as detection labels. We identify the main forces governing the immunoassay performance and develop a combined finite element method/analytical model to predict and control these forces. The clue for the improved assay specificity is in the fine-tuning of inter-bead magnetic dipolar and microfluidic viscous forces, which allows strongly reducing non-specific interactions, while enhancing the specific formation of immunocomplexes. We exploit our theoretical model to explain the enhanced sensitivity of magnetic bead-based immunoassay experiments performed in microfluidic chips.

  1. Detection of secondary phases in duplex stainless steel by magnetic force microscopy and scanning Kelvin probe force microscopy

    SciTech Connect

    Ramírez-Salgado, J.; Domínguez-Aguilar, M.A.; Castro-Domínguez, B.; Hernández-Hernández, P.; Newman, R.C.

    2013-12-15

    The secondary phase transformations in a commercial super duplex stainless steel were investigated by micro-chemical analyses and high resolution scanning probe microscopy. Energy dispersive X-ray and electron probe detected ferrite and austenite as well as secondary phases in unetched aged duplex stainless steel type 25Cr-7Ni-3Mo. Volta potential indicated that nitride and sigma appeared more active than ferrite, while secondary austenite and austenite presented a nobler potential. Reversal order in nobility is thought to be attributable to the potential ranking provided by oxide nature diversity as a result of secondary phase surface compositions on steel. After eutectoid transformation, secondary austenite was detected by electron probe microanalysis, whereas atomic force microscopy distinguished this phase from former austenite by image contrast. Magnetic force microscopy revealed a “ghosted” effect on the latter microstructure probably derived from metal memory reminiscence of mechanical polishing at passivity and long range magnetic forces of ferrite phase. - Highlights: • Nobility detection of secondary phases by SKPFM in DSS particles is not a straightforward procedure. • As Volta potential and contrast are not always consistent SKPFM surface oxides is thought played an important role in detection. • AFM distinguished secondary austenite from former austenite by image contrast though SEM required EPMA.

  2. Fluidic assisted thin-film device heterogeneous integration: Surface tension as driving force and magnetic as guiding force

    NASA Astrophysics Data System (ADS)

    Xiao, Jing; Ray Chaudhuri, Ritesh; Seo, Sang-Woo

    2015-10-01

    This paper demonstrates a fluidic assisted heterogeneous integration of optical thin-film device using surface tension as driving force and magnetic field as guiding force. Thin-film devices can be auto-aligned and integrated using surface tension onto their predesigned locations on a host substrate due to minimization of interfacial energy. By inserting a layer of nickel (Ni) into device metallization step, magnetic force was employed to increase mobility and contact probability of thin-film devices to their binding sites on the host substrate. A thin-film gallium arsenide (GaAs) inverted Metal-Semiconductor-Metal (MSM) photodetector (PD) has been successfully integrated onto a silicon host substrate with the proposed integration approach. The influence of the nickel layer to the PD performance was also investigated. Due to the self-assembly capability and thin-film format of the device, the proposed method has potential for wafer-scale implementation and is compatible with the matured silicon-based CMOS technology. This is a critical step towards a scalable manufacturing process to create advanced photonic/optoelectronic systems that are low-cost, compact, high performance, and complex in multi-material functionality.

  3. Magnetic Evidence for a Partially Differentiated Carbonaceous Chondrite Parent Body

    E-print Network

    Shuster, David L.

    The textures of chondritic meteorites demonstrate that they are not the products of planetary melting processes. This has long been interpreted as evidence that chondrite parent bodies never experienced large-scale melting. ...

  4. A body-force based method to generate supersonic equilibrium turbulent boundary layer profiles

    NASA Astrophysics Data System (ADS)

    Waindim, M.; Gaitonde, D. V.

    2016-01-01

    We further develop a simple counterflow body force-based approach to generate an equilibrium spatially developing turbulent boundary layer suitable for Direct Numerical Simulations (DNS) or Large Eddy Simulations (LES) of viscous-inviscid interactions. The force essentially induces a small separated region in an incoming specified laminar boundary layer. The resulting unstable shear layer then transitions and breaks down to yield the desired unsteady profile. The effects of wall thermal conditions are explored to demonstrate the capability of the method for both fixed wall and adiabatic wall conditions. We then describe an efficient method to select parameters that ensure transition by examining precursor signatures using generalized stability variables. These precursors are shown to be evident in a computational domain spanning only a small region around the trip and can also be detected using 2D simulations. Finally, the method is tested for different Mach numbers ranging from 1.7 to 2.9, with emphasis on flow field surveys, Reynolds stresses, and energy spectra. These results provide guidance on boundary conditions for desired boundary layer thickness at each Mach number. The consequences of using a much lower Reynolds number in computation relative to experiment are evident at the higher Mach number, where a self sustaining turbulent boundary layer is more difficult to obtain.

  5. Force measurements of a magnetic micro actuator proposed for a microvalve array

    NASA Astrophysics Data System (ADS)

    Chang, Pauline J.; Chang, Frank W.; Yuen, Michelle C.; Otillar, Robert; Horsley, David A.

    2014-03-01

    Low-cost, easily-fabricated and power-efficient microvalves are necessary for many microfluidic lab-on-a-chip applications. In this study, we present a simple, low-power, scalable, CMOS-compatible magnetic actuator for microvalve applications composed of a paramagnetic bead as the ball valve over a picoliter reaction well etched into a silicon substrate. The paramagnetic bead, composed of either pure FeSi or magnetite in a SiO2 matrix, is actuated by the local magnetic field gradient generated by a microcoil in an aqueous environment, and the reaction well is situated at the microcoil center. A permanent magnet beneath the microvalve device provides an external magnetic biasing field that magnetizes the bead, enabling bidirectional actuation and reducing the current required to actuate the bead to a level below 10 mA. The vertical and radial magnetic forces exerted on the bead by the microcoil were measured for both pure FeSi and composite beads and agree well with the predictions of 2D axisymmetric finite element method models. Vertical forces were within a range of 13-80 nN, and radial forces were 11-60 nN depending on the bead type. The threshold current required to initiate bead actuation was measured as a function of bead diameter and is found to scale inversely with volume for small beads, as expected based on the magnetic force model. To provide an estimate of the stiction force acting between the bead and the passivation layer on the substrate, repeated actuation trials were used to study the bead throw distance for substrates coated with silicon dioxide, Parylene-C, and photoresist. The stiction observed was lowest for a photoresist-coated substrate, while silicon dioxide and Parylene-C coated substrates exhibited similar levels of stiction.

  6. Characteristics and computer model simulation of magnetic damping forces in maglev systems

    NASA Astrophysics Data System (ADS)

    He, J. L.; Rote, D. M.; Chen, S. S.

    1994-05-01

    This report discusses the magnetic damping force in electrodynamic suspension (EDS) maglev systems. The computer model simulations, which combine electrical system equations with mechanical motion equations on the basis of dynamic circuit theory, were conducted for a loop-shaped coil guideway. The intrinsic damping characteristics of the EDS-type guideway are investigated, and the negative damping phenomenon is confirmed by the computer simulations. The report also presents a simple circuit model to aid in understanding damping-force characteristics.

  7. Effect of size on levitation force in a magnet/superconductor system

    SciTech Connect

    Yang, Z.J.; Hull, J.R.

    1996-03-01

    We consider a model system consisting of an infinitely long magnetic dipole line placed symmetrically above an infinitely long superconducting strip. Using the Meissner effect of superconductors, we derive analytical expressions of the levitation forces acting on the dipole line. At lowest-order approximation, we discuss the possible application of our model system to estimate the upper limit of the levitation forces in some magnetic bearing systems. In one example, the model correctly calculated the vertical vibration frequency of an experimental superconducting bearing.

  8. Practical limits to the performance of magnetic bearings: Peak force, slew rate, and displacement sensitivity

    NASA Technical Reports Server (NTRS)

    Maslen, E.; Hermann, P.; Scott, M.; Humphris, R. R.

    1993-01-01

    Magnetic bearings are subject to performance limits which are quite different from those of conventional bearings. These are due in part to the inherent nonlinearity of the device and in part to its electrical nature. Three important nonideal behaviors are presented: peak force capacity, force slew rate limitation, and sensitivity to rotor motion at large displacements. The problem of identifying the dynamic requirements of a magnetic bearing when used to support a known structure subject to known loads is discussed in the context of these limitations. Several simple design tools result from this investigation.

  9. Magnetic Resonance Force Microscopy of paramagnetic electron spins at millikelvin temperatures

    E-print Network

    A. Vinante; G. Wijts; O. Usenko; L. Schinkelshoek; T. H. Oosterkamp

    2011-12-07

    Magnetic Resonance Force Microscopy (MRFM) is a powerful technique to detect a small number of spins that relies on force-detection by an ultrasoft magnetically tipped cantilever and selective magnetic resonance manipulation of the spins. MRFM would greatly benefit from ultralow temperature operation, because of lower thermomechanical noise and increased thermal spin polarization. Here, we demonstrate MRFM operation at temperatures as low as 30 mK, thanks to a recently developed SQUID-based cantilever detection technique which avoids cantilever overheating. In our experiment, we detect dangling bond paramagnetic centers on a silicon surface down to millikelvin temperatures. Fluctuations of such kind of defects are supposedly linked to 1/f magnetic noise and decoherence in SQUIDs as well as in several superconducting and single spin qubits. We find evidence that spin diffusion plays a key role in the low temperature spin dynamics.

  10. Magnetic Resonance Force Microscopy of paramagnetic electron spins at millikelvin temperatures

    E-print Network

    Vinante, A; Usenko, O; Wijts, G; Oosterkamp, T H

    2011-01-01

    Magnetic Resonance Force Microscopy (MRFM) is a powerful technique to detect a small number of spins that relies on force-detection by an ultrasoft magnetically tipped cantilever and selective magnetic resonance manipulation of the spins. MRFM would greatly benefit from ultralow temperature operation, because of lower thermomechanical noise and increased thermal spin polarization. Here, we demonstrate MRFM operation at temperatures as low as 30 mK, thanks to a recently developed SQUID-based cantilever detection technique which avoids cantilever overheating. In our experiment, we detect dangling bond paramagnetic centers on a silicon surface down to millikelvin temperatures. Fluctuations of such kind of defects are supposedly linked to 1/$f$ magnetic noise and decoherence in SQUIDs and in several superconducting and single spin qubits. We find evidence that spin diffusion plays a key role in the low temperature spin dynamics.

  11. An investigation on the body force modeling in a lattice Boltzmann BGK simulation of generalized Newtonian fluids

    NASA Astrophysics Data System (ADS)

    Farnoush, Somayeh; Manzari, Mehrdad T.

    2014-12-01

    Body force modeling is studied in the Generalized Newtonian (GN) fluid flow simulation using a single relaxation time lattice Boltzmann (LB) method. First, in a shear thickening Poiseuille flow, the necessity for studying body force modeling in the LB method is explained. Then, a parametric unified framework is constructed for the first time which is composed of a parametric LB model and its associated macroscopic dual equations in both steady state and transient simulations. This unified framework is used to compare the macroscopic behavior of different forcing models. Besides, using this unified framework, a new forcing model for steady state simulations is devised. Finally, by solving a number of test cases it is shown that numerical results confirm the theoretical arguments presented in this paper.

  12. Confinement of Plasma along Shaped Open Magnetic Fields from the Centrifugal Force of Supersonic Plasma Rotation

    SciTech Connect

    Teodorescu, C.; Young, W. C.; Swan, G. W. S.; Ellis, R. F.; Hassam, A. B.; Romero-Talamas, C. A.

    2010-08-20

    Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic ExB rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

  13. Electric contributions to magnetic force microscopy response from graphene and MoS{sub 2} nanosheets

    SciTech Connect

    Li, Lu Hua Chen, Ying

    2014-12-07

    Magnetic force microscopy (MFM) signals have recently been detected from whole pieces of mechanically exfoliated graphene and molybdenum disulfide (MoS{sub 2}) nanosheets, and magnetism of the two nanomaterials was claimed based on these observations. However, non-magnetic interactions or artefacts are commonly associated with MFM signals, which make the interpretation of MFM signals not straightforward. A systematic investigation has been done to examine possible sources of the MFM signals from graphene and MoS{sub 2} nanosheets and whether the MFM signals can be correlated with magnetism. It is found that the MFM signals have significant non-magnetic contributions due to capacitive and electrostatic interactions between the nanosheets and conductive cantilever tip, as demonstrated by electric force microscopy and scanning Kevin probe microscopy analyses. In addition, the MFM signals of graphene and MoS{sub 2} nanosheets are not responsive to reversed magnetic field of the magnetic cantilever tip. Therefore, the observed MFM response is mainly from electric artefacts and not compelling enough to correlate with magnetism of graphene and MoS{sub 2} nanosheets.

  14. A dynamic magnetic tension force as the cause of failed solar eruptions.

    PubMed

    Myers, Clayton E; Yamada, Masaaki; Ji, Hantao; Yoo, Jongsoo; Fox, William; Jara-Almonte, Jonathan; Savcheva, Antonia; DeLuca, Edward E

    2015-12-24

    Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun's corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has not yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. Here we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such 'failed torus' events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. This magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events. PMID:26701052

  15. Magnetic force microscopy study of electron-beam-patterned soft permalloy particles: Technique and magnetization behavior

    E-print Network

    Grütter, Peter

    field Hs , while at the higher field Ha , the magnetic moments form a reversed single domain state of small magnetic elements are crucial tests of micromagnetic codes and lead to a better understanding

  16. A new approach to scaffold fixation by magnetic forces: Application to large osteochondral defects.

    PubMed

    Russo, Alessandro; Shelyakova, Tatiana; Casino, Daniela; Lopomo, Nicola; Strazzari, Alessandro; Ortolani, Alessandro; Visani, Andrea; Dediu, Valentin; Marcacci, Maurilio

    2012-11-01

    Scaffold fixation represents one of the most serious challenges in osteochondral defect surgery. Indeed, the fixation should firmly hold the scaffold in the implanted position as well as it should guaranty stable bone/scaffold interface for efficient tissue regeneration. Nonetheless successful results have been achieved for small defect repair, the fixation remains really problematic for large defects, i.e. defects with areas exceeding 2cm(2). This paper advances an innovative magnetic fixation approach based on application of magnetic scaffolds. Finite element modeling was exploited to investigate the fixation efficiency. We considered three magnetic configurations: (1) external permanent magnet ring placed around the leg near the joint; (2) four small permanent magnet pins implanted in the bone underlying the scaffold; (3) four similarly implanted stainless steel pins which magnetization was induced by the external magnet. It was found that for most appropriate magnetic materials and optimized magnet-scaffold positioning all the considered configurations provide a sufficient scaffold fixation. In addition to fixation, we analyzed the pressure induced by magnetic forces at the bone/scaffold interface. Such pressure is known to influence significantly the bone regeneration and could be used for magneto-mechanical stimulation. PMID:22381395

  17. First Use of Synoptic Vector Magnetograms for Global Nonlinear, Force-Free Coronal Magnetic Field Models

    NASA Technical Reports Server (NTRS)

    Tadesse, T.; Wiegelmann, T.; Gosain, S.; MacNeice, P.; Pevtsov, A. A.

    2014-01-01

    Context. The magnetic field permeating the solar atmosphere is generally thought to provide the energy for much of the activity seen in the solar corona, such as flares, coronal mass ejections (CMEs), etc. To overcome the unavailability of coronal magnetic field measurements, photospheric magnetic field vector data can be used to reconstruct the coronal field. Currently, there are several modelling techniques being used to calculate three-dimensional field lines into the solar atmosphere. Aims. For the first time, synoptic maps of a photospheric-vector magnetic field synthesized from the vector spectromagnetograph (VSM) on Synoptic Optical Long-term Investigations of the Sun (SOLIS) are used to model the coronal magnetic field and estimate free magnetic energy in the global scale. The free energy (i.e., the energy in excess of the potential field energy) is one of the main indicators used in space weather forecasts to predict the eruptivity of active regions. Methods. We solve the nonlinear force-free field equations using an optimization principle in spherical geometry. The resulting threedimensional magnetic fields are used to estimate the magnetic free energy content E(sub free) = E(sub nlfff) - E(sub pot), which is the difference of the magnetic energies between the nonpotential field and the potential field in the global solar corona. For comparison, we overlay the extrapolated magnetic field lines with the extreme ultraviolet (EUV) observations by the atmospheric imaging assembly (AIA) on board the Solar Dynamics Observatory (SDO). Results. For a single Carrington rotation 2121, we find that the global nonlinear force-free field (NLFFF) magnetic energy density is 10.3% higher than the potential one. Most of this free energy is located in active regions.

  18. Test of response linearity for magnetic force microscopy data R. Yongsunthon and E. D. Williamsa)

    E-print Network

    Williams, Ellen D.

    near defects, constrictions, and corners in current-carrying lines may play a role in electromigration-induced failure.1­3 Various groups have previously used magnetic force microscopy MFM to image current-carrying lines, in applications including detection of conducting paths for the purpose of IC failure analysis,4

  19. Magnetic levitation force and penetration depth in type-II superconductors

    SciTech Connect

    Xu, J.H.; Miller, J.H. Jr.; Ting, C.S. )

    1995-01-01

    The superconducting levitation force [ital F] acting on a magnet placed above a type-II superconductor in both Meissner and mixed states is calculated as a function of temperature, based upon the London model. A simple relationship between the levitation force and the London penetration depth [lambda] is found. In particular, in the limit of [ital a]/[lambda][much gt]1, where [ital a] is the separation between the magnet and the superconductor, [ital F] varies linearly with [lambda], regardless of the shape of the magnet. The temperature dependences of [lambda] and [ital F] are examined for various superconducting pairing states, including [ital s]-wave, [ital d]-wave, and [ital s]+[ital id] states. It is found that, at low temperatures, both [lambda] and [ital F] show an exponential temperature dependence for [ital s]-wave, linear-[ital T] for [ital d]-wave, and [ital T][sup 2] dependence in a wide low-temperature range for the [ital s]+[ital id] state with a dominant [ital d]-wave component. The magnetic force microscope (MFM) is proposed to accurately measure the temperature-dependent levitation force. It is shown that the microscopic size of the MFM tip enables one to obtain the intrinsic temperature-dependent penetration depth of a single grain, in spite of the overall quality of the superconducting sample.

  20. Magnetism of Minor Bodies in the Solar System: From 433 Eros, passing Braille, Steins, and Lutetia towards Churyumov-Gerasimenko and 1999 JU3.

    NASA Astrophysics Data System (ADS)

    Hercik, David; Auster, Hans-Ulrich; Heinisch, Philip; Richter, Ingo; Glassmeier, Karl-Heinz

    2015-04-01

    Minor bodies in the solar system, such as asteroids and comets, are important sources of information for our knowledge of the solar system formation. Besides other aspects, estimation of a magnetization state of such bodies might prove important in understanding the early aggregation phases of the protoplanetary disk, showing the level of importance of the magnetic forces in the processes involved. Meteorites' magnetization measurements suggest that primitive bodies consist of magnetized material. However, space observations from various flybys give to date diverse results for a global magnetization estimation. The flybys at Braille and Gaspra indicate possible higher magnetization (~ 10-3 Am2/kg), while flybys at Steins and Lutetia show no significant values in the global field change illustrating low global magnetization. Furthermore, the interpretation of remote (during flybys) measurements is very difficult. For correct estimates on the local magnetization one needs (in the best case) multi-point surface measurements. Single point observation has been done by NEAR-Shoemaker on 433 Eros asteroid, revealing no signature in magnetic field that could have origin in asteroid magnetization. Similar results, no magnetization observed, have been provided by evaluation of recent data from ROMAP (Philae lander) and RPC-MAG (Rosetta orbiter) instruments from comet 67P/Churyumov-Gerasimenko. The ROMAP instrument provided measurements from multiple points of the cometary surface as well as data along ballistic path between multiple touchdowns, which support the conclusion of no global magnetization. However, even in case of the in-situ on surface observations the magnetization estimate has a limiting spatial resolution that is dependent on the distance from the surface (~ 50 cm in case of ROMAP). To get information about possible smaller magnetized grains distribution and magnetization strength, the sensor shall be placed as close as possible to the surface. For such observations the next ideal candidate mission is Hayabusa-II with its Mascot lander equipped with fluxgate magnetometer. The small-sized lander shall deliver the magnetometer within centimeters from the surface, providing measurements on multiple points thanks to a hopping ability. The mission has been recently launched (December 2014) and is aiming to a C-type asteroid 1999 JU3 to reach it in 2018. The results will hopefully add some piece of information to the still unclear question of minor solar system bodies magnetization.

  1. Temperature properties of the alignment dependence of coercive force decrease ratio and the angular dependence of coercive force in Nd-Fe-B sintered magnets

    NASA Astrophysics Data System (ADS)

    Matsuura, Yutaka; Kitai, Nobuyuki; Ishii, Rintaro; Natsumeda, Mitsutoshi; Hoshijima, Jun; Kuniyoshi, Futoshi

    2016-01-01

    The temperature dependence of the coercive force decrease ratio for aligned magnets was investigated from room temperature (296 K) to 473 K. The temperature properties of the angular dependence of the coercive force were also measured from room temperature to 413 K, for comparison against the coercive force decrease ratio. From the temperature dependence of the coercive force decrease ratio of magnets with different alignment, it was found that the coercive force decrease ratio decreased as temperature increased until becoming close to the calculation results that were obtained from the Gaussian distribution for Nd2Fe14B grain alignment and from the postulation that every grain follows the Kondorskii law or the 1/cos ? law. When we compared the angle of the magnetization reverse area obtained from these calculation results and the angle of the reverse magnetization area calculated from the experimental data of the coercive force decrease ratio, it was found that this latter expanded to 30° for Nd13.48B5.76Co0.55Febal. having 0.95 alignment, at room temperature, from 14° that was the calculated angle obtained from the Gaussian distribution and the Kondorskii law. The angular dependence of coercive force of this magnet at room temperature agrees well with the calculation, when ?=31°, which is 30° for the reversed magnetization area, is applied as the standard deviation of Nd2Fe14B grain alignment distribution. For Nd12.75Dy0.84B5.81Co0.55Febal. with 0.96 for alignment, the reverse magnetization area also expanded to 36° and agreed well with the calculation result applied ?=44°, which has 36° for the reverse magnetization area. It was also found that, as temperature increased, the angle of the reverse magnetization area obtained from the experimental data shrunk towards the calculated angle. When we apply these results to the temperature properties of the angular dependence of the coercive force, it seems that the calculated angular dependence of the coercive force can qualitatively and reasonably explain these temperature properties. These results strongly suggest that the magnetic domain walls are strongly pinned at tilted grains. It also suggests that, when such magnetic domain walls are de-pinned from their pinning sites, they leap through several grains with weak pinning force, which determines the coercive force.

  2. Self-Assembled DNA Structures for Molecular Force Measurement: A Magnetically Actuated Approach

    NASA Astrophysics Data System (ADS)

    Armstrong, M.; Lauback, S.; Miller, C.; Peace, C.; Castro, C.; Sooryakumar, R.

    2015-03-01

    Understanding molecular forces is important to comprehend many of the underlying properties of molecular machines and biological processes. The relevant forces in these cases often lie in the picoNewton range, and thus experiments on individual biomolecules must integrate techniques capable of measuring such forces. A mechanical system to measure molecular forces associated with interacting DNA strands is being developed by using self-assembled DNA nanostructures and super-paramagnetic beads. The DNA nanostructure consists of single-stranded DNA molecules which can be folded into a precise compact geometry using hundreds of short oligonucleotides, i.e., staples, via programmed molecular self-assembly. These nanostructures can be polymerized into micron-scale filaments. By functionalizing the filament ends with bispecific conjugate staples, the structure can be attached to a surface as well as labeled with magnetic beads in order to apply a force on the system. External magnetic fields provide the means to maneuver and manipulate the magnetically labeled DNA structures. Preliminary findings associated with the DNA constructs and their manipulation lay the groundwork to establish real-time control of DNA nanodevices with micromanipulation.

  3. Estimation of stress corrosion cracking sensitivity of type 304 stainless steel by magnetic force microscope

    NASA Astrophysics Data System (ADS)

    Takaya, Shigeru; Suzuki, Takayuki; Matsumoto, Yoshihiro; Demachi, Kazuyuki; Uesaka, Mitsuru

    2004-04-01

    An application of a magnetic force microscope (MFM) to the measurement of the chromium depleted regions of type 304 stainless steel is proposed to enable more effective evaluation of the material sensitization to stress corrosion cracking than the conventional methods. The MFM images of sensitized materials show that the magnetizations are induced along grain boundaries by the chromium depletion. The dependence of the magnetization on the sensitization condition conforms to the expected one from the behavior of chromium depletion. Furthermore, the phase identification was performed by electron backscattered pattern technique to reveal the magnetization mechanism due to sensitization. Then, it was found that the magnetization is caused by the transformation from austenite phase to martensite phase. From the discussion on the temperature at which martensitic transformation starts, we see that it seems to be possible to detect regions where the chromium concentration is under 14% by using an MFM.

  4. GENERATION OF SEED MAGNETIC FIELD AROUND FIRST STARS: EFFECTS OF RADIATION FORCE

    SciTech Connect

    Ando, Masashi; Doi, Kentaro; Susa, Hajime E-mail: mn921009@center.konan-u.ac.j

    2010-06-20

    We investigate seed magnetic field generation in the early universe by the radiation force of first stars. In a previous study with the steady assumption, large amplitudes ({approx}10{sup -15} G for first stars, {approx}10{sup -11} G for QSOs) are predicted. In this study, we formulate this issue in an unsteady framework. Then, we consider a specific model of magnetic field generation around a very massive first star. Consequently, we (1) find that the steady assumption is not valid in realistic situations and (2) obtain a much smaller magnetic field strength than that predicted by Langer et al. In addition, we find that the momentum transfer process during photoionization is more important than Thomson scattering. The resultant magnetic flux density around the first star is {approx_lt}10{sup -19} G. This seed magnetic field will not affect subsequent star formation in the neighborhood of first stars.

  5. ON THE FORCE-FREE NATURE OF PHOTOSPHERIC SUNSPOT MAGNETIC FIELDS AS OBSERVED FROM HINODE (SOT/SP)

    SciTech Connect

    Tiwari, Sanjiv Kumar

    2012-01-01

    A magnetic field is force-free if there is no interaction between it and the plasma in the surrounding atmosphere, i.e., electric currents are aligned with the magnetic field, giving rise to zero Lorentz force. The computation of various magnetic parameters, such as magnetic energy (using the virial theorem), gradient of twist of sunspot magnetic fields (computed from the force-free parameter {alpha}), and any kind of extrapolation, heavily hinges on the force-free approximation of the photospheric sunspot magnetic fields. Thus, it is of vital importance to inspect the force-free behavior of sunspot magnetic fields. The force-free nature of sunspot magnetic fields has been examined earlier by some researchers, ending with incoherent results. Accurate photospheric vector field measurements with high spatial resolution are required to inspect the force-free nature of sunspots. For this purpose, we use several vector magnetograms of high spatial resolution obtained from the Solar Optical Telescope/Spectro-Polarimeter on board Hinode. Both the necessary and sufficient conditions for force-free nature are examined by checking the global and local nature of equilibrium magnetic forces over sunspots. We find that sunspot magnetic fields are not very far from the force-free configuration, although they are not completely force-free on the photosphere. The umbral and inner penumbral fields are more force-free than the middle and outer penumbral fields. During their evolution, sunspot magnetic fields are found to maintain their proximity to force-free field behavior. Although a dependence of net Lorentz force components is seen on the evolutionary stages of the sunspots, we do not find a systematic relationship between the nature of sunspot magnetic fields and the associated flare activity. Further, we examine whether the fields at the photosphere follow linear or nonlinear force-free conditions. After examining this in various complex and simple sunspots, we conclude that, in either case, photospheric sunspot magnetic fields are closer to satisfying the nonlinear force-free field approximation.

  6. Magnetic force microscopy measurements in external magnetic fields—comparison between coated probes and an iron filled carbon nanotube probe

    NASA Astrophysics Data System (ADS)

    Wolny, F.; Mühl, T.; Weissker, U.; Leonhardt, A.; Wolff, U.; Givord, D.; Büchner, B.

    2010-07-01

    We performed magnetic force microscopy (MFM) measurements in external magnetic fields parallel to the sample plane to qualitatively study their effect on the magnetization of different kinds of MFM probes. As a test structure we used an array of rectangular ferromagnetic thin film elements aligned with the external magnetic field direction. MFM images were taken while the field was increased stepwise to monitor the onset of a tilt in the MFM probe magnetization. Three different probes were investigated: a conventional pyramidal probe coated with 40 nm of CoCrTa, a coated high aspect ratio MFM probe, and a MFM probe based on an iron filled carbon nanotube (FeCNT). The results show that the magnetization of the pyramidal probe is only stable in in-plane fields of up to ˜60 mT, in larger fields a considerable in-plane component of the tip magnetization is observed. This makes it difficult to distinguish the effect of the external field on the sample from those on the MFM probe. The coated high aspect ratio probe is at first stable up to ˜200 mT and then shows a history dependent behavior, in the second sweep the onset of the magnetization tilt is already visible at ˜100 mT. With the FeCNT probe, no tilt of the probe magnetization could be observed in in-plane fields up to the experimental limit of 230 mT. Due to the large shape anisotropy of the enclosed iron nanowire its direction of magnetization stays mainly oriented along the long axis even in moderate fields that deviate from this easy axis. Consequently, this probe is best suited for MFM measurements in external fields.

  7. Effects of Rigid Body Collisions and Tide-Forced Drift on Large Tabular Icebergs of the Antarctic

    E-print Network

    Macayeal, Douglas R.

    1 Effects of Rigid Body Collisions and Tide-Forced Drift on Large Tabular Icebergs of the Antarctic ICEBERGS #12;2 Abstract. Following the calving of an iceberg from an ice shelf, many collisions between the new iceberg and the remaining shelf can occur as the iceberg responds to time-varying oceanic

  8. Radiation pressure excitation of Low Temperature Atomic Force & Magnetic Force Microscope (LT-AFM/MFM) for Imaging

    NASA Astrophysics Data System (ADS)

    Karci, Ozgur; Celik, Umit; Oral, Ahmet; NanoMagnetics Instruments Ltd. Team; Middle East Tech Univ Team

    2015-03-01

    We describe a novel method for excitation of Atomic Force Microscope (AFM) cantilevers by means of radiation pressure for imaging in an AFM for the first time. Piezo excitation is the most common method for cantilever excitation, but it may cause spurious resonance peaks. A fiber optic interferometer with 1310 nm laser was used both to measure the deflection of cantilever and apply a force to the cantilever in a LT-AFM/MFM from NanoMagnetics Instruments. The laser power was modulated at the cantilever`s resonance frequency by a digital Phase Lock Loop (PLL). The force exerted by the radiation pressure on a perfectly reflecting surface by a laser beam of power P is F = 2P/c. We typically modulate the laser beam by ~ 800 ?W and obtain 10nm oscillation amplitude with Q ~ 8,000 at 2.5x10-4 mbar. The cantilever's stiffness can be accurately calibrated by using the radiation pressure. We have demonstrated performance of the radiation pressure excitation in AFM/MFM by imaging a hard disk sample between 4-300K and Abrikosov vortex lattice in BSCCO single crystal at 4K to for the first time.

  9. High-force NdFeB-based magnetic tweezers device optimized for microrheology experiments

    SciTech Connect

    Lin Jun; Valentine, Megan T.

    2012-05-15

    We present the design, calibration, and testing of a magnetic tweezers device that employs two pairs of permanent neodymium iron boron magnets surrounded by low-carbon steel focusing tips to apply large forces to soft materials for microrheology experiments. Our design enables the application of forces in the range of 1-1800 pN to {approx}4.5 {mu}m paramagnetic beads using magnet-bead separations in the range of 0.3-20 mm. This allows the use of standard coverslips and sample geometries. A high speed camera, custom LED-based illumination scheme, and mechanically stabilized measurement platform are employed to enable the measurement of materials with viscoelastic moduli as high as {approx}1 kPa.

  10. Levitation force and trapped magnetic field of multi-grain YBCO bulk superconductors

    NASA Astrophysics Data System (ADS)

    Choi, J. S.; Park, S. D.; Jun, B. H.; Han, Y. H.; Jeong, N. H.; Kim, B. G.; Sohn, J. M.; Kim, C. J.

    2008-09-01

    A levitation force (LF), attractive force (AF) and trapped magnetic field (TMF) at 77 K of the multi-seeded melt processed (MSMG) bulk samples (single grain to five grain) were studied. The LF and TMF values of the MSMG-processed samples, cooled by both field cooling and zero-field cooling method, were smaller than that of a single grain sample, depending on the number of a grain. The trapped magnetic field analysis showed the magnetic fields were easily penetrated through the grain boundaries of multi-grain samples, because of the weak connection of (1 0 0)/(1 0 0) junctions. The poorly connected grain boundaries are thought to be the cause for the low LF and TMF values of the multi-grain samples.

