Relativistic magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Hernandez, Juan; Kovtun, Pavel
2017-05-01
We present the equations of relativistic hydrodynamics coupled to dynamical electromagnetic fields, including the effects of polarization, electric fields, and the derivative expansion. We enumerate the transport coefficients at leading order in derivatives, including electrical conductivities, viscosities, and thermodynamic coefficients. We find the constraints on transport coefficients due to the positivity of entropy production, and derive the corresponding Kubo formulas. For the neutral state in a magnetic field, small fluctuations include Alfvén waves, magnetosonic waves, and the dissipative modes. For the state with a non-zero dynamical charge density in a magnetic field, plasma oscillations gap out all propagating modes, except for Alfvén-like waves with a quadratic dispersion relation. We relate the transport coefficients in the "conventional" magnetohydrodynamics (formulated using Maxwell's equations in matter) to those in the "dual" version of magnetohydrodynamics (formulated using the conserved magnetic flux).
NASA Technical Reports Server (NTRS)
Mizuno, Yosuke; Lyubarsky, Yuri; ishikawa, Ken-Ichi; Hardee, Philip E.
2010-01-01
We have investigated the development of current-driven (CD) kink instability through three-dimensional relativistic MHD simulations. A static force-free equilibrium helical magnetic configuration is considered in order to study the influence of the initial configuration on the linear and nonlinear evolution of the instability. We found that the initial configuration is strongly distorted but not disrupted by the kink instability. The instability develops as predicted by linear theory. In the non-linear regime the kink amplitude continues to increase up to the terminal simulation time, albeit at different rates, for all but one simulation. The growth rate and nonlinear evolution of the CD kink instability depends moderately on the density profile and strongly on the magnetic pitch profile. The growth rate of the kink mode is reduced in the linear regime by an increase in the magnetic pitch with radius and the non-linear regime is reached at a later time than for constant helical pitch. On the other hand, the growth rate of the kink mode is increased in the linear regime by a decrease in the magnetic pitch with radius and reaches the non-linear regime sooner than the case with constant magnetic pitch. Kink amplitude growth in the non-linear regime for decreasing magnetic pitch leads to a slender helically twisted column wrapped by magnetic field. On the other hand, kink amplitude growth in the non-linear regime nearly ceases for increasing magnetic pitch.
Relativistic magnetohydrodynamics in one dimension
NASA Astrophysics Data System (ADS)
Lyutikov, Maxim; Hadden, Samuel
2012-02-01
We derive a number of solutions for one-dimensional dynamics of relativistic magnetized plasma that can be used as benchmark estimates in relativistic hydrodynamic and magnetohydrodynamic numerical codes. First, we analyze the properties of simple waves of fast modes propagating orthogonally to the magnetic field in relativistically hot plasma. The magnetic and kinetic pressures obey different equations of state, so that the system behaves as a mixture of gases with different polytropic indices. We find the self-similar solutions for the expansion of hot strongly magnetized plasma into vacuum. Second, we derive linear hodograph and Darboux equations for the relativistic Khalatnikov potential, which describe arbitrary one-dimensional isentropic relativistic motion of cold magnetized plasma and find their general and particular solutions. The obtained hodograph and Darboux equations are very powerful: A system of highly nonlinear, relativistic, time-dependent equations describing arbitrary (not necessarily self-similar) dynamics of highly magnetized plasma reduces to a single linear differential equation.
Relativistic magnetohydrodynamics in one dimension.
Lyutikov, Maxim; Hadden, Samuel
2012-02-01
We derive a number of solutions for one-dimensional dynamics of relativistic magnetized plasma that can be used as benchmark estimates in relativistic hydrodynamic and magnetohydrodynamic numerical codes. First, we analyze the properties of simple waves of fast modes propagating orthogonally to the magnetic field in relativistically hot plasma. The magnetic and kinetic pressures obey different equations of state, so that the system behaves as a mixture of gases with different polytropic indices. We find the self-similar solutions for the expansion of hot strongly magnetized plasma into vacuum. Second, we derive linear hodograph and Darboux equations for the relativistic Khalatnikov potential, which describe arbitrary one-dimensional isentropic relativistic motion of cold magnetized plasma and find their general and particular solutions. The obtained hodograph and Darboux equations are very powerful: A system of highly nonlinear, relativistic, time-dependent equations describing arbitrary (not necessarily self-similar) dynamics of highly magnetized plasma reduces to a single linear differential equation.
Action Principle for Relativistic Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
D'Avignon, Eric; Morrison, Philip; Pegoraro, Francesco
2015-11-01
A covariant action principle for ideal relativistic magnetohydrodynamics in terms of natural Eulerian field variables is given. This is done by generalizing the covariant Poisson bracket theory of Marsden et al., which uses a noncanonical bracket to implement constrained variations of an action functional. Various implications and extensions of this action principle are also discussed.
GRIM: General Relativistic Implicit Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Chandra, Mani; Foucart, Francois; Gammie, Charles F.
2017-02-01
GRIM (General Relativistic Implicit Magnetohydrodynamics) evolves a covariant extended magnetohydrodynamics model derived by treating non-ideal effects as a perturbation of ideal magnetohydrodynamics. Non-ideal effects are modeled through heat conduction along magnetic field lines and a difference between the pressure parallel and perpendicular to the field lines. The model relies on an effective collisionality in the disc from wave-particle scattering and velocity-space (mirror and firehose) instabilities. GRIM, which runs on CPUs as well as on GPUs, combines time evolution and primitive variable inversion needed for conservative schemes into a single step using only the residuals of the governing equations as inputs. This enables the code to be physics agnostic as well as flexible regarding time-stepping schemes.
Action principle for relativistic magnetohydrodynamics
NASA Astrophysics Data System (ADS)
D'Avignon, Eric; Morrison, P. J.; Pegoraro, F.
2015-04-01
A covariant action principle for ideal relativistic magnetohydrodynamics in terms of natural Eulerian field variables is given. This is done by generalizing the covariant Poisson bracket theory of Marsden et al. [Ann. Phys. 169, 29 (1986)], which uses a noncanonical bracket to effect constrained variations of an action functional. Various implications and extensions of this action principle are also discussed. Two significant byproducts of this formalism are the introduction of a new divergence-free 4-vector variable for the magnetic field, and a new Lie-dragged form for the theory.
Magnetohydrodynamic production of relativistic jets.
Meier, D L; Koide, S; Uchida, Y
2001-01-05
A number of astronomical systems have been discovered that generate collimated flows of plasma with velocities close to the speed of light. In all cases, the central object is probably a neutron star or black hole and is either accreting material from other stars or is in the initial violent stages of formation. Supercomputer simulations of the production of relativistic jets have been based on a magnetohydrodynamic model, in which differential rotation in the system creates a magnetic coil that simultaneously expels and pinches some of the infalling material. The model may explain the basic features of observed jets, including their speed and amount of collimation, and some of the details in the behavior and statistics of different jet-producing sources.
RESISTIVE MAGNETOHYDRODYNAMIC SIMULATIONS OF RELATIVISTIC MAGNETIC RECONNECTION
Zenitani, Seiji; Hesse, Michael; Klimas, Alex
2010-06-20
Resistive relativistic magnetohydrodynamic (RRMHD) simulations are applied to investigate the system evolution of relativistic magnetic reconnection. A time-split Harten-Lan-van Leer method is employed. Under a localized resistivity, the system exhibits a fast reconnection jet with an Alfvenic Lorentz factor inside a narrow Petschek-type exhaust. Various shock structures are resolved in and around the plasmoid such as the post-plasmoid vertical shocks and the 'diamond-chain' structure due to multiple shock reflections. Under a uniform resistivity, Sweet-Parker-type reconnection slowly evolves. Under a current-dependent resistivity, plasmoids are repeatedly formed in an elongated current sheet. It is concluded that the resistivity model is of critical importance for RRMHD modeling of relativistic magnetic reconnection.
Resistive Magnetohydrodynamic Simulations of Relativistic Magnetic Reconnection
NASA Technical Reports Server (NTRS)
Zenitani, Seiji; Hesse, Michael; Klimas, Alex
2010-01-01
Resistive relativistic magnetohydrodynamic (RRMHD) simulations are applied to investigate the system evolution of relativistic magnetic reconnection. A time-split Harten-Lan-van Leer method is employed. Under a localized resistivity, the system exhibits a fast reconnection jet with an Alfv enic Lorentz factor inside a narrow Petschek-type exhaust. Various shock structures are resolved in and around the plasmoid such as the post-plasmoid vertical shocks and the "diamond-chain" structure due to multiple shock reflections. Under a uniform resistivity, Sweet-Parker-type reconnection slowly evolves. Under a current-dependent resistivity, plasmoids are repeatedly formed in an elongated current sheet. It is concluded that the resistivity model is of critical importance for RRMHD modeling of relativistic magnetic reconnection.
Imbalanced relativistic force-free magnetohydrodynamic turbulence
Cho, Jungyeon; Lazarian, A.
2014-01-01
When magnetic energy density is much larger than that of matter, as in pulsar/black hole magnetospheres, the medium becomes force-free and we need relativity to describe it. As in non-relativistic magnetohydrodynamics (MHD), Alfvénic MHD turbulence in the relativistic limit can be described by interactions of counter-traveling wave packets. In this paper, we numerically study strong imbalanced MHD turbulence in such environments. Here, imbalanced turbulence means the waves traveling in one direction (dominant waves) have higher amplitudes than the opposite-traveling waves (sub-dominant waves). We find that (1) spectrum of the dominant waves is steeper than that of sub-dominant waves, (2) the anisotropy of the dominant waves is weaker than that of sub-dominant waves, and (3) the dependence of the ratio of magnetic energy densities of dominant and sub-dominant waves on the ratio of energy injection rates is steeper than quadratic (i.e., b{sub +}{sup 2}/b{sub −}{sup 2}∝(ϵ{sub +}/ϵ{sub −}){sup n} with n > 2). These results are consistent with those obtained for imbalanced non-relativistic Alfvénic turbulence. This corresponds well to the earlier reported similarity of the relativistic and non-relativistic balanced magnetic turbulence.
Rarefaction wave in relativistic steady magnetohydrodynamic flows
Sapountzis, Konstantinos Vlahakis, Nektarios
2014-07-15
We construct and analyze a model of the relativistic steady-state magnetohydrodynamic rarefaction that is induced when a planar symmetric flow (with one ignorable Cartesian coordinate) propagates under a steep drop of the external pressure profile. Using the method of self-similarity, we derive a system of ordinary differential equations that describe the flow dynamics. In the specific limit of an initially homogeneous flow, we also provide analytical results and accurate scaling laws. We consider that limit as a generalization of the previous Newtonian and hydrodynamic solutions already present in the literature. The model includes magnetic field and bulk flow speed having all components, whose role is explored with a parametric study.
Efficient acceleration of relativistic magnetohydrodynamic jets
NASA Astrophysics Data System (ADS)
Toma, Kenji; Takahara, Fumio
2013-08-01
Relativistic jets in active galactic nuclei, galactic microquasars, and gamma-ray bursts are widely considered to be magnetohydrodynamically driven by black hole accretion systems, although the conversion mechanism from the Poynting into the particle kinetic energy flux is still open. Recent detailed numerical and analytical studies of global structures of steady, axisymmetric magnetohydrodynamic (MHD) flows with specific boundary conditions have not reproduced as rapid an energy conversion as required by observations. In order to find more suitable boundary conditions, we focus on the flow along a poloidal magnetic field line just inside the external boundary, without treating the transfield force balance in detail. We find some examples of the poloidal field structure and corresponding external pressure profile for an efficient and rapid energy conversion as required by observations, and that the rapid acceleration requires a rapid decrease of the external pressure above the accretion disk. We also clarify the differences between the fast magnetosonic point of the MHD flow and the sonic point of the de Laval nozzle.
COUNTER-ROTATION IN RELATIVISTIC MAGNETOHYDRODYNAMIC JETS
Cayatte, V.; Sauty, C.; Vlahakis, N.; Tsinganos, K.; Matsakos, T.; Lima, J. J. G.
2014-06-10
Young stellar object observations suggest that some jets rotate in the opposite direction with respect to their disk. In a recent study, Sauty et al. showed that this does not contradict the magnetocentrifugal mechanism that is believed to launch such outflows. Motion signatures that are transverse to the jet axis, in two opposite directions, have recently been measured in M87. One possible interpretation of this motion is that of counter-rotating knots. Here, we extend our previous analytical derivation of counter-rotation to relativistic jets, demonstrating that counter-rotation can indeed take place under rather general conditions. We show that both the magnetic field and a non-negligible enthalpy are necessary at the origin of counter-rotating outflows, and that the effect is associated with a transfer of energy flux from the matter to the electromagnetic field. This can be realized in three cases: if a decreasing enthalpy causes an increase of the Poynting flux, if the flow decelerates, or if strong gradients of the magnetic field are present. An illustration of the involved mechanism is given by an example of a relativistic magnetohydrodynamic jet simulation.
Lattice Boltzmann model for resistive relativistic magnetohydrodynamics.
Mohseni, F; Mendoza, M; Succi, S; Herrmann, H J
2015-08-01
In this paper, we develop a lattice Boltzmann model for relativistic magnetohydrodynamics (MHD). Even though the model is derived for resistive MHD, it is shown that it is numerically robust even in the high conductivity (ideal MHD) limit. In order to validate the numerical method, test simulations are carried out for both ideal and resistive limits, namely the propagation of Alfvén waves in the ideal MHD and the evolution of current sheets in the resistive regime, where very good agreement is observed comparing to the analytical results. Additionally, two-dimensional magnetic reconnection driven by Kelvin-Helmholtz instability is studied and the effects of different parameters on the reconnection rate are investigated. It is shown that the density ratio has a negligible effect on the magnetic reconnection rate, while an increase in shear velocity decreases the reconnection rate. Additionally, it is found that the reconnection rate is proportional to σ-1/2, σ being the conductivity, which is in agreement with the scaling law of the Sweet-Parker model. Finally, the numerical model is used to study the magnetic reconnection in a stellar flare. Three-dimensional simulation suggests that the reconnection between the background and flux rope magnetic lines in a stellar flare can take place as a result of a shear velocity in the photosphere.
Lattice Boltzmann model for resistive relativistic magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Mohseni, F.; Mendoza, M.; Succi, S.; Herrmann, H. J.
2015-08-01
In this paper, we develop a lattice Boltzmann model for relativistic magnetohydrodynamics (MHD). Even though the model is derived for resistive MHD, it is shown that it is numerically robust even in the high conductivity (ideal MHD) limit. In order to validate the numerical method, test simulations are carried out for both ideal and resistive limits, namely the propagation of Alfvén waves in the ideal MHD and the evolution of current sheets in the resistive regime, where very good agreement is observed comparing to the analytical results. Additionally, two-dimensional magnetic reconnection driven by Kelvin-Helmholtz instability is studied and the effects of different parameters on the reconnection rate are investigated. It is shown that the density ratio has a negligible effect on the magnetic reconnection rate, while an increase in shear velocity decreases the reconnection rate. Additionally, it is found that the reconnection rate is proportional to σ-1 / 2, σ being the conductivity, which is in agreement with the scaling law of the Sweet-Parker model. Finally, the numerical model is used to study the magnetic reconnection in a stellar flare. Three-dimensional simulation suggests that the reconnection between the background and flux rope magnetic lines in a stellar flare can take place as a result of a shear velocity in the photosphere.
Regularity of the 3 D Stationary Hall Magnetohydrodynamic Equations on the Plane
NASA Astrophysics Data System (ADS)
Chae, Dongho; Wolf, Jörg
2017-08-01
We study the regularity of weak solutions to the 3D valued stationary Hall magnetohydrodynamic equations on R^2. We prove that every weak solution is smooth. Furthermore, we prove a Liouville type theorem for the Hall equations.
General relativistic magneto-hydrodynamics with the Einstein Toolkit
NASA Astrophysics Data System (ADS)
Moesta, Philipp; Mundim, Bruno; Faber, Joshua; Noble, Scott; Bode, Tanja; Haas, Roland; Loeffler, Frank; Ott, Christian; Reisswig, Christian; Schnetter, Erik
2013-04-01
The Einstein Toolkit Consortium is developing and supporting open software for relativistic astrophysics. Its aim is to provide the core computational tools that can enable new science, broaden our community, facilitate interdisciplinary research and take advantage of petascale computers and advanced cyberinfrastructure. The Einstein Toolkit currently consists of an open set of over 100 modules for the Cactus framework, primarily for computational relativity along with associated tools for simulation management and visualization. The toolkit includes solvers for vacuum spacetimes as well as relativistic magneto-hydrodynamics. This talk will present the current capabilities of the Einstein Toolkit with a particular focus on recent improvements made to the general relativistic magneto-hydrodynamics modeling and will point to information how to leverage it for future research.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.
1999-05-01
Koide et al have investigated the dynamics of an accretion disk initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code on a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics. 3-D RMHD simulations wil be also performed to investigate the dynamics of a jet with a helical mangetic field in it.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.
1999-12-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.
2001-12-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.
2000-12-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.
Jet Formation with 3-D General Relativistic MHD Simulations
NASA Astrophysics Data System (ADS)
Richardson, G. A.; Nishikawa, K.-I.; Preece, R.; Hardee, P.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.; Fishman, J.
2002-12-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (in a steady-state infalling state) around a non-rotating black hole using 3-D GRMHD with the ``axisymmetry'' along the z-direction. The magnetic field is tightly twisted by the rotation of the accretion disk, and plasmas in the shocked region of the disk are accelerated by the J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and the magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, Ken-Ichi; Koide, Shinji; Shibata, Kazunari; Kudoh, Takashiro; Sol, Helene; Hughes, John
2002-04-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J × B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.
Modification of magnetohydrodynamic waves by the relativistic Hall effect
NASA Astrophysics Data System (ADS)
Kawazura, Yohei
2017-07-01
This study shows that a relativistic Hall effect significantly changes the properties of wave propagation by deriving a linear dispersion relation for relativistic Hall magnetohydrodynamics (HMHD). Whereas, in nonrelativistic HMHD, the phase and group velocities of fast magnetosonic wave become anisotropic with an increasing Hall effect, the relativistic Hall effect brings upper bounds to the anisotropies. The Alfvén wave group velocity with strong Hall effect also becomes less anisotropic than the nonrelativistic case. Moreover, the group velocity surfaces of Alfvén and fast waves coalesce into a single surface in the direction other than near perpendicular to the ambient magnetic field. It is also remarkable that a characteristic scale length of the relativistic HMHD depends on ion temperature, magnetic field strength, and density while the nonrelativistic HMHD scale length, i.e., ion skin depth, depends only on density. The modified characteristic scale length increases as the ion temperature increases and decreases as the magnetic field strength increases.
Group velocity and causality in standard relativistic resistive magnetohydrodynamics
Koide, Shinji; Morino, Ryogo
2011-10-15
Group velocity of electromagnetic waves in plasmas derived by standard relativistic resistive magnetohydrodynamics equations is superluminal. If we assume that the group velocity represents the propagation velocity of a signal, we have to worry about the causality problem. That is, some acausal phenomena may be induced, such as information transportation to the absolute past and a spontaneous decrease in the entropy. Here, we tried to find the acausal phenomena using standard relativistic resistive magnetohydrodynamics numerical simulations in the suggested situation of the acausal phenomena. The calculation results showed that even in such situations no acausal effect happens. The numerical result with respect to the velocity limit of the information transportation is consistent with a linear theory of wave train propagation. Our results assure that we can use these equations without the problems of acausal phenomena.
HERO - A 3D general relativistic radiative post-processor for accretion discs around black holes
NASA Astrophysics Data System (ADS)
Zhu, Yucong; Narayan, Ramesh; Sadowski, Aleksander; Psaltis, Dimitrios
2015-08-01
HERO (Hybrid Evaluator for Radiative Objects) is a 3D general relativistic radiative transfer code which has been tailored to the problem of analysing radiation from simulations of relativistic accretion discs around black holes. HERO is designed to be used as a post-processor. Given some fixed fluid structure for the disc (i.e. density and velocity as a function of position from a hydrodynamic or magnetohydrodynamic simulation), the code obtains a self-consistent solution for the radiation field and for the gas temperatures using the condition of radiative equilibrium. The novel aspect of HERO is that it combines two techniques: (1) a short-characteristics (SC) solver that quickly converges to a self-consistent disc temperature and radiation field, with (2) a long-characteristics (LC) solver that provides a more accurate solution for the radiation near the photosphere and in the optically thin regions. By combining these two techniques, we gain both the computational speed of SC and the high accuracy of LC. We present tests of HERO on a range of 1D, 2D, and 3D problems in flat space and show that the results agree well with both analytical and benchmark solutions. We also test the ability of the code to handle relativistic problems in curved space. Finally, we discuss the important topic of ray defects, a major limitation of the SC method, and describe our strategy for minimizing the induced error.
Tokamak magnetohydrodynamic equilibrium states with axisymmetric boundary and a 3D helical core.
Cooper, W A; Graves, J P; Pochelon, A; Sauter, O; Villard, L
2010-07-16
Magnetohydrodynamic (MHD) equilibrium states with imposed axisymmetric boundary are computed in which a spontaneous bifurcation develops to produce an internal three-dimensional (3D) configuration with a helical structure in addition to the standard axisymmetric system. Equilibrium states with similar MHD energy levels are shown to develop very different geometric structures. The helical equilibrium states resemble saturated internal kink mode structures.
Tokamak Magnetohydrodynamic Equilibrium States with Axisymmetric Boundary and a 3D Helical Core
Cooper, W. A.; Graves, J. P.; Pochelon, A.; Sauter, O.; Villard, L.
2010-07-16
Magnetohydrodynamic (MHD) equilibrium states with imposed axisymmetric boundary are computed in which a spontaneous bifurcation develops to produce an internal three-dimensional (3D) configuration with a helical structure in addition to the standard axisymmetric system. Equilibrium states with similar MHD energy levels are shown to develop very different geometric structures. The helical equilibrium states resemble saturated internal kink mode structures.
3D Magnetohydrodynamic Models of Nonthermal Photon Emission in the Binary System γ 2 Velorum
NASA Astrophysics Data System (ADS)
Reitberger, K.; Kissmann, R.; Reimer, A.; Reimer, O.
2017-09-01
Recent reports claiming an association of the massive star binary system {γ }2 Velorum (WR 11) with a high-energy γ-ray source observed by Fermi-LAT contrast the so far exclusive role of η Carinae as the hitherto only detected γ-ray emitter in the source class of particle-accelerating colliding-wind binary (CWB) systems. We offer support to this claim of association by providing dedicated model predictions for the nonthermal photon emission spectrum of {γ }2 Velorum. We use 3D magnetohydrodynamic modeling (MHD) to investigate the structure and conditions of the wind-collision region (WCR) of {γ }2 Velorum including the important effect of radiative braking in the stellar winds. A transport equation is then solved for the entire computational domain to study the propagation of relativistic electrons and protons. The resulting distributions of particles are subsequently used to compute nonthermal photon emission components. In agreement with observation in X-ray spectroscopy, our simulations yield a large shock-cone opening angle. We find the nonthermal γ-ray emission of {γ }2 Velorum to be of hadronic origin owing to the strong radiation fields in the binary system, which inhibit the acceleration of electrons to energies sufficiently high for efficient inverse-Compton radiation. We also discuss the strong dependence of a hadronic γ-ray component on the energy-dependent diffusion used in the simulations. Of two mass-loss rates for the WR star found in literature, only the higher rate is able to accommodate the observed γ-ray spectrum with reasonable values for important simulation parameters such as the injection ratio of high-energy particles within the WCR.
SYNCHROTRON RADIATION OF SELF-COLLIMATING RELATIVISTIC MAGNETOHYDRODYNAMIC JETS
Porth, Oliver; Fendt, Christian; Vaidya, Bhargav; Meliani, Zakaria E-mail: fendt@mpia.de
2011-08-10
The goal of this paper is to derive signatures of synchrotron radiation from state-of-the-art simulation models of collimating relativistic magnetohydrodynamic (MHD) jets featuring a large-scale helical magnetic field. We perform axisymmetric special relativistic MHD simulations of the jet acceleration region using the PLUTO code. The computational domain extends from the slow-magnetosonic launching surface of the disk up to 6000{sup 2} Schwarzschild radii allowing jets to reach highly relativistic Lorentz factors. The Poynting-dominated disk wind develops into a jet with Lorentz factors of {Gamma} {approx_equal} 8 and is collimated to 1{sup 0}. In addition to the disk jet, we evolve a thermally driven spine jet emanating from a hypothetical black hole corona. Solving the linearly polarized synchrotron radiation transport within the jet, we derive very long baseline interferometry radio and (sub-) millimeter diagnostics such as core shift, polarization structure, intensity maps, spectra, and Faraday rotation measure (RM) directly from the Stokes parameters. We also investigate depolarization and the detectability of a {lambda}{sup 2}-law RM depending on beam resolution and observing frequency. We find non-monotonic intrinsic RM profiles that could be detected at a resolution of 100 Schwarzschild radii. In our collimating jet geometry, the strict bimodality in the polarization direction (as predicted by Pariev et al.) can be circumvented. Due to relativistic aberration, asymmetries in the polarization vectors across the jet can hint at the spin direction of the central engine.
Isotropic Landau levels of relativistic and non-relativistic fermions in 3D flat space
NASA Astrophysics Data System (ADS)
Li, Yi; Wu, Congjun
2012-02-01
The usual Landau level quantization, as demonstrated in the 2D quantum Hall effect, is crucially based on the planar structure. In this talk, we explore its 3D counterpart possessing the full 3D rotational symmetry as well as the time reversal symmetry. We construct the Landau level Hamiltonians in 3 and higher dimensional flat space for both relativistic and non-relativistic fermions. The 3D cases with integer fillings are Z2 topological insulators. The non-relativistic version describes spin-1/2 fermions coupling to the Aharonov-Casher SU(2) gauge field. This system exhibits flat Landau levels in which the orbital angular momentum and the spin are coupled with a fixed helicity. Each filled Landau level contributes one 2D helical Dirac Fermi surface at an open boundary, which demonstrates the Z2 topological nature. A natural generalization to Dirac fermions is found as a square root problem of the above non-relativistic version, which can also be viewed as the Dirac equation defined on the phase space. All these Landau level problems can be generalized to arbitrary high dimensions systematically. [4pt] [1] Yi Li and Congjun Wu, arXiv:1103.5422.[0pt] [2] Yi Li, Ken Intriligator, Yue Yu and Congjun Wu, arXiv:1108.5650.
Photospheric Emission from Collapsar Jets in 3D Relativistic Hydrodynamics
NASA Astrophysics Data System (ADS)
Ito, Hirotaka; Matsumoto, Jin; Nagataki, Shigehiro; Warren, Donald C.; Barkov, Maxim V.
2015-12-01
We explore the photospheric emission from a relativistic jet breaking out from a massive stellar envelope based on relativistic hydrodynamical simulations and post-process radiation transfer calculations in three dimensions. To investigate the impact of three-dimensional (3D) dynamics on the emission, two models of injection conditions are considered for the jet at the center of the progenitor star: one with periodic precession and another without precession. We show that structures developed within the jet due to the interaction with the stellar envelope, as well as due to the precession, have a significant imprint on the resulting emission. Particularly, we find that the signature of precession activity by the central engine is not smeared out and can be directly observed in the light curve as a periodic signal. We also show that non-thermal features, which can account for observations of gamma-ray bursts, are produced in the resulting spectra even though only thermal photons are injected initially and the effect of non-thermal particles is not considered.
PHOTOSPHERIC EMISSION FROM COLLAPSAR JETS IN 3D RELATIVISTIC HYDRODYNAMICS
Ito, Hirotaka; Matsumoto, Jin; Nagataki, Shigehiro; Warren, Donald C.; Barkov, Maxim V.
2015-12-01
We explore the photospheric emission from a relativistic jet breaking out from a massive stellar envelope based on relativistic hydrodynamical simulations and post-process radiation transfer calculations in three dimensions. To investigate the impact of three-dimensional (3D) dynamics on the emission, two models of injection conditions are considered for the jet at the center of the progenitor star: one with periodic precession and another without precession. We show that structures developed within the jet due to the interaction with the stellar envelope, as well as due to the precession, have a significant imprint on the resulting emission. Particularly, we find that the signature of precession activity by the central engine is not smeared out and can be directly observed in the light curve as a periodic signal. We also show that non-thermal features, which can account for observations of gamma-ray bursts, are produced in the resulting spectra even though only thermal photons are injected initially and the effect of non-thermal particles is not considered.
NASA Astrophysics Data System (ADS)
Narayan, Ramesh; Zhu, Yucong; Psaltis, Dimitrios; Saḑowski, Aleksander
2016-03-01
We describe Hybrid Evaluator for Radiative Objects Including Comptonization (HEROIC), an upgraded version of the relativistic radiative post-processor code HERO described in a previous paper, but which now Includes Comptonization. HEROIC models Comptonization via the Kompaneets equation, using a quadratic approximation for the source function in a short characteristics radiation solver. It employs a simple form of accelerated lambda iteration to handle regions of high scattering opacity. In addition to solving for the radiation field, HEROIC also solves for the gas temperature by applying the condition of radiative equilibrium. We present benchmarks and tests of the Comptonization module in HEROIC with simple 1D and 3D scattering problems. We also test the ability of the code to handle various relativistic effects using model atmospheres and accretion flows in a black hole space-time. We present two applications of HEROIC to general relativistic magnetohydrodynamics simulations of accretion discs. One application is to a thin accretion disc around a black hole. We find that the gas below the photosphere in the multidimensional HEROIC solution is nearly isothermal, quite different from previous solutions based on 1D plane parallel atmospheres. The second application is to a geometrically thick radiation-dominated accretion disc accreting at 11 times the Eddington rate. Here, the multidimensional HEROIC solution shows that, for observers who are on axis and look down the polar funnel, the isotropic equivalent luminosity could be more than 10 times the Eddington limit, even though the spectrum might still look thermal and show no signs of relativistic beaming.
Cosmos++: Relativistic Magnetohydrodynamics on Unstructured Grids with Local Adaptive Refinement
Anninos, P; Fragile, P C; Salmonson, J D
2005-05-06
A new code and methodology are introduced for solving the fully general relativistic magnetohydrodynamic (GRMHD) equations using time-explicit, finite-volume discretization. The code has options for solving the GRMHD equations using traditional artificial-viscosity (AV) or non-oscillatory central difference (NOCD) methods, or a new extended AV (eAV) scheme using artificial-viscosity together with a dual energy-flux-conserving formulation. The dual energy approach allows for accurate modeling of highly relativistic flows at boost factors well beyond what has been achieved to date by standard artificial viscosity methods. it provides the benefit of Godunov methods in capturing high Lorentz boosted flows but without complicated Riemann solvers, and the advantages of traditional artificial viscosity methods in their speed and flexibility. Additionally, the GRMHD equations are solved on an unstructured grid that supports local adaptive mesh refinement using a fully threated oct-tree (in three dimensions) network to traverse the grid hierarchy across levels and immediate neighbors. A number of tests are presented to demonstrate robustness of the numerical algorithms and adaptive mesh framework over a wide spectrum of problems, boosts, and astrophysical applications, including relativistic shock tubes, shock collisions, magnetosonic shocks, Alfven wave propagation, blast waves, magnetized Bondi flow, and the magneto-rotational instability in Kerr black hole spacetimes.
NASA Astrophysics Data System (ADS)
Wang, Yanqing; Wu, Gang; Zhou, Daoguo
2016-12-01
By means of blow-up method and the special structure of the 3D viscous magnetohydrodynamics equations, we derive some interior regularity criteria in terms of horizontal part of the velocity with sufficiently small local scaled norm and both the vertical part of the velocity and the magnetic field with bounded local scaled norm for the suitable weak solutions to this system. As an application, this allows us to improve the previous limiting case for the regularity criterion about the MHD equations.
bhlight: General Relativistic Radiation Magnetohydrodynamics with Monte Carlo Transport
Ryan, Benjamin R; Dolence, Joshua C.; Gammie, Charles F.
2015-06-25
We present bhlight, a numerical scheme for solving the equations of general relativistic radiation magnetohydrodynamics using a direct Monte Carlo solution of the frequency-dependent radiative transport equation. bhlight is designed to evolve black hole accretion flows at intermediate accretion rate, in the regime between the classical radiatively efficient disk and the radiatively inefficient accretion flow (RIAF), in which global radiative effects play a sub-dominant but non-negligible role in disk dynamics. We describe the governing equations, numerical method, idiosyncrasies of our implementation, and a suite of test and convergence results. We also describe example applications to radiative Bondi accretion and tomore » a slowly accreting Kerr black hole in axisymmetry.« less
bhlight: General Relativistic Radiation Magnetohydrodynamics with Monte Carlo Transport
Ryan, Benjamin R; Dolence, Joshua C.; Gammie, Charles F.
2015-06-25
We present bhlight, a numerical scheme for solving the equations of general relativistic radiation magnetohydrodynamics using a direct Monte Carlo solution of the frequency-dependent radiative transport equation. bhlight is designed to evolve black hole accretion flows at intermediate accretion rate, in the regime between the classical radiatively efficient disk and the radiatively inefficient accretion flow (RIAF), in which global radiative effects play a sub-dominant but non-negligible role in disk dynamics. We describe the governing equations, numerical method, idiosyncrasies of our implementation, and a suite of test and convergence results. We also describe example applications to radiative Bondi accretion and to a slowly accreting Kerr black hole in axisymmetry.
bhlight: GENERAL RELATIVISTIC RADIATION MAGNETOHYDRODYNAMICS WITH MONTE CARLO TRANSPORT
Ryan, B. R.; Gammie, C. F.; Dolence, J. C.
2015-07-01
We present bhlight, a numerical scheme for solving the equations of general relativistic radiation magnetohydrodynamics using a direct Monte Carlo solution of the frequency-dependent radiative transport equation. bhlight is designed to evolve black hole accretion flows at intermediate accretion rate, in the regime between the classical radiatively efficient disk and the radiatively inefficient accretion flow (RIAF), in which global radiative effects play a sub-dominant but non-negligible role in disk dynamics. We describe the governing equations, numerical method, idiosyncrasies of our implementation, and a suite of test and convergence results. We also describe example applications to radiative Bondi accretion and to a slowly accreting Kerr black hole in axisymmetry.
ACCELERATION AND COLLIMATION OF RELATIVISTIC MAGNETOHYDRODYNAMIC DISK WINDS
Porth, Oliver; Fendt, Christian E-mail: fendt@mpia.d
2010-02-01
We perform axisymmetric relativistic magnetohydrodynamic simulations to investigate the acceleration and collimation of jets and outflows from disks around compact objects. Newtonian gravity is added to the relativistic treatment in order to establish the physical boundary condition of an underlying accretion disk in centrifugal and pressure equilibrium. The fiducial disk surface (respectively a slow disk wind) is prescribed as boundary condition for the outflow. We apply this technique for the first time in the context of relativistic jets. The strength of this approach is that it allows us to run a parameter study in order to investigate how the accretion disk conditions govern the outflow formation. Substantial effort has been made to implement a current-free, numerical outflow boundary condition in order to avoid artificial collimation present in the standard outflow conditions. Our simulations using the PLUTO code run for 500 inner disk rotations and on a physical grid size of 100 x 200 inner disk radii. The simulations evolve from an initial state in hydrostatic equilibrium and an initially force-free magnetic field configuration. Two options for the initial field geometries are applied-an hourglass-shaped potential magnetic field and a split monopole field. Most of our parameter runs evolve into a steady state solution which can be further analyzed concerning the physical mechanism at work. In general, we obtain collimated beams of mildly relativistic speed with Lorentz factors up to 6 and mass-weighted half-opening angles of 3-7 deg. The split-monopole initial setup usually results in less collimated outflows. The light surface of the outflow magnetosphere tends to align vertically-implying three relativistically distinct regimes in the flow-an inner subrelativistic domain close to the jet axis, a (rather narrow) relativistic jet and a surrounding subrelativistic outflow launched from the outer disk surface-similar to the spine-sheath structure currently
Acceleration and Collimation of Relativistic Magnetohydrodynamic Disk Winds
NASA Astrophysics Data System (ADS)
Porth, Oliver; Fendt, Christian
2010-02-01
We perform axisymmetric relativistic magnetohydrodynamic simulations to investigate the acceleration and collimation of jets and outflows from disks around compact objects. Newtonian gravity is added to the relativistic treatment in order to establish the physical boundary condition of an underlying accretion disk in centrifugal and pressure equilibrium. The fiducial disk surface (respectively a slow disk wind) is prescribed as boundary condition for the outflow. We apply this technique for the first time in the context of relativistic jets. The strength of this approach is that it allows us to run a parameter study in order to investigate how the accretion disk conditions govern the outflow formation. Substantial effort has been made to implement a current-free, numerical outflow boundary condition in order to avoid artificial collimation present in the standard outflow conditions. Our simulations using the PLUTO code run for 500 inner disk rotations and on a physical grid size of 100 × 200 inner disk radii. The simulations evolve from an initial state in hydrostatic equilibrium and an initially force-free magnetic field configuration. Two options for the initial field geometries are applied—an hourglass-shaped potential magnetic field and a split monopole field. Most of our parameter runs evolve into a steady state solution which can be further analyzed concerning the physical mechanism at work. In general, we obtain collimated beams of mildly relativistic speed with Lorentz factors up to 6 and mass-weighted half-opening angles of 3-7 deg. The split-monopole initial setup usually results in less collimated outflows. The light surface of the outflow magnetosphere tends to align vertically—implying three relativistically distinct regimes in the flow—an inner subrelativistic domain close to the jet axis, a (rather narrow) relativistic jet and a surrounding subrelativistic outflow launched from the outer disk surface—similar to the spine-sheath structure
Numerical magneto-hydrodynamics for relativistic nuclear collisions
NASA Astrophysics Data System (ADS)
Inghirami, Gabriele; Del Zanna, Luca; Beraudo, Andrea; Moghaddam, Mohsen Haddadi; Becattini, Francesco; Bleicher, Marcus
2016-12-01
We present an improved version of the ECHO-QGP numerical code, which self-consistently includes for the first time the effects of electromagnetic fields within the framework of relativistic magneto-hydrodynamics (RMHD). We discuss results of its application in relativistic heavy-ion collisions in the limit of infinite electrical conductivity of the plasma. After reviewing the relevant covariant 3+1 formalisms, we illustrate the implementation of the evolution equations in the code and show the results of several tests aimed at assessing the accuracy and robustness of the implementation. After providing some estimates of the magnetic fields arising in non-central high-energy nuclear collisions, we perform full RMHD simulations of the evolution of the quark-gluon plasma in the presence of electromagnetic fields and discuss the results. In our ideal RMHD setup we find that the magnetic field developing in non-central collisions does not significantly modify the elliptic flow of the final hadrons. However, since there are uncertainties in the description of the pre-equilibrium phase and also in the properties of the medium, a more extensive survey of the possible initial conditions as well as the inclusion of dissipative effects are indeed necessary to validate this preliminary result.
Primitive Variable Solvers for Conservative General Relativistic Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Noble, Scott C.; Gammie, Charles F.; McKinney, Jonathan C.; Del Zanna, Luca
2006-04-01
Conservative numerical schemes for general relativistic magnetohydrodynamics (GRMHD) require a method for transforming between ``conserved'' variables such as momentum and energy density and ``primitive'' variables such as rest-mass density, internal energy, and components of the four-velocity. The forward transformation (primitive to conserved) has a closed-form solution, but the inverse transformation (conserved to primitive) requires the solution of a set of five nonlinear equations. Here we discuss the mathematical properties of the inverse transformation and present six numerical methods for performing the inversion. The first method solves the full set of five nonlinear equations directly using a Newton-Raphson scheme and a guess from the previous time step. The other methods reduce the five nonlinear equations to either one or two nonlinear equations that are solved numerically. Comparisons between the methods are made using a survey over phase space, a two-dimensional explosion problem, and a general relativistic MHD accretion disk simulation. The run time of the methods is also examined. Code implementing the schemes is available with the electronic edition of the article.
TWO-FLUID MAGNETOHYDRODYNAMIC SIMULATIONS OF RELATIVISTIC MAGNETIC RECONNECTION
Zenitani, Seiji; Hesse, Michael; Klimas, Alex
2009-05-10
We investigate the large-scale evolution of a relativistic magnetic reconnection in an electron-positron pair plasma by a relativistic two-fluid magnetohydrodynamic (MHD) code. We introduce an interspecies friction force as an effective resistivity to dissipate magnetic fields. We demonstrate that magnetic reconnection successfully occurs in our two-fluid system, and that it involves Petschek-type bifurcated current layers in a later stage. We further observe a quasi-steady evolution thanks to an open boundary condition, and find that the Petschek-type structure is stable over the long time period. Simulation results and theoretical analyses exhibit that the Petschek outflow channel becomes narrower when the reconnection inflow contains more magnetic energy, as previously claimed. Meanwhile, we find that the reconnection rate goes up to {approx}1 in extreme cases, which is faster than previously thought. The role of the resistivity, implications for reconnection models in the magnetically dominated limit, and relevance to kinetic reconnection works are discussed.
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.
Magnetohydrodynamic Jump Conditions for Oblique Relativistic Shocks with Gyrotropic Pressure
NASA Technical Reports Server (NTRS)
Double, Glen P.; Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.
2003-01-01
Shock jump conditions, i.e., the specification of the downstream parameters of the gas in terms of the upstream parameters, are obtained for steady-state, plane shocks with oblique magnetic fields and arbitrary flow speeds. This is done by combining the continuity of particle number flux and the electromagnetic boundary conditions at the shock with the magnetohydrodynamic conservation laws derived from the stress-energy tensor. For ultrarelativistic and nonrelativistic shocks, the jump conditions may be solved analytically. For mildly relativistic shocks, analytic solutions are obtained for isotropic pressure using an approximation for the adiabatic index that is valid in high sonic Mach number cases. Examples assuming isotropic pressure illustrate how the shock compression ratio depends on the shock speed and obliquity. In the more general case of gyrotropic pressure, the jump conditions cannot be solved analytically with- out additional assumptions, and the effects of gyrotropic pressure are investigated by parameterizing the distribution of pressure parallel and perpendicular to the magnetic field. Our numerical solutions reveal that relatively small departures from isotropy (e.g., approximately 20%) produce significant changes in the shock compression ratio, r , at all shock Lorentz factors, including ultrarelativistic ones, where an analytic solution with gyrotropic pressure is obtained. In particular, either dynamically important fields or significant pressure anisotropies can incur marked departures from the canonical gas dynamic value of r = 3 for a shocked ultrarelativistic flow and this may impact models of particle acceleration in gamma-ray bursts and other environments where relativistic shocks are inferred. The jump conditions presented apply directly to test-particle acceleration, and will facilitate future self-consistent numerical modeling of particle acceleration at oblique, relativistic shocks; such models include the modification of the fluid
Effects of a weakly 3-D equilibrium on ideal magnetohydrodynamic instabilities
Hegna, C. C.
2014-07-15
The effect of a small three-dimensional equilibrium distortion on an otherwise axisymmetric configuration is shown to be destabilizing to ideal magnetohydrodynamic modes. The calculations assume that the 3-D fields are weak and that shielding physics is present so that no islands appear in the resulting equilibrium. An eigenfunction that has coupled harmonics of different toroidal mode number is constructed using a perturbation approach. The theory is applied to the case of tokamak H-modes with shielded resonant magnetic perturbations (RMPs) present indicating RMPs can be destabilizing to intermediate-n peeling-ballooning modes.
NASA Astrophysics Data System (ADS)
Shiokawa, Hotaka; Dolence, Joshua C.; Gammie, Charles F.; Noble, Scott C.
2012-01-01
Global, general relativistic magnetohydrodynamic (GRMHD) simulations of non-radiative, magnetized disks are widely used to model accreting black holes. We have performed a convergence study of GRMHD models computed with HARM3D. The models span a factor of four in linear resolution, from 96 × 96 × 64 to 384 × 384 × 256. We consider three diagnostics of convergence: (1) dimensionless shell-averaged quantities such as plasma β (2) the azimuthal correlation length of fluid variables; and (3) synthetic spectra of the source including synchrotron emission, absorption, and Compton scattering. Shell-averaged temperature is, except for the lowest resolution run, nearly independent of resolution; shell-averaged plasma β decreases steadily with resolution but shows signs of convergence. The azimuthal correlation lengths of density, internal energy, and temperature decrease steadily with resolution but show signs of convergence. In contrast, the azimuthal correlation length of magnetic field decreases nearly linearly with grid size. We argue by analogy with local models, however, that convergence should be achieved with another factor of two in resolution. Synthetic spectra are, except for the lowest resolution run, nearly independent of resolution. The convergence behavior is consistent with that of higher physical resolution local model ("shearing box") calculations and with the recent non-relativistic global convergence studies of Hawley et al.
Shiokawa, Hotaka; Dolence, Joshua C.; Gammie, Charles F.; Noble, Scott C.
2012-01-10
Global, general relativistic magnetohydrodynamic (GRMHD) simulations of non-radiative, magnetized disks are widely used to model accreting black holes. We have performed a convergence study of GRMHD models computed with HARM3D. The models span a factor of four in linear resolution, from 96 Multiplication-Sign 96 Multiplication-Sign 64 to 384 Multiplication-Sign 384 Multiplication-Sign 256. We consider three diagnostics of convergence: (1) dimensionless shell-averaged quantities such as plasma {beta}; (2) the azimuthal correlation length of fluid variables; and (3) synthetic spectra of the source including synchrotron emission, absorption, and Compton scattering. Shell-averaged temperature is, except for the lowest resolution run, nearly independent of resolution; shell-averaged plasma {beta} decreases steadily with resolution but shows signs of convergence. The azimuthal correlation lengths of density, internal energy, and temperature decrease steadily with resolution but show signs of convergence. In contrast, the azimuthal correlation length of magnetic field decreases nearly linearly with grid size. We argue by analogy with local models, however, that convergence should be achieved with another factor of two in resolution. Synthetic spectra are, except for the lowest resolution run, nearly independent of resolution. The convergence behavior is consistent with that of higher physical resolution local model ({sup s}hearing box{sup )} calculations and with the recent non-relativistic global convergence studies of Hawley et al.
Fast reconnection in relativistic plasmas: the magnetohydrodynamics tearing instability revisited
NASA Astrophysics Data System (ADS)
Del Zanna, L.; Papini, E.; Landi, S.; Bugli, M.; Bucciantini, N.
2016-08-01
Fast reconnection operating in magnetically dominated plasmas is often invoked in models for magnetar giant flares, for magnetic dissipation in pulsar winds, or to explain the gamma-ray flares observed in the Crab nebula; hence, its investigation is of paramount importance in high-energy astrophysics. Here we study, by means of two-dimensional numerical simulations, the linear phase and the subsequent non-linear evolution of the tearing instability within the framework of relativistic resistive magnetohydrodynamics (MHD), as appropriate in situations where the Alfvén velocity approaches the speed of light. It is found that the linear phase of the instability closely matches the analysis in classical MHD, where the growth rate scales with the Lundquist number S as S-1/2, with the only exception of an enhanced inertial term due to the thermal and magnetic energy contributions. In addition, when thin current sheets of inverse aspect ratio scaling as S-1/3 are considered, the so-called ideal tearing regime is retrieved, with modes growing independently of S and extremely fast, on only a few light crossing times of the sheet length. The overall growth of fluctuations is seen to solely depend on the value of the background Alfvén velocity. In the fully non-linear stage, we observe an inverse cascade towards the fundamental mode, with Petschek-type supersonic jets propagating at the external Alfvén speed from the X-point, and a fast reconnection rate at the predicted value {R}˜ (ln S)^{-1}.
A General Relativistic Magnetohydrodynamic Simulation of Jet Formation
NASA Technical Reports Server (NTRS)
Nishikawa, K.-I.; Richardson, G.; Koide, S.; Shibata, K.; Kudoh, T.; Hardee, P.; Fishman, G. J.
2005-01-01
We have performed a fully three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulation ofjet formation from a thin accretion disk around a Schwarzschild black hole with a free-falling corona. The initial simulation results show that a bipolar jet (velocity approx.0.3c) is created, as shown by previous two-dimensional axi- symmetric simulations with mirror symmetry at the equator. The three-dimensional simulation ran over 100 light crossing time units (T(sub s) = r(sub s)/c, where r(sub s = 2GM/c(sup 2), which is considerably longer than the previous simulations. We show that the jet is initially formed as predicted owing in part to magnetic pressure from the twisting of the initially uniform magnetic field and from gas pressure associated with shock formation in the region around r = 3r(sub s). At later times, the accretion disk becomes thick and the jet fades resulting in a wind that is ejected from the surface ofthe thickened (torus-like) disk. It should be noted that no streaming matter from a donor is included at the outer boundary in the simulation (an isolated black hole not binary black hole). The wind flows outward with a wider angle than the initial jet. The widening of the jet is consistent with the outward-moving torsional Alfven waves. This evolution of disk-jet coupling suggests that the jet fades with a thickened accretion disk because of the iack of streaming materiai from an accompanying star.
Mizuno, Yosuke; Lyubarsky, Yuri; Nishikawa, Ken-Ichi; Hardee, Philip E.
2012-09-20
We have investigated the influence of jet rotation and differential motion on the linear and nonlinear development of the current-driven (CD) kink instability of force-free helical magnetic equilibria via three-dimensional relativistic magnetohydrodynamic simulations. In this study, we follow the temporal development within a periodic computational box. Displacement of the initial helical magnetic field leads to the growth of the CD kink instability. We find that, in accordance with the linear stability theory, the development of the instability depends on the lateral distribution of the poloidal magnetic field. If the poloidal field significantly decreases outward from the axis, then the initial small perturbations grow strongly, and if multiple wavelengths are excited, then nonlinear interaction eventually disrupts the initial cylindrical configuration. When the profile of the poloidal field is shallow, the instability develops slowly and eventually saturates. We briefly discuss implications of our findings for Poynting-dominated jets.
Takamoto, Makoto; Inoue, Tsuyoshi
2011-07-10
We present a new numerical method of special relativistic resistive magnetohydrodynamics with scalar resistivity that can treat a range of phenomena, from non-relativistic to relativistic (shock, contact discontinuity, and Alfven wave). The present scheme calculates the numerical flux of fluid by using an approximate Riemann solver and electromagnetic field by using the method of characteristics. Since this scheme uses appropriate characteristic velocities, it is capable of accurately solving problems that cannot be approximated as ideal magnetohydrodynamics and whose characteristic velocity is much lower than the velocity of light. The numerical results show that our scheme can solve the above problems as well as nearly ideal MHD problems. Our new scheme is particularly well suited to systems with initially weak magnetic field and mixed phenomena of relativistic and non-relativistic velocity, for example magnetorotational instability in an accretion disk and super Alfvenic turbulence.
