Science.gov

Sample records for 3-d magnetic field

  1. Note: 3D printed spheroid for uniform magnetic field generation

    NASA Astrophysics Data System (ADS)

    Öztürk, Y.; Aktaş, B.

    2016-10-01

    This article is focused on a novel and practical production method for a uniform magnetic field generator. The method involves building of a surface coil template using a desktop 3D printer and winding of a conducting wire onto the structure using surface grooves as a guide. Groove pattern was based on the parametric spheroidal helical coil formula. The coil was driven by a current source and the magnetic field inside was measured using a Hall probe placed into the holes on the printed structure. The measurements are found to be in good agreement with our finite element analysis results and indicate a fairly uniform field inside.

  2. 3D print of polymer bonded rare-earth magnets, and 3D magnetic field scanning with an end-user 3D printer

    NASA Astrophysics Data System (ADS)

    Huber, C.; Abert, C.; Bruckner, F.; Groenefeld, M.; Muthsam, O.; Schuschnigg, S.; Sirak, K.; Thanhoffer, R.; Teliban, I.; Vogler, C.; Windl, R.; Suess, D.

    2016-10-01

    3D print is a recently developed technique, for single-unit production, and for structures that have been impossible to build previously. The current work presents a method to 3D print polymer bonded isotropic hard magnets with a low-cost, end-user 3D printer. Commercially available isotropic NdFeB powder inside a PA11 matrix is characterized, and prepared for the printing process. An example of a printed magnet with a complex shape that was designed to generate a specific stray field is presented, and compared with finite element simulation solving the macroscopic Maxwell equations. For magnetic characterization, and comparing 3D printed structures with injection molded parts, hysteresis measurements are performed. To measure the stray field outside the magnet, the printer is upgraded to a 3D magnetic flux density measurement system. To skip an elaborate adjusting of the sensor, a simulation is used to calibrate the angles, sensitivity, and the offset of the sensor. With this setup, a measurement resolution of 0.05 mm along the z-axes is achievable. The effectiveness of our calibration method is shown. With our setup, we are able to print polymer bonded magnetic systems with the freedom of having a specific complex shape with locally tailored magnetic properties. The 3D scanning setup is easy to mount, and with our calibration method we are able to get accurate measuring results of the stray field.

  3. 3-D magnetic field calculations for wiggglers using MAGNUS-3D

    SciTech Connect

    Pissanetzky, S.; Tompkins, P.

    1988-01-01

    The recent but steady trend toward increased magnetic and geometric complexity in the design of wigglers and undulators, of which tapered wigglers, hybrid structures, laced electromagnetic wigglers, magnetic cladding, twisters and magic structures are examples, has caused a need for reliable 3-D computer models and a better understanding of the behavior of magnetic systems in three dimensions. The capabilities of the MAGNUS-3D Group of Programs are ideally suited to solve this class of problems and provide insight into 3-D effects. MAGNUS-3D can solve any problem of Magnetostatics involving permanent magnets, linear or nonlinear ferromagnetic materials and electric conductors of any shape in space. The magnetic properties of permanent magnets are described by the complete nonlinear demagnetization curve as provided by the manufacturer, or, at the user's choice, by a simpler approximation involving the coercive force, the residual induction and the direction of magnetization. The ferromagnetic materials are described by a magnetization table and an accurate interpolation relation. An internal library with properties of common industrial steels is available. The conductors are independent of the mesh and are described in terms of conductor elements from an internal library.

  4. Analysis and measurement of the 3D magnetic field in a rotating magnetic field driven FRC

    NASA Astrophysics Data System (ADS)

    Velas, K. M.; Milroy, R. D.

    2012-10-01

    A translatable three-axis probe was installed on TCSU shortly before its shutdown. The probe has 90 windings that simultaneously measure Br, Bθ, and Bz at 30 radial positions. Positioning the probe at multiple axial positions and taking multiple repeatable shots allows for a full r-z map of the magnetic field. Probe measurements are used to calculate the end-shorting torque and the rotating magnetic field (RMF) torque. The torque applied to the plasma is the RMF torque reduced by the shorting torque. An estimate of the plasma resistivity is made based on the steady state balance between the applied torque and the resistive torque. The steady state data from applying a 10 kHz low pass filter used in conjunction with data at the RMF frequency yields a map of the full 3D rotating field structure. Data from even- and odd-parity experiments will be presented. The NIMROD code has been adapted to simulate the TCSU experiment using boundary conditions adjusted to match both even- and odd-parity experimental conditions. A comparison of the n=0 components of the calculated fields to the 3-axis probe measurements shows agreement in the magnetic field structure of the FRC as well as in the jet region.

  5. 3D magnetization currents, magnetization loop, and saturation field in superconducting rectangular prisms

    NASA Astrophysics Data System (ADS)

    Pardo, E.; Kapolka, M.

    2017-06-01

    Bulk superconductors are used in many applications and material characterization experiments, with the bulk shape of the rectangular prism being the most frequent. However, the magnetization currents are still mostly unknown for this kind of 3D shape, especially below the saturation magnetic field. Knowledge of the magnetization currents in this kind of sample is needed to interpret the measurements and the development of bulk materials for applications. This article presents a systematic analysis of the magnetization currents in square-based prisms of several thicknesses. We make this study by numerical modeling using a variational principle that enables a high number of degrees of freedom. We also compute the magnetization loops and saturation magnetic field, using a definition that is more relevant for thin prisms than previous ones. The article presents a practical analytical fit for any aspect ratio. For applied fields below the saturation field, the current paths are not rectangular, presenting 3D bending. The thickness-average results are consistent with previous modeling and measurements for thin films. The 3D bending of the current lines indicates that there could be flux-cutting effects in rectangular prisms. The component of the critical current density in the applied field direction may play a role, with the magnetization currents being different in a bulk and a stack of tapes.

  6. Statistical Flux Tube Properties of 3D Magnetic Carpet Fields

    NASA Astrophysics Data System (ADS)

    Close, R. M.; Parnell, C. E.; Mackay, D. H.; Priest, E. R.

    2003-02-01

    The quiet-Sun photosphere consists of numerous magnetic flux fragments of both polarities that evolve with granular and supergranular flow fields. These concentrations give rise to a web of intermingled magnetic flux tubes which characterise the coronal magnetic field. Here, the nature of these flux tubes is studied. The photosphere is taken to be the source plane and each photospheric fragment is represented by a series of point sources. By analysing the potential field produced by these sources, it is found that the distribution of flux tube lengths obtained by (i) integrating forward from positive sources and (ii) tracing back from negative sources is highly dependent on the total flux imbalance within the region of interest. It is established that the relation between the footpoint separation of a flux tube and its height cannot be assumed to be linear. Where there is a significant imbalance of flux within a region, it is found that fragments of the dominant polarity will have noticeably more connections, on average, than the minority polarity fragments. Despite this difference, the flux from a single fragment of either polarity is typically divided such that (i) 60-70% connects to one opposite-polarity fragment, (ii) 25-30% goes to a further 1 to 2 opposite-polarity fragments, and (iii) any remaining flux may connect to as many as another 50 or more other opposite-polarity fragments. This is true regardless of any flux imbalance within the region. It is found that fragments connect preferentially to their nearest neighbours, with, on average, around 60-70% of flux closing down within 10 Mm of a typical fragment. Only 50% of the flux in a quiet region extends higher than 2.5 Mm above the solar surface and 5-10% extends higher than 25 Mm. The fragments that contribute to the field above this height cover a range of sizes, with even the smallest of fragments contributing to the field at heights of over 50 Mm.

  7. ELM suppression in helium plasmas with 3D magnetic fields

    DOE PAGES

    Evans, T. E.; Loarte, A.; Orlov, D. M.; ...

    2017-06-21

    Experiments in DIII-D, using non-axisymmetric magnetic perturbation fields in high-purity low toroidal rotation, 4He plasmas have resulted in Type-I edge localized mode (ELM) suppression and mitigation. Suppression is obtained in plasmas with zero net input torque near the L–H power threshold using either electron cyclotron resonant heating (ECRH) or balanced co- and counter-I p neutral beam injection (NBI) resulting in conditions equivalent to those expected in ITER's non-active operating phase. In low-power ECRH H-modes, periods with uncontrolled density and impurity radiation excursions are prevented by applying n = 3 non-axisymmetric magnetic perturbation fields. ELM suppression results from a reduction andmore » an outward shift of the electron pressure gradient peak compared to that in the high-power ELMing phase. Here, the change in the electron pressure gradient peak is primarily due to a drop in the pedestal temperature rather than the pedestal density.« less

  8. ELM suppression in helium plasmas with 3D magnetic fields

    NASA Astrophysics Data System (ADS)

    Evans, T. E.; Loarte, A.; Orlov, D. M.; Grierson, B. A.; Knölker, M. M.; Lyons, B. C.; Cui, L.; Gohil, P.; Groebner, R. J.; Moyer, R. A.; Nazikian, R.; Osborne, T. H.; Unterberg, E. A.

    2017-08-01

    Experiments in DIII-D, using non-axisymmetric magnetic perturbation fields in high-purity low toroidal rotation, 4He plasmas have resulted in Type-I edge localized mode (ELM) suppression and mitigation. Suppression is obtained in plasmas with zero net input torque near the L-H power threshold using either electron cyclotron resonant heating (ECRH) or balanced co- and counter-I p neutral beam injection (NBI) resulting in conditions equivalent to those expected in ITER’s non-active operating phase. In low-power ECRH H-modes, periods with uncontrolled density and impurity radiation excursions are prevented by applying n  =  3 non-axisymmetric magnetic perturbation fields. ELM suppression results from a reduction and an outward shift of the electron pressure gradient peak compared to that in the high-power ELMing phase. The change in the electron pressure gradient peak is primarily due to a drop in the pedestal temperature rather than the pedestal density.

  9. Effects of 3D Toroidally Asymmetric Magnetic Field on Tokamak Magnetic Surfaces

    NASA Astrophysics Data System (ADS)

    Lao, L. L.

    2005-10-01

    The effects of 3D error magnetic field on magnetic surfaces are investigated using the DIII-D internal coils (I-Coils). Slowly rotating n=1 traveling waves at 5 Hz and various amplitudes were applied to systematically perturb the edge surfaces by programming the I-Coil currents. The vertical separatrix location difference between EFIT magnetic reconstructions that assumes toroidal symmetry and Thomson scattering Te measurements responds in phase to the applied perturbed field. The oscillation amplitudes increase with the strength of the applied field but are much smaller than those expected from the applied field alone. The results indicate that plasma response is important. Various plasma response models based on results from the MHD codes MARS and GATO are being developed and compared to the experimental observations. To more accurately evaluate the effects of magnetic measurement errors, a new form of the magnetic uncertainty matrix is also being implemented into EFIT. Details will be presented.

  10. 3-D explosions: a meditation on rotation (and magnetic fields)

    NASA Astrophysics Data System (ADS)

    Wheeler, J. C.

    This is the text of an introduction to a workshop on asymmetric explosions held in Austin in June, 2003. The great progress in supernova research over thirty-odd years is briefly reviewed. The context in which the meeting was called is then summarized. The theoretical success of the intrinsically multidimensional delayed detonation paradigm in explaining the nature of Type Ia supernovae coupled with new techniques of observations in the near IR and with spectropolarimetry promise great advances in understanding binary progenitors, the explosion physics, and the ever more accurate application to cosmology. Spectropolarimetry has also revealed the strongly asymmetric nature of core collapse and given valuable perspectives on the supernova - gamma-ray burst connection. The capability of the magneto-rotational instability to rapidly create strong toroidal magnetic fields in the core collapse ambiance is outlined. This physics may be the precursor to driving MHD jets that play a role in asymmetric supernovae. Welcome to the brave new world of three-dimensional explosions!

  11. 3D field harmonics

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J.

    1991-03-30

    We have developed an harmonic representation for the three dimensional field components within the windings of accelerator magnets. The form by which the field is presented is suitable for interfacing with other codes that make use of the 3D field components (particle tracking and stability). The field components can be calculated with high precision and reduced cup time at any location (r,{theta},z) inside the magnet bore. The same conductor geometry which is used to simulate line currents is also used in CAD with modifications more readily available. It is our hope that the format used here for magnetic fields can be used not only as a means of delivering fields but also as a way by which beam dynamics can suggest correction to the conductor geometry. 5 refs., 70 figs.

  12. On the magnetotransport of 3D systems in quantizing magnetic field

    NASA Astrophysics Data System (ADS)

    Cheremisin, M. V.

    2014-12-01

    The resistivity components of 3D electron gas placed in quantizing magnetic field are calculated taking into account the correction caused by combined action of the Peltier and Seebeck thermoelectric effects. The longitudinal, transverse and the Hall magnetoresistivities exhibit familiar 1/B-period oscillations being universal functions of magnetic field and temperature.

  13. Slip versus Field-Line Mapping in Describing 3D Reconnection of Coronal Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Titov, V. S.; Mikic, Z.; Torok, T.; Downs, C.; Lionello, R.; Linker, J.

    2015-12-01

    We demonstrate two techniques for describing the structure of the coronal magnetic field and its evolution due to reconnection in numerical 3D simulations of the solar corona and CMEs. These techniques employ two types of mapping of the boundary of the computational domain on itself. One of them is defined at a given time moment via connections of the magnetic field lines to their opposite endpoints. The other mapping, called slip mapping, relates field line endpoints at two different time moments and allows one to identify the slippage of plasma elements due to resistivity across field lines for a given time interval (Titov et al. 2009). The distortion of each of these mappings can be measured by using the so-called squashing factor Q (Titov 2007). The high-Q layers computed for the first and second mappings define, respectively, (quasi-)separatrix surfaces and reconnection fronts in evolving magnetic configurations. Analyzing these structural features, we are able to reveal topologically different domains and reconnected flux systems in the configurations, in particular, open, closed and disconnected magnetic flux tubes, as well as quantify the related magnetic flux transfer. Comparison with observations makes it possible also to relate these features to observed morphological elements such as flare loops and ribbons, and EUV dimmings. We illustrate these general techniques by applying them to particular data-driven MHD simulations. *Research supported by NASA's HSR and LWS Programs, and NSF/SHINE and NSF/FESD.

  14. 3D Kinetic Simulation of Plasma Jet Penetration in Magnetic Field

    NASA Astrophysics Data System (ADS)

    Galkin, Sergei A.; Bogatu, I. N.; Kim, J. S.

    2009-11-01

    A high velocity plasmoid penetration through a magnetic barrier is a problem of a great experimental and theoretical interest. Our LSP PIC code 3D fully kinetic numerical simulations of high density (10^16 cm-3) high velocity (30-140 km/sec) plasma jet/bullet, penetrating through the transversal magnetic field, demonstrate three different regimes: reflection by field, penetration by magnetic field expulsion and penetration by magnetic self-polarization. The behavior depends on plasma jet parameters and its composition: hydrogen, carbon (A=12) and C60-fullerene (A=720) plasmas were investigated. The 3D simulation of two plasmoid head-on injections along uniform magnetic field lines is analyzed. Mini rail plasma gun (accelerator) modeling is also presented and discussed.

  15. 3D Global Coronal Density, Temperature, and Vector Magnetic Field Derived from Coronal Observation.

    NASA Astrophysics Data System (ADS)

    Kramar, M.; Lin, H.; Airapetian, V.; Tomczyk, S.

    2016-12-01

    Solar coronal magnetic fields play a key role in the energetics and dynamics of coronal heating, solar flares, coronal mass ejections (CME), filament eruptions, and determine space weather processes. Therefore, one of the central problems of solar physics is to measure the magnetic fields in the solar corona.The main techniques that are currently used to deduce the global magnetic structure of the solar corona include potential field, nonlinear force-free field (NLFFF), and magnetohydrodynamic (MHD) models. These methods are based on boundary conditions of the solar photospheric magnetic field that are derived directly from photospheric magnetograms. All of these methods are essentially extrapolation methods based on inner boundary conditions taken at the photosphere. However, the magnetic field at the photosphere and lower chromosphere is far from potential or force-free, because of the dominance of the plasma pressure there.We will present 3D reconstruction of the global coronal electron density, temperature during periods of minimum and maximum of solar activity cycle and derived from coronal STEREO/COR1 and EUVI observations. We find that the magnetic field configuration during maximum of solar activity (CR 2131) has a tendency to become radially open at heliocentric distances below 2.5 Rsun while during the solar minimum (CR 2066) they tend to open at higher distances.Moreover, the obtained 3D density and temperature has been used as additional input for recently developed vector tomography method to reconstruct the coronal vector magnetic field based on polarimetric observation of magnetically sensitive Fe XIII ion emission by Coronal Magnetic Polarimeter (CoMP). We validated the vector tomography inverted coronal magnetic fields with those constructed by MHD simulation based on observed photospheric magnetic fields as well as with the STEREO/EUVI 195 image and with the global 3D coronal electron density structure obtained by tomography based on STEREO/COR1

  16. DIRECT DETECTION OF THE HELICAL MAGNETIC FIELD GEOMETRY FROM 3D RECONSTRUCTION OF PROMINENCE KNOT TRAJECTORIES

    SciTech Connect

    Zapiór, Maciej; Martinez-Gómez, David

    2016-02-01

    Based on the data collected by the Vacuum Tower Telescope located in the Teide Observatory in the Canary Islands, we analyzed the three-dimensional (3D) motion of so-called knots in a solar prominence of 2014 June 9. Trajectories of seven knots were reconstructed, giving information of the 3D geometry of the magnetic field. Helical motion was detected. From the equipartition principle, we estimated the lower limit of the magnetic field in the prominence to ≈1–3 G and from the Ampère’s law the lower limit of the electric current to ≈1.2 × 10{sup 9} A.

  17. Fast 3D Spatial EPR Imaging Using Spiral Magnetic Field Gradient

    PubMed Central

    Deng, Yuanmu; Petryakov, Sergy; He, Guanglong; Kesselring, Eric; Kuppusamy, Periannan; Zweier, Jay L.

    2007-01-01

    Electron paramagnetic resonance imaging (EPRI) provides direct detection and mapping of free radicals. The continuous wave (CW) EPRI technique, in particular, has been widely used in a variety of applications in the fields of biology and medicine due to its high sensitivity and applicability to a wide range of free radicals and paramagnetic species. However, the technique requires long image acquisition periods, and this limits its use for many in vivo applications where relatively rapid changes occur in the magnitude and distribution of spins. Therefore, there has been a great need to develop fast EPRI techniques. We report the development of a fast 3D CW EPRI technique using spiral magnetic field gradient. By spiraling the magnetic field gradient and stepping the main magnetic field, this approach acquires a 3D image in one sweep of the main magnetic field, enabling significant reduction of the imaging time. A direct one-stage 3D image reconstruction algorithm, modified for reconstruction of the EPR images from the projections acquired with the spiral magnetic field gradient, was used. We demonstrated using a home-built L-band EPR system that the spiral magnetic field gradient technique enabled a 4 to 7-fold accelerated acquisition of projections. This technique has great potential for in vivo studies of free radicals and their metabolism. PMID:17267252

  18. Topology optimized and 3D printed polymer-bonded permanent magnets for a predefined external field

    NASA Astrophysics Data System (ADS)

    Huber, C.; Abert, C.; Bruckner, F.; Pfaff, C.; Kriwet, J.; Groenefeld, M.; Teliban, I.; Vogler, C.; Suess, D.

    2017-08-01

    Topology optimization offers great opportunities to design permanent magnetic systems that have specific external field characteristics. Additive manufacturing of polymer-bonded magnets with an end-user 3D printer can be used to manufacture permanent magnets with structures that had been difficult or impossible to manufacture previously. This work combines these two powerful methods to design and manufacture permanent magnetic systems with specific properties. The topology optimization framework is simple, fast, and accurate. It can also be used for the reverse engineering of permanent magnets in order to find the topology from field measurements. Furthermore, a magnetic system that generates a linear external field above the magnet is presented. With a volume constraint, the amount of magnetic material can be minimized without losing performance. Simulations and measurements of the printed systems show very good agreement.

  19. Anisotropic heat transport in integrable and chaotic 3-D magnetic fields

    SciTech Connect

    Del-Castillo-Negrete, Diego B; Blazevski, D.; Chacon, Luis

    2012-01-01

    A study of anisotropic heat transport in 3-D chaotic magnetic fields is presented. The approach is based on the recently proposed Lagrangian-Green s function (LG) method in Ref. [1] that allows an efficient and accurate integration of the parallel transport equation applicable to general magnetic fields with local or non-local parallel flux closures. We focus on reversed shear magnetic field configurations known to exhibit separatrix reconnection and shearless transport barriers. The role of reconnection and magnetic field line chaos on temperature transport is studied. Numerical results are presented on the anomalous relaxation of radial temperature gradients in the presence of shearless Cantori partial barri- ers. Also, numerical evidence of non-local effective radial temperature transport in chaotic fields is presented. Going beyond purely parallel transport, the LG method is generalized to include finite perpendicular diffusivity, and the problem of temperature flattening inside a magnetic island is studied.

  20. Synthesis of 3D Model of a Magnetic Field-Influenced Body from a Single Image

    NASA Technical Reports Server (NTRS)

    Wang, Cuilan; Newman, Timothy; Gallagher, Dennis

    2006-01-01

    A method for recovery of a 3D model of a cloud-like structure that is in motion and deforming but approximately governed by magnetic field properties is described. The method allows recovery of the model from a single intensity image in which the structure's silhouette can be observed. The method exploits envelope theory and a magnetic field model. Given one intensity image and the segmented silhouette in the image, the method proceeds without human intervention to produce the 3D model. In addition to allowing 3D model synthesis, the method's capability to yield a very compact description offers further utility. Application of the method to several real-world images is demonstrated.

  1. Synthesis of 3D Model of a Magnetic Field-Influenced Body from a Single Image

    NASA Technical Reports Server (NTRS)

    Wang, Cuilan; Newman, Timothy; Gallagher, Dennis

    2006-01-01

    A method for recovery of a 3D model of a cloud-like structure that is in motion and deforming but approximately governed by magnetic field properties is described. The method allows recovery of the model from a single intensity image in which the structure's silhouette can be observed. The method exploits envelope theory and a magnetic field model. Given one intensity image and the segmented silhouette in the image, the method proceeds without human intervention to produce the 3D model. In addition to allowing 3D model synthesis, the method's capability to yield a very compact description offers further utility. Application of the method to several real-world images is demonstrated.

  2. Casting the Coronal Magnetic Field Reconstruction Tools in 3D Using the MHD Bifrost Model

    NASA Astrophysics Data System (ADS)

    Fleishman, Gregory D.; Anfinogentov, Sergey; Loukitcheva, Maria; Mysh’yakov, Ivan; Stupishin, Alexey

    2017-04-01

    Quantifying the coronal magnetic field remains a central problem in solar physics. Nowadays, the coronal magnetic field is often modeled using nonlinear force-free field (NLFFF) reconstructions, whose accuracy has not yet been comprehensively assessed. Here we perform a detailed casting of the NLFFF reconstruction tools, such as π-disambiguation, photospheric field preprocessing, and volume reconstruction methods, using a 3D snapshot of the publicly available full-fledged radiative MHD model. Specifically, from the MHD model, we know the magnetic field vector in the entire 3D domain, which enables us to perform a “voxel-by-voxel” comparison of the restored and the true magnetic fields in the 3D model volume. Our tests show that the available π-disambiguation methods often fail in the quiet-Sun areas dominated by small-scale magnetic elements, while they work well in the active region (AR) photosphere and (even better) chromosphere. The preprocessing of the photospheric magnetic field, although it does produce a more force-free boundary condition, also results in some effective “elevation” of the magnetic field components. This “elevation” height is different for the longitudinal and transverse components, which results in a systematic error in absolute heights in the reconstructed magnetic data cube. The extrapolations performed starting from the actual AR photospheric magnetogram are free from this systematic error, while other metrics are comparable with those for extrapolations from the preprocessed magnetograms. This finding favors the use of extrapolations from the original photospheric magnetogram without preprocessing. Our tests further suggest that extrapolations from a force-free chromospheric boundary produce measurably better results than those from a photospheric boundary.

  3. 3D-xy critical properties of YBa2Cu4O8 and magnetic-field-induced 3D to 1D crossover

    NASA Astrophysics Data System (ADS)

    Weyeneth, S.; Schneider, T.; Bukowski, Z.; Karpinski, J.; Keller, H.

    2008-08-01

    We present reversible magnetization data of a YBa2Cu4O8 single crystal and analyze the evidence for 3D-xy critical behavior and a magnetic-field-induced 3D to 1D crossover. Remarkable consistency with these phenomena is observed in agreement with a magnetic-field-induced finite size effect, whereupon the correlation length transverse to the applied magnetic field cannot grow beyond the limiting magnetic length scale LH = (Φ0/(aH))1/2. By applying the appropriate scaling form we obtain the zero-field critical temperature, the 3D to 1D crossover, the vortex melting line and the universal ratios of the related scaling variables. Accordingly there is no continuous phase transition in the (H,T) plane along the Hc2 lines as predicted by the mean-field treatment.

  4. 2D and 3D fault basis for fuel cell diagnosis by external magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Ifrek, Lyes; Cauffet, Gilles; Chadebec, Olivier; Bultel, Yann; Rosini, Sébastien; Rouveyre, Luc

    2017-07-01

    An original approach used for the identification of faults in fuel cell stacks is presented. It is based on the 3D reconstruction of the current density from external magnetic field measurements which is an ill-posed magnetostatic linear inverse problem. A suitable and original current density and magnetic field basis are proposed in order to define both local and global faults on a fuel cell stack. The inverse problem is regularized by truncated singular value decomposition (SVD) to ensure the uniqueness of the solution. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

  5. Exact spectra of strong coulomb correlations of 3-D 2-e harmonic dots in magnetic field

    NASA Astrophysics Data System (ADS)

    Aggarwal, Priyanka; Sharma, Shivalika; Kaur, Harsimran; Singh, Sunny; Hazra, Ram Kuntal

    2017-01-01

    Applications of 3-D 2-e systems have proliferated very fast due to technological advancements in wide range of phenomena from atomic landscape to mesoscopic scale. The unusual properties of atomic/mesoscopic systems are the results of interplaying charge interactions among different bound states. The non-trivial e-e correlations in electrically and/or magnetically confined systems improvise wealth of intriguing challenges at fundamental level due to lack of exact solution of Schrödinger equations. For the first time, a novel methodology of exactly finite summed coulomb correlations invented by us is so handy that even usual programmable calculator can be used to examine the electronic structures of 3-D 2-e harmonic dots in perpendicular magnetic field (symmetric gauge). Statistics of electronic levels, heat capacity measurements and magnetization (T∼1 K) are also investigated in brief to probe the degree of disorderedness.

  6. Effect of geometry and magnetic field on the coherence time of 3D transmons

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Gao, Y.; Axline, C.; Brecht, T.; Frunzio, L.; Schoelkopf, R. J.

    2014-03-01

    The three-dimensional circuit QED architecture has enabled nearly two orders of magnitude of improvement in the coherence time of transmon qubits over the last couple of years. Continued improvement moving forward relies on a better understanding of the factors limiting coherence of the current generation of transmons. Here we present a systematic study of the energy relaxation time (T1) of transmon qubits coupled to 3D waveguide cavities with various designs of capacitor geometries and its dependence on temperature and external magnetic field. Our measurement and analysis indicate both surface dielectric loss and quasiparticle loss play important roles in limiting T1 of 3D transmons. More interestingly, with certain geometric design we found qubit T1 can be improved by cooling in a small magnetic field. These results suggest more complex interplays of loss mechanisms than was previously appreciated and may have important implications for future design of transmons. Work supported by IARPA.

  7. 3-D Modeling of Magnetic Fields for the Lithium Tokamak eXperiment

    NASA Astrophysics Data System (ADS)

    Logan, N.; Berzak, L.; Kaita, R.; Majeski, R.; Menard, J.; Zakharov, L.

    2010-11-01

    The Lithium Tokamak eXperiment (LTX) is designed to investigate low-recycling operating regimes by surrounding 85% of the last closed flux surface with liquid lithium evaporated onto a copper and stainless steel shell conformal to the plasma. Fields generated by currents in this conducting shell have significant effects on magnetic configurations. To understand these effects, the commercially available code Aether [http://www.fieldp.com] is used to simulate time varying magnetic fields in a 3-D model of LTX. The model is built using LTX CAD files and divided into a regular mesh for computing the evolution of coupled electromagnetic vector quantities through time and space. Applicable boundary conditions and symmetries are analyzed. Comparisons with measured data, results from a 2-D code, and results from a 3-D code designed specifically for LTX demonstrate the possible benefits and limitations of using this commercial code.

  8. An approach to 3D magnetic field calculation using numerical and differential algebra methods

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J.; Brady, V.O.

    1992-07-17

    Motivated by the need for new means for specification and determination of 3D fields that are produced by electromagnetic lens elements in the region interior to coil windings and seeking to obtain techniques that will be convenient for accurate conductor placement and dynamical study of particle motion, we have conveniently gene the representation of a 2D magnetic field to 3D. We have shown that the 3 dimensioal magnetic field components of a multipole magnet in the curl-fire divergence-fire region near the axis r=0 can be derived from one dimensional functions A{sub n}(z) and their derivatives (part 1). In the region interior to coil windings of accelerator magnets the three spatial components of magnet fields can be expressed in terms of harmonic components'' proportional to functions sin (n{theta}) or cos (n{theta}) of the azimuthal angle. The r,z dependence of any such component can then be expressed in terms of powers of r times functions A{sub n}(z) and their derivatives. For twodimensional configurations B{sub z} of course is identically zero, the derivatives of A{sub n}(z) vanish, and the harmonic components of the transverse field then acquire a simple proportionality B{sub r,n} {proportional to} r{sup n-1} sin (n{theta}),B{sub {theta},n} {proportional to} r{sup n-1} cos (n{theta}), whereas in a 3-D configuration the more complex nature of the field gives rise to additional so-called psuedomultipole'' components as judged by additional powers of r required in the development of the field. Computation of the 3-D magnetic field arising at a sequence of field points, as a direct result of a specified current configuration or coil geometry, can be calculated explicitly through use of the Biot-Savart law and from such data the coefficients can then be derived for a general development of the type indicated above. We indicate, discuss, and illustrate two means by which this development may be performed.

  9. 3D Design, Contruction, and Field Analysis of CIS Main Dipole Magnets

    NASA Astrophysics Data System (ADS)

    Berg, G. P. A.; Fox, W.; Friesel, D. L.; Rinckel, T.

    1997-05-01

    The lattice for CIS ( Cooler Injection Synchroton ) requires four laminated 90^circ main dipole magnets with bending radius ρ = 1.273 m, EFL = 2 m, and an edge angle of 12^circ. Optimum Cooler injection and injection in the planned 15 GeV LISS ring requires operation up to about 1.75 T. Initial operation of 1 Hz, with later upgrade to 5 Hz is planned. We will present 2D and 3D field calculations used to optimize the shape of laminations and endpacks of the magnet. Endpacks are designed to determine edge angle and to compensate hexapole components, in particular above 1.4 T where saturation becomes significant. The large dipole curvature required a new type of dipole construction. Each magnet consists of wedge shaped blocks fabricated from stamped lamination of cold rolled low carbon iron. B-stage (dry) epopy was used for bonding and insulation. The end blocks are machined to include the calculated 3D shape of the endpacks. All four magnets were mapped in the field range from 0.3 T - 1.8 T. Comparison of calculations and data in terms of B(I) curves, EFL, edge angle, and hexapole component as function of field excitation will be presented. The constructed magnets are well within expected specifications.

  10. 3D position estimation using a single coil and two magnetic field sensors.

    PubMed

    Tadayon, P; Staude, G; Felderhoff, T

    2015-01-01

    This paper presents an algorithm which enables the estimation of relative 3D position of a sensor module with two magnetic sensors with respect to a magnetic field source using a single transmitting coil. Starting with the description of the ambiguity problem caused by using a single coil, a system concept comprising two sensors having a fixed spatial relation to each other is introduced which enables the unique determination of the sensors' position in 3D space. For this purpose, an iterative two-step algorithm is presented: In a first step, the data of one sensor is used to limit the number of possible position solutions. In a second step, the spatial relation between the sensors is used to determine the correct sensor position.

  11. Analysis of the 3D magnetic field and its errors for undulators with iron poles

    SciTech Connect

    Ingold, G.; Bahrdt, J.; Gaupp, A.

    1995-12-31

    The attainable field strength and field quality, such as the optical phase error, the electron beam displacement within the undulator and higher order multipoles of the magnetic field, are discussed. These issues are critical to the design and construction of short period undulators for use in short wavelength FEL or for operation in third generation light sources. We discuss two approaches: (i) For superferric undulators the construction of a full length device would rely on the optimum sorting of precision machined undulator segments. Magnetic data on segments with 20 periods (period length 8.80mm) will be presented. (ii) For hybrid undulators the sorting has to be done on individual poles and magnets. For this approach typical error sources such as machining tolerances, magnetization errors of the permanent magnet material and assembly errors are modeled in 3D and compared to induced errors on an existing hybrid undulator segment. In case of undulators having a full length of hundred periods at least five times as many individual parts have to be characterized. This should be done automatically where both the mechanical and magnetic data before and after the assembly of the magnetic structure are recorded in one step. A CNC programmable measuring device suitable for this task will shortly be presented.

  12. Heat Transfer Affected by Transverse Magnetic Field using 3D Modeling of Arc Plasma

    NASA Astrophysics Data System (ADS)

    Maeda, Yoshifumi; Tanaka, Tatsuro; Yamamoto, Shinji; Iwao, Toru

    2016-10-01

    Gas shielded metal arc welding is used to join the various metal because this is the high quality joining technology. Thus, this welding is used for a welding of large buildings such as bridges and LNG tanks. However, the welding defect caused by the heat transfer decrement may occur with increasing the wind velocity. This is because that the convection loss increases because the arc deflects to leeward side with increasing the wind velocity. In order to prevent from the arc deflection, it is used that the transverse magnetic field is applied to the arc. However, the arc deflection occurs with increasing the transverse magnetic field excessively. The energy balance of the arc is changed with increasing the convection loss caused by the arc deflection, and the heat transfer to the anode decreases. Therefore, the analysis including the arc and anode is necessary to elucidate the heat transfer to the anode. In this paper, the heat transfer affected by the transverse magnetic field using 3D modeling of the arc plasma is elucidated. The heat transfer to the anode is calculated by using the EMTF(electromagnetic thermal fluid) simulation with increasing the transverse magnetic field. As a result, the heat transfer decreased with increasing the transverse magnetic field.

  13. Study of the internal magnetic field of Mercury through 3D hybrid simulations

    NASA Astrophysics Data System (ADS)

    Leclercq, Ludivine; Marcel Chanteur, Gerard; Modolo, Ronan; Leblanc, Francois; Schmidt, Carl; Langlais, Benoît; Thebault, Erwan

    2016-10-01

    In 1974, Mariner 10 discovered the intrinsic magnetic field of Mercury which interacts with the solar wind, leading to the formation of a magnetosphere. In spite of the recent MESSENGER observations, this magnetosphere remains quite unknown, especially in the Southern hemisphere. In order to improve our understanding of the Hermean magnetosphere, and to prepare the Bepi-Colombo mission (ESA/JAXA), we simulated the magnetized environment of Mercury using the model named LatHyS (LATMOS Hybrid Simulation). LatHyS is a 3D parallel multi-species hybrid code which has been applied to Mars, Titan and Ganymede, which has recently be improved by the implementation of a multi-grid method allowing to refine the spatial resolution near the planetary object (40 km in the case of Mercury). In order to investigate the Hermean environment, several hybrid simulations have been performed considering different internal field models, and results are compared with MESSENGER observations.

  14. Effects of 2D and 3D Error Fields on the SAS Divertor Magnetic Topology

    NASA Astrophysics Data System (ADS)

    Trevisan, G. L.; Lao, L. L.; Strait, E. J.; Guo, H. Y.; Wu, W.; Evans, T. E.

    2016-10-01

    The successful design of plasma-facing components in fusion experiments is of paramount importance in both the operation of future reactors and in the modification of operating machines. Indeed, the Small Angle Slot (SAS) divertor concept, proposed for application on the DIII-D experiment, combines a small incident angle at the plasma strike point with a progressively opening slot, so as to better control heat flux and erosion in high-performance tokamak plasmas. Uncertainty quantification of the error fields expected around the striking point provides additional useful information in both the design and the modeling phases of the new divertor, in part due to the particular geometric requirement of the striking flux surfaces. The presented work involves both 2D and 3D magnetic error field analysis on the SAS strike point carried out using the EFIT code for 2D equilibrium reconstruction, V3POST for vacuum 3D computations and the OMFIT integrated modeling framework for data analysis. An uncertainty in the magnetic probes' signals is found to propagate non-linearly as an uncertainty in the striking point and angle, which can be quantified through statistical analysis to yield robust estimates. Work supported by contracts DE-FG02-95ER54309 and DE-FC02-04ER54698.

  15. Magnetic field induced controllable self-assembly of maghemite nanocrystals: From 3D arrays to 1D nanochains

    NASA Astrophysics Data System (ADS)

    Tang, Yan; Chen, Qianwang; Chen, Rongsheng

    2015-08-01

    A hydrothermal process has been used to synthesize walnut-like maghemite superstructures which can be further self-assembled in a controllable manner into ordered three-dimensional (3D) architectures and one-dimensional (1D) nanochains in the presence of different external magnetic field. The assembly behavior of the maghemite nanoparticles isclosely related to the van der Waals interactions and external-field-induced magnetic dipole interactions. The magnetic properties of these nanostructures are also investigated.

  16. Simulation of bootstrap current in 2D and 3D ideal magnetic fields in tokamaks

    NASA Astrophysics Data System (ADS)

    Raghunathan, M.; Graves, J. P.; Cooper, W. A.; Pedro, M.; Sauter, O.

    2016-09-01

    We aim to simulate the bootstrap current for a MAST-like spherical tokamak using two approaches for magnetic equilibria including externally caused 3D effects such as resonant magnetic perturbations (RMPs), the effect of toroidal ripple, and intrinsic 3D effects such as non-resonant internal kink modes. The first approach relies on known neoclassical coefficients in ideal MHD equilibria, using the Sauter (Sauter et al 1999 Phys. Plasmas 6 2834) expression valid for all collisionalities in axisymmetry, and the second approach being the quasi-analytic Shaing-Callen (Shaing and Callen 1983 Phys. Fluids 26 3315) model in the collisionless regime for 3D. Using the ideal free-boundary magnetohydrodynamic code VMEC, we compute the flux-surface averaged bootstrap current density, with the Sauter and Shaing-Callen expressions for 2D and 3D ideal MHD equilibria including an edge pressure barrier with the application of resonant magnetic perturbations, and equilibria possessing a saturated non-resonant 1/1 internal kink mode with a weak internal pressure barrier. We compare the applicability of the self-consistent iterative model on the 3D applications and discuss the limitations and advantages of each bootstrap current model for each type of equilibrium.

  17. 3-D residual eddy current field characterisation: applied to diffusion weighted magnetic resonance imaging.

    PubMed

    O'Brien, Kieran; Daducci, Alessandro; Kickler, Nils; Lazeyras, Francois; Gruetter, Rolf; Feiweier, Thorsten; Krueger, Gunnar

    2013-08-01

    Clinical use of the Stejskal-Tanner diffusion weighted images is hampered by the geometric distortions that result from the large residual 3-D eddy current field induced. In this work, we aimed to predict, using linear response theory, the residual 3-D eddy current field required for geometric distortion correction based on phantom eddy current field measurements. The predicted 3-D eddy current field induced by the diffusion-weighting gradients was able to reduce the root mean square error of the residual eddy current field to ~1 Hz. The model's performance was tested on diffusion weighted images of four normal volunteers, following distortion correction, the quality of the Stejskal-Tanner diffusion-weighted images was found to have comparable quality to image registration based corrections (FSL) at low b-values. Unlike registration techniques the correction was not hindered by low SNR at high b-values, and results in improved image quality relative to FSL. Characterization of the 3-D eddy current field with linear response theory enables the prediction of the 3-D eddy current field required to correct eddy current induced geometric distortions for a wide range of clinical and high b-value protocols.

  18. Properties of the prominence magnetic field and plasma distributions as obtained from 3D whole-prominence fine structure modeling

    NASA Astrophysics Data System (ADS)

    Gunár, S.; Mackay, D. H.

    2016-07-01

    Aims: We analyze distributions of the magnetic field strength and prominence plasma (temperature, pressure, plasma β, and mass) using the 3D whole-prominence fine structure model. Methods: The model combines a 3D magnetic field configuration of an entire prominence, obtained from non-linear force-free field simulations, with a detailed semi-empirically derived description of the prominence plasma. The plasma is located in magnetic dips in hydrostatic equilibrium and is distributed along multiple fine structures within the 3D magnetic model. Results: We show that in the modeled prominence, the variations of the magnetic field strength and its orientation are insignificant on scales comparable to the smallest dimensions of the observed prominence fine structures. We also show the ability of the 3D whole-prominence fine structure model to reveal the distribution of the prominence plasma with respect to its temperature within the prominence volume. This provides new insights into the composition of the prominence-corona transition region. We further demonstrate that the values of the plasma β are small throughout the majority of the modeled prominences when realistic photospheric magnetic flux distributions and prominence plasma parameters are assumed. While this is generally true, we also find that in the region with the deepest magnetic dips, the plasma β may increase towards unity. Finally, we show that the mass of the modeled prominence plasma is in good agreement with the mass of observed non-eruptive prominences.

  19. Finite Element Treatment of Vortex States in 3D Cubic Superconductors in a Tilted Magnetic Field

    NASA Astrophysics Data System (ADS)

    Peng, Lin; Cai, Chuanbing

    2017-03-01

    The time-dependent Ginzburg-Landau equations have been solved numerically by a finite element analysis for superconducting samples with a cubic shape in a tilted magnetic field. We obtain different vortex patterns as a function of the external magnetic field. With a magnetic field not parallel to the x- or y-axis, the vortices attempt to change their orientation accordingly. Our analysis of the corresponding changes in the magnetic response in different directions can provide information not only about vorticity but also about the three-dimensional vortex arrangement, even about the very subtle changes for the superconducting samples with a cubic shape in a tilted magnetic field.

  20. ORBXYZ: a 3D single-particle orbit code for following charged-particle trajectories in equilibrium magnetic fields

    SciTech Connect

    Anderson, D.V.; Cohen, R.H.; Ferguson, J.R.; Johnston, B.M.; Sharp, C.B.; Willmann, P.A.

    1981-06-30

    The single particle orbit code, TIBRO, has been modified extensively to improve the interpolation methods used and to allow use of vector potential fields in the simulation of charged particle orbits on a 3D domain. A 3D cubic B-spline algorithm is used to generate spline coefficients used in the interpolation. Smooth and accurate field representations are obtained. When vector potential fields are used, the 3D cubic spline interpolation formula analytically generates the magnetic field used to push the particles. This field has del.BETA = 0 to computer roundoff. When magnetic induction is used the interpolation allows del.BETA does not equal 0, which can lead to significant nonphysical results. Presently the code assumes quadrupole symmetry, but this is not an essential feature of the code and could be easily removed for other applications. Many details pertaining to this code are given on microfiche accompanying this report.

  1. ORBXYZ: A 3D single-particle orbit code for following charged particle trajectories in equilibrium magnetic fields

    NASA Astrophysics Data System (ADS)

    Anderson, D. V.; Cohen, R. H.; Ferguson, J. R.; Johnston, B. M.; Sharp, C. B.; Willmann, P. A.

    1981-06-01

    The single particle orbit code, TIBRO, was modified extensively to improve the interpolation methods used and to allow use of vector potential fields in the simulation of charged particle orbits on a 3D domain. A 3D cubic B-spline algorithm is used to generate spline coefficients used in the interpolation. Smooth and accurate field representations are obtained. When vector potential fields are used, the 3D cubic spline interpolation formula analytically generates the magnetic field used to push the particles. This field has del.BETA = 0 to computer roundoff. When magnetic induction is used the interpolation allows del.BETA does not equal 0, which can lead to significant nonphysical results. Presently the code assumes quadrupole symmetry, but this is not an essential feature of the code and could be easily removed for other applications.

  2. 3D numerical simulations of negative hydrogen ion extraction using realistic plasma parameters, geometry of the extraction aperture and full 3D magnetic field map

    NASA Astrophysics Data System (ADS)

    Mochalskyy, S.; Wünderlich, D.; Ruf, B.; Franzen, P.; Fantz, U.; Minea, T.

    2014-02-01

    Decreasing the co-extracted electron current while simultaneously keeping negative ion (NI) current sufficiently high is a crucial issue on the development plasma source system for ITER Neutral Beam Injector. To support finding the best extraction conditions the 3D Particle-in-Cell Monte Carlo Collision electrostatic code ONIX (Orsay Negative Ion eXtraction) has been developed. Close collaboration with experiments and other numerical models allows performing realistic simulations with relevant input parameters: plasma properties, geometry of the extraction aperture, full 3D magnetic field map, etc. For the first time ONIX has been benchmarked with commercial positive ions tracing code KOBRA3D. A very good agreement in terms of the meniscus position and depth has been found. Simulation of NI extraction with different e/NI ratio in bulk plasma shows high relevance of the direct negative ion extraction from the surface produced NI in order to obtain extracted NI current as in the experimental results from BATMAN testbed.

  3. Testing the Validity of the Neoclassical Toroidal Viscosity Model of Torque due to 3D Non-Resonant Magnetic Fields

    NASA Astrophysics Data System (ADS)

    McCubbin, A. J.; Smith, S. P.; Ferraro, N. M.; Callen, J. D.; Meneghini, O.

    2012-10-01

    Understanding the torque applied by resonant and non-resonant magnetic perturbations and its effect on rotation is essential to predict confinement and stability in burning plasmas. Non-axisymmetric 3D fields produced in the DIII-D tokamak apply a torque to the plasma, which can be evaluated through its effect on the plasma rotation. One explanation for this torque is Neoclassical Toroidal Viscosity (NTV) acting through non-resonant field components [1]. We have developed a software framework in which magnetic perturbations calculated by the state of the art two fluid MHD code M3D-C1 can be used in NTV calculations. For discharges with applied external magnetic fields in DIII-D, the experimentally determined torques will be analyzed and compared with NTV models.[4pt] [1] J.D. Callen, Nucl. Fusion 51, 094026 (2011).

  4. 3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.

    2006-01-01

    Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.

  5. 3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.

    2006-01-01

    Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.

  6. 3D magnetic field configuration of small-scale reconnection events in the solar plasma atmosphere

    NASA Astrophysics Data System (ADS)

    Shimizu, T.

    2015-10-01

    The outer solar atmosphere, i.e., the corona and the chromosphere, is replete with small energy-release events, which are accompanied by transient brightening and jet-like ejections. These events are considered to be magnetic reconnection events in the solar plasma, and their dynamics have been studied using recent advanced observations from the Hinode spacecraft and other observatories in space and on the ground. These events occur at different locations in the solar atmosphere and vary in their morphology and amount of the released energy. The magnetic field configurations of these reconnection events are inferred based on observations of magnetic fields at the photospheric level. Observations suggest that these magnetic configurations can be classified into two groups. In the first group, two anti-parallel magnetic fields reconnect to each other, yielding a 2D emerging flux configuration. In the second group, helical or twisted magnetic flux tubes are parallel or at a relative angle to each other. Reconnection can occur only between anti-parallel components of the magnetic flux tubes and may be referred to as component reconnection. The latter configuration type may be more important for the larger class of small-scale reconnection events. The two types of magnetic configurations can be compared to counter-helicity and co-helicity configurations, respectively, in laboratory plasma collision experiments.

  7. 3D magnetic field configuration of small-scale reconnection events in the solar plasma atmosphere

    SciTech Connect

    Shimizu, T.

    2015-10-15

    The outer solar atmosphere, i.e., the corona and the chromosphere, is replete with small energy-release events, which are accompanied by transient brightening and jet-like ejections. These events are considered to be magnetic reconnection events in the solar plasma, and their dynamics have been studied using recent advanced observations from the Hinode spacecraft and other observatories in space and on the ground. These events occur at different locations in the solar atmosphere and vary in their morphology and amount of the released energy. The magnetic field configurations of these reconnection events are inferred based on observations of magnetic fields at the photospheric level. Observations suggest that these magnetic configurations can be classified into two groups. In the first group, two anti-parallel magnetic fields reconnect to each other, yielding a 2D emerging flux configuration. In the second group, helical or twisted magnetic flux tubes are parallel or at a relative angle to each other. Reconnection can occur only between anti-parallel components of the magnetic flux tubes and may be referred to as component reconnection. The latter configuration type may be more important for the larger class of small-scale reconnection events. The two types of magnetic configurations can be compared to counter-helicity and co-helicity configurations, respectively, in laboratory plasma collision experiments.

  8. 3D hybrid simulations of the plasma penetration across a magnetic field

    NASA Astrophysics Data System (ADS)

    Omelchenko, Yuri

    2016-10-01

    The expansion of hot dense plasmas across ambient magnetic fields in physical systems with spatial scales comparable to the ion gyro and inertial lengths is of great interest to space physics and fusion. This work presents results from recent three-dimensional hybrid simulations (kinetic ions, fluid electrons) of experiments at the LAPD and Nevada Terawatt Facility where short-pulse lasers are used to ablate solid targets to produce plasmas that expand across external magnetic fields. The first simulation recreates flutelike density striations observed at the leading edge of the carbon plasma and predicts an early destruction of the magnetic cavity in agreement with experimental evidence. In the second simulation the plasma contains protons and carbon ions produced during the ablation of a polyethylene target. A mechanism is demonstrated that allows protons to penetrate the magnetic field in the form of a collimated flow while the carbon ion component forms a supporting magnetic structure. The role of ion kinetic and Hall effects in creating an electric field responsible for plasma transport is discussed and results are compared to experimental data. The hybrid simulations are performed with a massively parallel hybrid code, HYPERS that advances fields and particles asynchronously on time scales determined by local physical and geometric properties. Supported by US DOE Award DE-SC0012345.

  9. First MMS Observations of High Time Resolution 3D Electric and Magnetic fields at the Dayside Magnetopause.

    NASA Astrophysics Data System (ADS)

    Torbert, R. B.; Burch, J. L.; Russell, C. T.; Magnes, W.; Ergun, R. E.; Lindqvist, P. A.; Le Contel, O.; Vaith, H.; Macri, J.; Myers, S.; Rau, D.; Needell, J.; King, B.; Granoff, M.; Chutter, M.; Dors, I.; Argall, M. R.; Shuster, J. R.; Olsson, G.; Marklund, G. T.; Khotyaintsev, Y. V.; Eriksson, A. I.; Kletzing, C.; Bounds, S. R.; Anderson, B. J.; Baumjohann, W.; Steller, M.; Bromund, K. R.; Le, G.; Nakamura, R.; Strangeway, R. J.; Leinweber, H. K.; Tucker, S.; Westfall, J.; Fischer, D.; Plaschke, F.; Pollock, C. J.; Giles, B. L.; Moore, T. E.; Mauk, B.; Fuselier, S. A.

    2015-12-01

    The electrodynamics at the magnetopause is key to our understanding of ion and electron acceleration within reconnection regions. The Magnetospheric Multiscale (MMS) fleet of four spacecraft was launched into its Phase-1 equatorial orbit of 12 Re apogee specifically to investigate these regions at the Earth's magnetopause. In addition to a comprehensive suite of particle measurements, MMS makes very high time resolution 3D electric and magnetic field measurements of high accuracy using flux-gate, search coil, 3-axis double probe, and electron drift sensors. In September 2015, the MMS fleet will begin to encounter the dusk-side magnetopause in its initial configuration of approximately 160 km separation, allowing investigation of the spatial and temporal characteristics of important electrodynamics during reconnection. Using these field and particle measurements, we present first observations of 3D magnetic and electric fields (including their parallel component), and inferred current sheets, during active magnetopause crossings using the highest time resolution data available on MMS.

  10. A practical and flexible implementation of 3D MRI in the Earth's magnetic field.

    PubMed

    Halse, Meghan E; Coy, Andrew; Dykstra, Robin; Eccles, Craig; Hunter, Mark; Ward, Rob; Callaghan, Paul T

    2006-09-01

    The Earth's magnetic field, though weak, is appealing for NMR applications because it is highly homogeneous, globally available and free. However, the practicality of Earth's field NMR (EFNMR) has long been limited by the need to perform experiments in outdoor locations where the local field homogeneity is not disrupted by ferrous or magnetic objects and where ultra-low frequency (ULF) noise sources are at a minimum. Herein we present a flexible and practical implementation of MRI in the Earth's magnetic field that demonstrates that EFNMR is not as difficult as it was previously thought to be. In this implementation, pre-polarization and ULF noise shielding, achieved using a crude electromagnet, are used to significantly improve signal-to-noise ratio (SNR) even in relatively noisy environments. A three axis gradient coil set, in addition to providing imaging gradients, is used to provide first-order shims such that sub-hertz linewidths can routinely be achieved, even in locations of significant local field inhomogeneity such as indoor scientific laboratories. Temporal fluctuations in the magnitude of the Earth's magnetic field are measured and a regime found within which these variations in Larmor frequency produce no observable artefacts in reconstructed images.

  11. A 3D model of crustal magnetization at the Pinacate Volcanic Field, NW Sonora, Mexico

    NASA Astrophysics Data System (ADS)

    García-Abdeslem, Juan; Calmus, Thierry

    2015-08-01

    The Pinacate Volcanic Field (PVF) is located near the western border of the southern Basin and Range province, in the State of Sonora NW Mexico, and within the Gulf of California Extensional Province. This volcanic field contains the shield volcano Santa Clara, which mainly consists of basaltic to trachytic volcanic rocks, and reaches an altitude of 1200 m. The PVF disrupts a series of discontinuous ranges of low topographic relief aligned in a NW direction, which consist mainly of Proterozoic metamorphic rocks and Proterozoic through Paleogene granitoids. The PVF covers an area of approximately 60 by 55 km, and includes more than 400 well-preserved cinder cones and vents and eight maar craters. It was active from about 1.7 Ma until about 13 ka. We have used the ages and magnetic polarities of the volcanic rocks, along with mapped magnetic anomalies and their inverse modeling to determine that the Pinacate Volcanic Field was formed during two volcanic episodes. The oldest one built the Santa Clara shield volcano of basaltic and trachytic composition, and occurred during the geomagnetic Matuyama Chron of reverse polarity, which also includes the normal polarity Jaramillo and Olduvai Subchrons, thus imprinting both normal and reverse magnetization in the volcanic products. The younger Pinacate series of basaltic composition represents monogenetic volcanic activity that extends all around the PVF and occurred during the subsequent geomagnetic Brunhes Chron of normal polarity. Magnetic anomalies toward the north of the Santa Clara volcano are the most intense in the PVF, and their inverse modeling indicates the presence of a large subsurface body magnetized in the present direction of the geomagnetic field. This suggests that the magma chambers at depth cooled below the Curie temperature during the Brunhes Chron.

  12. Reproducing Electric Field Observations during Magnetic Storms by means of Rigorous 3-D Modelling and Distortion Matrix Co-estimation

    NASA Astrophysics Data System (ADS)

    Püthe, Christoph; Manoj, Chandrasekharan; Kuvshinov, Alexey

    2015-04-01

    Electric fields induced in the conducting Earth during magnetic storms drive currents in power transmission grids, telecommunication lines or buried pipelines. These geomagnetically induced currents (GIC) can cause severe service disruptions. The prediction of GIC is thus of great importance for public and industry. A key step in the prediction of the hazard to technological systems during magnetic storms is the calculation of the geoelectric field. To address this issue for mid-latitude regions, we developed a method that involves 3-D modelling of induction processes in a heterogeneous Earth and the construction of a model of the magnetospheric source. The latter is described by low-degree spherical harmonics; its temporal evolution is derived from observatory magnetic data. Time series of the electric field can be computed for every location on Earth's surface. The actual electric field however is known to be perturbed by galvanic effects, arising from very local near-surface heterogeneities or topography, which cannot be included in the conductivity model. Galvanic effects are commonly accounted for with a real-valued time-independent distortion matrix, which linearly relates measured and computed electric fields. Using data of various magnetic storms that occurred between 2000 and 2003, we estimated distortion matrices for observatory sites onshore and on the ocean bottom. Strong correlations between modellings and measurements validate our method. The distortion matrix estimates prove to be reliable, as they are accurately reproduced for different magnetic storms. We further show that 3-D modelling is crucial for a correct separation of galvanic and inductive effects and a precise prediction of electric field time series during magnetic storms. Since the required computational resources are negligible, our approach is suitable for a real-time prediction of GIC. For this purpose, a reliable forecast of the source field, e.g. based on data from satellites

  13. Reproducing electric field observations during magnetic storms by means of rigorous 3-D modelling and distortion matrix co-estimation

    NASA Astrophysics Data System (ADS)

    Püthe, Christoph; Manoj, Chandrasekharan; Kuvshinov, Alexey

    2014-12-01

    Electric fields induced in the conducting Earth by geomagnetic disturbances drive currents in power transmission grids, telecommunication lines or buried pipelines, which can cause service disruptions. A key step in the prediction of the hazard to technological systems during magnetic storms is the calculation of the geoelectric field. To address this issue for mid-latitude regions, we revisit a method that involves 3-D modelling of induction processes in a heterogeneous Earth and the construction of a magnetospheric source model described by low-degree spherical harmonics from observatory magnetic data. The actual electric field, however, is known to be perturbed by galvanic effects, arising from very local near-surface heterogeneities or topography, which cannot be included in the model. Galvanic effects are commonly accounted for with a real-valued time-independent distortion matrix, which linearly relates measured and modelled electric fields. Using data of six magnetic storms that occurred between 2000 and 2003, we estimate distortion matrices for observatory sites onshore and on the ocean bottom. Reliable estimates are obtained, and the modellings are found to explain up to 90% of the measurements. We further find that 3-D modelling is crucial for a correct separation of galvanic and inductive effects and a precise prediction of the shape of electric field time series during magnetic storms. Since the method relies on precomputed responses of a 3-D Earth to geomagnetic disturbances, which can be recycled for each storm, the required computational resources are negligible. Our approach is thus suitable for real-time prediction of geomagnetically induced currents by combining it with reliable forecasts of the source field.

  14. 3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets.

  15. 3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets.

  16. Marine induction studies based on measurements of vertical gradient of scalar magnetic field. A concept and 3-D model studies

    NASA Astrophysics Data System (ADS)

    Kuvshinov, Alexey

    2014-05-01

    Most of marine EM studies are based on sea-bottom vector measurements which are logistically and instrumentally demanding and rather expensive. Recently Kuvshinov et al (2013) proposed and proved a low-cost and easy-to-deploy magnetic survey concept which exploits sea surface scalar measurements. The concept is based on responses that relate variations of the scalar magnetic field at offshore survey sites with variations of the horizontal magnetic field at onshore base site. These responses are a mixture of elements of tipper and horizontal magnetic tensor, and thus they can be used to probe the electrical conductivity of the Earth. In the present work we introduce alternative responses that relate variations of vertical gradient of the scalar magnetic field at survey sites with variations of the horizontal magnetic field at a base site. We show that these responses are a mixture of elements of inter-site magnetotelluric tensor, and thus they also can be exploited for EM sounding of the Earth. We discuss the results of 3-D model studies aimed to investigate the sensitivity of the newly introduced responses to hypothetic plume structure beneath Hawaii islands.

  17. CONTINUUM INTENSITY AND [O i] SPECTRAL LINE PROFILES IN SOLAR 3D PHOTOSPHERIC MODELS: THE EFFECT OF MAGNETIC FIELDS

    SciTech Connect

    Fabbian, D.; Moreno-Insertis, F. E-mail: fmi@iac.es

    2015-04-01

    The importance of magnetic fields in three-dimensional (3D) magnetoconvection models of the Sun’s photosphere is investigated in terms of their influence on the continuum intensity at different viewing inclination angles and on the intensity profile of two [O i] spectral lines. We use the RH numerical radiative transfer code to perform a posteriori spectral synthesis on the same time series of magnetoconvection models used in our publications on the effect of magnetic fields on abundance determination. We obtain a good match of the synthetic disk-center continuum intensity to the absolute continuum values from the Fourier Transform Spectrometer (FTS) observational spectrum; the match of the center-to-limb variation synthetic data to observations is also good, thanks, in part, to the 3D radiation transfer capabilities of the RH code. The different levels of magnetic flux in the numerical time series do not modify the quality of the match. Concerning the targeted [O i] spectral lines, we find, instead, that magnetic fields lead to nonnegligible changes in the synthetic spectrum, with larger average magnetic flux causing both of the lines to become noticeably weaker. The photospheric oxygen abundance that one would derive if instead using nonmagnetic numerical models would thus be lower by a few to several centidex. The inclusion of magnetic fields is confirmed to be important for improving the current modeling of the Sun, here in particular in terms of spectral line formation and of deriving consistent chemical abundances. These results may shed further light on the still controversial issue regarding the precise value of the solar oxygen abundance.

  18. 3D Printing of Polymer-Bonded Rare-Earth Magnets With a Variable Magnetic Compound Fraction for a Predefined Stray Field.

    PubMed

    Huber, Christian; Abert, Claas; Bruckner, Florian; Groenefeld, Martin; Schuschnigg, Stephan; Teliban, Iulian; Vogler, Christoph; Wautischer, Gregor; Windl, Roman; Suess, Dieter

    2017-08-25

    Additive manufacturing of polymer-bonded magnets is a recently developed technique, for single-unit production, and for structures that have been impossible to manufacture previously. Also, new possibilities to create a specific stray field around the magnet are triggered. The current work presents a method to 3D print polymer-bonded magnets with a variable magnetic compound fraction distribution. This means the saturation magnetization can be adjusted during the printing process to obtain a required external field of the manufactured magnets. A low-cost, end-user 3D printer with a mixing extruder is used to mix permanent magnetic filaments with pure polyamide (PA12) filaments. The magnetic filaments are compounded, extruded, and characterized for the printing process. To deduce the quality of the manufactured magnets with a variable magnetic compound fraction, an inverse stray field framework is developed. The effectiveness of the printing process and the simulation method is shown. It can also be used to manufacture magnets that produce a predefined stray field in a given region. This opens new possibilities for magnetic sensor applications. This setup and simulation framework allows the design and manufacturing of polymer-bonded permanent magnets, which are impossible to create with conventional methods.

  19. 3-D Modelling of Stretched Solitary Waves along Magnetic Field Lines

    NASA Astrophysics Data System (ADS)

    Muschietti, L.; Roth, I.; Carlson, C. W.; Berthomier, M.

    2001-12-01

    A model is presented for a new type of fast solitary waves which is observed by FAST in downward current regions of the auroral zone. The three-dimensional, coherent structures are electrostatic, have a positive potential, and move along the ambient magnetic field lines with speeds on the order of the electron drift. Their potential profile in the parallel direction, which can be directly measured, is flat-top whereby it cannot fit to the Gaussian shape used in previous work. Their potential profile in the perpendicular direction can only be inferred from a measured unipolar electric signal. We develop an extended BGK model which includes a flattened potential and an assumed cylindrical symmetry around a centric magnetic field line. The model envisions concentric shells of trapped electrons slowly drifting azimuthally while bouncing back and forth in the parallel direction. The electron dynamics is analysed in terms of three basic motions that occur on different time scales. These are defined by the cyclotron frequency Ω e, the bounce frequency ω b, and the azimuthal drift frequency ω γ , for which explicit analytical expressions are obtained. Subject to the ordering ω γ <<ωb<< Ωe, we calculate self-consistent distribution functions in terms of approximate constants of motion. Constraints on the parameters characterizing the amplitude and shape of the stretched solitary wave are discussed.

  20. Modelling of plasma response to 3D external magnetic field perturbations in EAST

    NASA Astrophysics Data System (ADS)

    Yang, Xu; Sun, Youwen; Liu, Yueqiang; Gu, Shuai; Liu, Yue; Wang, Huihui; Zhou, Lina; Guo, Wenfeng

    2016-11-01

    Sustained mitigation and/or suppression of type-I edge localized modes (ELMs) has been achieved in EAST high-confinement plasmas, utilizing the resonant magnetic perturbation (RMP) fields produced by two rows of magnetic coils located just inside the vacuum vessel. Systematic toroidal modelling of the plasma response to these RMP fields with various coil configurations (with dominant toroidal mode number n  = 1, 2, 3, 4) in EAST is, for the first time, carried out by using the MARS-F code (Liu et al 2000 Phys. Plasmas 7 3681), with results reported here. In particular, the plasma response is computed with varying coil phasing (the toroidal phase difference of the coil currents) between the upper and lower rows of coils, from 0 to 360°. Four figures of merit, constructed based on the MARS-F computations, are used to determine the optimal coil phasing. The modelled results, taking into account the plasma response, agree well with the experimental observations in terms of the coil phasing for both the mitigated and the suppressed ELM cases in EAST experiments. This study provides a crucial confirmation of the role of the plasma edge peeling response in ELM control, complementing similar studies carried out for other tokamak devices.

  1. Regional magnetic anomaly fields: 3D Taylor polynomial and surface spline models

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Jiang, Yong; Jiang, Yi; Li, Zheng; Jiang, Jin; Liu, Zhong-Wei; Ye, Mei-Chen; Wang, Hong-Sheng; Li, Xiu-Ming

    2016-03-01

    We used data from 1960.0, 1970.0, 1980.0, 1990.0, and 2000.0 to study the geomagnetic anomaly field over the Chinese mainland by using the three-dimensional Taylor polynomial (3DTP) and the surface spline (SS) models. To obtain the pure anomaly field, the main field and the induced field of the ionospheric and magnetospheric fields were removed from measured data. We also compared the SS model anomalies and the data obtained with Kriging interpolation (KI). The geomagnetic anomaly distribution over the mainland was analyzed based on the SS and 3DTP models by transferring all points from 1960.0-1990.0 to 2000.0. The results suggest that the total intensity F anomalies estimated based on the SS and KI for each year are basically consistent in distribution and intensity. The anomalous distributions in the X-, Y-, and Z-direction and F are mainly negative. The 3DTP model anomalies suggest that the intensity in the X-direction increases from -100 nT to 0 nT with longitude, whereas the intensity in the Y-direction decreases from 400 nT to 20 nT with longitude and over the eastern mainland is almost negative. The intensity in the Z-direction and F are very similar and in most areas it is about -50nT and higher in western Tibet. The SS model anomalies overall reflect the actual distribution of the magnetic field anomalies; however, because of the uneven distribution of measurements, it yields several big anomalies. Owing to the added altitude term, the 3DTP model offers higher precision and is consistent with KI.