  11. Attosecond Electro-Magnetic Forces Acting on Metal Nanospheres Induced By Relativistic Electrons

    NASA Astrophysics Data System (ADS)

    Lagos, M. J.; Batson, P. E.; Reyes-Coronado, A.; Echenique, P. M.; Aizpurua, J.

    2014-03-01

    Swift electron scattering near nanoscale materials provides information about light-matter behavior, including induced forces. We calculate time-dependent electromagnetic forces acting on 1-1.5 nm metal nanospheres induced by passing swift electrons, finding both impulse-like and oscillatory response forces. Initially, impulse-like forces are generated by a competition between attractive electric forces and repulsive magnetic forces, lasting a few attoseconds (5-10 as). Oscillatory, plasmonic response forces take place later in time, last a few femtoseconds (1- 5 fs), and apparently rely on photon emission by decay of the electron-induced surface plasmons. A comparison of the strength of these two forces suggests that the impulse-like behavior dominates the process, and can transfer significant linear momentum to the sphere. Our results advance understanding of the physics behind the observation of both attractive and repulsive behavior of gold nano-particles induced by electron beams in aberration-corrected electron microscopy. Work supported under DOE, Award # DE-SC0005132, Basque Gov. project ETORTEK inano, Spanish Ministerio de Ciencia e Innovacion, No. FIS2010-19609-C02-01.

  12. Experimental study of the two-body spin-orbit force

    E-print Network

    G. Burgunder; O. Sorlin; F. Nowacki; S. Giron; F. Hammache; M. Moukaddam; N. De S er eville; D. Beaumel; L. C aceres; E. Cl ément; G. Duchêne; J. P. Ebran; B. Fernandez-Dominguez; F. Flavigny; S. Franchoo; J. Gibelin; A. Gillibert; S. Gr évy; J. Guillot; V. Lapoux; A. Lepailleur; I. Matea; A. Matta; L. Nalpas; A. Obertelli; T. Otsuka; J. Pancin; A. Poves; R. Raabe; J. A. Scarpaci; I. Stefan; C. Stodel; T. Suzuki; J. C. Thomas

    2014-01-08

    Energies and spectroscopic factors of the first $7/2^-$, $3/2^-$, $1/2^-$ and $5/2^-$ states in the $^{35}$Si$_{21}$ nucleus were determined by means of the (d,p) transfer reaction in inverse kinematics at GANIL using the MUST2 and EXOGAM detectors. By comparing the spectroscopic information on the $^{35}$Si and $^{37}$S isotones, a reduction of the $p_{3/2} - p_{1/2}$ spin-orbit splitting by about 25% is proposed, while the $f_{7/2} -f_{5/2}$ spin-orbit splitting seems to remain constant. These features, derived after having unfolded nuclear correlations using shell model calculations, have been attributed to the properties of the 2-body spin-orbit interaction, the amplitude of which is derived for the first time in an atomic nucleus. The present results, remarkably well reproduced by using several realistic nucleon-nucleon forces, provide a unique touchstone for the modeling of the spin-orbit interaction in atomic nuclei.

  13. Computational analysis of wake structure and body forces on marine animal research tag

    NASA Astrophysics Data System (ADS)

    Rosanio, Matthew; Morrida, Jacob; Green, Melissa

    2013-11-01

    The Acousounde 3B marine animal research tag is used to study the relationship between the sounds made by whales and their behaviors, and ultimately to improve whale conservation efforts. In practical implementation, some researchers have attached external GPS Fastloc devices to the top surface of the tag, in order to accurately record the position of the whales throughout the deployment. There is a need to characterize the flow over the tag in order to better understand the body forces being exerted on it and how wake turbulence could affect noise measurements. The addition of the GPS Fastloc exacerbates both of these concerns, as it complicates the hydrodynamics of the device. Using CFD techniques, we were able to simulate the flow over the tag with a GPS attachment at multiple yaw angles. We used Pointwise to construct the mesh and Fluent to simulate the flow. We have also used flow visualization to experimentally validate our computational results. It was found that the GPS has a minimal effect on the wake of the tag at a 0 degree offset from the freestream flow. However, at increasing offset angles, the presence of the GPS greatly increased the amount of wake turbulence observed. Performed work while undergrad at Syracuse.

  14. Do body weight and gender shape the work force? The case of Iceland.

    PubMed

    Asgeirsdottir, Tinna Laufey

    2011-03-01

    Most studies of the relationship between body weight - as well as its corollary, beauty - and labor-market outcomes have indicated that it is a function of a gender bias, the negative relationship between excess weight or obesity and labor-market outcomes being greater for women than for men. Iceland offers an exceptional opportunity to examine this hypothesis, given that it scores relatively well on an index of gender equality comprising economic, political, educational, labor-market, and health-based criteria. Equipped with an advanced level of educational attainment, on average, women are well represented in Iceland's labor force. When it comes to women's presence in the political sphere, Iceland is out of the ordinary as well; that Icelanders were the first in the world to elect a woman to be president may suggest a relatively gender-blind assessment in the labor market. In the current study, survey data collected by Gallup Iceland in 2002 are used to examine the relationship between weight and employment within this political and social setting. Point estimates indicate that, despite apparently lesser gender discrimination in Iceland than elsewhere, the bias against excess weight and obesity remains gender-based, showing a slightly negative relationship between weight and the employment rate of women, whereas a slightly positive relationship was found for men. PMID:21196135

  15. Wake dynamics past a curved body of circular cross-section under forced cross-flow vibration

    NASA Astrophysics Data System (ADS)

    de Vecchi, A.; Sherwin, S. J.; Graham, J. M. R.

    2009-05-01

    Three-dimensional numerical simulations are presented of flow past a curved body at a Reynolds number of 100. The geometry consists of a circular cross-sectioned body, whose centreline axis is prescribed by a quarter ring with a horizontal extension. This plane of curvature of the body is aligned to the free-stream flow direction such that the outer part of the ring is the body's stagnation face (convex configuration). The bluff body is forced to sinusoidally vibrate in the cross-flow direction at different amplitudes and frequencies. The resulting vortex shedding is strongly influenced by the curvature of the body. Within the lock-in region for a straight cylinder, the shedding past the convex body exhibits a 2S mode for all the pairs of input parameters tested; outside this region, a “weak” form of shedding with two pairs of counter-rotating vortices per cycle occurs in the top part of the body. At lower amplitudes of oscillation and frequencies below the Strouhal value for a straight cylinder, dislocations are found in the near wake: these generally occur in the middle of the curved part of the body, at an angle of approximately 45 from the top plane, regardless of the amplitude of oscillation. However, at very low amplitudes, an increase in the input frequency is found to influence the spanwise position of the dislocations by shifting them towards the top sections. The wake dynamics and force distribution are associated with the relative importance of the different regions of the curved geometry: the top region, nearly perpendicular to the inflow and therefore comparable to a straight cylinder, and the lower region with the horizontal extension, which is parallel to the inflow direction and hence behaves similarly to a slender body. The influence of the force contributions from these regions and their different nature determine the occurrence of dislocations in the wake, as well as their position along the span. The energy transfer mechanism, which determines whether the body is excited or damped by the flow, is also affected by this balance: at very low amplitudes the top part undergoes a lift force due to vortex shedding, which is strong enough to overcome the dampening effect from the horizontal extension used in this case and therefore provides a positive energy transfer from the fluid to the structure.

  16. Determination of radiation exposure history of common materials and computer hardware by using atomic (and magnetic force) microscopy

    NASA Astrophysics Data System (ADS)

    Sharma, J.; Teter, J. P.; Abbundi, R. J.; Guardala, N. A.

    2003-04-01

    Defects produced by ionizing radiation are smaller than a micrometer and are unobservable in an optical microscope. An atomic force microscope was utilized to reveal their counts and structure in common materials like mica, silicon, organic solids, polymers, sugar, quartz, and calcite. A magnetic force microscope has shown the damage of radiation on computer hard disks. The present work shows that exposure to radioactive material leaves a permanent record, which can be read for dosimetric or forensic purposes by using atomic force microcopy on common objects or a magnetic force microscope on magnetic media.

  17. Paleo-Magnetic Field Recorded in the Parent Body of the Murchison Meteorite

    NASA Astrophysics Data System (ADS)

    Kletetschka, G.; Páchová, H.

    2014-12-01

    Murchison meteorite is a carbonaceous chondrite containing small amount of chondrules, various inclusions, and matrix with occasional porphyroblasts of olivine and/or pyroxene. We applied magnetic efficiency method (Kletetschka et al 2005, Kohout et al, 2008) in order to get the demagnetization spectra for several randomly oriented fragments of Murchison meteorite. Our method detected not only viscous magnetization removable in low fields, but also very persistent magnetizations in all meterorite fragments. Data suggest that magnetic carriers within the Murchison meteorite were grown in a paleofield of 450 - 850 nT. Meteorite record in other fragments contains an existence of antipodal fields that may be tied to an event of magnetic reversal within the nebular magnetic field or parent asteroid body. Other meteorites show stable record over its entire spectrum, giving magnetic paleofield of 1100 - 1900 nT. Magnetic record in Murchison meteorite comes from magnetite, pyrrhotite and Iron Nickel alloy. Pyrrhotite is suggested to be the main carrier of the paleofield in Murchison. Iron-Nickel alloy generate observable zigzag pattern when magnetically saturated. Kletetschka, G., Kohout, T., Wasilewski, P., and Fuller, M. D., 2005, Recognition of thermal remanent magnetization in rocks and meteorites, The IAGA Scientific Assembly, Volume GAI10: Toulouse, IAGA, p. IAGA2005-A-00945. Kohout, T., Kletetschka, G., Donadini, F., Fuller, M., and Herrero-Bervera, E., 2008, Analysis of the natural remanent magnetization of rocks by measuring the efficiency ratio through alternating field demagnetization spectra: Studia Geophysica Et Geodaetica, v. 52, no. 2, p. 225-235.

  18. Forces and moments of a small body moving in a 3-D unsteady flow (with applications to slender structures)

    SciTech Connect

    Foulhoux, L. . Marine Advanced Techniques Section); Bernitsas, M.M. . Dept. of Naval Architecture and Marine Engineering)

    1993-05-01

    Complete expressions are derived for the inertia forces and moments acting on a small body in a six-degree-of-freedom motion in a three-dimensional unsteady flow in an unbounded ideal fluid. The far-field approximation of the body motion is represented by a series of multipoles located at the origin of the body. Unsteady terms are expanded in a dual series to the multipole series. Lagally integrals are expressed in terms of multipoles as well, by using Legendre polynomial expansions. New inertia force expressions are derived by truncating the multipole series after the quadrupoles. Corresponding terms for moments are also developed. The derived formulas are still compact enough for engineering applications. Many practical problems involving fixed and oscillating cylinders, piles, and risers are studied numerically. Comparisons to the Morison equation formulation prove that the nonlinear convective terms are not negligible in multidimensional relative flows.

  19. Limitations of force-free magnetic field extrapolations: revisiting basic assumptions

    E-print Network

    Peter, H; Chitta, L P; Cameron, R H

    2015-01-01

    Force-free extrapolations are widely used to study the magnetic field in the solar corona based on surface measurements. The extrapolations assume that the ratio of internal energy of the plasma to magnetic energy, the plasma-beta is negligible. Despite the widespread use of this assumption observations, models, and theoretical considerations show that beta is of the order of a few percent to more than 10%, and thus not small. We investigate what consequences this has for the reliability of extrapolation results. We use basic concepts starting with the force and the energy balance to infer relations between plasma-beta and free magnetic energy, to study the direction of currents in the corona with respect to the magnetic field, and to estimate the errors in the free magnetic energy by neglecting effects of the plasma (beta<<1). A comparison with a 3D MHD model supports our basic considerations. If plasma-beta is of the order of the relative free energy (the ratio of the free magnetic energy to the total...

  20. Expanded Equations for Torque and Force on a Cylindrical Permanent Magnet Core in a Large-Gap Magnetic Suspension System

    NASA Technical Reports Server (NTRS)

    Groom, Nelson J.

    1997-01-01

    The expanded equations for torque and force on a cylindrical permanent magnet core in a large-gap magnetic suspension system are presented. The core is assumed to be uniformly magnetized, and equations are developed for two orientations of the magnetization vector. One orientation is parallel to the axis of symmetry, and the other is perpendicular to this axis. Fields and gradients produced by suspension system electromagnets are assumed to be calculated at a point in inertial space which coincides with the origin of the core axis system in its initial alignment. Fields at a given point in the core are defined by expanding the fields produced at the origin as a Taylor series. The assumption is made that the fields can be adequately defined by expansion up to second-order terms. Examination of the expanded equations for the case where the magnetization vector is perpendicular to the axis of symmetry reveals that some of the second-order gradient terms provide a method of generating torque about the axis of magnetization and therefore provide the ability to produce six-degree-of-freedom control.

  1. 3-D Force Control on the Human Fingerpad Using a Magnetic Levitation Device for Fingernail Imaging Calibration

    E-print Network

    Hollerbach, John M.

    3-D Force Control on the Human Fingerpad Using a Magnetic Levitation Device for Fingernail Imaging of Mechanical Engineering University of Utah ABSTRACT This paper demonstrates fast, accurate, and stable force. The primary application of this force control is for the automated calibration of a fingernail imaging system

  2. IEEE TRANSACTIONS ON MAGNETICS, VOL. 42, NO. 10, OCTOBER 2006 3165 Temperature Dependence of FORC Diagrams in

    E-print Network

    Spinu, Leonard

    ). The FORC diagram is calculated as described in [1]­[4] at a set of temper- atures K around the blocking Terms--FORC diagram, magnetization processes, Preisach model. I. INTRODUCTION AS the new patterned media which implies in each case the simulation of a set of typically 100 first-order reversal curves (FORC

  3. Magnetic susceptibility variations in Loess sequences and their relationship to astronomical forcing

    NASA Technical Reports Server (NTRS)

    Verosub, Kenneth L.; Singer, Michael J.

    1992-01-01

    The long, well-exposed and often continuous sequences of loess found throughout the world are generally thought to provide an excellent opportunity for studying long-term, large-scale environmental change during the last few million years. In recent years, the most fruitful loess studies have been those involving the deposits of the loess in China. One of the most intriguing results of that work has been the discovery of an apparent correlation between variations in the magnetic susceptibility of the loess sequence and the oxygen isotope record of the deep sea. This correlation implies that magnetic susceptibility variations are being driven by astronomical parameters. However, the basic data have been interpreted in various ways by different authors, most of whom assumed that the magnetic minerals in the loess have not been affected by post-depositional processes. Using a chemical extraction procedure that allows us to separate the contribution of secondary pedogenic magnetic minerals from primary inherited magnetic minerals, we have found that the magnetic susceptibility of the Chinese paleosols is largely due to a pedogenic component which is present to a lesser degree in the loess. We have also found that the smaller inherited component of the magnetic susceptibility is about the same in the paleosols and the loess. These results demonstrate the need for additional study of the processes that create magnetic susceptibility variations in order to interpret properly the role of astronomical forcing in producing these variations.

  4. Study of magnetism in Ni-Cr hardface alloy deposit on 316LN stainless steel using magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Kishore, G. V. K.; Kumar, Anish; Chakraborty, Gopa; Albert, S. K.; Rao, B. Purna Chandra; Bhaduri, A. K.; Jayakumar, T.

    2015-07-01

    Nickel base Ni-Cr alloy variants are extensively used for hardfacing of austenitic stainless steel components in sodium cooled fast reactors (SFRs) to avoid self-welding and galling. Considerable difference in the compositions and melting points of the substrate and the Ni-Cr alloy results in significant dilution of the hardface deposit from the substrate. Even though, both the deposit and the substrate are non-magnetic, the diluted region exhibits ferromagnetic behavior. The present paper reports a systematic study carried out on the variations in microstructures and magnetic behavior of American Welding Society (AWS) Ni Cr-C deposited layers on 316 LN austenitic stainless steels, using atomic force microscopy (AFM) and magnetic force microscopy (MFM). The phase variations of the oscillations of a Co-Cr alloy coated magnetic field sensitive cantilever is used to quantitatively study the magnetic strength of the evolved microstructure in the diluted region as a function of the distance from the deposit/substrate interface, with the spatial resolution of about 100 nm. The acquired AFM/MFM images and the magnetic property profiles have been correlated with the variations in the chemical compositions in the diluted layers obtained by the energy dispersive spectroscopy (EDS). The study indicates that both the volume fraction of the ferromagnetic phase and its ferromagnetic strength decrease with increasing distance from the deposit/substrate interface. A distinct difference is observed in the ferromagnetic strength in the first few layers and the ferromagnetism is observed only near to the precipitates in the fifth layer. The study provides a better insight of the evolution of ferromagnetism in the diluted layers of Ni-Cr alloy deposits on stainless steel.

  5. Observation of force-detected nuclear magnetic resonance in a homogeneous field

    PubMed Central

    Madsen, L. A.; Leskowitz, G. M.; Weitekamp, D. P.

    2004-01-01

    We report the experimental realization of BOOMERANG (better observation of magnetization, enhanced resolution, and no gradient), a sensitive and general method of magnetic resonance. The prototype millimeter-scale NMR spectrometer shows signal and noise levels in agreement with the design principles. We present 1H and 19F NMR in both solid and liquid samples, including time-domain Fourier transform NMR spectroscopy, multiple-pulse echoes, and heteronuclear J spectroscopy. By measuring a 1H-19F J coupling, this last experiment accomplishes chemically specific spectroscopy with force-detected NMR. In BOOMERANG, an assembly of permanent magnets provides a homogeneous field throughout the sample, while a harmonically suspended part of the assembly, a detector, is mechanically driven by spin-dependent forces. By placing the sample in a homogeneous field, signal dephasing by diffusion in a field gradient is made negligible, enabling application to liquids, in contrast to other force-detection methods. The design appears readily scalable to ?m-scale samples where it should have sensitivity advantages over inductive detection with microcoils and where it holds great promise for application of magnetic resonance in biology, chemistry, physics, and surface science. We briefly discuss extensions of the BOOMERANG method to the ?m and nm scales. PMID:15326302

  6. A comparison of 60 Hz uniform magnetic and electric induction in the human body.

    PubMed

    Dawson, T W; Caputa, K; Stuchly, M A

    1997-12-01

    High-resolution computations of induced fields are used to assess equivalent source levels for human exposure to uniform low-frequency electric and magnetic fields. These results pertain to 60 Hz foot-to-head electric excitation of the body in three positions with respect to a ground plane, and to magnetic excitation by three orthogonal source orientations. All computations are based on an anatomically derived human body model composed of 1736873 cubic voxels with 3.6 mm edges. The data for magnetic excitation are computed using a scalar potential finite difference (SPFD) method, while those for electric excitation are computed using a hybrid method based on the SPFD method coupled with a quasistatic finite difference time domain code. The data are analysed in two ways, using an induced current density threshold of 1 mA m-2. Firstly, the various field strengths required to produce a whole-body average current density magnitude equal to the threshold are derived for each configuration, and the associated current density levels in various organs and tissues are presented. It is found that the average current density magnitude values in at least one tissue group can be up to 3 (5) times greater than the whole-body average under electric (magnetic) excitation, and that the associated maximum values can be up to 46 (28) times greater than the whole-body average under electric (magnetic) excitation, for at least one source/body configuration. Secondly, the data are analysed from the opposite point of view, in which the source levels required to induce average or maximum induced current density magnitudes at the threshold level in specific tissue groups are determined. Evaluations such as the present one should prove useful in the development of protection standards, and are also expected to aid in the understanding of results from various animal and tissue culture studies. PMID:9434290

  7. Force and heat current formulas for many-body potentials in molecular dynamics simulations with applications to thermal conductivity calculations

    NASA Astrophysics Data System (ADS)

    Fan, Zheyong; Pereira, Luiz Felipe C.; Wang, Hui-Qiong; Zheng, Jin-Cheng; Donadio, Davide; Harju, Ari

    2015-09-01

    We derive expressions of interatomic force and heat current for many-body potentials such as the Tersoff, the Brenner, and the Stillinger-Weber potential used extensively in molecular dynamics simulations of covalently bonded materials. Although these potentials have a many-body nature, a pairwise force expression that follows Newton's third law can be found without referring to any partition of the potential. Based on this force formula, a stress applicable for periodic systems can be unambiguously defined. The force formula can then be used to derive the heat current formulas using a natural potential partitioning. Our heat current formulation is found to be equivalent to most of the seemingly different heat current formulas used in the literature, but to deviate from the stress-based formula derived from two-body potential. We validate our formulation numerically on various systems described by the Tersoff potential, namely three-dimensional silicon and diamond, two-dimensional graphene, and quasi-one-dimensional carbon nanotube. The effects of cell size and production time used in the simulation are examined.

  8. EVOLUTION OF THE MAGNETIC ENERGY BUDGET IN AR 10486 FROM POTENTIAL AND NONLINEAR FORCE-FREE MODELS

    E-print Network

    Régnier, Stéphane

    1 EVOLUTION OF THE MAGNETIC ENERGY BUDGET IN AR 10486 FROM POTENTIAL AND NONLINEAR FORCE before and after the X17.2 flare on October 28. To determine the coronal mangetic fields, we use in a reversed-Y magnetic configuration. From the 3D configurations we derive the magnetic energy budget which

  9. The Use of Magnets for Introducing Primary School Students to Some Properties of Forces through Small-Group Pedagogy

    ERIC Educational Resources Information Center

    Carruthers, Rebecca; de Berg, Kevin

    2010-01-01

    Seventeen Grade Six students were divided into small groups to study the concept of forces in the context of magnets and their properties. The researcher, a pre-service primary school teacher, encouraged the students into conversation about magnets and it was found that, without hesitation, they talked about their prior experience of magnets. The…

  10. An energy-conserving formalism for adaptive gravitational force softening in SPH and N-body codes

    E-print Network

    D. J. Price; J. J. Monaghan

    2006-10-30

    In this paper we describe an adaptive softening length formalism for collisionless N-body and self-gravitating Smoothed Particle Hydrodynamics (SPH) calculations which conserves momentum and energy exactly. This means that spatially variable softening lengths can be used in N-body calculations without secular increases in energy. The formalism requires the calculation of a small additional term to the gravitational force related to the gradient of the softening length. The extra term is similar in form to the usual SPH pressure force (although opposite in direction) and is therefore straightforward to implement in any SPH code at almost no extra cost. For N-body codes some additional cost is involved as the formalism requires the computation of the density via a summation over neighbouring particles using the smoothing kernel. The results of numerical tests demonstrate that, for homogeneous mass distributions, the use of adaptive softening lengths gives a softening which is always close to the `optimal' choice of fixed softening parameter, removing the need for fine-tuning. For a heterogeneous mass distribution (as may be found in any large scale N-body simulation) we find that the errors on the least-dense component are lowered by an order of magnitude compared to the use of a fixed softening length tuned to the densest component. For SPH codes our method presents a natural and elegant choice of softening formalism which makes a small improvement to both the force resolution and the total energy conservation at almost zero additional cost.

  11. Asymptotic analysis of force-free magnetic fields of cylindrical symmetry

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.; Antiochos, S. K.; Roumeliotis, G.

    1995-01-01

    It is known from computer calculations that if a force-free magnetic-field configuration is stressed progressively by footpoint displacements, the configuration expands and approaches the open configuration with the same surface flux distribution, and, in the process, the energy of the field increases progressively. Analysis of a simple model of force-free fields of cylindrical symmetry leads to simple asymptotic expressions for the extent and energy of such a configuration. The analysis is carried through for both spherical and planar source surfaces. According to this model, the field evolves in a well-behaved manner with no indication of instability or loss of equilibrium.

  12. Rotordynamic forces acting on a centrifugal open impeller in whirling motion by using active magnetic bearing

    NASA Astrophysics Data System (ADS)

    Nagao, N.; Eguchi, M.; Uchiumi, M.; Yoshida, Y.

    2013-03-01

    Rotordynamic forces acting on a centrifugal open impeller of a rocket engine turbopump were measured using a rotordynamic test stand controlled by active magnetic bearings. The tangential rotordynamic force ft had a small constantly negative value in the measured range. The direct stiffness K had a positive value under various test conditions. In general, direct stiffness K of a closed impeller had a negative value because of the Bernoulli effect. In the case of open impellers, the Bernoulli effect is speculated to be smaller because the absence of a front shroud makes K positive.

  13. JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS, VOL. 118, 23772397, doi:10.1002/jgra.50163, 2013 Compressible f-plane solutions to body forces, heatings, and coolings,

    E-print Network

    Vadas, Sharon

    . Space Physics, 118, 2377­2397, doi:10.1002/jgra.50163. 1. Introduction [2] Local, interval body forcesJOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS, VOL. 118, 2377­2397, doi:10.1002/jgra.50163, 2013 Compressible f-plane solutions to body forces, heatings, and coolings, and application to the primary

  14. Scaling the energy conversion rate from magnetic field reconnection to different bodies

    SciTech Connect

    Mozer, F. S.; Hull, A.

    2010-10-15

    Magnetic field reconnection is often invoked to explain electromagnetic energy conversion in planetary magnetospheres, stellar coronae, and other astrophysical objects. Because of the huge dynamic range of magnetic fields in these bodies, it is important to understand energy conversion as a function of magnetic field strength and related parameters. It is conjectured theoretically and shown experimentally that the energy conversion rate per unit area in reconnection scales as the cube of an appropriately weighted magnetic field strength divided by the square root of an appropriately weighted density. With this functional dependence, the energy release in flares on the Sun, the large and rapid variation of the magnetic flux in the tail of Mercury, and the apparent absence of reconnection on Jupiter and Saturn, may be understood. Electric fields at the perihelion of the Solar Probe Plus mission may be tens of V/m.

  15. Exploiting Size-Dependent Drag and Magnetic Forces for Size-Specific Separation of Magnetic Nanoparticles.

    PubMed

    Rogers, Hunter B; Anani, Tareq; Choi, Young Suk; Beyers, Ronald J; David, Allan E

    2015-01-01

    Realizing the full potential of magnetic nanoparticles (MNPs) in nanomedicine requires the optimization of their physical and chemical properties. Elucidation of the effects of these properties on clinical diagnostic or therapeutic properties, however, requires the synthesis or purification of homogenous samples, which has proved to be difficult. While initial simulations indicated that size-selective separation could be achieved by flowing magnetic nanoparticles through a magnetic field, subsequent in vitro experiments were unable to reproduce the predicted results. Magnetic field-flow fractionation, however, was found to be an effective method for the separation of polydisperse suspensions of iron oxide nanoparticles with diameters greater than 20 nm. While similar methods have been used to separate magnetic nanoparticles before, no previous work has been done with magnetic nanoparticles between 20 and 200 nm. Both transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis were used to confirm the size of the MNPs. Further development of this work could lead to MNPs with the narrow size distributions necessary for their in vitro and in vivo optimization. PMID:26307980

  16. Exploiting Size-Dependent Drag and Magnetic Forces for Size-Specific Separation of Magnetic Nanoparticles

    PubMed Central

    Rogers, Hunter B.; Anani, Tareq; Choi, Young Suk; Beyers, Ronald J.; David, Allan E.

    2015-01-01

    Realizing the full potential of magnetic nanoparticles (MNPs) in nanomedicine requires the optimization of their physical and chemical properties. Elucidation of the effects of these properties on clinical diagnostic or therapeutic properties, however, requires the synthesis or purification of homogenous samples, which has proved to be difficult. While initial simulations indicated that size-selective separation could be achieved by flowing magnetic nanoparticles through a magnetic field, subsequent in vitro experiments were unable to reproduce the predicted results. Magnetic field-flow fractionation, however, was found to be an effective method for the separation of polydisperse suspensions of iron oxide nanoparticles with diameters greater than 20 nm. While similar methods have been used to separate magnetic nanoparticles before, no previous work has been done with magnetic nanoparticles between 20 and 200 nm. Both transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis were used to confirm the size of the MNPs. Further development of this work could lead to MNPs with the narrow size distributions necessary for their in vitro and in vivo optimization. PMID:26307980

  17. MEMS-Based Force-Detected Nuclear Magnetic Resonance (FDNMR) Spectrometer

    NASA Technical Reports Server (NTRS)

    Lee, Choonsup; Butler, Mark C.; Elgammal, Ramez A.; George, Thomas; Hunt, Brian; Weitekamp, Daniel P.

    2006-01-01

    Nuclear Magnetic Resonance (NMR) spectroscopy allows assignment of molecular structure by acquiring the energy spectrum of nuclear spins in a molecule, and by interpreting the symmetry and positions of resonance lines in the spectrum. As such, NMR has become one of the most versatile and ubiquitous spectroscopic methods. Despite these tremendous successes, NMR experiments suffer from inherent low sensitivity due to the relatively low energy of photons in the radio frequency (rt) region of the electromagnetic spectrum. Here, we describe a high-resolution spectroscopy in samples with diameters in the micron range and below. We have reported design and fabrication of force-detected nuclear magnetic resonance (FDNMR).

  18. Magnetic force driven nanogenerators as a noncontact energy harvester and sensor.

    PubMed

    Cui, Nuanyang; Wu, Weiwei; Zhao, Yong; Bai, Suo; Meng, Leixin; Qin, Yong; Wang, Zhong Lin

    2012-07-11

    Nanogenerator has been a very important energy harvesting technology through directly deforming piezoelectric material. Here, we report a new magnetic force driven contactless nanogenerator (CLNG), which avoids the direct contact between nanogenerator and mechanical movement source. The CLNG can harvest the mechanical movement energy in a noncontact mode to generate electricity. Their output voltage and current can be as large as 3.2 V and 50 nA, respectively, which is large enough to power up a liquid crystal display. We also demonstrate a means by which a magnetic sensor can be built. PMID:22681509

  19. A Sound Mind in a Sound Body: That's the Philosophy behind This Classical Greek Magnet School.

    ERIC Educational Resources Information Center

    Natale, Jo Anna

    1992-01-01

    Central City High School, Kansas City, Missouri, has found its identity in the past. As part of comprehensive desegregation program, this magnet school offers its students classical Greek program that, like ancient Greek civilization, calls for as much attention to body as to mind. The costly Olympic athletic program and classical Greek curriculum…

  20. Nonlinear force-free reconstruction of the global solar magnetic field: methodology

    E-print Network

    Contopoulos, Ioannis; Georgoulis, Manolis

    2010-01-01

    We present a novel numerical method that allows the calculation of nonlinear force-free magnetostatic solutions above a boundary surface on which only the distribution of the normal magnetic field component is given. The method relies on the theory of force-free electrodynamics and applies directly to the reconstruction of the solar coronal magnetic field for a given distribution of the photospheric radial field component. The method works as follows: we start with any initial magnetostatic global field configuration (e.g. zero, dipole), and along the boundary surface we create an evolving distribution of tangential (horizontal) electric fields that, via Faraday's equation, give rise to a respective normal field distribution approaching asymptotically the target distribution. At the same time, these electric fields are used as boundary condition to numerically evolve the resulting electromagnetic field above the boundary surface, modelled as a thin ideal plasma with non-reflecting, perfectly absorbing outer b...

  1. Estimating Three-Dimensional Orientation of Human Body Parts by Inertial/Magnetic Sensing

    PubMed Central

    Sabatini, Angelo Maria

    2011-01-01

    User-worn sensing units composed of inertial and magnetic sensors are becoming increasingly popular in various domains, including biomedical engineering, robotics, virtual reality, where they can also be applied for real-time tracking of the orientation of human body parts in the three-dimensional (3D) space. Although they are a promising choice as wearable sensors under many respects, the inertial and magnetic sensors currently in use offer measuring performance that are critical in order to achieve and maintain accurate 3D-orientation estimates, anytime and anywhere. This paper reviews the main sensor fusion and filtering techniques proposed for accurate inertial/magnetic orientation tracking of human body parts; it also gives useful recipes for their actual implementation. PMID:22319365

  2. Leg intramuscular pressures and in vivo knee forces during lower body positive and negative pressure treadmill exercise.