Properties of balanced and imbalanced relativistic alfvénic magnetohydrodynamic turbulence
NASA Astrophysics Data System (ADS)
Cho, Jungyeon
2014-09-01
When the magnetic field is so strong that the magnetic energy density is much larger than that of matter, magnetic perturbations propagate along the magnetic field lines, and the speed of propagation approaches the speed of light. As in the non-relativistic case, counter-traveling waves in this relativistic limit can interact and generate turbulence. In the present paper, we discuss the properties of the magnetohydrodynamic (MHD) turbulence generated by such interactions. First, we discuss the scaling relations for driven, balanced, relativistic MHD turbulence, in which the amplitudes of counter-traveling wave packets are similar. Second, we discuss the scaling relations of imbalanced relativistic MHD turbulence, in which the amplitudes of counter-traveling wave packets are different. Numerical simulations show that the scaling relations of relativistic MHD turbulence for both cases are very similar to those for their non-relativistic counterparts.
A General Relativistic Magnetohydrodynamics Simulation of Jet Formation with a State Transition
NASA Technical Reports Server (NTRS)
Nishikawa, K. I.; Richardson, G.; Koide, S.; Shibata, K.; Kudoh, T.; Hardee, P.; Fushman, G. J.
2004-01-01
We have performed the first fully three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulation of jet formation from a thin accretion disk around a Schwarzschild black hole with a free-falling corona. The initial simulation results show that a bipolar jet (velocity sim 0.3c) is created as shown by previous two-dimensional axisymmetric simulations with mirror symmetry at the equator. The 3-D simulation ran over one hundred light-crossing time units which is considerably longer than the previous simulations. We show that the jet is initially formed as predicted due in part to magnetic pressure from the twisting the initially uniform magnetic field and from gas pressure associated with shock formation. At later times, the accretion disk becomes thick and the jet fades resulting in a wind that is ejected from the surface of the thickened (torus-like) disk. It should be noted that no streaming matter from a donor is included at the outer boundary in the simulation (an isolated black hole not binary black hole). The wind flows outwards with a wider angle than the initial jet. The widening of the jet is consistent with the outward moving shock wave. This evolution of jet-disk coupling suggests that the low/hard state of the jet system may switch to the high/soft state with a wind, as the accretion rate diminishes.
NASA Astrophysics Data System (ADS)
Anantua, Richard; Roger Blandford, Jonathan McKinney and Alexander Tchekhovskoy
2016-01-01
We carry out the process of "observing" simulations of active galactic nuclei (AGN) with relativistic jets (hereafter called jet/accretion disk/black hole (JAB) systems) from ray tracing between image plane and source to convolving the resulting images with a point spread function. Images are generated at arbitrary observer angle relative to the black hole spin axis by implementing spatial and temporal interpolation of conserved magnetohydrodynamic flow quantities from a time series of output datablocks from fully general relativistic 3D simulations. We also describe the evolution of simulations of JAB systems' dynamical and kinematic variables, e.g., velocity shear and momentum density, respectively, and the variation of these variables with respect to observer polar and azimuthal angles. We produce, at frequencies from radio to optical, fixed observer time intensity and polarization maps using various plasma physics motivated prescriptions for the emissivity function of physical quantities from the simulation output, and analyze the corresponding light curves. Our hypothesis is that this approach reproduces observed features of JAB systems such as superluminal bulk flow projections and quasi-periodic oscillations in the light curves more closely than extant stylized analytical models, e.g., cannonball bulk flows. Moreover, our development of user-friendly, versatile C++ routines for processing images of state-of-the-art simulations of JAB systems may afford greater flexibility for observing a wide range of sources from high power BL-Lacs to low power quasars (possibly with the same simulation) without requiring years of observation using multiple telescopes. Advantages of observing simulations instead of observing astrophysical sources directly include: the absence of a diffraction limit, panoramic views of the same object and the ability to freely track features. Light travel time effects become significant for high Lorentz factor and small angles between
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.
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.
An Extended Magnetohydrodynamics Model for Relativistic Weakly Collisional Plasmas
NASA Astrophysics Data System (ADS)
Chandra, Mani; Gammie, Charles F.; Foucart, Francois; Quataert, Eliot
2015-09-01
Black holes that accrete far below the Eddington limit are believed to accrete through a geometrically thick, optically thin, rotationally supported plasma that we will refer to as a radiatively inefficient accretion flow (RIAF). RIAFs are typically collisionless in the sense that the Coulomb mean free path is large compared to {GM}/{c}2, and relativistically hot near the event horizon. In this paper we develop a phenomenological model for the plasma in RIAFs, motivated by the application to sources such as Sgr A* and M87. The model is derived using Israel-Stewart theory, which considers deviations up to second order from thermal equilibrium, but modified for a magnetized plasma. This leads to thermal conduction along magnetic field lines and a difference in pressure, parallel and perpendicular to the field lines (which is equivalent to anisotropic viscosity). In the non-relativistic limit, our model reduces to the widely used Braginskii theory of magnetized, weakly collisional plasmas. We compare our model to the existing literature on dissipative relativistic fluids, describe the linear theory of the plasma, and elucidate the physical meaning of the free parameters in the model. We also describe limits of the model when the conduction is saturated and when the viscosity implies a large pressure anisotropy. In future work, the formalism developed in this paper will be used in numerical models of RIAFs to assess the importance of non-ideal processes for the dynamics and radiative properties of slowly accreting black holes.
Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization
NASA Astrophysics Data System (ADS)
Pu, Shi; Roy, Victor; Rezzolla, Luciano; Rischke, Dirk H.
2016-04-01
We study the one-dimensional, longitudinally boost-invariant motion of an ideal fluid with infinite conductivity in the presence of a transverse magnetic field, i.e., in the ideal transverse magnetohydrodynamical limit. In an extension of our previous work Roy et al., [Phys. Lett. B 750, 45 (2015)], we consider the fluid to have a nonzero magnetization. First, we assume a constant magnetic susceptibility χm and consider an ultrarelativistic ideal gas equation of state. For a paramagnetic fluid (i.e., with χm>0 ), the decay of the energy density slows down since the fluid gains energy from the magnetic field. For a diamagnetic fluid (i.e., with χm<0 ), the energy density decays faster because it feeds energy into the magnetic field. Furthermore, when the magnetic field is taken to be external and to decay in proper time τ with a power law ˜τ-a, two distinct solutions can be found depending on the values of a and χm. Finally, we also solve the ideal magnetohydrodynamical equations for one-dimensional Bjorken flow with a temperature-dependent magnetic susceptibility and a realistic equation of state given by lattice-QCD data. We find that the temperature and energy density decay more slowly because of the nonvanishing magnetization. For values of the magnetic field typical for heavy-ion collisions, this effect is, however, rather small. It is only for magnetic fields about an order of magnitude larger than expected for heavy-ion collisions that the system is substantially reheated and the lifetime of the quark phase might be extended.
Beyond ideal magnetohydrodynamics: resistive, reactive and relativistic plasmas
NASA Astrophysics Data System (ADS)
Andersson, N.; Dionysopoulou, K.; Hawke, I.; Comer, G. L.
2017-06-01
We develop a new framework for the modelling of charged fluid dynamics in general relativity. The model, which builds on a recently developed variational multi-fluid framework for dissipative fluids, accounts for relevant effects like the inertia of both charge currents and heat and, for mature systems, the decoupling of superfluid components. We discuss how the model compares to standard relativistic magnetohydronamics and consider the connection between the fluid dynamics, the microphysics and the underlying equation of state. As illustrations of the formalism, we consider three distinct two-fluid models describing (i) an Ohm’s law for resistive charged flows, (ii) a relativistic heat equation, and (iii) an equation representing the momentum of a decoupled superfluid component. As a more complex example, we also formulate a three-fluid model which demonstrates the thermo-electric effect. The new framework allows us to model neutron stars (and related systems) at a hierarchy of increasingly complex levels, and should enable us to make progress on a range of exciting problems in astrophysics and cosmology.
Anton, Luis; MartI, Jose M; Ibanez, Jose M; Aloy, Miguel A.; Mimica, Petar; Miralles, Juan A.
2010-05-01
We obtain renormalized sets of right and left eigenvectors of the flux vector Jacobians of the relativistic MHD equations, which are regular and span a complete basis in any physical state including degenerate ones. The renormalization procedure relies on the characterization of the degeneracy types in terms of the normal and tangential components of the magnetic field to the wave front in the fluid rest frame. Proper expressions of the renormalized eigenvectors in conserved variables are obtained through the corresponding matrix transformations. Our work completes previous analysis that present different sets of right eigenvectors for non-degenerate and degenerate states, and can be seen as a relativistic generalization of earlier work performed in classical MHD. Based on the full wave decomposition (FWD) provided by the renormalized set of eigenvectors in conserved variables, we have also developed a linearized (Roe-type) Riemann solver. Extensive testing against one- and two-dimensional standard numerical problems allows us to conclude that our solver is very robust. When compared with a family of simpler solvers that avoid the knowledge of the full characteristic structure of the equations in the computation of the numerical fluxes, our solver turns out to be less diffusive than HLL and HLLC, and comparable in accuracy to the HLLD solver. The amount of operations needed by the FWD solver makes it less efficient computationally than those of the HLL family in one-dimensional problems. However, its relative efficiency increases in multidimensional simulations.
NASA Astrophysics Data System (ADS)
Antón, Luis; Miralles, Juan A.; Martí, José M.; Ibáñez, José M.; Aloy, Miguel A.; Mimica, Petar
2010-05-01
We obtain renormalized sets of right and left eigenvectors of the flux vector Jacobians of the relativistic MHD equations, which are regular and span a complete basis in any physical state including degenerate ones. The renormalization procedure relies on the characterization of the degeneracy types in terms of the normal and tangential components of the magnetic field to the wave front in the fluid rest frame. Proper expressions of the renormalized eigenvectors in conserved variables are obtained through the corresponding matrix transformations. Our work completes previous analysis that present different sets of right eigenvectors for non-degenerate and degenerate states, and can be seen as a relativistic generalization of earlier work performed in classical MHD. Based on the full wave decomposition (FWD) provided by the renormalized set of eigenvectors in conserved variables, we have also developed a linearized (Roe-type) Riemann solver. Extensive testing against one- and two-dimensional standard numerical problems allows us to conclude that our solver is very robust. When compared with a family of simpler solvers that avoid the knowledge of the full characteristic structure of the equations in the computation of the numerical fluxes, our solver turns out to be less diffusive than HLL and HLLC, and comparable in accuracy to the HLLD solver. The amount of operations needed by the FWD solver makes it less efficient computationally than those of the HLL family in one-dimensional problems. However, its relative efficiency increases in multidimensional simulations.
NASA Astrophysics Data System (ADS)
Ma, Haitao; Zhai, Xiaoping; Yan, Wei; Li, Yongsheng
2017-02-01
In this paper, we study the global well posedness of the 3D incompressible magnetohydrodynamic system with horizontal dissipation and horizontal magnetic diffusion in the scaling invariant Besov-Sobolev-type spaces. We first get a unique global solution to this system with small initial data by the classical Friedrich's regularization method. Then using a weighted Chemin-Lerner-type norm, we prove the system also can generate a global solution if the horizontal components of the initial data are small enough compared to the vertical components. In particular, our results imply the global large solutions with highly oscillating initial data.
On the Global Regularity for the 3D Magnetohydrodynamics Equations Involving Partial Components
NASA Astrophysics Data System (ADS)
Qian, Chenyin
2017-01-01
In this paper, we study the regularity criteria of the three-dimensional magnetohydrodynamics system in terms of some components of the velocity field and the magnetic field. With a decomposition of the four nonlinear terms of the system, this result gives an improvement of some corresponding previous works (Yamazaki in J Math Fluid Mech 16: 551-570, 2014; Jia and Zhou in Nonlinear Anal Real World Appl 13: 410-418, 2012).
General relativistic magnetohydrodynamical simulations of the jet in M 87
NASA Astrophysics Data System (ADS)
Mościbrodzka, Monika; Falcke, Heino; Shiokawa, Hotaka
2016-02-01
Context. The connection between black hole, accretion disk, and radio jet can be constrained best by fitting models to observations of nearby low-luminosity galactic nuclei, in particular the well-studied sources Sgr A* and M 87. There has been considerable progress in modeling the central engine of active galactic nuclei by an accreting supermassive black hole coupled to a relativistic plasma jet. However, can a single model be applied to a range of black hole masses and accretion rates? Aims: Here we want to compare the latest three-dimensional numerical model, originally developed for Sgr A* in the center of the Milky Way, to radio observations of the much more powerful and more massive black hole in M 87. Methods: We postprocess three-dimensional GRMHD models of a jet-producing radiatively inefficient accretion flow around a spinning black hole using relativistic radiative transfer and ray-tracing to produce model spectra and images. As a key new ingredient in these models, we allow the proton-electron coupling in these simulations depend on the magnetic properties of the plasma. Results: We find that the radio emission in M 87 is described well by a combination of a two-temperature accretion flow and a hot single-temperature jet. Most of the radio emission in our simulations comes from the jet sheath. The model fits the basic observed characteristics of the M 87 radio core: it is "edge-brightened", starts subluminally, has a flat spectrum, and increases in size with wavelength. The best fit model has a mass-accretion rate of Ṁ ~ 9 × 10-3M⊙ yr-1 and a total jet power of Pj ~ 1043 erg s-1. Emission at λ = 1.3 mm is produced by the counter-jet close to the event horizon. Its characteristic crescent shape surrounding the black hole shadow could be resolved by future millimeter-wave VLBI experiments. Conclusions: The model was successfully derived from one for the supermassive black hole in the center of the Milky Way by appropriately scaling mass and
Koide, Shinji
2010-01-10
To study phenomena of plasmas around rotating black holes, we have derived a set of 3+1 formalism of generalized general relativistic magnetohydrodynamic (GRMHD) equations. In particular, we investigated general relativistic phenomena with respect to the Ohm's law. We confirmed the electromotive force due to the gravitation, centrifugal force, and frame-dragging effect in plasmas near the black holes. These effects are significant only in the local small-scale phenomena compared to the scale of astrophysical objects. We discuss the possibility of magnetic reconnection, which is triggered by one of these effects in a small-scale region and influences the plasmas globally. We clarify the conditions of applicability of the generalized GRMHD, standard resistive GRMHD, and ideal GRMHD for plasmas in black hole magnetospheres.
RAISHIN: A High-Resolution Three-Dimensional General Relativistic Magnetohydrodynamics Code
NASA Technical Reports Server (NTRS)
Mizuno, Yosuke; Nishikawa, Ken-Ichi; Koide, Shinji; Hardee, Philip; Fishman, Gerald J.
2006-01-01
We have developed a new three-dimensional general relativistic magnetohydrodynamic (GRMHD) code, RAISHIN, using a conservative, high resolution shock-capturing scheme. The numerical fluxes are calculated using the Harten, Lax, & van Leer (HLL) approximate Riemann solver scheme. The flux-interpolated, constrained transport scheme is used to maintain a divergence-free magnetic field. In order to examine the numerical accuracy and the numerical efficiency, the code uses four different reconstruction methods: piecewise linear methods with Minmod and MC slope-limiter function, convex essentially non-oscillatory (CENO) method, and piecewise parabolic method (PPM) using multistep TVD Runge-Kutta time advance methods with second and third-order time accuracy. We describe code performance on an extensive set of test problems in both special and general relativity. Our new GRMHD code has proven to be accurate in second order and has successfully passed with all tests performed, including highly relativistic and magnetized cases in both special and general relativity.
NASA Astrophysics Data System (ADS)
Shiokawa, Hotaka
The goal of the series of studies in this thesis is to understand the black hole accretion process and predict its observational properties. The highly non-linear process involves a turbulent magnetized plasma in a general relativistic regime, thus making it hard to study analytically. We use numerical simulations, specifically general relativistic magnetohydrodynamics (GRMHD), to construct a realistic dynamical and radiation model of accretion disks. Our simulations are for black holes in low luminous regimes that probably possesses a hot and thick accretion disk. Flows in this regime are called radiatively inefficient accretion flows (RIAF). The most plausible mechanism for transporting angular momentum is turbulence induced by magnetorotational instability (MRI). The RIAF model has been used to model the supermassive black hole at the center of our Milky Way galaxy, Sagittarius A* (Sgr A*). Owing to its proximity, rich observational data of Sgr A* is available to compare with the simulation results. We focus mainly on four topics. First, we analyse numerical convergence of 3D GRMHD global disk simulations. Convergence is one of the essential factors in deciding quantitative outcomes of the simulations. We analyzed dimensionless shell-averaged quantities such as plasma beta, the azimuthal correlation length (angle) of fluid variables, and spectra of the source for four different resolutions. We found that all the variables converged with the highest resolution (384x384x256 in radial, poloidal, and azimuthal directions) except the magnetic field correlation length. It probably requires another factor of 2 in resolution to achieve convergence. Second, we studied the effect of equation of state on dynamics of GRMHD simulation and radiative transfer. Temperature of RIAF gas is high, and all the electrons are relativistic, but not the ions. In addition, the dynamical time scale of the accretion disk is shorter than the collisional time scale of electrons and ions
DISCO: A 3D Moving-mesh Magnetohydrodynamics Code Designed for the Study of Astrophysical Disks
NASA Astrophysics Data System (ADS)
Duffell, Paul C.
2016-09-01
This work presents the publicly available moving-mesh magnetohydrodynamics (MHD) code DISCO. DISCO is efficient and accurate at evolving orbital fluid motion in two and three dimensions, especially at high Mach numbers. DISCO employs a moving-mesh approach utilizing a dynamic cylindrical mesh that can shear azimuthally to follow the orbital motion of the gas. The moving mesh removes diffusive advection errors and allows for longer time-steps than a static grid. MHD is implemented in DISCO using an HLLD Riemann solver and a novel constrained transport (CT) scheme that is compatible with the mesh motion. DISCO is tested against a wide variety of problems, which are designed to test its stability, accuracy, and scalability. In addition, several MHD tests are performed which demonstrate the accuracy and stability of the new CT approach, including two tests of the magneto-rotational instability, one testing the linear growth rate and the other following the instability into the fully turbulent regime.
Particle energization in 3D magnetic reconnection of relativistic pair plasmas
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.
NASA Astrophysics Data System (ADS)
Kawazura, Yohei; Miloshevich, George; Morrison, Philip J.
2017-02-01
Two types of Eulerian action principles for relativistic extended magnetohydrodynamics (MHD) are formulated. With the first, the action is extremized under the constraints of density, entropy, and Lagrangian label conservation, which leads to a Clebsch representation for a generalized momentum and a generalized vector potential. The second action arises upon transformation to physical field variables, giving rise to a covariant bracket action principle, i.e., a variational principle in which constrained variations are generated by a degenerate Poisson bracket. Upon taking appropriate limits, the action principles lead to relativistic Hall MHD and well-known relativistic ideal MHD. For the first time, the Hamiltonian formulation of relativistic Hall MHD with electron thermal inertia (akin to Comisso et al., Phys. Rev. Lett. 113, 045001 (2014) for the electron-positron plasma) is introduced. This thermal inertia effect allows for violation of the frozen-in magnetic flux condition in marked contrast to nonrelativistic Hall MHD that does satisfy the frozen-in condition. We also find the violation of the frozen-in condition is accompanied by freezing-in of an alternative flux determined by a generalized vector potential. Finally, we derive a more general 3 + 1 Poisson bracket for nonrelativistic extended MHD, one that does not assume smallness of the electron ion mass ratio.
NASA Astrophysics Data System (ADS)
Zanotti, Olindo; Dumbser, Michael
2015-03-01
We present a high order one-step ADER-WENO finite volume scheme with space-time adaptive mesh refinement (AMR) for the solution of the special relativistic hydrodynamic and magnetohydrodynamic equations. By adopting a local discontinuous Galerkin predictor method, a high order one-step time discretization is obtained, with no need for Runge-Kutta sub-steps. This turns out to be particularly advantageous in combination with space-time adaptive mesh refinement, which has been implemented following a "cell-by-cell" approach. As in existing second order AMR methods, also the present higher order AMR algorithm features time-accurate local time stepping (LTS), where grids on different spatial refinement levels are allowed to use different time steps. We also compare two different Riemann solvers for the computation of the numerical fluxes at the cell interfaces. The new scheme has been validated over a sample of numerical test problems in one, two and three spatial dimensions, exploring its ability in resolving the propagation of relativistic hydrodynamical and magnetohydrodynamical waves in different physical regimes. The astrophysical relevance of the new code for the study of the Richtmyer-Meshkov instability is briefly discussed in view of future applications.
The Beale-Kato-Majda Criterion for the 3D Magneto-Hydrodynamics Equations
NASA Astrophysics Data System (ADS)
Chen, Qionglei; Miao, Changxing; Zhang, Zhifei
2007-11-01
We study the blow-up criterion of smooth solutions to the 3D MHD equations. By means of the Littlewood-Paley decomposition, we prove a Beale-Kato-Majda type blow-up criterion of smooth solutions via the vorticity of velocity only, namely sup_{jinmathbb{Z}}int_0^T\\|Δ_j(nabla× u)\\|_infty dt, where Δ j is the frequency localization operator in the Littlewood-Paley decomposition.
VizieR Online Data Catalog: Solar wind 3D magnetohydrodynamic simulation (Chhiber+, 2017)
NASA Astrophysics Data System (ADS)
Chhiber, R.; Subedi, P.; Usmanov, A. V.; Matthaeus, W. H.; Ruffolo, D.; Goldstein, M. L.; Parashar, T. N.
2017-08-01
We use a three-dimensional magnetohydrodynamic simulation of the solar wind to calculate cosmic-ray diffusion coefficients throughout the inner heliosphere (2Rȯ-3au). The simulation resolves large-scale solar wind flow, which is coupled to small-scale fluctuations through a turbulence model. Simulation results specify background solar wind fields and turbulence parameters, which are used to compute diffusion coefficients and study their behavior in the inner heliosphere. The parallel mean free path (mfp) is evaluated using quasi-linear theory, while the perpendicular mfp is determined from nonlinear guiding center theory with the random ballistic interpretation. Several runs examine varying turbulent energy and different solar source dipole tilts. We find that for most of the inner heliosphere, the radial mfp is dominated by diffusion parallel to the mean magnetic field; the parallel mfp remains at least an order of magnitude larger than the perpendicular mfp, except in the heliospheric current sheet, where the perpendicular mfp may be a few times larger than the parallel mfp. In the ecliptic region, the perpendicular mfp may influence the radial mfp at heliocentric distances larger than 1.5au; our estimations of the parallel mfp in the ecliptic region at 1 au agree well with the Palmer "consensus" range of 0.08-0.3au. Solar activity increases perpendicular diffusion and reduces parallel diffusion. The parallel mfp mostly varies with rigidity (P) as P.33, and the perpendicular mfp is weakly dependent on P. The mfps are weakly influenced by the choice of long-wavelength power spectra. (2 data files).
Performance improvement study of a relativistic magnetron using MAGIC-3D
Maurya, S.; Singh, V.V.P.; Jain, R.K.
2011-07-01
A three dimensional particle-in-cell (PlC) code, MAGIC3D, is used to examine the performance improvement in a relativistic magnetron by perturbing technique. Asymmetrical metal rods of different length have been used to perturb the magnetic field in the annular sector of the resonant system. Enhancement up to 45% in the radiated output power has been obtained in the perturbed magnetic field case over the unperturbed one. It has also been found in the simulation that oscillation start up time is reduced by 16 %, and the amplitude of the nearest competing mode goes down 9dB compared to unperturbed case. Perturbed magnetic field also reduces the end caps current improving the efficiency. (author)
Performance improvement study of a relativistic magnetron using MAGIC-3D
Maurya, S.; Singh, V.V.P.; Jain, P.K.
2011-07-01
A three dimensional particle-in-cell (PlC) code, MAGIC3D, is used to examine the performance improvement in a relativistic magnetron by perturbing technique. Asymmetrical metal rods of different length have been used to perturb the magnetic field in the annular sector of the resonant system. Enhancement up to 45% in the radiated output power has been obtained in the perturbed magnetic field case over the unperturbed one. It has also been found in the simulation that oscillation start up time is reduced by 16 %, and the amplitude of the nearest competing mode goes down 9dB compared to unperturbed case. Perturbed magnetic field also reduces the end caps current improving the efficiency. (author)
Maroof, R.; Ali, S.; Mushtaq, A.; Qamar, A.
2015-11-15
Linear properties of high and low frequency waves are studied in an electron-positron-ion (e-p-i) dense plasma with spin and relativity effects. In a low frequency regime, the magnetohydrodynamic (MHD) waves, namely, the magnetoacoustic and Alfven waves are presented in a magnetized plasma, in which the inertial ions are taken as spinless and non-degenerate, whereas the electrons and positrons are treated quantum mechanically due to their smaller mass. Quantum corrections associated with the spin magnetization and density correlations for electrons and positrons are re-considered and a generalized dispersion relation for the low frequency MHD waves is derived to account for relativistic degeneracy effects. On the basis of angles of propagation, the dispersion relations of different modes are discussed analytically in a degenerate relativistic plasma. Numerical results reveal that electron and positron relativistic degeneracy effects significantly modify the dispersive properties of MHD waves. Our present analysis should be useful for understanding the collective interactions in dense astrophysical compact objects, like, the white dwarfs and in atmosphere of neutron stars.
A high-order kinetic flux-splitting method for the relativistic magnetohydrodynamics
Qamar, Shamsul . E-mail: shamsul.qamar@mathematik.uni-magdeburg.de; Warnecke, Gerald . E-mail: gerald.warnecke@mathematik.uni-magdeburg.de
2005-05-01
In this paper we extend the special relativistic hydrodynamic (SRHD) equations [L.D. Landau, E.M. Lifshitz, Fluid Mechanics, Pergamon, New York, 1987] and as a limiting case the ultra-relativistic hydrodynamic equations [M. Kunik, S. Qamar, G. Warnecke, J. Comput. Phys. 187 (2003) 572-596] to the special relativistic magnetohydrodynamics (SRMHD). We derive a flux splitting method based on gas-kinetic theory in order to solve these equations in one space dimension. The scheme is based on the direct splitting of macroscopic flux functions with consideration of particle transport. At the same time, particle 'collisions' are implemented in the free transport process to reduce numerical dissipation. To achieve high-order accuracy we use a MUSCL-type initial reconstruction and Runge-Kutta time stepping method. For the direct comparison of the numerical results, we also solve the SRMHD equations with the well-developed second-order central schemes. The 1D computations reported in this paper have comparable accuracy to the already published results. The results verify the desired accuracy, high resolution, and robustness of the kinetic flux splitting method and central schemes.
Zhang, Haocheng; Deng, Wei; Li, Hui; ...
2016-01-20
The optical radiation and polarization signatures in blazars are known to be highly variable during flaring activities. It is frequently argued that shocks are the main driver of the flaring events. However, the spectral variability modelings generally lack detailed considerations of the self-consistent magnetic field evolution modeling; thus, so far the associated optical polarization signatures are poorly understood. We present the first simultaneous modeling of the optical radiation and polarization signatures based on 3D magnetohydrodynamic simulations of relativistic shocks in the blazar emission environment, with the simplest physical assumptions. By comparing the results with observations, we find that shocks inmore » a weakly magnetized environment will largely lead to significant changes in the optical polarization signatures, which are seldom seen in observations. Hence an emission region with relatively strong magnetization is preferred. In such an environment, slow shocks may produce minor flares with either erratic polarization fluctuations or considerable polarization variations, depending on the parameters; fast shocks can produce major flares with smooth polarization angle rotations. In addition, the magnetic fields in both cases are observed to actively revert to the original topology after the shocks. In addition, all these features are consistent with observations. Future observations of the radiation and polarization signatures will further constrain the flaring mechanism and the blazar emission environment.« less
Zhang, Haocheng; Deng, Wei; Li, Hui; Bottcher, Markus
2016-01-20
The optical radiation and polarization signatures in blazars are known to be highly variable during flaring activities. It is frequently argued that shocks are the main driver of the flaring events. However, the spectral variability modelings generally lack detailed considerations of the self-consistent magnetic field evolution modeling; thus, so far the associated optical polarization signatures are poorly understood. We present the first simultaneous modeling of the optical radiation and polarization signatures based on 3D magnetohydrodynamic simulations of relativistic shocks in the blazar emission environment, with the simplest physical assumptions. By comparing the results with observations, we find that shocks in a weakly magnetized environment will largely lead to significant changes in the optical polarization signatures, which are seldom seen in observations. Hence an emission region with relatively strong magnetization is preferred. In such an environment, slow shocks may produce minor flares with either erratic polarization fluctuations or considerable polarization variations, depending on the parameters; fast shocks can produce major flares with smooth polarization angle rotations. In addition, the magnetic fields in both cases are observed to actively revert to the original topology after the shocks. In addition, all these features are consistent with observations. Future observations of the radiation and polarization signatures will further constrain the flaring mechanism and the blazar emission environment.
Zhang, Haocheng; Deng, Wei; Li, Hui; Böttcher, Markus
2016-01-20
The optical radiation and polarization signatures in blazars are known to be highly variable during flaring activities. It is frequently argued that shocks are the main driver of the flaring events. However, the spectral variability modelings generally lack detailed considerations of the self-consistent magnetic field evolution modeling; thus, so far the associated optical polarization signatures are poorly understood. We present the first simultaneous modeling of the optical radiation and polarization signatures based on 3D magnetohydrodynamic simulations of relativistic shocks in the blazar emission environment, with the simplest physical assumptions. By comparing the results with observations, we find that shocks in a weakly magnetized environment will largely lead to significant changes in the optical polarization signatures, which are seldom seen in observations. Hence an emission region with relatively strong magnetization is preferred. In such an environment, slow shocks may produce minor flares with either erratic polarization fluctuations or considerable polarization variations, depending on the parameters; fast shocks can produce major flares with smooth polarization angle rotations. In addition, the magnetic fields in both cases are observed to actively revert to the original topology after the shocks. All these features are consistent with observations. Future observations of the radiation and polarization signatures will further constrain the flaring mechanism and the blazar emission environment.
NASA Astrophysics Data System (ADS)
Shiokawa, Hotaka; Gammie, C. F.; Dolence, J.; Noble, S. C.
2013-01-01
We perform global General Relativistic Magnetohydrodynamics (GRMHD) simulations of non-radiative, magnetized disks that are initially tilted with respect to the black hole's spin axis. We run the simulations with different size and tilt angle of the tori for 2 different resolutions. We also perform radiative transfer using Monte Carlo based code that includes synchrotron emission, absorption and Compton scattering to obtain spectral energy distribution and light curves. Similar work was done by Fragile et al. (2007) and Dexter & Fragile (2012) to model the super massive black hole SgrA* with tilted accretion disks. We compare our results of fully conservative hydrodynamic code and spectra that include X-ray, with their results.
3D Radiation Nonideal Magnetohydrodynamical Simulations of the Inner Rim in Protoplanetary Disks
NASA Astrophysics Data System (ADS)
Flock, M.; Fromang, S.; Turner, N. J.; Benisty, M.
2017-02-01
Many planets orbit within 1 au of their stars, raising questions about their origins. Particularly puzzling are the planets found near the silicate sublimation front. We investigate conditions near the front in the protostellar disk around a young intermediate-mass star, using the first global 3D radiation nonideal MHD simulations in this context. We treat the starlight heating; the silicate grains’ sublimation and deposition at the local, time-varying temperature and density; temperature-dependent ohmic dissipation; and various initial magnetic fields. The results show magnetorotational turbulence around the sublimation front at 0.5 au. The disk interior to 0.8 au is turbulent, with velocities exceeding 10% of the sound speed. Beyond 0.8 au is the dead zone, cooler than 1000 K and with turbulence orders of magnitude weaker. A local pressure maximum just inside the dead zone concentrates solid particles, favoring their growth. Over many orbits, a vortex develops at the dead zone’s inner edge, increasing the disk’s thickness locally by around 10%. We synthetically observe the results using Monte Carlo transfer calculations, finding that the sublimation front is near-infrared bright. The models with net vertical magnetic fields develop extended, magnetically supported atmospheres that reprocess extra starlight, raising the near-infrared flux 20%. The vortex throws a nonaxisymmetric shadow on the outer disk. At wavelengths > 2 μ {{m}}, the flux varies several percent on monthly timescales. The variations are more regular when the vortex is present. The vortex is directly visible as an arc at ultraviolet through near-infrared wavelengths, given sub-au spatial resolution.
NASA Astrophysics Data System (ADS)
Takamoto, Makoto; Lazarian, Alexandre
2016-11-01
In this Letter, we report compressible mode effects on relativistic magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using three-dimensional numerical simulations. We decomposed fluctuations in the turbulence into 3 MHD modes (fast, slow, and Alfvén) following the procedure of mode decomposition in Cho & Lazarian, and analyzed their energy spectra and structure functions separately. We also analyzed the ratio of compressible mode to Alfvén mode energy with respect to its Mach number. We found the ratio of compressible mode increases not only with the Alfvén Mach number, but also with the background magnetization, which indicates a strong coupling between the fast and Alfvén modes. It also signifies the appearance of a new regime of RMHD turbulence in Poynting-dominated plasmas where the fast and Alfvén modes are strongly coupled and, unlike the non-relativistic MHD regime, cannot be treated separately. This finding will affect particle acceleration efficiency obtained by assuming Alfvénic critical-balance turbulence and can change the resulting photon spectra emitted by non-thermal electrons.
NASA Astrophysics Data System (ADS)
Matsumoto, Jin; Masada, Youhei; Asano, Eiji; Shibata, Kazunari
2011-06-01
The nonlinear dynamics of the outflow driven by magnetic explosion on the surface of compact object is investigated through special relativistic magnetohydrodynamic simulations. We adopt, as an initial equilibrium state, a spherical stellar object embedded in the hydrostatic plasma which has a density ρ(r) ~ r-α and is threaded by a dipole magnetic field. The injection of magnetic energy at the surface of compact star breaks the dynamical equilibrium and triggers two-component outflow. At the early evolutionary stage, the magnetic pressure increases rapidly in time around the stellar surface, initiating a magnetically driven outflow. Then it excites a strong forward shock, shock driven outflow. The expansion velocity of the magnetically driven outflow is characterized by the Alfvén velocity on the stellar surface, and follows a simple scaling relation υmag ~ υA1/2. When the initial density profile declines steeply with radius, the strong shock is accelerated self-similarly to relativistic velocity ahead of the magnetically driven component. We find that the evolution of the strong forward shock can be described by a self-similar relation Γsh ~ rsh, where Γsh is the Lorentz factor of the plasma measured at the shock surface rsh. It should be stressed that the pure hydrodynamic process is responsible for the acceleration of the shock driven outflow. Our two-component outflow model, which is the natural outcome of the magnetic explosion, would deepen the understanding of the magnetic active phenomena on various magnetized stellar objects.
Runge-Kutta discontinuous Galerkin methods for the special relativistic magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Zhao, Jian; Tang, Huazhong
2017-08-01
This paper develops PK-based non-central and central Runge-Kutta discontinuous Galerkin (DG) methods with WENO limiter for the one- and two-dimensional special relativistic magnetohydrodynamical (RMHD) equations, K = 1 , 2 , 3. The non-central DG methods are locally divergence-free, while the central DG are ;exactly; divergence-free but have to find two approximate solutions defined on mutually dual meshes. The adaptive WENO limiter first identifies the ;troubled; cells by using a modified TVB minmod function, and then uses the WENO technique and the cell average values of the DG solutions in the neighboring cells as well as the original cell averages of the ;troubled; cells to locally reconstruct a new polynomial of degree (2 K + 1) inside the ;troubled; cells instead of the DG solution. The WENO limiting procedure does not destroy the locally or ;exactly; divergence-free property of magnetic field and is only employed for finite ;troubled; cells so that the computational cost can be as little as possible. Several test problems in one and two dimensions are solved by using our non-central and central Runge-Kutta DG methods with WENO limiter. The numerical results demonstrate that our methods are stable, accurate, and robust in resolving complex wave structures.
NASA Astrophysics Data System (ADS)
Castro, Manuel J.; Gallardo, José M.; Marquina, Antonio
2017-10-01
We present recent advances in PVM (Polynomial Viscosity Matrix) methods based on internal approximations to the absolute value function, and compare them with Chebyshev-based PVM solvers. These solvers only require a bound on the maximum wave speed, so no spectral decomposition is needed. Another important feature of the proposed methods is that they are suitable to be written in Jacobian-free form, in which only evaluations of the physical flux are used. This is particularly interesting when considering systems for which the Jacobians involve complex expressions, e.g., the relativistic magnetohydrodynamics (RMHD) equations. On the other hand, the proposed Jacobian-free solvers have also been extended to the case of approximate DOT (Dumbser-Osher-Toro) methods, which can be regarded as simple and efficient approximations to the classical Osher-Solomon method, sharing most of it interesting features and being applicable to general hyperbolic systems. To test the properties of our schemes a number of numerical experiments involving the RMHD equations are presented, both in one and two dimensions. The obtained results are in good agreement with those found in the literature and show that our schemes are robust and accurate, running stable under a satisfactory time step restriction. It is worth emphasizing that, although this work focuses on RMHD, the proposed schemes are suitable to be applied to general hyperbolic systems.
Zhang, Haocheng; Li, Hui; Guo, Fan; ...
2017-01-23
Kink instabilities are likely to occur in the current-carrying magnetized plasma jets. Recent observations of the blazar radiation and polarization signatures suggest that the blazar emission region may be considerably magnetized. While the kink instability has been studied with first-principle magnetohydrodynamic (MHD) simulations, the corresponding time-dependent radiation and polarization signatures have not been investigated. Here, in this paper, we perform comprehensive polarization-dependent radiation modeling of the kink instability in the blazar emission region based on relativistic MHD (RMHD) simulations. We find that the kink instability may give rise to strong flares with polarization angle (PA) swings or weak flares withmore » polarization fluctuations, depending on the initial magnetic topology and magnetization. These findings are consistent with observations. In addition, compared with the shock model, the kink model generates polarization signatures that are in better agreement with the general polarization observations. Therefore, we suggest that kink instabilities may widely exist in the jet environment and provide an efficient way to convert the magnetic energy and produce multiwavelength flares and polarization variations.« less
NASA Astrophysics Data System (ADS)
Endrizzi, Andrea; Ciolfi, Riccardo; Giacomazzo, Bruno; Kastaun, Wolfgang; Kawamura, Takumu
2016-03-01
We present new results of fully general relativistic magnetohydrodynamic (GRMHD) simulations of binary neutron star (BNS) mergers performed with the Whisky code. All the models use a piecewise polytropic approximation of the APR4 equation of state (EOS) for cold matter, together with a ''hybrid'' part to incorporate thermal effects during the evolution. We consider both equal and unequal-mass models, with total masses such that either a supramassive NS or a black hole (BH) is formed after merger. Each model is evolved with and without a magnetic field initially confined to the stellar interior. We present the different gravitational wave (GW) signals as well as a detailed description of the matter dynamics (magnetic field evolution, ejected mass, post-merger remnant properties, disk mass). Our new simulations provide a further important step in the understanding of these GW sources and their possible connection with the engine of short gamma-ray bursts (both in the ``standard'' and in the ``time-reversal'' scenarios) and with other electromagnetic counterparts.
NASA Astrophysics Data System (ADS)
Endrizzi, A.; Ciolfi, R.; Giacomazzo, B.; Kastaun, W.; Kawamura, T.
2016-08-01
We present new results of fully general relativistic magnetohydrodynamic simulations of binary neutron star (BNS) mergers performed with the Whisky code. All the models use a piecewise polytropic approximation of the APR4 equation of state for cold matter, together with a ‘hybrid’ part to incorporate thermal effects during the evolution. We consider both equal and unequal-mass models, with total masses such that either a supramassive NS or a black hole is formed after merger. Each model is evolved with and without a magnetic field initially confined to the stellar interior. We present the different gravitational wave (GW) signals as well as a detailed description of the matter dynamics (magnetic field evolution, ejected mass, post-merger remnant/disk properties). Our simulations provide new insights into BNS mergers, the associated GW emission and the possible connection with the engine of short gamma-ray bursts (both in the ‘standard’ and in the ‘time-reversal’ scenarios) and other electromagnetic counterparts.
NASA Astrophysics Data System (ADS)
Zhang, Haocheng; Li, Hui; Guo, Fan; Taylor, Greg
2017-02-01
Kink instabilities are likely to occur in the current-carrying magnetized plasma jets. Recent observations of the blazar radiation and polarization signatures suggest that the blazar emission region may be considerably magnetized. While the kink instability has been studied with first-principle magnetohydrodynamic (MHD) simulations, the corresponding time-dependent radiation and polarization signatures have not been investigated. In this paper, we perform comprehensive polarization-dependent radiation modeling of the kink instability in the blazar emission region based on relativistic MHD (RMHD) simulations. We find that the kink instability may give rise to strong flares with polarization angle (PA) swings or weak flares with polarization fluctuations, depending on the initial magnetic topology and magnetization. These findings are consistent with observations. Compared with the shock model, the kink model generates polarization signatures that are in better agreement with the general polarization observations. Therefore, we suggest that kink instabilities may widely exist in the jet environment and provide an efficient way to convert the magnetic energy and produce multiwavelength flares and polarization variations.
McKinney, Jonathan C.; Tchekhovskoy, Alexander; Blandford, Roger D.
2012-04-26
Black hole (BH) accretion flows and jets are qualitatively affected by the presence of ordered magnetic fields. We study fully three-dimensional global general relativistic magnetohydrodynamic (MHD) simulations of radially extended and thick (height H to cylindrical radius R ratio of |H/R| {approx} 0.2-1) accretion flows around BHs with various dimensionless spins (a/M, with BH mass M) and with initially toroidally-dominated ({phi}-directed) and poloidally-dominated (R-z directed) magnetic fields. Firstly, for toroidal field models and BHs with high enough |a/M|, coherent large-scale (i.e. >> H) dipolar poloidal magnetic flux patches emerge, thread the BH, and generate transient relativistic jets. Secondly, for poloidal field models, poloidal magnetic flux readily accretes through the disk from large radii and builds-up to a natural saturation point near the BH. While models with |H/R| {approx} 1 and |a/M| {le} 0.5 do not launch jets due to quenching by mass infall, for sufficiently high |a/M| or low |H/R| the polar magnetic field compresses the inflow into a geometrically thin highly non-axisymmetric 'magnetically choked accretion flow' (MCAF) within which the standard linear magneto-rotational instability is suppressed. The condition of a highly-magnetized state over most of the horizon is optimal for the Blandford-Znajek mechanism that generates persistent relativistic jets with and 100% efficiency for |a/M| {approx}> 0.9. A magnetic Rayleigh-Taylor and Kelvin-Helmholtz unstable magnetospheric interface forms between the compressed inflow and bulging jet magnetosphere, which drives a new jet-disk oscillation (JDO) type of quasi-periodic oscillation (QPO) mechanism. The high-frequency QPO has spherical harmonic |m| = 1 mode period of {tau} {approx} 70GM/c{sup 3} for a/M {approx} 0.9 with coherence quality factors Q {approx}> 10. Overall, our models are qualitatively distinct from most prior MHD simulations (typically, |H/R| << 1 and poloidal flux is limited by
NASA Astrophysics Data System (ADS)
Del Zanna, L.; Zanotti, O.; Bucciantini, N.; Londrillo, P.
2007-10-01
Aims:We present a new numerical code, ECHO, based on a Eulerian conservative high-order scheme for time dependent three-dimensional general relativistic magnetohydrodynamics (GRMHD) and magnetodynamics (GRMD). ECHO is aimed at providing a shock-capturing conservative method able to work at an arbitrary level of formal accuracy (for smooth flows), where the other existing GRMHD and GRMD schemes yield an overall second order at most. Moreover, our goal is to present a general framework based on the 3+1 Eulerian formalism, allowing for different sets of equations and different algorithms and working in a generic space-time metric, so that ECHO may be easily coupled to any solver for Einstein's equations. Methods: Our finite-difference conservative scheme previously developed for special relativistic hydrodynamics and MHD is extended here to the general relativistic case. Various high-order reconstruction methods are implemented and a two-wave approximate Riemann solver is used. The induction equation is treated by adopting the upwind constrained transport (UCT) procedures, appropriate to preserving the divergence-free condition of the magnetic field in shock-capturing methods. The limiting case of magnetodynamics (also known as force-free degenerate electrodynamics) is implemented by simply replacing the fluid velocity with the electromagnetic drift velocity and by neglecting the contribution of matter to the stress tensor. Results: ECHO is particularly accurate, efficient, versatile, and robust. It has been tested against several astrophysical applications, like magnetized accretion onto black holes and constant angular momentum thick disks threaded by toroidal fields. A novel test of the propagation of large-amplitude, circularly polarized Alfvén waves is proposed, and this allows us to prove the spatial and temporal high-order properties of ECHO very accurately. In particular, we show that reconstruction based on a monotonicity-preserving (MP) filter applied to a
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.
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.
3D RMHD Simulations of Magnetized Spine-Sheath Relativistic Jets
NASA Technical Reports Server (NTRS)
Mizuno, Yosuke; Hardee, Philip; Nishikawa, Ken-Ichi
2008-01-01
We have performed numerical simulations of weakly and strongly magnetized relativistic jets embedded in a weakly and strongly magnetized stationary or mildly relativistic (0.5c) sheath flow using the RAISHIN code. In the numerical simulations a jet with Lorentz factor gamma=2.5 is processed to break the initial equilibrium configuration. Results of the numerical simulations are compared to theoretical predictions from a normal mode analysis of the linearized RMHD equations describing a uniform axially magnetized cylindrical relativistic jet embedded in a uniform axially magnetized sheath flow. The prediction of increased stability of a weakly-magnetized system with mildly relativistic sheath flow to Kelvin-Helmholtz instabilities and the stabilization of a strongly magnetized system with mildly relativistic sheath flow is confirmed by the numerical simulations.
3D RMHD Simulations of Magnetized Spine-sheath Relativistic Jets
NASA Technical Reports Server (NTRS)
Mizuno, Yosuke; Hardee, Phillip; Ken-Ichi, Nishikawa
2008-01-01
We have performed numerical simulations of weakly and strongly magnetized relativistic jets embedded in a weakly and strongly magnetized stationary or mildly relativistic'(0.5c) sheath flow using the RAISHIN code. In the numerical simulations a jet with Lorentz factor gamma=2.5 is processed to break the initial equilibrium configuration. Results of the numerical simulations are compared to theoretical predictions from a normal mode analysis of the linearized RMHD equations describing a uniform axially magnetized cylindrical relativistic jet embedded in a uniform axially magnetized sheath flow. The prediction of increased stability of a weakly-magnetized system with mildly relativistic sheath flow to Kelvin-Helmholtz instabilities and the stabilization of a strongly-magnetized system with mildly relativistic sheath flow is confirmed by the numerical simulations.
NASA Astrophysics Data System (ADS)
Barbera, E.; Orlando, S.; Peres, G.
2017-04-01
Context. Intermediate polar cataclysmic variables (IPCV) contain a magnetic, rotating white dwarf surrounded by a magnetically truncated accretion disk. To explain their strong flickering X-ray emission, accretion has been successfully taken into account. Nevertheless, observations suggest that accretion phenomena might not be the only process behind it. An intense flaring activity occurring on the surface of the disk may generate a corona, contribute to the thermal X-ray emission, and influence the system stability. Aims: Our purposes are: investigating the formation of an extended corona above the accretion disk, due to an intense flaring activity occurring on the disk surface; studying the effects of flares on the disk and stellar magnetosphere; assessing its contribution to the observed thermal X-ray flux. Methods: We have developed a 3D magnetohydrodynamic (MHD) model of a IPCV system. The model takes into account gravity, disk viscosity, thermal conduction, radiative losses, and coronal flare heating through heat injection at randomly chosen locations on the disk surface. To perform a parameter space exploration, several system conditions have been considered, with different magnetic field intensity and disk density values. From the results of the evolution of the model, we have synthesized the thermal X-ray emission. Results: The simulations show the formation of an extended corona, linking disk and star. The flaring activity is capable of strongly influencing the disk configuration and possibly its stability, effectively deforming the magnetic field lines. Hot plasma evaporation phenomena occur in the layer immediately above the disk. The flaring activity gives rise to a thermal X-ray emission in both the [ 0.1-2.0 ] keV and the [ 2.0-10 ] keV X-ray bands. Conclusions: An intense coronal activity occurring on the disk surface of an IPCV can affect the structure of the disk depending noticeably on the density of the disk and the magnetic field of the central
NASA Astrophysics Data System (ADS)
Bugner, Marcus; Dietrich, Tim; Bernuzzi, Sebastiano; Weyhausen, Andreas; Brügmann, Bernd
2016-10-01
Discontinuous Galerkin (DG) methods coupled to weighted essentially nonoscillatory (WENO) algorithms allow high order convergence for smooth problems and for the simulation of discontinuities and shocks. In this work, we investigate WENO-DG algorithms in the context of numerical general relativity, in particular for general relativistic hydrodynamics. We implement the standard WENO method at different orders, a compact (simple) WENO scheme, as well as an alternative subcell evolution algorithm. To evaluate the performance of the different numerical schemes, we study nonrelativistic, special relativistic, and general relativistic test beds. We present the first three-dimensional simulations of general relativistic hydrodynamics, albeit for a fixed spacetime background, within the framework of WENO-DG methods. The most important test bed is a single Tolman-Oppenheimer-Volkoff star in three dimensions, showing that long term stable simulations of single isolated neutron stars can be obtained with WENO-DG methods.
NASA Astrophysics Data System (ADS)
Ciolfi, Riccardo; Kastaun, Wolfgang; Giacomazzo, Bruno; Endrizzi, Andrea; Siegel, Daniel M.; Perna, Rosalba
2017-03-01
Merging binary neutron stars (BNSs) represent the ultimate targets for multimessenger astronomy, being among the most promising sources of gravitational waves (GWs), and, at the same time, likely accompanied by a variety of electromagnetic counterparts across the entire spectrum, possibly including short gamma-ray bursts (SGRBs) and kilonova/macronova transients. Numerical relativity simulations play a central role in the study of these events. In particular, given the importance of magnetic fields, various aspects of this investigation require general relativistic magnetohydrodynamics (GRMHD). So far, most GRMHD simulations focused the attention on BNS mergers leading to the formation of a hypermassive neutron star (NS), which, in turn, collapses within few tens of ms into a black hole surrounded by an accretion disk. However, recent observations suggest that a significant fraction of these systems could form a long-lived NS remnant, which will either collapse on much longer time scales or remain indefinitely stable. Despite the profound implications for the evolution and the emission properties of the system, a detailed investigation of this alternative evolution channel is still missing. Here, we follow this direction and present a first detailed GRMHD study of BNS mergers forming a long-lived NS. We consider magnetized binaries with different mass ratios and equations of state and analyze the structure of the NS remnants, the rotation profiles, the accretion disks, the evolution and amplification of magnetic fields, and the ejection of matter. Moreover, we discuss the connection with the central engine of SGRBs and provide order-of-magnitude estimates for the kilonova/macronova signal. Finally, we study the GW emission, with particular attention to the post-merger phase.
