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Sample records for 3d particle simulations

  1. 3-D Particle Simulation of Current Sheet Instabilities

    NASA Astrophysics Data System (ADS)

    Wang, Zhenyu; Lin, Yu; Wang, Xueyi; Tummel, Kurt; Chen, Liu

    2015-11-01

    The electrostatic (ES) and electromagnetic (EM) instabilities of a Harris current sheet are investigated using a 3-D linearized (δf) gyrokinetic (GK) electron and fully kinetic (FK) ion (GeFi) particle simulation code. The equilibrium magnetic field consists of an asymptotic anti-parallel Bx 0 and a guide field BG. The ES simulations show the excitation of lower-hybrid drift instability (LHDI) at the current sheet edge. The growth rate of the 3-D LHDI is scanned through the (kx ,ky) space. The most unstable modes are found to be at k∥ = 0 for smaller ky. As ky increases, the growth rate shows two peaks at k∥ ≠ 0 , consistent with analytical GK theory. The eigenmode structure and growth rate of LHDI obtained from the GeFi simulation agree well with those obtained from the FK PIC simulation. Decreasing BG, the asymptotic βe 0, or background density can destabilize the LHDI. In the EM simulation, tearing mode instability is dominant in the cases with ky kx , there exist two unstable modes: a kink-like (LHDI) mode at the current sheet edge and a sausage-like mode at the sheet center. The results are compared with the GK eigenmode theory and the FK simulation.

  2. Development of a 3D particle treecode for plasma simulations

    NASA Astrophysics Data System (ADS)

    Ong, Benjamin; Christlieb, Andrew; Krasny, Robert

    2008-11-01

    In this work we present a fully 3-D Boundary Integral Treecode (BIT). We apply the method to several classic problems such as sheath formation and 3D simulations of a Penning trap. In addition, we investigate the ability of the solver to naturally capture Coloumb scattering. A key point in the investigation is to understand the effect of different types of regularizations, and how to appropriately incorporate the regularization in the BIT framework. This work builds on substantial efforts in 1- and 2-D. [1] R. Krasny and K. Lindsay, A particle method and adaptive treecode for vortex sheet motion in 3-D flow, JCP, Vol. 172, No. 2, 879-907 [2] K. Matyash, R. Schneider, R. Sydora, and F. Taccogna, Application of a Grid-Free Kinetic Model to the Collisionless Sheath, Contrib. Plasma Phys, Vol. 48, No. 1-3, 116-120 (2008) [3] K. Cartwright and A. Christlieb, Boundary Integral Corrected Particle in Cell, SIAM Journal on Sci. Comput., submitted [4] A. Christlieb, R. Krasny, B. Ong and J. Qiu, A Step Towards Addressing Temporal Multi-scale Problems in Plasma Physics, in prep.

  3. 3-D Spreadsheet Simulation of a Modern Particle Detector

    ERIC Educational Resources Information Center

    Scott, Alan J.

    2004-01-01

    A spreadsheet simulation of a modern particle detector has been developed and can be readily used as an instructional tool in the physics classroom. The spreadsheet creates a three-dimensional model that can be rotated and helical trajectories can be highlighted. An associated student worksheet is also presented.

  4. Particle Acceleration in the Low Corona Over Broad Longitudes: Coupling MHD and 3D Particle Simulations

    NASA Astrophysics Data System (ADS)

    Gorby, M.; Schwadron, N.; Torok, T.; Downs, C.; Lionello, R.; Linker, J.; Titov, V. S.; Mikic, Z.; Riley, P.; Desai, M. I.; Dayeh, M. A.

    2014-12-01

    Recent work on the coupling between the Energetic Particle Radiation Environment Module (EPREM, a 3D energetic particle model) and Magnetohydrodynamics Around a Sphere (MAS, an MHD code developed at Predictive Science, Inc.) has demonstrated the efficacy of compression regions around fast coronal mass ejections (CMEs) for particle acceleration low in the corona (˜ 3 - 6 solar radii). These couplings show rapid particle acceleration over a broad longitudinal extent (˜ 80 degrees) resulting from the pile-up of magnetic flux in the compression regions and their subsequent expansion. The challenge for forming large SEP events in such compression-acceleration scenarios is to have enhanced scattering within the acceleration region while also allowing for efficient escape of accelerated particles downstream (away from the Sun) from the compression region. We present here the most recent simulation results including energetic particle and CME plasma profiles, the subsequent flux and dosages at 1AU, and an analysis of the compressional regions as efficient accelerators.

  5. Effect of Model Scale and Particle Size Distribution on PFC3D Simulation Results

    NASA Astrophysics Data System (ADS)

    Ding, Xiaobin; Zhang, Lianyang; Zhu, Hehua; Zhang, Qi

    2014-11-01

    This paper investigates the effect of model scale and particle size distribution on the simulated macroscopic mechanical properties, unconfined compressive strength (UCS), Young's modulus and Poisson's ratio, using the three-dimensional particle flow code (PFC3D). Four different maximum to minimum particle size ( d max/ d min) ratios, all having a continuous uniform size distribution, were considered and seven model (specimen) diameter to median particle size ratios ( L/ d) were studied for each d max/ d min ratio. The results indicate that the coefficients of variation (COVs) of the simulated macroscopic mechanical properties using PFC3D decrease significantly as L/ d increases. The results also indicate that the simulated mechanical properties using PFC3D show much lower COVs than those in PFC2D at all model scales. The average simulated UCS and Young's modulus using the default PFC3D procedure keep increasing with larger L/ d, although the rate of increase decreases with larger L/ d. This is mainly caused by the decrease of model porosity with larger L/ d associated with the default PFC3D method and the better balanced contact force chains at larger L/ d. After the effect of model porosity is eliminated, the results on the net model scale effect indicate that the average simulated UCS still increases with larger L/ d but the rate is much smaller, the average simulated Young's modulus decreases with larger L/ d instead, and the average simulated Poisson's ratio versus L/ d relationship remains about the same. Particle size distribution also affects the simulated macroscopic mechanical properties, larger d max/ d min leading to greater average simulated UCS and Young's modulus and smaller average simulated Poisson's ratio, and the changing rates become smaller at larger d max/ d min. This study shows that it is important to properly consider the effect of model scale and particle size distribution in PFC3D simulations.

  6. M3D-K simulations of sawteeth and energetic particle transport in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Shen, Wei; Fu, G. Y.; Sheng, Zheng-Mao; Breslau, J. A.; Wang, Feng

    2014-09-01

    Nonlinear simulations of sawteeth and related energetic particle transport are carried out using the kinetic/magnetohydrodynamic (MHD) hybrid code M3D-K. MHD simulations show repeated sawtooth cycles for a model tokamak equilibrium. Furthermore, test particle simulations are carried out to study the energetic particle transport due to a sawtooth crash. The results show that energetic particles are redistributed radially in the plasma core, depending on pitch angle and energy. For trapped particles, the redistribution occurs for particle energy below a critical value in agreement with existing theories. For co-passing particles, the redistribution is strong with little dependence on particle energy. In contrast, the redistribution level of counter-passing particles decreases with increasing particle energy.

  7. M3D-K Simulations of Sawteeth and Energetic Particle Transport in Tokamak Plasmas

    NASA Astrophysics Data System (ADS)

    Shen, Wei; Fu, Guoyong; Sheng, Zhengmao; Breslau, Joshua; Wang, Feng

    2013-10-01

    Nonlinear simulations of Sawteeth and energetic particle transport are carried out using the kinetic/MHD hybrid code M3D-K. MHD simulations show repeated sawtooth cycles due to a resistive (1,1) internal kink mode for a model tokamak equilibrium. Furthermore, test particle simulations are carried out to study the energetic particle transport due to a sawtooth crash. The results show that energetic particles are redistributed radially in plasma core depending on pitch angle and energy. For trapped particles, the redistribution occurs for particle energy below a critical value in agreement with previous theory. For co-passing particles, the redistribution is strong with little dependence on particle energy. In contrast, the redistribution level of counter-passing particles decreases as particle energy becomes large.

  8. M3D-K simulations of sawteeth and energetic particle transport in tokamak plasmas

    SciTech Connect

    Shen, Wei; Sheng, Zheng-Mao; Fu, G. Y.; Breslau, J. A.; Wang, Feng

    2014-09-15

    Nonlinear simulations of sawteeth and related energetic particle transport are carried out using the kinetic/magnetohydrodynamic (MHD) hybrid code M3D-K. MHD simulations show repeated sawtooth cycles for a model tokamak equilibrium. Furthermore, test particle simulations are carried out to study the energetic particle transport due to a sawtooth crash. The results show that energetic particles are redistributed radially in the plasma core, depending on pitch angle and energy. For trapped particles, the redistribution occurs for particle energy below a critical value in agreement with existing theories. For co-passing particles, the redistribution is strong with little dependence on particle energy. In contrast, the redistribution level of counter-passing particles decreases with increasing particle energy.

  9. Simulation of surface tension in 2D and 3D with smoothed particle hydrodynamics method

    NASA Astrophysics Data System (ADS)

    Zhang, Mingyu

    2010-09-01

    The methods for simulating surface tension with smoothed particle hydrodynamics (SPH) method in two dimensions and three dimensions are developed. In 2D surface tension model, the SPH particle on the boundary in 2D is detected dynamically according to the algorithm developed by Dilts [G.A. Dilts, Moving least-squares particle hydrodynamics II: conservation and boundaries, International Journal for Numerical Methods in Engineering 48 (2000) 1503-1524]. The boundary curve in 2D is reconstructed locally with Lagrangian interpolation polynomial. In 3D surface tension model, the SPH particle on the boundary in 3D is detected dynamically according to the algorithm developed by Haque and Dilts [A. Haque, G.A. Dilts, Three-dimensional boundary detection for particle methods, Journal of Computational Physics 226 (2007) 1710-1730]. The boundary surface in 3D is reconstructed locally with moving least squares (MLS) method. By transforming the coordinate system, it is guaranteed that the interface function is one-valued in the local coordinate system. The normal vector and curvature of the boundary surface are calculated according to the reconstructed boundary surface and then surface tension force can be calculated. Surface tension force acts only on the boundary particle. Density correction is applied to the boundary particle in order to remove the boundary inconsistency. The surface tension models in 2D and 3D have been applied to benchmark tests for surface tension. The ability of the current method applying to the simulation of surface tension in 2D and 3D is proved.

  10. Test-particle Orbit Simulations in Fields from a Realistic 3D MHD Simulation

    NASA Astrophysics Data System (ADS)

    Decker, R. B.; Opher, M.; Hill, M. E.

    2007-05-01

    Models designed to explore the global structure of the heliosphere have become increasing sophisticated. Incentives to increase and to further explore the predictive capabilities of such models include the entry of the Voyager spacecraft into the foreshock region of the termination shock (TS), Voyager 1 in mid-2002 and Voyager 2 in late 2004, and the crossing of the TS and passage into the heliosheath (HSH) of Voyager 1 in 2004 day 351. Using the electric and magnetic fields generated by a MHD model of a 3D, asymmetric heliosphere [Opher et al., Ap. J. L., 640, 2006], we have developed full-particle and adiabatic-orbit codes to simulate the motion of test particles in the solar wind, TS, and HSH environments. The full-particle orbits are necessary to investigate energetic ion (e.g., anomalous and galactic cosmic ray) motion at the TS and within the heliospheric current sheet that is included in the MHD model. Adiabatic orbits are used to study particle motion in the much larger volume of the HSH where the non-homogeneous model fields produce complex guiding center motions, including mirroring in local field compressions. We will present results from these orbit computations, which are intended to provide an initial, albeit simplified, look at the propagation of high-energy charged particles, in the scatter-free limit, in the best model of the TS/HSH field configurations currently available. We will also display drift paths of high-energy ions in the HSH fields using the guiding center drift equations that are applicable in the limit of diffusive propagation.

  11. GPU accelerated simulations of 3D deterministic particle transport using discrete ordinates method

    NASA Astrophysics Data System (ADS)

    Gong, Chunye; Liu, Jie; Chi, Lihua; Huang, Haowei; Fang, Jingyue; Gong, Zhenghu

    2011-07-01

    Graphics Processing Unit (GPU), originally developed for real-time, high-definition 3D graphics in computer games, now provides great faculty in solving scientific applications. The basis of particle transport simulation is the time-dependent, multi-group, inhomogeneous Boltzmann transport equation. The numerical solution to the Boltzmann equation involves the discrete ordinates ( Sn) method and the procedure of source iteration. In this paper, we present a GPU accelerated simulation of one energy group time-independent deterministic discrete ordinates particle transport in 3D Cartesian geometry (Sweep3D). The performance of the GPU simulations are reported with the simulations of vacuum boundary condition. The discussion of the relative advantages and disadvantages of the GPU implementation, the simulation on multi GPUs, the programming effort and code portability are also reported. The results show that the overall performance speedup of one NVIDIA Tesla M2050 GPU ranges from 2.56 compared with one Intel Xeon X5670 chip to 8.14 compared with one Intel Core Q6600 chip for no flux fixup. The simulation with flux fixup on one M2050 is 1.23 times faster than on one X5670.

  12. GPU accelerated simulations of 3D deterministic particle transport using discrete ordinates method

    SciTech Connect

    Gong Chunye; Liu Jie; Chi Lihua; Huang Haowei; Fang Jingyue; Gong Zhenghu

    2011-07-01

    Graphics Processing Unit (GPU), originally developed for real-time, high-definition 3D graphics in computer games, now provides great faculty in solving scientific applications. The basis of particle transport simulation is the time-dependent, multi-group, inhomogeneous Boltzmann transport equation. The numerical solution to the Boltzmann equation involves the discrete ordinates (S{sub n}) method and the procedure of source iteration. In this paper, we present a GPU accelerated simulation of one energy group time-independent deterministic discrete ordinates particle transport in 3D Cartesian geometry (Sweep3D). The performance of the GPU simulations are reported with the simulations of vacuum boundary condition. The discussion of the relative advantages and disadvantages of the GPU implementation, the simulation on multi GPUs, the programming effort and code portability are also reported. The results show that the overall performance speedup of one NVIDIA Tesla M2050 GPU ranges from 2.56 compared with one Intel Xeon X5670 chip to 8.14 compared with one Intel Core Q6600 chip for no flux fixup. The simulation with flux fixup on one M2050 is 1.23 times faster than on one X5670.

  13. 3-D Particl-in-Cell Simulations of Transport Driven Currents

    NASA Astrophysics Data System (ADS)

    Tsung, F. S.; Dawson, J. M.

    1997-11-01

    In the advanced tokamak regime, transport phenomena can account for a signficant fraction of the toroidal current, possibly over that driven directly by the ohmic heating electric fields. Although bootstrap theory accounts for contributions of the collisional modification of banana orbits on the toroidal currents, the corresponding transport theory does not accurately predict the transport of particles and heat in present-day tokamak experiments. Furthermore, in our previous simulations in 21/2-D, currents were spontaneously generated in both the cylindrical and the toroidal geometries, contrary to neoclassical predictions. In these calculations, it was believed that the driving mechanism is the preferential loss of particles whose initial velocity is opposite to that of the plasma current. Because the preferential loss mechanism assumes the conservation of toroidal angular momentum, we have extended these simulations to three dimensions to study the effects of toroidal assymetries. A parallel, 3-D electromagnetic PIC code running on the IBM SP, with a localized field-solver has been developed to investigate the effects of perturbations parallel to the field lines, and direct comparisons has been made between the 21/2-D and 3-D simulations, and we have found good agreements between the 2 1/2-D calculations and the 3-D results. We will present these results at the meeting.

  14. A 3d particle simulation code for heavy ion fusion accelerator studies

    SciTech Connect

    Friedman, A.; Bangerter, R.O.; Callahan, D.A.; Grote, D.P.; Langdon, A.B. ); Haber, I. )

    1990-06-08

    We describe WARP, a new particle-in-cell code being developed and optimized for ion beam studies in true geometry. We seek to model transport around bends, axial compression with strong focusing, multiple beamlet interaction, and other inherently 3d processes that affect emittance growth. Constraints imposed by memory and running time are severe. Thus, we employ only two 3d field arrays ({rho} and {phi}), and difference {phi} directly on each particle to get E, rather than interpolating E from three meshes; use of a single 3d array is feasible. A new method for PIC simulation of bent beams follows the beam particles in a family of rotated laboratory frames, thus straightening'' the bends. We are also incorporating an envelope calculation, an (r, z) model, and 1d (axial) model within WARP. The BASIS development and run-time system is used, providing a powerful interactive environment in which the user has access to all variables in the code database. 10 refs., 3 figs.

  15. Earth's Magnetosphere 3D Simulation by Coupling Particle-In-Cell and Magnetohydrodynamics Models: Parametric Study

    NASA Astrophysics Data System (ADS)

    Baraka, S. M.; Ben-Jaffel, L. B.