    PubMed

    Macias, Brandon R; D'Lima, Darryl D; Cutuk, Adnan; Patil, Shantanu; Steklov, Nick; Neuschwander, Timothy B; Meuche, Sabine; Colwell, Clifford W; Hargens, Alan R

    2012-07-01

    Quantifying muscle and joint forces over a broad range of weight bearing loads during exercise may provide data required to improve prosthetic materials and better protect against muscle and bone loss. Collectively, leg intramuscular pressure (IMP), ground reaction force (GRF), and the instrumented tibial tray force measurements provide a comprehensive assessment of leg muscle and joint biomechanical effects of gravity during exercise. Titration of body weight (BW) by lower body negative pressure (LBNP) and lower body positive pressure (LBPP) can reproducibly modulate IMP within leg muscle compartments. In addition, previous studies document peak tibial forces during various daily activities of 2.2 to 2.5 BW. The study objective was to determine the IMPs of the leg, axial compressive force on the tibia in vivo, vertical GRF, and knee range of motion during altered BW levels using LBPP and LBNP treadmill exercise. We hypothesize that peak GRF, peak tibial forces, and peak IMPs of the leg correlate linearly with percent BW, as generated across a broad range of upright LBPP and supine LBNP exercise. When running at 2.24 m/s the leg IMPs significantly increased over the loading range of 60% to 140% BW with LBPP and LBNP (P < 0.001); as expected, leg IMPs were significantly higher when running compared with standing (P < 0.001). During upright LBPP, total axial force at the knee increased linearly as a function of BW at 0.67 m/s (R(2) = 0.90) and 1.34 m/s (R(2) = 0.98). During supine LBNP, total axial force at the knee increased linearly as a function of BW at 0.67 m/s (R(2) = 0.98) and 1.34 m/s (R(2) = 0.91). The present study is the first to measure IMPs and peak tibial forces in vivo during upright LBPP, upright LBNP, and supine LBNP exercise. These data will aid the development of rehabilitation exercise hardware and prescriptions for patients and astronauts. PMID:22539171

  3. Determination of forces in a magnetic bearing actuator - Numerical computation with comparison to experiment

    NASA Technical Reports Server (NTRS)

    Knight, J. D.; Xia, Z.; Mccaul, E.; Hacker, H., Jr.

    1992-01-01

    Calculations of the forces exerted on a journal by a magnetic bearing actuator are presented, along with comparisons to experimentally measured forces. The calculations are based on two-dimensional solutions for the flux distribution in the metal parts and free space, using finite but constant permeability in the metals. Above a relative permeability of 10,000 the effects of changes in permeability are negligible, but below 10,000 decreases in permeability cause significant decreases in the force. The calculated forces are shown to depend on the metal permeability more strongly when the journal is displaced from its centered position. The predicted forces in the principal attractive direction are in good agreement with experiment when a relatively low value of permeability is chosen. The forces measured normal to the axis of symmetry when the journal is displaced from that axis, however, are significantly higher than predicted by theory, even with a value of relative permeability larger than 5000. These results indicate a need for further work including nonlinear permeability distributions.

  4. Magnetic force microscopy/current contrast imaging: A new technique for internal current probing of ICs

    SciTech Connect

    Campbell, A.N.; Cole, E.I. Jr.; Dodd, B.A.; Anderson, R.E.

    1993-09-01

    This invited paper describes recently reported work on the application of magnetic force microscopy (MFM) to image currents in IC conductors [1]. A computer model for MFM imaging of IC currents and experimental results demonstrating the ability to determine current direction and magnitude with a resolution of {approximately} 1 mA dc and {approximately} 1 {mu}A ac are presented. The physics of MFM signal generation and applications to current imaging and measurement are described.

  5. Imaging Carbon Nanotubes in High Performance Polymer Composites via Magnetic Force Microscope

    NASA Technical Reports Server (NTRS)

    Lillehei, Peter T.; Park, Cheol; Rouse, Jason H.; Siochi, Emilie J.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    Application of carbon nanotubes as reinforcement in structural composites is dependent on the efficient dispersion of the nanotubes in a high performance polymer matrix. The characterization of such dispersion is limited by the lack of available tools to visualize the quality of the matrix/carbon nanotube interaction. The work reported herein demonstrates the use of magnetic force microscopy (MFM) as a promising technique for characterizing the dispersion of nanotubes in a high performance polymer matrix.

  6. The exterior source surface for force-free fields. [solar atmosphere magnetic field model

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.

    1978-01-01

    Consideration is given to the exterior source surface for force-free fields. The spherical harmonic expansion is presented for boundary values on two concentric spheres. An upper limit on a constant which measures the strength of coronal currents is found to be a function of the lowest multipole moment of the prescribed boundary values. The solar atmosphere is in the class of magnetic fields for which the study is applicable.

  7. Electric/magnetic dipolein an electromagnetic field: force, torque and energy

    NASA Astrophysics Data System (ADS)

    Kholmetskii, Alexander; Missevitch, Oleg; Yarman, T.

    2014-10-01

    In this paper we collect the relativistic expressions for the force, torque and energy of a small electric/magnetic dipole in an electromagnetic field, which we recently obtained (A.L. Kholmetskii et al., Eur. J. Phys. 33, L7 (2011), Prog. Electromagn. Res. B 45, 83 (2012), Can. J. Phys. 9, 576 (2013)) and consider a number of subtle effects, characterized the behavior of the dipole in an external field, which seem interesting from the practical viewpoint.

  8. Calculation of the induced currents and forces for a hybrid magnetic levitation system

    SciTech Connect

    Albertz, D.; Dappen, S.; Henneberger, G.

    1997-03-01

    This paper presents the calculation of the induced currents and forces for a 3D non-linear eddy current field problem with ferromagnetic moving conductors. The {rvec A}, V-{rvec A} formulation is used in combination with four different gauging methods to stabilize the solution process. To consider non-rectangular shapes of geometries tetrahedral elements were employed. The computation procedure is applied to a hybrid magnetic levitation system of a contactless and frictionless conveyance system.

  9. Current evaluation of hydraulics to replace the cable force transmission system for body-powered upper-limb prostheses.

    PubMed

    LeBlanc, M

    1990-01-01

    Present body-powered upper-limb prostheses use a cable control system employing World War II aircraft technology to transmit force from the body to the prosthesis for operation. The cable and associated hardware are located outside the prosthesis. Because individuals with arm amputations want prostheses that are natural looking with a smooth, soft outer surface, a design and development project was undertaken to replace the cable system with hydraulics located inside the prosthesis. Three different hydraulic transmission systems were built for evaluation, and other possibilities were explored. Results indicate that a hydraulic force transmission system remains an unmet challenge as a practical replacement for the cable system. The author was unable to develop a hydraulic system that meets the necessary dynamic requirements and is acceptable in size and appearance. PMID:10149042

  10. Trapping and micromanipulation using ultrasonic fields and dual ultrasonic/magnetic forces

    NASA Astrophysics Data System (ADS)

    Hill, Martyn; Glynne-Jones, Peter; Harris, Nicholas R.; Boltryk, Rosemary J.; Stanley, Christopher; Bond, Damian

    2010-08-01

    Ultrasonic fields can be used to trap and manipulate micron-scale particles and second-phase fluids, utilising energy densities that do not impair cell viability. The technology can be seen as complementary to optical trapping as the size of the potential wells generated can be relatively large, making ultrasound suitable for the formation and manipulation of cell agglomerates, but less suitable for the manipulation of individual cells. This paper discusses physical phenomena associated with ultrasonic manipulation, including radiation forces, cavitation, and acoustic streaming. The technology is well suited to integration within "Lab on a Chip" devices and can involve excitation by plane, focussed, flexural, or surface acoustic waves. Example applications of resonators are discussed including particle filtration and concentration, cell washing, and biosensor enhancement. A recently developed device that uses both ultrasonic and magnetic forces to enhance the detection of tuberculosis bacteria using magnetic beads is discussed in detail. This approach uses ultrasonic levitation forces to overcome some of the issues associated with purely magnetic trapping. The technology has been implemented in a device in which the main fluidic components are disposable to allow for low production costs and improved control of biohazards.

  11. Effect of size and geometry on levitation force measurements between permanent magnets and high-temperature superconductors

    SciTech Connect

    Cha, Y.S.; Hull, J.R.; Mulcahy, T.M.; Rossing, T.D. )

    1991-11-15

    A series of experiments measuring the levitation force between a permanent magnet (PM) and a high-temperature superconductor (HTS) and between pairs of PMs, coupled with finite-element calculations of the forces and fields, has identified factors that influence the levitation force. The self-demagnetizing factor within the HTS and, to some extent, within the PM has a profound effect on magnetic pressure. For large HTSs with strong flux-pinning, the demagnetizing effect of the diamagnetic image of the PM is substantial. For short distances between the HTS and PM, compression of magnetic flux produces a dependence on PM diameter.

  12. The Effective CSR Forces on an Energy-Chirped Bunch under Magnetic Compression

    SciTech Connect

    Rui Li

    2007-06-25

    Following our earlier formulation of the coherent synchrotron radiation (CSR) effect on bunch dynamics in magnetic bends, here we investigate the behavior of the effective CSR forces for an energy-chirped Gaussian bunch in the bending plane around full compression, with special care being taken in the incorporation of the retardation relation. Our results show clearly a delayed response of the CSR forces to the compression or lengthening of the bunch length. In addition, around full compression, our results reveal sensitivity of the effective CSR forces on the particles' transverse position, as a consequence of the geometry of particle interaction and retardation in this regime. These results can serve as benchmarks to the numerical simulation of the CSR effects.

  13. Canine retraction with rare earth magnets: an investigation into the validity of the constant force hypothesis.

    PubMed

    Daskalogiannakis, J; McLachlan, K R

    1996-05-01

    The objective of this study was to test the hypothesis that a prolonged constant force provides more effective tooth movement than an impulsive force of short duration. Six human subjects were selected, the main criterion being a need for extraction of their upper first premolars. Canine retraction on these subjects was executed on one side with the application of a force rapidly declining in magnitude, produced by a vertical loop, and on the other side with the application of a relatively constant force. This type of force was achieved by a similar vertical loop which was constantly activated by three parylene-coated neodymium-iron-boron (Nd2Fe14P) block magnets. The vertical loop on the control side was reactivated 6 weeks after the initial activation. No reactivation was necessary on the experimental side for the duration of the experiment. The rate of tooth movement on the two sides was compared over a period of 3 months, on the basis of maxillary impressions taken at frequent intervals during the course of the study. The canines retracted with a constant force moved statistically significantly more than the control canines (p < 0.05) during the experimental period. The average differences in the mean rates of tooth movement between the two sides were in the order of 2:1 in favor of the experimental side. There were no statistically significant differences in the changes of angulation (tipping) or rotation about the y axis between the two sides. The duration of force application seems to be a critical factor in regulating rate of tooth movement. Conversely, magnitude of the applied force did not appear to be of primary significance. PMID:8638593

  14. Transient body force effects on the dryout and rewet of a heated capillary structure. Doctoral thesis, January 1990-April 1994

    SciTech Connect

    Reagan, M.K.

    1994-04-01

    A transient, one-dimensional numerical code was developed to model the liquid flow in a non-uniformly heated, axial square groove. The groove was subjected to transient body forces up to approximately 0.51 m/s sq. Axial variation in meniscus levels, shear stress and heat transfer between the groove wall and the liquid, axial conduction through the liquid, evaporation and body forces were accounted for in the model. Dryout and rewet of the groove were allowed; the front location was determined using conservation of mass and linear extrapolation. A physical experiment was performed with a stainless steel plate into which eight square grooves were machined. Ethanol was used as the working liquid. One end of the plate was tilted relative to the other end and this tilt was varied with time, thereby providing the transient body force. The depth of the ethanol in the groove, and the dryout and rewet front locations, were experimentally measured. Within the uncertainty of the measurements, the numerical results from the code predicted the correct movement of liquid within the groove structure and also the correct position of the dryout and rewet fronts.

  15. Parallel rf Force Driven by the Inhomogeneity of Power Absorption in Magnetized Plasma Zhe Gao,1,2,* Jiale Chen,2

    E-print Network

    Parallel rf Force Driven by the Inhomogeneity of Power Absorption in Magnetized Plasma Zhe Gao,1 Jersey 08543, USA (Received 8 February 2013; published 6 June 2013) A nonlinear parallel force can no integrated force over a plasma volume, this force can redistribute momentum parallel to the magnetic field

  16. Molecular dynamics simulation of Lorentz force microscopy in magnetic nano-disks

    NASA Astrophysics Data System (ADS)

    Dias, R. A.; Mello, E. P.; Coura, P. Z.; Leonel, S. A.; Maciel, I. O.; Toscano, D.; Rocha, J. C. S.; Costa, B. V.

    2013-04-01

    In this paper, we present a molecular dynamics simulation to model the Lorentz force microscopy experiment. Experimentally, this technique consists in the scattering of electrons by magnetic structures in surfaces and gases. Here, we will explore the behavior of electrons colliding with nano-magnetic disks. The computational molecular dynamics experiment allows us to follow the trajectory of individual electrons all along the experiment. In order to compare our results with the experimental one reported in literature, we model the experimental electron detectors in a simplified way: a photo-sensitive screen is simulated in such way that it counts the number of electrons that collide at a certain position. The information is organized to give in grey scale the image information about the magnetic properties of the structure in the target. Computationally, the sensor is modeled as a square matrix in which we count how many electrons collide at each specific point after being scattered by the magnetic structure. We have used several configurations of the magnetic nano-disks to understand the behavior of the scattered electrons, changing the orientation direction of the magnetic moments in the nano-disk in several ways. Our results match very well with the experiments, showing that this simulation can become a powerful technique to help to interpret experimental results.

  17. A method for embedding circular force-free flux ropes in potential magnetic fields

    SciTech Connect

    Titov, V. S.; Török, T.; Mikic, Z.; Linker, J. A.

    2014-08-01

    We propose a method for constructing approximate force-free equilibria in pre-eruptive configurations in which a thin force-free flux rope is embedded into a locally bipolar-type potential magnetic field. The flux rope is assumed to have a circular-arc axis, a circular cross-section, and electric current that is either concentrated in a thin layer at the boundary of the rope or smoothly distributed across it with a maximum of the current density at the center. The entire solution is described in terms of the magnetic vector potential in order to facilitate the implementation of the method in numerical magnetohydrodynamic (MHD) codes that evolve the vector potential rather than the magnetic field itself. The parameters of the flux rope can be chosen so that its subsequent MHD relaxation under photospheric line-tied boundary conditions leads to nearly exact numerical equilibria. To show the capabilities of our method, we apply it to several cases with different ambient magnetic fields and internal flux-rope structures. These examples demonstrate that the proposed method is a useful tool for initializing data-driven simulations of solar eruptions.

  18. Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations

    NASA Astrophysics Data System (ADS)

    Poisson, Mariano; López Fuentes, Marcelo; Mandrini, Cristina H.; Démoulin, Pascal

    2015-11-01

    The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the force-free parameter [ ?] of the model and, on the other, from the computed coronal magnetic helicity normalized by the magnetic flux squared. We compare our results, for the same set of ARs, with those of Poisson et al. (Solar Phys. 290, 727, 2015), in which the twist was estimated using the so-called magnetic tongues observed in line-of-sight magnetograms during AR emergence. We corroborate the agreement between the photospheric and coronal twist-sign and the presence of magnetic tongues as an early proxy of the AR non-potentiality. We find a globally linear relationship between the coronal twist and the one previously deduced for the emerging AR flux rope at the photospheric level. The coronal-twist value is typically lower by a factor of six than the one deduced for the emerging flux rope. We interpret this result as due to the partial emergence of the flux rope that forms the region.

  19. Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations

    NASA Astrophysics Data System (ADS)

    Poisson, Mariano; López Fuentes, Marcelo; Mandrini, Cristina H.; Démoulin, Pascal

    2015-11-01

    The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the force-free parameter [?] of the model and, on the other, from the computed coronal magnetic helicity normalized by the magnetic flux squared. We compare our results, for the same set of ARs, with those of Poisson et al. ( Solar Phys. 290, 727, 2015), in which the twist was estimated using the so-called magnetic tongues observed in line-of-sight magnetograms during AR emergence. We corroborate the agreement between the photospheric and coronal twist-sign and the presence of magnetic tongues as an early proxy of the AR non-potentiality. We find a globally linear relationship between the coronal twist and the one previously deduced for the emerging AR flux rope at the photospheric level. The coronal-twist value is typically lower by a factor of six than the one deduced for the emerging flux rope. We interpret this result as due to the partial emergence of the flux rope that forms the region.

  20. Magnetic irreversibility and pinning force density in the Mo100-xRex alloy superconductors

    NASA Astrophysics Data System (ADS)

    Sundar, Shyam; Chattopadhyay, M. K.; Sharath Chandra, L. S.; Roy, S. B.

    2015-12-01

    We have measured the isothermal field dependence of magnetization of the Mo100-xRex (15 ? x ? 48) alloys, and have estimated the critical current and pinning force density from these measurements. We have performed structural characterization of the above alloys using standard techniques, and analyzed the field dependence of critical current and pinning force density using existing theories. Our results indicate that dislocation networks and point defects like voids and interstitial imperfections are the main flux line pinning centers in the Mo100-xRex alloys in the intermediate fields, i.e., in the "small bundle" flux line pinning regime. In this regime, the critical current density is also quite robust against increasing magnetic field. In still higher fields, the critical current density is affected by flux creep. In the low field regime, on the other hand, the pinning of the flux lines seems to be influenced by the presence of two superconducting energy gaps in the Mo100-xRex alloys. This modifies the field dependence of critical current density, and also seems to contribute to the asymmetry in the magnetic irreversibility exhibited by the isothermal field dependence of magnetization.

  1. Controlling a magnetic force microscope to track a magnetized nanosize particle

    E-print Network

    Andersson, Sean B.

    feedback control law which translates the measurement of this phase shift into a trajectory for the tip of the MFM and prove that this trajectory converges to a neighborhood of the magnetic particle. The viability and then post- processed to extract information about the motion of objects of interest. The applicability

  2. ON THE STABILITY OF NON-FORCE-FREE MAGNETIC EQUILIBRIA IN STARS

    SciTech Connect

    Duez, V.; Braithwaite, J.; Mathis, S.

    2010-11-20

    The existence of stable magnetic configurations in white dwarfs, neutron stars, and various non-convective stellar regions is now well recognized. It has recently been shown numerically that various families of equilibria, including axisymmetric mixed poloidal-toroidal configurations, are stable. Here we test the stability of an analytically derived non-force-free magnetic equilibrium resulting from an initial relaxation (self-organization) process, using three-dimensional magnetohydrodynamic simulations: the obtained mixed configuration is compared with the dynamical evolution of its purely poloidal and purely toroidal components, both known to be unstable. The mixed equilibrium shows no sign of instability under white noise perturbations. This configuration therefore provides a good description of magnetic equilibrium topology inside non-convective stellar objects and will be useful to initialize magneto-rotational transport in stellar evolution codes and in multi-dimensional magnetohydrodynamic simulations.

  3. Effects of aft geometry on vortex behavior and force production by a tangential jet on a body at high alpha

    NASA Technical Reports Server (NTRS)

    Font, G. I.

    1993-01-01

    Explored in this study are the physical effects of the numerical treatment of the aft geometry on the vortex behavior and force production due to a tangential jet on a body at a high angle of attack. The study is conducted numerically by solving the three-dimensional, compressible-flow, Reynolds-averaged Navier-Stokes equations. Two tangent-ogive cylinder configurations are used. The first configuration locates the computational exit plane at the end of the body, while the second caps the end of the body with a hemisphere and locates the exit plane far downstream. In both configurations, a blowing slot is located at the cylinder-ogive junction. Comparisons are made between results for the two configurations for cases with and without the jet present. Results indicate that inclusion of the wake of the body in the computations, while altering the flow in small details, does not change the character of the flow. The vortex behavior remains unaltered and the force distribution, while changing to some degree in magnitude, does not change in shape.

  4. Temporal and preparation effects in the magnetic nanoparticles of Apis mellifera body parts

    NASA Astrophysics Data System (ADS)

    Chambarelli, L. L.; Pinho, M. A.; Abraçado, L. G.; Esquivel, D. M. S.; Wajnberg, E.

    Magnetic nanoparticles in the Apis mellifera abdomens are well accepted as involved in their magnetoreception mechanism. The effects of sample preparation on the time evolution of magnetic particles in the honeybee body parts (antennae, head, thorax and abdomen) were investigated by Ferromagnetic Resonance (FMR) at room temperature (RT), for about 100 days. Three preparations were tested: (a) washed with water (WT); (b) as (a), kept in glutaraldehyde 2.5% in 0.1 M cacodylate buffer (pH 7.4) for 24 h and washed with cacodylate buffer (C); (c) as (a), kept in glutaraldehyde 2.5% for 24 h and washed with glutaraldehyde 2.5% in cacodylate buffer (GLC). The four body parts of young and adult worker presented magnetic nanoparticles. The Mn 2+ lines are observed except for the antennae spectra. The high field (HF) and low field (LF) components previously observed in the spectra of social insects, are confirmed in these spectra. The HF line is present in all spectra while the LF is easily observed in the spectra of the young bee and it appears as a baseline shift in spectra of some adult parts. The HF intensity of the abdomen is commonly one order of magnitude larger than any other body parts. This is the first systematic study on the conservation of magnetic material in all body parts of bees. The results show that the time evolution of the spectra depends on the body part, conserving solution and bee age. Further measurements are necessary to understand these effects and extend it to other social insects.

  5. Numerical simulations of mass outflows driven from accretion disks by radiation and magnetic forces

    E-print Network

    D. Proga

    2002-10-29

    We study the two-dimensional, time-dependent MHD of radiation-driven winds from luminous accretion disks initially threaded by a purely axial magnetic field. The radiation force is mediated primarily by spectral lines. We use ideal MHD to compute the evolution of Keplerian disks, varying the magnetic field strengths and the luminosity of the disk, the central accreting object or both. We find that the magnetic fields very quickly start deviating from purely axial due to the magnetorotational instability. This leads to fast growth of the toroidal magnetic field. As a result the toroidal field dominates over the poloidal field above the disk and the gradient of the former drives a slow and dense disk outflow, which conserves specific angular momentum. Depending on the strength of the magnetic field relative to the system luminosity the disk wind can be radiation- or MHD driven. The pure radiation-driven wind consists of a dense, slow outflow that is bounded on the polar side by a high-velocity stream. The mass-loss rate is mostly due to the fast stream. As the magnetic field strength increases first the slow part of the flow is affected, namely it becomes denser and slightly faster and begins to dominate the mass-loss rate. In very strong magnetic field or pure MHD cases, the wind consists of only a dense, slow outflow without the presence of the distinctive fast stream so typical to pure radiation-driven winds. Our simulations indicate that winds launched by the magnetic fields are likely to remain dominated by the fields downstream because of their relatively high densities.

  6. [A functional orthodontic magnetic appliance (FOMA) after Vardimon. 1. A three-dimensional analysis of the force system of the attractive magnets].

    PubMed

    Bourauel, C; Vardimon, A D; Drescher, D; Schmuth, G P

    1995-09-01

    The functional magnetic system (FMS) is a removable functional appliance which induces mandibular advance by means of mandibular and maxillary magnets in an attracting configuration. The maxillary and mandibular plates are each equipped with 2 cylindrically shaped cobalt-samarium magnets, 4 mm in diameter and 3 mm in height, which are welded into stainless steel housings. The force system of this magnetic configuration was analyzed using the orthodontic measurement and simulation system (OMSS). OMSS simulated the mandibular jaw movements by separating the installed magnets vertically, corresponding to a mouth opening of X = -10 mm, transversally (right excursion, +/left excursion, -) at Y = +/- 10 mm and sagittally (anterior displacement, +/posterior displacement, -) at Z = +/- 10 mm. The resulting 2D and 3D force/displacement diagrams elucidate the outstanding centripetal-spatial orientation characteristics of the functional magnetic appliance in reference to the full overlap brought about by the attraction of the mandibular magnet by the maxillary magnet. The maximum centripetal forces reached a value of approximately FY, max = 0.65 N for the vertical attracting force at full overlap of the mandibular and maxillary magnets (X = 0.55 mm, Y = Z = 0 mm), a value of FY, max = 0.65 N for the medial shearing force at a partial transversal overlap Z = 0, Y = +/- 2 mm and Y = +/- 6 mm), and for the sagittal shearing force a value of FZ, max = 1.2 N at a partial sagittal overlap of the magnets (Y = 0 mm, Z = +/- 2 mm).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7557800

  7. Gender differences in vestibular modulation of body mass in altered force environments

    NASA Astrophysics Data System (ADS)

    Fuller, Charles; Fuller, Patrick; Hoban-Higgins, Tana; Fuller, Charles

    Body mass regulation is affected by the gravitational environment. Gravitational and linear acceleration information is transduced by the vestibular macular receptors. In addition, there are gender differences in the regulation of body mass and composition. This study therefore investigated the role of the vestibular system in the regulation of body mass in age-matched male and female rats. Four groups of male and female rats were established. A 1G and a 2G labyrinthectomized experimental group (Labx) and a 1G and 2G control group (Con). Labyrinthectomies were accomplished by trans-tympanic injection of sodium arsanilate to remove vestibular input. Control groups experienced the same surgical procedures, but with a saline control injection. Body mass and food and water consumption data were collected twice weekly. Baseline data were collected prior to surgery. There was a decrease in body mass following chemical labyrinthectomy in both male and female rats. A recovery period followed surgery to allow for the re-establishment of stable growth curves. Body mass of female experimental rats returned to the same levels as the female controls while male labyrinthectomized rats continued to regulate body mass at a lower level. All 2G groups were exposed to 8 weeks of 2G produced via centrifugation while all control groups remained at 1G. All 2G groups decreased body mass at the onset of centrifugation, with experimental groups having a smaller response than the controls. Males continued to maintain body mass at a lower level under 2G, while, again body mass of the females returned to levels similar to controls. At the conclusion of the eight week centrifugation period, all four female groups had a similar body mass while differences were evident between male groups. Overall, 1G males had a higher body mass than did males exposed to 2G. Within G levels, 1G controls were heavier than 1G Labx and, in contrast, at 2G Labx had a larger body mass than controls. (Supported by NASA Grant NNA07CN33G.)

  8. Towards an on-chip platform for the controlled application of forces via magnetic particles: A novel device for mechanobiology

    NASA Astrophysics Data System (ADS)

    Monticelli, M.; Albisetti, E.; Petti, D.; Conca, D. V.; Falcone, M.; Sharma, P. P.; Bertacco, R.

    2015-05-01

    In-vitro tests and analyses are of fundamental importance for investigating biological mechanisms in cells and bio-molecules. The controlled application of forces to activate specific bio-pathways and investigate their effects, mimicking the role of the cellular environment, is becoming a prominent approach in this field. In this work, we present a non-invasive magnetic on-chip platform which allows for the manipulation of magnetic particles, through micrometric magnetic conduits of Permalloy patterned on-chip. We show, from simulations and experiments, that this technology permits to exert a finely controlled force on magnetic beads along the chip surface. This force can be tuned from few to hundreds pN by applying a variable external magnetic field.

  9. Current sheet formation in a sheared force-free-magnetic field. [in sun

    NASA Technical Reports Server (NTRS)

    Wolfson, Richard

    1989-01-01

    This paper presents the results of a study showing how continuous shearing motion of magnetic footpoints in a tenuous, infinitely conducting plasma can lead to the development of current sheets, despite the absence of such sheets or even of neutral points in the initial state. The calculations discussed here verify the earlier suggestion by Low and Wolfson (1988) that extended current sheets should form due to the shearing of a force-free quadrupolar magnetic field. More generally, this work augments earlier studies suggesting that the appearance of discontinuities - current sheets - may be a necessary consequence of the topological invariance imposed on the magnetic field geometry of an ideal MHD system by virtue of its infinite conductivity. In the context of solar physics, the work shows how the gradual and continuous motion of magnetic footpoints at the solar photosphere may lead to the buildup of magnetic energy that can then be released explosively when finite conductivity effects become important and lead to the rapid dissipation of current sheets. Such energy release may be important in solar flares, coronal mass ejections, and other eruptive events.

  10. Multiple degree-of-freedom force and moment measurement for static propulsion testing using magnetic suspension technology

    NASA Technical Reports Server (NTRS)

    Stuart, Keith; Bartosh, Blake

    1993-01-01

    Innovative Information Systems (IIS), Inc. is in the process of designing and fabricating a high bandwidth force and moment measuring device (i.e. the Magnetic Thruster Test Stand). This device will use active magnetic suspension to allow direct measurements of the forces and torques generated by the rocket engines of the missile under test. The principle of operation of the Magnetic Thruster Test Stand (MTTS) is based on the ability to perform very precise, high bandwidth force and position measurements on an object suspended in a magnetic field. This ability exists due to the fact that the digital servo control mechanism that performs the magnetic suspension uses high bandwidth (10 kHz) position data (via an eddy-current proximity sensor) to determine the amount of force required to maintain stable suspension at a particular point. This force is converted into required electromagnet coil current, which is then output to a current amplifier driving the coils. A discussion of how the coil current and magnetic gap distance (the distance between the electromagnet and the object being suspended) is used to determine the forces being applied from the suspended assembly is presented.

  11. Multiple degree-of-freedom force and moment measurement for static propulsion testing using magnetic suspension technology

    NASA Astrophysics Data System (ADS)

    Stuart, Keith; Bartosh, Blake

    Innovative Information Systems (IIS), Inc. is in the process of designing and fabricating a high bandwidth force and moment measuring device (i.e. the Magnetic Thruster Test Stand). This device will use active magnetic suspension to allow direct measurements of the forces and torques generated by the rocket engines of the missile under test. The principle of operation of the Magnetic Thruster Test Stand (MTTS) is based on the ability to perform very precise, high bandwidth force and position measurements on an object suspended in a magnetic field. This ability exists due to the fact that the digital servo control mechanism that performs the magnetic suspension uses high bandwidth (10 kHz) position data (via an eddy-current proximity sensor) to determine the amount of force required to maintain stable suspension at a particular point. This force is converted into required electromagnet coil current, which is then output to a current amplifier driving the coils. A discussion of how the coil current and magnetic gap distance (the distance between the electromagnet and the object being suspended) is used to determine the forces being applied from the suspended assembly is presented.

  12. Lean body mass correction of standardized uptake value in simultaneous whole-body positron emission tomography and magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Jochimsen, Thies H.; Schulz, Jessica; Busse, Harald; Werner, Peter; Schaudinn, Alexander; Zeisig, Vilia; Kurch, Lars; Seese, Anita; Barthel, Henryk; Sattler, Bernhard; Sabri, Osama

    2015-06-01

    This study explores the possibility of using simultaneous positron emission tomography—magnetic resonance imaging (PET-MRI) to estimate the lean body mass (LBM) in order to obtain a standardized uptake value (SUV) which is less dependent on the patients' adiposity. This approach is compared to (1) the commonly-used method based on a predictive equation for LBM, and (2) to using an LBM derived from PET-CT data. It is hypothesized that an MRI-based correction of SUV provides a robust method due to the high soft-tissue contrast of MRI. A straightforward approach to calculate an MRI-derived LBM is presented. It is based on the fat and water images computed from the two-point Dixon MRI primarily used for attenuation correction in PET-MRI. From these images, a water fraction was obtained for each voxel. Averaging over the whole body yielded the weight-normalized LBM. Performance of the new approach in terms of reducing variations of 18F-Fludeoxyglucose SUVs in brain and liver across 19 subjects was compared with results using predictive methods and PET-CT data to estimate the LBM. The MRI-based method reduced the coefficient of variation of SUVs in the brain by 41??± 10% which is comparable to the reduction by the PET-CT method (35??± 10%). The reduction of the predictive LBM method was 29??± 8%. In the liver, the reduction was less clear, presumably due to other sources of variation. In conclusion, employing the Dixon data in simultaneous PET-MRI for calculation of lean body mass provides a brain SUV which is less dependent on patient adiposity. The reduced dependency is comparable to that obtained by CT and predictive equations. Therefore, it is more comparable across patients. The technique does not impose an overhead in measurement time and is straightforward to implement.

  13. Force-free magnetic fields - Is there a 'loss of equilibrium'?

    NASA Technical Reports Server (NTRS)

    Klimchuk, J. A.; Sturrock, P. A.

    1989-01-01

    This paper examines concept in solar physics that is known as loss of equilibrium in which a sequence of force-free magnetic fields, said to represent a possible quasi-static evolution of solar magnetic fields, reaches a critical configuration beyond which no acceptable solution of the prescribed form exists. This concept is used to explain eruptive phenomena ranging from solar flares to coronal mass ejections. Certain sequences of force-free configurations are discussed that exhibit a loss of equilibrium, and it is argued that the concept is devoid of physical significance since each sequence is defined a way that does not represent an acceptable thought experiment. For example, the sequence may be defined in terms of a global constraint on the boundary conditions, or the evolution of the sequence may require the creation of mgnetic flux that is not connected to the photosphere and is not present in the original configuration. The global constraints typically occur in using the so-called generating function method. An acceptance thought experiment is proposed to specify the field configuration in terms of photospheric boundary conditions comprising the normal component of the field and the field-line connectivity. Consider a magnetic-field sequence that, when described in terms of a generating function, exhibits a loss of equilibrium and show that, when one instead defines the sequence in terms of the corresponding boundary conditions, the sequence is well behaved.