The lifespan of 3D radial solutions to the non-isentropic relativistic Euler equations
NASA Astrophysics Data System (ADS)
Wei, Changhua
2017-10-01
This paper investigates the lower bound of the lifespan of three-dimensional spherically symmetric solutions to the non-isentropic relativistic Euler equations, when the initial data are prescribed as a small perturbation with compact support to a constant state. Based on the structure of the hyperbolic system, we show the almost global existence of the smooth solutions to Eulerian flows (polytropic gases and generalized Chaplygin gases) with genuinely nonlinear characteristics. While for the Eulerian flows (Chaplygin gas and stiff matter) with mild linearly degenerate characteristics, we show the global existence of the radial solutions, moreover, for the non-strictly hyperbolic system (pressureless perfect fluid) satisfying the mild linearly degenerate condition, we prove the blowup phenomenon of the radial solutions and show that the lifespan of the solutions is of order O(ɛ ^{-1}), where ɛ denotes the width of the perturbation. This work can be seen as a complement of our work (Lei and Wei in Math Ann 367:1363-1401, 2017) for relativistic Chaplygin gas and can also be seen as a generalization of the classical Eulerian fluids (Godin in Arch Ration Mech Anal 177:497-511, 2005, J Math Pures Appl 87:91-117, 2007) to the relativistic Eulerian fluids.
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.
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.
Introduction and guide to LLNL's relativistic 3-D nuclear hydrodynamics code
Zingman, J.A.; McAbee, T.L.; Alonso, C.T.; Wilson, J.R.
1987-11-01
We have constructed a relativistic hydrodynamic model to investigate Bevalac and higher energy, heavy-ion collisions. The basis of the model is a finite-difference solution to covariant hydrodynamics, which will be described in the rest of this paper. This paper also contains: a brief review of the equations and numerical methods we have employed in the solution to the hydrodynamic equations, a detailed description of several of the most important subroutines, and a numerical test on the code. 30 refs., 8 figs., 1 tab.
Relativistic Laser Pulse Intensification with 3D Printed Micro-Tube Plasma Target
NASA Astrophysics Data System (ADS)
Ji, Liangliang; Snyder, Joseph; Pukhov, Alexander; Akli, Kramer
2015-11-01
The potential and applications of laser-plasma interactions (LPI) are restricted by the parameter space of existing lasers and targets. Advancing the laser intensity to the extreme regime is motivated by the production of energetic particle beams and by the quest to explore the exotic regimes of light-matter interaction. Target density and dimensions can always be varied to optimize the outcome. Here, we propose to create another degree of freedom in the parameter space of LPI using recent advances in 3D printing of materials. Fine structures at nm scale with high repetition and accuracy can nowadays be manufactured, allowing for a full precise control of the target. We demonstrate, via particle-in-cell (PIC) simulations, that 3D-printed micro-tube plasma (MTP) targets yield an intensity enhancement factor of 2-5. The novel MTP targets not only act as a plasma optical device to reach the 1023W/cm2 threshold based on today's intensities, but can also boost the generation of secondary particle and radiation sources. This work demonstrates that the combination of high contrast high power lasers and nano-3D printing techniques opens new paths in the intensity frontier and LPI micro-engineering.
NASA Astrophysics Data System (ADS)
Kumar, R. V. M. S. S. Kiran; Varma, S. Vijaya Kumar; Raju, C. S. K.; Ibrahim, S. M.; Lorenzini, G.; Lorenzini, E.
2017-05-01
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics and other fields of materials science and technology. With this intention, we investigate the three-dimensional magnetohydrodynamic convective heat and mass transfer of nanofluid over a slendering stretching sheet filled with porous medium and heat source/sink. For balancing the flow, temperature and concentration slip mechanisms are also taken into account. In this investigation simulation performed by mixing the two types of carbon nanotubes, namely single- and multi-walled carbon nanotubes, into water as base fluid. The governing system of partial differential equations is transformed into nonlinear ordinary differential equations which answered by using R-K-Fehlberg-integration scheme. The impact of various pertinent parameters on velocity, temperature and concentration as well as the friction factor coefficient, local Nusselt and local Sherwood number is derived and discussed through graphs and tables for both single- and multi-walled carbon nanotubes cases. It is found that the momentum boundary layer thickness of SWCNTs is thicker than MWCNTs. These results can help us to conclude that SWCNTs are helpful for minimizing the friction between the particles, whereas MWCNTs are helpful for boosting the heat and mass transfer rate.
Ohsuga, Ken; Takahashi, Hiroyuki R.
2016-02-20
We develop a numerical scheme for solving the equations of fully special relativistic, radiation magnetohydrodynamics (MHDs), in which the frequency-integrated, time-dependent radiation transfer equation is solved to calculate the specific intensity. The radiation energy density, the radiation flux, and the radiation stress tensor are obtained by the angular quadrature of the intensity. In the present method, conservation of total mass, momentum, and energy of the radiation magnetofluids is guaranteed. We treat not only the isotropic scattering but also the Thomson scattering. The numerical method of MHDs is the same as that of our previous work. The advection terms are explicitly solved, and the source terms, which describe the gas–radiation interaction, are implicitly integrated. Our code is suitable for massive parallel computing. We present that our code shows reasonable results in some numerical tests for propagating radiation and radiation hydrodynamics. Particularly, the correct solution is given even in the optically very thin or moderately thin regimes, and the special relativistic effects are nicely reproduced.
NASA Astrophysics Data System (ADS)
Matsumoto, Jin; Masada, Youhei; Asano, Eiji; Shibata, Kazunari
2011-05-01
The nonlinear dynamics of outflows driven by magnetic explosion on the surface of a compact star is investigated through special relativistic magnetohydrodynamic simulations. We adopt, as the initial equilibrium state, a spherical stellar object embedded in hydrostatic plasma which has a density ρ(r) vprop r -α and is threaded by a dipole magnetic field. The injection of magnetic energy at the surface of a compact star breaks the equilibrium and triggers a two-component outflow. At the early evolutionary stage, the magnetic pressure increases rapidly around the stellar surface, initiating a magnetically driven outflow. A strong forward shock driven outflow is then excited. The expansion velocity of the magnetically driven outflow is characterized by the Alfvén velocity on the stellar surface and follows a simple scaling relation v mag vprop v A 1/2. When the initial density profile declines steeply with radius, the strong shock is accelerated self-similarly to relativistic velocity ahead of the magnetically driven component. We find that it evolves according to a self-similar relation Γsh vprop r sh, where Γsh is the Lorentz factor of the plasma measured at the shock surface r sh. A purely hydrodynamic process would be responsible for the acceleration mechanism of the shock driven outflow. Our two-component outflow model, which is the natural outcome of the magnetic explosion, can provide a better understanding of the magnetic active phenomena on various magnetized compact stars.
Matsumoto, R.; Tajima, T.; Kaisig, M.; Shibata, K.; Ishido, Y.; Tsuneta, S.; Kawai, G; Kurokawa, H.; Akioka, M.; Acton, L.; Strong, K.; Nitta, N.
1992-01-01
The soft X-ray telescope on the Yohkoh mission enabled us to observe the evolution of emerging flux regions (EFR) in coronal X-rays with high spatial and temportal resolution. Futhermore, we now have enough computing capability to perform three-dimensional MHD simulation of EFRs with sufficient spacial resolution to study details of the flux emergence process. These new tools provide the opportunity to investigate the physics involved in the formation of coronal loops in much more detail. We carried out 3D MHD simulations of emerging magnetic flux regions under various initial conditions; (1) a horizontal magnetic flux sheet, (2) a bundle of horizontal flux tubes, and (3) a flux sheet with sheared magnetic fields. Numerical results show that coronal magnetic loops are formed due to the enhanced bouyancy resulting from gas precipitating along magnetic field lines. The interchange modes help to produce a fine fibrous structure perpendicular to the magnetic field direction in the linear stage, while the undular modes determine the overall loop structure. We observe in 3D simulations that during the ascendance of loops the bundle of flux tubes, or even the flux sheet, developes into dense filaments pinched between magnetic loops. We also find that magnetic field lines are twisted by the vortex motion produced by the horizontal expansion of magnetic loops. Our numerical results may explain the observed signatures such as (1) the spacial relation between soft X-ray loops and H[alpha] arch filaments obtained by coordinated observation between Yohkoh and ground-based observatories (Kawai et al. 1992), (2) the rate of increase in size of soft X-ray loops in EFRs (Ishido et al. 1992), (3) emergence of twisted magnetic loops, and (4) the threshold flux for formation of chromospheric arch filament systems (AFS).
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
Building a numerical relativistic non-ideal magnetohydrodynamics code for astrophysical applications
NASA Astrophysics Data System (ADS)
Aranguren, S. Miranda; Aloy, M. A.; Aloy, Carmen.
2014-08-01
Including resistive effects in relativistic magnetized plasmas is a challenging task, that a number of authors have recently tackled employing different methods. From the numerical point of view, the difficulty in including non-ideal terms arises from the fact that, in the limit of very high plasma conductivity (i.e., close to the ideal MHD limit), the system of governing equations becomes stiff, and the standard explicit integrating methods produce instabilities that destroy the numerical solution. To deal with such a difficulty, we have extended the relativistic MHD code MR-GENESIS, to include a number of Implicit Explicit Runge-Kutta (IMEX-RK) numerical methods. To validate the implementation of the IMEX-RK schemes, two standard tests are presented in one and two spatial dimensions, covering different conductivity regimes.
Equation of state in relativistic magnetohydrodynamics: variable versus constant adiabatic index
NASA Astrophysics Data System (ADS)
Mignone, A.; McKinney, Jonathan C.
2007-07-01
The role of the equation of state (EoS) for a perfectly conducting, relativistic magnetized fluid is the main subject of this work. The ideal constant Γ-law EoS, commonly adopted in a wide range of astrophysical applications, is compared with a more realistic EoS that better approximates the single-specie relativistic gas. The paper focuses on three different topics. First, the influence of a more realistic EoS on the propagation of fast magnetosonic shocks is investigated. This calls into question the validity of the constant Γ-law EoS in problems where the temperature of the gas substantially changes across hydromagnetic waves. Secondly, we present a new inversion scheme to recover primitive variables (such as rest-mass density and pressure) from conservative ones that allows for a general EoS and avoids catastrophic numerical cancellations in the non-relativistic and ultrarelativistic limits. Finally, selected numerical tests of astrophysical relevance (including magnetized accretion flows around Kerr black holes) are compared using different equations of state. Our main conclusion is that the choice of a realistic EoS can considerably bear upon the solution when transitions from cold to hot gas (or vice versa) are present. Under these circumstances, a polytropic EoS can significantly endanger the solution.
Matsumoto, Jin; Asano, Eiji; Shibata, Kazunari; Masada, Youhei
2011-05-20
The nonlinear dynamics of outflows driven by magnetic explosion on the surface of a compact star is investigated through special relativistic magnetohydrodynamic simulations. We adopt, as the initial equilibrium state, a spherical stellar object embedded in hydrostatic plasma which has a density {rho}(r) {proportional_to} r{sup -}{alpha} and is threaded by a dipole magnetic field. The injection of magnetic energy at the surface of a compact star breaks the equilibrium and triggers a two-component outflow. At the early evolutionary stage, the magnetic pressure increases rapidly around the stellar surface, initiating a magnetically driven outflow. A strong forward shock driven outflow is then excited. The expansion velocity of the magnetically driven outflow is characterized by the Alfven velocity on the stellar surface and follows a simple scaling relation v{sub mag} {proportional_to} v{sub A}{sup 1/2}. When the initial density profile declines steeply with radius, the strong shock is accelerated self-similarly to relativistic velocity ahead of the magnetically driven component. We find that it evolves according to a self-similar relation {Gamma}{sub sh} {proportional_to} r{sub sh}, where {Gamma}{sub sh} is the Lorentz factor of the plasma measured at the shock surface r{sub sh}. A purely hydrodynamic process would be responsible for the acceleration mechanism of the shock driven outflow. Our two-component outflow model, which is the natural outcome of the magnetic explosion, can provide a better understanding of the magnetic active phenomena on various magnetized compact stars.
NASA Astrophysics Data System (ADS)
Núñez-de la Rosa, Jonatan; Munz, Claus-Dieter
2016-07-01
In this work, we discuss the extension of the XTROEM-FV code to relativistic hydrodynamics and magnetohydrodynamics. XTROEM-FV is a simulation package for computational astrophysics based on very high order finite-volume methods on Cartesian coordinates. Arbitrary spatial high order of accuracy is achieved with a weighted essentially non-oscillatory (WENO) reconstruction operator, and the time evolution is carried out with a strong stability preserving Runge-Kutta scheme. In XTROEM-FV has been implemented a cheap, robust, and accurate shock-capturing strategy for handling complex shock waves problems, typical in an astrophysical environment. The divergence constraint of the magnetic field is tackled with the generalized Lagrange multiplier divergence cleaning approach. Numerical computations of smooth flows for the relativistic hydrodynamics and magnetohydrodynamics equations are performed and confirm the high-order accuracy of the main reconstruction algorithm for such kind of flows. XTROEM-FV has been subject to a comprehensive numerical benchmark, especially for complex flows configurations within an astrophysical context. Computations of problems with shocks with very high order reconstruction operators up to seventh order are reported. For instance, one-dimensional shock tubes problems for relativistic hydrodynamics and magnetohydrodynamics, as well as two-dimensional flows like the relativistic double Mach reflection problem, the interaction of a shock wave with a bubble, the relativistic Orszag-Tang vortex, the cylindrical blast wave problem, the rotor problem, the Kelvin-Helmholtz instability, and an astrophysical slab jet. XTROEM-FV represents a new attempt to simulate astrophysical flow phenomena with very high order numerical methods.
Nakamura, Masanori
2014-04-20
We describe a new paradigm for understanding both relativistic motions and particle acceleration in the M87 jet: a magnetically dominated relativistic flow that naturally produces four relativistic magnetohydrodynamic (MHD) shocks (forward/reverse fast and slow modes). We apply this model to a set of optical super- and subluminal motions discovered by Biretta and coworkers with the Hubble Space Telescope during 1994-1998. The model concept consists of ejection of a single relativistic Poynting jet, which possesses a coherent helical (poloidal + toroidal) magnetic component, at the remarkably flaring point HST-1. We are able to reproduce quantitatively proper motions of components seen in the optical observations of HST-1 with the same model we used previously to describe similar features in radio very long baseline interferometry observations in 2005-2006. This indicates that the quad relativistic MHD shock model can be applied generally to recurring pairs of super/subluminal knots ejected from the upstream edge of the HST-1 complex as observed from radio to optical wavelengths, with forward/reverse fast-mode MHD shocks then responsible for observed moving features. Moreover, we identify such intrinsic properties as the shock compression ratio, degree of magnetization, and magnetic obliquity and show that they are suitable to mediate diffusive shock acceleration of relativistic particles via the first-order Fermi process. We suggest that relativistic MHD shocks in Poynting-flux-dominated helical jets may play a role in explaining observed emission and proper motions in many active galactic nuclei.
Pu, Hung-Yi; Nakamura, Masanori; Hirotani, Kouichi; Asada, Keiichi; Wu, Kinwah
2015-03-01
General relativistic magnetohydrodynamic (GRMHD) flows along magnetic fields threading a black hole can be divided into inflow and outflow parts, according to the result of the competition between the black hole gravity and magneto-centrifugal forces along the field line. Here we present the first self-consistent, semi-analytical solution for a cold, Poynting flux–dominated (PFD) GRMHD flow, which passes all four critical (inner and outer, Alfvén, and fast magnetosonic) points along a parabolic streamline. By assuming that the dominating (electromagnetic) component of the energy flux per flux tube is conserved at the surface where the inflow and outflow are separated, the outflow part of the solution can be constrained by the inflow part. The semi-analytical method can provide fiducial and complementary solutions for GRMHD simulations around the rotating black hole, given that the black hole spin, global streamline, and magnetizaion (i.e., a mass loading at the inflow/outflow separation) are prescribed. For reference, we demonstrate a self-consistent result with the work by McKinney in a quantitative level.
Mizuno, Yosuke; Nishikawa, Ken-Ichi; Lyubarsky, Yuri; Hardee, Philip E.
2009-07-20
We have investigated the development of current-driven (CD) kink instability through three-dimensional relativistic magnetohydrodynamic simulations. A static force-free equilibrium helical magnetic configuration is considered in order to study the influence of the initial configuration on the linear and nonlinear evolution of the instability. We found that the initial configuration is strongly distorted but not disrupted by the kink instability. The instability develops as predicted by linear theory. In the nonlinear regime, the kink amplitude continues to increase up to the terminal simulation time, albeit at different rates, for all but one simulation. The growth rate and nonlinear evolution of the CD kink instability depend moderately on the density profile and strongly on the magnetic pitch profile. The growth rate of the kink mode is reduced in the linear regime by an increase in the magnetic pitch with radius and reaches the nonlinear regime at a later time than the case with constant helical pitch. On the other hand, the growth rate of the kink mode is increased in the linear regime by a decrease in the magnetic pitch with radius and reaches the nonlinear regime sooner than the case with constant magnetic pitch. Kink amplitude growth in the nonlinear regime for decreasing magnetic pitch leads to a slender helically twisted column wrapped by magnetic field. On the other hand, kink amplitude growth in the nonlinear regime nearly ceases for increasing magnetic pitch.
NASA Technical Reports Server (NTRS)
Mizuno, Y.; Nishikawa, K.I.; Zhang, B.; Giacomazzo, B.; Hardee, P.E.; Nagataki, S.; Hartmann, D.H.
2008-01-01
We solve the Riemann problem for the deceleration of arbitrarily magnetized relativistic ejecta injected into a static unmagnetized medium. We find that for the same initial Lorentz factor, the reverse shock becomes progressively weaker with increasing magnetization s (the Poynting-to-kinetic energy flux ratio), and the shock becomes a rarefaction wave when s exceeds a critical value, sc, defined by the balance between the magnetic pressure in the ejecta and the thermal pressure in the forward shock. In the rarefaction wave regime, we find that the rarefied region is accelerated to a Lorentz factor that is significantly larger than the initial value. This acceleration mechanism is due to the strong magnetic pressure in the ejecta.
General Relativistic Magnetohydrodynamic Simulations of Jet Formation with a Thin Keplerian Disk
NASA Technical Reports Server (NTRS)
Mizuno, Yosuke; Nishikawa, Ken-Ichi; Koide, Shinji; Hardee, Philip; Gerald, J. Fishman
2006-01-01
We have performed several simulations of black hole systems (non-rotating, black hole spin parameter a = 0.0 and rapidly rotating, a = 0.95) with a geometrically thin Keplerian disk using the newly developed RAISHIN code. The simulation results show the formation of jets driven by the Lorentz force and the gas pressure gradient. The jets have mildly relativistic speed (greater than or equal to 0.4 c). The matter is continuously supplied from the accretion disk and the jet propagates outward until each applicable terminal simulation time (non-rotating: t/tau S = 275 and rotating: t/tau S = 200, tau s equivalent to r(sub s/c). It appears that a rotating black hole creates an additional, faster, and more collimated inner outflow (greater than or equal to 0.5 c) formed and accelerated by the twisted magnetic field resulting from frame-dragging in the black hole ergosphere. This new result indicates that jet kinematic structure depends on black hole rotation.
NASA Astrophysics Data System (ADS)
Takahashi, Hiroyuki R.; Ohsuga, Ken; Kawashima, Tomohisa; Sekiguchi, Yuichiro
2016-07-01
Using three-dimensional general relativistic radiation-magnetohydrodynamics simulations of accretion flows around stellar mass black holes, we report that the relatively cold disk (≳ {10}7 {{K}}) is truncated near the black hole. Hot and less dense regions, of which the gas temperature is ≳ {10}9 {{K}} and more than 10 times higher than the radiation temperature (overheated regions), appear within the truncation radius. The overheated regions also appear above as well as below the disk, sandwiching the cold disk, leading to the effective Compton upscattering. The truncation radius is ˜ 30{r}{{g}} for \\dot{M}˜ {L}{{Edd}}/{c}2, where {r}{{g}},\\dot{M},{L}{Edd},c are the gravitational radius, mass accretion rate, Eddington luminosity, and light speed, respectively. Our results are consistent with observations of a very high state, whereby the truncated disk is thought to be embedded in the hot rarefied regions. The truncation radius shifts inward to ˜ 10{r}{{g}} with increasing mass accretion rate \\dot{M}˜ 100{L}{{Edd}}/{c}2, which is very close to an innermost stable circular orbit. This model corresponds to the slim disk state observed in ultraluminous X-ray sources. Although the overheated regions shrink if the Compton cooling effectively reduces the gas temperature, the sandwich structure does not disappear at the range of \\dot{M}≲ 100{L}{{Edd}}/{c}2. Our simulations also reveal that the gas temperature in the overheated regions depends on black hole spin, which would be due to efficient energy transport from black hole to disks through the Poynting flux, resulting in gas heating.
NASA Astrophysics Data System (ADS)
Balsara, Dinshaw S.; Kim, Jinho
2016-05-01
The relativistic magnetohydrodynamics (RMHD) set of equations has recently seen an increased use in astrophysical computations. Even so, RMHD codes remain fragile. The reconstruction can sometimes yield superluminal velocities in certain parts of the mesh. The current generation of RMHD codes does not have any particularly good strategy for avoiding such an unphysical situation. In this paper we present a reconstruction strategy that overcomes this problem by making a single conservative to primitive transformation per cell followed by higher order WENO reconstruction on a carefully chosen set of primitives that guarantee subluminal reconstruction of the flow variables. For temporal evolution via a predictor step we also present second, third and fourth order accurate ADER methods that keep the velocity subluminal during the predictor step. The methods presented here are very general and should apply to other PDE systems where physical realizability is most easily asserted in the primitive variables. The RMHD system also requires the magnetic field to be evolved in a divergence-free fashion. In the treatment of classical numerical MHD the analogous issue has seen much recent progress with the advent of multidimensional Riemann solvers. By developing multidimensional Riemann solvers for RMHD, we show that similar advances extend to RMHD. As a result, the face-centered magnetic fields can be evolved much more accurately using the edge-centered electric fields in the corrector step. Those edge-centered electric fields come from a multidimensional Riemann solver for RMHD which we present in this paper. The overall update results in a one-step, fully conservative scheme that is suited for AMR. In this paper we also develop several new test problems for RMHD. We show that RMHD vortices can be designed that propagate on the computational mesh as self-preserving structures. These RMHD vortex test problems provide a means to do truly multidimensional accuracy testing for
NASA Astrophysics Data System (ADS)
Novak, Jerome; Dimmelmeier, Harrald; Font-Roda, Jose A.
2004-12-01
We present a new three-dimensional general relativistic hydrodynamics code which can be applied to study stellar core collapses and the resulting gravitational radiation. This code uses two different numerical techniques to solve partial differential equations arising in the model: high-resolution shock capturing (HRSC) schemes for the evolution of hydrodynamic quantities and spectral methods for the solution of Einstein equations. The equations are written and solved using spherical polar coordinates, best suited to stellar topology. Einstein equations are formulated within the 3+1 formalism and conformal flat condition (CFC) for the 3-metric and gravitational radiation is extracted using Newtonian quadrupole formulation.
Bai Xianchen; Yang Jianhua; Zhang Jiande
2012-08-15
By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.
NASA Astrophysics Data System (ADS)
Niasse, Nicolas; Chittenden, Jeremy
2012-10-01
The last few years have seen considerable advances in the application of high performance computing techniques to 3D simulations of wire array Z-pinches. Whilst the intense soft X-ray radiation output is the principle application of wire arrays, the ability to encompass spectrally detailed models of this emission within such 3D calculations was thought to be computationally prohibitive. We have developed a non-LTE atomic and radiation physics model with detailed configuration accounting and n-l splitting which is sufficiently streamlined to run in-line with large scale 3D simulations. In order to handle the volume of data generated by the spectral treatment of the billions of numerical cells, a novel data structure derived from a self-balancing binary search tree was developed, enabling the use of non-LTE DCA calculations within large scale 3D simulations for the first time. A brief description of the model is provided and the application of the simulations to understanding the X-ray generation processes within wire array Z-pinches on the Z generator at Sandia National Laboratory is reported. The contribution of the ion temperature and the motion of the unstable plasma at stagnation to the Doppler widths of the lines is described in detail.
Cheng, Lan; Gauss, Jürgen; Ruscic, Branko; ...
2017-01-12
Benchmark scalar-relativistic coupled-cluster calculations for dissociation energies of the 20 diatomic molecules containing 3d transition metals in the 3dMLBE20 database ( J. Chem. Theory Comput. 2015, 11, 2036) are reported in this paper. Electron correlation and basis set effects are systematically studied. The agreement between theory and experiment is in general satisfactory. For a subset of 16 molecules, the standard deviation between computational and experimental values is 9 kJ/mol with the maximum deviation being 15 kJ/mol. The discrepancies between theory and experiment remain substantial (more than 20 kJ/mol) for VH, CrH, CoH, and FeH. To explore the source of themore » latter discrepancies, the analysis used to determine the experimental dissociation energies for VH and CrH is revisited. It is shown that, if improved values are used for the heterolytic C–H dissociation energies of di- and trimethylamine involved in the experimental determination, the experimental values for the dissociation energies of VH and CrH are increased by 18 kJ/mol, such that D0(VH) = 223 ± 7 kJ/mol and D0(CrH) = 204 ± 7 kJ/mol (or De(VH) = 233 ± 7 kJ/mol and De(CrH) = 214 ± 7 kJ/mol). Finally, the new experimental values agree quite well with the calculated values, showing the consistency of the computation and the measured reaction thresholds.« less
Chen, Yuxi; Tóth, Gábor; Cassak, Paul; ...
2017-09-18
Here, we perform a three-dimensional (3D) global simulation of Earth's magnetosphere with kinetic reconnection physics to study the flux transfer events (FTEs) and dayside magnetic reconnection with the recently developed magnetohydrodynamics with embedded particle-in-cell model (MHD-EPIC). During the one-hour long simulation, the FTEs are generated quasi-periodically near the subsolar point and move toward the poles. We also find the magnetic field signature of FTEs at their early formation stage is similar to a ‘crater FTE’, which is characterized by a magnetic field strength dip at the FTE center. After the FTE core field grows to a significant value, it becomesmore » an FTE with typical flux rope structure. When an FTE moves across the cusp, reconnection between the FTE field lines and the cusp field lines can dissipate the FTE. The kinetic features are also captured by our model. A crescent electron phase space distribution is found near the reconnection site. A similar distribution is found for ions at the location where the Larmor electric field appears. The lower hybrid drift instability (LHDI) along the current sheet direction also arises at the interface of magnetosheath and magnetosphere plasma. Finally, the LHDI electric field is about 8 mV/m and its dominant wavelength relative to the electron gyroradius agrees reasonably with MMS observations.« less
Conservation of circulation in magnetohydrodynamics
Bekenstein; Oron
2000-10-01
We demonstrate at both the Newtonian and (general) relativistic levels the existence of a generalization of Kelvin's circulation theorem (for pure fluids) that is applicable to perfect magnetohydrodynamics. The argument is based on the least action principle for magnetohydrodynamic flow. Examples of the new conservation law are furnished. The new theorem should be helpful in identifying new kinds of vortex phenomena distinct from magnetic ropes or fluid vortices.
CAFE: A NEW RELATIVISTIC MHD CODE
Lora-Clavijo, F. D.; Cruz-Osorio, A.; Guzmán, F. S. E-mail: aosorio@astro.unam.mx
2015-06-22
We introduce CAFE, a new independent code designed to solve the equations of relativistic ideal magnetohydrodynamics (RMHD) in three dimensions. We present the standard tests for an RMHD code and for the relativistic hydrodynamics regime because we have not reported them before. The tests include the one-dimensional Riemann problems related to blast waves, head-on collisions of streams, and states with transverse velocities, with and without magnetic field, which is aligned or transverse, constant or discontinuous across the initial discontinuity. Among the two-dimensional (2D) and 3D tests without magnetic field, we include the 2D Riemann problem, a one-dimensional shock tube along a diagonal, the high-speed Emery wind tunnel, the Kelvin–Helmholtz (KH) instability, a set of jets, and a 3D spherical blast wave, whereas in the presence of a magnetic field we show the magnetic rotor, the cylindrical explosion, a case of Kelvin–Helmholtz instability, and a 3D magnetic field advection loop. The code uses high-resolution shock-capturing methods, and we present the error analysis for a combination that uses the Harten, Lax, van Leer, and Einfeldt (HLLE) flux formula combined with a linear, piecewise parabolic method and fifth-order weighted essentially nonoscillatory reconstructors. We use the flux-constrained transport and the divergence cleaning methods to control the divergence-free magnetic field constraint.
CAFE: A New Relativistic MHD Code
NASA Astrophysics Data System (ADS)
Lora-Clavijo, F. D.; Cruz-Osorio, A.; Guzmán, F. S.
2015-06-01
We introduce CAFE, a new independent code designed to solve the equations of relativistic ideal magnetohydrodynamics (RMHD) in three dimensions. We present the standard tests for an RMHD code and for the relativistic hydrodynamics regime because we have not reported them before. The tests include the one-dimensional Riemann problems related to blast waves, head-on collisions of streams, and states with transverse velocities, with and without magnetic field, which is aligned or transverse, constant or discontinuous across the initial discontinuity. Among the two-dimensional (2D) and 3D tests without magnetic field, we include the 2D Riemann problem, a one-dimensional shock tube along a diagonal, the high-speed Emery wind tunnel, the Kelvin-Helmholtz (KH) instability, a set of jets, and a 3D spherical blast wave, whereas in the presence of a magnetic field we show the magnetic rotor, the cylindrical explosion, a case of Kelvin-Helmholtz instability, and a 3D magnetic field advection loop. The code uses high-resolution shock-capturing methods, and we present the error analysis for a combination that uses the Harten, Lax, van Leer, and Einfeldt (HLLE) flux formula combined with a linear, piecewise parabolic method and fifth-order weighted essentially nonoscillatory reconstructors. We use the flux-constrained transport and the divergence cleaning methods to control the divergence-free magnetic field constraint.
Magneto-hydrodynamical model for plasma
NASA Astrophysics Data System (ADS)
Liu, Ruikuan; Yang, Jiayan
2017-10-01
Based on the Newton's second law and the Maxwell equations for the electromagnetic field, we establish a new 3-D incompressible magneto-hydrodynamics model for the motion of plasma under the standard Coulomb gauge. By using the Galerkin method, we prove the existence of a global weak solution for this new 3-D model.
Haas, Fernando; Pascoal, Kellen Alves; Mendonça, José Tito
2016-01-15
A new neutrino magnetohydrodynamics (NMHD) model is formulated, where the effects of the charged weak current on the electron-ion magnetohydrodynamic fluid are taken into account. The model incorporates in a systematic way the role of the Fermi neutrino weak force in magnetized plasmas. A fast neutrino-driven short wavelengths instability associated with the magnetosonic wave is derived. Such an instability should play a central role in strongly magnetized plasma as occurs in supernovae, where dense neutrino beams also exist. In addition, in the case of nonlinear or high frequency waves, the neutrino coupling is shown to be responsible for breaking the frozen-in magnetic field lines condition even in infinite conductivity plasmas. Simplified and ideal NMHD assumptions were adopted and analyzed in detail.
Boquist, Carl W.; Marchant, David D.
1978-01-01
A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.
Magnetohydrodynamic instability
NASA Technical Reports Server (NTRS)
Priest, E. R.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson, R. S.
1986-01-01
There have been major advances in the theory of magnetic reconnection and of magnetic instability, with important implications for the observations, as follows: (1) Fast and slow magnetic shock waves are produced by the magnetohydrodynamics of reconnection and are potential particle accelerators. (2) The impulsive bursty regime of reconnection gives a rapid release of magnetic energy in a series of bursts. (3) The radiative tearing mode creates cool filamentary structures in the reconnection process. (4) The stability analyses imply that an arcade can become unstable when either its height or twist of plasma pressure become too great.
Magnetohydrodynamics in stationary and axisymmetric spacetimes: A fully covariant approach
Gourgoulhon, Eric; Markakis, Charalampos; Uryu, Koji; Eriguchi, Yoshiharu
2011-05-15
A fully geometrical treatment of general relativistic magnetohydrodynamics is developed under the hypotheses of perfect conductivity, stationarity, and axisymmetry. The spacetime is not assumed to be circular, which allows for greater generality than the Kerr-type spacetimes usually considered in general relativistic magnetohydrodynamics. Expressing the electromagnetic field tensor solely in terms of three scalar fields related to the spacetime symmetries, we generalize previously obtained results in various directions. In particular, we present the first relativistic version of the Soloviev transfield equation, subcases of which lead to fully covariant versions of the Grad-Shafranov equation and of the Stokes equation in the hydrodynamical limit. We have also derived, as another subcase of the relativistic Soloviev equation, the equation governing magnetohydrodynamical equilibria with purely toroidal magnetic fields in stationary and axisymmetric spacetimes.
Newly-Developed 3D GRMHD Code and its Application to Jet Formation
NASA Technical Reports Server (NTRS)
Mizuno, Y.; Nishikawa, K.-I.; Koide, S.; Hardee, P.; Fishman, G. J.
2006-01-01
We have developed a new three-dimensional general relativistic magnetohydrodynamic code by using a conservative, high-resolution shock-capturing scheme. The numerical fluxes are calculated using the HLL approximate Riemann solver scheme. The flux-interpolated constrained transport scheme is used to maintain a divergence-free magnetic field. We have performed various 1-dimensional test problems in both special and general relativity by using several reconstruction methods and found that the new 3D GRMHD code shows substantial improvements over our previous model. The . preliminary results show the jet formations from a geometrically thin accretion disk near a non-rotating and a rotating black hole. We will discuss the jet properties depended on the rotation of a black hole and the magnetic field strength.
Marchant, David D.; Killpatrick, Don H.
1978-01-01
An electrode capable of withstanding high temperatures and suitable for use as a current collector in the channel of a magnetohydrodynamic (MHD) generator consists of a sintered powdered metal base portion, the upper surface of the base being coated with a first layer of nickel aluminide, an intermediate layer of a mixture of nickel aluminide - refractory ceramic on the first layer and a third or outer layer of a refractory ceramic material on the intermediate layer. The sintered powdered metal base resists spalling by the ceramic coatings and permits greater electrode compliance to thermal shock. The density of the powdered metal base can be varied to allow optimization of the thermal conductivity of the electrode and prevent excess heat loss from the channel.
SCALING OF THE ANOMALOUS BOOST IN RELATIVISTIC JET BOUNDARY LAYER
Zenitani, Seiji; Hesse, Michael; Klimas, Alex
2010-04-01
We investigate the one-dimensional interaction of a relativistic jet and an external medium. Relativistic magnetohydrodynamic simulations show an anomalous boost of the jet fluid in the boundary layer, as previously reported. We describe the boost mechanism using an ideal relativistic fluid and magnetohydrodynamic theory. The kinetic model is also examined for further understanding. Simple scaling laws for the maximum Lorentz factor are derived, and verified by the simulations.
Relativistic HD and MHD modelling for AGN jets
NASA Astrophysics Data System (ADS)
Keppens, R.; Porth, O.; Monceau-Baroux, R.; Walg, S.
2013-12-01
Relativistic hydro and magnetohydrodynamics (MHD) provide a continuum fluid description for plasma dynamics characterized by shock-dominated flows approaching the speed of light. Significant progress in its numerical modelling emerged in the last two decades; we highlight selected examples of modern grid-adaptive, massively parallel simulations realized by our open-source software MPI-AMRVAC (Keppens et al 2012 J. Comput. Phys. 231 718). Hydrodynamical models quantify how energy transfer from active galactic nuclei (AGN) jets to their surrounding interstellar/intergalactic medium (ISM/IGM) gets mediated through shocks and various fluid instability mechanisms (Monceau-Baroux et al 2012 Astron. Astrophys. 545 A62). With jet parameters representative for Fanaroff-Riley type-II jets with finite opening angles, we can quantify the ISM volumes affected by jet injection and distinguish the roles of mixing versus shock-heating in cocoon regions. This provides insight in energy feedback by AGN jets, usually incorporated parametrically in cosmological evolution scenarios. We discuss recent axisymmetric studies up to full 3D simulations for precessing relativistic jets, where synthetic radio maps can confront observations. While relativistic hydrodynamic models allow one to better constrain dynamical parameters like the Lorentz factor and density contrast between jets and their surroundings, the role of magnetic fields in AGN jet dynamics and propagation characteristics needs full relativistic MHD treatments. Then, we can demonstrate the collimating properties of an overal helical magnetic field backbone and study differences between poloidal versus toroidal field dominated scenarios (Keppens et al 2008 Astron. Astrophys. 486 663). Full 3D simulations allow one to consider the fate of non-axisymmetric perturbations on relativistic jet propagation from rotating magnetospheres (Porth 2013 Mon. Not. R. Astron. Soc. 429 2482). Self-stabilization mechanisms related to the detailed
NASA Astrophysics Data System (ADS)
Pletinckx, D.
2011-09-01
The current 3D hype creates a lot of interest in 3D. People go to 3D movies, but are we ready to use 3D in our homes, in our offices, in our communication? Are we ready to deliver real 3D to a general public and use interactive 3D in a meaningful way to enjoy, learn, communicate? The CARARE project is realising this for the moment in the domain of monuments and archaeology, so that real 3D of archaeological sites and European monuments will be available to the general public by 2012. There are several aspects to this endeavour. First of all is the technical aspect of flawlessly delivering 3D content over all platforms and operating systems, without installing software. We have currently a working solution in PDF, but HTML5 will probably be the future. Secondly, there is still little knowledge on how to create 3D learning objects, 3D tourist information or 3D scholarly communication. We are still in a prototype phase when it comes to integrate 3D objects in physical or virtual museums. Nevertheless, Europeana has a tremendous potential as a multi-facetted virtual museum. Finally, 3D has a large potential to act as a hub of information, linking to related 2D imagery, texts, video, sound. We describe how to create such rich, explorable 3D objects that can be used intuitively by the generic Europeana user and what metadata is needed to support the semantic linking.
NASA Astrophysics Data System (ADS)
Pei, Du; Ye, Ke
2016-11-01
We test the 3d-3d correspondence for theories that are labeled by Lens spaces. We find a full agreement between the index of the 3d N=2 "Lens space theory" T [ L( p, 1)] and the partition function of complex Chern-Simons theory on L( p, 1). In particular, for p = 1, we show how the familiar S 3 partition function of Chern-Simons theory arises from the index of a free theory. For large p, we find that the index of T[ L( p, 1)] becomes a constant independent of p. In addition, we study T[ L( p, 1)] on the squashed three-sphere S b 3 . This enables us to see clearly, at the level of partition function, to what extent G ℂ complex Chern-Simons theory can be thought of as two copies of Chern-Simons theory with compact gauge group G.
3d-3d correspondence revisited
Chung, Hee -Joong; Dimofte, Tudor; Gukov, Sergei; ...
2016-04-21
In fivebrane compactifications on 3-manifolds, we point out the importance of all flat connections in the proper definition of the effective 3d N = 2 theory. The Lagrangians of some theories with the desired properties can be constructed with the help of homological knot invariants that categorify colored Jones polynomials. Higgsing the full 3d theories constructed this way recovers theories found previously by Dimofte-Gaiotto-Gukov. As a result, we also consider the cutting and gluing of 3-manifolds along smooth boundaries and the role played by all flat connections in this operation.
3d-3d correspondence revisited
Chung, Hee -Joong; Dimofte, Tudor; Gukov, Sergei; Sułkowski, Piotr
2016-04-21
In fivebrane compactifications on 3-manifolds, we point out the importance of all flat connections in the proper definition of the effective 3d N = 2 theory. The Lagrangians of some theories with the desired properties can be constructed with the help of homological knot invariants that categorify colored Jones polynomials. Higgsing the full 3d theories constructed this way recovers theories found previously by Dimofte-Gaiotto-Gukov. As a result, we also consider the cutting and gluing of 3-manifolds along smooth boundaries and the role played by all flat connections in this operation.
PB3D: A new code for edge 3-D ideal linear peeling-ballooning stability
NASA Astrophysics Data System (ADS)
Weyens, T.; Sánchez, R.; Huijsmans, G.; Loarte, A.; García, L.
2017-02-01
A new numerical code PB3D (Peeling-Ballooning in 3-D) is presented. It implements and solves the intermediate-to-high-n ideal linear magnetohydrodynamic stability theory extended to full edge 3-D magnetic toroidal configurations in previous work [1]. The features that make PB3D unique are the assumptions on the perturbation structure through intermediate-to-high mode numbers n in general 3-D configurations, while allowing for displacement of the plasma edge. This makes PB3D capable of very efficient calculations of the full 3-D stability for the output of multiple equilibrium codes. As first verification, it is checked that results from the stability code MISHKA [2], which considers axisymmetric equilibrium configurations, are accurately reproduced, and these are then successfully extended to 3-D configurations, through comparison with COBRA [3], as well as using checks on physical consistency. The non-intuitive 3-D results presented serve as a tentative first proof of the capabilities of the code.
NASA Astrophysics Data System (ADS)
Meulien Ohlmann, Odile
2013-02-01
Today the industry offers a chain of 3D products. Learning to "read" and to "create in 3D" becomes an issue of education of primary importance. 25 years professional experience in France, the United States and Germany, Odile Meulien set up a personal method of initiation to 3D creation that entails the spatial/temporal experience of the holographic visual. She will present some different tools and techniques used for this learning, their advantages and disadvantages, programs and issues of educational policies, constraints and expectations related to the development of new techniques for 3D imaging. Although the creation of display holograms is very much reduced compared to the creation of the 90ies, the holographic concept is spreading in all scientific, social, and artistic activities of our present time. She will also raise many questions: What means 3D? Is it communication? Is it perception? How the seeing and none seeing is interferes? What else has to be taken in consideration to communicate in 3D? How to handle the non visible relations of moving objects with subjects? Does this transform our model of exchange with others? What kind of interaction this has with our everyday life? Then come more practical questions: How to learn creating 3D visualization, to learn 3D grammar, 3D language, 3D thinking? What for? At what level? In which matter? for whom?
Variational Integrators for Ideal and Reduced Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Kraus, Michael; Maj, Omar; Tassi, Emanuele; Grasso, Daniela
2016-10-01
Ideal and reduced magnetohydrodynamics are simplified sets of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. Discrete exterior calculus is used for the discretisation of the field variables in order to preserve their geometrical character. The resulting integrators preserve important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As these integrators are free of numerical resistivity, the magnetic field line topology is preserved and spurious reconnection is absent in the ideal case. Only when effects of finite electron mass are added, magnetic reconnection takes place. The excellent conservation properties of the methods are exemplified with numerical examples in 2D. We conclude with an outlook towards the treatment of general geometries in 3D and full magnetohydrodynamics.
On the kinetic foundations of Kaluza's magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Sandoval-Villalbazo, Alfredo; Sagaceta-Mejía, Alma R.; García-Perciante, Ana L.
2015-06-01
Recent work has shown the existence of a relativistic effect present in a single component non-equilibrium fluid, corresponding to a heat flux due to an electric field [J. Non-Equilib. Thermodyn. 38 (2013), 141-151]. The treatment in that work was limited to a four-dimensional Minkowski space-time in which the Boltzmann equation was treated in a special relativistic approach. The more complete framework of general relativity can be introduced to kinetic theory in order to describe transport processes associated to electromagnetic fields. In this context, the original Kaluza's formalism is a promising approach [Sitz. Ber. Preuss. Akad. Wiss. (1921), 966-972; Gen. Rel. Grav. 39 (2007), 1287-1296; Phys. Plasmas 7 (2000), 4823-4830]. The present work contains a kinetic theory basis for Kaluza's magnetohydrodynamics and gives a novel description for the establishment of thermodynamic forces beyond the special relativistic description.
NASA Astrophysics Data System (ADS)
Alday, Luis F.; Genolini, Pietro Benetti; Bullimore, Mathew; van Loon, Mark
2017-04-01
We explore aspects of the correspondence between Seifert 3-manifolds and 3d N = 2 supersymmetric theories with a distinguished abelian flavour symmetry. We give a prescription for computing the squashed three-sphere partition functions of such 3d N = 2 theories constructed from boundary conditions and interfaces in a 4d N = 2∗ theory, mirroring the construction of Seifert manifold invariants via Dehn surgery. This is extended to include links in the Seifert manifold by the insertion of supersymmetric Wilson-'t Hooft loops in the 4d N = 2∗ theory. In the presence of a mass parameter cfor the distinguished flavour symmetry, we recover aspects of refined Chern-Simons theory with complex gauge group, and in particular construct an analytic continuation of the S-matrix of refined Chern-Simons theory.
Kinetic approach to Kaluza's magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Sandoval-Villalbazo, A.; Garcia-Colin, L. S.
2011-11-01
Ten years ago we presented a formalism by means of which the basic tenets of relativistic magnetohydrodynamics were derived using Kaluza's ideas about unifying fields in terms of the corresponding space time curvature for a given metric. In this work we present an attempt to obtain the thermodynamic properties of a charged fluid using using Boltzmann's equation for a dilute system adapted to kaluza's formalism. The main results that we obtain are analytical expressions for the main currents and corresponding forces, within the formalism of linear irreversible thermodynamics. We also indicate how transport coefficients can be calculated. Other relevant results are also mentioned. A. Sandoval-Villalbazo and L.S. Garcia-Colin; Phys. of Plasmas 7, 4823 (2000).
Pei, Du; Ye, Ke
2016-11-02
Here, we test the 3d-3d correspondence for theories that are labeled by Lens spaces. We find a full agreement between the index of the 3d N=2 “Lens space theory” T [L(p, 1)] and the partition function of complex Chern-Simons theory on L(p, 1). In particular, for p = 1, we show how the familiar S3 partition function of Chern-Simons theory arises from the index of a free theory. For large p, we find that the index of T[L(p, 1)] becomes a constant independent of p. In addition, we study T[L(p, 1)] on the squashed three-sphere Sb3. This enables us tomore » see clearly, at the level of partition function, to what extent GC complex Chern-Simons theory can be thought of as two copies of Chern-Simons theory with compact gauge group G.« less
Pei, Du; Ye, Ke
2016-11-02
Here, we test the 3d-3d correspondence for theories that are labeled by Lens spaces. We find a full agreement between the index of the 3d N=2 “Lens space theory” T [L(p, 1)] and the partition function of complex Chern-Simons theory on L(p, 1). In particular, for p = 1, we show how the familiar S^{3} partition function of Chern-Simons theory arises from the index of a free theory. For large p, we find that the index of T[L(p, 1)] becomes a constant independent of p. In addition, we study T[L(p, 1)] on the squashed three-sphere S_{b}^{3}. This enables us to see clearly, at the level of partition function, to what extent G_{C} complex Chern-Simons theory can be thought of as two copies of Chern-Simons theory with compact gauge group G.
ERIC Educational Resources Information Center
Hastings, S. K.
2002-01-01
Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)
ERIC Educational Resources Information Center
Hastings, S. K.
2002-01-01
Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)
2004-08-20
This 3-D, microscopic imager mosaic of a target area on a rock called Diamond Jenness was taken after NASA Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time. 3D glasses are necessary.
Multi-region relaxed magnetohydrodynamics with flow
Dennis, G. R. Dewar, R. L.; Hole, M. J.; Hudson, S. R.
2014-04-15
We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes plasma flow. This new model is a generalization of Woltjer's model of relaxed magnetohydrodynamics equilibria with flow. We prove that as the number of plasma regions becomes infinite, our extension of MRxMHD reduces to ideal MHD with flow. We also prove that some solutions to MRxMHD with flow are not time-independent in the laboratory frame, and instead have 3D structure which rotates in the toroidal direction with fixed angular velocity. This capability gives MRxMHD potential application to describing rotating 3D MHD structures such as 'snakes' and long-lived modes.
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.
2011-01-01
In this animation of a 3D plasmon ruler, the plasmonic assembly acts as a transducer to deliver optical information about the structural dynamics of an attached protein. (courtesy of Paul Alivisatos group)
1997-07-13
Many prominent rocks near the Sagan Memorial Station are featured in this image from NASA Mars Pathfinder. Shark, Half-Dome, and Pumpkin are at center 3D glasses are necessary to identify surface detail.
2015-09-16
NASA Glenn's Icing Research Tunnel 3D Laser System used for digitizing ice shapes created in the wind tunnel. The ice shapes are later utilized for characterization, analysis, and software development.
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.
NASA Technical Reports Server (NTRS)
Niemiec, J.; Nishikawa, K.-I.; Hardee, P.; Pohl, M.; Medvedev, M.; Mizuno, Y.; Zhang, B.; Oka, M.; Sol, H.; Hartmann, D.
2009-01-01
Using 3D and 2D particle-in-cell simulations we investigate a shock structure, magnetic field generation, and particle acceleration associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized pair plasma. The simulations use long computational grids which allow to study the formation and dynamics of the system in a spatial and temporal way. We find for the first time a relativistic shock system comparable to a predicted magnetohydrodynamic shock structure consisting of leading and trailing shocks separated by a contact discontinuity. Strong electromagnetic fields resulting from the Weibel two-stream instability are generated in the trailing shock where jet matter is thermalized and decelerated. We analyze the formation and nonlinear development through saturation and dissipation of those fields and associated particle acceleration. In the AGN context the trailing shock corresponds to the jet shock at the head of a relativistic astrophysical jet. In the GRB context this trailing shock can be identified with the bow shock driven by relativistic ejecta. The strong electromagnetic field region in the trailing shock provides the emission site for the hot spot at the leading edge of AGN jets and for afterglow emission from GRBs.
NASA Astrophysics Data System (ADS)
Oldham, Mark
2015-01-01
Radiochromic materials exhibit a colour change when exposed to ionising radiation. Radiochromic film has been used for clinical dosimetry for many years and increasingly so recently, as films of higher sensitivities have become available. The two principle advantages of radiochromic dosimetry include greater tissue equivalence (radiologically) and the lack of requirement for development of the colour change. In a radiochromic material, the colour change arises direct from ionising interactions affecting dye molecules, without requiring any latent chemical, optical or thermal development, with important implications for increased accuracy and convenience. It is only relatively recently however, that 3D radiochromic dosimetry has become possible. In this article we review recent developments and the current state-of-the-art of 3D radiochromic dosimetry, and the potential for a more comprehensive solution for the verification of complex radiation therapy treatments, and 3D dose measurement in general.
NASA Astrophysics Data System (ADS)
Moore, Gregory F.
2009-05-01
This volume is a brief introduction aimed at those who wish to gain a basic and relatively quick understanding of the interpretation of three-dimensional (3-D) seismic reflection data. The book is well written, clearly illustrated, and easy to follow. Enough elementary mathematics are presented for a basic understanding of seismic methods, but more complex mathematical derivations are avoided. References are listed for readers interested in more advanced explanations. After a brief introduction, the book logically begins with a succinct chapter on modern 3-D seismic data acquisition and processing. Standard 3-D acquisition methods are presented, and an appendix expands on more recent acquisition techniques, such as multiple-azimuth and wide-azimuth acquisition. Although this chapter covers the basics of standard time processing quite well, there is only a single sentence about prestack depth imaging, and anisotropic processing is not mentioned at all, even though both techniques are now becoming standard.
Iliesiu, Luca; Kos, Filip; Poland, David; ...
2016-03-17
We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge CT. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.
Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran
2016-03-17
We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge C_{T}. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.