    2014-12-01

    We use particle-in-cell PIC 3D Electromagnetic, relativistic global code to address large-scale problems in magnetosphere electrodynamics. Terrestrial bow shock is simulated as an example. 3D Magnetohydrodynamics model ,MHD GUMICS in CCMC project, have been used in parallel with PIC under same scaled Solar wind (SW) and IMF conditions. We report new results from the coupling between the two models. Further investigations are required for confirmations of these results. In both codes the Earth's bow shock position is found at ~14.8 RE along the Sun-Earth line, and ~29 RE on the dusk side which is consistent with past in situ observation. Both simulations reproduce the theoretical jump conditions at the shock. However, PIC code density and temperature distributions are inflated and slightly shifted sunward when compared to MHD results. Reflected ions upstream of the bow shock may cause this sunward shift for density and temperature. Distribution of reflected ions and electrons are shown in the foreshock region, within the transition of the shock and in the downstream. The current version of PIC code can be run under modest computing facilities and resources. Additionally, existing MHD simulations should be useful to calibrate scaled properties of plasma resulting from PIC simulations for comparison with observations. Similarities and drawbacks of the results obtained by the two models are listed. The ultimate goal of using these different models in a complimentary manner rather than competitive is to better understand the macrostructure of the magnetosphere

  16. 3D Printing Meets Computational Astrophysics: Deciphering the Structure of Eta Carinae’s Colliding Winds Using 3D Prints of Smoothed Particle Hydrodynamics Simulations

    NASA Astrophysics Data System (ADS)

    Madura, Thomas; Gull, Theodore R.; Clementel, Nicola; Paardekooper, Jan-Pieter; Kruip, Chael; Corcoran, Michael F.; Hamaguchi, Kenji; Teodoro, Mairan

    2015-01-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (>120 MSun), highly eccentric (e ~ 0.9) binary Eta Carinae. Using a consumer-grade 3D printer (Makerbot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics simulations of Eta Carinae's inner (r ~110 AU) wind-wind collision interface at multiple orbital phases. These 3D prints reveal important, previously unknown 'finger-like' structures at orbital phases shortly after periastron (φ ~1.045) that protrude radially outward from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. Rayleigh-Taylor) that arise at the interface between the radiatively-cooled layer of dense post-shock primary-star wind and the hot, adiabatic post-shock companion-star wind. The success of our work and easy identification of previously unknown physical features highlight the important role 3D printing can play in the visualization and understanding of complex 3D time-dependent numerical simulations of astrophysical phenomena.

  17. Particle entry through "Sash" groove simulated by Global 3D Electromagnetic Particle code with duskward IMF By

    NASA Astrophysics Data System (ADS)

    Yan, X.; Cai, D.; Nishikawa, K.; Lembege, B.

    2004-12-01

    We made our efforts to parallelize the global 3D HPF Electromagnetic particle model (EMPM) for several years and have also reported our meaningful simulation results that revealed the essential physics involved in interaction of the solar wind with the Earth's magnetosphere using this EMPM (Nishikawa et al., 1995; Nishikawa, 1997, 1998a, b, 2001, 2002) in our PC cluster and supercomputer(D.S. Cai et al., 2001, 2003). Sash patterns and related phenomena have been observed and reported in some satellite observations (Fujumoto et al. 1997; Maynard, 2001), and have motivated 3D MHD simulations (White and al., 1998). We also investigated it with our global 3D parallelized HPF EMPM with dawnward IMF By (K.-I. Nishikawa, 1998) and recently new simulation with dusk-ward IMF By was accomplished in the new VPP5000 supercomputer. In the new simulations performed on the new VPP5000 supercomputer of Tsukuba University, we used larger domain size, 305×205×205, smaller grid size (Δ ), 0.5R E(the radium of the Earth), more total particle number, 220,000,000 (about 8 pairs per cell). At first, we run this code until we get the so-called quasi-stationary status; After the quasi-stationary status was established, we applied a northward IMF (B z=0.2), and then wait until the IMF arrives around the magnetopuase. After the arrival of IMF, we begin to change the IMF from northward to duskward (IMF B y=-0.2). The results revealed that the groove structure at the day-side magnetopause, that causes particle entry into inner magnetosphere and the cross structure or S-structure at near magneto-tail are formed. Moreover, in contrast with MHD simulations, kinetic characteristic of this event is also analyzed self-consistently with this simulation. The new simulation provides new and more detailed insights for the observed sash event.

  18. 3D Particle-In-Cell (PIC) simulations of plasma sheath formation above lunar craters

    NASA Astrophysics Data System (ADS)

    Likhanskii, A.; Poppe, A. R.; Piquette, M.; Amyx, K.; Messmer, P.; Horanyi, M.

    2010-12-01

    Comprehensive investigation of plasma sheath formation and consequent dust levitation on lunar surface is important for interpretation of results of future lunar missions (such as LADEE and ARTEMIS). Until recently, most of such studies were done in experimental laboratories at reduced scales. Due to the complexity and nonlinearity of the problem, only simplified theories, describing this effect, were developed. However, recent progress in high-performance kinetic plasma simulations allowed tackling the problem of plasma sheath formation numerically. In this poster we will present the simulation results of plasma sheath formation above the lunar craters in presence of solar wind and photoelectron emission. These results were obtained using 3D Particle-In-Cell (PIC) code VORPAL. In the simulations we considered plasma sheath formation for normal, 45 and 90 degree incidence solar wind. Sample distribution of electric field in plasma sheath is shown in Figure 1. In the second part of the poster, we will present results of simulations of the LASP (Laboratory for Atmospheric and Space Physics at University of Colorado) experiments on study of plasma sheath formation above hemispherical isolated dimple. Figure 1. Electric field distribution in the plasma sheath above the lunar crater

  19. 3D and r,z particle simulations of heavy ion fusion beams

    NASA Astrophysics Data System (ADS)

    Friedman, A.; Grote, D. P.; Callahan, D. A.; Langdon, A. B.; Haber, I.

    1992-08-01

    The space-charge-dominated beams in a heavy ion beam driven inertial fusion (HIF) accelerator must be focused onto small (few mm) spots at the fusion target, and so preservation of a small emittance is crucial. The nonlinear beam self-fields can lead to emittance growth; thus, a self-consistent field description is necessary. We have developed a multi-dimensional time-dependent discrete particle simulation code, WARP, and are using it to study the behavior of HIF beams. The code's 3d package combines features of an accelerator code and a particle-in-cell (PIC) plasma simulation. Novel techniques allow it to follow beams through many accelerator elements over long distances and around bends. We have used the code to understand the emittance growth observed in the MBE4 experiment at Lawrence Berkeley Laboratory (LBL) under conditions of aggressive drift-compression. We are currently applying it to LBL's planned ILSE experiments, and (most recently) to an ESQ injector option being evaluated for ILSE. The code's r, z package is being used to study the axial confinement afforded by the shaped ends of the accelerating pulses, and to study longitudinal instability induced by induction module impedance.

  20. 3D Surgical Simulation

    PubMed Central

    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

  1. 3D Unsteady Multiphase Simulation of Uranium Tetrafluoride Particle Fluorination in Fluidized Bed Pilot

    NASA Astrophysics Data System (ADS)

    Konan, N. A.; Neau, H.; Simonin, O.; Dupoizat, M.; Le Geaziou, T.

    This paper investigates Eulerian simulation approach of uranium hexafluoride production in fluidized bed pilot. Mass transfer is modeled by using the shrinking particle model. The model successfully predicts expected amount of uranium hexafluoride. As heat transfers with wall are neglected, temperature increases within the reactor and there is no gradient in wall-normal direction of reactor. External diffusion model of reactive gas around particle is developed. Effect of fluorine diffusion within nitrogen is found to be negligible under the simulation conditions. Moreover, inter-particle radiative heat transfer between particles of dense phase in the bed is investigated in the frame of Rosseland approximation.

  2. 3D hybrid simulations with gyrokinetic particle ions and fluid electrons

    SciTech Connect

    Belova, E.V.; Park, W.; Fu, G.Y.; Strauss, H.R.; Sugiyama, L.E.

    1998-12-31

    The previous hybrid MHD/particle model (MH3D-K code) represented energetic ions as gyrokinetic (or drift-kinetic) particles coupled to MHD equations using the pressure or current coupling scheme. A small energetic to bulk ion density ratio was assumed, n{sub h}/n{sub b} {much_lt} 1, allowing the neglect of the energetic ion perpendicular inertia in the momentum equation and the use of MHD Ohm`s law E = {minus}v{sub b} {times} B. A generalization of this model in which all ions are treated as gyrokinetic/drift-kinetic particles and fluid description is used for the electron dynamics is considered in this paper.

  3. Simulation of the 3D viscoelastic free surface flow by a parallel corrected particle scheme

    NASA Astrophysics Data System (ADS)

    Jin-Lian, Ren; Tao, Jiang

    2016-02-01

    In this work, the behavior of the three-dimensional (3D) jet coiling based on the viscoelastic Oldroyd-B model is investigated by a corrected particle scheme, which is named the smoothed particle hydrodynamics with corrected symmetric kernel gradient and shifting particle technique (SPH_CS_SP) method. The accuracy and stability of SPH_CS_SP method is first tested by solving Poiseuille flow and Taylor-Green flow. Then the capacity for the SPH_CS_SP method to solve the viscoelastic fluid is verified by the polymer flow through a periodic array of cylinders. Moreover, the convergence of the SPH_CS_SP method is also investigated. Finally, the proposed method is further applied to the 3D viscoelastic jet coiling problem, and the influences of macroscopic parameters on the jet coiling are discussed. The numerical results show that the SPH_CS_SP method has higher accuracy and better stability than the traditional SPH method and other corrected SPH method, and can improve the tensile instability. Project supported by the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK20130436 and BK20150436) and the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (Grant No. 15KJB110025).

  4. Enabling Lorentz boosted frame particle-in-cell simulations of laser wakefield acceleration in quasi-3D geometry

    NASA Astrophysics Data System (ADS)

    Yu, Peicheng; Xu, Xinlu; Davidson, Asher; Tableman, Adam; Dalichaouch, Thamine; Li, Fei; Meyers, Michael D.; An, Weiming; Tsung, Frank S.; Decyk, Viktor K.; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo A.; Lu, Wei; Silva, Luis O.; Mori, Warren B.

    2016-07-01

    When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at βb c towards the laser, which can lead to a computational speedup of ∼ γb2 = (1 - βb2)-1. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited number of azimuthal harmonics, speedups are achieved by modeling three dimensional (3D) problems with the computational loads on the order of two dimensional r - z simulations. Here, we describe a method to combine the speedups from the Lorentz boosted frame and quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT solver in the quasi-3D geometry that significantly mitigates the Numerical Cerenkov Instability (NCI) which inevitably arises in a Lorentz boosted frame due to the unphysical coupling of Langmuir modes and EM modes of the relativistically drifting plasma in these simulations. In addition, based on the space-time distribution of the LWFA data in the lab and boosted frame, we propose to use a moving window to follow the drifting plasma, instead of following the laser driver as is done in the LWFA lab frame simulations, in order to further reduce the computational loads. We describe the details of how the NCI is mitigated for the quasi-3D geometry, the setups for simulations which combine the Lorentz boosted frame, quasi-3D geometry, and the use of a moving window, and compare the results from these simulations against their corresponding lab frame cases. Good agreement is obtained among these sample simulations, particularly when there is no self-trapping, which demonstrates it is possible to combine the Lorentz boosted frame and the quasi-3D algorithms when modeling LWFA. We also discuss the preliminary speedups achieved in these sample simulations.

  5. Numerical simulation of inhaled aerosol particle deposition within 3D realistic human upper respiratory tract

    NASA Astrophysics Data System (ADS)

    Lin, J.; Fan, J. R.; Zheng, Y. Q.; Hu, G. L.; Pan, D.

    2010-03-01

    Computational fluid dynamics (CFD) simulations of airflow and particle deposition in the upper respiratory tract (URT) were conducted in this paper. Based on the CT (Computerized Tomography) scanned images of a 19-years-old healthy boy, a realistic geometric model of URT from oral cavity to the upper six-generation bronchial is rebuilt. To investigate airflow and particle deposition in the obtained realistic human upper respiratory tract, RNG k-ɛ turbulence model was used to describe the primary flow and particle deposition under three breathing intensity such as 15 L/min, 30 L/min and 60 L/min. The particle is tracked and analyzed in the Lagrangian frame. The velocity fields of airflow under different airflow rates were computed and discussed. In order to study the characteristics of particles movement and the effect of particles diameter on the deposition pattern, eleven kinds of sphere particles with different diameters are selected as research object. The diameters of selected particles as follows: 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 6.5 μm and 8 μm. The variation of inhalable particles deposition in realistic human upper respiratory tract with respiratory intensity and particle size was researched and compared. Furthermore, the more real inhalable particles with Rosin-Rammler mass distribution are used to study the effect of particles size. The deposition rate of particles with the different diameter scope in the different part of upper respiratory tract was summarized. The geometrical model based images technology promises to provide more real results of airflow field and particle deposition in the URT.

  6. Some Progress in Large-Eddy Simulation using the 3-D Vortex Particle Method

    NASA Technical Reports Server (NTRS)

    Winckelmans, G. S.

    1995-01-01

    This two-month visit at CTR was devoted to investigating possibilities in LES modeling in the context of the 3-D vortex particle method (=vortex element method, VEM) for unbounded flows. A dedicated code was developed for that purpose. Although O(N(sup 2)) and thus slow, it offers the advantage that it can easily be modified to try out many ideas on problems involving up to N approx. 10(exp 4) particles. Energy spectrums (which require O(N(sup 2)) operations per wavenumber) are also computed. Progress was realized in the following areas: particle redistribution schemes, relaxation schemes to maintain the solenoidal condition on the particle vorticity field, simple LES models and their VEM extension, possible new avenues in LES. Model problems that involve strong interaction between vortex tubes were computed, together with diagnostics: total vorticity, linear and angular impulse, energy and energy spectrum, enstrophy. More work is needed, however, especially regarding relaxation schemes and further validation and development of LES models for VEM. Finally, what works well will eventually have to be incorporated into the fast parallel tree code.

  7. MHD-Epic: Embedded Particle-in-Cell Simulations of Reconnection in Global 3D Extended MHD Simulations

    NASA Astrophysics Data System (ADS)

    Daldorff, L. K. S.; Toth, G.; Borovikov, D.; Gombosi, T. I.; Lapenta, G.

    2014-12-01

    With the new modeling capability in the Space Weather Modeling Framework (SWMF) of embedding an implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US magnetohydrodynamics model (Daldorff et al. 2014, JCP, 268, 236) we are ready to locally handle the full physics of the reconnection and its implications on the full system where globally, away from the reconnection region, a magnetohydrodynamic description is satisfactory. As magnetic reconnection is one of the main drivers in magnetospheric and heliospheric plasma dynamics, the self-consistent description of the electron dynamics in the coupled MHD-EPIC model is well suited for investigating the nature of these systems. We will compare the new embedded MHD-EPIC model with pure MHD and Hall MHD simulations of the Earth's magnetosphere.

  8. Soot particle size modelling in 3D simulations of diesel engine combustion

    NASA Astrophysics Data System (ADS)

    Fraioli, V.; Beatrice, C.; Lazzaro, M.

    2011-12-01

    The present work is focused on multi-dimensional simulations of combustion in diesel engines. The primary objective was to test, in a diesel engine framework, a soot particle size model to represent the carbon particle formation and calculate the corresponding size distribution function. Simulations are performed by means of a parallel version of the KIVA3V numerical code, modified to adopt detailed kinetics reaction mechanisms. A skeletal reaction scheme for n-heptane autoignition has been extended, to include PAH kinetics and carbonaceous particle formation and consumption rates: the full reaction set is made up of 82 gas species and 50 species accounting for the particles, thus the complete reaction scheme comprises 132 species and 2206 reaction steps. Four different engine operative conditions, varying engine speed and load, are taken into account and experimentally tested on a single cylinder diesel engine fuelling pure n-heptane. Computed particle size distribution functions are compared with corresponding measurements at the exhaust, performed by a differential mobility spectrometer. A satisfying agreement between computed and measured combustion profiles is obtained in all the conditions. A reasonable aerosol evolution can be obtained, yet in all the cases the model exhibits the tendency to overestimate the number of particles within the range 5-160 nm. Moreover calculations predict a nucleation mode not detected by the available instrument. According to the simulations, the total number and size of the nascent particles would not depend on the operative conditions, while the features of the larger aggregates distinctly vary with the engine functioning.