  14. Experimental studies in magnetically induced transverse force-frequency effect in thin quartz microresonators

    NASA Astrophysics Data System (ADS)

    Hatipoglu, Gokhan; Tadigadapa, Srinivas

    2015-07-01

    In this work, the transverse force-frequency sensitivity of magnetostrictive Metglas® (Fe85B5Si10) thin film coated AT-cut thickness shear mode quartz thin plate microresonator (500 ?m × 500 ?m × 19 ?m) is experimentally measured and modeled in Lagrangian formulation by coupling magnetostrictive deformation equations with the basic plate equations from the theory of small deformation. The quartz plate resonator is fabricated by micromachining techniques and released into fixed-free structure using focused ion beam milling. Application of a magnetic field results in the out-of-plane bending of the structure due to elastic coupling between the magnetostrictive Metglas® and quartz resonator layers. As a result of the transverse loading and out-of-plane bending, the admittance characteristics of the resonator shifts, and these shifts are recorded in real time utilizing a network analyzer. The sensitivity is experimentally measured to be 162.3 mdeg/Oe for phase, corresponding to a frequency sensitivity of ?f/H = 11 Hz/Oe. The equivalent force-frequency sensitivity can then be calculated as 2.36 ?N/Hz using the developed model. The coupled domain analysis fits well with the experimental data. Further reduction of quartz thickness and optimization of the thickness ratio of the magnetostrictive to quartz layers offers the possibility of exploiting the stress sensitivity of plate microresonators as sensitive magnetic field sensors capable of low nanoTesla to picoTesla level magnetic flux densities.

  15. The Outflows Accelerated by the Magnetic Fields and Radiation Force of Accretion Disks

    NASA Astrophysics Data System (ADS)

    Cao, Xinwu

    2014-03-01

    The inner region of a luminous accretion disk is radiation-pressure-dominated. We estimate the surface temperature of a radiation-pressure-dominated accretion disk, \\Theta =c_s^2/r^2\\Omega _K^2\\ll (H/r)^2, which is significantly lower than that of a gas-pressure-dominated disk, ? ~ (H/r)2. This means that the outflow can be launched magnetically from the photosphere of the radiation-pressure-dominated disk only if the effective potential barrier along the magnetic field line is extremely shallow or no potential barrier is present. For the latter case, the slow sonic point in the outflow will probably be in the disk, which leads to a slow circular dense flow above the disk. This implies that hot gas (probably in the corona) is necessary for launching an outflow from the radiation-pressure-dominated disk, which provides a natural explanation for the observational evidence that the relativistic jets are related to hot plasma in some X-ray binaries and active galactic nuclei. We investigate the outflows accelerated from the hot corona above the disk by the magnetic field and radiation force of the accretion disk. We find that with the help of the radiation force, the mass loss rate in the outflow is high, which leads to a slow outflow. This may be why the jets in radio-loud narrow-line Seyfert galaxies are in general mildly relativistic compared with those in blazars.

  16. Lorentz Force on Sodium and Chlorine Ions in a Salt Water Solution Flow under a Transverse Magnetic Field

    ERIC Educational Resources Information Center

    De Luca, R.

    2009-01-01

    It is shown that, by applying elementary concepts in electromagnetism and electrochemistry to a system consisting of salt water flowing in a thin rectangular pipe at an average velocity v[subscript A] under the influence of a transverse magnetic field B[subscript 0], an electromotive force generator can be conceived. In fact, the Lorentz force

  17. Rigid-body rotation of an electron cloud in divergent magnetic fields

    SciTech Connect

    Fruchtman, A.; Gueroult, R.; Fisch, N. J.

    2013-07-15

    For a given voltage across a divergent poloidal magnetic field, two electric potential distributions, each supported by a rigid-rotor electron cloud rotating with a different frequency, are found analytically. The two rotation frequencies correspond to the slow and fast rotation frequencies known in uniform plasma. Due to the centrifugal force, the equipotential surfaces, that correspond to the two electric potential distributions, diverge more than the magnetic surfaces do, the equipotential surfaces in the fast mode diverge largely in particular. The departure of the equipotential surfaces from the magnetic field surfaces may have a significant focusing effect on the ions accelerated by the electric field. The focusing effect could be important for laboratory plasma accelerators as well as for collimation of astrophysical jets.

  18. Dipolar spin echoes in magnetic resonance force microscopy C. L. Degen,* Q. Lin, and B. H. Meier

    E-print Network

    Leonardo, Degiorgi

    Dipolar spin echoes in magnetic resonance force microscopy C. L. Degen,* Q. Lin, and B. H. Meier time suspension pulse sequences based on the "magic echo." Two micron-sized single crystals of KPF6 s : 76.60.Lz, 68.37.Rt, 76.60.Pc Mechanical detection of nuclear magnetic resonance MRFM has resulted

  19. Dot-by-dot analysis of magnetization reversal in perpendicular patterned CoCrPt medium by using magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Bai, J.; Takahoshi, H.; Ito, H.; Saito, H.; Ishio, S.

    2004-07-01

    A dot-by-dot analysis to investigate the magnetization switching behavior of the perpendicular patterned CoCrPt medium is reported. The medium is investigated by in situ and ex situ magnetic force microscopy (MFM) techniques. The topographical and magnetic characteristics of each magnetic dot were studied in given areas. The perpendicular dc demagnetization (DCD) remanence data evaluated by counting the volume of reversed magnetic dots according to the ex situ MFM measurements were in good agreement with alternating gradient magnetometry measurements. The influence of the magnetostatic energy associated with nanodots to the distribution of the intrinsic coercivity of individual magnetic dots and the intrinsic DCD curve of the medium are estimated. Further, the mechanism of magnetization reversal of individual magnetic dot is discussed.

  20. Calculation of the linear force-free magnetic field above a solar active region

    NASA Astrophysics Data System (ADS)

    Abramenko, V. I.

    1997-08-01

    Modeling the linear force-free fields above solar active regions involves the use of either Fourier transforms or Green functions. The modeling results depend on the a priori conditions specified for the edges of the volume studied. However, none of the methods that have been developed allow direct specification of the values for the field at the nonphotospheric boundaries of the volume. A method that allows this would make it possible to study the influence of lateral boundary conditions on the solution inside the volume of interest and to use a priori information about the field in the corona. Here, an algorithm is presented for calculation of the linear force-free field in a limited volume (in the shape of a parallelepiped, Omega) using the distribution of the Bz component of the field at all boundaries of Omega and the distribution of Bx and Bv in a frame made up by the intersection of a lateral surface of Omega and a single arbitrarily chosen plane z = const. The algorithm is verified using a numerical model, permitting calculation of the linear force-free field of a dipole in a half-space using exact formulas. The rms deviation of the calculated and analytical solutions at each layer along the z axis does not exceed 1 percent. Substituting potential boundary conditions for force-free conditions at the nonphotospheric border of the Omega volume leads to a substantial change in the resulting magnetic configuration.

  1. Asymptotic forms for the energy of force-free magnetic field ion figurations of translational symmetry

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.; Antiochos, S. K.; Klinchuk, J. A.; Roumeliotis, G.

    1994-01-01

    It is known from computer calculations that if a force-free magnetic field configuration is stressed progressively by footpoint displacements, the configuration expands and approaches the open configuration with the same surface flux distribution and the energy of the field increases progressively. For configurations of translationalsymmetry, it has been found empirically that the energy tends asymptotically to a certain functional form. It is here shown that analysis of a simple model of the asymptotic form of force-free fields of translational symmetry leads to and therefore justifies this functional form. According to this model, the field evolves in a well-behaved manner with no indication of instability or loss of equilibrium.

  2. MeV scale leptonic force for cosmic neutrino spectrum and muon anomalous magnetic moment

    E-print Network

    Takeshi Araki; Fumihiro Kaneko; Toshihiko Ota; Joe Sato; Takashi Shimomura

    2015-08-29

    Characteristic patterns of cosmic neutrino spectrum reported by the IceCube collaboration and long-standing inconsistency between theory and experiment in muon anomalous magnetic moment are simultaneously explained by an extra leptonic force mediated by a gauge field with a mass of the MeV scale. With different assumptions for redshift distribution of cosmic neutrino sources, diffuse neutrino flux is calculated with the scattering between cosmic neutrino and cosmic neutrino background through the new leptonic force. Our analysis sheds light on a relation among lepton physics at the three different scales, PeV, MeV, and eV, and provides possible clues to the distribution of sources of cosmic neutrino and also to neutrino mass spectrum.

  3. The Influence of Lorentz Force on Vacuum Arc Behaviors with AN Axial Magnetic Field

    NASA Astrophysics Data System (ADS)

    Cho, S. H.; Lee, H. G.; Choi, M. J.; Kwon, J. R.; Kim, Y. J.

    The necessity of the vacuum interrupters (VIs) has been widely recognized on switching and controlling the fault currents in medium voltage level. An axial magnetic field (AMF) electrode has more advantages of the switching capability than other contact designs such as securing higher current value for transferring from the constriction arc to the diffuse. The heat flux and the local temperature on the electrode are increased by arc constriction, which is influenced by Lorentz force. It has undesirable influence on the characteristics of vacuum arc. In this study, we simulated the influence of Lorentz force on vacuum arc behaviors with an AMF electrode by using a commercial FEM package, ANSYS. The vacuum arc has been modeled with the sequential coupling method of two different fields, which are on the electromagnetic and thermal-flow. Arc constriction with various applied currents could be predicted with the results of temperature distribution.

  4. Effect of radiation forces on disk accretion by weakly magnetic neutron stars

    NASA Technical Reports Server (NTRS)

    Miller, M. C.; Lamb, Frederick K.

    1993-01-01

    Radiation forces are shown to be more important than general relativistic corrections to Newtonian gravitational forces in determining the motion of particles accreting onto a slowly rotating neutron star if the luminosity of the star is greater than about 1 percent of the Eddington critical luminosity (ECL). This is so even if the radius of the star is less than the radius of the innermost stable orbit. In particular, radiation drag causes matter accreting from a disk to lose angular momentum and spiral inward. At luminosities greater than about 0.2 ECL, a substantial fraction of the accreting matter can transfer most of its angular momentum and gravitational binding energy to the radiation field before reaching the stellar surface. These results have important implications for the X-ray spectra, time variability, and spin evolution of neutron stars with very weak magnetic fields and the prospects for detecting general relativistic effects near such stars.

  5. Design of a self-aligned, wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with 10 nm magnetic force microscope resolution

    SciTech Connect

    Karc?, Özgür; Dede, Münir

    2014-10-01

    We describe the design of a wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with a self-aligned fibre-cantilever mechanism. An alignment chip with alignment groves and a special mechanical design are used to eliminate tedious and time consuming fibre-cantilever alignment procedure for the entire temperature range. A low noise, Michelson fibre interferometer was integrated into the system for measuring deflection of the cantilever. The spectral noise density of the system was measured to be ~12 fm/?Hz at 4.2 K at 3 mW incident optical power. Abrikosov vortices in BSCCO(2212) single crystal sample and a high density hard disk sample were imaged at 10 nm resolution to demonstrate the performance of the system.

  6. Novel system for bite-force sensing and monitoring based on magnetic near field communication.

    PubMed

    Lantada, Andres Diaz; Bris, Carlos González; Morgado, Pilar Lafont; Maudes, Jesús Sanz

    2012-01-01

    Intraoral devices for bite-force sensing have several applications in odontology and maxillofacial surgery, as bite-force measurements provide additional information to help understand the characteristics of bruxism disorders and can also be of help for the evaluation of post-surgical evolution and for comparison of alternative treatments. A new system for measuring human bite forces is proposed in this work. This system has future applications for the monitoring of bruxism events and as a complement for its conventional diagnosis. Bruxism is a pathology consisting of grinding or tight clenching of the upper and lower teeth, which leads to several problems such as lesions to the teeth, headaches, orofacial pain and important disorders of the temporomandibular joint. The prototype uses a magnetic field communication scheme similar to low-frequency radio frequency identification (RFID) technology (NFC). The reader generates a low-frequency magnetic field that is used as the information carrier and powers the sensor. The system is notable because it uses an intra-mouth passive sensor and an external interrogator, which remotely records and processes information regarding a patient's dental activity. This permits a quantitative assessment of bite-force, without requiring intra-mouth batteries, and can provide supplementary information to polysomnographic recordings, current most adequate early diagnostic method, so as to initiate corrective actions before irreversible dental wear appears. In addition to describing the system's operational principles and the manufacture of personalized prototypes, this report will also demonstrate the feasibility of the system and results from the first in vitro and in vivo trials. PMID:23112669

  7. Novel System for Bite-Force Sensing and Monitoring Based on Magnetic Near Field Communication

    PubMed Central

    Lantada, Andres Diaz; Bris, Carlos González; Morgado, Pilar Lafont; Maudes, Jesús Sanz

    2012-01-01

    Intraoral devices for bite-force sensing have several applications in odontology and maxillofacial surgery, as bite-force measurements provide additional information to help understand the characteristics of bruxism disorders and can also be of help for the evaluation of post-surgical evolution and for comparison of alternative treatments. A new system for measuring human bite forces is proposed in this work. This system has future applications for the monitoring of bruxism events and as a complement for its conventional diagnosis. Bruxism is a pathology consisting of grinding or tight clenching of the upper and lower teeth, which leads to several problems such as lesions to the teeth, headaches, orofacial pain and important disorders of the temporomandibular joint. The prototype uses a magnetic field communication scheme similar to low-frequency radio frequency identification (RFID) technology (NFC). The reader generates a low-frequency magnetic field that is used as the information carrier and powers the sensor. The system is notable because it uses an intra-mouth passive sensor and an external interrogator, which remotely records and processes information regarding a patient's dental activity. This permits a quantitative assessment of bite-force, without requiring intra-mouth batteries, and can provide supplementary information to polysomnographic recordings, current most adequate early diagnostic method, so as to initiate corrective actions before irreversible dental wear appears. In addition to describing the system's operational principles and the manufacture of personalized prototypes, this report will also demonstrate the feasibility of the system and results from the first in vitro and in vivo trials. PMID:23112669

  8. A nonlinear eigenvalue problem for self-similar spherical force-free magnetic fields

    NASA Astrophysics Data System (ADS)

    Lerche, I.; Low, B. C.

    2014-10-01

    An axisymmetric force-free magnetic field B(r, ?) in spherical coordinates is defined by a function r sin ? B ? = Q ( A ) relating its azimuthal component to its poloidal flux-function A. The power law r sin ? B ? = a A | A | 1/ n, n a positive constant, admits separable fields with A = An/(?)rn, posing a nonlinear boundary-value problem for the constant parameter a as an eigenvalue and An(?) as its eigenfunction [B. C. Low and Y. Q Lou, Astrophys. J. 352, 343 (1990)]. A complete analysis is presented of the eigenvalue spectrum for a given n, providing a unified understanding of the eigenfunctions and the physical relationship between the field's degree of multi-polarity and rate of radial decay via the parameter n. These force-free fields, self-similar on spheres of constant r, have basic astrophysical applications. As explicit solutions they have, over the years, served as standard benchmarks for testing 3D numerical codes developed to compute general force-free fields in the solar corona. The study presented includes a set of illustrative multipolar field solutions to address the magnetohydrodynamics (MHD) issues underlying the observation that the solar corona has a statistical preference for negative and positive magnetic helicities in its northern and southern hemispheres, respectively; a hemispherical effect, unchanging as the Sun's global field reverses polarity in successive eleven-year cycles. Generalizing these force-free fields to the separable form B = H/(? ,?)rn+2 promises field solutions of even richer topological varieties but allowing for ?-dependence greatly complicates the governing equations that have remained intractable. The axisymmetric results obtained are discussed in relation to this generalization and the Parker Magnetostatic Theorem. The axisymmetric solutions are mathematically related to a family of 3D time-dependent ideal MHD solutions for a polytropic fluid of index ? = 4/3 as discussed in the Appendix.

  9. A continuum body force sensor designed for flexible surgical robotics devices.

    PubMed

    Noh, Yohan; Secco, Emanuele Lindo; Sareh, Sina; Wurdemann, Helge; Faragasso, Angela; Back, Junghwan; Liu, Hongbin; Sklar, Elizabeth; Althoefer, Kaspar

    2014-01-01

    This paper presents a novel three-axis force sensor based on optical photo interrupters and integrated with the robot arm STIFF-FLOP (STIFFness controllable Flexible and Learnable Manipulator for Surgical Operations) to measure external interacting forces and torques. The ring-shape bio-compatible sensor presented here embeds the distributed actuation and sensing system of the STIFF-FLOP manipulator and is applicable to the geometry of its structure as well to the structure of any other similar soft robotic manipulator. Design and calibration procedures of the device are introduced: experimental results allow defining a stiffness sensor matrix for real-time estimation of force and torque components and confirm the usefulness of the proposed optical sensing approach. PMID:25570797

  10. Outflow and plasma acceleration in Titan's induced magnetotail: Evidence of magnetic tension forces

    NASA Astrophysics Data System (ADS)

    Romanelli, N.; Modolo, R.; Dubinin, E.; Berthelier, J.-J.; Bertucci, C.; Wahlund, J. E.; Leblanc, F.; Canu, P.; Edberg, N. J. T.; Waite, H.; Kurth, W. S.; Gurnett, D.; Coates, A.; Dougherty, M.

    2014-12-01

    Cassini plasma wave and particle observations are combined with magnetometer measurements to study Titan's induced magnetic tail. In this study, we report and analyze the plasma acceleration in Titan's induced magnetotail observed in flybys T17, T19, and T40. Radio and Plasma Wave Science observations show regions of cold plasma with electron densities between 0.1 and a few tens of electrons per cubic centimeter. The Cassini Plasma Spectrometer (CAPS)-ion mass spectrometer (IMS) measurements suggest that ionospheric plasma in this region is composed of ions with masses ranging from 15 to 17 amu and from 28 to 31 amu. From these measurements, we determine the bulk velocity of the plasma and the Alfvén velocity in Titan's tail region. Finally, a Walén test of such measurements suggest that the progressive acceleration of the ionospheric plasma shown by CAPS can be interpreted in terms of magnetic tension forces.

  11. Measurement and calculation of levitation forces between magnets and granular superconductors

    NASA Astrophysics Data System (ADS)

    Johansen, T. H.; Bratsberg, H.; Baziljevich, M.; Hetland, P. O.; Riise, A. B.

    1995-04-01

    Recent developments indicate that exploitation of the phenomenon of magnetic levitation may become one of the most important near-term applications of high-T(sub c) superconductivity. Because of this, the interaction between a strong permanent magnet(PM) and bulk high-T(sub c) superconductor (HTSC) is currently a subject of much interest. We have studied central features of the mechanics of PM-HTSC systems of simple geometries. Here we report experimental results for the components of the levitation force, their associated stiffness and mechanical ac-loss. To analyze the observed behavior a theoretical framework based on critical-state considerations is developed. It will be shown that all the mechanical properties can be explained consistently at a quantitative level wing a minimum of model parameters.

  12. Measurement and calculation of levitation forces between magnets and granular superconductors

    NASA Technical Reports Server (NTRS)

    Johansen, T. H.; Bratsberg, H.; Baziljevich, M.; Hetland, P. O.; Riise, A. B.

    1995-01-01

    Recent developments indicate that exploitation of the phenomenon of magnetic levitation may become one of the most important near-term applications of high-T(sub c) superconductivity. Because of this, the interaction between a strong permanent magnet(PM) and bulk high-T(sub c) superconductor (HTSC) is currently a subject of much interest. We have studied central features of the mechanics of PM-HTSC systems of simple geometries. Here we report experimental results for the components of the levitation force, their associated stiffness and mechanical ac-loss. To analyze the observed behavior a theoretical framework based on critical-state considerations is developed. It will be shown that all the mechanical properties can be explained consistently at a quantitative level wing a minimum of model parameters.

  13. Measurement and calculation of levitation forces between magnets and granular superconductors

    SciTech Connect

    Johansen, T.H.; Bratsberg, H.; Baziljevich, M.; Hetland, P.O.; Riise, A.B.

    1995-04-01

    Recent developments indicate that exploitation of the phenomenon of magnetic levitation may become one of the most important near-term applications of high-T{sub c} superconductivity. Because of this, the interaction between a strong permanent magnet (PM) and bulk high-T{sub c} superconductor (HTSC) is currently a subject of much interest. The authors have studied central features of the mechanics of PM-HTSC systems of simple geometries. Here they report experimental results for the components of the levitation force, their associated stiffness and mechanical ac-loss. To analyze the observed behavior a theoretical framework based on critical-state considerations is developed. It will be shown that all the mechanical properties can be explained consistently at a quantitative level using a minimum of model parameters.

  14. Optical Characterization of Lorentz Force Based CMOS-MEMS Magnetic Field Sensor.

    PubMed

    Dennis, John Ojur; Ahmad, Farooq; Khir, M Haris Bin Md; Bin Hamid, Nor Hisham

    2015-01-01

    Magnetic field sensors are becoming an essential part of everyday life due to the improvements in their sensitivities and resolutions, while at the same time they have become compact, smaller in size and economical. In the work presented herein a Lorentz force based CMOS-MEMS magnetic field sensor is designed, fabricated and optically characterized. The sensor is fabricated by using CMOS thin layers and dry post micromachining is used to release the device structure and finally the sensor chip is packaged in DIP. The sensor consists of a shuttle which is designed to resonate in the lateral direction (first mode of resonance). In the presence of an external magnetic field, the Lorentz force actuates the shuttle in the lateral direction and the amplitude of resonance is measured using an optical method. The differential change in the amplitude of the resonating shuttle shows the strength of the external magnetic field. The resonance frequency of the shuttle is determined to be 8164 Hz experimentally and from the resonance curve, the quality factor and damping ratio are obtained. In an open environment, the quality factor and damping ratio are found to be 51.34 and 0.00973 respectively. The sensitivity of the sensor is determined in static mode to be 0.034 µm/mT when a current of 10 mA passes through the shuttle, while it is found to be higher at resonance with a value of 1.35 µm/mT at 8 mA current. Finally, the resolution of the sensor is found to be 370.37 µT. PMID:26225972

  15. Optical Characterization of Lorentz Force Based CMOS-MEMS Magnetic Field Sensor

    PubMed Central

    Dennis, John Ojur; Ahmad, Farooq; Khir, M. Haris Bin Md; Hamid, Nor Hisham Bin

    2015-01-01

    Magnetic field sensors are becoming an essential part of everyday life due to the improvements in their sensitivities and resolutions, while at the same time they have become compact, smaller in size and economical. In the work presented herein a Lorentz force based CMOS-MEMS magnetic field sensor is designed, fabricated and optically characterized. The sensor is fabricated by using CMOS thin layers and dry post micromachining is used to release the device structure and finally the sensor chip is packaged in DIP. The sensor consists of a shuttle which is designed to resonate in the lateral direction (first mode of resonance). In the presence of an external magnetic field, the Lorentz force actuates the shuttle in the lateral direction and the amplitude of resonance is measured using an optical method. The differential change in the amplitude of the resonating shuttle shows the strength of the external magnetic field. The resonance frequency of the shuttle is determined to be 8164 Hz experimentally and from the resonance curve, the quality factor and damping ratio are obtained. In an open environment, the quality factor and damping ratio are found to be 51.34 and 0.00973 respectively. The sensitivity of the sensor is determined in static mode to be 0.034 µm/mT when a current of 10 mA passes through the shuttle, while it is found to be higher at resonance with a value of 1.35 µm/mT at 8 mA current. Finally, the resolution of the sensor is found to be 370.37 µT. PMID:26225972

  16. Effect of size and geometry on levitation force measurements between permanent magnets and high-temperature superconductors

    SciTech Connect

    Cha, Y.S.; Hull, J.R.; Mulcahy, T.M.; Rossing, T.D. Northern Illinois Univ., De Kalb, IL . Dept. of Physics)

    1991-01-01

    A series of experiments measuring the levitation force between a permanent magnet (PM) and a high temperature superconductor (HTS) and between pairs of PMs, coupled with finite-element analysis of the experiments, has identified factors that influence the levitation force. The self demagnetizing factor within the HTS and, to some extent, within the PM has a profound effect on magnetic pressure. For large HTSs with strong flux-pinning, the demagnetizing effect of the diamagnetic image of the PM is substantial. For short distances between the HTS and PM, compression of magnetic flux produces a dependence on PM diameter. 8 refs.

  17. Sub-surface characterization and three dimensional profiling of semiconductors by magnetic resonance force microscopy

    SciTech Connect

    Hammel, P.C.; Moore, G.; Roukes, M.; Zhenyong Zhang

    1996-10-01

    This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project successfully developed a magnetic resonance force microscope (MRFM) instrument to mechanically detect magnetic resonance signals. This technique provides an intrinsically subsurface, chemical-species-specific probe of structure, constituent density and other properties of materials. As in conventional magnetic resonance imaging (MRI), an applied magnetic field gradient selects a well defined volume of the sample for study. However mechanical detection allows much greater sensitivity, and this in turn allows the reduction of the size of the minimum resolvable volume. This requires building an instrument designed to achieve nanometer-scale resolution at buried semiconductor interfaces. High-resolution, three-dimensional depth profiling of semiconductors is critical in the development and fabrication of semiconductor devices. Currently, there is no capability for direct, high-resolution observation and characterization of dopant density, and other critical features of semiconductors. The successful development of MRFM in conjunction with modifications to improve resolution will enable for the first time detailed structural and electronic studies in doped semiconductors and multilayered nanoelectronic devices, greatly accelerating the current pace of research and development.

  18. A Nuclear Magnetic Resonance Force Microscope for Micron-scale Liquids

    NASA Astrophysics Data System (ADS)

    Giraldo, Felipe; Paster, Jeremy W.; Tennant, Daniel M.; Markert, John T.

    2015-03-01

    We have designed and constructed a Nuclear Magnetic Resonance Force Microscopy (NMRFM) probe for the analysis of liquid and soft matter samples. This NRMFM probe uses a magnet-on-cantilever geometry and is equipped with dual x- y- z piezoelectric motion stages, for micron-step coarse positioning and sub-nanometer fine positioning of both the laser interferometer and the sample with respect to the cantilever, permitting three-dimensional scanning-mode detection of nuclear magnetism. The probe keeps the cantilever detector in high vacuum, maintaining a high Q, while the local NMR properties of nearby aqueous samples in glass microtubes are measured. The entire probe head fits in either a 3.5-cm bore magnet or in an electromagnet with a similarly small gap. We plan to demonstrate the ability to scan and distinguish microscale NMR properties using a copper sulfate solution with concentrations in the 2-20 millimolar range, thus providing dynamical imaging of regions with differing longitudinal relaxation times, T1. This concentration range will permit us to compare the conventional saturation-recovery pulse sequence with a more efficient single-pulse detection, possible when T1 is comparable to or less than the duration of the modified cyclic-adiabatic-inversion pulse.

  19. Wearable Ballistocardiography: Preliminary Methods for Mapping Surface Vibration Measurements to Whole Body Forces

    PubMed Central

    Wiens, Andrew; Etemadi, Mozziyar; Klein, Liviu; Roy, Shuvo; Inan, Omer T.

    2015-01-01

    The recent resurgence of ballistocardiogram (BCG) measurement and interpretation technologies has led to a wide range of powerful tools available for unobtrusively assessing mechanical aspects of cardiovascular health at home. Researchers have demonstrated a multitude of modern BCG measurement modalities, including beds, chairs, weighing scales, and wearable approaches. However, many modalities produce significant variations in the morphology of the measured BCG, creating confusion in the analysis and interpretation of the signals. This paper creates a framework for comparing wearable BCG measurements to whole body measurements—such as taken with a weighing scale system—to eventually allow the same analysis and interpretation tools that have been developed for whole body systems to be applied in the future to wearable systems. To the best of our knowledge, it represents the first attempt to morphologically compare vertical acceleration recordings measured on different locations on the torso to whole body displacements measured by BCG instrumentation. PMID:25571158

  20. Wearable ballistocardiography: preliminary methods for mapping surface vibration measurements to whole body forces.

    PubMed

    Wiens, Andrew; Etemadi, Mozziyar; Klein, Liviu; Roy, Shuvo; Inan, Omer T

    2014-01-01

    The recent resurgence of ballistocardiogram (BCG) measurement and interpretation technologies has led to a wide range of powerful tools available for unobtrusively assessing mechanical aspects of cardiovascular health at home. Researchers have demonstrated a multitude of modern BCG measurement modalities, including beds, chairs, weighing scales, and wearable approaches. However, many modalities produce significant variations in the morphology of the measured BCG, creating confusion in the analysis and interpretation of the signals. This paper creates a framework for comparing wearable BCG measurements to whole body measurements--such as taken with a weighing scale system--to eventually allow the same analysis and interpretation tools that have been developed for whole body systems to be applied in the future to wearable systems. To the best of our knowledge, it represents the first attempt to morphologically compare vertical acceleration recordings measured on different locations on the torso to whole body displacements measured by BCG instrumentation. PMID:25571158

  1. Changes in the nanoparticle aggregation rate due to the additional effect of electrostatic and magnetic forces on mass transport coefficients.

    PubMed

    Rosická, Dana; Sembera, Jan

    2013-01-01

    : The need may arise to be able to simulate the migration of groundwater nanoparticles through the ground. Transportation velocities of nanoparticles are different from that of water and depend on many processes that occur during migration. Unstable nanoparticles, such as zero-valent iron nanoparticles, are especially slowed down by aggregation between them. The aggregation occurs when attracting forces outweigh repulsive forces between the particles. In the case of iron nanoparticles that are used for remediation, magnetic forces between particles contribute to attractive forces and nanoparticles aggregate rapidly. This paper describes the addition of attractive magnetic forces and repulsive electrostatic forces between particles (by 'particle', we mean both single nanoparticles and created aggregates) into a basic model of aggregation which is commonly used. This model is created on the basis of the flow of particles in the proximity of observed particles that gives the rate of aggregation of the observed particle. By using a limit distance that has been described in our previous work, the flow of particles around one particle is observed in larger spacing between the particles. Attractive magnetic forces between particles draw the particles into closer proximity and result in aggregation. This model fits more closely with rapid aggregation which occurs between magnetic nanoparticles. PMID:23302651

  2. Emerging Technologies | Juried Work 69 Kinesthetic stimulations, produced by forces exerted on the body,

    E-print Network

    Tachi, Susumu

    a heavy object, its weight pro- duces torques in the wrist, elbow, and shoulder joint. Each muscle generates a torque at a joint that is the product of its contractile force and its moment arm at that joint. The idea behind FlexTorque is to reproduce human muscle structures that allow us to perform dexterous

  3. Dynamics of a Longitudinally Forced, Bluff Body Stabilized Flame Dong-Hyuk Shin,

    E-print Network

    Lieuwen, Timothy C.

    velocities from 38 to 170 m=s. These data show that the flame-front response at the acoustic forcing of flame-front wrinkles by the oscillating velocity, 3) interference of wrinkles on the flame front, and 4 SL = laminar flame speed ST = turbulent flame speed t = time u = flow velocity in the x-direction u0

  4. Magnetically operated check valve

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (inventor); Bozeman, Richard J., Jr. (inventor)

    1994-01-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  5. Many-body dispersion forces of polarizable clusters and liquids J Caoa) and B J Berne

    E-print Network

    Berne, Bruce J.

    It is now well known that the surface tension predicted by a pairwise additive potential of the Lennard- Jones (12-6) [L-J ( 12-6)] form gives surface tensions in error by as much as 50%. In this case the use of the Axilrod-Teller three-body potential corrects the surface tension. ' Hoare and Pal3 have determined

  6. Superadiabatic Forces in Brownian Many-Body Dynamics Andrea Fortini,1

    E-print Network

    Schmidt, Matthias

    evolution of the one-body density of Brownian particles. Within this approach one makes the assumption qualitative features of the density evolution. Recent applications include the study of active colloidal,7,15], the theory is qualitatively wrong for either strongly confined systems or high density states around

  7. Analysis of adipose tissue distribution using whole-body magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Wald, Diana; Schwarz, Tobias; Dinkel, Julien; Delorme, Stefan; Teucher, Birgit; Kaaks, Rudolf; Meinzer, Hans-Peter; Heimann, Tobias

    2011-03-01

    Obesity is an increasing problem in the western world and triggers diseases like cancer, type two diabetes, and cardiovascular diseases. In recent years, magnetic resonance imaging (MRI) has become a clinically viable method to measure the amount and distribution of adipose tissue (AT) in the body. However, analysis of MRI images by manual segmentation is a tedious and time-consuming process. In this paper, we propose a semi-automatic method to quantify the amount of different AT types from whole-body MRI data with less user interaction. Initially, body fat is extracted by automatic thresholding. A statistical shape model of the abdomen is then used to differentiate between subcutaneous and visceral AT. Finally, fat in the bone marrow is removed using morphological operators. The proposed method was evaluated on 15 whole-body MRI images using manual segmentation as ground truth for adipose tissue. The resulting overlap for total AT was 93.7% +/- 5.5 with a volumetric difference of 7.3% +/- 6.4. Furthermore, we tested the robustness of the segmentation results with regard to the initial, interactively defined position of the shape model. In conclusion, the developed method proved suitable for the analysis of AT distribution from whole-body MRI data. For large studies, a fully automatic version of the segmentation procedure is expected in the near future.