  2. Magnetic Properties of 3D Printed Toroids

    NASA Astrophysics Data System (ADS)

    Bollig, Lindsey; Otto, Austin; Hilpisch, Peter; Mowry, Greg; Nelson-Cheeseman, Brittany; Renewable Energy; Alternatives Lab (REAL) Team

    Transformers are ubiquitous in electronics today. Although toroidal geometries perform most efficiently, transformers are traditionally made with rectangular cross-sections due to the lower manufacturing costs. Additive manufacturing techniques (3D printing) can easily achieve toroidal geometries by building up a part through a series of 2D layers. To get strong magnetic properties in a 3D printed transformer, a composite filament is used containing Fe dispersed in a polymer matrix. How the resulting 3D printed toroid responds to a magnetic field depends on two structural factors of the printed 2D layers: fill factor (planar density) and fill pattern. In this work, we investigate how the fill factor and fill pattern affect the magnetic properties of 3D printed toroids. The magnetic properties of the printed toroids are measured by a custom circuit that produces a hysteresis loop for each toroid. Toroids with various fill factors and fill patterns are compared to determine how these two factors can affect the magnetic field the toroid can produce. These 3D printed toroids can be used for numerous applications in order to increase the efficiency of transformers by making it possible for manufacturers to make a toroidal geometry.

  3. 3D modeling of the total electric field induced by transcranial magnetic stimulation using the boundary element method

    NASA Astrophysics Data System (ADS)

    Salinas, F. S.; Lancaster, J. L.; Fox, P. T.

    2009-06-01

    Transcranial magnetic stimulation (TMS) delivers highly localized brain stimulations via non-invasive externally applied magnetic fields. This non-invasive, painless technique provides researchers and clinicians with a unique tool capable of stimulating both the central and peripheral nervous systems. However, a complete analysis of the macroscopic electric fields produced by TMS has not yet been performed. In this paper, we addressed the importance of the secondary E-field created by surface charge accumulation during TMS using the boundary element method (BEM). 3D models were developed using simple head geometries in order to test the model and compare it with measured values. The effects of tissue geometry, size and conductivity were also investigated. Finally, a realistically shaped head model was used to assess the effect of multiple surfaces on the total E-field. Secondary E-fields have the greatest impact at areas in close proximity to each tissue layer. Throughout the head, the secondary E-field magnitudes typically range from 20% to 35% of the primary E-field's magnitude. The direction of the secondary E-field was generally in opposition to the primary E-field; however, for some locations, this was not the case (i.e. going from high to low conductivity tissues). These findings show that realistically shaped head geometries are important for accurate modeling of the total E-field.

  4. 3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Xu, Y.; Ida, K.; Corre, Y.; Feng, Y.; Schmitz, O.; Frerichs, H.; Tabares, F. L.; Evans, T. E.; Coenen, J. W.; Liang, Y.; Bader, A.; Itoh, K.; Yamada, H.; Ghendrih, Ph.; Ciraolo, G.; Tafalla, D.; Lopez-Fraguas, A.; Guo, H. Y.; Cui, Z. Y.; Reiter, D.; Asakura, N.; Wenzel, U.; Morita, S.; Ohno, N.; Peterson, B. J.; Masuzaki, S.

    2015-10-01

    This paper assesses the three-dimensional (3D) effects of the edge magnetic field structure on divertor/scrape-off layer transport, based on an inter-machine comparison of experimental data and on the recent progress of 3D edge transport simulation. The 3D effects are elucidated as a consequence of competition between transports parallel (\\parallel ) and perpendicular (\\bot ) to the magnetic field, in open field lines cut by divertor plates, or in magnetic islands. The competition has strong impacts on divertor functions, such as determination of the divertor density regime, impurity screening and detachment control. The effects of magnetic perturbation on the edge electric field and turbulent transport are also discussed. Parameterization to measure the 3D effects on the edge transport is attempted for the individual divertor functions. Based on the suggested key parameters, an operation domain of the 3D divertor configuration is discussed for future devices.

  5. The Need For High Resolution In Studies Of The 3-D Magnetic Field Structure Of AGN Jets

    NASA Astrophysics Data System (ADS)

    O'Sullivan, S. P.; Gabuzda, D. C.

    2009-08-01

    We are using ``broadband" (4.6 to 43 GHz) multi-frequency VLBA polarization observations of compact AGN to investigate the 3-D structure of their jet magnetic (B) fields. Observing at several frequencies, separated by short and long intervals, enables reliable determination of the distribution of Faraday Rotation, and thereby the intrinsic B field structure. Transverse Rotation Measure (RM) gradients were detected in the jets of 0954+658 and 1418+546, providing evidence for the presence of a helical B field surrounding the jet. The RM in the core regions of 2200+420 (BL Lac), 0954+658 and 1418+546 display different signs in different frequency-intervals (on different spatial scales); we suggest an explanation for this in terms of modest bends in a helical B field surrounding their jets. In future, polarization observations with a combination of VSOP-2 at 8, 22 and 43 GHz and ground arrays at frequencies with corresponding resolution will help map out the distributions of Faraday rotation, spectral index and the 3-D B field structure both across the jet and closer to the central engine, providing strong constraints for any jet B field models.

  6. Combined magnetic vector-scalar potential finite element computation of 3D magnetic field and performance of modified Lundell alternators in Space Station applications. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Wang, Ren H.

    1991-01-01

    A method of combined use of magnetic vector potential (MVP) based finite element (FE) formulations and magnetic scalar potential (MSP) based FE formulations for computation of three-dimensional (3D) magnetostatic fields is developed. This combined MVP-MSP 3D-FE method leads to considerable reduction by nearly a factor of 3 in the number of unknowns in comparison to the number of unknowns which must be computed in global MVP based FE solutions. This method allows one to incorporate portions of iron cores sandwiched in between coils (conductors) in current-carrying regions. Thus, it greatly simplifies the geometries of current carrying regions (in comparison with the exclusive MSP based methods) in electric machinery applications. A unique feature of this approach is that the global MSP solution is single valued in nature, that is, no branch cut is needed. This is again a superiority over the exclusive MSP based methods. A Newton-Raphson procedure with a concept of an adaptive relaxation factor was developed and successfully used in solving the 3D-FE problem with magnetic material anisotropy and nonlinearity. Accordingly, this combined MVP-MSP 3D-FE method is most suited for solution of large scale global type magnetic field computations in rotating electric machinery with very complex magnetic circuit geometries, as well as nonlinear and anisotropic material properties.

  7. Combined magnetic vector-scalar potential finite element computation of 3D magnetic field and performance of modified Lundell alternators in Space Station applications

    NASA Astrophysics Data System (ADS)

    Wang, Ren H.

    1991-02-01

    A method of combined use of magnetic vector potential (MVP) based finite element (FE) formulations and magnetic scalar potential (MSP) based FE formulations for computation of three-dimensional (3D) magnetostatic fields is developed. This combined MVP-MSP 3D-FE method leads to considerable reduction by nearly a factor of 3 in the number of unknowns in comparison to the number of unknowns which must be computed in global MVP based FE solutions. This method allows one to incorporate portions of iron cores sandwiched in between coils (conductors) in current-carrying regions. Thus, it greatly simplifies the geometries of current carrying regions (in comparison with the exclusive MSP based methods) in electric machinery applications. A unique feature of this approach is that the global MSP solution is single valued in nature, that is, no branch cut is needed. This is again a superiority over the exclusive MSP based methods. A Newton-Raphson procedure with a concept of an adaptive relaxation factor was developed and successfully used in solving the 3D-FE problem with magnetic material anisotropy and nonlinearity. Accordingly, this combined MVP-MSP 3D-FE method is most suited for solution of large scale global type magnetic field computations in rotating electric machinery with very complex magnetic circuit geometries, as well as nonlinear and anisotropic material properties.

  8. 3D field calculation of the GEM prototype magnet and comparison with measurements

    SciTech Connect

    Lari, R.J.

    1983-10-28

    The proposed 4 GeV Electron Microtron (GEM) is designed to fill the existing buildings left vacant by the demise of the Zero Gradient Synchrotron (ZGS) accelerator. One of the six large dipole magnets is shown as well as the first 10 electron orbits. A 3-orbit prototype magnet has been built. The stepped edge of the magnet is to keep the beam exiting perpendicular to the pole. The end guards that wrap around the main coils are joined together by the 3 shield plates. The auxiliary coils are needed to keep the end guards and shield plates from saturating. A 0.3 cm Purcell filter air gap exists between the pole and the yoke. Can anyone question this being a truly three-dimensional magnetostatic problem. The computer program TOSCA, developed at the Rutherford Appleton Laboratory by the Computing Applications Group, was used to calculate this magnet and the results have been compared with measurements.

  9. Effect of varying strength and orientation of local interstellar magnetic field on configuration of exterior heliosphere: 3D MHD simulations

    NASA Astrophysics Data System (ADS)

    Ratkiewicz, R.; Barnes, A.; Molvik, G. A.; Spreiter, J. R.; Stahara, S. S.; Vinokur, M.; Venkateswaran, S.

    1998-07-01

    The aim of this paper is to present the effects of varying magnitude and orientation of the local interstellar magnetic field on the heliospheric boundary region (the region between the termination shock and the bow shock containing the heliopause). Other effects such as interstellar neutrals, cosmic rays and the asymmetry of the solar wind caused by its heliolatitude dependence are disregarded. We calculate the shape and structure of the heliospheric boundary region for different interstellar Alfvenic Mach numbers and various inclination angles between Very Local InterStellar Medium (VLISM) velocity and magnetic field vectors using a fully three-dimensional MHD computational analysis. The new results show the asymmetry of this region for inclination angles 0(deg) < alpha < 90(deg) and are in agreement with the Newtonian approximation theory (Fahr et al. 1986, 1988) concerning trends in the heliopause orientation and location. Unlike the NA model which only qualitatively indicates the effects of the VLISM magnetic field on the heliospheric boundary region the present 3D MHD calculations reveal fully the nature of these effects by capturing all discontinuities including the termination shock, heliopause and bow shock. The numerical scheme employed in this study is fully implicit and conservative, using a Roe-type Riemann solver in a generalized coordinate system.

  10. A three-step calibration method for tri-axial field sensors in a 3D magnetic digital compass

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoning; Zhao, Ta; Cheng, Defu; Zhou, Zhijian

    2017-04-01

    In a 3D magnetic compass, it is important to calibrate the tri-axial magnetometers and accelerometers so the compass will provide accurate heading and attitude information. Previous researchers have used two methods to calibrate these two field sensors separately, i.e. the classic independent ellipsoid fitting method and the independent dot product invariant method, respectively. Both methods are easy to use, and no highly accurate, external equipment is required. However, self-calibration with ellipsoid fitting has the disadvantage that it interfuses an orthogonal matrix, and the dot product invariant method requires the use of pre-calibrated internal field sensors, which may be unavailable in many cases. In this paper, we have introduced and unified an error model of two tri-axial field sensors. Accordingly, the orthogonal matrix caused by ellipsoid fitting was mathematically proved to be the combination of two sources, the mounting misalignment and the rotation misalignment. Moreover, a new method, which we call optimal resultant vector, was proposed to further calibrate multi-sensor systems on the basis of ellipsoid fitting and dot product invariant methods, establishing a new, three-step calibration method. The superiority of the proposed method over the state-of-the-art approaches were demonstrated by simulations and a 3D compass experiment.

  11. Secondary Instability in 3-D Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Wang, X.; Lin, Y.; Chen, L.

    2016-12-01

    3-D magnetic reconnection is investigated using the gyrokinetic-electron and fully-kinetic ion (GeFi) particle simulation model. The simulation is carried out in the force free current sheet for cases with a strong guide field BG as occurring in the solar and laboratory plasmas. It is found that, following the growth of the primary reconnection, a secondary instability is excited in the separatrix region, which leads to the electron heating and acceleration in the direction parallel to the magnetic field. The instability is due to the 3-D physics associated with a finite kz, where kz is the wave number along the guide field direction. Dependences of the growth rate of the secondary instability on the electron-ion resistivity, the ion-to-electron mass ratio mi/me, beta values, and the half-width of the current sheet are investigated. It is demonstrated that the secondary instability is of the magnetohydrodynamic (MHD) kink type.

  12. Calibrating MMS Electron Drift Instrument (EDI) Ambient Electron Flux Measurements and Characterizing 3D Electric Field Signatures of Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Shuster, J. R.; Torbert, R. B.; Vaith, H.; Argall, M. R.; Li, G.; Chen, L. J.; Ergun, R. E.; Lindqvist, P. A.; Marklund, G. T.; Khotyaintsev, Y. V.; Russell, C. T.; Magnes, W.; Le Contel, O.; Pollock, C. J.; Giles, B. L.

    2015-12-01

    The electron drift instruments (EDIs) onboard each MMS spacecraft are designed with large geometric factors (~0.01cm2 str) to facilitate detection of weak (~100 nA) electron beams fired and received by the two gun-detector units (GDUs) when EDI is in its "electric field mode" to determine the local electric and magnetic fields. A consequence of the large geometric factor is that "ambient mode" electron flux measurements (500 eV electrons having 0°, 90°, or 180° pitch angle) can vary depending on the orientation of the EDI instrument with respect to the magnetic field, a nonphysical effect that requires a correction. Here, we present determinations of the θ- and ø-dependent correction factors for the eight EDI GDUs, where θ (ø) is the polar (azimuthal) angle between the GDU symmetry axis and the local magnetic field direction, and compare the corrected fluxes with those measured by the fast plasma instrument (FPI). Using these corrected, high time resolution (~1,000 samples per second) ambient electron fluxes, combined with the unprecedentedly high resolution 3D electric field measurements taken by the spin-plane and axial double probes (SDP and ADP), we are equipped to accurately detect electron-scale current layers and electric field waves associated with the non-Maxwellian (anisotropic and agyrotropic) particle distribution functions predicted to exist in the reconnection diffusion region. We compare initial observations of the diffusion region with distributions and wave analysis from PIC simulations of asymmetric reconnection applicable for modeling reconnection at the Earth's magnetopause, where MMS will begin Science Phase 1 as of September 1, 2015.

  13. Computation of load performance and other parameters of extra high speed modified Lundell alternators from 3D-FE magnetic field solutions

    NASA Technical Reports Server (NTRS)

    Wang, R.; Demerdash, N. A.

    1992-01-01

    The combined magnetic vector potential - magnetic scalar potential method of computation of 3D magnetic fields by finite elements, introduced in a companion paper, in combination with state modeling in the abc-frame of reference, are used for global 3D magnetic field analysis and machine performance computation under rated load and overload condition in an example 14.3 kVA modified Lundell alternator. The results vividly demonstrate the 3D nature of the magnetic field in such machines, and show how this model can be used as an excellent tool for computation of flux density distributions, armature current and voltage waveform profiles and harmonic contents, as well as computation of torque profiles and ripples. Use of the model in gaining insight into locations of regions in the magnetic circuit with heavy degrees of saturation is demonstrated. Experimental results which correlate well with the simulations of the load case are given.

  14. Protecting ITER walls: fast ion power loads in 3D magnetic field

    NASA Astrophysics Data System (ADS)

    Kurki-Suonio, T.; Särkimäki, K.; Äkäslompolo, S.; Varje, J.; Liu, Y.; Sipilä, S.; Asunta, O.; Hirvijoki, E.; Snicker, A.; Terävä, J.; Cavinato, M.; Gagliardi, M.; Parail, V.; Saibene, G.

    2017-01-01

    The fusion alpha and beam ion with steady-state power loads in all four main operating scenarios of ITER have been evaluated by the ASCOT code. For this purpose, high-fidelity magnetic backgrounds were reconstructed, taking into account even the internal structure of the ferritic inserts and tritium breeding modules (TBM). The beam ions were found to be almost perfectly confined in all scenarios, and only the so-called hybrid scenario featured alpha loads reaching 0.5 MW due to its more triangular plasma. The TBMs were not found to jeopardize the alpha confinement, nor cause any hot spots. Including plasma response did not bring dramatic changes to the load. The ELM control coils (ECC) were simulated in the baseline scenario and found to seriously deteriorate even the beam confinement. However, the edge perturbation in this case is so large that the sources have to be re-evaluated with plasma profiles that take into account the ECC perturbation.

  15. Mixed model phase evolution for correction of magnetic field inhomogeneity effects in 3D quantitative gradient echo-based MRI.

    PubMed

    Fatnassi, Chemseddine; Boucenna, Rachid; Zaidi, Habib

    2017-07-01

    In 3D gradient echo magnetic resonance imaging (MRI), strong field gradients B0macro are visually observed at air/tissue interfaces. At low spatial resolution in particular, the respective field gradients lead to an apparent increase in intravoxel dephasing, and subsequently, to signal loss or inaccurate R2* estimates. If the strong field gradients are measured, their influence can be removed by postprocessing. Conventional corrections usually assume a linear phase evolution with time. For high macroscopic gradient inhomogeneities near the edge of the brain and at the paranasal sinuses, however, this assumption is often broken. Herein, we explored a novel model that considers both linear and stochastic dependences of the phase evolution with echo time in the presence of weak and strong macroscopic field inhomogeneities. We tested the performance of the model at large field gradients using simulation, phantom, and human in vivo studies. The performance of the proposed approach was markedly better than the standard correction method, providing a correction equivalent to that of the conventional approach in regions with high signal to noise ratio (SNR > 10), but appearing more robust in regions with low SNR (SNR < 4). The proposed technique shows promise to improve R2* measurements in regions of large susceptibilities. The clinical and research applications still require further investigation. © 2017 American Association of Physicists in Medicine.

  16. Magnetic field dependent zero-bias diffusive anomaly in Pb-oxide- n-InAs structures: Coexistence of 2D and 3D states

    NASA Astrophysics Data System (ADS)

    Minkov, G. M.; Germanenko, A. V.; Negachev, S. A.; Rut, O. E.; Sukhorukov, Eugene V.

    1998-12-01

    The results of experimental and theoretical studies of zero-bias anomaly (ZBA) in the Pb-oxide- n-InAs tunnel structures in magnetic field up to 6 T are presented. A specific feature of the structures is a coexistence of the 2D and 3D states at the Fermi energy near the semiconductor surface. Experimentally observed magnetic field dependence of the amplitude of ZBA for different orientations of the magnetic field is in agreement with the proposed theoretical model. According to this model, electrons tunnel into 2D states, and move diffusively in 2D layer, whereas the main contribution to the screening comes from 3D electrons.

  17. Reconstructing the 3D coronal magnetic field using a Potential Field Source Surface model comparing different magnetograph input data

    NASA Astrophysics Data System (ADS)

    Kruse, M. A., II; Peleikis, T.; Berger, L.; Wimmer-Schweingruber, R. F.

    2014-12-01

    We utilize a Potential Field Source Sourface (PFSS) model developed by Altschuler & Newkirk (1969) to model and analyze the coronal magnetic field up to the source surface at 2.5 solar radii. As the photospheric boundary to that model we employ data from several instruments, namely the Wilcox Solar Observatory, NSO's Kitt Peak Vacuum Telescope, the Michelson Doppler Imager onboard the SOHO spacecraft and its successor, the Helioseismic and Magnetic Imager onboard SDO. Instead of the harmonic function approach commonly used, we employ a three dimensional computational grid and methods of computational fluid dynamics to solve the governing equations in order to easily incorporate more complex phenomena if the need for doing so arises during the course of our work. Another advantage of the grid approach is the possibility to outsource the computational work to a parallel computing architecture like NVIDIA's CUDA, which we employ to speed up processing time and increase data throughput significantly. The obtained magnetic field data is utilized in several ways. First it is compared with in-situ data from several spacecraft like Ulysses to validate the employed PFSS model. We further use the expansion geometry of the magnetic field as an input to a 1D-solar-wind model developed by Cranmer et al. (2007) to determine characteristics of the solar wind in several magnetic flux tubes. We can then infer the theoretical charge-state composition inside these flux tubes, which in turn can be employed to test our hypotheses on the origin of the slow solar wind.

  18. Conceptual design of the 3D magnetic field configuration relevant to the magnetopause reconnection in the SPERF

    NASA Astrophysics Data System (ADS)

    Mao, Aohua; Ji, Hantao; Ren, Yang; E, Peng; Wang, Zhibin; Xiao, Qingmei; Xiao, Chijie

    2016-10-01

    A new terrella device, the Space Plasma Environment Research Facility (SPERF), is designed and under construction in China, with Asymmetric Reconnection EXperiment (AREX) as one component to study the interaction between the magnetosheath and magnetosphere plasmas. AREX will provide a unique platform for studying asymmetric magnetic reconnection relevant to the magnetopause, via a set of coils for simulating ``solar-wind-side'' magnetosheath field and a dipole field on the ``magnetosphere-side''. Thus it could be able to investigate a range of important issues in the magnetosphere geometry, such as the electron and ion-scale dynamics in the current sheet, particle and energy transfer from magnetosheath to magnetosphere, particle energization/heating during magnetic reconnection, 3D and asymmetric effects in fast reconnection, and so on. The plasma is generated by two flux cores at the ``magnetosheath-side'' and one electron cyclotron resonance source at the ``magnetosphere-side''. Different kinds of coils with specific current driven functions, as well as advanced diagnostics are designed. Motivation, overview of the AREX design and reconnection scenarios will be discussed.

  19. EDITORIAL: 15th Workshop on MHD Stability Control: 3D Magnetic Field Effects in MHD Control 15th Workshop on MHD Stability Control: 3D Magnetic Field Effects in MHD Control

    NASA Astrophysics Data System (ADS)

    Buttery, Richard

    2011-08-01

    This annual workshop on MHD Stability Control has been held since 1996 with a focus on understanding and developing control of MHD instabilities for future fusion reactors. The workshop generally covers a wide range of stability topics: from disruptions, to tearing modes, error fields, ELMs, resistive wall modes (RWMs) and ideal MHD. It spans many device types, particularly tokamaks, stellarators and reversed field pinches, to pull out commonalities in the physics and improve understanding. In 2010 the workshop was held on 15-17 November at the University of Wisconsin in Madison and was combined with the annual US-Japan MHD Workshop. The theme was `3D Magnetic Field Effects in MHD Control', with a focus on multidisciplinary sessions exploring issues of plasma response to 3D fields, the manifestation of such fields in the plasma, and how they influence stability. This has been a topic of renewed interest, with utilisation of 3D fields for ELM control now planned in ITER, and a focus on the application of such fields for error field correction, disruption avoidance, and RWM control. Key issues included the physics of the interaction, types of coils and harmonic spectra needed to control instabilities, and subsidiary effects such as braking (or rotating) the plasma. More generally, a wider range of issues were discussed including RWM physics, tearing mode physics, disruption mitigation, ballooning stability, the snowflake divertor concept, and the line tied pinch! A novel innovation to the meeting was a panel discussion session, this year on Neoclassical Toroidal Viscosity, which ran well; more will be tried next year. In this special section of Plasma Physics and Controlled Fusion we present several of the invited and contributed papers from the 2010 workshop, which have been subject to the normal refereeing procedures of the journal. These papers give a sense of the exceptional quality of the presentations at this workshop, all of which may be found at http

  20. High-Magnetic-Field Effect on Interplay between Sm 4f and Mn 3d Moments in SmMnO3

    NASA Astrophysics Data System (ADS)

    Iyama, Ayato; Jung, Jong-Suck; Choi, Eun Sang; Hwang, Jungmin; Kimura, Tsuyoshi

    2012-01-01

    Measurements of magnetization and dielectric constant were carried out in static magnetic fields up to 35 T for an N-type ferrimagnetic SmMnO3 with the compensation temperature Tcomp = 9.4 K. In-field data exhibit a first-order-like transition at around Tcomp. The temperature profiles of the magnetization around the transition point show different behaviors between the data taken in magnetic fields whose energy is below and above the magnitude of the interaction between Sm 4f and Mn 3d moments. We interpret that the observed transition results from keen competition among thermal energy, the Zeeman energy, and the f--d interaction.

  1. Finite element analysis of a 3D moving vacuum arc for transverse magnetic field contacts based on Gundlach's formula

    NASA Astrophysics Data System (ADS)

    Kwak, Chang-Seob; Kim, Hong-Kyu; Kim, Tae-Hoon; Lee, Se-Hee

    2017-01-01

    A systematic numerical method for analyzing a 3D moving vacuum arc was proposed and tested in this research by using a transverse magnetic field (TMF) contact. The analysis was carried out by employing the finite element method and the experimental energy equation defined by Gundlach's formula. In the literature, the vacuum interrupter has been widely applied to medium-voltage switching circuits. TMF-type contacts use the Lorentz force density to move a high-temperature arc so as to prevent the contacts from being melted and damaged. The material erosion caused by the arc on the electrode's surface is an important process that results in the interruptive capabilities of these vacuum interrupters. In a classical arc model, to move the vacuum arc, it is required that the magneto-hydrodynamics be analyzed in the arc region at each step. However, with this approach convergence is difficult, resulting in a very time-consuming. Therefore, we propose a new technique to predict the behaviors of vacuum arc between two electrodes. This new approach adopts the experimental arc voltage equation between two electrodes defined by Gundlach's formula. We verify our proposed model by comparing its results with the arcing behaviors obtained from earlier experiments.

  2. A 3D MOF constructed from dysprosium(III) oxalate and capping ligands: ferromagnetic coupling and field-induced two-step magnetic relaxation.

    PubMed

    Liu, Cai-Ming; Zhang, De-Qing; Zhu, Dao-Ben

    2016-04-04

    A novel 3D MOF based on dysprosium(iii) oxalate and 1,10-phenanthroline (phen), {[Dy(C2O4)1.5phen]·0.5H2O}n (1), has been hydrothermally synthesized. The Dy(3+) ion acts as a typical Y-shaped node, linking to each other to generate an interesting 3D topology structure. Complex 1 is the first 3D DyMOF displaying both ferromagnetic coupling and field-induced two-step magnetic relaxation.

  3. 2D/3D quench simulation using ANSYS for epoxy impregnated Nb3Sn high field magnets

    SciTech Connect

    Ryuji Yamada et al.

    2002-09-19

    A quench program using ANSYS is developed for the high field collider magnet for three-dimensional analysis. Its computational procedure is explained. The quench program is applied to a one meter Nb{sub 3}Sn high field model magnet, which is epoxy impregnated. The quench simulation program is used to estimate the temperature and mechanical stress inside the coil as well as over the whole magnet. It is concluded that for the one meter magnet with the presented cross section and configuration, the thermal effects due to the quench is tolerable. But we need much more quench study and improvements in the design for longer magnets.

  4. The Polarization Signature of Photospheric Magnetic Fields in 3D MHD Simulations and Observations at Disk Center

    NASA Astrophysics Data System (ADS)

    Beck, C.; Fabbian, D.; Rezaei, R.; Puschmann, K. G.

    2017-06-01

    Before using three-dimensional (3D) magnetohydrodynamical (MHD) simulations of the solar photosphere in the determination of elemental abundances, one has to ensure that the correct amount of magnetic flux is present in the simulations. The presence of magnetic flux modifies the thermal structure of the solar photosphere, which affects abundance determinations and the solar spectral irradiance. The amount of magnetic flux in the solar photosphere also constrains any possible heating in the outer solar atmosphere through magnetic reconnection. We compare the polarization signals in disk-center observations of the solar photosphere in quiet-Sun regions with those in Stokes spectra computed on the basis of 3D MHD simulations having average magnetic flux densities of about 20, 56, 112, and 224 G. This approach allows us to find the simulation run that best matches the observations. The observations were taken with the Hinode SpectroPolarimeter (SP), the Tenerife Infrared Polarimeter (TIP), the Polarimetric Littrow Spectrograph (POLIS), and the GREGOR Fabry-Pèrot Interferometer (GFPI), respectively. We determine characteristic quantities of full Stokes profiles in a few photospheric spectral lines in the visible (630 nm) and near-infrared (1083 and 1565 nm). We find that the appearance of abnormal granulation in intensity maps of degraded simulations can be traced back to an initially regular granulation pattern with numerous bright points in the intergranular lanes before the spatial degradation. The linear polarization signals in the simulations are almost exclusively related to canopies of strong magnetic flux concentrations and not to transient events of magnetic flux emergence. We find that the average vertical magnetic flux density in the simulation should be less than 50 G to reproduce the observed polarization signals in the quiet-Sun internetwork. A value of about 35 G gives the best match across the SP, TIP, POLIS, and GFPI observations.

  5. Reduction of laser-induced retinal injury applying the combination of the 3D variable electric and magnetic fields in "vivo".

    PubMed

    Makarov, Vladimir I

    2014-06-01

    Oscillating Low Frequency Electro-Magnetic Fields action on eye retina restoration in Rattus Norvegicus was studied in the present work. A beneficial effect of 3-Dimention Oscillating Low Frequency Electro-Magnetic Field was found for the specific values of Electro-Magnetic Field parameters. We found that eye retina damaged by radiation of the fundamental frequency harmonic of a YAG laser has recovered earlier and rehabilitated to the original 3D-state in the presence of OLFEMF, with the parameters listed below in the text. The results obtained were explained by the action of oscillating sub-macro-motions in the cells upon the metabolic processes in these cells.

  6. Study of the 3D Coronal Magnetic Field of Active Region 11117 Around the Time of a Confined Flare Using a Data-Driven CESE-MHD Model

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Feng, X.; Wu, S.; Hu, Q.

    2012-12-01

    Non-potentiality of the solar coronal magnetic field accounts for the solar explosion like flares and CMEs. We apply a data-driven CESE-MHD model to investigate the three-dimensional (3D) coronal magnetic field of NOAA active region (AR) 11117 around the time of a C-class confined flare occurred on 2010 October 25. The CESE-MHD model, based on the spacetime conservation-element and solution-element scheme, is designed to focus on the magnetic-field evolution and to consider a simplified solar atomsphere with finite plasma β. Magnetic vector-field data derived from the observations at the photoshpere is inputted directly to constrain the model. Assuming that the dynamic evolution of the coronal magnetic field can be approximated by successive equilibria, we solve a time sequence of MHD equilibria basing on a set of vector magnetograms for AR 11117 taken by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO) around the time of flare. The model qualitatively reproduces the basic structures of the 3D magnetic field, as supported by the visual similarity between the field lines and the coronal loops observed by the Atmospheric Imaging Assembly (AIA), which shows that the coronal field can indeed be well characterized by the MHD equilibrium in most time. The magnetic configuration changes very limited during the studied time interval of two hours. A topological analysis reveals that the small flare is correlated with a bald patch (BP, where the magnetic field is tangent to the photoshpere), suggesting that the energy release of the flare can be understood by magnetic reconnection associated with the BP separatrices. The total magnetic flux and energy keep increasing slightly in spite of the flare, while the magnetic free energy drops during the flare with an amount of 1.7 × 1030 erg, which can be interpreted as the energy budget released by the minor C-class flare.

  7. External control of the Drosophila melanogaster egg to imago development period by specific combinations of 3D low-frequency electric and magnetic fields.

    PubMed

    Makarov, Vladimir I; Khmelinskii, Igor

    2016-01-01

    We report that the duration of the egg-to-imago development period of the Drosophila melanogaster, and the imago longevity, are both controllable by combinations of external 3-dimensional (3D) low-frequency electric and magnetic fields (LFEMFs). Both these periods may be reduced or increased by applying an appropriate configuration of external 3D LFEMFs. We report that the longevity of D. melanogaster imagoes correlates with the duration of the egg-to-imago development period of the respective eggs. We infer that metabolic processes in both eggs and imago are either accelerated (resulting in reduced time periods) or slowed down (resulting in increased time periods). We propose that external 3D LFEMFs induce electric currents in live systems as well as mechanical vibrations on sub-cell, whole-cell and cell-group levels. These external fields induce media polarization due to ionic motion and orientation of electric dipoles that could moderate the observed effects. We found that the longevity of D. melanogaster imagoes is affected by action of 3D LFEMFs on the respective eggs in the embryonic development period (EDP). We interpret this effect as resulting from changes in the regulation mechanism of metabolic processes in D. melanogaster eggs, inherited by the resulting imagoes. We also tested separate effects of either 3D electric or 3D magnetic fields, which were significantly weaker.

  8. Using a modified 3D-printer for mapping the magnetic field of RF coils designed for fetal and neonatal imaging

    NASA Astrophysics Data System (ADS)

    Vavoulas, Alexander; Vaiopoulos, Nicholas; Hedström, Erik; Xanthis, Christos G.; Sandalidis, Harilaos G.; Aletras, Anthony H.

    2016-08-01

    An experimental setup for characterizing the magnetic field of MRI RF coils was proposed and tested. The setup consisted of a specially configured 3D-printer, a network analyzer and a mid-performance desktop PC. The setup was tested on a single loop RF coil, part of a phased array for fetal imaging. Then, the setup was used for determining the magnetic field characteristics of a high-pass birdcage coil used for neonatal MR imaging with a vertical static field. The scattering parameter S21, converted into power ratio, was used for mapping the B1 magnetic field. The experimental measurements from the loop coil were close to the theoretical results (R = 0.924). A high degree of homogeneity was measured for the neonatal birdcage RF coil. The development of MR RF coils is time consuming and resource intensive. The proposed experimental setup provides an alternative method for magnetic field characterization of RF coils used in MRI.

  9. Quantify Plasma Response to Non-Axisymmetric (3D) Magnetic Fields in Tokamaks, Final Report for FES (Fusion Energy Sciences) FY2014 Joint Research Target

    SciTech Connect

    Strait, E. J.; Park, J. -K.; Marmar, E. S.; Ahn, J. -W.; Berkery, J. W.; Burrell, K. H.; Canik, J. M.; Delgado-Aparicio, L.; Ferraro, N. M.; Garofalo, A. M.; Gates, D. A.; Greenwald, M.; Kim, K.; King, J. D.; Lanctot, M. J.; Lazerson, S. A.; Liu, Y. Q.; Lore, J. D.; Menard, J. E.; Nazikian, R.; Shafer, M. W.; Paz-Soldan, C.; Reiman, A. H.; Rice, J. E.; Sabbagh, S. A.; Sugiyama, L.; Turnbull, A. D.; Volpe, F.; Wang, Z. R.; Wolfe, S. M.

    2014-09-30

    The goal of the 2014 Joint Research Target (JRT) has been to conduct experiments and analysis to investigate and quantify the response of tokamak plasmas to non-axisymmetric (3D) magnetic fields. Although tokamaks are conceptually axisymmetric devices, small asymmetries often result from inaccuracies in the manufacture and assembly of the magnet coils, or from nearby magnetized objects. In addition, non-axisymmetric fields may be deliberately applied for various purposes. Even at small amplitudes of order 10-4 of the main axisymmetric field, such “3D” fields can have profound impacts on the plasma performance. The effects are often detrimental (reduction of stabilizing plasma rotation, degradation of energy confinement, localized heat flux to the divertor, or excitation of instabilities) but may in some case be beneficial (maintenance of rotation, or suppression of instabilities). In general, the magnetic response of the plasma alters the 3D field, so that the magnetic field configuration within the plasma is not simply the sum of the external 3D field and the original axisymmetric field. Typically the plasma response consists of a mixture of local screening of the external field by currents induced at resonant surfaces in the plasma, and amplification of the external field by stable kink modes. Thus, validated magnetohydrodynamic (MHD) models of the plasma response to 3D fields are crucial to the interpretation of existing experiments and the prediction of plasma performance in future devices. The non-axisymmetric coil sets available at each facility allow well-controlled studies of the response to external 3D fields. The work performed in support of the 2014 Joint Research Target has included joint modeling and analysis of existing experimental data, and collaboration on new experiments designed to address the goals of the JRT. A major focus of the work was validation of numerical models through quantitative comparison to experimental data, in

  10. Jovian Plasmas Torus Interaction with Europa. Plasma Wake Structure and Effect of Inductive Magnetic Field: 3D Hybrid Kinetic Simulation

    NASA Technical Reports Server (NTRS)

    Lipatov, A. S.; Cooper, J F.; Paterson, W. R.; Sittler, E. C., Jr.; Hartle, R. E.; Simpson, David G.

    2013-01-01

    The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect to a variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions). Photoionization, electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider the models with Oþ þ and Sþ þ background plasma, and various betas for background ions and electrons, and pickup electrons. The majority of O2 atmosphere is thermal with an extended non-thermal population (Cassidy et al., 2007). In this paper, we discuss two tasks: (1) the plasma wake structure dependence on the parameters of the upstream plasma and Europa's atmosphere (model I, cases (a) and (b) with a homogeneous Jovian magnetosphere field, an inductive magnetic dipole and high oceanic shell conductivity); and (2) estimation of the possible effect of an induced magnetic field arising from oceanic shell conductivity. This effect was estimated based on the difference between the observed and modeled magnetic fields (model II, case (c) with an inhomogeneous Jovian magnetosphere field, an inductive

  11. General principles of describing second- and higher-order null points of a potential magnetic field in 3D

    NASA Astrophysics Data System (ADS)

    Lukashenko, A. T.; Veselovsky, I. S.

    2015-12-01

    General principles of describing secondand higher-order null points of a potential magnetic field are formulated. The potential near a second-order null of the general form can be specified by a linear combination of four basic functions, the list of which is presented. Near secondand higher-order null points, field line equations often cannot be integrated analytically; however, in some cases, it is possible to present a qualitative description of the geometry of null vicinities with consideration of the behavior of field lines near rays outgoing from null, at which the field is radial or equals zero.

  12. The Effect of Dissipation Mechanism and Guide Field Strength on X-line Spreading in 3D Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Shepherd, Lucas; Cassak, P.; Drake, J.; Gosling, J.; Phan, T.; Shay, M. A.

    2013-07-01

    In two-ribbon flares, the fact that the ribbons separate in time is considered evidence of magnetic reconnection. However, in addition to the ribbons separating, they can also elongate (as seen in animations of, for example, the Bastille Day flare). The elongation is undoubtedly related to the reconnection spreading in the out-of-plane direction. Indeed, naturally occurring magnetic reconnection generally begins in a spatially localized region and spreads in the direction perpendicular to the reconnection plane as time progresses. For example, it was suggested that X-line spreading is necessary to explain the observation of X-lines extending more than 390 Earth radii (Phan et al., Nature, 404, 848, 2006), and has been seen in reconnection experiments. A sizeable out-of-plane (guide) magnetic field is present at flare sites and in the solar wind. Here, we study the effect of dissipation mechanism and the strength of the guide field has on X-line spreading. We present results from three-dimensional numerical simulations of magnetic reconnection, comparing spreading with the Hall term to spreading with anomalous resistivity. Applications to solar flares and magnetic reconnection in the solar wind will be discussed.

  13. Investigation of surfactant-enhanced mass removal and flux reduction in 3D correlated permeability fields using magnetic resonance imaging.

    PubMed

    Zhang, Changyong; Werth, Charles J; Webb, Andrew G

    2008-09-10

    Magnetic resonance imaging (MRI) was used to visualize the NAPL source zone architecture before and after surfactant-enhanced NAPL dissolution in three-dimensional (3D) heterogeneously packed flowcells characterized by different longitudinal correlation lengths: 2.1 cm (aquifer 1) and 1.1 cm (aquifer 2). Surfactant flowpaths were determined by imaging the breakthrough of a paramagnetic tracer (MnCl(2)) analyzed by the method of moments. In both experimental aquifers, preferential flow occurred in high permeability materials with low NAPL saturations, and NAPL was preferentially removed from the top of the aquifers with low saturation. Alternate flushing with water and two surfactant pulses (5-6 pore volumes each) resulted in approximately 63% of NAPL mass removal from both aquifers. However, overall reduction in mass flux (Mass Flux 1) exiting the flowcell was lower in aquifer 2 (68%) than in aquifer 1 (81%), and local effluent concentrations were found to increase by as high as 120 times at local sampling ports from aquifer 2 after surfactant flushing. 3D MRI images of NAPL revealed that NAPL migrated downward and created additional NAPL source zones in previously uncontaminated areas at the bottom of the aquifers. The additional NAPL source zones were created in the direction transverse to flow in aquifer 2, which explains the higher mass flux relative to aquifer 1. Analysis using a total trapping number indicates that mobilization of NAPL trapped in the two coarsest sand fractions is possible when saturation is below 0.5 and 0.4, respectively. Results from this study highlight the potential impacts of porous media heterogeneity and NAPL source zone architecture on advanced in-situ flushing technologies.

  14. Trans-Hudsonian far-field deformation effects in the Rae foreland: An integrated geological-3D magnetic model

    NASA Astrophysics Data System (ADS)

    Percival, J. A.; Tschirhart, V.

    2017-03-01

    The intracratonic Rae cover sequence, deposited ca. 2.2-1.9 Ga, forms a useful marker for unravelling tectonic events that affected the Archean Rae Province at ca.2.0, 1.9 and 1.85 Ga. Polyphase deformation is recognized within the Rae cover rocks, including the 70 × 10 km Montresor belt, and attributed to distal effects of the ca. 1.85 Ga Trans-Hudson orogeny. In this contribution we explore the 3D geometry and structural history of the Montresor belt, previously considered to be a simple syncline lying unconformably on Archean basement. New geological, geophysical and geochronological results define a more complex history in which lower Montresor units were thrust-imbricated with basement gneisses and metamorphosed to the amphibolite facies. Mid-to upper greenschist facies upper Montresor units, exposed in an open synform, are superficially less deformed. However, using high-resolution aeromagnetic data and distinct magnetic marker units considered proxies for bedding, we constructed a set of forward models to explore the three-dimensional geometry of the belt. The re-analysis outlines a set of pre-synform structures defined by low-angle truncations of the magnetic markers. Geometric relationships indicate the presence of at least three faults at low angles to bedding, interpreted as D1 piggy-back thrusts, and bracketed by available geochronology between 1.924 and 1.87 Ga. D1 strain in the upper Montresor strata is significantly less intense than that further south in Rae cover rocks, consistent with a more distal foreland setting during the Trans-Hudson orogeny. The Montresor belt preserves a record of the Trans-Hudson tectonic style at relatively shallow crustal levels as a result of its foreland setting and structural history including a syn-orogenic extensional detachment event.

  15. In-Plane Magnetic Field Effect on the Transport Properties in a Quasi-3D Quantum Well Structure

    SciTech Connect

    Brooks, J.; Clark, R.; Lumpkin, N.; O'Brien, J.; Reno, J.; Simmons, J.; Wang, Z.; Zhang, B.

    1999-05-25

    The transport properties of a quasi-three-dimensional, 200 layer quantum well structure are investigated at integer filling in the quantum Hall state. We find that the transverse magnetoresistance Rxx, the Hall resistance Rxy, and the vertical resistance Rzz all follow a similar behavior with both temperature and in-plane magnetic field. A general feature of the influence of increasing in-plane field Bin is that the Hall conductance quantization first improves, but above a characteristic value BCin, the quantization is systematically removed. We consider the interplay of the chid edge state transport and the bulk (quantum Hall) transport properties. This mechanism may arise from the competition of the cyclotron energy with the superlattice band structure energies. A comparison of the resuIts with existing theories of the chiral edge state transport with in-plane field is also discussed.

  16. Using a modified 3D-printer for mapping the magnetic field of RF coils designed for fetal and neonatal imaging.

    PubMed

    Vavoulas, Alexander; Vaiopoulos, Nicholas; Hedström, Erik; Xanthis, Christos G; Sandalidis, Harilaos G; Aletras, Anthony H

    2016-08-01

    An experimental setup for characterizing the magnetic field of MRI RF coils was proposed and tested. The setup consisted of a specially configured 3D-printer, a network analyzer and a mid-performance desktop PC. The setup was tested on a single loop RF coil, part of a phased array for fetal imaging. Then, the setup was used for determining the magnetic field characteristics of a high-pass birdcage coil used for neonatal MR imaging with a vertical static field. The scattering parameter S21, converted into power ratio, was used for mapping the B1 magnetic field. The experimental measurements from the loop coil were close to the theoretical results (R=0.924). A high degree of homogeneity was measured for the neonatal birdcage RF coil. The development of MR RF coils is time consuming and resource intensive. The proposed experimental setup provides an alternative method for magnetic field characterization of RF coils used in MRI. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Initial Results from 3D Electric and Magnetic Field Measurements of the Interaction of a Laser-Produced and Ambient Plasma

    NASA Astrophysics Data System (ADS)

    Heuer, P. V.; Schaeffer, D. B.; Hofer, L. R.; Constantin, C. G.; Bondarenko, A. S.; Everson, E. T.; Clark, S. E.; Gekelman, W.; Niemann, C.

    2015-11-01

    Utilizing high-repetition lasers combined with a high-repetition ambient plasma allows for detailed 3D scans of the interaction of the laser-produced and ambient plasmas. We present the first results from experiments combining a newly-commissioned high-repetition (1 Hz) laser with the 1 Hz ambient plasma of the Large Plasma Device (LAPD) at the University of California, Los Angeles. The laser (20 J, 14 ns) was focused on a cylindrical plastic target embedded in the ambient LAPD plasma, resulting in an ablated debris-plasma that expanded perpendicular to the background magnetic field. The debris-ambient plasma interaction was studied with 3-axis magnetic flux probes, mounted on a 3D motion drive for detailed, high-resolution planar scans both along and perpendicular to the background field. Measurements were also taken using filtered fast-gate (ns) imaging, emissive Langmuir probes, and emissive spectroscopy. The results show that the debris ions are de-energized inside the diamagnetic cavity, while the ambient ions are accelerated through laminar electric fields.

  18. Dissipation mechanism in 3D magnetic reconnection

    SciTech Connect

    Fujimoto, Keizo

    2011-11-15

    Dissipation processes responsible for fast magnetic reconnection in collisionless plasmas are investigated using 3D electromagnetic particle-in-cell simulations. The present study revisits the two simulation runs performed in the previous study (Fujimoto, Phys. Plasmas 16, 042103 (2009)); one with small system size in the current density direction, and the other with larger system size. In the case with small system size, the reconnection processes are almost the same as those in 2D reconnection, while in the other case a kink mode evolves along the current density and deforms the current sheet structure drastically. Although fast reconnection is achieved in both the cases, the dissipation mechanism is very different between them. In the case without kink mode, the electrons transit the electron diffusion region without thermalization, so that the magnetic dissipation is supported by the inertia resistivity alone. On the other hand, in the kinked current sheet, the electrons are not only accelerated in bulk, but they are also partly scattered and thermalized by the kink mode, which results in the anomalous resistivity in addition to the inertia resistivity. It is demonstrated that in 3D reconnection the thickness of the electron current sheet becomes larger than the local electron inertia length, consistent with the theoretical prediction in Fujimoto and Sydora (Phys. Plasmas 16, 112309 (2009)).

  19. Multimaterial magnetically assisted 3D printing of composite materials.

    PubMed

    Kokkinis, Dimitri; Schaffner, Manuel; Studart, André R

    2015-10-23

    3D printing has become commonplace for the manufacturing of objects with unusual geometries. Recent developments that enabled printing of multiple materials indicate that the technology can potentially offer a much wider design space beyond unusual shaping. Here we show that a new dimension in this design space can be exploited through the control of the orientation of anisotropic particles used as building blocks during a direct ink-writing process. Particle orientation control is demonstrated by applying low magnetic fields on deposited inks pre-loaded with magnetized stiff platelets. Multimaterial dispensers and a two-component mixing unit provide additional control over the local composition of the printed material. The five-dimensional design space covered by the proposed multimaterial magnetically assisted 3D printing platform (MM-3D printing) opens the way towards the manufacturing of functional heterogeneous materials with exquisite microstructural features thus far only accessible by biological materials grown in nature.

  20. Multimaterial magnetically assisted 3D printing of composite materials

    PubMed Central

    Kokkinis, Dimitri; Schaffner, Manuel; Studart, André R.

    2015-01-01

    3D printing has become commonplace for the manufacturing of objects with unusual geometries. Recent developments that enabled printing of multiple materials indicate that the technology can potentially offer a much wider design space beyond unusual shaping. Here we show that a new dimension in this design space can be exploited through the control of the orientation of anisotropic particles used as building blocks during a direct ink-writing process. Particle orientation control is demonstrated by applying low magnetic fields on deposited inks pre-loaded with magnetized stiff platelets. Multimaterial dispensers and a two-component mixing unit provide additional control over the local composition of the printed material. The five-dimensional design space covered by the proposed multimaterial magnetically assisted 3D printing platform (MM-3D printing) opens the way towards the manufacturing of functional heterogeneous materials with exquisite microstructural features thus far only accessible by biological materials grown in nature. PMID:26494528

  1. Voltage controlled magnetism in 3d transitional metals

    NASA Astrophysics Data System (ADS)

    Wang, Weigang

    2015-03-01

    Despite having attracted much attention in multiferroic materials and diluted magnetic semiconductors, the impact of an electric field on the magnetic properties remains largely unknown in 3d transitional ferromagnets (FMs) until recent years. A great deal of effort has been focused on the voltage-controlled magnetic anisotropy (VCMA) effect where the modulation of anisotropy field is understood by the change of electron density among different d orbitals of FMs in the presence of an electric field. Here we demonstrate another approach to alter the magnetism by electrically controlling the oxidation state of the 3d FM at the FM/oxide interface. The thin FM film sandwiched between a heavy metal layer and a gate oxide can be reversibly changed from an optimally-oxidized state with a strong perpendicular magnetic anisotropy to a metallic state with an in-plane magnetic anisotropy, or to a fully-oxidized state with nearly zero magnetization, depending on the polarity and time duration of the applied electric fields. This is a voltage controlled magnetism (VCM) effect, where both the saturation magnetization and anisotropy field of the 3d FM layer can be simultaneously controlled by voltage in a non-volatile fashion. We will also discuss the impact of this VCM effect on magnetic tunnel junctions and spin Hall switching experiments. This work, in collaboration with C. Bi, Y.H. Liu, T. Newhouse-Illige, M. Xu, M. Rosales, J.W. Freeland, O. Mryasov, S. Zhang, and S.G.E. te Velthuis, was supported in part by NSF (ECCS-1310338) and by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA.

  2. Magnetic field driven 2D-3D crossover in the S =1/2 frustrated chain magnet LiCuVO4

    NASA Astrophysics Data System (ADS)

    Prozorova, L. A.; Sosin, S. S.; Svistov, L. E.; Büttgen, N.; Kemper, J. B.; Reyes, A. P.; Riggs, S.; Prokofiev, A.; Petrenko, O. A.

    2015-05-01

    We report on a heat-capacity study of high-quality single-crystal samples of LiCuVO4—a frustrated spin S =1/2 chain system—in a magnetic field amounting to 3/4 of the saturation field. A detailed examination of magnetic phase transitions observed in this field range shows that although the low-field helical state clearly has three-dimensional properties, the field-induced spin-modulated phase turns out to be quasi-two-dimensional. The model proposed in this paper allows one to qualitatively understand this crossover, thus eliminating the presently existing contradictions in the interpretations of NMR and neutron-scattering measurements.

  3. A Study of the 3-D Reconstruction of Heliospheric Vector Magnetic Fields From Faraday-Rotation Inversion

    DTIC Science & Technology

    2009-12-30

    field extrapolated from the solar surface to provide the FR signal (from the densities reconstructed during the Bastille Day CME). (b) The same density...LASCO coronagraphs. Earth’s orbit is shown as a near-circle or line with the Earth, ⊕, indicated on each plot. The expected r−2 density fall -off...Comparison with SMEI White-Light Observations’, EOS Trans. AGU 87(52), Fall Meet. Suppl., Abstract SH33A-0397. Jensen, E.A., Hick, P.P., Bisi, M.M

  4. Switchable field-tuned control of magnetic domain wall pinning along Co microwires by 3D e-beam lithographed structures

    NASA Astrophysics Data System (ADS)

    Blanco-Roldán, C.; Quirós, C.; Rodriguez-Rodriguez, G.; Vélez, M.; Martín, J. I.; Alameda, J. M.

    2016-02-01

    Three-dimensional magnetic circuits composed of Co microwires crossed by elevated Co bridges have been patterned on Si substrate by e-beam lithography and lift-off process. The lithographic procedure includes a double resist procedure that optimizes the shape of the bridge, so that 200 nm air gaps can be routinely achieved in between the wire and bridge elements. Microwire magnetization reversal processes have been analyzed by magneto-optical Kerr effect microscopy with different remanent bridge configurations. When the Co bridge is magnetized along the in-plane direction parallel to the wire axis, its stray field induces a marked pinning effect on domain wall propagation along the wire below it, even without being in contact. Changing the sign of the remanent state of the bridge, domain wall pinning can be selected to occur in either the ascending or descending branches of the wire hysteresis loop. Thus, these wire-bridge 3D circuits provide a simple system for tunable domain wall pinning controllable through the pre-recorded bridge remanent state.

  5. Tracking Efficiency And Charge Sharing of 3D Silicon Sensors at Different Angles in a 1.4T Magnetic Field

    SciTech Connect

    Gjersdal, H.; Bolle, E.; Borri, M.; Da Via, C.; Dorholt, O.; Fazio, S.; Grenier, P.; Grinstein, S. Hansson, P.; Hasi, J.; Hugging, F.; Jackson, P.; Kenney, C.; Kocian, M.; La Rosa, A.; Mastroberardino, A.; Nordahl, P.; Rivero, F.; Rohne, O.; Sandaker, H.; Sjobaek, K.; /Oslo U. /Prague, Tech. U. /SLAC /Bonn U. /SUNY, Stony Brook /Bonn U. /SLAC

    2012-05-07

    A 3D silicon sensor fabricated at Stanford with electrodes penetrating throughout the entire silicon wafer and with active edges was tested in a 1.4 T magnetic field with a 180 GeV/c pion beam at the CERN SPS in May 2009. The device under test was bump-bonded to the ATLAS pixel FE-I3 readout electronics chip. Three readout electrodes were used to cover the 400 {micro}m long pixel side, this resulting in a p-n inter-electrode distance of {approx} 71 {micro}m. Its behavior was confronted with a planar sensor of the type presently installed in the ATLAS inner tracker. Time over threshold, charge sharing and tracking efficiency data were collected at zero and 15{sup o} angles with and without magnetic field. The latest is the angular configuration expected for the modules of the Insertable B-Layer (IBL) currently under study for the LHC phase 1 upgrade expected in 2014.

  6. 3-D Magnetospheric Field and Plasma Containing Thin Current Sheets

    NASA Astrophysics Data System (ADS)

    Zaharia, S.; Cheng, C. Z.; Maezawa, K.; Wing, S.

    2002-05-01

    In this study we present fully-3D self-consistent solutions of the magnetosphere by using observation-based plasma pressure distributions and computational boundary conditions based on the T96 magnetospheric field model. The pressure profiles we use are either taken directly from observations (GEOTAIL pressure data in the plasma sheet and DMSP ionospheric pressure) or empirical (Spence-Kivelson formula for pressure on the midnight equatorial line). The 3-D solutions involve solving 2 coupled elliptic equations in a flux coordinate systems, with the magnetic field expressed by two Euler potentials and using appropriate boundary conditions for both the closed- and open-field regions derived from the empirical field model. We look into how the self-consistent magnetic field and current structures change under different external conditions, and we discuss the appearance of thin cross-tail current sheets during disturbed magnetospheric times.

  7. Majority logic gate for 3D magnetic computing.

    PubMed

    Eichwald, Irina; Breitkreutz, Stephan; Ziemys, Grazvydas; Csaba, György; Porod, Wolfgang; Becherer, Markus

    2014-08-22

    For decades now, microelectronic circuits have been exclusively built from transistors. An alternative way is to use nano-scaled magnets for the realization of digital circuits. This technology, known as nanomagnetic logic (NML), may offer significant improvements in terms of power consumption and integration densities. Further advantages of NML are: non-volatility, radiation hardness, and operation at room temperature. Recent research focuses on the three-dimensional (3D) integration of nanomagnets. Here we show, for the first time, a 3D programmable magnetic logic gate. Its computing operation is based on physically field-interacting nanometer-scaled magnets arranged in a 3D manner. The magnets possess a bistable magnetization state representing the Boolean logic states '0' and '1.' Magneto-optical and magnetic force microscopy measurements prove the correct operation of the gate over many computing cycles. Furthermore, micromagnetic simulations confirm the correct functionality of the gate even for a size in the nanometer-domain. The presented device demonstrates the potential of NML for three-dimensional digital computing, enabling the highest integration densities.

  8. Vibrating sample magnetometer 2D and 3D magnetization effects associated with different initial magnetization states

    NASA Astrophysics Data System (ADS)

    Lukins, Ronald E.

    2017-05-01

    Differences in VSM magnetization vector rotation associated with various initial magnetization states were demonstrated. Procedures and criteria were developed to select sample orientation and initial magnetization states to allow for the combination of two different 2D measurements runs (with the same field profiles) to generate a dataset that can be representative of actual 3D magnetization rotation. Nickel, cast iron, and low moment magnetic tape media were used to demonstrate these effects using hysteresis and remanent magnetization test sequences. These results can be used to generate 2D and 3D magnetic properties to better characterize magnetic phenomena which are inherently three dimensional. Example applications are magnetic tape-head orientation sensitivity, reinterpretation of 3D coercivity and other standard magnetic properties, and multi-dimensional shielding effectiveness.

  9. Visualization of 3-D tensor fields

    NASA Technical Reports Server (NTRS)

    Hesselink, L.

    1996-01-01

    Second-order tensor fields have applications in many different areas of physics, such as general relativity and fluid mechanics. The wealth of multivariate information in tensor fields makes them more complex and abstract than scalar and vector fields. Visualization is a good technique for scientists to gain new insights from them. Visualizing a 3-D continuous tensor field is equivalent to simultaneously visualizing its three eigenvector fields. In the past, research has been conducted in the area of two-dimensional tensor fields. It was shown that degenerate points, defined as points where eigenvalues are equal to each other, are the basic singularities underlying the topology of tensor fields. Moreover, it was shown that eigenvectors never cross each other except at degenerate points. Since we live in a three-dimensional world, it is important for us to understand the underlying physics of this world. In this report, we describe a new method for locating degenerate points along with the conditions for classifying them in three-dimensional space. Finally, we discuss some topological features of three-dimensional tensor fields, and interpret topological patterns in terms of physical properties.

  10. Proton acceleration by 3D magnetic reconnection in solar flares

    NASA Astrophysics Data System (ADS)

    Browning, P. K.; Dalla, S.

    2007-05-01

    High energy charged particles are an important feature of solar activity such as flares, and indeed non thermal particles play a significant role in flare energy balance. Magnetic reconnection is the primary energy release mechanism in flares, and the strong DC electric fields associated with this reconnection may well be the origin of the high energy charged particles. Whilst particle acceleration has been widely studied for 2D configurations, little is known about 3D configurations. We investigate particle acceleration using a test particle approach, in the simplest 3D reconnection configuration, a 3D magnetic null point. Two modes of reconnection are possible: with a strong current filament along the "spine" field line connecting to the null, or with a sheet current at the "fan" plane of field lines emerging from the null. Using simple model fields, incorporating intiially only thee ideal reconnection region outside the current sheet (or filament), particle trajectories are investigated and the energy spectra and spatial distribution of accelerated particles are determined. We consider and compare fan and spine reconnection, and determine how the properties of the accelerated particles depend on the parameters of the reonnecting field. We also present preliminary results using more realistic, self consistent model fields.

  11. Kinetic shielding of magnetic islands in 3-D equilibria

    NASA Astrophysics Data System (ADS)

    Hegna, C. C.

    2010-11-01

    Kinetic theory is employed to calculate corrections to analytic predictions of saturated magnetic islands due to pressure gradients in 3-D magnetic configurations. The theory calculates the dominant trapped particle response to 3-D field induced net bounce averaged radial drifts. The associated kinetic response describes plasma currents that flow within magnetic surfaces. In general, these currents have a component that resonates with the helical angle of the magnetic island and affect saturated island sizes through the parallel currents generated to satisfy quasineutrality. The resulting kinetic response generally opposes the effects of singular Pfirsch-Schlüter currents that arise at the rational surfaces of general 3-D MHD equilibria. Accounting for both the MHD and kinetic responses, self-consistent magnetic island widths are calculated using Ampere's law. The kinetic effect is largest at lowest collisionality suggesting high-β stellarators are more resilient to retaining flux surface integrity at high-temperatures than predictions from conventional MHD based theory would imply.

  12. 3-D MHD Model of the Solar Wind-Interplanetary Space Combining System 1:Variation of Solar Wind Speed Associated with the Photospheric Magnetic Field

    NASA Astrophysics Data System (ADS)

    Nakamizo, A.; Tanaka, T.

    2006-12-01

    Existing global models of the solar-wind/IMF expanding to the Earth's orbit are basically grounded in the idea of "source surface." It is widely accepted that the sector structure and the solar wind speed are primarily controlled by the magnetic field at the source surface and the so-called "expansion factor." On the other hand, 3-D MHD model is still off from practical use because both of scientific and technical problems. One of the former problems is the reproduction of supersonic solar-wind. From the viewpoint of the physics of the solar wind, coronal heating and outward acceleration mechanisms are invoked to explain the supersonic evolution of the solar wind. Since the mechanism responsible for the heating/acceleration is still one of the primary subjects of the physics of the solar wind, many MHD models have taken into account their effects by incorporating additional source terms corresponding to promising candidates such as thermal conductions, radiation losses and wave pressures. However there are few MHD models considering the effect of the expansion factor, which determines the solar-wind speed in the series of source surface models. In this study we newly incorporate the flux tube expansion rate into the MHD equation system including heat source function in the energy equation. Appling the unstructured grid system, we achieved the dense grid spacing at the inner boundary, which enable us to adopt realistic solar magnetic fields, and a size of simulation space of 1AU. Photospheric magnetic field data is used as the inner boundary condition.The simulation results are summarized as: (1) The variation of solar wind speed is well controlled by the structure of magnetic fields at and little above the solar surface and (2) Far above the solar surface, the interface between high and low speed flows evolves to a structure suggestive of CIRs. Comparing the data from simulation with the actual solar wind data obtained by spacecrafts, we will discuss the future

  13. 3-D MHD Simulation of Oscillating Field Current Drive

    NASA Astrophysics Data System (ADS)

    Ebrahimi, F.; Prager, S. C.; Wright, J. C.

    2000-10-01

    Oscillating Field Current Drive (OFCD) is a proposed low frequency steady-state current drive technique for the Reversed Field Pinch (RFP). In OFCD toroidal and poloidal oscillating electric fields are applied with 90^circ phase difference to inject magnetic helicity. In the present work, the 3-D nonlinear, resistive MHD code DEBS is used to simulate OFCD in relaxed RFP plasmas. The present simulations are at high Lundquist number S=10^5 and low spect ratio R/a=1.5. The physics issues investigated are the response of background magnetic fluctuations to the oscillating fields, the relative contributions of the tearing mode dynamo and the oscillating fields to the current profile, and the sustainment and control of the steady-state current profile. Initial results with low amplitude oscillating fields show the expected increase in magnetic helicity and current. Results with higher amplitude will also be presented.

  14. Flux and Field Line Conservation in 3-D Non-Ideal MHD Flows: Remarks About Criteria for 3-D Reconnection Without Magnetic Neutral Points and Their Application to the Heliospheric Interface

    NASA Astrophysics Data System (ADS)

    Nickeler, D. H.; Fahr, H.-J.

    2006-05-01

    In this paper, we address the issue of finding velocity fields which conserve magnetic flux or at least magnetic fieldline connectivity. We start from the basic principles of flux and line conservation and present and discuss the criterion, given by Newcomb (1958), Stern (1966), and Vasyliunas (1972). In addition, we find a new formulation of the line-conserving velocity field by solving the system of partial differential equations which corresponds to Newcomb's criterion for line conservation. This velocity field is given by a correlation between the non-idealness, described by a generalized form of the Ohm's law and a general transporting velocity, which is fieldline conserving. Our considerations give additional insights into the discussion on violations of the frozen-in field concept which started recently with the papers by Baranov and Fahr (2003a,b). These authors analyzed a generalized form of Ohm's law, which is valid for the heliosphere and claimed that the transport velocity for the magnetic flux may be different from the plasma velocity. We can show that the non-idealness given in the paper by Baranov and Fahr could not change the magnetic topology and can therefore not be responsible for magnetic reconnection. But we found that it is in general not clear if the flux-conserving velocity field is identical to the plasma flow or to any species velocity field.

  15. Particle acceleration at 3D reconnecting magnetic separators

    NASA Astrophysics Data System (ADS)

    Threlfall, James; Neukirch, Thomas; Parnell, Clare; Stevenson, Julie

    2015-04-01

    We present results of test particle orbit calculations in three different environments which model separator reconnection in three dimensions. The test particle (electron and proton) orbits are calculated using the relativistic guiding centre approximation. We investigate test particle orbits in a time-dependent (analytical) electro-magnetic field configuration [detailed in Threlfall et al. (A&A, in press); arXiv:1410.6465]. These results are also compared with orbits based upon large-scale 3D MHD simulations of both a single reconnecting magnetic separator and an observationally driven 3D model of a solar active region which contains several topological features of interest, including separators. We discuss how the test-particle orbits and the energy gain depend on the initial conditions, and how observations (for example, of solar flares) may be used to constrain model parameters.

  16. Accelerated mapping of magnetic susceptibility using 3D planes-on-a-paddlewheel (POP) EPI at ultra-high field strength.