  9. 3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2006-01-01

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

  10. Fully 3D Particle-in-Cell Simulation of Double Post-Hole Convolute on PTS Facility

    NASA Astrophysics Data System (ADS)

    Zhao, Hailong; Dong, Ye; Zhou, Haijing; Zou, Wenkang; Institute of Fluid Physics Collaboration; Institute of Applied Physics; Computational Mathematics Collaboration

    2015-11-01

    In order to get better understand of energy transforming and converging process during High Energy Density Physics (HEDP) experiments, fully 3D particle-in-cell (PIC) simulation code NEPTUNE3D was used to provide numerical approach towards parameters which could hardly be acquired through diagnostics. Cubic region (34cm × 34cm × 18cm) including the double post-hole convolute (DPHC) on the primary test stand (PTS) facility was chosen to perform a series of fully 3D PIC simulations, calculating ability of codes were tested and preliminary simulation results about DPHC on PTS facility were discussed. Taking advantages of 3D simulation codes and large-scale parallel computation, massive data (~ 250GB) could be acquired in less than 5 hours and clear process of current transforming and electron emission in DPHC were demonstrated with the help of visualization tools. Cold-chamber tests were performed during which only cathode electron emission was considered without temperature rise or ion emission, current loss efficiency was estimated to be 0.46% ~ 0.48% by comparisons between output magnetic field profiles with or without electron emission. Project supported by the National Natural Science Foundation of China (Grant No. 11205145, 11305015, 11475155).

  11. Particle Acceleration in 3D Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Dahlin, J.; Drake, J. F.; Swisdak, M.

    2015-12-01

    Magnetic reconnection is an important driver of energetic particles in phenomena such as magnetospheric storms and solar flares. Using kinetic particle-in-cell (PIC) simulations, we show that the stochastic magnetic field structure which develops during 3D reconnection plays a vital role in particle acceleration and transport. In a 2D system, electrons are trapped in magnetic islands which limits their energy gain. In a 3D system, however, the stochastic magnetic field enables the energetic electrons to access volume-filling acceleration regions and therefore gain energy much more efficiently than in the 2D system. We also examine the relative roles of two important acceleration drivers: parallel electric fields and a Fermi mechanism associated with reflection of charged particles from contracting field lines. We find that parallel electric fields are most important for accelerating low energy particles, whereas Fermi reflection dominates energetic particle production. We also find that proton energization is reduced in the 3D system.

  12. 3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  13. 3D particle simulation of beams using the WARP code: Transport around bends

    SciTech Connect

    Friedman, A.; Grote, D.P.; Callahan, D.A.; Langdon, A.B. ); Haber, I. )

    1990-11-30

    WARP is a discrete-particle simulation program which was developed for studies of space charge dominated ion beams. It combines features of an accelerator code and a particle-in-cell plasma simulation. The code architecture, and techniques employed to enhance efficiency, are briefly described. Current applications are reviewed. In this paper we emphasize the physics of transport of three-dimensional beams around bends. We present a simple bent-beam PIC algorithm. Using this model, we have followed a long, thin beam around a bend in a simple racetrack system (assuming straight-pipe self-fields). Results on beam dynamics are presented; no transverse emittance growth (at mid-pulse) is observed. 11 refs., 5 figs.

  14. 3D Boltzmann Simulation of the Io's Plasma Environment with Adaptive Mesh and Particle Refinement

    NASA Astrophysics Data System (ADS)

    Lipatov, A. S.; Combi, M. R.

    2002-12-01

    The global dynamics of the ionized and neutral components in the environment of Io plays an important role in the interaction of Jupiter's corotating magnetospheric plasma with Io [Combi et al., 2002; 1998; Kabin et al., 2001]. The stationary simulation of this problem was done in the MHD [Combi et al., 1998; Linker et al, 1998; Kabin et al., 2001] and the electrodynamic [Saur et al., 1999] approaches. In this report, we develop a method of kinetic ion-neutral simulation, which is based on a multiscale adaptive mesh, particle and algorithm refinement. This method employs the fluid description for electrons whereas for ions the drift-kinetic and particle approaches are used. This method takes into account charge-exchange and photoionization processes. The first results of such simulation of the dynamics of ions in the Io's environment are discussed in this report. ~ M R Combi et al., J. Geophys. Res., 103, 9071, 1998. M R Combi, T I Gombosi, K Kabin, Atmospheres in the Solar System: Comparative\\ Aeronomy. Geophys. Monograph Series, 130, 151, 2002. K Kabin et al., Planetary and Space Sci., 49, 337, 2001. J A Linker et al., J. Geophys. Res., 103(E9), 19867, 1998. J Saur et al., J. Geophys. Res., 104, 25105, 1999.

  15. Particle sedimentation in curved tubes: A 3D simulation and optimization for treatment of vestibular vertigo

    NASA Astrophysics Data System (ADS)

    White, Brian; Squires, Todd M.; Hain, Timothy C.; Stone, Howard A.

    2003-11-01

    Benign paroxysmal positional vertigo (BPPV) is a mechanical disorder of the vestibular system where micron-size crystals abnormally drift into the semicircular canals of the inner ear that sense angular motion of the head. Sedimentation of these crystals causes sensation of motion after true head motion has stopped: vertigo results. The usual clinical treatment is through a series of head maneuvers designed to move the particles into a less sensitive region of the canal system. We present a three-dimensional model to simulate treatment of BPPV by determining the complete hydrodynamic motion of the particles through the course of a therapeutic maneuver while using a realistic representation of the actual geometry. Analyses of clinical maneuvers show the parameter range for which they are effective, and indicate inefficiencies in current practice. In addition, an optimization process determines the most effective head maneuver, which significantly differs from those currently in practice.

  16. Grid dependent noise and entropy growth in anisotropic 3d particle-in-cell simulation of high intensity beams

    NASA Astrophysics Data System (ADS)

    Hofmann, I.; Boine-Frankenheim, O.

    2014-12-01

    The numerical noise inherent to particle-in-cell (PIC) simulation of 3d anisotropic high intensity bunched beams in periodic focusing is compared with the analytical model by Struckmeier [Part. Accel. 45, 229 (1994)]. The latter assumes that entropy growth can be related to Markov type stochastic processes due to temperature anisotropy and the artificial "collisions" caused by using macro-particles and calculating the space charge effect. The PIC simulations are carried out with the tracewin code widely used for high intensity beam simulation. The resulting noise can lead to growth of the six-dimensional rms emittance. The logarithm of the latter is shown to qualify as rms-based entropy. We confirm the dependence of this growth on the bunch temperature anisotropy as predicted by Struckmeier. However, we also find a grid and focusing dependent component of noise not predicted by Struckmeier. Although commonalities exist with well-established models for collision effects in PIC-simulation of extended plasmas, a distinctive feature is the presence of a periodic focusing potential, wherein the beam one-component plasma extends only over relatively few Debye lengths. Our findings are applied in particular to noise in high current linac beam simulation, where they help for optimization of the balance between the number of simulation particles and the grid resolution.

  17. 3D Electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  18. Particle entry through sash in the magnetopause with a dawndard IMF as simulated by a 3-D EM particle code

    NASA Astrophysics Data System (ADS)

    Cai, D.; Yan, X.; Lembege, B.; Nishikawa, K.

    2003-12-01

    We report a new progress in the long-term effort to represent the global interaction of the solar wind with the Earth's magnetosphere using a three-dimensional electromagnetic particle code with the improved resolutions using the HPF Tristan code. After a quasi-steady state is established with an unmagnetized solar wind we gradually switch on a northward interplanetary magnetic field (IMF), which causes a magnetic reconnection at the nightside cusps and the magnetosphere to be depolarized. In the case that the northward IMF is switched gradually to dawnward, there is no signature of reconnection in the near-Earth magnetotail as in the case with the southward turning. On the contrary analysis of magnetic fields in the magnetopause confirms a signature of magnetic reconnection at both the dawnside and duskside. And the plasma sheet in the near-Earth magnetotail clearly thins as in the case of southward turning. Arrival of dawnward IMF to the magnetopause creates a reconnection groove which cause particle entry into the deep region of the magnetosphere via field lines that go near the magnetopause. This deep connection is more fully recognized tailward of Earth. The flank weak-field fan joins onto the plasma sheet and the current sheet to form a geometrical feature called the cross-tail S that structurally integrates the magnetopause and the tail interior. This structure contributes to direct plasma entry between the magnetosheath to the inner magnetosphere and plasma sheet, in which the entry process heats the magnetosheath plasma to plasma sheet temperatures. These phenomena have been found by Cluster observations. Further investigation with Cluster observations will provide new insights for unsolved problems such as hot flow anomalies (HFAs), substorms, and storm-substorm relationship. 3-D movies with sash structure will be presented at the meeting.

  19. Guiding-centre and full-Lorentz orbit solving in 3D magnetic coordinates for fast particle simulations

    NASA Astrophysics Data System (ADS)

    Cooper, Wilfred A.; Pfefferle, David; Graves, Jonathan P.

    2014-10-01

    Designed to accurately solve the motion of energetic particles in the presence of 3D magnetic fields, the VENUS-LEVIS code leans on a non-canonical general coordinate Lagrangian formulation of the equations of motion. It switches between full-orbit particle following and guiding-centre tracing by verifying the perpendicular variation of magnetic vector field, not only including gradients and curvature terms but also the shearing of field-lines. The criteria is particularly relevant for the study of fast ion redistribution in the kinked core of hybrid plasmas, where the compression of flux-surfaces against the axisymmetric outer mantle creates strongly varying magnetic field-lines and large parallel currents. Slowing-down simulations of NBI fast ions show that co-passing particles helically align in the opposite side of the plasma deformation whereas counter-passing particles are barely affected by the kinked structure. Results are compared with experimental neutron camera traces and FIDA measurements during long-lived modes (LLM).

  20. 3-D Full-kinetic Simulations of the Solar Wind Interaction with Lunar Magnetic Anomalies: Particle Behaviour

    NASA Astrophysics Data System (ADS)

    Deca, J.; Divin, A. V.; Wang, X.; Lembege, B.; Markidis, S.; Lapenta, G.; Horanyi, M.

    2015-12-01

    We present three-dimensional full-kinetic electromagnetic simulations of the solar wind interaction with lunar crustal magnetic anomalies (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier MHD and hybrid simulations, the full-kinetic nature of iPic3D allows to self-consistently investigate space charge effects, and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe the general mechanism of the interaction of both a horizontal and vertical dipole model embedded just below the lunar surface focussing on the ion and electron kinetic behaviour of the system. It is shown that the configurations are largely dominated by electron motion, because the LMA scale size is small with respect to the gyro-radius of the solar wind ions. The formation of mini-magnetospheres is an electrostatic effect. Additionally, we discuss typical particle trajectories as well as complete particle distribution functions covering thermal and suprathermal energies, within the interaction region and on viable spacecraft altitudes. Our work opens new frontiers of research toward a deeper understanding of LMAs and is ideally suited to be compared with field or particle observations from spacecraft such as Kaguya (SELENE), Lunar Prospector or ARTEMIS. The ability to evaluate the implications for future lunar exploration as well as lunar science in general hinges on a better understanding of LMAs.This research has received funding from the European Commission's FP7 Program with the grant agreement EHEROES (project 284461, www.eheroes.eu). The simulations were conducted on the computational resources provided by the PRACE Tier-0 project 2013091928 (SuperMUC). This research was supported by the Swedish National Space Board

  1. 3-D Relativistic MHD Simulations

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Frank, J.; Koide, S.; Sakai, J.-I.; Christodoulou, D. M.; Sol, H.; Mutel, R. L.

    1998-12-01

    We present 3-D numerical simulations of moderately hot, supersonic jets propagating initially along or obliquely to the field lines of a denser magnetized background medium with Lorentz factors of W = 4.56 and evolving in a four-dimensional spacetime. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently in the simulations. This effect is analogous to pushing Japanese ``noren'' or vertical Venetian blinds out of the way while the slats are allowed to bend in 3-D space rather than as a 2-D slab structure.

  2. 3-D Relativistic MHD Simulations

    NASA Astrophysics Data System (ADS)

    Nishikaw, K.-I.; Frank, J.; Christodoulou, D. M.; Koide, S.; Sakai, J.-I.; Sol, H.; Mutel, R. L.

    1998-12-01

    We present 3-D numerical simulations of moderately hot, supersonic jets propagating initially along or obliquely to the field lines of a denser magnetized background medium with Lorentz factors of W=4.56 and evolving in a four-dimensional spacetime. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently in the simulations. This effect is analogous to pushing Japanese ``noren'' or vertical Venetian blinds out of the way while the slats are allowed to bend in 3-D space rather than as a 2-D slab structure. We also simulate jets with the more realistic initial conditions for injecting jets for helical mangetic field, perturbed density, velocity, and internal energy, which are supposed to be caused in the process of jet generation. Three possible explanations for the observed variability are (i) tidal disruption of a star falling into the black hole, (ii) instabilities in the relativistic accretion disk, and (iii) jet-related PRocesses. New results will be reported at the meeting.

  3. Prediction of the effect of an extreme solar event on the Martian environment using a 3-D, self consistent hybrid model supplemented by test particle simulations.

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, Susan; Kallio, Esa; Dyadechkin, Sergey; Jarvinen, Riku; Janhunen, Pekka

    2010-05-01

    Energetic particle data recorded by the SLED and LET instruments aboard the Phobos-2 spacecraft while in circular orbit about Mars showed the presence from 6 > 26 March, 1989, in association with an extreme solar event, of intense ambient particle radiation (> 30 MeV) punctuated by traveling interplanetary shocks. The response of the Martian environment to the March 1989 solar disturbances is modeled using a 3-D, self-consistent, hybrid model (HYB-Mars) supplemented by test particle simulations. In HYB-Mars ions are modeled as particles while electrons form a massless, charge neutralizing, fluid. The magnetic and electric fields present during the March 1989 activity are each derived from HYB- Mars while the high energy ion populations are analyzed using test particle simulations. Finally, the predictions of the model are validated by comparing the simulated properties of the disturbed Martian environment with the in situ observations.

  4. 3D Finite Element Analysis of Particle-Reinforced Aluminum

    NASA Technical Reports Server (NTRS)

    Shen, H.; Lissenden, C. J.

    2002-01-01

    Deformation in particle-reinforced aluminum has been simulated using three distinct types of finite element model: a three-dimensional repeating unit cell, a three-dimensional multi-particle model, and two-dimensional multi-particle models. The repeating unit cell model represents a fictitious periodic cubic array of particles. The 3D multi-particle (3D-MP) model represents randomly placed and oriented particles. The 2D generalized plane strain multi-particle models were obtained from planar sections through the 3D-MP model. These models were used to study the tensile macroscopic stress-strain response and the associated stress and strain distributions in an elastoplastic matrix. The results indicate that the 2D model having a particle area fraction equal to the particle representative volume fraction of the 3D models predicted the same macroscopic stress-strain response as the 3D models. However, there are fluctuations in the particle area fraction in a representative volume element. As expected, predictions from 2D models having different particle area fractions do not agree with predictions from 3D models. More importantly, it was found that the microscopic stress and strain distributions from the 2D models do not agree with those from the 3D-MP model. Specifically, the plastic strain distribution predicted by the 2D model is banded along lines inclined at 45 deg from the loading axis while the 3D model prediction is not. Additionally, the triaxial stress and maximum principal stress distributions predicted by 2D and 3D models do not agree. Thus, it appears necessary to use a multi-particle 3D model to accurately predict material responses that depend on local effects, such as strain-to-failure, fracture toughness, and fatigue life.

  5. 3D Magnetron simulation with CST STUDIO SUITE

    SciTech Connect

    Balk, Monika C.

    2011-07-01

    The modeling of magnetrons compared to other tubes is more difficult since it requires 3D modeling rather than a 2D investigation. This is not only due to the geometry which can include complicated details to be modeled in 3D but also due to the interaction process itself. The electric field, magnetic field and particle movement span a 3D space. In this paper 3D simulations of a strapped magnetron with CSTSTUDIO SUITE{sup TM} are presented. (author)

  6. Self-consistent Nonlinear Analysis and 3D Particle-In-Cell Simulation of a W-band Gyro-TWT

    NASA Astrophysics Data System (ADS)

    Tang, Yong; Luo, Yong; Xu, Yong; Yan, Ran

    2014-10-01

    The self-consistent nonlinear analysis and CST 3D particle-in-cell (PIC) simulation of a W-band gyrotron traveling wave tube (gyro-TWT) are presented in this paper. Both the simulation results of the two codes are excellent agreement with each other. The gyro-TWT loaded with periodic lossy dielectric in the circuit for suppressing potential spurious oscillations. It is driven by a 70kV, 10A gyrating electron beam with velocity ratio of 1.0. PIC simulation results are: the maximum peak output power of 198kW, statured gain of 62.3dB and efficiency of 28.3% at 92.5GHz. Only the operating mode TE 01 is observed in the CST 3D simulation and the potential competing backward wave oscillations are effectively suppressed. The CST simulation also predicts that the device works stably under the condition of the beam current lower than 14A and B 0 /B g lower than 1.05. The simulated bandwidth with peak power greater than 100kW is 6.8GHz without axial velocity spread, and 4.1GHz with 6% axial velocity spread.