  8. Effects of a Circulating-water Garment and Forced-air Warming on Body Heat Content and Core Temperature

    PubMed Central

    Taguchi, Akiko; Ratnaraj, Jebadurai; Kabon, Barbara; Sharma, Neeru; Lenhardt, Rainer; Sessler, Daniel I.

    2005-01-01

    Background: Forced-air warming is sometimes unable to maintain perioperative normothermia. We therefore compared heat transfer, regional heat distribution, and core rewarming of forced-air warming with a novel circulating-water garment. Methods: Nine volunteers were each evaluated on two randomly ordered study days. They were anesthetized and cooled to a core temperature near 34°C. The volunteers were subsequently warmed for 2.5 hours with either a circulating-water garment or forced-air cover. Overall, heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Average arm and leg (peripheral) tissue temperatures were determined from 18 intramuscular needle thermocouples, 15 skin thermal flux transducers, and “deep” arm and foot thermometers. Results: Heat production (? 60 kcal/h) and loss (?45 kcal/h) were similar with each treatment before warming. The increase in heat transfer across anterior portions of the skin surface was similar with each warming system (?65 kcal/h). Forced-air warming had no effect on posterior heat transfer whereas circulating-water transferred 21 ± 9 kcal/h through the posterior skin surface after a half hour of warming. Over 2.5 h, circulating-water thus increased body heat content 56% more than forced air. Core temperatures thus increased faster than with circulating water than forced air, especially during the first hour, with the result that core temperature was 1.1 ± 0.7°C greater after 2.5 h (P < 0.001). Peripheral tissue heat content increased twice as much as core heat content with each device, but the core-to-peripheral tissue temperature gradient remained positive throughout the study. Conclusions: The circulating-water system transferred more heat than forced air, with the difference resulting largely from posterior heating. Circulating water rewarmed patients 0.4°C/h faster than forced air. A substantial peripheral-to-core tissue-temperature gradient with each device indicated that peripheral tissues insulated the core, thus slowing heat transfer. PMID:15114200

  9. A force calibration standard for magnetic tweezers Zhongbo Yu, David Dulin, Jelmer Cnossen, Mariana Kber, Maarten M. van Oene, Orkide Ordu, Bojk A.

    E-print Network

    Dekker, Nynke

    A force calibration standard for magnetic tweezers Zhongbo Yu, David Dulin, Jelmer Cnossen, Mariana and experimental analysis of the forced LacI-AraC oscillator with a minimal gene regulatory model Chaos 23, 025109 (2013); 10.1063/1.4809786 High-force NdFeB-based magnetic tweezers device optimized for microrheology

  10. Nonlinear force-free extrapolation of the coronal magnetic field based on the magnetohydrodynamic relaxation method

    SciTech Connect

    Inoue, S.; Magara, T.; Choe, G. S.; Kim, K. S.; Pandey, V. S.; Shiota, D.; Kusano, K.

    2014-01-01

    We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially proposed by Dedner et al. to effectively clean the numerical errors associated with ? · B . Second, the multigrid type method is implemented in our NLFFF to perform direct analysis of the high-resolution magnetogram data. As a result of these two implementations, we successfully extrapolated the high resolution force-free field introduced by Low and Lou with better accuracy in a drastically shorter time. We also applied our extrapolation method to the MHD solution obtained from the flux-emergence simulation by Magara. We found that NLFFF extrapolation may be less effective for reproducing areas higher than a half-domain, where some magnetic loops are found in a state of continuous upward expansion. However, an inverse S-shaped structure consisting of the sheared and twisted loops formed in the lower region can be captured well through our NLFFF extrapolation method. We further discuss how well these sheared and twisted fields are reconstructed by estimating the magnetic topology and twist quantitatively.

  11. Resonant Vibrations of Bluff Bodies Cause Multivortex Shedding and High Frequency Forces J. M. Dahl,* F. S. Hover, and M. S. Triantafyllou

    E-print Network

    Dong, Suchuan "Steven"

    Resonant Vibrations of Bluff Bodies Cause Multivortex Shedding and High Frequency Forces J. M. Dahl frequency, the lift (transverse) force contains a dominant fluctuating component with the vortex-shedding with half the vortex-shedding period. Vortex formation locks on to the frequency of cylinder vibration

  12. On Fully Developed Channel Flows: Some Solutions and Limitations, and Effects of Compressibility, Variable Properties, and Body Forces

    NASA Technical Reports Server (NTRS)

    Maslen, Stephen H.

    1959-01-01

    An examination of the effects of compressibility, variable properties, and body forces on fully developed laminar flow has indicated several limitations on such streams. In the absence of a pressure gradient, but presence of a body force (e.g., gravity), an exact fully developed gas flow results. For a liquid this follows also for the case of a constant streamwise pressure gradient. These motions are exact in the sense of a Couette flow. In the liquid case two solutions (not a new result) can occur for the same boundary conditions. An approximate analytic solution was found which agrees closely with machine calculations.In the case of approximately exact flows, it turns out that for large temperature variations across the channel the effects of convection (due to, say, a wall temperature gradient) and frictional heating must be negligible. In such a case the energy and momentum equations are separated, and the solutions are readily obtained. If the temperature variations are small, then both convection effects and frictional heating can consistently be considered. This case becomes the constant-property incompressible case (or quasi-incompressible case for free-convection flows) considered by many authors. Finally there is a brief discussion of cases wherein streamwise variations of all quantities are allowed but only a such form that independent variables are separable. For the case where the streamwise velocity varies inversely as the square root distance along the channel a solution is given.

  13. Forced convection past a slender body in a saturated porous medium

    SciTech Connect

    Romero, L.A.

    1995-08-01

    The analysis presented in this paper was motivated by a groundwater velocity probe that is currently being designed at Sandia National Laboratories in Albuquerque, New Mexico. The probe under consideration is buried in the ground, and a constant flux of heat is supplied at the surface of the probe. Here, the author presents solutions for the temperature field due to Darcy flow past a slender body with a prescribed flux distribution embedded in a saturated porous medium. The results of the analysis are compared to both a perturbation analysis of low Peclet number flow past a prolate spheroid and to direct numerical simulations of the same problem. The slender body approximation is found to be in excellent agreement with these results.

  14. Current sheet scattering and ion isotropic boundary under 3-D empirical force-balanced magnetic field

    NASA Astrophysics Data System (ADS)

    Yue, Chao; Wang, Chih-Ping; Lyons, Larry; Liang, Jun; Donovan, Eric F.; Zaharia, Sorin G.; Henderson, Michael

    2014-10-01

    To determine statistically the extent to which current sheet scattering is sufficient to account for the observed ion isotropic boundaries (IBs) for <30 keV ions, we have computed IBs from our 3-D empirical force-balanced magnetic field, identified IBs in FAST observations, and investigated the model-observation consistency. We have found in both model and FAST results the same dependences of IB latitudes on magnetic local time, ion energy, Kp, and solar wind dynamic pressure (PSW) levels: IB moves to higher latitudes from midnight toward dawn/dusk and to lower latitudes as energy increases and as Kp or PSW increases. The model predicts well the observed energy dependence, and the modeled IB latitudes match fairly well with those from FAST for Kp = 0. As Kp increases, the latitude agreement at midnight remains good but a larger discrepancy is found near dusk. The modeled IBs at the equator are located around the earthward boundary of highly isotropic ions observed by Time History of Events and Macroscale Interactions during Substorms at midnight and postmidnight, but with some discrepancy near dusk under high Kp. Thus, our results indicate that current sheet scattering generally plays the dominant role. The discrepancies suggest the importance of pitch angle scattering by electromagnetic ion cyclotron waves, which occur more often from dusk to noon and are more active during higher Kp. The comparison with the observed IBs is better with our model than under the nonforce-balanced T89, indicating that using a forced-balanced model improves the description of the magnetic field configuration and reinforces our conclusions regarding the role of current sheet scattering.

  15. Magnetic Coupling and Relaxation at Interfaces Measured by Ferromagnetic Resonance Spectroscopy and Force Microscopy

    NASA Astrophysics Data System (ADS)

    Adur, Rohan

    The emergent field of spintronics, which utilizes the spin of the electron rather than the charge for information processing, relies on an understanding of interfaces and surfaces of ferromagnetic thin films. An interface between a ferromagnetic thin film and a neighboring material can be engineered to provide tuneable static and dynamic couplings, which manifest as effective fields on the ferromagnet. Ferromagnetic resonance (FMR) is a powerful spectroscopic technique for studying these effective fields and couplings. In addition, FMR has been used to generate a pure spin current at these interfaces, which allows for the transfer of angular momentum without an accompanying charge current. The technique of magnetic resonance force microscopy (MRFM) has allowed the study of spin dynamics at the nanometer scale and with sensitivity down to single electron spins in paramagnetic materials and it would be illuminating to use this technique to study the spin transport behavior near an interface. MRFM uses the field from a magnetic probe to define a sensitive slice in which the resonance condition is met. The combination of MRFM techniques with FMR spectroscopy has, until recently, been limited to the measurement of global properties of a sample due to strong spin-spin exchange interactions that lead to collective spin wave modes that are defined by the sample and not sensitive to the probe field. Recently, the negative dipole field from a high coercivity probe magnet has been used to strongly perturb the spin wave spectrum of metallic ferromagnetic films, resulting in the localization of precessing magnetization in the 'field well' of the probe magnet into discrete modes, analogous to the discrete modes of a particle in a quantum well. The localized nature of these modes enables their use as a local probe of magnetic properties, and this has been utilized in the demonstration of FMR imaging of a ferromagnetic thin film using ferromagnetic resonance force microscopy (FMRFM). In this thesis I shall demonstrate the use of FMR spectroscopy and FMRFM to study static and dynamic couplings in ferromagnetic materials with emphasis on interfaces. First, I introduce the basic concepts of ferromagnetic resonance and spin wave relaxation. Second, I present the results of using conventional FMR spectroscopy to study the tuneable static effective fields in a ferromagnet, which manifest as anisotropy fields that define the energy landscape and equilibrium direction of the magnetization. Third, I explore both dipolar and exchange couplings between magnetizations which are dynamic in nature, and only manifest when the magnetizations are precessing. Fourth, I demonstrate the use of FMRFM to observe the modification of localized modes in a ferromagnetic film engineered with a lateral interface. Fifth, I describe the design of an FMRFM microscope and management of spurious background effects in an FMRFM experiment. Sixth, I measure relaxation from the localized modes in an insulating ferromagnetic film, which reveal a size-dependent damping effect that was unexpected in an insulating system. This suggests that spin transport from the interface of the localized mode can dictate its relaxation, even in the absence of conduction electrons. Finally, I observe a frequency-independent linewidth broadening contribution that also depends on mode size and this may give a measure of the inhomogeneous fields within a ferromagnetic sample.

  16. Comment on ``London model for the levitation force between a horizontally oriented point magnetic dipole and superconducting sphere''

    NASA Astrophysics Data System (ADS)

    Lin, Qiong-Gui

    2007-01-01

    In a recent paper the magnetostatic boundary-value problem for a magnetic dipole with transverse direction in the presence of a superconducting sphere was solved in both cases when the London penetration depth is zero and finite. It was concluded that the levitation force on the transverse magnetic dipole is exactly half that for a magnetic dipole with radial direction. We show that this conclusion is incorrect in either case. In the former case it is due to an incorrect boundary condition. In the latter case it is caused by calculational errors. Corrected results are presented. The distribution of supercurrent and the associated magnetic moment are also calculated.

  17. Internal resonance in forced vibration of coupled cantilevers subjected to magnetic interaction

    NASA Astrophysics Data System (ADS)

    Chen, Li-Qun; Zhang, Guo-Ce; Ding, Hu

    2015-10-01

    Forced vibration is investigated for two elastically connected cantilevers, under harmonic base excitation. One of the cantilevers is with a tip magnet repelled by a magnet fixed on the base. The cantilevers are uniform viscoelastic beams constituted by the Kelvin model. The system is formulated as a set of two linear partial differential equations with nonlinear boundary conditions. The method of multiple scales is developed to analyze the effects of internal resonances on the steady-state responses to external excitations in the nonlinear boundary problem of the partial differential equations. In the presence of 2:1 internal resonance, both the first and the second primary resonances are examined in detail. The analytical frequency-amplitude response relationships are derived from the solvability conditions. It is found that the frequency-amplitude response curves reveal typical nonlinear phenomena such as jumping and hysteresis in both primary resonances as well as saturation in the second primary resonance. The frequency-amplitude response curves may be converted from hardening-type single-jumping to double-jumpings, and further to softening-type single-jumping by adjusting the distance between two magnets. It is also found that the unstable parts of the frequency-amplitude response curves correspond to quasi-periodic motions. The finite difference scheme is proposed to discretize both the temporal and the spatial variables, and thus the numerical solutions can be calculated. The analytical results are supported by the numerical solutions.

  18. CP-Violating Effect of the Th Nuclear Magnetic Quadrupole Moment: Accurate Many-Body Study of ThO

    E-print Network

    Titov, Anatoly

    CP-Violating Effect of the Th Nuclear Magnetic Quadrupole Moment: Accurate Many-Body Study of ThO L) and parity (P)-violating effect in 229 ThO is induced by the nuclear magnetic quadrupole moment. We perform nuclear and molecular calculations to express this effect in terms of the strength constants of T, P

  19. Solar Wind Effects on Atmospheres of the Weakly Magnetized Bodies: Mars, Titan and the Moon

    NASA Technical Reports Server (NTRS)

    Luhmann, Janet G.

    1996-01-01

    The atmospheres of planetary bodies without significant intrinsic magnetic fields exhibit unique features because they interact with the external plasma flows in their space environment. The plasma interactions also have the potential of altering the evolutionary paths of these atmospheres since the processes (such as ion pickup and sputtering) that lead to loss of constituents have effects unlike those of other escape mechanisms. This ongoing investigation has been concentrating on the characterization of the plasma interactions and the associated plasma physical escape processes at Mars and Titan. The results are relevant to both mission planning and interpretation of data from past and future Mars and Lunar missions, and to tour and mission operations planning for the Cassini Orbiter. The also contribute to our general understanding, from a comparative planetology standpoint, of the role that planetary magnetic field play in determining the state and fate of a planetary atmosphere.

  20. Ab initio many-body calculations of nucleon-4He scattering with three-nucleon forces

    E-print Network

    Guillaume Hupin; Joachim Langhammer; Petr Navrátil; Sofia Quaglioni; Angelo Calci; Robert Roth

    2013-08-12

    We extend the ab initio no-core shell model/resonating-group method to include three-nucleon (3N) interactions for the description of nucleon-nucleus collisions. We outline the formalism, give algebraic expressions for the 3N-force integration kernels, and discuss computational aspects of two alternative implementations. The extended theoretical framework is then applied to nucleon-4He scattering using similarity-renormalization-group (SRG) evolved nucleon-nucleon plus three-nucleon potentials derived from chiral effective field theory. We analyze the convergence properties of the calculated phase shifts and explore their dependence upon the SRG evolution parameter. We include up to six excited states of the 4He target and find significant effects from the inclusion of the chiral 3N force, e.g., it enhances the spin-orbit splitting between the 3/2- and 1/2- resonances and leads to an improved agreement with the phase shifts obtained from an accurate R-matrix analysis of the five-nucleon experimental data. We find remarkably good agreement with measured differential cross sections at various energies, while analyzing powers manifest larger deviations from experiment for certain energies and angles.

  1. EFFECT OF POLARIMETRIC NOISE ON THE ESTIMATION OF TWIST AND MAGNETIC ENERGY OF FORCE-FREE FIELDS

    SciTech Connect

    Tiwari, Sanjiv Kumar; Venkatakrishnan, P.; Gosain, Sanjay; Joshi, Jayant E-mail: pvk@prl.res.in E-mail: jayant@prl.res.in

    2009-07-20

    The force-free parameter {alpha}, also known as helicity parameter or twist parameter, bears the same sign as the magnetic helicity under some restrictive conditions. The single global value of {alpha} for a whole active region gives the degree of twist per unit axial length. We investigate the effect of polarimetric noise on the calculation of global {alpha} value and magnetic energy of an analytical bipole. The analytical bipole has been generated using the force-free field approximation with a known value of constant {alpha} and magnetic energy. The magnetic parameters obtained from the analytical bipole are used to generate Stokes profiles from the Unno-Rachkovsky solutions for polarized radiative transfer equations. Then we add random noise of the order of 10{sup -3} of the continuum intensity (I {sub c}) in these profiles to simulate the real profiles obtained by modern spectropolarimeters such as Hinode (SOT/SP), SVM (USO), ASP, DLSP, POLIS, and SOLIS etc. These noisy profiles are then inverted using a Milne-Eddington inversion code to retrieve the magnetic parameters. Hundred realizations of this process of adding random noise and polarimetric inversion is repeated to study the distribution of error in global {alpha} and magnetic energy values. The results show that (1) the sign of {alpha} is not influenced by polarimetric noise and very accurate values of global twist can be calculated, and (2) accurate estimation of magnetic energy with uncertainty as low as 0.5% is possible under the force-free condition.

  2. Decay Characteristics of Levitation Force of YBCO Bulk Exposed to AC Magnetic Field above NdFeB Guideway

    NASA Astrophysics Data System (ADS)

    Liu, Minxian; Lu, Yiyun; Wang, Suyu; Ma, Guangtong

    2011-04-01

    The superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the nonuniformity of the magnetic field along the movement direction above the NdFeB guideway is inevitable due to the assembly error and inhomogeneity of the material property of the NdFeB magnet. So it is required to study the characteristics of levitation force of the bulks affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we will study the characteristics of the levitation force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet is used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experimental results, it has found that the levitation force is decreasing with the application of the AC external magnetic field, and the decay increasing with the amplitude of the applied magnetic field and is almost independent of the frequency.

  3. Comparison between magnetic force microscopy and electron back-scatter diffraction for ferrite quantification in type 321 stainless steel.

    PubMed

    Warren, A D; Harniman, R L; Collins, A M; Davis, S A; Younes, C M; Flewitt, P E J; Scott, T B

    2015-01-01

    Several analytical techniques that are currently available can be used to determine the spatial distribution and amount of austenite, ferrite and precipitate phases in steels. The application of magnetic force microscopy, in particular, to study the local microstructure of stainless steels is beneficial due to the selectivity of this technique for detection of ferromagnetic phases. In the comparison of Magnetic Force Microscopy and Electron Back-Scatter Diffraction for the morphological mapping and quantification of ferrite, the degree of sub-surface measurement has been found to be critical. Through the use of surface shielding, it has been possible to show that Magnetic Force Microscopy has a measurement depth of 105-140 nm. A comparison of the two techniques together with the depth of measurement capabilities are discussed. PMID:25195013

  4. Magnetic Energy and Helicity Budgets in the Active-Region Solar Corona. I. Linear Force-Free Approximation

    E-print Network

    M. K. Georgoulis; Barry J. LaBonte

    2007-06-27

    We self-consistently derive the magnetic energy and relative magnetic helicity budgets of a three-dimensional linear force-free magnetic structure rooted in a lower boundary plane. For the potential magnetic energy we derive a general expression that gives results practically equivalent to those of the magnetic Virial theorem. All magnetic energy and helicity budgets are formulated in terms of surface integrals applied to the lower boundary, thus avoiding computationally intensive three-dimensional magnetic field extrapolations. We analytically and numerically connect our derivations with classical expressions for the magnetic energy and helicity, thus presenting a so-far lacking unified treatment of the energy/helicity budgets in the constant-alpha approximation. Applying our derivations to photospheric vector magnetograms of an eruptive and a noneruptive solar active regions, we find that the most profound quantitative difference between these regions lies in the estimated free magnetic energy and relative magnetic helicity budgets. If this result is verified with a large number of active regions, it will advance our understanding of solar eruptive phenomena. We also find that the constant-alpha approximation gives rise to large uncertainties in the calculation of the free magnetic energy and the relative magnetic helicity. Therefore, care must be exercised when this approximation is applied to photospheric magnetic field observations. Despite its shortcomings, the constant-alpha approximation is adopted here because this study will form the basis of a comprehensive nonlinear force-free description of the energetics and helicity in the active-region solar corona, which is our ultimate objective.

  5. An investigation of the accuracy in measuring the body center of pressure in a standing posture with a force plate.

    PubMed

    Mita, K; Akataki, K; Itoh, K; Nogami, H; Katoh, R; Ninomi, S; Watakabe, M; Suzuki, N

    1993-01-01

    It has been reported that accuracy in the measured point of force application depends on the position and magnitude of load. The aim of this study is to investigate the error in measuring the body center of pressure in a standing posture with a force plate and to improve the accuracy by proposing a correction algorithm. The measurement of the point of force application with a calibrated load demonstrated its co-ordinates, which were scaled down towards the zero co-ordinate and moved parallel relative to the true co-ordinates. This trend was exaggerated with any decrease in magnitude of the load. The root mean square (r.m.s.) and maximum of errors at light load of 10 kg were 10 and 18 mm in the X axis, and 6 and 12 mm in the Y axis, respectively. The error seems to result from such causes as (i) non-linearity of the load cell, (ii) deformation of the top plate due to load application and (iii) differences in characteristics among individual load cells, including amplifiers. A mathematical representation of the measured point of force application accounting for these causes of error has been made and an algorithm for estimating the true point at any magnitude of load with only one correction equation is proposed. Actual correction of the measured point demonstrated an expected improvement in the r.m.s. error to less than 1 mm at any magnitude of load greater than 10 kg and the validity of this algorithm was confirmed. PMID:8280668

  6. A nonlinear eigenvalue problem for self-similar spherical force-free magnetic fields

    SciTech Connect

    Lerche, I.; Low, B. C.

    2014-10-15

    An axisymmetric force-free magnetic field B(r, ?) in spherical coordinates is defined by a function r?sin??B{sub ?}=Q(A) relating its azimuthal component to its poloidal flux-function A. The power law r?sin??B{sub ?}=aA|A|{sup 1/n}, n a positive constant, admits separable fields with A=(A{sub n}(?))/(r{sup n}) , posing a nonlinear boundary-value problem for the constant parameter a as an eigenvalue and A{sub n}(?) as its eigenfunction [B. C. Low and Y. Q Lou, Astrophys. J. 352, 343 (1990)]. A complete analysis is presented of the eigenvalue spectrum for a given n, providing a unified understanding of the eigenfunctions and the physical relationship between the field's degree of multi-polarity and rate of radial decay via the parameter n. These force-free fields, self-similar on spheres of constant r, have basic astrophysical applications. As explicit solutions they have, over the years, served as standard benchmarks for testing 3D numerical codes developed to compute general force-free fields in the solar corona. The study presented includes a set of illustrative multipolar field solutions to address the magnetohydrodynamics (MHD) issues underlying the observation that the solar corona has a statistical preference for negative and positive magnetic helicities in its northern and southern hemispheres, respectively; a hemispherical effect, unchanging as the Sun's global field reverses polarity in successive eleven-year cycles. Generalizing these force-free fields to the separable form B=(H(?,?))/(r{sup n+2}) promises field solutions of even richer topological varieties but allowing for ?-dependence greatly complicates the governing equations that have remained intractable. The axisymmetric results obtained are discussed in relation to this generalization and the Parker Magnetostatic Theorem. The axisymmetric solutions are mathematically related to a family of 3D time-dependent ideal MHD solutions for a polytropic fluid of index ??=?4/3 as discussed in the Appendix.

  7. Three-body spin-orbit forces from chiral two-pion exchange

    E-print Network

    N. Kaiser

    2003-12-16

    Using chiral perturbation theory, we calculate the density-dependent spin-orbit coupling generated by the two-pion exchange three-nucleon interaction involving virtual $\\Delta$-isobar excitation. From the corresponding three-loop Hartree and Fock diagrams we obtain an isoscalar spin-orbit strength $F_{\\rm so}(k_f)$ which amounts at nuclear matter saturation density to about half of the empirical value of $90 $MeVfm$^5$. The associated isovector spin-orbit strength $G_{\\rm so}(k_f)$ comes out about a factor of 20 smaller. Interestingly, this three-body spin-orbit coupling is not a relativistic effect but independent of the nucleon mass $M$. Furthermore, we calculate the three-body spin-orbit coupling generated by two-pion exchange on the basis of the most general chiral $\\pi\\pi NN$-contact interaction. We find similar (numerical) results for the isoscalar and isovector spin-orbit strengths $F_{\\rm so}(k_f)$ and $G_{\\rm so}(k_f)$ with a strong dominance of the p-wave part of the $\\pi\\pi NN$-contact interaction and the Hartree contribution.

  8. Eruption triggering of giant magma bodies by internal versus external forcing: A rhyolite-MELTS study

    NASA Astrophysics Data System (ADS)

    Carley, T. L.; Gualda, G. A.; Ghiorso, M. S.; Miller, C. F.

    2012-12-01

    Silicic volcanism, particularly supereruptions, raises questions about the mechanisms by which magma bodies destabilize and erupt. Are external events necessary to initiate an eruption of a large silicic system, or is possible for internal processes (crystallization, volatile exsolution) to destabilize a system and drive it to erupt? If external triggers are critically important to prompting eruption, are all felsic magma bodies equally prone to erupt? To respond to these questions, we use rhyolite-MELTS (Gualda et al. 2012) to investigate the pre-eruptive chemical evolution and the resultant changes to physical properties of giant (super-eruptive) felsic magma bodies. Simulations are conducted using pumice and glass compositions from the Peach Spring (Southwestern USA) and the Bishop (California USA) Tuffs, two giant high-silica rhyolite deposits. In our simulations, we vary initial pressure (150-350 MPa in 50 MPa intervals), volatile content (initial water ranging from 1-7 wt. %), mode of crystallization (equilibrium vs. fractional), and rheology of the magma reservoir (isobaric vs. isochoric vs. transitional). We run simulations through as much of the crystallization interval as possible, but focus on the first ~50 wt. % crystallization, most relevant for volcanic systems. In all simulations, we observe near-invariant behavior when the system becomes saturated in quartz, two feldspars and a fluid phase, from which point crystallization is essentially isothermal. Prior to the near-invariant, crystallization leads to gradual changes in bulk properties (e.g., < 1% volume decrease over 50 °C), which effectively results in modest pressure changes within the magma body (i.e., ~10 MPa). Upon reaching the near-invariant, the bulk properties change abruptly (e.g., > 5% volume increase in 0.1 °C), causing significant overpressurization of the magma body. The magnitude of this overpressurization (i.e. 10s to 100s of MPa depending on system conditions) is sufficient to exceed the yield strength of the country rocks, effectively making eruption possible independent of any external triggers. Our simulations reveal that the Peach Spring and Bishop Tuff magmatic systems represent two contrasting types of behavior. In the Bishop case, only ~5-25 wt.% of crystallization over a short temperature interval (~30 °C cooling) is needed to reach near-invariant behavior, making it plausible that crystallization led to eruption without external triggers. This is consistent with the lack of evidence for interaction of Bishop magma with mafic magmas. In the Peach Spring case, 30-70 wt. % crystallization over a much longer temperature interval (~60-130 °C cooling) is needed for the system to reach the near-invariant. Given that Peach Spring pumice and fiamme are characterized by <30 wt. % crystals, it seems unlikely that crystallization alone led to eruption, suggesting the action of an external trigger in promoting eruption. This is consistent with evidence for significant heating and mush remobilization preserved in intracaldera Peach Spring rocks. Our results show that phase-equilibria constrains whether a magma system is likely to destabilize itself and erupt as a result of overpressurization by closed-system crystallization and volatile exsolution.

  9. A multipole accelerated desingularized method for computing nonlinear wave forces on bodies

    SciTech Connect

    Scorpio, S.M.; Beck, R.F.

    1996-12-31

    Nonlinear wave forces on offshore structures are investigated. The fluid motion is computed using an Euler-Lagrange time domain approach. Nonlinear free surface boundary conditions are stepped forward in time using an accurate and stable integration technique. The field equation with mixed boundary conditions that result at each time step are solved at N nodes using a desingularized boundary integral method with multipole acceleration. Multipole accelerated solutions require O(N) computational effort and computer storage while conventional solvers require O(N{sup 2}) effort and storage for an iterative solution and O(N{sup 3}) effort for direct inversion of the influence matrix. These methods are applied to the three dimensional problem of wave diffraction by a vertical cylinder.

  10. Analysis and parallel implementation of a forced N-body problem

    NASA Astrophysics Data System (ADS)

    Torres, C. E.; Parishani, H.; Ayala, O.; Rossi, L. F.; Wang, L.-P.

    2013-07-01

    The understanding of particle dynamics in N-body problems is of importance to many applications in astrophysics, molecular dynamics and cloud/plasma physics where the theoretical representation results in a coupled system of equations for a large number of entities. This paper concerns algorithms for solving a specific N-body problem, namely, a system of disturbance velocities for hydrodynamically interacting particles in a particle-laden turbulent flow. The system is derived from the improved superposition method of [1]. Targeting for scalable computations on petascale computers, we have carried out a thorough study of a parallel implementation of GMRes with different features, such as preconditioners, matrix-free and parallel sparse representation of the matrix through 1D and 2D spatial domain decompositions. Gauss-Seidel method is also studied as a reference iterative algorithm. The range of conditions for efficiency and failure of each method is discussed in detail. Through perturbation analysis, we have conducted a series of experiments to understand the effect of particle sizes, interaction symmetry, inter-particle distances and interaction truncation on the eigenvalues and normality of the linear system. For situations where the system is ill-conditioned, we introduce a restricted Schwarz type preconditioner. We verified the parallel efficiency of the preconditioner using 1D domain decomposition on a parallel machine. A benchmark problem of particle laden turbulence at 5123 resolution with 2×106 particles is studied to understand the scalability of the proposed methods on parallel machines. We have developed a stable and highly scalable parallel solver with an affordable computational cost even for ill-conditioned systems through preconditioning. On 64 cores, using GMRes in 2D domain decomposition, we achieved a speed-up of ˜5.6x (relative to 1D domain decomposition on the same number of processors). Our complexity analysis showed that for large N-body problems, the proposed GMRes scheme scales well for moderate to large number of processors in current tera to petascale computers.

  11. Numerical computation for a new way to reduce vibration and noise due to magnetostriction and magnetic forces of transformer cores

    NASA Astrophysics Data System (ADS)

    Zhu, Lihua; Yang, Qingxin; Yan, Rongge; Li, Yongjian; Zhang, Xian; Yan, Weili; Zhu, Jianguo

    2013-05-01

    Magnetostriction (MS) caused by the global magnetization of limbs and yokes and magnetic forces are the undisputed causes of the vibration and noise in power transformer cores. This paper presents a novel way to reduce the vibration and noise, in which nanocrystalline soft magnetic composite (NSMC) material with high permeability is used to fill the step-lap joint gaps of the power transformer magnetic cores. In order to numerically predict the effectiveness of the proposed method, a 3-D magneto-mechanical strong coupled model including MS and magnetic anisotropy of steel sheet was founded. Then, the numerical model was applied to analyze the step-lap joint region of the corner of magnetic cores. The analysis results illustrated that the deformation and noise of core with NSMC are lower than with the traditional epoxy damping material. Moreover, the validity of the proposed new way was verified by the simplified step-lap joint cores, which were achieved based on Epstein Frames.

  12. Design and Use of Capacitive Force Transducers for Superconducting Magnet Models for the LHC

    E-print Network

    Siegel, N; Vanenkov, I

    1998-01-01

    Capacitive force transducers have been developed and used for monitoring the coil pre-stress during assembly and excitation of several dipole models for LHC. Typically these gauges are strips several tenths of millimeter thick that can be made according to a large variety of geometries. Inserted between two surfaces, they allow to measure the distribution of contact pressures up to 200 MPa from am bient temperature to superfluid helium also in presence of a static magnetic field. The sequence and quality of the manufacturing steps are determining factors in the performance of this kind of gauge s. The paper describes the basic principles, possible configuration geometries, fabrication and calibration procedures of these gauges. Finally the applications of capacitive gauges in the framework o f the R&D programme of superconducting short dipole models for LHC are reviewed and discussed.

  13. Cryogenic analysis of forced-cooled, superconducting TF magnets for compact tokamak reactors

    SciTech Connect

    Kerns, J.A.; Slack, D.S.; Miller, J.R.

    1988-10-25

    Current designs for compact tokamak reactors require the toroidal- field (TF) superconducting magnets to produce fields from 10 to 15 T at the winding pack, using high-current densities to high nuclear heat loads (greater than 1 kW/coil in some instances), which are significantly greater than the conduction and radiation heat loads for which cryogenic systems are usually designed. A cryogenic system for the TF winding pack for two such tokamak designs has been verified by performing a detailed, steady-state heat-removal analysis. Helium properties along the forced-cooled conductor flow path for a range of nuclear heat loads have been calculated. The results and implications of this analysis are presented. 12 refs., 6 figs.