    PubMed

    Stäb, Daniel; Bollmann, Steffen; Langkammer, Christian; Bredies, Kristian; Barth, Markus

    2017-04-01

    With the advent of ultra-high field MRI scanners in clinical research, susceptibility based MRI has recently gained increasing interest because of its potential to assess subtle tissue changes underlying neurological pathologies/disorders. Conventional, but rather slow, three-dimensional (3D) spoiled gradient-echo (GRE) sequences are typically employed to assess the susceptibility of tissue. 3D echo-planar imaging (EPI) represents a fast alternative but generally comes with echo-time restrictions, geometrical distortions and signal dropouts that can become severe at ultra-high fields. In this work we assess quantitative susceptibility mapping (QSM) at 7 T using non-Cartesian 3D EPI with a planes-on-a-paddlewheel (POP) trajectory, which is created by rotating a standard EPI readout train around its own phase encoding axis. We show that the threefold accelerated non-Cartesian 3D POP EPI sequence enables very fast, whole brain susceptibility mapping at an isotropic resolution of 1 mm and that the high image quality has sufficient signal-to-noise ratio in the phase data for reliable QSM processing. The susceptibility maps obtained were comparable with regard to QSM values and geometric distortions to those calculated from a conventional 4 min 3D GRE scan using the same QSM processing pipeline. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Impact of the Interplanetary Magnetic Field rotation from North to South on the Alfven Transition Layer: 3D Global PIC Simulation

    NASA Astrophysics Data System (ADS)

    Cai, DongSheng; Lembege, Bertrand; Nishikawa, Ken-ichi

    2017-04-01

    Using a global 3D PIC simulation, the solar-terrestrial magnetosphere interaction has been analyzed focusing on the 3D magnetic cusp region. Our recent global simulation results (Cai et al., JGR 2015) have reproduced the main features of the magnetic cusp under a northward IMF configuration comparing with the three-year statistical observations of Cluster satellites (Lavraud et al., JGR, 2005). One of the most important features found in our simulation is the existence of the Alfven Transition Layer (ATL) where Alfven Mach number is nearly zero almost adjacent to the upper stagnant exterior cusp (SEC). Its width measured near the SEC within the meridian plane varies from 1 to 4 Re. From the magnetosheath to SEC, the plasma flows transit from super to sub-Alfvenic regime. Striking features observed in the simulation is the unique depleted funnel shape ATL starting from the high altitude dusk to low altitude dawn above the magnetic cusp in a northward IMF. Both the ion and electron flux enter and spiral into the cups region through this depleted ATL with possibly a curvature drift. Varying IMF from north to south through dusk-dawn direction, this ATL persists although it drastically shrinks. Especially, in the southward IMF, the ion flux enters into the cusp region through the complicated ATL and bounce back to the magnetosheath. ATL can help us to investigate the complex structures of the magnetic cusp.

  18. 3D touchable holographic light-field display.

    PubMed

    Yamaguchi, Masahiro; Higashida, Ryo

    2016-01-20

    We propose a new type of 3D user interface: interaction with a light field reproduced by a 3D display. The 3D display used in this work reproduces a 3D light field, and a real image can be reproduced in midair between the display and the user. When using a finger to touch the real image, the light field from the display will scatter. Then, the 3D touch sensing is realized by detecting the scattered light by a color camera. In the experiment, the light-field display is constructed with a holographic screen and a projector; thus, a preliminary implementation of a 3D touch is demonstrated.

  19. Magnetic field sensor

    NASA Astrophysics Data System (ADS)

    Silva, Nicolas

    2012-09-01

    Earlier papers1-3 in this journal have described experiments on measuring the magnetic fields of current-carrying wires and permanent magnets using magnetic field probes of various kinds. This paper explains how to use an iPad and the free app MagnetMeter-3D Vector Magnetometer and Accelerometer4 (compass HD) to measure the magnetic fields.

  20. 3D magnetic sources' framework estimation using Genetic Algorithm (GA)

    NASA Astrophysics Data System (ADS)

    Ponte-Neto, C. F.; Barbosa, V. C.

    2008-05-01

    We present a method for inverting total-field anomaly for determining simple 3D magnetic sources' framework such as: batholiths, dikes, sills, geological contacts, kimberlite and lamproite pipes. We use GA to obtain magnetic sources' frameworks and their magnetic features simultaneously. Specifically, we estimate the magnetization direction (inclination and declination) and the total dipole moment intensity, and the horizontal and vertical positions, in Cartesian coordinates , of a finite set of elementary magnetic dipoles. The spatial distribution of these magnetic dipoles composes the skeletal outlines of the geologic sources. We assume that the geologic sources have a homogeneous magnetization distribution and, thus all dipoles have the same magnetization direction and dipole moment intensity. To implement the GA, we use real-valued encoding with crossover, mutation, and elitism. To obtain a unique and stable solution, we set upper and lower bounds on declination and inclination of [0,360°] and [-90°, 90°], respectively. We also set the criterion of minimum scattering of the dipole-position coordinates, to guarantee that spatial distribution of the dipoles (defining the source skeleton) be as close as possible to continuous distribution. To this end, we fix the upper and lower bounds of the dipole moment intensity and we evaluate the dipole-position estimates. If the dipole scattering is greater than a value expected by the interpreter, the upper bound of the dipole moment intensity is reduced by 10 % of the latter. We repeat this procedure until the dipole scattering and the data fitting are acceptable. We apply our method to noise-corrupted magnetic data from simulated 3D magnetic sources with simple geometries and located at different depths. In tests simulating sources such as sphere and cube, all estimates of the dipole coordinates are agreeing with center of mass of these sources. To elongated-prismatic sources in an arbitrary direction, we estimate

  1. MagicFinger: 3D Magnetic Fingerprints for Indoor Location

    PubMed Central

    Carrillo, Daniel; Moreno, Victoria; Úbeda, Benito; Skarmeta, Antonio F.

    2015-01-01

    Given the indispensable role of mobile phones in everyday life, phone-centric sensing systems are ideal candidates for ubiquitous observation purposes. This paper presents a novel approach for mobile phone-centric observation applied to indoor location. The approach involves a location fingerprinting methodology that takes advantage of the presence of magnetic field anomalies inside buildings. Unlike existing work on the subject, which uses the intensity of magnetic field for fingerprinting, our approach uses all three components of the measured magnetic field vectors to improve accuracy. By using adequate soft computing techniques, it is possible to adequately balance the constraints of common solutions. The resulting system does not rely on any infrastructure devices and therefore is easy to manage and deploy. The proposed system consists of two phases: the offline phase and the online phase. In the offline phase, magnetic field measurements are taken throughout the building, and 3D maps are generated. Then, during the online phase, the user's location is estimated through the best estimator for each zone of the building. Experimental evaluations carried out in two different buildings confirm the satisfactory performance of indoor location based on magnetic field vectors. These evaluations provided an error of (11.34 m, 4.78 m) in the (x, y) components of the estimated positions in the first building where the experiments were carried out, with a standard deviation of (3.41 m, 4.68 m); and in the second building, an error of (4 m, 2.98 m) with a deviation of (2.64 m, 2.33 m). PMID:26184230

  2. Observation of a 3D Magnetic Null Point

    NASA Astrophysics Data System (ADS)

    Romano, P.; Falco, M.; Guglielmino, S. L.; Murabito, M.

    2017-03-01

    We describe high-resolution observations of a GOES B-class flare characterized by a circular ribbon at the chromospheric level, corresponding to the network at the photospheric level. We interpret the flare as a consequence of a magnetic reconnection event that occurred at a three-dimensional (3D) coronal null point located above the supergranular cell. The potential field extrapolation of the photospheric magnetic field indicates that the circular chromospheric ribbon is cospatial with the fan footpoints, while the ribbons of the inner and outer spines look like compact kernels. We found new interesting observational aspects that need to be explained by models: (1) a loop corresponding to the outer spine became brighter a few minutes before the onset of the flare; (2) the circular ribbon was formed by several adjacent compact kernels characterized by a size of 1″–2″ (3) the kernels with a stronger intensity emission were located at the outer footpoint of the darker filaments, departing radially from the center of the supergranular cell; (4) these kernels started to brighten sequentially in clockwise direction; and (5) the site of the 3D null point and the shape of the outer spine were detected by RHESSI in the low-energy channel between 6.0 and 12.0 keV. Taking into account all these features and the length scales of the magnetic systems involved in the event, we argue that the low intensity of the flare may be ascribed to the low amount of magnetic flux and to its symmetric configuration.

  3. Validation of the Model for ELM Suppression with 3D Magnetic Fields Using Low Torque ITER Baseline Scenario Discharges in DIII-D

    NASA Astrophysics Data System (ADS)

    Moyer, R. A.

    2016-10-01

    Suppression of Edge Localized Modes (ELMs) is lost in ITER Baseline Scenario discharges when the torque Tinj and toroidal rotation νϕ are reduced. This is due to a shift in the tearing response deeper into the plasma. ELM suppression is recovered by reducing the normalized plasma pressure βN. In H-mode plasmas, edge turbulence is suppressed in a ``pedestal'' region, leading to large pressure gradients that trigger MHD instabilities (ELMs), causing rapid heat expulsion. 3D magnetic fields are used to drive resonances that limit the pedestal width preventing the ELM. Reducing Tinj changes the νϕ profile such that the drive shifts to a resonance deeper in the plasma, allowing the pedestal to grow again to MHD instability. Reducing βN reduces the edge pressure, which reduces the electron diamagnetic flow and moves the drive to a resonance that is closer to the boundary, recovering suppression. In two-fluid theory, the tearing response occurs at a resonant surface where the electron perpendicular rotation ω (⊥ e) 0 . Linear two-fluid resistive MHD simulations show that the tearing response shifts to a resonance deeper in the plasma when Tinj is reduced. The experimental results confirm that the tearing response occurs for a resonance where ω (⊥ e) 0 , and suggest that the transport which limits the pedestal width is linked to the tearing response, even if any islands are predicted to be small. Although this model describes the differences between ELMing and ELM suppressed H-modes, it doesn't address the transition from ELMs to suppression, because ω (⊥ e) 0 is initially too deep (ψN <= 0.9, q = 3) for the tearing response to limit the pedestal width. Although understanding this transition is important, ITER must apply the RMP in L-mode to avoid the first ELM. These results suggest that manipulation of the edge rotation profile will be important to optimize ELM suppression in future tokamaks. Supported by the US DOE under DE-FG02-07ER54917 and DE-FG02

  4. Chevrons, filaments, spinning clusters and phase coexistence: emergent dynamics of 2- and 3-d particle suspensions driven by multiaxial magnetic fields.

    PubMed

    Solis, Kyle J; Martin, James E

    2017-08-30

    In recent years a rich variety of emergent phenomena have been observed when suspensions of magnetic particles are subjected to alternating magnetic fields. These particle assemblies often exhibit vigorous dynamics due to the injection of energy from the field. These assemblies include surface and interface phenomena, such as highly organized, segmented "snakes" that can be induced to swim by structural symmetry breaking, and "asters" and "anti-asters," particle assemblies that can be manipulated to capture and transport cargo. In bulk suspensions of magnetic platelets subjected to multiaxial alternating fields, advection lattices and even vortex lattices have been created, and a variety of biomimetic dynamics - serpents, bees and amoebas - have been discovered in magnetic fluids suspended in an immiscible liquid. In this paper several new driven phases are presented, including flying chevrons, dense spinning clusters, filaments, and examples of phase coexistence in driven phases. These observations broaden the growing field of driven magnetic suspensions and present new challenges to those interested in simulating the dynamics of these complex systems.

  5. Light field display and 3D image reconstruction

    NASA Astrophysics Data System (ADS)

    Iwane, Toru

    2016-06-01

    Light field optics and its applications become rather popular in these days. With light field optics or light field thesis, real 3D space can be described in 2D plane as 4D data, which we call as light field data. This process can be divided in two procedures. First, real3D scene is optically reduced with imaging lens. Second, this optically reduced 3D image is encoded into light field data. In later procedure we can say that 3D information is encoded onto a plane as 2D data by lens array plate. This transformation is reversible and acquired light field data can be decoded again into 3D image with the arrayed lens plate. "Refocusing" (focusing image on your favorite point after taking a picture), light-field camera's most popular function, is some kind of sectioning process from encoded 3D data (light field data) to 2D image. In this paper at first I show our actual light field camera and our 3D display using acquired and computer-simulated light field data, on which real 3D image is reconstructed. In second I explain our data processing method whose arithmetic operation is performed not in Fourier domain but in real domain. Then our 3D display system is characterized by a few features; reconstructed image is of finer resolutions than density of arrayed lenses and it is not necessary to adjust lens array plate to flat display on which light field data is displayed.

  6. Free-Standing Magnetic Nanopillars for 3D Nanomagnet Logic

    PubMed Central

    2014-01-01

    Nanomagnet logic (NML) is a relatively new computation technology that uses arrays of shape-controlled nanomagnets to enable digital processing. Currently, conventional resist-based lithographic processes limit the design of NML circuitry to planar nanostructures with homogeneous thicknesses. Here, we demonstrate the focused electron beam induced deposition of Fe-based nanomaterial for magnetic in-plane nanowires and out-of-plane nanopillars. Three-dimensional (3D) NML was achieved based on the magnetic coupling between nanowires and nanopillars in a 3D array. Additionally, the same Fe-based nanomaterial was used to produce tilt-corrected high-aspect-ratio probes for the accurate magnetic force microscopy (MFM) analysis of the fabricated 3D NML gate arrays. The interpretation of the MFM measurements was supported by magnetic simulations using the Object Oriented MicroMagnetic Framework. Introducing vertical out-of-plane nanopillars not only increases the packing density of 3D NML but also introduces an extra magnetic degree of freedom, offering a new approach to input/output and processing functionalities in nanomagnetic computing. PMID:25296008

  7. Natural 3D content on glasses-free light-field 3D cinema

    NASA Astrophysics Data System (ADS)

    Balogh, Tibor; Nagy, Zsolt; Kovács, Péter Tamás.; Adhikarla, Vamsi K.

    2013-03-01

    This paper presents a complete framework for capturing, processing and displaying the free viewpoint video on a large scale immersive light-field display. We present a combined hardware-software solution to visualize free viewpoint 3D video on a cinema-sized screen. The new glasses-free 3D projection technology can support larger audience than the existing autostereoscopic displays. We introduce and describe our new display system including optical and mechanical design considerations, the capturing system and render cluster for producing the 3D content, and the various software modules driving the system. The indigenous display is first of its kind, equipped with front-projection light-field HoloVizio technology, controlling up to 63 MP. It has all the advantages of previous light-field displays and in addition, allows a more flexible arrangement with a larger screen size, matching cinema or meeting room geometries, yet simpler to set-up. The software system makes it possible to show 3D applications in real-time, besides the natural content captured from dense camera arrangements as well as from sparse cameras covering a wider baseline. Our software system on the GPU accelerated render cluster, can also visualize pre-recorded Multi-view Video plus Depth (MVD4) videos on this light-field glasses-free cinema system, interpolating and extrapolating missing views.

  8. The electric field induced in the brain by magnetic stimulation: a 3-D finite-element analysis of the effect of tissue heterogeneity and anisotropy.

    PubMed

    Miranda, Pedro C; Hallett, Mark; Basser, Peter J

    2003-09-01

    We investigate the effect of tissue heterogeneity and anisotropy on the electric field and current density distribution induced in the brain during magnetic stimulation. Validation of the finite-element (FE) calculations in a homogeneous isotropic sphere showed that the magnitude of the total electric field can be calculated to within an error of approximately 5% in the region of interest, even in the presence of a significant surface charge contribution. We used a high conductivity inclusion within a sphere of lower conductivity to simulate a lesion due to an infarct. Its effect is to increase the electric field induced in the surrounding low conductivity region. This boost is greatest in the vicinity of interfaces that lie perpendicular to the current flow. For physiological values of the conductivity distribution, it can reach a factor of 1.6 and extend many millimeters from the interface. We also show that anisotropy can significantly alter the electric field and current density distributions. Either heterogeneity or anisotropy can introduce a radial electric field component, not present in a homogeneous isotropic conductor. Heterogeneity and anisotropy are predicted to significantly affect the distribution of the electric field induced in the brain. It is, therefore, expected that anatomically faithful FE models of individual brains which incorporate conductivity tensor data derived from diffusion tensor measurements, will provide a better understanding of the location of possible stimulation sites in the brain.

  9. A Theoretical Study of the Build-up of the Sun’s Polar Magnetic Field by using a 3D Kinematic Dynamo Model

    NASA Astrophysics Data System (ADS)

    Hazra, Gopal; Choudhuri, Arnab Rai; Miesch, Mark S.

    2017-01-01

    We develop a three-dimensional kinematic self-sustaining model of the solar dynamo in which the poloidal field generation is from tilted bipolar sunspot pairs placed on the solar surface above regions of strong toroidal field by using the SpotMaker algorithm, and then the transport of this poloidal field to the tachocline is primarily caused by turbulent diffusion. We obtain a dipolar solution within a certain range of parameters. We use this model to study the build-up of the polar magnetic field and show that some insights obtained from surface flux transport models have to be revised. We present results obtained by putting a single bipolar sunspot pair in a hemisphere and two symmetrical sunspot pairs in two hemispheres. We find that the polar fields produced by them disappear due to the upward advection of poloidal flux at low latitudes, which emerges as oppositely signed radial flux and which is then advected poleward by the meridional flow. We also study the effect that a large sunspot pair, violating Hale’s polarity law, would have on the polar field. We find that there would be some effect—especially if the anti-Hale pair appears at high latitudes in the mid-phase of the cycle—though the effect is not very dramatic.

  10. Effects of H+, He+ ion reflection at the lunar surface and pickup ion dynamics in case of oblique/quasi-parallel magnetic field: 3-D hybrid kinetic modeling

    NASA Astrophysics Data System (ADS)

    Lipatov, A. S.; Cooper, J. F.; Sittler, E. C.; Hartle, R. E.; Sarantos, M.

    2013-12-01

    The hybrid kinetic model used here supports comprehensive simulation of the interaction between different spatial and energetic elements of the moon-solar wind-magnetosphere of the Earth system. This involves variable upstream magnetic field and solar wind plasma, including energetic ions, electrons, and neutral atoms. This capability is critical to improved interpretation of existing measurements for surface and atmospheric composition from previous missions and planning future missions. Recently, MAP-PAGE-IMA (Plasma energy Angle and Composition Experiment, and Ion Mass Analyzer) onboard Japanese lunar orbiter SELENE (KAGUYA) detected Moon originating ions at 100 km altitude. Ion species of H+, He++, He+, C+, O+, Na+, K+, and Ar+ were definitively identified. The first portion of our modeling devotes to a study of the H+, H2+, He+, Na+ pickup ion dynamics in cases of flow with a oblique and quasi-parallel magnetic field. In the second series of modeling we also take into account collisions between ions and the surface of the moon and further sputtering of fragments from the surface of the moon. The ion reflection at the lunar surface is also responsible for wave activity in the upstream flow. The solar wind parameters are chosen from ARTEMIS observations. The hybrid kinetic model allows us to take into account the finite gyroradius effects of pickup ions and to estimate correctly the ions velocity distribution and the fluxes along the magnetic field. Modeling shows the asymmetric Mach cone, pickup and reflected ion tails, and presents another type of lunar-solar wind interaction. Our simulation may be also important for the study of the interaction between the solar wind and very weak comets, Mercury and Pluto.

  11. Magnetic reconnection in 3D magnetosphere models: magnetic separators and open flux production

    NASA Astrophysics Data System (ADS)

    Glocer, A.; Dorelli, J.; Toth, G.; Komar, C. M.; Cassak, P.

    2014-12-01

    There are multiple competing definitions of magnetic reconnection in 3D (e.g., Hesse and Schindler [1988], Lau and Finn [1990], and Boozer [2002]). In this work we focus on separator reconnection. A magnetic separator can be understood as the 3D analogue of a 2D x line with a guide field, and is defined by the line corresponding to the intersection of the separatrix surfaces associated with the magnetic nulls. A separator in the magnetosphere represents the intersection of four distinct magnetic topologies: solar wind, closed, open connected to the northern hemisphere, and open connected to the southern hemisphere. The integral of the parallel electric field along the separator defines the rate of open flux production, and is one measure of the reconnection rate. We present three methods for locating magnetic separators and apply them to 3D resistive MHD simulations of the Earth's magnetosphere using the BATS-R-US code. The techniques for finding separators and determining the reconnection rate are insensitive to IMF clock angle and can in principle be applied to any magnetospheric model. The present work examines cases of high and low resistivity, for two clock angles. We also examine the separator during Flux Transfer Events (FTEs) and Kelvin-Helmholtz instability.

  12. Magnetism In 3d Transition Metals at High Pressures

    SciTech Connect

    Iota, V

    2006-02-09

    This research project examined the changes in electronic and magnetic properties of transition metals and oxides under applied pressures, focusing on complex relationship between magnetism and phase stability in these correlated electron systems. As part of this LDRD project, we developed new measurement techniques and adapted synchrotron-based electronic and magnetic measurements for use in the diamond anvil cell. We have performed state-of-the-art X-ray spectroscopy experiments at the dedicated high-pressure beamline HP-CAT (Sector 16 Advanced Photon Source, Argonne National Laboratory), maintained in collaboration with of University of Nevada, Las Vegas and Geophysical Laboratory of The Carnegie Institution of Washington. Using these advanced measurements, we determined the evolution of the magnetic order in the ferromagnetic 3d transition metals (Fe, Co and Ni) under pressure, and found that at high densities, 3d band broadening results in diminished long range magnetic coupling. Our experiments have allowed us to paint a unified picture of the effects of pressure on the evolution of magnetic spin in 3d electron systems. The technical and scientific advances made during this LDRD project have been reported at a number of scientific meetings and conferences, and have been submitted for publication in technical journals. Both the technical advances and the physical understanding of correlated systems derived from this LDRD are being applied to research on the 4f and 5f electron systems under pressure.

  13. Magnetic properties measurement of soft magnetic composite material (SOMALOY 700) by using 3-D tester

    NASA Astrophysics Data System (ADS)

    Asari, Ashraf; Guo, Youguang; Zhu, Jianguo

    2017-08-01

    Core losses of rotating electrical machine can be predicted by identifying the magnetic properties of the magnetic material. The magnetic properties should be properly measured since there are some variations of vector flux density in the rotating machine. In this paper, the SOMALOY 700 material has been measured under x, y and z- axes flux density penetration by using the 3-D tester. The calibrated sensing coils are used in detecting the flux densities which have been generated by the Labview software. The measured sensing voltages are used in obtaining the magnetic properties of the sample such as magnetic flux density B, magnetic field strength H, hysteresis loop which can be used to calculate the total core loss of the sample. The results of the measurement are analyzed by using the Mathcad software before being compared to another material.

  14. Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D

    NASA Astrophysics Data System (ADS)

    Moyer, R. A.; Paz-Soldan, C.; Nazikian, R.; Orlov, D. M.; Ferraro, N. M.; Grierson, B. A.; Knölker, M.; Lyons, B. C.; McKee, G. R.; Osborne, T. H.; Rhodes, T. L.; Meneghini, O.; Smith, S.; Evans, T. E.; Fenstermacher, M. E.; Groebner, R. J.; Hanson, J. M.; La Haye, R. J.; Luce, T. C.; Mordijck, S.; Solomon, W. M.; Turco, F.; Yan, Z.; Zeng, L.; DIII-D Team

    2017-10-01

    Experiments have been executed in the DIII-D tokamak to extend suppression of Edge Localized Modes (ELMs) with Resonant Magnetic Perturbations (RMPs) to ITER-relevant levels of beam torque. The results support the hypothesis for RMP ELM suppression based on transition from an ideal screened response to a tearing response at a resonant surface that prevents expansion of the pedestal to an unstable width [Snyder et al., Nucl. Fusion 51, 103016 (2011) and Wade et al., Nucl. Fusion 55, 023002 (2015)]. In ITER baseline plasmas with I/aB = 1.4 and pedestal ν* ˜ 0.15, ELMs are readily suppressed with co- Ip neutral beam injection. However, reducing the beam torque from 5 Nm to ≤ 3.5 Nm results in loss of ELM suppression and a shift in the zero-crossing of the electron perpendicular rotation ω⊥e ˜ 0 deeper into the plasma. The change in radius of ω⊥e ˜ 0 is due primarily to changes to the electron diamagnetic rotation frequency ωe*. Linear plasma response modeling with the resistive MHD code m3d-c1 indicates that the tearing response location tracks the inward shift in ω⊥e ˜ 0. At pedestal ν*˜ 1, ELM suppression is also lost when the beam torque is reduced, but the ω⊥e change is dominated by collapse of the toroidal rotation vT. The hypothesis predicts that it should be possible to obtain ELM suppression at reduced beam torque by also reducing the height and width of the ωe* profile. This prediction has been confirmed experimentally with RMP ELM suppression at 0 Nm of beam torque and plasma normalized pressure βN ˜ 0.7. This opens the possibility of accessing ELM suppression in low torque ITER baseline plasmas by establishing suppression at low beta and then increasing beta while relying on the strong RMP-island coupling to maintain suppression.

  15. 3-D, Impulsive Magnetic Reconnection in a Laboratory Plasma (Invited)

    NASA Astrophysics Data System (ADS)

    Dorfman, S. E.; Ji, H.; Yamada, M.; Yoo, J.; Myers, C. E.; Roytershteyn, V.; Daughton, W. S.; Jara-Almonte, J.

    2013-12-01

    Magnetic reconnection is a fundamental plasma process involving the efficient conversion of magnetic field energy to plasma kinetic energy through changing field line topology. In many space and astrophysical systems, including the solar surface and the Earth's magnetotail, reconnection is not only fast, but also impulsive; in other words, a slow buildup phase is followed by a comparatively quick release of magnetic energy. An important question in the literature is if these examples of impulsive reconnection can be described by a two-dimensional model with no variation in the out-of-plane direction or if impulsive reconnection is fundamentally three-dimensional. Events observed on the Magnetic Reconnection Experiment (MRX) are characterized by large local gradients in the third direction and cannot be explained by 2-D models [1]. Detailed measurements show that the ejection of flux rope structures from the current sheet plays a key role in these events. By contrast, even though electromagnetic fluctuations in the lower hybrid frequency range are also observed concurrently with the impulsive behavior, they are not the key physics responsible. Furthermore, an important discrepancy in the layer width and force balance between the collisionless regime of MRX and kinetic simulations [2-4] persists when the fluctuations are small or absent, implying that they are not the cause of the wider electron layers observed in the experiment [5]. These wider layers may instead be due to the formation of flux ropes with a wide range of sizes; consistent with this hypothesis, flux rope signatures are observed down to the smallest scales resolved by the diagnostics. Finally, a qualitative, 3-D, two-fluid model is proposed to explain the observed disruptions. Many of the features observed in MRX including current disruptions [6], flux ropes [7], and electromagnetic fluctuations [8] have analogues in space observations. Thus, further detailed comparisons may enhance our understanding

  16. 3D Magnetic inversion and remanence: solving the problem

    NASA Astrophysics Data System (ADS)

    Thomson, V.; Morris, W.

    2003-04-01

    3D inversion of surface magnetic data is a common processing technique when used in mineral exploration. The major drawback of most 3D inversion algorithms is that they assume that the surface magnetic anomaly is produced by induced magnetization and that there are no remanent magnetization or demagnetization effects present. This has a significant impact when modeling magnetic data that has remanent magnetization. The magnetic anomaly produced by a dipping subsurface body will be identical for a consistent relationship between the dip of the body and the dip of the magnetic vector, regardless of the actual dip of the magnetic body. For example, in the case where a subsurface body is dipping, such as a dipping dike, the dip estimated by the inversion routine will be correct only if induced magnetization is present. This has serious implications for mineral exploration. A solution to the remanence problem is to model the surface magnetic anomaly using a constrained 2D approach rather than 3D. Using a priori information on dip and strike length of a source body, it is possible to approximate the remanence direction and intensity. The 2D solutions can then be rendered into a 3D imaging package to create a model in 3D. A case study was performed on a mafic-ultramafic layered igneous intrusion located in Big Trout Lake, northwestern Ontario, Canada. Large layered igneous intrusions are known to have significant remanence. Like many other layered igneous intrusions such as the Bushveld Complex in South Africa, the Big Trout Lake Complex is highly prospective for Platinum Group Elements (PGEs). Intruded during Archean time, the Big Trout Lake Complex has been subsequently folded and faulted to near vertical. As a consequence of limited surface exposures, knowledge of layering within the pluton and the extent of deformation of the pluton is very limited. Newly acquired high-resolution aeromagnetic data shows a strongly mineralized horizon within the intrusion that

  17. 3-D Display Of Magnetic Resonance Imaging Of The Spine

    NASA Astrophysics Data System (ADS)

    Nelson, Alan C.; Kim, Yongmin; Haralick, Robert M.; Anderson, Paul A.; Johnson, Roger H.; DeSoto, Larry A.

    1988-06-01

    The original data is produced through standard magnetic resonance imaging (MRI) procedures with a surface coil applied to the lower back of a normal human subject. The 3-D spine image data consists of twenty-six contiguous slices with 256 x 256 pixels per slice. Two methods for visualization of the 3-D spine are explored. One method utilizes a verifocal mirror system which creates a true 3-D virtual picture of the object. Another method uses a standard high resolution monitor to simultaneously show the three orthogonal sections which intersect at any user-selected point within the object volume. We discuss the application of these systems in assessment of low back pain.

  18. Single cell detection using 3D magnetic rolled-up structures.

    PubMed

    Ger, Tzong-Rong; Huang, Hao-Ting; Huang, Chen-Yu; Lai, Mei-Feng

    2013-11-07

    A 3D rolled-up structure made of a SiO2 layer and a fishbone-like magnetic thin film was proposed here as a biosensor. The magnetoresistance (MR) measurement results of the sensor suggest that the presence of the stray field, which is induced by the magnetic nanoparticles, significantly increased the switching field. Comparing the performance of the 2D sensor and 3D sensor designed in this study, the response in switching field variation was 12.14% in the 2D sensor and 62.55% in the 3D sensor. The response in MR ratio variation was 4.55% in the 2D sensor and 82.32% in the 3D sensor. In addition, the design of the 3D sensor structure also helped to attract and trap a single magnetic cell due to its stronger stray field compared with the 2D structure. The 3D magnetic biosensor designed here can provide important information for future biochip research and applications.

  19. Contiguous 3 d and 4 f Magnetism: Strongly Correlated 3 d Electrons in YbFe2Al10

    NASA Astrophysics Data System (ADS)

    Khuntia, P.; Peratheepan, P.; Strydom, A. M.; Utsumi, Y.; Ko, K.-T.; Tsuei, K.-D.; Tjeng, L. H.; Steglich, F.; Baenitz, M.

    2014-11-01

    We present magnetization, specific heat, and Al 27 NMR investigations on YbFe2Al10 over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a ln (T0/T ) divergence of the low-T specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard-x-ray photoemission spectroscopy study, the Yb valence at 50 K is evaluated to be 2.38. The system displays valence fluctuating behavior in the low to intermediate temperature range, whereas above 400 K, Yb3 + carries a full and stable moment, and Fe carries a moment of about 3.1 μB. The enhanced value of the Sommerfeld-Wilson ratio and the dynamic scaling of the spin-lattice relaxation rate divided by T [(1 /T1T ) 27 ] with static susceptibility suggests admixed ferromagnetic correlations. (1 /T1T ) 27 simultaneously tracks the valence fluctuations from the 4 f Yb ions in the high temperature range and field dependent antiferromagnetic correlations among partially Kondo screened Fe 3 d moments at low temperature; the latter evolve out of an Yb 4 f admixed conduction band.

  20. Magnetism in a graphene-4 f -3 d hybrid system

    NASA Astrophysics Data System (ADS)

    Huttmann, Felix; Klar, David; Atodiresei, Nicolae; Schmitz-Antoniak, Carolin; Smekhova, Alevtina; Martínez-Galera, Antonio J.; Caciuc, Vasile; Bihlmayer, Gustav; Blügel, Stefan; Michely, Thomas; Wende, Heiko

    2017-02-01

    We create an interface of graphene with a metallic and magnetic support that leaves its electronic structure largely intact. This is achieved by exposing epitaxial graphene on ferromagnetic thin films of Co and Ni to vapor of the rare earth metal Eu at elevated temperatures, resulting in the intercalation of an Eu monolayer in between graphene and its substrate. The system is atomically well defined, with the Eu monolayer forming a (√{3 }×√{3 }) R 30∘ superstructure with respect to the graphene lattice. Thereby, we avoid the strong hybridization with the (Ni,Co) substrate 3 d states that otherwise drastically modify the electronic structure of graphene. This picture is suggested by our x-ray absorption spectroscopy measurements which show that after Eu intercalation the empty 2 p states of C atoms resemble more the ones measured for graphite in contrast to graphene directly bound to 3 d ferromagnetic substrates. We use x-ray magnetic circular dichroism at the Co and Ni L2 ,3 and Eu M4 ,5 as an element-specific probe to investigate magnetism in these systems. An antiferromagnetic coupling between Eu and Co/Ni moments is found, which is so strong that a magnetic moment of the Eu layer can be detected at room temperature. Density functional theory calculations confirm the antiferromagnetic coupling and provide an atomic insight into the magnetic coupling mechanism.

  1. Imaging 3D strain field monitoring during hydraulic fracturing processes

    NASA Astrophysics Data System (ADS)

    Chen, Rongzhang; Zaghloul, Mohamed A. S.; Yan, Aidong; Li, Shuo; Lu, Guanyi; Ames, Brandon C.; Zolfaghari, Navid; Bunger, Andrew P.; Li, Ming-Jun; Chen, Kevin P.

    2016-05-01

    In this paper, we present a distributed fiber optic sensing scheme to study 3D strain fields inside concrete cubes during hydraulic fracturing process. Optical fibers embedded in concrete were used to monitor 3D strain field build-up with external hydraulic pressures. High spatial resolution strain fields were interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry. The fiber optics sensor scheme presented in this paper provides scientists and engineers a unique laboratory tool to understand the hydraulic fracturing processes in various rock formations and its impacts to environments.

  2. 3D printing of intracranial artery stenosis based on the source images of magnetic resonance angiograph.

    PubMed

    Xu, Wei-Hai; Liu, Jia; Li, Ming-Li; Sun, Zhao-Yong; Chen, Jie; Wu, Jian-Huang

    2014-08-01

    Three dimensional (3D) printing techniques for brain diseases have not been widely studied. We attempted to 'print' the segments of intracranial arteries based on magnetic resonance imaging. Three dimensional magnetic resonance angiography (MRA) was performed on two patients with middle cerebral artery (MCA) stenosis. Using scale-adaptive vascular modeling, 3D vascular models were constructed from the MRA source images. The magnified (ten times) regions of interest (ROI) of the stenotic segments were selected and fabricated by a 3D printer with a resolution of 30 µm. A survey to 8 clinicians was performed to evaluate the accuracy of 3D printing results as compared with MRA findings (4 grades, grade 1: consistent with MRA and provide additional visual information; grade 2: consistent with MRA; grade 3: not consistent with MRA; grade 4: not consistent with MRA and provide probable misleading information). If a 3D printing vessel segment was ideally matched to the MRA findings (grade 2 or 1), a successful 3D printing was defined. Seven responders marked "grade 1" to 3D printing results, while one marked "grade 4". Therefore, 87.5% of the clinicians considered the 3D printing were successful. Our pilot study confirms the feasibility of using 3D printing technique in the research field of intracranial artery diseases. Further investigations are warranted to optimize this technique and translate it into clinical practice.

  3. 3D quantum gravity and effective noncommutative quantum field theory.

    PubMed

    Freidel, Laurent; Livine, Etera R

    2006-06-09

    We show that the effective dynamics of matter fields coupled to 3D quantum gravity is described after integration over the gravitational degrees of freedom by a braided noncommutative quantum field theory symmetric under a kappa deformation of the Poincaré group.

  4. Contactless steering of a plasma jet with a 3D magnetic nozzle

    NASA Astrophysics Data System (ADS)

    Merino, Mario; Ahedo, Eduardo

    2017-09-01

    A 3D, steerable magnetic nozzle (MN) is presented that enables contactless thrust vector control of a plasma jet without any moving parts. The concept represents a substantial simplification over current plasma thruster gimbaled platforms, and requires only a small modification in thrusters that already have a MN. The characteristics of the plasma expansion in the 3D magnetic field and the deflection performance of the device are characterized with a fully magnetized plasma model, suggesting that thrust deflections of 5° -10° are readily achievable.

  5. Advances toward field application of 3D hydraulic tomography

    NASA Astrophysics Data System (ADS)

    Cardiff, M. A.; Barrash, W.; Kitanidis, P. K.

    2011-12-01

    Hydraulic tomography (HT) is a technique that shows great potential for aquifer characterization and one that holds the promise of producing 3D hydraulic property distributions, given suitable equipment. First suggested over 15 years ago, HT assimilates distributed aquifer pressure (head) response data collected during a series of multiple pumping tests to produce estimates of aquifer property variability. Unlike traditional curve-matching analyses, which assume homogeneity or "effective" parameters within the radius of influence of a hydrologic test, HT analysis relies on numerical models with detailed heterogeneity in order to invert for the highly resolved 3D parameter distribution that jointly fits all data. Several numerical and laboratory investigations of characterization using HT have shown that property distributions can be accurately estimated between observation locations when experiments are correctly designed - a property not always shared by other, simpler 1D characterization approaches such as partially-penetrating slug tests. HT may represent one of the best methods available for obtaining detailed 3D aquifer property descriptions, especially in deep or "hard" aquifer materials, where direct-push methods may not be feasible. However, to date HT has not yet been widely adopted at contaminated field sites. We believe that current perceived impediments to HT adoption center around four key issues: 1) A paucity in the scientific literature of proven, cross-validated 3D field applications 2) A lack of guidelines and best practices for performing field 3D HT experiments; 3) Practical difficulty and time commitment associated with the installation of a large number of high-accuracy sampling locations, and the running of a large number of pumping tests; and 4) Computational difficulty associated with solving large-scale inverse problems for parameter identification. In this talk, we present current results in 3D HT research that addresses these four issues

  6. Supramolecular 3d-4f single-molecule magnet architectures.

    PubMed

    Schmitz, Sebastian; van Leusen, Jan; Izarova, Natalya V; Lan, Yanhua; Wernsdorfer, Wolfgang; Kögerler, Paul; Monakhov, Kirill Yu

    2016-10-18

    The nanosized self-assemblies {[{Ln(III)}{H2O⊂CrLn}]2(H2O)} (Ln = Dy, 1 and Tb, 2) based on new 3d-4f mixed-metal coordination topologies are formed via extensive intramolecular hydrogen bonding that is directed by enclosed water molecules. Compounds 1 and 2 show single-molecule magnet characteristics manifested by hysteresis loops up to 1.6 K (Ueff = 8.3 cm(-1)) and 1 K (Ueff = 3.4 cm(-1)), respectively.

  7. Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D

    DOE PAGES

    Moyer, Richard A.; Paz-Soldan, Carlos; Nazikian, Raffi; ...

    2017-09-18

    Here, experiments have been executed in the DIII-D tokamak to extend suppression of Edge Localized Modes (ELMs) with Resonant Magnetic Perturbations (RMPs) to ITER-relevant levels of beam torque. The results support the hypothesis for RMP ELM suppression based on transition from an ideal screened response to a tearing response at a resonant surface that prevents expansion of the pedestal to an unstable width.

  8. Magnetically Defined Qubits on 3D Topological Insulators

    NASA Astrophysics Data System (ADS)

    Ferreira, Gerson J.; Loss, Daniel

    2013-09-01

    We explore potentials that break time-reversal symmetry to confine the surface states of 3D topological insulators into quantum wires and quantum dots. A magnetic domain wall on a ferromagnet insulator cap layer provides interfacial states predicted to show the quantum anomalous Hall effect (QAHE). Here, we show that confinement can also occur at magnetic domain heterostructures, with states extended in the inner domain, as well as interfacial QAHE states at the surrounding domain walls. The proposed geometry allows the isolation of the wire and dot from spurious circumventing surface states. For the quantum dots, we find that highly spin-polarized quantized QAHE states at the dot edge constitute a promising candidate for quantum computing qubits.

  9. Bifurcation to 3D helical magnetic equilibrium in an axisymmetric toroidal device.

    PubMed

    Bergerson, W F; Auriemma, F; Chapman, B E; Ding, W X; Zanca, P; Brower, D L; Innocente, P; Lin, L; Lorenzini, R; Martines, E; Momo, B; Sarff, J S; Terranova, D

    2011-12-16

    We report the first direct measurement of the internal magnetic field structure associated with a 3D helical equilibrium generated spontaneously in the core of an axisymmetric toroidal plasma containment device. Magnetohydrodynamic equilibrium bifurcation occurs in a reversed-field pinch when the innermost resonant magnetic perturbation grows to a large amplitude, reaching up to 8% of the mean field strength. Magnetic topology evolution is determined by measuring the Faraday effect, revealing that, as the perturbation grows, toroidal symmetry is broken and a helical equilibrium is established. © 2011 American Physical Society

  10. Magnetically Defined Qubits on 3D Topological Insulators

    NASA Astrophysics Data System (ADS)

    Ferreira, Gerson J.; Loss, Daniel

    2014-03-01

    We explore potentials that break time-reversal symmetry to confine the surface states of 3D topological insulators into quantum wires and quantum dots. A magnetic domain wall on a ferromagnet insulator cap layer provides interfacial states predicted to show the quantum anomalous Hall effect. Here, we show that confinement can also occur at magnetic domain heterostructures, with states extended in the inner domain, as well as interfacial QAHE states at the surrounding domain walls. The proposed geometry allows the isolation of the wire and dot from spurious circumventing surface states. For the quantum dots, we find that highly spin-polarized quantized QAHE states at the dot edge constitute a promising candidate for quantum computing qubits. See [Ferreira and Loss, Phys. Rev. Lett. 111, 106802 (2013)]. We explore potentials that break time-reversal symmetry to confine the surface states of 3D topological insulators into quantum wires and quantum dots. A magnetic domain wall on a ferromagnet insulator cap layer provides interfacial states predicted to show the quantum anomalous Hall effect. Here, we show that confinement can also occur at magnetic domain heterostructures, with states extended in the inner domain, as well as interfacial QAHE states at the surrounding domain walls. The proposed geometry allows the isolation of the wire and dot from spurious circumventing surface states. For the quantum dots, we find that highly spin-polarized quantized QAHE states at the dot edge constitute a promising candidate for quantum computing qubits. See [Ferreira and Loss, Phys. Rev. Lett. 111, 106802 (2013)]. We acknowledge support from the Swiss NSF, NCCR Nanoscience, NCCR QSIT, and the Brazillian Research Support Center Initiative (NAP Q-NANO) from Pró-Reitoria de Pesquisa (PRP/USP).

  11. Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data

    NASA Astrophysics Data System (ADS)

    Strait, E. J.; King, J. D.; Hanson, J. M.; Logan, N. C.

    2016-11-01

    An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric "3D" features of tokamak plasmas, with typical amplitudes ˜10-3 to 10-5 of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.

  12. Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data.

    PubMed

    Strait, E J; King, J D; Hanson, J M; Logan, N C

    2016-11-01

    An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric "3D" features of tokamak plasmas, with typical amplitudes ∼10(-3) to 10(-5) of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.

  13. Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data

    SciTech Connect

    Strait, E. J.; King, J. D.; Hanson, J. M.; Logan, N. C.

    2016-08-11

    An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric "3D" features of tokamak plasmas, with typical amplitudes ~10-3 to 10-5 of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Lastly, applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.

  14. Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data

    SciTech Connect

    Strait, E. J.; King, J. D.; Hanson, J. M.; Logan, N. C.

    2016-08-11

    An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric "3D" features of tokamak plasmas, with typical amplitudes ~10-3 to 10-5 of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Lastly, applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.

  15. Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data

    DOE PAGES

    Strait, E. J.; King, J. D.; Hanson, J. M.; ...

    2016-08-11

    An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric "3D" features of tokamak plasmas, with typical amplitudes ~10-3 to 10-5 of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Lastly, applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.

  16. Magnetic fields dispersed by high-voltage power lines: an advanced evaluation method based on 3-D models of electrical lines and the territory.

    PubMed

    Andreuccetti, D; Zoppetti, N

    2004-01-01

    An advanced numerical evaluation tool is proposed for calculating the magnetic flux density dispersed by high-voltage power lines. When compared to existing software packages based on the application of standardized methods, this tool turned out to be particularly suitable for making accurate evaluations on vast portions of the territory, especially when the contribution of numerous aerial and/or underground lines must be taken into account. The aspects of the tool of greatest interest are (1) the interaction with an electronic archive of power lines, from which all the information necessary for the calculation is obtained; (2) the use of three-dimensional models of both the power lines and the territory crossed by these; (3) the direct interfacing with electronic cartography; and finally (4) the use of a representation procedure for the results that is based on contour maps. The tool had proven to be very useful especially for Environmental Impact Assessment procedures relative to new power lines.

  17. 3D temperature field reconstruction using ultrasound sensing system

    NASA Astrophysics Data System (ADS)

    Liu, Yuqian; Ma, Tong; Cao, Chengyu; Wang, Xingwei

    2016-04-01

    3D temperature field reconstruction is of practical interest to the power, transportation and aviation industries and it also opens up opportunities for real time control or optimization of high temperature fluid or combustion process. In our paper, a new distributed optical fiber sensing system consisting of a series of elements will be used to generate and receive acoustic signals. This system is the first active temperature field sensing system that features the advantages of the optical fiber sensors (distributed sensing capability) and the acoustic sensors (non-contact measurement). Signals along multiple paths will be measured simultaneously enabled by a code division multiple access (CDMA) technique. Then a proposed Gaussian Radial Basis Functions (GRBF)-based approach can approximate the temperature field as a finite summation of space-dependent basis functions and time-dependent coefficients. The travel time of the acoustic signals depends on the temperature of the media. On this basis, the Gaussian functions are integrated along a number of paths which are determined by the number and distribution of sensors. The inversion problem to estimate the unknown parameters of the Gaussian functions can be solved with the measured times-of-flight (ToF) of acoustic waves and the length of propagation paths using the recursive least square method (RLS). The simulation results show an approximation error less than 2% in 2D and 5% in 3D respectively. It demonstrates the availability and efficiency of our proposed 3D temperature field reconstruction mechanism.

  18. Nonthermal Particle Acceleration in 3D Relativistic Magnetic Reconnection in Pair Plasma

    NASA Astrophysics Data System (ADS)

    Werner, Gregory R.; Uzdensky, Dmitri A.

    2017-07-01

    As a fundamental process converting magnetic to plasma energy in high-energy astrophysical plasmas, relativistic magnetic reconnection is a leading explanation for the acceleration of particles to the ultrarelativistic energies that are necessary to power nonthermal emission (especially X-rays and gamma-rays) in pulsar magnetospheres and pulsar wind nebulae, coronae and jets of accreting black holes, and gamma-ray bursts. An important objective of plasma astrophysics is therefore the characterization of nonthermal particle acceleration (NTPA) effected by reconnection. Reconnection-powered NTPA has been demonstrated over a wide range of physical conditions using large 2D kinetic simulations. However, its robustness in realistic 3D reconnection—in particular, whether the 3D relativistic drift-kink instability (RDKI) disrupts NTPA—has not been systematically investigated, although pioneering 3D simulations have observed NTPA in isolated cases. Here, we present the first comprehensive study of NTPA in 3D relativistic reconnection in collisionless electron-positron plasmas, characterizing NTPA as the strength of 3D effects is varied systematically via the length in the third dimension and the strength of the guide magnetic field. We find that, while the RDKI prominently perturbs 3D reconnecting current sheets, it does not suppress particle acceleration, even for zero guide field; fully 3D reconnection robustly and efficiently produces nonthermal power-law particle spectra closely resembling those obtained in 2D. This finding provides strong support for reconnection as the key mechanism powering high-energy flares in various astrophysical systems. We also show that strong guide fields significantly inhibit NTPA, slowing reconnection and limiting the energy available for plasma energization, yielding steeper and shorter power-law spectra.

  19. Advancing the field of 3D biomaterial printing.

    PubMed

    Jakus, Adam E; Rutz, Alexandra L; Shah, Ramille N

    2016-01-11

    3D biomaterial printing has emerged as a potentially revolutionary technology, promising to transform both research and medical therapeutics. Although there has been recent progress in the field, on-demand fabrication of functional and transplantable tissues and organs is still a distant reality. To advance to this point, there are two major technical challenges that must be overcome. The first is expanding upon the limited variety of available 3D printable biomaterials (biomaterial inks), which currently do not adequately represent the physical, chemical, and biological complexity and diversity of tissues and organs within the human body. Newly developed biomaterial inks and the resulting 3D printed constructs must meet numerous interdependent requirements, including those that lead to optimal printing, structural, and biological outcomes. The second challenge is developing and implementing comprehensive biomaterial ink and printed structure characterization combined with in vitro and in vivo tissue- and organ-specific evaluation. This perspective outlines considerations for addressing these technical hurdles that, once overcome, will facilitate rapid advancement of 3D biomaterial printing as an indispensable tool for both investigating complex tissue and organ morphogenesis and for developing functional devices for a variety of diagnostic and regenerative medicine applications.

  20. Designing bioinspired composite reinforcement architectures via 3D magnetic printing

    PubMed Central

    Martin, Joshua J.; Fiore, Brad E.; Erb, Randall M.

    2015-01-01

    Discontinuous fibre composites represent a class of materials that are strong, lightweight and have remarkable fracture toughness. These advantages partially explain the abundance and variety of discontinuous fibre composites that have evolved in the natural world. Many natural structures out-perform the conventional synthetic counterparts due, in part, to the more elaborate reinforcement architectures that occur in natural composites. Here we present an additive manufacturing approach that combines real-time colloidal assembly with existing additive manufacturing technologies to create highly programmable discontinuous fibre composites. This technology, termed as ‘3D magnetic printing', has enabled us to recreate complex bioinspired reinforcement architectures that deliver enhanced material performance compared with monolithic structures. Further, we demonstrate that we can now design and evolve elaborate reinforcement architectures that are not found in nature, demonstrating a high level of possible customization in discontinuous fibre composites with arbitrary geometries. PMID:26494282

  1. Designing bioinspired composite reinforcement architectures via 3D magnetic printing

    NASA Astrophysics Data System (ADS)

    Martin, Joshua J.; Fiore, Brad E.; Erb, Randall M.

    2015-10-01

    Discontinuous fibre composites represent a class of materials that are strong, lightweight and have remarkable fracture toughness. These advantages partially explain the abundance and variety of discontinuous fibre composites that have evolved in the natural world. Many natural structures out-perform the conventional synthetic counterparts due, in part, to the more elaborate reinforcement architectures that occur in natural composites. Here we present an additive manufacturing approach that combines real-time colloidal assembly with existing additive manufacturing technologies to create highly programmable discontinuous fibre composites. This technology, termed as `3D magnetic printing', has enabled us to recreate complex bioinspired reinforcement architectures that deliver enhanced material performance compared with monolithic structures. Further, we demonstrate that we can now design and evolve elaborate reinforcement architectures that are not found in nature, demonstrating a high level of possible customization in discontinuous fibre composites with arbitrary geometries.

  2. Unsupervised fuzzy segmentation of 3D magnetic resonance brain images

    NASA Astrophysics Data System (ADS)

    Velthuizen, Robert P.; Hall, Lawrence O.; Clarke, Laurence P.; Bensaid, Amine M.; Arrington, J. A.; Silbiger, Martin L.

    1993-07-01

    Unsupervised fuzzy methods are proposed for segmentation of 3D Magnetic Resonance images of the brain. Fuzzy c-means (FCM) has shown promising results for segmentation of single slices. FCM has been investigated for volume segmentations, both by combining results of single slices and by segmenting the full volume. Different strategies and initializations have been tried. In particular, two approaches have been used: (1) a method by which, iteratively, the furthest sample is split off to form a new cluster center, and (2) the traditional FCM in which the membership grade matrix is initialized in some way. Results have been compared with volume segmentations by k-means and with two supervised methods, k-nearest neighbors and region growing. Results of individual segmentations are presented as well as comparisons on the application of the different methods to a number of tumor patient data sets.

  3. 3D Geological Model of Nihe ore deposit Constrained by Gravity and Magnetic Modeling

    NASA Astrophysics Data System (ADS)

    Qi, Guang; Yan, Jiayong; Lv, Qingtan; Zhao, Jinhua

    2016-04-01

    We present a case study on using integrated geologic model in mineral exploration at depth. Nihe ore deposit in Anhui Province, is deep hidden ore deposit which was discovered in recent years, this finding is the major driving force of deep mineral exploration work in Luzong. Building 3D elaborate geological model has the important significance for prospecting to deep or surround in this area, and can help us better understand the metallogenic law and ore-controlling regularity. A 3D geological model, extending a depth from +200m to -1500m in Nihe ore deposit, has been compiled from surface geological map, cross-section, borehole logs and amounts of geological inference. And then the 3D geological models have been given physical property parameter for calculating the potential field. Modelling the potential response is proposed as means of evaluating the viability of the 3D geological models, and the evidence of making small changes to the uncertain parts of the original 3D geological models. It is expected that the final models not only reproduce supplied prior geological knowledge, but also explain the observed geophysical data. The workflow used to develop the 3D geologic model in this study includes the three major steps, as follows: (1) Determine the basic information of Model: Defining the 3D limits of the model area, the basic geological and structural unit, and the tectonic contact relations and the sedimentary sequences between these units. (2) 3D model construction: Firstly, a series of 2D geological cross sections over the model area are built by using all kinds of prior information, including surface geology, borehole data, seismic sections, and local geologists' knowledge and intuition. Lastly, we put these sections into a 3D environment according to their profile locations to build a 3D model by using geostatistics method. (3) 3D gravity and magnetic modeling: we calculate the potential field responses of the 3D model, and compare the predicted and

  4. 3D fibre deposition and stereolithography techniques for the design of multifunctional nanocomposite magnetic scaffolds.

    PubMed

    De Santis, Roberto; D'Amora, Ugo; Russo, Teresa; Ronca, Alfredo; Gloria, Antonio; Ambrosio, Luigi

    2015-10-01

    Magnetic nanocomposite scaffolds based on poly(ε-caprolactone) and poly(ethylene glycol) were fabricated by 3D fibre deposition modelling (FDM) and stereolithography techniques. In addition, hybrid coaxial and bilayer magnetic scaffolds were produced by combining such techniques. The aim of the current research was to analyse some structural and functional features of 3D magnetic scaffolds obtained by the 3D fibre deposition technique and by stereolithography as well as features of multimaterial scaffolds in the form of coaxial and bilayer structures obtained by the proper integration of such methods. The compressive mechanical behaviour of these scaffolds was investigated in a wet environment at 37 °C, and the morphological features were analysed through scanning electron microscopy (SEM) and X-ray micro-computed tomography. The capability of a magnetic scaffold to absorb magnetic nanoparticles (MNPs) in water solution was also assessed. confocal laser scanning microscopy was used to assess the in vitro biological behaviour of human mesenchymal stem cells (hMSCs) seeded on 3D structures. Results showed that a wide range of mechanical properties, covering those spanning hard and soft tissues, can be obtained by 3D FDM and stereolithography techniques. 3D virtual reconstruction and SEM showed the precision with which the scaffolds were fabricated, and a good-quality interface between poly(ε-caprolactone) and poly(ethylene glycol) based scaffolds was observed for bilayer and coaxial scaffolds. Magnetised scaffolds are capable of absorbing water solution of MNPs, and a preliminary information on cell adhesion and spreading of hMSCs was obtained without the application of an external magnetic field.

  5. 3-D UAV magnetic gradiometery survey for chromite exploration using an alkali vapor magnetometer

    NASA Astrophysics Data System (ADS)

    Braun, A.; Parvar, K.; Walter, C. A.; Burns, M.

    2016-12-01

    Unmanned Aerial Vehicles (UAV) are capable of carrying a wide range of sensors and thus become available for a variety of new applications which can exploit the new platform capabilities. This study exploits a multi-rotor UAV equipped with a high-sensitivity magnetometer to explore for Chromite deposits in Oman. Having 3-D magnetic data around an ore body allows for improved detection and estimation of ore body geometry compared to a 2-D survey. This is one of the main advantages of using multi-rotor UAVs. The autonomous UAV-Magnetometer system which was used in this research consists of a GEM Systems GSMP-35A magnetometer which is mounted on a Pioneer Exploration UAV-MAG™ platform. Surveys were conducted at different elevations in order to acquire a full 3-D dataset of the total magnetic field. Knowing that the chromite in the study area is associated with a significant amount of Hematite and Magnetite made magnetic gradiometry the first choice as an exploration method. Processing the measured values lead to a 3-D voxel cube of the magnetic field components including gradients. Specifically, the vertical gradient was measured directly from the 3-D observations at different elevations. Compared to the vertical gradient estimated from a 2-D survey plane alone, having access to 3-D data allowed for new discoveries of deposits not detectable from a 2-D survey alone. The 3-D field created by the susceptible chromite body shows a strong anomaly and the measured vertical derivative indicates details about location and geometry. The findings were confirmed by resistivity surveys over the area and by noticeable overlap with known chromite outcrops.

  6. 3D measuring in the field of endoscopy

    NASA Astrophysics Data System (ADS)

    Schick, Anton; Forster, Frank; Stockmann, Michael

    2011-05-01

    Industrial optical 3D-measurement techniques are well established to achieve quality targets in production and manufacturing. However measurements inside of objects, especially small ones, are still a challenge since there is no easy access for measurement tools. Inspection tools like endoscopes, which provide a 2D-view or a stereoscopic view of inner surfaces, are commercially available and widely used. Nevertheless, there is no technique for precisely measuring the inner surface geometry of a small hollow object. Especially medical applications would greatly benefit from "dimensional" measuring. Thus a novel approach and a corresponding prototype of a miniaturized endoscopic 3D-scanner are presented. To be suited even for very narrow objects, the prototype has a maximum diameter of 3.6 mm, its flexible design allows for access to bent tubes or canals. The 3D scanning approach is based on the principle of active triangulation, which means that a coded light pattern is projected and then viewed under a different angle. It is usually difficult to realize triangulation setups in a small embodiment. Therefore an optical tandem of a miniaturized pattern projector and a small camera with a resolution of 400 x 400 pixel is presented as a practical solution. The projector projects a pattern of 15 rings of distinct colors into a cylindrical measurement space where the color sequence constitutes a code. The camera uses a catadioptric setup with a spherical mirror to enhance its field of view. It detects the projected rings and is then able to unambiguously reconstruct the 3D-shape of a surface using ray-cone intersection. This so called color coding approach provides several advantages. For example, only a static projection pattern is needed, which greatly reduces complexity and size of the projector compared to phase shifting technologies. Experimental 3D-scans of arbitrarily shaped tubes demonstrate good performance and an accuracy of about 0.1mm.

  7. 3-D field computation: The near-triumph of commerical codes

    SciTech Connect

    Turner, L.R.

    1995-07-01

    In recent years, more and more of those who design and analyze magnets and other devices are using commercial codes rather than developing their own. This paper considers the commercial codes and the features available with them. Other recent trends with 3-D field computation include parallel computation and visualization methods such as virtual reality systems.

  8. 3D stochastic joint inversion of gravity and magnetic data

    NASA Astrophysics Data System (ADS)

    Shamsipour, Pejman; Marcotte, Denis; Chouteau, Michel

    2012-04-01

    A novel stochastic joint inversion method based on cokriging is applied to estimate density and magnetic susceptibility distributions from gravity and total magnetic field data. The method fully integrates the physical relations between density-gravity, on one hand, and magnetic susceptibility-total magnetic field, on the other hand. As a consequence, when the data are considered noise-free, the responses from the inverted density and susceptibility data exactly reproduce the observed data. The required density and magnetic susceptibility auto- and cross covariance are assumed to follow a linear model of coregionalization (LCM). The parameters of the LCM are estimated from v-v plot fitting of the gravity and total magnetic experimental covariances. The model is tested on two synthetic cases and one real data set, the Perseverance mine (Quebec, Canada). Joint inversions are compared to separate inversions. The joint inversions better recover the known models in the synthetic cases. With the real data set, better definition and location of the mineralized lenses are achieved by joint inversion.

  9. Exchange charge model of crystal field for 3d ions

    NASA Astrophysics Data System (ADS)

    Brik, M. G.; Avram, N. M.; Avram, C. N.

    In the second chapter of the book the authors present the results of theoretical studies ofthe energy levels schemes of all 3dn (n=1, 9) ionsin various crystals at the substitutionalsites. Systematic calculations are described in all details; they include the overlap integrals between the impurityions' and ligands' wave functions; the crystal field parameters calculations, and diagonalization of the crystal field Hamiltonians for each considered case. The calculated results arediscussed and compared with experimental data and with similar results from literature. The chapter also contains a comprehensive literature review on the properties of 3d-ions doped crystals.

  10. 3D deformation field throughout the interior of materials.

    SciTech Connect

    Jin, Huiqing; Lu, Wei-Yang

    2013-09-01

    This report contains the one-year feasibility study for our three-year LDRD proposal that is aimed to develop an experimental technique to measure the 3D deformation fields inside a material body. In this feasibility study, we first apply Digital Volume Correlation (DVC) algorithm to pre-existing in-situ Xray Computed Tomography (XCT) image sets with pure rigid body translation. The calculated displacement field has very large random errors and low precision that are unacceptable. Then we enhance these tomography images by setting threshold of the intensity of each slice. DVC algorithm is able to obtain accurate deformation fields from these enhanced image sets and the deformation fields are consistent with the global mechanical loading that is applied to the specimen. Through this study, we prove that the internal markers inside the pre-existing tomography images of aluminum alloy can be enhanced and are suitable for DVC to calculate the deformation field throughout the material body.

  11. Visualizing 3D velocity fields near contour surfaces

    SciTech Connect

    Max, N.; Crawfis, R.; Grant, C.

    1994-03-01

    Vector field rendering is difficult in 3D because the vector icons overlap and hide each other. We propose four different techniques for visualizing vector fields only near surfaces. The first uses motion blurred particles in a thickened region around the surface. The second uses a voxel grid to contain integral curves of the vector field. The third uses many antialiased lines through the surface, and the fourth uses hairs sprouting from the surface and then bending in the direction of the vector field. All the methods use the graphite pipeline, allowing real time rotation and interaction, and the first two methods can animate the texture to move in the flow determined by the velocity field.

  12. Experimental onset threshold and magnetic pressure pileup for 3D Sweet-Parker reconnection

    SciTech Connect

    Intrator, Thomas P; Sun, Xuan; Lapenta, Giovanni; Furno, Ivo

    2008-01-01

    In space, astrophysical and laboratory plasmas, magnetic reconnect ion converts magnetic into particle energy during unsteady, explosive events. The abrupt onset and cessation has been a long standing puzzle. We show the first three-dimensional (3D) laboratory example of onset and stagnation of Sweet-Parker type magnetic reconnection between magnetized and parallel current (flux) ropes driven by magnetohydrodynamic (MHD) attraction and 3D instability. Mutually attracting flux ropes advect and merge oppositely directed magnetic fields. Magnetic flux is annihilated, but reaches soon a threshold where magnetic flux and pressure pile up, and reconnection magnetic topology appears. This occurs when inflow speeds exceed the SweetParker speed v{sub SP} = v{sub A} / S{sup 1/2}, where v{sub A} is the Alfven speed and S is the Lundquist number for the reconnection layer, as magnetic flux arrives faster than flux annihilation can process it. Finally piled up fields generate MHD reaction forces that stall the inflow and the reconnection process.

  13. Magnetic and Magnetoresistive Properties of 3D Interconnected NiCo Nanowire Networks

    NASA Astrophysics Data System (ADS)

    da Câmara Santa Clara Gomes, Tristan; De La Torre Medina, Joaquín; Lemaitre, Matthieu; Piraux, Luc

    2016-10-01

    Track-etched polymer membranes with crossed nanochannels have been revealed to be most suitable as templates to produce large surface area and mechanically stable 3D interconnected nanowire (NW) networks by electrodeposition. Geometrically controlled NW superstructures made of NiCo ferromagnetic alloys exhibit appealing magnetoresistive properties. The combination of exact alloy compositions with the spatial arrangement of NWs in the 3D network is decisive to obtain specific magnetic and magneto-transport behavior. A proposed simple model based on topological aspects of the 3D NW networks is used to accurately determine the anisotropic magnetoresistance ratios. Despite of their complex topology, the microstructure of Co-rich NiCo NW networks display mixed fcc-hcp phases with the c-axis of the hcp phase oriented perpendicular to their axis. These interconnected NW networks have high potential as reliable and stable magnetic field sensors.

  14. Ballooning Stability Of Tokamak Pedestals In The Presence Of Applied 3D Magnetic Perturbations

    NASA Astrophysics Data System (ADS)

    Cote, T. B.; Hegna, C. C.; Willensdorfer, M.; Strumberger, E.; Suttrop, W.; Zohm, H.

    2016-10-01

    Applied 3d magnetic perturbations can destabilize ideal mhd ballooning modes in tokamak pedestals. In this work, we describe techniques for studying infinite-n ballooning stability of 3d equilibria deduced from vmec calculations. Full magnetic profiles from vmec are used to construct local equilibria for flux surfaces in and around the edge pedestal region. These local equilibrium calculations are coupled with ideal ballooning stability analysis to determine stability of the system for given rmp configurations. This theoretical development is motivated by recent asdex-u experiments, where toroidally localized high-n mhd activity is observed in the presence of applied 3d fields. We will attempt to explain these observations. Supported by US DOE under Grant No. DE-FG02-86ER53218.

  15. A 3D Current Loop Model of Magnetic Clouds

    NASA Astrophysics Data System (ADS)

    Chen, James

    1992-05-01

    A magnetohydrodynamic (MHD) model is developed to study magnetic clouds (Burlaga et al. 1981). In this model, magnetic clouds observed near 1 AU are treated as a consequence of eruptive solar current loops. It is shown that current loops intially in MHD equilibrium can be triggered to rise rapidly, propelling material of up to 10(16) g at up to ~ 1000 km s(-1) and dissipating ~ 10(32) erg of magnetic energy in tens of minutes. The initial rise profile is consistent with observed height-time profiles of erupting filaments (Kahler et al. 1988). Two triggering mechanisms for eruption are suggested: (1)subphotospheric energy storage and trigger and (2) in situ (coronal) energy storage and trigger. In the former, eruption occurs as a result of changes in the subphotospheric magnetic topology and subsequent relaxation to a new equilibrium. In the latter, the current loop can evolve to exceed a local maximum in the magnetic potential associated with the ambient magnetic fields. The former scenario leads to more energetic and longer-lasting eruption than the latter. Burlaga, L. F., Sittler, E., Mariani, F., and Schwenn, R. 1981, J. Geophys. Res., 86, 6673. Kahler, S. W., Moore, R. L., Kane, S. R., and Zirin, H. 1988, Ap. J., 328, 824.

  16. A Magnetic Diagnostic Code for 3D Fusion Equilibria

    SciTech Connect

    Samuel A. Lazerson, S. Sakakibara and Y. Suzuki

    2013-03-12

    A synthetic magnetic diagnostics code for fusion equilibria is presented. This code calculates the response of various magnetic diagnostics to the equilibria produced by the VMEC and PIES codes. This allows for treatment of equilibria with both good nested flux surfaces and those with stochastic regions. DIAGNO v2.0 builds upon previous codes through the implementation of a virtual casing principle. The code is validated against a vacuum shot on the Large Helical Device (LHD) where the vertical field was ramped. As an exercise of the code, the diagnostic response for various equilibria are calculated on the LHD.

  17. Quantitative 3D electromagnetic field determination of 1D nanostructures from single projection

    DOE PAGES

    Phatak, C.; Knoop, L. de; Houdellier, F.; ...