  7. Non-isothermal 3D SDPD Simulations

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Potami, Raffaele; Gatsonis, Nikolaos

    2012-11-01

    The study of fluids at micro and nanoscale requires new modeling and computational approaches. Smooth Particle Dissipative Dynamics (SDPD) is a mesh-free method that provides a bridge between the continuum equations of hydrodynamics embedded in the Smooth Particle Hydrodynamics approach and the molecular nature embedded in the DPD approach. SDPD is thermodynamically consistent, does not rely on arbitrary coefficients for its thermostat, involves realistic transport coefficients, and includes fluctuation terms. SDPD is implemented in our work for arbitrary 3D geometries with a methodology to model solid wall boundary conditions. We present simulations for isothermal flows for verification of our approach. The entropy equation is implemented with a velocity-entropy Verlet integration algorithm Flows with heat transfer are simulated for verification of the SDPD. We present also the self-diffusion coefficient derived from SDPD simulations for gases and liquids. Results show the scale dependence of self-diffusion coefficient on SDPD particle size. Computational Mathematics Program of the Air Force Office of Scientific Research under grant/contract number FA9550-06-1-0236.

  8. Self consistent particles dynamics in/out of the cusp region by using back tracking technics; a global 3D PIC simulation approach

    NASA Astrophysics Data System (ADS)

    Esmaeili, A.; Cai, D.; Lembege, B.; Nishikawa, K.

    2013-12-01

    Large scale three dimensionbal PIC (particle in cell) simulations are presently used in order to analyze the global solar wind-terrestrial magnetosphere intreraction within a full self-consistent approach, and where both electrons and ions are treated as an assembly of individual particles. This 3D kinetic approach allows us to analyze in particular the dynamics and the fine structures of the cusp region when including self consistently not only its whole neighborhood (in the terrestrial magnetosphere) but also the impact of the solar wind and the interplanetary field (IMF) features. Herein, we focuss our attention on the cusp region and in particular on the acceleration and precipitation of particles (both ions and electrons) within the cusp. In present simulations, the IMF is chosen northward, (i.e. where the X -reconnection region is just above the cusp, in the meridian plane). Back-trackings of self-consistent particles are analyzed in details in order to determine (i) which particles (just above the cusp) are precipitated deeply into the cusp, (ii) which populations are injected from the cusp into the nearby tail, (iii) where the particles suffer the largest energisation along their self-consistent trajectories, (iv) where these populations accumulate, and (v) where the most energetic particles are originally coming from. This approach allows to make a traking of particles within the scenario "solar wind-magnetosheath- cusp -nearbytail"; moreover it strongly differs from the standard test particles technics and allows to provide informations not accessible when using full MHD approach. Keywords: Tracing Particles, Particle In Cell (PIC) simulation, double cusp, test particles method, IMF, Solar wind, Magnetosphere

  9. 3D Simulation: Microgravity Environments and Applications

    NASA Technical Reports Server (NTRS)

    Hunter, Steve L.; Dischinger, Charles; Estes, Samantha; Parker, Nelson C. (Technical Monitor)

    2001-01-01

    Most, if not all, 3-D and Virtual Reality (VR) software programs are designed for one-G gravity applications. Space environments simulations require gravity effects of one one-thousandth to one one-million of that of the Earth's surface (10(exp -3) - 10(exp -6) G), thus one must be able to generate simulations that replicate those microgravity effects upon simulated astronauts. Unfortunately, the software programs utilized by the National Aeronautical and Space Administration does not have the ability to readily neutralize the one-G gravity effect. This pre-programmed situation causes the engineer or analysis difficulty during micro-gravity simulations. Therefore, microgravity simulations require special techniques or additional code in order to apply the power of 3D graphic simulation to space related applications. This paper discusses the problem and possible solutions to allow microgravity 3-D/VR simulations to be completed successfully without program code modifications.

  10. 3D View of Mars Particle

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This is a 3D representation of the pits seen in the first Atomic Force Microscope, or AFM, images sent back from NASA's Phoenix Mars Lander. Red represents the highest point and purple represents the lowest point.

    The particle in the upper left corner shown at the highest magnification ever seen from another world is a rounded particle about one micrometer, or one millionth of a meter, across. It is a particle of the dust that cloaks Mars. Such dust particles color the Martian sky pink, feed storms that regularly envelop the planet and produce Mars' distinctive red soil.

    The particle was part of a sample informally called 'Sorceress' delivered to the AFM on the 38th Martian day, or sol, of the mission (July 2, 2008). The AFM is part of Phoenix's microscopic station called MECA, or the Microscopy, Electrochemistry, and Conductivity Analyzer.

    The AFM was developed by a Swiss-led consortium, with Imperial College London producing the silicon substrate that holds sampled particles.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  11. A 3D immersed finite element method with non-homogeneous interface flux jump for applications in particle-in-cell simulations of plasma-lunar surface interactions

    NASA Astrophysics Data System (ADS)

    Han, Daoru; Wang, Pu; He, Xiaoming; Lin, Tao; Wang, Joseph

    2016-09-01

    Motivated by the need to handle complex boundary conditions efficiently and accurately in particle-in-cell (PIC) simulations, this paper presents a three-dimensional (3D) linear immersed finite element (IFE) method with non-homogeneous flux jump conditions for solving electrostatic field involving complex boundary conditions using structured meshes independent of the interface. This method treats an object boundary as part of the simulation domain and solves the electric field at the boundary as an interface problem. In order to resolve charging on a dielectric surface, a new 3D linear IFE basis function is designed for each interface element to capture the electric field jump on the interface. Numerical experiments are provided to demonstrate the optimal convergence rates in L2 and H1 norms of the IFE solution. This new IFE method is integrated into a PIC method for simulations involving charging of a complex dielectric surface in a plasma. A numerical study of plasma-surface interactions at the lunar terminator is presented to demonstrate the applicability of the new method.

  12. Fractal and fractional calculus to model hydrological processes with application to particle-based 2D and 3D landslide simulation

    NASA Astrophysics Data System (ADS)

    Martelloni, Gianluca; Bagnoli, Franco; Di Cintio, Pierfrancesco

    2015-04-01

    We integrate existing soil infiltration modeling with particle based methods in order to simulate two and three-dimensional setups of triggered landslides. Commonly, the infiltration models are based on continuum schemes (e.g. Eulerian approach) by means of which it is possible to define the field of the pore pressure within a soil. By contrast, the particle based methods follow a Lagrangian scheme that allows one to identify the particle trajectories and their dynamical properties. In this work, in order to simulate the triggering mechanism, we apply the classical, fractal and fractional Richards equations and the Mohr-Coulomb failure criterion, adapted to the molecular dynamics technique. In our scheme the (local) positive pore pressure is simply implemented as a perturbation of the rest state of each grain. Therefore, the pore pressure function can be interpreted as a time-space dependent scalar field acting on each particle. To initialize the system we generate, using a molecular dynamics based algorithm, a mechanically stable disk (2D) or sphere (3D) packing simulating the consolidated soil. In this way, we can built the micro and macro pore structure related to different infiltration time scales. The inter-particle interactions are modeled with a Lennard-Jones like potential. The particle positions are updated in time, after and during a rainfall, with standard molecular dynamics. We analyze the sensitivity of the model with respect to the variation of some parameters such as hydraulic conductivity, cohesion, slope and friction angle, soil depth and fractional order of the generalized infiltration model. In addition, we consider both regular and random particle configurations. The results of our simulations are found to be in agreement with real landslides. In particular, the mean velocity patterns of the simulated landslides appear extremely similar to the observed ones. Moreover, it is possible to apply the method of the inverse surface displacement

  13. M3D project for simulation studies of plasmas

    SciTech Connect

    Park, W.; Belova, E.V.; Fu, G.Y.; Strauss, H.R.; Sugiyama, L.E.

    1998-12-31

    The M3D (Multi-level 3D) project carries out simulation studies of plasmas of various regimes using multi-levels of physics, geometry, and mesh schemes in one code package. This paper and papers by Strauss, Sugiyama, and Belova in this workshop describe the project, and present examples of current applications. The currently available physics models of the M3D project are MHD, two-fluids, gyrokinetic hot particle/MHD hybrid, and gyrokinetic particle ion/two-fluid hybrid models. The code can be run with both structured and unstructured meshes.

  14. Development of the 3D Parallel Particle-In-Cell Code IMPACT to Simulate the Ion Beam Transport System of VENUS (Abstract)

    SciTech Connect

    Qiang, J.; Leitner, D.; Todd, D.S.; Ryne, R.D.

    2005-03-15

    The superconducting ECR ion source VENUS serves as the prototype injector ion source for the Rare Isotope Accelerator (RIA) driver linac. The RIA driver linac requires a great variety of high charge state ion beams with up to an order of magnitude higher intensity than currently achievable with conventional ECR ion sources. In order to design the beam line optics of the low energy beam line for the RIA front end for the wide parameter range required for the RIA driver accelerator, reliable simulations of the ion beam extraction from the ECR ion source through the ion mass analyzing system are essential. The RIA low energy beam transport line must be able to transport intense beams (up to 10 mA) of light and heavy ions at 30 keV.For this purpose, LBNL is developing the parallel 3D particle-in-cell code IMPACT to simulate the ion beam transport from the ECR extraction aperture through the analyzing section of the low energy transport system. IMPACT, a parallel, particle-in-cell code, is currently used to model the superconducting RF linac section of RIA and is being modified in order to simulate DC beams from the ECR ion source extraction. By using the high performance of parallel supercomputing we will be able to account consistently for the changing space charge in the extraction region and the analyzing section. A progress report and early results in the modeling of the VENUS source will be presented.

  15. Development of the 3D Parallel Particle-In-Cell Code IMPACT to Simulate the Ion Beam Transport System of VENUS (Abstract)

    NASA Astrophysics Data System (ADS)

    Qiang, J.; Leitner, D.; Todd, D. S.; Ryne, R. D.

    2005-03-01

    The superconducting ECR ion source VENUS serves as the prototype injector ion source for the Rare Isotope Accelerator (RIA) driver linac. The RIA driver linac requires a great variety of high charge state ion beams with up to an order of magnitude higher intensity than currently achievable with conventional ECR ion sources. In order to design the beam line optics of the low energy beam line for the RIA front end for the wide parameter range required for the RIA driver accelerator, reliable simulations of the ion beam extraction from the ECR ion source through the ion mass analyzing system are essential. The RIA low energy beam transport line must be able to transport intense beams (up to 10 mA) of light and heavy ions at 30 keV. For this purpose, LBNL is developing the parallel 3D particle-in-cell code IMPACT to simulate the ion beam transport from the ECR extraction aperture through the analyzing section of the low energy transport system. IMPACT, a parallel, particle-in-cell code, is currently used to model the superconducting RF linac section of RIA and is being modified in order to simulate DC beams from the ECR ion source extraction. By using the high performance of parallel supercomputing we will be able to account consistently for the changing space charge in the extraction region and the analyzing section. A progress report and early results in the modeling of the VENUS source will be presented.

  16. Comparison of quasi-3D and full-3D laser wakefield PIC simulations using azimuthal mode decomposition

    NASA Astrophysics Data System (ADS)

    Dalichaouch, Thamine; Yu, Peicheng; Davidson, Asher; Mori, Warren; Vieira, Jorge; Fonseca, Ricardo

    2015-11-01

    Laser wakefield acceleration (LWFA) has attracted a lot of interest as a possible compact particle accelerator. However, 3D simulations of plasma-based accelerators are computationally intensive, sometimes taking millions of core hours on today's computers. A quasi-3D particle-In-cell (PIC) approach has been developed to take advantage of azimuthal symmetry in LWFA (and PWFA) simulations by using a particle-in-cell description in r-z and a Fourier description in φ. Quasi-3D simulations of LWFA are computationally more efficient and faster than Full-3D simulations because only first few azimuthal harmonics are needed to capture the physics of the problem. We have developed a cylindrical mode decomposition diagnostic for 3D Cartesian geometry simulations to analyze the agreement between full-3D and quasi-3D PIC simulations of laser and beam-plasma interactions. The diagnostic interpolates field data from Full-3D PIC simulations onto an irregular cylindrical grid (r , φ , z). A Fourier decomposition is then performed on the interpolated 3D simulation data along the azimuthal direction. This diagnostic has the added advantage of separating out the wakefields from the laser field. Preliminary results for this diagnostic of LWFA and PWFA simulations with symmetric and nearly symmetric spot sizes as well as of laser-plasma interactions using lasers with orbital angular momentum (higher order Laguerre-Gaussian modes) will be presented.

  17. Loop heating by D.C. electric current and electromagnetic wave emissions simulated by 3-D EM particle zone

    NASA Technical Reports Server (NTRS)

    Sakai, J. I.; Zhao, J.; Nishikawa, K.-I.

    1994-01-01

    We have shown that a current-carrying plasma loop can be heated by magnetic pinch driven by the pressure imbalance between inside and outside the loop, using a 3-dimensional electromagnetic (EM) particle code. Both electrons and ions in the loop can be heated in the direction perpendicular to the ambient magnetic field, therefore the perpendicular temperature can be increased about 10 times compared with the parallel temperature. This temperature anisotropy produced by the magnetic pinch heating can induce a plasma instability, by which high-frequency electromagnetic waves can be excited. The plasma current which is enhanced by the magnetic pinch can also excite a kinetic kink instability, which can heat ions perpendicular to the magnetic field. The heating mechanism of ions as well as the electromagnetic emission could be important for an understanding of the coronal loop heating and the electromagnetic wave emissions from active coronal regions.

  18. Large-eddy simulations of 3D Taylor-Green vortex: comparison of Smoothed Particle Hydrodynamics, Lattice Boltzmann and Finite Volume methods

    NASA Astrophysics Data System (ADS)

    Kajzer, A.; Pozorski, J.; Szewc, K.

    2014-08-01

    In the paper we present Large-eddy simulation (LES) results of 3D Taylor- Green vortex obtained by the three different computational approaches: Smoothed Particle Hydrodynamics (SPH), Lattice Boltzmann Method (LBM) and Finite Volume Method (FVM). The Smagorinsky model was chosen as a subgrid-scale closure in LES for all considered methods and a selection of spatial resolutions have been investigated. The SPH and LBM computations have been carried out with the use of the in-house codes executed on GPU and compared, for validation purposes, with the FVM results obtained using the open-source CFD software OpenFOAM. A comparative study in terms of one-point statistics and turbulent energy spectra shows a good agreement of LES results for all methods. An analysis of the GPU code efficiency and implementation difficulties has been made. It is shown that both SPH and LBM may offer a significant advantage over mesh-based CFD methods.

  19. INCORPORATING DYNAMIC 3D SIMULATION INTO PRA

    SciTech Connect

    Steven R Prescott; Curtis Smith

    2011-07-01

    Through continued advancement in computational resources, development that was previously done by trial and error production is now performed through computer simulation. These virtual physical representations have the potential to provide accurate and valid modeling results and are being used in many different technical fields. Risk assessment now has the opportunity to use 3D simulation to improve analysis results and insights, especially for external event analysis. By using simulations, the modeler only has to determine the likelihood of an event without having to also predict the results of that event. The 3D simulation automatically determines not only the outcome of the event, but when those failures occur. How can we effectively incorporate 3D simulation into traditional PRA? Most PRA plant modeling is made up of components with different failure modes, probabilities, and rates. Typically, these components are grouped into various systems and then are modeled together (in different combinations) as a “system” with logic structures to form fault trees. Applicable fault trees are combined through scenarios, typically represented by event tree models. Though this method gives us failure results for a given model, it has limitations when it comes to time-based dependencies or dependencies that are coupled to physical processes which may themselves be space- or time-dependent. Since, failures from a 3D simulation are naturally time related, they should be used in that manner. In our simulation approach, traditional static models are converted into an equivalent state diagram representation with start states, probabilistic driven movements between states and terminal states. As the state model is run repeatedly, it converges to the same results as the PRA model in cases where time-related factors are not important. In cases where timing considerations are important (e.g., when events are dependent upon each other), then the simulation approach will typically

  20. HIGH-TEMPERATURE PROCESSING OF SOLIDS THROUGH SOLAR NEBULAR BOW SHOCKS: 3D RADIATION HYDRODYNAMICS SIMULATIONS WITH PARTICLES

    SciTech Connect

    Boley, A. C.; Morris, M. A.; Desch, S. J.