  14. Boxfish swimming paradox resolved: forces by the flow of water around the body promote manoeuvrability.

    PubMed

    Van Wassenbergh, S; van Manen, K; Marcroft, T A; Alfaro, M E; Stamhuis, E J

    2015-02-01

    The shape of the carapace protecting the body of boxfishes has been attributed an important hydrodynamic role in drag reduction and in providing automatic, flow-direction realignment and is therefore used in bioinspired design of cars. However, tight swimming-course stabilization is paradoxical given the frequent, high-performance manoeuvring that boxfishes display in their spatially complex, coral reef territories. Here, by performing flow-tank measurements of hydrodynamic drag and yaw moments together with computational fluid dynamics simulations, we reverse several assumptions about the hydrodynamic role of the boxfish carapace. Firstly, despite serving as a model system in aerodynamic design, drag-reduction performance was relatively low compared with more generalized fish morphologies. Secondly, the current theory of course stabilization owing to flow over the boxfish carapace was rejected, as destabilizing moments were found consistently. This solves the boxfish swimming paradox: destabilizing moments enhance manoeuvrability, which is in accordance with the ecological demands for efficient turning and tilting. PMID:25505133

  15. Hybrid Wing Body Model Identification Using Forced-Oscillation Water Tunnel Data

    NASA Technical Reports Server (NTRS)

    Murphy, Patrick C.; Vicroy, Dan D.; Kramer, Brian; Kerho, Michael

    2014-01-01

    Static and dynamic testing of the NASA 0.7 percent scale Hybrid Wing Body (HWB) configuration was conducted in the Rolling Hills Research Corporation water tunnel to investigate aerodynamic behavior over a large range of angle-of-attack and to develop models that can predict aircraft response in nonlinear unsteady flight regimes. This paper reports primarily on the longitudinal axis results. Flow visualization tests were also performed. These tests provide additional static data and new dynamic data that complement tests conducted at NASA Langley 14- by 22-Foot Subsonic Tunnel. HWB was developed to support the NASA Environmentally Responsible Aviation Project goals of lower noise, emissions, and fuel burn. This study also supports the NASA Aviation Safety Program efforts to model and control advanced transport configurations in loss-of-control conditions.

  16. Design of a magnetic force exciter for a small-scale windmill using a piezo-composite generating element

    NASA Astrophysics Data System (ADS)

    Luong, Hung Truyen; Goo, Nam Seo

    2011-03-01

    We introduce a design for a magnetic force exciter that applies vibration to a piezo-composite generating element (PCGE) for a small-scale windmill to convert wind energy into electrical energy. The windmill can be used to harvest wind energy in urban regions. The magnetic force exciter consists of exciting magnets attached to the device's input rotor, and a secondary magnet that is fixed at the tip of the PCGE. Under an applied wind force, the input rotor rotates to create a magnetic force interaction to excite the PCGE. Deformation of the PCGE enables it to generate the electric power. Experiments were performed to test power generation and battery charging capabilities. In a battery charging test, the charging time for a 40 mAh battery is approximately 1.5 hours for a wind speed of 2.5 m/s. Our experimental results show that the prototype can harvest energy in urban areas with low wind speeds, and convert the wasted wind energy into electricity for city use.

  17. Direct current force sensing device based on compressive spring, permanent magnet, and coil-wound magnetostrictive/piezoelectric laminate

    NASA Astrophysics Data System (ADS)

    Leung, Chung Ming; Or, Siu Wing; Ho, S. L.

    2013-12-01

    A force sensing device capable of sensing dc (or static) compressive forces is developed based on a NAS106N stainless steel compressive spring, a sintered NdFeB permanent magnet, and a coil-wound Tb0.3Dy0.7Fe1.92/Pb(Zr, Ti)O3 magnetostrictive/piezoelectric laminate. The dc compressive force sensing in the device is evaluated theoretically and experimentally and is found to originate from a unique force-induced, position-dependent, current-driven dc magnetoelectric effect. The sensitivity of the device can be increased by increasing the spring constant of the compressive spring, the size of the permanent magnet, and/or the driving current for the coil-wound laminate. Devices of low-force (20 N) and high-force (200 N) types, showing high output voltages of 262 and 128 mV peak, respectively, are demonstrated at a low driving current of 100 mA peak by using different combinations of compressive spring and permanent magnet.

  18. Time-Resolved Records of Magnetic Activity on the Pallasite Parent Body and Psyche

    NASA Astrophysics Data System (ADS)

    Bryson, J. F. J.; Nichols, C. I. O.; Herrero-Albillos, J.; Kronast, F.; Kasama, T.; Alimadadi, H.; van der Laan, G.; Nimmo, F.; Harrison, R. J.

    2014-12-01

    Although many small bodies apparently generated dynamo fields in the early solar system, the nature and temporal evolution of these fields has remained enigmatic. Time-resolved records of the Earth's planetary field have been essential in understanding the dynamic history of our planet, and equivalent information from asteroids could provide a unique insight into the development of the solar system. Here we present time-resolved records of magnetic activity on the main-group pallasite parent body and (16) Psyche, obtained using newly-developed nanomagnetic imaging techniques. For the pallasite parent body, the inferred field direction remained relatively constant and the intensity was initially stable at ~100 ?T before it decreased in two discrete steps down to 0 ?T. We interpret this behaviour as due to vigorous dynamo activity driven by compositional convection in the core, ultimately transitioning from a dipolar to multipolar field as the inner core grew from the bottom-up. For Psyche (measured from IVA iron meteorites), the inferred field direction reversed, while the intensity remained stable at >50 ?T. Psyche cooled rapidly as an unmantled core, although the resulting thermal convection alone cannot explain these observations. Instead, this behaviour required top-down core solidification, and is attributed either to compositional convection (if the core also solidified from the bottom-up) or convection generated directly by top-down solidification (e.g. Fe-snow). The mechanism governing convection in small body cores is an open question (due partly to uncertainties in the direction of core solidification), and these observations suggest that unconventional (i.e. not thermal) mechanisms acted in the early solar system. These mechanisms are very efficient at generating convection, implying a long-lasting and widespread epoch of dynamo activity among small bodies in the early solar system.

  19. Use of a magnetic force exciter to vibrate a piezocomposite generating element in a small-scale windmill

    NASA Astrophysics Data System (ADS)

    Truyen Luong, Hung; Goo, Nam Seo

    2012-02-01

    A piezocomposite generating element (PCGE) can be used to convert ambient vibrations into electrical energy that can be stored and used to power other devices. This paper introduces a design of a magnetic force exciter for a small-scale windmill that vibrates a PCGE to convert wind energy into electrical energy. A small-scale windmill was designed to be sensitive to low-speed wind in urban regions for the purpose of collecting wind energy. The magnetic force exciter consists of exciting magnets attached to the device’s input rotor and a secondary magnet fixed at the tip of the PCGE. The PCGE is fixed to a clamp that can be adjusted to slide on the windmill’s frame in order to change the gap between exciting and secondary magnets. Under an applied wind force, the input rotor rotates to create a magnetic force interaction that excites the PCGE. The deformation of the PCGE enables it to generate electric power. Experiments were performed with different numbers of exciting magnets and different gaps between the exciting and secondary magnets to determine the optimal configuration for generating the peak voltage and harvesting the maximum wind energy for the same range of wind speeds. In a battery-charging test, the charging time for a 40 mA h battery was approximately 3 h for natural wind in an urban region. The experimental results show that the prototype can harvest energy in urban regions with low wind speeds and convert the wasted wind energy into electricity for city use.

  20. The dust motion inside the magnetized sheath - The effect of drag forces

    SciTech Connect

    Pandey, B. P.; Samarian, A.; Vladimirov, S. V.

    2010-08-15

    The isolated charged dust inside the magnetized plasma sheath moves under the influence of the electron and ion drag force and the sheath electrostatic field. The charge on the dust is a function of its radius as well as the value of the ambient sheath potential. It is shown that the charge on the dust determines its trajectory and dust performs the spiraling motion inside the sheath. The location of the turning spiral is determined by the number of negative charge on the dust, which in turn is a function of the dust radius. The back and forth spiraling motion finally causes the dust to move in a small, narrow region of the sheath. For a bigger dust particle, the dust moves closer to the sheath presheath boundary suggesting that the bigger grains, owing to the strong repulsion between the wall and dust, will be unable to travel inside the sheath. Only small, micron-sized grains can travel closer to the wall before repulsion pushes it back toward the plasma-sheath boundary. The temporal behavior of the spiraling dust motion appears like a damped harmonic oscillation, suggesting that the plasma drag force causes dissipation of the electrostatic energy. However, after initial damping, the grain keeps oscillating although with much smaller amplitude. The possible application of the present results to the ongoing sheath experiments is discussed.

  1. Detailed description of exclusive muon capture rates using realistic two-body forces

    E-print Network

    P. G. Giannaka; T. S. Kosmas

    2015-06-18

    Starting from state-by-state calculations of exclusive rates of the ordinary muon capture (OMC), we evaluated total muon-capture rates for a set of light- and medium-weight nuclear isotopes. We employed a version of the proton-neutron quasi-particle random phase approximation (pn-QRPA, for short) which uses as realistic nuclear forces the Bonn C-D one boson exchange potential. Special attention was paid on the percentage contribution to the total muon-capture rate of specific low-spin multipolarities resulting by summing over the corresponding multipole transitions. The nuclear method used offers the possibility of estimating separately the individual contributions to the total and partial rates of the polar-vector and axial-vector components of the weak interaction Hamiltonian for each accessible final state of the daughter nucleus. One of our main goals is to provide a reliable description of the charge changing transitions matrix elements entering the description of other similar semileptonic nuclear processes like the charged-current neutrino-nucleus reactions, the electron capture on nuclei, the single \\b{eta}-decay mode, etc., which play important role in currently interesting laboratory and astrophysical applications like the neutrino-detection through lepton- nucleus interaction probes, and neutrino-nucleosynthesis. Such results can be also be useful in various ongoing muon-capture experiments at PSI, Fermilab, JPARC and RCNP.

  2. Detailed description of exclusive muon capture rates using realistic two-body forces

    E-print Network

    Giannaka, P G

    2015-01-01

    Starting from state-by-state calculations of exclusive rates of the ordinary muon capture (OMC), we evaluated total muon-capture rates for a set of light- and medium-weight nuclear isotopes. We employed a version of the proton-neutron quasi-particle random phase approximation (pn-QRPA, for short) which uses as realistic nuclear forces the Bonn C-D one boson exchange potential. Special attention was paid on the percentage contribution to the total muon-capture rate of specific low-spin multipolarities resulting by summing over the corresponding multipole transitions. The nuclear method used offers the possibility of estimating separately the individual contributions to the total and partial rates of the polar-vector and axial-vector components of the weak interaction Hamiltonian for each accessible final state of the daughter nucleus. One of our main goals is to provide a reliable description of the charge changing transitions matrix elements entering the description of other similar semileptonic nuclear proce...

  3. Detailed description of exclusive muon capture rates using realistic two-body forces

    NASA Astrophysics Data System (ADS)

    Giannaka, P. G.; Kosmas, T. S.

    2015-07-01

    Starting from state-by-state calculations of exclusive rates of the ordinary muon capture, we evaluated total ?- capture rates for a set of light- and medium-weight nuclear isotopes. We employed a version of the proton-neutron quasiparticle random-phase approximation (p n -QRPA, for short) which uses as realistic nuclear forces the Bonn C-D one-boson exchange potential. Special attention was paid on the percentage contribution to the total ?- capture rate of specific low-spin multipolarities resulting by summing over the corresponding multipole transitions. The nuclear method used offers the possibility of estimating separately the individual contributions to the total and partial rates of the polar-vector and axial-vector components of the weak-interaction Hamiltonian for each accessible final state of the daughter nucleus. One of our main goals is to provide a reliable description of the charge-changing transitions matrix elements entering the description of other similar semileptonic nuclear processes like the charged-current neutrino-nucleus reactions, the electron capture on nuclei, the single ?±-decay mode, etc., which play important role in currently interesting laboratory and astrophysical applications like the neutrino detection through lepton-nucleus interaction probes and neutrino nucleosynthesis. Such results can also be useful in various ongoing muon capture experiments at Paul Scherrer Institute (PSI), Fermilab, Japan Proton Accelerator Research Complex, and Research Center for Nuclear Physics, Osaka University.

  4. Clinical value of whole-body magnetic resonance imaging in health screening of general adult population

    PubMed Central

    Tarnoki, David Laszlo; Tarnoki, Adam Domonkos; Richter, Antje; Karlinger, Kinga; Berczi, Viktor; Pickuth, Dirk

    2015-01-01

    Background Whole-body magnetic resonance imaging (WB-MRI) and angiography (WB-MRA) has become increasingly popular in population-based research. We evaluated retrospectively the frequency of potentially relevant incidental findings throughout the body. Materials and methods 22 highly health-conscious managers (18 men, mean age 47±9 years) underwent WB-MRI and WB-MRA between March 2012 and September 2013 on a Discovery MR750w wide bore 3 Tesla device (GE Healthcare) using T1 weighted, short tau inversion recovery (STIR) and diffusion weighted imaging (DWI) acquisitions according to a standardized protocol. Results A suspicious (pararectal) malignancy was detected in one patient which was confirmed by an endorectal sonography. Incidental findings were described in 20 subjects, including hydrocele (11 patients), benign bony lesion (7 patients) and non-specific lymph nodes (5 patients). Further investigations were recommended in 68% (ultrasound: 36%, computed tomography: 28%, mammography: 9%, additional MRI: 9%). WB-MRA were negative in 16 subjects. Vascular normal variations were reported in 23%, and a 40% left proximal common carotid artery stenosis were described in one subject. Conclusions WB-MRI and MRA lead to the detection of clinically relevant diseases and unexpected findings in a cohort of healthy adults that require further imaging or surveillance in 68%. WB-MR imaging may play a paramount role in health screening, especially in the future generation of (epi)genetic based screening of malignant and atherosclerotic disorders. Our study is the first which involved a highly selected patient group using a high field 3-T wide bore magnet system with T1, STIR, MRA and whole-body DWI acquisitions as well. PMID:25810696

  5. Averaging out magnetic forces with fast rf-sweeps in an optical trap for metastable chromium atoms

    E-print Network

    Q. Beaufils; R. Chicireanu; A. Pouderous; W. de Souza Melo; B. Laburthe-Tolra; E. Maréchal; L. Vernac; J. C. Keller; O. Gorceix

    2007-11-05

    We introduce a novel type of time-averaged trap, in which the internal state of the atoms is rapidly modulated to modify magnetic trapping potentials. In our experiment, fast radiofrequency (rf) linear sweeps flip the spin of atoms at a fast rate, which averages out magnetic forces. We use this procedure to optimize the accumulation of metastable chomium atoms into an optical dipole trap from a magneto-optical trap. The potential experienced by the metastable atoms is identical to the bare optical dipole potential, so that this procedure allows for trapping all magnetic sublevels, hence increasing by up to 80 percent the final number of accumulated atoms.

  6. Effect of unbalanced magnetic pull and hydraulic seal force on the vibration of large rotor-bearing systems

    NASA Astrophysics Data System (ADS)

    Song, Z.; Guo, P.; Liu, Y.

    2014-03-01

    The influence of unbalanced magnetic pull (UMP) and hydraulic seal force on the vibration of large rotor-bearing systems is studied. The UMP caused by rotor eccentricity imposes important effects on rotating machinery, especially for large generators such as water turbine generator sets, because these machines operate above their first critical speed in some instances and are supported by oil film bearings. A magnetic stiffness matrix for studying the effects of the UMP is proposed. The magnetic stiffness matrix can be generated by decomposing the expression of air gap magnetic field energy. Two vibration models are constructed using the Lagrange equation. The difference between the two models lies in the boundary support condition: one has rigid support and the other has elastic bearing support. The influence of the magnetic stiffness and elastic support on the critical speed of the rotor is studied using Lyapunov nonlinear vibration stability theory. The vibration amplitude of the rotor is calculated, taking the magnetic stiffness and horizontal centrifugal force into account. The unbalanced hydraulic seal force is produced because of the asymmetry of seal clearance. This imbalance is one of the factors that causes self-excited vibration in rotating machinery, and is as important as the UMP for large water turbine generator sets. The rotor-bearing system is supported by an oil film journal bearing, whose characteristic also impose considerable influence on vibration. On the basis of the above-mentioned conditions, a three-dimensional finite element model of the rotating system that includes the oil film journal bearing is constructed. The effect of the UMP and unbalanced hydraulic seal force is considered in the construction, and studied in relation to the magnetic parameters, seal parameters, journal bearing stiffness, and outer diameter of the rotating machine critical speed. Conclusions may benefit the dynamic design and optimized operation of large rotating machinery.

  7. Correlations in light nuclei and their relation to fine tuning and uncertainty quantifications of many body forces in low-energy nuclear physics

    E-print Network

    Lupu, Sergiu; Gazit, Doron

    2015-01-01

    The large nucleon-nucleon scattering length, and the isospin approximate symmetry, are low energy properties of quantum chromodynamics (QCD). These entail correlations in the binding energies of light nuclei, e.g., the A=3 iso-multiplet, and Tjon's correlation between the binding energy of three and four body nuclei. Using a new representation of these, we establish that they translate into a correlation between different short-range contributions to three body forces in chiral effective field theory of low-energy nuclear physics. We demonstrate that these correlations should be taken into account in order to avoid fine-tuning in the calibration of three body forces. We relate this to the role of correlations in uncertainty quantification of non-renormalizable effective field theories of the nuclear regime. In addition, we show that correlations can be useful in assessing the importance of forces induced by renormalization group (RG) transformations. We give numerical evidence that such RG transformations can...

  8. Induced Electromotive Force (EMF) Profile in a Circular Loop Passing a Limited Rectangular Area with Perpendicular Uniform Constant Magnetic Field

    E-print Network

    Viridi, Sparisoma; Khairurrijal,

    2012-01-01

    Profile of induced eletromotive force (EMF) for a circular loop (CL) entering and leaving a limited rectangular area which has perpendicular uniform magnetic field is reported in this work. The influence of parameters of the sytem to the induced EMF profile is discussed.

  9. Guiding-centre transformation of the radiation-reaction force in a non-uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Hirvijoki, E.; Decker, J.; Brizard, A. J.; Embréus, O.

    2015-10-01

    > In this paper, we present the guiding-centre transformation of the radiation-reaction force of a classical point charge travelling in a non-uniform magnetic field. The transformation is valid as long as the gyroradius of the charged particles is much smaller than the magnetic field non-uniformity length scale, so that the guiding-centre Lie-transform method is applicable. Elimination of the gyromotion time scale from the radiation-reaction force is obtained with the Poisson-bracket formalism originally introduced by Brizard (Phys. Plasmas, vol. 11, 2004, 4429-4438), where it was used to eliminate the fast gyromotion from the Fokker-Planck collision operator. The formalism presented here is applicable to the motion of charged particles in planetary magnetic fields as well as in magnetic confinement fusion plasmas, where the corresponding so-called synchrotron radiation can be detected. Applications of the guiding-centre radiation-reaction force include tracing of charged particle orbits in complex magnetic fields as well as the kinetic description of plasma when the loss of energy and momentum due to radiation plays an important role, e.g. for runaway-electron dynamics in tokamaks.

  10. EVOLUTION OF A MAGNETIC FLUX ROPE AND ITS OVERLYING ARCADE BASED ON NONLINEAR FORCE-FREE FIELD EXTRAPOLATIONS

    SciTech Connect

    Jing, Ju; Liu, Chang; Lee, Jeongwoo; Wang, Shuo; Xu, Yan; Wang, Haimin; Wiegelmann, Thomas

    2014-03-20

    Dynamic phenomena indicative of slipping reconnection and magnetic implosion were found in a time series of nonlinear force-free field (NLFFF) extrapolations for the active region 11515, which underwent significant changes in the photospheric fields and produced five C-class flares and one M-class flare over five hours on 2012 July 2. NLFFF extrapolation was performed for the uninterrupted 5 hour period from the 12 minute cadence vector magnetograms of the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory. According to the time-dependent NLFFF model, there was an elongated, highly sheared magnetic flux rope structure that aligns well with an H? filament. This long filament splits sideways into two shorter segments, which further separate from each other over time at a speed of 1-4 km s{sup –1}, much faster than that of the footpoint motion of the magnetic field. During the separation, the magnetic arcade arching over the initial flux rope significantly decreases in height from ?4.5 Mm to less than 0.5 Mm. We discuss the reality of this modeled magnetic restructuring by relating it to the observations of the magnetic cancellation, flares, a filament eruption, a penumbra formation, and magnetic flows around the magnetic polarity inversion line.

  11. Influence of Line-Tied Boundary Conditions on the Development of Magnetic Reconnection in Force-Free Current Layers

    NASA Astrophysics Data System (ADS)

    Akcay, Cihan; Daughton, William; Stanier, Adam; Lukin, Vyacheslav

    2014-10-01

    The evolution of plasmas in magnetically dominated low- ? regimes often leads to the formation of nearly force-free current sheets where magnetic reconnection may be triggered by the tearing instability. In this study, we examine the influence of line-tied boundary conditions on the onset and development of three-dimensional magnetic reconnection in kinetic-scale force-free layers. To better understand the physics, we perform cross-comparisons between fully kinetic VPIC simulations and two-fluid HiFi simulations. We focus on a range of guide fields Bg = (1 - 10) B0 relevant to both space and laboratory plasmas, and compare the evolution between systems with line-tied and periodic boundary conditions.

  12. Assessment of a magnet system combining the advantages of cable-in-conduit forced-flow and pool-boiling magnets

    SciTech Connect

    Slack, D.; Hassenzahl, W.; Felker, B.; Chaplin, M.

    1993-10-06

    This paper presents an idea for a magnet system that could be used to advantage in tokamaks and other fusion engineering devices. Higher performance designs, specifically newer tokamaks such as those for the international Tokamak Engineering Reactor (ITER) and Tokamak Physics Experiment (TPX) use Cable in Conduit Conductor (CICC) forced flow coils to advantage to meet field and current density requirements. Pool boiling magnets lack structural integrity to resist high magnetic forces since helium cooling areas must surround each conductor. A second problem is that any leak can threaten the voltage standoff integrity of the magnet system. This is because a leak can result in low-pressure helium gas becoming trapped by limited conductance in the magnet bundle and low-pressure helium has poor dielectric strength. The system proposed here is basically a CICC system, with it`s inherent advantages, but bathed in higher pressure supercritical helium to eliminate the leak and voltage break-down problems. Schemes to simplify helium coolant plumbing with the proposed system are discussed. A brief historical review of related magnet systems is included. The advantages and disadvantages of using higher pressure, supercritical helium in combination with solid electrical insulation in a CICC system are discussed. Related electrical data from some previous works are compiled and discussed.

  13. Numerical code for multi-component galaxies: from N-body to chemistry and magnetic fields

    E-print Network

    Khoperskov, S A; Khoperskov, A V; Lubimov, V N

    2015-01-01

    We present a numerical code for multi-component simulation of the galactic evolution. Our code includes the following parts: $N$-body is used to evolve dark matter, stellar dynamics and dust grains, gas dynamics is based on TVD-MUSCL scheme with the extra modules for thermal processes, star formation, magnetic fields, chemical kinetics and multi-species advection. We describe our code in brief, but we give more details for the magneto-gas dynamics. We present several tests for our code and show that our code have passed the tests with a reasonable accuracy. Our code is parallelized using the MPI library. We apply our code to study the large scale dynamics of galactic discs.

  14. Whole-body diffusion magnetic resonance imaging in the assessment of lymphoma.

    PubMed

    Lin, Chieh; Luciani, Alain; Itti, Emmanuel; Haioun, Corinne; Safar, Violaine; Meignan, Michel; Rahmouni, Alain

    2012-01-01

    The current evidence regarding the usefulness of whole-body diffusion-weighted magnetic resonance imaging (diffusion MRI) in the assessment of lymphoma is reviewed. Diffusion MRI combining both anatomical and bio-physiological information is currently under investigation as a valuable tool in the oncology field including lymphoma, not only for staging but also for the assessment of response. Representative images for each purpose are shown. Diffusion MRI requires no administration of contrast medium and does not use ionizing radiation, which could be particularly advantageous for repeat follow-up surveillance in lymphoma patients. Diffusion MRI may prove to be a useful biomarker in clinical decision making for patients with lymphoma. Large-scale prospective studies are warranted to further establish its complementary value to the current standard of care, [(18)F]fluorodeoxyglucose positron emission tomography/computed tomography. PMID:23022623

  15. Whole-body diffusion magnetic resonance imaging in the assessment of lymphoma

    PubMed Central

    Lin, Chieh; Luciani, Alain; Itti, Emmanuel; Haioun, Corinne; Safar, Violaine; Meignan, Michel

    2012-01-01

    Abstract The current evidence regarding the usefulness of whole-body diffusion-weighted magnetic resonance imaging (diffusion MRI) in the assessment of lymphoma is reviewed. Diffusion MRI combining both anatomical and bio-physiological information is currently under investigation as a valuable tool in the oncology field including lymphoma, not only for staging but also for the assessment of response. Representative images for each purpose are shown. Diffusion MRI requires no administration of contrast medium and does not use ionizing radiation, which could be particularly advantageous for repeat follow-up surveillance in lymphoma patients. Diffusion MRI may prove to be a useful biomarker in clinical decision making for patients with lymphoma. Large-scale prospective studies are warranted to further establish its complementary value to the current standard of care, [18F]fluorodeoxyglucose positron emission tomography/computed tomography. PMID:23022623

  16. Mechanical characterization and modelling of Lorentz force based MEMS magnetic field sensors

    NASA Astrophysics Data System (ADS)

    Gkotsis, P.; Lara-Castro, M.; López-Huerta, F.; Herrera-May, A. L.; Raskin, J.-P.

    2015-10-01

    In this work we present experimental results from dynamic and static tests on miniature magnetic field sensors which are based on Micro Electro Mechanical Systems (MEMS) technologies. These MEMS magnetometers were fabricated on SOI wafers using Si bulk micromachining techniques and they operate at the first resonant frequency under the action of the Lorentz force which arises when a current flows through them in the presence of an external magnetic field. Sensing is based on piezoresistive principles and high sensitivity is expected from devices that show high total quality factors Qtot. We investigate here the energy loss mechanisms and the temperature rise due to Joule heating effects in the resonators of the magnetometers by performing tests both in air and under vacuum conditions. Testing was performed using laser Doppler Vibrometry and white light interferometry. At each pressure different driving currents have been applied and Qtot was extracted. It is found that Qtot varies with pressure between two limiting values: a low one in air which was between 17 and 500 for the tested devices and a high one in vacuum which in the case of one of our devices was equal to 2800. The amplitude of the applied current is also affecting the Q value at a certain pressure due to the rise of thermal stress in the resonating structures. The sensitivity of the sensors in air was experimentally measured using a Helmholtz coil and an oscilloscope and values between 72 mV T-1 and 513 mV T-1 were obtained from the tested devices. We further attempt to estimate the temperature rise in the devices due to Joule heating effects by combining the topography scans which were experimentally obtained with results from thermomechanical analysis of the sensors using Finite Element Modelling.

  17. Magnetic force microscopy studies of the domain structure of CoPd multilayers in a magnetic field

    E-print Network

    Dahlberg, E. Dan

    have measured the magnetic domain patterns in Co/Pd multilayers of varying thickness using magnetic In this article we describe a study of Co/Pd multilayers which are known to have perpendicular anisotropy when

  18. Design and development of scanning eddy current force microscopy for characterization of electrical, magnetic and ferroelectric properties with nanometer resolution

    NASA Astrophysics Data System (ADS)

    Nalladega, Vijayaraghava

    This dissertation describes the design and development of a new high-resolution electrical conductivity imaging technique combining the basic principles of eddy currents and atomic force microscopy (AFM). An electromagnetic coil is used to generate eddy currents in an electrically conducting material. The eddy currents induced in the sample are detected and measured with a magnetic tip attached to the AFM cantilever. The interaction of eddy currents with the magnetic tip-cantilever is theoretically modeled. The model is then used to estimate the eddy current forces generated in a typical metallic material placed in induced current field. The magnitude of the eddy current force is directly proportional to the electrical conductivity of the sample. The theoretical eddy current forces are used to design a magnetic tip-cantilever system with appropriate magnetic field and spring constant to facilitate the development of a high-resolution, high sensitivity electrical conductivity imaging technique. The technique is used to experimentally measure eddy current forces in metals of different conductivities and compared with theoretical and finite element models. The experimental results show that the technique is capable of measuring pN range eddy current forces. The experimental eddy current forces are used to determine the electrical resistivity of a thin copper wire and the experimental value agrees with the bulk resistivity of copper reported in literature. The imaging capabilities of the new technique are demonstrated by imaging the electrical conductivity variations in a composite sample and a dual-phase titanium alloy in lift mode AFM. The results indicate that this technique can be used to detect very small variations in electrical conductivity. The spatial resolution of the technique is determined to be about 25 nm by imaging carbon nanofibers reinforced in polymer matrix. Since AFM is extensively used to characterize nanomaterials, the newly developed technique is used to characterize metallic nanoparticles. The results showed for the first time that it is possible to image helicons in nanometallic particles at low electromagnetic frequencies using an AFM. The theoretical analysis of the helicons in nanostructured materials is presented using the concept of effective mass of electrons. The primary objective of the research work reported in this dissertation is to develop a high-resolution electrical conductivity imaging system. However, the interaction of induced currents with different materials gives rise to different interaction forces. If an appropriate probe and an imaging mode are used, different material properties can be characterized using the same experimental setup. Therefore, in this study, magneto-acoustic, magnetic and dielectric properties of materials placed in induced current fields are studied. The modifications necessary to image these properties are discussed in detail. The advantages, limitations and applications of the new methodology are discussed.

  19. Analysis of Effect of Ultrasound on the Magnetic Topography of Electroplated Ni Films by Magnetic Force Microscopy (MFM)

    NASA Astrophysics Data System (ADS)

    Das, Arpita; Mallik, Archana; Ray, Bankim Chandra

    2012-04-01

    It has been shown to be extremely beneficial to employ power ultrasound to assist electrochemical processes. Considerable mass transport has been demonstrated with the application of ultrasound. The magnetic microstructure, magnetic phase, and orientation images show better magnetic particle deposits in the presence of a sonication environment. Furthermore, deposits with ultrasound show permanent dipole moment magnetization. Hence, Ni film synthesis in presence of ultrasound may open new heights for hard disk drives.

  20. Evaluation of nuclear magnetic resonance spectroscopy for determination of deuterium abundance in body fluids: application to measurement of total-body water in human infants

    SciTech Connect

    Rebouche, C.J.; Pearson, G.A.; Serfass, R.E.; Roth, C.W.; Finley, J.W.

    1987-02-01

    Nuclear magnetic resonance (NMR) spectroscopy was used to quantitate abundance of 2H in body water of human infants. This method provides precise measurement of total-body water without the extensive sample preparation requirements of previously described methods for determination of 2H content in body fluids. 2H2O (1 g/kg body weight) was administered to infants and saliva and urine were collected for up to 5 h. An internal standard was added directly to the fluid specimen and 2H enrichment in water was measured by NMR spectroscopy. Working range of deuterium abundance was 0.04-0.32 atom %. Coefficients of variation for saliva samples at 0.20 atom % 2H was 1.97%. 2H content in urine and saliva water reached a plateau by 4 h after administration, and amounts in the two fluids were virtually identical. Mean total-body water determination for six infants was 58.3 +/- 5.8% of body weight (range 53-66%).

  1. Forces and Moments on Pointed Blunt-nosed Bodies of Revolution at Mach Numbers from 2.75 to 5.00

    NASA Technical Reports Server (NTRS)

    Dennis, David H; Cunningham, Bernard E

    1952-01-01

    Results of tests to determine the aerodynamic forces and moments on bodies of revolution at angles of attack from 0 degrees to 25 degrees are presented and compared with theory. Cones and ogives of fineness ratios 3 to 7 and two blunt-nosed body shapes with fineness ratios 3 and 5 were tested at Mach numbers from 2.75 to 5.00. Reynolds numbers were from 0.5 million to 6.4 million, depending on Mach number and body fineness ratio.

  2. Helicity dissipation in 3d PIC simulation of magnetic reconnection of a force free configuration

    NASA Astrophysics Data System (ADS)

    Bowers, Kevin; Li, Hui

    2003-10-01

    We have conducted many simulations of reconnection in a force-free sheet-pinch configuration with twisting magnetic fields (B0 s ? z, B0 sin ? z, 0). The simulations were done with a new relativistic parallelized PIC code. The code uses exact charge and energy conserving algorithms and a 6th order Boris rotation to accurately resolve reconnection physics. Further the implementation minimizes memory bandwidth, maximizes data locality and utilizes vector features on commodity processors to achieve exceptional performance which allows us routinely to make large runs. In a periodic box where the x and y dimensions are longer than the z dimension, the configuration is unstable; collisionless tearing modes grow at discrete layers with different orientations. The overall evolution can be divided into three stages: (1) linear growth of tearing modes; (2) overlap of tearing islands, leading to stochastic field lines; (3) relaxation to a new equilibrium. Presently, we are studying the effect of Debye scale phenomena on helicity dissipation, the electron phase-space distribution and the growth of secondary instabilities. In contrast to our 2d3v simulations, we see anomalous levels of helicity dissipation during reconnection in our 3d simulations.