Furlow, Bryant
2017-05-01
Three-dimensional printing is used in the manufacturing industry, medical and pharmaceutical research, drug production, clinical medicine, and dentistry, with implications for precision and personalized medicine. This technology is advancing the development of patient-specific prosthetics, stents, splints, and fixation devices and is changing medical education, treatment decision making, and surgical planning. Diagnostic imaging modalities play a fundamental role in the creation of 3-D printed models. Although most 3-D printed objects are rigid, flexible soft-tissue-like prosthetics also can be produced. ©2017 American Society of Radiologic Technologists.
Magnetohydrodynamic cellular automata
NASA Technical Reports Server (NTRS)
Montgomery, David; Doolen, Gary D.
1987-01-01
A generalization of the hexagonal lattice gas model of Frisch, Hasslacher and Pomeau is shown to lead to two-dimensional magnetohydrodynamics. The method relies on the ideal point-wise conservation law for vector potential.
Experiments in Magnetohydrodynamics
ERIC Educational Resources Information Center
Rayner, J. P.
1970-01-01
Describes three student experiments in magnetohydrodynamics (MHD). In these experiments, it was found that the electrical conductivity of the local water supply was sufficient to demonstrate effectively some of the features of MHD flowmeters, generators, and pumps. (LC)
Experiments in Magnetohydrodynamics
ERIC Educational Resources Information Center
Rayner, J. P.
1970-01-01
Describes three student experiments in magnetohydrodynamics (MHD). In these experiments, it was found that the electrical conductivity of the local water supply was sufficient to demonstrate effectively some of the features of MHD flowmeters, generators, and pumps. (LC)
Magnetohydrodynamic power generation
NASA Technical Reports Server (NTRS)
Smith, J. L.
1984-01-01
Magnetohydrodynamic (MHD) Power Generation is a concise summary of MHD theory, history, and future trends. Results of the major international MHD research projects are discussed. Data from MHD research is included. Economics of initial and operating costs are considered.
Gyroscopic analog for magnetohydrodynamics
Holm, D.D.
1981-01-01
The gross features of plasma equilibrium and dynamics in the ideal magnetohydrodynamics (MHD) model can be understood in terms of a dynamical system which closely resembles the equations for a deformable gyroscope.
Introduction to Modern Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Galtier, Sébastien
2016-10-01
Preface; Table of physical quantities; Part I. Foundations: 1. Introduction; 2. Magnetohydrodynamics; 3. Conservation laws; Part II. Fundamental Processes: 4. Magnetohydrodynamic waves; 5. Dynamo; 6. Discontinuities and shocks; 7. Magnetic reconnection; Part III. Instabilities and Magnetic Confinement: 8. Static equilibrium; 9. Linear perturbation theory; 10. Study of MHD instabilities; Part IV. Turbulence: 11. Hydrodynamic turbulence; 12. MHD turbulence; 13. Advanced MHD turbulence; Appendix 1. Solutions to the exercises; Appendix 2. Formulary; References; Index.
Magnetohydrodynamic fluidic system
Lee, Abraham P.; Bachman, Mark G.
2004-08-24
A magnetohydrodynamic fluidic system includes a reagent source containing a reagent fluid and a sample source containing a sample fluid that includes a constituent. A reactor is operatively connected to the supply reagent source and the sample source. MHD pumps utilize a magnetohydrodynamic drive to move the reagent fluid and the sample fluid in a flow such that the reagent fluid and the sample fluid form an interface causing the constituent to be separated from the sample fluid.
NASA Technical Reports Server (NTRS)
Plaut, Jeffrey J.
1993-01-01
Stereographic images of the surface of Venus which enable geologists to reconstruct the details of the planet's evolution are discussed. The 120-meter resolution of these 3D images make it possible to construct digital topographic maps from which precise measurements can be made of the heights, depths, slopes, and volumes of geologic structures.
NASA Astrophysics Data System (ADS)
Carson, Jeffrey J. L.; Roumeliotis, Michael; Chaudhary, Govind; Stodilka, Robert Z.; Anastasio, Mark A.
2010-06-01
Our group has concentrated on development of a 3D photoacoustic imaging system for biomedical imaging research. The technology employs a sparse parallel detection scheme and specialized reconstruction software to obtain 3D optical images using a single laser pulse. With the technology we have been able to capture 3D movies of translating point targets and rotating line targets. The current limitation of our 3D photoacoustic imaging approach is its inability ability to reconstruct complex objects in the field of view. This is primarily due to the relatively small number of projections used to reconstruct objects. However, in many photoacoustic imaging situations, only a few objects may be present in the field of view and these objects may have very high contrast compared to background. That is, the objects have sparse properties. Therefore, our work had two objectives: (i) to utilize mathematical tools to evaluate 3D photoacoustic imaging performance, and (ii) to test image reconstruction algorithms that prefer sparseness in the reconstructed images. Our approach was to utilize singular value decomposition techniques to study the imaging operator of the system and evaluate the complexity of objects that could potentially be reconstructed. We also compared the performance of two image reconstruction algorithms (algebraic reconstruction and l1-norm techniques) at reconstructing objects of increasing sparseness. We observed that for a 15-element detection scheme, the number of measureable singular vectors representative of the imaging operator was consistent with the demonstrated ability to reconstruct point and line targets in the field of view. We also observed that the l1-norm reconstruction technique, which is known to prefer sparseness in reconstructed images, was superior to the algebraic reconstruction technique. Based on these findings, we concluded (i) that singular value decomposition of the imaging operator provides valuable insight into the capabilities of
NASA Astrophysics Data System (ADS)
Connors, M. G.; Schofield, I. S.
2012-12-01
Modern technologies in imaging greatly extend the potential to present visual information. With recently developed software tools, the perception of the third dimension can not only dramatically enhance presentation, but also allow spatial data to be better encoded. 3-D images can be taken for many subjects with only one camera, carefully moved to generate a stereo pair. Color anaglyph viewing now can be very effective using computer screens, and active filter technologies can enhance visual effects with ever-decreasing cost. We will present various novel results of 3-D imaging, including those from the auroral observations of the new twinned Athabasca University Geophysical Observatories.; Single camera stereo image for viewing with red/cyan glasses.
NASA Astrophysics Data System (ADS)
Bhardwaj, Lakshya
2017-05-01
This paper generalizes two facts about oriented 3d TFTs to the unoriented case. On one hand, it is known that oriented 3d TFTs having a topological boundary condition admit a state-sum construction known as the Turaev-Viro construction. This is related to the string-net construction of fermionic phases of matter. We show how Turaev-Viro construction can be generalized to unoriented 3d TFTs. On the other hand, it is known that the "fermionic" versions of oriented TFTs, known as Spin-TFTs, can be constructed in terms of "shadow" TFTs which are ordinary oriented TFTs with an anomalous ℤ 2 1-form symmetry. We generalize this correspondence to Pin+-TFTs by showing that they can be constructed in terms of ordinary unoriented TFTs with anomalous ℤ 2 1-form symmetry having a mixed anomaly with time-reversal symmetry. The corresponding Pin+-TFT does not have any anomaly for time-reversal symmetry however and hence it can be unambiguously defined on a non-orientable manifold. In case a Pin+-TFT admits a topological boundary condition, one can combine the above two statements to obtain a Turaev-Viro-like construction of Pin+-TFTs. As an application of these ideas, we construct a large class of Pin+-SPT phases.
NASA Technical Reports Server (NTRS)
1992-01-01
Ames Research Center research into virtual reality led to the development of the Convolvotron, a high speed digital audio processing system that delivers three-dimensional sound over headphones. It consists of a two-card set designed for use with a personal computer. The Convolvotron's primary application is presentation of 3D audio signals over headphones. Four independent sound sources are filtered with large time-varying filters that compensate for motion. The perceived location of the sound remains constant. Possible applications are in air traffic control towers or airplane cockpits, hearing and perception research and virtual reality development.
NASA Technical Reports Server (NTRS)
1997-01-01
The two hills in the distance, approximately one to two kilometers away, have been dubbed the 'Twin Peaks' and are of great interest to Pathfinder scientists as objects of future study. 3D glasses are necessary to identify surface detail. The white areas on the left hill, called the 'Ski Run' by scientists, may have been formed by hydrologic processes.
The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
NASA Astrophysics Data System (ADS)
Fung, Y. C.
1995-05-01
This conference on physiology and function covers a wide range of subjects, including the vasculature and blood flow, the flow of gas, water, and blood in the lung, the neurological structure and function, the modeling, and the motion and mechanics of organs. Many technologies are discussed. I believe that the list would include a robotic photographer, to hold the optical equipment in a precisely controlled way to obtain the images for the user. Why are 3D images needed? They are to achieve certain objectives through measurements of some objects. For example, in order to improve performance in sports or beauty of a person, we measure the form, dimensions, appearance, and movements.
Nonlinear magnetohydrodynamic stability
NASA Technical Reports Server (NTRS)
Bauer, F.; Betancourt, O.; Garabedian, P.
1981-01-01
The computer code developed by Bauer et al. (1978) for the study of the magnetohydrodynamic equilibrium and stability of a plasma in toroidal geometry is extended so that the growth rates of instabilities may be estimated more accurately. The original code, which is based on the variational principle of ideal magnetohydrodynamics, is upgraded by the introduction of a nonlinear formula for the growth rate of an unstable mode which acts as a quantitative measure of instability that is important in estimating numerical errors. The revised code has been applied to the determination of the nonlinear saturation, ballooning modes and beta limits for tokamaks, stellarators and torsatrons.
Cevidanes, Lucia; Tucker, Scott; Styner, Martin; Kim, Hyungmin; Chapuis, Jonas; Reyes, Mauricio; Proffit, William; Turvey, Timothy; Jaskolka, Michael
2009-01-01
This paper discusses the development of methods for computer-aided jaw surgery. Computer-aided jaw surgery allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery (CAS) system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3D surface models from Cone-beam CT (CBCT), dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intra-operative guidance. The system provides further intra-operative assistance with the help of a computer display showing jaw positions and 3D positioning guides updated in real-time during the surgical procedure. The CAS system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training and assessing the difficulties of the surgical procedures prior to the surgery. CAS has the potential to make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases. Supported by NIDCR DE017727, and DE018962 PMID:20816308
NASA Technical Reports Server (NTRS)
1997-01-01
An area of rocky terrain near the landing site of the Sagan Memorial Station can be seen in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
NASA Technical Reports Server (NTRS)
1997-01-01
An area of rocky terrain near the landing site of the Sagan Memorial Station can be seen in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
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.
3D glasma initial state for relativistic heavy ion collisions
Schenke, Björn; Schlichting, Sören
2016-10-13
We extend the impact-parameter-dependent Glasma model to three dimensions using explicit small-x evolution of the two incoming nuclear gluon distributions. We compute rapidity distributions of produced gluons and the early-time energy momentum tensor as a function of space-time rapidity and transverse coordinates. Finally, we study rapidity correlations and fluctuations of the initial geometry and multiplicity distributions and make comparisons to existing models for the three-dimensional initial state.
3D glasma initial state for relativistic heavy ion collisions
NASA Astrophysics Data System (ADS)
Schenke, Björn; Schlichting, Sören
2016-10-01
We extend the impact-parameter-dependent Glasma model to three dimensions using explicit small-x evolution of the two incoming nuclear gluon distributions. We compute rapidity distributions of produced gluons and the early-time energy momentum tensor as a function of space-time rapidity and transverse coordinates. We study rapidity correlations and fluctuations of the initial geometry and multiplicity distributions and make comparisons to existing models for the three-dimensional initial state.
RELATIVISTIC TWO-FLUID SIMULATIONS OF GUIDE FIELD MAGNETIC RECONNECTION
Zenitani, Seiji; Hesse, Michael; Klimas, Alex
2009-11-01
The nonlinear evolution of relativistic magnetic reconnection in sheared magnetic configuration (with a guide field) is investigated by using two-dimensional relativistic two-fluid simulations. Relativistic guide field reconnection features the charge separation and the guide field compression in and around the outflow channel. As the guide field increases, the composition of the outgoing energy changes from enthalpy-dominated to Poynting-dominated. The inertial effects of the two-fluid model play an important role to sustain magnetic reconnection. Implications for the single-fluid magnetohydrodynamic approach and the physics models of relativistic reconnection are briefly addressed.
NASA Technical Reports Server (NTRS)
1997-01-01
Many prominent rocks near the Sagan Memorial Station are featured in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. Wedge is at lower left; Shark, Half-Dome, and Pumpkin are at center. Flat Top, about four inches high, is at lower right. The horizon in the distance is one to two kilometers away.
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
2015-10-23
Global stereo mapping of Pluto surface is now possible, as images taken from multiple directions are downlinked from NASA New Horizons spacecraft. Stereo images will eventually provide an accurate topographic map of most of the hemisphere of Pluto seen by New Horizons during the July 14 flyby, which will be key to understanding Pluto's geological history. This example, which requires red/blue stereo glasses for viewing, shows a region 180 miles (300 kilometers) across, centered near longitude 130 E, latitude 20 N (the red square in the global context image). North is to the upper left. The image shows an ancient, heavily cratered region of Pluto, dotted with low hills and cut by deep fractures, which indicate extension of Pluto's crust. Analysis of these stereo images shows that the steep fracture in the upper left of the image is about 1 mile (1.6 kilometers) deep, and the craters in the lower right part of the image are up to 1.3 miles (2.1 km) deep. Smallest visible details are about 0.4 miles (0.6 kilometers) across. You will need 3D glasses to view this image showing an ancient, heavily cratered region of Pluto. http://photojournal.jpl.nasa.gov/catalog/PIA20032
NASA Astrophysics Data System (ADS)
Kühmstedt, Peter; Bräuer-Burchardt, Christian; Munkelt, Christoph; Heinze, Matthias; Palme, Martin; Schmidt, Ingo; Hintersehr, Josef; Notni, Gunther
2007-09-01
Here a new set-up of a 3D-scanning system for CAD/CAM in dental industry is proposed. The system is designed for direct scanning of the dental preparations within the mouth. The measuring process is based on phase correlation technique in combination with fast fringe projection in a stereo arrangement. The novelty in the approach is characterized by the following features: A phase correlation between the phase values of the images of two cameras is used for the co-ordinate calculation. This works contrary to the usage of only phase values (phasogrammetry) or classical triangulation (phase values and camera image co-ordinate values) for the determination of the co-ordinates. The main advantage of the method is that the absolute value of the phase at each point does not directly determine the coordinate. Thus errors in the determination of the co-ordinates are prevented. Furthermore, using the epipolar geometry of the stereo-like arrangement the phase unwrapping problem of fringe analysis can be solved. The endoscope like measurement system contains one projection and two camera channels for illumination and observation of the object, respectively. The new system has a measurement field of nearly 25mm × 15mm. The user can measure two or three teeth at one time. So the system can by used for scanning of single tooth up to bridges preparations. In the paper the first realization of the intraoral scanner is described.
NASA Technical Reports Server (NTRS)
2004-01-01
This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.
Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.
On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.
The image mosaic is about 6 centimeters (2.4 inches) across.
NASA Technical Reports Server (NTRS)
2004-01-01
This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.
Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.
On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.
The image mosaic is about 6 centimeters (2.4 inches) across.
3D Printing and 3D Bioprinting in Pediatrics
Vijayavenkataraman, Sanjairaj; Fuh, Jerry Y H; Lu, Wen Feng
2017-01-01
Additive manufacturing, commonly referred to as 3D printing, is a technology that builds three-dimensional structures and components layer by layer. Bioprinting is the use of 3D printing technology to fabricate tissue constructs for regenerative medicine from cell-laden bio-inks. 3D printing and bioprinting have huge potential in revolutionizing the field of tissue engineering and regenerative medicine. This paper reviews the application of 3D printing and bioprinting in the field of pediatrics. PMID:28952542
3D Printing and 3D Bioprinting in Pediatrics.
Vijayavenkataraman, Sanjairaj; Fuh, Jerry Y H; Lu, Wen Feng
2017-07-13
Additive manufacturing, commonly referred to as 3D printing, is a technology that builds three-dimensional structures and components layer by layer. Bioprinting is the use of 3D printing technology to fabricate tissue constructs for regenerative medicine from cell-laden bio-inks. 3D printing and bioprinting have huge potential in revolutionizing the field of tissue engineering and regenerative medicine. This paper reviews the application of 3D printing and bioprinting in the field of pediatrics.
Thermoacoustic magnetohydrodynamic electrical generator
Wheatley, John C.; Swift, Gregory W.; Migliori, Albert
1986-01-01
A thermoacoustic magnetohydrodynamic electrical generator includes an intrinsically irreversible thermoacoustic heat engine coupled to a magnetohydrodynamic electrical generator. The heat engine includes an electrically conductive liquid metal as the working fluid and includes two heat exchange and thermoacoustic structure assemblies which drive the liquid in a push-pull arrangement to cause the liquid metal to oscillate at a resonant acoustic frequency on the order of 1,000 Hz. The engine is positioned in the field of a magnet and is oriented such that the liquid metal oscillates in a direction orthogonal to the field of the magnet, whereby an alternating electrical potential is generated in the liquid metal. Low-loss, low-inductance electrical conductors electrically connected to opposite sides of the liquid metal conduct an output signal to a transformer adapted to convert the low-voltage, high-current output signal to a more usable higher voltage, lower current signal.
Thermoacoustic magnetohydrodynamic electrical generator
Wheatley, J.C.; Swift, G.W.; Migliori, A.
1984-11-16
A thermoacoustic magnetohydrodynamic electrical generator includes an intrinsically irreversible thermoacoustic heat engine coupled to a magnetohydrodynamic electrical generator. The heat engine includes an electrically conductive liquid metal as the working fluid and includes two heat exchange and thermoacoustic structure assemblies which drive the liquid in a push-pull arrangement to cause the liquid metal to oscillate at a resonant acoustic frequency on the order of 1000 Hz. The engine is positioned in the field of a magnet and is oriented such that the liquid metal oscillates in a direction orthogonal to the field of the magnet, whereby an alternating electrical potential is generated in the liquid metal. Low-loss, low-inductance electrical conductors electrically connected to opposite sides of the liquid metal conduct an output signal to a transformer adapted to convert the low-voltage, high-current output signal to a more usable higher voltage, lower current signal.
3D MHD disruptions simulations of tokamaks plasmas
NASA Astrophysics Data System (ADS)
Paccagnella, Roberto; Strauss, Hank; Breslau, Joshua
2008-11-01
Tokamaks Vertical Displacement Events (VDEs) and disruptions simulations in toroidal geometry by means of a single fluid visco-resistive magneto-hydro-dynamic (MHD) model are presented in this paper. The plasma model, implemented in the M3D code [1], is completed with the presence of a 2D homogeneous wall with finite resistivity. This allows the study of the relatively slowly growing magneto-hydro-dynamical perturbation, the resistive wall mode (RWM), which is, in this work, the main drive of the disruptions. Amplitudes and asymmetries of the halo currents pattern at the wall are also calculated and comparisons with tokamak experimental databases and predictions for ITER are given. [1] W. Park, E.V. Belova, G.Y. Fu, X.Z. Tang, H.R. Strauss, L.E. Sugiyama, Phys. Plasmas 6 (1999) 1796.
Interactions between magnetohydrodynamical discontinuities
Dai, W.; Woodward, P.R. )
1994-11-01
Interactions between magnetohydrodynamical (MHD) discontinuities are studied through numerical simulations for the set of one-dimensional MHD equations. The interactions include the impact of a shock on a contact discontinuity, the collision of two shocks, and the catchup of a shock over another shock. The shocks involved in the interactions may be very strong. Each shock in an interaction may be either a fast or a slow shock.
AC magnetohydrodynamic microfluidic switch
Lemoff, A V; Lee, A P
2000-03-02
A microfluidic switch has been demonstrated using an AC Magnetohydrodynamic (MHD) pumping mechanism in which the Lorentz force is used to pump an electrolytic solution. By integrating two AC MHD pumps into different arms of a Y-shaped fluidic circuit, flow can be switched between the two arms. This type of switch can be used to produce complex fluidic routing, which may have multiple applications in {micro}TAS.
Future of Magnetohydrodynamic Ship Propulsion,
1983-08-16
83 FOREIGN TECHNOLOGY DIVISION FUTURE OF MAGNETOHYDRODYNAMIC SHIP PROPULSION by A.P. Baranov DTIQ ~E tJ Approved for public release; 0.. distribution...MAGNETOHYDRODYNAMIC SHIP PROPULSION By: A.P. Baranov -,English pages: 10 Source: Sudostroyeniye, Nr. 12, December 1966, pp. 3-6 . Country of origin: USSR X...equations, etc. merged into this translation were extracted from the best quality copy available. FUTURE OF MAGNETOHYDRODYNAMIC SHIP PROPULSION A. P
Spectral Methods in General Relativistic MHD Simulations
NASA Astrophysics Data System (ADS)
Garrison, David
2012-03-01
In this talk I discuss the use of spectral methods in improving the accuracy of a General Relativistic Magnetohydrodynamic (GRMHD) computer code. I introduce SpecCosmo, a GRMHD code developed as a Cactus arrangement at UHCL, and show simulation results using both Fourier spectral methods and finite differencing. This work demonstrates the use of spectral methods with the FFTW 3.3 Fast Fourier Transform package integrated with the Cactus Framework to perform spectral differencing using MPI.
NASA Astrophysics Data System (ADS)
Mediavilla, Evencio; Arribas, Santiago; Roth, Martin; Cepa-Nogué, Jordi; Sánchez, Francisco
2011-09-01
Preface; Acknowledgements; 1. Introductory review and technical approaches Martin M. Roth; 2. Observational procedures and data reduction James E. H. Turner; 3. 3D Spectroscopy instrumentation M. A. Bershady; 4. Analysis of 3D data Pierre Ferruit; 5. Science motivation for IFS and galactic studies F. Eisenhauer; 6. Extragalactic studies and future IFS science Luis Colina; 7. Tutorials: how to handle 3D spectroscopy data Sebastian F. Sánchez, Begona García-Lorenzo and Arlette Pécontal-Rousset.
Spherical 3D isotropic wavelets
NASA Astrophysics Data System (ADS)
Lanusse, F.; Rassat, A.; Starck, J.-L.
2012-04-01
Context. Future cosmological surveys will provide 3D large scale structure maps with large sky coverage, for which a 3D spherical Fourier-Bessel (SFB) analysis in spherical coordinates is natural. Wavelets are particularly well-suited to the analysis and denoising of cosmological data, but a spherical 3D isotropic wavelet transform does not currently exist to analyse spherical 3D data. Aims: The aim of this paper is to present a new formalism for a spherical 3D isotropic wavelet, i.e. one based on the SFB decomposition of a 3D field and accompany the formalism with a public code to perform wavelet transforms. Methods: We describe a new 3D isotropic spherical wavelet decomposition based on the undecimated wavelet transform (UWT) described in Starck et al. (2006). We also present a new fast discrete spherical Fourier-Bessel transform (DSFBT) based on both a discrete Bessel transform and the HEALPIX angular pixelisation scheme. We test the 3D wavelet transform and as a toy-application, apply a denoising algorithm in wavelet space to the Virgo large box cosmological simulations and find we can successfully remove noise without much loss to the large scale structure. Results: We have described a new spherical 3D isotropic wavelet transform, ideally suited to analyse and denoise future 3D spherical cosmological surveys, which uses a novel DSFBT. We illustrate its potential use for denoising using a toy model. All the algorithms presented in this paper are available for download as a public code called MRS3D at http://jstarck.free.fr/mrs3d.html
3D Elevation Program—Virtual USA in 3D
Lukas, Vicki; Stoker, J.M.
2016-04-14
The U.S. Geological Survey (USGS) 3D Elevation Program (3DEP) uses a laser system called ‘lidar’ (light detection and ranging) to create a virtual reality map of the Nation that is very accurate. 3D maps have many uses with new uses being discovered all the time.
Magnetohydrodynamics of fractal media
Tarasov, Vasily E.
2006-05-15
The fractal distribution of charged particles is considered. An example of this distribution is the charged particles that are distributed over the fractal. The fractional integrals are used to describe fractal distribution. These integrals are considered as approximations of integrals on fractals. Typical turbulent media could be of a fractal structure and the corresponding equations should be changed to include the fractal features of the media. The magnetohydrodynamics equations for fractal media are derived from the fractional generalization of integral Maxwell equations and integral hydrodynamics (balance) equations. Possible equilibrium states for these equations are considered.
Magnetohydrodynamic Underwater Acoustic Transducer
1986-12-01
conductivity of an electrolyte not in the vicinity of an electrode + surface is "classically" analyzed using the theories of Debye and HuckelI5 and Debye and...15. P. Debye and E. Huckel , Physik. Z. 24 (1933) (in German). 16. P. Debye and H. Falkenhagen, Physik. Z. 29 121 (1928) (in German). 153 17. K. J...Transdtction 3 B. Present Work 4 Chapter 2 THEORY : THE MAGNETOHYDRODYNAMIC- THERMOACOUSTIC WAVE EQUATION A. Ohm’s Law for an Electrolyte 7 B Derivation of the
BOOK REVIEW: Nonlinear Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Shafranov, V.
1998-08-01
equations of a plasma in a magnetic field (which will be used further in models of dynamic processes), approaches to the description of three dimensional (3-D) equilibrium are briefly discussed, and the basis of the theory of linear instabilities and the basic types of MHD instabilities, with account taken of ideal resistive modes, are considered. The value of the material of these chapters is that here in a brief form the results of numerous researches in this area are presented, and frequently with a fresh point of view of old results. Chapters 5 to 10 are devoted to the subject of the book, non-linear magnetohydrodynamics. In the introduction to Chapter 5 the author pays attention to the fact that long standing doubts about the feasibility of magnetic thermonuclear reactors because of inevitable instabilities of non-uniform plasmas have been overcome in the last two decades: the plasma in tokamaks is rather well confined, despite the presence of some instabilities. The latter, as a rule, result only in the redistribution of current and plasma pressure profiles and some increase of transport, but can also lead to extremely undesirable effects. In this connection in Chapter 5 the attention of the reader is directed to the physics of the most important plasma instabilities in tokamaks. Models of the development of external and internal kink modes in tokamaks are considered, including the `vacuum bubble' model in shearless plasmas, the evolution of the resistive tearing mode together with saturation of the magnetic islands arising at a tearing instability. The rather long Chapter 6 is devoted to the fundamentals of the magnetic hydrodynamic dissipative process in the magnetic field line reconnection. This process of rapid dissipation of the energy of a magnetic field, having in the simplest case different directions in two adjacent volumes of plasma, underlies the theory of the phenomenon of powerful flares in the solar chromosphere, resulting in the well-known `magnetic
NASA Astrophysics Data System (ADS)
Ciardi, A.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Jennings, C. A.
2003-10-01
X-pinch produced plasmas are an intense source of soft x-rays generated by passing a large, fast rising current through two or more thin metallic wires crossed in the shape of <93>an "X". During the current pulse, the plasma is pinched at the crossing point where a dense Z-pinch plasma column develops. Further compression produces micron sized x-ray hot spots with energy densities in excess of ˜10^24 eV cm-3. We present 3D resistive magnetohydrodynamic simulations of two- and four-wire X-pinches for a variety of wire materials. The simulations naturally follow the evolution of the X-pinch: jet-like structures on axis, formation of a Z-pinch and its subsequent rapid evolution and production of x-ray hot spots. The effects of wire material and wire number are studied with particular consideration to the relationship between the magnetic confinement and radiative cooling mechanisms, which ultimately determine the complex behaviour of the X-pinch.
NASA Astrophysics Data System (ADS)
Ripperda, B.; Porth, O.; Xia, C.; Keppens, R.
2017-05-01
Magnetic reconnection and non-thermal particle distributions associated with current-driven instabilities are investigated by means of resistive magnetohydrodynamics (MHD) simulations combined with relativistic test particle methods. We propose a system with two parallel, repelling current channels in an initially force-free equilibrium, as a simplified representation of flux ropes in a stellar magnetosphere. The current channels undergo a rotation and separation on Alfvénic time-scales, forming secondary islands and (up to tearing unstable) current sheets in which non-thermal energy distributions are expected to develop. Using the recently developed particle module of our open-source grid-adaptive mpi-amrvac software, we simulate MHD evolution combined with test particle treatments in MHD snapshots. We explore under which plasma-β conditions the fastest reconnection occurs in 2.5D scenarios, and in these settings, test particles are evolved. We quantify energy distributions, acceleration mechanisms, relativistic corrections to the particle equations of motion and effects of resistivity in magnetically dominated proton-electron plasmas. Due to large resistive electric fields and indefinite acceleration of particles in the infinitely long current channels, hard energy spectra are found in 2.5D configurations. Solutions to these numerical artefacts are proposed for both 2.5D setups and future 3D work. We discuss the MHD of an additional kink instability in 3D setups and the expected effects on energy distributions. The obtained results hold as a proof-of-principle for test particle approaches in MHD simulations, relevant to explore less idealized scenarios like solar flares and more exotic astrophysical phenomena, like black hole flares, magnetar magnetospheres and pulsar wind nebulae.
Chiral magnetohydrodynamic turbulence
NASA Astrophysics Data System (ADS)
Pavlović, Petar; Leite, Natacha; Sigl, Günter
2017-07-01
In this work the influence of the chiral anomaly effect on the evolution of magnetohydrodynamic turbulence was studied. We argue that before the electroweak symmetry breaking and for temperatures high enough such that the electron mass can be ignored, the description of a charged plasma in general needs to take into account the interplay between turbulence and the anomaly effects. It was demonstrated that this generalization can have important consequences on the evolution of turbulence, leading to the creation of maximally-helical fields from initially nonhelical ones. Therefore, chiral effects can strongly support turbulent inverse cascade, and lead to a slower decrease of the magnetic field with time, and also to a faster growth of the correlation length, when compared to the evolution predicted by the standard magnetohydrodynamics description. Using the weak anomaly approximation, and treating the anomaly contributions to magnetic energy and helicity as a small perturbation, we derive the specific solutions for the inverse cascade regime that demonstrate how chiral effects support the inverse cascade.
Perception of 3D spatial relations for 3D displays
NASA Astrophysics Data System (ADS)
Rosen, Paul; Pizlo, Zygmunt; Hoffmann, Christoph; Popescu, Voicu S.
2004-05-01
We test perception of 3D spatial relations in 3D images rendered by a 3D display (Perspecta from Actuality Systems) and compare it to that of a high-resolution flat panel display. 3D images provide the observer with such depth cues as motion parallax and binocular disparity. Our 3D display is a device that renders a 3D image by displaying, in rapid succession, radial slices through the scene on a rotating screen. The image is contained in a glass globe and can be viewed from virtually any direction. In the psychophysical experiment several families of 3D objects are used as stimuli: primitive shapes (cylinders and cuboids), and complex objects (multi-story buildings, cars, and pieces of furniture). Each object has at least one plane of symmetry. On each trial an object or its "distorted" version is shown at an arbitrary orientation. The distortion is produced by stretching an object in a random direction by 40%. This distortion must eliminate the symmetry of an object. The subject's task is to decide whether or not the presented object is distorted under several viewing conditions (monocular/binocular, with/without motion parallax, and near/far). The subject's performance is measured by the discriminability d', which is a conventional dependent variable in signal detection experiments.
Generalized Ohm's law for relativistic plasmas
NASA Astrophysics Data System (ADS)
Kandus, A.; Tsagas, C. G.
2008-04-01
We generalize the relativistic expression of Ohm's law by studying a multifluid system of charged species using the 1 + 3 covariant formulation of general relativistic electrodynamics. This is done by providing a fully relativistic, fully non-linear propagation equation for the spatial component of the electric 4-current. Our analysis proceeds along the lines of the non-relativistic studies and extends previous relativistic work on cold plasmas. Exploiting the compactness and transparency of the covariant formalism, we provide a direct comparison with the standard Newtonian versions of Ohm's law and identify the relativistic corrections in an unambiguous way. The generalized expression of Ohm's law is initially given relative to an arbitrary observer and for a multicomponent relativistic charged medium. Then, the law is written with respect to the Eckart frame and for a hot two-fluid plasma with zero total charge. Finally, we apply our analysis to a cold proton-electron plasma and recover the well-known magnetohydrodynamic expressions. In every step, we discuss the approximations made and identify familiar effects, like the Biermann battery and the Hall effect.
2013-10-01
Earth3D is a computer code designed to allow fast calculation of seismic rays and travel times through a 3D model of the Earth. LLNL is using this for earthquake location and global tomography efforts and such codes are of great interest to the Earth Science community.
None
2016-07-12
This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.
NASA Technical Reports Server (NTRS)
1977-01-01
A market study of a proposed version of a 3-D eyetracker for initial use at NASA's Ames Research Center was made. The commercialization potential of a simplified, less expensive 3-D eyetracker was ascertained. Primary focus on present and potential users of eyetrackers, as well as present and potential manufacturers has provided an effective means of analyzing the prospects for commercialization.
NASA Astrophysics Data System (ADS)
van Hecke, Martin; de Reus, Koen; Florijn, Bastiaan; Coulais, Corentin
2014-03-01
We present a class of elastic structures which exhibit collective buckling in 3D, and create these by a 3D printing/moulding technique. Our structures consist of cubic lattice of anisotropic unit cells, and we show that their mechanical properties are programmable via the orientation of these unit cells.
2013-10-30
This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.
NASA Astrophysics Data System (ADS)
Walsh, J. R.
2004-02-01
The Euro3D RTN is an EU funded Research Training Network to foster the exploitation of 3D spectroscopy in Europe. 3D spectroscopy is a general term for spectroscopy of an area of the sky and derives its name from its two spatial + one spectral dimensions. There are an increasing number of instruments which use integral field devices to achieve spectroscopy of an area of the sky, either using lens arrays, optical fibres or image slicers, to pack spectra of multiple pixels on the sky (``spaxels'') onto a 2D detector. On account of the large volume of data and the special methods required to reduce and analyse 3D data, there are only a few centres of expertise and these are mostly involved with instrument developments. There is a perceived lack of expertise in 3D spectroscopy spread though the astronomical community and its use in the armoury of the observational astronomer is viewed as being highly specialised. For precisely this reason the Euro3D RTN was proposed to train young researchers in this area and develop user tools to widen the experience with this particular type of data in Europe. The Euro3D RTN is coordinated by Martin M. Roth (Astrophysikalisches Institut Potsdam) and has been running since July 2002. The first Euro3D science conference was held in Cambridge, UK from 22 to 23 May 2003. The main emphasis of the conference was, in keeping with the RTN, to expose the work of the young post-docs who are funded by the RTN. In addition the team members from the eleven European institutes involved in Euro3D also presented instrumental and observational developments. The conference was organized by Andy Bunker and held at the Institute of Astronomy. There were over thirty participants and 26 talks covered the whole range of application of 3D techniques. The science ranged from Galactic planetary nebulae and globular clusters to kinematics of nearby galaxies out to objects at high redshift. Several talks were devoted to reporting recent observations with newly
Dawood, A; Marti Marti, B; Sauret-Jackson, V; Darwood, A
2015-12-01
3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.
NASA Astrophysics Data System (ADS)
Pezzaniti, J. Larry; Edmondson, Richard; Vaden, Justin; Hyatt, Bryan; Chenault, David B.; Kingston, David; Geulen, Vanilynmae; Newell, Scott; Pettijohn, Brad
2009-02-01
In this paper, we report on the development of a 3D vision system consisting of a flat panel stereoscopic display and auto-converging stereo camera and an assessment of the system's use for robotic driving, manipulation, and surveillance operations. The 3D vision system was integrated onto a Talon Robot and Operator Control Unit (OCU) such that direct comparisons of the performance of a number of test subjects using 2D and 3D vision systems were possible. A number of representative scenarios were developed to determine which tasks benefited most from the added depth perception and to understand when the 3D vision system hindered understanding of the scene. Two tests were conducted at Fort Leonard Wood, MO with noncommissioned officers ranked Staff Sergeant and Sergeant First Class. The scenarios; the test planning, approach and protocols; the data analysis; and the resulting performance assessment of the 3D vision system are reported.
NASA Technical Reports Server (NTRS)
Walatka, Pamela P.; Buning, Pieter G.; Pierce, Larry; Elson, Patricia A.
1990-01-01
PLOT3D is a computer graphics program designed to visualize the grids and solutions of computational fluid dynamics. Seventy-four functions are available. Versions are available for many systems. PLOT3D can handle multiple grids with a million or more grid points, and can produce varieties of model renderings, such as wireframe or flat shaded. Output from PLOT3D can be used in animation programs. The first part of this manual is a tutorial that takes the reader, keystroke by keystroke, through a PLOT3D session. The second part of the manual contains reference chapters, including the helpfile, data file formats, advice on changing PLOT3D, and sample command files.
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITH TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITHOUT TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITHOUT TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITH TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into
Numerical Hydrodynamics and Magnetohydrodynamics in General Relativity.
Font, José A
2008-01-01
This article presents a comprehensive overview of numerical hydrodynamics and magneto-hydrodynamics (MHD) in general relativity. Some significant additions have been incorporated with respect to the previous two versions of this review (2000, 2003), most notably the coverage of general-relativistic MHD, a field in which remarkable activity and progress has occurred in the last few years. Correspondingly, the discussion of astrophysical simulations in general-relativistic hydrodynamics is enlarged to account for recent relevant advances, while those dealing with general-relativistic MHD are amply covered in this review for the first time. The basic outline of this article is nevertheless similar to its earlier versions, save for the addition of MHD-related issues throughout. Hence, different formulations of both the hydrodynamics and MHD equations are presented, with special mention of conservative and hyperbolic formulations well adapted to advanced numerical methods. A large sample of numerical approaches for solving such hyperbolic systems of equations is discussed, paying particular attention to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. As previously stated, a comprehensive summary of astrophysical simulations in strong gravitational fields is also presented. These are detailed in three basic sections, namely gravitational collapse, black-hole accretion, and neutron-star evolutions; despite the boundaries, these sections may (and in fact do) overlap throughout the discussion. The material contained in these sections highlights the numerical challenges of various representative simulations. It also follows, to some extent, the chronological development of the field, concerning advances in the formulation of the gravitational field, hydrodynamics and MHD equations and the numerical methodology designed to solve them. To keep the length of this article reasonable, an effort has
Unassisted 3D camera calibration
NASA Astrophysics Data System (ADS)
Atanassov, Kalin; Ramachandra, Vikas; Nash, James; Goma, Sergio R.
2012-03-01
With the rapid growth of 3D technology, 3D image capture has become a critical part of the 3D feature set on mobile phones. 3D image quality is affected by the scene geometry as well as on-the-device processing. An automatic 3D system usually assumes known camera poses accomplished by factory calibration using a special chart. In real life settings, pose parameters estimated by factory calibration can be negatively impacted by movements of the lens barrel due to shaking, focusing, or camera drop. If any of these factors displaces the optical axes of either or both cameras, vertical disparity might exceed the maximum tolerable margin and the 3D user may experience eye strain or headaches. To make 3D capture more practical, one needs to consider unassisted (on arbitrary scenes) calibration. In this paper, we propose an algorithm that relies on detection and matching of keypoints between left and right images. Frames containing erroneous matches, along with frames with insufficiently rich keypoint constellations, are detected and discarded. Roll, pitch yaw , and scale differences between left and right frames are then estimated. The algorithm performance is evaluated in terms of the remaining vertical disparity as compared to the maximum tolerable vertical disparity.
Stanton, M M; Samitier, J; Sánchez, S
2015-08-07
Three-dimensional (3D) bioprinting has recently emerged as an extension of 3D material printing, by using biocompatible or cellular components to build structures in an additive, layer-by-layer methodology for encapsulation and culture of cells. These 3D systems allow for cell culture in a suspension for formation of highly organized tissue or controlled spatial orientation of cell environments. The in vitro 3D cellular environments simulate the complexity of an in vivo environment and natural extracellular matrices (ECM). This paper will focus on bioprinting utilizing hydrogels as 3D scaffolds. Hydrogels are advantageous for cell culture as they are highly permeable to cell culture media, nutrients, and waste products generated during metabolic cell processes. They have the ability to be fabricated in customized shapes with various material properties with dimensions at the micron scale. 3D hydrogels are a reliable method for biocompatible 3D printing and have applications in tissue engineering, drug screening, and organ on a chip models.
Relativistic Particle and Relativistic Fluids: Magnetic Moment and Spin-Orbit Interactions
NASA Astrophysics Data System (ADS)
Karabali, Dimitra; Nair, V. P.
2014-11-01
We consider relativistic charged-particle dynamics and relativistic magnetohydrodynamics using symplectic structures and actions given in terms of coadjoint orbits of the Poincaré group. The particle case is meant to clarify some points such as how minimal coupling (as defined in the text) leads to a gyromagnetic ratio g =2 and to set the stage for fluid dynamics. The general group-theoretic framework is further explained and is then used to set up Abelian magnetohydrodynamics including spin effects. An interesting new physical effect is precession of spin density induced by gradients in pressure and energy density. The Euler equation (the dynamics of the velocity field) is also modified by gradients of the spin density.
2007-11-02
AGENCY USE ONLY (Leave Blank) 2. REPORT DATE 5 Feb 98 4. TITLE AND SUBTITLE 3D Scan Systems Integration REPORT TYPE AND DATES COVERED...2-89) Prescribed by ANSI Std. Z39-1 298-102 [ EDO QUALITY W3PECTEDI DLA-ARN Final Report for US Defense Logistics Agency on DDFG-T2/P3: 3D...SCAN SYSTEMS INTEGRATION Contract Number SPO100-95-D-1014 Contractor Ohio University Delivery Order # 0001 Delivery Order Title 3D Scan Systems
Thermoacoustic magnetohydrodynamic electrical generator
Wheatley, J.C.; Swift, G.W.; Migliori, A.
1986-07-08
A thermoacoustic magnetohydrodynamic electrical generator is described comprising a magnet having a magnetic field, an elongate hollow housing containing an electrically conductive liquid and a thermoacoustic structure positioned in the liquid, heat exchange means thermally connected to the thermoacoustic structure for inducing the liquid to oscillate at an acoustic resonant frequency within the housing. The housing is positioned in the magnetic field and oriented such that the direction of the magnetic field and the direction of oscillatory motion of the liquid are substantially orthogonal to one another, first and second electrical conductor means connected to the liquid on opposite sides of the housing along an axis which is substantially orthogonal to both the direction of the magnetic field and the direction of oscillatory motion of the liquid, an alternating current output signal is generated in the conductor means at a frequency corresponding to the frequency of the oscillatory motion of the liquid.
FARGO3D: A NEW GPU-ORIENTED MHD CODE
Benitez-Llambay, Pablo; Masset, Frédéric S. E-mail: masset@icf.unam.mx
2016-03-15
We present the FARGO3D code, recently publicly released. It is a magnetohydrodynamics code developed with special emphasis on the physics of protoplanetary disks and planet–disk interactions, and parallelized with MPI. The hydrodynamics algorithms are based on finite-difference upwind, dimensionally split methods. The magnetohydrodynamics algorithms consist of the constrained transport method to preserve the divergence-free property of the magnetic field to machine accuracy, coupled to a method of characteristics for the evaluation of electromotive forces and Lorentz forces. Orbital advection is implemented, and an N-body solver is included to simulate planets or stars interacting with the gas. We present our implementation in detail and present a number of widely known tests for comparison purposes. One strength of FARGO3D is that it can run on either graphical processing units (GPUs) or central processing units (CPUs), achieving large speed-up with respect to CPU cores. We describe our implementation choices, which allow a user with no prior knowledge of GPU programming to develop new routines for CPUs, and have them translated automatically for GPUs.
Radiation Magnetohydrodynamic Simulations of Protostellar Core Formation
NASA Astrophysics Data System (ADS)
Tomida, K.
2013-04-01
We perform 3D nested-grid radiation magnetohydrodynamic (RMHD) simulations of protostellar collapse from molecular cloud cores to protostellar cores with and without Ohmic dissipation of magnetic fields. We describe formation of circumstellar disks and multi-component outflows with our new code involving improved treatment of radiation transfer and thermodynamics. In the ideal RMHD models, the evolution of the protostellar core is very similar to that in the spherically symmetric non-rotating model because magnetic fields transport angular momentum very efficiently. However, if the resistivity is present, angular momentum transport is considerably suppressed due to loss of magnetic flux, and a rotationally-supported circumstellar disk is rapidly built up in the vicinity of the protostellar core. Magnetic fields are amplified by rotation and a fast well-collimated bipolar outflow is launched from the protostellar core via magnetic pressure gradient force.
1997-07-13
The Atmospheric Structure Instrument/Meteorology Package ASI/MET is the mast and windsocks at the center of this stereo image from NASA Mars Pathfinder. 3D glasses are necessary to identify surface detail.
This collaborative grant is developing 3D models of both mouse and human biology to investigate aspects of therapeutic vaccination in order to answer key questions relevant to human cancer immunotherapy.
Simon, Carl G; Yang, Yanyin; Dorsey, Shauna M; Ramalingam, Murugan; Chatterjee, Kaushik
2011-01-01
We have developed a combinatorial platform for fabricating tissue scaffold arrays that can be used for screening cell-material interactions. Traditional research involves preparing samples one at a time for characterization and testing. Combinatorial and high-throughput (CHT) methods lower the cost of research by reducing the amount of time and material required for experiments by combining many samples into miniaturized specimens. In order to help accelerate biomaterials research, many new CHT methods have been developed for screening cell-material interactions where materials are presented to cells as a 2D film or surface. However, biomaterials are frequently used to fabricate 3D scaffolds, cells exist in vivo in a 3D environment and cells cultured in a 3D environment in vitro typically behave more physiologically than those cultured on a 2D surface. Thus, we have developed a platform for fabricating tissue scaffold libraries where biomaterials can be presented to cells in a 3D format.
Rich, D.O.; Pope, S.C.; DeLapp, J.G.
1994-10-01
In April, a 128 PE Cray T3D was installed at Los Alamos National Laboratory`s Advanced Computing Laboratory as part of the DOE`s High-Performance Parallel Processor Program (H4P). In conjunction with CRI, the authors implemented a 30 day acceptance test. The test was constructed in part to help them understand the strengths and weaknesses of the T3D. In this paper, they briefly describe the H4P and its goals. They discuss the design and implementation of the T3D acceptance test and detail issues that arose during the test. They conclude with a set of system requirements that must be addressed as the T3D system evolves.
[Tridimensional (3D) endoscopic ultrasonography].
Varas Lorenzo, M J; Muñoz Agel, F; Abad Belando, R
2007-01-01
A review and update on 3D endoscopic ultrasonography is included regarding all of this technique s aspects, technical details, and current indications. Images from our own clinical experience are presented.
NASA Astrophysics Data System (ADS)
Yang, Xu; Zhang, Yong; Yang, Chenghua; Xu, Lu; Wang, Qiang; Zhao, Yuan
2016-06-01
Conventional three dimensional (3D) ghost imaging measures range of target based on pulse fight time measurement method. Due to the limit of data acquisition system sampling rate, range resolution of the conventional 3D ghost imaging is usually low. In order to take off the effect of sampling rate to range resolution of 3D ghost imaging, a heterodyne 3D ghost imaging (HGI) system is presented in this study. The source of HGI is a continuous wave laser instead of pulse laser. Temporal correlation and spatial correlation of light are both utilized to obtain the range image of target. Through theory analysis and numerical simulations, it is demonstrated that HGI can obtain high range resolution image with low sampling rate.
Combinatorial 3D Mechanical Metamaterials
NASA Astrophysics Data System (ADS)
Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin
2015-03-01
We present a class of elastic structures which exhibit 3D-folding motion. Our structures consist of cubic lattices of anisotropic unit cells that can be tiled in a complex combinatorial fashion. We design and 3d-print this complex ordered mechanism, in which we combine elastic hinges and defects to tailor the mechanics of the material. Finally, we use this large design space to encode smart functionalities such as surface patterning and multistability.
Fluid-magnetic helicity in axisymmetric stationary relativistic magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Prasad, G.
2017-10-01
The present work is intended to gain a fruitful insight into the understanding of the formations of magneto-vortex configurations and their role in the physical processes of mutual exchange of energies associated with fluid's motion and the magnetic fields in an axisymmetric stationary hydromagnetic system subject to strong gravitational field (e.g., neutron star/magnetar). It is found that the vorticity flux vector field associated with vorticity 2-form is a linear combination of fluid's vorticity vector and of magnetic vorticity vector. The vorticity flux vector obeys Helmholtz's flux conservation. The energy equation associated with the vorticity flux vector field is deduced. It is shown that the mechanical rotation of vorticity flux surfaces contributes to the formation of vorticity flux vector field. The dynamo action for the generation of toroidal components of vorticity flux vector field is described in the presence of meridional circulations. It is shown that the stretching of twisting magnetic lines due to differential rotation leads to the breakdown of gravitational isorotation in the absence of meridional circulations. An explicit expression consists of rotation of vorticity flux surface, energy and angular momentum per baryon for the fluid-magnetic helicity current vector is obtained. The conservation of fluid-magnetic helicity is demonstrated. It is found that the fluid-magnetic helicity displays the energy spectrum arising due to the interaction between the mechanical rotation of vorticity flux surfaces and the fluid's motion obeying Euler's equations. The dissipation of a linear combination of modified fluid helicity and magnetic twist is shown to occur due to coupled effect of frame dragging and meridional circulation. It is found that the growing twist of magnetic lines causes the dissipation of modified fluid helicity in the absence of meridional circulations.
LASTRAC.3d: Transition Prediction in 3D Boundary Layers
NASA Technical Reports Server (NTRS)
Chang, Chau-Lyan
2004-01-01
Langley Stability and Transition Analysis Code (LASTRAC) is a general-purpose, physics-based transition prediction code released by NASA for laminar flow control studies and transition research. This paper describes the LASTRAC extension to general three-dimensional (3D) boundary layers such as finite swept wings, cones, or bodies at an angle of attack. The stability problem is formulated by using a body-fitted nonorthogonal curvilinear coordinate system constructed on the body surface. The nonorthogonal coordinate system offers a variety of marching paths and spanwise waveforms. In the extreme case of an infinite swept wing boundary layer, marching with a nonorthogonal coordinate produces identical solutions to those obtained with an orthogonal coordinate system using the earlier release of LASTRAC. Several methods to formulate the 3D parabolized stability equations (PSE) are discussed. A surface-marching procedure akin to that for 3D boundary layer equations may be used to solve the 3D parabolized disturbance equations. On the other hand, the local line-marching PSE method, formulated as an easy extension from its 2D counterpart and capable of handling the spanwise mean flow and disturbance variation, offers an alternative. A linear stability theory or parabolized stability equations based N-factor analysis carried out along the streamline direction with a fixed wavelength and downstream-varying spanwise direction constitutes an efficient engineering approach to study instability wave evolution in a 3D boundary layer. The surface-marching PSE method enables a consistent treatment of the disturbance evolution along both streamwise and spanwise directions but requires more stringent initial conditions. Both PSE methods and the traditional LST approach are implemented in the LASTRAC.3d code. Several test cases for tapered or finite swept wings and cones at an angle of attack are discussed.