    2013-10-20

    A fundamental, unsolved problem in solar system formation is explaining the melting and crystallization of chondrules found in chondritic meteorites. Theoretical models of chondrule melting in nebular shocks have been shown to be consistent with many aspects of thermal histories inferred for chondrules from laboratory experiments; but, the mechanism driving these shocks is unknown. Planetesimals and planetary embryos on eccentric orbits can produce bow shocks as they move supersonically through the disk gas, and are one possible source of chondrule-melting shocks. We investigate chondrule formation in bow shocks around planetoids through three-dimensional radiation hydrodynamics simulations. A new radiation transport algorithm that combines elements of flux-limited diffusion and Monte Carlo methods is used to capture the complexity of radiative transport around bow shocks. An equation of state that includes the rotational, vibrational, and dissociation modes of H{sub 2} is also used. Solids are followed directly in the simulations and their thermal histories are recorded. Adiabatic expansion creates rapid cooling of the gas, and tail shocks behind the embryo can cause secondary heating events. Radiative transport is efficient, and bow shocks around planetoids can have luminosities ∼few× 10{sup –8} L{sub ☉}. While barred and radial chondrule textures could be produced in the radiative shocks explored here, porphyritic chondrules may only be possible in the adiabatic limit. We present a series of predicted cooling curves that merit investigation in laboratory experiments to determine whether the solids produced by bow shocks are represented in the meteoritic record by chondrules or other solids.

  1. 3D laser traking of a particle in 3DFM

    NASA Astrophysics Data System (ADS)

    Desai, Kalpit; Welch, Gregory; Bishop, Gary; Taylor, Russell; Superfine, Richard

    2003-11-01

    The principal goal of 3D tracking in our home-built 3D Magnetic Force Microscope is to monitor movement of the particle with respect to laser beam waist and keep the particle at the center of laser beam. The sensory element is a Quadrant Photo Diode (QPD) which captures scattering of light caused by particle motion with bandwidth up to 40 KHz. XYZ translation stage is the driver element which moves particle back in the center of the laser with accuracy of couple of nanometers and with bandwidth up to 300 Hz. Since our particles vary in size, composition and shape, instead of using a priori model we use standard system identification techniques to have optimal approximation to the relationship between particle motion and QPD response. We have developed position feedback control system software that is capable of 3-dimensional tracking of beads that are attached to cilia on living cells which are beating at up to 15Hz. We have also modeled the control system of instrument to simulate performance of 3D particle tracking for different experimental conditions. Given operational level of nanometers, noise poses a great challenge for the tracking system. We propose to use stochastic control theory approaches to increase robustness of tracking.

  2. 3D MHD Simulations of Tokamak Disruptions

    NASA Astrophysics Data System (ADS)

    Woodruff, Simon; Stuber, James

    2014-10-01

    Two disruption scenarios are modeled numerically by use of the CORSICA 2D equilibrium and NIMROD 3D MHD codes. The work follows the simulations of pressure-driven modes in DIII-D and VDEs in ITER. The aim of the work is to provide starting points for simulation of tokamak disruption mitigation techniques currently in the CDR phase for ITER. Pressure-driven instability growth rates previously observed in simulations of DIIID are verified; Halo and Hiro currents produced during vertical displacements are observed in simulations of ITER with implementation of resistive walls in NIMROD. We discuss plans to exercise new code capabilities and validation.

  3. Crashworthiness simulations with DYNA3D

    SciTech Connect

    Schauer, D.A.; Hoover, C.G.; Kay, G.J.; Lee, A.S.; De Groot, A.J.

    1996-04-01

    Current progress in parallel algorithm research and applications in vehicle crash simulation is described for the explicit, finite element algorithms in DYNA3D. Problem partitioning methods and parallel algorithms for contact at material interfaces are the two challenging algorithm research problems that are addressed. Two prototype parallel contact algorithms have been developed for treating the cases of local and arbitrary contact. Demonstration problems for local contact are crashworthiness simulations with 222 locally defined contact surfaces and a vehicle/barrier collision modeled with arbitrary contact. A simulation of crash tests conducted for a vehicle impacting a U-channel small sign post embedded in soil has been run on both the serial and parallel versions of DYNA3D. A significant reduction in computational time has been observed when running these problems on the parallel version. However, to achieve maximum efficiency, complex problems must be appropriately partitioned, especially when contact dominates the computation.

  4. DRACO development for 3D simulations

    NASA Astrophysics Data System (ADS)

    Fatenejad, Milad; Moses, Gregory

    2006-10-01

    The DRACO (r-z) lagrangian radiation-hydrodynamics laser fusion simulation code is being extended to model 3D hydrodynamics in (x-y-z) coordinates with hexahedral cells on a structured grid. The equation of motion is solved with a lagrangian update with optional rezoning. The fluid equations are solved using an explicit scheme based on (Schulz, 1964) while the SALE-3D algorithm (Amsden, 1981) is used as a template for computing cell volumes and other quantities. A second order rezoner has been added which uses linear interpolation of the underlying continuous functions to preserve accuracy (Van Leer, 1976). Artificial restoring force terms and smoothing algorithms are used to avoid grid distortion in high aspect ratio cells. These include alternate node couplers along with a rotational restoring force based on the Tensor Code (Maenchen, 1964). Electron and ion thermal conduction is modeled using an extension of Kershaw's method (Kershaw, 1981) to 3D geometry. Test problem simulations will be presented to demonstrate the applicability of this new version of DRACO to the study of fluid instabilities in three dimensions.

  5. Analytical augmentation of 3D simulation environments

    NASA Astrophysics Data System (ADS)

    Loughran, Julia J.; Stahl, Marchelle M.

    1998-05-01

    This paper describes an approach for augmenting three- dimensional (3D) virtual environments (VEs) with analytic information and multimedia annotations to enhance training and education applications. Analytic or symbolic information in VEs is presented as bar charts, text, graphical overlays, or with the use of color. Analytic results can be computed and displayed in the VE at run-time or, more likely, while replaying a simulation. These annotations would typically include computations of pre-defined Measures of Performance (MOPs) or Measures of Effectiveness (MOEs) associated with the training or educational goals of the simulation. Multimedia annotations are inserted into the VE by the user and may include: a drawing or whiteboarding capability, enabling participants to insert written text and/or graphics into the two-dimensional (2D) or 3D world; audio comments, and/or video recordings. These annotations can clarify a point, capture teacher feedback, or elaborate on the student's perspective or understanding of the experience. The annotations are captured in the VE either synchronously or asynchronously from the users (students and instructors), during simulation execution or afterward during a replay. When replaying or reviewing the simulation, the embedded annotations can be reviewed by a single user or by multiple users through the use of collaboration technologies. By augmenting 3D virtual environments with analytic and multimedia annotations, the education and training experience may be enhanced. The annotations can offer more effective feedback, enhance understanding, and increase participation. They may also support distance learning by promoting student/teacher interaction without co-location.

  6. 3-D simulations of multiple beam klystrons

    SciTech Connect

    Smithe, David N.; Bettenhausen, Mike; Ludeking, Larry; Caryotakis, G.; Sprehn, Daryl; Scheitrum, Glenn

    1999-05-07

    The MAGIC3D simulation code is being used to assess the multi-dimensional physics issues relating to the design and operation of multiple beam klystrons. Investigations, to date, include a detailed study of the mode structure of the cavities in the 19-beam hexagonally packed geometry and a study of the velocity spread caused by the cavity mode's field profile. Some attempts to minimize this effect are investigated. Additional simulations have provided quantification of the beam loading Q in a dual input cavity, and optimization of a dual output cavity. An important goal of the simulations is an accurate picture of beam transport along the length of the MBK. We have quantified the magnitude and spatial variation of the beam-line space charge interactions within a cavity gap. Present simulations have demonstrated the transport of the beam through three cavities (the present limits of our simulation size) without difficulty; additional length simulations are expected. We have also examined unbalanced beam-line scenarios, e.g., one beam-line suppressed, and find little disturbance to the transport in individual cavity tests, with results for multiple cavity transport expected.

  7. 3D Hydrodynamic Simulations of Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Hughes, P. A.; Miller, M. A.; Duncan, G. C.; Swift, C. M.

    1998-12-01

    We present the results of validation runs and the first extragalactic jet simulations performed with a 3D relativistic numerical hydrodynamic code employing a solver of the RHLLE type and using adaptive mesh refinement (AMR; Duncan & Hughes, 1994, Ap. J., 436, L119). Test problems include the shock tube, blast wave and spherical shock reflection (implosion). Trials with the code show that as a consequence of AMR it is viable to perform exploratory runs on workstation class machines (with no more than 128Mb of memory) prior to production runs. In the former case we achieve a resolution not much less than that normally regarded as the minimum needed to capture the essential physics of a problem, which means that such runs can provide valuable guidance allowing the optimum use of supercomputer resources. We present initial results from a program to explore the 3D stability properties of flows previously studied using a 2D axisymmetric code, and our first attempt to explore the structure and morphology of a relativistic jet encountering an ambient density gradient that mimics an ambient inhomogeneity or cloud.

  8. Simulating coronal condensation dynamics in 3D

    NASA Astrophysics Data System (ADS)

    Moschou, S. P.; Keppens, R.; Xia, C.; Fang, X.

    2015-12-01

    We present numerical simulations in 3D settings where coronal rain phenomena take place in a magnetic configuration of a quadrupolar arcade system. Our simulation is a magnetohydrodynamic simulation including anisotropic thermal conduction, optically thin radiative losses, and parametrised heating as main thermodynamical features to construct a realistic arcade configuration from chromospheric to coronal heights. The plasma evaporation from chromospheric and transition region heights eventually causes localised runaway condensation events and we witness the formation of plasma blobs due to thermal instability, that evolve dynamically in the heated arcade part and move gradually downwards due to interchange type dynamics. Unlike earlier 2.5D simulations, in this case there is no large scale prominence formation observed, but a continuous coronal rain develops which shows clear indications of Rayleigh-Taylor or interchange instability, that causes the denser plasma located above the transition region to fall down, as the system moves towards a more stable state. Linear stability analysis is used in the non-linear regime for gaining insight and giving a prediction of the system's evolution. After the plasma blobs descend through interchange, they follow the magnetic field topology more closely in the lower coronal regions, where they are guided by the magnetic dips.

  9. Elastically deformable 3D organs for haptic surgical simulation.

    PubMed

    Webster, Roger; Haluck, Randy; Ravenscroft, Rob; Mohler, Betty; Crouthamel, Eric; Frack, Tyson; Terlecki, Steve; Sheaffer, Jeremy

    2002-01-01

    This paper describes a technique for incorporating real-time elastically deformable 3D organs in haptic surgical simulators. Our system is a physically based particle model utilizing a mass-springs-damper connectivity with an implicit predictor to speed up calculations during each time step. The solution involves repeated application of Newton's 2ndd Law of motion: F = ma using an implicit solver for numerically solving the differential equations. PMID:15458154

  10. Flare Particle Escape in 3D Solar Eruptive Events

    NASA Astrophysics Data System (ADS)

    Antiochos, Spiro K.; Masson, Sophie; DeVore, C. R.

    2015-04-01

    Among the most important, but least understood forms of space weather are the so-called Impulsive Solar Energetic Particle (SEP) events, which can be especially hazardous to deep-space astronauts. These energetic particles are generally believed to be produced by the flare reconnection that is the primary driver of solar eruptive events (SEE). A key point is that in the standard model of SEEs, the particles should remain trapped in the coronal flare loops and in the ejected plasmoid, the CME. However, flare-accelerated particles frequently reach the Earth long before the CME does. In previous 2.5D calculations we showed how the external reconnection that is an essential element of the breakout model for CME initiation could lead to the escape of flare-accelerated particles. The problem, however, is that in 2.5D this reconnection also tends to destroy the plasmoid, which disagrees with the observation that SEP events are often associated with well-defined plasmoids at 1 AU known as “magnetic clouds”. Consequently, we have extended our model to a fully 3D topology that includes a multi-polar coronal field suitable for a breakout SEE near a coronal hole region. We performed high-resolution 3D MHD numerical simulations with the Adaptively Refined MHD Solver (ARMS). Our results demonstrate that the model allows for the effective escape of energetic particles from deep within an ejecting well-defined plasmoid. We show how the complex interactions between the flare and breakout reconnection reproduce all the main observational features of SEEs and SEPs. We discuss the implications of our calculations for the upcoming Solar Orbiter and Solar Probe Plus missions, which will measure SEEs and SEPs near the Sun, thereby, mitigating propagation effects.This research was supported, in part, by the NASA SR&T and TR&T Programs.

  11. Resolution improvement by 3D particle averaging in localization microscopy

    PubMed Central

    Broeken, Jordi; Johnson, Hannah; Lidke, Diane S.; Liu, Sheng; Nieuwenhuizen, Robert P.J.; Stallinga, Sjoerd; Lidke, Keith A.; Rieger, Bernd

    2015-01-01

    Inspired by recent developments in localization microscopy that applied averaging of identical particles in 2D for increasing the resolution even further, we discuss considerations for alignment (registration) methods for particles in general and for 3D in particular. We detail that traditional techniques for particle registration from cryo electron microscopy based on cross-correlation are not suitable, as the underlying image formation process is fundamentally different. We argue that only localizations, i.e. a set of coordinates with associated uncertainties, are recorded and not a continuous intensity distribution. We present a method that owes to this fact and that is inspired by the field of statistical pattern recognition. In particular we suggest to use an adapted version of the Bhattacharyya distance as a merit function for registration. We evaluate the method in simulations and demonstrate it on three-dimensional super-resolution data of Alexa 647 labelled to the Nup133 protein in the nuclear pore complex of Hela cells. From the simulations we find suggestions that for successful registration the localization uncertainty must be smaller than the distance between labeling sites on a particle. These suggestions are supported by theoretical considerations concerning the attainable resolution in localization microscopy and its scaling behavior as a function of labeling density and localization precision. PMID:25866640

  12. 3D flare particle model for ShipIR/NTCS

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Srinivasan; Vaitekunas, David A.

    2016-05-01

    A key component in any soft-kill response to an incoming guided missile is the flare /chaff decoy used to distract or seduce the seeker homing system away from the naval platform. This paper describes a new 3D flare particle model in the naval threat countermeasure simulator (NTCS) of the NATO-standard ship signature model (ShipIR), which provides independent control over the size and radial distribution of its signature. The 3D particles of each flare sub-munition are modelled stochastically and rendered using OpenGL z-buffering, 2D projection, and alpha-blending to produce a unique and time varying signature. A sensitivity analysis on each input parameter provides the data and methods needed to synthesize a model from an IR measurement of a decoy. The new model also eliminated artifacts and deficiencies in our previous model which prevented reliable tracks from the adaptive track gate algorithm already presented by Ramaswamy and Vaitekunas (2015). A sequence of scenarios are used to test and demonstrate the new flare model during a missile engagement.

  13. 3D Simulations of the Beehive Proplyd

    NASA Astrophysics Data System (ADS)

    Feitosa, J. A.; Vasconcelos, M. J.; Cerqueira, A. H.

    2014-10-01

    Some star formation regions, like the Orion nebula, have stars of different masses, from massive stars, responsible for strong ionizing winds and HII regions, to low-mass stars, which spend a long time in the protostellar phase, and are frequently associated with protostellar disks and jets. Massive O or B stars emit a great deal of UV radiation, able to dissociate the hydrogen molecule (FUV radiation, energies between 6-13 eV), to ionize the atomic hydrogen (EUV radiation, energies greater than 13.6 eV) and heat the gas. Around these stars, a large and hot (10^{4}K) region is formed, known as HII region. T-Tauri stars inside HII regions produce a type of young stellar object, a proplyd, described with accuracy in O'Dell et al. (1993). Proplyds exhibit a cometary shape from which we can distinguish a central low-mass star with an accretion disk, an ionization front, a photodissociation region and, sometimes, an external bow shock and a protostellar jet. Its morphological characteristics depends on the distance between the low-mass star and the source of the ionizing radiation. The Beehive, a giant proplyd in Orion Nebula, has attracted attention due to its exotic system of rings coaxial to the HH540 jet's axis. Bally et al. (2005) suggested that the rings are perturbations due to the crossing of the ionization front by the jet. In this work, we test this hypothesis making 3D hydrodynamic numerical simulations over an adaptive grid, using the Yguazú-A code (Raga et al., 2000), properly adapted for the Beehive conditions. Our results show that the jet causes a perturbation in the ionization front of the proplyd, but is necessary to adjust carefully some parameters of the jet like its velocity and ejection frequency in order to have the results matching the observations.

  14. Optimizing Stellarators for Energetic Particle Confinement using BEAMS3D

    NASA Astrophysics Data System (ADS)

    Bolgert, Peter; Drevlak, Michael; Lazerson, Sam; Gates, David; White, Roscoe

    2015-11-01

    Energetic particle (EP) loss has been called the ``Achilles heel of stellarators,'' (Helander, Rep. Prog. Phys. 77 087001 (2014)) and there is a great need for magnetic configurations with improved EP confinement. In this study we utilize a newly developed capability of the stellarator optimization code STELLOPT: the ability to optimize EP confinement via an interface with guiding center code BEAMS3D (McMillan et al., Plasma Phys. Control. Fusion 56, 095019 (2014)). Using this new tool, optimizations of the W7-X experiment and ARIES-CS reactor are performed where the EP loss fraction is one of many target functions to be minimized. In W7-X, we simulate the experimental NBI system using realistic beam geometry and beam deposition physics. The goal is to find configurations with improved neutral beam deposition and energetic particle confinement. These calculations are compared to previous studies of W7-X NBI deposition. In ARIES-CS, we launch 3.5 MeV alpha particles from a near-axis flux surface using a uniform grid in toroidal and poloidal angle. As these particles are born from D-T reactions, we consider an isotropic distribution in velocity space. This research is supported by DoE Contract Number DE-AC02-09CH11466.