    2016-05-01

    One-dimensional (1D) nanostructures have been regarded as the most promising building blocks for nanoelectronics and nanocomposite material systems as well as for alternative energy applications. Although they result in confinement of a material, their properties and interactions with other nanostructures are still very much three-dimensional (3D) in nature. In this work, we present a novel method for quantitative determination of the 3D electromagnetic fields in and around 1D nanostructures using a single electron wave phase image, thereby eliminating the cumbersome acquisition of tomographic data. Using symmetry arguments, we have reconstructed the 3D magnetic field of a nickel nanowire as wellmore » as the 3D electric field around a carbon nanotube field emitter, from one single projection. The accuracy of quantitative values determined here is shown to be a better fit to the physics at play than the value obtained by conventional analysis. Moreover the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures.« less

  18. Quantitative 3D electromagnetic field determination of 1D nanostructures from single projection

    SciTech Connect

    Phatak, C.; Knoop, L. de; Houdellier, F.; Gatel, C.; Hÿtch, M. J.; Masseboeuf, A.

    2016-05-01

    One-dimensional (1D) nanostructures have been regarded as the most promising building blocks for nanoelectronics and nanocomposite material systems as well as for alternative energy applications. Although they result in confinement of a material, their properties and interactions with other nanostructures are still very much three-dimensional (3D) in nature. In this work, we present a novel method for quantitative determination of the 3D electromagnetic fields in and around 1D nanostructures using a single electron wave phase image, thereby eliminating the cumbersome acquisition of tomographic data. Using symmetry arguments, we have reconstructed the 3D magnetic field of a nickel nanowire as well as the 3D electric field around a carbon nanotube field emitter, from one single projection. The accuracy of quantitative values determined here is shown to be a better fit to the physics at play than the value obtained by conventional analysis. Moreover the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures.

  19. Quantitative 3D electromagnetic field determination of 1D nanostructures from single projection

    SciTech Connect

    Phatak, C.; Knoop, L. de; Houdellier, F.; Gatel, C.; Hÿtch, M. J.; Masseboeuf, A.

    2016-05-01

    One-dimensional (1D) nanostructures have been regarded as the most promising building blocks for nanoelectronics and nanocomposite material systems as well as for alternative energy applications. Although they result in confinement of a material, their properties and interactions with other nanostructures are still very much three-dimensional (3D) in nature. In this work, we present a novel method for quantitative determination of the 3D electromagnetic fields in and around 1D nanostructures using a single electron wave phase image, thereby eliminating the cumbersome acquisition of tomographic data. Using symmetry arguments, we have reconstructed the 3D magnetic field of a nickel nanowire as well as the 3D electric field around a carbon nanotube field emitter, from one single projection. The accuracy of quantitative values determined here is shown to be a better fit to the physics at play than the value obtained by conventional analysis. Moreover the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures.

  20. The 3D Flow Field Around an Embedded Planet

    NASA Astrophysics Data System (ADS)

    Fung, Jeffrey; Artymowicz, Pawel; Wu, Yanqin

    2015-10-01

    3D modifications to the well-studied 2D flow topology around an embedded planet have the potential to resolve long-standing problems in planet formation theory. We present a detailed analysis of the 3D isothermal flow field around a 5 Earth-mass planet on a fixed circular orbit, simulated using our graphics processing unit hydrodynamics code PEnGUIn. We find that, overall, the horseshoe region has a columnar structure extending vertically much beyond the Hill sphere of the planet. This columnar structure is only broken for some of the widest horseshoe streamlines, along which high altitude fluid descends rapidly into the planet’s Bondi sphere, performs one horseshoe turn, and exits the Bondi sphere radially in the midplane. A portion of this flow exits the horseshoe region altogether, which we refer to as the “transient” horseshoe flow. The flow continues as it rolls up into a pair of up-down symmetric horizontal vortex lines shed into the wake of the planet. This flow, unique to 3D, affects both planet accretion and migration. It prevents the planet from sustaining a hydrostatic atmosphere due to its intrusion into the Bondi sphere, and leads to a significant corotation torque on the planet, unanticipated by 2D analysis. In the reported simulation, starting with a {{Σ }}˜ {r}-3/2 radial surface density profile, this torque is positive and partially cancels with the negative differential Lindblad torque, resulting in a factor of three slower planet migration rate. Finally, we report 3D effects can be suppressed by a sufficiently large disk viscosity, leading to results similar to 2D.

  1. [Application of 3D FIESTA sequence in magnetic resonance sialography for obstructive salivary diseases].

    PubMed

    Kang, Zhuang; Zou, Yan; Su, Yu-xiong; Wang, Liang; Luo, Zhong-xing; Lu, Guang-wen

    2009-12-01

    To investigate the value of 3D FIESTA sequence in magnetic resonance sialography (MRS) in the diagnosis of obstructive salivary diseases. Eleven patients with obstructive salivary diseases underwent MRS, and three-dimensional (3D) reconstruction and virtual endoscopic images of the salivary gland ducts were obtained after MRS data post-processing for comparison with those of sialoendoscopy. The diagnostic accuracy of MRS was 72.7% for obstructive salivary diseases. The virtual endoscopy provided a visual field highly consistent with that by sialoendoscopy. MRS is capable of visualizing the tracts of salivary glands. MR virtual endoscopy can provide sufficient morphological and pathological data for preoperative assessment of salivary operations with sialoendoscopy.

  2. Analysis of a 3-D system function measured for magnetic particle imaging.

    PubMed

    Rahmer, Jürgen; Weizenecker, Jürgen; Gleich, Bernhard; Borgert, Jörn

    2012-06-01

    Magnetic particle imaging (MPI) is a new tomographic imaging approach that can quantitatively map magnetic nanoparticle distributions in vivo. It is capable of volumetric real-time imaging at particle concentrations low enough to enable clinical applications. For image reconstruction in 3-D MPI, a system function (SF) is used, which describes the relation between the acquired MPI signal and the spatial origin of the signal. The SF depends on the instrumental configuration, the applied field sequence, and the magnetic particle characteristics. Its properties reflect the quality of the spatial encoding process. This work presents a detailed analysis of a measured SF to give experimental evidence that 3-D MPI encodes information using a set of 3-D spatial patterns or basis functions that is stored in the SF. This resembles filling 3-D k-space in magnetic resonance imaging, but is faster since all information is gathered simultaneously over a broad acquisition bandwidth. A frequency domain analysis shows that the finest structures that can be encoded with the presented SF are as small as 0.6 mm. SF simulations are performed to demonstrate that larger particle cores extend the set of basis functions towards higher resolution and that the experimentally observed spatial patterns require the existence of particles with core sizes of about 30 nm in the calibration sample. A simple formula is presented that qualitatively describes the basis functions to be expected at a certain frequency.

  3. Extensions of 1d Bgk Electron Solitary Wave Solutions To 3d Magnetized and Unmagnetized Plasmas

    NASA Astrophysics Data System (ADS)

    Chen, Li-Jen; Parks, George K.

    This paper will compare the key results for BGK electron solitary waves in 3D mag- netized and unmagnetized plasmas. For 3D magnetized plasmas with highly magnetic field-aligned electrons, our results predict that the parallel widths of the solitary waves can be smaller than one Debye length, the solitary waves can be large scale features of the magnetosphere, and the parallel width-amplitude relation has a dependence on the perpendicular size. We can thus obtain an estimate on the typical perpendicular size of the observed solitary waves assuming a series of consecutive solitary waves are in the same flux tude with a particular perpendicular span. In 3D unmagnetized plasma systems such as the neutral sheet and magnetic reconnection sites, our theory indi- cates that although mathematical solutions can be constructed as the time-stationary solutions for the nonlinear Vlasov-Poisson equations, there does not exist a param- eter range for the solutions to be physical. We conclude that single-humped solitary potential pulses cannot be self-consistently supported by charged particles in 3D un- magnetized plasmas.

  4. 3-D flame temperature field reconstruction with multiobjective neural network

    NASA Astrophysics Data System (ADS)

    Wan, Xiong; Gao, Yiqing; Wang, Yuanmei

    2003-02-01

    A novel 3-D temperature field reconstruction method is proposed in this paper, which is based on multiwavelength thermometry and Hopfield neural network computed tomography. A mathematical model of multi-wavelength thermometry is founded, and a neural network algorithm based on multiobjective optimization is developed. Through computer simulation and comparison with the algebraic reconstruction technique (ART) and the filter back-projection algorithm (FBP), the reconstruction result of the new method is discussed in detail. The study shows that the new method always gives the best reconstruction results. At last, temperature distribution of a section of four peaks candle flame is reconstructed with this novel method.

  5. A full field, 3-D velocimeter for microgravity crystallization experiments

    NASA Technical Reports Server (NTRS)

    Brodkey, Robert S.; Russ, Keith M.

    1991-01-01

    The programming and algorithms needed for implementing a full-field, 3-D velocimeter for laminar flow systems and the appropriate hardware to fully implement this ultimate system are discussed. It appears that imaging using a synched pair of video cameras and digitizer boards with synched rails for camera motion will provide a viable solution to the laminar tracking problem. The algorithms given here are simple, which should speed processing. On a heavily loaded VAXstation 3100 the particle identification can take 15 to 30 seconds, with the tracking taking less than one second. It seeems reasonable to assume that four image pairs can thus be acquired and analyzed in under one minute.

  6. Cash value of 3-D seismic to a producing field

    SciTech Connect

    Bligh, R.; Thompson, S.

    1996-05-01

    Recent years have produced many reservoir management examples guided by seismic where clear value in excess of cost can be demonstrated. One of these examples was a 3-D survey recorded in the winter of 1994 over the Wytch Farm oil field in southern England, operated by BP on behalf of a consortium, including Arco, Clyda, Premier, Goal and Purbeck. A joint BP-CGG case history of this survey was presented at the 1995 SEG Convention in Houston and will be repeated at the 1996 AAPG Convention in San Diego. A brief summary is provided in this paper.

  7. Laboratory Study of Magnetic Reconnection in 3D Geometry Relevant to Magnetopause and Magnetotail

    NASA Astrophysics Data System (ADS)

    Ren, Y.; Lu, Q.; Ji, H.; Mao, A.; Wang, X.; E, P.; Wang, Z.; Xiao, Q.; Ding, W.; Zheng, J.

    2015-12-01

    Laboratory Study of Magnetic Reconnection in 3D Geometry Relevant to Magnetopause and Magnetotail Y. Ren1,2, Quaming Lu3, Hantao Ji1,2, Aohua Mao1, Xiaogang Wang1, Peng E1, Zhibin Wang1, Qingmei Xiao1, Weixing Ding4, Jinxing Zheng51 Harbin Institute of Technology, Harbin, China2 Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 3University of Science and Technology of China, Hefei, China 4University of California at Los Angeles, Los Angeles, CA, 90095 5ASIPP, Hefei, China A new magnetic reconnection experiment, Harbin reconnection eXperiment (HRX), is currently being designed as a key part of Space Plasma Environment Research Facility (SPERF) at Harbin Institute of Technology in Harbin, China. HRX aims to provide a unique experimental platform for studying reconnections in 3D geometry relevant to magnetopause and magnetotail to address: the role of electron and ion-scale dynamics in the current sheet; particle and energy transfer from magnetosheath to magnetosphere; particle energization/heating mechanisms during magnetic reconnection; 3D effects in fast reconnection, e.g. the role of 3D magnetic null point. HRX employs a unique set of coils to generate the required 3D magnetic geometry and provides a wide range of plasma parameters. Here, important motivating scientific problems are reviewed and the physics design of HRX is presented, including plasma parameters determined from Vlasov scaling law, reconnection scenarios explored using vacuum magnetic field calculations and numerical simulations of HRX using hybrid and MHD codes. Plasma diagnostics plan and engineering design of important coils will also be briefly presented.

  8. Nonthermal Particle Acceleration in 3D Relativistic Magnetic Reconnection in Pair Plasma

    NASA Astrophysics Data System (ADS)

    Uzdensky, Dmitri; Werner, Gregory; Zhdankin, Vladimir

    2016-10-01

    Magnetic reconnection is a fundamental plasma process that converts magnetic energy into particle kinetic energy. ``Relativistic'' reconnection is of interest in astrophysical contexts because it can accelerate particles to relativistic energies high enough for synchrotron (or inverse Compton) emission to explain observed high-energy radiation. After several 2D particle-in-cell (PIC) simulations of reconnection in pair plasmas demonstrated power-law electron-energy spectra extending to high energies, a few 3D simulations surprisingly confirmed the robustness of nonthermal particle acceleration, despite fundamental differences, such as the development of the relativistic drift-kink instability (RDKI) in 3D. We present a comprehensive PIC study of 3D relativistic pair-plasma reconnection characterizing the effect of the third dimension. We investigate how reconnection dynamics and particle acceleration depend on guide magnetic field Bz and on the simulation box length Lz in the third dimension. We find that, while the RDKI does indeed grow in 3D reconnection, it does not inhibit particle acceleration, even in the absence of guide field. This work was funded by NSF, DOE, and NASA.

  9. The ITER 3D Magnetic Diagnostic Response to Applied n=3 and n=4 RMP's

    SciTech Connect

    Lazerson, S A

    2014-09-01

    The ITER magnetic diagnostic response to applied n=3 and n=4 RMPs has been calculated for the 15MA scenario. The VMEC code was utilized to calculate free boundary 3D ideal MHD equilibria, where the non-stellarator symmetric terms were included in the calculation. This allows an assessment to be made of the possible boundary displacements due to RMP application in ITER. As the VMEC code assumes a continuous set of nested flux surface, the possibility of island and stochastic region formation is ignored. At the start of the current at-top (L-Mode) application of n = 4 RMP's indicates approximately 1 cm peak-to-peak displacements on the low field side of the plasma while later in the shot (H-mode) perturbations as large as 3 cm are present. Forward modeling of the ITER magnetic diagnostics indicates significant non-axisymmetric plasma response, exceeding 10% the axisymmetric signal in many of the flux loops. Magnetic field probes seem to indicate a greater robustness to 3D effects but still indicate large sensitivities to 3D effects in a number of sensors. Forward modeling of the diagnostics response to 3D equilibria allows assessment of diagnostics design and control scenarios.

  10. Three-dimensional two-fluid investigation of 3D-localized magnetic reconnection and its relation to whistler waves

    NASA Astrophysics Data System (ADS)

    Yoon, Young Dae; Bellan, Paul M.

    2016-10-01

    A full three-dimensional computer code was developed in order to simulate a 3D-localized magnetic reconnection. We assume an incompressible two-fluid regime where the ions are stationary, and electron inertia and Hall effects are present. We solve a single dimensionless differential equation for perturbed magnetic fields with arbitrary background fields. The code has successfully reproduced both experimental and analytic solutions to resonance and Gendrin mode whistler waves in a uniform background field. The code was then modified to model 3D-localized magnetic reconnection as a 3D-localized perturbation on a hyperbolic-tangent background field. Three-dimensional properties that are asymmetric in the out-of-plane direction have been observed. These properties pertained to magnetic field lines, electron currents and their convection. Helicity and energy have also been examined, as well as the addition of a guide field.

  11. Evidence of toroidally localized turbulence with applied 3D fields in the DIII-D tokamak

    SciTech Connect

    Wilcox, R. S.; Shafer, M. W.; Ferraro, N. M.; McKee, G. R.; Zeng, L.; Rhodes, T. L.; Canik, J. M.; Paz-Soldan, C.; Nazikian, R.; Unterberg, E. A.

    2016-09-21

    New evidence indicates that there is significant 3D variation in density fluctuations near the boundary of weakly 3D tokamak plasmas when resonant magnetic perturbations are applied to suppress transient edge instabilities. The increase in fluctuations is concomitant with an increase in the measured density gradient, suggesting that this toroidally localized gradient increase could be a mechanism for turbulence destabilization in localized flux tubes. Two-fluid magnetohydrodynamic simulations find that, although changes to the magnetic field topology are small, there is a significant 3D variation of the density gradient within the flux surfaces that is extended along field lines. This modeling agrees qualitatively with the measurements. The observed gradient and fluctuation asymmetries are proposed as a mechanism by which global profile gradients in the pedestal could be relaxed due to a local change in the 3D equilibrium. In conclusion, these processes may play an important role in pedestal and scrape-off layer transport in ITER and other future tokamak devices with small applied 3D fields.

  12. Evidence of Toroidally Localized Turbulence with Applied 3D Fields in the DIII-D Tokamak.

    PubMed

    Wilcox, R S; Shafer, M W; Ferraro, N M; McKee, G R; Zeng, L; Rhodes, T L; Canik, J M; Paz-Soldan, C; Nazikian, R; Unterberg, E A

    2016-09-23

    New evidence indicates that there is significant 3D variation in density fluctuations near the boundary of weakly 3D tokamak plasmas when resonant magnetic perturbations are applied to suppress transient edge instabilities. The increase in fluctuations is concomitant with an increase in the measured density gradient, suggesting that this toroidally localized gradient increase could be a mechanism for turbulence destabilization in localized flux tubes. Two-fluid magnetohydrodynamic simulations find that, although changes to the magnetic field topology are small, there is a significant 3D variation of the density gradient within the flux surfaces that is extended along field lines. This modeling agrees qualitatively with the measurements. The observed gradient and fluctuation asymmetries are proposed as a mechanism by which global profile gradients in the pedestal could be relaxed due to a local change in the 3D equilibrium. These processes may play an important role in pedestal and scrape-off layer transport in ITER and other future tokamak devices with small applied 3D fields.

  13. Evidence of toroidally localized turbulence with applied 3D fields in the DIII-D tokamak

    SciTech Connect

    Wilcox, R. S.; Shafer, M. W.; Ferraro, N. M.; McKee, G. R.; Zeng, L.; Rhodes, T. L.; Canik, J. M.; Paz-Soldan, C.; Nazikian, R.; Unterberg, E. A.

    2016-09-21

    New evidence indicates that there is significant 3D variation in density fluctuations near the boundary of weakly 3D tokamak plasmas when resonant magnetic perturbations are applied to suppress transient edge instabilities. The increase in fluctuations is concomitant with an increase in the measured density gradient, suggesting that this toroidally localized gradient increase could be a mechanism for turbulence destabilization in localized flux tubes. Two-fluid magnetohydrodynamic simulations find that, although changes to the magnetic field topology are small, there is a significant 3D variation of the density gradient within the flux surfaces that is extended along field lines. This modeling agrees qualitatively with the measurements. The observed gradient and fluctuation asymmetries are proposed as a mechanism by which global profile gradients in the pedestal could be relaxed due to a local change in the 3D equilibrium. In conclusion, these processes may play an important role in pedestal and scrape-off layer transport in ITER and other future tokamak devices with small applied 3D fields.

  14. Evidence of toroidally localized turbulence with applied 3D fields in the DIII-D tokamak

    DOE PAGES

    Wilcox, R. S.; Shafer, M. W.; Ferraro, N. M.; ...

    2016-09-21

    New evidence indicates that there is significant 3D variation in density fluctuations near the boundary of weakly 3D tokamak plasmas when resonant magnetic perturbations are applied to suppress transient edge instabilities. The increase in fluctuations is concomitant with an increase in the measured density gradient, suggesting that this toroidally localized gradient increase could be a mechanism for turbulence destabilization in localized flux tubes. Two-fluid magnetohydrodynamic simulations find that, although changes to the magnetic field topology are small, there is a significant 3D variation of the density gradient within the flux surfaces that is extended along field lines. This modeling agreesmore » qualitatively with the measurements. The observed gradient and fluctuation asymmetries are proposed as a mechanism by which global profile gradients in the pedestal could be relaxed due to a local change in the 3D equilibrium. In conclusion, these processes may play an important role in pedestal and scrape-off layer transport in ITER and other future tokamak devices with small applied 3D fields.« less

  15. Combined registration of 3D tibia and femur implant models in 3D magnetic resonance images

    NASA Astrophysics Data System (ADS)

    Englmeier, Karl-Hans; Siebert, Markus; von Eisenhart-Rothe, Ruediger; Graichen, Heiko

    2008-03-01

    The most frequent reasons for revision of total knee arthroplasty are loosening and abnormal axial alignment leading to an unphysiological kinematic of the knee implant. To get an idea about the postoperative kinematic of the implant, it is essential to determine the position and orientation of the tibial and femoral prosthesis. Therefore we developed a registration method for fitting 3D CAD-models of knee joint prostheses into an 3D MR image. This rigid registration is the basis for a quantitative analysis of the kinematics of knee implants. Firstly the surface data of the prostheses models are converted into a voxel representation; a recursive algorithm determines all boundary voxels of the original triangular surface data. Secondly an initial preconfiguration of the implants by the user is still necessary for the following step: The user has to perform a rough preconfiguration of both remaining prostheses models, so that the fine matching process gets a reasonable starting point. After that an automated gradient-based fine matching process determines the best absolute position and orientation: This iterative process changes all 6 parameters (3 rotational- and 3 translational parameters) of a model by a minimal amount until a maximum value of the matching function is reached. To examine the spread of the final solutions of the registration, the interobserver variability was measured in a group of testers. This variability, calculated by the relative standard deviation, improved from about 50% (pure manual registration) to 0.5% (rough manual preconfiguration and subsequent fine registration with the automatic fine matching process).

  16. 3D wind field from spaceborne Doppler radar

    NASA Astrophysics Data System (ADS)

    Lemaître, Y.; Viltard, N.

    2013-10-01

    Numerous space radar missions are presently envisioned to study the water cycle in the tropics. Among them, the DYCECT (DYnamique, énergie et Cycle de l'Eau dans la Convection Tropicale) mission, a French proposal (submitted to the French CNES Agency), could embark a Doppler radar (W-band or Ka-band) with scanning possibilities onboard a low-orbiting satellite. This instrument could be implemented in addition to a Passive Microwave Radiometer (PMR), and eventually an improved ScaraB-like broadband radiometer, and a lightning detection instrument. This package will document the ice microphysics and the heat budgets. Since the microphysics and the water and energy budgets are strongly driven by the dynamics, the addition of a Doppler radar with scanning possibilities could provide valuable information (3D wind and rain fields) and a large statistic of such critical information over the entire tropics and for all the stages of development. These new information could be used to better understand the tropical convection and to improve convection parameterization relevant for cloud and climate models. It could be used also to associate direct applications such as now-casting and risk prevention. The present study focuses on the feasibility of such 3D wind field retrieval from spaceborne radar. It uses a simulator of some parts of the spaceborne radar in order i) to evaluate the sensitivity of the retrieved wind fields to the scanning strategies and sampling parameters, and to the instrumental and platform parameters and ii) to determine the best parameters providing the most accurate wind fields.

  17. A 3D gravity and magnetic model for the Entenschnabel area (German North Sea)

    NASA Astrophysics Data System (ADS)

    Dressel, Ingo; Barckhausen, Udo; Heyde, Ingo

    2017-06-01

    In this study, we focus on structural configuration of the Entenschnabel area, a part of the German exclusive economic zone within the North Sea, by means of gravity and magnetic modelling. The starting point of the 3D modelling approach is published information on subseafloor structures for shallow depths, acquired by wells and seismic surveys. Subsequent gravity and magnetic modelling of the structures of the deeper subsurface builds on this geophysical and geological information and on gravity and magnetic data acquired during a research cruise to the Entenschnabel area. On the one hand, our 3D model shows the density and susceptibility distribution of the sediments and the crust. In addition, the potential field modelling provides evidence for a differentiation between lower and upper crust. The thickness distribution of the crust is also discussed with respect to the tectonic framework. Furthermore, gravity as well as magnetic modelling points to an intrusive complex beneath the Central Graben within the Entenschnabel area. On the other hand, this work provides a geological-geophysical consistent 3D gravity and magnetic model that can be used as a starting point for further investigation of this part of the German North Sea.

  18. Direct-write 3D printing of composite materials with magnetically aligned discontinuous reinforcement

    NASA Astrophysics Data System (ADS)

    Martin, Joshua J.; Caunter, Andrew; Dendulk, Amy; Goodrich, Scott; Pembroke, Ryan; Shores, Dan; Erb, Randall M.

    2017-05-01

    Three-dimensional (3D) printing of fiber reinforced composites represents an enabling technology that may bring toughness and specific strength to complex parts. Recently, direct-write 3D printing has been offered as a promising route to manufacturing fiber reinforced composites that show high specific strength. These approaches primarily rely on the use of shear-alignment during the extrusion process to align fibers along the printing direction. Shear alignment prevents fibers from being oriented along principle stress directions of the final designed part. This paper describes a new direct-write style 3D printing system that incorporates magnetic fields to actively control the orientation of reinforcing fibers during the printing of fiber reinforced composites. Such a manufacturing system is fraught with complications from the high shear dominated alignment experienced by the fibers during extrusion to the slow magnetic alignment dynamics of fibers in viscous media. Here we characterize these issues and suggest effective operating windows in which magnetic alignment is a viable approach to orienting reinforcing particles during direct-write 3D printing.

  19. 3D low-beta magnetized plasma equilibria from external shaping

    NASA Astrophysics Data System (ADS)

    Hassam, A.; Tenbarge, J.; Landreman, M.; Dorland, W.; Sengupta, W.

    2016-10-01

    A 3D nonlinear dissipative MHD code is in development to allow relaxation to low-beta MHD equilibrium inside a shaped 3D conducting boundary with prescribed conserved axial magnetic flux and no external current. Formation of magnetic islands is expected. Heat sources would be eventually introduced to allow the possibility of non-stationary convection depending on the stability properties of the accessible MHD equilibria. The initial development will be done using the code UMHD. The initial emphasis will be on recovering expected physics in simpler 3D geometries. A primary objective is to minimize numerical boundary noise. In particular, codes which specify the normal magnetic field B.n on bounding surfaces are prone to noise generation. We plan to shape the boundary to conform to the desired field shape so that B.n is zero on the boundary. Non-orthogonal coordinates will be chosen to effect this. We will test noise reduction within the tangential field approach. Results obtained to date support this conjecture. Initial results from simple 2D code equilibria have been verified against analytic solution of equilibria in weak shaping. Initial results also recover the expected features of the Hahm- Kulsrud island formation solution. Work supported by US DOE.

  20. 3D inversion of full magnetic gradient tensor data based on hybrid regularization method

    NASA Astrophysics Data System (ADS)

    Ji, Shuangxi; Zhang, Huai; Wang, Yanfei; Zhao, Lingling

    2017-04-01

    Recently, the magnetic tensor data can be directly measured due to the latest development of superconducting quantum interference device (SQUID) based sensors, which can collect five unique magnetic gradients components (partial H_x/ partial x , partial H_x/ partial y , partial H_x/ partial z , partial H_y/ partial z ,partial H_z/ partial z ). More measurement date will bring more useful information of observed magnetic anomaly, however it still bear the computational instability problem because of the intrinsic ill-posed property in the magnetic inverse problem. Furthermore, most of research on magnetic regularization inversion only concentrate on total magnetic field or magnetic vector field, rather than the magnetic gradient tensor field. Therefore we introduce a novel 3D hybrid regularization method by MS-TV stabilizer for inversion of magnetic gradient tensor data, which is designed mainly based on the minimum support functional (MS) and total variation functional (TV), and the final regularization functional can be described as the following form: J(κ)&=1/2(G(κ)-d,wd(G(κ)-d))ΩP+α((1-λ)φpMS(κ)+λφβ TV(κ)) &=1/2(G(κ)-d,wd(G(κ)-d))ΩP +α(1-λ/2\\intΩQ(κ-κprior)2/(κ-κprior)2+e2dΩQ &+λ\\intΩQ√{|\

  1. Invariant superoscillatory electromagnetic fields in 3D-space

    NASA Astrophysics Data System (ADS)

    Makris, K. G.; Papazoglou, D. G.; Tzortzakis, S.

    2017-01-01

    We derive exact solutions of Maxwell’s equations based on superoscillatory superpositions of vectorial Bessel beams. These novel beams are diffraction-free and can support subwavelength features in their transverse electromagnetic fields, without the presence of any evanescent waves. These features can be propagated into the far field. Approximate solutions in closed form are also derived based on asymptotic expansions of Bessel functions for simple prescribed subwavelength patterns. The superoscillatory characteristics of both electric, magnetic field components (transverse and longitudinal), and the Poynting vector, as well as, the effect of nonparaxiality are systematically investigated.

  2. Magnetic Dissipation in Asymmetric Strong Guide 3D Simulations: Examples of Magnetic Diffusion and Reconnection

    NASA Astrophysics Data System (ADS)

    Scudder, J. D.; Karimabadi, H.; Daughton, W. S.

    2013-12-01

    Interpretations of 2D simulations of magnetic reconnection are greatly simplified by using the flux function, usually the out of plane component of the vector potential. This theoretical device is no longer available when simulations are analyzed in 3-D. We illustrate the results of determining the locale rates of flux slippage in simulations by a technique based on Maxwell's equations. The technique recovers the usual results obtained for the flux function in 2D simulations, but remains viable in 3D simulations where there is no flux function. The method has also been successfully tested for full PIC simulations where reconnection is geometrically forbiddden. While such layers possess measurable flux slippages (diffusion) their level is not as strong as recorded in known 2D PIC reconnection sites using the same methodology. This approach will be used to explore the spatial incidence and strength of flux slippages across a 3D, asymmetric, strong guide field run discussed previously in the literature. Regions of diffusive behavior are illustrated where LHDI has been previously identified out on the separatrices, while much stronger flux slippages, typical of the X-regions of 2D simulations, are shown to occur elsewhere throughout the simulation. These results suggest that reconnection requires sufficiently vigorous flux slippage to be self sustaining, while non-zero flux slippage can and does occur without being at the reconnection site. A cross check of this approach is provided by the mixing ratio of tagged simulation particles of known spatial origin discussed by Daughton et al., 2013 (this meeting); they provide an integral measure of flux slippage up to the present point in the simulation. We will discuss the correlations between our Maxwell based flux slippage rates and the inferred rates of change of this mixing ratio (as recorded in the local fluid frame).

  3. MR imaging of the internal auditory canal and inner ear at 3T: comparison between 3D driven equilibrium and 3D balanced fast field echo sequences.

    PubMed

    Byun, Jun Soo; Kim, Hyung Jin; Yim, Yoo Jeong; Kim, Sung Tae; Jeon, Pyoung; Kim, Keon Ha; Kim, Sam Soo; Jeon, Yong Hwan; Lee, Jiwon

    2008-01-01

    To compare the use of 3D driven equilibrium (DRIVE) imaging with 3D balanced fast field echo (bFFE) imaging in the assessment of the anatomic structures of the internal auditory canal (IAC) and inner ear at 3 Tesla (T). Thirty ears of 15 subjects (7 men and 8 women; age range, 22-71 years; average age, 50 years) without evidence of ear problems were examined on a whole-body 3T MR scanner with both 3D DRIVE and 3D bFFE sequences by using an 8-channel sensitivity encoding (SENSE) head coil. Two neuroradiologists reviewed both MR images with particular attention to the visibility of the anatomic structures, including four branches of the cranial nerves within the IAC, anatomic structures of the cochlea, vestibule, and three semicircular canals. Although both techniques provided images of relatively good quality, the 3D DRIVE sequence was somewhat superior to the 3D bFFE sequence. The discrepancies were more prominent for the basal turn of the cochlea, vestibule, and all semicircular canals, and were thought to be attributed to the presence of greater magnetic susceptibility artifacts inherent to gradient-echo techniques such as bFFE. Because of higher image quality and less susceptibility artifacts, we highly recommend the employment of 3D DRIVE imaging as the MR imaging choice for the IAC and inner ear.

  4. Imaging solar coronal magnetic structures in 3D

    NASA Astrophysics Data System (ADS)

    Cartledge, N. P.

    The study of solar coronal structures and, in particular prominences, is a key part of understanding the highly complex physical mechanisms occurring in the Sun's atmosphere. Solar prominences are important in their own right and some of the most puzzling questions in solar theory have arisen through their study. For example, how do they form and how is their mass continuously replenished? How can the magnetic field provide their continuous support against gravity over time periods of several months? How can such cool, dense material exist in thermal equilibrium in the surrounding coronal environment? Why do they erupt? A study of their structure and that of the surrounding medium is important in determining the nature of the coronal plasma and magnetic field. Also, prominences are closely associated with other key phenomena such as coronal mass ejections and eruptive solar flares which occur as a prominence loses equilibrium and rises from the solar surface. Our current understanding of these fascinating structures is extremely limited and we know very little about their basic global structure. In fact, recent prominence observations have caused our basic paradigms to be challenged (Priest, 1996) and so we must set up new models in order to gain even a fundamental understanding. Prominences are highly nonlinear, three-dimensional structures. Large feet (or barbs) reach out from the main body of a prominence and reach down to the photosphere where the dense material continuously drains away. These provide a real clue to the three-dimensional nature of the coronal field and its relation to the photospheric field. It is important, therefore, to make stereographic observations of prominences in order to gain a basic understanding of their essentially three-dimensional nature and attempt to formulate new paradigms for their structure and evolution. There is no doubt that the study of prominences in three dimensions is a crucial exercise if we are to develop a better

  5. Exploration 3-D Seismic Field Test/Native Tribes Initiative

    SciTech Connect

    Carroll, Herbert B.; Chen, K.C.; Guo, Genliang; Johnson, W.I.; Reeves,T.K.; Sharma,Bijon

    1999-04-27

    To determine current acquisition procedures and costs and to further the goals of the President's Initiative for Native Tribes, a seismic-survey project is to be conducted on Osage tribal lands. The goals of the program are to demonstrate the capabilities, costs, and effectiveness of 3-D seismic work in a small-operator setting and to determine the economics of such a survey. For these purposes, typical small-scale independent-operator practices are being followed and a shallow target chose in an area with a high concentration of independent operators. The results will be analyzed in detail to determine if there are improvements and/or innovations which can be easily introduced in field-acquisition procedures, in processing, or in data manipulation and interpretation to further reduce operating costs and to make the system still more active to the small-scale operator.

  6. Advanced prior modeling for 3D bright field electron tomography

    NASA Astrophysics Data System (ADS)

    Sreehari, Suhas; Venkatakrishnan, S. V.; Drummy, Lawrence F.; Simmons, Jeffrey P.; Bouman, Charles A.

    2015-03-01

    Many important imaging problems in material science involve reconstruction of images containing repetitive non-local structures. Model-based iterative reconstruction (MBIR) could in principle exploit such redundancies through the selection of a log prior probability term. However, in practice, determining such a log prior term that accounts for the similarity between distant structures in the image is quite challenging. Much progress has been made in the development of denoising algorithms like non-local means and BM3D, and these are known to successfully capture non-local redundancies in images. But the fact that these denoising operations are not explicitly formulated as cost functions makes it unclear as to how to incorporate them in the MBIR framework. In this paper, we formulate a solution to bright field electron tomography by augmenting the existing bright field MBIR method to incorporate any non-local denoising operator as a prior model. We accomplish this using a framework we call plug-and-play priors that decouples the log likelihood and the log prior probability terms in the MBIR cost function. We specifically use 3D non-local means (NLM) as the prior model in the plug-and-play framework, and showcase high quality tomographic reconstructions of a simulated aluminum spheres dataset, and two real datasets of aluminum spheres and ferritin structures. We observe that streak and smear artifacts are visibly suppressed, and that edges are preserved. Also, we report lower RMSE values compared to the conventional MBIR reconstruction using qGGMRF as the prior model.

  7. 3D wind field retrieval from spaceborne Doppler radar

    NASA Astrophysics Data System (ADS)

    Lemaêtre, Y.; Viltard, N.

    2012-11-01

    Numerous space missions carrying a radar are presently envisioned, particularly to study tropical rain systems. Among those missions, BOITATA is a joint effort between Brazil (INPE/AEB) and France (CNES). The goal is to embark a Doppler radar with scanning possibilities onboard a low-orbiting satellite. This instrument should be implemented in addition to a Passive Microwave Radiometer (PMR) between 19 and 183 GHz, an improved ScaraB-like broadband radiometer, a mm/submm PMR and a lightning detection instrument. This package would be meant to document the feedback of the ice microphysics on the rain systems life cycle and on their heat and radiative budgets. Since the microphysics and the water and energy budgets are strongly driven by the dynamics, the addition of a Doppler radar with scanning possibilities could provide precious information (3D wind and rain fields). It would allow us to build a large statistics of such critical information over the entire tropics and for all the stages of development of the convection. This information could be used to better understand the tropical convection and to improve convection parameterization relevant for cloud and climate models and associated applications such as now-casting and risk prevention. The present work focuses on the feasibility to retrieve 3D winds in precipitating areas from such a radar. A simulator of some parts of the spaceborne radar is developed to estimate the precision on the retrieved wind field depending on the scanning strategies and instrumental parameters and to determine the best sampling parameters.

  8. Pipe3D, a pipeline to analyze Integral Field Spectroscopy Data: I. New fitting philosophy of FIT3D

    NASA Astrophysics Data System (ADS)

    Sánchez, S. F.; Pérez, E.; Sánchez-Blázquez, P.; González, J. J.; Rosález-Ortega, F. F.; Cano-Dí az, M.; López-Cobá, C.; Marino, R. A.; Gil de Paz, A.; Mollá, M.; López-Sánchez, A. R.; Ascasibar, Y.; Barrera-Ballesteros, J.

    2016-04-01

    We present an improved version of FIT3D, a fitting tool for the analysis of the spectroscopic properties of the stellar populations and the ionized gas derived from moderate resolution spectra of galaxies. This tool was developed to analyze integral field spectroscopy data and it is the basis of Pipe3D, a pipeline used in the analysis of CALIFA, MaNGA, and SAMI data. We describe the philosophy and each step of the fitting procedure. We present an extensive set of simulations in order to estimate the precision and accuracy of the derived parameters for the stellar populations and the ionized gas. We report on the results of those simulations. Finally, we compare the results of the analysis using FIT3D with those provided by other widely used packages, and we find that the parameters derived by FIT3D are fully compatible with those derived using these other tools.

  9. Comparison of divertor heat flux splitting by 3D fields with field line tracing simulation in KSTAR

    NASA Astrophysics Data System (ADS)

    Kim, Kimin; Ahn, J.-W.; Lee, H. H.; Park, J.-K.; Kang, C. S.; In, Y.; Kwak, J. G.; Yoon, S. W.; Oh, O. K.; Choe, Wonho

    2017-05-01

    We present the experimental and numerical analysis of divertor heat flux spitting by 3D magnetic fields in KSTAR. A dedicated experiment to measure the modification of the divertor heat flux profile in the n = 2 resonant and non-resonant field configurations has been conducted. The measured heat flux profiles were directly compared to the magnetic field line tracing (FLT) simulation using the POCA-FLT code, which fully considers vacuum and ideal plasma response models. Measurements indicate that the 3D fields induce strong splitting of heat flux on the divertor target due to the formation of stochastic field layers. Splitting characteristics largely depend on the applied 3D field structure and its alignment to the axisymmetric magnetic pitch. The modeling of the field line connection length shows good agreement with measurements, reproducing well the pattern of heat flux splitting. Simulations with the ideal plasma response better reproduce measured heat flux profiles by excitation of non-resonant field components in the non-resonant 0° phase and shielding of resonant field components in the resonant 90° phase.

  10. [A 3D FEM model for calculation of electromagnetic fields in transmagnetic stimulation].

    PubMed

    Seilwinder, J; Kammer, T; Andrä, W; Bellemann, M E

    2002-01-01

    We developed a realistic finite elements method (FEM) model of the brain for the calculation of electromagnetic fields in transcranial magnetic stimulation (TMS). A focal butterfly stimulation coil was X-rayed, parameterized, and modeled. The magnetic field components of the TMS coil were calculated and compared for validation to pointwise measurements of the magnetic fields with a Hall sensor. We found a mean deviation of 7.4% at an axial distance of 20 mm to the coil. A 3D brain model with the biological tissues of white and gray matter, bone, and cerebrospinal fluid was developed. At a current sweep of 1000 A in 120 microseconds, the maximum induced current density in gray matter was 177 mA/m2 and the strongest electric field gradient covered an area of 40 mm x 53 mm.

  11. The distribution of 3D superconductivity near the second critical field

    NASA Astrophysics Data System (ADS)

    Kachmar, Ayman; Nasrallah, Marwa

    2016-09-01

    We study the minimizers of the Ginzburg-Landau energy functional with a uniform magnetic field in a three dimensional bounded domain. The functional depends on two positive parameters, the Ginzburg-Landau parameter and the intensity of the applied magnetic field, and acts on complex-valued functions and vector fields. We establish a formula for the distribution of the L 2-norm of the minimizing complex-valued function (order parameter). The formula is valid in the regime where the Ginzburg-Landau parameter is large and the applied magnetic field is close to and strictly below the second critical field—the threshold value corresponding to the transition from the superconducting to the normal phase in the bulk of the sample. Earlier results are valid in 2D domains and for the L 4-norm in 3D domains.

  12. 3D Magnetotelluic characterization of the Coso GeothermalField

    SciTech Connect

    Newman, Gregory A.; Hoversten, G. Michael; Wannamaker, Philip E.; Gasperikova, Erika

    2007-04-23

    -dimensional conductivitymodel. Initial analysis of the Coso MT data was carried out using 2D MTimaging. An initial 3D conductivity model was constructed from a seriesof 2D resistivity images obtained using the inline electric fieldmeasurements (Zyx impedance elements) along several measurementtransects. This model was then refined through a 3D inversion process.This model shows the controlling geological structures possiblyinfluencing well production at Coso and correlations with mapped surfacefeatures such as faults and regional geoelectric strike. The 3D modelalso illustrates the refinement in positioning of conductivity contactswhen compared to isolated 2D inversion transects. The conductivity modelhas also been correlated with microearthquake locations, well fluidproduction intervals and most importantly with an acoustic and shearvelocity model derived by Wu and Lees (1999). This later correlationshows the near-vertical high conductivity structure on the eastern flankof the producing field is also a zone of increased acoustic velocity andincreased Vp/Vs ratio bounded by mapped fault traces. South of theDevil's Kitchen is an area of high geothermal well density, where highlyconductive near surface material is interpreted as a clay cap alterationzone manifested from the subsurface geothermal fluids and relatedgeochemistry. Beneath the clay cap, however, the conductivity isnondescript, whereas the Vp/Vs ratio is enhanced over the productionintervals. It is recommended that more MT data sites be acquired to thesouthwest of the Devil's Kitchen area to better refine the conductivitymodel in that area.

  13. 3-D Finite Element Analyses of the Egan Cavern Field

    SciTech Connect

    Klamerus, E.W.; Ehgartner, B.L.

    1999-02-01

    Three-dimensional finite element analyses were performed for the two gas-filled storage caverns at the Egan field, Jennings dome, Louisiana. The effects of cavern enlargement on surface subsidence, storage loss, and cavern stability were investigated. The finite element model simulated the leaching of caverns to 6 and 8 billion cubic feet (BCF) and examined their performance at various operating conditions. Operating pressures varied from 0.15 psi/ft to 0.9 psi/ft at the bottom of the lowest cemented casing. The analysis also examined the stability of the web or pillar of salt between the caverns under differential pressure loadings. The 50-year simulations were performed using JAC3D, a three dimensional finite element analysis code for nonlinear quasistatic solids. A damage criterion based on onset of dilatancy was used to evaluate cavern instability. Dilation results from the development of microfractures in salt and, hence, potential increases in permeability onset occurs well before large scale failure. The analyses predicted stable caverns throughout the 50-year period for the range of pressures investigated. Some localized salt damage was predicted near the bottom walls of the caverns if the caverns are operated at minimum pressure for long periods of time. Volumetric cavern closures over time due to creep were moderate to excessive depending on the salt creep properties and operating pressures. However, subsidence above the cavern field was small and should pose no problem, to surface facilities.

  14. 3D Bayesian inversion of magnetic data applied to Basse-Terre volcanic island, Guadeloupe, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Barnoud, Anne; Bouligand, Claire; Coutant, Olivier

    2015-04-01

    We linearly invert magnetic data for 3D magnetization distribution using a Bayesian methodology with a grid discretization of the space. The Bayesian approach introduces covariance matrices to regularize the ill-posed problem and overcome the non-uniqueness of the solution (Tarantola & Valette, 1982). The use of spatial covariance matrices and grid discretization leads to smooth and compact models. The algorithm provides 3D magnetization models along with resolution parameters extracted from the resolution matrix. The direct computation of the magnetic field includes the surface topography and assumes a linear relationship between rock magnetization and the magnetic field they produce. The methodology is applied to aeromagnetic data from the volcanic island of Basse-Terre in Guadeloupe, Lesser Antilles (Le Borgne & Le Mouël 1976, Le Mouël et al., 1979). Low magnetizations (a few A/m) allow linear inversion that takes into account polarity inversions of the geomagnetic field that occurred across the volcanic history of the island. Inverted magnetizations are consistent with paleomagnetic measurements on surface samples (Carlut et al., 2000 ; Samper et al., 2007). The resulting 3D model is validated against a 2D inversion performed in the Fourier domain (Parker & Huestis, 1974; Bouligand et al., 2014). The 3D distribution of magnetization helps identifying the different volcanic edifices that build the island both at the surface and up to 3 km depth.

  15. A remark on the Beale-Kato-Majda criterion for the 3D MHD equations with zero magnetic diffusivity

    NASA Astrophysics Data System (ADS)

    Gala, Sadek; Ragusa, Maria Alessandra

    2016-06-01

    In this work, we show that a smooth solution of the 3D MHD equations with zero magnetic diffusivity in the whole space ℝ3 breaks down if and only if a certain norm of the magnetic field blows up at the same time.

  16. Magnetic engineering in 3d transition metals on phosphorene by strain

    NASA Astrophysics Data System (ADS)

    Cai, Xiaolin; Niu, Chunyao; Wang, Jianjun; Yu, Weiyang; Ren, XiaoYan; Zhu, Zhili

    2017-04-01

    Using first-principles density functional theory (DFT) calculations, we systematically investigate the strain effects on the adsorption energies, magnetic ordering and electronic properties of 3d transition metal (TM) atoms (from Sc to Co) adsorbed on phosphorene (P). We find that the adsorption energy of TM can be enhanced by compressive strain whereas weakened by tensile strain. Our results show that strain plays a decisive role in the magnetic moments as well as the magnetic coupling states of TM adatoms. Importantly, the transitions from antiferromagnetic (AFM) state to ferromagnetic (FM) state or to another different AFM ordering can be induced by strain effect. In addition, we observe the semiconductor to metal or half-metal transitions in some TM@P systems by applying strain. Our findings shed a new light on precisely engineering the magnetic properties and electronic properties of the TM@P systems, which will have great potential applications in spin electronics and other related fields.

  17. A 3-D Magnetic Analysis of a Linear Alternator For a Stirling Power System

    NASA Technical Reports Server (NTRS)

    Geng, Steven M.; Schwarze, Gene E.; Niedra, Janis M.

    2000-01-01

    The NASA Glenn Research Center and the Department of Energy (DOE) are developing advanced radioisotope Stirling convertors, under contract with Stirling Technology Company (STC), for space applications. Of critical importance to the successful development of the Stirling convertor for space power applications is the development of a lightweight and highly efficient linear alternator. This paper presents a 3-D finite element method (FEM) approach for evaluating Stirling convertor linear alternators. Preliminary correlations with open-circuit voltage measurements provide an encouraging level of confidence in the model. Spatial plots of magnetic field strength (H) are presented in the region of the exciting permanent magnets. These plots identify regions of high H, where at elevated temperature and under electrical load, the potential to alter the magnetic moment of the magnets exists. This implies the need for further testing and analysis.

  18. Treatment envelope evaluation in transcranial magnetic resonance-guided focused ultrasound utilizing 3D MR thermometry

    PubMed Central

    2014-01-01

    Background Current clinical targets for transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) are all located close to the geometric center of the skull convexity, which minimizes challenges related to focusing the ultrasound through the skull bone. Non-central targets will have to be reached to treat a wider variety of neurological disorders and solid tumors. Treatment envelope studies utilizing two-dimensional (2D) magnetic resonance (MR) thermometry have previously been performed to determine the regions in which therapeutic levels of FUS can currently be delivered. Since 2D MR thermometry was used, very limited information about unintended heating in near-field tissue/bone interfaces could be deduced. Methods In this paper, we present a proof-of-concept treatment envelope study with three-dimensional (3D) MR thermometry monitoring of FUS heatings performed in a phantom and a lamb model. While the moderate-sized transducer used was not designed for transcranial geometries, the 3D temperature maps enable monitoring of the entire sonication field of view, including both the focal spot and near-field tissue/bone interfaces, for full characterization of all heating that may occur. 3D MR thermometry is achieved by a combination of k-space subsampling and a previously described temporally constrained reconstruction method. Results We present two different types of treatment envelopes. The first is based only on the focal spot heating—the type that can be derived from 2D MR thermometry. The second type is based on the relative near-field heating and is calculated as the ratio between the focal spot heating and the near-field heating. This utilizes the full 3D MR thermometry data achieved in this study. Conclusions It is shown that 3D MR thermometry can be used to improve the safety assessment in treatment envelope evaluations. Using a non-optimal transducer, it is shown that some regions where therapeutic levels of FUS can be delivered, as suggested by

  19. Joint inversions of two VTEM surveys using quasi-3D TDEM and 3D magnetic inversion algorithms

    NASA Astrophysics Data System (ADS)

    Kaminski, Vlad; Di Massa, Domenico; Viezzoli, Andrea

    2016-05-01

    In the current paper, we present results of a joint quasi-three-dimensional (quasi-3D) inversion of two versatile time domain electromagnetic (VTEM) datasets, as well as a joint 3D inversion of associated aeromagnetic datasets, from two surveys flown six years apart from one another (2007 and 2013) over a volcanogenic massive sulphide gold (VMS-Au) prospect in northern Ontario, Canada. The time domain electromagnetic (TDEM) data were inverted jointly using the spatially constrained inversion (SCI) approach. In order to increase the coherency in the model space, a calibration parameter was added. This was followed by a joint inversion of the total magnetic intensity (TMI) data extracted from the two surveys. The results of the inversions have been studied and matched with the known geology, adding some new valuable information to the ongoing mineral exploration initiative.

  20. Fast ion transport during applied 3D magnetic perturbations on DIII-D

    SciTech Connect

    Van Zeeland, Michael A.; Ferraro, Nathaniel M.; Grierson, Brian A.; Heidbrink, William W.; Kramer, Gerrit J.; Lasnier, Charles J.; Pace, David C.; Allen, Steve L.; Chen, Xi; Evans, Todd E.; García-Muñoz, Manuel; Hanson, Jeremy M.; Lanctot, Matthew J.; Lao, Lang L.; Meyer, William H.; Moyer, Richard A.; Nazikian, Raffi; Orlov, Dmitriy M.; Paz-Soldan, Carlos; Wingen, Andreas

    2015-06-26

    In this paper, measurements show fast ion losses correlated with applied three-dimensional (3D) fields in a variety of plasmas ranging from L-mode to resonant magnetic perturbation (RMP) edge localized mode (ELM) suppressed H-mode discharges. In DIII-D L-mode discharges with a slowly rotating $n=2$ magnetic perturbation, scintillator detector loss signals synchronized with the applied fields are observed to decay within one poloidal transit time after beam turn-off indicating they arise predominantly from prompt loss orbits. Full orbit following using M3D-C1 calculations of the perturbed fields and kinetic profiles reproduce many features of the measured losses and points to the importance of the applied 3D field phase with respect to the beam injection location in determining the overall impact on prompt beam ion loss. Modeling of these results includes a self-consistent calculation of the 3D perturbed beam ion birth profiles and scrape-off-layer ionization, a factor found to be essential to reproducing the experimental measurements. Extension of the simulations to full slowing down timescales, including fueling and the effects of drag and pitch angle scattering, show the applied $n=3$ RMPs in ELM suppressed H-mode plasmas can induce a significant loss of energetic particles from the core. With the applied $n=3$ fields, up to 8.4% of the injected beam power is predicted to be lost, compared to 2.7% with axisymmetric fields only. These fast ions, originating from minor radii $\\rho >0.7$ , are predicted to be primarily passing particles lost to the divertor region, consistent with wide field-of-view infrared periscope measurements of wall heating in $n=3$ RMP ELM suppressed plasmas. Edge fast ion ${{\\text{D}}_{\\alpha}}$ (FIDA) measurements also confirm a large change in edge fast ion profile due to the $n=3$ fields, where the effect was isolated by using short 50 ms RMP-off periods during which ELM suppression was maintained yet the fast ion profile was allowed

  1. Fast ion transport during applied 3D magnetic perturbations on DIII-D

    DOE PAGES

    Van Zeeland, Michael A.; Ferraro, Nathaniel M.; Grierson, Brian A.; ...

    2015-06-26

    In this paper, measurements show fast ion losses correlated with applied three-dimensional (3D) fields in a variety of plasmas ranging from L-mode to resonant magnetic perturbation (RMP) edge localized mode (ELM) suppressed H-mode discharges. In DIII-D L-mode discharges with a slowly rotatingmore » $n=2$ magnetic perturbation, scintillator detector loss signals synchronized with the applied fields are observed to decay within one poloidal transit time after beam turn-off indicating they arise predominantly from prompt loss orbits. Full orbit following using M3D-C1 calculations of the perturbed fields and kinetic profiles reproduce many features of the measured losses and points to the importance of the applied 3D field phase with respect to the beam injection location in determining the overall impact on prompt beam ion loss. Modeling of these results includes a self-consistent calculation of the 3D perturbed beam ion birth profiles and scrape-off-layer ionization, a factor found to be essential to reproducing the experimental measurements. Extension of the simulations to full slowing down timescales, including fueling and the effects of drag and pitch angle scattering, show the applied $n=3$ RMPs in ELM suppressed H-mode plasmas can induce a significant loss of energetic particles from the core. With the applied $n=3$ fields, up to 8.4% of the injected beam power is predicted to be lost, compared to 2.7% with axisymmetric fields only. These fast ions, originating from minor radii $$\\rho >0.7$$ , are predicted to be primarily passing particles lost to the divertor region, consistent with wide field-of-view infrared periscope measurements of wall heating in $n=3$ RMP ELM suppressed plasmas. Edge fast ion $${{\\text{D}}_{\\alpha}}$$ (FIDA) measurements also confirm a large change in edge fast ion profile due to the $n=3$ fields, where the effect was isolated by using short 50 ms RMP-off periods during which ELM suppression was maintained yet the fast ion profile

  2. Magnetic Damping of g-Jitter Driven Flows: 3-D Calculations

    NASA Technical Reports Server (NTRS)

    Shang, D. Y.; Li, B. Q.; deGroh, H. C.

    1997-01-01

    A 3-D numerical model is developed to represent the oscillating natural convection induced in a cylindrical cavity filled with Ga-doped germanium with and without the presence of an external magnetic field. The model is developed based on the penalty-finite element solution of the equations describing the transport of momentum, heat and solutal element as well as the electromagnetic field distribution in the melt pool. Automatic time step control is applied to help speed up the calculations. Numerical simulations are conducted to study the convection and magnetic damping effects as a function of frequency, directions and amplitudes of g-jitter and also the direction and magnitudes of the applied magnetic fields. The results show that the g-jitter driven flow is time dependent and exhibits a complex recirculating convection pattern in three dimensions and that an applied magnetic field can be employed to suppress this deleterious convective flow and both magnitude and orientation of the applied field are important in magnetic damping of the g-jitter induced convective flows.

  3. Using the CAVE virtual-reality environment as an aid to 3-D electromagnetic field computation

    SciTech Connect

    Turner, L.R.; Levine, D.; Huang, M.; Papka, M; Kettunen, L.

    1995-08-01

    One of the major problems in three-dimensional (3-D) field computation is visualizing the resulting 3-D field distributions. A virtual-reality environment, such as the CAVE, (CAVE Automatic Virtual Environment) is helping to overcome this problem, thus making the results of computation more usable for designers and users of magnets and other electromagnetic devices. As a demonstration of the capabilities of the CAVE, the elliptical multipole wiggler (EMW), an insertion device being designed for the Advanced Photon Source (APS) now being commissioned at Argonne National Laboratory (ANL), wa made visible, along with its fields and beam orbits. Other uses of the CAVE in preprocessing and postprocessing computation for electromagnetic applications are also discussed.

  4. Determining 3D flow fields via multi-camera light field imaging.

    PubMed

    Truscott, Tadd T; Belden, Jesse; Nielson, Joseph R; Daily, David J; Thomson, Scott L

    2013-03-06

    In the field of fluid mechanics, the resolution of computational schemes has outpaced experimental methods and widened the gap between predicted and observed phenomena in fluid flows. Thus, a need exists for an accessible method capable of resolving three-dimensional (3D) data sets for a range of problems. We present a novel technique for performing quantitative 3D imaging of many types of flow fields. The 3D technique enables investigation of complicated velocity fields and bubbly flows. Measurements of these types present a variety of challenges to the instrument. For instance, optically dense bubbly multiphase flows cannot be readily imaged by traditional, non-invasive flow measurement techniques due to the bubbles occluding optical access to the interior regions of the volume of interest. By using Light Field Imaging we are able to reparameterize images captured by an array of cameras to reconstruct a 3D volumetric map for every time instance, despite partial occlusions in the volume. The technique makes use of an algorithm known as synthetic aperture (SA) refocusing, whereby a 3D focal stack is generated by combining images from several cameras post-capture (1). Light Field Imaging allows for the capture of angular as well as spatial information about the light rays, and hence enables 3D scene reconstruction. Quantitative information can then be extracted from the 3D reconstructions using a variety of processing algorithms. In particular, we have developed measurement methods based on Light Field Imaging for performing 3D particle image velocimetry (PIV), extracting bubbles in a 3D field and tracking the boundary of a flickering flame. We present the fundamentals of the Light Field Imaging methodology in the context of our setup for performing 3DPIV of the airflow passing over a set of synthetic vocal folds, and show representative results from application of the technique to a bubble-entraining plunging jet.

  5. An orientation measurement method based on Hall-effect sensors for permanent magnet spherical actuators with 3D magnet array.

    PubMed

    Yan, Liang; Zhu, Bo; Jiao, Zongxia; Chen, Chin-Yin; Chen, I-Ming

    2014-10-24

    An orientation measurement method based on Hall-effect sensors is proposed for permanent magnet (PM) spherical actuators with three-dimensional (3D) magnet array. As there is no contact between the measurement system and the rotor, this method could effectively avoid friction torque and additional inertial moment existing in conventional approaches. Curved surface fitting method based on exponential approximation is proposed to formulate the magnetic field distribution in 3D space. The comparison with conventional modeling method shows that it helps to improve the model accuracy. The Hall-effect sensors are distributed around the rotor with PM poles to detect the flux density at different points, and thus the rotor orientation can be computed from the measured results and analytical models. Experiments have been conducted on the developed research prototype of the spherical actuator to validate the accuracy of the analytical equations relating the rotor orientation and the value of magnetic flux density. The experimental results show that the proposed method can measure the rotor orientation precisely, and the measurement accuracy could be improved by the novel 3D magnet array. The study result could be used for real-time motion control of PM spherical actuators.

  6. A new 3-D integral code for computation of accelerator magnets

    SciTech Connect

    Turner, L.R.; Kettunen, L.

    1991-01-01

    For computing accelerator magnets, integral codes have several advantages over finite element codes; far-field boundaries are treated automatically, and computed field in the bore region satisfy Maxwell's equations exactly. A new integral code employing edge elements rather than nodal elements has overcome the difficulties associated with earlier integral codes. By the use of field integrals (potential differences) as solution variables, the number of unknowns is reduced to one less than the number of nodes. Two examples, a hollow iron sphere and the dipole magnet of Advanced Photon Source injector synchrotron, show the capability of the code. The CPU time requirements are comparable to those of three-dimensional (3-D) finite-element codes. Experiments show that in practice it can realize much of the potential CPU time saving that parallel processing makes possible. 8 refs., 4 figs., 1 tab.

  7. 3D Extended Logging for Geothermal Resources: Field Trials with the Geo-Bilt System

    SciTech Connect

    Mallan, R; Wilt, M; Kirkendall, B; Kasameyer, P

    2002-05-29

    Geo-BILT (Geothermal Borehole Induction Logging Tool) is an extended induction logging tool designed for 3D resistivity imaging around a single borehole. The tool was developed for deployment in high temperature geothermal wells under a joint program funded by the California Energy Commission, Electromagnetic Instruments (EMI) and the U.S. Department of Energy. EM1 was responsible for tool design and manufacture, and numerical modeling efforts were being addressed at Lawrence Livermore Laboratory (LLNL) and other contractors. The field deployment was done by EM1 and LLNL. The tool operates at frequencies from 2 to 42 kHz, and its design features a series of three-component magnetic sensors offset at 2 and 5 meters from a three-component magnetic source. The combined package makes it possible to do 3D resistivity imaging, deep into the formation, from a single well. The manufacture and testing of the tool was completed in spring of 2001, and the initial deployment of Geo-BILT occurred in May 2001 at the Lost Hills oil field in southern California at leases operated by Chevron USA. This site was chosen for the initial field test because of the favorable geological conditions and the availability of a number of wells suitable for tool deployment. The second deployment occurred in April 2002 at the Dixie Valley geothermal field, operated by Caithness Power LLC, in central Nevada. This constituted the first test in a high temperature environment. The Chevron site features a fiberglass-cased observation well in the vicinity of a water injector. The injected water, which is used for pressure maintenance and for secondary sweep of the heavy oil formation, has a much lower resistivity than the oil bearing formation. This, in addition to the non-uniform flow of this water, creates a 3D resistivity structure, which is analogous to conditions produced from flowing fractures adjacent to geothermal boreholes. Therefore, it is an excellent site for testing the 3D capability of

  8. Optimization of a Hybrid Magnetic Bearing for a Magnetically Levitated Blood Pump via 3-D FEA

    PubMed Central

    Cheng, Shanbao; Olles, Mark W.; Burger, Aaron F.; Day, Steven W.

    2011-01-01

    In order to improve the performance of a magnetically levitated (maglev) axial flow blood pump, three-dimensional (3-D) finite element analysis (FEA) was used to optimize the design of a hybrid magnetic bearing (HMB). Radial, axial, and current stiffness of multiple design variations of the HMB were calculated using a 3-D FEA package and verified by experimental results. As compared with the original design, the optimized HMB had twice the axial stiffness with the resulting increase of negative radial stiffness partially compensated for by increased current stiffness. Accordingly, the performance of the maglev axial flow blood pump with the optimized HMBs was improved: the maximum pump speed was increased from 6000 rpm to 9000 rpm (50%). The radial, axial and current stiffness of the HMB was found to be linear at nominal operational position from both 3-D FEA and empirical measurements. Stiffness values determined by FEA and empirical measurements agreed well with one another. The magnetic flux density distribution and flux loop of the HMB were also visualized via 3-D FEA which confirms the designers’ initial assumption about the function of this HMB. PMID:22065892

  9. Optimization of a Hybrid Magnetic Bearing for a Magnetically Levitated Blood Pump via 3-D FEA.

    PubMed

    Cheng, Shanbao; Olles, Mark W; Burger, Aaron F; Day, Steven W

    2011-10-01

    In order to improve the performance of a magnetically levitated (maglev) axial flow blood pump, three-dimensional (3-D) finite element analysis (FEA) was used to optimize the design of a hybrid magnetic bearing (HMB). Radial, axial, and current stiffness of multiple design variations of the HMB were calculated using a 3-D FEA package and verified by experimental results. As compared with the original design, the optimized HMB had twice the axial stiffness with the resulting increase of negative radial stiffness partially compensated for by increased current stiffness. Accordingly, the performance of the maglev axial flow blood pump with the optimized HMBs was improved: the maximum pump speed was increased from 6000 rpm to 9000 rpm (50%). The radial, axial and current stiffness of the HMB was found to be linear at nominal operational position from both 3-D FEA and empirical measurements. Stiffness values determined by FEA and empirical measurements agreed well with one another. The magnetic flux density distribution and flux loop of the HMB were also visualized via 3-D FEA which confirms the designers' initial assumption about the function of this HMB.

  10. 3D Magnetic Measurements of Kink and Locked Modes in DIII-D

    NASA Astrophysics Data System (ADS)

    King, J. D.; Strait, E. J.; Hanson, J. M.; Paz-Soldan, C.; Logan, N. C.; Lanctot, M. J.; Shiraki, D.

    2013-10-01

    The DIII-D magnetics diagnostic has been greatly expanded to fully characterize non-axisymmetric ``3D'' fields. Five poloidal locations now recover n <= 3 , while new HFS arrays provide poloidal spectral resolution of 7.4 cm. Initial measurements suggest externally driven kink structures deviate from MARS-F and IPEC models. These variations extend to the ideal regime, where toroidal agreement is observed. The plasma response to an n = 3 RMP increases monotonically as beta increases and q95 decreases, contrary to predictions of a screening to kink valley. Finally, the temporal evolution of the 3D eigenstructure of a slowly rotating (5 Hz) quasi-static, born locked, tearing mode provides the first evidence of an appreciable n = 2 error field, and an estimate of the phase for future correction. This new 3D capability will be used to understand and optimize control of RWMs, NTV torque, ELMs, and error field correction to extend stable tokamak operation. Work supported in part by the US Department of Energy under DE-AC05-00OR22725, DE-FC02-04ER54698, DE-FG02-95ER54309, DE-AC02-09CH11466, DE-FG02-04ER54761 and DE-AC52-07NA27344.

  11. Magnetospheric Magnetic Reconnection with Southward IMF by a 3D EMPM Simulation

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Yan, X. Y.; Cai, D. S.; Lembege, B.

    2004-01-01

    We report our new simulation results on magnetospheric magnetic reconnection with southward IMF using a 3D EMPM model, with greater resolution and more particles using the parallelized 3D HPF TRISTAN code on VPP5000 supercomputer. Main parameters used in the new simulation are: domain size is 215 x 145 x 145, grid size = 0.5 Earth radius, initial particle number is 16 per cell, the IMF is southward. Arrival of southward IMF will cause reconnection in the magnetopause, thus allowing particles to enter into the inner magnetosphere. Sunward and tailward high particle flow are observed by satellites, and these phenomena are also observed in the simulation near the neutral line (X line) of the near-Earth magnetotail. This high particle flow goes along with the reconnected island. The magnetic reconnection process contributes to direct plasma entry between the magnetosheath to the inner magnetosphere and plasma sheet, in which the entry process eats the magnetosheath plasma to plasma sheet temperatures. We investigate magnetic, electric fields, density, and current during this magnetic reconnection with southward IMF. Further investigation with this simulation will provide insight into unsolved problems, such as the triggering of storms and substorms, and the storm-substorm relationship. New results will be presented at the meeting.