NASA Astrophysics Data System (ADS)
Yildiz, Yesna O.; Abraham, Douglas Q.; Agaian, Sos; Panetta, Karen
2008-02-01
Automated Explosive Detection Systems utilizing Computed Tomography perform a series X-ray scans of passenger bags being checked in at the airport, and produce various 2-D projection images and 3-D volumetric images of the bag. The determination as to whether the passenger bag contains an explosive and needs to be searched manually is performed through trained Transportation Security Administration screeners following an approved protocol. In order to keep the screeners vigilant with regards to screening quality, the Transportation Security Administration has mandated the use of Threat Image Projection on 2-D projection X-ray screening equipment used at all US airports. These algorithms insert visual artificial threats into images of the normal passenger bags in order to test the screeners with regards to their screening efficiency and their screening quality at determining threats. This technology for 2-D X-ray system is proven and is widespread amongst multiple manufacturers of X-ray projection systems. Until now, Threat Image Projection has been unsuccessful at being introduced into 3-D Automated Explosive Detection Systems for numerous reasons. The failure of these prior attempts are mainly due to imaging queues that the screeners pickup on, and therefore make it easy for the screeners to discern the presence of the threat image and thus defeating the intended purpose. This paper presents a novel approach for 3-D Threat Image Projection for 3-D Automated Explosive Detection Systems. The method presented here is a projection based approach where both the threat object and the bag remain in projection sinogram space. Novel approaches have been developed for projection based object segmentation, projection based streak reduction used for threat object isolation along with scan orientation independence and projection based streak generation for an overall realistic 3-D image. The algorithms are prototyped in MatLab and C++ and demonstrate non discernible 3-D threat
Relabeling symmetry in relativistic fluids and plasmas
NASA Astrophysics Data System (ADS)
Kawazura, Yohei; Yoshida, Zensho; Fukumoto, Yasuhide
2014-11-01
The conservation of the recently formulated relativistic canonical helicity (Yoshida et al 2014 J. Math. Phys. 55 043101) is derived from Noether's theorem by constructing an action principle on the relativistic Lagrangian coordinates (we obtain general cross helicities that include the helicity of the canonical vorticity). The conservation law is, then, explained by the relabeling symmetry pertinent to the Lagrangian label of fluid elements. Upon Eulerianizing the Noether current, the purely spatial volume integral on the Lagrangian coordinates is mapped to a space-time mixed three-dimensional integral on the four-dimensional Eulerian coordinates. The relativistic conservation law in the Eulerian coordinates is no longer represented by any divergence-free current; hence, it is not adequate to regard the relativistic helicity (represented by the Eulerian variables) as a Noether charge, and this stands the reason why the ‘conventional helicity’ is no longer a constant of motion. We have also formulated a relativistic action principle of magnetohydrodynamics (MHD) on the Lagrangian coordinates, and have derived the relativistic MHD cross helicity.
NASA Astrophysics Data System (ADS)
Dima, M.; Farisato, G.; Bergomi, M.; Viotto, V.; Magrin, D.; Greggio, D.; Farinato, J.; Marafatto, L.; Ragazzoni, R.; Piazza, D.
2014-08-01
In the last few years 3D printing is getting more and more popular and used in many fields going from manufacturing to industrial design, architecture, medical support and aerospace. 3D printing is an evolution of bi-dimensional printing, which allows to obtain a solid object from a 3D model, realized with a 3D modelling software. The final product is obtained using an additive process, in which successive layers of material are laid down one over the other. A 3D printer allows to realize, in a simple way, very complex shapes, which would be quite difficult to be produced with dedicated conventional facilities. Thanks to the fact that the 3D printing is obtained superposing one layer to the others, it doesn't need any particular work flow and it is sufficient to simply draw the model and send it to print. Many different kinds of 3D printers exist based on the technology and material used for layer deposition. A common material used by the toner is ABS plastics, which is a light and rigid thermoplastic polymer, whose peculiar mechanical properties make it diffusely used in several fields, like pipes production and cars interiors manufacturing. I used this technology to create a 1:1 scale model of the telescope which is the hardware core of the space small mission CHEOPS (CHaracterising ExOPlanets Satellite) by ESA, which aims to characterize EXOplanets via transits observations. The telescope has a Ritchey-Chrétien configuration with a 30cm aperture and the launch is foreseen in 2017. In this paper, I present the different phases for the realization of such a model, focusing onto pros and cons of this kind of technology. For example, because of the finite printable volume (10×10×12 inches in the x, y and z directions respectively), it has been necessary to split the largest parts of the instrument in smaller components to be then reassembled and post-processed. A further issue is the resolution of the printed material, which is expressed in terms of layers
YouDash3D: exploring stereoscopic 3D gaming for 3D movie theaters
NASA Astrophysics Data System (ADS)
Schild, Jonas; Seele, Sven; Masuch, Maic
2012-03-01
Along with the success of the digitally revived stereoscopic cinema, events beyond 3D movies become attractive for movie theater operators, i.e. interactive 3D games. In this paper, we present a case that explores possible challenges and solutions for interactive 3D games to be played by a movie theater audience. We analyze the setting and showcase current issues related to lighting and interaction. Our second focus is to provide gameplay mechanics that make special use of stereoscopy, especially depth-based game design. Based on these results, we present YouDash3D, a game prototype that explores public stereoscopic gameplay in a reduced kiosk setup. It features live 3D HD video stream of a professional stereo camera rig rendered in a real-time game scene. We use the effect to place the stereoscopic effigies of players into the digital game. The game showcases how stereoscopic vision can provide for a novel depth-based game mechanic. Projected trigger zones and distributed clusters of the audience video allow for easy adaptation to larger audiences and 3D movie theater gaming.
NASA Technical Reports Server (NTRS)
2002-01-01
In 1999, Genex submitted a proposal to Stennis Space Center for a volumetric 3-D display technique that would provide multiple users with a 360-degree perspective to simultaneously view and analyze 3-D data. The futuristic capabilities of the VolumeViewer(R) have offered tremendous benefits to commercial users in the fields of medicine and surgery, air traffic control, pilot training and education, computer-aided design/computer-aided manufacturing, and military/battlefield management. The technology has also helped NASA to better analyze and assess the various data collected by its satellite and spacecraft sensors. Genex capitalized on its success with Stennis by introducing two separate products to the commercial market that incorporate key elements of the 3-D display technology designed under an SBIR contract. The company Rainbow 3D(R) imaging camera is a novel, three-dimensional surface profile measurement system that can obtain a full-frame 3-D image in less than 1 second. The third product is the 360-degree OmniEye(R) video system. Ideal for intrusion detection, surveillance, and situation management, this unique camera system offers a continuous, panoramic view of a scene in real time.
Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Cole, John; Lineberry, John; Chapman, Jim; Schmidt, Harold; Cook, Stephen (Technical Monitor)
2002-01-01
A fundamental obstacle to routine space access is the specific energy limitations associated with chemical fuels. In the case of vertical take-off, the high thrust needed for vertical liftoff and acceleration to orbit translates into power levels in the 10 GW range. Furthermore, useful payload mass fractions are possible only if the exhaust particle energy (i.e., exhaust velocity) is much greater than that available with traditional chemical propulsion. The electronic binding energy released by the best chemical reactions (e.g., LOX/LH2 for example, is less than 2 eV per product molecule (approx. 1.8 eV per H2O molecule), which translates into particle velocities less than 5 km/s. Useful payload fractions, however, will require exhaust velocities exceeding 15 km/s (i.e., particle energies greater than 20 eV). As an added challenge, the envisioned hypothetical RLV (reusable launch vehicle) should accomplish these amazing performance feats while providing relatively low acceleration levels to orbit (2-3g maximum). From such fundamental considerations, it is painfully obvious that planned and current RLV solutions based on chemical fuels alone represent only a temporary solution and can only result in minor gains, at best. What is truly needed is a revolutionary approach that will dramatically reduce the amount of fuel and size of the launch vehicle. This implies the need for new compact high-power energy sources as well as advanced accelerator technologies for increasing engine exhaust velocity. Electromagnetic acceleration techniques are of immense interest since they can be used to circumvent the thermal limits associated with conventional propulsion systems. This paper describes the Magnetohydrodynamic Augmented Propulsion Experiment (MAPX) being undertaken at NASA Marshall Space Flight Center (MSFC). In this experiment, a 1-MW arc heater is being used as a feeder for a 1-MW magnetohydrodynamic (MHD) accelerator. The purpose of the experiment is to demonstrate
Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Cole, John; Lineberry, John; Chapman, Jim; Schmidt, Harold; Cook, Stephen (Technical Monitor)
2002-01-01
A fundamental obstacle to routine space access is the specific energy limitations associated with chemical fuels. In the case of vertical take-off, the high thrust needed for vertical liftoff and acceleration to orbit translates into power levels in the 10 GW range. Furthermore, useful payload mass fractions are possible only if the exhaust particle energy (i.e., exhaust velocity) is much greater than that available with traditional chemical propulsion. The electronic binding energy released by the best chemical reactions (e.g., LOX/LH2 for example, is less than 2 eV per product molecule (approx. 1.8 eV per H2O molecule), which translates into particle velocities less than 5 km/s. Useful payload fractions, however, will require exhaust velocities exceeding 15 km/s (i.e., particle energies greater than 20 eV). As an added challenge, the envisioned hypothetical RLV (reusable launch vehicle) should accomplish these amazing performance feats while providing relatively low acceleration levels to orbit (2-3g maximum). From such fundamental considerations, it is painfully obvious that planned and current RLV solutions based on chemical fuels alone represent only a temporary solution and can only result in minor gains, at best. What is truly needed is a revolutionary approach that will dramatically reduce the amount of fuel and size of the launch vehicle. This implies the need for new compact high-power energy sources as well as advanced accelerator technologies for increasing engine exhaust velocity. Electromagnetic acceleration techniques are of immense interest since they can be used to circumvent the thermal limits associated with conventional propulsion systems. This paper describes the Magnetohydrodynamic Augmented Propulsion Experiment (MAPX) being undertaken at NASA Marshall Space Flight Center (MSFC). In this experiment, a 1-MW arc heater is being used as a feeder for a 1-MW magnetohydrodynamic (MHD) accelerator. The purpose of the experiment is to demonstrate
3D Printed Bionic Nanodevices.
Kong, Yong Lin; Gupta, Maneesh K; Johnson, Blake N; McAlpine, Michael C
2016-06-01
The ability to three-dimensionally interweave biological and functional materials could enable the creation of bionic devices possessing unique and compelling geometries, properties, and functionalities. Indeed, interfacing high performance active devices with biology could impact a variety of fields, including regenerative bioelectronic medicines, smart prosthetics, medical robotics, and human-machine interfaces. Biology, from the molecular scale of DNA and proteins, to the macroscopic scale of tissues and organs, is three-dimensional, often soft and stretchable, and temperature sensitive. This renders most biological platforms incompatible with the fabrication and materials processing methods that have been developed and optimized for functional electronics, which are typically planar, rigid and brittle. A number of strategies have been developed to overcome these dichotomies. One particularly novel approach is the use of extrusion-based multi-material 3D printing, which is an additive manufacturing technology that offers a freeform fabrication strategy. This approach addresses the dichotomies presented above by (1) using 3D printing and imaging for customized, hierarchical, and interwoven device architectures; (2) employing nanotechnology as an enabling route for introducing high performance materials, with the potential for exhibiting properties not found in the bulk; and (3) 3D printing a range of soft and nanoscale materials to enable the integration of a diverse palette of high quality functional nanomaterials with biology. Further, 3D printing is a multi-scale platform, allowing for the incorporation of functional nanoscale inks, the printing of microscale features, and ultimately the creation of macroscale devices. This blending of 3D printing, novel nanomaterial properties, and 'living' platforms may enable next-generation bionic systems. In this review, we highlight this synergistic integration of the unique properties of nanomaterials with the
Kong, Yong Lin; Gupta, Maneesh K.; Johnson, Blake N.; McAlpine, Michael C.
2016-01-01
Summary The ability to three-dimensionally interweave biological and functional materials could enable the creation of bionic devices possessing unique and compelling geometries, properties, and functionalities. Indeed, interfacing high performance active devices with biology could impact a variety of fields, including regenerative bioelectronic medicines, smart prosthetics, medical robotics, and human-machine interfaces. Biology, from the molecular scale of DNA and proteins, to the macroscopic scale of tissues and organs, is three-dimensional, often soft and stretchable, and temperature sensitive. This renders most biological platforms incompatible with the fabrication and materials processing methods that have been developed and optimized for functional electronics, which are typically planar, rigid and brittle. A number of strategies have been developed to overcome these dichotomies. One particularly novel approach is the use of extrusion-based multi-material 3D printing, which is an additive manufacturing technology that offers a freeform fabrication strategy. This approach addresses the dichotomies presented above by (1) using 3D printing and imaging for customized, hierarchical, and interwoven device architectures; (2) employing nanotechnology as an enabling route for introducing high performance materials, with the potential for exhibiting properties not found in the bulk; and (3) 3D printing a range of soft and nanoscale materials to enable the integration of a diverse palette of high quality functional nanomaterials with biology. Further, 3D printing is a multi-scale platform, allowing for the incorporation of functional nanoscale inks, the printing of microscale features, and ultimately the creation of macroscale devices. This blending of 3D printing, novel nanomaterial properties, and ‘living’ platforms may enable next-generation bionic systems. In this review, we highlight this synergistic integration of the unique properties of nanomaterials with
Van Goethem, Emeline; Guiet, Romain; Balor, Stéphanie; Charrière, Guillaume M; Poincloux, Renaud; Labrousse, Arnaud; Maridonneau-Parini, Isabelle; Le Cabec, Véronique
2011-01-01
Macrophage tissue infiltration is a critical step in the immune response against microorganisms and is also associated with disease progression in chronic inflammation and cancer. Macrophages are constitutively equipped with specialized structures called podosomes dedicated to extracellular matrix (ECM) degradation. We recently reported that these structures play a critical role in trans-matrix mesenchymal migration mode, a protease-dependent mechanism. Podosome molecular components and their ECM-degrading activity have been extensively studied in two dimensions (2D), but yet very little is known about their fate in three-dimensional (3D) environments. Therefore, localization of podosome markers and proteolytic activity were carefully examined in human macrophages performing mesenchymal migration. Using our gelled collagen I 3D matrix model to obligate human macrophages to perform mesenchymal migration, classical podosome markers including talin, paxillin, vinculin, gelsolin, cortactin were found to accumulate at the tip of F-actin-rich cell protrusions together with β1 integrin and CD44 but not β2 integrin. Macrophage proteolytic activity was observed at podosome-like protrusion sites using confocal fluorescence microscopy and electron microscopy. The formation of migration tunnels by macrophages inside the matrix was accomplished by degradation, engulfment and mechanic compaction of the matrix. In addition, videomicroscopy revealed that 3D F-actin-rich protrusions of migrating macrophages were as dynamic as their 2D counterparts. Overall, the specifications of 3D podosomes resembled those of 2D podosome rosettes rather than those of individual podosomes. This observation was further supported by the aspect of 3D podosomes in fibroblasts expressing Hck, a master regulator of podosome rosettes in macrophages. In conclusion, human macrophage podosomes go 3D and take the shape of spherical podosome rosettes when the cells perform mesenchymal migration. This work
3D Computations and Experiments
Couch, R; Faux, D; Goto, D; Nikkel, D
2004-04-05
This project consists of two activities. Task A, Simulations and Measurements, combines all the material model development and associated numerical work with the materials-oriented experimental activities. The goal of this effort is to provide an improved understanding of dynamic material properties and to provide accurate numerical representations of those properties for use in analysis codes. Task B, ALE3D Development, involves general development activities in the ALE3D code with the focus of improving simulation capabilities for problems of mutual interest to DoD and DOE. Emphasis is on problems involving multi-phase flow, blast loading of structures and system safety/vulnerability studies.
NASA Technical Reports Server (NTRS)
1997-01-01
Portions of the lander's deflated airbags and a petal are at the lower area of this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. The metallic object at lower right is part of the lander's low-gain antenna. This image is part of a 3D 'monster
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
NASA Technical Reports Server (NTRS)
1997-01-01
Portions of the lander's deflated airbags and a petal are at the lower area of this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. The metallic object at lower right is part of the lander's low-gain antenna. This image is part of a 3D 'monster
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
Magnetohydrodynamics in Materials Processing
NASA Astrophysics Data System (ADS)
Davidson, P. A.
1999-01-01
Magnetic fields can be used to melt, pump, stir, and stabilize liquid metals. This provides a nonintrusive means of controlling the flow of metal in commercial casting and refining operations. The quest for greater efficiency and more control in the production of steel, aluminum, and high-performance superalloys has led to a revolution in the application of magnetohydrodynamics (MHD) to process metallurgy. Three typical applications are described here, chosen partially on the basis of their general interest to fluid dynamicists, and partially because of their considerable industrial importance. We look first at magnetic stirring, where a rotating magnetic field is used to agitate and homogenize the liquid zone of a partially-solidified ingot. This is a study in Ekman pumping. Next, we consider magnetic damping, where an intense, static magnetic field is used to suppress fluid motion. In particular, we look at the damping of jets, vortices, and turbulence. We conclude with a discussion of the magnetic destabilization of liquid-liquid interfaces. This is of particular importance in aluminum production.
Multi-symplectic magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Webb, G. M.; McKenzie, J. F.; Zank, G. P.; Zank
2014-10-01
A multi-symplectic formulation of ideal magnetohydrodynamics (MHD) is developed based on the Clebsch variable variational principle in which the Lagrangian consists of the kinetic minus the potential energy of the MHD fluid modified by constraints using Lagrange multipliers that ensure mass conservation, entropy advection with the flow, the Lin constraint, and Faraday's equation (i.e. the magnetic flux is Lie dragged with the flow). The analysis is also carried out using the magnetic vector potential Ã where α=Ã. d x is Lie dragged with the flow, and B=∇×Ã. The multi-symplectic conservation laws give rise to the Eulerian momentum and energy conservation laws. The symplecticity or structural conservation laws for the multi-symplectic system corresponds to the conservation of phase space. It corresponds to taking derivatives of the momentum and energy conservation laws and combining them to produce n(n-1)/2 extra conservation laws, where n is the number of independent variables. Noether's theorem for the multi-symplectic MHD system is derived, including the case of non-Cartesian space coordinates, where the metric plays a role in the equations.
Generalized reduced magnetohydrodynamic equations
Kruger, S.E.
1999-02-01
A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-Alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson. The equations have been programmed into a spectral initial value code and run with shear flow that is consistent with the equilibrium input into the code. Linear results of tearing modes with shear flow are presented which differentiate the effects of shear flow gradients in the layer with the effects of the shear flow decoupling multiple harmonics.
Filamentary magnetohydrodynamic plasmas
Kinney, R.; Tajima, T.; Petviashvili, N.; McWilliams, J.C.
1993-05-01
A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to ones based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected. the plasma vortex system is described by a Hamiltonian. For a system with many such vortices we present a statistical treatment of a collection of discrete current-vorticity concentrations. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories. but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected.
3D Printing: Exploring Capabilities
ERIC Educational Resources Information Center
Samuels, Kyle; Flowers, Jim
2015-01-01
As 3D printers become more affordable, schools are using them in increasing numbers. They fit well with the emphasis on product design in technology and engineering education, allowing students to create high-fidelity physical models to see and test different iterations in their product designs. They may also help students to "think in three…
2010-02-23
This anaglyph from images captured by NASA Cassini spacecraft shows a dramatic, 3-D view of one of the deep fractures nicknamed tiger stripes on Saturn moon Enceladus which are located near the moon south pole, spray jets of water ice.
3D Printing: Exploring Capabilities
ERIC Educational Resources Information Center
Samuels, Kyle; Flowers, Jim
2015-01-01
As 3D printers become more affordable, schools are using them in increasing numbers. They fit well with the emphasis on product design in technology and engineering education, allowing students to create high-fidelity physical models to see and test different iterations in their product designs. They may also help students to "think in three…
ERIC Educational Resources Information Center
Manos, Harry
2016-01-01
Visual aids are important to student learning, and they help make the teacher's job easier. Keeping with the "TPT" theme of "The Art, Craft, and Science of Physics Teaching," the purpose of this article is to show how teachers, lacking equipment and funds, can construct a durable 3-D model reference frame and a model gravity…
1999-06-25
Ganges Chasma is part of the Valles Marineris trough system that stretches nearly 5,000 kilometers 3,000 miles across the western equatorial region of Mars. This stereo anaglyph is from NASA Mars Global Surveyor. 3D glasses are necessary.
2004-02-02
This is a three-dimensional stereo anaglyph of an image taken by the front hazard-identification camera onboard NASA Mars Exploration Rover Opportunity, showing the rover arm in its extended position. 3D glasses are necessary to view this image.
ERIC Educational Resources Information Center
Manos, Harry
2016-01-01
Visual aids are important to student learning, and they help make the teacher's job easier. Keeping with the "TPT" theme of "The Art, Craft, and Science of Physics Teaching," the purpose of this article is to show how teachers, lacking equipment and funds, can construct a durable 3-D model reference frame and a model gravity…
ERIC Educational Resources Information Center
Mayshark, Robin K.
1991-01-01
Students explore three-dimensional properties by creating red and green wall decorations related to Christmas. Students examine why images seem to vibrate when red and green pieces are small and close together. Instructions to conduct the activity and construct 3-D glasses are given. (MDH)
2014-11-21
A 3D image shows what it would look like to fly over the surface of comet 67P/Churyumov-Gerasimenko. The image was generated by data collected by ESA Philae spacecraft during the decent to the spacecraft initial touchdown on the comet Nov. 12, 2014.
Russ, Trina; Koch, Mark; Koudelka, Melissa; Peters, Ralph; Little, Charles; Boehnen, Chris; Peters, Tanya
2007-07-20
This software distribution contains MATLAB and C++ code to enable identity verification using 3D images that may or may not contain a texture component. The code is organized to support system performance testing and system capability demonstration through the proper configuration of the available user interface. Using specific algorithm parameters the face recognition system has been demonstrated to achieve a 96.6% verification rate (Pd) at 0.001 false alarm rate. The system computes robust facial features of a 3D normalized face using Principal Component Analysis (PCA) and Fisher Linear Discriminant Analysis (FLDA). A 3D normalized face is obtained by alighning each face, represented by a set of XYZ coordinated, to a scaled reference face using the Iterative Closest Point (ICP) algorithm. The scaled reference face is then deformed to the input face using an iterative framework with parameters that control the deformed surface regulation an rate of deformation. A variety of options are available to control the information that is encoded by the PCA. Such options include the XYZ coordinates, the difference of each XYZ coordinates from the reference, the Z coordinate, the intensity/texture values, etc. In addition to PCA/FLDA feature projection this software supports feature matching to obtain similarity matrices for performance analysis. In addition, this software supports visualization of the STL, MRD, 2D normalized, and PCA synthetic representations in a 3D environment.
Allen, M.A.; Azuma, O.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Hoag, H.A.; Koontz, R.F.
1989-03-01
Experimental work is underway by a SLAC-LLNL-LBL collaboration to investigate the feasibility of using relativistic klystrons as a power source for future high gradient accelerators. Two different relativistic klystron configurations have been built and tested to date: a high grain multicavity klystron at 11.4 GHz and a low gain two cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, we have used both a single resonant cavity and a multi-cell traveling wave structure for energy extraction. We have learned how to overcome our previously reported problem of high power RF pulse shortening, and have achieved peak RF power levels of 170 MW with the RF pulse of the same duration as the beam current pulse. 6 refs., 3 figs., 3 tabs.
NASA Astrophysics Data System (ADS)
Flury, J.
2016-06-01
Quantum metrology enables new applications in geodesy, including relativistic geodesy. The recent progress in optical atomic clocks and in long-distance frequency transfer by optical fiber together pave the way for using measurements of the gravitational frequency redshift for geodesy. The remote comparison of frequencies generated by calibrated clocks will allow for a purely relativistic determination of differences in gravitational potential and height between stations on Earth surface (chronometric leveling). The long-term perspective is to tie potential and height differences to atomic standards in order to overcome the weaknesses and inhomogeneity of height systems determined by classical spirit leveling. Complementarily, gravity measurements with atom interferometric setups, and satellite gravimetry with space borne laser interferometers allow for new sensitivities in the measurement of the Earth's gravity field.
TACO3D. 3-D Finite Element Heat Transfer Code
Mason, W.E.
1992-03-04
TACO3D is a three-dimensional, finite-element program for heat transfer analysis. An extension of the two-dimensional TACO program, it can perform linear and nonlinear analyses and can be used to solve either transient or steady-state problems. The program accepts time-dependent or temperature-dependent material properties, and materials may be isotropic or orthotropic. A variety of time-dependent and temperature-dependent boundary conditions and loadings are available including temperature, flux, convection, and radiation boundary conditions and internal heat generation. Additional specialized features treat enclosure radiation, bulk nodes, and master/slave internal surface conditions (e.g., contact resistance). Data input via a free-field format is provided. A user subprogram feature allows for any type of functional representation of any independent variable. A profile (bandwidth) minimization option is available. The code is limited to implicit time integration for transient solutions. TACO3D has no general mesh generation capability. Rows of evenly-spaced nodes and rows of sequential elements may be generated, but the program relies on separate mesh generators for complex zoning. TACO3D does not have the ability to calculate view factors internally. Graphical representation of data in the form of time history and spatial plots is provided through links to the POSTACO and GRAPE postprocessor codes.
3D GRMHD and GRPIC Simulations of Disk-Jet Coupling and Emission
Nishikawa, Ken-Ichi; Mizuno, Y.; Watson, M.; Hardee, P.; Fuerst, S.; Wu, K.; Fishman, G.J.; /NASA, Marshall
2006-12-19
We investigate jet formation in black-hole systems using 3-D General Relativistic Particle-In-Cell (GRPIC) and 3-D GRMHD simulations. GRPIC simulations, which allow charge separations in a collisionless plasma, do not need to invoke the frozen condition as in GRMHD simulations. 3-D GRPIC simulations show that jets are launched from Kerr black holes as in 3-D GRMHD simulations, but jet formation in the two cases may not be identical. Comparative study of black hole systems with GRPIC and GRMHD simulations with the inclusion of radiate transfer will further clarify the mechanisms that drive the evolution of disk-jet systems.
Solar Flares: Magnetohydrodynamic Processes
NASA Astrophysics Data System (ADS)
Shibata, Kazunari; Magara, Tetsuya
2011-12-01
This paper outlines the current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD) processes responsible for producing a flare. Observations show that flares are one of the most explosive phenomena in the atmosphere of the Sun, releasing a huge amount of energy up to about 1032 erg on the timescale of hours. Flares involve the heating of plasma, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes for producing a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence), local enhancement of electric current in the corona (formation of a current sheet), and rapid dissipation of electric current (magnetic reconnection) that causes shock heating, mass ejection, and particle acceleration. The evolution toward the onset of a flare is rather quasi-static when free energy is accumulated in the form of coronal electric current (field-aligned current, more precisely), while the dissipation of coronal current proceeds rapidly, producing various dynamic events that affect lower atmospheres such as the chromosphere and photosphere. Flares manifest such rapid dissipation of coronal current, and their theoretical modeling has been developed in accordance with observations, in which numerical simulations proved to be a strong tool reproducing the time-dependent, nonlinear evolution of a flare. We review the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes mentioned above. We start with basic properties of flares, then go into the details of energy build-up, release and transport in flares where magnetic reconnection works as the central engine to produce a flare.
Compressible magnetohydrodynamic sawtooth crash
NASA Astrophysics Data System (ADS)
Sugiyama, Linda E.
2014-02-01
In a toroidal magnetically confined plasma at low resistivity, compressible magnetohydrodynamic (MHD) predicts that an m = 1/n = 1 sawtooth has a fast, explosive crash phase with abrupt onset, rate nearly independent of resistivity, and localized temperature redistribution similar to experimental observations. Large scale numerical simulations show that the 1/1 MHD internal kink grows exponentially at a resistive rate until a critical amplitude, when the plasma motion accelerates rapidly, culminating in fast loss of the temperature and magnetic structure inside q < 1, with somewhat slower density redistribution. Nonlinearly, for small effective growth rate the perpendicular momentum rate of change remains small compared to its individual terms ∇p and J × B until the fast crash, so that the compressible growth rate is determined by higher order terms in a large aspect ratio expansion, as in the linear eigenmode. Reduced MHD fails completely to describe the toroidal mode; no Sweet-Parker-like reconnection layer develops. Important differences result from toroidal mode coupling effects. A set of large aspect ratio compressible MHD equations shows that the large aspect ratio expansion also breaks down in typical tokamaks with rq =1/Ro≃1/10 and a /Ro≃1/3. In the large aspect ratio limit, failure extends down to much smaller inverse aspect ratio, at growth rate scalings γ =O(ɛ2). Higher order aspect ratio terms, including B˜ϕ, become important. Nonlinearly, higher toroidal harmonics develop faster and to a greater degree than for large aspect ratio and help to accelerate the fast crash. The perpendicular momentum property applies to other transverse MHD instabilities, including m ≥ 2 magnetic islands and the plasma edge.
NASA Astrophysics Data System (ADS)
Jones, Bernard J. T.; Markovic, Dragoljub
1997-06-01
Preface; Prologue: Conference overview Bernard Carr; Part I. The Universe At Large and Very Large Redshifts: 2. The size and age of the Universe Gustav A. Tammann; 3. Active galaxies at large redshifts Malcolm S. Longair; 4. Observational cosmology with the cosmic microwave background George F. Smoot; 5. Future prospects in measuring the CMB power spectrum Philip M. Lubin; 6. Inflationary cosmology Michael S. Turner; 7. The signature of the Universe Bernard J. T. Jones; 8. Theory of large-scale structure Sergei F. Shandarin; 9. The origin of matter in the universe Lev A. Kofman; 10. New guises for cold-dark matter suspects Edward W. Kolb; Part II. Physics and Astrophysics Of Relativistic Compact Objects: 11. On the unification of gravitational and inertial forces Donald Lynden-Bell; 12. Internal structure of astrophysical black holes Werner Israel; 13. Black hole entropy: external facade and internal reality Valery Frolov; 14. Accretion disks around black holes Marek A. Abramowicz; 15. Black hole X-ray transients J. Craig Wheeler; 16. X-rays and gamma rays from active galactic nuclei Roland Svensson; 17. Gamma-ray bursts: a challenge to relativistic astrophysics Martin Rees; 18. Probing black holes and other exotic objects with gravitational waves Kip Thorne; Epilogue: the past and future of relativistic astrophysics Igor D. Novikov; I. D. Novikov's scientific papers and books.
NASA Technical Reports Server (NTRS)
Fuerst, Steven V.; Mizuno, Yosuke; Nishikawa, Ken-Ichi; Wu, Kinwah
2007-01-01
We have calculated the emission from relativistic flows in black hole systems using a fully general relativistic radiative transfer, with flow structures obtained by general relativistic magnetohydrodynamic simulations. We consider thermal free-free emission and thermal synchrotron emission. Bright filament-like features are found protruding (visually) from the accretion disk surface, which are enhancements of synchrotron emission when the magnetic field is roughly aligned with the line-of-sight in the co-moving frame. The features move back and forth as the accretion flow evolves, but their visibility and morphology are robust. We propose that variations and location drifts of the features are responsible for certain X-ray quasi-periodic oscillations (QPOs) observed in black-hole X-ray binaries.
Generalized global symmetries and dissipative magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Grozdanov, Sašo; Hofman, Diego M.; Iqbal, Nabil
2017-05-01
The conserved magnetic flux of U (1 ) electrodynamics coupled to matter in four dimensions is associated with a generalized global symmetry. We study the realization of such a symmetry at finite temperature and develop the hydrodynamic theory describing fluctuations of a conserved 2-form current around thermal equilibrium. This can be thought of as a systematic derivation of relativistic magnetohydrodynamics, constrained only by symmetries and effective field theory. We construct the entropy current and show that at first order in derivatives, there are seven dissipative transport coefficients. We present a universal definition of resistivity in a theory of dynamical electromagnetism and derive a direct Kubo formula for the resistivity in terms of correlation functions of the electric field operator. We also study fluctuations and collective modes, deriving novel expressions for the dissipative widths of magnetosonic and Alfvén modes. Finally, we demonstrate that a nontrivial truncation of the theory can be performed at low temperatures compared to the magnetic field: this theory has an emergent Lorentz invariance along magnetic field lines, and hydrodynamic fluctuations are now parametrized by a fluid tensor rather than a fluid velocity. Throughout, no assumption is made of weak electromagnetic coupling. Thus, our theory may have phenomenological relevance for dense electromagnetic plasmas.
Forensic 3D scene reconstruction
NASA Astrophysics Data System (ADS)
Little, Charles Q.; Small, Daniel E.; Peters, Ralph R.; Rigdon, J. B.
2000-05-01
Traditionally law enforcement agencies have relied on basic measurement and imaging tools, such as tape measures and cameras, in recording a crime scene. A disadvantage of these methods is that they are slow and cumbersome. The development of a portable system that can rapidly record a crime scene with current camera imaging, 3D geometric surface maps, and contribute quantitative measurements such as accurate relative positioning of crime scene objects, would be an asset to law enforcement agents in collecting and recording significant forensic data. The purpose of this project is to develop a fieldable prototype of a fast, accurate, 3D measurement and imaging system that would support law enforcement agents to quickly document and accurately record a crime scene.
NASA Technical Reports Server (NTRS)
Pizarro, Yaritzmar Rosario; Schuler, Jason M.; Lippitt, Thomas C.
2013-01-01
Dexterous robotic hands are changing the way robots and humans interact and use common tools. Unfortunately, the complexity of the joints and actuations drive up the manufacturing cost. Some cutting edge and commercially available rapid prototyping machines now have the ability to print multiple materials and even combine these materials in the same job. A 3D model of a robotic hand was designed using Creo Parametric 2.0. Combining "hard" and "soft" materials, the model was printed on the Object Connex350 3D printer with the purpose of resembling as much as possible the human appearance and mobility of a real hand while needing no assembly. After printing the prototype, strings where installed as actuators to test mobility. Based on printing materials, the manufacturing cost of the hand was $167, significantly lower than other robotic hands without the actuators since they have more complex assembly processes.
Forensic 3D Scene Reconstruction
LITTLE,CHARLES Q.; PETERS,RALPH R.; RIGDON,J. BRIAN; SMALL,DANIEL E.
1999-10-12
Traditionally law enforcement agencies have relied on basic measurement and imaging tools, such as tape measures and cameras, in recording a crime scene. A disadvantage of these methods is that they are slow and cumbersome. The development of a portable system that can rapidly record a crime scene with current camera imaging, 3D geometric surface maps, and contribute quantitative measurements such as accurate relative positioning of crime scene objects, would be an asset to law enforcement agents in collecting and recording significant forensic data. The purpose of this project is to develop a feasible prototype of a fast, accurate, 3D measurement and imaging system that would support law enforcement agents to quickly document and accurately record a crime scene.
NASA Technical Reports Server (NTRS)
Wade, Michael O. (Inventor); Poland, Jr., James W. (Inventor)
2003-01-01
A ratcheting device comprising a driver head assembly which includes at least two 3-D sprag elements positioned within a first groove within the driver head assembly such that at least one of the 3-D sprag elements may lockingly engage the driver head assembly and a mating hub assembly to allow for rotation of the hub assembly in one direction with respect to the driver head assembly. This arrangement allows the ratcheting tool to impart torque in either the clockwise or counterclockwise direction without having to first rotate the ratcheting tool in the direction opposite the direction in which the torque is applied. This arrangement also allows the ratcheting tool to impart torque in either the clockwise or counterclockwise direction while in the neutral position.
van Geer, Erik; Molenbroek, Johan; Schreven, Sander; deVoogd-Claessen, Lenneke; Toussaint, Huib
2012-01-01
In competitive swimming, suits have become more important. These suits influence friction, pressure and wave drag. Friction drag is related to the surface properties whereas both pressure and wave drag are greatly influenced by body shape. To find a relationship between the body shape and the drag, the anthropometry of several world class female swimmers wearing different suits was accurately defined using a 3D scanner and traditional measuring methods. The 3D scans delivered more detailed information about the body shape. On the same day the swimmers did performance tests in the water with the tested suits. Afterwards the result of the performance tests and the differences found in body shape was analyzed to determine the deformation caused by a swimsuit and its effect on the swimming performance. Although the amount of data is limited because of the few test subjects, there is an indication that the deformation of the body influences the swimming performance.
Belenkov, E. A. Ali-Pasha, V. A.
2011-01-15
The structure of clusters of some new carbon 3D-graphite phases have been calculated using the molecular-mechanics methods. It is established that 3D-graphite polytypes {alpha}{sub 1,1}, {alpha}{sub 1,3}, {alpha}{sub 1,5}, {alpha}{sub 2,1}, {alpha}{sub 2,3}, {alpha}{sub 3,1}, {beta}{sub 1,2}, {beta}{sub 1,4}, {beta}{sub 1,6}, {beta}{sub 2,1}, and {beta}{sub 3,2} consist of sp{sup 2}-hybridized atoms, have hexagonal unit cells, and differ in regards to the structure of layers and order of their alternation. A possible way to experimentally synthesize new carbon phases is proposed: the polymerization and carbonization of hydrocarbon molecules.
VizieR Online Data Catalog: STAGGER-grid of 3D stellar models. I. (Magic+, 2013)
NASA Astrophysics Data System (ADS)
Magic, Z.; Collet, R.; Asplund, M.; Trampedach, R.; Hayek, W.; Chiavassa, A.; Stein, R. F.; Nordlund, A.
2013-07-01
The 3D model atmospheres presented here were constructed with a custom version of the Stagger-code, a state-of-the-art, multipurpose, radiative-magnetohydrodynamics (R-MHD) code originally developed by Nordlund & Galsgaard (1995, http://www.astro.ku.dk/~kg/Papers/MHD_code.ps.gz), and continuously improved over the years by its user community. (1 data file).
[Real time 3D echocardiography
NASA Technical Reports Server (NTRS)
Bauer, F.; Shiota, T.; Thomas, J. D.
2001-01-01
Three-dimensional representation of the heart is an old concern. Usually, 3D reconstruction of the cardiac mass is made by successive acquisition of 2D sections, the spatial localisation and orientation of which require complex guiding systems. More recently, the concept of volumetric acquisition has been introduced. A matricial emitter-receiver probe complex with parallel data processing provides instantaneous of a pyramidal 64 degrees x 64 degrees volume. The image is restituted in real time and is composed of 3 planes (planes B and C) which can be displaced in all spatial directions at any time during acquisition. The flexibility of this system of acquisition allows volume and mass measurement with greater accuracy and reproducibility, limiting inter-observer variability. Free navigation of the planes of investigation allows reconstruction for qualitative and quantitative analysis of valvular heart disease and other pathologies. Although real time 3D echocardiography is ready for clinical usage, some improvements are still necessary to improve its conviviality. Then real time 3D echocardiography could be the essential tool for understanding, diagnosis and management of patients.
[Real time 3D echocardiography
NASA Technical Reports Server (NTRS)
Bauer, F.; Shiota, T.; Thomas, J. D.
2001-01-01
Three-dimensional representation of the heart is an old concern. Usually, 3D reconstruction of the cardiac mass is made by successive acquisition of 2D sections, the spatial localisation and orientation of which require complex guiding systems. More recently, the concept of volumetric acquisition has been introduced. A matricial emitter-receiver probe complex with parallel data processing provides instantaneous of a pyramidal 64 degrees x 64 degrees volume. The image is restituted in real time and is composed of 3 planes (planes B and C) which can be displaced in all spatial directions at any time during acquisition. The flexibility of this system of acquisition allows volume and mass measurement with greater accuracy and reproducibility, limiting inter-observer variability. Free navigation of the planes of investigation allows reconstruction for qualitative and quantitative analysis of valvular heart disease and other pathologies. Although real time 3D echocardiography is ready for clinical usage, some improvements are still necessary to improve its conviviality. Then real time 3D echocardiography could be the essential tool for understanding, diagnosis and management of patients.
GPU-Accelerated Denoising in 3D (GD3D)
2013-10-01
The raw computational power GPU Accelerators enables fast denoising of 3D MR images using bilateral filtering, anisotropic diffusion, and non-local means. This software addresses two facets of this promising application: what tuning is necessary to achieve optimal performance on a modern GPU? And what parameters yield the best denoising results in practice? To answer the first question, the software performs an autotuning step to empirically determine optimal memory blocking on the GPU. To answer the second, it performs a sweep of algorithm parameters to determine the combination that best reduces the mean squared error relative to a noiseless reference image.
GPU-Accelerated Denoising in 3D (GD3D)
2013-10-01
The raw computational power GPU Accelerators enables fast denoising of 3D MR images using bilateral filtering, anisotropic diffusion, and non-local means. This software addresses two facets of this promising application: what tuning is necessary to achieve optimal performance on a modern GPU? And what parameters yield the best denoising results in practice? To answer the first question, the software performs an autotuning step to empirically determine optimal memory blocking on the GPU. To answer the second, it performs a sweep of algorithm parameters to determine the combination that best reduces the mean squared error relative to a noiseless reference image.
[Nonlinear magnetohydrodynamics]. Final report
Montgomery, D.C.
1998-11-01
This is a final report on the research activities carried out under the above grant at Dartmouth. During the period considered, the grant was identified as being for nonlinear magnetohydrodynamics, considered as the most tractable theoretical framework in which the plasma problems associated with magnetic confinement of fusion plasmas could be studied. During the first part of the grant`s lifetime, the author was associated with Los Alamos National Laboratory as a consultant and the work was motivated by the reversed-field pinch. Later, when that program was killed at Los Alamos, the problems became ones that could be motivated by their relation to tokamaks. Throughout the work, the interest was always on questions that were as fundamental as possible, compatible with those motivations. The intent was always to contribute to plasma physics as a science, as well as to the understanding of mission-oriented confined fusion plasmas. Twelve Ph.D. theses were supervised during this period and a comparable number of postdoctoral research associates were temporarily supported. Many of these have gone on to distinguished careers, though few have done so in the context of the controlled fusion program. Their work was a combination of theory and numerical computation, in gradually less and less idealized settings, moving from rectangular periodic boundary conditions in two dimensions, through periodic straight cylinders and eventually, before the grant was withdrawn, to toroids, with a gradually more prominent role for electrical and mechanical boundary conditions. The author never had access to a situation where he could initiate experiments and relate directly to the laboratory data he wanted. Computers were the laboratory. Most of the work was reported in referred publications in the open literature, copies of which were transmitted one by one to DOE at the time they appeared. The Appendix to this report is a bibliography of published work which was carried out under the
NASA Astrophysics Data System (ADS)
Kent, G. M.; Harding, A. J.; Babcock, J. M.; Orcutt, J. A.; Bazin, S.; Singh, S.; Detrick, R. S.; Canales, J. P.; Carbotte, S. M.; Diebold, J.
2002-12-01
Multichannel seismic (MCS) images of crustal magma chambers are ideal targets for advanced visualization techniques. In the mid-ocean ridge environment, reflections originating at the melt-lens are well separated from other reflection boundaries, such as the seafloor, layer 2A and Moho, which enables the effective use of transparency filters. 3-D visualization of seismic reflectivity falls into two broad categories: volume and surface rendering. Volumetric-based visualization is an extremely powerful approach for the rapid exploration of very dense 3-D datasets. These 3-D datasets are divided into volume elements or voxels, which are individually color coded depending on the assigned datum value; the user can define an opacity filter to reject plotting certain voxels. This transparency allows the user to peer into the data volume, enabling an easy identification of patterns or relationships that might have geologic merit. Multiple image volumes can be co-registered to look at correlations between two different data types (e.g., amplitude variation with offsets studies), in a manner analogous to draping attributes onto a surface. In contrast, surface visualization of seismic reflectivity usually involves producing "fence" diagrams of 2-D seismic profiles that are complemented with seafloor topography, along with point class data, draped lines and vectors (e.g. fault scarps, earthquake locations and plate-motions). The overlying seafloor can be made partially transparent or see-through, enabling 3-D correlations between seafloor structure and seismic reflectivity. Exploration of 3-D datasets requires additional thought when constructing and manipulating these complex objects. As numbers of visual objects grow in a particular scene, there is a tendency to mask overlapping objects; this clutter can be managed through the effective use of total or partial transparency (i.e., alpha-channel). In this way, the co-variation between different datasets can be investigated
NASA Astrophysics Data System (ADS)
Deng, Wei; Li, Hui; Zhang, Bing; Li, Shengtai
2015-06-01
We perform 3D relativistic ideal magnetohydrodynamics (MHD) simulations to study the collisions between high-σ (Poynting-flux-dominated (PFD)) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable PFD jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvénic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in the relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. Our results give support to the proposed astrophysical models that invoke significant magnetic energy dissipation in PFD jets, such as the internal collision-induced magnetic reconnection and turbulence model for gamma-ray bursts, and reconnection triggered mini jets model for active galactic nuclei. The simulation movies are shown in http://www.physics.unlv.edu/∼deng/simulation1.html.
Deng, Wei; Zhang, Bing; Li, Hui; Li, Shengtai E-mail: zhang@physics.unlv.edu E-mail: sli@lanl.gov
2015-06-01
We perform 3D relativistic ideal magnetohydrodynamics (MHD) simulations to study the collisions between high-σ (Poynting-flux-dominated (PFD)) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable PFD jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvénic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in the relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. Our results give support to the proposed astrophysical models that invoke significant magnetic energy dissipation in PFD jets, such as the internal collision-induced magnetic reconnection and turbulence model for gamma-ray bursts, and reconnection triggered mini jets model for active galactic nuclei. The simulation movies are shown in http://www.physics.unlv.edu/∼deng/simulation1.html.
MHD instabilities in accretion mounds - II. 3D simulations
NASA Astrophysics Data System (ADS)
Mukherjee, Dipanjan; Bhattacharya, Dipankar; Mignone, Andrea
2013-10-01
We investigate the onset of pressure-driven toroidal-mode instabilities in accretion mounds on neutron stars by 3D magnetohydrodynamic (MHD) simulations using the PLUTO MHD code. Our results confirm that for mounds beyond a threshold mass, instabilities form finger-like channels at the periphery, resulting in mass-loss from the magnetically confined mound. Ring-like mounds with hollow interior show the instabilities at the inner edge as well. We perform the simulations for mounds of different sizes to investigate the effect of the mound mass on the growth rate of the instabilities. We also investigate the effect of such instabilities on observables such as cyclotron resonant scattering features and timing properties of such systems.
Intermittent dissipation and heating in 3D kinetic plasma turbulence
NASA Astrophysics Data System (ADS)
Wan, M.; Matthaeus, W. H.; Roytershteyn, V.; Karimabadi, H.; Parashar, T.; Wu, P.; Shay, M. A.
2014-12-01
The nature of collisionless dissipation has been hotlydebated in recent years, with alternative ideas posed interms of various wave modes, such as kinetic Alfven waves,whistlers, linear Vlasov instabilities, cyclotron resonance,and Landau damping. Here we use large scale, fully kinetic3D simulations of collisionless plasma turbulence which showthe development of turbulence characterized by sheet-likecurrent density structures spanning a range of scales.We present evidence that these structures are sites for heatingand dissipation, and that stronger current structures signifyhigher dissipation rates. The analyses focus on quantities such as J.E, electron and proton temperatures, and PVI of the magnetic field. Evidently, kinetic scale plasma,like magnetohydrodynamics, becomes intermittent due tocurrent sheet formation, leading to the expectationthat heating and dissipation in astrophysical and space plasmasmay be highly nonuniform. Comparison with previousresults from 2D kinetic simulations, as well as high frequencysolar wind observational data will also be discussed.
Interactive 3D Mars Visualization
NASA Technical Reports Server (NTRS)
Powell, Mark W.
2012-01-01
The Interactive 3D Mars Visualization system provides high-performance, immersive visualization of satellite and surface vehicle imagery of Mars. The software can be used in mission operations to provide the most accurate position information for the Mars rovers to date. When integrated into the mission data pipeline, this system allows mission planners to view the location of the rover on Mars to 0.01-meter accuracy with respect to satellite imagery, with dynamic updates to incorporate the latest position information. Given this information so early in the planning process, rover drivers are able to plan more accurate drive activities for the rover than ever before, increasing the execution of science activities significantly. Scientifically, this 3D mapping information puts all of the science analyses to date into geologic context on a daily basis instead of weeks or months, as was the norm prior to this contribution. This allows the science planners to judge the efficacy of their previously executed science observations much more efficiently, and achieve greater science return as a result. The Interactive 3D Mars surface view is a Mars terrain browsing software interface that encompasses the entire region of exploration for a Mars surface exploration mission. The view is interactive, allowing the user to pan in any direction by clicking and dragging, or to zoom in or out by scrolling the mouse or touchpad. This set currently includes tools for selecting a point of interest, and a ruler tool for displaying the distance between and positions of two points of interest. The mapping information can be harvested and shared through ubiquitous online mapping tools like Google Mars, NASA WorldWind, and Worldwide Telescope.
High-Speed Magnetohydrodynamic Flow Control Analyses With 3-D Simulations
2008-01-01
shock/boundary layer interactions. A series of previous papers (e.g., Refs.25, 26) have demonstrated the capability of the scheme, through exhaustive... electromotive force of the boundary layer recovering after stagnation. The electrodeless configurations yield considerably lower Joule heating rates and
MERIDIONAL CIRCULATION DYNAMICS FROM 3D MAGNETOHYDRODYNAMIC GLOBAL SIMULATIONS OF SOLAR CONVECTION
Passos, Dário; Charbonneau, Paul; Miesch, Mark
2015-02-10
The form of solar meridional circulation is a very important ingredient for mean field flux transport dynamo models. However, a shroud of mystery still surrounds this large-scale flow, given that its measurement using current helioseismic techniques is challenging. In this work, we use results from three-dimensional global simulations of solar convection to infer the dynamical behavior of the established meridional circulation. We make a direct comparison between the meridional circulation that arises in these simulations and the latest observations. Based on our results, we argue that there should be an equatorward flow at the base of the convection zone at mid-latitudes, below the current maximum depth helioseismic measures can probe (0.75 R{sub ⊙}). We also provide physical arguments to justify this behavior. The simulations indicate that the meridional circulation undergoes substantial changes in morphology as the magnetic cycle unfolds. We close by discussing the importance of these dynamical changes for current methods of observation which involve long averaging periods of helioseismic data. Also noteworthy is the fact that these topological changes indicate a rich interaction between magnetic fields and plasma flows, which challenges the ubiquitous kinematic approach used in the vast majority of mean field dynamo simulations.
NASA Technical Reports Server (NTRS)
2004-01-01
This is a 3-D anaglyph showing a microscopic image taken of an area measuring 3 centimeters (1.2 inches) across on the rock called Adirondack. The image was taken at Gusev Crater on the 33rd day of the Mars Exploration Rover Spirit's journey (Feb. 5, 2004), after the rover used its rock abrasion tool brush to clean the surface of the rock. Dust, which was pushed off to the side during cleaning, can still be seen to the left and in low areas of the rock.
NASA Technical Reports Server (NTRS)
2004-01-01
This is a 3-D anaglyph showing a microscopic image taken of an area measuring 3 centimeters (1.2 inches) across on the rock called Adirondack. The image was taken at Gusev Crater on the 33rd day of the Mars Exploration Rover Spirit's journey (Feb. 5, 2004), after the rover used its rock abrasion tool brush to clean the surface of the rock. Dust, which was pushed off to the side during cleaning, can still be seen to the left and in low areas of the rock.