  15. Optofluidic fabrication for 3D-shaped particles.

    PubMed

    Paulsen, Kevin S; Di Carlo, Dino; Chung, Aram J

    2015-01-01

    Complex three-dimensional (3D)-shaped particles could play unique roles in biotechnology, structural mechanics and self-assembly. Current methods of fabricating 3D-shaped particles such as 3D printing, injection moulding or photolithography are limited because of low-resolution, low-throughput or complicated/expensive procedures. Here, we present a novel method called optofluidic fabrication for the generation of complex 3D-shaped polymer particles based on two coupled processes: inertial flow shaping and ultraviolet (UV) light polymerization. Pillars within fluidic platforms are used to deterministically deform photosensitive precursor fluid streams. The channels are then illuminated with patterned UV light to polymerize the photosensitive fluid, creating particles with multi-scale 3D geometries. The fundamental advantages of optofluidic fabrication include high-resolution, multi-scalability, dynamic tunability, simple operation and great potential for bulk fabrication with full automation. Through different combinations of pillar configurations, flow rates and UV light patterns, an infinite set of 3D-shaped particles is available, and a variety are demonstrated. PMID:25904062

  16. Optofluidic fabrication for 3D-shaped particles

    NASA Astrophysics Data System (ADS)

    Paulsen, Kevin S.; di Carlo, Dino; Chung, Aram J.

    2015-04-01

    Complex three-dimensional (3D)-shaped particles could play unique roles in biotechnology, structural mechanics and self-assembly. Current methods of fabricating 3D-shaped particles such as 3D printing, injection moulding or photolithography are limited because of low-resolution, low-throughput or complicated/expensive procedures. Here, we present a novel method called optofluidic fabrication for the generation of complex 3D-shaped polymer particles based on two coupled processes: inertial flow shaping and ultraviolet (UV) light polymerization. Pillars within fluidic platforms are used to deterministically deform photosensitive precursor fluid streams. The channels are then illuminated with patterned UV light to polymerize the photosensitive fluid, creating particles with multi-scale 3D geometries. The fundamental advantages of optofluidic fabrication include high-resolution, multi-scalability, dynamic tunability, simple operation and great potential for bulk fabrication with full automation. Through different combinations of pillar configurations, flow rates and UV light patterns, an infinite set of 3D-shaped particles is available, and a variety are demonstrated.

  17. 3D Numerical simulations of oblique subduction

    NASA Astrophysics Data System (ADS)

    Malatesta, C.; Gerya, T.; Scambelluri, M.; Crispini, L.; Federico, L.; Capponi, G.

    2012-04-01

    In the past 2D numerical studies (e.g. Gerya et al., 2002; Gorczyk et al., 2007; Malatesta et al., 2012) provided evidence that during intraoceanic subduction a serpentinite channel forms above the downgoing plate. This channel forms as a result of hydration of the mantle wedge by uprising slab-fluids. Rocks buried at high depths are finally exhumed within this buoyant low-viscosity medium. Convergence rate in these 2D models was described by a trench-normal component of velocity. Several present and past subduction zones worldwide are however driven by oblique convergence between the plates, where trench-normal motion of the subducting slab is coupled with trench-parallel displacement of the plates. Can the exhumation mechanism and the exhumation rates of high-pressure rocks be affected by the shear component of subduction? And how uprise of these rocks can vary along the plate margin? We tried to address these questions performing 3D numerical models that simulate an intraoceanic oblique subduction. The models are based on thermo-mechanical equations that are solved with finite differences method and marker-in-cell techniques combined with multigrid approach (Gerya, 2010). In most of the models a narrow oceanic basin (500 km-wide) surrounded by continental margins is depicted. The basin is floored by either layered or heterogeneous oceanic lithosphere with gabbro as discrete bodies in serpentinized peridotite and a basaltic layer on the top. A weak zone in the mantle is prescribed to control the location of subduction initiation and therefore the plate margins geometry. Finally, addition of a third dimension in the simulations allowed us to test the role of different plate margin geometries on oblique subduction dynamics. In particular in each model we modified the dip angle of the weak zone and its "lateral" geometry (e.g. continuous, segmented). We consider "continuous" weak zones either parallel or increasingly moving away from the continental margins

  18. Simulation of Current Generation in a 3-D Plasma Model

    NASA Astrophysics Data System (ADS)

    Tsung, F. S.; Dawson, J. M.

    1996-11-01

    In the advanced tokamak regime, transport phenomena can account for a signficant fraction of the toroidal current, possibly over that driven directly by the ohmic heating electric fields. Bootstrap theory accounts for contributions of the collisional modification of banana orbits on the toroidal currents. In our previous simulations in 21/2-D, currents were spontaneously generated in both the cylindrical and the toroidal geometries, contrary to neoclassical predictions. In these calculations, it was believed that the driving mechanism is the preferential loss of particles whose initial velocity is opposite to that of the plasma current. We are extending these simulations to three dimensions. A parallel 3-D electromagnetic PIC code running on the IBM SP2, with a localized field-solver has been developed to investigate the effects of perturbations parallel to the field lines, and direct comparisons has been made between the 21/2-D and 3-D simulations and we have found good agreements between the 2 1/2-D calculations and the 3-D results. We will present our new results at the meeting. Research partially supported by NSF and DOE.

  19. 3D simulation studies of tokamak plasmas using MHD and extended-MHD models

    SciTech Connect

    Park, W.; Chang, Z.; Fredrickson, E.; Fu, G.Y.

    1996-12-31

    The M3D (Multi-level 3D) tokamak simulation project aims at the simulation of tokamak plasmas using a multi-level tokamak code package. Several current applications using MHD and Extended-MHD models are presented; high-{beta} disruption studies in reversed shear plasmas using the MHD level MH3D code, {omega}{sub *i} stabilization and nonlinear island saturation of TAE mode using the hybrid particle/MHD level MH3D-K code, and unstructured mesh MH3D{sup ++} code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree which agree well with experimental data.

  20. Light Attenuation Method for 3D data acquisition (LAM3D) of bottom particle deposits

    NASA Astrophysics Data System (ADS)

    Er, Jenn Wei; Law, Adrian W. K.; Adams, E. Eric; Yang, Yang

    2015-11-01

    We have developed a novel experimental technique, Light Attenuation Method for 3D data acquisition (LAM3D), to acquire three-dimensional spatial characteristics and temporal development of bottom particle deposits. The new technique performs data acquisition with higher spatial and temporal resolution than existing approaches with laser and ultrasonic 3D profilers, and is therefore ideal for laboratory investigations with fast varying changes in the sediment bed, such as the developing deposition profile from sediment clouds commonly formed during dredging or land reclamation projects and the dynamic evolution in movable bed processes in rivers. The principle of the technique is based on the analysis of the light attenuation due to multiple light scattering through the particle deposits layer compared to the clear water column. With appropriate calibration, the particles size and distribution thickness can be quantified by the transmitted light spectrum. In the presentation, we will first show our measurement setup with a light panel for calibrated illumination and a system of DSLR cameras for the light capturing. Subsequently, we shall present the experimental results of fast evolving deposition profile of a barge-disposed sediment cloud upon its bottom impact on the sea bed.

  1. 3D simulations of an electrostatic quadrupole injector

    SciTech Connect

    Grote, D.P. |; Friedman, A.; Yu, S.

    1993-02-01

    Analysis of the dynamics of a space charge dominated beam in a lattice of electrostatic focusing structures requires a full three-dimensional conic that includes self-consistent space charge fields and the fields from the complex conductor shapes. The existing WARP3d code, a particle simulation code which has been developed for heavy-ion fusion (HIF) applications contains machinery for handling particles in three-dimensional fields. A successive overrelaxation field solver with subgrid-scale placement of boundaries for rounded surface and four-fold symmetry has been added to the code. The electrostatic quadrupole (ESQ) injector for the ILSE accelerator facility being planned at Lawrence Berkeley Laboratory is shown as an application. The issue of concern is possible emittance degradation because the focusing voltages are a significant fraction of the particles` energy and because there are significant nonlinear fields arising from the shapes of the quadrupole structures.

  2. Numerical simulation of 3D breaking waves

    NASA Astrophysics Data System (ADS)

    Fraunie, Philippe; Golay, Frederic

    2015-04-01

    Numerical methods dealing with two phase flows basically can be classified in two ways : the "interface tracking" methods when the two phases are resolved separately including boundary conditions fixed at the interface and the "interface capturing" methods when a single flow is considered with variable density. Physical and numerical properties of the two approaches are discussed, based on some numerical experiments performed concerning 3D breaking waves. Acknowledgements : This research was supported by the Modtercom program of Region PACA.

  3. Ultrafine particle emissions from desktop 3D printers

    NASA Astrophysics Data System (ADS)

    Stephens, Brent; Azimi, Parham; El Orch, Zeineb; Ramos, Tiffanie

    2013-11-01

    The development of low-cost desktop versions of three-dimensional (3D) printers has made these devices widely accessible for rapid prototyping and small-scale manufacturing in home and office settings. Many desktop 3D printers rely on heated thermoplastic extrusion and deposition, which is a process that has been shown to have significant aerosol emissions in industrial environments. However, we are not aware of any data on particle emissions from commercially available desktop 3D printers. Therefore, we report on measurements of size-resolved and total ultrafine particle (UFP) concentrations resulting from the operation of two types of commercially available desktop 3D printers inside a commercial office space. We also estimate size-resolved (11.5 nm-116 nm) and total UFP (<100 nm) emission rates and compare them to emission rates from other desktop devices and indoor activities known to emit fine and ultrafine particles. Estimates of emission rates of total UFPs were large, ranging from ˜2.0 × 1010 # min-1 for a 3D printer utilizing a polylactic acid (PLA) feedstock to ˜1.9 × 1011 # min-1 for the same type of 3D printer utilizing a higher temperature acrylonitrile butadiene styrene (ABS) thermoplastic feedstock. Because most of these devices are currently sold as standalone devices without any exhaust ventilation or filtration accessories, results herein suggest caution should be used when operating in inadequately ventilated or unfiltered indoor environments. Additionally, these results suggest that more controlled experiments should be conducted to more fundamentally evaluate particle emissions from a wider arrange of desktop 3D printers.

  4. Light shaping along 3D curves and particle manipulation

    NASA Astrophysics Data System (ADS)

    Rodrigo, José A.; Alieva, Tatiana

    2015-03-01

    We present a non-iterative holographic technique for efficient and versatile laser beam shaping along arbitrary 3D curves. Light beams with intensity shaped for several 3D curves: Tilted ring, Viviani's curve, Archimedean spiral, and trefoil-knotted curve have been experimentally generated and applied for optical trapping of micrometer-sized dielectric particles. The high intensity gradients and independent phase control prescribed along the curve make this kind of laser trap attractive for multiple particle manipulation and allow for forward and backward motion to the light source. Indeed, different configurations of tractor beam traps are experimentally demonstrated. This technique can also be applied for laser micro-machining.

  5. Iterative Reconstruction of Volumetric Particle Distribution for 3D Velocimetry

    NASA Astrophysics Data System (ADS)

    Wieneke, Bernhard; Neal, Douglas

    2011-11-01

    A number of different volumetric flow measurement techniques exist for following the motion of illuminated particles. For experiments that have lower seeding densities, 3D-PTV uses recorded images from typically 3-4 cameras and then tracks the individual particles in space and time. This technique is effective in flows that have lower seeding densities. For flows that have a higher seeding density, tomographic PIV uses a tomographic reconstruction algorithm (e.g. MART) to reconstruct voxel intensities of the recorded volume followed by the cross-correlation of subvolumes to provide the instantaneous 3D vector fields on a regular grid. A new hybrid algorithm is presented which iteratively reconstructs the 3D-particle distribution directly using particles with certain imaging properties instead of voxels as base functions. It is shown with synthetic data that this method is capable of reconstructing densely seeded flows up to 0.05 particles per pixel (ppp) with the same or higher accuracy than 3D-PTV and tomographic PIV. Finally, this new method is validated using experimental data on a turbulent jet.

  6. 3-D numerical simulations of volcanic ash transport and deposition

    NASA Astrophysics Data System (ADS)

    Suzuki, Y. J.; Koyaguchi, T.

    2012-12-01

    During an explosive volcanic eruption, volcanic gas and pyroclasts are ejected from the volcanic vent. The pyroclasts are carried up within a convective plume, advected by the surrounding wind field, and sediment on the ground depending on their terminal velocity. The fine ash are expected to have atmospheric residence, whereas the coarser particles form fall deposits. Accurate modeling of particle transport and deposition is of critical importance from the viewpoint of disaster prevention. Previously, some particle-tracking models (e.g., PUFF) and advection-diffusion models (e.g., TEPHRA2 and FALL3D) tried to forecast particle concentration in the atmosphere and particle loading at ground level. However, these models assumed source conditions (the grain-size distribution, plume height, and mass release location) based on the simple 1-D model of convective plume. In this study, we aim to develop a new 3-D model which reproduces both of the dynamics of convective plume and the ash transport. The model is designed to describe the injection of eruption cloud and marker particles from a circular vent above a flat surface into the stratified atmosphere. Because the advection is the predominant mechanism of particle transport near the volcano, the diffusive process is not taken into account in this model. The distribution of wind velocity is given as an initial condition. The model of the eruption cloud dynamics is based on the 3-D time-dependent model of Suzuki et al. (2005). We apply a pseudo-gas model to calculate the eruption cloud dynamics: the effect of particle separation on the cloud dynamics is not considered. In order to reproduce the drastic change of eruption cloud density, we change the effective gas constant and heat capacity of the mixture in the equation of state for ideal gases with the mixing ratio between the ejected material and entrained air. In order to calculate the location and movement of ash particles, the present model employs Lagrangian marker

  7. Vertical Flow Lithography for Fabrication of 3D Anisotropic Particles.

    PubMed

    Habasaki, Shohei; Lee, Won Chul; Yoshida, Shotaro; Takeuchi, Shoji

    2015-12-22

    A microfluidics-based method for the 3D fabrication of anisotropic particles is reported. The method uses a vertical microchannel where tunable light patterns solidify photocurable resins for stacking multiple layers of the resins, thus enabling an application of stereolithography concepts to conventional flow lithography. Multilayered, tapered, and angular compartmental microparticles are demonstrated. PMID:26551590

  8. 3D visualization of port simulation.

    SciTech Connect

    Horsthemke, W. H.; Macal, C. M.; Nevins, M. R.

    1999-06-14

    Affordable and realistic three dimensional visualization technology can be applied to large scale constructive simulations such as the port simulation model, PORTSIM. These visualization tools enhance the experienced planner's ability to form mental models of how seaport operations will unfold when the simulation model is implemented and executed. They also offer unique opportunities to train new planners not only in the use of the simulation model but on the layout and design of seaports. Simulation visualization capabilities are enhanced by borrowing from work on interface design, camera control, and data presentation. Using selective fidelity, the designers of these visualization systems can reduce their time and efforts by concentrating on those features which yield the most value for their simulation. Offering the user various observational tools allows the freedom to simply watch or engage in the simulation without getting lost. Identifying the underlying infrastructure or cargo items with labels can provide useful information at the risk of some visual clutter. The PortVis visualization expands the PORTSIM user base which can benefit from the results provided by this capability, especially in strategic planning, mission rehearsal, and training. Strategic planners will immediately reap the benefits of seeing the impact of increased throughput visually without keeping track of statistical data. Mission rehearsal and training users will have an effective training tool to supplement their operational training exercises which are limited in number because of their high costs. Having another effective training modality in this visualization system allows more training to take place and more personnel to gain an understanding of seaport operations. This simulation and visualization training can be accomplished at lower cost than would be possible for the operational training exercises alone. The application of PORTSIM and PortVis will lead to more efficient

  9. 3D implicit PIC simulations of solar wind - moon interactions

    NASA Astrophysics Data System (ADS)

    Deca, J.; Markidis, S.; Divin, A.; Lapenta, G.; Vapirev, A.