  3. Application of small-angle neutron scattering to the study of forces between magnetically chained monodisperse ferrofluid emulsion droplets

    SciTech Connect

    Jain, Dr Nirmesh; Liu, Dr C K; Hawkett, Dr B. S.; Warr, G. G.; Hamilton, William A

    2014-01-01

    The optical magnetic chaining technique (MCT) developed by Leal-Calderon, Bibette and co-workers in the 1990 s allows precise measurements of force profiles between droplets in monodisperse ferrofluid emulsions. However, the method lacks an in-situ determination of droplet size and therefore requires the combination of separately acquired measurements of droplet chain periodicity versus an applied magnetic field from optical Bragg scattering and droplet diameter inferred from dynamic light scattering (DLS) to recover surface force-distance profiles between the colloidal particles. Compound refractive lens (CRL) focussed small-angle scattering (SANS) MCT should result in more consistent measurements of droplet size (form factor measurements in the absence of field) and droplet chaining period (from structure factor peaks when the magnetic field is applied); and, with access to shorter length scales, extend force measurements to closer approaches than possible by optical measurements. We report on CRL-SANS measurements of monodisperse ferrofluid emulsion droplets aligned in straight chains by an applied field perpendicular to the incident beam direction. Analysis of the scattering from the closely spaced droplets required algorithms that carefully treated resolution and its effect on mean scattering vector magnitudes in order to determine droplet size and chain periods to sufficient accuracy. At lower applied fields scattering patterns indicate structural correlations transverse to the magnetic field direction due to the formation of intermediate structures in early chain growth.

  4. Effect of the size of GdBCO-Ag secondary magnet on the static forces performance of linear synchronous motors

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Shi, Yunhua; He, Dabo; Jing, Hailian; Li, Jing; Deng, Zigang; Wang, Suyu; Wang, Jiasu; Cardwell, David A.

    2014-11-01

    Bulk high temperature superconductor magnets (HTSMs) have a higher flux-generating capability compared to conventional permanent magnets (PMs). These materials potentially can be used in high temperature superconducting (HTS) linear synchronous motors (LSMs) as superconducting secondary magnets, what will result in a reduced volume and weight as well as in higher force density and efficiency of these devices when compared to conventional PMs. The focus of this paper is on the effect of size of the secondary HTSM on the static performance (thrust force and normal force) of a LSM. In order to obtain high-field HTSM as the secondary, single grain bulk GdBCO-Ag superconductors of diameter 20 mm, 30 mm and 40 mm, which have higher Jc and trapped fields than YBCO superconductors, were used in this device for the first time following application by the same optimized magnetization condition. It was found that both thrust and normal forces increase and saturate with the increasing size of the HTSM secondary at the small size range, and then potentially distort when the physical size of the HTSM secondary approaches the pole pitch of the linear three-phase primary windings of the LSM. Furthermore, more experiments of a larger-sized multi-seeded HTSM secondary, confirmed that the relationship between the HTSM secondary size and the pole pitch of the primary is an important factor for achieving higher thrust and normal forces. It is suggested that the multi-pole HTSM secondary will be more beneficial to future HTS LSM designs since the single-pole HTSM secondary size should be equal to or smaller than the stator pole pitch in the paper.

  5. The properties of the three-nucleon system with the dressed-bag model for nn interaction. I: New scalar three-body force

    E-print Network

    V. I. Kukulin; V. N. Pomerantsev; M. Kaskulov; Amand Faessler

    2004-01-29

    A multi-component formalism is developed to describe three-body systems with nonstatic pairwise interactions and non-nucleonic degrees of freedom. The dressed-bag model for $NN$ interaction based on the formation of an intermediate six-quark bag dressed by a $\\sigma$-field is applied to the $3N$ system, where it results in a new three-body force between the six-quark bag and a third nucleon. Concise variational calculations of $3N$ bound states are carried out in the dressed-bag model including the new three-body force. It is shown that this three-body force gives at least half the $3N$ total binding energy, while the weight of non-nucleonic components in the $^3$H and $^3$He wavefunctions can exceed 10%. The new force model provides a very good description of $3N$ bound states with a reasonable magnitude of the $\\sigma NN$ coupling constant. The model can serve as a natural bridge between dynamical description of few-nucleon systems and the very successful Walecka approach to heavy nuclei and nuclear matter.

  6. Large Eddy Simulations of forced ignition of a non-premixed bluff-body methane flame with Conditional Moment Closure

    SciTech Connect

    Triantafyllidis, A.; Mastorakos, E.; Eggels, R.L.G.M.

    2009-12-15

    Large Eddy Simulations (LES) of forced ignition of a bluff-body stabilised non-premixed methane flame using the Conditional Moment Closure (CMC) turbulent combustion model have been performed. The aim is to investigate the feasibility of the use of CMC/LES for ignition problems and to examine which, if any, of the characteristics already observed in related experiments could be predicted. A three-dimensional formulation of the CMC equation was used with simple and detailed chemical mechanisms, and sparks with different parameters (location, size) were used. It was found that the correct pattern of flame expansion and overall flame appearance were predicted with reasonable accuracy with both mechanisms, but the detailed mechanism resulted in expansion rates closer to the experiment. Moreover, the distribution of OH was predicted qualitatively accurately, with patches of high and low concentration in the recirculation zone during the ignition transient, consistent with experimental data. The location of the spark relative to the recirculation zone was found to determine the pattern of the flame propagation and the total time for the flame stabilisation. The size was also an important parameter, since it was found that the flame extinguishes when the spark is very small, in agreement with expectations from experiment. The stabilisation mechanism of the flame was dominated by the convection and sub-grid scale diffusion of hot combustion products from the recirculation zone to the cold gases that enter the burner, as revealed by analysis of the CMC equation. (author)

  7. Observation of the orientation of membrane protein crystals grown in high magnetic force fields

    NASA Astrophysics Data System (ADS)

    Numoto, Nobutaka; Shimizu, Ken-ichi; Matsumoto, Kazuya; Miki, Kunio; Kita, Akiko

    2013-03-01

    Crystallization of membrane proteins in magnetic fields is thought to reveal the magnetic orientations of crystals, and is expected to enhance crystal quality for X-ray crystallographic analysis. The light-harvesting complex 2 (LH2) from a photosynthetic bacterium, Thermochromatium tepidum was crystallized in steep-gradient magnetic fields. The rod-shaped crystals of LH2 grown in the magnetic fields were oriented parallel to the magnetic field direction. An X-ray diffraction experiment indicated that the overall R value and crystal mosaicity are improved for the magnetically oriented crystal, and the helix bundles of LH2 were located parallel to the magnetic field direction in the crystal packing.

  8. Three-body force effect on the properties of nuclear matter under the gap and continuous choices within the BHF approach

    E-print Network

    Pei Wang; Wei Zuo

    2014-04-16

    We have calculated and compared the three-body force effects on the properties of nuclear matter under the gap and continuous choices for the self-consistent auxiliary potential within the Brueckner-Hartree-Fock approach by adopting the Argonne $V18$ and the Bonn B two-body potentials plus a microscopic three-body force (TBF). The TBF provides a strong repulsive effect on the equation of state of nuclear matter at high densities for both the gap and continuous choices. The saturation point turns out to be much closer to the empirical value when the continuous choice is adopted. In addition, the dependence of the calculated symmetry energy upon the choice of the self-consistent auxiliary potential is discussed.

  9. A Smart Magnetically Active Nanovehicle for on-Demand Targeted Drug Delivery: Where van der Waals Force Balances the Magnetic Interaction.

    PubMed

    Panja, Sudipta; Maji, Somnath; Maiti, Tapas K; Chattopadhyay, Santanu

    2015-11-01

    The magnetic field is a promising external stimulus for controlled and targeted delivery of therapeutic agents. Here, we focused on the preparation of a novel magnetically active polymeric micelle (MAPM) for magnetically targeted controlled drug delivery. To accomplish this, a number of superparamagnetic as well as biocompatible hybrid micelles were prepared by grafting four armed pentaerythretol poly(?-caprolactone) (PE-PCL) onto the surface of Fe3O4 magnetic nanoparticles (MNPs) of two different ranges of size (?5 nm and ?15 nm). PE-PCL (four-armed) was synthesized by ring-opening polymerization, and it has been subsequently grafted onto the surface of modified MNP through urethane (-NHCO-) linkage. Polymer-immobilized MNP (5 and 15 nm) showed peculiar dispersion behavior. One displayed uniform dispersion of MNP (5 nm), while the other (15 nm) revealed associated structure. This type of size dependent contradictory dispersion behavior was realized by taking the van der Waals force as well as magnetic dipole-dipole force into consideration. The uniformly dispersed polymer immobilized MNP (5 nm) was used for the preparation of MAPM. The hydrodynamic size and bulk morphology of MAPM were studied by dynamic light scattering and high-resolution transmission electron microscopy. The anticancer drug (DOX) was encapsulated into the MAPM. The magnetic field triggers cell uptake of MAPM micelles preferentially toward targeted cells compare to untargeted ones. The cell viabilities of MAMP, DOX-encapsulated MAPM, and free DOX were studied against HeLa cell by MTT assay. In vitro release profile displayed about 51.5% release of DOX from MAPM (just after 1 h) under the influence of high frequency alternating magnetic field (HFAMF; prepared in-house device). The DOX release rate has also been tailored by on-demand application of HFAMF. PMID:26458134

  10. Empirical modeling of 3-D force-balanced plasma and magnetic field structures during substorm growth phase

    NASA Astrophysics Data System (ADS)

    Yue, Chao; Wang, Chih-Ping; Nishimura, Yukitoshi; Murphy, Kyle R.; Xing, Xiaoyan; Lyons, Larry; Henderson, Michael; Angelopoulos, Vassilis; Lui, A. T. Y.; Nagai, Tsugunobu

    2015-08-01

    Accurate evaluation of the physical processes during the substorm growth phase, including formation of field-aligned currents (FACs), isotropization by current sheet scattering, instabilities, and ionosphere-magnetosphere connection, relies on knowing the realistic three-dimensional (3-D) magnetic field configuration, which cannot be reliably provided by current available empirical models. We have established a 3-D substorm growth phase magnetic field model, which is uniquely constructed from empirical plasma sheet pressures under the constraint of force balance. We investigated the evolution of model pressure and magnetic field responding to increasing energy loading and their configurations under different solar wind dynamic pressure (PSW) and sunspot number. Our model reproduces the typical growth phase evolution signatures: plasma pressure increases, magnetic field lines become more stretched, current sheet becomes thinner, and the Region 2 FACs are enhanced. The model magnetic fields agree quantitatively well with observed fields. The magnetic field is substantially more stretched under higher PSW, while the dependence on sunspot number is nonlinear and less substantial. By applying our modeling to a substorm event, we found that (1) the equatorward movement of proton aurora during the growth phase is mainly due to continuous stretching of magnetic field lines, (2) the ballooning instability is more favorable during late growth phase around midnight tail where there is a localized plasma beta peak, and (3) the equatorial mapping of the breakup auroral arc is at X~-14 RE near midnight, coinciding with the location of the maximum growth rate for the ballooning instability.

  11. Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis.

    PubMed

    Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori

    2009-01-01

    The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump. PMID:19894088

  12. Nuclear magnetic resonance force microscopy: Adiabaticity, external field effects, and, Demonstration of magnet-on-oscillator detection with sub-micron resolution

    NASA Astrophysics Data System (ADS)

    Miller, Casey William

    Investigations of the adiabatic condition governing nuclear magnetic resonance force microscopy (NMR-FM) have been performed. It has been determined that the adiabatic conditional factor for protons in ammonium sulfate must have a value of 1.5 or greater to optimize the NMR-FM signal. A theoretical formalism is presented that describes the data. The characteristics of CoPt-capped single-crystal-silicon micro-oscillators with a magnetic field applied perpendicular to the magnetic film have been determined. The resonance frequency of the oscillators show two distinct regimes, one of softening and one of stiffening of the oscillator. A model is developed to describe the previously unseen softening. This work suggests that using NMR-FM with a magnetic particle on the oscillator is experimentally feasible. Magnet-on-oscillator NMR-FM has been demonstrated for the first time with our NMR-FM microscope using resonance slice thicknesses as small as ˜150 nm. The sample investigated was a semi-infinite slab of ammonium sulfate. The resonance slice of the microscope was scanned from vacuum into the sample by changing the tuned carrier frequency of the AC magnetic field H1. The resulting signal-to-noise ratio of ˜4 is slightly better than what was expected from conservative calculations. Finally, feasibility calculations and an experimental plan are set forth for the future measurement, of relaxation times of single crystals of the super-conductor magnesium diboride.

  13. The attenuation of the levitation force of HTS bulk exposed to AC magnetic field on the above NdFeB guideway

    NASA Astrophysics Data System (ADS)

    Liu, Minxian; Wang, Yan

    2012-01-01

    In the present High Temperature Superconducting (HTS) maglev vehicle system, the air gaps between the adjacent permanent magnets make the magnetic fields above the NdFeB guideway non-uniform. So it is required to study the characteristics of levitation force of the HTS bulk affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we have studied the characteristics of the levitation force relaxation by an experiment in which AC magnetic field generated by an electromagnet is used to simulate the time-varying magnetic field caused by the inhomogeneity of the NdFeB guideway. From the experiment results, it is found that the levitation force is attenuated with the application of the AC field, and the attenuation is increased with the amplitude of the AC field, but the attenuation is almost independent of the frequency the AC magnetic field.

  14. A review of a method for dynamic load distribution, dynamical modeling, and explicit internal force control when two manipulators mutually lift and transport a rigid body object

    SciTech Connect

    Unseren, M.A.

    1997-04-20

    The paper reviews a method for modeling and controlling two serial link manipulators which mutually lift and transport a rigid body object in a three dimensional workspace. A new vector variable is introduced which parameterizes the internal contact force controlled degrees of freedom. A technique for dynamically distributing the payload between the manipulators is suggested which yields a family of solutions for the contact forces and torques the manipulators impart to the object. A set of rigid body kinematic constraints which restrict the values of the joint velocities of both manipulators is derived. A rigid body dynamical model for the closed chain system is first developed in the joint space. The model is obtained by generalizing the previous methods for deriving the model. The joint velocity and acceleration variables in the model are expressed in terms of independent pseudovariables. The pseudospace model is transformed to obtain reduced order equations of motion and a separate set of equations governing the internal components of the contact forces and torques. A theoretic control architecture is suggested which explicitly decouples the two sets of equations comprising the model. The controller enables the designer to develop independent, non-interacting control laws for the position control and internal force control of the system.

  15. Effect of Perturbations in the Coriolis and Centrifugal Forces on the Stability of Equilibrium Points in the Restricted Four-Body Problem

    NASA Astrophysics Data System (ADS)

    Singh, Jagadish; Vincent, Aguda Ekele

    2015-10-01

    This paper studies numerically the existence, location and stability of equilibrium points under the influence of small perturbations in the Coriolis and centrifugal forces in the restricted four-body problem, where three of the bodies are finite, moving in circles around their centre of mass fixed at the origin of the coordinate system, according to the solutions of Lagrange where they are always at the vertices of an equilateral triangle, while the fourth one is infinitesimal. The fourth body does not affect the motion of the three bodies (primaries). We consider that the two masses of the primaries m2 and m3 are equal to ? and the dominant mass m1 is 1 - 2 ?. The allowed regions of motion as determined by the zero-velocity surfaces and the corresponding equipotential curves are given. The equations which determine equilibrium positions of the infinitesimal mass in the rotating coordinate system are found. This is observed that their positions are affected by a small perturbation in the centrifugal force, but are unaffected by that of the Coriolis force. For different values of the perturbation parameter , we obtain two collinear and six non-collinear equilibrium points. We also examine the linear stability of these equilibrium points for a wide range of the small perturbations and all points found unstable except two (L7,8) which are stable.

  16. Monocoil reciprocating permanent magnet electric machine with self-centering force

    NASA Technical Reports Server (NTRS)

    Bhate, Suresh K. (Inventor); Vitale, Nicholas G. (Inventor)

    1989-01-01

    A linear reciprocating machine has a tubular outer stator housing a coil, a plunger and an inner stator. The plunger has four axially spaced rings of radially magnetized permanent magnets which cooperate two at a time with the stator to complete first or second opposite magnetic paths. The four rings of magnets and the stators are arranged so that the stroke of the plunger is independent of the axial length of the coil.

  17. Effects of repulsive three-body force in 12C + 12C scattering at 100A MeV

    NASA Astrophysics Data System (ADS)

    Qu, W. W.; Zhang, G. L.; Terashima, S.; Furumoto, T.; Ayyad, Y.; Chen, Z. Q.; Guo, C. L.; Inoue, A.; Le, X. Y.; Ong, H. J.; Pang, D. Y.; Sakaguchi, H.; Sakuragi, Y.; Sun, B. H.; Tamii, A.; Tanihata, I.; Wang, T. F.; Wada, R.; Yamamoto, Y.

    2015-12-01

    The angular distribution of 12C + 12C scattering at an incident energy of 100A MeV has been measured. The elastic and inelastic scatterings in 12C to the excitation energies of up to ? 45 MeV were measured simultaneously for the first time with the high-resolution Grand Raiden spectrometer at the Research Center for Nuclear Physics (RCNP). The angular distributions of the elastic scattering to the ground state (01+) and inelastic scattering to the 4.44 MeV (21+) excited state were precisely obtained in the angular range of 1.0°-7.5° with a step of 0.1°. Additionally, the angular distribution was obtained for the sum of the cross sections for excitation energies above the 4.44 MeV state up to 11 MeV, which includes the 7.65 MeV (02+), 9.64 MeV (31-), and 10.30 MeV (22+) states, in addition to probably the simultaneous excitation of the 4.44 MeV state in the projectile and the target nuclei. Those combined data provide a means to study the effects of channel coupling on the elastic cross section. The observed angular distributions are compared with theoretical calculations based on three double-folding models with complex G-matrix interactions, the CEG07b, MPa, and ESC models. The importance of three-body repulsive forces included in the CEG07b and MPa models will be discussed.

  18. Theory of spin relaxation in magnetic resonance force microscopy D. Mozyrsky and I. Martina)

    E-print Network

    Hammel, P. Chris

    . There is an additional constant magnetic field B0 applied normally to the sample, and a linearly polarized microwave magnetic field B1 cos( rft) in a direction perpendicular to B0 . The magnetic resonance condition rf of the microwave field be chosen such that g B Btip 0 (r) B0 rf , where g is elec- tronic g factor

  19. The mean electro-motive force, current- and cross-helicity under the influence of rotation, magnetic field and shear

    E-print Network

    V. V. Pipin

    2007-01-22

    The mean electromotive force (MEMF) in a rotating stratified magnetohydrodynamical turbulence is studied.Our study rests on the mean-field magnetohydrodynamics framework and $\\tau$ approximation. We compute the effects of the large-scale magnetic fields (LSMF), global rotation and large-scale shear flow on the different parts of the MEMF (such as $\\alpha$ - effect, turbulent diffusion, turbulent transport, etc.) in an explicit form. The influence of the helical magnetic fluctuations which stem from the small-scale dynamo is taken into account, as well. In the paper, we derive the equation governing the current helicity evolution. It is shown that the joint effect of the differential rotation and magnetic fluctuations in the stratified media can be responsible for the generation, maintenance and redistribution of the current helicity. The implication of the obtained results to astrophysical dynamos is considered as well.

  20. THE ABRUPT CHANGES IN THE PHOTOSPHERIC MAGNETIC AND LORENTZ FORCE VECTORS DURING SIX MAJOR NEUTRAL-LINE FLARES

    SciTech Connect

    Petrie, G. J. D.

    2012-11-01

    We analyze the spatial and temporal variations of the abrupt photospheric magnetic changes associated with six major flares using 12 minute, 0.''5 pixel{sup -1} vector magnetograms from NASA's Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory satellite. The six major flares occurred near the main magnetic neutral lines of four active regions, NOAA 11158, 11166, 11283, and 11429. During all six flares the neutral-line field vectors became stronger and more horizontal, in each case almost entirely due to strengthening of the horizontal field components parallel to the neutral line. In all six cases the neutral-line pre-flare fields were more vertical than the reference potential fields, and collapsed abruptly and permanently closer to potential-field tilt angles during every flare, implying that the relaxation of magnetic stress associated with non-potential tilt angles plays a major role during major flares. The shear angle with respect to the reference potential field did not show such a pattern, demonstrating that flare processes do not generally relieve magnetic stresses associated with photospheric magnetic shear. The horizontal fields became significantly and permanently more aligned with the neutral line during the four largest flares, suggesting that the collapsing field is on average more aligned with the neutral line than the pre-flare neutral-line field. The vertical Lorentz force had a large, abrupt, permanent downward change during each of the flares, consistent with loop collapse. The horizontal Lorentz force changes acted mostly parallel to the neutral line in opposite directions on each side, a signature of the fields contracting during the flare, pulling the two sides of the neutral line toward each other. The greater effect of the flares on field tilt than on shear may be explained by photospheric line-tying.

  1. Anomalous diffusion of field lines and charged particles in Arnold-Beltrami-Childress force-free magnetic fields

    SciTech Connect

    Ram, Abhay K.; Dasgupta, Brahmananda; Krishnamurthy, V.; Mitra, Dhrubaditya

    2014-07-15

    The cosmic magnetic fields in regions of low plasma pressure and large currents, such as in interstellar space and gaseous nebulae, are force-free in the sense that the Lorentz force vanishes. The three-dimensional Arnold-Beltrami-Childress (ABC) field is an example of a force-free, helical magnetic field. In fluid dynamics, ABC flows are steady state solutions of the Euler equation. The ABC magnetic field lines exhibit a complex and varied structure that is a mix of regular and chaotic trajectories in phase space. The characteristic features of field line trajectories are illustrated through the phase space distribution of finite-distance and asymptotic-distance Lyapunov exponents. In regions of chaotic trajectories, an ensemble-averaged variance of the distance between field lines reveals anomalous diffusion—in fact, superdiffusion—of the field lines. The motion of charged particles in the force-free ABC magnetic fields is different from the flow of passive scalars in ABC flows. The particles do not necessarily follow the field lines and display a variety of dynamical behavior depending on their energy, and their initial pitch-angle. There is an overlap, in space, of the regions in which the field lines and the particle orbits are chaotic. The time evolution of an ensemble of particles, in such regions, can be divided into three categories. For short times, the motion of the particles is essentially ballistic; the ensemble-averaged, mean square displacement is approximately proportional to t{sup 2}, where t is the time of evolution. The intermediate time region is defined by a decay of the velocity autocorrelation function—this being a measure of the time after which the collective dynamics is independent of the initial conditions. For longer times, the particles undergo superdiffusion—the mean square displacement is proportional to t{sup ?}, where ??>?1, and is weakly dependent on the energy of the particles. These super-diffusive characteristics, both of magnetic field lines and of particles moving in these fields, strongly suggest that theories of transport in three-dimensional chaotic magnetic fields need a shift from the usual paradigm of quasilinear diffusion.

  2. Floating Bodies of Equilibrium in 2D, the Tire Track Problem and Electrons in a Parabolic Magnetic Field

    E-print Network

    Franz J. Wegner

    2007-09-14

    Explicit solutions of the two-dimensional floating body problem (bodies that can float in all positions) for relative density different from 1/2 and of the tire track problem (tire tracks of a bicycle, which do not allow to determine, which way the bicycle went) are given, which differ from circles. Starting point is the differential equation given by the author in archive physics/0205059 and Studies in Appl. Math. 111 (2003) 167-183. The curves are also trajectories of charges in a perpendicular magnetic field.

  3. Effect of self-consistent magnetic field on plasma sheet penetration to the inner magnetosphere under enhanced convection: RCM simulations combined with force-balance magnetic field solver

    NASA Astrophysics Data System (ADS)

    Gkioulidou, M.; Wang, C.; Lyons, L. R.; Wolf, R. A.

    2010-12-01

    Transport of plasma sheet particles into the inner magnetosphere is strongly affected by the penetration of the convection electric field, which is the result of the large-scale magnetosphere-ionosphere electromagnetic coupling. This transport, on the other hand, results in plasma heating and magnetic field stretching, which become very significant in the inner plasma sheet (inside 20 RE). We have previously run simulations with the Rice Convection Model (RCM) to investigate how the earthward penetration of convection electric field, and therefore plasma sheet population, depends on plasma sheet boundary conditions. Outer boundary conditions at r ~20 RE are a function of MLT and interplanetary conditions based on 11 years of Geotail data. In the previous simulations, Tsyganenko 96 magnetic field model (T96) was used so force balance between plasma pressure and magnetic fields was not maintained. We have now integrated the RCM with a magnetic field solver (Liu et al., 2006) to obtain the required force balance in the equatorial plane. We have run the self-consistent simulations under enhanced convection with different boundary conditions in which we kept different parameters (flux tube particle content, plasma pressure, plasma beta, or magnetic fields) at the outer boundary to be MLT-dependent but time independent. Different boundary conditions result in qualitatively similar plasma sheet profiles. The results show that magnetic field has a dawn dusk asymmetry with field lines being more stretched in the pre-midnight sector, due to relatively higher plasma pressure there. The asymmetry in the magnetic fields in turn affects the radial distance and MLT of plasma sheet penetration into the inner magnetosphere. In comparison with results using the T96, plasma transport under self-consistent magnetic field results in proton and electron plasma sheet inner edges that are located in higher latitudes, weaker pressure gradients, and more efficient shielding of the near-Earth convection electric field (since auroral conductance is also confined to higher latitudes). We are currently evaluating the simulated plasma sheet properties by comparing them with statistical results obtained from Geotail and THEMIS observations.

  4. High-resolution and high-coercivity FePtL10 magnetic force microscopy nanoprobes to study next-generation magnetic recording media

    NASA Astrophysics Data System (ADS)

    Amos, Nissim; Lavrenov, Andrey; Fernandez, Robert; Ikkawi, Rabee; Litvinov, Dmitri; Khizroev, Sakhrat

    2009-04-01

    A cylindrical probe with almost perfectly flat plateaulike surface was focused ion beam (FIB) milled from an atomic force microscopy probe in order to create the required surface conditions for thin film deposition with finely controlled deposition/growth parameters. A composition of Pd(5 nm)/MgO(8 nm)/FePt(10 nm)/MgO(8 nm) was sputter deposited on the plateau probe, followed by deposition of a Pd (5 nm) protective layer. The plateau probe was then FIB-milled to produce a tip with a curvature radius of ˜25 nm. After annealing the probe at 650 °C for ˜15 min to generate an ultrahigh anisotropy L10 phase, magnetic force microscopy (MFM) imaging was performed with the probe on magnetic tracks with linear densities ranging from 200 to 1200 KFCI. The results show sub-20-nm lateral resolution in ambient conditions and magnetic tracks, which are otherwise invisible to standard MFM probes, are clearly evident with the FIB-fabricated FePt probe. With relatively high spatial resolution and coercivity values higher than 1 T, among other applications, this type of probe may be ideal for high-quality MFM study of next-generation recording media.

  5. Correlations in light nuclei and their relation to fine tuning and uncertainty quantifications of many body forces in low-energy nuclear physics

    E-print Network

    Sergiu Lupu; Nir Barnea; Doron Gazit

    2015-08-23

    The large nucleon-nucleon scattering length, and the isospin approximate symmetry, are low energy properties of quantum chromodynamics (QCD). These entail correlations in the binding energies of light nuclei, e.g., the A=3 iso-multiplet, and Tjon's correlation between the binding energy of three and four body nuclei. Using a new representation of these, we establish that they translate into a correlation between different short-range contributions to three body forces in chiral effective field theory of low-energy nuclear physics. We demonstrate that these correlations should be taken into account in order to avoid fine-tuning in the calibration of three body forces. We relate this to the role of correlations in uncertainty quantification of non-renormalizable effective field theories of the nuclear regime. In addition, we show that correlations can be useful in assessing the importance of forces induced by renormalization group (RG) transformations. We give numerical evidence that such RG transformations can be represented effectively by adding a constant to the pure three nucleon contact low energy constant $c_E$.

  6. Nonlinear force-free magnetic field extrapolations: comparison of the Grad-Rubin and Wheatland-Sturrock-Roumeliotis algorithm

    E-print Network

    B. Inhester; T. Wiegelmann

    2008-01-23

    We compare the performance of two alternative algorithms which aim to construct a force-free magnetic field given suitable boundary conditions. For this comparison, we have implemented both algorithms on the same finite element grid which uses Whitney forms to describe the fields within the grid cells. The additional use of conjugate gradient and multigrid iterations result in quite effective codes. The Grad-Rubin and Wheatland-Sturrock-Roumeliotis algorithms both perform well for the reconstruction of a known analytic force-free field. For more arbitrary boundary conditions the Wheatland-Sturrock-Roumeliotis approach has some difficulties because it requires overdetermined boundary information which may include inconsistencies. The Grad-Rubin code on the other hand loses convergence for strong current densities. For the example we have investigated, however, the maximum possible current density seems to be not far from the limit beyond which a force free field cannot exist anymore for a given normal magnetic field intensity on the boundary.

  7. Measurement of changes in body composition of piglets from birth to 4 kg using quantitative magnetic resonance (QMR)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this study was to use quantitative magnetic resonance (QMR) to measure changes in the body composition of piglets during growth from birth to 4 kg BW. Using QMR, 60 pigs were scanned an average of 5 times starting at 2.7±1.3 d of age (1.95 kg) and finally at 13.1±4.3 d (4.14 kg). Regr...

  8. Standardized image interpretation and post processing in cardiovascular magnetic resonance: Society for Cardiovascular Magnetic Resonance (SCMR) Board of Trustees Task Force on Standardized Post Processing

    PubMed Central

    2013-01-01

    With mounting data on its accuracy and prognostic value, cardiovascular magnetic resonance (CMR) is becoming an increasingly important diagnostic tool with growing utility in clinical routine. Given its versatility and wide range of quantitative parameters, however, agreement on specific standards for the interpretation and post-processing of CMR studies is required to ensure consistent quality and reproducibility of CMR reports. This document addresses this need by providing consensus recommendations developed by the Task Force for Post Processing of the Society for Cardiovascular MR (SCMR). The aim of the task force is to recommend requirements and standards for image interpretation and post processing enabling qualitative and quantitative evaluation of CMR images. Furthermore, pitfalls of CMR image analysis are discussed where appropriate. PMID:23634753

  9. Measurement of total body water in human infants using deuterium isotope dilution and nuclear magnetic resonance spectroscopy

    SciTech Connect

    Rebouche, C.J.; Pearson, G.A.; Serfass, R.E.; Roth, C.W.; Finley, J.W.

    1986-03-01

    Total body water (TBW) provides a useful measure of fat-free body mass. Deuterium (D) oxide isotope dilution is a useful method to determine TBW. Various techniques, including density, infrared absorption, mass spectrometry and gas chromatography have been employed to determine D enrichment in body fluids. Each of these methods requires extensive sample preparation (sublimation or distillation of the body fluid). The authors have employed nuclear magnetic resonance (NMR) spectroscopy to measure D enrichment in saliva and urine of human infants. No sample preparation was necessary. A standard (dg-t-butanol) was added to 0.5 ml of sample and D enrichment was measured using a JEOL FX-900 NMR spectrometer. Signal acquisition time was 4.7 min. Working range of D enrichment was 0.04-0.32 atom % D (corresponding to an oral dose of approximately 0.25-2.0 g D/sub 2/O/kg body weight). Coefficients of variation (c.v.) for saliva samples at 0.20 and 0.06 atom % enrichment were 1.97% and 4.78%, respectively. Mean (+/-SD) of TBW determinations for 6 infants was 58.5 +/- 5.4% of body weight (range 53-66%). Repeat measurements (3) of TBW for each infant at weekly intervals yielded a mean c.v. of 4.1% (n = 6). This method provides precise measurement of TBW without the extensive sample preparation requirements of previously-described methods.