  12. Effects of magnetic ripple on 3D equilibrium and alpha particle confinement in the European DEMO

    NASA Astrophysics Data System (ADS)

    Pfefferlé, D.; Cooper, W. A.; Fasoli, A.; Graves, J. P.

    2016-11-01

    An assessment of alpha particle confinement is performed in the European DEMO reference design. 3D MHD equilibria with nested flux-surfaces and single magnetic axis are obtained with the VMEC free-boundary code, thereby including the plasma response to the magnetic ripple created by the finite number of TF coils. Populations of fusion alphas that are consistent with the equilibrium profiles are evolved until slowing-down with the VENUS-LEVIS orbit code in the guiding-centre approximation. Fast ion losses through the last-closed flux-surface are numerically evaluated with two ripple models: (1) using the 3D equilibrium and (2) algebraically adding the non-axisymmetric ripple perturbation to the 2D equilibrium. By virtue of the small ripple field and its non-resonant nature, both models quantitatively agree. Differences are however noted in the toroidal location of particles losses on the last-closed flux-surface, which in the first case is 3D and in the second not. Superbanana transport, i.e. ripple-well trapping and separatrix crossing, is expected to be the dominant loss mechanism, the strongest effect on alphas being between 100-200 KeV. Above this, stochastic ripple diffusion is responsible for a rather weak loss rate, as the stochastisation threshold is observed numerically to be higher than analytic estimates. The level of ripple in the current 18 TF coil design of the European DEMO is not found to be detrimental to fusion alpha confinement.

  13. Kinematics and flow fields in 3D around swimming lamprey using light field PIV

    NASA Astrophysics Data System (ADS)

    Lehn, Andrea M.; Techet, Alexandra H.

    2016-11-01

    The fully time-resolved 3D kinematics and flow field velocities around freely swimming sea lamprey are derived using 3D light field imaging PIV. Lighthill's Elongated Body Theory (EBT) predicts that swimmers with anguilliform kinematics likened to lamprey, and similarly eels, will exhibit relatively poor propulsive efficiency. However, previous experimental studies of eel locomotion utilizing 2D PIV suggest disagreement with EBT estimates of wake properties; although, the thrust force generated by such swimmers has yet to be fully resolved using 3D measurements. A light field imaging array of multiple high-speed cameras is used to perform 3D synthetic aperture PIV around ammocoete sea lamprey (Petromyzon marinus). Fluid mechanics equations are used to determine thrust force generation, leading experimental studies closer to underpinning the physical mechanisms that enable aquatic locomotion of long, slender undulatory swimmers.

  14. Fast 3D fluid registration of brain magnetic resonance images

    NASA Astrophysics Data System (ADS)

    Leporé, Natasha; Chou, Yi-Yu; Lopez, Oscar L.; Aizenstein, Howard J.; Becker, James T.; Toga, Arthur W.; Thompson, Paul M.

    2008-03-01

    Fluid registration is widely used in medical imaging to track anatomical changes, to correct image distortions, and to integrate multi-modality data. Fluid mappings guarantee that the template image deforms smoothly into the target, without tearing or folding, even when large deformations are required for accurate matching. Here we implemented an intensity-based fluid registration algorithm, accelerated by using a filter designed by Bro-Nielsen and Gramkow. We validated the algorithm on 2D and 3D geometric phantoms using the mean square difference between the final registered image and target as a measure of the accuracy of the registration. In tests on phantom images with different levels of overlap, varying amounts of Gaussian noise, and different intensity gradients, the fluid method outperformed a more commonly used elastic registration method, both in terms of accuracy and in avoiding topological errors during deformation. We also studied the effect of varying the viscosity coefficients in the viscous fluid equation, to optimize registration accuracy. Finally, we applied the fluid registration algorithm to a dataset of 2D binary corpus callosum images and 3D volumetric brain MRIs from 14 healthy individuals to assess its accuracy and robustness.

  15. DIII-D Equilibrium Reconstructions with New 3D Magnetic Probes

    NASA Astrophysics Data System (ADS)

    Lao, Lang; Strait, E. J.; Ferraro, N. M.; Ferron, J. R.; King, J. D.; Lee, X.; Meneghini, O.; Turnbull, A. D.; Huang, Y.; Qian, J. G.; Wingen, A.

    2015-11-01

    DIII-D equilibrium reconstructions with the recently installed new 3D magnetic diagnostic are presented. In addition to providing information to allow more accurate 2D reconstructions, the new 3D probes also provide useful information to guide computation of 3D perturbed equilibria. A new more comprehensive magnetic compensation has been implemented. Algorithms are being developed to allow EFIT to reconstruct 3D perturbed equilibria making use of the new 3D probes and plasma responses from 3D MHD codes such as GATO and M3D-C1. To improve the computation efficiency, all inactive probes in one of the toroidal planes in EFIT have been replaced with new probes from other planes. Other 3D efforts include testing of 3D reconstructions using V3FIT and a new 3D variational moment equilibrium code VMOM3D. Other EFIT developments include a GPU EFIT version and new safety factor and MSE-LS constraints. The accuracy and limitation of the new probes for 3D reconstructions will be discussed. Supported by US DOE under DE-FC02-04ER54698 and DE-FG02-95ER54309.

  16. New Era in 3-D Modeling of Convection and Magnetic Dynamos in Stellar Envelopes and Cores

    NASA Astrophysics Data System (ADS)

    Toomre, J.; Augustson, K. C.; Brown, B. P.; Browning, M. K.; Brun, A. S.; Featherstone, N. A.; Miesch, M. S.

    2012-09-01

    The recent advances in asteroseismology and spectropolarimetry are beginning to provide estimates of differential rotation and magnetic structures for a range of F and G-type stars possessing convective envelopes, and in A-type stars with convective cores. It is essential to complement such observational work with theoretical studies based on 3-D simulations of highly turbulent convection coupled to rotation, shear and magnetic fields in full spherical geometries. We have so employed the anelastic spherical harmonic (ASH) code, which deals with compressible magnetohydrodynamics (MHD) in spherical shells, to examine the manner in which the global-scale convection can establish differential rotation and meridional circulations under current solar rotation rates, and these make good contact with helioseismic findings. For younger G stars rotating 3 to 5 times faster than the current Sun, the convection establishes ever stronger angular velocity contrasts between their fast equators and slow poles, and these are accompanied by prominent latitudinal temperature contrasts as well. Turning to MHD simulation of magnetic dynamo action within these younger G stars, the resulting magnetism involves wreaths of strong toroidal magnetic fields (up to 50 to 100 kG strengths) in the bulk of the convection zone, typically of opposite polarity in the northern and southern hemispheres. These fields can persist for long intervals despite being pummeled by the fast convective downflows, but they can also exhibit field reversals and cycles. Turning to shallower convective envelopes in the more luminous F-type stars that range in mass from 1.2 to 1.4 solar masses and for various rotation rates, we find that the convection can again establish solar-like differential rotation profiles with a fast equator and slow poles, but the opposite is achieved at the slower rotation rates. The F stars are also capable of building strong magnetic fields, often as wreaths, through dynamo action. We also

  17. Effect of Resonant Magnetic Perturbations on 3D equilibria in the MST RFP

    NASA Astrophysics Data System (ADS)

    Munaretto, Stefano

    2015-11-01

    The orientation of 3D, stellarator-like equilibria in the MST RFP can now be controlled with application of an m = 1 RMP. This has led to greatly improved diagnosis, revealing enhancements in both the central electron temperature and density. Coupled to a recent advance in the V3FIT code, reconstructions of the 3D equilibria have also been dramatically improved. The RMP also inhibits the generation of high-energy >20 keV electrons that is otherwise common with the 3D state. This state occurs when the normally broad spectrum of core-resonant m = 1 tearing modes condenses, with the innermost resonant mode growing to large amplitude, reaching ~ 8% of the axisymmetric field strength. This occurs in plasmas of sufficiently large Lundquist number ~ IpTe3/2, and the duration of the state is maximized with zero applied Bt (infinite toroidal beta). As the dominant mode grows, eddy current in MST's conducting shell slows the mode's rotation. This leads to locking of the 3D structure, but with an orientation that varies randomly shot to shot, making diagnosis difficult. An m = 1 RMP can now be applied with an array of saddle coils at the vertical insulated cut in the shell. With an amplitude br/B ~ 10% and a tailored temporal waveform, the RMP can force the 3D structure into any desired orientation relative to MST's diagnostics. A recent advance in V3FIT allows calculation of the substantial helical image current flowing in MST's shell, which has in turn allowed self-consistent utilization of both external and internal (Faraday rotation) measurements of the magnetic field. The ORBIT code predicts reduced stochasticity and improved confinement of high-energy electrons within the 3D structure. The suppression of these electrons by the m = 1 RMP may reflect a change to the central magnetic topology. The generation of these electrons is unaffected by non-resonant perturbations, such as m = 3. Supported by the US DOE.

  18. A symmetric, triply interlaced 3-D anionic MOF that exhibits both magnetic order and SMM behaviour.

    PubMed

    Campo, J; Falvello, L R; Forcén-Vázquez, E; Sáenz de Pipaón, C; Palacio, F; Tomás, M

    2016-11-14

    A newly prepared 3-D polymer of cobalt citrate cubanes bridged by high-spin Co(ii) centres displays both single-molecule magnet (SMM) behaviour and magnetic ordering. Triple interpenetration of the 3-D diamondoid polymers yields a crystalline solid with channels that host cations and free water molecules, with the SMM behaviour of the Co4O4 cores preserved. The octahedrally coordinated Co(ii) bridges are implicated in the onset of magnetic order at an experimentally accessible temperature.

  19. 3-D Printing: A New Method to Investigate the Effect of Deformation on Remanent Magnetization

    NASA Astrophysics Data System (ADS)

    Hirt, Ann; Mahfuj, Ali; Pané, Salvador; Gervasoni, Simone

    2017-04-01

    A fundamental assumption in paleomagnetism is that a sediment or rock retains the direction of the Earth's magnetic field over its geologic history. Sedimentary compaction or tectonic deformation can lead to the realignment of minerals, which could deflect the direction of the original natural remanent magnetization. Correction of the deflection often assumes a simple March model, in which it is assumed that the material deforms under pure shear. Sedimentary compaction and tectonic deformation involve a number of geological processes, which makes it difficult to reproduce these processes on a laboratory scale. Redepositional experiments have been carried out to examine how remanent magnetization is affected by sedimentary compaction, but little experimental data is available for the deformation of rocks. Previous experiments used deformation rigs to subject rocks to compactional or torsional deformation; however, the remanent magnetization of the rocks was often reset, due to strong magnetic fields associated with the rigs. 3-D printing opens new possibilities to create analogue rocks that can be subjected to deformation. In a proof-of-concept study, we have examined two designs to explore the applicability of the March model for simple compaction. In the first case cubes with different geometries of pore openings were printed with non-magnetic inks. The samples were then submerged in a ferrofluid and left to dry. An anhysteretic remanent magnetization (ARM) was imparted in a 50 µT DC field superimposed on a 100 mT alternating field and measured using a 2G cryogenic magnetometer. A sample holder was constructed to allow incremental, uniaxial compaction of the sample, whereby the magnetization was measured after each step. In a second set of experiments, 30 nm particles of magnetite/maghemite were incorporated into the material used to make the filament that is then used in the 3-D printer. This assures that the ferromagnetic particles are imbedded in the material

  20. 3-D Hybrid Kinetic Modeling of the Interaction Between the Solar Wind and Lunar-like Exospheric Pickup Ions in Case of Oblique/ Quasi-Parallel/Parallel Upstream Magnetic Field

    NASA Technical Reports Server (NTRS)

    Lipatov, A. S.; Farrell, W. M.; Cooper, J. F.; Sittler, E. C., Jr.; Hartle, R. E.

    2015-01-01

    The interactions between the solar wind and Moon-sized objects are determined by a set of the solar wind parameters and plasma environment of the space objects. The orientation of upstream magnetic field is one of the key factors which determines the formation and structure of bow shock wave/Mach cone or Alfven wing near the obstacle. The study of effects of the direction of the upstream magnetic field on lunar-like plasma environment is the main subject of our investigation in this paper. Photoionization, electron-impact ionization and charge exchange are included in our hybrid model. The computational model includes the self-consistent dynamics of the light (hydrogen (+), helium (+)) and heavy (sodium (+)) pickup ions. The lunar interior is considered as a weakly conducting body. Our previous 2013 lunar work, as reported in this journal, found formation of a triple structure of the Mach cone near the Moon in the case of perpendicular upstream magnetic field. Further advances in modeling now reveal the presence of strong wave activity in the upstream solar wind and plasma wake in the cases of quasiparallel and parallel upstream magnetic fields. However, little wave activity is found for the opposite case with a perpendicular upstream magnetic field. The modeling does not show a formation of the Mach cone in the case of theta(Sub B,U) approximately equal to 0 degrees.

  1. Microscopic modeling of the 3D quantum magnet Cu2OSeO3

    NASA Astrophysics Data System (ADS)

    Janson, Oleg; Rousochatzakis, Ioannis; Roessler, Ulrich; van den Brink, Jeroen; Tsirlin, Alexander; Rosner, Helge

    2013-03-01

    Unlike most undoped cuprates, the S = 1 / 2 Heisenberg magnet Cu2OSeO3 exhibits a ferrimagnetic ground state and sizable magnetoelectric coupling. Recent experiments reported magnetic-field-induced emergence of skyrmions in this material. Based on extensive DFT band structure calculations we evaluate the microscopic magnetic model, including isotropic (Heisenberg) and anisotropic (Dzyaloshinskii-Moriya) terms. We extract five relevant couplings that form a complex, but non-frustrated spin model which can be described as a pyrochlore lattice of magnetic tetrahedra. A peculiar feature of this lattice is the alternation of ``strong'' (the constituent spins are strongly coupled) and ``weak'' tetrahedra. Profiting from a separation of the energy scales we develop an effective model, treating strong tetrahedra either as a classical S = 1 object or as a coherent quantum superposition of classical states. For the latter case, we find an excellent agreement with the quantum Monte Carlo simulations of the full model and the experimental magnetization and neutron diffraction data. Quite surprising for a 3D model we find distinct manifestations of quantum fluctuations. The developed effective model can be further used to model the field-induced behavior including the formation of skyrmions.

  2. Dynamic magnetic excitations in 3d and 4f atoms and clusters

    NASA Astrophysics Data System (ADS)

    Balashov, Timofey; Miyamachi, Toshio; Schuh, Tobias; Märkl, Tobias; Bresch, Christopher; Wulfhekel, Wulf

    2014-12-01

    Spins in magnetic nanostructures can be excited by an electric current. In the inelastic scattering events, the spin of a tunneling electron provided by a scanning tunneling microscope may be flipped and angular momentum is transferred to the magnetic system. We used this technique to determine magnetic anisotropies and exchange couplings in 3d transition and 4f rare earth metal atoms and clusters on surfaces. Further, we discuss that the magnetic anisotropy, i.e. the zero field splitting, in rare earth atoms requires a fully relativistic description, in which not only the spin of the atoms but also their orbital angular momentum is taken into account. When describing the magnetic anisotropy with the Hamiltonian including all Stevens operators and combining it with spin flip scattering by conduction and tunneling electrons, we find that long spin lifetimes are theoretically expected for specific total angular momenta and crystal field symmetries and show experimental evidence that such a situation is realized in Ho on Pt(111).

  3. Online Detection of Peroxidase Using 3D Printing, Active Magnetic Mixing, and Spectra Analysis

    PubMed Central

    2017-01-01

    A new method for online detection of peroxidase (POD) using 3D printing, active magnetic mixing, fluidic control, and optical detection was developed and demonstrated in this study. The proposed POD detection system consisted of a 3D printing and active magnetic mixing based fluidic chip for online catalytic reaction, an optical detector with a fluidic flow cell for quantitative determination of the final catalysate, and a single-chip microcontroller based controller for automatic control of two rotating magnetic fields and four precise peristaltic pumps. Horseradish peroxidase (HRP) was used as research model and a linear relationship between the absorbance at the characteristic wavelength of 450 nm and the concentration of HRP of 1/4–1/128 μg mL−1 was obtained as A  =  0.257ln⁡(C) + 1.425 (R2  = 0.976). For the HRP spiked pork tests, the recoveries of HRP ranged from 93.5% to 110.4%, indicating that this proposed system was capable of detecting HRP in real samples. It has the potential to be extended for online detection of the activity of other enzymes and integration with ELISA method for biological and chemical analysis. PMID:28523275

  4. Particle energization in 3D magnetic reconnection of relativistic pair plasmas

    SciTech Connect

    Liu Wei; Yin Lin; Albright, B. J.; Bowers, K. J.; Liang, Edison P.; Li Hui

    2011-05-15

    We present large scale 3D particle-in-cell simulations to examine particle energization in magnetic reconnection of relativistic electron-positron (pair) plasmas. The initial configuration is set up as a relativistic Harris equilibrium without a guide field. These simulations are large enough to accommodate a sufficient number of tearing and kink modes. Contrary to the non-relativistic limit, the linear tearing instability is faster than the linear kink instability, at least in our specific parameters. We find that the magnetic energy dissipation is first facilitated by the tearing instability and followed by the secondary kink instability. Particles are mostly energized inside the magnetic islands during the tearing stage due to the spatially varying electric fields produced by the outflows from reconnection. Secondary kink instability leads to additional particle acceleration. Accelerated particles are, however, observed to be thermalized quickly. The large amplitude of the vertical magnetic field resulting from the tearing modes by the secondary kink modes further help thermalizing the non-thermal particles generated from the secondary kink instability. Implications of these results for astrophysics are briefly discussed.

  5. Neoclassical Tearing Mode Locking Avoidance by 3D Fields and Recovery of High Confinement

    NASA Astrophysics Data System (ADS)

    Okabayashi, M.; Budny, B.; Brennan, D.; Ferraro, N.; Grierson, B.; Jardin, S.; Logan, N.; Nazikian, R.; Tobias, B.; Wang, Z.; Strait, E.; de Grassie, J.; La Haye, R.; Paz-Soldan, C.; Taylor, Z.; Shiraki, D.; Hanson, J.; Holcomb, C.; Liu, Y.

    2016-10-01

    A slowly rotating n=1 helical magnetic field has been applied for Neoclassical Tearing Mode (NTM) locking avoidance in the DIII-D tokamak. This 3D field applied through feedback recovered a high performance configuration by rebuilding a H-mode edge and high ion temperature internal transport barrier in the plasma core, although, at present, the βn was reduced by 30%. The m/n=2/1 component of 3D field served to avoid NTM locking, while the m/n=1 and the m/n=(4-5)/1 components recover core confinement and H-mode edge. Preliminary analysis shows a quasi-steady helical plasma flow was built up around the core, mostly parallel to the equilibrium magnetic field. The optimization of m-components with n=1 is a promising approach for integrating optimizations of MHD stability from core to edge. Supported in part by the US DOE under DE-AC02-09CH11466, DE-FG02-99ER54531, DE-SC0003913 and DE-FC02-04ER54698.

  6. GPU-accelerated denoising of 3D magnetic resonance images

    SciTech Connect

    Howison, Mark; Wes Bethel, E.

    2014-05-29

    The raw computational power of GPU accelerators enables fast denoising of 3D MR images using bilateral filtering, anisotropic diffusion, and non-local means. In practice, applying these filtering operations requires setting multiple parameters. This study was designed to provide better guidance to practitioners for choosing the most appropriate parameters by answering two questions: what parameters yield the best denoising results in practice? And what tuning is necessary to achieve optimal performance on a modern GPU? To answer the first question, we use two different metrics, mean squared error (MSE) and mean structural similarity (MSSIM), to compare denoising quality against a reference image. Surprisingly, the best improvement in structural similarity with the bilateral filter is achieved with a small stencil size that lies within the range of real-time execution on an NVIDIA Tesla M2050 GPU. Moreover, inappropriate choices for parameters, especially scaling parameters, can yield very poor denoising performance. To answer the second question, we perform an autotuning study to empirically determine optimal memory tiling on the GPU. The variation in these results suggests that such tuning is an essential step in achieving real-time performance. These results have important implications for the real-time application of denoising to MR images in clinical settings that require fast turn-around times.

  7. Tuning the Origin of Magnetic Relaxation by Substituting the 3d or Rare-Earth Ions into Three Isostructural Cyano-Bridged 3d-4f Heterodinuclear Compounds.

    PubMed

    Zhang, Yan; Guo, Zhen; Xie, Shuang; Li, Hui-Li; Zhu, Wen-Hua; Liu, Li; Dong, Xun-Qing; He, Wei-Xun; Ren, Jin-Chao; Liu, Ling-Zhi; Powell, Annie K

    2015-11-02

    Three isostructural cyano-bridged 3d-4f compounds, [YFe(CN)6(hep)2(H2O)4] (1), [DyFe(CN)6(hep)2(H2O)4] (2), and [DyCo(CN)6(hep)2(H2O)4] (3), were successfully assembled by site-targeted substitution of the 3d or rare-earth ions. All compounds have been structurally characterized to display slightly distorted pentagonal-bipyramidal local coordination geometry around the rare-earth ions. Magnetic analyses revealed negligible magnetic coupling in compound 1, antiferromagnetic intradimer interaction in 2, and weak ferromagnetic coupling through dipolar-dipolar interaction in 3. Under an applied direct-current (dc) field, 1 (Hdc = 2.5 kOe, τ0 = 1.3 × 10(-7) s, and Ueff/kB = 23 K) and 3 (Hdc = 2.0 kOe, τ0 = 7.1 × 10(-11) s, and Ueff/kB = 63 K) respectively indicated magnetic relaxation behavior based on a single [Fe(III)]LS ion and a Dy(III) ion; nevertheless, 2 (Hdc = 2.0 kOe, τ0 = 9.7 × 10(-8) s, and Ueff/kB = 23 K) appeared to be a single-molecule magnet based on a cyano-bridged DyFe dimer. Compound 1, which can be regarded as a single-ion magnet of the [Fe(III)]LS ion linked to a diamagnetic Y(III) ion in a cyano-bridged heterodimer, represents one of the rarely investigated examples based on a single Fe(III) ion explored in magnetic relaxation behavior. It demonstrated that the introduction of intradimer magnetic interaction of 2 through a cyano bridge between Dy(III) and [Fe(III)]LS ions negatively affects the energy barrier and χ″(T) peak temperature compared to 3.

  8. 3D and 4D magnetic susceptibility tomography based on complex MR images

    DOEpatents

    Chen, Zikuan; Calhoun, Vince D

    2014-11-11

    Magnetic susceptibility is the physical property for T2*-weighted magnetic resonance imaging (T2*MRI). The invention relates to methods for reconstructing an internal distribution (3D map) of magnetic susceptibility values, .chi. (x,y,z), of an object, from 3D T2*MRI phase images, by using Computed Inverse Magnetic Resonance Imaging (CIMRI) tomography. The CIMRI technique solves the inverse problem of the 3D convolution by executing a 3D Total Variation (TV) regularized iterative convolution scheme, using a split Bregman iteration algorithm. The reconstruction of .chi. (x,y,z) can be designed for low-pass, band-pass, and high-pass features by using a convolution kernel that is modified from the standard dipole kernel. Multiple reconstructions can be implemented in parallel, and averaging the reconstructions can suppress noise. 4D dynamic magnetic susceptibility tomography can be implemented by reconstructing a 3D susceptibility volume from a 3D phase volume by performing 3D CIMRI magnetic susceptibility tomography at each snapshot time.

  9. Quiescence of magnetic braking and control of 3D non-resonance in KSTAR

    NASA Astrophysics Data System (ADS)

    Park, J.-K.; in, Y.; Jeon, Y. M.; Logan, N. C.; Wang, Z. R.; Menard, J. E.; Kim, J. H.; Ko, W. H.; Kstar Team

    2016-10-01

    Magnetic braking using non-axisymmetric (3D) field is a promising tool to control rotation in tokamaks and thereby micro-to-macro instabilities. Ideally magnetic braking should induce only neoclassical momentum transport, without provoking resonant instabilities or unnecessary perturbations in particle or heat transport. Indeed in KSTAR, it was shown that the 3 rows of internal coils could be used to generate highly non-resonant n =1 with backward-helicity field distribution, called -90 phasing, and to change rotation without any perturbations to other transport channels. Recent KSTAR experiments, however, have also shown that the broad-wavelength field distribution, called 0 phasing, is rather more quiescent whereas -90 phasing can be highly degrading especially in high q95 plasmas. IPEC and NTV modeling are consistent with both observations, and further provide the optimal point in coil phasing and amplitude space. Additional experiments and comparisons with modeling all imply the sensitivity of plasma response to remnant resonant field, and thus importance of non-resonance control, to accomplish quiescent magnetic braking. This work was supported by DOE Contract DE-AC02-09CH11466.

  10. 3D MHD Coronal Oscillations about a Magnetic Null Point: Application of WKB Theory

    NASA Astrophysics Data System (ADS)

    McLaughlin, J. A.; Ferguson, J. S. L.; Hood, A. W.

    2008-09-01

    This paper is a demonstration of how the WKB approximation can be used to help solve the linearised 3D MHD equations. Using Charpit’s method and a Runge Kutta numerical scheme, we have demonstrated this technique for a potential 3D magnetic null point, B=[ x, ɛ y,-( ɛ+1) z]. Under our cold-plasma assumption, we have considered two types of wave propagation: fast magnetoacoustic and Alfvén waves. We find that the fast magnetoacoustic wave experiences refraction towards the magnetic null point and that the effect of this refraction depends upon the Alfvén speed profile. The wave and thus the wave energy accumulate at the null point. We have found that current buildup is exponential and the exponent is dependent upon ɛ. Thus, for the fast wave there is preferential heating at the null point. For the Alfvén wave, we find that the wave propagates along the field lines. For an Alfvén wave generated along the fan plane, the wave accumulates along the spine. For an Alfvén wave generated across the spine, the value of ɛ determines where the wave accumulation will occur: fan plane ( ɛ=1), along the x-axis (0< ɛ<1) or along the y-axis ( ɛ>1). We have shown analytically that currents build up exponentially, leading to preferential heating in these areas. The work described here highlights the importance of understanding the magnetic topology of the coronal magnetic field for the location of wave heating.

  11. Sawtooth mitigation in 3D MHD tokamak modelling with applied magnetic perturbations

    NASA Astrophysics Data System (ADS)

    Bonfiglio, D.; Veranda, M.; Cappello, S.; Chacón, L.; Escande, D. F.

    2017-01-01

    The effect of magnetic perturbations (MPs) on the sawtoothing dynamics of the internal kink mode in the tokamak is discussed in the framework of nonlinear 3D MHD modelling. Numerical simulations are performed with the pixie3d code (Chacón 2008 Phys. Plasmas 15 056103) based on a D-shaped configuration in toroidal geometry. MPs are applied as produced by two sets of coils distributed along the toroidal direction, one set located above and the other set below the outboard midplane, like in experimental devices such as DIII-D and ASDEX Upgrade. The capability of n  =  1 MPs to affect quasi-periodic sawteeth is shown to depend on the toroidal phase difference Δ φ between the perturbations produced by the two sets of coils. In particular, sawtooth mitigation is obtained for the Δ φ =π phasing, whereas no significant effect is observed for Δ φ =0 . Numerical findings are explained by the interplay between different poloidal harmonics in the spectrum of applied MPs, and appear to be consistent with experiments performed in the DIII-D device. Sawtooth mitigation and stimulation of self-organized helical states by applied MPs have been previously demonstrated in both circular tokamak and reversed-field pinch (RFP) experiments in the RFX-mod device, and in related 3D MHD modelling.

  12. Automated objective characterization of visual field defects in 3D

    NASA Technical Reports Server (NTRS)

    Fink, Wolfgang (Inventor)

    2006-01-01

    A method and apparatus for electronically performing a visual field test for a patient. A visual field test pattern is displayed to the patient on an electronic display device and the patient's responses to the visual field test pattern are recorded. A visual field representation is generated from the patient's responses. The visual field representation is then used as an input into a variety of automated diagnostic processes. In one process, the visual field representation is used to generate a statistical description of the rapidity of change of a patient's visual field at the boundary of a visual field defect. In another process, the area of a visual field defect is calculated using the visual field representation. In another process, the visual field representation is used to generate a statistical description of the volume of a patient's visual field defect.

  13. 3D simulation of coaxial carbon nanotube field effect transistor

    NASA Astrophysics Data System (ADS)

    Hien, Dinh Sy; Thi Luong, Nguyen; Tuan, Thi Tran Anh; Viet Nga, Dinh

    2009-09-01

    We provide a model of coaxial CNTFET geometry. Coaxial devices are of special interest because their geometry allows for better electrostatics. We explore the possibilities of using non-equilibrium Green's function method to get I-V characteristics for CNTFETs. This simulator also includes a graphic user interface (GUI) of Matlab. We review the capabilities of the simulator, and give examples of typical CNTFET's 3D simulations (current-voltage characteristics are a function of parameters such as the length of CNTFET, gate thickness and temperature). The obtained I-V characteristics of the CNTFET are also presented by analytical equations.

  14. The impact of 3D fields on tearing mode stability of H-modes

    NASA Astrophysics Data System (ADS)

    Buttery, R. J.; Gerhardt, S.; La Haye, R. J.; Liu, Y. Q.; Reimerdes, H.; Sabbagh, S.; Chu, M. S.; Osborne, T. H.; Park, J.-K.; Pinsker, R. I.; Strait, E. J.; Yu, J. H.; DIII-D, the; NSTX Teams

    2011-07-01

    New processes have been discovered in the interaction of 3D fields with tearing mode stability at low torque and modest β on DIII-D and NSTX. These are thought to arise from the plasma response at the tearing resonant surface, which theoretically is expected to depend strongly on plasma rotation and underlying intrinsic tearing stability. This leads to sensitivities additional to those previously identified at low density where the plasma rotation is more readily stopped, or at high βN where ideal MHD responses amplify the fields (where βN is the plasma β divided by the ratio of plasma current to minor radius multiplied by toroidal field). It is found that the threshold size for 3D fields to induce modes tends to zero as the natural tearing βN limit is approached. 3D field sensitivity is further enhanced at low rotation, with magnetic probing detecting an increased response to applied fields in such regimes. Modelling with the MARS-F code confirms the interpretation with the usual plasma screening response breaking down in low rotation plasmas and a tearing response developing, opening the door to additional sensitivities to β and the current profile. Typical field thresholds to induce modes in torque-free βN ~ 1.5 H-modes are well below those in ohmic plasmas or plasmas near the ideal βN limit. The strong interaction with the tearing mode βN limit is identified through rotation shear, which is decreased by the 3D field, leading to decreased tearing stability. Thus both locked and rotating mode field thresholds can be considered in terms of a torque balance, with sufficient braking leading to destabilization of a mode. On this basis new measurements of the principal parameter scalings for error field threshold have been obtained in torque-free H-modes leading to new predictions for error field sensitivity in ITER. The scalings have similar exponents to ohmic plasmas, but with seven times lower threshold at the ITER baseline βN value of 1.8, and a linear

  15. 3D Electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies

    NASA Astrophysics Data System (ADS)

    Deca, J.; Lapenta, G.; Divin, A. V.; Lembege, B.; Markidis, S.

    2013-12-01

    Unlike the Earth and Mercury, our Moon has no global magnetic field and is therefore not shielded from the impinging solar wind by a magnetosphere. However, lunar magnetic field measurements made by the Apollo missions provided direct evidence that the Moon has regions of small-scale crustal magnetic fields, ranging up to a few 100km in scale size with surface magnetic field strengths up to hundreds of nanoTeslas. More recently, the Lunar Prospector spacecraft has provided high-resolution observations allowing to construct magnetic field maps of the entire Moon, confirming the earlier results from Apollo, but also showing that the lunar plasma environment is much richer than earlier believed. Typically the small-scale magnetic fields are non-dipolar and rather tiny compared to the lunar radius and mainly clustered on the far side of the moon. Using iPic3D we present the first 3D fully kinetic and electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies. We study the behaviour of a dipole model with variable surface magnetic field strength under changing solar wind conditions and confirm that lunar crustal magnetic fields may indeed be strong enough to stand off the solar wind and form a mini-magnetosphere, as suggested by MHD and hybrid simulations and spacecraft observations. 3D-PIC simulations reveal to be very helpful to analyze the diversion/braking of the particle flux and the characteristics of the resulting particles accumulation. The particle flux to the surface is significantly reduced at the magnetic anomaly, surrounded by a region of enhanced density due to the magnetic mirror effect. Second, the ability of iPic3D to resolve all plasma components (heavy ions, protons and electrons) allows to discuss in detail the electron physics leading to the highly non-adiabatic interactions expected as well as the implications for solar wind shielding of the lunar surface, depending on the scale size (solar wind protons

  16. Modeling of 3D magnetic equilibrium effects on edge turbulence stability during RMP ELM suppression in tokamaks

    DOE PAGES

    Wilcox, R. S.; Wingen, Andreas; Cianciosa, Mark R.; ...

    2017-07-28

    Some recent experimental observations have found turbulent fluctuation structures that are non-axisymmetric in a tokamak with applied 3D fields. Here, two fluid resistive effects are shown to produce changes relevant to turbulent transport in the modeled 3D magnetohydrodynamic (MHD) equilibrium of tokamak pedestals with these 3D fields applied. Ideal MHD models are insufficient to reproduce the relevant effects. By calculating the ideal 3D equilibrium using the VMEC code, the geometric shaping parameters that determine linear turbulence stability, including the normal curvature and local magnetic shear, are shown to be only weakly modified by applied 3D fields in the DIII-D tokamak.more » These ideal MHD effects are therefore not sufficient to explain the observed changes to fluctuations and transport. Using the M3D-C1 code to model the 3D equilibrium, density is shown to be redistributed on flux surfaces in the pedestal when resistive two fluid effects are included, while islands are screened by rotation in this region. Furthermore, the redistribution of density results in density and pressure gradient scale lengths that vary within pedestal flux surfaces between different helically localized flux tubes. This would produce different drive terms for trapped electron mode and kinetic ballooning mode turbulence, the latter of which is expected to be the limiting factor for pedestal pressure gradients in DIII-D.« less

  17. 2D and 3D ordered arrays of Co magnetic nanowires

    NASA Astrophysics Data System (ADS)

    Garcia, J.; Prida, V. M.; Vega, V.; Rosa, W. O.; Caballero-Flores, R.; Iglesias, L.; Hernando, B.

    2015-06-01

    Cobalt nanowire arrays spatially distributed in 2D and 3D arrangements have been performed by pulsed electrodeposition into the pores of planar and cylindrical nanoporous anodic alumina membranes, respectively. Morphological characterization points out the good filling factor reached by electroplated Co nanowires in both kinds of alumina membranes exhibiting hexagonally self-ordered porous structures. Co nanowires grown in both kinds of alumina templates exhibit the same crystalline phases. DC magnetometry and First Order Reversal Curve (FORC) analysis were carried out in order to determine the overall magnetic behavior for both nanowire array geometries. It is found that when the Co nanowires of two kinds of arrays are perpendicularly magnetized, both hysteresis loops are identical, suggesting that neither the intrinsic magnetic behavior of the nanowires nor the collective one depend on the arrays geometry. FORC analysis performed along the radial direction of the Co nanowire arrays embedded in the cylindrical alumina template reveals that the contribution of each nanowire to the magnetization reversal process involves its specific orientation with respect to the applied field direction. Furthermore, the comparison between the magnetic properties for both kinds of Co nanowire arrays allows discussing about the effect of the cylindrical geometry of the template on the magnetostatic interaction among nanowires.

  18. Online reconstruction of 3D magnetic particle imaging data

    NASA Astrophysics Data System (ADS)

    Knopp, T.; Hofmann, M.

    2016-06-01

    Magnetic particle imaging is a quantitative functional imaging technique that allows imaging of the spatial distribution of super-paramagnetic iron oxide particles at high temporal resolution. The raw data acquisition can be performed at frame rates of more than 40 volumes s-1. However, to date image reconstruction is performed in an offline step and thus no direct feedback is available during the experiment. Considering potential interventional applications such direct feedback would be mandatory. In this work, an online reconstruction framework is implemented that allows direct visualization of the particle distribution on the screen of the acquisition computer with a latency of about 2 s. The reconstruction process is adaptive and performs block-averaging in order to optimize the signal quality for a given amount of reconstruction time.

  19. Direct-write 3D printing of NdFeB bonded magnets

    DOE PAGES

    Compton, Brett Gibson; Kemp, James William; Novikov, Timofei V.; ...

    2016-08-17

    We report a method to fabricate Nd-Fe-B bonded magnets of complex shape via extrusion-based additive manufacturing (AM), also known as 3D-printing. We have successfully formulated a 3D-printable epoxy-based ink for direct-write AM with anisotropic MQA NdFeB magnet particles that can be deposited at room temperature. The new feedstocks contain up to 40 vol.% MQA anisotropic Nd-Fe-B magnet particles, and they are shown to remain uniformly dispersed in the thermoset matrix throughout the deposition process. Ring, bar, and horseshoe-type 3D magnet structures were printed and cured in air at 100°C without degrading the magnetic properties. Lastly, this study provides a newmore » pathway for fabricating Nd-Fe-B bonded magnets with complex geometry at low temperature, and presents new opportunities for fabricating multifunctional hybrid structures and devices.« less

  20. Direct-write 3D printing of NdFeB bonded magnets

    SciTech Connect

    Compton, Brett Gibson; Kemp, James William; Novikov, Timofei V.; Pack, Robert Cody; Nlebedim, Cajetan I.; Duty, Chad Edward; Rios, Orlando; Paranthaman, M. Parans

    2016-08-17

    We report a method to fabricate Nd-Fe-B bonded magnets of complex shape via extrusion-based additive manufacturing (AM), also known as 3D-printing. We have successfully formulated a 3D-printable epoxy-based ink for direct-write AM with anisotropic MQA NdFeB magnet particles that can be deposited at room temperature. The new feedstocks contain up to 40 vol.% MQA anisotropic Nd-Fe-B magnet particles, and they are shown to remain uniformly dispersed in the thermoset matrix throughout the deposition process. Ring, bar, and horseshoe-type 3D magnet structures were printed and cured in air at 100°C without degrading the magnetic properties. Lastly, this study provides a new pathway for fabricating Nd-Fe-B bonded magnets with complex geometry at low temperature, and presents new opportunities for fabricating multifunctional hybrid structures and devices.

  1. 3D linear inversion of magnetic susceptibility data acquired by frequency domain EMI

    NASA Astrophysics Data System (ADS)

    Thiesson, J.; Tabbagh, A.; Simon, F.-X.; Dabas, M.

    2017-01-01

    Low induction number EMI instruments are able to simultaneously measure a soil's apparent magnetic susceptibility and electrical conductivity. This family of dual measurement instruments is highly useful for the analysis of soils and archeological sites. However, the electromagnetic properties of soils are found to vary over considerably different ranges: whereas their electrical conductivity varies from ≤ 0.1 to ≥ 100 mS/m, their relative magnetic permeability remains within a very small range, between 1.0001 and 1.01 SI. Consequently, although apparent conductivity measurements need to be inverted using non-linear processes, the variations of the apparent magnetic susceptibility can be approximated through the use of linear processes, as in the case of the magnetic prospection technique. Our proposed 3D inversion algorithm starts from apparent susceptibility data sets, acquired using different instruments over a given area. A reference vertical profile is defined by considering the mode of the vertical distributions of both the electrical resistivity and of the magnetic susceptibility. At each point of the mapped area, the reference vertical profile response is subtracted to obtain the apparent susceptibility variation dataset. A 2D horizontal Fourier transform is applied to these variation datasets and to the dipole (impulse) response of each instrument, a (vertical) 1D inversion is performed at each point in the spectral domain, and finally the resulting dataset is inverse transformed to restore the apparent 3D susceptibility variations. It has been shown that when applied to synthetic results, this method is able to correct the apparent deformations of a buried object resulting from the geometry of the instrument, and to restore reliable quantitative susceptibility contrasts. It also allows the thin layer solution, similar to that used in magnetic prospection, to be implemented. When applied to field data it initially delivers a level of contrast

  2. Flow properties along field lines in a 3-D tilted-dipole geometry

    NASA Technical Reports Server (NTRS)

    Pizzo, V. J.

    1995-01-01

    A 3-D MHD simulation of a global, tilted-dipole solar wind flow pattern is analyzed to determine flow properties along individual magnetic field lines. In the model, flow conditions near the Sun are chosen to provide a reasonable match to the interplanetary configuration prevailing during the recent south polar passage by Ulysses, i.e., a streamer belt inclined approximately 30 deg to the solar equator and speeds ranging from 325-800 km/s. Field lines all across the stream pattern are traced from 1 to 10 AU by following the motion of marker particles embedded in the flow. It is found that those field lines threading the core of the interaction region are subject to significant latitudinal and relative longitudinal displacement over this range of heliocentric distance. Thus, observations taken at a fixed latitude in the inner solar system sample, over the course of a solar rotation, field lines which connect to a range of latitudes in the outer heliosphere. Maps of the field line displacements are presented to help visualize these connections. In addition, it is found that depending upon the location relative to the CIR structure, the radial evolution of fluid elements frozen to different field lines can deviate considerably from that of the canonical solar wind. That is, for selected subsets of field lines, large speed changes (not just at shocks) can be experienced; the density variation can be far from 1/r(exp 2), and the magnetic field intensity need not decay monotonically with distance.

  3. GMC Collisions as Triggers of Star Formation. II. 3D Turbulent, Magnetized Simulations

    NASA Astrophysics Data System (ADS)

    Wu, Benjamin; Tan, Jonathan C.; Nakamura, Fumitaka; Van Loo, Sven; Christie, Duncan; Collins, David

    2017-02-01

    We investigate giant molecular cloud collisions and their ability to induce gravitational instability and thus star formation. This mechanism may be a major driver of star formation activity in galactic disks. We carry out a series of 3D, magnetohydrodynamics (MHD), adaptive mesh refinement simulations to study how cloud collisions trigger formation of dense filaments and clumps. Heating and cooling functions are implemented based on photo-dissociation region models that span the atomic-to-molecular transition and can return detailed diagnostic information. The clouds are initialized with supersonic turbulence and a range of magnetic field strengths and orientations. Collisions at various velocities and impact parameters are investigated. Comparing and contrasting colliding and non-colliding cases, we characterize morphologies of dense gas, magnetic field structure, cloud kinematic signatures, and cloud dynamics. We present key observational diagnostics of cloud collisions, especially: relative orientations between magnetic fields and density structures, like filaments; 13CO(J = 2-1), 13CO(J = 3-2), and 12CO(J = 8-7) integrated intensity maps and spectra; and cloud virial parameters. We compare these results to observed Galactic clouds.

  4. 3D stochastic inversion and joint inversion of potential fields for multi scale parameters

    NASA Astrophysics Data System (ADS)

    Shamsipour, Pejman

    In this thesis we present the development of new techniques for the interpretation of potential field (gravity and magnetic data), which are the most widespread economic geophysical methods used for oil and mineral exploration. These new techniques help to address the long-standing issue with the interpretation of potential fields, namely the intrinsic non-uniqueness inversion of these types of data. The thesis takes the form of three papers (four including Appendix), which have been published, or soon to be published, in respected international journals. The purpose of the thesis is to introduce new methods based on 3D stochastical approaches for: 1) Inversion of potential field data (magnetic), 2) Multiscale Inversion using surface and borehole data and 3) Joint inversion of geophysical potential field data. We first present a stochastic inversion method based on a geostatistical approach to recover 3D susceptibility models from magnetic data. The aim of applying geostatistics is to provide quantitative descriptions of natural variables distributed in space or in time and space. We evaluate the uncertainty on the parameter model by using geostatistical unconditional simulations. The realizations are post-conditioned by cokriging to observation data. In order to avoid the natural tendency of the estimated structure to lay near the surface, depth weighting is included in the cokriging system. Then, we introduce algorithm for multiscale inversion, the presented algorithm has the capability of inverting data on multiple supports. The method involves four main steps: i. upscaling of borehole parameters (It could be density or susceptibility) to block parameters, ii. selection of block to use as constraints based on a threshold on kriging variance, iii. inversion of observation data with selected block densities as constraints, and iv. downscaling of inverted parameters to small prisms. Two modes of application are presented: estimation and simulation. Finally, a novel

  5. 3D stress field simulation for Greater Munich, Germany

    NASA Astrophysics Data System (ADS)

    Ziegler, Moritz; Heidbach, Oliver; Reinecker, John; Przybycin, Anna Maria; Scheck-Wenderoth, Magdalena

    2016-04-01

    Geotechnical applications such as tunneling, storage of waste, wellbore planning, or reservoir engineering requires detailed 3D information on the rock properties and behavior of the continuum. One of the key parameters is the contemporary crustal in-situ stress state. However, generally the availability of stress data on reservoir scale is scarce or no data exists at all. Furthermore, stress data is often limited to the orientation of the maximum horizontal stress. Hence, geomechanical-numerical modelling provides an approximation of a continuous description of the 3D in-situ stress state. We present a model workflow that shows (1) how to calibrate a regional scale model of Greater Munich with stress orientations and magnitudes mainly from borehole data and (2) how to derive from the regional model boundary conditions for a local high-resolution model of a geothermal reservoir site. This approach using two models is an alternative to the required trade-off between resolution, computational cost and a sufficient number of calibration data which is otherwise inevitable for a single model. The incorporated 3D geological models contain the topography from a digital elevation model and 6 stratigraphic units with different elasto-plastic rock properties. The local model mimics the area of a planned reservoir and its resolution is significantly higher than in the regional model and down to 10 m near the planned borehole trajectories using 21×106 tetrahedron finite elements with linear approximation functions. The uncertainties of the calibrated regional model are large since no information on the magnitude of the maximum horizontal stress is available. Even in the entire Greater Munich area only two reliable leak-off tests that deliver the magnitude of the minimum horizontal stress could be used. These uncertainties are transferred also to the local model. Hence we also show how to quantify for the workflow in general the systematic uncertainties and discuss

  6. Integration of real-time 3D capture, reconstruction, and light-field display

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaoxing; Geng, Zheng; Li, Tuotuo; Pei, Renjing; Liu, Yongchun; Zhang, Xiao

    2015-03-01

    Effective integration of 3D acquisition, reconstruction (modeling) and display technologies into a seamless systems provides augmented experience of visualizing and analyzing real objects and scenes with realistic 3D sensation. Applications can be found in medical imaging, gaming, virtual or augmented reality and hybrid simulations. Although 3D acquisition, reconstruction, and display technologies have gained significant momentum in recent years, there seems a lack of attention on synergistically combining these components into a "end-to-end" 3D visualization system. We designed, built and tested an integrated 3D visualization system that is able to capture in real-time 3D light-field images, perform 3D reconstruction to build 3D model of the objects, and display the 3D model on a large autostereoscopic screen. In this article, we will present our system architecture and component designs, hardware/software implementations, and experimental results. We will elaborate on our recent progress on sparse camera array light-field 3D acquisition, real-time dense 3D reconstruction, and autostereoscopic multi-view 3D display. A prototype is finally presented with test results to illustrate the effectiveness of our proposed integrated 3D visualization system.

  7. 3D non-linear inversion of magnetic anomalies caused by prismatic bodies using differential evolution algorithm

    NASA Astrophysics Data System (ADS)

    Balkaya, Çağlayan; Ekinci, Yunus Levent; Göktürkler, Gökhan; Turan, Seçil

    2017-01-01

    3D non-linear inversion of total field magnetic anomalies caused by vertical-sided prismatic bodies has been achieved by differential evolution (DE), which is one of the population-based evolutionary algorithms. We have demonstrated the efficiency of the algorithm on both synthetic and field magnetic anomalies by estimating horizontal distances from the origin in both north and east directions, depths to the top and bottom of the bodies, inclination and declination angles of the magnetization, and intensity of magnetization of the causative bodies. In the synthetic anomaly case, we have considered both noise-free and noisy data sets due to two vertical-sided prismatic bodies in a non-magnetic medium. For the field case, airborne magnetic anomalies originated from intrusive granitoids at the eastern part of the Biga Peninsula (NW Turkey) which is composed of various kinds of sedimentary, metamorphic and igneous rocks, have been inverted and interpreted. Since the granitoids are the outcropped rocks in the field, the estimations for the top depths of two prisms representing the magnetic bodies were excluded during inversion studies. Estimated bottom depths are in good agreement with the ones obtained by a different approach based on 3D modelling of pseudogravity anomalies. Accuracy of the estimated parameters from both cases has been also investigated via probability density functions. Based on the tests in the present study, it can be concluded that DE is a useful tool for the parameter estimation of source bodies using magnetic anomalies.

  8. Ising-like chain magnetism, Arrhenius magnetic relaxation, and case against 3D magnetic ordering in β-manganese phthalocyanine (C₃₂H₁₆MnN₈).

    PubMed

    Wang, Zhengjun; Seehra, Mohindar S

    2016-04-06

    Previous magnetic studies in the organic semiconductor β-manganese phthalocyanine (β-MnPc) have reported it to be a canted ferromagnet below T(C)  ≈  8.6 K. However, the recent result of the lack of a λ-type anomaly in the specific heat versus temperature data near the quoted T(C) has questioned the presence of long-range 3-dimensional (3D) magnetic ordering in this system. In this paper, detailed measurements and analysis of the temperature (2 K-300 K) and magnetic field (up to 90 kOe) dependence of the dc and ac magnetic susceptibilities in a powder sample of β-MnPc leads us to conclude that 3D long-range magnetic ordering is absent in this material. This is supported by the Arrott plots and the lack of a peak in the ac susceptibilities, χ' and χ″, near the quoted T(C). Instead, the system can be best described as an Ising-like chain magnet with Arrhenius relaxation of the magnetization governed by an intra-layer ferromagnetic exchange constant J/k(B)  =  2.6 K and the single ion anisotropy energy parameter |D|/k(B)  =  8.3 K. The absence of 3D long range order is consistent with the measured |D|/  >  J.

  9. Ising-like chain magnetism, Arrhenius magnetic relaxation, and case against 3D magnetic ordering in β-manganese phthalocyanine (C32H16MnN8)

    NASA Astrophysics Data System (ADS)

    Wang, Zhengjun; Seehra, Mohindar S.

    2016-04-01

    Previous magnetic studies in the organic semiconductor β-manganese phthalocyanine (β-MnPc) have reported it to be a canted ferromagnet below T C  ≈  8.6 K. However, the recent result of the lack of a λ-type anomaly in the specific heat versus temperature data near the quoted T C has questioned the presence of long-range 3-dimensional (3D) magnetic ordering in this system. In this paper, detailed measurements and analysis of the temperature (2 K-300 K) and magnetic field (up to 90 kOe) dependence of the dc and ac magnetic susceptibilities in a powder sample of β-MnPc leads us to conclude that 3D long-range magnetic ordering is absent in this material. This is supported by the Arrott plots and the lack of a peak in the ac susceptibilities, χ‧ and χ″, near the quoted T C. Instead, the system can be best described as an Ising-like chain magnet with Arrhenius relaxation of the magnetization governed by an intra-layer ferromagnetic exchange constant J/k B  =  2.6 K and the single ion anisotropy energy parameter |D|/k B  =  8.3 K. The absence of 3D long range order is consistent with the measured \\mid D\\mid   >  J.

  10. IGMAS+ a new 3D Gravity, FTG and Magnetic Modeling Software

    NASA Astrophysics Data System (ADS)

    Götze, Hans-Jürgen; Schmidt, Sabine; Fichler, Christine; Planka, Christian

    2010-05-01

    Modern geophysical interpretation requires an interdisciplinary approach, particularly when considering the available amount of 'state of the art' information contained in comprehensive data bases. A combination of different geophysical surveys employing seismics, gravity and geoelectrics, together with geological and petrological studies, can provide new insights into the structures and tectonic evolution of the lithosphere and natural deposits. Interdisciplinary interpretation is essential for any numerical modelling of these structures and the processes acting on them Three-dimensional (3D) interactive modeling with the IGMAS+ software provides means for integrated processing and interpretation of geoid, gravity and magnetic fields and their gradients (full tensor), yielding improved geological interpretation. IGMAS+ is an acronym standing for "Interactive Geophysical Modelling Application System". It bases on the existing software IGMAS (http://www.gravity.uni-kiel.de/igmas), a tool developed during the past twenty years for potential field modelling. The new IGMAS+, however, will comprise the advantages of the "old" IGMAS (e.g. flexible geometry concept and a fast and stable algorithm) with automated interpretation tools and a modern graphical GUI based on leading edge insights from psychological computer graphics research and thus provide optimal man machine communication. IGMAS+ fully three-dimensional models are constructed using triangulated polyhedra and/or triangulated grids, to which constant density and/or induced and remanent susceptibility are assigned. Interactive modifications of model parameters (geometry, density, susceptibility, magnetization), access to the numerical modeling process, and direct visualization of both calculated and measured fields of gravity and magnetics, enable the interpreter to design the model as realistically as possible. IGMAS+ allows easy integration of constraining data into interactive modeling processes

  11. IGMAS+ A New 3D Gravity, FTG and Magnetic Modeling Software

    NASA Astrophysics Data System (ADS)

    Goetze, H.; Schmidt, S.; Fichler, C.; Alvers, M. R.

    2007-12-01

    Modern geophysical interpretation requires an interdisciplinary approach, particularly when considering the available amount of 'state of the art' information contained in comprehensive data bases. A combination of different geophysical surveys employing seismics, gravity and geoelectrics, together with geological and petrological studies, can provide new insights into the structures and tectonic evolution of the lithosphere and natural deposits. Interdisciplinary interpretation is essential for any numerical modelling of these structures and the processes acting on them. Three-dimensional (3D) interactive modeling with the IGMAS+ software provides means for integrated processing and interpretation of geoid, gravity and magnetic fields and their gradients (full tensor), yielding improved geological interpretation. IGMAS+ is an acronym standing for "Interactive Geophysical Modelling Application System". It bases on the existing software IGMAS (http://www.gravity.uni-kiel.de/igmas), a tool developed during the past twenty years for potential field modelling. The new IGMAS+, however, will comprise the advantages of the "old" IGMAS (e.g. flexible geometry concept and a fast and stable algorithm) with automated interpretation tools and a modern graphical GUI based on leading edge insights from psychological computer graphics research and thus provide optimal man machine communication. IGMAS+ fully three-dimensional models are constructed using triangulated polyhedra and/or triangulated grids, to which constant density and/or induced and remanent susceptibility are assigned. Interactive modifications of model parameters (geometry, density, susceptibility, magnetization), access to the numerical modeling process, and direct visualization of both calculated and measured fields of gravity and magnetics, enable the interpreter to design the model as realistically as possible. IGMAS+ allows easy integration of constraining data into interactive modeling processes

  12. Edge plasma properties with 3D magnetic perturbations in RFX-mod

    NASA Astrophysics Data System (ADS)

    Agostini, M.; Scarin, P.; Spizzo, G.; Auriemma, F.; Cappello, S.; Carraro, L.; Marrelli, L.; Spagnolo, S.; Spolaore, M.; Veranda, M.; Vianello, N.; Zuin, M.; RFX-mod Team

    2017-07-01

    The response of the edge plasma to a magnetic perturbation (MP) is studied in the RFX-mod device, in both reversed field pinch (RFP) and tokamak discharges. The use of spatially distributed diagnostics, in particular along the poloidal direction, allows a direct 3D characterization of the plasma. It is shown that there is a difference between the spectrum of the MP and that of different properties of the edge plasma, such as the floating potential, the electron pressure and the flow, for both RFP and tokamak plasmas. In particular, for RFP cases, even if the magnetic perturbation is mainly m  =  1, with the amplitude of the m  =  0 and m  =  2 sidebands negligible, the connection length to the wall of the magnetic field L cw has a more complex structure. The ergodic regions, with L cw larger than the Kolmogorov length, are due to the interaction of both m  =  1 and m  =  0 modes, showing a complex and non-monochromatic behaviour along the poloidal angle. This structure of L cw is responsible for the impure m  =  1 behaviour of the plasma wall interaction, floating potential and electron pressure. Thus the helicity of the edge plasma is quite different from that of the dominant MP.

  13. A new approach for magnetic curves in 3D Riemannian manifolds

    SciTech Connect

    Bozkurt, Zehra Gök, Ismail Yaylı, Yusuf Ekmekci, F. Nejat

    2014-05-15

    A magnetic field is defined by the property that its divergence is zero in a three-dimensional oriented Riemannian manifold. Each magnetic field generates a magnetic flow whose trajectories are curves called as magnetic curves. In this paper, we give a new variational approach to study the magnetic flow associated with the Killing magnetic field in a three-dimensional oriented Riemann manifold, (M{sup 3}, g). And then, we investigate the trajectories of the magnetic fields called as N-magnetic and B-magnetic curves.

  14. A new computation method for a staggered grid of 3D EM field conservative modeling

    NASA Astrophysics Data System (ADS)

    Fomenko, Elena Yu.; Mogi, Toru

    2002-05-01

    A new three-dimensional (3D) MT modeling scheme conserving electric current and magnetic flux is developed. The scheme is based on finite difference (FD) staggered rectangular non-uniform grid formulation for the secondary electric field with continuous components of tangential electric and normal magnetic fields, in contrast to existing FD algorithms with a discontinuous E-field at the face of the cells. The scheme leads to a sparse 13-band complex symmetrical system of linear equations, which is effectively solved by fast and stable conjugate gradient (CG) methods. The preconditioning procedure was used to decrease the condition of a number of an ill-conditioned matrix system by several orders and stably and quickly solves the matrix system. The special module for the correction of divergence-free current J greatly increased the speed of convergence and accuracy, especially at low frequencies and for high-contrast resistivity or conductivity structures. A special procedure was developed to improve the accuracy of tangential magnetic and vertical electrical components at the Earth's surface and at the interface with a large conductivity contrast. The validity of the new algorithm was demonstrated for difficult models with high-contrast resistivity structures including topography and for COMMEMI project models.

  15. Laboratory Measurement of 3D Magnetic Reconnection of Arched Flux Tubes

    NASA Astrophysics Data System (ADS)

    Haw, Magnus; Bellan, Paul M.

    2015-11-01

    An experiment has been constructed to collide two arched magnetic flux tubes at different angles with fully 3D, non-symmetric geometry. The configuration is designed to mimic sheared solar arcades and evaluate the importance of magnetic reconnection in such systems. Time resolved (1MHz) 3D magnetic measurements are taken with a multi-channel 3D magnetic probe. Preliminary analysis shows good agreement between calculated current density and external current diagnostics. Additional simultaneous diagnostics include voltage probes, fast camera imaging, and a 12-channel spectrometer. The spectrometer measures temperature, density, velocity, while the camera provides a view of global plasma behavior. Fast camera images indicate that the topology of the flux tubes evolves such that two equally sized, overlapping loops reconnect to form a small underlying loop and a large overarching loop.

  16. 3D seismic data interpretation of Boonsville Field, Texas

    NASA Astrophysics Data System (ADS)

    Alhakeem, Aamer Ali

    The Boonsville field is one of the largest gas fields in the US located in the Fort Worth Basin, north central Texas. The highest potential reservoirs reside in the Bend Conglomerate deposited during the Pennsylvanian. The Boonsville data set is prepared by the Bureau of Economic Geology at the University of Texas, Austin, as part of the secondary gas recovery program. The Boonsville field seismic data set covers an area of 5.5 mi2. It includes 38 wells data. The Bend Conglomerate is deposited in fluvio-deltaic transaction. It is subdivided into many genetic sequences which include depositions of sandy conglomerate representing the potential reserves in the Boonsville field. The geologic structure of the Boonsville field subsurface are visualized by constructing structure maps of Caddo, Davis, Runaway, Beans Cr, Vineyard, and Wade. The mapping includes time structure, depth structure, horizon slice, velocity maps, and isopach maps. Many anticlines and folds are illustrated. Karst collapse features are indicated specially in the lower Atoka. Dipping direction of the Bend Conglomerate horizons are changing from dipping toward north at the top to dipping toward east at the bottom. Stratigraphic interpretation of the Runaway Formation and the Vineyard Formation using well logs and seismic data integration showed presence of fluvial dominated channels, point bars, and a mouth bar. RMS amplitude maps are generated and used as direct hydrocarbon indicator for the targeted formations. As a result, bright spots are indicated and used to identify potential reservoirs. Petrophysical analysis is conducted to obtain gross, net pay, NGR, water saturation, shale volume, porosity, and gas formation factor. Volumetric calculations estimated 989.44 MMSCF as the recoverable original gas in-place for a prospect in the Runaway and 3.32 BSCF for a prospect in the Vineyard Formation.

  17. Lithologic identification & mapping test based on 3D inversion of magnetic and gravity

    NASA Astrophysics Data System (ADS)

    Yan, Jiayong; Lv, Qingtian; Qi, Guang; Zhao, Jinhua; Zhang, Yongqian

    2016-04-01

    Though lithologic identification & mapping to achieve ore concentration district transparent within 5km depth is the main way to realize deep fine structures study, to explore deep mineral resources and to reveal metallogenic regularity of large-scale ore district . Owing to the wide covered area, high sampling density and mature three-dimensional inversion algorithm of gravity and magnetic data, so gravity and magnetic inversion become the most likely way to achieve three-dimensional lithologic mapping at the present stage. In this paper, we take Lu-zong(Lujiang county to Zongyang county in Anhui province ,east China) ore district as a case, we proposed lithologic mapping flow based 3D inversion of gravity magnetic and then carry out the lithologic mapping test. Lithologic identification & mapping flow is as follows: 1. Analysis relations between lithology and density and magnetic susceptibility by cross plot. 2.Extracting appropriate residual anomalies from high-precision Bourger gravity and aeromagnetic. 3.Use same mesh, do 3D magnetic and gravity inversion respectively under prior information constrained, and then invert susceptibility and density 3D model. 4. According setp1, construct logical topology operations between density 3D model and susceptibility. 5.Use the logical operations, identify lithogies cell by cell in 3D mesh, and then get 3D lithological model. According this flow, we obtained three-dimensional distribution of five main type lithologies in the Lu-Zong ore district within 5km depth. The result of lithologic mapping not only showed that the shallow characteristics and surface geological mapping are basically Coincide,more importantly ,it reveals the deeper lithologic changes.The lithlogical model make up the insufficient of surface geological mapping. The lithologic mapping test results in Lu-Zong ore concentration district showed that lithological mapping using 3D inversion of gravity and magnetic is a effective method to reveal the

  18. 3D fingerprint imaging system based on full-field fringe projection profilometry

    NASA Astrophysics Data System (ADS)

    Huang, Shujun; Zhang, Zonghua; Zhao, Yan; Dai, Jie; Chen, Chao; Xu, Yongjia; Zhang, E.; Xie, Lili

    2014-01-01

    As an unique, unchangeable and easily acquired biometrics, fingerprint has been widely studied in academics and applied in many fields over the years. The traditional fingerprint recognition methods are based on the obtained 2D feature of fingerprint. However, fingerprint is a 3D biological characteristic. The mapping from 3D to 2D loses 1D information and causes nonlinear distortion of the captured fingerprint. Therefore, it is becoming more and more important to obtain 3D fingerprint information for recognition. In this paper, a novel 3D fingerprint imaging system is presented based on fringe projection technique to obtain 3D features and the corresponding color texture information. A series of color sinusoidal fringe patterns with optimum three-fringe numbers are projected onto a finger surface. From another viewpoint, the fringe patterns are deformed by the finger surface and captured by a CCD camera. 3D shape data of the finger can be obtained from the captured fringe pattern images. This paper studies the prototype of the 3D fingerprint imaging system, including principle of 3D fingerprint acquisition, hardware design of the 3D imaging system, 3D calibration of the system, and software development. Some experiments are carried out by acquiring several 3D fingerprint data. The experimental results demonstrate the feasibility of the proposed 3D fingerprint imaging system.

  19. New techniques in 3D scalar and vector field visualization

    SciTech Connect

    Max, N.; Crawfis, R.; Becker, B.

    1993-05-05

    At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ``splatting`` scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ``flow volume`` of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity.

  20. 3D Magnetic Induction Maps of Nanoscale Materials Revealed by Electron Holographic Tomography

    PubMed Central

    2015-01-01

    The investigation of three-dimensional (3D) ferromagnetic nanoscale materials constitutes one of the key research areas of the current magnetism roadmap and carries great potential to impact areas such as data storage, sensing, and biomagnetism. The properties of such nanostructures are closely connected with their 3D magnetic nanostructure, making their determination highly valuable. Up to now, quantitative 3D maps providing both the internal magnetic and electric configuration of the same specimen with high spatial resolution are missing. Here, we demonstrate the quantitative 3D reconstruction of the dominant axial component of the magnetic induction and electrostatic potential within a cobalt nanowire (NW) of 100 nm in diameter with spatial resolution below 10 nm by applying electron holographic tomography. The tomogram was obtained using a dedicated TEM sample holder for acquisition, in combination with advanced alignment and tomographic reconstruction routines. The powerful approach presented here is widely applicable to a broad range of 3D magnetic nanostructures and may trigger the progress of novel spintronic nonplanar nanodevices. PMID:27182110

  1. 3D Magnetic Induction Maps of Nanoscale Materials Revealed by Electron Holographic Tomography.

    PubMed

    Wolf, Daniel; Rodriguez, Luis A; Béché, Armand; Javon, Elsa; Serrano, Luis; Magen, Cesar; Gatel, Christophe; Lubk, Axel; Lichte, Hannes; Bals, Sara; Van Tendeloo, Gustaaf; Fernández-Pacheco, Amalio; De Teresa, José M; Snoeck, Etienne

    2015-10-13

    The investigation of three-dimensional (3D) ferromagnetic nanoscale materials constitutes one of the key research areas of the current magnetism roadmap and carries great potential to impact areas such as data storage, sensing, and biomagnetism. The properties of such nanostructures are closely connected with their 3D magnetic nanostructure, making their determination highly valuable. Up to now, quantitative 3D maps providing both the internal magnetic and electric configuration of the same specimen with high spatial resolution are missing. Here, we demonstrate the quantitative 3D reconstruction of the dominant axial component of the magnetic induction and electrostatic potential within a cobalt nanowire (NW) of 100 nm in diameter with spatial resolution below 10 nm by applying electron holographic tomography. The tomogram was obtained using a dedicated TEM sample holder for acquisition, in combination with advanced alignment and tomographic reconstruction routines. The powerful approach presented here is widely applicable to a broad range of 3D magnetic nanostructures and may trigger the progress of novel spintronic nonplanar nanodevices.