    2012-04-01

    We present three-dimensional Particle-in-Cell simulations of an unmagnetized insulating Moon-sized body immersed in the solar wind. The simulations are performed using the implicit electromagnetic Particle-in-Cell code iPIC3D [Markidis, 2009]. Multiscale kinetic physics is resolved for all plasma components (heavy ions, protons and electrons) in the code, recently updated with a set of open boundary conditions designed for solar wind - body interaction studies. Particles are injected at the inflow side of the computational domain and absorbed at all others. A bow shock is not formed upstream of the body, but the obstacle generates faint dispersive waves propagating parallel to the magnetic field lines, in agreement with numerical simulations done in MHD approach. Polarization electric field is generated in the wake. In addition, plasma flows filling the wake tend to excite streaming instabilities, which lead to bipolar signatures in the parallel electric field. Our future work includes updating the physical model to include photoionization and re-emission at the object's surface.

  10. Simulation of 3D infrared scenes using random fields model

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Zhang, Jianqi

    2001-09-01

    Analysis and simulation of smart munitions requires imagery for the munition's sensor to view. The traditional infrared background simulations are always limited in the plane scene studies. A new method is described to synthesize the images in 3D view and with various terrains texture. We develop the random fields model and temperature fields to simulate 3D infrared scenes. Generalized long-correlation (GLC) model, one of random field models, will generate both the 3D terrains skeleton data and the terrains texture in this work. To build the terrain mesh with the random fields, digital elevation models (DEM) are introduced in the paper. And texture mapping technology will perform the task of pasting the texture in the concavo-convex surfaces of the 3D scene. The simulation using random fields model is a very available method to produce 3D infrared scene with great randomicity and reality.

  11. 3-D PARTICLE TRANSPORT WITHIN THE HUMAN UPPER RESPIRATORY TRACT

    EPA Science Inventory

    In this study trajectories of inhaled particulate matter (PM) were simulated within a three-dimensional (3-D) computer model of the human upper respiratory tract (URT). The airways were described by computer-reconstructed images of a silicone rubber cast of the human head, throat...

  12. 3D MHD Simulations of Spheromak Compression

    NASA Astrophysics Data System (ADS)

    Stuber, James E.; Woodruff, Simon; O'Bryan, John; Romero-Talamas, Carlos A.; Darpa Spheromak Team

    2015-11-01

    The adiabatic compression of compact tori could lead to a compact and hence low cost fusion energy system. The critical scientific issues in spheromak compression relate both to confinement properties and to the stability of the configuration undergoing compression. We present results from the NIMROD code modified with the addition of magnetic field coils that allow us to examine the role of rotation on the stability and confinement of the spheromak (extending prior work for the FRC). We present results from a scan in initial rotation, from 0 to 100km/s. We show that strong rotational shear (10km/s over 1cm) occurs. We compare the simulation results with analytic scaling relations for adiabatic compression. Work performed under DARPA grant N66001-14-1-4044.

  13. Rockfall assessment of natural hazards by 3D-simulation

    NASA Astrophysics Data System (ADS)

    Tobler, D.; Graf, K.; Krummenacher, B.

    2009-04-01

    Keywords: 3D rockfall modelling, protection measures, case study, ROFMOD 4.1 model In mountain areas many residential areas as well as important lifelines are exposed to potential rockfall events. The assessment of the hazard potential in a complex morphology with changing surface parameters and inhomogeneous forestation, call for an in-depth analysis of the physical processes involved. Therefore the different problems concerning the assessment of rockfall hazards have to be solved adequately. Moreover, due to the actual discussion about cost efficiency the planning of protective measures calls for (more) detailed information about the intensity and probability of expected rockfall incidents along a typical trajectory or for a given area. Today simulation models like GEOTEST's - ROFMOD 4.1 (2D and 3D) are important tools for hazard assessment. This simulation model produces profiles and maps with intensity and range and allows to calculate decisive parameters for the dimensioning optimized positioning of protection measures. Within the impact analysis the relevant scenarios according to their intensities are determined using a 3D rockfall model. It calculates the trajectories of rock-bodies with realistic forms based on physical laws from defined starting points within the mapped rock area as well as steep slopes with loose blocks. The movement is of any chosen particle with defined axis length ratio, rounding and specific weight is strongly influenced by the spatial resolution of the digital terrain model (DTM as well as the interaction with the underground and possible tree-impacts). Therefore, the following parameters are implemented in the rockfall model: geometry of blocks, underground plasticity (value of attenuation), surface roughness as well as forest quality (amount of trees per area (ha) and trunk diameter). A very important aspect is the geometry of the blocks. For realistic results only a simulation with real block shapes will be sucessful. For these

  14. 3D radiative transfer in colliding wind binaries: Application of the SimpleX algorithm to 3D SPH simulations

    NASA Astrophysics Data System (ADS)

    Madura, Thomas; Clementel, Nicola; Kruip, Chael; Icke, Vincent; Gull, Theodore

    2014-09-01

    We present the first results of full 3D radiative transfer simulations of the colliding stellar winds in a massive binary system. We accomplish this by applying the SIMPLEX algorithm for 3D radiative transfer on an unstructured Delaunay grid to recent 3D smoothed particle hydrodynamics (SPH) simulations of the colliding winds in the binary system η Carinae. We use SIMPLEX to obtain detailed ionization fractions of hydrogen and helium, in 3D, at the resolution of the original SPH simulations. We show how the SIMPLEX simulations can be used to generate synthetic spectral data cubes for comparison to data obtained with the Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph as part of a multi-cycle program to map changes in η Car's extended interacting wind structures across one binary cycle. Comparison of the HST observations to the SIMPLEX models can help lead to more accurate constraints on the orbital, stellar, and wind parameters of the η Car system, such as the primary's mass-loss rate and the companion's temperature and luminosity. While we initially focus specifically on the η Car binary, the numerical methods employed can be applied to numerous other colliding wind (WR140, WR137, WR19) and dusty 'pinwheel' (WR104, WR98a) binary systems. One of the biggest remaining mysteries is how dust can form and survive in such systems that contain a hot, luminous O star. Coupled with 3D hydrodynamical simulations, SIMPLEX simulations have the potential to help determine the regions where dust can form and survive in these unique objects.

  15. Design of 3D simulation engine for oilfield safety training

    NASA Astrophysics Data System (ADS)

    Li, Hua-Ming; Kang, Bao-Sheng

    2015-03-01

    Aiming at the demand for rapid custom development of 3D simulation system for oilfield safety training, this paper designs and implements a 3D simulation engine based on script-driven method, multi-layer structure, pre-defined entity objects and high-level tools such as scene editor, script editor, program loader. A scripting language been defined to control the system's progress, events and operating results. Training teacher can use this engine to edit 3D virtual scenes, set the properties of entity objects, define the logic script of task, and produce a 3D simulation training system without any skills of programming. Through expanding entity class, this engine can be quickly applied to other virtual training areas.

  16. An Evaluative Review of Simulated Dynamic Smart 3d Objects

    NASA Astrophysics Data System (ADS)

    Romeijn, H.; Sheth, F.; Pettit, C. J.

    2012-07-01

    Three-dimensional (3D) modelling of plants can be an asset for creating agricultural based visualisation products. The continuum of 3D plants models ranges from static to dynamic objects, also known as smart 3D objects. There is an increasing requirement for smarter simulated 3D objects that are attributed mathematically and/or from biological inputs. A systematic approach to plant simulation offers significant advantages to applications in agricultural research, particularly in simulating plant behaviour and the influences of external environmental factors. This approach of 3D plant object visualisation is primarily evident from the visualisation of plants using photographed billboarded images, to more advanced procedural models that come closer to simulating realistic virtual plants. However, few programs model physical reactions of plants to external factors and even fewer are able to grow plants based on mathematical and/or biological parameters. In this paper, we undertake an evaluation of plant-based object simulation programs currently available, with a focus upon the components and techniques involved in producing these objects. Through an analytical review process we consider the strengths and weaknesses of several program packages, the features and use of these programs and the possible opportunities in deploying these for creating smart 3D plant-based objects to support agricultural research and natural resource management. In creating smart 3D objects the model needs to be informed by both plant physiology and phenology. Expert knowledge will frame the parameters and procedures that will attribute the object and allow the simulation of dynamic virtual plants. Ultimately, biologically smart 3D virtual plants that react to changes within an environment could be an effective medium to visually represent landscapes and communicate land management scenarios and practices to planners and decision-makers.

  17. 3D Ultrasonic Wave Simulations for Structural Health Monitoring

    NASA Technical Reports Server (NTRS)

    Campbell, Leckey Cara A/; Miler, Corey A.; Hinders, Mark K.

    2011-01-01

    Structural health monitoring (SHM) for the detection of damage in aerospace materials is an important area of research at NASA. Ultrasonic guided Lamb waves are a promising SHM damage detection technique since the waves can propagate long distances. For complicated flaw geometries experimental signals can be difficult to interpret. High performance computing can now handle full 3-dimensional (3D) simulations of elastic wave propagation in materials. We have developed and implemented parallel 3D elastodynamic finite integration technique (3D EFIT) code to investigate ultrasound scattering from flaws in materials. EFIT results have been compared to experimental data and the simulations provide unique insight into details of the wave behavior. This type of insight is useful for developing optimized experimental SHM techniques. 3D EFIT can also be expanded to model wave propagation and scattering in anisotropic composite materials.

  18. Digital In-Line Holography System for 3D-3C Particle Tracking Velocimetry

    NASA Astrophysics Data System (ADS)

    Malek, Mokrane; Lebrun, Denis; Allano, Daniel

    Digital in-line holography is a suitable method for measuring three dimensional (3D) velocity fields. Such a system records directly on a charge-coupled device (CCD) camera a couple of diffraction patterns produced by small particles illuminated by a modulated laser diode. The numerical reconstruction is based on the wavelet transformation method. A 3D particle field is reconstructed by computing the wavelet components for different scale parameters. The scale parameter is directly related to the axial distance between a given particle and the CCD camera. The particle images are identified and localized by analyzing the maximum of the wavelet transform modulus (WTMM) and the equivalent diameter of the particle image (Deq). Afterwards, a 3D point-matching (PM) algorithm is applied to the pair of sets containing the 3D particle locations. In the PM algorithm, the displacement of the particles is modeled by an affine transformation. This affine transformation is based on the use of the dual number quaternions. Afterwards, the velocity-field extraction is performed. This system is tested with simulated particle field displacements and the feasibility is checked with an experimental displacement.

  19. Computationally efficient storage of 3D particle intensity and position data for use in 3D PIV and 3D PTV

    NASA Astrophysics Data System (ADS)

    Atkinson, C.; Buchmann, N. A.; Soria, J.

    2013-11-01

    Three-dimensional (3D) volumetric velocity measurement techniques, such as tomographic or holographic particle image velocimetry (PIV), rely upon the computationally intensive formation, storage and localized interrogation of multiple 3D particle intensity fields. Calculation of a single velocity field typically requires the extraction of particle intensities into tens of thousands of 3D sub-volumes or discrete particle clusters, the processing of which can significantly affect the performance of 3D cross-correlation based PIV and 3D particle tracking velocimetry (PTV). In this paper, a series of popular and customized volumetric data formats are presented and investigated using synthetic particle volumes and experimental data arising from tomographic PIV measurements of a turbulent boundary layer. Results show that the use of a sub-grid ordered non-zero intensity format with a sub-grid size of 16 × 16 × 16 points provides the best performance for cross-correlation based PIV analysis, while a particle clustered non-zero intensity format provides the best format for PTV applications. In practical tomographic PIV measurements the sub-grid ordered non-zero intensity format offered a 29% improvement in reconstruction times, while providing a 93% reduction in volume data requirements and a 28% overall improvement in cross-correlation based velocity analysis and validation times.

  20. First 3-D simulations of meteor plasma dynamics and turbulence

    NASA Astrophysics Data System (ADS)

    Oppenheim, Meers M.; Dimant, Yakov S.

    2015-02-01

    Millions of small but detectable meteors hit the Earth's atmosphere every second, creating trails of hot plasma that turbulently diffuse into the background atmosphere. For over 60 years, radars have detected meteor plasmas and used these signals to infer characteristics of the meteoroid population and upper atmosphere, but, despite the importance of meteor radar measurements, the complex processes by which these plasmas evolve have never been thoroughly explained or modeled. In this paper, we present the first fully 3-D simulations of meteor evolution, showing meteor plasmas developing instabilities, becoming turbulent, and inhomogeneously diffusing into the background ionosphere. These instabilities explain the characteristics and strength of many radar observations, in particular the high-resolution nonspecular echoes made by large radars. The simulations reveal how meteors create strong electric fields that dig out deep plasma channels along the Earth's magnetic fields. They also allow researchers to explore the impacts of the intense winds and wind shears, commonly found at these altitudes, on meteor plasma evolution. This study will allow the development of more sophisticated models of meteor radar signals, enabling the extraction of detailed information about the properties of meteoroid particles and the atmosphere.

  1. Simulations of Coulomb systems with slab geometry using an efficient 3D Ewald summation method

    NASA Astrophysics Data System (ADS)

    dos Santos, Alexandre P.; Girotto, Matheus; Levin, Yan

    2016-04-01

    We present a new approach to efficiently simulate electrolytes confined between infinite charged walls using a 3d Ewald summation method. The optimal performance is achieved by separating the electrostatic potential produced by the charged walls from the electrostatic potential of electrolyte. The electric field produced by the 3d periodic images of the walls is constant inside the simulation cell, with the field produced by the transverse images of the charged plates canceling out. The non-neutral confined electrolyte in an external potential can be simulated using 3d Ewald summation with a suitable renormalization of the electrostatic energy, to remove a divergence, and a correction that accounts for the conditional convergence of the resulting lattice sum. The new algorithm is at least an order of magnitude more rapid than the usual simulation methods for the slab geometry and can be further sped up by adopting a particle-particle particle-mesh approach.

  2. 3d visualization of atomistic simulations on every desktop

    NASA Astrophysics Data System (ADS)

    Peled, Dan; Silverman, Amihai; Adler, Joan

    2013-08-01

    Once upon a time, after making simulations, one had to go to a visualization center with fancy SGI machines to run a GL visualization and make a movie. More recently, OpenGL and its mesa clone have let us create 3D on simple desktops (or laptops), whether or not a Z-buffer card is present. Today, 3D a la Avatar is a commodity technique, presented in cinemas and sold for home TV. However, only a few special research centers have systems large enough for entire classes to view 3D, or special immersive facilities like visualization CAVEs or walls, and not everyone finds 3D immersion easy to view. For maximum physics with minimum effort a 3D system must come to each researcher and student. So how do we create 3D visualization cheaply on every desktop for atomistic simulations? After several months of attempts to select commodity equipment for a whole room system, we selected an approach that goes back a long time, even predating GL. The old concept of anaglyphic stereo relies on two images, slightly displaced, and viewed through colored glasses, or two squares of cellophane from a regular screen/projector or poster. We have added this capability to our AViz atomistic visualization code in its new, 6.1 version, which is RedHat, CentOS and Ubuntu compatible. Examples using data from our own research and that of other groups will be given.

  3. 3-D laser radar simulation for autonomous spacecraft landing

    NASA Technical Reports Server (NTRS)

    Reiley, Michael F.; Carmer, Dwayne C.; Pont, W. F.

    1991-01-01

    A sophisticated 3D laser radar sensor simulation, developed and applied to the task of autonomous hazard detection and avoidance, is presented. This simulation includes a backward ray trace to sensor subpixels, incoherent subpixel integration, range dependent noise, sensor point spread function effects, digitization noise, and AM-CW modulation. Specific sensor parameters, spacecraft lander trajectory, and terrain type have been selected to generate simulated sensor data.

  4. Current loop coalescence studied by 3-D electromagnetic particle code

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi; Sakai, Jun-Ichi; Koide, Shinji; Buneman, O.; Neubert, T.

    1993-01-01

    Solar flare plasma data from the Yohkoh satellite is analyzed. The interactions of current loops were observed in the active regions on the Sun. This observation pointed out the importance of the idea that the solar flare is generated by the coalescence of current loops. The three dimensional electromagnetic particle simulations are to help in understanding the global interaction between two current loops including the evolution of the twist of loops due to instabilities. Associated rapid dynamics of current loop coalescence such as reconnection, shock waves and associated kinetic processes such as energy transfer, acceleration of particles, and electromagnetic emissions are to be studied by the code to complement analytical theories and magnetohydrodynamic simulations of the current loop coalescence. The simulation results show the strong interactions between two current loops, beam and whistler instabilities, and associated parallel and perpendicular particle heating.

  5. 3D Fiber Orientation Simulation for Plastic Injection Molding

    NASA Astrophysics Data System (ADS)

    Lin, Baojiu; Jin, Xiaoshi; Zheng, Rong; Costa, Franco S.; Fan, Zhiliang

    2004-06-01

    Glass fiber reinforced polymer is widely used in the products made using injection molding processing. The distribution of fiber orientation inside plastic parts has direct effects on quality of molded parts. Using computer simulation to predict fiber orientation distribution is one of most efficient ways to assist engineers to do warpage analysis and to find a good design solution to produce high quality plastic parts. Fiber orientation simulation software based on 2-1/2D (midplane /Dual domain mesh) techniques has been used in industry for a decade. However, the 2-1/2D technique is based on the planar Hele-Shaw approximation and it is not suitable when the geometry has complex three-dimensional features which cannot be well approximated by 2D shells. Recently, a full 3D simulation software for fiber orientation has been developed and integrated into Moldflow Plastics Insight 3D simulation software. The theory for this new 3D fiber orientation calculation module is described in this paper. Several examples are also presented to show the benefit in using 3D fiber orientation simulation.