NASA Astrophysics Data System (ADS)
Manos, Harry
2016-03-01
Visual aids are important to student learning, and they help make the teacher's job easier. Keeping with the TPT theme of "The Art, Craft, and Science of Physics Teaching," the purpose of this article is to show how teachers, lacking equipment and funds, can construct a durable 3-D model reference frame and a model gravity well tailored to specific class lessons. Most of the supplies are readily available in the home or at school: rubbing alcohol, a rag, two colors of spray paint, art brushes, and masking tape. The cost of these supplies, if you don't have them, is less than 20.
NASA Technical Reports Server (NTRS)
2004-01-01
This 3-D cylindrical-perspective mosaic taken by the navigation camera on the Mars Exploration Rover Spirit on sol 82 shows the view south of the large crater dubbed 'Bonneville.' The rover will travel toward the Columbia Hills, seen here at the upper left. The rock dubbed 'Mazatzal' and the hole the rover drilled in to it can be seen at the lower left. The rover's position is referred to as 'Site 22, Position 32.' This image was geometrically corrected to make the horizon appear flat.
NASA Technical Reports Server (NTRS)
2004-01-01
This 3-D cylindrical-perspective mosaic taken by the navigation camera on the Mars Exploration Rover Spirit on sol 82 shows the view south of the large crater dubbed 'Bonneville.' The rover will travel toward the Columbia Hills, seen here at the upper left. The rock dubbed 'Mazatzal' and the hole the rover drilled in to it can be seen at the lower left. The rover's position is referred to as 'Site 22, Position 32.' This image was geometrically corrected to make the horizon appear flat.
Love, Lonnie
2015-01-09
ORNL's newly printed 3D Shelby Cobra was showcased at the 2015 NAIAS in Detroit. This "laboratory on wheels" uses the Shelby Cobra design, celebrating the 50th anniversary of this model and honoring the first vehicle to be voted a national monument. The Shelby was printed at the Department of Energy’s Manufacturing Demonstration Facility at ORNL using the BAAM (Big Area Additive Manufacturing) machine and is intended as a “plug-n-play” laboratory on wheels. The Shelby will allow research and development of integrated components to be tested and enhanced in real time, improving the use of sustainable, digital manufacturing solutions in the automotive industry.
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.
Beam Optics Analysis - An Advanced 3D Trajectory Code
Ives, R. Lawrence; Bui, Thuc; Vogler, William; Neilson, Jeff; Read, Mike; Shephard, Mark; Bauer, Andrew; Datta, Dibyendu; Beal, Mark
2006-01-03
Calabazas Creek Research, Inc. has completed initial development of an advanced, 3D program for modeling electron trajectories in electromagnetic fields. The code is being used to design complex guns and collectors. Beam Optics Analysis (BOA) is a fully relativistic, charged particle code using adaptive, finite element meshing. Geometrical input is imported from CAD programs generating ACIS-formatted files. Parametric data is inputted using an intuitive, graphical user interface (GUI), which also provides control of convergence, accuracy, and post processing. The program includes a magnetic field solver, and magnetic information can be imported from Maxwell 2D/3D and other programs. The program supports thermionic emission and injected beams. Secondary electron emission is also supported, including multiple generations. Work on field emission is in progress as well as implementation of computer optimization of both the geometry and operating parameters. The principle features of the program and its capabilities are presented.
NASA Astrophysics Data System (ADS)
Valente, Giovanni; Owen Weatherall, James
2014-11-01
Relativity theory is often taken to include, or to imply, a prohibition on superluminal propagation of causal processes. Yet, what exactly the prohibition on superluminal propagation amounts to and how one should deal with its possible violation have remained open philosophical problems, both in the context of the metaphysics of causation and the foundations of physics. In particular, recent work in philosophy of physics has focused on the causal structure of spacetime in relativity theory and on how this causal structure manifests itself in our most fundamental theories of matter. These topics were the subject of a workshop on "Relativistic Causality in Quantum Field Theory and General Relativity" that we organized (along with John Earman) at the Center for Philosophy of Science in Pittsburgh on April 5-7, 2013. The present Special Issue comprises contributions by speakers in that workshop as well as several other experts exploring different aspects of relativistic causality. We are grateful to the journal for hosting this Special Issue, to the journal's managing editor, Femke Kuiling, for her help and support in putting the issue together, and to the authors and the referees for their excellent work.
Positional Awareness Map 3D (PAM3D)
NASA Technical Reports Server (NTRS)
Hoffman, Monica; Allen, Earl L.; Yount, John W.; Norcross, April Louise
2012-01-01
The Western Aeronautical Test Range of the National Aeronautics and Space Administration s Dryden Flight Research Center needed to address the aging software and hardware of its current situational awareness display application, the Global Real-Time Interactive Map (GRIM). GRIM was initially developed in the late 1980s and executes on older PC architectures using a Linux operating system that is no longer supported. Additionally, the software is difficult to maintain due to its complexity and loss of developer knowledge. It was decided that a replacement application must be developed or acquired in the near future. The replacement must provide the functionality of the original system, the ability to monitor test flight vehicles in real-time, and add improvements such as high resolution imagery and true 3-dimensional capability. This paper will discuss the process of determining the best approach to replace GRIM, and the functionality and capabilities of the first release of the Positional Awareness Map 3D.
Mannoor, Manu S.; Jiang, Ziwen; James, Teena; Kong, Yong Lin; Malatesta, Karen A.; Soboyejo, Winston O.; Verma, Naveen; Gracias, David H.; McAlpine, Michael C.
2013-01-01
The ability to three-dimensionally interweave biological tissue with functional electronics could enable the creation of bionic organs possessing enhanced functionalities over their human counterparts. Conventional electronic devices are inherently two-dimensional, preventing seamless multidimensional integration with synthetic biology, as the processes and materials are very different. Here, we present a novel strategy for overcoming these difficulties via additive manufacturing of biological cells with structural and nanoparticle derived electronic elements. As a proof of concept, we generated a bionic ear via 3D printing of a cell-seeded hydrogel matrix in the precise anatomic geometry of a human ear, along with an intertwined conducting polymer consisting of infused silver nanoparticles. This allowed for in vitro culturing of cartilage tissue around an inductive coil antenna in the ear, which subsequently enables readout of inductively-coupled signals from cochlea-shaped electrodes. The printed ear exhibits enhanced auditory sensing for radio frequency reception, and complementary left and right ears can listen to stereo audio music. Overall, our approach suggests a means to intricately merge biologic and nanoelectronic functionalities via 3D printing. PMID:23635097
3D Printable Graphene Composite
Wei, Xiaojun; Li, Dong; Jiang, Wei; Gu, Zheming; Wang, Xiaojuan; Zhang, Zengxing; Sun, Zhengzong
2015-01-01
In human being’s history, both the Iron Age and Silicon Age thrived after a matured massive processing technology was developed. Graphene is the most recent superior material which could potentially initialize another new material Age. However, while being exploited to its full extent, conventional processing methods fail to provide a link to today’s personalization tide. New technology should be ushered in. Three-dimensional (3D) printing fills the missing linkage between graphene materials and the digital mainstream. Their alliance could generate additional stream to push the graphene revolution into a new phase. Here we demonstrate for the first time, a graphene composite, with a graphene loading up to 5.6 wt%, can be 3D printable into computer-designed models. The composite’s linear thermal coefficient is below 75 ppm·°C−1 from room temperature to its glass transition temperature (Tg), which is crucial to build minute thermal stress during the printing process. PMID:26153673
3D Printable Graphene Composite
NASA Astrophysics Data System (ADS)
Wei, Xiaojun; Li, Dong; Jiang, Wei; Gu, Zheming; Wang, Xiaojuan; Zhang, Zengxing; Sun, Zhengzong
2015-07-01
In human being’s history, both the Iron Age and Silicon Age thrived after a matured massive processing technology was developed. Graphene is the most recent superior material which could potentially initialize another new material Age. However, while being exploited to its full extent, conventional processing methods fail to provide a link to today’s personalization tide. New technology should be ushered in. Three-dimensional (3D) printing fills the missing linkage between graphene materials and the digital mainstream. Their alliance could generate additional stream to push the graphene revolution into a new phase. Here we demonstrate for the first time, a graphene composite, with a graphene loading up to 5.6 wt%, can be 3D printable into computer-designed models. The composite’s linear thermal coefficient is below 75 ppm·°C-1 from room temperature to its glass transition temperature (Tg), which is crucial to build minute thermal stress during the printing process.
3D medical thermography device
NASA Astrophysics Data System (ADS)
Moghadam, Peyman
2015-05-01
In this paper, a novel handheld 3D medical thermography system is introduced. The proposed system consists of a thermal-infrared camera, a color camera and a depth camera rigidly attached in close proximity and mounted on an ergonomic handle. As a practitioner holding the device smoothly moves it around the human body parts, the proposed system generates and builds up a precise 3D thermogram model by incorporating information from each new measurement in real-time. The data is acquired in motion, thus it provides multiple points of view. When processed, these multiple points of view are adaptively combined by taking into account the reliability of each individual measurement which can vary due to a variety of factors such as angle of incidence, distance between the device and the subject and environmental sensor data or other factors influencing a confidence of the thermal-infrared data when captured. Finally, several case studies are presented to support the usability and performance of the proposed system.
3D acoustic atmospheric tomography
NASA Astrophysics Data System (ADS)
Rogers, Kevin; Finn, Anthony
2014-10-01
This paper presents a method for tomographically reconstructing spatially varying 3D atmospheric temperature profiles and wind velocity fields based. Measurements of the acoustic signature measured onboard a small Unmanned Aerial Vehicle (UAV) are compared to ground-based observations of the same signals. The frequency-shifted signal variations are then used to estimate the acoustic propagation delay between the UAV and the ground microphones, which are also affected by atmospheric temperature and wind speed vectors along each sound ray path. The wind and temperature profiles are modelled as the weighted sum of Radial Basis Functions (RBFs), which also allow local meteorological measurements made at the UAV and ground receivers to supplement any acoustic observations. Tomography is used to provide a full 3D reconstruction/visualisation of the observed atmosphere. The technique offers observational mobility under direct user control and the capacity to monitor hazardous atmospheric environments, otherwise not justifiable on the basis of cost or risk. This paper summarises the tomographic technique and reports on the results of simulations and initial field trials. The technique has practical applications for atmospheric research, sound propagation studies, boundary layer meteorology, air pollution measurements, analysis of wind shear, and wind farm surveys.
Mannoor, Manu S; Jiang, Ziwen; James, Teena; Kong, Yong Lin; Malatesta, Karen A; Soboyejo, Winston O; Verma, Naveen; Gracias, David H; McAlpine, Michael C
2013-06-12
The ability to three-dimensionally interweave biological tissue with functional electronics could enable the creation of bionic organs possessing enhanced functionalities over their human counterparts. Conventional electronic devices are inherently two-dimensional, preventing seamless multidimensional integration with synthetic biology, as the processes and materials are very different. Here, we present a novel strategy for overcoming these difficulties via additive manufacturing of biological cells with structural and nanoparticle derived electronic elements. As a proof of concept, we generated a bionic ear via 3D printing of a cell-seeded hydrogel matrix in the anatomic geometry of a human ear, along with an intertwined conducting polymer consisting of infused silver nanoparticles. This allowed for in vitro culturing of cartilage tissue around an inductive coil antenna in the ear, which subsequently enables readout of inductively-coupled signals from cochlea-shaped electrodes. The printed ear exhibits enhanced auditory sensing for radio frequency reception, and complementary left and right ears can listen to stereo audio music. Overall, our approach suggests a means to intricately merge biologic and nanoelectronic functionalities via 3D printing.
3D structured illumination microscopy
NASA Astrophysics Data System (ADS)
Dougherty, William M.; Goodwin, Paul C.
2011-03-01
Three-dimensional structured illumination microscopy achieves double the lateral and axial resolution of wide-field microscopy, using conventional fluorescent dyes, proteins and sample preparation techniques. A three-dimensional interference-fringe pattern excites the fluorescence, filling in the "missing cone" of the wide field optical transfer function, thereby enabling axial (z) discrimination. The pattern acts as a spatial carrier frequency that mixes with the higher spatial frequency components of the image, which usually succumb to the diffraction limit. The fluorescence image encodes the high frequency content as a down-mixed, moiré-like pattern. A series of images is required, wherein the 3D pattern is shifted and rotated, providing down-mixed data for a system of linear equations. Super-resolution is obtained by solving these equations. The speed with which the image series can be obtained can be a problem for the microscopy of living cells. Challenges include pattern-switching speeds, optical efficiency, wavefront quality and fringe contrast, fringe pitch optimization, and polarization issues. We will review some recent developments in 3D-SIM hardware with the goal of super-resolved z-stacks of motile cells.
Martian terrain & airbags - 3D
NASA Technical Reports Server (NTRS)
1997-01-01
Portions of the lander's deflated airbags and a petal are at lower left in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
Martian terrain & airbags - 3D
NASA Technical Reports Server (NTRS)
1997-01-01
Portions of the lander's deflated airbags and a petal are at the lower area of this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
Martian terrain & airbags - 3D
NASA Technical Reports Server (NTRS)
1997-01-01
Portions of the lander's deflated airbags and a petal are at lower left in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
Martian terrain & airbags - 3D
NASA Technical Reports Server (NTRS)
1997-01-01
Portions of the lander's deflated airbags and a petal are at the lower area of this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.
Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right
General Relativistic MHD Simulations of Jet Formation
NASA Technical Reports Server (NTRS)
Mizuno, Y.; Nishikawa, K.-I.; Hardee, P.; Koide, S.; Fishman, G. J.
2005-01-01
We have performed 3-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations of jet formation from an accretion disk with/without initial perturbation around a rotating black hole. We input a sinusoidal perturbation (m = 5 mode) in the rotation velocity of the accretion disk. The simulation results show the formation of a relativistic jet from the accretion disk. Although the initial perturbation becomes weakened by the coupling among different modes, it survives and triggers lower modes. As a result, complex non-axisymmetric density structure develops in the disk and the jet. Newtonian MHD simulations of jet formation with a non-axisymmetric mode show the growth of the m = 2 mode but GRMHD simulations cannot see the clear growth of the m = 2 mode.
Larry Lawrence; Bruce Miller
2004-09-01
The Lott Ranch 3D seismic prospect located in Garza County, Texas is a project initiated in September of 1991 by the J.M. Huber Corp., a petroleum exploration and production company. By today's standards the 126 square mile project does not seem monumental, however at the time it was conceived it was the most intensive land 3D project ever attempted. Acquisition began in September of 1991 utilizing GEO-SEISMIC, INC., a seismic data contractor. The field parameters were selected by J.M. Huber, and were of a radical design. The recording instruments used were GeoCor IV amplifiers designed by Geosystems Inc., which record the data in signed bit format. It would not have been practical, if not impossible, to have processed the entire raw volume with the tools available at that time. The end result was a dataset that was thought to have little utility due to difficulties in processing the field data. In 1997, Yates Energy Corp. located in Roswell, New Mexico, formed a partnership to further develop the project. Through discussions and meetings with Pinnacle Seismic, it was determined that the original Lott Ranch 3D volume could be vastly improved upon reprocessing. Pinnacle Seismic had shown the viability of improving field-summed signed bit data on smaller 2D and 3D projects. Yates contracted Pinnacle Seismic Ltd. to perform the reprocessing. This project was initiated with high resolution being a priority. Much of the potential resolution was lost through the initial summing of the field data. Modern computers that are now being utilized have tremendous speed and storage capacities that were cost prohibitive when this data was initially processed. Software updates and capabilities offer a variety of quality control and statics resolution, which are pertinent to the Lott Ranch project. The reprocessing effort was very successful. The resulting processed data-set was then interpreted using modern PC-based interpretation and mapping software. Production data, log data
NASA Astrophysics Data System (ADS)
Deb, Narayan C.; Hibbert, Alan
2010-07-01
Oscillator strengths and transition rates for the electric-dipole (E1) allowed and intercombination transitions among 3d 5, 3d 44s and 3d 44p levels of Fe IV are calculated using the CIV3 code of Hibbert and coworkers. Using the Hartree-Fock functions up to 3d orbitals we have also optimized 4s, 4p, 4d, 4f, 5s, 5p and 5d orbitals of which 4s and 4p are taken to be spectroscopic and the remaining orbitals represent corrections to the spectroscopic orbitals or the correlation effects. The J-dependent levels of 108 LS states are included in the calculation and the relativistic effects are accounted for via the Breit-Pauli operator. Configurations are chosen in two steps: (a) two promotions were allowed from the 3p, 3d, 4s and 4p subshells, using all the orbitals; and (b) selective promotions from the 3s subshell are included, but only to the 3s and 4s orbitals. The ab initio fine-structure levels are then fine tuned to reproduce observed energy levels as closely as possible, and the resulting wavefunctions are used to calculate oscillator strengths and transition rates for all possible E1 transitions. For many of these transitions, the present results show good agreement between the length and velocity forms while for some transitions, some large disagreements are found with other available results. The complete list of weighted oscillator strengths, transition rates, and line strengths for transitions among the fine structure levels of the three lowest configurations are presented in ascending order of wavelength.
Magnetoresistance in relativistic hydrodynamics without anomalies
NASA Astrophysics Data System (ADS)
Baumgartner, Andrew; Karch, Andreas; Lucas, Andrew
2017-06-01
We present expressions for the magnetoconductivity and the magnetoresistance of a strongly interacting metal in 3 + 1 dimensions, derivable from relativistic hydrodynamics. Such an approach is suitable for ultraclean metals with emergent Lorentz invariance. When this relativistic fluid contains chiral anomalies, it is known to exhibit longitudinal negative magnetoresistance. We show that similar effects can arise in non-anomalous relativistic fluids due to the distinctive gradient expansion. In contrast with a Galilean-invariant fluid, the resistivity tensor of a dirty relativistic fluid exhibits similar angular dependence to negative magnetoresistance, even when the constitutive relations and momentum relaxation rate are isotropic. We further account for the effect of magnetic field-dependent corrections to the gradient expansion and the effects of long-wavelength impurities on magnetoresistance. We note that the holographic D3/D7 system exhibits negative magnetoresistance.
Calculations of two-fluid magnetohydrodynamic axisymmetric steady-states
NASA Astrophysics Data System (ADS)
Ferraro, N. M.; Jardin, S. C.
2009-11-01
M3D- C1 is an implicit, high-order finite element code for the solution of the time-dependent nonlinear two-fluid magnetohydrodynamic equations [S.C. Jardin, J. Breslau, N. Ferraro, A high-order implicit finite element method for integrating the two-fluid magnetohydrodynamic equations in two dimensions, J. Comp. Phys. 226 (2) (2007) 2146-2174]. This code has now been extended to allow computations in toroidal geometry. Improvements to the spatial integration and time-stepping algorithms are discussed. Steady-states of a resistive two-fluid model, self-consistently including flows, anisotropic viscosity (including gyroviscosity) and heat flux, are calculated for diverted plasmas in geometries typical of the National Spherical Torus Experiment (NSTX) [M. Ono et al., Exploration of spherical torus physics in the NSTX device, Nucl. Fusion 40 (3Y) (2000) 557-561]. These states are found by time-integrating the dynamical equations until the steady-state is reached, and are therefore stationary or statistically steady on both magnetohydrodynamic and transport time-scales. Resistively driven cross-surface flows are found to be in close agreement with Pfirsch-Schlüter theory. Poloidally varying toroidal flows are in agreement with comparable calculations [A.Y. Aydemir, Shear flows at the tokamak edge and their interaction with edge-localized modes, Phys. Plasmas 14]. New effects on core toroidal rotation due to gyroviscosity and a local particle source are observed.
Love, Lonnie
2016-11-02
ORNL's newly printed 3D Shelby Cobra was showcased at the 2015 NAIAS in Detroit. This "laboratory on wheels" uses the Shelby Cobra design, celebrating the 50th anniversary of this model and honoring the first vehicle to be voted a national monument. The Shelby was printed at the Department of Energyâs Manufacturing Demonstration Facility at ORNL using the BAAM (Big Area Additive Manufacturing) machine and is intended as a âplug-n-playâ laboratory on wheels. The Shelby will allow research and development of integrated components to be tested and enhanced in real time, improving the use of sustainable, digital manufacturing solutions in the automotive industry.
Quasi 3D dispersion experiment
NASA Astrophysics Data System (ADS)
Bakucz, P.
2003-04-01
This paper studies the problem of tracer dispersion in a coloured fluid flowing through a two-phase 3D rough channel-system in a 40 cm*40 cm plexi-container filled by homogen glass fractions and colourless fluid. The unstable interface between the driving coloured fluid and the colourless fluid develops viscous fingers with a fractal structure at high capillary number. Five two-dimensional fractal fronts have been observed at the same time using four cameras along the vertical side-walls and using one camera located above the plexi-container. In possession of five fronts the spatial concentration contours are determined using statistical models. The concentration contours are self-affine fractal curves with a fractal dimension D=2.19. This result is valid for disperison at high Péclet numbers.
Sinclair, Michael B
2012-01-05
ShowMe3D is a data visualization graphical user interface specifically designed for use with hyperspectral image obtained from the Hyperspectral Confocal Microscope. The program allows the user to select and display any single image from a three dimensional hyperspectral image stack. By moving a slider control, the user can easily move between images of the stack. The user can zoom into any region of the image. The user can select any pixel or region from the displayed image and display the fluorescence spectrum associated with that pixel or region. The user can define up to 3 spectral filters to apply to the hyperspectral image and view the image as it would appear from a filter-based confocal microscope. The user can also obtain statistics such as intensity average and variance from selected regions.
NASA Technical Reports Server (NTRS)
2009-01-01
wavelengths. Since the amount of the wavelength shift is related to the speed of motion, one can determine how fast the debris are moving in either direction. Because Cas A is the result of an explosion, the stellar debris is expanding radially outwards from the explosion center. Using simple geometry, the scientists were able to construct a 3-D model using all of this information. A program called 3-D Slicer modified for astronomical use by the Astronomical Medicine Project at Harvard University in Cambridge, Mass. was used to display and manipulate the 3-D model. Commercial software was then used to create the 3-D fly-through.
The blue filaments defining the blast wave were not mapped using the Doppler effect because they emit a different kind of light synchrotron radiation that does not emit light at discrete wavelengths, but rather in a broad continuum. The blue filaments are only a representation of the actual filaments observed at the blast wave.
This visualization shows that there are two main components to this supernova remnant: a spherical component in the outer parts of the remnant and a flattened (disk-like) component in the inner region. The spherical component consists of the outer layer of the star that exploded, probably made of helium and carbon. These layers drove a spherical blast wave into the diffuse gas surrounding the star. The flattened component that astronomers were unable to map into 3-D prior to these Spitzer observations consists of the inner layers of the star. It is made from various heavier elements, not all shown in the visualization, such as oxygen, neon, silicon, sulphur, argon and iron.
High-velocity plumes, or jets, of this material are shooting out from the explosion in the plane of the disk-like component mentioned above. Plumes of silicon appear in the northeast and southwest, while those of iron are seen in the southeast and north. These jets were already known and Doppler velocity measurements have been made for these
NASA Technical Reports Server (NTRS)
2009-01-01
wavelengths. Since the amount of the wavelength shift is related to the speed of motion, one can determine how fast the debris are moving in either direction. Because Cas A is the result of an explosion, the stellar debris is expanding radially outwards from the explosion center. Using simple geometry, the scientists were able to construct a 3-D model using all of this information. A program called 3-D Slicer modified for astronomical use by the Astronomical Medicine Project at Harvard University in Cambridge, Mass. was used to display and manipulate the 3-D model. Commercial software was then used to create the 3-D fly-through.
The blue filaments defining the blast wave were not mapped using the Doppler effect because they emit a different kind of light synchrotron radiation that does not emit light at discrete wavelengths, but rather in a broad continuum. The blue filaments are only a representation of the actual filaments observed at the blast wave.
This visualization shows that there are two main components to this supernova remnant: a spherical component in the outer parts of the remnant and a flattened (disk-like) component in the inner region. The spherical component consists of the outer layer of the star that exploded, probably made of helium and carbon. These layers drove a spherical blast wave into the diffuse gas surrounding the star. The flattened component that astronomers were unable to map into 3-D prior to these Spitzer observations consists of the inner layers of the star. It is made from various heavier elements, not all shown in the visualization, such as oxygen, neon, silicon, sulphur, argon and iron.
High-velocity plumes, or jets, of this material are shooting out from the explosion in the plane of the disk-like component mentioned above. Plumes of silicon appear in the northeast and southwest, while those of iron are seen in the southeast and north. These jets were already known and Doppler velocity measurements have been made for these
3D Printing of Graphene Aerogels.
Zhang, Qiangqiang; Zhang, Feng; Medarametla, Sai Pradeep; Li, Hui; Zhou, Chi; Lin, Dong
2016-04-06
3D printing of a graphene aerogel with true 3D overhang structures is highlighted. The aerogel is fabricated by combining drop-on-demand 3D printing and freeze casting. The water-based GO ink is ejected and freeze-cast into designed 3D structures. The lightweight (<10 mg cm(-3) ) 3D printed graphene aerogel presents superelastic and high electrical conduction.
Magnetohydrodynamic sea water propulsion
Petrick, M.; Thomas, A.; Genens, L.; Libera, J.; Nietert, R.; Bouillard, J.; Pierson, E.; Hill, D.; Picologlou, B.; Ohlsson, O.; Kasprzyk, T.; Berry, G.
1991-01-01
An experimental and theoretical investigation of a large scale MHD propulsor has been undertaken whose objectives are to (1) investigate the transient and steady state performance of the thruster over operating parameter ranges that are compatible with achievement of high efficiency, (2) to quantify the principal loss mechanisms within the thruster and (3) to obtain preliminary hydroacoustic data. The performance of the thruster was first investigated theoretically with a 3-D code to quantify the loss mechanisms and identify experimental parameter ranges of interest. The loss mechanisms of interest are ohmic losses within the channel and those resulting from electrical currents at the entrance and exit of the thruster, and enhanced frictional losses. The analysis indicated that the relative importance of the loss mechanisms was a function of the thruster design and operating parameters. The experimental investigation of the large scale propulsor is being conducted on a sea water test facility that was designed to match the capabilities of a large 6-T superconducting magnet. The facility design was such that {approximately}90{degrees} of all losses occurred within the propulsion test train (inlet nozzle, propulsor and diffuser) thus facilitating isolation of the loss mechanisms. The test thruster itself is heavily instrumented to provide local measurements of velocity, pressure, and electric fields. The predicted overall thruster performance and value of the loss mechanisms will be compared with measured values. Comparisons will also be presented of the voltage gradients between electrodes, overall thruster efficiency, axial pressure gradients across the propulsor, change in velocity profiles, axial and vertical current distributions and exit distribution of the electrolytic gases.
Magnetohydrodynamic sea water propulsion
Petrick, M.; Thomas, A.; Genens, L.; Libera, J.; Nietert, R.; Bouillard, J.; Pierson, E.; Hill, D.; Picologlou, B.; Ohlsson, O.; Kasprzyk, T.; Berry, G.
1991-12-31
An experimental and theoretical investigation of a large scale MHD propulsor has been undertaken whose objectives are to (1) investigate the transient and steady state performance of the thruster over operating parameter ranges that are compatible with achievement of high efficiency, (2) to quantify the principal loss mechanisms within the thruster and (3) to obtain preliminary hydroacoustic data. The performance of the thruster was first investigated theoretically with a 3-D code to quantify the loss mechanisms and identify experimental parameter ranges of interest. The loss mechanisms of interest are ohmic losses within the channel and those resulting from electrical currents at the entrance and exit of the thruster, and enhanced frictional losses. The analysis indicated that the relative importance of the loss mechanisms was a function of the thruster design and operating parameters. The experimental investigation of the large scale propulsor is being conducted on a sea water test facility that was designed to match the capabilities of a large 6-T superconducting magnet. The facility design was such that {approximately}90{degrees} of all losses occurred within the propulsion test train (inlet nozzle, propulsor and diffuser) thus facilitating isolation of the loss mechanisms. The test thruster itself is heavily instrumented to provide local measurements of velocity, pressure, and electric fields. The predicted overall thruster performance and value of the loss mechanisms will be compared with measured values. Comparisons will also be presented of the voltage gradients between electrodes, overall thruster efficiency, axial pressure gradients across the propulsor, change in velocity profiles, axial and vertical current distributions and exit distribution of the electrolytic gases.
Relativistic Plasma Polarizer: Impact of Temperature Anisotropy on Relativistic Transparency.
Stark, David J; Bhattacharjee, Chinmoy; Arefiev, Alexey V; Toncian, Toma; Hazeltine, R D; Mahajan, S M
2015-07-10
3D particle-in-cell simulations demonstrate that the enhanced transparency of a relativistically hot plasma is sensitive to how the energy is partitioned between different degrees of freedom. For an anisotropic electron distribution, propagation characteristics, like the critical density, will depend on the polarization of the electromagnetic wave. Despite the onset of the Weibel instability in such plasmas, the anisotropy can persist long enough to affect laser propagation. This plasma can then function as a polarizer or a wave plate to dramatically alter the pulse polarization.
Magnetohydrodynamics of Mira's cometary tail
NASA Astrophysics Data System (ADS)
Gómez, E. A.
2013-10-01
Aims: The asymptotic giant-branch, long-period variable star Mira exhibits a 4 parsec long cometary tail in the far-ultraviolet. We address the issue of the origin of this structure and its emission process by simulating the transition of this star from the interstellar medium to the Local Bubble, which is a tenuous, high-pressure medium. Methods: We use the hydrodynamic and the magnetohydrodynamic modules of the PLUTO astrophysical code to carry out our simulations. We study the system without a cooling function, with a simplified exponential cooling function, and with a simplified nonequilibrium cooling function. Results: We find evidence that magnetohydrodynamics constrain the shape of the cometary tail and explain features of its far-ultraviolet emission. We suggest an emission process that involves C0 excitation through inelastic electron collisions and a two-photon continuum to explain the luminosity of Mira's tail.
Representation of Ideal Magnetohydrodynamic Modes
Roscoe B. White
2013-01-15
One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through δ Β = ∇ X (xi X B) ensures that δ B • ∇ ψ = 0 at a resonance, with ψ labelling an equilibrium flux surface. Also useful for the analysis of guiding center orbits in a perturbed field is the representation δ Β = ∇ X αB. These two representations are equivalent, but the vanishing of δ B • ∇ψ at a resonance is necessary but not sufficient for the preservation of field line topology, and a indiscriminate use of either perturbation in fact destroys the original equilibrium flux topology. It is necessary to find the perturbed field to all orders in xi to conserve the original topology. The effect of using linearized perturbations on stability and growth rate calculations is discussed
Dynamic multiscaling in magnetohydrodynamic turbulence.
Ray, Samriddhi Sankar; Sahoo, Ganapati; Pandit, Rahul
2016-11-01
We present a study of the multiscaling of time-dependent velocity and magnetic-field structure functions in homogeneous, isotropic magnetohydrodynamic (MHD) turbulence in three dimensions. We generalize the formalism that has been developed for analogous studies of time-dependent structure functions in fluid turbulence to MHD. By carrying out detailed numerical studies of such time-dependent structure functions in a shell model for three-dimensional MHD turbulence, we obtain both equal-time and dynamic scaling exponents.
Acceleration of positrons by a relativistic electron beam in the presence of quantum effects
Niknam, A. R.; Aki, H.; Khorashadizadeh, S. M.
2013-09-15
Using the quantum magnetohydrodynamic model and obtaining the dispersion relation of the Cherenkov and cyclotron waves, the acceleration of positrons by a relativistic electron beam is investigated. The Cherenkov and cyclotron acceleration mechanisms of positrons are compared together. It is shown that growth rate and, therefore, the acceleration of positrons can be increased in the presence of quantum effects.
NASA Astrophysics Data System (ADS)
Mahjoubfar, A.; Goda, K.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.
2013-03-01
Laser scanners are essential for scientific research, manufacturing, defense, and medical practice. Unfortunately, often times the speed of conventional laser scanners (e.g., galvanometric mirrors and acousto-optic deflectors) falls short for many applications, resulting in motion blur and failure to capture fast transient information. Here, we present a novel type of laser scanner that offers roughly three orders of magnitude higher scan rates than conventional methods. Our laser scanner, which we refer to as the hybrid dispersion laser scanner, performs inertia-free laser scanning by dispersing a train of broadband pulses both temporally and spatially. More specifically, each broadband pulse is temporally processed by time stretch dispersive Fourier transform and further dispersed into space by one or more diffractive elements such as prisms and gratings. As a proof-of-principle demonstration, we perform 1D line scans at a record high scan rate of 91 MHz and 2D raster scans and 3D volumetric scans at an unprecedented scan rate of 105 kHz. The method holds promise for a broad range of scientific, industrial, and biomedical applications. To show the utility of our method, we demonstrate imaging, nanometer-resolved surface vibrometry, and high-precision flow cytometry with real-time throughput that conventional laser scanners cannot offer due to their low scan rates.
3D multiplexed immunoplasmonics microscopy
NASA Astrophysics Data System (ADS)
Bergeron, Éric; Patskovsky, Sergiy; Rioux, David; Meunier, Michel
2016-07-01
Selective labelling, identification and spatial distribution of cell surface biomarkers can provide important clinical information, such as distinction between healthy and diseased cells, evolution of a disease and selection of the optimal patient-specific treatment. Immunofluorescence is the gold standard for efficient detection of biomarkers expressed by cells. However, antibodies (Abs) conjugated to fluorescent dyes remain limited by their photobleaching, high sensitivity to the environment, low light intensity, and wide absorption and emission spectra. Immunoplasmonics is a novel microscopy method based on the visualization of Abs-functionalized plasmonic nanoparticles (fNPs) targeting cell surface biomarkers. Tunable fNPs should provide higher multiplexing capacity than immunofluorescence since NPs are photostable over time, strongly scatter light at their plasmon peak wavelengths and can be easily functionalized. In this article, we experimentally demonstrate accurate multiplexed detection based on the immunoplasmonics approach. First, we achieve the selective labelling of three targeted cell surface biomarkers (cluster of differentiation 44 (CD44), epidermal growth factor receptor (EGFR) and voltage-gated K+ channel subunit KV1.1) on human cancer CD44+ EGFR+ KV1.1+ MDA-MB-231 cells and reference CD44- EGFR- KV1.1+ 661W cells. The labelling efficiency with three stable specific immunoplasmonics labels (functionalized silver nanospheres (CD44-AgNSs), gold (Au) NSs (EGFR-AuNSs) and Au nanorods (KV1.1-AuNRs)) detected by reflected light microscopy (RLM) is similar to the one with immunofluorescence. Second, we introduce an improved method for 3D localization and spectral identification of fNPs based on fast z-scanning by RLM with three spectral filters corresponding to the plasmon peak wavelengths of the immunoplasmonics labels in the cellular environment (500 nm for 80 nm AgNSs, 580 nm for 100 nm AuNSs and 700 nm for 40 nm × 92 nm AuNRs). Third, the developed
NASA Astrophysics Data System (ADS)
Hermanns, Maria
The Kitaev honeycomb model has become one of the archetypal spin models exhibiting topological phases of matter, where the magnetic moments fractionalize into Majorana fermions interacting with a Z2 gauge field. In this talk, we discuss generalizations of this model to three-dimensional lattice structures. Our main focus is the metallic state that the emergent Majorana fermions form. In particular, we discuss the relation of the nature of this Majorana metal to the details of the underlying lattice structure. Besides (almost) conventional metals with a Majorana Fermi surface, one also finds various realizations of Dirac semi-metals, where the gapless modes form Fermi lines or even Weyl nodes. We introduce a general classification of these gapless quantum spin liquids using projective symmetry analysis. Furthermore, we briefly outline why these Majorana metals in 3D Kitaev systems provide an even richer variety of Dirac and Weyl phases than possible for electronic matter and comment on possible experimental signatures. Work done in collaboration with Kevin O'Brien and Simon Trebst.
Crowdsourcing Based 3d Modeling
NASA Astrophysics Data System (ADS)
Somogyi, A.; Barsi, A.; Molnar, B.; Lovas, T.
2016-06-01
Web-based photo albums that support organizing and viewing the users' images are widely used. These services provide a convenient solution for storing, editing and sharing images. In many cases, the users attach geotags to the images in order to enable using them e.g. in location based applications on social networks. Our paper discusses a procedure that collects open access images from a site frequently visited by tourists. Geotagged pictures showing the image of a sight or tourist attraction are selected and processed in photogrammetric processing software that produces the 3D model of the captured object. For the particular investigation we selected three attractions in Budapest. To assess the geometrical accuracy, we used laser scanner and DSLR as well as smart phone photography to derive reference values to enable verifying the spatial model obtained from the web-album images. The investigation shows how detailed and accurate models could be derived applying photogrammetric processing software, simply by using images of the community, without visiting the site.
NIF Ignition Target 3D Point Design
Jones, O; Marinak, M; Milovich, J; Callahan, D
2008-11-05
We have developed an input file for running 3D NIF hohlraums that is optimized such that it can be run in 1-2 days on parallel computers. We have incorporated increasing levels of automation into the 3D input file: (1) Configuration controlled input files; (2) Common file for 2D and 3D, different types of capsules (symcap, etc.); and (3) Can obtain target dimensions, laser pulse, and diagnostics settings automatically from NIF Campaign Management Tool. Using 3D Hydra calculations to investigate different problems: (1) Intrinsic 3D asymmetry; (2) Tolerance to nonideal 3D effects (e.g. laser power balance, pointing errors); and (3) Synthetic diagnostics.
Disk Emission from Magnetohydrodynamic Simulations of Spinning Black Holes
NASA Technical Reports Server (NTRS)
Schnittman, Jeremy D.; Krolik, Julian H.; Noble, Scott C.
2016-01-01
We present the results of a new series of global, three-dimensional, relativistic magnetohydrodynamic (MHD) simulations of thin accretion disks around spinning black holes. The disks have aspect ratios of H/R approx. 0.05 and spin parameters of a/M = 0, 0.5, 0.9, and 0.99. Using the ray-tracing code Pandurata, we generate broadband thermal spectra and polarization signatures from the MHD simulations. We find that the simulated spectra can be well fit with a simple, universal emissivity profile that better reproduces the behavior of the emission from the inner disk, compared to traditional analyses carried out using a Novikov-Thorne thin disk model. Finally, we show how spectropolarization observations can be used to convincingly break the spin-inclination degeneracy well known to the continuum-fitting method of measuring black hole spin.
NASA Astrophysics Data System (ADS)
Brito, T.; Hudson, M. K.; Kress, B. T.
2011-12-01
The energization and loss processes for energetic radiation belt electrons are not yet well understood. Global simulations using magnetohydrodynamics (MHD) model fields as drivers provide a valuable tool to study the dynamics of these ~MeV energetic particles. We use satellite measurements of the solar wind as the boundary condition for the Lyon-Fedder-Mobarry (LFM) 3D MHD code calculation of fields which then drive electrons in a 3D test particle simulation that keeps track of attributes like energy, pitch-angle and L-shell. Wave-particle interaction can cause both energization and pitch-angle scattering loss. Ultra Low Frequency (ULF) waves resolved by the MHD code have been correlated with both enhancement in outer zone radiation belt electron flux1 and modulation of precipitation loss to the atmosphere2. The time scales seen in several studies linking ULF waves with radiation belt flux increases are usually several hours to a few days1,3, but few studies consider the effects of ULF waves in the Pc-4 to Pc-5 range on electron loss to the atmosphere on a time scale of tens of minutes. We investigate such rapid loss, using measured solar wind input to MHD-test particle simulations for a CME-shock event that occurred on January 21, 2005. We focus on mechanisms by which ULF waves, seen both in the simulations and observations, especially ones driven by pressure variations in the solar wind, influence the radiation belts. ULF modulation was seen in precipitation detected by the MINIS balloon campaign measurements of atmospheric Bremsstrahlung from MeV electron precipitation4. We propose a coherent energization and precipitation mechanism due to trapped electron drift resonance with azimuthally propagating poloidal mode ULF waves during the CME-shock compression of the magnetosphere4; depending on the drift phase, some electrons are energized by the azimuthal electric field pulse and some are de-energized in the perpendicular direction causing them to pitch
3-D Cavern Enlargement Analyses
EHGARTNER, BRIAN L.; SOBOLIK, STEVEN R.
2002-03-01
Three-dimensional finite element analyses simulate the mechanical response of enlarging existing caverns at the Strategic Petroleum Reserve (SPR). The caverns are located in Gulf Coast salt domes and are enlarged by leaching during oil drawdowns as fresh water is injected to displace the crude oil from the caverns. The current criteria adopted by the SPR limits cavern usage to 5 drawdowns (leaches). As a base case, 5 leaches were modeled over a 25 year period to roughly double the volume of a 19 cavern field. Thirteen additional leaches where then simulated until caverns approached coalescence. The cavern field approximated the geometries and geologic properties found at the West Hackberry site. This enabled comparisons are data collected over nearly 20 years to analysis predictions. The analyses closely predicted the measured surface subsidence and cavern closure rates as inferred from historic well head pressures. This provided the necessary assurance that the model displacements, strains, and stresses are accurate. However, the cavern field has not yet experienced the large scale drawdowns being simulated. Should they occur in the future, code predictions should be validated with actual field behavior at that time. The simulations were performed using JAS3D, a three dimensional finite element analysis code for nonlinear quasi-static solids. The results examine the impacts of leaching and cavern workovers, where internal cavern pressures are reduced, on surface subsidence, well integrity, and cavern stability. The results suggest that the current limit of 5 oil drawdowns may be extended with some mitigative action required on the wells and later on to surface structure due to subsidence strains. The predicted stress state in the salt shows damage to start occurring after 15 drawdowns with significant failure occurring at the 16th drawdown, well beyond the current limit of 5 drawdowns.
America's National Parks 3d (4)
Atmospheric Science Data Center
2017-04-11
article title: America's National Parks Viewed in 3D by NASA's MISR (Anaglyph 4) ... four new anaglyphs that showcase 33 of our nation's national parks, monuments, historical sites and recreation areas in glorious 3D. ...
America's National Parks 3d (3)
Atmospheric Science Data Center
2016-12-30
article title: America's National Parks Viewed in 3D by NASA's MISR (Anaglyph 3) ... four new anaglyphs that showcase 33 of our nation's national parks, monuments, historical sites and recreation areas in glorious 3D. ...
America's National Parks 3d (2)
Atmospheric Science Data Center
2016-12-30
article title: America's National Parks Viewed in 3D by NASA's MISR (Anaglyph 2) ... four new anaglyphs that showcase 33 of our nation's national parks, monuments, historical sites and recreation areas in glorious 3D. ...
America's National Parks 3d (1)
Atmospheric Science Data Center
2016-12-30
article title: America's National Parks Viewed in 3D by NASA's MISR (Anaglyph 1) ... four new anaglyphs that showcase 33 of our nation's national parks, monuments, historical sites and recreation areas in glorious 3D. ...
3D ultrasound in fetal spina bifida.
Schramm, T; Gloning, K-P; Minderer, S; Tutschek, B
2008-12-01
3D ultrasound can be used to study the fetal spine, but skeletal mode can be inconclusive for the diagnosis of fetal spina bifida. We illustrate a diagnostic approach using 2D and 3D ultrasound and indicate possible pitfalls.
An interactive multiview 3D display system
NASA Astrophysics Data System (ADS)
Zhang, Zhaoxing; Geng, Zheng; Zhang, Mei; Dong, Hui
2013-03-01
The progresses in 3D display systems and user interaction technologies will help more effective 3D visualization of 3D information. They yield a realistic representation of 3D objects and simplifies our understanding to the complexity of 3D objects and spatial relationship among them. In this paper, we describe an autostereoscopic multiview 3D display system with capability of real-time user interaction. Design principle of this autostereoscopic multiview 3D display system is presented, together with the details of its hardware/software architecture. A prototype is built and tested based upon multi-projectors and horizontal optical anisotropic display structure. Experimental results illustrate the effectiveness of this novel 3D display and user interaction system.
[3D emulation of epicardium dynamic mapping].
Lu, Jun; Yang, Cui-Wei; Fang, Zu-Xiang
2005-03-01
In order to realize epicardium dynamic mapping of the whole atria, 3-D graphics are drawn with OpenGL. Some source codes are introduced in the paper to explain how to produce, read, and manipulate 3-D model data.
3-D Extensions for Trustworthy Systems
2011-01-01
modifications to the floor planning stage of the 3-D design flow that are necessary to support our design approach. We strongly recommend that the 3-D EDA ...and we outline problems, challenges, attacks, solutions, and topics for future research. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17...Requirements for automated 3-D IC design tools for the physical layout of components. Since fully automated Electronic Design Automation ( EDA ) for 3-D
True 3d Images and Their Applications
NASA Astrophysics Data System (ADS)
Wang, Z.; wang@hzgeospace., zheng.
2012-07-01
A true 3D image is a geo-referenced image. Besides having its radiometric information, it also has true 3Dground coordinates XYZ for every pixels of it. For a true 3D image, especially a true 3D oblique image, it has true 3D coordinates not only for building roofs and/or open grounds, but also for all other visible objects on the ground, such as visible building walls/windows and even trees. The true 3D image breaks the 2D barrier of the traditional orthophotos by introducing the third dimension (elevation) into the image. From a true 3D image, for example, people will not only be able to read a building's location (XY), but also its height (Z). true 3D images will fundamentally change, if not revolutionize, the way people display, look, extract, use, and represent the geospatial information from imagery. In many areas, true 3D images can make profound impacts on the ways of how geospatial information is represented, how true 3D ground modeling is performed, and how the real world scenes are presented. This paper first gives a definition and description of a true 3D image and followed by a brief review of what key advancements of geospatial technologies have made the creation of true 3D images possible. Next, the paper introduces what a true 3D image is made of. Then, the paper discusses some possible contributions and impacts the true 3D images can make to geospatial information fields. At the end, the paper presents a list of the benefits of having and using true 3D images and the applications of true 3D images in a couple of 3D city modeling projects.
Microfabricating 3D Structures by Laser Origami
2011-11-09
10.1117/2.1201111.003952 Microfabricating 3D structures by laser origami Alberto Piqué, Scott Mathews, Andrew Birnbaum, and Nicholas Charipar A new...folding known as origami allows the transformation of flat patterns into 3D shapes. A similar approach can be used to generate 3D structures com...materials Figure 1. (A–C) Schematic illustrating the steps in the laser origami process and (D) a resulting folded out-of-plane 3D structure. that can
Laser Based 3D Volumetric Display System
1993-03-01
Literature, Costa Mesa, CA July 1983. 3. "A Real Time Autostereoscopic Multiplanar 3D Display System", Rodney Don Williams, Felix Garcia, Jr., Texas...8217 .- NUMBERS LASER BASED 3D VOLUMETRIC DISPLAY SYSTEM PR: CD13 0. AUTHOR(S) PE: N/AWIU: DN303151 P. Soltan, J. Trias, W. Robinson, W. Dahlke 7...laser generated 3D volumetric images on a rotating double helix, (where the 3D displays are computer controlled for group viewing with the naked eye
Teaching Geography with 3-D Visualization Technology
ERIC Educational Resources Information Center
Anthamatten, Peter; Ziegler, Susy S.
2006-01-01
Technology that helps students view images in three dimensions (3-D) can support a broad range of learning styles. "Geo-Wall systems" are visualization tools that allow scientists, teachers, and students to project stereographic images and view them in 3-D. We developed and presented 3-D visualization exercises in several undergraduate courses.…
Expanding Geometry Understanding with 3D Printing
ERIC Educational Resources Information Center
Cochran, Jill A.; Cochran, Zane; Laney, Kendra; Dean, Mandi
2016-01-01
With the rise of personal desktop 3D printing, a wide spectrum of educational opportunities has become available for educators to leverage this technology in their classrooms. Until recently, the ability to create physical 3D models was well beyond the scope, skill, and budget of many schools. However, since desktop 3D printers have become readily…
Imaging a Sustainable Future in 3D
NASA Astrophysics Data System (ADS)
Schuhr, W.; Lee, J. D.; Kanngieser, E.
2012-07-01
It is the intention of this paper, to contribute to a sustainable future by providing objective object information based on 3D photography as well as promoting 3D photography not only for scientists, but also for amateurs. Due to the presentation of this article by CIPA Task Group 3 on "3D Photographs in Cultural Heritage", the presented samples are masterpieces of historic as well as of current 3D photography concentrating on cultural heritage. In addition to a report on exemplarily access to international archives of 3D photographs, samples for new 3D photographs taken with modern 3D cameras, as well as by means of a ground based high resolution XLITE staff camera and also 3D photographs taken from a captive balloon and the use of civil drone platforms are dealt with. To advise on optimum suited 3D methodology, as well as to catch new trends in 3D, an updated synoptic overview of the 3D visualization technology, even claiming completeness, has been carried out as a result of a systematic survey. In this respect, e.g., today's lasered crystals might be "early bird" products in 3D, which, due to lack in resolution, contrast and color, remember to the stage of the invention of photography.
Expanding Geometry Understanding with 3D Printing
ERIC Educational Resources Information Center
Cochran, Jill A.; Cochran, Zane; Laney, Kendra; Dean, Mandi
2016-01-01
With the rise of personal desktop 3D printing, a wide spectrum of educational opportunities has become available for educators to leverage this technology in their classrooms. Until recently, the ability to create physical 3D models was well beyond the scope, skill, and budget of many schools. However, since desktop 3D printers have become readily…
Teaching Geography with 3-D Visualization Technology
ERIC Educational Resources Information Center
Anthamatten, Peter; Ziegler, Susy S.
2006-01-01
Technology that helps students view images in three dimensions (3-D) can support a broad range of learning styles. "Geo-Wall systems" are visualization tools that allow scientists, teachers, and students to project stereographic images and view them in 3-D. We developed and presented 3-D visualization exercises in several undergraduate courses.…
3D Printing and Its Urologic Applications
Soliman, Youssef; Feibus, Allison H; Baum, Neil
2015-01-01
3D printing is the development of 3D objects via an additive process in which successive layers of material are applied under computer control. This article discusses 3D printing, with an emphasis on its historical context and its potential use in the field of urology. PMID:26028997
NASA Astrophysics Data System (ADS)
Engle, Rob
2008-02-01
This paper discusses the creative and technical challenges encountered during the production of "Beowulf 3D," director Robert Zemeckis' adaptation of the Old English epic poem and the first film to be simultaneously released in IMAX 3D and digital 3D formats.
3D Flow Visualization Using Texture Advection
NASA Technical Reports Server (NTRS)
Kao, David; Zhang, Bing; Kim, Kwansik; Pang, Alex; Moran, Pat (Technical Monitor)
2001-01-01
Texture advection is an effective tool for animating and investigating 2D flows. In this paper, we discuss how this technique can be extended to 3D flows. In particular, we examine the use of 3D and 4D textures on 3D synthetic and computational fluid dynamics flow fields.