  2. Focused shape models for hip joint segmentation in 3D magnetic resonance images.

    PubMed

    Chandra, Shekhar S; Xia, Ying; Engstrom, Craig; Crozier, Stuart; Schwarz, Raphael; Fripp, Jurgen

    2014-04-01

    Deformable models incorporating shape priors have proved to be a successful approach in segmenting anatomical regions and specific structures in medical images. This paper introduces weighted shape priors for deformable models in the context of 3D magnetic resonance (MR) image segmentation of the bony elements of the human hip joint. The fully automated approach allows the focusing of the shape model energy to a priori selected anatomical structures or regions of clinical interest by preferentially ordering the shape representation (or eigen-modes) within this type of model to the highly weighted areas. This focused shape model improves accuracy of the shape constraints in those regions compared to standard approaches. The proposed method achieved femoral head and acetabular bone segmentation mean absolute surface distance errors of 0.55±0.18mm and 0.75±0.20mm respectively in 35 3D unilateral MR datasets from 25 subjects acquired at 3T with different limited field of views for individual bony components of the hip joint.

  3. Increasing the depth of field in Multiview 3D images

    NASA Astrophysics Data System (ADS)

    Lee, Beom-Ryeol; Son, Jung-Young; Yano, Sumio; Jung, Ilkwon

    2016-06-01

    A super-multiview condition simulator which can project up to four different view images to each eye is introduced. This simulator with the image having both disparity and perspective informs that the depth of field (DOF) will be extended to more than the default DOF values as the number of simultaneously but separately projected different view images to each eye increase. The DOF range can be extended to near 2 diopters with the four simultaneous view images. However, the DOF value increments are not prominent as the image with both disparity and perspective with the image with disparity only.

  4. 3-D MHD modeling and stability analysis of jet and spheromak plasmas launched into a magnetized plasma

    NASA Astrophysics Data System (ADS)

    Fisher, Dustin; Zhang, Yue; Wallace, Ben; Gilmore, Mark; Manchester, Ward; Arge, C. Nick

    2016-10-01

    The Plasma Bubble Expansion Experiment (PBEX) at the University of New Mexico uses a coaxial plasma gun to launch jet and spheromak magnetic plasma configurations into the Helicon-Cathode (HelCat) plasma device. Plasma structures launched from the gun drag frozen-in magnetic flux into the background magnetic field of the chamber providing a rich set of dynamics to study magnetic turbulence, force-free magnetic spheromaks, and shocks. Preliminary modeling is presented using the highly-developed 3-D, MHD, BATS-R-US code developed at the University of Michigan. BATS-R-US employs an adaptive mesh refinement grid that enables the capture and resolution of shock structures and current sheets, and is particularly suited to model the parameter regime under investigation. CCD images and magnetic field data from the experiment suggest the stabilization of an m =1 kink mode trailing a plasma jet launched into a background magnetic field. Results from a linear stability code investigating the effect of shear-flow as a cause of this stabilization from magnetic tension forces on the jet will be presented. Initial analyses of a possible magnetic Rayleigh Taylor instability seen at the interface between launched spheromaks and their entraining background magnetic field will also be presented. Work supported by the Army Research Office Award No. W911NF1510480.

  5. Resolving stellar populations with crowded field 3D spectroscopy

    NASA Astrophysics Data System (ADS)

    Kamann, S.; Wisotzki, L.; Roth, M. M.

    2013-01-01

    We describe a new method of extracting the spectra of stars from observations of crowded stellar fields with integral field spectroscopy (IFS). Our approach extends the well-established concept of crowded field photometry in images into the domain of 3-dimensional spectroscopic datacubes. The main features of our algorithm follow. (1) We assume that a high-fidelity input source catalogue already exists, e.g. from HST data, and that it is not needed to perform sophisticated source detection in the IFS data. (2) Source positions and properties of the point spread function (PSF) vary smoothly between spectral layers of the datacube, and these variations can be described by simple fitting functions. (3) The shape of the PSF can be adequately described by an analytical function. Even without isolated PSF calibrator stars we can therefore estimate the PSF by a model fit to the full ensemble of stars visible within the field of view. (4) By using sparse matrices to describe the sources, the problem of extracting the spectra of many stars simultaneously becomes computationally tractable. We present extensive performance and validation tests of our algorithm using realistic simulated datacubes that closely reproduce actual IFS observations of the central regions of Galactic globular clusters. We investigate the quality of the extracted spectra under the effects of crowding with respect to the resulting signal-to-noise ratios (S/N) and any possible changes in the continuum level, as well as with respect to absorption line spectral parameters, radial velocities, and equivalent widths. The main effect of blending between two nearby stars is a decrease in the S/N in their spectra. The effect increases with the crowding in the field in a way that the maximum number of stars with useful spectra is always ~0.2 per spatial resolution element. This balance breaks down when exceeding a total source density of one significantly detected star per resolution element. We also explore the

  6. Local and Global 3-D Effects in the Magnetic Reconnection Experiment (MRX)

    NASA Astrophysics Data System (ADS)

    Dorfman, S.; Ji, H.; Yamada, M.; Oz, E.; Yoo, J.; Daughton, W.; Roytershteyn, V.

    2009-11-01

    One of the key open questions in Magnetic Reconnection is the nature of the mechanism that governs the reconnection rate in real astrophysical and laboratory systems. Comparisons between fully kinetic 2-D simulations of the Magnetic Reconnection Experiment (MRX) and experimental data show that the 2-D, collisionless expression for the electric field due to particle dynamics [1] does not match MRX data; related to this is a factor of 3-5 discrepancy in the layer width [2,3]. Adding collisions to the simulation leads to a broadening of the layer, but the level of collisionality present in MRX may not be high enough to resolve the discrepancy. Ongoing research on MRX explores the role of fluctuations and 3-D effects in the force balance. Significant toroidal asymmetries have been found, manifested by regions of high inductive electric field moving in the electron flow direction within the layer. Electromagnetic fluctuations in the lower hybrid frequency range [4] tend to occur in discharges with high local currents and a rapid local reconnection rate. The precise relation of these phenomena to fast reconnection is actively being investigated. [1] M. Hesse, et al., Phys. Plasmas, 6:1781 (1999). [2] Y. Ren, et al., Phys. Plasmas 15, 082113 (2008). [3] S. Dorfman, et al., Phys. Plasmas 15, 102107 (2008). [4] H. Ji, et al., Phys.Rev.Lett. 92 (2004) 115001. Supported by NDSEG, DOE, NASA, and NSF.

  7. Engineering Magnetic Anisotropy in Nanostructured 3d and 4f Ferromagnets

    NASA Astrophysics Data System (ADS)

    Hsu, Chin-Jui

    Due to the increased demand for clean energy in recent years, there is a need for the scientific community to develop technology to harvest thermal energy which is ubiquitous but mostly wasted in our environment. However, there is still no efficient approach to harvest thermal energy to date. In this study, the theory of thermomagnetic energy harvesting is reviewed and unique applications of multiferroics (ferromagnetic plus ferroelectric) are introduced. Based on an efficiency analysis using experimentally measured magneto-thermal properties of 3d transitional and 4f rare earth ferromagnetic elements, the idea of using single domain ferromagnetic elements to obtain higher thermomagnetic conversion efficiencies is proposed. In order to fabricate a ferromagnetic single domain, the magnetic anisotropy of gadolinium (Gd) and nickel (Ni) is engineered at the nanoscale. Both thin films and nanostructures are fabricated and characterized with a focus on the change of magnetic anisotropy governed by shape, crystal structure, and strain. The fabrication processes include sputtering, e-beam lithography (writing and evaporation), and focused ion beam milling. Characterization techniques involving atomic/magnetic force microscopy, energy dispersive X-ray spectroscopy, magneto-optical Kerr effect magnetometry, superconducting quantum interference device magnetometry, scanning/transmission electron microscopy, and X-ray diffraction will also be discussed. Experimental results show that the magnetic domain structure of nanostructured Ni can be stably controlled with geometric constraints or by strain induced via electric field. The magnetic properties of nanostructured Gd, on the other hand, is sensitive to crystal structure. These results provide critical information toward the use of ferromagnetic nanostructures in thermomagnetic energy harvesting and multiferroic applications.

  8. Experimental Studies on the 3D Macro- and Microphysics of Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Jara-Almonte, J.; Ji, H.; Yamada, M.; Yoo, J.; Fox, W. R., II

    2015-12-01

    Magnetic reconnection has been extensively studied in 2D geometries for many decades and considerable progress has been made in understating 2D reconnection physics, yet in real plasmas reconnection is fundamentally 3D in nature. Only recently has it become possible to study 3D reconnection using simulations, however some initial results have suggested that the inclusion of 3D effects does not strongly affect the basic properties of reconnection (e.g. reconnection rate or particle acceleration). Yet on the other hand, previous experiments, without direct 3D measurements, have implied that 3D effects could be important even in a quasi-2D system. Here we experimentally study both the (1) macro- and (2) microphysics of 3D reconnection in order to directly test the importance of 3D effects in a quasi-2D experiment. Using fully simultaneous 3D measurements, it is shown that during highly driven reconnection the macroscopic structure of the current sheet can become strongly 3D despite an essentially 2D upstream region. The correlation length along the current sheet is measured to be far shorter than suggested by kinetic simulations. Results from new experiments with stronger reconnection drive and diagnostics designed to estimate the 3D reconnection rate will be discussed. With regards to (2), the 3D microphysics, new diagnostics capable of measuring fluctuations at frequencies up to the electron cyclotron frequency (~ 300 MHz) have been developed and have identified the presence of very high frequency waves (~ 100 MHz) during asymmetric reconnection, localized to the low-density side. The detailed properties of these waves, including the measured power spectra and dispersion relation, will be discussed and compared with both previous satellite observations of high-frequency waves as well as with theoretical predictions on the generation of whistler waves during reconnection.

  9. Tuning the electronic and magnetic properties of borophene by 3d transition-metal atom adsorption

    NASA Astrophysics Data System (ADS)

    Li, J. Y.; Lv, H. Y.; Lu, W. J.; Shao, D. F.; Xiao, R. C.; Sun, Y. P.

    2016-12-01

    The electronic and magnetic properties of borophene functionalized by 3d transition metal (TM) atom adsorption are investigated by using first-principles calculations. The results show that the 3d TM atoms can be adsorbed on borophene with high binding energies ranging between 5.9 and 8.3 eV. Interestingly, the originally nonmagnetic borophene tends to be ferromagnetic when Ti, V, Cr, Mn, and Fe atoms are adsorbed, and the magnetic moments are dominated by the TM atoms. The origin of the ferromagnetism is discussed based on the Stoner criterion. Our results indicate that the magnetic properties of borophene can be effectively tuned through the adsorption of 3d TM atoms, which could have promising applications in spintronics and nanoelectronics.

  10. Connecting Global Measures of 3D Magnetic Reconnection to Local Kinetic Physics

    SciTech Connect

    Daughton, William Scott

    2015-07-16

    After giving the motivation for the work, slides present the topic under the following headings: Description of LAPD experiment; Actual simulation setup; Simple kinetic theory of ined-tied tearing; Diagnostics to characterizing 3D reconnection; Example #1 - short-tied system; and Example #2 - long line-tied system. Colorful simulations are shown for quasipotential vs field line exponentiation, field line integrated Ohms Law, and correlation with agyrotopy & energy conversion for example #1; and evolution of current density for largest case, field exponentiation vs quasi-potential, and time evolution of magnetic field lines for example #2. To satisfy line-tied boundary conditions, there is need for superposition of oblique modes--the simple two-mode approximation works surprisingly well. For force-free layers with bg >1, the fastest growing periodic modes are oblique with kxλ ~0.5. This implies a minimum length of Ly > 2πλbg. There are strong correlations between σ → Ξ → A0e (observable with spacecraft). Electron pressure tensor is the dominant non-ideal term.

  11. Multilevel-3D Bit Patterned Magnetic Media with 8 Signal Levels Per Nanocolumn

    PubMed Central

    Amos, Nissim; Butler, John; Lee, Beomseop; Shachar, Meir H.; Hu, Bing; Tian, Yuan; Hong, Jeongmin; Garcia, Davil; Ikkawi, Rabee M.; Haddon, Robert C.; Litvinov, Dmitri; Khizroev, Sakhrat

    2012-01-01

    This letter presents an experimental study that shows that a 3rd physical dimension may be used to further increase information packing density in magnetic storage devices. We demonstrate the feasibility of at least quadrupling the magnetic states of magnetic-based data storage devices by recording and reading information from nanopillars with three magnetically-decoupled layers. Magneto-optical Kerr effect microscopy and magnetic force microscopy analysis show that both continuous (thin film) and patterned triple-stack magnetic media can generate eight magnetically-stable states. This is in comparison to only two states in conventional magnetic recording. Our work further reveals that ferromagnetic interaction between magnetic layers can be reduced by combining Co/Pt and Co/Pd multilayers media. Finally, we are showing for the first time an MFM image of multilevel-3D bit patterned media with 8 discrete signal levels. PMID:22808105

  12. Multilevel-3D bit patterned magnetic media with 8 signal levels per nanocolumn.

    PubMed

    Amos, Nissim; Butler, John; Lee, Beomseop; Shachar, Meir H; Hu, Bing; Tian, Yuan; Hong, Jeongmin; Garcia, Davil; Ikkawi, Rabee M; Haddon, Robert C; Litvinov, Dmitri; Khizroev, Sakhrat

    2012-01-01

    This letter presents an experimental study that shows that a 3(rd) physical dimension may be used to further increase information packing density in magnetic storage devices. We demonstrate the feasibility of at least quadrupling the magnetic states of magnetic-based data storage devices by recording and reading information from nanopillars with three magnetically-decoupled layers. Magneto-optical Kerr effect microscopy and magnetic force microscopy analysis show that both continuous (thin film) and patterned triple-stack magnetic media can generate eight magnetically-stable states. This is in comparison to only two states in conventional magnetic recording. Our work further reveals that ferromagnetic interaction between magnetic layers can be reduced by combining Co/Pt and Co/Pd multilayers media. Finally, we are showing for the first time an MFM image of multilevel-3D bit patterned media with 8 discrete signal levels.

  13. 3D Characterization of the Magnetic Signature of a Medium Sized Impact Crater at Odessa, TX

    NASA Astrophysics Data System (ADS)

    Robinson, A.; Soule, D.; Everett, M.; Rodman, T.; Mangue Ndong, M.; Pereira, A.; Platt, P.; Trahan, A.

    2008-12-01

    Meteorite impacts are a common occurrence throughout Earth's geologic history. Many of the surface expressions of large ancient impacts have been subsequently erased by weathering and erosion processes. The study of preserved meteorite impacts is necessary to better understand this natural hazard which has been increasingly linked to rapid climate change and mass extinctions. The 60 ka Odessa meteorite crater located in Ector Co. Texas, is unique because it is not only well-preserved, but also has been the subject of extensive geologic examination. Geologic mapping and numeric models indicate that the crater was caused by a relatively small oblique impactor. The crater rim is remarkably well exposed. Much of the ejecta blanket is present, although deeply eroded. There has been considerable site disturbance due to drilling, shaft excavation, trenching, construction of a museum, trails, and the oil/gas activity in surrounding fields. Two previous geophysical investigations have shown that our data clearly corresponds to large-scale thrust deformation. With this in mind we have performed 3D high resolution magnetic gradiometer surveys that will allow us to quantify and characterize the magnetic signature of small to medium impacts. We will tie this data set to a 3D photorealistic outcrop image provided by laser scanning with coarser-scale, below-ground geophysical information. Our geophysical imagery provides a useful constraint on numerical simulations of the impact and its immediate regional-scale environmental effects. This information can be used to identify impact sites whose surface expression has been erased by natural erosional processes, allowing for improved frequency estimates and improved geo-hazard assessment.

  14. Influence of Critical Current Density on Magnetic Force of Htsc Bulk above Pmr with 3D-MODELING Numerical Solutions

    NASA Astrophysics Data System (ADS)

    Lu, Yiyun; Lu, Bingjuan; Ge, Yunwang; Chen, Wenqing

    Numerical electromagnetic field simulations of high-temperature superconductors (HTSC) bulk were carried out to calculate the magnetic force between the HTSC bulk and the permanent magnet railway (PMR). A 3D-modeling numerical calculation method is proposed using the finite element method. The model is formulated with the magnetic field vector (H-method). The resulting code was written with FORTRAN language. The electric field intensity E and the current density J constitutive relation of HTSC were described with E-J power law. The Kim macro-model is used to describe critical current density Jc of HTSC bulk. Two virtual HTSC bulks were used to solve the critical current density Jc anisotropic properties of HTSC materials. A superconducting levitation system composed of one HTSC bulk and PMR is successfully investigated using the proposed method. By this method, the influence of critical current density on magnetic levitation force of the superconducting levitation system is mathematically studied.

  15. A review of 3D first-pass, whole-heart, myocardial perfusion cardiovascular magnetic resonance.

    PubMed

    Fair, Merlin J; Gatehouse, Peter D; DiBella, Edward V R; Firmin, David N

    2015-08-01

    A comprehensive review is undertaken of the methods available for 3D whole-heart first-pass perfusion (FPP) and their application to date, with particular focus on possible acceleration techniques. Following a summary of the parameters typically desired of 3D FPP methods, the review explains the mechanisms of key acceleration techniques and their potential use in FPP for attaining 3D acquisitions. The mechanisms include rapid sequences, non-Cartesian k-space trajectories, reduced k-space acquisitions, parallel imaging reconstructions and compressed sensing. An attempt is made to explain, rather than simply state, the varying methods with the hope that it will give an appreciation of the different components making up a 3D FPP protocol. Basic estimates demonstrating the required total acceleration factors in typical 3D FPP cases are included, providing context for the extent that each acceleration method can contribute to the required imaging speed, as well as potential limitations in present 3D FPP literature. Although many 3D FPP methods are too early in development for the type of clinical trials required to show any clear benefit over current 2D FPP methods, the review includes the small but growing quantity of clinical research work already using 3D FPP, alongside the more technical work. Broader challenges concerning FPP such as quantitative analysis are not covered, but challenges with particular impact on 3D FPP methods, particularly with regards to motion effects, are discussed along with anticipated future work in the field.

  16. Reconstruction of divergence-free velocity fields from cine 3D phase-contrast flow measurements.

    PubMed

    Busch, Julia; Giese, Daniel; Wissmann, Lukas; Kozerke, Sebastian

    2013-01-01

    Three-dimensional phase-contrast velocity vector field mapping shows great potential for clinical applications; however measurement inaccuracies may limit the utility and robustness of the technique. While parts of the error in the measured velocity fields can be minimized by background phase estimation in static tissue and magnetic field monitoring, considerable inaccuracies remain. The present work introduces divergence-reduction processing of 3D phase-contrast flow data based on a synergistic combination of normalized convolution and divergence-free radial basis functions. It is demonstrated that this approach effectively addresses erroneous flow for image reconstructions from both fully sampled and undersampled data. Using computer simulations and in vivo data acquired in the aorta of healthy subjects and a stenotic valve patient it is shown that divergence arising from measurement imperfections can be reduced by up to 87% resulting in improved vector field representations. Based on the results obtained it is concluded that integration of the divergence-free condition into postprocessing of vector fields presents an efficient approach to addressing flow field inaccuracies. Copyright © 2012 Wiley Periodicals, Inc.

  17. Light field 3D endoscope based on electro-wetting lens array

    NASA Astrophysics Data System (ADS)

    Lee, Jin Su; Jung, Gyu Suk; Won, Yong Hyub

    2017-02-01

    In this study, we propose light field 3D endoscope using the electro-wetting lens array. Compared to conventional light field endoscope technology, the electro-wetting micro lens array are not only switchable between 2D and 3D, but also adjusts the focal length to capture the varying images and control the diopter sufficiently fast (ms). The electro-wetting lens array has diameter 2.4mm and diopter -20D 28D with 40ms of response time, which is an appropriate to get an endoscopic image. We also compare with light field 3D endoscope using a fixed focus lens array and our proposed light field 3D endoscope under the same condition. To achieve the electro-wetting lens array, parylene C layer are deposited on the silicon through hole substrate. In this study, we focus on the electro-wetting lens array fabrication and feasibility of a light field 3D system based on the electro-wetting micro lens array, accordingly we do not assemble the whole system in the real endoscope. Although it is performed on the optical stage, we successfully captured a light field images of several objects and reproduce a 3D image. Hereafter research, we will apply extended depth-of-field algorithm in our technology to improve the 3D image resolution and depth of field.

  18. Rare meshes FEM scheme for quasi-stationary electromagnetic fields determination 3D problems

    NASA Astrophysics Data System (ADS)

    Chekmarev, D. T.; Kalinin, A. V.; Sadovsky, V. V.; Tiukhtina, A. A.

    2016-11-01

    The initial-boundary value problem for the quasi-stationary magnetic approximation of the Maxwell equations in inhomogeneous media is studied. The considered problem is reduced to the variational problem of determining the vector magnetic potential. The special gauge for vector magnetic and scalar electrical potentials is used. The well-posedness of the problems is established under general conditions on the coefficients and the applicability of the projection methods for these problems is validated. For the numerical solution of this problem provides to use the effective rare mesh FEM scheme for 3D problems. This scheme is well- proven in 3D elasticity and plasticity problems solving.

  19. The Donegal Sign Tree: A Local Legend Confirmed with Holographic Radar and 3-D Magnetics

    NASA Astrophysics Data System (ADS)

    Bechtel, T.; Cassidy, M.; Inagaki, M.; Windsor, C.; Capineri, L.; Falorni, P.; Bulleti, A.; Valentini, S.; Borgioli, G.; Ivashov, S.; Zhuravlev, A.; Razewig, V.; Vasiliev, I.; Bechtel, E.

    2009-05-01

    A tree at a crossroad in Historic Donegal, PA (founded 1722) bears unusual burls. Two are similar in size, and lie on opposite sides of the trunk at a height of six feet. Locals say that the tree engulfed an old road sign, and the geometry of the burls gives this appearance. However, the trunk between these two burls bears no welt where it sealed after swallowing the sign. In addition, there are other burls farther up the tree, which are not consistent with engulfed signs. Although the locals all know the legend of the swallowed sign, none ever actually saw the sign; not even an octogenarian who has lived at the crossroad his entire life, and recalls the tree as a child just as it is today. In order to test the veracity of the legend, this study performed subsurface imaging of the tree using holographic subsurface radar (Rascan), and 3-D measurements of the magnetic field about the tree using cesium vapor sensors. The Rascan system used is a continuous wave subsurface radar that operates at 5 discrete frequencies between 1.5 and 2.0 GHz. Reflections from subsurface objects are recorded as the phase difference pattern between an internal reference signal, and the reflected signal. Thus, it is a microwave analogy for optical holography. Rascan records reflections with two receiving antennae - parallel and perpendicular to the transmitter - so a single set of scans provides ten images; five frequencies at two polarizations. This ensures that an object at arbitrary depth will produce a strong phase difference in one of the images. As a consequence, elongate objects that are angled from the plane of scanning (e.g. a dipping sheet) produce "zebra stripes" of contrast values that vary cyclically with depth. The presence of stripes, and their relative positions in the different frequency images (the movement of which has been dubbed the "zebra shift") is useful for determining the relative depth of different portions of a dipping planar, or curved subsurface object. Rascan

  20. 3D gradient system for two B0 field directions in earth's field MRI.

    PubMed

    Lother, Steffen; Hoelscher, Uvo; Kampf, Thomas; Jakob, Peter; Fidler, Florian

    2013-12-01

    A new gradient system for earth's field magnetic resonance imaging (EFMRI) is presented that can be rotated relatively to the earth's field direction while maintaining the ability to encode images. Orthogonal components of the gradient field are exploited to reduce the number of gradient coils. Two favorable orientations of the gradient system relative to the earth's magnetic field (parallel and perpendicular) are discussed. We introduce the theory for the magnetic fields of the new gradient system and illustrate the design of the coil geometries which were worked out with the help of simulations and a numerical optimization algorithm. Field mapping measurements and imaging experiments in the two different orientations of the gradient system were carried out. Orthogonal components of the gradient field take over the role of the additionally needed gradient fields when the gradient system is rotated relative to the earth's magnetic field. The results from the field mapping and imaging experiments verify the presented theory and show the functionality of the new gradient system. The presented system demonstrates that gradient coils can be used for image encoding in multiple directions. This fact can be exploited to realize an EFMRI setup for parallel and perpendicular prepolarization with a single set of gradient coils.

  1. Relativistic MHD simulations of core-collapse GRB jets: 3D instabilities and magnetic dissipation

    NASA Astrophysics Data System (ADS)

    Bromberg, Omer; Tchekhovskoy, Alexander

    2016-02-01

    Relativistic jets are associated with extreme astrophysical phenomena, like the core collapse of massive stars in gamma-ray bursts (GRBs) and the accretion on to supermassive black holes in active galactic nuclei. It is generally accepted that these jets are powered electromagnetically, by the magnetized rotation of a central compact object (black hole or neutron star). However, how the jets produce the observed emission and survive the propagation for many orders of magnitude in distance without being disrupted by current-driven instabilities is the subject of active debate. We carry out time-dependent 3D relativistic magnetohydrodynamic (MHD) simulations of relativistic, Poynting-flux-dominated jets. The jets are launched self-consistently by the rotation of a strongly magnetized central object. This determines the natural degree of azimuthal magnetic field winding, a crucial factor that controls jet stability. We find that the jets are susceptible to two types of instability: (i) a global, external kink mode that grows on long time-scales. It bodily twists the jet, reducing its propagation velocity. We show analytically that in flat density profiles, like the ones associated with galactic cores, the external mode grows and may stall the jet. In the steep profiles of stellar envelopes the external kink weakens as the jet propagates outward. (ii) a local, internal kink mode that grows over short time-scales and causes small-angle magnetic reconnection and conversion of about half of the jet electromagnetic energy flux into heat. We suggest that internal kink instability is the main dissipation mechanism responsible for powering GRB prompt emission.

  2. Magnetic assembly of 3D cell clusters: visualizing the formation of an engineered tissue.

    PubMed

    Ghosh, S; Kumar, S R P; Puri, I K; Elankumaran, S

    2016-02-01

    Contactless magnetic assembly of cells into 3D clusters has been proposed as a novel means for 3D tissue culture that eliminates the need for artificial scaffolds. However, thus far its efficacy has only been studied by comparing expression levels of generic proteins. Here, it has been evaluated by visualizing the evolution of cell clusters assembled by magnetic forces, to examine their resemblance to in vivo tissues. Cells were labeled with magnetic nanoparticles, then assembled into 3D clusters using magnetic force. Scanning electron microscopy was used to image intercellular interactions and morphological features of the clusters. When cells were held together by magnetic forces for a single day, they formed intercellular contacts through extracellular fibers. These kept the clusters intact once the magnetic forces were removed, thus serving the primary function of scaffolds. The cells self-organized into constructs consistent with the corresponding tissues in vivo. Epithelial cells formed sheets while fibroblasts formed spheroids and exhibited position-dependent morphological heterogeneity. Cells on the periphery of a cluster were flattened while those within were spheroidal, a well-known characteristic of connective tissues in vivo. Cells assembled by magnetic forces presented visual features representative of their in vivo states but largely absent in monolayers. This established the efficacy of contactless assembly as a means to fabricate in vitro tissue models. © 2016 John Wiley & Sons Ltd.

  3. Coloring 3D line fields using Boy's real projective plane immersion.

    PubMed

    Demiralp, Cağatay; Hughes, John F; Laidlaw, David H

    2009-01-01

    We introduce a new method for coloring 3D line fields and show results from its application in visualizing orientation in DTI brain data sets. The method uses Boy's surface, an immersion of RP2 in 3D. This coloring method is smooth and one-to-one except on a set of measure zero, the double curve of Boy's surface.

  4. Accretion to magnetized stars through the Rayleigh-Taylor instability: global 3D simulations

    NASA Astrophysics Data System (ADS)

    Kulkarni, A. K.; Romanova, M. M.

    2008-05-01

    We present results of 3D simulations of magnetohydrodynamics (MHD) instabilities at the accretion disc-magnetosphere boundary. The instability is Rayleigh-Taylor, and develops for a fairly broad range of accretion rates and stellar rotation rates and magnetic fields. It manifests itself in the form of tall, thin tongues of plasma that penetrate the magnetosphere in the equatorial plane. The shape and number of the tongues changes with time on the inner disc dynamical time-scale. In contrast with funnel flows, which deposit matter mainly in the polar region, the tongues deposit matter much closer to the stellar equator. The instability appears for relatively small misalignment angles, Θ <~ 30°, between the star's rotation and magnetic axes, and is associated with higher accretion rates. The hotspots and light curves during accretion through instability are generally much more chaotic than during stable accretion. The unstable state of accretion has possible implications for quasi-periodic oscillations and intermittent pulsations from accreting systems, as well as planet migration.

  5. An industrial light-field camera applied for 3D velocity measurements in a slot jet

    NASA Astrophysics Data System (ADS)

    Seredkin, A. V.; Shestakov, M. V.; Tokarev, M. P.

    2016-10-01

    Modern light-field cameras have found their application in different areas like photography, surveillance and quality control in industry. A number of studies have been reported relatively low spatial resolution of 3D profiles of registered objects along the optical axis of the camera. This article describes a method for 3D velocity measurements in fluid flows using an industrial light-field camera and an alternative reconstruction algorithm based on a statistical approach. This method is more accurate than triangulation when applied for tracking small registered objects like tracer particles in images. The technique was used to measure 3D velocity fields in a turbulent slot jet.

  6. Analyses of Magnetic Structures of Active Region 11117 Evolution using a 3D Data-Driven Magnetohydrodynamic Model

    NASA Astrophysics Data System (ADS)

    Wu, Shi; Jiang, Chaowei; Feng, Xueshang

    We use the photospheric vector magnetograms obtained by Helioseismic and Magnetic Image (HMI) on-board the Solar Dynamic Observatory (SDO) as the boundary conditions for a Data-Driven CESE-MHD model (Jiang et al. 2012) to investigate the physical characteristics and evolution of magnetic field configurations in the corona before and after a solar eruptive event. Specifically, the evolution of AR11117 characteristics such as length of magnetic shear along the neutral line, current helicity, magnetic free energy and the energy flux across the photosphere due to flux emergence and surface flow are presented. The computed 3D magnetic field configuration are compared with AIA (Atmosphere Image Assembly) which shows remarkable resemblance. A topological analyses reveals that the small flare is correlated with a bald patch (BP, where the magnetic field is tangent to the photosphere), suggesting that the energy release of the flare is caused by magnetic reconnection associated with the BP separatrices. The total magnetic flux and energy keep increasing slightly in spite of flare, while the computed magnetic free energy drops during the flare by 10 (30) ergs which is adequate in providing the energy budget of a minor C-class confined flare as observed. Jiang, Chaowei, Xueshang, Feng, S. T Wu and Qiang Hu, Ap. J., 759:85, 2012 Nov 10

  7. Simulation of the 3-D Evolution of Electron Scale Magnetic Reconnection - Motivated by Laboratory Experiments Predictions for MMS

    NASA Astrophysics Data System (ADS)

    Buechner, J.; Jain, N.; Sharma, A.

    2013-12-01

    The four s/c of the Magnetospheric Multiscale (MMS) mission, to be launched in 2014, will use the Earth's magnetosphere as a laboratory to study the microphysics of three fundamental plasma processes. One of them is magnetic reconnection, an essentially multi-scale process. While laboratory experiments and past theoretical investigations have shown that important processes necessary to understand magnetic reconnection take place at electron scales the MMS mission for the first time will be able to resolve these scales by in space observations. For the measurement strategy of MMS it is important to make specific predictions of the behavior of current sheets with a thickness of the order of the electron skin depth which play an important role in the evolution of collisionless magnetic reconnection. Since these processes are highly nonlinear and non-local numerical simulation is needed to specify the current sheet evolution. Here we present new results about the nonlinear evolution of electron-scale current sheets starting from the linear stage and using 3-D electron-magnetohydrodynamic (EMHD) simulations. The growth rates of the simulated instabilities compared well with the growth rates obtained from linear theory. Mechanisms and conditions of the formation of flux ropes and of current filamentation will be discussed in comparison with the results of fully kinetic simulations. In 3D the X- and O-point configurations of the magnetic field formed in reconnection planes alternate along the out-of-reconnection-plane direction with the wavelength of the unstable mode. In the presence of multiple reconnection sites, the out-of-plane magnetic field can develop nested structure of quadrupoles in reconnection planes, similar to the 2-D case, but now with variations in the out-of-plane direction. The structures of the electron flow and magnetic field in 3-D simulations will be compared with those in 2-D simulations to discriminate the essentially 3D features. We also discuss

  8. Measurements of 3D velocity and scalar field for a film-cooled airfoil trailing edge

    NASA Astrophysics Data System (ADS)

    Benson, Michael J.; Elkins, Christopher J.; Eaton, John K.

    2011-08-01

    The 3D velocity and concentration fields have been measured for flow in a pressure side cutback trailing edge film cooling geometry consisting of rectangular film cooling slots separated by tapered lands. The velocity field was measured using conventional magnetic resonance velocimetry, and the concentration distribution was measured with a refined magnetic resonance concentration technique that yields experimental uncertainties for the concentration between 5 and 6%. All experiments were performed in water. A separation bubble behind the slot lip entrains coolant and promotes rapid turbulent mixing at the upper edge of the coolant jet. Vortices from inside the slot feed channel and on the upper sides of the lands rapidly distort the initially rectangular shape of the coolant stream and sweep mainstream flow toward the airfoil surface. The vortices also prevent any coolant from reaching the upper surfaces of the land. At the trailing edge, a second separation region exists in the blunt trailing edge wake. The flow forms suction side streaks behind the land tips, as well as streaks behind the slot centers on the pressure side. The peak coolant concentrations in the streaks remain above 25% through the end of the measurement domain, over 30 slot heights downstream.

  9. Effect of 3D magnetic perturbations on divertor conditions and detachment in tokamak and stellarator

    NASA Astrophysics Data System (ADS)

    Ahn, J.-W.; Briesemester, A. R.; Kobayashi, M.; Lore, J. D.; Schmitz, O.; Diallo, A.; Gray, T. K.; Lasnier, C. J.; LeBlanc, B. P.; Maingi, R.; McLean, A. G.; Sabbagh, S. A.; Soukhanovskii, V. A.

    2017-08-01

    Enhanced perpendicular heat and momentum transport induces parallel pressure loss leading to divertor detachment, which can be produced by the increase of density in 2D tokamaks. However, in the 3D configurations such as tokamaks with 3D fields and stellarators, the fraction of perpendicular transport can be higher even in a lower density regime, which could lead to the early transition to detachment without passing through the high-recycling regime. 3D fields applied to the limiter tokamak plasmas produce edge stochastic layers close to the last closed flux surface (LCFS), which can allow for enhanced perpendicular transport and indeed the absence of high recycling regime and early detachment have been observed in TEXTOR and Tore Supra. However, in the X-point divertor tokamaks with the applied 3D fields, the parallel transport is still dominant and the detachment facilitation has not been observed yet. Rather, 3D fields affected detachment adversely under certain conditions, either by preventing detachment onset as seen in DIII-D or by re-attaching the existing detached plasma as shown in NSTX. The possible way for strong 3D effects to induce access to the early detachment in divertor tokamaks appears to be via significant perpendicular loss of parallel momentum by frictional force for the counter-streaming flows between neighboring flow channels in the divertor. In principle, the adjacent lobes in the 3D divertor tokamak may generate the counter-streaming flow channels. However, an EMC3-EIRENE simulation for ITER H-mode plasmas demonstrated that screened RMP leads to significantly reduced counter-flows near the divertor target, therefore the momentum loss effect leading to detachment facilitation is expected to be small. This is consistent with the observation in LHD, which showed screening (amplification) of RMP fields in the attachment (stable detachment) case. Work for optimal parameter window for best divertor operation scenario is needed particularly for

  10. 3-D Localization Method for a Magnetically Actuated Soft Capsule Endoscope and Its Applications

    PubMed Central

    Yim, Sehyuk; Sitti, Metin

    2014-01-01

    In this paper, we present a 3-D localization method for a magnetically actuated soft capsule endoscope (MASCE). The proposed localization scheme consists of three steps. First, MASCE is oriented to be coaxially aligned with an external permanent magnet (EPM). Second, MASCE is axially contracted by the enhanced magnetic attraction of the approaching EPM. Third, MASCE recovers its initial shape by the retracting EPM as the magnetic attraction weakens. The combination of the estimated direction in the coaxial alignment step and the estimated distance in the shape deformation (recovery) step provides the position of MASCE in 3-D. It is experimentally shown that the proposed localization method could provide 2.0–3.7 mm of distance error in 3-D. This study also introduces two new applications of the proposed localization method. First, based on the trace of contact points between the MASCE and the surface of the stomach, the 3-D geometrical model of a synthetic stomach was reconstructed. Next, the relative tissue compliance at each local contact point in the stomach was characterized by measuring the local tissue deformation at each point due to the preloading force. Finally, the characterized relative tissue compliance parameter was mapped onto the geometrical model of the stomach toward future use in disease diagnosis. PMID:25383064

  11. 3D model of small-scale density cavities in the auroral magnetosphere with field-aligned current

    NASA Astrophysics Data System (ADS)

    Bespalov, P. A.; Misonova, V. G.; Savina, O. N.

    2016-09-01

    We propose a 3D model of small-scale density cavities stimulated by an auroral field-aligned current and an oscillating field-aligned current of kinetic Alfvén waves. It is shown that when the field-aligned current increases so that the electron drift velocity exceeds a value of the order of the electron thermal velocity, the plasma becomes unstable to the formation of cavities with low density and strong electric field. The condition of instability is associated with the value of the background magnetic field. In the case of a relatively weak magnetic field (where the electron gyro-radius is greater than the ion acoustic wavelength), the current instability can lead to the formation of one-dimensional cavities along the magnetic field. In the case of a stronger magnetic field (where the ion acoustic wavelength is greater than the electron gyro-radius, but still is less than the ion gyro-radius), the instability can lead to the formation of 3D density cavities. In this case, the spatial scales of the cavity, both along and across the background magnetic field, can be comparable, and at the earlier stage of the cavity formation they are of the order of the ion acoustic wavelength. Rarefactions of the cavity density are accompanied by an increase in the electric field and are limited by the pressure of bipolar electric fields that occur within them. The estimates of typical density cavity characteristics and the results of numerical solutions agree with known experimental data: small-scale structures with a sufficiently strong electric field are observed in the auroral regions with strong field-aligned current.

  12. 3D Mesh Segmentation Based on Markov Random Fields and Graph Cuts

    NASA Astrophysics Data System (ADS)

    Shi, Zhenfeng; Le, Dan; Yu, Liyang; Niu, Xiamu

    3D Mesh segmentation has become an important research field in computer graphics during the past few decades. Many geometry based and semantic oriented approaches for 3D mesh segmentation has been presented. However, only a few algorithms based on Markov Random Field (MRF) has been presented for 3D object segmentation. In this letter, we present a definition of mesh segmentation according to the labeling problem. Inspired by the capability of MRF combining the geometric information and the topology information of a 3D mesh, we propose a novel 3D mesh segmentation model based on MRF and Graph Cuts. Experimental results show that our MRF-based schema achieves an effective segmentation.

  13. LC-lens array with light field algorithm for 3D biomedical applications

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Pai; Hsieh, Po-Yuan; Hassanfiroozi, Amir; Martinez, Manuel; Javidi, Bahram; Chu, Chao-Yu; Hsuan, Yun; Chu, Wen-Chun

    2016-03-01

    In this paper, liquid crystal lens (LC-lens) array was utilized in 3D bio-medical applications including 3D endoscope and light field microscope. Comparing with conventional plastic lens array, which was usually placed in 3D endoscope or light field microscope system to record image disparity, our LC-lens array has higher flexibility of electrically changing its focal length. By using LC-lens array, the working distance and image quality of 3D endoscope and microscope could be enhanced. Furthermore, the 2D/3D switching ability could be achieved if we turn off/on the electrical power on LClens array. In 3D endoscope case, a hexagonal micro LC-lens array with 350um diameter was placed at the front end of a 1mm diameter endoscope. With applying electric field on LC-lens array, the 3D specimen would be recorded as from seven micro-cameras with different disparity. We could calculate 3D construction of specimen with those micro images. In the other hand, if we turn off the electric field on LC-lens array, the conventional high resolution 2D endoscope image would be recorded. In light field microscope case, the LC-lens array was placed in front of the CMOS sensor. The main purpose of LC-lens array is to extend the refocusing distance of light field microscope, which is usually very narrow in focused light field microscope system, by montaging many light field images sequentially focusing on different depth. With adjusting focal length of LC-lens array from 2.4mm to 2.9mm, the refocusing distance was extended from 1mm to 11.3mm. Moreover, we could use a LC wedge to electrically shift the optics axis and increase the resolution of light field.

  14. 4D Magnetic Resonance Velocimetry in a 3D printed brain aneurysm

    NASA Astrophysics Data System (ADS)

    Amili, Omid; Schiavazzi, Daniele; Coletti, Filippo

    2016-11-01

    Cerebral aneurysms are of great clinical importance. It is believed that hemodynamics play a critical role in the development, growth, and rupture of brain arteries with such condition. The flow structure in the aneurysm sac is complex, unsteady, and three-dimensional. Therefore the time-resolved measurement of the three-dimensional three-component velocity field is crucial to predict the clinical outcome. In this study magnetic resonance velocimetry is used to assess the fluid dynamics inside a 3D printed model of a giant intracranial aneurysm. We reach sub-millimeter resolution while resolving sixteen instances within the cardiac cycle. The physiological flow waveform is imposed using an in-house built pump in a flow circuit where the cardiovascular impedance is matched. The flow evolution over time is reconstructed in detail. The complex flow structure is characterized by vortical and helical motions that reside in the aneurysm for most part of the cycle. The 4D pressured distribution is also reconstructed from the velocity field. The present case study was used in a previous CFD challenge, therefore these results may provide useful experimental comparison for simulations performed by other research groups.

  15. Electronic structure and local magnetism of 3d-5d impurity substituted CeFe2

    NASA Astrophysics Data System (ADS)

    Das, Rakesh; Das, G. P.; Srivastava, S. K.

    2016-04-01

    We present here a systematic first-principles study of electronic structure and local magnetic properties of Ce[Fe0.75M0.25]2 compounds, where M is a 3d, 4d or 5d transition or post-transition element, using the generalized gradient approximation of the density functional theory. The d-f band hybridizations existing in CeFe2 get modified by the impurity M in an orderly manner across a period for each impurity series: the hybridization is strongest for the Mn group impurity in the period and gets diminished on either side of it. The weakening of the d-f hybridization strength is also associated with a relative localization of the Ce 4f states with respect to the delocalized 4f states in CeFe2. The above effects are most prominent for 3d impurity series, while for 4d and 5d impurities, the hybridizations and relocalizations are relatively weak due primarily to the relatively extended nature of 4d and 5d wavefunctions. The Ce local moment is found to decrease from the CeFe2 value in proportion to the strength of relocalization, thus following almost the same orderly trend as obeyed by the d-f hybridization. Further, depending on the way the spin-up and spin-down densities of states of an impurity shift relative to the Fermi energy, the impurity local moments are highest for Mn or Fe group, reduce on either side, become zero for Ni to Ga, and are small but negative for V and Ti. The Ce hyperfine field is found to follow the M local moment in a linear fashion, and vice-versa.

  16. (1 + 3)-D topological superconductors: Screening and confinement in the presence of external fields

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio; Helayël-Neto, José A.

    2016-12-01

    Adopting the gauge-invariant and path-dependent variables formalism, we compute the interaction energy for a topological field theory describing (1 + 3)-D topological superconductors in the presence of external fields. As a result, in the case of a constant electric-field strength expectation value, we show that the interaction energy describes a purely screening phase, encoded in a Yukawa potential. On the other hand, in the case of a constant magnetic-field strength and for a very small Josephson coupling constant, the particle-antiparticle binding potential displays a linear term leading to the confinement of static charge probes along with a screening contribution.

  17. Semiautomatic approaches to account for 3-D distortion of the electric field from local, near-surface structures in 3-D resistivity inversions of 3-D regional magnetotelluric data

    USGS Publications Warehouse

    Rodriguez, Brian D.

    2017-03-31

    This report summarizes the results of three-dimensional (3-D) resistivity inversion simulations that were performed to account for local 3-D distortion of the electric field in the presence of 3-D regional structure, without any a priori information on the actual 3-D distribution of the known subsurface geology. The methodology used a 3-D geologic model to create a 3-D resistivity forward (“known”) model that depicted the subsurface resistivity structure expected for the input geologic configuration. The calculated magnetotelluric response of the modeled resistivity structure was assumed to represent observed magnetotelluric data and was subsequently used as input into a 3-D resistivity inverse model that used an iterative 3-D algorithm to estimate 3-D distortions without any a priori geologic information. A publicly available inversion code, WSINV3DMT, was used for all of the simulated inversions, initially using the default parameters, and subsequently using adjusted inversion parameters. A semiautomatic approach of accounting for the static shift using various selections of the highest frequencies and initial models was also tested. The resulting 3-D resistivity inversion simulation was compared to the “known” model and the results evaluated. The inversion approach that produced the lowest misfit to the various local 3-D distortions was an inversion that employed an initial model volume resistivity that was nearest to the maximum resistivities in the near-surface layer.

  18. A cross-platform solution for light field based 3D telemedicine.

    PubMed

    Wang, Gengkun; Xiang, Wei; Pickering, Mark

    2016-03-01

    Current telehealth services are dominated by conventional 2D video conferencing systems, which are limited in their capabilities in providing a satisfactory communication experience due to the lack of realism. The "immersiveness" provided by 3D technologies has the potential to promote telehealth services to a wider range of applications. However, conventional stereoscopic 3D technologies are deficient in many aspects, including low resolution and the requirement for complicated multi-camera setup and calibration, and special glasses. The advent of light field (LF) photography enables us to record light rays in a single shot and provide glasses-free 3D display with continuous motion parallax in a wide viewing zone, which is ideally suited for 3D telehealth applications. As far as our literature review suggests, there have been no reports of 3D telemedicine systems using LF technology. In this paper, we propose a cross-platform solution for a LF-based 3D telemedicine system. Firstly, a novel system architecture based on LF technology is established, which is able to capture the LF of a patient, and provide an immersive 3D display at the doctor site. For 3D modeling, we further propose an algorithm which is able to convert the captured LF to a 3D model with a high level of detail. For the software implementation on different platforms (i.e., desktop, web-based and mobile phone platforms), a cross-platform solution is proposed. Demo applications have been developed for 2D/3D video conferencing, 3D model display and edit, blood pressure and heart rate monitoring, and patient data viewing functions. The demo software can be extended to multi-discipline telehealth applications, such as tele-dentistry, tele-wound and tele-psychiatry. The proposed 3D telemedicine solution has the potential to revolutionize next-generation telemedicine technologies by providing a high quality immersive tele-consultation experience.

  19. Microfluidic Fabrication of Bio-Inspired Microfibers with Controllable Magnetic Spindle-Knots for 3D Assembly and Water Collection.

    PubMed

    He, Xiao-Heng; Wang, Wei; Liu, Ying-Mei; Jiang, Ming-Yue; Wu, Fang; Deng, Ke; Liu, Zhuang; Ju, Xiao-Jie; Xie, Rui; Chu, Liang-Yin

    2015-08-12

    A simple and flexible approach is developed for controllable fabrication of spider-silk-like microfibers with tunable magnetic spindle-knots from biocompatible calcium alginate for controlled 3D assembly and water collection. Liquid jet templates with volatile oil drops containing magnetic Fe3O4 nanoparticles are generated from microfluidics for fabricating spider-silk-like microfibers. The structure of jet templates can be precisely adjusted by simply changing the flow rates to tailor the structures of the resultant spider-silk-like microfibers. The microfibers can be well manipulated by external magnetic fields for controllably moving, and patterning and assembling into different 2D and 3D structures. Moreover, the dehydrated spider-silk-like microfibers, with magnetic spindle-knots for collecting water drops, can be controllably assembled into spider-web-like structures for excellent water collection. These spider-silk-like microfibers are promising as functional building blocks for engineering complex 3D scaffolds for water collection, cell culture, and tissue engineering.

  20. New 3D parallel GILD electromagnetic modeling and nonlinear inversion using global magnetic integral and local differential equation

    SciTech Connect

    Xie, G.; Li, J.; Majer, E.; Zuo, D.

    1998-07-01

    This paper describes a new 3D parallel GILD electromagnetic (EM) modeling and nonlinear inversion algorithm. The algorithm consists of: (a) a new magnetic integral equation instead of the electric integral equation to solve the electromagnetic forward modeling and inverse problem; (b) a collocation finite element method for solving the magnetic integral and a Galerkin finite element method for the magnetic differential equations; (c) a nonlinear regularizing optimization method to make the inversion stable and of high resolution; and (d) a new parallel 3D modeling and inversion using a global integral and local differential domain decomposition technique (GILD). The new 3D nonlinear electromagnetic inversion has been tested with synthetic data and field data. The authors obtained very good imaging for the synthetic data and reasonable subsurface EM imaging for the field data. The parallel algorithm has high parallel efficiency over 90% and can be a parallel solver for elliptic, parabolic, and hyperbolic modeling and inversion. The parallel GILD algorithm can be extended to develop a high resolution and large scale seismic and hydrology modeling and inversion in the massively parallel computer.

  1. 3D Equilibrium Reconstruction of Current-Driven Discharges in the Compact Toroidal Hybrid with Magnetic Diagnostics

    NASA Astrophysics Data System (ADS)

    Stevenson, A.; Hanson, J.; Hartwell, G.; Hebert, J.; Knowlton, S.

    2010-11-01

    The capability of rapidly reconstructing 3D equilibria in toroidal confinement experiments is important to understand the stability and confinement of fusion plasmas. Plasma reconstructions using the V3FIT 3D magnetic equilibrium reconstruction code [1] are performed using magnetic diagnostics in the Compact Toroidal Hybrid (CTH). CTH is a heliotron device in which the magnetic configuration can be strongly modified by an ohmic plasma current. Currently, signals from several sets of segmented and full Rogowski coils measuring the poloidal field provide the experimental input to V3FIT which utilizes the VMEC equilibrium code [2] to reconstruct 3D plasma equilibria. A movable array of Hall probes is being built to measure the interior poloidal field and will be included in plasma reconstruction to provide better resolution of the current profile. Supported by US DOE Grant DE-FG02-00ER54610. [4pt] [1] J. D. Hanson et al, Nucl. Fusion 49, 075031 (2009) [0pt] [2] S. P. Hirshman and D. K. Lee, Comput. Phys. Commun. 39, 161(1986)

  2. Magnetic diffusivities in 3D radiative chemo-hydrodynamic simulations of protostellar collapse

    NASA Astrophysics Data System (ADS)

    Dzyurkevich, Natalia; Commerçon, Benoît; Lesaffre, Pierre; Semenov, Dimitry

    2017-07-01

    Context. Both theory and observations of star-forming clouds require simulations that combine the co-evolving chemistry, magneto-hydrodynamics, and radiative transfer in protostellar collapse simulation. A detailed knowledge of self-consistent chemical evolution for the main charge carriers (both gas species and dust grains) allows us to correctly estimate the rate and nature of magnetic dissipation in the collapsing core. This knowledge is critical to answer one of the most significant issues of star and planet formation: what is the magnitude and spatial distribution of magnetic flux as the initial condition to protoplanetary disk evolution? Aims: We use a chemo-dynamical version of RAMSES, which is described in a companion publication, to follow the chemo-dynamical evolution of collapsing dense cores with various dust properties and interpret differences that occur in magnetic diffusivity terms. These differences are crucial to circumstellar disk formation. Methods: We performed 3D chemo-dynamical simulations of 1 M⊙ isolated dense core collapse for a range in dust size assumptions. The number density of dust and its mean size affect the efficiency of charge capturing and the formation of ices. The radiative hydrodynamics and dynamical evolution of chemical abundances were used to reconstruct the magnetic diffusivity terms for clouds with various magnetisation. Results: The simulations are performed for a mean dust size ranging from 0.017 μm to 1 μm, and we adopt both a fixed dust size and a dust size distribution. The chemical abundances for this range of dust sizes are produced by RAMSES and serve as inputs to calculations of Ohmic, ambipolar, and Hall diffusivity terms. Ohmic resistivity only plays a role at the late stage of the collapse in the innermost region of the cloud where gas density is in excess of a few times 1013 cm-3. Ambipolar diffusion is a dominant magnetic diffusivity term in cases where mean dust size is a typical ISM value or larger. We

  3. AE3D

    SciTech Connect

    Spong, Donald A

    2016-06-20

    AE3D solves for the shear Alfven eigenmodes and eigenfrequencies in a torodal magnetic fusion confinement device. The configuration can be either 2D (e.g. tokamak, reversed field pinch) or 3D (e.g. stellarator, helical reversed field pinch, tokamak with ripple). The equations solved are based on a reduced MHD model and sound wave coupling effects are not currently included.

  4. Investigation of Plutonic Rocks in Biga Peninsula, NW Turkey, using 3D Normalized Full Gradient of Magnetic Data

    NASA Astrophysics Data System (ADS)

    Ekinci, Y. L.; Yiǧitbaş, E.

    2012-04-01

    Airborne magnetic data of Biga Peninsula were investigated by using 3D Normalized Full Gradient (NFG) technique. The NFG procedure is based on the downward continuation of the potential field data and the NFG amplitude is calculated by dividing the Analytic Signal (AS) of downward continued magnetic data by the average of AS. Application of NFG technique usually enhances the anomalies by computing the anomaly to a level close to the source bodies and points to the boundaries of causative bodies. To that end, a MATLAB based code consisting of a series of linked functions was developed and used for analyses. Study area covers an area of 120 km x 180 km and the data were collected with 1-2 km profile intervals and with about 70 m sampling from 625 m above the ground surface by MTA (General Directorate of Mineral Research and Exploration). 2 km sampling intervals for both north and east directions were used for gridding of the magnetic data. Regional anomalies were approximated by means of element shape functions used in finite element method and then residuals were computed. Prior to the application of 3D NFG, Reduction to the Pole (RTP) transformation was applied to residual data in order to remove the complexity due to the effects of the direction of magnetization and ambient field. RTP transformation process was performed using 55 and 4 degrees for inclination and declination angles, respectively. 3D NFG operation was performed to reduced to pole data for 6 different depth levels (-200, -400, -600, -800, -1000 and -1200 m). Analyzing the resulting anomaly maps of different depth levels together with the geological map (1/500.000) showed that the locations of maximum NFG amplitudes indicate the boundaries of plutonic rocks having high magnetization intensity. Additionally, horizontal and vertical extensions of plutonic rocks were also determined. Keywords: Airborne magnetic data, normalized full gradient, plutonic rocks, Biga Peninsula-Turkey

  5. A 360-degree floating 3D display based on light field regeneration.

    PubMed

    Xia, Xinxing; Liu, Xu; Li, Haifeng; Zheng, Zhenrong; Wang, Han; Peng, Yifan; Shen, Weidong

    2013-05-06

    Using light field reconstruction technique, we can display a floating 3D scene in the air, which is 360-degree surrounding viewable with correct occlusion effect. A high-frame-rate color projector and flat light field scanning screen are used in the system to create the light field of real 3D scene in the air above the spinning screen. The principle and display performance of this approach are investigated in this paper. The image synthesis method for all the surrounding viewpoints is analyzed, and the 3D spatial resolution and angular resolution of the common display zone are employed to evaluate display performance. The prototype is achieved and the real 3D color animation image has been presented vividly. The experimental results verified the representability of this method.

  6. FGG-NUFFT-Based Method for Near-Field 3-D Imaging Using Millimeter Waves

    PubMed Central

    Kan, Yingzhi; Zhu, Yongfeng; Tang, Liang; Fu, Qiang; Pei, Hucheng

    2016-01-01

    In this paper, to deal with the concealed target detection problem, an accurate and efficient algorithm for near-field millimeter wave three-dimensional (3-D) imaging is proposed that uses a two-dimensional (2-D) plane antenna array. First, a two-dimensional fast Fourier transform (FFT) is performed on the scattered data along the antenna array plane. Then, a phase shift is performed to compensate for the spherical wave effect. Finally, fast Gaussian gridding based nonuniform FFT (FGG-NUFFT) combined with 2-D inverse FFT (IFFT) is performed on the nonuniform 3-D spatial spectrum in the frequency wavenumber domain to achieve 3-D imaging. The conventional method for near-field 3-D imaging uses Stolt interpolation to obtain uniform spatial spectrum samples and performs 3-D IFFT to reconstruct a 3-D image. Compared with the conventional method, our FGG-NUFFT based method is comparable in both efficiency and accuracy in the full sampled case and can obtain more accurate images with less clutter and fewer noisy artifacts in the down-sampled case, which are good properties for practical applications. Both simulation and experimental results demonstrate that the FGG-NUFFT-based near-field 3-D imaging algorithm can have better imaging performance than the conventional method for down-sampled measurements. PMID:27657066

  7. FGG-NUFFT-Based Method for Near-Field 3-D Imaging Using Millimeter Waves.

    PubMed

    Kan, Yingzhi; Zhu, Yongfeng; Tang, Liang; Fu, Qiang; Pei, Hucheng

    2016-09-19

    In this paper, to deal with the concealed target detection problem, an accurate and efficient algorithm for near-field millimeter wave three-dimensional (3-D) imaging is proposed that uses a two-dimensional (2-D) plane antenna array. First, a two-dimensional fast Fourier transform (FFT) is performed on the scattered data along the antenna array plane. Then, a phase shift is performed to compensate for the spherical wave effect. Finally, fast Gaussian gridding based nonuniform FFT (FGG-NUFFT) combined with 2-D inverse FFT (IFFT) is performed on the nonuniform 3-D spatial spectrum in the frequency wavenumber domain to achieve 3-D imaging. The conventional method for near-field 3-D imaging uses Stolt interpolation to obtain uniform spatial spectrum samples and performs 3-D IFFT to reconstruct a 3-D image. Compared with the conventional method, our FGG-NUFFT based method is comparable in both efficiency and accuracy in the full sampled case and can obtain more accurate images with less clutter and fewer noisy artifacts in the down-sampled case, which are good properties for practical applications. Both simulation and experimental results demonstrate that the FGG-NUFFT-based near-field 3-D imaging algorithm can have better imaging performance than the conventional method for down-sampled measurements.

  8. Fully automated measurement of field-dependent AMS using MFK1-FA Kappabridge equipped with 3D rotator

    NASA Astrophysics Data System (ADS)

    Chadima, Martin; Studynka, Jan

    2013-04-01

    Low-field magnetic susceptibility of paramagnetic and diamagnetic minerals is field-independent by definition being also field-independent in pure magnetite. On the other hand, in pyrrhotite, hematite and high-Ti titanomagnetite it may be clearly field-dependent. Consequently, the field-dependent AMS enables the magnetic fabric of the latter group of minerals to be separated from the whole-rock AMS. The methods for the determination of the field-dependent AMS consist of separate measurements of each specimen in several fields within the Rayleigh Law range and subsequent processing in which the field-independent and field-dependent AMS components are calculated. The disadvantage of this technique is that each specimen must be measured several times, which is relatively laborious and time consuming. Recently, a new 3D rotator was developed for the MFK1-FA Kappabridge, which rotates the specimen simultaneously about two axes with different velocities. The measurement is fully automated in such a way that, once the specimen is inserted into the rotator, it requires no additional manipulation to measure the full AMS tensor. Consequently, the 3D rotator enables to measure the AMS tensors in the pre-set field intensities without any operator interference. Whole procedure is controlled by newly developed Safyr5 software; once the measurements are finished, the acquired data are immediately processed and can be visualized in a standard way.

  9. Temporomandibular joint: a methodology of magnetic resonance imaging 3-D reconstruction.

    PubMed

    Chirani, Reza Arbab; Jacq, Jean-José; Meriot, Philippe; Roux, Christian

    2004-06-01

    The aim of this study was to develop a new method for the 3-dimensional reconstruction of the temporomandibular joint (TMJ) images by means of magnetic resonance imaging (MRI). In a preliminary study, this modality of 3-D representation was tested to evaluate the joint motion. Sagittal MRI slices were obtained from a healthy subject. Acquisitions were realized by a spin-echo sequence, with a proton-density weighting and a 2-mm slice thickness. A 3-D reconstruction of the TMJ images was performed. Three-dimensional representations of the temporomandibular joint were obtained. The depiction of the principal anatomical elements of this joint was realized. A study of TMJ dynamics was also carried out. In this case, movements of the right and left disks and condyles were measured. This 3-D reconstruction methodology allowed a more understandable anatomical description than 2-D images of the TMJ and offered possibilities for joint functional analysis. Copyright 2004 Elsevier Inc.

  10. Developments for 3D gravity and magnetic modeling in spherical coordinates

    NASA Astrophysics Data System (ADS)

    Lane, R. J.; Liang, Q.; Chen, C.; Li, Y.

    2012-12-01

    for improved management of rock property data and to develop methods to better understand how these data can be used to provide constraints for geophysical modeling. GA are also using the opportunities afforded through the DET CRC to improve documentation and standardization of data and model storage and transfer formats so that the tasks of management, discovery and delivery of modeling inputs and results to various users can be simplified and made more efficient. To provide the foundations of integration and analysis of information in a 3D spatial context, GA are utilizing and customizing 3D visualization software using a Virtual Globe application, NASA World Wind. This will permit us to view the spherical coordinate models and other information at global to local scales in a realistic coordinate framework. The various development activities will together play an important role in the on-going effort by GA to add value to large stores of potential field, rock property, and geological information. This will lead to a better understanding of the geology of the Australian region which will be used in a range of applications, including mineral and energy exploration, natural hazard mitigation, and groundwater management.

  11. How 3D seismic-CAEX combination affected development of N. Frisco City field in Alabama

    SciTech Connect

    Stephenson, M.; Cox, J.; Jones-Fuentes, P. )

    1992-10-26

    This paper reports that by applying the latest in 3D seismic and computer aided exploration and production (CAEX) technology, small and mid-size independents are changing the methods by which fields are discovered and profitably developed. The combination of 3D and CAEX has, in many cases, altered oilfield economics. Nuevo Energy Co.'s North Frisco City development---located in the updip Jurassic Haynesville trend of Southwest Alabama---offers a case in point. The 3D technology employed at North Frisco City produced and accurate, detailed picture of the subsurface. Ultimately it more than doubled the drilling success rate over that of a nearby, closely related field in which 3D was not used.

  12. Ultrahigh-definition dynamic 3D holographic display by active control of volume speckle fields

    NASA Astrophysics Data System (ADS)

    Yu, Hyeonseung; Lee, Kyeoreh; Park, Jongchan; Park, Yongkeun

    2017-01-01

    Holographic displays generate realistic 3D images that can be viewed without the need for any visual aids. They operate by generating carefully tailored light fields that replicate how humans see an actual environment. However, the realization of high-performance, dynamic 3D holographic displays has been hindered by the capabilities of present wavefront modulator technology. In particular, spatial light modulators have a small diffraction angle range and limited pixel number limiting the viewing angle and image size of a holographic 3D display. Here, we present an alternative method to generate dynamic 3D images by controlling volume speckle fields significantly enhancing image definition. We use this approach to demonstrate a dynamic display of micrometre-sized optical foci in a volume of 8 mm × 8 mm × 20 mm.

  13. Enhancing the sensitivity of magnetic sensors by 3D metamaterial shells.

    PubMed

    Navau, Carles; Mach-Batlle, Rosa; Parra, Albert; Prat-Camps, Jordi; Laut, Sergi; Del-Valle, Nuria; Sanchez, Alvaro

    2017-03-17

    Magnetic sensors are key elements in our interconnected smart society. Their sensitivity becomes essential for many applications in fields such as biomedicine, computer memories, geophysics, or space exploration. Here we present a universal way of increasing the sensitivity of magnetic sensors by surrounding them with a spherical metamaterial shell with specially designed anisotropic magnetic properties. We analytically demonstrate that the magnetic field in the sensing area is enhanced by our metamaterial shell by a known factor that depends on the shell radii ratio. When the applied field is non-uniform, as for dipolar magnetic field sources, field gradient is increased as well. A proof-of-concept experimental realization confirms the theoretical predictions. The metamaterial shell is also shown to concentrate time-dependent magnetic fields upto frequencies of 100 kHz.

  14. Enhancing the sensitivity of magnetic sensors by 3D metamaterial shells

    PubMed Central

    Navau, Carles; Mach-Batlle, Rosa; Parra, Albert; Prat-Camps, Jordi; Laut, Sergi; Del-Valle, Nuria; Sanchez, Alvaro

    2017-01-01

    Magnetic sensors are key elements in our interconnected smart society. Their sensitivity becomes essential for many applications in fields such as biomedicine, computer memories, geophysics, or space exploration. Here we present a universal way of increasing the sensitivity of magnetic sensors by surrounding them with a spherical metamaterial shell with specially designed anisotropic magnetic properties. We analytically demonstrate that the magnetic field in the sensing area is enhanced by our metamaterial shell by a known factor that depends on the shell radii ratio. When the applied field is non-uniform, as for dipolar magnetic field sources, field gradient is increased as well. A proof-of-concept experimental realization confirms the theoretical predictions. The metamaterial shell is also shown to concentrate time-dependent magnetic fields upto frequencies of 100 kHz. PMID:28303951

  15. Enhancing the sensitivity of magnetic sensors by 3D metamaterial shells

    NASA Astrophysics Data System (ADS)

    Navau, Carles; Mach-Batlle, Rosa; Parra, Albert; Prat-Camps, Jordi; Laut, Sergi; Del-Valle, Nuria; Sanchez, Alvaro

    2017-03-01

    Magnetic sensors are key elements in our interconnected smart society. Their sensitivity becomes essential for many applications in fields such as biomedicine, computer memories, geophysics, or space exploration. Here we present a universal way of increasing the sensitivity of magnetic sensors by surrounding them with a spherical metamaterial shell with specially designed anisotropic magnetic properties. We analytically demonstrate that the magnetic field in the sensing area is enhanced by our metamaterial shell by a known factor that depends on the shell radii ratio. When the applied field is non-uniform, as for dipolar magnetic field sources, field gradient is increased as well. A proof-of-concept experimental realization confirms the theoretical predictions. The metamaterial shell is also shown to concentrate time-dependent magnetic fields upto frequencies of 100 kHz.