  10. Effect of the magnetic field direction on forced convection heat transfer enhancements in ferrofluids

    NASA Astrophysics Data System (ADS)

    Cherief, Wahid; Avenas, Yvan; Ferrouillat, Sébastien; Kedous-Lebouc, Afef; Jossic, Laurent; Berard, Jean; Petit, Mickael

    2015-07-01

    Applying a magnetic field on a ferrofluid flow induces a large increase of the convective heat transfer coefficient. In this paper, the thermal-hydraulic behaviors of two commercial ferrofluids are compared. The variations of both the pressure drop and the heat transfer coefficient due to the magnetic field are measured in the following conditions: square duct, laminar flow and uniform wall heat flux. The square section with two insulated walls allows for the characterization of the effect of the magnetic field direction. The experimental results show that the heat transfer is better enhanced when the magnetic field is perpendicular to the heat flux. In the best case, the local heat transfer coefficient increase is about 75%. On the contrary, another experimental setup shows no enhancement of thermal conductivity when the magnetic field is perpendicular to the heat flux. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014) - Elected submissions", edited by Adel Razek

  11. The unified strain and temperature scaling law for the pinning force density of bronze-route Nb3Sn wires in high magnetic fields

    E-print Network

    Hampshire, Damian

    The unified strain and temperature scaling law for the pinning force density of bronze-route Nb3Sn wires in high magnetic fields Najib Cheggour 1 , Damian P. Hampshire * Superconductivity Group) of a bronze-route niobium­tin wire are presented for magnetic fields (B) up to 15 T as a function

  12. Influence of dust charge fluctuation and polarization force on radiative condensation instability of magnetized gravitating dusty plasma

    NASA Astrophysics Data System (ADS)

    Prajapati, R. P.; Bhakta, S.

    2015-10-01

    The influence of dust charge fluctuation, thermal speed and polarization force due to massive charged dust grains is studied on the radiative condensation instability (RCI) of magnetized self-gravitating astrophysical dusty (complex) plasma. The dynamics of the charged dust and inertialess electrons are considered while the Boltzmann distributed ions are assumed to be thermal. The dusty fluid model is formulated and the general dispersion relations are derived analytically using the plane wave solutions under the long wavelength limits in both the presence and the absence of dust charge fluctuations. The combined effects of polarization force, dust thermal speed, dust charge fluctuation and dust cyclotron frequency are observed on the low frequency wave modes and radiative modified Jeans Instability. The classical criterion of RCI is also derived which remains unaffected due to the presence of these parameters. Numerical calculations have been performed to calculate the growth rate of the system and plotted graphically. We find that dust charge fluctuation, radiative cooling and polarization force have destabilizing while dust thermal speed and dust cyclotron frequency have stabilizing influence on the growth rate of Jeans instability. The results have been applied to understand the radiative cooling process in dusty molecular cloud when both the dust charging and polarization force are dominant.

  13. Force-free magnetosphere of an aligned rotator with differential rotation of open magnetic field lines

    E-print Network

    Andrey N. Timokhin

    2006-09-07

    Here we briefly report on results of self-consistent numerical modeling of a differentially rotating force-free magnetosphere of an aligned rotator. We show that differential rotation of the open field line zone is significant for adjusting of the global structure of the magnetosphere to the current density flowing through the polar cap cascades. We argue that for most pulsars stationary cascades in the polar cap can not support stationary force-free configurations of the magnetosphere.

  14. Sunspots and the physics of magnetic flux tubes. V - Mutual hydrodynamic forces between neighboring tubes

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1979-01-01

    The mutual hydrodynamic forces between parallel cylinders in a moving fluid are illustrated through several formal examples. Parallel tubes in a uniform flow are attracted or repelled depending on whether they are side by side or one ahead of the other, respectively. A pulsating or undulating tube attracts all other neighboring tubes toward itself. These hydrodynamic effects suggest that the separate flux tubes beneath the sunspots exert significant attractive forces on each other.

  15. Specific features of the thermal electromotive force in Bi quantum wires in transverse magnetic and electric fields

    NASA Astrophysics Data System (ADS)

    Sinyavskii, E. P.; Solovenko, V. G.

    2014-11-01

    The thermal electromotive force (emf) in Bi quantum wires has been calculated in the model of potential in the form of a paraboloid of revolution in a uniform magnetic field H, which is normal to the axis of the studied nanostructure, and in a direct-current (dc) electric field E ? H. It has been shown that, with an increase in E, the thermal emf ?xx is described by a nonmonotonic function at different values of H. A physical interpretation of this behavior of ?xx as a function of E is proposed with account for the interaction between carriers and the rough surface of the nanowire.

  16. A constitutive model for the forces of a magnetic bearing including eddy currents

    NASA Technical Reports Server (NTRS)

    Taylor, D. L.; Hebbale, K. V.

    1993-01-01

    A multiple magnet bearing can be developed from N individual electromagnets. The constitutive relationships for a single magnet in such a bearing is presented. Analytical expressions are developed for a magnet with poles arranged circumferencially. Maxwell's field equations are used so the model easily includes the effects of induced eddy currents due to the rotation of the journal. Eddy currents must be included in any dynamic model because they are the only speed dependent parameter and may lead to a critical speed for the bearing. The model is applicable to bearings using attraction or repulsion.

  17. The scaling of reconnection rate in the two-fluid model of a collisionless forced magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Hosseinpour, M.; Hosseinpour

    2013-10-01

    The two-fluid model of collisionless forced magnetic reconnection is considered where breaking the frozen-in flow constraint for magnetic field lines is provided by electron inertia. Following the Taylor problem, a tearing stable slab of plasma with a magnetic field reversal is subjected to a small-amplitude boundary perturbation that drives magnetic reconnection at the neutral surface within the plasma. It has been shown that unlike the resistive regime, where the two-fluid magnetohydrodynamics (MHD) description reduces to the single-fluid MHD regime at sufficiently small values of the ion inertial skin-depth, di ? c/? pi (with ? pi as the ion plasma frequency), there is no room for the single-fluid MHD reconnection in the collisionless case, even at very small values of di . Meanwhile, contradictory to the resistive reconnection, the rate of collisionless Hall reconnection always decreases with time as reconnection proceeds. In particular, in the main stage of Hall reconnection, when transition between two main equilibria states are taking place, it scales as t -1/2.

  18. Structure and Stability of Magnetic Fields in Solar Active Region12192 Based on Nonlinear Force-Free Field Modeling

    E-print Network

    Inoue, S; Kusano, K

    2016-01-01

    We analyze a three-dimensional (3D) magnetic structure and its stability in large solar active region(AR) 12192, using the 3D coronal magnetic field constructed under a nonlinear force-free field (NLFFF) approximation. In particular, we focus on the magnetic structure that produced an X3.1-class flare which is one of the X-class flares observed in AR 12192. According to our analysis, the AR contains multiple-flux-tube system, {\\it e.g.}, a large flux tube, both of whose footpoints are anchored to the large bipole field, under which other tubes exist close to a polarity inversion line (PIL). These various flux tubes of different sizes and shapes coexist there. In particular, the later are embedded along the PIL, which produces a favorable shape for the tether-cutting reconnection and is related to the X-class solar flare. We further found that most of magnetic twists are not released even after the flare, which is consistent with the fact that no observational evidence for major eruptions was found. On the oth...

  19. A novel method of evaluating the lift force on the bluff body based on Noca’s flux equation

    NASA Astrophysics Data System (ADS)

    Sui, Xiang-Kun; Jiang, Nan

    2015-08-01

    The influence of experimental error on lift force evaluated by Noca’s flux equation is studied based on adding errors into the direct numerical simulation data for flow past cylinder at Re = 100. As Noca suggested using the low-pass filter to get rid of the high-frequency noise in the evaluated lift force, we verify that his method is inapplicable for dealing with the dataset of 1% experimental error, although the precision is acceptable in practice. To overcome this defect, a novel method is proposed in this paper. The average of the lift forces calculated by using multiple control volume is taken as the evaluation before applying the low-pass filter. The method is applied to an experimental data for flow past a cylinder at approximately Re = 900 to verify its validation. The results show that it improves much better on evaluating the lift forces.

  20. A 4 K cryogenic probe for use in magnetic resonance force microscopy experiments

    SciTech Connect

    Smith, Doran D.; Alexson, Dimitri A.; Garbini, Joseph L.

    2013-09-15

    The detailed design of a mechanically detected nuclear magnetic resonance probe using the SPAM (Springiness Preservation by Aligning Magnetization) geometry, operating at 4 K, in vacuum, and a several-Tesla magnetic field is described. The probe head is vibration-isolated well enough from the environment by a three-spring suspension system that the cantilever achieves thermal equilibrium with the environment without the aid of eddy current damping. The probe uses an ultra-soft Si cantilever with a Ni sphere attached to its tip, and magnetic resonance is registered as a change in the resonant frequency of the driven cantilever. The RF system uses frequency sweeps for adiabatic rapid passage using a 500 ?m diameter RF coil wound around a sapphire rod. The RF coil and optical fiber of the interferometer used to sense the cantilever's position are both located with respect to the cantilever using a Garbini micropositioner, and the sample stage is mounted on an Attocube nanopositioner.

  1. Planetary rings as relics of plasma proto-rings rotating in the magnetic field of a central body

    NASA Astrophysics Data System (ADS)

    Rabinovich, B.

    2007-08-01

    A possibility is discussed in accordance to hypothesis by H. Alfven, that the rings of large planets are relics of some plasma proto-rings rotating in the magnetic fields of central bodies. A finite-dimensional mathematical model of the system is synthesized using the solution of the boundary-value problem by the Boubnov - Galerkin method. The dipole magnetic field of the central body is assumed to have a small eccentricity, and the dipole axis - to be inclined at a small angle to the central body's axis of rotation which coincides with the ring's rotation axis. The proto-ring is supposed to be thin and narrow and having the same rotating axis as the central body. A medium forming the ring is cold rarefied plasma with high electron density, so that electric conductivity of the medium tends to infinity, as well as the magnetic Reynolds number. The original mathematical model is reduced to a system of finite-difference equations whose asymptotic analytical solution is obtained. Emphasis is placed on the problems of stability of the ring's steady state rotation and quantization of the eigenvalues of nondimensional sector velocity of the ring with respect to the central body. The solutions corresponding to magneto-gravitational and to magneto-gyroscopic waves are considered It is demonstrated that some rings characterized by integral quantum numbers are stable and long-living, while the rings which are associated with half-integer quantum numbers () are unstable and short-living. As a result, an evolutionally rife rotating plasma ring turns out to be stratified into a large number of narrow elite rings separated by gaps whose position correspond to anti-rings. The regions of possible existence of elite rings in near-central body space are determined. The main result of eigenvalue spectrum's analysis is as follows. Quantum numbers determining elite eigenvalues of the sector velocity of a ring (normalized in a certain manner) coincide with the quantum numbers appearing in the solution of the Schr¨odingerequation for a hydrogen atom. Perturbations of the elite orbits corresponding to this numbers satisfy the de Brogli quantum-mechanical condition. The solution of the model boundary-value problem has been applied to planetary rings origin and evolution. The main result is a mechanism of stratification of the evolutionally mature plasma proto-ring into a large number of narrow elite rings separated by anti-rings (gaps), which were playing a role of for present-day planetary rings. Another result is the theoretical substantiation of the presence in the nearplanetary space of a region of existence and stability of plasma rings. The data, which had been obtained in the course of the Voyager, Galileo, and Cassini missions were used for verification of theoretical results concerning the planetary rings and Io plasma thorus. The theoretical dates turned out to be in accordance with experimental dates. References Alfven H. Cosmic Plasma. Dordrecht: Reidel, 1961. Rabinovich B.I. Dynamics of Plasma Ring Rotating in the Magnetic Field of Central Body: Magneto-GravitationalWaves // Cosmic Research, 2006. V. 44. No. 1. P. 43-51. Rabinovich B.I. Dynamics of Plasma Ring Rotating in the Magnetic Field of Central Body: Magneto-Gyroscopic Waves. Problems of Stability and Quantization // Cosmic Research, 2006. V. 44. No. 2. P. 146 - 161. Gore, Rick. Voyager 1 at Saturn. Riddles of the Rings // National Geographic, 1981. V. 160. No. 1. P. 3 - 31. Porco, Carolyn. Captain 's Log.: 2004, 184 // The Planetary Report, 2004. V. 24, No. 5. P. 2 - 18.

  2. Magnetic Force Microscopy Study of Zr2Co11 -Based Nanocrystalline Materials: Effect of Mo Addition

    DOE PAGESBeta

    Yue, Lanping; Jin, Yunlong; Zhang, Wenyong; Sellmyer, David J.

    2015-01-01

    The addition of Molybdenum was used to modify the nanostructure and enhance coercivity of rare-earth-free Zr2Co11-based nanocrystalline permanent magnets. The effect of Mo addition on magnetic domain structures of melt spun nanocrystalline Zr16Co84-xMox(x=0, 0.5, 1, 1.5, and 2.0) ribbons has been investigated. It was found that magnetic properties and local domain structures are strongly influenced by Mo doping. The coercivity of the samples increases with the increase in Mo content (x?1.5). The maximum energy product(BH)maxincreases with increasingxfrom 0.5?MGOe forx=0to a maximum value of 4.2?MGOe forx=1.5. The smallest domain size with a relativelymore »short magnetic correlation length of 128?nm and largest root-mean-square phase shift?rmsvalue of 0.66° are observed for thex=1.5. The optimal Mo addition promotes magnetic domain structure refinement and thus leads to a significant increase in coercivity and energy product in this sample.« less

  3. Force-free field modeling of twist and braiding-induced magnetic energy in an active-region corona

    SciTech Connect

    Thalmann, J. K.

    2014-01-01

    The theoretical concept that braided magnetic field lines in the solar corona may dissipate a sufficient amount of energy to account for the brightening observed in the active-region (AR) corona has only recently been substantiated by high-resolution observations. From the analysis of coronal images obtained with the High Resolution Coronal Imager, first observational evidence of the braiding of magnetic field lines was reported by Cirtain et al. (hereafter CG13). We present nonlinear force-free reconstructions of the associated coronal magnetic field based on Solar Dynamics Observatory/Helioseismic and Magnetic Imager vector magnetograms. We deliver estimates of the free magnetic energy associated with a braided coronal structure. Our model results suggest (?100 times) more free energy at the braiding site than analytically estimated by CG13, strengthening the possibility of the AR corona being heated by field line braiding. We were able to appropriately assess the coronal free energy by using vector field measurements and we attribute the lower energy estimate of CG13 to the underestimated (by a factor of 10) azimuthal field strength. We also quantify the increase in the overall twist of a flare-related flux rope that was noted by CG13. From our models we find that the overall twist of the flux rope increased by about half a turn within 12 minutes. Unlike another method to which we compare our results, we evaluate the winding of the flux rope's constituent field lines around each other purely based on their modeled coronal three-dimensional field line geometry. To our knowledge, this is done for the first time here.

  4. Estimating body segment orientation by applying inertial and magnetic sensing near ferromagnetic materials.

    PubMed

    Roetenberg, Daniel; Baten, Chris T M; Veltink, Peter H

    2007-09-01

    Inertial and magnetic sensors are very suitable for ambulatory monitoring of human posture and movements. However, ferromagnetic materials near the sensor disturb the local magnetic field and, therefore, the orientation estimation. A Kalman-based fusion algorithm was used to obtain dynamic orientations and to minimize the effect of magnetic disturbances. This paper compares the orientation output of the sensor fusion using three-dimensional inertial and magnetic sensors against a laboratory bound opto-kinetic system (Vicon) in a simulated work environment. With the tested methods, the difference between the optical reference system and the output of the algorithm was 2.6 degrees root mean square (rms) when no metal was near the sensor module. Near a large metal object instant errors up to 50 degrees were measured when no compensation was applied. Using a magnetic disturbance model, the error reduced significantly to 3.6 degrees rms. PMID:17894280

  5. Paleoclimatic forcing of magnetic susceptibility variations in Alaskan loess during the late Quaternary

    SciTech Connect

    Beget, J.E.; Stone, D.B.; Hawkins, D.B. )

    1990-01-01

    Visual matches and statistical tests suggest correlations between marine isotope curves, retrodictive solar insolation at lat 65{degree}N, and magnetic susceptibility profiles through late Quaternary age Alaskan loess sections. The susceptibility changes largely appear to reflect variability in magnetite content due to climatically controlled changes in wind intensity and competence. Magnetic susceptibility profiles through massive loess can provide stratigraphic context for intercalated paleosols and tephras. A prominent paleosol correlated with marine isotope stage 5 occurs several metres above the Old Crow ash in loess sections, indicating that this important tephra is older than suggested by thermoluminescence dates, and may have been deposited ca. 215 {plus minus}25 ka.

  6. Investigation of Three-Body Force Effects in Neutron-Deuteron Scattering at 95 MeV

    SciTech Connect

    Mermod, P.; Blomgren, J.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Klug, J.; Oesterlund, M.; Pomp, S.; Nilsson, L.; Olsson, N.; Tippawan, U.; Jonsson, O.; Prokofiev, A.; Renberg, P.-U.; Nadel-Turonski, P.; Maeda, Y.; Sakai, H.; Tamii, A.

    2005-05-24

    We have measured the neutron-deuteron (nd) elastic-scattering differential cross section at 95 MeV incident neutron energy, using both the Medley and the SCANDAL setups at TSL in Uppsala. The full angular distribution was covered by detecting recoil deuterons from thin CD2 targets, and the result was normalized to the neutron-proton (np) cross section. Recent theories predict that three-nucleon (3N) force effects, if present, would affect the cross section in the minimum region by about 30%. The results are compared with theoretical calculations and are well described if 3N forces are included.

  7. In vivo measurement of body composition of chickens using quantitative magnetic resonance (QMR)and dual x-ray absorptiometry (DXA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    QMR is a nuclear magnetic resonance based method for measuring the fat, lean and water content of the total body of the live animal. The purpose of this study was to evaluate the use of QMR for measuring the body composition of chickens while comparing QMR results to those obtained by dual X-ray ab...

  8. Exchange spring in A1/L1{sub 0} FePt composite and its application in magnetic force microscope

    SciTech Connect

    Li, Guoqing Zhu, Yanyan Zhang, Yong; Zhao, Hujun; Zeng, Daofu; Li, Yuhui; Lu, Wei

    2015-02-23

    This paper reported fabrication of Fe{sub x}Pt{sub 100-x} films with (001) epitaxy on MgO(100) substrates. The atomic percentage of Fe was changed within the range of x?=?10–85 in order to search the optimal atomic ratio for achieving both high and isotropic-like coercivity. It was found that the Fe{sub 60}Pt{sub 40} film exhibited large coercivities exceeding 5 kOe along both in-plane and out-of-plane directions due to the formation of A1/L1{sub 0} FePt composite. A penta-domain model for hard/soft/hard exchange spring system was proposed to interpret the anomalous magnetization behaviors observed in Fe{sub 60}Pt{sub 40} sample. By using Fe{sub 60}Pt{sub 40} as the magnetic coating layer on a probe of magnetic force microscope, the flux changes at a linear density of 1000 kfci could be readily observed at a resolution of ?13?nm.

  9. A single cell culture system using lectin-conjugated magnetite nanoparticles and magnetic force to screen mutant cyanobacteria.

    PubMed

    Arai, Sayuri; Okochi, Mina; Shimizu, Kazunori; Hanai, Taizo; Honda, Hiroyuki

    2016-01-01

    Cyanobacteria can be utilized as a potential biocatalyst for the production of biofuels and biochemicals directly from CO2 . Useful mutants of cyanobacteria, which can grow rapidly or are resistant to specific metabolic products, are essential to improve the productivity of biofuels. In this study, we developed a single cell culture system to effectively screen mutant cyanobacteria using magnetite nanoparticles and magnetic force. Lens culinaris Agglutinin (LCA) was selected as a lectin, which binds to the surface of Synechococcus elongatus PCC7942 cells and the LCA-conjugated magnetite cationic liposomes (MCLs) were developed for magnetic labeling of PCC7942 cells. The MCL-labeled PCC7942 cells were magnetically patterned at a single cell level by using 6,400 iron pillars of the pin-holder device. The device enabled 1,600 single cells to be arrayed in one square centimeter. We cultured the patterned cells in liquid medium and achieved higher colony-forming ratio (78.4%) than that obtained using conventional solid culture method (4.8%). Single cells with different properties could be distinguished in the single cell culture system depending on their growth. Furthermore, we could selectively pick up the target cells and subsequently perform efficient isolation culture. The ratio of successful isolation culture using the developed method was 13 times higher than that of the conventional methods. Thus, the developed system would serve as a powerful tool for screening mutant cyanobacteria. Biotechnol. Bioeng. 2016;113: 112-119. © 2015 Wiley Periodicals, Inc. PMID:26175102

  10. MEMS-based force-detected nuclear magnetic resonance spectrometer for in situ planetary exploration

    NASA Technical Reports Server (NTRS)

    George, T.; Leskowitz, G.; Madsen, L.; Weitekamp, D.; Tang, W.

    2000-01-01

    Nuclear Magnetic resonance (NMR) is a well-known spectroscopic technique used by chemists and is especially powerful in detecting the presence of water and distinguishing between arbitrary physisorbed and chemisorbed states. This ability is of particular importance in the search for extra-terrestrial life on planets such as Mars.

  11. An effective field theory for neutron stars with many-body forces, strong ?- repulsion, and K- and \\bar{K}0 condensation

    NASA Astrophysics Data System (ADS)

    Mesquita, A.; Razeira, M.; Ruffini, R.; Rueda, J. A.; Hadjimichef, D.; Gomes, R. O.; Vasconcellos, C. A. Zen

    2015-11-01

    The role of many-body correlations (many-body forces) and K--\\bar{K}0 condensation in ?-equilibrated hyperonic matter is investigated in order to shed some light in the hyperonization puzzle, ie that neutron star mass of 2 M? cannot be obtained in the presence of exotic degree of freedoms. In this investigation, we use an effective relativistic QHD-model with parameterized couplings which represents an extended compilation of other effective models found in the literature. Our theoretical approach exhausts the whole fundamental baryon octet (n, p, ?-, ?0, ?+, ?, ?-, ?0) and simulates n-order corrections to the minimal Yukawa couplings by considering many-body nonlinear self-couplings and meson-meson interaction terms involving scalar-isoscalar (?, ?*), vector-isoscalar (?, ?), vector-isovector (?rrho), and scalar-isovector (?) sectors. Following recent experimental results, we consider in our calculations the extreme case where the ?- experiences such a strong repulsion that its influence in the nuclear structure of a neutron star is excluded at all. We study the effects of this exclusion on the phase transition of conventional exotic hadronic matter to hadronic matter containing a condensate of kaons and anti-kaons. As a novelty in the treatment of kaon and anti-kaon condensation in high density nuclear matter, we consider a Lagrangian formulation which describes, in addition to the interaction involving baryons and mesons and the contribution of kaons and anti-kaons in free propagation, the presence of many-body forces involving kaon, anti-kaon and meson fields. To implement the corresponding phase transition we considered the Gibbs conditions combined with the mean-field approximation, giving rise to a mixed phase of coexistence between baryon matter and the condensed of kaons and anti-kaons. Our investigation show that even with kaon condensation, the nuclear equation of state satisfies both the maximum mass and the allowed ranges of mass and radius of neutron stars.

  12. Floating chip mounting system driven by repulsive force of permanent magnets for multiple on-site SPR immunoassay measurements.

    PubMed

    Horiuchi, Tsutomu; Tobita, Tatsuya; Miura, Toru; Iwasaki, Yuzuru; Seyama, Michiko; Inoue, Suzuyo; Takahashi, Jun-ichi; Haga, Tsuneyuki; Tamechika, Emi

    2012-01-01

    We have developed a measurement chip installation/removal mechanism for a surface plasmon resonance (SPR) immunoassay analysis instrument designed for frequent testing, which requires a rapid and easy technique for changing chips. The key components of the mechanism are refractive index matching gel coated on the rear of the SPR chip and a float that presses the chip down. The refractive index matching gel made it possible to optically couple the chip and the prism of the SPR instrument easily via elastic deformation with no air bubbles. The float has an autonomous attitude control function that keeps the chip parallel in relation to the SPR instrument by employing the repulsive force of permanent magnets between the float and a float guide located in the SPR instrument. This function is realized by balancing the upward elastic force of the gel and the downward force of the float, which experiences a leveling force from the float guide. This system makes it possible to start an SPR measurement immediately after chip installation and to remove the chip immediately after the measurement with a simple and easy method that does not require any fine adjustment. Our sensor chip, which we installed using this mounting system, successfully performed an immunoassay measurement on a model antigen (spiked human-IgG) in a model real sample (non-homogenized milk) that included many kinds of interfering foreign substances without any sample pre-treatment. The ease of the chip installation/removal operation and simple measurement procedure are suitable for frequent on-site agricultural, environmental and medical testing. PMID:23202030

  13. Floating Chip Mounting System Driven by Repulsive Force of Permanent Magnets for Multiple On-Site SPR Immunoassay Measurements

    PubMed Central

    Horiuchi, Tsutomu; Tobita, Tatsuya; Miura, Toru; Iwasaki, Yuzuru; Seyama, Michiko; Inoue, Suzuyo; Takahashi, Jun-ichi; Haga, Tsuneyuki; Tamechika, Emi

    2012-01-01

    We have developed a measurement chip installation/removal mechanism for a surface plasmon resonance (SPR) immunoassay analysis instrument designed for frequent testing, which requires a rapid and easy technique for changing chips. The key components of the mechanism are refractive index matching gel coated on the rear of the SPR chip and a float that presses the chip down. The refractive index matching gel made it possible to optically couple the chip and the prism of the SPR instrument easily via elastic deformation with no air bubbles. The float has an autonomous attitude control function that keeps the chip parallel in relation to the SPR instrument by employing the repulsive force of permanent magnets between the float and a float guide located in the SPR instrument. This function is realized by balancing the upward elastic force of the gel and the downward force of the float, which experiences a leveling force from the float guide. This system makes it possible to start an SPR measurement immediately after chip installation and to remove the chip immediately after the measurement with a simple and easy method that does not require any fine adjustment. Our sensor chip, which we installed using this mounting system, successfully performed an immunoassay measurement on a model antigen (spiked human-IgG) in a model real sample (non-homogenized milk) that included many kinds of interfering foreign substances without any sample pre-treatment. The ease of the chip installation/removal operation and simple measurement procedure are suitable for frequent on-site agricultural, environmental and medical testing. PMID:23202030

  14. Electromagnetic Forces of High- T c Superconducting Coated Conductor Coils Subjected to Sinusoidal Traveling Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Li, Jing; Yen, Fei; Zheng, Shijun; Wang, Suyu

    2014-01-01

    In order to optimize the structure of high temperature superconducting coils for linear motor applications, three separate coils with different shapes made of Re-BCO coated conductor were studied: circular shaped single pancake, circular shaped double-pancake and racetrack shaped single-pancake. The thrust and vertical forces of the three coils above a conventional flat linear three-phases winding were investigated experimentally. With the aid of the experimentally obtained values, it was found that single-pancake coil in the shape of a racetrack was the best selection for a flat single-sided linear motor system. Studies were also made on the frequency characteristics of the vertical force of the racetrack shaped single-pancake coil.

  15. Quench protection design of a 9.4 T whole-body MRI superconducting magnet

    NASA Astrophysics Data System (ADS)

    Chen, Shunzhong; Li, Yi; Dai, Yinming; Lei, Yuanzhong; Yan, Luguang

    2014-02-01

    A 9.4 T MRI superconducting magnet with a 800 mm clear warm bore in diameter is designed and fabricated for bioscience research. The superconducting magnet consisting of five coaxial solenoid coils is fabricated with NbTi Wire-in-Channel (WIC) conductor where the ratios of copper to non-copper are from 5 to 10. The four compensation solenoid coils are with rectangular NbTi/Cu strand wires. The magnet will be operated in a relative low nominal current of 224.5 A with a high level of stored energy, about 138 MJ. A protection method with the cold diodes and resistors in series across the subdivided sections and active trigger heater to accelerate quench is adopted to avoid the damage of the magnet. In the paper, the quench simulation results of currents, voltages and hot-spot temperatures based on the protection scheme are analyzed in details.

  16. Methodologies to determine forces on bones and muscles of body segments during exercise, employing compact sensors suitable for use in crowded space vehicles

    NASA Technical Reports Server (NTRS)

    Figueroa, Fernando

    1995-01-01

    Work under this grant was carried out by the author and by a graduate research assistant. An instrumented bicycle ergometer was implemented focusing on the stated objective: to estimate the forces exerted by each muscle of the feet, calf, and thigh of an individual while bicycling. The sensors used were light and compact. These were probes to measure muscle EMG activity, miniature accelerometers, miniature load sensors, and small encoders to measure angular positions of the pedal. A methodology was developed and implemented to completely describe the kinematics of the limbs using data from the sensors. This work has been published as a Master's Thesis by the Graduate student supported by the grant. The instrumented ergometer along with the sensors and instrumentation were tested during a KC-135 Zero-Gravity flight in July, 1994. A complete description of the system and the tests performed have been published as a report submitted to NASA Johnson Space Center. The data collected during the KC-135 flight is currently being processed so that a kinematic description of the bicycling experiment will be soon determined. A methodology to estimate the muscle forces has been formulated based on previous work. The methodology involves the use of optimization concepts so that the individual muscle forces that represent variables in dynamic equations of motion may be estimated. Optimization of a criteria (goal) function such as minimization of energy will be used along with constraint equations defined by rigid body equations of motion. Use of optimization principles is necessary, because the equations of motion alone constitute an indeterminate system of equations with respect to the large amount of muscle forces which constitute the variables in these equations. The number of variables is reduced somewhat by using forces measured by the load cells installed on the pedal. These load cells measure pressure and shear forces on the foot. The author and his collaborators at NASA and at the University of Alabama, Tuscaloosa, are continuing the work of reducing the experimental data from the KC-135 flight, and the implementation of the optimization methods to estimate muscle forces. As soon as results from these efforts are available, they will be published in reputable journals. Results of this work will impact studies addressing bone density loss and development of countermeasures to minimize bone loss in zero gravity conditions. By analyzing muscle forces on Earth and in Space during exercise, scientists could eventually formulate new exercises and machines to help maintain bone density. On Earth, this work will impact studies concerning arthritis, and will provide the means to study possible exercise countermeasures to minimize arthritis problems.

  17. VOLUME 86, NUMBER 13 P H Y S I C A L R E V I E W L E T T E R S 26 MARCH 2001 Magnetic Resonance Force Microscopy Quantum Computer with Tellurium Donors in Silicon

    E-print Network

    Hammel, P. Chris

    Force Microscopy Quantum Computer with Tellurium Donors in Silicon G. P. Berman,1 G. D. Doolen,1 P. C a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities

  18. Role of the pressure force in the explosive dynamics of magnetic islands in double tearing modes

    SciTech Connect

    Janvier, M.; Li, J.; Kishimoto, Y.; Ishizawa, A.

    2011-10-15

    The evolution of magnetic islands at two resonant surfaces during the development of a global tearing mode is investigated via numerical simulations of a reduced set of magneto-hydrodynamic equations in slab plasmas. The explosive dynamics of the islands resulting in an interchange follows a Rutherford-like regime, also referred to as a weakly coupled double tearing mode. It is found that the latent mechanism of this dynamics is the reduction of the total pressure around the opposite X-point and the abrupt growth is associated with an imbalance of the pressure around the islands. Once this imbalance is well established, each plasmoid is pushed to the opposite X-point, increasing the drive for the field merging. A feedback loop then takes place as the reconnection itself decreases the strength of the magnetic field between the tearing layers, i.e., reinforces the pressure imbalance. This loop accelerates reconnection, thus leading to the observed explosive growth.

  19. Analysis of interaction effect of stress intensity factors for interface cracks and angular corners using singular integral equations of the body force method

    SciTech Connect

    Noda, Nao-Aki; Oda, Kazuhiro

    1995-11-01

    In this study, numerical solution of singular integral equations is discussed in the analysis of interface cracks and angular corners. The problems are formulated as a system of singular integral equations on the basis of the body force method. In the analysis of interface cracks, the unknown functions of the body force densities which satisfy the boundary conditions are expressed by the products of fundamental density functions and power series. In the problem of angular corners, two types of fundamental density functions are chosen to express the symmetric type stress singularity of 1/r{sup 1{minus}{lambda}1} and the skew-symmetric type stress singularity of 1/r{sup 1{minus}{lambda}2}; then the unknown functions are expressed as a linear combination of the fundamental density functions and power series. The accuracy of the present analysis is verified by comparing the present results with the results obtained by other researchers and examining the compliance with boundary conditions. The calculation shows that the present method gives rapidly converging numerical results for those problems as well as ordinary crack problems in homogeneous materials.

  20. Geometrical crossover in two-body systems in a magnetic field

    NASA Astrophysics Data System (ADS)

    Cerkaski, M.; Nazmitdinov, R. G.

    2013-08-01

    An algebraic approach is formulated in the harmonic approximation to describe a dynamics of two-fermion systems, confined in a three-dimensional axially symmetric parabolic potential, in an external magnetic field. The fermion interaction is considered in the form \\mathscr {U}_{M}( r )= \\alpha _{ M}\\,r^{-M} (?M > 0, M > 0). The formalism of a semisimple Lie group is applied to analyse symmetries of the considered system. Explicit algebraic expressions are derived in terms of the system's parameters and the magnetic field strength to trace the evolution of the equilibrium shape. It is predicted that the interplay of classical and quantum correlations may lead to a quantum shape transition from a lateral to a vertical localization of fermions in the confined system. The analytical results demonstrate a good agreement with the numerical results for two-electron quantum dots in the magnetic field, when classical correlations dominate in the dynamics.