3-D Perspective Pasadena, California
NASA Technical Reports Server (NTRS)
2000-01-01
This perspective view shows the western part of the city of Pasadena, California, looking north towards the San Gabriel Mountains. Portions of the cities of Altadena and La Canada, Flintridge are also shown. The image was created from three datasets: the Shuttle Radar Topography Mission (SRTM) supplied the elevation data; Landsat data from November 11, 1986 provided the land surface color (not the sky) and U.S. Geological Survey digital aerial photography provides the image detail. The Rose Bowl, surrounded by a golf course, is the circular feature at the bottom center of the image. The Jet Propulsion Laboratory is the cluster of large buildings north of the Rose Bowl at the base of the mountains. A large landfill, Scholl Canyon, is the smooth area in the lower left corner of the scene. This image shows the power of combining data from different sources to create planning tools to study problems that affect large urban areas. In addition to the well-known earthquake hazards, Southern California is affected by a natural cycle of fire and mudflows. Wildfires strip the mountains of vegetation, increasing the hazards from flooding and mudflows for several years afterwards. Data such as shown on this image can be used to predict both how wildfires will spread over the terrain and also how mudflows will be channeled down the canyons. The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission was designed to collect three dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency
3D simulations of fluctuation spectra in the hall-MHD plasma.
Shaikh, Dastgeer; Shukla, P K
2009-01-30
Turbulent spectral cascades are investigated by means of fully three-dimensional (3D) simulations of a compressible Hall-magnetohydrodynamic (H-MHD) plasma in order to understand the observed spectral break in the solar wind turbulence spectra in the regime where the characteristic length scales associated with electromagnetic fluctuations are smaller than the ion gyroradius. In this regime, the results of our 3D simulations exhibit that turbulent spectral cascades in the presence of a mean magnetic field follow an omnidirectional anisotropic inertial-range spectrum close to k(-7/3). The latter is associated with the Hall current arising from nonequal electron and ion fluid velocities in our 3D H-MHD plasma model.
Regularity criteria for incompressible magnetohydrodynamics equations in three dimensions
NASA Astrophysics Data System (ADS)
Lin, Hongxia; Du, Lili
2013-01-01
In this paper, we give some new global regularity criteria for three-dimensional incompressible magnetohydrodynamics (MHD) equations. More precisely, we provide some sufficient conditions in terms of the derivatives of the velocity or pressure, for the global regularity of strong solutions to 3D incompressible MHD equations in the whole space, as well as for periodic boundary conditions. Moreover, the regularity criterion involving three of the nine components of the velocity gradient tensor is also obtained. The main results generalize the recent work by Cao and Wu (2010 Two regularity criteria for the 3D MHD equations J. Diff. Eqns 248 2263-74) and the analysis in part is based on the works by Cao C and Titi E (2008 Regularity criteria for the three-dimensional Navier-Stokes equations Indiana Univ. Math. J. 57 2643-61 2011 Gobal regularity criterion for the 3D Navier-Stokes equations involving one entry of the velocity gradient tensor Arch. Rational Mech. Anal. 202 919-32) for 3D incompressible Navier-Stokes equations.
Radiation magnetohydrodynamics in global simulations of protoplanetary discs
NASA Astrophysics Data System (ADS)
Flock, M.; Fromang, S.; González, M.; Commerçon, B.
2013-12-01
Aims: Our aim is to study the thermal and dynamical evolution of protoplanetary discs in global simulations, including the physics of radiation transfer and magneto-hydrodynamic turbulence caused by the magneto-rotational instability. Methods: We have developed a radiative transfer method based on the flux-limited diffusion approximation that includes frequency dependent irradiation by the central star. This hybrid scheme is implemented in the PLUTO code. The focus of our implementation is on the performance of the radiative transfer method. Using an optimized Jacobi preconditioned BiCGSTAB solver, the radiative module is three times faster than the magneto-hydrodynamic step for the disc set-up we consider. We obtain weak scaling efficiencies of 70% up to 1024 cores. Results: We present the first global 3D radiation magneto-hydrodynamic simulations of a stratified protoplanetary disc. The disc model parameters were chosen to approximate those of the system AS 209 in the star-forming region Ophiuchus. Starting the simulation from a disc in radiative and hydrostatic equilibrium, the magneto-rotational instability quickly causes magneto-hydrodynamic turbulence and heating in the disc. We find that the turbulent properties are similar to that of recent locally isothermal global simulations of protoplanetary discs. For example, the rate of angular momentum transport α is a few times 10-3. For the disc parameters we use, turbulent dissipation heats the disc midplane and raises the temperature by about 15% compared to passive disc models. The vertical temperature profile shows no temperature peak at the midplane as in classical viscous disc models. A roughly flat vertical temperature profile establishes in the optically thick region of the disc close to the midplane. We reproduce the vertical temperature profile with viscous disc models for which the stress tensor vertical profile is flat in the bulk of the disc and vanishes in the disc corona. Conclusions: The present
Data assimilation for magnetohydrodynamics systems
NASA Astrophysics Data System (ADS)
Mendoza, O. Barrero; de Moor, B.; Bernstein, D. S.
2006-05-01
Prediction of solar storms has become a very important issue due to the fact that they can affect dramatically the telecommunication and electrical power systems at the earth. As a result, a lot of research is being done in this direction, space weather forecast. Magnetohydrodynamics systems are being studied in order to analyse the space plasma dynamics, and techniques which have been broadly used in the prediction of earth environmental variables like the Kalman filter (KF), the ensemble Kalman filter (EnKF), the extended Kalman filter (EKF), etc., are being studied and adapted to this new framework. The assimilation of a wide range of space environment data into first-principles-based global numerical models will improve our understanding of the physics of the geospace environment and the forecasting of its behaviour. Therefore, the aim of this paper is to study the performance of nonlinear observers in magnetohydrodynamics systems, namely, the EnKF.The EnKF is based on a Monte Carlo simulation approach for propagation of process and measurement errors. In this paper, the EnKF for a nonlinear two-dimensional magnetohydrodynamic (2D-MHD) system is considered. For its implementation, two software packages are merged, namely, the Versatile Advection Code (VAC) written in Fortran and Matlab of Mathworks. The 2D-MHD is simulated with the VAC code while the EnKF is computed in Matlab. In order to study the performance of the EnKF in MHD systems, different number of measurement points as well as ensemble members are set.
Case study: Beauty and the Beast 3D: benefits of 3D viewing for 2D to 3D conversion
NASA Astrophysics Data System (ADS)
Handy Turner, Tara
2010-02-01
From the earliest stages of the Beauty and the Beast 3D conversion project, the advantages of accurate desk-side 3D viewing was evident. While designing and testing the 2D to 3D conversion process, the engineering team at Walt Disney Animation Studios proposed a 3D viewing configuration that not only allowed artists to "compose" stereoscopic 3D but also improved efficiency by allowing artists to instantly detect which image features were essential to the stereoscopic appeal of a shot and which features had minimal or even negative impact. At a time when few commercial 3D monitors were available and few software packages provided 3D desk-side output, the team designed their own prototype devices and collaborated with vendors to create a "3D composing" workstation. This paper outlines the display technologies explored, final choices made for Beauty and the Beast 3D, wish-lists for future development and a few rules of thumb for composing compelling 2D to 3D conversions.
Cho, Jungyeon
2011-05-13
Electron magnetohydrodynamics (EMHD) provides a fluidlike description of small-scale magnetized plasmas. An EMHD wave propagates along magnetic field lines. The direction of propagation can be either parallel or antiparallel to the magnetic field lines. We numerically study propagation of three-dimensional (3D) EMHD wave packets moving in one direction. We obtain two major results. (1) Unlike its magnetohydrodynamic (MHD) counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave packets traveling in one direction create opposite-traveling wave packets via self-interaction and cascade energy to smaller scales. (2) EMHD wave packets traveling in one direction clearly exhibit inverse energy cascade. We find that the latter is due to conservation of magnetic helicity. We compare inverse energy cascade in 3D EMHD turbulence and two-dimensional (2D) hydrodynamic turbulence.
Method for manufacturing magnetohydrodynamic electrodes
Killpatrick, D.H.; Thresh, H.R.
1980-06-24
A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator is described comprising the steps of preparing a billet having a core of a first metal, a tubular sleeve of a second metal, and an outer sheath of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MHD channel frame. The method forms a bond between the first metal of the core and the second metal of the sleeve strong enough to withstand a hot and corrosive environment.
Isogeometric analysis in reduced magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Ratnani, A.; Sonnendrücker, E.
2012-01-01
Isogeometric analysis (IGA) consists of using computer-aided design (CAD) models defining the geometry of the computational domain using both B-splines and non-uniform rational B-splines (NURBS) to represent the unknowns that are the solution of a partial differential equation using a finite element principle. In this paper, we review the main ideas of IGA and apply it to a reduced magnetohydrodynamic (MHD) model that is used in tokamak simulations. This is a first step towards arbitrary high-order and smooth approximations of reduced MHD generalizing the Bézier splines approach of Czarny and Huysmans (2008 J. Comput. Phys. 227 7423-45).
Magnetohydrodynamic mechanism for pedestal formation.
Guazzotto, L; Betti, R
2011-09-16
Time-dependent two-dimensional magnetohydrodynamic simulations are carried out for tokamak plasmas with edge poloidal flow. Differently from conventional equilibrium theory, a density pedestal all around the edge is obtained when the poloidal velocity exceeds the poloidal sound speed. The outboard pedestal is induced by the transonic discontinuity, the inboard one by mass redistribution. The density pedestal follows the formation of a highly sheared flow at the transonic surface. These results may be relevant to the L-H transition and pedestal formation in high performance tokamak plasmas.
Galerkin approximations for dissipative magnetohydrodynamics
NASA Technical Reports Server (NTRS)
Chen, Hudong; Shan, Xiaowen; Montgomery, David
1990-01-01
A Galerkin approximation scheme is proposed for voltage-driven, dissipative magnetohydrodynamics. The trial functions are exact eigenfunctions of the linearized continuum equations and represent helical deformations of the axisymmetric, zero-flow, driven steady state. The lowest nontrivial truncation is explored: one axisymmetric trial function and one helical trial function each for the magnetic and velocity fields. The system resembles the Lorenz approximation to Benard convection, but in the region of believed applicability, its dynamical behavior is rather different, including relaxation to a helically deformed state similar to those that have emerged in the much higher resolution computations of Dahlburg et al.
Magneto-Hydrodynamics Based Microfluidics
Qian, Shizhi; Bau, Haim H.
2009-01-01
In microfluidic devices, it is necessary to propel samples and reagents from one part of the device to another, stir fluids, and detect the presence of chemical and biological targets. Given the small size of these devices, the above tasks are far from trivial. Magnetohydrodynamics (MHD) offers an elegant means to control fluid flow in microdevices without a need for mechanical components. In this paper, we review the theory of MHD for low conductivity fluids and describe various applications of MHD such as fluid pumping, flow control in fluidic networks, fluid stirring and mixing, circular liquid chromatography, thermal reactors, and microcoolers. PMID:20046890
Mini 3D for shallow gas reconnaissance
Vallieres, T. des; Enns, D.; Kuehn, H.; Parron, D.; Lafet, Y.; Van Hulle, D.
1996-12-31
The Mini 3D project was undertaken by TOTAL and ELF with the support of CEPM (Comite d`Etudes Petrolieres et Marines) to define an economical method of obtaining 3D seismic HR data for shallow gas assessment. An experimental 3D survey was carried out with classical site survey techniques in the North Sea. From these data 19 simulations, were produced to compare different acquisition geometries ranging from dual, 600 m long cables to a single receiver. Results show that short offset, low fold and very simple streamer positioning are sufficient to give a reliable 3D image of gas charged bodies. The 3D data allow a much more accurate risk delineation than 2D HR data. Moreover on financial grounds Mini-3D is comparable in cost to a classical HR 2D survey. In view of these results, such HR 3D should now be the standard for shallow gas surveying.
Relativistic electron beam generator
Mooney, L.J.; Hyatt, H.M.
1975-11-11
A relativistic electron beam generator for laser media excitation is described. The device employs a diode type relativistic electron beam source having a cathode shape which provides a rectangular output beam with uniform current density.
Fuerst, Steven V.; Mizuno, Yosuke; Nishikawa, Ken-Ichi; Wu, Kinwah; /Mullard Space Sci. Lab.
2007-01-05
We calculate the emission from relativistic flows in black hole systems using a fully general relativistic radiative transfer formulation, with flow structures obtained by general relativistic magneto-hydrodynamic simulations. We consider thermal free-free emission and thermal synchrotron emission. Bright filament-like features protrude (visually) from the accretion disk surface, which are enhancements of synchrotron emission where the magnetic field roughly aligns with the line-of-sight in the co-moving frame. The features move back and forth as the accretion flow evolves, but their visibility and morphology are robust. We propose that variations and drifts of the features produce certain X-ray quasi-periodic oscillations (QPOs) observed in black-hole X-ray binaries.
3-D Technology Approaches for Biological Ecologies
NASA Astrophysics Data System (ADS)
Liu, Liyu; Austin, Robert; U. S-China Physical-Oncology Sciences Alliance (PS-OA) Team
Constructing three dimensional (3-D) landscapes is an inevitable issue in deep study of biological ecologies, because in whatever scales in nature, all of the ecosystems are composed by complex 3-D environments and biological behaviors. Just imagine if a 3-D technology could help complex ecosystems be built easily and mimic in vivo microenvironment realistically with flexible environmental controls, it will be a fantastic and powerful thrust to assist researchers for explorations. For years, we have been utilizing and developing different technologies for constructing 3-D micro landscapes for biophysics studies in in vitro. Here, I will review our past efforts, including probing cancer cell invasiveness with 3-D silicon based Tepuis, constructing 3-D microenvironment for cell invasion and metastasis through polydimethylsiloxane (PDMS) soft lithography, as well as explorations of optimized stenting positions for coronary bifurcation disease with 3-D wax printing and the latest home designed 3-D bio-printer. Although 3-D technologies is currently considered not mature enough for arbitrary 3-D micro-ecological models with easy design and fabrication, I hope through my talk, the audiences will be able to sense its significance and predictable breakthroughs in the near future. This work was supported by the State Key Development Program for Basic Research of China (Grant No. 2013CB837200), the National Natural Science Foundation of China (Grant No. 11474345) and the Beijing Natural Science Foundation (Grant No. 7154221).
Clement, T.P.; Jones, N.L.
1998-02-01
RT3D (Reactive Transport in 3-Dimensions) is a computer code that solves coupled partial differential equations that describe reactive-flow and transport of multiple mobile and/or immobile species in a three dimensional saturated porous media. RT3D was developed from the single-species transport code, MT3D (DoD-1.5, 1997 version). As with MT3D, RT3D also uses the USGS groundwater flow model MODFLOW for computing spatial and temporal variations in groundwater head distribution. This report presents a set of tutorial problems that are designed to illustrate how RT3D simulations can be performed within the Department of Defense Groundwater Modeling System (GMS). GMS serves as a pre- and post-processing interface for RT3D. GMS can be used to define all the input files needed by RT3D code, and later the code can be launched from within GMS and run as a separate application. Once the RT3D simulation is completed, the solution can be imported to GMS for graphical post-processing. RT3D v1.0 supports several reaction packages that can be used for simulating different types of reactive contaminants. Each of the tutorials, described below, provides training on a different RT3D reaction package. Each reaction package has different input requirements, and the tutorials are designed to describe these differences. Furthermore, the tutorials illustrate the various options available in GMS for graphical post-processing of RT3D results. Users are strongly encouraged to complete the tutorials before attempting to use RT3D and GMS on a routine basis.
3D change detection - Approaches and applications
NASA Astrophysics Data System (ADS)
Qin, Rongjun; Tian, Jiaojiao; Reinartz, Peter
2016-12-01
Due to the unprecedented technology development of sensors, platforms and algorithms for 3D data acquisition and generation, 3D spaceborne, airborne and close-range data, in the form of image based, Light Detection and Ranging (LiDAR) based point clouds, Digital Elevation Models (DEM) and 3D city models, become more accessible than ever before. Change detection (CD) or time-series data analysis in 3D has gained great attention due to its capability of providing volumetric dynamics to facilitate more applications and provide more accurate results. The state-of-the-art CD reviews aim to provide a comprehensive synthesis and to simplify the taxonomy of the traditional remote sensing CD techniques, which mainly sit within the boundary of 2D image/spectrum analysis, largely ignoring the particularities of 3D aspects of the data. The inclusion of 3D data for change detection (termed 3D CD), not only provides a source with different modality for analysis, but also transcends the border of traditional top-view 2D pixel/object-based analysis to highly detailed, oblique view or voxel-based geometric analysis. This paper reviews the recent developments and applications of 3D CD using remote sensing and close-range data, in support of both academia and industry researchers who seek for solutions in detecting and analyzing 3D dynamics of various objects of interest. We first describe the general considerations of 3D CD problems in different processing stages and identify CD types based on the information used, being the geometric comparison and geometric-spectral analysis. We then summarize relevant works and practices in urban, environment, ecology and civil applications, etc. Given the broad spectrum of applications and different types of 3D data, we discuss important issues in 3D CD methods. Finally, we present concluding remarks in algorithmic aspects of 3D CD.
Variational integrators for reduced magnetohydrodynamics
Kraus, Michael; Tassi, Emanuele; Grasso, Daniela
2016-09-15
Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. The resulting integrator preserves important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As the integrator is free of numerical resistivity, spurious reconnection along current sheets is absent in the ideal case. If effects of electron inertia are added, reconnection of magnetic field lines is allowed, although the resulting model still possesses a noncanonical Hamiltonian structure. After reviewing the conservation laws of the model equations, the adopted variational principle with the related conservation laws is described both at the continuous and discrete level. We verify the favourable properties of the variational integrator in particular with respect to the preservation of the invariants of the models under consideration and compare with results from the literature and those of a pseudo-spectral code.
Variational integrators for reduced magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Kraus, Michael; Tassi, Emanuele; Grasso, Daniela
2016-09-01
Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. The resulting integrator preserves important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As the integrator is free of numerical resistivity, spurious reconnection along current sheets is absent in the ideal case. If effects of electron inertia are added, reconnection of magnetic field lines is allowed, although the resulting model still possesses a noncanonical Hamiltonian structure. After reviewing the conservation laws of the model equations, the adopted variational principle with the related conservation laws is described both at the continuous and discrete level. We verify the favourable properties of the variational integrator in particular with respect to the preservation of the invariants of the models under consideration and compare with results from the literature and those of a pseudo-spectral code.
Representation of ideal magnetohydrodynamic modes
White, R. B.
2013-02-15
One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through {delta}B(vector sign)={nabla} Multiplication-Sign ({xi}(vector sign) Multiplication-Sign B(vector sign)) ensures that {delta}B(vector sign){center_dot}{nabla}{psi}=0 at a resonance, with {psi} labelling an equilibrium flux surface. Also useful for the analysis of guiding center orbits in a perturbed field is the representation {delta}B(vector sign)={nabla} Multiplication-Sign {alpha}B(vector sign). These two representations are equivalent, but the vanishing of {delta}B(vector sign){center_dot}{nabla}{psi} at a resonance is necessary but not sufficient for the preservation of field line topology, and a indiscriminate use of either perturbation in fact destroys the original equilibrium flux topology. It is necessary to find the perturbed field to all orders in {xi}(vector sign) to conserve the original topology. The effect of using linearized perturbations on stability and growth rate calculations is discussed.
Three-dimensional relativistic electromagnetic subcycle solitons.
Esirkepov, Timur; Nishihara, Katsunobu; Bulanov, Sergei V; Pegoraro, Francesco
2002-12-30
Three-dimensional (3D) relativistic electromagnetic subcycle solitons were observed in 3D particle-in-cell simulations of an intense short-laser-pulse propagation in an underdense plasma. Their structure resembles that of an oscillating electric dipole with a poloidal electric field and a toroidal magnetic field that oscillate in phase with the electron density with frequency below the Langmuir frequency. On the ion time scale, the soliton undergoes a Coulomb explosion of its core, resulting in ion acceleration, and then evolves into a slowly expanding quasineutral cavity.
Evolution of 3D Boson Stars with Waveform Extraction
NASA Astrophysics Data System (ADS)
Bondarescu, Ruxandra; Balakrishna, Jayashree; Daues, Gregory; Guzman, Francisco
2005-04-01
This talk will present results from a study of boson stars under nonspherical perturbations using a fully general-relativistic 3D code based on the Cactus Computational Toolkit. We study the evolution of stable, critical and unstable boson stars subjected to various types of nonspherical perturbations and analyze the emitted gravitational waves. We calculate the Zerilli and Newman-Penrose ψ4 gravitational waveforms and study the quasinormal mode content of the numerical waveforms using predicted QNM frequencies from perturbation theory calculations of Yoshida, Eriguchi and Futamase. Our results show that the waveforms accurately display the strong damping predicted for quasinormal modes of boson stars. The apparent horizons formed from perturbed unstable star collapse were observed to be slightly nonspherical when initially detected and became more spherical as the system evolved.
Substructures in Simulations of Relativistic Jet Formation
NASA Astrophysics Data System (ADS)
Garcia, Raphael de Oliveira; Oliveira, Samuel Rocha de
2017-02-01
We present a set of simulations of relativistic jets from accretion disk initial setup with numerical solutions of a system of general-relativistic magnetohydrodynamics (GRMHD) partial differential equations in a fixed black hole (BH) spacetime which is able to show substructures formations inside the jet as well as lobe formation on the jet head. For this, we used a central scheme of finite volume method without dimensional split and with no Riemann solvers namely the Nessyahu-Tadmor method. Thus, we were able to obtain stable numerical solutions with spurious oscillations under control and with no excessive numerical dissipation. Therefore, we developed some setups for initial conditions capable of simulating the formation of relativistic jets from the accretion disk falling onto central black hole until its ejection, both immersed in a magnetosphere. In our simulations, we were able to observe some substructure of a jet created from an accretion initial disk, namely, jet head, knots, cocoon, and lobe. Also, we present an explanation for cocoon formation and lobe formation. Each initial scenario was determined by ratio between disk density and magnetosphere density, showing that this relation is very important for the shape of the jet and its substructures.
Substructures in Simulations of Relativistic Jet Formation
NASA Astrophysics Data System (ADS)
Garcia, Raphael de Oliveira; Oliveira, Samuel Rocha de
2017-04-01
We present a set of simulations of relativistic jets from accretion disk initial setup with numerical solutions of a system of general-relativistic magnetohydrodynamics (GRMHD) partial differential equations in a fixed black hole (BH) spacetime which is able to show substructures formations inside the jet as well as lobe formation on the jet head. For this, we used a central scheme of finite volume method without dimensional split and with no Riemann solvers namely the Nessyahu-Tadmor method. Thus, we were able to obtain stable numerical solutions with spurious oscillations under control and with no excessive numerical dissipation. Therefore, we developed some setups for initial conditions capable of simulating the formation of relativistic jets from the accretion disk falling onto central black hole until its ejection, both immersed in a magnetosphere. In our simulations, we were able to observe some substructure of a jet created from an accretion initial disk, namely, jet head, knots, cocoon, and lobe. Also, we present an explanation for cocoon formation and lobe formation. Each initial scenario was determined by ratio between disk density and magnetosphere density, showing that this relation is very important for the shape of the jet and its substructures.
Equations on knot polynomials and 3d/5d duality
NASA Astrophysics Data System (ADS)
Mironov, A.; Morozov, A.
2012-10-01
We briefly review the current situation with various relations between knot/braid polynomials (Chern-Simons correlation functions), ordinary and extended, considered as functions of the representation and of the knot topology. These include linear skein relations, quadratic Plucker relations, as well as "differential" and (quantum) ̂A-polynomial structures. We pay a special attention to identity between the ̂A-polynomial equations for knots and Baxter equations for quantum relativistic integrable systems, related through Seiberg-Witten theory to 5d super-Yang-Mills models and through the AGT relation to the q-Virasoro algebra. This identity is an important ingredient of emerging a 3d - 5d generalization of the AGT relation. The shape of the Baxter equation (including the values of coefficients) depend on the choice of the knot/braid. Thus, like the case of KP integrability, where (some, so far torus) knots parameterize particular points of the Universal Grassmannian, in this relation they parameterize particular points in the moduli space of many-body integrable systems of relativistic type.
Equations on knot polynomials and 3d/5d duality
Mironov, A.; Morozov, A.
2012-09-24
We briefly review the current situation with various relations between knot/braid polynomials (Chern-Simons correlation functions), ordinary and extended, considered as functions of the representation and of the knot topology. These include linear skein relations, quadratic Plucker relations, as well as 'differential' and (quantum) A-polynomial structures. We pay a special attention to identity between the A-polynomial equations for knots and Baxter equations for quantum relativistic integrable systems, related through Seiberg-Witten theory to 5d super-Yang-Mills models and through the AGT relation to the q-Virasoro algebra. This identity is an important ingredient of emerging a 3d- 5d generalization of the AGT relation. The shape of the Baxter equation (including the values of coefficients) depend on the choice of the knot/braid. Thus, like the case of KP integrability, where (some, so far torus) knots parameterize particular points of the Universal Grassmannian, in this relation they parameterize particular points in the moduli space of many-body integrable systems of relativistic type.
3D Printer Coupon removal and stowage
2014-12-09
iss042e031282 (12/09/2014) ---US Astronaut Barry (Butch) Wilmore holding a 3D coupon works with the new 3D printer aboard the International Space Station. The 3D Printing experiment in zero gravity demonstrates that a 3D printer works normally in space. In general, a 3D printer extrudes streams of heated plastic, metal or other material, building layer on top of layer to create 3 dimensional objects. Testing a 3D printer using relatively low-temperature plastic feedstock on the International Space Station is the first step towards establishing an on-demand machine shop in space, a critical enabling component for deep-space crewed missions and in-space manufacturing.
3D measurement for rapid prototyping
NASA Astrophysics Data System (ADS)
Albrecht, Peter; Lilienblum, Tilo; Sommerkorn, Gerd; Michaelis, Bernd
1996-08-01
Optical 3-D measurement is an interesting approach for rapid prototyping. On one hand it's necessary to get the 3-D data of an object and on the other hand it's necessary to check the manufactured object (quality checking). Optical 3-D measurement can realize both. Classical 3-D measurement procedures based on photogrammetry cause systematic errors at strongly curved surfaces or steps in surfaces. One possibility to reduce these errors is to calculate the 3-D coordinates from several successively taken images. Thus it's possible to get higher spatial resolution and to reduce the systematic errors at 'problem surfaces.' Another possibility is to process the measurement values by neural networks. A modified associative memory smoothes and corrects the calculated 3-D coordinates using a-priori knowledge about the measurement object.
Center for Extended Magnetohydrodynamic Modeling Cooperative Agreement
Carl R. Sovinec
2008-02-15
nonlinear simulations, which has been publicized as a success story of SciDAC-fostered collaboration. Furthermore, the SuperLU software does not assume any mathematical symmetry, and its generality provides an important capability for extending the physical model beyond magnetohydrodynamics (MHD). With respect to algorithmic and model development, our most significant accomplishment is the development of a new method for solving plasma models that treat electrons as an independent plasma component. These ‘two-fluid’ models encompass MHD and add temporal and spatial scales that are beyond the response of the ion species. Implementation and testing of a previously published algorithm did not prove successful for NIMROD, and the new algorithm has since been devised, analyzed, and implemented. Two-fluid modeling, an important objective of the original NIMROD project, is now routine in 2D applications. Algorithmic components for 3D modeling are in place and tested; though, further computational work is still needed for efficiency. Other algorithmic work extends the ion-fluid stress tensor to include models for parallel and gyroviscous stresses. In addition, our hot-particle simulation capability received important refinements that permitted completion of a benchmark with the M3D code. A highlight of our applications work is the edge-localized mode (ELM) modeling, which was part of the first-ever computational Performance Target for the DOE Office of Fusion Energy Science, see http://www.science.doe.gov/ofes/performancetargets.shtml. Our efforts allowed MHD simulations to progress late into the nonlinear stage, where energy is conducted to the wall location. They also produced a two-fluid ELM simulation starting from experimental information and demonstrating critical drift effects that are characteristic of two-fluid physics. Another important application is the internal kink mode in a tokamak. Here, the primary purpose of the study has been to benchmark the two main code
Transverse electron-scale instability in relativistic shear flows
NASA Astrophysics Data System (ADS)
Alves, E. P.; Grismayer, T.; Fonseca, R. A.; Silva, L. O.
2015-08-01
Electron-scale surface waves are shown to be unstable in the transverse plane of a sheared flow in an initially unmagnetized collisionless plasma, not captured by (magneto)hydrodynamics. It is found that these unstable modes have a higher growth rate than the closely related electron-scale Kelvin-Helmholtz instability in relativistic shears. Multidimensional particle-in-cell simulations verify the analytic results and further reveal the emergence of mushroomlike electron density structures in the nonlinear phase of the instability, similar to those observed in the Rayleigh Taylor instability despite the great disparity in scales and different underlying physics. This transverse electron-scale instability may play an important role in relativistic and supersonic sheared flow scenarios, which are stable at the (magneto)hydrodynamic level. Macroscopic (≫c /ωp e ) fields are shown to be generated by this microscopic shear instability, which are relevant for particle acceleration, radiation emission, and to seed magnetohydrodynamic processes at long time scales.
Expedient Gap Definition Using 3D LADAR
2006-09-01
Research and Development Center (ERDC), ASI has developed an algorithm to reduce the 3D point cloud acquired with the LADAR system into sets of 2D ...developed an algorithm to extract from this 3D point cloud any user-defined number of 2D slices. ASI has incorporated this sensor and algorithm into...direction, ASI has developed an algorithm to condense the 3D point cloud acquired with the LADAR system into sets of 2D profiles that describe the
Digital holography and 3-D imaging.
Banerjee, Partha; Barbastathis, George; Kim, Myung; Kukhtarev, Nickolai
2011-03-01
This feature issue on Digital Holography and 3-D Imaging comprises 15 papers on digital holographic techniques and applications, computer-generated holography and encryption techniques, and 3-D display. It is hoped that future work in the area leads to innovative applications of digital holography and 3-D imaging to biology and sensing, and to the development of novel nonlinear dynamic digital holographic techniques.
Parker, Dennis L.
2015-01-01
SYNOPSIS There has been significant progress made in 3D carotid plaque magnetic resonance imaging techniques in recent years. 3D plaque imaging clearly represents the future in clinical use. With effective flow suppression techniques, choices of different contrast weighting acquisitions, and time-efficient imaging approaches, 3D plaque imaging offers flexible imaging plane and view angle analysis, large coverage, multi-vascular beds capability, and even can be used in fast screening. PMID:26610656
Photorefractive Polymers for Updateable 3D Displays
2010-02-24
Final Performance Report 3. DATES COVERED (From - To) 01-01-2007 to 11-30-2009 4. TITLE AND SUBTITLE Photorefractive Polymers for Updateable 3D ...ABSTRACT During the tenure of this project a large area updateable 3D color display has been developed for the first time using a new co-polymer...photorefractive polymers have been demonstrated. Moreover, a 6 inch × 6 inch sample was fabricated demonstrating the feasibility of making large area 3D
Bifurcation to 3D helical magnetic equilibrium in an axisymmetric toroidal device.
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
Relativistic radiative transfer in relativistic spherical flows
NASA Astrophysics Data System (ADS)
Fukue, Jun
2017-02-01
Relativistic radiative transfer in relativistic spherical flows is numerically examined under the fully special relativistic treatment. We first derive relativistic formal solutions for the relativistic radiative transfer equation in relativistic spherical flows. We then iteratively solve the relativistic radiative transfer equation, using an impact parameter method/tangent ray method, and obtain specific intensities in the inertial and comoving frames, as well as moment quantities, and the Eddington factor. We consider several cases; a scattering wind with a luminous central core, an isothermal wind without a core, a scattering accretion on to a luminous core, and an adiabatic accretion on to a dark core. In the typical wind case with a luminous core, the emergent intensity is enhanced at the center due to the Doppler boost, while it reduces at the outskirts due to the transverse Doppler effect. In contrast to the plane-parallel case, the behavior of the Eddington factor is rather complicated in each case, since the Eddington factor depends on the optical depth, the flow velocity, and other parameters.
Dimensional accuracy of 3D printed vertebra
NASA Astrophysics Data System (ADS)
Ogden, Kent; Ordway, Nathaniel; Diallo, Dalanda; Tillapaugh-Fay, Gwen; Aslan, Can
2014-03-01
3D printer applications in the biomedical sciences and medical imaging are expanding and will have an increasing impact on the practice of medicine. Orthopedic and reconstructive surgery has been an obvious area for development of 3D printer applications as the segmentation of bony anatomy to generate printable models is relatively straightforward. There are important issues that should be addressed when using 3D printed models for applications that may affect patient care; in particular the dimensional accuracy of the printed parts needs to be high to avoid poor decisions being made prior to surgery or therapeutic procedures. In this work, the dimensional accuracy of 3D printed vertebral bodies derived from CT data for a cadaver spine is compared with direct measurements on the ex-vivo vertebra and with measurements made on the 3D rendered vertebra using commercial 3D image processing software. The vertebra was printed on a consumer grade 3D printer using an additive print process using PLA (polylactic acid) filament. Measurements were made for 15 different anatomic features of the vertebral body, including vertebral body height, endplate width and depth, pedicle height and width, and spinal canal width and depth, among others. It is shown that for the segmentation and printing process used, the results of measurements made on the 3D printed vertebral body are substantially the same as those produced by direct measurement on the vertebra and measurements made on the 3D rendered vertebra.
TAURUS. 3-D Finite Element Code Postprocessor
Whirley, R.G.
1984-05-01
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-D Finite Element Code Postprocessor
Kennedy, T.
1992-03-03
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories, and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-D Finite Element Code Postprocessor
Whirley, R.G.
1993-11-30
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-d Finite Element Code Postprocessor
Whirley, R.G.
1991-05-01
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-d Finite Element Code Postprocessor
Whirley, R.G.
1992-03-03
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-D Finite Element Code Postprocessor
Whirley, R.G.
1992-03-03
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
Relativistic linear restoring force
NASA Astrophysics Data System (ADS)
Clark, D.; Franklin, J.; Mann, N.
2012-09-01
We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke’s law to be the force appearing on the right-hand side of the relativistic expressions: dp/dt or dp/dτ. Either formulation recovers Hooke’s law in the non-relativistic limit. In addition to these two forces, we introduce a form of retardation appropriate for the description of a linear (in displacement) force arising from the interaction of a pair of particles with a relativistic field. The procedure is akin to replacing Coulomb’s law in electromagnetism with a retarded form (the first correction in the full relativistic case). This retardation leads to the expected oscillation, but with amplitude growth in both its relativistic and non-relativistic incarnations.
FastScript3D - A Companion to Java 3D
NASA Technical Reports Server (NTRS)
Koenig, Patti
2005-01-01
FastScript3D is a computer program, written in the Java 3D(TM) programming language, that establishes an alternative language that helps users who lack expertise in Java 3D to use Java 3D for constructing three-dimensional (3D)-appearing graphics. The FastScript3D language provides a set of simple, intuitive, one-line text-string commands for creating, controlling, and animating 3D models. The first word in a string is the name of a command; the rest of the string contains the data arguments for the command. The commands can also be used as an aid to learning Java 3D. Developers can extend the language by adding custom text-string commands. The commands can define new 3D objects or load representations of 3D objects from files in formats compatible with such other software systems as X3D. The text strings can be easily integrated into other languages. FastScript3D facilitates communication between scripting languages [which enable programming of hyper-text markup language (HTML) documents to interact with users] and Java 3D. The FastScript3D language can be extended and customized on both the scripting side and the Java 3D side.
Hund's Rule-Driven Dzyaloshinskii-Moriya Interaction at 3 d -5 d Interfaces
NASA Astrophysics Data System (ADS)
Belabbes, A.; Bihlmayer, G.; Bechstedt, F.; Blügel, S.; Manchon, A.
2016-12-01
Using relativistic first-principles calculations, we show that the chemical trend of the Dzyaloshinskii-Moriya interaction (DMI) in 3 d -5 d ultrathin films follows Hund's first rule with a tendency similar to their magnetic moments in either the unsupported 3 d monolayers or 3 d -5 d interfaces. We demonstrate that, besides the spin-orbit coupling (SOC) effect in inversion asymmetric noncollinear magnetic systems, the driving force is the 3 d orbital occupations and their spin-flip mixing processes with the spin-orbit active 5 d states control directly the sign and magnitude of the DMI. The magnetic chirality changes are discussed in the light of the interplay between SOC, Hund's first rule, and the crystal-field splitting of d orbitals.
3D PDF - a means of public access to geological 3D - objects, using the example of GTA3D
NASA Astrophysics Data System (ADS)
Slaby, Mark-Fabian; Reimann, Rüdiger
2013-04-01
In geology, 3D modeling has become very important. In the past, two-dimensional data such as isolines, drilling profiles, or cross-sections based on those, were used to illustrate the subsurface geology, whereas now, we can create complex digital 3D models. These models are produced with special software, such as GOCAD ®. The models can be viewed, only through the software used to create them, or through viewers available for free. The platform-independent PDF (Portable Document Format), enforced by Adobe, has found a wide distribution. This format has constantly evolved over time. Meanwhile, it is possible to display CAD data in an Adobe 3D PDF file with the free Adobe Reader (version 7). In a 3D PDF, a 3D model is freely rotatable and can be assembled from a plurality of objects, which can thus be viewed from all directions on their own. In addition, it is possible to create moveable cross-sections (profiles), and to assign transparency to the objects. Based on industry-standard CAD software, 3D PDFs can be generated from a large number of formats, or even be exported directly from this software. In geoinformatics, different approaches to creating 3D PDFs exist. The intent of the Authority for Mining, Energy and Geology to allow free access to the models of the Geotectonic Atlas (GTA3D), could not be realized with standard software solutions. A specially designed code converts the 3D objects to VRML (Virtual Reality Modeling Language). VRML is one of the few formats that allow using image files (maps) as textures, and to represent colors and shapes correctly. The files were merged in Acrobat X Pro, and a 3D PDF was generated subsequently. A topographic map, a display of geographic directions and horizontal and vertical scales help to facilitate the use.
Observation of 2p3d(1Po)→1s3d(1De) radiative transition in He-like Si, S, and Cl ions.
Kasthurirangan, S; Saha, J K; Agnihotri, A N; Bhattacharyya, S; Misra, D; Kumar, A; Mukherjee, P K; Santos, J P; Costa, A M; Indelicato, P; Mukherjee, T K; Tribedi, L C
2013-12-13
We present an experimental determination of the 2p3d(1Po)→1s3d(1De) x-ray line emitted from He-like Si, S, and Cl projectile ions, excited in collisions with thin carbon foils, using a high-resolution bent-crystal spectrometer. A good agreement between the observation and state-of-the-art relativistic calculations using the multiconfiguration Dirac-Fock formalism including the Breit interaction and QED effects implies the dominance of fluorescent decay over the autoionization process for the 2p3d(^{1}P^{o}) state of He-like heavy ions. This is the first observation of the fluorescence-active doubly excited states in He-like Si, S, and Cl ions.
A hybrid numerical fluid dynamics code for resistive magnetohydrodynamics
Johnson, Jeffrey
2006-04-01
Spasmos is a computational fluid dynamics code that uses two numerical methods to solve the equations of resistive magnetohydrodynamic (MHD) flows in compressible, inviscid, conducting media[1]. The code is implemented as a set of libraries for the Python programming language[2]. It represents conducting and non-conducting gases and materials with uncomplicated (analytic) equations of state. It supports calculations in 1D, 2D, and 3D geometry, though only the 1D configuation has received significant testing to date. Because it uses the Python interpreter as a front end, users can easily write test programs to model systems with a variety of different numerical and physical parameters. Currently, the code includes 1D test programs for hydrodynamics (linear acoustic waves, the Sod weak shock[3], the Noh strong shock[4], the Sedov explosion[5], magnetic diffusion (decay of a magnetic pulse[6], a driven oscillatory "wine-cellar" problem[7], magnetic equilibrium), and magnetohydrodynamics (an advected magnetic pulse[8], linear MHD waves, a magnetized shock tube[9]). Spasmos current runs only in a serial configuration. In the future, it will use MPI for parallel computation.
3D ultrafast ultrasound imaging in vivo
NASA Astrophysics Data System (ADS)
Provost, Jean; Papadacci, Clement; Esteban Arango, Juan; Imbault, Marion; Fink, Mathias; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu
2014-10-01
Very high frame rate ultrasound imaging has recently allowed for the extension of the applications of echography to new fields of study such as the functional imaging of the brain, cardiac electrophysiology, and the quantitative imaging of the intrinsic mechanical properties of tumors, to name a few, non-invasively and in real time. In this study, we present the first implementation of Ultrafast Ultrasound Imaging in 3D based on the use of either diverging or plane waves emanating from a sparse virtual array located behind the probe. It achieves high contrast and resolution while maintaining imaging rates of thousands of volumes per second. A customized portable ultrasound system was developed to sample 1024 independent channels and to drive a 32 × 32 matrix-array probe. Its ability to track in 3D transient phenomena occurring in the millisecond range within a single ultrafast acquisition was demonstrated for 3D Shear-Wave Imaging, 3D Ultrafast Doppler Imaging, and, finally, 3D Ultrafast combined Tissue and Flow Doppler Imaging. The propagation of shear waves was tracked in a phantom and used to characterize its stiffness. 3D Ultrafast Doppler was used to obtain 3D maps of Pulsed Doppler, Color Doppler, and Power Doppler quantities in a single acquisition and revealed, at thousands of volumes per second, the complex 3D flow patterns occurring in the ventricles of the human heart during an entire cardiac cycle, as well as the 3D in vivo interaction of blood flow and wall motion during the pulse wave in the carotid at the bifurcation. This study demonstrates the potential of 3D Ultrafast Ultrasound Imaging for the 3D mapping of stiffness, tissue motion, and flow in humans in vivo and promises new clinical applications of ultrasound with reduced intra—and inter-observer variability.
An aerial 3D printing test mission
NASA Astrophysics Data System (ADS)
Hirsch, Michael; McGuire, Thomas; Parsons, Michael; Leake, Skye; Straub, Jeremy
2016-05-01
This paper provides an overview of an aerial 3D printing technology, its development and its testing. This technology is potentially useful in its own right. In addition, this work advances the development of a related in-space 3D printing technology. A series of aerial 3D printing test missions, used to test the aerial printing technology, are discussed. Through completing these test missions, the design for an in-space 3D printer may be advanced. The current design for the in-space 3D printer involves focusing thermal energy to heat an extrusion head and allow for the extrusion of molten print material. Plastics can be used as well as composites including metal, allowing for the extrusion of conductive material. A variety of experiments will be used to test this initial 3D printer design. High altitude balloons will be used to test the effects of microgravity on 3D printing, as well as parabolic flight tests. Zero pressure balloons can be used to test the effect of long 3D printing missions subjected to low temperatures. Vacuum chambers will be used to test 3D printing in a vacuum environment. The results will be used to adapt a current prototype of an in-space 3D printer. Then, a small scale prototype can be sent into low-Earth orbit as a 3-U cube satellite. With the ability to 3D print in space demonstrated, future missions can launch production hardware through which the sustainability and durability of structures in space will be greatly improved.
3D ultrafast ultrasound imaging in vivo.
Provost, Jean; Papadacci, Clement; Arango, Juan Esteban; Imbault, Marion; Fink, Mathias; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu
2014-10-07
Very high frame rate ultrasound imaging has recently allowed for the extension of the applications of echography to new fields of study such as the functional imaging of the brain, cardiac electrophysiology, and the quantitative imaging of the intrinsic mechanical properties of tumors, to name a few, non-invasively and in real time. In this study, we present the first implementation of Ultrafast Ultrasound Imaging in 3D based on the use of either diverging or plane waves emanating from a sparse virtual array located behind the probe. It achieves high contrast and resolution while maintaining imaging rates of thousands of volumes per second. A customized portable ultrasound system was developed to sample 1024 independent channels and to drive a 32 × 32 matrix-array probe. Its ability to track in 3D transient phenomena occurring in the millisecond range within a single ultrafast acquisition was demonstrated for 3D Shear-Wave Imaging, 3D Ultrafast Doppler Imaging, and, finally, 3D Ultrafast combined Tissue and Flow Doppler Imaging. The propagation of shear waves was tracked in a phantom and used to characterize its stiffness. 3D Ultrafast Doppler was used to obtain 3D maps of Pulsed Doppler, Color Doppler, and Power Doppler quantities in a single acquisition and revealed, at thousands of volumes per second, the complex 3D flow patterns occurring in the ventricles of the human heart during an entire cardiac cycle, as well as the 3D in vivo interaction of blood flow and wall motion during the pulse wave in the carotid at the bifurcation. This study demonstrates the potential of 3D Ultrafast Ultrasound Imaging for the 3D mapping of stiffness, tissue motion, and flow in humans in vivo and promises new clinical applications of ultrasound with reduced intra--and inter-observer variability.
Building 3D data sets of flux tube dynamics
NASA Astrophysics Data System (ADS)
Loseth, B.; Intrator, T. P.; Sears, J.
2010-11-01
Magnetic Reconnection occurs when oppositely directed magnetic fields are advected towards each other as plasma flow. The magnetic fields diffuse through a small region where the frozen flux condition of ideal magnetohydrodynamics (MHD) breaks down and the field lines lose their identity and reconnect to other fields. The reconnection process is important in the confinement of fusion plasmas as well as long-standing solar-physics issues in solar flares, geomagnetic storms, and black hole accretion discs. The Reconnection Scaling Experiment (RSX) uses plasma guns to create one, two, or more parallel flux ropes in a cylindrical chamber with an axial magnetic guide field. The plasma channels twist helically and merge or bounce depending on the attractive force due to the parallel currents and the repulsive force associated with axial and azimuthal magnetic field line bending. The dynamics of merging and bouncing may lead to a new understanding of the statistical mechanics of magnetic fields and provide a means of visualizing three-dimensional MHD turbulence. An update of the RSX vessel including an adjustable magnetic probe array is currently under way and will allow for the building of 3D data sets of these dynamics.
Simulations of Dynamic Relativistic Magnetospheres
NASA Astrophysics Data System (ADS)
Parfrey, Kyle Patrick
Neutron stars and black holes are generally surrounded by magnetospheres of highly conducting plasma in which the magnetic flux density is so high that hydrodynamic forces are irrelevant. In this vanishing-inertia—or ultra-relativistic—limit, magnetohydrodynamics becomes force-free electrodynamics, a system of equations comprising only the magnetic and electric fields, and in which the plasma response is effected by a nonlinear current density term. In this dissertation I describe a new pseudospectral simulation code, designed for studying the dynamic magnetospheres of compact objects. A detailed description of the code and several numerical test problems are given. I first apply the code to the aligned rotator problem, in which a star with a dipole magnetic field is set rotating about its magnetic axis. The solution evolves to a steady state, which is nearly ideal and dissipationless everywhere except in a current sheet, or magnetic field discontinuity, at the equator, into which electromagnetic energy flows and is dissipated. Magnetars are believed to have twisted magnetospheres, due to internal magnetic evolution which deforms the crust, dragging the footpoints of external magnetic field lines. This twisting may be able to explain both magnetars' persistent hard X-ray emission and their energetic bursts and flares. Using the new code, I simulate the evolution of relativistic magnetospheres subjected to slow twisting through large angles. The field lines expand outward, forming a strong current layer; eventually the configuration loses equilibrium and a dynamic rearrangement occurs, involving large-scale rapid magnetic reconnection and dissipation of the free energy of the twisted magnetic field. When the star is rotating, the magnetospheric twisting leads to a large increase in the stellar spin-down rate, which may take place on the long twisting timescale or in brief explosive events, depending on where the twisting is applied and the history of the system
Two-dimensional state in driven magnetohydrodynamic turbulence
Bigot, Barbara; Galtier, Sebastien
2011-02-15
The dynamics of the two-dimensional (2D) state in driven three-dimensional (3D) incompressible magnetohydrodynamic turbulence is investigated through high-resolution direct numerical simulations and in the presence of an external magnetic field at various intensities. For such a flow the 2D state (or slow mode) and the 3D modes correspond, respectively, to spectral fluctuations in the plane k{sub ||}=0 and in the area k{sub ||}>0. It is shown that if initially the 2D state is set to zero it becomes nonnegligible in few turnover times, particularly when the external magnetic field is strong. The maintenance of a large-scale driving leads to a break for the energy spectra of 3D modes; when the driving is stopped, the previous break is removed and a decay phase emerges with Alfvenic fluctuations. For a strong external magnetic field the energy at large perpendicular scales lies mainly in the 2D state, and in all situations a pinning effect is observed at small scales.
Magnetohydrodynamic turbulence: Observation and experiment
Brown, M. R.; Schaffner, D. A.; Weck, P. J.
2015-05-15
We provide a tutorial on the paradigms and tools of magnetohydrodynamic (MHD) turbulence. The principal paradigm is that of a turbulent cascade from large scales to small, resulting in power law behavior for the frequency power spectrum for magnetic fluctuations E{sub B}(f). We will describe five useful statistical tools for MHD turbulence in the time domain: the temporal autocorrelation function, the frequency power spectrum, the probability distribution function of temporal increments, the temporal structure function, and the permutation entropy. Each of these tools will be illustrated with an example taken from MHD fluctuations in the solar wind. A single dataset from the Wind satellite will be used to illustrate all five temporal statistical tools.
Magnetohydrodynamic Turbulence and the Geodynamo
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2014-01-01
The ARES Directorate at JSC has researched the physical processes that create planetary magnetic fields through dynamo action since 2007. The "dynamo problem" has existed since 1600, when William Gilbert, physician to Queen Elizabeth I, recognized that the Earth was a giant magnet. In 1919, Joseph Larmor proposed that solar (and by implication, planetary) magnetism was due to magnetohydrodynamics (MHD), but full acceptance did not occur until Glatzmaier and Roberts solved the MHD equations numerically and simulated a geomagnetic reversal in 1995. JSC research produced a unique theoretical model in 2012 that provided a novel explanation of these physical observations and computational results as an essential manifestation of broken ergodicity in MHD turbulence. Research is ongoing, and future work is aimed at understanding quantitative details of magnetic dipole alignment in the Earth as well as in Mercury, Jupiter and its moon Ganymede, Saturn, Uranus, Neptune, and the Sun and other stars.
Method for manufacturing magnetohydrodynamic electrodes
Killpatrick, Don H.; Thresh, Henry R.
1982-01-01
A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator comprising the steps of preparing a billet having a core 10 of a first metal, a tubular sleeve 12 of a second metal, and an outer sheath 14, 16, 18 of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket 14. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MDH channel frame. The method forms a bond between the first metal of the core 10 and the second metal of the sleeve 12 strong enough to withstand a hot and corrosive environment.
ANISOTROPIC INTERMITTENCY OF MAGNETOHYDRODYNAMIC TURBULENCE
Osman, K. T.; Kiyani, K. H.; Chapman, S. C.; Hnat, B.
2014-03-10
A higher-order multiscale analysis of spatial anisotropy in inertial range magnetohydrodynamic turbulence is presented using measurements from the STEREO spacecraft in fast ambient solar wind. We show for the first time that, when measuring parallel to the local magnetic field direction, the full statistical signature of the magnetic and Elsässer field fluctuations is that of a non-Gaussian globally scale-invariant process. This is distinct from the classic multiexponent statistics observed when the local magnetic field is perpendicular to the flow direction. These observations are interpreted as evidence for the weakness, or absence, of a parallel magnetofluid turbulence energy cascade. As such, these results present strong observational constraints on the statistical nature of intermittency in turbulent plasmas.