  16. Magnetically Bioprinted Human Myometrial 3D Cell Rings as A Model for Uterine Contractility.

    PubMed

    Souza, Glauco R; Tseng, Hubert; Gage, Jacob A; Mani, Arunmani; Desai, Pujan; Leonard, Fransisca; Liao, Angela; Longo, Monica; Refuerzo, Jerrie S; Godin, Biana

    2017-03-23

    Deregulation in uterine contractility can cause common pathological disorders of the female reproductive system, including preterm labor, infertility, inappropriate implantation, and irregular menstrual cycle. A better understanding of human myometrium contractility is essential to designing and testing interventions for these important clinical problems. Robust studies on the physiology of human uterine contractions require in vitro models, utilizing a human source. Importantly, uterine contractility is a three-dimensionally (3D)-coordinated phenomenon and should be studied in a 3D environment. Here, we propose and assess for the first time a 3D in vitro model for the evaluation of human uterine contractility. Magnetic 3D bioprinting is applied to pattern human myometrium cells into rings, which are then monitored for contractility over time and as a function of various clinically relevant agents. Commercially available and patient-derived myometrium cells were magnetically bioprinted into rings in 384-well formats for throughput uterine contractility analysis. The bioprinted uterine rings from various cell origins and patients show different patterns of contractility and respond differently to clinically relevant uterine contractility inhibitors, indomethacin and nifedipine. We believe that the novel system will serve as a useful tool to evaluate the physiology of human parturition while enabling high-throughput testing of multiple agents and conditions.

  17. Magnetic and Electronic Phase Diagram of Sr2VFeAsO3-d

    NASA Astrophysics Data System (ADS)

    Tojo, Yujiro; Shibuya, Taizo; Nakamura, Tetsuro; Shoji, Koichiro; Matoba, Masanori; Yasui, Shintaro; Itoh, Mitsuru; Kitao, Shinji; Seto, Makoto; Kamihara, Yoichi; Research Grants From Keio Univ. Collaboration; Msl Collaborative Research Project Collaboration; Joint Usage in Krri Collaboration

    2014-03-01

    Ae2MFePnO3 (so-called 21113 systems) with perovskite-type layers such as Ae2MO3, where Ae denotes alkaline earth metals, M does Sc, Ti, Cr, V and other transition metal atoms and Pn does As and P shows superconductivity at T <46 K. Sr2VFeAsO3-d is a representative compound in 21113 systems. [Zhu et al, Phys. Rev. B (2009); Ogino et al, Supercond. Sci. Technol. (2009); Ogino et al, Supercond. Sci. Technol. (2009)] Although the oxygen deficiency (d) as a function of Tc is still controversial in Sr2VFeAsO3-d, many samples have been reported as superconductors with Tc = 24-37 K. In this study, a polycrystalline Sr2VFeAsO3-d (d = ~ 0.1- 0.6) were prepared by a solid state reaction using an alumina tube in a sealed silica tube. DC electrical resistivity was measured by a four-probe technique. Magnetization measurements were performed on a superconducting quantum interference device. 57Fe Mossbauer spectra were obtained using conventional equipment. The electronic and magnetic phase diagram of Sr2VFeAsO3-d is elucidated.

  18. pynoddy 1.0: an experimental platform for automated 3-D kinematic and potential field modelling

    NASA Astrophysics Data System (ADS)

    Florian Wellmann, J.; Thiele, Sam T.; Lindsay, Mark D.; Jessell, Mark W.

    2016-03-01

    We present a novel methodology for performing experiments with subsurface structural models using a set of flexible and extensible Python modules. We utilize the ability of kinematic modelling techniques to describe major deformational, tectonic, and magmatic events at low computational cost to develop experiments testing the interactions between multiple kinematic events, effect of uncertainty regarding event timing, and kinematic properties. These tests are simple to implement and perform, as they are automated within the Python scripting language, allowing the encapsulation of entire kinematic experiments within high-level class definitions and fully reproducible results. In addition, we provide a link to geophysical potential-field simulations to evaluate the effect of parameter uncertainties on maps of gravity and magnetics. We provide relevant fundamental information on kinematic modelling and our implementation, and showcase the application of our novel methods to investigate the interaction of multiple tectonic events on a pre-defined stratigraphy, the effect of changing kinematic parameters on simulated geophysical potential fields, and the distribution of uncertain areas in a full 3-D kinematic model, based on estimated uncertainties in kinematic input parameters. Additional possibilities for linking kinematic modelling to subsequent process simulations are discussed, as well as additional aspects of future research. Our modules are freely available on github, including documentation and tutorial examples, and we encourage the contribution to this project.

  19. pynoddy 1.0: an experimental platform for automated 3-D kinematic and potential field modelling

    NASA Astrophysics Data System (ADS)

    Wellmann, J. F.; Thiele, S. T.; Lindsay, M. D.; Jessell, M. W.

    2015-11-01

    We present a novel methodology for performing experiments with subsurface structural models using a set of flexible and extensible Python modules. We utilise the ability of kinematic modelling techniques to describe major deformational, tectonic, and magmatic events at low computational cost to develop experiments testing the interactions between multiple kinematic events, effect of uncertainty regarding event timing, and kinematic properties. These tests are simple to implement and perform, as they are automated within the Python scripting language, allowing the encapsulation of entire kinematic experiments within high-level class definitions and fully reproducible results. In addition, we provide a~link to geophysical potential-field simulations to evaluate the effect of parameter uncertainties on maps of gravity and magnetics. We provide relevant fundamental information on kinematic modelling and our implementation, and showcase the application of our novel methods to investigate the interaction of multiple tectonic events on a pre-defined stratigraphy, the effect of changing kinematic parameters on simulated geophysical potential-fields, and the distribution of uncertain areas in a full 3-D kinematic model, based on estimated uncertainties in kinematic input parameters. Additional possibilities for linking kinematic modelling to subsequent process simulations are discussed, as well as additional aspects of future research. Our modules are freely available on github, including documentation and tutorial examples, and we encourage the contribution to this project.

  20. Reconstruction of 3D Coronal Magnetic Structures from THEMIS/MTR and Hinode/SOT Vector Maps

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Guo, Y.; Aulanier, G.; Démoulin, P.; Török, T.; Bommier, V.; Wiegelmann, T.; Gosain, S.

    2012-08-01

    Coordinated campaigns using THEMIS, Hinode, and other instruments have allowed us to study the magnetic fields of faculae, filaments, and active regions. In a first case, we modelled the 3D magnetic field in a flaring active region with a nonlinear force-free field extrapolation, using magnetic vectors observed by THEMIS/MTR as boundary condition. In order to construct a consistent bottom boundary for the model, we first removed the 180 degree ambiguity of the transverse fields and minimized the force and torque in the observed vector fields. We found a twisted magnetic flux rope, well aligned with the polarity inversion line and a part of an Hα filament, and located where a large flare is initiated about two hours later. In a second case, Hinode/SOT allowed us to detect fine flux concentrations in faculae, while MTR provided us with magnetic information at different levels in the atmosphere. The polarimetry analysis of the MTR and SOT data gave consistent results, using both UNNOFIT and MELANIE inversion codes.

  1. A high-throughput in vitro ring assay for vasoactivity using magnetic 3D bioprinting

    PubMed Central

    Tseng, Hubert; Gage, Jacob A.; Haisler, William L.; Neeley, Shane K.; Shen, Tsaiwei; Hebel, Chris; Barthlow, Herbert G.; Wagoner, Matthew; Souza, Glauco R.

    2016-01-01

    Vasoactive liabilities are typically assayed using wire myography, which is limited by its high cost and low throughput. To meet the demand for higher throughput in vitro alternatives, this study introduces a magnetic 3D bioprinting-based vasoactivity assay. The principle behind this assay is the magnetic printing of vascular smooth muscle cells into 3D rings that functionally represent blood vessel segments, whose contraction can be altered by vasodilators and vasoconstrictors. A cost-effective imaging modality employing a mobile device is used to capture contraction with high throughput. The goal of this study was to validate ring contraction as a measure of vasoactivity, using a small panel of known vasoactive drugs. In vitro responses of the rings matched outcomes predicted by in vivo pharmacology, and were supported by immunohistochemistry. Altogether, this ring assay robustly models vasoactivity, which could meet the need for higher throughput in vitro alternatives. PMID:27477945

  2. Reconstructing the Vulcano Island evolution from 3D modeling of magnetic signatures

    NASA Astrophysics Data System (ADS)

    Napoli, Rosalba; Currenti, Gilda

    2016-06-01

    High-resolution ground and marine magnetic data are exploited for a detailed definition of a 3D model of the Vulcano Island volcanic complex. The resulting 3D magnetic imaging, obtained by 3-D inverse modeling technique, has delivered useful constraints both to reconstruct the Vulcano Island evolution and to be used as input data for volcanic hazard assessment models. Our results constrained the depth and geometry of the main geo-structural features revealing more subsurface volcanic structures than exposed ones and allowing to elucidate the relationships between them. The recognition of two different magnetization sectors, approximatively coincident with the structural depressions of Piano caldera, in the southern half of the island, and La Fossa caldera at the north, suggests a complex structural and volcanic evolution. Magnetic highs identified across the southern half of the island reflect the main crystallized feeding systems, intrusions and buried vents, whose NNW-SSE preferential alignment highlights the role of the NNW-SSE Tindari-Letojanni regional system from the initial activity of the submarine edifice, to the more recent activity of the Vulcano complex. The low magnetization area, in the middle part of the island may result from hydrothermally altered rocks. Their presence not only in the central part of the volcano edifice but also in other peripheral areas, is a sign of a more diffuse historical hydrothermal activity than in present days. Moreover, the high magnetization heterogeneity within the upper flanks of La Fossa cone edifice is an imprint of a composite distribution of unaltered and altered rocks with different mechanical properties, which poses in this area a high risk level for failure processes especially during volcanic or hydrothermal crisis.

  3. X-ray Emission Spectroscopy in Magnetic 3d-Transition Metals

    SciTech Connect

    Iota, V; Park, J; Baer, B; Yoo, C; Shen, G

    2003-11-18

    The application of high pressure affects the band structure and magnetic interactions in solids by modifying nearest-neighbor distances and interatomic potentials. While all materials experience electronic changes with increasing pressure, spin polarized, strongly electron correlated materials are expected to undergo the most dramatic transformations. In such materials, (d and f-electron metals and compounds), applied pressure reduces the strength of on-site correlations, leading to increased electron delocalization and, eventually, to loss of its magnetism. In this ongoing project, we study the electronic and magnetic properties of Group VIII, 3d (Fe, Co and Ni) magnetic transition metals and their compounds at high pressures. The high-pressure properties of magnetic 3d-transition metals and compounds have been studied extensively over the years, because of iron being a major constituent of the Earth's core and its relevance to the planetary modeling to understand the chemical composition, internal structure, and geomagnetism. However, the fundamental scientific interest in the high-pressure properties of magnetic 3d-electron systems extends well beyond the geophysical applications to include the electron correlation-driven physics. The role of magnetic interactions in the stabilization of the ''non-standard'' ambient pressure structures of Fe, Co and Ni is still incompletely understood. Theoretical studies have predicted (and high pressure experiments are beginning to show) strong correlations between the electronic structure and phase stability in these materials. The phase diagrams of magnetic 3d systems reflect a delicate balance between spin interactions and structural configuration. At ambient conditions, the crystal structures of {alpha}-Fe(bcc) and {var_epsilon}-Co(hcp) phases depart from the standard sequence (hcp {yields} bcc{yields} hcp {yields} fcc), as observed in all other non-magnetic transition metals with increasing the d-band occupancy, and are

  4. 3D structure and conductive thermal field of the sea of Marmara

    NASA Astrophysics Data System (ADS)

    Gholamrezaie, Ershad; Scheck-Wenderoth, Magdalena; Heidbach, Oliver

    2017-04-01

    The Sea of Marmara and its basins mainly evolved due to the activities of the Thrace-Eskisehir Fault Zone (TEFZ) in Neogene and the North Anatolian Fault Zone (NAFZ) in Quaternary. At present-day, the Sea of Marmara is still evolving due to the NAFZ and the Marmara region is an earthquake danger zone while hosting around 20 million of inhabitants. For a better understanding of the tectonic processes and geodynamic evolution, it is important to model the geological structure and the thermal field of this region. The aim of this study is to build a 3D lithospheric-scale structural model and a 3D conductive thermal model for the Sea of Marmara and including its adjacent onshore areas. Therefore, we integrate different geological and geophysical data such as existing structural models, well data, seismic observations and gravity to build a new 3D lithospheric-scale structural model which is additionally constrained by 3D gravity modeling. The final 3D structural model differentiates various sedimentary, crustal and mantle units and is the base for the 3D thermal field calculation. The 3D conductive thermal model is a numerical solution to the Fourier's law equation in steady-state condition and considering the thermal properties of the corresponding structural model. Our 3D lithospheric-scale models of the geological structure and the conductive thermal field are the key points for further general research and useful particularly for mechanical modeling, considering variations in rheology and strength of the lithosphere in the Marmara region. In addition, our results have application in geo-resources exploration and would be helpful in risk management and hazard mitigation.

  5. Extension of the Optimized Virtual Fields Method to estimate viscoelastic material parameters from 3D dynamic displacement fields

    PubMed Central

    Connesson, N.; Clayton, E.H.; Bayly, P.V.; Pierron, F.

    2015-01-01

    In-vivo measurement of the mechanical properties of soft tissues is essential to provide necessary data in biomechanics and medicine (early cancer diagnosis, study of traumatic brain injuries, etc.). Imaging techniques such as Magnetic Resonance Elastography (MRE) can provide 3D displacement maps in the bulk and in vivo, from which, using inverse methods, it is then possible to identify some mechanical parameters of the tissues (stiffness, damping etc.). The main difficulties in these inverse identification procedures consist in dealing with the pressure waves contained in the data and with the experimental noise perturbing the spatial derivatives required during the processing. The Optimized Virtual Fields Method (OVFM) [1], designed to be robust to noise, present natural and rigorous solution to deal with these problems. The OVFM has been adapted to identify material parameter maps from Magnetic Resonance Elastography (MRE) data consisting of 3-dimensional displacement fields in harmonically loaded soft materials. In this work, the method has been developed to identify elastic and viscoelastic models. The OVFM sensitivity to spatial resolution and to noise has been studied by analyzing 3D analytically simulated displacement data. This study evaluates and describes the OVFM identification performances: different biases on the identified parameters are induced by the spatial resolution and experimental noise. The well-known identification problems in the case of quasi-incompressible materials also find a natural solution in the OVFM. Moreover, an a posteriori criterion to estimate the local identification quality is proposed. The identification results obtained on actual experiments are briefly presented. PMID:26146416

  6. Electrochemical fields within 3D reconstructed microstructures of mixed ionic and electronic conducting devices

    NASA Astrophysics Data System (ADS)

    Zhang, Yanxiang; Chen, Yu; Lin, Ye; Yan, Mufu; Harris, William M.; Chiu, Wilson K. S.; Ni, Meng; Chen, Fanglin

    2016-11-01

    The performance and stability of the mixed ionic and electronic conducting (MIEC) membrane devices, such as solid oxide cells (SOCs) and oxygen separation membranes (OSMs) interplay tightly with the transport properties and the three-dimensional (3D) microstructure of the membrane. However, development of the MIEC devices is hindered by the limited knowledge about the distribution of electrochemical fields within the 3D local microstructures, especially at surface and interface. In this work, a generic model conforming to local thermodynamic equilibrium is developed to calculate the electrochemical fields, such as electric potential and oxygen chemical potential, within the 3D microstructure of the MIEC membrane. Stability of the MIEC membrane is evaluated by the distribution of oxygen partial pressure. The cell-level performance such as polarization resistance and voltage vs. current curve can be further calculated. Case studies are performed to demonstrate the capability of the framework by using X-ray computed tomography reconstructed 3D microstructures of a SOC and an OSM. The calculation method demonstrates high computational efficiency for large size 3D tomographic microstructures, and permits parallel calculation. The framework can serve as a powerful tool for correlating the transport properties and the 3D microstructure to the performance and the stability of MIEC devices.

  7. Compact and field-portable 3D printed shearing digital holographic microscope for automated cell identification.

    PubMed

    Rawat, Siddharth; Komatsu, Satoru; Markman, Adam; Anand, Arun; Javidi, Bahram

    2017-03-20

    We propose a low-cost, compact, and field-portable 3D printed holographic microscope for automated cell identification based on a common path shearing interferometer setup. Once a hologram is captured from the portable setup, a 3D reconstructed height profile of the cell is created. We extract several morphological cell features from the reconstructed 3D height profiles, including mean physical cell thickness, coefficient of variation, optical volume (OV) of the cell, projected area of the cell (PA), ratio of PA to OV, cell thickness kurtosis, cell thickness skewness, and the dry mass of the cell for identification using the random forest (RF) classifier. The 3D printed prototype can serve as a low-cost alternative for the developing world, where access to laboratory facilities for disease diagnosis are limited. Additionally, a cell phone sensor is used to capture the digital holograms. This enables the user to send the acquired holograms over the internet to a computational device located remotely for cellular identification and classification (analysis). The 3D printed system presented in this paper can be used as a low-cost, stable, and field-portable digital holographic microscope as well as an automated cell identification system. To the best of our knowledge, this is the first research paper presenting automatic cell identification using a low-cost 3D printed digital holographic microscopy setup based on common path shearing interferometry.

  8. Methodology for time-domain estimation of storm time geoelectric fields using the 3-D magnetotelluric response tensors

    NASA Astrophysics Data System (ADS)

    Kelbert, Anna; Balch, Christopher C.; Pulkkinen, Antti; Egbert, Gary D.; Love, Jeffrey J.; Rigler, E. Joshua; Fujii, Ikuko

    2017-07-01

    Geoelectric fields at the Earth's surface caused by magnetic storms constitute a hazard to the operation of electric power grids and related infrastructure. The ability to estimate these geoelectric fields in close to real time and provide local predictions would better equip the industry to mitigate negative impacts on their operations. Here we report progress toward this goal: development of robust algorithms that convolve a magnetic storm time series with a frequency domain impedance for a realistic three-dimensional (3-D) Earth, to estimate the local, storm time geoelectric field. Both frequency domain and time domain approaches are presented and validated against storm time geoelectric field data measured in Japan. The methods are then compared in the context of a real-time application.

  9. 3D model of small-scale density cavern formation in the region of auroral field-aligned currents

    NASA Astrophysics Data System (ADS)

    Bespalov, P. A.; Mizonova, V. G.

    2015-11-01

    A 3D problem of the formation of small-scale density caverns with a nonstationary electric field in the region of auroral electric currents and kinetic Alfvén wave currents is considered. It is shown that an excess of the electron current velocity over a certain critical value of their thermal velocity is a probable cause of cavern formation. Linear and nonlinear stages of the density cavern formation are considered, and their main parameters are estimated. In the case of comparatively strong magnetic fields, caverns can be formed with comparable longitudinal and transverse (with respect to the magnetic field) scales. The properties of parameters of small-scale density caverns and nonstationary electric field agree with well-known experimental data.

  10. Methodology for time-domain estimation of storm time geoelectric fields using the 3-D magnetotelluric response tensors

    USGS Publications Warehouse

    Kelbert, Anna; Balch, Christopher; Pulkkinen, Antti; Egbert, Gary D; Love, Jeffrey J.; Rigler, E. Joshua; Fujii, Ikuko

    2017-01-01

    Geoelectric fields at the Earth's surface caused by magnetic storms constitute a hazard to the operation of electric power grids and related infrastructure. The ability to estimate these geoelectric fields in close to real time and provide local predictions would better equip the industry to mitigate negative impacts on their operations. Here we report progress toward this goal: development of robust algorithms that convolve a magnetic storm time series with a frequency domain impedance for a realistic three-dimensional (3-D) Earth, to estimate the local, storm time geoelectric field. Both frequency domain and time domain approaches are presented and validated against storm time geoelectric field data measured in Japan. The methods are then compared in the context of a real-time application.

  11. Topology and Dynamics of Reconnection in 3D Pair Plasma Without Guide Field

    NASA Astrophysics Data System (ADS)

    Mollica, F.; Bhattacharjee, A.; Fox, W.

    2011-10-01

    We investigate fast reconnection in 3D pair plasma without a guide field using the Particle Simulation Code (PSC), beginning from a Harris sheet with a neutral line, which is a continuum of nulls and is structurally unstable in 3D. The neutral line is shown to break up into a sequence of discrete nulls of the A- and B-type, which are joined by null-null lines that constitute an AB-web, and provide an underlying topological skeleton for 3D reconnection. The current density distribution in such a system is shown to correspond to recent 3D models of ``spine reconnection.'' The sheet current density is unstable with respect to the kink instability which introduces folding as well as plasmoid instabilities that introduce complex structure formation, while supporting fast time-dependent reconnection.

  12. Modeling of 3d Space-time Surface of Potential Fields and Hydrogeologic Modeling of Nuclear Waste Disposal Sites

    NASA Astrophysics Data System (ADS)

    Shestopalov, V.; Bondarenko, Y.; Zayonts, I.; Rudenko, Y.

    Introduction After the Chernobyl Nuclear Power Plant (CNPP) disaster (04.26.1986) a huge amount (over 2000 sq. km) of nuclear wastes appeared within so-called "Cher- nobyl Exclusion Zone" (CEZ). At present there are not enough storage facilities in the Ukraine for safe disposal of nuclear wastes and hazardous chemical wastes. The urgent problem now is safe isolation of these dangerous wastes. According to the developed state program of radioactive waste management, the construction of a na- tional storage facility of nuclear wastes is planned. It is also possible to create regional storage facilities for hazardous chemical wastes. The region of our exploration cov- ers the eastern part of the Korosten Plutone and its slope, reaching the CNPP. 3D Space-Time Surface Imaging of Geophysical Fields. There are only three direct meth- ods of stress field reconstruction in present practice, namely the field investigations based on the large-scale fracturing tests, petrotectonic and optical polarization meth- ods. Unfortunately, all these methods are extremely laborious and need the regular field tests, which is difficult to conduct in the areas of anisotropic rock outcrops. A compilation of magnetic and gravity data covering the CNPP area was carried out as a prelude to an interpretation study. More than thirty map products were generated from magnetic, gravity and geodesy data to prepare the 3D Space-Time Surface Images (3D STSI). Multi-layer topography and geophysic surfaces included: total magnetic intensity, isostatically-corrected Bouguer gravity, aspect and slope, first and second derivatives, vertical and horizontal curvature, histogram characteristics and space cor- relation coefficients between the gradient fields. Many maps shows the first and sec- ond derivatives of the potential fields, with the results of lineament (edge) structure detection superimposed. The lineament or edges of the potential fields are located from maximal gradient in many directions

  13. Cross modality registration of video and magnetic tracker data for 3D appearance and structure modeling

    NASA Astrophysics Data System (ADS)

    Sargent, Dusty; Chen, Chao-I.; Wang, Yuan-Fang

    2010-02-01

    The paper reports a fully-automated, cross-modality sensor data registration scheme between video and magnetic tracker data. This registration scheme is intended for use in computerized imaging systems to model the appearance, structure, and dimension of human anatomy in three dimensions (3D) from endoscopic videos, particularly colonoscopic videos, for cancer research and clinical practices. The proposed cross-modality calibration procedure operates this way: Before a colonoscopic procedure, the surgeon inserts a magnetic tracker into the working channel of the endoscope or otherwise fixes the tracker's position on the scope. The surgeon then maneuvers the scope-tracker assembly to view a checkerboard calibration pattern from a few different viewpoints for a few seconds. The calibration procedure is then completed, and the relative pose (translation and rotation) between the reference frames of the magnetic tracker and the scope is determined. During the colonoscopic procedure, the readings from the magnetic tracker are used to automatically deduce the pose (both position and orientation) of the scope's reference frame over time, without complicated image analysis. Knowing the scope movement over time then allows us to infer the 3D appearance and structure of the organs and tissues in the scene. While there are other well-established mechanisms for inferring the movement of the camera (scope) from images, they are often sensitive to mistakes in image analysis, error accumulation, and structure deformation. The proposed method using a magnetic tracker to establish the camera motion parameters thus provides a robust and efficient alternative for 3D model construction. Furthermore, the calibration procedure does not require special training nor use expensive calibration equipment (except for a camera calibration pattern-a checkerboard pattern-that can be printed on any laser or inkjet printer).

  14. 3D field-shaping lens using all-dielectric gradient refractive index materials.

    PubMed

    Ding, Tongyu; Yi, Jianjia; Li, Haoyu; Zhang, Hailin; Burokur, Shah Nawaz

    2017-04-10

    A novel three-dimensional (3D) optical lens structure for electromagnetic field shaping based on spatial light transformation method is proposed at microwave frequencies. The lens is capable of transforming cylindrical wavefronts into planar ones, and generating a directive emission. Such manipulation is simulated and analysed by solving Laplace's equation, and the deformation of the medium during the transformation is theoretically described in detail. The two-dimensional (2D) design method producing quasi-isotropic parameters is further extended to a potential 3D realization with all-dielectric gradient refractive index metamaterials. Numerical full-wave simulations are performed on both 2D and 3D models to verify the functionality and broadband characteristics of the calculated lens. Far-field radiation patterns and near-field distributions demonstrate a highly radiated directive beam when the lens is applied to a conical horn antenna.

  15. Quantitative 3D magnetic resonance elastography: Comparison with dynamic mechanical analysis

    PubMed Central

    Rossman, Phillip J.; Arani, Arvin; Lake, David S.; Glaser, Kevin J.; Trzasko, Joshua D.; Manduca, Armando; McGee, Kiaran P.; Ehman, Richard L.; Araoz, Philip A.

    2016-01-01

    Purpose Magnetic resonance elastography (MRE) is a rapidly growing noninvasive imaging technique for measuring tissue mechanical properties in vivo. Previous studies have compared two‐dimensional MRE measurements with material properties from dynamic mechanical analysis (DMA) devices that were limited in frequency range. Advanced DMA technology now allows broad frequency range testing, and three‐dimensional (3D) MRE is increasingly common. The purpose of this study was to compare 3D MRE stiffness measurements with those of DMA over a wide range of frequencies and shear stiffnesses. Methods 3D MRE and DMA were performed on eight different polyvinyl chloride samples over 20–205 Hz with stiffness between 3 and 23 kPa. Driving frequencies were chosen to create 1.1, 2.2, 3.3, 4.4, 5.5, and 6.6 effective wavelengths across the diameter of the cylindrical phantoms. Wave images were analyzed using direct inversion and local frequency estimation algorithm with the curl operator and compared with DMA measurements at each corresponding frequency. Samples with sufficient spatial resolution and with an octahedral shear strain signal‐to‐noise ratio > 3 were compared. Results Consistency between the two techniques was measured with the intraclass correlation coefficient (ICC) and was excellent with an overall ICC of 0.99. Conclusions 3D MRE and DMA showed excellent consistency over a wide range of frequencies and stiffnesses. Magn Reson Med 77:1184–1192, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. PMID:27016276

  16. Tunable magnetism of 3d transition metal doped BiFeO3

    NASA Astrophysics Data System (ADS)

    Lu, S.; Li, C.; Zhao, Y. F.; Gong, Y. Y.; Niu, L. Y.; Liu, X. J.; Wang, T.

    2017-10-01

    Electronic polarization or bond relaxation can effectively alter the electronic and magnetic behavior of materials by doping impurity atom. For this aim, the thermodynamic, electronic and magnetic performances of cubic BiFeO3 have been modulated by the 3d transition metal (TM) dopants (Sc, Ti, V, Cr, Mn, Co, Ni, Cu and Zn) based on the density functional theory. Results show that the doped specimen with low impurity concentration is more stable than that with high impurity concentration. The Mulliken charge values and spin magnetic moments of TM element are making major changes, while those of all host atoms are making any major changes. Especially, it is the linear relation between the spin magnetic moments of TM dopants and the total magnetic moment of doped specimens; thus, the variations of total magnetic moment of doped specimens are decided by the spin magnetic moments of TM dopants, thought the total magnetic moments of doped specimens mainly come from Fe atom and TM dopants. Besides, as double TM atoms substitution the Fe atoms, the Sc-, Ti-, Mn-, Co- and Zn-doped specimens show AFM state, while the V-, Cr-, Ni- and Cu-doped specimens show FM state.

  17. 3D geological model of Bairendaba Ag-Pb-Zn ore field, northeastern China, based on integrated geophysics

    NASA Astrophysics Data System (ADS)

    Li, W.; Zhang, J.

    2013-12-01

    Bairendaba Ag-Pb-Zn ore field, located in the southwestern part of the Greater Khingan Range, is one of the most representative ore that found by geophysical and geochemical methods in Inner Mongolia, China. Bairendaba ore field has rich mineral reserves, including 8000 tons of Ag, and 3 million tons of Pb and Zn. Since the ore field was discovered in 2001, a large number of ore bodies have been found by IP and other geophysical methods in this area. However, a high-level integrated geophysical interpretation had not been completed. A new study of 3D geology model, based on gravity, magnetic, IP and surface wave method, reveals subtle image of the ore field. A 3D forward modeling was conducted to include faulting and folding systems for the inversion. Moreover, the non-uniqueness of geophysics in interpretation has been constrained by integrated geophysical methods, geology profiles and drilling holes. Such a 3D visualization can illustrate the depth, thickness, attitude and other key properties of strata. Our study provides a subtle approach to delineate complex ore fields, and suggests the unexploited western district has a high resource potential in greater depth.

  18. Evaluation of Gastric Volumes: Comparison of 3-D Ultrasound and Magnetic Resonance Imaging.

    PubMed

    Buisman, Wijnand J; Mauritz, Femke A; Westerhuis, Wouter E; Gilja, Odd Helge; van der Zee, David C; van Herwaarden-Lindeboom, Maud Y A

    2016-07-01

    To investigate gastric accommodation, accurate measurements of gastric volumes are necessary. An excellent technique to measure gastric volumes is dynamic magnetic resonance imaging (MRI). Unfortunately, dynamic MRI is expensive and not always available. A new 3-D ultrasound (US) method using a matrix transducer was developed to measure gastric volumes. In this prospective study, 14 healthy volunteers underwent a dynamic MRI and a 3-D US. Gastric volumes were calculated with intra-gastric liquid content and total gastric volume. Mean postprandial liquid gastric content was 397 ± 96.5 mL. Mean volume difference was 1.0 mL with limits of agreement of -8.9 to 10.9 mL. When gastric air was taken into account, mean total gastric volume was 540 ± 115.4 mL SD. Mean volume difference was 2.3 mL with limits of agreement of -21.1 to 26.4 mL. The matrix 3-D US showed excellent agreement with dynamic MRI. Therefore matrix 3-D US is a reliable alternative to measure gastric volumes.

  19. Realistic 3D coherent transfer function inverse filtering of complex fields.

    PubMed

    Cotte, Yann; Toy, Fatih M; Arfire, Cristian; Kou, Shan Shan; Boss, Daniel; Bergoënd, Isabelle; Depeursinge, Christian

    2011-08-01

    We present a novel technique for three-dimensional (3D) image processing of complex fields. It consists in inverting the coherent image formation by filtering the complex spectrum with a realistic 3D coherent transfer function (CTF) of a high-NA digital holographic microscope. By combining scattering theory and signal processing, the method is demonstrated to yield the reconstruction of a scattering object field. Experimental reconstructions in phase and amplitude are presented under non-design imaging conditions. The suggested technique is best suited for an implementation in high-resolution diffraction tomography based on sample or illumination rotation.

  20. Realistic 3D coherent transfer function inverse filtering of complex fields

    PubMed Central

    Cotte, Yann; Toy, Fatih M.; Arfire, Cristian; Kou, Shan Shan; Boss, Daniel; Bergoënd, Isabelle; Depeursinge, Christian

    2011-01-01

    We present a novel technique for three-dimensional (3D) image processing of complex fields. It consists in inverting the coherent image formation by filtering the complex spectrum with a realistic 3D coherent transfer function (CTF) of a high-NA digital holographic microscope. By combining scattering theory and signal processing, the method is demonstrated to yield the reconstruction of a scattering object field. Experimental reconstructions in phase and amplitude are presented under non-design imaging conditions. The suggested technique is best suited for an implementation in high-resolution diffraction tomography based on sample or illumination rotation. PMID:21833359

  1. Steady state reconnection at a single 3D magnetic null point

    NASA Astrophysics Data System (ADS)

    Galsgaard, K.; Pontin, D. I.

    2011-05-01

    Aims: We systematically stress a rotationally symmetric 3D magnetic null point by advecting the opposite footpoints of the spine axis in opposite directions. This stress eventually concentrates in the vicinity of the null point, thereby forming a local current sheet through which magnetic reconnection takes place. The aim is to look for a steady state evolution of the current sheet dynamics, which may provide scaling relations for various characteristic parameters of the system. Methods: The evolution is followed by solving numerically the non-ideal MHD equations in a Cartesian domain. The null point is embedded in an initially constant density and temperature plasma. Results: It is shown that a quasi-steady reconnection process can be set up at a 3D null by continuous shear driving. It appears that a true steady state is unlikely to be realised because the current layer tends to grow until it is restricted by the geometry of the computational domain and the imposed driving profile. However, ratios between characteristic quantities clearly settle after some time to stable values, so that the evolution is quasi-steady. The experiments show a number of scaling relations, but they do not provide a clear consensus for extending to lower magnetic resistivity or faster driving velocities. More investigations are needed to fully clarify the properties of current sheets at magnetic null points.

  2. Syntheses, structures, luminescence, and magnetism of four 3D lanthanide 5-sulfosalicylates

    SciTech Connect

    Zhou Ruisha; Ye Ling; Ding Hong; Song Jiangfeng; Xu Xiaoyu; Xu Jiqing

    2008-03-15

    Four 3D lanthanide(III) complexes with 5-sulfosalicylic acid (H{sub 3}SSA) as bridging ligands, Ln(SSA)(H{sub 2}O){sub 2} [Ln=Ce(III) (1), Pr(III) (2), Nd(III) (3) and Dy(III) (4)], have been synthesized and characterized by elemental analysis, IR, XRD and single-crystal X-ray diffraction. X-ray structural analysis reveals that isostructral complexes 1-4 possess 3D structures with 4{sup 6}6{sup 4} topology. Complexes 1 and 2 exhibit broad intraligand fluorescent emission bands. Complexes 3 and 4 not only display intraligand fluorescent emission bands, but also present Nd(III) characteristic emission in the near-IR region and sensitized luminescence of Dy(III) ions in the visible region, respectively. Variable-temperature magnetic susceptibility measurements of 2-4 have been studied over the temperature range of 4-300 K. - Graphical abstract: Syntheses and crystal structures of four 3D lanthanide-5-sulfosalicylates, Ln(SSA)(H{sub 2}O){sub 2} [Ln=Ce(III) (1), Pr(III) (2), Nd(III) (3), and Dy(III) (4)], have been reported. In complexes 1-4, Ln(III) acting as 5-connected inorganic node and SSA{sup 3-} ligand acing as 5-connected organic node interlink into rarely reported 4{sup 6}6{sup 4} topology network. Luminescence and magnetism properties have also been studied.

  3. Cosmological magnetic fields

    NASA Astrophysics Data System (ADS)

    Kunze, Kerstin E.

    2013-12-01

    Magnetic fields are observed on nearly all scales in the Universe, from stars and galaxies up to galaxy clusters and even beyond. The origin of cosmic magnetic fields is still an open question, however a large class of models puts its origin in the very early Universe. A magnetic dynamo amplifying an initial seed magnetic field could explain the present day strength of the galactic magnetic field. However, it is still an open problem how and when this initial magnetic field was created. Observations of the cosmic microwave background (CMB) provide a window to the early Universe and might therefore be able to tell us whether cosmic magnetic fields are of a primordial cosmological origin and at the same time constrain its parameters. We will give an overview of the observational evidence of large-scale magnetic fields, describe generation mechanisms of primordial magnetic fields and possible imprints in the CMB.

  4. Magnetic fields during galaxy mergers

    NASA Astrophysics Data System (ADS)

    Rodenbeck, Kai; Schleicher, Dominik R. G.

    2016-09-01

    Galaxy mergers are expected to play a central role for the evolution of galaxies and may have a strong effect on their magnetic fields. We present the first grid-based 3D magnetohydrodynamical simulations investigating the evolution of magnetic fields during merger events. For this purpose, we employed a simplified model considering the merger event of magnetized gaseous disks in the absence of stellar feedback and without a stellar or dark matter component. We show that our model naturally leads to the production of two peaks in the evolution of the average magnetic field strength within 5 kpc, within 25 kpc, and on scales in between 5 and 25 kpc. The latter is consistent with the peak in the magnetic field strength previously reported in a merger sequence of observed galaxies. We show that the peak on the galactic scale and in the outer regions is most likely due to geometrical effects, as the core of one galaxy enters the outskirts of the other one. In addition, the magnetic field within the central ~5 kpc is physically enhanced, which reflects the enhancement in density that is due to efficient angular momentum transport. We conclude that high-resolution observations of the central regions will be particularly relevant for probing the evolution of magnetic field structures during merger events.

  5. Assembly of Hepatocyte Spheroids Using Magnetic 3D Cell Culture for CYP450 Inhibition/Induction

    PubMed Central

    Desai, Pujan K.; Tseng, Hubert; Souza, Glauco R.

    2017-01-01

    There is a significant need for in vitro methods to study drug-induced liver injury that are rapid, reproducible, and scalable for existing high-throughput systems. However, traditional monolayer and suspension cultures of hepatocytes are difficult to handle and risk the loss of phenotype. Generally, three-dimensional (3D) cell culture platforms help recapitulate native liver tissue phenotype, but suffer from technical limitations for high-throughput screening, including scalability, speed, and handling. Here, we developed a novel assay for cytochrome P450 (CYP450) induction/inhibition using magnetic 3D cell culture that overcomes the limitations of other platforms by aggregating magnetized cells with magnetic forces. With this platform, spheroids can be rapidly assembled and easily handled, while replicating native liver function. We assembled spheroids of primary human hepatocytes in a 384-well format and maintained this culture over five days, including a 72 h induction period with known CYP450 inducers/inhibitors. CYP450 activity and viability in the spheroids were assessed and compared in parallel with monolayers. CYP450 activity was induced/inhibited in spheroids as expected, separate from any toxic response. Spheroids showed a significantly higher baseline level of CYP450 activity and induction over monolayers. Positive staining in spheroids for albumin and multidrug resistance-associated protein (MRP2) indicates the preservation of hepatocyte function within spheroids. The study presents a proof-of-concept for the use of magnetic 3D cell culture for the assembly and handling of novel hepatic tissue models. PMID:28524079

  6. 3-D seismic velocity and attenuation structures in the geothermal field

    SciTech Connect

    Nugraha, Andri Dian; Syahputra, Ahmad; Fatkhan,; Sule, Rachmat

    2013-09-09

    We conducted delay time tomography to determine 3-D seismic velocity structures (Vp, Vs, and Vp/Vs ratio) using micro-seismic events in the geothermal field. The P-and S-wave arrival times of these micro-seismic events have been used as input for the tomographic inversion. Our preliminary seismic velocity results show that the subsurface condition of geothermal field can be fairly delineated the characteristic of reservoir. We then extended our understanding of the subsurface physical properties through determining of attenuation structures (Qp, Qs, and Qs/Qp ratio) using micro-seismic waveform. We combined seismic velocities and attenuation structures to get much better interpretation of the reservoir characteristic. Our preliminary attanuation structures results show reservoir characterization can be more clearly by using the 3-D attenuation model of Qp, Qs, and Qs/Qp ratio combined with 3-D seismic velocity model of Vp, Vs, and Vp/Vs ratio.

  7. 3-D Flow Field Diagnostics and Validation Studies using Stereoscopic Tracking Velocimetry

    NASA Technical Reports Server (NTRS)

    Cha, Soyoung Stephen; Ramachandran, Narayanan; Whitaker, Ann F. (Technical Monitor)

    2002-01-01

    The measurement of 3-D three-component velocity fields is of great importance in both ground and space experiments for understanding materials processing and fluid physics. Here, we present the investigation results of stereoscopic tracking velocimetry (STV) for measuring 3-D velocity fields. The effort includes diagnostic technology development, experimental velocity measurement, and comparison with analytical and numerical computation. The advantages of STV stems from the system simplicity for building compact hardware and in software efficiency for continual near-real-time process monitoring. It also has illumination flexibility for observing volumetric flow fields from arbitrary directions. STV is based on stereoscopic CCD observations of particles seeded in a flow. Neural networks are used for data analysis. The developed diagnostic tool is tested with a simple directional solidification apparatus using Succinonitrile. The 3-D velocity field in the liquid phase is measured and compared with results from detailed numerical computations. Our theoretical, numerical, and experimental effort has shown STV to be a viable candidate for reliably quantifying the 3-D flow field in materials processing and fluids experiments.

  8. 3D Magnetization Vector Inversion of Magnetic Data: Improving and Comparing Methods

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Hu, Xiangyun; Zhang, Henglei; Geng, Meixia; Zuo, Boxin

    2017-09-01

    Magnetization vector inversion is an useful approach to invert for magnetic anomaly in the presence of significant remanent magnetization and self-demagnetization. However, magnetizations are usually obtained in many different directions under the influences of geophysical non-uniqueness. We propose an iteration algorithm of magnetization vector inversion (M-IDI) that one couple of magnetization direction is iteratively computed after the magnetization intensity is recovered from the magnitude magnetic anomaly. And we compare it with previous methods of (1) three orthogonal components inversion of total magnetization vector at Cartesian framework (MMM), (2) intensity, inclination and declination inversion at spherical framework (MID), (3) directly recovering the magnetization inclination and declination (M-IDCG) and (4) estimating the magnetization direction using correlation method (M-IDC) at the sequential inversion frameworks. The synthetic examples indicate that MMM returns multiply magnetization directions and MID results are strongly dependent on initial model and parameter weights. M-IDI computes faster than M-IDC and achieves a constant magnetization direction compared with M-IDCG. Additional priori information constraints can improve the results of MMM, MID and M-IDCG. Obtaining one magnetization direction, M-IDC and M-IDI are suitable for single and isolated anomaly. Finally, M-IDI and M-IDC are used to invert and interpret the magnetic anomaly of the Galinge iron-ore deposit (NW China) and the results are verified by information from drillholes and physical properties measurements of ore and rock samples. Magnetization vector inversion provides a comprehensive way to evaluate and investigate the remanent magnetization and self-demagnetization.

  9. Series of chiral interpenetrating 3d-4f heterometallic MOFs: Luminescent sensors and magnetic properties

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolei; Chen, Chen; Liu, Xiaoli; Gao, Peng; Hu, Ming

    2017-09-01

    Series of chiral 3d-4f heterometallic MOFs based on a multidentate terpyridyl carboxylic acid ligand have been synthesized under the solvothermal conditions, namely, [LnZnL(CO3)2(H2O)]n (Ln = Eu (1), Gd (2), Dy (3), Ho (4), Er (5), Tm (6), Yb (7), Lu (8)) (HL = 4‧-(4-carboxyphenyl)-2,2‧:6‧,2″-terpyridine). Compounds 1-8 were structurally characterized by the elemental analyses, infrared spectra, and single crystal X-ray diffractions. Compounds 1-8 exhibit the chiral interpenetrating 3D frameworks. Interestingly, 1 can serve as the luminescent sensor to detect nitrobenzene molecules with high sensitivity. The investigations on CD spectra of single crystals clearly assigned the Cotton effect, indicating that there exist two chiral enantiomers of 1-8 in the course of crystallization. The magnetic properties of 2 and 7 were exploited, respectively.

  10. Enhanced Electron Heating and Mixing in a 3D Kinetic Simulation for MMS Magnetopause Crossings with Weak Guide Fields

    NASA Astrophysics Data System (ADS)

    Le, Ari; Daughton, William; Chen, Li-Jen; Egedal, Jan

    2016-10-01

    We present a 3D kinetic simulation of asymmetric reconnection with plasma parameters matching the MMS magetopause diffusion region crossing reported by Burch et al. (Science 2016). The simulation was performed with the code VPIC on LANL's Trinity machine, which enabled relatively high grid resolution and numerical particle numbers to resolve the electron diffusion region dynamics. The simulation not only reproduces the reported crescent distributions but also appears to account for new features observed by MMS in other diffusion region events with weak guide fields. Compared to a 2D simulation with the same plasma parameters, drift turbulence in the 3D simulation substantially enhances the mixing and parallel heating of electrons on the magnetosphere side. This modifies the reconnection rate inferred from a recently introduced electron mixing diagnostic. To the magnetosphere side of the in-plane magnetic null, the parallel electric field exhibits a bipolar structure with polarities opposite to the large-scale parallel electric field. The 3D structure of the X line and the particle signature of the inverted bipolar parallel electric field have been observed by MMS.

  11. 3D mapping of neuronal migration in the embryonic mouse brain with magnetic resonance microimaging.

    PubMed

    Deans, Abby E; Wadghiri, Youssef Zaim; Aristizábal, Orlando; Turnbull, Daniel H

    2015-07-01

    A prominent feature of the developing mammalian brain is the widespread migration of neural progenitor (NP) cells during embryogenesis. A striking example is provided by NP cells born in the ventral forebrain of mid-gestation stage mice, which subsequently migrate long distances to their final positions in the cortex and olfactory bulb. Previous studies have used two-dimensional histological methods, making it difficult to analyze three-dimensional (3D) migration patterns. Unlike histology, magnetic resonance microimaging (micro-MRI) is a non-destructive, quantitative and inherently 3D imaging method for analyzing mouse embryos. To allow mapping of migrating NP cells with micro-MRI, cells were labeled in situ in the medial (MGE) and lateral (LGE) ganglionic eminences, using targeted in utero ultrasound-guided injection of micron-sized particles of iron-oxide (MPIO). Ex vivo micro-MRI and histology were then performed 5-6days after injection, demonstrating that the MPIO had magnetically labeled the migrating NP populations, which enabled 3D visualization and automated segmentation of the labeled cells. This approach was used to analyze the distinct patterns of migration from the MGE and LGE, and to construct rostral-caudal migration maps from each progenitor region. Furthermore, abnormal migratory phenotypes were observed in Nkx2.1(-/-) embryos, most notably a significant increase in cortical neurons derived from the Nkx2.1(-/-) LGE. Taken together, these results demonstrate that MPIO labeling and micro-MRI provide an efficient and powerful approach for analyzing 3D cell migration patterns in the normal and mutant mouse embryonic brain.

  12. Facility Measures Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Honess, Shawn B.; Narvaez, Pablo; Mcauley, James M.

    1991-01-01

    Partly automated facility measures and computes steady near magnetic field produced by object. Designed to determine magnetic fields of equipment to be installed on spacecraft including sensitive magnetometers, with view toward application of compensating fields to reduce interfernece with spacecraft-magnetometer readings. Because of its convenient operating features and sensitivity of its measurements, facility serves as prototype for similar facilities devoted to magnetic characterization of medical equipment, magnets for high-energy particle accelerators, and magnetic materials.

  13. 3D imaging of magnetic particles using the 7-channel magnetoencephalography device without pre-magnetization or displacement of the sample

    NASA Astrophysics Data System (ADS)

    Polikarpov, M. A.; Ustinin, M. N.; Rykunov, S. D.; Yurenya, A. Y.; Naurzakov, S. P.; Grebenkin, A. P.; Panchenko, V. Y.

    2017-04-01

    SQUID-based magnetoencephalography device was used for the measurement of a magnetic noise generated by ferrofluid in the stationary standing vial. It was found that a free surface of the ferrofluid generates spontaneous magnetic field sufficient to detect the presence of nanoparticles in the experimental setup. The spatial distribution of elementary magnetic sources was reconstructed by the frequency-pattern analysis of multichannel time series. The localization of ferrofluids was performed based on the analysis of quasirandom time series in two cases of oscillation source. One of them was infrasound from outer noise, and another one was the human heartbeat. These results are prospective for 3D imaging of magnetic particles without pre-magnetization.

  14. Motion field estimation for a dynamic scene using a 3D LiDAR.

    PubMed

    Li, Qingquan; Zhang, Liang; Mao, Qingzhou; Zou, Qin; Zhang, Pin; Feng, Shaojun; Ochieng, Washington

    2014-09-09

    This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively.

  15. Motion Field Estimation for a Dynamic Scene Using a 3D LiDAR

    PubMed Central

    Li, Qingquan; Zhang, Liang; Mao, Qingzhou; Zou, Qin; Zhang, Pin; Feng, Shaojun; Ochieng, Washington

    2014-01-01

    This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively. PMID:25207868

  16. Numerical Optimization Strategy for Determining 3D Flow Fields in Microfluidics

    NASA Astrophysics Data System (ADS)

    Eden, Alex; Sigurdson, Marin; Mezic, Igor; Meinhart, Carl

    2015-11-01

    We present a hybrid experimental-numerical method for generating 3D flow fields from 2D PIV experimental data. An optimization algorithm is applied to a theory-based simulation of an alternating current electrothermal (ACET) micromixer in conjunction with 2D PIV data to generate an improved representation of 3D steady state flow conditions. These results can be used to investigate mixing phenomena. Experimental conditions were simulated using COMSOL Multiphysics to solve the temperature and velocity fields, as well as the quasi-static electric fields. The governing equations were based on a theoretical model for ac electrothermal flows. A Nelder-Mead optimization algorithm was used to achieve a better fit by minimizing the error between 2D PIV experimental velocity data and numerical simulation results at the measurement plane. By applying this hybrid method, the normalized RMS velocity error between the simulation and experimental results was reduced by more than an order of magnitude. The optimization algorithm altered 3D fluid circulation patterns considerably, providing a more accurate representation of the 3D experimental flow field. This method can be generalized to a wide variety of flow problems. This research was supported by the Institute for Collaborative Biotechnologies through grant W911NF-09-0001 from the U.S. Army Research Office.

  17. Color Flat Panel Displays: 3D Autostereoscopic Brassboard and Field Sequential Illumination Technology.

    DTIC Science & Technology

    1997-06-01

    DTI has advanced autostereoscopic and field sequential color (FSC) illumination technologies for flat panel displays. Using a patented backlight...technology, DTI has developed prototype 3D flat panel color display that provides stereoscopic viewing without the need for special glasses or other... autostereoscopic viewing. Discussions of system architecture, critical component specifications and resultant display characteristics are provided. Also

  18. Experimental Investigation of 3-D Global Magnetic Reconnection by Use of Merging Plasmas

    NASA Astrophysics Data System (ADS)

    Ono, Yasushi

    1996-11-01

    A laboratory experiment of magnetic reconnection and plasma merging has been developed in the TS-3 merging device at University of Tokyo by use of two colliding spheromaks and tokamaks. The global MHD physics issues for magnetic reconnection have been primarily investigated( M. Katsurai and Y. Ono, Trans. Inst. Electr. Eng. Jpn. 107, 65 (1987)), together with the global equilibrium transition of counter-helicity spheromaks to a high-beta FRC( Y. Ono et al.), Plas. Phys. Cont. Nucl. Rus. Res. 1992, Wurzburg, 2, p. 619 (1992). The 3-D features of magnetic reconnection were found to be quite different from the 2-D features depending on whether the plasma toroids have co-helicity or counter-helicity configurations( M. Yamada et al.), Phys. Rev. Letts. 65, 721 (1990). Evidences of driven reconnection have been observed and a quantitative dependence of the reconnection rate on external force was documented in connection with the anomalous dissipation of the current sheet. A new plasma acceleration mechanism accompanied by a significant direct ion heating has been measured during the 3-D reconnection process( Y. Ono et al.), Phys. Rev. Letts. vol.76, 3328 (1996).

  19. Investigation of the 3-D actinic flux field in mountainous terrain

    PubMed Central

    Wagner, J.E.; Angelini, F.; Blumthaler, M.; Fitzka, M.; Gobbi, G.P.; Kift, R.; Kreuter, A.; Rieder, H.E.; Simic, S.; Webb, A.; Weihs, P.

    2011-01-01

    During three field campaigns spectral actinic flux was measured from 290–500 nm under clear sky conditions in Alpine terrain and the associated O3- and NO2-photolysis frequencies were calculated and the measurement products were then compared with 1-D- and 3-D-model calculations. To do this 3-D-radiative transfer model was adapted for actinic flux calculations in mountainous terrain and the maps of the actinic flux field at the surface, calculated with the 3-D-radiative transfer model, are given. The differences between the 3-D- and 1-D-model results for selected days during the campaigns are shown, together with the ratios of the modeled actinic flux values to the measurements. In many cases the 1-D-model overestimates actinic flux by more than the measurement uncertainty of 10%. The results of using a 3-D-model generally show significantly lower values, and can underestimate the actinic flux by up to 30%. This case study attempts to quantify the impact of snow cover in combination with topography on spectral actinic flux. The impact of snow cover on the actinic flux was ~ 25% in narrow snow covered valleys, but for snow free areas there were no significant changes due snow cover in the surrounding area and it is found that the effect snow-cover at distances over 5 km from the point of interest was below 5%. Overall the 3-D-model can calculate actinic flux to the same accuracy as the 1-D-model for single points, but gives a much more realistic view of the surface actinic flux field in mountains as topography and obstruction of the horizon are taken into account. PMID:26412915

  20. Field lens multiplexing in holographic 3D displays by using Bragg diffraction based volume gratings

    NASA Astrophysics Data System (ADS)

    Fütterer, G.

    2016-11-01

    Applications, which can profit from holographic 3D displays, are the visualization of 3D data, computer-integrated manufacturing, 3D teleconferencing and mobile infotainment. However, one problem of holographic 3D displays, which are e.g. based on space bandwidth limited reconstruction of wave segments, is to realize a small form factor. Another problem is to provide a reasonable large volume for the user placement, which means to provide an acceptable freedom of movement. Both problems should be solved without decreasing the image quality of virtual and real object points, which are generated within the 3D display volume. A diffractive optical design using thick hologram gratings, which can be referred to as Bragg diffraction based volume gratings, can provide a small form factor and high definition natural viewing experience of 3D objects. A large collimated wave can be provided by an anamorphic backlight unit. The complex valued spatial light modulator add local curvatures to the wave field he is illuminated with. The modulated wave field is focused onto to the user plane by using a volume grating based field lens. Active type liquid crystal gratings provide 1D fine tracking of approximately +/- 8° deg. Diffractive multiplex has to be implemented for each color and for a set of focus functions providing coarse tracking. Boundary conditions of the diffractive multiplexing are explained. This is done in regards to the display layout and by using the coupled wave theory (CWT). Aspects of diffractive cross talk and its suppression will be discussed including longitudinal apodized volume gratings.

  1. Interpretation of gravity and magnetic data with geological constraints for 3D structure of the Thuringian Basin, Germany

    NASA Astrophysics Data System (ADS)

    Prutkin, Ilya; Vajda, Peter; Jahr, Thomas; Bleibinhaus, Florian; Novák, Pavel; Tenzer, Robert

    2017-01-01

    We apply a novel method for the separation of potential field sources and their 3D inversion at the regional study area of Thuringian Basin in central Germany. The gravity and magnetic data are separated into long, medium and short wavelengths and then inverted separately. The main goal is to study uniqueness of the solution and its stability in all numerical steps of the interpretation process and to demonstrate, how geological constraints can diminish the degree of non-uniqueness by the interpretation of the gravity and magnetic anomalies. Our numerical experiments with medium wavelengths reveal that if we explain negative anomalies with the topography of near-surface layers, the obtained solution is not supported by borehole data. These negative anomalies are thus explained by restricted bodies (granitic intrusions) at the depths from 4 down to 10 km. These bodies are located above a density interface with topography at the depth of approximately 10 km. The 3D inversion of magnetic data (at short wavelengths) allows investigating a detailed structure of the upper boundary of the crystalline basement: two uplifts in the depths between 2.0 and 0.7 km are found. By using the residual negative anomalies we further study the salt tectonics, showing that the geometry of a salt pillow with a thickness of approximately 200 m closely agrees with borehole data.

  2. Observation of toroidal variation of density gradients and turbulence in DIII-D with 3D fields during ELM suppression

    NASA Astrophysics Data System (ADS)

    Wilcox, R. S.; Schafer, M. W.; Canik, J. M.; Unterberg, E. A.; Wingen, A.; Ferraro, N. M.; McKee, G. R.; Zeng, L.; Rhodes, T. L.

    2016-10-01

    Significant 3D variation in broadband density fluctuations is observed using beam emission spectroscopy and Doppler backscattering near the boundary of weakly 3D plasmas in DIII-D when non-axisymmetric fields are applied to suppress ELMs. The increase in fluctuations is concomitant with an increase in the density gradient measured using profile reflectometry, suggesting that this toroidally localized density gradient could be a mechanism for turbulence destabilization in localized flux tubes. Although changes to magnetic surface topology are shown to be too small to affect turbulence stability directly, two-fluid M3D-C1 simulations find that there is a significant 3D variation of density within flux surfaces in the pedestal. These modeled local density changes modify the local pressure- and density- gradient scale lengths, and measured turbulence is shown to increase on flux tubes with larger gradients. Work supported by the US DOE under contracts DE-AC05-00OR22725, DE-AC02-09CH11466, DE-FG02-08ER54999 and DE-FG02-08ER54984.

  3. Moving from Batch to Field Using the RT3D Reactive Transport Modeling System

    NASA Astrophysics Data System (ADS)

    Clement, T. P.; Gautam, T. R.

    2002-12-01

    The public domain reactive transport code RT3D (Clement, 1997) is a general-purpose numerical code for solving coupled, multi-species reactive transport in saturated groundwater systems. The code uses MODFLOW to simulate flow and several modules of MT3DMS to simulate the advection and dispersion processes. RT3D employs the operator-split strategy which allows the code solve the coupled reactive transport problem in a modular fashion. The coupling between reaction and transport is defined through a separate module where the reaction equations are specified. The code supports a versatile user-defined reaction option that allows users to define their own reaction system through a Fortran-90 subroutine, known as the RT3D-reaction package. Further a utility code, known as BATCHRXN, allows the users to independently test and debug their reaction package. To analyze a new reaction system at a batch scale, users should first run BATCHRXN to test the ability of their reaction package to model the batch data. After testing, the reaction package can simply be ported to the RT3D environment to study the model response under 1-, 2-, or 3-dimensional transport conditions. This paper presents example problems that demonstrate the methods for moving from batch to field-scale simulations using BATCHRXN and RT3D codes. The first example describes a simple first-order reaction system for simulating the sequential degradation of Tetrachloroethene (PCE) and its daughter products. The second example uses a relatively complex reaction system for describing the multiple degradation pathways of Tetrachloroethane (PCA) and its daughter products. References 1) Clement, T.P, RT3D - A modular computer code for simulating reactive multi-species transport in 3-Dimensional groundwater aquifers, Battelle Pacific Northwest National Laboratory Research Report, PNNL-SA-28967, September, 1997. Available at: http://bioprocess.pnl.gov/rt3d.htm.

  4. Feasibility of using PRESAGE® for relative 3D dosimetry of small proton fields

    PubMed Central

    Zhao, Li; Newton, Joseph; Oldham, Mark; Das, Indra J; Cheng, Chee-Wai; Adamovics, John

    2013-01-01

    Small field dosimetry is challenging due to the finite size of the conventional detectors that underestimate the dose distribution. With the fast development of the dynamic proton beam delivery system, it is essential to find a dosimeter which can be used for 3D dosimetry of small proton fields. We investigated the feasibility of using a proton formula PRESAGE® for 3D dosimetry of small fields in a uniform scanning proton beam delivery system with dose layer stacking technology. The relationship between optical density and the absorbed dose was found to be linear through small volume cuvette studies for both photon and proton irradiation. Two circular fields and three patient-specific fields were used for proton treatment planning calculation and beam delivery. The measured results were compared with the calculated results in the form of lateral dose profiles, depth dose, isodose plots and gamma index analysis. For the circular field study, lateral dose profile comparison showed that the relative PRESAGE® profile falls within ± 5% from the calculated profile for most of the spatial range. For unmodulated depth dose comparison, the agreement between the measured and calculated results was within 3% in the beam entrance region before the Bragg peak. However, at the Bragg peak, there was about 20% underestimation of the absorbed dose from PRESAGE®. For patient-specific field 3D dosimetry, most of the data points within the target volume passed gamma analysis for 3% relative dose difference and 3 mm distance to agreement criteria. Our results suggest that this proton formula PRESAGE® dosimeter has the potential for 3D dosimetry of small fields in proton therapy, but further investigation is needed to improve the dose under-response of the PRESAGE® in the Bragg peak region. PMID:23103526

  5. 3D In Vitro Model for Breast Cancer Research Using Magnetic Levitation and Bioprinting Method.

    PubMed

    Leonard, Fransisca; Godin, Biana

    2016-01-01

    Tumor microenvironment composition and architecture are known as a major factor in orchestrating the tumor growth and its response to various therapies. In this context, in vivo studies are necessary to evaluate the responses. However, while tumor cells can be of human origin, tumor microenvironment in the in vivo models is host-based. On the other hand, in vitro studies in a flat monoculture of tumor cells (the most frequently used in vitro tumor model) are unable to recapitulate the complexity of tumor microenvironment. Three-dimensional (3D) in vitro cell cultures of tumor cells have been proven to be an important experimental tool in understanding mechanisms of tumor growth, response to therapeutics, and transport of nutrients/drugs. We have recently described a novel tool to create 3D co-cultures of tumor cells and cells in the tumor microenvironment. Our method utilizes magnetic manipulation/levitation of the specific ratios of tumor cells and cells in the tumor microenvironment (from human or animal origin) aiding in the formation of tumor spheres with defined cellular composition and density, as quickly as within 24 h. This chapter describes the experimental protocols developed to model the 3D structure of the cancer environment using the above method.

  6. 3D kinematics of the tarsal joints from magnetic resonance images

    NASA Astrophysics Data System (ADS)

    Hirsch, Bruce E.; Udupa, Jayaram K.; Okereke, Enyi; Hillstrom, Howard J.; Siegler, Sorin; Ringleb, Stacie I.; Imhauser, Carl W.

    2001-09-01

    We have developed a method for analyzing motion at skeletal joints based on the 3D reconstruction of magnetic resonance (MR) image data. Since the information about each voxel in MR images includes its location in the scanner, it follows that information is available for each organ whose 3D surface is computed from a series of MR slices. In addition, there is information on the shape and orientation of each organ, and the contact areas of adjacent bones. By collecting image data in different positions we can calculate the motion of the individual bones. We have used this method to study human foot bones, in order to understand normal and abnormal foot function. It has been used to evaluate patients with tarsal coalitions, various forms of pes planus, ankle sprains, and several other conditions. A newly described feature of this system is the ability to visualize the contact area at a joint, as determined by the region of minimum distance. The display of contact area helps understand abnormal joint function. Also, the use of 3D imaging reveals motions in joints which cannot otherwise be visualized, such as the subtalar joint, for more accurate diagnosis of joint injury.

  7. 3D in vitro model for breast cancer research using magnetic levitation and bioprinting method

    PubMed Central

    Leonard, Fransisca; Godin, Biana

    2016-01-01

    Summary Tumor microenvironment composition and architecture are known as a major factor in orchestrating the tumor growth and its response to various therapies. In this context, in vivo studies are necessary to evaluate the responses. However, while tumor cells can be of human origin, tumor microenvironment in the in vivo models is host-based. On the other hand, in vitro studies in a flat monoculture of tumor cells (the most frequently used in vitro tumor model) are unable to recapitulate the complexity of tumor microenvironment. Three-dimensional (3D) in vitro cell cultures of tumor cells have been proven to be an important experimental tool in understanding mechanisms of tumor growth, response to therapeutics and transport of nutrients/drugs. We have recently described a novel tool to create 3D co-cultures of tumor cells and cells in the tumor microenvironment. Our method utilizes magnetic manipulation/levitation of the specific ratios of tumor cells and cells in the tumor microenvironment (from human or animal origin) aiding in the formation of tumor spheres with defined cellular composition and density, as quickly as within 24 hours. This chapter describes the experimental protocols developed to model the 3D structure of the cancer environment using the above method. PMID:26820961

  8. Wave optics theory and 3-D deconvolution for the light field microscope.

    PubMed

    Broxton, Michael; Grosenick, Logan; Yang, Samuel; Cohen, Noy; Andalman, Aaron; Deisseroth, Karl; Levoy, Marc

    2013-10-21

    Light field microscopy is a new technique for high-speed volumetric imaging of weakly scattering or fluorescent specimens. It employs an array of microlenses to trade off spatial resolution against angular resolution, thereby allowing a 4-D light field to be captured using a single photographic exposure without the need for scanning. The recorded light field can then be used to computationally reconstruct a full volume. In this paper, we present an optical model for light field microscopy based on wave optics, instead of previously reported ray optics models. We also present a 3-D deconvolution method for light field microscopy that is able to reconstruct volumes at higher spatial resolution, and with better optical sectioning, than previously reported. To accomplish this, we take advantage of the dense spatio-angular sampling provided by a microlens array at axial positions away from the native object plane. This dense sampling permits us to decode aliasing present in the light field to reconstruct high-frequency information. We formulate our method as an inverse problem for reconstructing the 3-D volume, which we solve using a GPU-accelerated iterative algorithm. Theoretical limits on the depth-dependent lateral resolution of the reconstructed volumes are derived. We show that these limits are in good agreement with experimental results on a standard USAF 1951 resolution target. Finally, we present 3-D reconstructions of pollen grains that demonstrate the improvements in fidelity made possible by our method.

  9. Wave optics theory and 3-D deconvolution for the light field microscope

    PubMed Central

    Broxton, Michael; Grosenick, Logan; Yang, Samuel; Cohen, Noy; Andalman, Aaron; Deisseroth, Karl; Levoy, Marc

    2013-01-01

    Light field microscopy is a new technique for high-speed volumetric imaging of weakly scattering or fluorescent specimens. It employs an array of microlenses to trade off spatial resolution against angular resolution, thereby allowing a 4-D light field to be captured using a single photographic exposure without the need for scanning. The recorded light field can then be used to computationally reconstruct a full volume. In this paper, we present an optical model for light field microscopy based on wave optics, instead of previously reported ray optics models. We also present a 3-D deconvolution method for light field microscopy that is able to reconstruct volumes at higher spatial resolution, and with better optical sectioning, than previously reported. To accomplish this, we take advantage of the dense spatio-angular sampling provided by a microlens array at axial positions away from the native object plane. This dense sampling permits us to decode aliasing present in the light field to reconstruct high-frequency information. We formulate our method as an inverse problem for reconstructing the 3-D volume, which we solve using a GPU-accelerated iterative algorithm. Theoretical limits on the depth-dependent lateral resolution of the reconstructed volumes are derived. We show that these limits are in good agreement with experimental results on a standard USAF 1951 resolution target. Finally, we present 3-D reconstructions of pollen grains that demonstrate the improvements in fidelity made possible by our method. PMID:24150383

  10. Calculating Pressure-Driven Current Near Magnetic Islands for 3D MHD Equilibria

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Dhanush; Reiman, Allan

    2016-10-01

    In general, 3D MHD equilibria in toroidal plasmas do not result in nested pressure surfaces. Instead, islands and chaotic regions appear in the equilibrium. Near small magnetic islands, the pressure varies within the flux surfaces, which has a significant effect on the pressure-driven current, introducing singularities. Previously, the MHD equilibrium current near a magnetic island was calculated, including the effect of ``stellarator symmetry,'' wherein the singular components of the pressure-driven current vanish [A. H. Reiman, Phys. Plasmas 23, 072502 (2016)]. Here we first solve for pressure in a cylindrical plasma from the heat diffusion equation, after adding a helical perturbation. We then numerically calculate the corresponding Pfirsch-Schluter current. At the small island limit, we compare the pressure-driven current with the previously calculated solution, and far from the island, we recover the solution for nested flux surfaces. Lastly, we compute the current for a toroidal plasma for symmetric and non-symmetric geometries.

  11. Evaluation of 3D multi-contrast joint intra- and extracranial vessel wall cardiovascular magnetic resonance.

    PubMed

    Zhou, Zechen; Li, Rui; Zhao, Xihai; He, Le; Wang, Xiaole; Wang, Jinnan; Balu, Niranjan; Yuan, Chun

    2015-05-27

    Multi-contrast vessel wall cardiovascular magnetic resonance (CMR) has demonstrated its capability for atherosclerotic plaque morphology measurement and component characterization in different vasculatures. However, limited coverage and partial volume effect with conventional two-dimensional (2D) techniques might cause lesion underestimation. The aim of this work is to evaluate the performance in a) blood suppression and b) vessel wall delineation of three-dimensional (3D) multi-contrast joint intra- and extracranial vessel wall imaging at 3T. Three multi-contrast 3D black blood (BB) sequences with T1, T2 and heavy T1 weighting and a custom designed 36-channel neurovascular coil covering the entire intra- and extracranial vasculature have been used and investigated in this study. Two healthy subjects were recruited for sequence parameter optimization and twenty-five patients were consecutively scanned for image quality and blood suppression assessment. Qualitative image scores of vessel wall delineation as well as quantitative Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) were evaluated at five typical locations ranging from common carotid arteries to middle cerebral arteries. The 3D multi-contrast images acquired within 15mins allowed the vessel wall visualization with 0.8 mm isotropic spatial resolution covering intra- and extracranial segments. Quantitative wall and lumen SNR measurements for each sequence showed effective blood suppression at all selected locations (P < 0.0001). Although the wall-lumen CNR varied across measured locations, each sequence provided good or adequate image quality in both intra- and extracranial segments. The proposed 3D multi-contrast vessel wall technique provides isotropic resolution and time efficient solution for joint intra- and extracranial vessel wall CMR.

  12. Radial electric field 3D modeling for wire arrays driving dynamic hohlraums on Z.

    SciTech Connect

    Mock, Raymond Cecil

    2007-06-01

    The anode-cathode structure of the Z-machine wire array results in a higher negative radial electric field (Er) on the wires near the cathode relative to the anode. The magnitude of this field has been shown to anti-correlate with the axial radiation top/bottom symmetry in the DH (Dynamic Hohlraum). Using 3D modeling, the structure of this field is revealed for different wire-array configurations and for progressive mechanical alterations, providing insight for minimizing the negative Er on the wire array in the anode-to-cathode region of the DH. Also, the 3D model is compared to Sasorov's approximation, which describes Er at the surface of the wire in terms of wire-array parameters.

  13. Analysis of 3d Magnetotelluric Measurements Over the Coso Geothermal Field

    NASA Astrophysics Data System (ADS)

    Newman, G. A.; Gasperikova, E.; Hoversten, M.

    2007-12-01

    We have carried out an investigation of the Coso Geothermal field utilizing a dense grid of magnetotelluric (MT) stations plus a single line of contiguous bipole array profiling over the east flank of the field. Motivation for this study is that electrical resistivity/conductivity mapping can contribute to better understanding of enhanced geothermal systems (EGS) by imaging the geometry, bounds and controlling structures in existing production, and by monitoring changes in the underground resistivity properties in the vicinity of injection due to fracture porosity enhancement. Initial analysis of the Coso MT data was carried out using 2D MT imaging technology to construct a starting 3D resistivity model from a series of 2D resistivity images obtained using the inline electric field measurements (Zxy impedance elements) along different measurement transects. This model was then refined through a 3D inversion process. The 3D resisitivity model clearly showed the controlling geological structures influencing well production at Coso and shows correlations with mapped surface features such as faults and regional geoelectric strike. We have also correlated the model with an acoustic and shear velocity model of the field to show that the near-vertical high conductivity (low resistivity) structure on the eastern flank of the producing field is also a zone of increase acoustic velocity and increased Vp/Vs ratio.

  14. Exploring Direct 3D Interaction for Full Horizontal Parallax Light Field Displays Using Leap Motion Controller

    PubMed Central

    Adhikarla, Vamsi Kiran; Sodnik, Jaka; Szolgay, Peter; Jakus, Grega

    2015-01-01

    This paper reports on the design and evaluation of direct 3D gesture interaction with a full horizontal parallax light field display. A light field display defines a visual scene using directional light beams emitted from multiple light sources as if they are emitted from scene points. Each scene point is rendered individually resulting in more realistic and accurate 3D visualization compared to other 3D displaying technologies. We propose an interaction setup combining the visualization of objects within the Field Of View (FOV) of a light field display and their selection through freehand gesture tracked by the Leap Motion Controller. The accuracy and usefulness of the proposed interaction setup was also evaluated in a user study with test subjects. The results of the study revealed high user preference for free hand interaction with light field display as well as relatively low cognitive demand of this technique. Further, our results also revealed some limitations and adjustments of the proposed setup to be addressed in future work. PMID:25875189

  15. Critical Point Cancellation in 3D Vector Fields: Robustness and Discussion.

    PubMed

    Skraba, Primoz; Rosen, Paul; Wang, Bei; Chen, Guoning; Bhatia, Harsh; Pascucci, Valerio

    2016-02-29

    Vector field topology has been successfully applied to represent the structure of steady vector fields. Critical points, one of the essential components of vector field topology, play an important role in describing the complexity of the extracted structure. Simplifying vector fields via critical point cancellation has practical merit for interpreting the behaviors of complex vector fields such as turbulence. However, there is no effective technique that allows direct cancellation of critical points in 3D. This work fills this gap and introduces the first framework to directly cancel pairs or groups of 3D critical points in a hierarchical manner with a guaranteed minimum amount of perturbation based on their robustness, a quantitative measure of their stability. In addition, our framework does not require the extraction of the entire 3D topology, which contains non-trivial separation structures, and thus is computationally effective. Furthermore, our algorithm can remove critical points in any subregion of the domain whose degree is zero and handle complex boundary configurations, making it capable of addressing challenging scenarios that may not be resolved otherwise. We apply our method to synthetic and simulation datasets to demonstrate its effectiveness.

  16. Integrating a High Resolution Optically Pumped Magnetometer with a Multi-Rotor UAV towards 3-D Magnetic Gradiometry

    NASA Astrophysics Data System (ADS)

    Braun, A.; Walter, C. A.; Parvar, K.

    2016-12-01

    The current platforms for collecting magnetic data include dense coverage, but low resolution traditional airborne surveys, and high resolution, but low coverage terrestrial surveys. Both platforms leave a critical observation gap between the ground surface and approximately 100m above ground elevation, which can be navigated efficiently by new technologies, such as Unmanned Aerial Vehicles (UAVs). Specifically, multi rotor UAV platforms provide the ability to sense the magnetic field in a full 3-D tensor, which increases the quality of data collected over other current platform types. Payload requirements and target requirements must be balanced to fully exploit the 3-D magnetic tensor. This study outlines the integration of a GEM Systems Cesium Vapour UAV Magnetometer, a Lightware SF-11 Laser Altimeter and a uBlox EVK-7P GPS module with a DJI s900 Multi Rotor UAV. The Cesium Magnetometer is suspended beneath the UAV platform by a cable of varying length. A set of surveys was carried out to optimize the sensor orientation, sensor cable length beneath the UAV and data collection methods of the GEM Systems Cesium Vapour UAV Magnetometer when mounted on the DJI s900. The target for these surveys is a 12 inch steam pipeline located approximately 2 feet below the ground surface. A systematic variation of cable length, sensor orientation and inclination was conducted. The data collected from the UAV magnetometer was compared to a terrestrial survey conducted with the GEM GST-19 Proton Procession Magnetometer at the same elevation, which also served a reference station. This allowed for a cross examination between the UAV system and a proven industry standard for magnetic field data collection. The surveys resulted in optimizing the above parameters based on minimizing instrument error and ensuring reliable data acquisition. The results demonstrate that optimizing the UAV magnetometer survey can yield to industry standard measurements.

  17. Feasibility of 3D printed air slab diode caps for small field dosimetry.

    PubMed

    Perrett, Benjamin; Charles, Paul; Markwell, Tim; Kairn, Tanya; Crowe, Scott

    2017-07-31

    Commercial diode detectors used for small field dosimetry introduce a field-size-dependent over-response relative to an ideal, water-equivalent dosimeter due to high density components in the body of the detector. An air gap above the detector introduces a field-size-dependent under-response, and can be used to offset the field-size-dependent detector over-response. Other groups have reported experimental validation of caps containing air gaps for use with several types of diodes in small fields. This paper examines two designs for 3D printed diode air caps for the stereotactic field diode (SFD)-a cap containing a sealed air cavity, and a cap with an air cavity at the face of the SFD. Monte Carlo simulations of both designs were performed to determine dimensions for an air cavity to introduce the desired dosimetric correction. Various parameter changes were also simulated to estimate the dosimetric uncertainties introduced by 3D printing. Cap layer dimensions, cap density changes due to 3D printing, and unwanted air gaps were considered. For the sealed design the optimal air gap size for water-equivalent cap material was 0.6 mm, which increased to 1.0 mm when acrylonitrile butadiene styrene in the cap was simulated. The unsealed design had less variation, a 0.4 mm air gap is optimal in both situations. Unwanted air pockets in the bore of the cap and density changes introduced by the 3D printing process can potentially introduce significant dosimetric effects. These effects may be limited by using fine print resolutions and minimising the volume of cap material.

  18. A 3D radiative transfer framework . VII. Arbitrary velocity fields in the Eulerian frame

    NASA Astrophysics Data System (ADS)

    Seelmann, A. M.; Hauschildt, P. H.; Baron, E.

    2010-11-01

    Aims: A solution of the radiative-transfer problem in 3D with arbitrary velocity fields in the Eulerian frame is presented. The method is implemented in our 3D radiative transfer framework and used in the PHOENIX/3D code. It is tested by comparison to our well-tested 1D co-moving frame radiative transfer code, where the treatment of a monotonic velocity field is implemented in the Lagrangian frame. The Eulerian formulation does not need much additional memory and is useable on state-of-the-art computers, even large-scale applications with 1000's of wavelength points are feasible. Methods: In the Eulerian formulation of the problem, the photon is seen by the atom at a Doppler-shifted wavelength depending on its propagation direction, which leads to a Doppler-shifted absorption and emission. This leads to a different source function and a different Λ^* operator in the radiative transfer equations compared to the static case. Results: The results of the Eulerian 3D spherical calculations are compared to our well-tested 1D Lagrangian spherical calculations, the agreement is, up to vmax = 1 × 103 km s-1 very good. Test calculation in other geometries are also shown.

  19. Heptanuclear 3d-4f cluster complexes with a coaxial double-screw-propeller topology and diverse magnetic properties.

    PubMed

    Liu, Cai-Ming; Zhang, De-Qing; Zhu, Dao-Ben

    2010-12-21

    Two novel coaxial double-screw-propeller heptanuclear 3d-4f cluster complexes are ferromagnetic: one exhibits a large magnetocaloric effect while the other a magnetic relaxation behavior, depending on the lanthanoid ions used.

  20. Studying nanoparticles' 3D shape by aspect maps: Determination of the morphology of bacterial magnetic nanoparticles.

    PubMed

    Peddis, D; Muscas, G; Mathieu, R; Kumar, P Anil; Varvaro, G; Singh, G; Orue, I; Gil-Carton, D; Marcano, L; Muela, A; Fdez-Gubieda, M L

    2016-10-06

    Magnetic nanoparticles (MNPs) are widely investigated due to their potential use in various applications, ranging from electronics to biomedical devices. The magnetic properties of MNPs are strongly dependent on their size and shape (i.e., morphology), thus appropriate tools to investigate their morphology are fundamental to understand the physics of these systems. Recently a new approach to study nanoparticle morphology by Transmission Electron Microscopy (TEM) analysis has been proposed, introducing the so-called Aspect Maps (AMs). In this paper, a further evolution of the AM method is presented, allowing determination of the nanoparticles' 3D shape by TEM image. As a case study, this paper will focus on magnetite nanoparticles (Fe3O4), with a mean size of ∼45 nm extracted from Magnetospirillum gryphiswaldense magnetostatic bacteria (MTB). The proposed approach gives a complete description of the nanoparticles' morphology, allowing estimation of an average geometrical size and shape. In addition, preliminary investigation of the magnetic properties of MTB nanoparticles was performed, giving some insight into interparticle interactions and on the reversal mechanism of the magnetization.

  1. Surface strain-field determination of tympanic membrane using 3D-digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Hernandez-Montes, María del S.; Mendoza Santoyo, Fernando; Muñoz, Silvino; Perez, Carlos; de la Torre, Manuel; Flores, Mauricio; Alvarez, Luis

    2015-08-01

    In order to increase the understanding of soft tissues mechanical properties, 3D Digital Holographic Interferometry (3D-DHI) was used to quantify the strain-field on a cat tympanic membrane (TM) surface. The experiments were carried out applying a constant sound-stimuli pressure of 90 dB SPL (0.632 Pa) on the TM at 1.2 kHz. The technique allows the accurate acquisition of the micro-displacement data along the x, y and z directions, which is a must for a full characterization of the tissue mechanical behavior under load, and for the calculation of the strain-field in situ. The displacements repeatability in z direction shows a standard deviation of 0.062 μm at 95% confidence level. In order to realize the full 3D characterization correctly the contour of the TM surface was measured employing the optically non-contact two-illumination positions contouring method. The x, y and z displacements combined with the TM contour data allow the evaluation its strain-field by spatially differentiating the u(m,n), v(m,n), and w(m,n) deformation components. The accurate and correct determination of the TM strain-field leads to describing its elasticity, which is an important parameter needed to improve ear biomechanics studies, audition processes and TM mobility in both experimental measurements and theoretical analysis of ear functionality and its modeling.

  2. Photospheric magnetic fields

    NASA Technical Reports Server (NTRS)

    Howard, R.

    1972-01-01

    Knowledge on the nature of magnetic fields on the solar surface is reviewed. At least a large part of the magnetic flux in the solar surface is confined to small bundles of lines of force within which the field strength is of the order of 500 gauss. Magnetic fields are closely associated with all types of solar activity. Magnetic flux appears at the surface at the clearly defined birth or regeneration of activity of an active region. As the region ages, the magnetic flux migrates to form large-scale patterns and the polar fields. Some manifestations of the large-scale distribution are discussed.

  3. Inductively Driven, 3D Liner Compression of a Magnetized Plasma to Megabar Energy Densities

    SciTech Connect

    Slough, John

    2015-02-01

    modules. The additional energy and switching capability proposed will thus provide for optimal utilization of the liner energy. The following tasks were outlined for the three year effort: (1) Design and assemble the foil liner compression test structure and chamber including the compression bank and test foils [Year 1]. (2) Perform foil liner compression experiments and obtain performance data over a range on liner dimensions and bank parameters [Year 2]. (3) Carry out compression experiments of the FRC plasma to Megagauss fields and measure key fusion parameters [Year 3]. (4) Develop numerical codes and analyze experimental results, and determine the physics and scaling for future work [Year 1-3]. The principle task of the project was to design and assemble the foil liner FRC formation chamber, the full compression test structure and chamber including the compression bank. This task was completed successfully. The second task was to test foils in the test facility constructed in year one and characterize the performance obtained from liner compression. These experimental measurements were then compared with analytical predictions, and numerical code results. The liner testing was completed and compared with both the analytical results as well as the code work performed with the 3D structural dynamics package of ANSYS Metaphysics®. This code is capable of modeling the dynamic behavior of materials well into the non-linear regime (e.g. a bullet hit plate glass). The liner dynamic behavior was found to be remarkably close to that predicted by the 3D structural dynamics results. Incorporating a code that can also include the magnetics and plasma physics has also made significant progress at the UW. The remaining test bed construction and assembly task is was completed, and the FRC formation and merging experiments were carried out as planned. The liner compression of the FRC to Megagauss fields was not performed due to not obtaining a sufficiently long lived FRC during the

  4. Mapping 3D breast lesions from full-field digital mammograms using subject-specific finite element models

    NASA Astrophysics Data System (ADS)

    García, E.; Oliver, A.; Diaz, O.; Diez, Y.; Gubern-Mérida, A.; Martí, R.; Martí, J.

    2017-03-01

    Patient-specific finite element (FE) models of the breast have received increasing attention due to the potential capability of fusing images from different modalities. During the Magnetic Resonance Imaging (MRI) to X-ray mammography registration procedure, the FE model is compressed mimicking the mammographic acquisition. Subsequently, suspicious lesions in the MRI volume can be projected into the 2D mammographic space. However, most registration algorithms do not provide the reverse information, avoiding to obtain the 3D geometrical information from the lesions localized in the mammograms. In this work we introduce a fast method to localize the 3D position of the lesion within the MRI, using both cranio-caudal (CC) and medio-lateral oblique (MLO) mammographic projections, indexing the tetrahedral elements of the biomechanical model by means of an uniform grid. For each marked lesion in the Full-Field Digital Mammogram (FFDM), the X-ray path from source to the marker is calculated. Barycentric coordinates are computed in the tetrahedrons traversed by the ray. The list of elements and coordinates allows to localize two curves within the MRI and the closest point between both curves is taken as the 3D position of the lesion. The registration errors obtained in the mammographic space are 9.89 +/- 3.72 mm in CC- and 8.04 +/- 4.68 mm in MLO-projection and the error in the 3D MRI space is equal to 10.29 +/- 3.99 mm. Regarding the uniform grid, it is computed spending between 0.1 and 0.7 seconds. The average time spent to compute the 3D location of a lesion is about 8 ms.

  5. Total-Field Technique for 3-D Modeling of Short Period Teleseismic Waves

    NASA Astrophysics Data System (ADS)

    Monteiller, V.; Beller, S.; Operto, S.; Nissen-Meyer, T.; Tago Pacheco, J.; Virieux, J.

    2014-12-01

    The massive development of dense seismic arrays and the rapid increase in computing capacity allow today to consider application of full waveform inversion of teleseismic data for high-resolution lithospheric imaging. We present an hybrid numerical method that allows for the modellingof short period teleseismic waves in 3D lithospheric target with both the discontinuous Galerkin finite elements method and finite difference method, opening the possibility to perform waveform inversion of seismograms recorded by dense regional broadband arrays. However, despite the supercomputer ability, the forward-problem remains expensive at global scale for teleseismic configuration especially when 3D numerical methods are considered. In order to perform the forward problem in a reasonable amount of time, we reduce the computational domain in which full waveform modelling is performed. We define a 3D regional domain located below the seismological network that is embedded in a homogeneous background or axisymmetric model, in which the seismic wavefield can be computed efficiently. The background wavefield is used to compute the full wavefield in the 3D regional domain using the so-called total-field/scattered-field technique. This method relies on the decomposition of the wavefield into a background and a scattered wavefields. The computational domain is subdivided into three sub-domains: an outer domain formed by the perfectly-matched absorbing layers, an intermediate domain in which only the outgoing wavefield scattered by the lithospheric heterogeneities is computed, and the inner domain formed by the lithospheric target in which the full wavefield is computed. In this study, we shall present simulations in realistic lithospheric target when the axisymetric background wavefield is computed with the AxiSEM softwave and the 3D simulation in lithospheric target model is performed with the discontinuous Galerkin or finite difference method.

  6. Hybrid wide-field and scanning microscopy for high-speed 3D imaging.

    PubMed

    Duan, Yubo; Chen, Nanguang

    2015-11-15

    Wide-field optical microscopy is efficient and robust in biological imaging, but it lacks depth sectioning. In contrast, scanning microscopic techniques, such as confocal microscopy and multiphoton microscopy, have been successfully used for three-dimensional (3D) imaging with optical sectioning capability. However, these microscopic techniques are not very suitable for dynamic real-time imaging because they usually take a long time for temporal and spatial scanning. Here, a hybrid imaging technique combining wide-field microscopy and scanning microscopy is proposed to accelerate the image acquisition process while maintaining the 3D optical sectioning capability. The performance was demonstrated by proof-of-concept imaging experiments with fluorescent beads and zebrafish liver.

  7. Self-assembly of a 3d-5f trinuclear single-molecule magnet from a pentavalent uranyl complex.

    PubMed

    Chatelain, Lucile; Walsh, James P S; Pécaut, Jacques; Tuna, Floriana; Mazzanti, Marinella

    2014-12-01

    Mixed-metal uranium compounds are very attractive candidates in the design of single-molecule magnets (SMMs), but only one 3d-5f hetero-polymetallic SMM containing a uranium center is known. Herein, we report two trimeric heterodimetallic 3d-5f complexes self-assembled by cation-cation interactions between a uranyl(V) complex and a TPA-capped M(II)  complex (M=Mn (1), Cd (2); TPA=tris(2-pyridylmethyl)amine). The metal centers were strategically chosen to promote the formation of discrete molecules rather than extended chains. Compound 1, which contains an almost linear {MnOUOMn} core, exhibits SMM behavior with a relaxation barrier of 81±0.5 K-the highest reported for a mono-uranium system-arising from intramolecular Mn-U exchange interactions combined with the high Ising anisotropy of the uranyl(V) moiety. Compound 1 also exhibits an open magnetic hysteresis loop at temperatures less than 3 K, with a significant coercive field of 1.9 T at 1.8 K.

  8. 4f-3d interaction and magnetic anisotropy in ThMn12-type rare-earth transition-metal compounds

    NASA Astrophysics Data System (ADS)

    de Boer, F. R.; Zhao, Z. G.; Buschow, K. H. J.

    1996-05-01

    Rare-earth (R) transition-metal (T) compounds of the R(T,M)12-type with R=Y or one of the heavy-rare-earth elements, T=Fe or Co and M=Ti, V, Mo or Si, have been studied at 4.2 K in the Amsterdam High-Field Installation in magnetic fields up to 38 T and at temperatures between 4.2 and 1000 K in other magnetometers. The 4f-3d interaction is derived from magnetization measurements on single-crystalline particles that are free to rotate in the applied fields. The stabilizing element M is shown to have a pronounced influence on the 4f-3d interaction strength in these compounds. The large variation in Curie temperatures of the Y compounds and the different types of magnetic anisotropy found in the Y compounds demonstrate that the element M plays an important role in establishing these properties as well.

  9. Rigorous analysis of an electric-field-driven liquid crystal lens for 3D displays

    NASA Astrophysics Data System (ADS)

    Kim, Bong-Sik; Lee, Seung-Chul; Park, Woo-Sang

    2014-08-01

    We numerically analyzed the optical performance of an electric field driven liquid crystal (ELC) lens adopted for 3-dimensional liquid crystal displays (3D-LCDs) through rigorous ray tracing. For the calculation, we first obtain the director distribution profile of the liquid crystals by using the Erickson-Leslie motional equation; then, we calculate the transmission of light through the ELC lens by using the extended Jones matrix method. The simulation was carried out for a 9view 3D-LCD with a diagonal of 17.1 inches, where the ELC lens was slanted to achieve natural stereoscopic images. The results show that each view exists separately according to the viewing position at an optimum viewing distance of 80 cm. In addition, our simulation results provide a quantitative explanation for the ghost or blurred images between views observed from a 3D-LCD with an ELC lens. The numerical simulations are also shown to be in good agreement with the experimental results. The present simulation method is expected to provide optimum design conditions for obtaining natural 3D images by rigorously analyzing the optical functionalities of an ELC lens.

  10. Simultaneous 3D Strain and Flow Fields Measurement of a Model Artery under Unsteady Flows

    NASA Astrophysics Data System (ADS)

    Toloui, Mostafa; Sheng, Jian

    2011-11-01

    Fluid-Structure Interaction imposes challenges in both aero-elasticity and biomedical studies. A simultaneous solid deformation and fluid flow measurement technique based on digital in-line holographic particle tracking velocimetry (PTV) has been developed. It allows us to measure concurrently 3D strain field of a deforming structure and the unsteady flow near it. To facilitate the measurement, both wall and flow are seeded with tracer particles distinguished by size. The motion of these tracers provides the 3D deformation of the wall and the 3D velocity distribution of the flow separately. A fully index matched facility including transparent artery and NaI solution is constructed to enable observations near the wall or through the complex geometry. An arterial model with the inner diameter of 9.5 mm and the thickness of 0.9 mm is manufactured from the cross-linked transparent PDMS at the mixing ratio of 1:10 and doped with mono-dispersed 19 μm polystyrene particles. A cinematic holographic PTV system is used to trace the 3D particle motion in the model and flow simultaneously. Preliminary study is performed within a sample volume of 15 × 15 × 75 mm with the spatial resolution of 7.4 μm in lateral and 10 μm in depth. Uncertainty and accuracy analysis will be reported. NSF Grant No: CBET-0844647.

  11. Regional rigorous 3-D modelling of ground geoelectric field due to realistic geomagnetic disturbances. An approach and implementation.

    NASA Astrophysics Data System (ADS)

    Ivannikova, Elena; Kruglyakov, Mikhail; Kuvshinov, Alexey; Rastaetter, Lutz; Pulkkinen, Antti

    2017-04-01

    Strong eruptions at the Sun's surface produce large release of plasma, which with a high speed (solar wind) flows into space. Solar wind interaction with the Earth's magnetosphere and the ionosphere leads to a continuous disturbance of the geomagnetic field. This fluctuating geomagnetic field induces a ground geoelectric field that in turn generates geomagnetically induced currents (GICs) in technological systems, such as power grids and pipelines. It is well known that GICs are one of the most dangerous factors affecting the operation of the above systems. Thus, an accurate modelling of the spatio-temporal evolution of the geoelectric field during abnormal (storm-time) geomagnetic activity is a key consideration in estimating the hazard to technological systems from space weather. We present a numerical tool for regional modelling of the space weather influence on ground geoelectric field. The tool exploits realistic regional and global three-dimensional (3-D) models of Earth's electrical conductivity, and realistic global models of the spatio-temporal evolution of magnetospheric and ionospheric current systems responsible for geomagnetic disturbances. The tool involves four steps. First, we compute the spatio-temporal distribution of external magnetic field on a regular grid at the surface of the Earth using a magnetohydrodynamic model of the magnetosphere coupled to an electrostatic model of the ionosphere. Second, from the external magnetic field we compute the global source in the form of equivalent currents flowing in a thin shell above the Earth. Third, for a given global source and a given global 3-D conductivity model of the Earth we compute ground geoelectric field globally at a coarse grid (using spherical geometry). Finally, for a given source and a given regional 3-D conductivity model(s) of the Earth we compute geoelectric field regionally (using Cartesian geometry) at a dense grid utilizing the results from the global modelling. Both global and

  12. 3D magnetic resonance imaging as a non-invasive tool for investigating water-filled karst formations

    NASA Astrophysics Data System (ADS)

    Legchenko, A.; Ezersky, M.; Boucher, M.; Chevalier, A.; Vouillamoz, J.-M.

    2012-04-01

    Magnetic Resonance Sounding (MRS) is a geophysical technique developed for groundwater exploration. MRS can be used for reliable identification of karst aquifers because of the relaxation time of the magnetic resonance signal (T1) is longer for bulk water in karst caverns and channels (about 2 s) than for water in porous rock (few tens of ms). MRS is sensitive primary to groundwater volume but electrically conductive layers modify electromagnetic fields in the subsurface and thus may have an effect on MRS performance. Generally, the study of a karst requires a 3D field set-up and we developed a measuring procedure and interpretation software that makes it possible to image heterogeneous water-bearing geological formations down to about 80 m (3D-SNMR method). Numerical modeling results show that limited resolution of the method allows only identification of large karst formations. For example detectable karst should be larger than a few hundred cubic meters when karst is located close to the surface and a few thousand cubic meters when it is located at 60 m. Time Domain Electromagnetic method (TDEM) is known as an efficient tool for investigating electrical conductivity of rocks. TDEM results allow more accurate computing of the EM field in the subsurface and thus contribute for improving accuracy of MRS results. TDEM and 3D-SNMR methods were applied jointly in the Dead Sea coast of Israel (Nahal Hever South). The subsurface in this area is heterogeneous and composed of intercalated sand and clay layers over a salt rock, which is partly karstified. Groundwater is very saline, with a chloride concentration of 100-225 g/l thus rendering the resistivity of geological formations less than 1 ohm-m. We have shown numerically that under Dead Sea coast conditions, 3D-SNMR is able to detect and to locate the target within an error of a few tens of meters. In the investigated area (500×500 m2) our results reveal a very heterogeneous shallow aquifer that could be divided into

  13. Full-field strain measurements on turbomachinery components using 3D SLDV technology

    NASA Astrophysics Data System (ADS)

    Maguire, Martyn; Sever, Ibrahim

    2016-06-01

    This paper focuses on measurements of 3D Operating Deflection Shapes (ODSs), and subsequently, construction of full-field surface strain maps of a number of turbomachinery components. For this purpose a 3D Scanning Laser Doppler Vibrometer (SLDV) is used. The ODS measurements are performed for a large number of modes and results obtained are compared with the 1-D shapes that are most commonly measured. It is demonstrated that the 3D measurements are a significant improvement over the 1-D case in terms of independent amount of extra information they provide. This is confirmed through comparisons with FE results. Special tests are carried out to recover the full-field strain on scanned faces of the components used. Visual comparison of these measurements with FE counterparts reveal that strain maps can be successfully measured, not only for low frequency modes but also for highly complex high frequency ones. These maps are measured with different levels of input force to assess the linearity of strain results to varying response amplitudes. Lessons learnt and observations made are summarised in concluding remarks and the scope of future work to take this study into the production environment is discussed. This study constitutes a unique comprehensive investigation into full-field strain measurements using real application hardware and a large frequency range.

  14. The research of 3D small-field imaging system based on fringe projection technique

    NASA Astrophysics Data System (ADS)

    Yu, Yanqin; Huang, Shujun; Zhang, Zonghua; Gao, Feng; Jiang, Xiangqian

    2014-12-01

    This paper presents a 3D small-field imaging system by using the color fringe projection technique to measure the small objects having large slopes and/or discontinuous surface. A stereo microscope is used to generate a small-field projecting field and to capture the deformed fringe patterns on the measured small objects, respectively. Three fringe sets having the optimum fringe numbers are coded into one major color channel to generate color fringe patterns having the maximum fringe contrast of the captured fringe images. Through one channel of the stereo microscope, a DLP (Digital Light Processing) projector projects these generated color fringe pattern images onto the measured objects surface. From another channel, the fringe patterns are deformed with regard to the object surface and captured by a color CCD camera. The absolute phase of each pixel can be calculated from the captured fringe patterns by using the optimum three-fringe numbers selection method. Experimental results on measuring 3D shape of small objects show the accuracy and availability of the developed 3D imaging system.

  15. Commissioning a small-field biological irradiator using point, 2D, and 3D dosimetry techniques

    SciTech Connect

    Newton, Joseph; Oldham, Mark; Thomas, Andrew; Li Yifan; Adamovics, John; Kirsch, David G.; Das, Shiva

    2011-12-15

    Purpose: To commission a small-field biological irradiator, the XRad225Cx from Precision x-Ray, Inc., for research use. The system produces a 225 kVp x-ray beam and is equipped with collimating cones that produce both square and circular radiation fields ranging in size from 1 to 40 mm. This work incorporates point, 2D, and 3D measurements to determine output factors (OF), percent-depth-dose (PDD) and dose profiles at multiple depths. Methods: Three independent dosimetry systems were used: ion-chambers (a farmer chamber and a micro-ionisation chamber), 2D EBT2 radiochromic film, and a novel 3D dosimetry system (DLOS/PRESAGE registered ). Reference point dose rates and output factors were determined from in-air ionization chamber measurements for fields down to {approx}13 mm using the formalism of TG61. PDD, profiles, and output factors at three separate depths (0, 0.5, and 2 cm), were determined for all field sizes from EBT2 film measurements in solid water. Several film PDD curves required a scaling correction, reflecting the challenge of accurate film alignment in very small fields. PDDs, profiles, and output factors were also determined with the 3D DLOS/PRESAGE registered system which generated isotropic 0.2 mm data, in scan times of 20 min. Results: Surface output factors determined by ion-chamber were observed to gradually drop by {approx}9% when the field size was reduced from 40 to 13 mm. More dramatic drops were observed for the smallest fields as determined by EBT{approx}18% and {approx}42% for the 2.5 mm and 1 mm fields, respectively. PRESAGE registered and film output factors agreed well for fields <20 mm (where 3D data were available) with mean deviation of 2.2% (range 1%-4%). PDD values at 2 cm depth varied from {approx}72% for the 40 mm field, down to {approx}55% for the 1 mm field. EBT and PRESAGE registered PDDs agreed within {approx}3% in the typical therapy region (1-4 cm). At deeper depths the EBT curves were slightly steeper (2.5% at 5 cm

  16. Qualitative and quantitative assessment of wrist MRI at 3.0T: comparison between isotropic 3D turbo spin echo and isotropic 3D fast field echo and 2D turbo spin echo.

    PubMed

    Jung, Jee Young; Yoon, Young Cheol; Jung, Jin Young; Choe, Bong-Keun

    2013-04-01

    Isotropic three-dimensional (3D) magnetic resonance imaging (MRI) has been applied to various joints. However, comparison for image quality between isotropic 3D MRI and two-dimensional (2D) turbo spin echo (TSE) sequence of the wrist at a 3T MR system has not been investigated. To compare the image quality of isotropic 3D MRI including TSE intermediate-weighted (VISTA) sequence and fast field echo (FFE) sequence with 2D TSE intermediate-weighted sequence of the wrist joint at 3.0 T. MRI was performed in 10 wrists of 10 healthy volunteers with isotropic 3D sequences (VISTA and FFE) and 2D TSE intermediate-weighted sequences at 3.0 T. The signal-to-noise ratio (SNR) was obtained by imaging phantom and noise-only image. Contrast ratios (CRs) were calculated between fluid and cartilage, triangular fibrocartilage complex (TFCC), and the scapholunate ligament. Two radiologists independently assessed the visibility of TFCC, carpal ligaments, cartilage, tendons and nerves with a four-point grading scale. Statistical analysis to compare CRs (one way ANOVA with a Tukey test) and grades of visibility (Kruskal-Wallis test) between three sequences and those for inter-observer agreement (kappa analysis) were performed. The SNR of 2D TSE (46.26) was higher than those of VISTA (23.34) and 3D FFE (19.41). CRs were superior in 2D TSE than VISTA (P = 0.02) for fluid-cartilage and in 2D TSE than 3D FFE (P < 0.01) for fluid-TFCC. The visibility was best in 2D TSE (P < 0.01) for TFCC and in VISTA (P = 0.01) for scapholunate ligament. The visibility was better in 2D TSE and 3D FFE (P = 0.04) for cartilage and in VISTA than 3D FFE (P < 0.01) for TFCC. The inter-observer agreement for the visibility of anatomic structures was moderate or substantial. Image quality of 2D TSE was superior to isotropic 3D MR imaging for cartilage, and TFCC. 3D FFE has better visibility for cartilage than VISTA and VISTA has superior visibility for TFCC to 3D FFE and the visibility for scapholunate ligament

  17. 3-D joint inversion of the magnetotelluric phase tensor and vertical magnetic transfer functions

    NASA Astrophysics Data System (ADS)

    Tietze, Kristina; Ritter, Oliver; Egbert, Gary D.

    2015-11-01

    With advancing computational resources, 3-D inversion techniques have become feasible in recent years and are now a more widely used tool for magnetotelluric (MT) data interpretation. Galvanic distortion caused by small-scale near-surface inhomogeneities remains an obstacle for 3-D MT inversion which so far has experienced little attention. If not considered properly, the effect on 3-D inversion can be immense and result in erroneous subsurface models and interpretations. To tackle the problem we implemented inversion of the distortion-free phase tensor into the ModEM inversion package. The dimensionless phase tensor components describe only variations of the conductivity structure. When inverting these data, particular care has to be taken of the conductivity structure in the a priori model, which provides the reference frame when transferring the information from phase tensors into absolute conductivity values. Our results obtained with synthetic data show that phase tensor inversion can recover the regional conductivity structure in presence of galvanic distortion if the a priori model provides a reasonable assumption for the regional resistivity average. Joint inversion of phase tensor data and vertical magnetic transfer functions improves recovery of the absolute resistivity structure and is less dependent on the prior model. We also used phase tensor inversion for a data set of more than 250 MT sites from the central San Andreas fault, California, where a number of sites showed significant galvanic distortion. We find the regional structure of the phase tensor inversion results compatible with previously obtained models from impedance inversion. In the vicinity of distorted sites, phase tensor inversion models exhibit more homogeneous/smoother conductivity structures.

  18. 3D modeling inversion calculation of magnetic data using iterative reweighted least squares at the Lau basin, Southwest Pacific

    NASA Astrophysics Data System (ADS)

    Choi, S.; Kim, C.; Kim, H. R.; Park, C.; Park, H. Y.

    2015-12-01

    We performed the marine magnetic and the bathymetry survey in the Lau basin for finding the submarine hydrothermal deposits in October 2009. We acquired magnetic and bathymetry datasets by using Overhouser Proton Magnetometer SeaSPY(Marine Magnetics Co.) and Multi-Beam Echo Sounder EM120(Kongsberg Co.). We conducted the data processing to obtain detailed seabed topography, magnetic anomaly and reduction to the pole(RTP). The Lau basin is one of the youngest back-arc basins in the Southwest Pacific. This region was a lot of hydrothermal activities and hydrothermal deposits. In particular, Tofua Arc(TA) in the Lau basin consists of various and complex stratovolcanos(from Massoth et al., 2007).), We calculated the magnetic susceptibility distribution of the TA19-1 seamount(longitude:176°23.5'W, latitude: 22°42.5'W)area using the RTP data by 3-D magnetic inversion from Jung's previous study(2013). Based on 2D 'compact gravity inversion' by Last & Kubik(1983), we expend it to the 3D algorithm using iterative reweighted least squares method with some weight matrices. The used weight matrices are two types: 1) the minimum gradient support(MGS) that controls the spatial distribution of the solution from Porniaguine and Zhdanov(1999); 2) the depth weight that are used according to the shape of subsurface structures. From the modeling, we derived the appropriate scale factor for the use of depth weight and setting magnetic susceptibility. Furthermore, we have to enter a very small error value to control the computation of the singular point of the inversion model that was able to be easily calculated for modeling. In addition, we applied separately weighted value for the correct shape and depth of the magnetic source. We selected the best results model by change to converge of RMS. Compared between the final modeled result and RTP values in this study, they are generally similar to the each other. But the input values and the modeled values have slightly little difference

  19. A thermoresponsive and magnetic colloid for 3D cell expansion and reconfiguration.

    PubMed

    Saeed, Aram; Francini, Nora; White, Lisa; Dixon, James; Gould, Toby; Rashidi, Hassan; Al Ghanami, Racha Cheikh; Hruschka, Veronika; Redl, Heinz; Saunders, Brian R; Alexander, Cameron; Shakesheff, Kevin M

    2015-01-27

    A dual thermoresponsive and magnetic colloidal gel matrix is described for enhanced stem-cell culture. The combined properties of the material allow enzyme-free passaging and expansion of mesenchymal stem cells, as well as isolation of cells postculture by the simple process of lowering the temperature and applying an external magnetic field. The colloidal gel can be reconfigured with thermal and magnetic stimuli to allow patterning of cells in discrete zones and to control movement of cells within the porous matrix during culture.

  20. 3D-HST WFC3-SELECTED PHOTOMETRIC CATALOGS IN THE FIVE CANDELS/3D-HST FIELDS: PHOTOMETRY, PHOTOMETRIC REDSHIFTS, AND STELLAR MASSES

    SciTech Connect

    Skelton, Rosalind E.; Whitaker, Katherine E.; Momcheva, Ivelina G.; Van Dokkum, Pieter G.; Bezanson, Rachel; Leja, Joel; Nelson, Erica J.; Oesch, Pascal; Brammer, Gabriel B.; Labbé, Ivo; Franx, Marijn; Fumagalli, Mattia; Van der Wel, Arjen; Da Cunha, Elisabete; Maseda, Michael V.; Förster Schreiber, Natascha; Kriek, Mariska; Lundgren, Britt F.; Magee, Daniel; Marchesini, Danilo; and others

    2014-10-01

    The 3D-HST and CANDELS programs have provided WFC3 and ACS spectroscopy and photometry over ≈900 arcmin{sup 2} in five fields: AEGIS, COSMOS, GOODS-North, GOODS-South, and the UKIDSS UDS field. All these fields have a wealth of publicly available imaging data sets in addition to the Hubble Space Telescope (HST) data, which makes it possible to construct the spectral energy distributions (SEDs) of objects over a wide wavelength range. In this paper we describe a photometric analysis of the CANDELS and 3D-HST HST imaging and the ancillary imaging data at wavelengths 0.3-8 μm. Objects were selected in the WFC3 near-IR bands, and their SEDs were determined by carefully taking the effects of the point-spread function in each observation into account. A total of 147 distinct imaging data sets were used in the analysis. The photometry is made available in the form of six catalogs: one for each field, as well as a master catalog containing all objects in the entire survey. We also provide derived data products: photometric redshifts, determined with the EAZY code, and stellar population parameters determined with the FAST code. We make all the imaging data that were used in the analysis available, including our reductions of the WFC3 imaging in all five fields. 3D-HST is a spectroscopic survey with the WFC3 and ACS grisms, and the photometric catalogs presented here constitute a necessary first step in the analysis of these grism data. All the data presented in this paper are available through the 3D-HST Web site (http://3dhst.research.yale.edu)

  1. 3D Equilibrium Reconstruction with Improved Magnetic Diagnostics on the Compact Toroidal Hybrid

    NASA Astrophysics Data System (ADS)

    Ma, Xinxing; Hanson, James D.; Hartwell, Gregory J.; Knowlton, Stephen F.; Maurer, David A.

    2013-10-01

    Equilibrium reconstructions using the three-dimensional V3FIT code [ 1 ] have been performed for low density (low β) current carrying plasmas on the Compact Toroidal Hybrid (CTH), a torsatron in which the magnetic configuration can be strongly modified by an ohmically-driven plasma current. These reconstructions use 50 external magnetic diagnostic measurements, including segmented and full Rogowski coils, saddle loops, poloidal and radial magnetic pickup coils. Time dependent 3D reconstructions document the evolution of the plasma cross section and current profile, with calculated value of βθ much less than the plasma internal inductance, li. Reconstructions typically show the plasma to move outward in major radius and become less elongated in poloidal cross section with increasing plasma current. In plasmas with low vacuum transform (ιvac ~ 0 . 04), the plasma current profile peaks with li above 0 . 84 when the total transform is 1 / 2 , which typically leads disruption. With values of ιvac >= 0 . 1 , li remains low (~ 0 . 7), and the discharges no longer disrupt. This work is supported by the USDoE under grant DE-FG02-00ER54610.

  2. 3D Equilibrium Reconstruction with Improved Magnetic Diagnostics on the Compact Toroidal Hybrid

    NASA Astrophysics Data System (ADS)

    Ma, X.; Hanson, J. D.; Hartwell, G. J.; Knowlton, S. F.; Maurer, D. A.

    2012-10-01

    Three-dimensional reconstruction of plasma equilibria is important for understanding the physics of both intrinsic 3D confinement in stellarators as well as axisymmetric plasmas in tokamaks. Equilibrium reconstructions using the V3FIT code [1] will be presented for current carrying plasma on the Compact Toroidal Hybrid (CTH) torsatron experiment. The CTH is a heliotron-type device, in which the magnetic configuration can be strongly modified by an ohmically-driven plasma current. These reconstructions use sets of recently upgraded magnetic diagnostics (44 channels), including segment and full Rogowski coils and new saddle coils. Reconstruction results with these new diagnostics, especially the time evolution of the reconstructed current density profile for a series of plasma conditions, will be presented and compared to previous ones using a smaller set of input magnetic signals. New modelling of the effects of eddy currents in the helical coil frame and vacuum vessel will also be discussed.[4pt] [1] J. D. Hanson, S. P. Hirshman, S. F. Knowlton, L. L. Lao, E. A. Lazarus, J. M. Shields, Nucl, Fusion49, 075031 (2009)

  3. Microscopic magnetic nature of K2NiF4-type 3d transition metal oxides

    NASA Astrophysics Data System (ADS)

    Sugiyama, J.; Nozaki, H.; Umegaki, I.; Higemoto, W.; Ansaldo, E. J.; Brewer, J. H.; Sakurai, H.; Kao, T.-H.; Yang, H.-D.; Månsson, M.

    2014-12-01

    In order to elucidate the magnetic nature of K2NiF4-type 3d transition metal oxides, we have measured μ+SR spectra for Sr2VO4, LaSrVO4, and Sr2CrO4 using powder samples. ZF- and wTF-μ+SR measurements propose that Sr2VO4 enters into the static antiferromagnetic (AF) order phase below 8 K. In addition, TF-μ+SR measurements evidence that the transition at 105 K is not magnetic but structural and/or electronic in origin. For LaSrVO4, static long-range order has not been observed down to 20 K, while, as T decreases from 145 K, wTF asymmetry starts to decrease below 60 K, suggesting the appearance and evolution of localized magnetic moments below 60 K. For Sr2CrO4, by contrast, both ZF- and wTF-μ+SR have confirmed the presence of antiferromagnetic order below 117 K, as predicted in the χ(T) curve.

  4. Denoising of 3D magnetic resonance images by using higher-order singular value decomposition.

    PubMed

    Zhang, Xinyuan; Xu, Zhongbiao; Jia, Nan; Yang, Wei; Feng, Qianjin; Chen, Wufan; Feng, Yanqiu

    2015-01-01

    The denoising of magnetic resonance (MR) images is important to improve the inspection quality and reliability of quantitative image analysis. Nonlocal filters by exploiting similarity and/or sparseness among patches or cubes achieve excellent performance in denoising MR images. Recently, higher-order singular value decomposition (HOSVD) has been demonstrated to be a simple and effective method for exploiting redundancy in the 3D stack of similar patches during denoising 2D natural image. This work aims to investigate the application and improvement of HOSVD to denoising MR volume data. The wiener-augmented HOSVD method achieves comparable performance to that of BM4D. For further improvement, we propose to augment the standard HOSVD stage by a second recursive stage, which is a repeated HOSVD filtering of the weighted summation of the residual and denoised image in the first stage. The appropriate weights have been investigated by experiments with different image types and noise levels. Experimental results over synthetic and real 3D MR data demonstrate that the proposed method outperforms current state-of-the-art denoising methods.

  5. Waves in 3D Magnetic Nulls: some preliminary results in the PPT device and in situ Measurements in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Xiao, Chijie; Yang, Xiaoyi; Chen, Yangao; Chen, Yihang; Wang, Xiaogang

    2015-11-01

    Plasma waves and the particle dynamics in the magnetic null are very important to understand the three-dimensional (3D) magnetic reconnection process. A small plasma device, which named PPT device (abbreviated form of PKU Plasma Test device), has setup recently to study the waves and particle dynamics around a magnetic null. Here we will report the first preliminary results, such as the waves along the spines and the fan surfaces, as well as the particle dynamics around it. Furthermore, some wave modes around 3D nulls detected by Cluster mission in the magnetosphere will also be reported to compare. These preliminary results will give more clues to understanding of the magnetic nulls and 3D magnetic reconnection.

  6. Locating magnetic reconnection x-lines in 3D PIC simulations

    NASA Astrophysics Data System (ADS)

    Olson, D. K.; Dorelli, J.; Daughton, W. S.; Karimabadi, H.

    2013-12-01

    In a three-dimensional PIC simulation of turbulent magnetic reconnection, a reconnection 'X-line' can be identified as a separator in the magnetic topology. From this x-line, it is possible to compute the reconnection rate by evaluating the line integral of the electric field along the separator. This technique is used in a reconnection simulation of a symmetric Harris sheet driven by inflow at the upstream boundaries with a strong guide field (such that the magnetic field is non-vanishing everywhere and there are no magnetic nulls). The results of this analysis are compared to the General Magnetic Reconnection theory (GMR) [Hesse and Schindler, 1998], showing that in this symmetric case GMR agrees with our topological approach to finding the location of the x-line. The parallel electric field is non-trivial along the entire length of the x-line, however, suggesting that the reconnection diffusion region cannot be identified by local measures of the breakdown of ideal MHD alone. We discuss the implications of these results for NASA's upcoming Magnetospheric Multiscale mission.

  7. Effects of 3-D thermal radiation on the development of a shallow cumulus cloud field

    NASA Astrophysics Data System (ADS)

    Klinger, Carolin; Mayer, Bernhard; Jakub, Fabian; Zinner, Tobias; Park, Seung-Bu; Gentine, Pierre

    2017-04-01

    We investigate the effects of thermal radiation on cloud development in large-eddy simulations (LESs) with the UCLA-LES model. We investigate single convective clouds (driven by a warm bubble) at 50 m horizontal resolution and a large cumulus cloud field at 50 and 100 m horizontal resolutions. We compare the newly developed 3-D Neighboring Column Approximation with the independent column approximation and a simulation without radiation and their respective impact on clouds. Thermal radiation causes strong local cooling at cloud tops accompanied by a modest warming at the cloud bottom and, in the case of the 3-D scheme, also cloud side cooling. 3-D thermal radiation causes systematically larger cooling when averaged over the model domain. In order to investigate the effects of local cooling on the clouds and to separate these local effects from a systematically larger cooling effect in the modeling domain, we apply the radiative transfer solutions in different ways. The direct effect of heating and cooling at the clouds is applied (local thermal radiation) in a first simulation. Furthermore, a horizontal average of the 1-D and 3-D radiation in each layer is used to study the effect of local cloud radiation as opposed to the domain-averaged effect. These averaged radiation simulations exhibit a cooling profile with stronger cooling in the cloudy layers. In a final setup, we replace the radiation simulation by a uniform cooling of 2.6 K day-1. To focus on the radiation effects themselves and to avoid possible feedbacks, we fixed surface fluxes of latent and sensible heat and omitted the formation of rain in our simulations. Local thermal radiation changes cloud circulation in the single cloud simulations, as well as in the shallow cumulus cloud field, by causing stronger updrafts and stronger subsiding shells. In our cumulus cloud field simulation, we find that local radiation enhances the circulation compared to the averaged radiation applications. In addition, we

  8. Anatomical delineation of congenital heart disease using 3D magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Adams Bornemeier, Renee; Fellows, Kenneth E.; Fogel, Mark A.; Weinberg, Paul M.

    1994-05-01

    Anatomic delineation of the heart and great vessels is a necessity when managing children with congenital heart disease. Spatial orientation of the vessels and chambers in the heart and the heart itself may be quite abnormal. Though magnetic resonance imaging provides a noninvasive means for determining the anatomy, the intricate interrelationships between many structures are difficult to conceptualize from a 2-D format. Taking the 2-D images and using a volumetric analysis package allows for a 3-D replica of the heart to be created. This model can then be used to view the anatomy and spatial arrangement of the cardiac structures. This information may be utilized by the physicians to assist in the clinical management of these children.

  9. Blood velocity assessment using 3D bright-blood time-resolved magnetic resonance angiography.

    PubMed

    Miraux, Sylvain; Franconi, Jean-Michel; Thiaudière, Eric

    2006-09-01

    Blood velocity is a functional parameter that is not easily assessed noninvasively, especially in small animals. A new noninvasive method that uses magnetic resonance angiography (MRA) to measure blood flows is proposed. This method is based on the time-of-flight (TOF) phenomenon. By initially suppressing the signal from the stationary spins in the area of interest, it is possible to sequentially visualize only the signal from the moving spins entering a given volume. With this method, 3D cine images of the blood flow can be generated by positive contrast, with unparalleled spatial (<200 microm) and temporal resolutions (<10 ms/image). As a result, it is possible to measure flow in sinuous paths. The present method was applied in vivo to measure the blood velocity in mouse carotid arteries. Because of its robustness and simplicity of implementation, this method has numerous potential applications for fundamental studies in small animal models. Copyright (c) 2006 Wiley-Liss, Inc.

  10. Magnetic Fields in Stars

    NASA Astrophysics Data System (ADS)

    Landstreet, J.; Murdin, P.

    2000-11-01

    Magnetism—the force that deflects the needle of a compass—and magnetic fields have been found in some hundreds of stars during the past 50 yr. Magnetic fields have been detected in T Tauri stars and other pre-main-sequence stars, several types of main sequence stars, white dwarfs and neutron stars. We now know a number of methods by which such magnetic fields may be detected, we are in the proces...

  11. Organic magnetic field sensor

    DOEpatents

    McCamey, Dane; Boehme, Christoph

    2017-01-24

    An organic, spin-dependent magnetic field sensor (10) includes an active stack (12) having an organic material with a spin-dependence. The sensor (10) also includes a back electrical contact (14) electrically coupled to a back of the active stack (12) and a front electrical contact (16) electrically coupled to a front of the active stack (12). A magnetic field generator (18) is oriented so as to provide an oscillating magnetic field which penetrates the active stack (12).

  12. The rise of 3-d single-ion magnets in molecular magnetism: towards materials from molecules?

    PubMed Central

    Frost, Jamie M.; Harriman, Katie L. M.

    2016-01-01

    Single-molecule magnets (SMMs) that contain one spin centre (so-called single-ion magnets) theoretically represent the smallest possible unit for spin-based electronic devices. The realisation of this and related technologies, depends on first being able to design systems with sufficiently large energy barriers to magnetisation reversal, U eff, and secondly, on being able to organise these molecules into addressable arrays. In recent years, significant progress has been made towards the former goal – principally as a result of efforts which have been directed towards studying complexes based on highly anisotropic lanthanide ions, such as Tb(iii) and Dy(iii). Since 2013 however, and the remarkable report by Long and co-workers of a linear Fe(i) system exhibiting U eff = 325 K, single-ion systems of transition metals have undergone something of a renaissance in the literature. Not only do they have important lessons to teach us about anisotropy and relaxation dynamics in the quest to enhance U eff, the ability to create strongly coupled spin systems potentially offers access to a whole of host of 1, 2 and 3-dimensional materials with interesting structural and physical properties. This perspective summarises recent progress in this rapidly expanding sub-genre of molecular magnetism from the viewpoint of the synthetic chemist, with a particular focus on the lessons that have so far been learned from single-ion magnets of the d-block, and, the future research directions which we feel are likely to emerge in the coming years. PMID:28660017

  13. 3D Scanning Cloud Radar Observations at Azores during the ARM AMF field campaign: Reconstruction and study of 3D cloud structures and properties

    NASA Astrophysics Data System (ADS)

    Bowley, K.; Jo, I.; Tatarevic, A.; Kollias, P.

    2010-12-01

    The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) has been operating at Graciosa Island (Azores) since May 2009. This 21-month field campaign focuses on the study of marine stratus clouds. The ARM/AMF instrumentation and location provides a unique opportunity to observe the cloud properties of marine stratocumulus utilizing a variety of active and passive remote sensors. In addition to the standard profiling instrumentation, the first scanning W-band (94-GHz) ARM Cloud Radar (SWACR) was deployed for a short two-month period (October-November 2009). Several scan strategies were tested during the SWACR deployment. The scan strategies were designed specifically to provide the ability to reconstruct the 3D cloud structure. The raw radar observations are quality controlled with the identification of radar volumes with significant detections, water vapor attenuation and unfolding of the radar Doppler velocity. The observations are also transformed from the original radar coordinate system (spherical) to a Cartesian coordinate system using an adaptive gridding algorithm. The 3D gridding of the radar observables, along with spatial data analysis, allow us to evaluate important issues, specifically spatial variability of cloud and drizzle structures. Column profiles of SWACR observables are used in combination with Liquid Water Path measurements from the collocated Microwave Radiometer (MWR) to develop new relationships to compute Liquid Water Content (LWC). The best possible estimate of the 3D LWC structure is reconstructed by assessing both our relationship and other known relationships between radar reflectivity and LWC. This is required in order to use the 3D cloud observations for radiative transfer modeling. Additional drizzle-identification techniques are also being developed to allow the isolation of 3D cloud-only or liquid-only fields. These types of variables have a key impact on the understanding of the radiative budget

  14. Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

    SciTech Connect

    Li, Yanzhou; Luo, Jie; Zhang, Yanting; Zhao, Junwei; Chen, Lijuan; Ma, Pengtao; Niu, Jingyang

    2013-09-15

    An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na{sub 2}[Cu(dap){sub 2}]{sub 2}[Cu(dap){sub 2}] ([Cu{sub 6}(H{sub 2}O){sub 2}(dap){sub 2}][B-α-GeW{sub 9}O{sub 34}]{sub 2})·4H{sub 2}O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6{sub 4}·4·4·4·4·6{sub 4}·4·4·4·6{sub 4}·4·4·4 and the short vertex (Schläfli) symbol of 4{sup 12}6{sup 3}. Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu{sup II} cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W{sup VI}-based wave. - Graphical abstract: A hexa-Cu{sup II} sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide.

  15. Characterization of 3D geometric distortion of magnetic resonance imaging scanners commissioned for radiation therapy planning.

    PubMed

    Torfeh, Tarraf; Hammoud, Rabih; Perkins, Gregory; McGarry, Maeve; Aouadi, Souha; Celik, Azim; Hwang, Ken-Pin; Stancanello, Joseph; Petric, Primoz; Al-Hammadi, Noora

    2016-06-01

    To develop a method for the assessment and characterization of 3D geometric distortion as part of routine quality assurance for MRI scanners commissioned for Radiation Therapy planning. In this study, the in-plane and through-plane geometric distortions on a 1.5T GE MRI-SIM unit are characterized and the 2D and 3D correction algorithms provided by the vendor are evaluated. We used a phantom developed by GE Healthcare that covers a large field of view of 500mm, and consists of layers of foam embedded with a matrix of ellipsoidal markers. An in-house Java-based software module was developed to automatically assess the geometric distortion by calculating the center of each marker using the center of mass method, correcting of gross rotation errors and comparing the corrected positions with a CT gold standard data set. Spatial accuracy of typical pulse sequences used in RT planning was assessed (2D T1/T2 FSE, 3D CUBE, T1 SPGR) using the software. The accuracy of vendor specific geometric distortion correction (GDC) algorithms was quantified by measuring distortions before and after the application of the 2D and 3D correction algorithms. Our algorithm was able to accurately calculate geometric distortion with sub-pixel precision. For all typical MR sequences used in Radiotherapy, the vendor's GDC was able to substantially reduce the distortions. Our results showed also that the impact of the acquisition produced a maximum variation of 0.2mm over a radial distance of 200mm. It has been shown that while the 2D correction algorithm remarkably reduces the in-plane geometric distortion, 3D geometric distortion further reduced the geometric distortion by correcting both in-plane and through-plane distortions in all acquisitions. The presented methods represent a valuable tool for routine quality assurance of MR applications that require stringent spatial accuracy assessment such as radiotherapy. The phantom used in this study provides three dimensional arrays of control

  16. 3D magnetic interactions of stars with their close-in planets

    NASA Astrophysics Data System (ADS)

    Strugarek, Antoine; Brun, Allan Sacha; Matt, Sean; Réville, Victor

    2015-08-01

    Close-in planets generally orbit in a sub-alfv ´enic stellar wind, where the perturbations they excite in the corona are able to travel upwind to the stellar surface and potentially induce observable phenomena. The effective connection between the planet and its host takes the form of two Aflv ´en wings. Depending on the topology of the planetary and stellar magnetic fields, the rotation profile of the corona, and the orbital parameters, it is possible that none, one, or the two Aflv ´en wings connect together the star and the planet.We explore the formation and sustainment of Alfv ´en wings in global three dimensional simulations under the magneto-hydrodynamic formalism with the PLUTO code. We model the stellar wind of a typical cool star in which a close-in orbiting planet is introduced as a boundary condition. By varying the magnetic topologies of the planetary and stellar magnetic fields, we explore the variety of Alfv ´en wings that can develop and quantify the Poynting flux flowing through those wings. We thus provide estimates of the amount of magnetic energy these magnetic interactions can channel to the lower corona. We also quantify the phase and latitude offsets that can be expected between the planetary subpoint on the stellar surface and the actual location where energy is deposited. We summarize the typical situations (in terms of magnetic topology, stellar type, and orbital parameters) where the star-planet magnetic interaction could trigger observable flares. We conclude by extending our results to the cases of more complex, non-axisymmetric topologies of the observed magnetic fields for a few particular stars.

  17. RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations.

    PubMed

    Pasipoularides, Ares D; Shu, Ming; Womack, Michael S; Shah, Ashish; Von Ramm, Olaf; Glower, Donald D

    2003-01-01

    We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent of the digital imaging modality used. It comprises three parts. First, a semiautomated segmentation aided by intraluminal contrast medium locates the RV endocardial surface. Second, a geometric scheme for dynamic RV chamber reconstruction applies a time interpolation procedure to the RT3D data to quantify wall geometry and motion at 400 Hz. A volumetric prism method validated the dynamic geometric reconstruction against simultaneous sonomicrometric canine measurements. Finally, the RV endocardial border motion information is used for mesh generation on a computational fluid dynamics solver to simulate development of the early RV diastolic inflow field. Boundary conditions (tessellated endocardial surface nodal velocities) for the solver are directly derived from the endocardial geometry and motion information. The new functional imaging approach may yield important kinematic information on the distribution of instantaneous velocities in the RV diastolic flow field of specific normal or diseased hearts.

  18. Bias Field Inconsistency Correction of Motion-Scattered Multislice MRI for Improved 3D Image Reconstruction

    PubMed Central

    Kim, Kio; Habas, Piotr A.; Rajagopalan, Vidya; Scott, Julia A.; Corbett-Detig, James M.; Rousseau, Francois; Barkovich, A. James; Glenn, Orit A.; Studholme, Colin

    2012-01-01

    A common solution to clinical MR imaging in the presence of large anatomical motion is to use fast multi-slice 2D studies to reduce slice acquisition time and provide clinically usable slice data. Recently, techniques have been developed which retrospectively correct large scale 3D motion between individual slices allowing the formation of a geometrically correct 3D volume from the multiple slice stacks. One challenge, however, in the final reconstruction process is the possibility of varying intensity bias in the slice data, typically due to the motion of the anatomy relative to imaging coils. As a result, slices which cover the same region of anatomy at different times may exhibit different sensitivity. This bias field inconsistency can induce artifacts in the final 3D reconstruction that can impact both clinical interpretation of key tissue boundaries and the automated analysis of the data. Here we describe a framework to estimate and correct the bias field inconsistency in each slice collectively across all motion corrupted image slices. Experiments using synthetic and clinical data show that the proposed method reduces intensity variability in tissues and improves the distinction between key tissue types. PMID:21511561

  19. Bias field inconsistency correction of motion-scattered multislice MRI for improved 3D image reconstruction.

    PubMed

    Kim, Kio; Habas, Piotr A; Rajagopalan, Vidya; Scott, Julia A; Corbett-Detig, James M; Rousseau, Francois; Barkovich, A James; Glenn, Orit A; Studholme, Colin

    2011-09-01

    A common solution to clinical MR imaging in the presence of large anatomical motion is to use fast multislice 2D studies to reduce slice acquisition time and provide clinically usable slice data. Recently, techniques have been developed which retrospectively correct large scale 3D motion between individual slices allowing the formation of a geometrically correct 3D volume from the multiple slice stacks. One challenge, however, in the final reconstruction process is the possibility of varying intensity bias in the slice data, typically due to the motion of the anatomy relative to imaging coils. As a result, slices which cover the same region of anatomy at different times may exhibit different sensitivity. This bias field inconsistency can induce artifacts in the final 3D reconstruction that can impact both clinical interpretation of key tissue boundaries and the automated analysis of the data. Here we describe a framework to estimate and correct the bias field inconsistency in each slice collectively across all motion corrupted image slices. Experiments using synthetic and clinical data show that the proposed method reduces intensity variability in tissues and improves the distinction between key tissue types.

  20. 3D inversion of total magnetic intensity data for time-domain EM at the Lalor massive sulphide deposit

    NASA Astrophysics Data System (ADS)

    Yang, Dikun; Oldenburg, Douglas W.

    2017-01-01

    The Lalor deposit is a massive sulphide that is characterised as a stack of conductive ore lenses buried more than 600 m deep. We invert helicopter sub-audio magnetics (HeliSAM) data from Lalor collected using a ground large transmitter loop and an airborne total magnetic intensity (TMI) magnetometer measuring the time-domain electromagnetic (EM) responses. The TMI data are modelled as a projection of the anomalous field onto the earth's magnetic field. Inversion of these data is considered a significant case study because of two challenges. First, the early-time data are contaminated by the infrastructure on the surface. Second, inverting the data with a uniform half-space as the initial model results in a mathematically acceptable, but non-geologic, model. We create workflows to overcome these difficulties. For the contaminated data, we use a locally refined mesh and a constrained inversion to recover highly conductive cells near the surface that effectively represent the infrastructure. This allows us to safely extract geologic information from the early time data. The non-uniqueness in the inversion is reduced by warm-starting the voxel 3D inversion with a more reasonable initial guess, for example, a block model from geometric inversions. Those procedures greatly improve the inversion image from the surface to the bottom of the target at Lalor, and they can easily be incorporated into the industrial production workflows.

  1. A 3D technique for simulation of irregular electron treatment fields using a digital camera

    SciTech Connect

    Bassalow, Roustem; Sidhu, Narinder P

    2003-09-30

    Cerrobend inserts, which define electron field apertures, are manufactured at our institution using perspex templates. Contours are reproduced manually on these templates at the simulator from the field outlines drawn on the skin or mask of a patient. A previously reported technique for simulation of electron treatment fields uses a digital camera to eliminate the need for such templates. However, avoidance of the image distortions introduced by non-flat surfaces on which the electron field outlines were drawn could only be achieved by limiting the application of this technique to surfaces which were flat or near flat. We present a technique that employs a digital camera and allows simulation of ele