Numerical Investigations of Magnetohydrodynamic Turbulence
NASA Astrophysics Data System (ADS)
Mueller, W. C.
2006-12-01
Incompressible magnetohydrodynamic turbulence studied by large-scale direct numerical simulations has revealed a number of new interesting facets. The Goldreich-Sridhar phenomenology partly breaks down in turbulence subject to a strong mean magnetic field. This leads to a measureable anisotropy of two-point statistics. The nonlinear dynamics of kinetic (E^K) and magnetic energy (E^M) is the result of a dynamical equilibrium of Alfvén effect and a small-sale dynamo leading to a scaling relation between total and residual energy: (E^M-E^K)~ k(E^K+E^M)2. The probability density functions of cascading quantities are found to exhibit mono-scaling.
Magnetohydrodynamic turbulence: Observation and experimenta)
NASA Astrophysics Data System (ADS)
Brown, M. R.; Schaffner, D. A.; Weck, P. J.
2015-05-01
We provide a tutorial on the paradigms and tools of magnetohydrodynamic (MHD) turbulence. The principal paradigm is that of a turbulent cascade from large scales to small, resulting in power law behavior for the frequency power spectrum for magnetic fluctuations EB(f ) . We will describe five useful statistical tools for MHD turbulence in the time domain: the temporal autocorrelation function, the frequency power spectrum, the probability distribution function of temporal increments, the temporal structure function, and the permutation entropy. Each of these tools will be illustrated with an example taken from MHD fluctuations in the solar wind. A single dataset from the Wind satellite will be used to illustrate all five temporal statistical tools.
Magnetohydrodynamic Turbulence and the Geodynamo
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2016-01-01
Recent research results concerning forced, dissipative, rotating magnetohydrodynamic (MHD) turbulence will be discussed. In particular, we present new results from long-time Fourier method (periodic box) simulations in which forcing contains varying amounts of magnetic and kinetic helicity. Numerical results indicate that if MHD turbulence is forced so as to produce a state of relatively constant energy, then the largest-scale components are dominant and quasistationary, and in fact, have an effective dipole moment vector that aligns closely with the rotation axis. The relationship of this work to established results in ideal MHD turbulence, as well as to models of MHD turbulence in a spherical shell will also be presented. These results appear to be very pertinent to understanding the Geodynamo and the origin of its dominant dipole component. Our conclusion is that MHD turbulence, per se, may well contain the origin of the Earth's dipole magnetic field.
Weakly nonlinear magnetohydrodynamic wave interactions
Webb, G.M.; Brio, M.; Kruse, M.T.; Zank, G.P.
1999-06-01
Equations describing weakly nonlinear magnetohydrodynamic (MHD) wave interactions in one Cartesian space dimension are discussed. For wave propagation in uniform media, the wave interactions of interest consist of: (a) three-wave resonant interactions in which high frequency waves, may evolve on long space and time scales if the wave phases satisfy the resonance conditions; (b) Burgers self-wave steepening for the magnetoacoustic waves, and (c) mean wave field effects, in which a particular wave interacts with the mean wave field of the other waves. For wave propagation in non-uniform media, further linear wave mixing terms appear in the equations. The equations describe four types of resonant triads: slow-fast magnetosonic wave interaction; Alfv{acute e}n-entropy wave interaction; Alfv{acute e}n-magnetosonic wave interaction; and magnetosonic-entropy wave interaction. The formalism is restricted to coherent wave interactions. {copyright} {ital 1999 American Institute of Physics.}
Micromachined magnetohydrodynamic actuators and sensors
Lee, Abraham P.; Lemoff, Asuncion V.
2000-01-01
A magnetohydrodynamic (MHD) micropump and microsensor which utilizes micromachining to integrate the electrodes with microchannels and includes a magnet for producing magnetic fields perpendicular to both the electrical current direction and the fluid flow direction. The magnet can also be micromachined and integrated with the micropump using existing technology. The MHD micropump, for example, can generate continuous, reversible flow, with readily controllable flow rates. The flow can be reversed by either reversing the electrical current flow or reversing the magnetic field. By mismatching the electrodes, a swirling vortex flow can be generated for potential mixing applications. No moving parts are necessary and the dead volume is minimal. The micropumps can be placed at any position in a fluidic circuit and a combination of micropumps can generate fluidic plugs and valves.
Scaling laws in magnetohydrodynamic turbulence
Campanelli, Leonardo
2004-10-15
We analyze the decay laws of the kinetic and magnetic energies and the evolution of correlation lengths in freely decaying incompressible magnetohydrodynamic (MHD) turbulence. Scale invariance of MHD equations assures that, in the case of constant dissipation parameters (i.e., kinematic viscosity and resistivity) and null magnetic helicity, the kinetic and magnetic energies decay in time as E{approx}t{sup -1}, and the correlation lengths evolve as {xi}{approx}t{sup 1/2}. In the helical case, assuming that the magnetic field evolves towards a force-free state, we show that (in the limit of large magnetic Reynolds number) the magnetic helicity remains constant, and the kinetic and magnetic energies decay as E{sub v}{approx}t{sup -1} and E{sub B}{approx}t{sup -1/2} respectively, while both the kinetic and magnetic correlation lengths grow as {xi}{approx}t{sup 1/2}.
Wow! 3D Content Awakens the Classroom
ERIC Educational Resources Information Center
Gordon, Dan
2010-01-01
From her first encounter with stereoscopic 3D technology designed for classroom instruction, Megan Timme, principal at Hamilton Park Pacesetter Magnet School in Dallas, sensed it could be transformative. Last spring, when she began pilot-testing 3D content in her third-, fourth- and fifth-grade classrooms, Timme wasn't disappointed. Students…
Pathways for Learning from 3D Technology
ERIC Educational Resources Information Center
Carrier, L. Mark; Rab, Saira S.; Rosen, Larry D.; Vasquez, Ludivina; Cheever, Nancy A.
2012-01-01
The purpose of this study was to find out if 3D stereoscopic presentation of information in a movie format changes a viewer's experience of the movie content. Four possible pathways from 3D presentation to memory and learning were considered: a direct connection based on cognitive neuroscience research; a connection through "immersion"…
Wow! 3D Content Awakens the Classroom
ERIC Educational Resources Information Center
Gordon, Dan
2010-01-01
From her first encounter with stereoscopic 3D technology designed for classroom instruction, Megan Timme, principal at Hamilton Park Pacesetter Magnet School in Dallas, sensed it could be transformative. Last spring, when she began pilot-testing 3D content in her third-, fourth- and fifth-grade classrooms, Timme wasn't disappointed. Students…
Infrastructure for 3D Imaging Test Bed
2007-05-11
analysis. (c.) Real time detection & analysis of human gait: using a video camera we capture walking human silhouette for pattern modeling and gait ... analysis . Fig. 5 shows the scanning result result that is fed into a Geo-magic software tool for 3D meshing. Fig. 5: 3D scanning result In
2004-02-12
This 3-D anaglyph, from NASA Mars Exploration Rover Spirit, shows a microscopic image taken of soil featuring round, blueberry-shaped rock formations on the crater floor at Meridiani Planum, Mars. 3D glasses are necessary to view this image.
3D Printing of Molecular Models
ERIC Educational Resources Information Center
Gardner, Adam; Olson, Arthur
2016-01-01
Physical molecular models have played a valuable role in our understanding of the invisible nano-scale world. We discuss 3D printing and its use in producing models of the molecules of life. Complex biomolecular models, produced from 3D printed parts, can demonstrate characteristics of molecular structure and function, such as viral self-assembly,…
ERIC Educational Resources Information Center
Love, Tyler S.; Roy, Ken
2016-01-01
Health concerns from 3D printing were first documented by Stephens, Azimi, Orch, and Ramos (2013), who found that commercially available 3D printers were producing hazardous levels of ultrafine particles (UFPs) and volatile organic compounds (VOCs) when plastic materials were melted through the extruder. UFPs are particles less than 100 nanometers…
3D Printed Block Copolymer Nanostructures
ERIC Educational Resources Information Center
Scalfani, Vincent F.; Turner, C. Heath; Rupar, Paul A.; Jenkins, Alexander H.; Bara, Jason E.
2015-01-01
The emergence of 3D printing has dramatically advanced the availability of tangible molecular and extended solid models. Interestingly, there are few nanostructure models available both commercially and through other do-it-yourself approaches such as 3D printing. This is unfortunate given the importance of nanotechnology in science today. In this…
3D elastic control for mobile devices.
Hachet, Martin; Pouderoux, Joachim; Guitton, Pascal
2008-01-01
To increase the input space of mobile devices, the authors developed a proof-of-concept 3D elastic controller that easily adapts to mobile devices. This embedded device improves the completion of high-level interaction tasks such as visualization of large documents and navigation in 3D environments. It also opens new directions for tomorrow's mobile applications.
Immersive 3D Geovisualization in Higher Education
ERIC Educational Resources Information Center
Philips, Andrea; Walz, Ariane; Bergner, Andreas; Graeff, Thomas; Heistermann, Maik; Kienzler, Sarah; Korup, Oliver; Lipp, Torsten; Schwanghart, Wolfgang; Zeilinger, Gerold
2015-01-01
In this study, we investigate how immersive 3D geovisualization can be used in higher education. Based on MacEachren and Kraak's geovisualization cube, we examine the usage of immersive 3D geovisualization and its usefulness in a research-based learning module on flood risk, called GEOSimulator. Results of a survey among participating students…
Stereo 3-D Vision in Teaching Physics
ERIC Educational Resources Information Center
Zabunov, Svetoslav
2012-01-01
Stereo 3-D vision is a technology used to present images on a flat surface (screen, paper, etc.) and at the same time to create the notion of three-dimensional spatial perception of the viewed scene. A great number of physical processes are much better understood when viewed in stereo 3-D vision compared to standard flat 2-D presentation. The…
3D Printing of Molecular Models
ERIC Educational Resources Information Center
Gardner, Adam; Olson, Arthur
2016-01-01
Physical molecular models have played a valuable role in our understanding of the invisible nano-scale world. We discuss 3D printing and its use in producing models of the molecules of life. Complex biomolecular models, produced from 3D printed parts, can demonstrate characteristics of molecular structure and function, such as viral self-assembly,…
Computer Assisted Cancer Device - 3D Imaging
2006-10-01
tomosynthesis images of the breast. iCAD has identified several sources of 3D tomosynthesis data, and has begun adapting its image analysis...collaborative relationships with major manufacturers of tomosynthesis equipment. 21. iCAD believes that tomosynthesis , a 3D breast imaging technique...purported advantages of tomosynthesis relative to conventional mammography include; improved lesion visibility, improved lesion detectability and
3D Printed Block Copolymer Nanostructures
ERIC Educational Resources Information Center
Scalfani, Vincent F.; Turner, C. Heath; Rupar, Paul A.; Jenkins, Alexander H.; Bara, Jason E.
2015-01-01
The emergence of 3D printing has dramatically advanced the availability of tangible molecular and extended solid models. Interestingly, there are few nanostructure models available both commercially and through other do-it-yourself approaches such as 3D printing. This is unfortunate given the importance of nanotechnology in science today. In this…
Stereo 3-D Vision in Teaching Physics
ERIC Educational Resources Information Center
Zabunov, Svetoslav
2012-01-01
Stereo 3-D vision is a technology used to present images on a flat surface (screen, paper, etc.) and at the same time to create the notion of three-dimensional spatial perception of the viewed scene. A great number of physical processes are much better understood when viewed in stereo 3-D vision compared to standard flat 2-D presentation. The…
Case study of 3D fingerprints applications.
Liu, Feng; Liang, Jinrong; Shen, Linlin; Yang, Meng; Zhang, David; Lai, Zhihui
2017-01-01
Human fingers are 3D objects. More information will be provided if three dimensional (3D) fingerprints are available compared with two dimensional (2D) fingerprints. Thus, this paper firstly collected 3D finger point cloud data by Structured-light Illumination method. Additional features from 3D fingerprint images are then studied and extracted. The applications of these features are finally discussed. A series of experiments are conducted to demonstrate the helpfulness of 3D information to fingerprint recognition. Results show that a quick alignment can be easily implemented under the guidance of 3D finger shape feature even though this feature does not work for fingerprint recognition directly. The newly defined distinctive 3D shape ridge feature can be used for personal authentication with Equal Error Rate (EER) of ~8.3%. Also, it is helpful to remove false core point. Furthermore, a promising of EER ~1.3% is realized by combining this feature with 2D features for fingerprint recognition which indicates the prospect of 3D fingerprint recognition.
A 3D Geostatistical Mapping Tool
Weiss, W. W.; Stevenson, Graig; Patel, Ketan; Wang, Jun
1999-02-09
This software provides accurate 3D reservoir modeling tools and high quality 3D graphics for PC platforms enabling engineers and geologists to better comprehend reservoirs and consequently improve their decisions. The mapping algorithms are fractals, kriging, sequential guassian simulation, and three nearest neighbor methods.
Topology dictionary for 3D video understanding.
Tung, Tony; Matsuyama, Takashi
2012-08-01
This paper presents a novel approach that achieves 3D video understanding. 3D video consists of a stream of 3D models of subjects in motion. The acquisition of long sequences requires large storage space (2 GB for 1 min). Moreover, it is tedious to browse data sets and extract meaningful information. We propose the topology dictionary to encode and describe 3D video content. The model consists of a topology-based shape descriptor dictionary which can be generated from either extracted patterns or training sequences. The model relies on 1) topology description and classification using Reeb graphs, and 2) a Markov motion graph to represent topology change states. We show that the use of Reeb graphs as the high-level topology descriptor is relevant. It allows the dictionary to automatically model complex sequences, whereas other strategies would require prior knowledge on the shape and topology of the captured subjects. Our approach serves to encode 3D video sequences, and can be applied for content-based description and summarization of 3D video sequences. Furthermore, topology class labeling during a learning process enables the system to perform content-based event recognition. Experiments were carried out on various 3D videos. We showcase an application for 3D video progressive summarization using the topology dictionary.
ERIC Educational Resources Information Center
Norbury, Keith
2012-01-01
It may be too soon for students to be showing up for class with popcorn and gummy bears, but technology similar to that behind the 3D blockbuster movie "Avatar" is slowly finding its way into college classrooms. 3D classroom projectors are taking students on fantastic voyages inside the human body, to the ruins of ancient Greece--even to faraway…
Immersive 3D Geovisualization in Higher Education
ERIC Educational Resources Information Center
Philips, Andrea; Walz, Ariane; Bergner, Andreas; Graeff, Thomas; Heistermann, Maik; Kienzler, Sarah; Korup, Oliver; Lipp, Torsten; Schwanghart, Wolfgang; Zeilinger, Gerold
2015-01-01
In this study, we investigate how immersive 3D geovisualization can be used in higher education. Based on MacEachren and Kraak's geovisualization cube, we examine the usage of immersive 3D geovisualization and its usefulness in a research-based learning module on flood risk, called GEOSimulator. Results of a survey among participating students…
ERIC Educational Resources Information Center
Norbury, Keith
2012-01-01
It may be too soon for students to be showing up for class with popcorn and gummy bears, but technology similar to that behind the 3D blockbuster movie "Avatar" is slowly finding its way into college classrooms. 3D classroom projectors are taking students on fantastic voyages inside the human body, to the ruins of ancient Greece--even to faraway…
ERIC Educational Resources Information Center
Love, Tyler S.; Roy, Ken
2016-01-01
Health concerns from 3D printing were first documented by Stephens, Azimi, Orch, and Ramos (2013), who found that commercially available 3D printers were producing hazardous levels of ultrafine particles (UFPs) and volatile organic compounds (VOCs) when plastic materials were melted through the extruder. UFPs are particles less than 100 nanometers…
1955-07-27
DOUGLAS XA3D-1 #413 AIRPLANE MOUNTED IN THE NACA AMES RESEARCH CENTER'S 40X80_FOOT SUBSONIC WIND TUNNEL Testing the boundary layer control of the A3D in the 40 x 80 wind tunnel. Boundary layer control was added to increase the lift of the wing for take off from an aircraft carrier.
1955-07-27
DOUGLAS XA3D-1 #413 AIRPLANE MOUNTED IN THE NACA AMES RESEARCH CENTER'S 40X80_FOOT SUBSONIC WIND TUNNEL sweptback wing Testing the wing boundary layer control of the A3D in the 40 x 80 wind tunnel. Boundary layer control was added to increase the lift of the wing for aircraft carrier take off and landing.
Static & Dynamic Response of 3D Solids
Lin, Jerry
1996-07-15
NIKE3D is a large deformations 3D finite element code used to obtain the resulting displacements and stresses from multi-body static and dynamic structural thermo-mechanics problems with sliding interfaces. Many nonlinear and temperature dependent constitutive models are available.
Integration of real-time 3D image acquisition and multiview 3D display
NASA Astrophysics Data System (ADS)
Zhang, Zhaoxing; Geng, Zheng; Li, Tuotuo; Li, Wei; Wang, Jingyi; Liu, Yongchun
2014-03-01
Seamless integration of 3D acquisition and 3D display systems offers enhanced experience in 3D visualization of the real world objects or scenes. The vivid representation of captured 3D objects displayed on a glasses-free 3D display screen could bring the realistic viewing experience to viewers as if they are viewing real-world scene. Although the technologies in 3D acquisition and 3D display have advanced rapidly in recent years, effort is lacking in studying the seamless integration of these two different aspects of 3D technologies. In this paper, we describe our recent progress on integrating a light-field 3D acquisition system and an autostereoscopic multiview 3D display for real-time light field capture and display. This paper focuses on both the architecture design and the implementation of the hardware and the software of this integrated 3D system. A prototype of the integrated 3D system is built to demonstrate the real-time 3D acquisition and 3D display capability of our proposed system.
Magnetohydrodynamic actuation of droplets for millimetric planar fluidic systems
Ahmadi, A. McDermid, C. M.; Markley, L.
2016-01-04
In this work, a magnetohydrodynamic method is proposed for the actuation of droplets in small-scale planar fluidic systems, providing an alternative to commonly used methods such as electrowetting-on-dielectric. Elementary droplet-based operations, including transport, merging, and mixing, are demonstrated. The forces acting on millimetric droplets are carefully investigated, with a primary focus on the magnetic actuation force and on the unbalanced capillary forces that arise due to hysteresis. A super-hydrophobic channel is 3D printed to guide the droplets, with thin wires installed as contact electrodes and permanent magnets providing a static magnetic field. It is shown that droplet motion is enhanced by increasing the droplet size and minimizing the electrode contact surface. The effects of channel geometry on threshold voltage and minimum moveable droplet volume are characterized. Finally, the presence of electrolysis is investigated and mitigating strategies are discussed.
Quon 3D language for quantum information
Liu, Zhengwei; Wozniakowski, Alex; Jaffe, Arthur M.
2017-01-01
We present a 3D topological picture-language for quantum information. Our approach combines charged excitations carried by strings, with topological properties that arise from embedding the strings in the interior of a 3D manifold with boundary. A quon is a composite that acts as a particle. Specifically, a quon is a hemisphere containing a neutral pair of open strings with opposite charge. We interpret multiquons and their transformations in a natural way. We obtain a type of relation, a string–genus “joint relation,” involving both a string and the 3D manifold. We use the joint relation to obtain a topological interpretation of the C∗-Hopf algebra relations, which are widely used in tensor networks. We obtain a 3D representation of the controlled NOT (CNOT) gate that is considerably simpler than earlier work, and a 3D topological protocol for teleportation. PMID:28167790
NASA Astrophysics Data System (ADS)
Dekker, T.; de Zwart, S. T.; Willemsen, O. H.; Hiddink, M. G. H.; IJzerman, W. L.
2006-02-01
A prerequisite for a wide market acceptance of 3D displays is the ability to switch between 3D and full resolution 2D. In this paper we present a robust and cost effective concept for an auto-stereoscopic switchable 2D/3D display. The display is based on an LCD panel, equipped with switchable LC-filled lenticular lenses. We will discuss 3D image quality, with the focus on display uniformity. We show that slanting the lenticulars in combination with a good lens design can minimize non-uniformities in our 20" 2D/3D monitors. Furthermore, we introduce fractional viewing systems as a very robust concept to further improve uniformity in the case slanting the lenticulars and optimizing the lens design are not sufficient. We will discuss measurements and numerical simulations of the key optical characteristics of this display. Finally, we discuss 2D image quality, the switching characteristics and the residual lens effect.
6D Interpretation of 3D Gravity
NASA Astrophysics Data System (ADS)
Herfray, Yannick; Krasnov, Kirill; Scarinci, Carlos
2017-02-01
We show that 3D gravity, in its pure connection formulation, admits a natural 6D interpretation. The 3D field equations for the connection are equivalent to 6D Hitchin equations for the Chern–Simons 3-form in the total space of the principal bundle over the 3-dimensional base. Turning this construction around one gets an explanation of why the pure connection formulation of 3D gravity exists. More generally, we interpret 3D gravity as the dimensional reduction of the 6D Hitchin theory. To this end, we show that any \\text{SU}(2) invariant closed 3-form in the total space of the principal \\text{SU}(2) bundle can be parametrised by a connection together with a 2-form field on the base. The dimensional reduction of the 6D Hitchin theory then gives rise to 3D gravity coupled to a topological 2-form field.
BEAMS3D Neutral Beam Injection Model
Lazerson, Samuel
2014-04-14
With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.
Fabrication of 3D Silicon Sensors
Kok, A.; Hansen, T.E.; Hansen, T.A.; Lietaer, N.; Summanwar, A.; Kenney, C.; Hasi, J.; Da Via, C.; Parker, S.I.; /Hawaii U.
2012-06-06
Silicon sensors with a three-dimensional (3-D) architecture, in which the n and p electrodes penetrate through the entire substrate, have many advantages over planar silicon sensors including radiation hardness, fast time response, active edge and dual readout capabilities. The fabrication of 3D sensors is however rather complex. In recent years, there have been worldwide activities on 3D fabrication. SINTEF in collaboration with Stanford Nanofabrication Facility have successfully fabricated the original (single sided double column type) 3D detectors in two prototype runs and the third run is now on-going. This paper reports the status of this fabrication work and the resulted yield. The work of other groups such as the development of double sided 3D detectors is also briefly reported.
Biocompatible 3D Matrix with Antimicrobial Properties.
Ion, Alberto; Andronescu, Ecaterina; Rădulescu, Dragoș; Rădulescu, Marius; Iordache, Florin; Vasile, Bogdan Ștefan; Surdu, Adrian Vasile; Albu, Madalina Georgiana; Maniu, Horia; Chifiriuc, Mariana Carmen; Grumezescu, Alexandru Mihai; Holban, Alina Maria
2016-01-20
The aim of this study was to develop, characterize and assess the biological activity of a new regenerative 3D matrix with antimicrobial properties, based on collagen (COLL), hydroxyapatite (HAp), β-cyclodextrin (β-CD) and usnic acid (UA). The prepared 3D matrix was characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Microscopy (FT-IRM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). In vitro qualitative and quantitative analyses performed on cultured diploid cells demonstrated that the 3D matrix is biocompatible, allowing the normal development and growth of MG-63 osteoblast-like cells and exhibited an antimicrobial effect, especially on the Staphylococcus aureus strain, explained by the particular higher inhibitory activity of usnic acid (UA) against Gram positive bacterial strains. Our data strongly recommend the obtained 3D matrix to be used as a successful alternative for the fabrication of three dimensional (3D) anti-infective regeneration matrix for bone tissue engineering.
Relativistic decay widths of autoionization processes: The relativistic FanoADC-Stieltjes method
NASA Astrophysics Data System (ADS)
Fasshauer, Elke; Kolorenč, Přemysl; Pernpointner, Markus
2015-04-01
Electronic decay processes of ionized systems are, for example, the Auger decay or the Interatomic/ Intermolecular Coulombic Decay. In both processes, an energetically low lying vacancy is filled by an electron of an energetically higher lying orbital and a secondary electron is instantaneously emitted to the continuum. Whether or not such a process occurs depends both on the energetic accessibility and the corresponding lifetime compared to the lifetime of competing decay mechanisms. We present a realization of the non-relativistically established FanoADC-Stieltjes method for the description of autoionization decay widths including relativistic effects. This procedure, being based on the Algebraic Diagrammatic Construction (ADC), was adapted to the relativistic framework and implemented into the relativistic quantum chemistry program package Dirac. It is, in contrast to other existing relativistic atomic codes, not limited to the description of autoionization lifetimes in spherically symmetric systems, but is instead also applicable to molecules and clusters. We employ this method to the Auger processes following the Kr3d-1, Xe4d-1, and Rn5d-1 ionization. Based on the results, we show a pronounced influence of mainly scalar-relativistic effects on the decay widths of autoionization processes.
Relativistic decay widths of autoionization processes: the relativistic FanoADC-Stieltjes method.
Fasshauer, Elke; Kolorenč, Přemysl; Pernpointner, Markus
2015-04-14
Electronic decay processes of ionized systems are, for example, the Auger decay or the Interatomic/ Intermolecular Coulombic Decay. In both processes, an energetically low lying vacancy is filled by an electron of an energetically higher lying orbital and a secondary electron is instantaneously emitted to the continuum. Whether or not such a process occurs depends both on the energetic accessibility and the corresponding lifetime compared to the lifetime of competing decay mechanisms. We present a realization of the non-relativistically established FanoADC-Stieltjes method for the description of autoionization decay widths including relativistic effects. This procedure, being based on the Algebraic Diagrammatic Construction (ADC), was adapted to the relativistic framework and implemented into the relativistic quantum chemistry program package Dirac. It is, in contrast to other existing relativistic atomic codes, not limited to the description of autoionization lifetimes in spherically symmetric systems, but is instead also applicable to molecules and clusters. We employ this method to the Auger processes following the Kr3d(-1), Xe4d(-1), and Rn5d(-1) ionization. Based on the results, we show a pronounced influence of mainly scalar-relativistic effects on the decay widths of autoionization processes.
Relativistic decay widths of autoionization processes: The relativistic FanoADC-Stieltjes method
Fasshauer, Elke; Kolorenč, Přemysl; Pernpointner, Markus
2015-04-14
Electronic decay processes of ionized systems are, for example, the Auger decay or the Interatomic/ Intermolecular Coulombic Decay. In both processes, an energetically low lying vacancy is filled by an electron of an energetically higher lying orbital and a secondary electron is instantaneously emitted to the continuum. Whether or not such a process occurs depends both on the energetic accessibility and the corresponding lifetime compared to the lifetime of competing decay mechanisms. We present a realization of the non-relativistically established FanoADC-Stieltjes method for the description of autoionization decay widths including relativistic effects. This procedure, being based on the Algebraic Diagrammatic Construction (ADC), was adapted to the relativistic framework and implemented into the relativistic quantum chemistry program package Dirac. It is, in contrast to other existing relativistic atomic codes, not limited to the description of autoionization lifetimes in spherically symmetric systems, but is instead also applicable to molecules and clusters. We employ this method to the Auger processes following the Kr3d{sup −1}, Xe4d{sup −1}, and Rn5d{sup −1} ionization. Based on the results, we show a pronounced influence of mainly scalar-relativistic effects on the decay widths of autoionization processes.
3D Ultrafast Ultrasound Imaging In Vivo
Provost, Jean; Papadacci, Clement; Arango, Juan Esteban; Imbault, Marion; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu
2014-01-01
Very high frame rate ultrasound imaging has recently allowed for the extension of the applications of echography to new fields of study such as the functional imaging of the brain, cardiac electrophysiology, and the quantitative real-time imaging of the intrinsic mechanical properties of tumors, to name a few, non-invasively and in real time. In this study, we present the first implementation of Ultrafast Ultrasound Imaging in three dimensions based on the use of either diverging or plane waves emanating from a sparse virtual array located behind the probe. It achieves high contrast and resolution while maintaining imaging rates of thousands of volumes per second. A customized portable ultrasound system was developed to sample 1024 independent channels and to drive a 32×32 matrix-array probe. Its capability to track in 3D transient phenomena occurring in the millisecond range within a single ultrafast acquisition was demonstrated for 3-D Shear-Wave Imaging, 3-D Ultrafast Doppler Imaging and finally 3D Ultrafast combined Tissue and Flow Doppler. The propagation of shear waves was tracked in a phantom and used to characterize its stiffness. 3-D Ultrafast Doppler was used to obtain 3-D maps of Pulsed Doppler, Color Doppler, and Power Doppler quantities in a single acquisition and revealed, for the first time, the complex 3-D flow patterns occurring in the ventricles of the human heart during an entire cardiac cycle, and the 3-D in vivo interaction of blood flow and wall motion during the pulse wave in the carotid at the bifurcation. This study demonstrates the potential of 3-D Ultrafast Ultrasound Imaging for the 3-D real-time mapping of stiffness, tissue motion, and flow in humans in vivo and promises new clinical applications of ultrasound with reduced intra- and inter-observer variability. PMID:25207828
Pathways for Learning from 3D Technology
Carrier, L. Mark; Rab, Saira S.; Rosen, Larry D.; Vasquez, Ludivina; Cheever, Nancy A.
2016-01-01
The purpose of this study was to find out if 3D stereoscopic presentation of information in a movie format changes a viewer's experience of the movie content. Four possible pathways from 3D presentation to memory and learning were considered: a direct connection based on cognitive neuroscience research; a connection through "immersion" in that 3D presentations could provide additional sensorial cues (e.g., depth cues) that lead to a higher sense of being surrounded by the stimulus; a connection through general interest such that 3D presentation increases a viewer’s interest that leads to greater attention paid to the stimulus (e.g., "involvement"); and a connection through discomfort, with the 3D goggles causing discomfort that interferes with involvement and thus with memory. The memories of 396 participants who viewed two-dimensional (2D) or 3D movies at movie theaters in Southern California were tested. Within three days of viewing a movie, participants filled out an online anonymous questionnaire that queried them about their movie content memories, subjective movie-going experiences (including emotional reactions and "presence") and demographic backgrounds. The responses to the questionnaire were subjected to path analyses in which several different links between 3D presentation to memory (and other variables) were explored. The results showed there were no effects of 3D presentation, either directly or indirectly, upon memory. However, the largest effects of 3D presentation were on emotions and immersion, with 3D presentation leading to reduced positive emotions, increased negative emotions and lowered immersion, compared to 2D presentations. PMID:28078331
3D Visualization Development of SIUE Campus
NASA Astrophysics Data System (ADS)
Nellutla, Shravya
Geographic Information Systems (GIS) has progressed from the traditional map-making to the modern technology where the information can be created, edited, managed and analyzed. Like any other models, maps are simplified representations of real world. Hence visualization plays an essential role in the applications of GIS. The use of sophisticated visualization tools and methods, especially three dimensional (3D) modeling, has been rising considerably due to the advancement of technology. There are currently many off-the-shelf technologies available in the market to build 3D GIS models. One of the objectives of this research was to examine the available ArcGIS and its extensions for 3D modeling and visualization and use them to depict a real world scenario. Furthermore, with the advent of the web, a platform for accessing and sharing spatial information on the Internet, it is possible to generate interactive online maps. Integrating Internet capacity with GIS functionality redefines the process of sharing and processing the spatial information. Enabling a 3D map online requires off-the-shelf GIS software, 3D model builders, web server, web applications and client server technologies. Such environments are either complicated or expensive because of the amount of hardware and software involved. Therefore, the second objective of this research was to investigate and develop simpler yet cost-effective 3D modeling approach that uses available ArcGIS suite products and the free 3D computer graphics software for designing 3D world scenes. Both ArcGIS Explorer and ArcGIS Online will be used to demonstrate the way of sharing and distributing 3D geographic information on the Internet. A case study of the development of 3D campus for the Southern Illinois University Edwardsville is demonstrated.
The psychology of the 3D experience
NASA Astrophysics Data System (ADS)
Janicke, Sophie H.; Ellis, Andrew
2013-03-01
With 3D televisions expected to reach 50% home saturation as early as 2016, understanding the psychological mechanisms underlying the user response to 3D technology is critical for content providers, educators and academics. Unfortunately, research examining the effects of 3D technology has not kept pace with the technology's rapid adoption, resulting in large-scale use of a technology about which very little is actually known. Recognizing this need for new research, we conducted a series of studies measuring and comparing many of the variables and processes underlying both 2D and 3D media experiences. In our first study, we found narratives within primetime dramas had the power to shift viewer attitudes in both 2D and 3D settings. However, we found no difference in persuasive power between 2D and 3D content. We contend this lack of effect was the result of poor conversion quality and the unique demands of 3D production. In our second study, we found 3D technology significantly increased enjoyment when viewing sports content, yet offered no added enjoyment when viewing a movie trailer. The enhanced enjoyment of the sports content was shown to be the result of heightened emotional arousal and attention in the 3D condition. We believe the lack of effect found for the movie trailer may be genre-related. In our final study, we found 3D technology significantly enhanced enjoyment of two video games from different genres. The added enjoyment was found to be the result of an increased sense of presence.
Relativistic Magnetic Reconnection in Kerr Spacetime.
Asenjo, Felipe A; Comisso, Luca
2017-02-03
The magnetic reconnection process is analyzed for relativistic magnetohydrodynamical plasmas around rotating black holes. A simple generalization of the Sweet-Parker model is used as a first approximation to the problem. The reconnection rate, as well as other important properties of the reconnection layer, has been calculated taking into account the effect of spacetime curvature. Azimuthal and radial current sheet configurations in the equatorial plane of the black hole have been studied, and the case of small black hole rotation rate has been analyzed. For the azimuthal configuration, it is found that the black hole rotation decreases the reconnection rate. On the other hand, in the radial configuration, it is the gravitational force created by the black hole mass that decreases the reconnection rate. These results establish a fundamental interaction between gravity and magnetic reconnection in astrophysical contexts.
Relativistic Magnetic Reconnection in Kerr Spacetime
NASA Astrophysics Data System (ADS)
Asenjo, Felipe A.; Comisso, Luca
2017-02-01
The magnetic reconnection process is analyzed for relativistic magnetohydrodynamical plasmas around rotating black holes. A simple generalization of the Sweet-Parker model is used as a first approximation to the problem. The reconnection rate, as well as other important properties of the reconnection layer, has been calculated taking into account the effect of spacetime curvature. Azimuthal and radial current sheet configurations in the equatorial plane of the black hole have been studied, and the case of small black hole rotation rate has been analyzed. For the azimuthal configuration, it is found that the black hole rotation decreases the reconnection rate. On the other hand, in the radial configuration, it is the gravitational force created by the black hole mass that decreases the reconnection rate. These results establish a fundamental interaction between gravity and magnetic reconnection in astrophysical contexts.
RELAP5-3D Code Includes Athena Features and Models
Richard A. Riemke; Cliff B. Davis; Richard R. Schultz
2006-07-01
Version 2.3 of the RELAP5-3D computer program includes all features and models previously available only in the ATHENA version of the code. These include the addition of new working fluids (i.e., ammonia, blood, carbon dioxide, glycerol, helium, hydrogen, lead-bismuth, lithium, lithium-lead, nitrogen, potassium, sodium, and sodium-potassium) and a magnetohydrodynamic model that expands the capability of the code to model many more thermal-hydraulic systems. In addition to the new working fluids along with the standard working fluid water, one or more noncondensable gases (e.g., air, argon, carbon dioxide, carbon monoxide, helium, hydrogen, krypton, nitrogen, oxygen, sf6, xenon) can be specified as part of the vapor/gas phase of the working fluid. These noncondensable gases were in previous versions of RELAP5- 3D. Recently four molten salts have been added as working fluids to RELAP5-3D Version 2.4, which has had limited release. These molten salts will be in RELAP5-3D Version 2.5, which will have a general release like RELAP5-3D Version 2.3. Applications that use these new features and models are discussed in this paper.
Evidence of toroidally localized turbulence with applied 3D fields in the DIII-D tokamak
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.
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.
Evidence of Toroidally Localized Turbulence with Applied 3D Fields in the DIII-D Tokamak.
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.
Evidence of toroidally localized turbulence with applied 3D fields in the DIII-D tokamak
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.
Numerical non-LTE 3D radiative transfer using a multigrid method
NASA Astrophysics Data System (ADS)
Bjørgen, Johan P.; Leenaarts, Jorrit
2017-03-01
Context. 3D non-LTE radiative transfer problems are computationally demanding, and this sets limits on the size of the problems that can be solved. So far, multilevel accelerated lambda iteration (MALI) has been the method of choice to perform high-resolution computations in multidimensional problems. The disadvantage of MALI is that its computing time scales as O(n2), with n the number of grid points. When the grid becomes finer, the computational cost increases quadratically. Aims: We aim to develop a 3D non-LTE radiative transfer code that is more efficient than MALI. Methods: We implement a non-linear multigrid, fast approximation storage scheme, into the existing Multi3D radiative transfer code. We verify our multigrid implementation by comparing with MALI computations. We show that multigrid can be employed in realistic problems with snapshots from 3D radiative magnetohydrodynamics (MHD) simulations as input atmospheres. Results: With multigrid, we obtain a factor 3.3-4.5 speed-up compared to MALI. With full-multigrid, the speed-up increases to a factor 6. The speed-up is expected to increase for input atmospheres with more grid points and finer grid spacing. Conclusions: Solving 3D non-LTE radiative transfer problems using non-linear multigrid methods can be applied to realistic atmospheres with a substantial increase in speed.
Evidence of toroidally localized turbulence with applied 3D fields in the DIII-D tokamak
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
Propulsive Efficiencies of Magnetohydrodynamic Submerged Vehicular Propulsors
1990-04-01
Research and Development Report Propulsive Efficiencies of Magnetohydrodynamic Submerged Vehicular Propulsors by S. H. Brown, J.S. Walker, N.A...Analysis of Magnetohydrodynamic Propulsors ." In addition, this work was partially supported by the DTRC Block Program sponsored by ONT (Gene Remmers), Work...Vehicular Propulsors 1•. PERSONAL AUTHOR(S) Samuel H. Brown, John S. Walker, Neal A. Sondergaard, Patrick J. Reilly, and David E. Bagley 13L. TYPE OF REPORT
Optically rewritable 3D liquid crystal displays.
Sun, J; Srivastava, A K; Zhang, W; Wang, L; Chigrinov, V G; Kwok, H S
2014-11-01
Optically rewritable liquid crystal display (ORWLCD) is a concept based on the optically addressed bi-stable display that does not need any power to hold the image after being uploaded. Recently, the demand for the 3D image display has increased enormously. Several attempts have been made to achieve 3D image on the ORWLCD, but all of them involve high complexity for image processing on both hardware and software levels. In this Letter, we disclose a concept for the 3D-ORWLCD by dividing the given image in three parts with different optic axis. A quarter-wave plate is placed on the top of the ORWLCD to modify the emerging light from different domains of the image in different manner. Thereafter, Polaroid glasses can be used to visualize the 3D image. The 3D image can be refreshed, on the 3D-ORWLCD, in one-step with proper ORWLCD printer and image processing, and therefore, with easy image refreshing and good image quality, such displays can be applied for many applications viz. 3D bi-stable display, security elements, etc.
Medical 3D Printing for the Radiologist.
Mitsouras, Dimitris; Liacouras, Peter; Imanzadeh, Amir; Giannopoulos, Andreas A; Cai, Tianrun; Kumamaru, Kanako K; George, Elizabeth; Wake, Nicole; Caterson, Edward J; Pomahac, Bohdan; Ho, Vincent B; Grant, Gerald T; Rybicki, Frank J
2015-01-01
While use of advanced visualization in radiology is instrumental in diagnosis and communication with referring clinicians, there is an unmet need to render Digital Imaging and Communications in Medicine (DICOM) images as three-dimensional (3D) printed models capable of providing both tactile feedback and tangible depth information about anatomic and pathologic states. Three-dimensional printed models, already entrenched in the nonmedical sciences, are rapidly being embraced in medicine as well as in the lay community. Incorporating 3D printing from images generated and interpreted by radiologists presents particular challenges, including training, materials and equipment, and guidelines. The overall costs of a 3D printing laboratory must be balanced by the clinical benefits. It is expected that the number of 3D-printed models generated from DICOM images for planning interventions and fabricating implants will grow exponentially. Radiologists should at a minimum be familiar with 3D printing as it relates to their field, including types of 3D printing technologies and materials used to create 3D-printed anatomic models, published applications of models to date, and clinical benefits in radiology. Online supplemental material is available for this article. (©)RSNA, 2015.
3D imaging in forensic odontology.
Evans, Sam; Jones, Carl; Plassmann, Peter
2010-06-16
This paper describes the investigation of a new 3D capture method for acquiring and subsequent forensic analysis of bite mark injuries on human skin. When documenting bite marks with standard 2D cameras errors in photographic technique can occur if best practice is not followed. Subsequent forensic analysis of the mark is problematic when a 3D structure is recorded into a 2D space. Although strict guidelines (BAFO) exist, these are time-consuming to follow and, due to their complexity, may produce errors. A 3D image capture and processing system might avoid the problems resulting from the 2D reduction process, simplifying the guidelines and reducing errors. Proposed Solution: a series of experiments are described in this paper to demonstrate that the potential of a 3D system might produce suitable results. The experiments tested precision and accuracy of the traditional 2D and 3D methods. A 3D image capture device minimises the amount of angular distortion, therefore such a system has the potential to create more robust forensic evidence for use in courts. A first set of experiments tested and demonstrated which method of forensic analysis creates the least amount of intra-operator error. A second set tested and demonstrated which method of image capture creates the least amount of inter-operator error and visual distortion. In a third set the effects of angular distortion on 2D and 3D methods of image capture were evaluated.
NUBEAM developments and 3d halo modeling
NASA Astrophysics Data System (ADS)
Gorelenkova, M. V.; Medley, S. S.; Kaye, S. M.
2012-10-01
Recent developments related to the 3D halo model in NUBEAM code are described. To have a reliable halo neutral source for diagnostic simulation, the TRANSP/NUBEAM code has been enhanced with full implementation of ADAS atomic physic ground state and excited state data for hydrogenic beams and mixed species plasma targets. The ADAS codes and database provide the density and temperature dependence of the atomic data, and the collective nature of the state excitation process. To be able to populate 3D halo output with sufficient statistical resolution, the capability to control the statistics of fast ion CX modeling and for thermal halo launch has been added to NUBEAM. The 3D halo neutral model is based on modification and extension of the ``beam in box'' aligned 3d Cartesian grid that includes the neutral beam itself, 3D fast neutral densities due to CX of partially slowed down fast ions in the beam halo region, 3D thermal neutral densities due to CX deposition and fast neutral recapture source. More details on the 3D halo simulation design will be presented.
Medical 3D Printing for the Radiologist
Mitsouras, Dimitris; Liacouras, Peter; Imanzadeh, Amir; Giannopoulos, Andreas A.; Cai, Tianrun; Kumamaru, Kanako K.; George, Elizabeth; Wake, Nicole; Caterson, Edward J.; Pomahac, Bohdan; Ho, Vincent B.; Grant, Gerald T.
2015-01-01
While use of advanced visualization in radiology is instrumental in diagnosis and communication with referring clinicians, there is an unmet need to render Digital Imaging and Communications in Medicine (DICOM) images as three-dimensional (3D) printed models capable of providing both tactile feedback and tangible depth information about anatomic and pathologic states. Three-dimensional printed models, already entrenched in the nonmedical sciences, are rapidly being embraced in medicine as well as in the lay community. Incorporating 3D printing from images generated and interpreted by radiologists presents particular challenges, including training, materials and equipment, and guidelines. The overall costs of a 3D printing laboratory must be balanced by the clinical benefits. It is expected that the number of 3D-printed models generated from DICOM images for planning interventions and fabricating implants will grow exponentially. Radiologists should at a minimum be familiar with 3D printing as it relates to their field, including types of 3D printing technologies and materials used to create 3D-printed anatomic models, published applications of models to date, and clinical benefits in radiology. Online supplemental material is available for this article. ©RSNA, 2015 PMID:26562233
3D bioprinting of tissues and organs.
Murphy, Sean V; Atala, Anthony
2014-08-01
Additive manufacturing, otherwise known as three-dimensional (3D) printing, is driving major innovations in many areas, such as engineering, manufacturing, art, education and medicine. Recent advances have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine to address the need for tissues and organs suitable for transplantation. Compared with non-biological printing, 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the sensitivities of living cells and the construction of tissues. Addressing these complexities requires the integration of technologies from the fields of engineering, biomaterials science, cell biology, physics and medicine. 3D bioprinting has already been used for the generation and transplantation of several tissues, including multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures. Other applications include developing high-throughput 3D-bioprinted tissue models for research, drug discovery and toxicology.
Quasi-3D electron cyclotron emission imaging on J-TEXT
NASA Astrophysics Data System (ADS)
Zhao, Zhenling; Zhu, Yilun; Tong, Li; Xie, Jinlin; Liu, Wandong; Yu, Changxuan; Yang, Zhoujun; Zhuang, Ge; Luhmann, N. C., Jr.; Domier, C. W.
2017-09-01
Electron cyclotron emission imaging (ECEI) can provide measurements of 2D electron temperature fluctuation with high temporal and spatial resolution in magnetic fusion plasma devices. Two ECEI systems located in different toroidal ports with 67.5 degree separation have been implemented on J-TEXT to study the 3D structure of magnetohydrodynamic (MHD) instabilities. Each system consists of 12 (vertical) × 16 (horizontal) = 192 channels and the image of the 2nd harmonic X-mode electron cyclotron emission can be captured continuously in the core plasma region. The field curvature adjustment lens concept is developed to control the imaging plane for receiving optics of the ECEI systems. Field curvature of the image can be controlled to match the emission layer. Consequently, a quasi-3D image of the MHD instability in the core of the plasma has been achieved.
Relativistic Plasma Polarizer: Impact of Temperature Anisotropy on Relativistic Transparency
NASA Astrophysics Data System (ADS)
Hazeltine, R. D.; Stark, David J.; Bhattacharjee, Chinmoy; Arefiev, Alexey V.; Toncian, Toma; Mahajan, S. M.
2015-11-01
3D particle-in-cell simulations demonstrate that the enhanced transparency of a relativistically hot plasma is sensitive to how the energy is partitioned between different degrees of freedom. We consider here the simplest problem: the propagation of a low amplitude pulse through a preformed relativistically hot anisotropic electron plasma to explore its intrinsic dielectric properties. We find that: 1) the critical density for propagation depends strongly on the pulse polarization, 2) two plasmas with the same density and average energy per electron can exhibit profoundly different responses to electromagnetic pulses, 3) the anisotropy-driven Weibel instability develops as expected; the timescales of the growth and back reaction (on anisotropy), however, are long enough that sufficient anisotropy persists for the entire duration of the simulation. This plasma can then function as a polarizer or a wave plate to dramatically alter the pulse polarization. This work was supported by the U.S. DOE Contract Nos. DE-FG02-04ER54742 and DE-AC05-06OR23100 (D. J. S.) and NNSA Contract No. DE-FC52-08NA28512.
Extra Dimensions: 3D in PDF Documentation
NASA Astrophysics Data System (ADS)
Graf, Norman A.
2012-12-01
Experimental science is replete with multi-dimensional information which is often poorly represented by the two dimensions of presentation slides and print media. Past efforts to disseminate such information to a wider audience have failed for a number of reasons, including a lack of standards which are easy to implement and have broad support. Adobe's Portable Document Format (PDF) has in recent years become the de facto standard for secure, dependable electronic information exchange. It has done so by creating an open format, providing support for multiple platforms and being reliable and extensible. By providing support for the ECMA standard Universal 3D (U3D) and the ISO PRC file format in its free Adobe Reader software, Adobe has made it easy to distribute and interact with 3D content. Until recently, Adobe's Acrobat software was also capable of incorporating 3D content into PDF files from a variety of 3D file formats, including proprietary CAD formats. However, this functionality is no longer available in Acrobat X, having been spun off to a separate company. Incorporating 3D content now requires the additional purchase of a separate plug-in. In this talk we present alternatives based on open source libraries which allow the programmatic creation of 3D content in PDF format. While not providing the same level of access to CAD files as the commercial software, it does provide physicists with an alternative path to incorporate 3D content into PDF files from such disparate applications as detector geometries from Geant4, 3D data sets, mathematical surfaces or tesselated volumes.
Relativistic Linear Restoring Force
ERIC Educational Resources Information Center
Clark, D.; Franklin, J.; Mann, N.
2012-01-01
We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…
Relativistic Guiding Center Equations
White, R. B.; Gobbin, M.
2014-10-01
In toroidal fusion devices it is relatively easy that electrons achieve relativistic velocities, so to simulate runaway electrons and other high energy phenomena a nonrelativistic guiding center formalism is not sufficient. Relativistic guiding center equations including flute mode time dependent field perturbations are derived. The same variables as used in a previous nonrelativistic guiding center code are adopted, so that a straightforward modifications of those equations can produce a relativistic version.
Relativistic Linear Restoring Force
ERIC Educational Resources Information Center
Clark, D.; Franklin, J.; Mann, N.
2012-01-01
We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…
Multi-D magnetohydrodynamic modelling of pulsar wind nebulae: recent progress and open questions
NASA Astrophysics Data System (ADS)
Olmi, B.; Del Zanna, L.; Amato, E.; Bucciantini, N.; Mignone, A.
2016-12-01
In the last decade, the relativistic magnetohydrodynamic (MHD) modelling of pulsar wind nebulae, and of the Crab nebula in particular, has been highly successful, with many of the observed dynamical and emission properties reproduced down to the finest detail. Here, we critically discuss the results of some of the most recent studies: namely the investigation of the origin of the radio emitting particles and the quest for the acceleration sites of particles of different energies along the termination shock, by using wisp motions as a diagnostic tool; the study of the magnetic dissipation process in high magnetization nebulae by means of new long-term three-dimensional simulations of the pulsar wind nebula evolution; the investigation of the relativistic tearing instability in thinning current sheets, leading to fast reconnection events that might be at the origin of the Crab nebula gamma-ray flares.
2015-04-23
A new type of graphene aerogel will make for better energy storage, sensors, nanoelectronics, catalysis and separations. Lawrence Livermore National Laboratory researchers have made graphene aerogel microlattices with an engineered architecture via a 3D printing technique known as direct ink writing. The research appears in the April 22 edition of the journal, Nature Communications. The 3D printed graphene aerogels have high surface area, excellent electrical conductivity, are lightweight, have mechanical stiffness and exhibit supercompressibility (up to 90 percent compressive strain). In addition, the 3D printed graphene aerogel microlattices show an order of magnitude improvement over bulk graphene materials and much better mass transport.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.;
2014-01-01
This manual describes the installation and execution of FUN3D version 12.4, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixedelement unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Carlson, Jan-Renee; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2016-01-01
This manual describes the installation and execution of FUN3D version 12.9, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Carlson, Jan-Renee; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bill; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2016-01-01
This manual describes the installation and execution of FUN3D version 13.0, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Carlson, Jan-Renee; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2017-01-01
This manual describes the installation and execution of FUN3D version 13.1, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.