  6. 3D mapping and simulation of Geneva Lake environmental data

    NASA Astrophysics Data System (ADS)

    Villard, Roch; Maignan, Michel; Kanevski, Mikhail; Rapin, Francois; Klein, Audrey

    2010-05-01

    The Geneva Lake is the biggest alpine and subalpine lake in central Europe. The depth of this lake is 309 meters and its total volume of water is 89 billions m3. It takes, on average, around twelve years so that waters of the lake are completely brewed. Furthermore the Geneva lake waters are rich in dissolved substances as carbonate, sulfate. The quantity of particles in suspension in the lake, which mainly arrived from the Rhône, is nowadays around height million of tones. The International Commission for the Leman Lake (CIPEL) works about the improvement of the quality of this lake since 1962. In the present study three dimensional environmental data (temperature, oxygen and nitrate) which cover the period from 1954 to 2008, for a total of 27'500 cases are investigated. We are interested to study the evolution of the temperature of the lake because there is an impact on the reproduction of fishes and also because the winter brewing of the water makes the re-oxygenation of deep-water. In order that biological balance is maintained in a lake, there must be enough oxygen in the water. Moreover, we work on nitrate distribution and evolution because contributions in fertilizers cause eutrophication of lake. The data are very numerous when we consider the time series, some of them with more than 300 occurrences, but there are between 2 and 15 data available for spatial cartography. The basic methodology used for the analysis, mapping and simulations of 3D patterns of environmental data is based on geostatistical predictions (family of kriging models) and conditional stochastic simulations. Spatial and temporal variability, 3D monitoring networks changing over time, make this study challenging. An important problem is also to make interpolation/simulations over a long period of time, like ten years. One way used to overcome this problem, consists in using a weighted average of ten variograms during this period. 3D mapping was carried out using environment data for

  7. 3D two-fluid simulations of turbulence in LAPD

    NASA Astrophysics Data System (ADS)

    Fisher, Dustin M.

    The Large Plasma Device (LAPD) is modeled using a modified version of the 3D Global Braginskii Solver code (GBS) for a nominal Helium plasma. The unbiased low-flow regime is explored in simulations where there is an intrinsic E x B rotation of the plasma. In the simulations this rotation is caused primarily by sheath effects with the Reynolds stress and J x B torque due to a cross-field Pederson conductivity having little effect. Explicit biasing simulations are also explored for the first time where the intrinsic rotation of the plasma is modified through boundary conditions that mimic the biasable limiter used in LAPD. Comparisons to experimental measurements in the unbiased case show strong qualitative agreement with the data, particularly the radial dependence of the density fluctuations, cross-correlation lengths, radial flux dependence outside of the cathode edge, and camera imagery. Kelvin Helmholtz (KH) turbulence at relatively large scales is the dominant driver of cross-field transport in these simulations with smaller-scale drift waves and sheath modes playing a secondary role. Plasma holes and blobs arising from KH vortices are consistent with the scale sizes and overall appearance of those in LAPD camera images. The addition of ion-neutral collisions in the unbiased simulations at previously theorized values reduces the radial particle flux due to a modest stabilizing contribution of the collisions on the KH-modes driving the turbulent transport. In the biased runs the ion-neutral collisions have a much smaller effect due to the modification of the potential from sheath terms. In biasing the plasma to increase the intrinsic rotation, simulations show the emergence of a nonlinearly saturated coherent mode of order m = 6. In addition, the plasma inside of the cathode edge becomes quiescent due to the strong influence of the wall bias in setting up the equilibrium plasma potential. Biasing in the direction opposite to the intrinsic flow reduces the

  8. Parallelization of Program to Optimize Simulated Trajectories (POST3D)

    NASA Technical Reports Server (NTRS)

    Hammond, Dana P.; Korte, John J. (Technical Monitor)

    2001-01-01

    This paper describes the parallelization of the Program to Optimize Simulated Trajectories (POST3D). POST3D uses a gradient-based optimization algorithm that reaches an optimum design point by moving from one design point to the next. The gradient calculations required to complete the optimization process, dominate the computational time and have been parallelized using a Single Program Multiple Data (SPMD) on a distributed memory NUMA (non-uniform memory access) architecture. The Origin2000 was used for the tests presented.

  9. 3D Structural Fluctuation of IgG1 Antibody Revealed by Individual Particle Electron Tomography

    PubMed Central

    Zhang, Xing; Zhang, Lei; Tong, Huimin; Peng, Bo; Rames, Matthew J.; Zhang, Shengli; Ren, Gang

    2015-01-01

    Commonly used methods for determining protein structure, including X-ray crystallography and single-particle reconstruction, often provide a single and unique three-dimensional (3D) structure. However, in these methods, the protein dynamics and flexibility/fluctuation remain mostly unknown. Here, we utilized advances in electron tomography (ET) to study the antibody flexibility and fluctuation through structural determination of individual antibody particles rather than averaging multiple antibody particles together. Through individual-particle electron tomography (IPET) 3D reconstruction from negatively-stained ET images, we obtained 120 ab-initio 3D density maps at an intermediate resolution (~1–3 nm) from 120 individual IgG1 antibody particles. Using these maps as a constraint, we derived 120 conformations of the antibody via structural flexible docking of the crystal structure to these maps by targeted molecular dynamics simulations. Statistical analysis of the various conformations disclosed the antibody 3D conformational flexibility through the distribution of its domain distances and orientations. This blueprint approach, if extended to other flexible proteins, may serve as a useful methodology towards understanding protein dynamics and functions. PMID:25940394

  10. 3D structural fluctuation of IgG1 antibody revealed by individual particle electron tomography

    SciTech Connect

    Zhang, Xing; Zhang, Lei; Tong, Huimin; Peng, Bo; Rames, Matthew J.; Zhang, Shengli; Ren, Gang

    2015-05-05

    Commonly used methods for determining protein structure, including X-ray crystallography and single-particle reconstruction, often provide a single and unique three-dimensional (3D) structure. However, in these methods, the protein dynamics and flexibility/fluctuation remain mostly unknown. Here, we utilized advances in electron tomography (ET) to study the antibody flexibility and fluctuation through structural determination of individual antibody particles rather than averaging multiple antibody particles together. Through individual-particle electron tomography (IPET) 3D reconstruction from negatively-stained ET images, we obtained 120 ab-initio 3D density maps at an intermediate resolution (~1–3 nm) from 120 individual IgG1 antibody particles. Using these maps as a constraint, we derived 120 conformations of the antibody via structural flexible docking of the crystal structure to these maps by targeted molecular dynamics simulations. Statistical analysis of the various conformations disclosed the antibody 3D conformational flexibility through the distribution of its domain distances and orientations. This blueprint approach, if extended to other flexible proteins, may serve as a useful methodology towards understanding protein dynamics and functions.

  11. 3D structural fluctuation of IgG1 antibody revealed by individual particle electron tomography

    DOE PAGESBeta

    Zhang, Xing; Zhang, Lei; Tong, Huimin; Peng, Bo; Rames, Matthew J.; Zhang, Shengli; Ren, Gang

    2015-05-05

    Commonly used methods for determining protein structure, including X-ray crystallography and single-particle reconstruction, often provide a single and unique three-dimensional (3D) structure. However, in these methods, the protein dynamics and flexibility/fluctuation remain mostly unknown. Here, we utilized advances in electron tomography (ET) to study the antibody flexibility and fluctuation through structural determination of individual antibody particles rather than averaging multiple antibody particles together. Through individual-particle electron tomography (IPET) 3D reconstruction from negatively-stained ET images, we obtained 120 ab-initio 3D density maps at an intermediate resolution (~1–3 nm) from 120 individual IgG1 antibody particles. Using these maps as a constraint, wemore » derived 120 conformations of the antibody via structural flexible docking of the crystal structure to these maps by targeted molecular dynamics simulations. Statistical analysis of the various conformations disclosed the antibody 3D conformational flexibility through the distribution of its domain distances and orientations. This blueprint approach, if extended to other flexible proteins, may serve as a useful methodology towards understanding protein dynamics and functions.« less

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

    SciTech Connect

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

    1981-06-30

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

  13. Continuous dielectrophoretic particle separation using a microfluidic device with 3D electrodes and vaulted obstacles.

    PubMed

    Jia, Yankai; Ren, Yukun; Jiang, Hongyuan

    2015-08-01

    This paper reports a microfluidic separation device combining 3D electrodes and vaulted obstacles to continuously separate particles experiencing strong positive dielectrophoresis (DEP) from particles experiencing weak positive DEP, or from particles experiencing negative DEP. The separation is achieved by first focusing the particle mixture into a narrow stream by a hydrodynamic focusing flow, and then deviating them into different outlets by AC DEP. The vaulted obstacles facilitate the separation by both increasing the non-uniformity of the electric field, and influencing the particles to move in regions strongly affected by DEP. The 3D electrodes give rise to a spatially non-uniform electric field and extend DEP effect to the channel height. Numerical simulations are performed to investigate the effects of the obstacles on electric field distribution and particle trajectories so as to optimize the obstacle height and compare with the experimental results. The performance of the device is assessed by separating 25 μm gold-coated particles from 10 μm particles in different flow rates by positive DEP and negative DEP, and also separating 25 μm gold-coated particles from yeast cells using only positive DEP. The experimental observation shows a reasonable agreement with numerical simulation results. PMID:25962351

  14. VISRAD, 3-D Target Design and Radiation Simulation Code

    NASA Astrophysics Data System (ADS)

    Li, Yingjie; Macfarlane, Joseph; Golovkin, Igor

    2015-11-01

    The 3-D view factor code VISRAD is widely used in designing HEDP experiments at major laser and pulsed-power facilities, including NIF, OMEGA, OMEGA-EP, ORION, LMJ, Z, and PLX. It simulates target designs by generating a 3-D grid of surface elements, utilizing a variety of 3-D primitives and surface removal algorithms, and can be used to compute the radiation flux throughout the surface element grid by computing element-to-element view factors and solving power balance equations. Target set-up and beam pointing are facilitated by allowing users to specify positions and angular orientations using a variety of coordinates systems (e.g., that of any laser beam, target component, or diagnostic port). Analytic modeling for laser beam spatial profiles for OMEGA DPPs and NIF CPPs is used to compute laser intensity profiles throughout the grid of surface elements. We will discuss recent improvements to the software package and plans for future developments.

  15. 3D finite element simulations of high velocity projectile impact

    NASA Astrophysics Data System (ADS)

    Ožbolt, Joško; İrhan, Barış; Ruta, Daniela

    2015-09-01

    An explicit three-dimensional (3D) finite element (FE) code is developed for the simulation of high velocity impact and fragmentation events. The rate sensitive microplane material model, which accounts for large deformations and rate effects, is used as a constitutive law. In the code large deformation frictional contact is treated by forward incremental Lagrange multiplier method. To handle highly distorted and damaged elements the approach based on the element deletion is employed. The code is then used in 3D FE simulations of high velocity projectile impact. The results of the numerical simulations are evaluated and compared with experimental results. It is shown that it realistically predicts failure mode and exit velocities for different geometries of plain concrete slab. Moreover, the importance of some relevant parameters, such as contact friction, rate sensitivity, bulk viscosity and deletion criteria are addressed.

  16. 3-D simulation of nanopore structure for DNA sequencing.

    PubMed

    Park, Jun-Mo; Pak, Y Eugene; Chun, Honggu; Lee, Jong-Ho

    2012-07-01

    In this paper, we propose a method for simulating nanopore structure by using conventional 3-D simulation tool to mimic the I-V behavior of the nanopore structure. In the simulation, we use lightly doped silicon for ionic solution where some parameters like electron affinity and dielectric constant are fitted to consider the ionic solution. By using this method, we can simulate the I-V behavior of nanopore structure depending on the location and the size of the sphere shaped silicon oxide which is considered to be an indicator of a DNA base. In addition, we simulate an Ionic Field Effect Transistor (IFET) which has basically the nanopore structure, and show that the simulated curves follow sufficiently the I-V behavior of the measurement data. Therefore, we think it is reasonable to apply parameter modeling mentioned above to simulate nanopore structure. The key idea is to modify electron affinity of silicon which is used to mimic the KCl solution to avoid band bending and depletion inside the nanopore. We could efficiently utilize conventional 3-D simulation tool to simulate the I-V behavior of nanopore structures. PMID:22966538

  17. Using the symmetries in 3D Smoothed Particle Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Cruz-Pérez, Juan P.; González, José A.

    2011-10-01

    We apply the cartoon SPH technique to solve numerically the Newtonian Euler's equations in scenarios with spherical symmetry with the standard Smoothed Particle Hydrodynamics method, using the equations written in cartesian coordinates. This implementation allow us to increase the resolution of the simulations in order to obtain accurate results. We test it using the Shock tube and the isothermal collapse of a perfect fluid in spherical symmetry.

  18. Fast 3D stereo flood simulations in urban areas

    NASA Astrophysics Data System (ADS)

    Hoes, O.; de Haan, G.; Stelling, G.; van Leeuwen, E.; van Dam, A.; Pleumeekers, O.; Schuurmans, W.

    2012-04-01

    Flood propagation models are essential to study floods as it is problematic to collect data during actual floods. Moreover, models are needed to explore the consequences of additional scenarios above the actual flood itself. The results of these model studies are generally graphs with water levels over time for certain locations or maps with the flood extent in an area for different return periods. A main difficulty with these depictions of flood information is that they do not reflect the seriousness of flood impacts well in terms of life-like human experience. Typically, one needs a (near) flood before measures are implemented. Apparently, a graph or map is not the proper material to convince politicians and policy makers, even if they live in the threatened area. The recent introduction of commercially available 3D stereo projectors and high resolution elevation data make it possible to build life-like visualizations of simulations. In our research we explored using 3D stereo, the recently collected elevation data of the Netherlands (20 laser points per m2!) in combination with aerial photographs, and a new fast 2D flood propagation calculation scheme. This scheme (under construction) is able to simulate floods using such high amounts of data points. The model simulates flood propagation on an irregular grid; at locations with large elevation differences (e.g. in urban areas) and fast flowing water, smaller cells are used compared to flat surfaces where the water is not or hardly flowing. The result of our combination is a very detailed flood simulation model that can be used to simulate floods within a fraction of the current calculation time. The opportunities of models and their results increase enormously with fast calculations and visualizations combined. For example, the model allows on the spot exploration of measures during a flood, with the 3D visualization ensuring that flood impacts become clear for decision makers. We will show the preliminary

  19. Automated 3D trajectory measuring of large numbers of moving particles.

    PubMed

    Wu, Hai Shan; Zhao, Qi; Zou, Danping; Chen, Yan Qiu

    2011-04-11

    Complex dynamics of natural particle systems, such as insect swarms, bird flocks, fish schools, has attracted great attention of scientists for years. Measuring 3D trajectory of each individual in a group is vital for quantitative study of their dynamic properties, yet such empirical data is rare mainly due to the challenges of maintaining the identities of large numbers of individuals with similar visual features and frequent occlusions. We here present an automatic and efficient algorithm to track 3D motion trajectories of large numbers of moving particles using two video cameras. Our method solves this problem by formulating it as three linear assignment problems (LAP). For each video sequence, the first LAP obtains 2D tracks of moving targets and is able to maintain target identities in the presence of occlusions; the second one matches the visually similar targets across two views via a novel technique named maximum epipolar co-motion length (MECL), which is not only able to effectively reduce matching ambiguity but also further diminish the influence of frequent occlusions; the last one links 3D track segments into complete trajectories via computing a globally optimal assignment based on temporal and kinematic cues. Experiment results on simulated particle swarms with various particle densities validated the accuracy and robustness of the proposed method. As real-world case, our method successfully acquired 3D flight paths of fruit fly (Drosophila melanogaster) group comprising hundreds of freely flying individuals. PMID:21503074

  20. Novel Discrete Element Method for 3D non-spherical granular particles.

    NASA Astrophysics Data System (ADS)

    Seelen, Luuk; Padding, Johan; Kuipers, Hans

    2015-11-01

    Granular materials are common in many industries and nature. The different properties from solid behavior to fluid like behavior are well known but less well understood. The main aim of our work is to develop a discrete element method (DEM) to simulate non-spherical granular particles. The non-spherical shape of particles is important, as it controls the behavior of the granular materials in many situations, such as static systems of packed particles. In such systems the packing fraction is determined by the particle shape. We developed a novel 3D discrete element method that simulates the particle-particle interactions for a wide variety of shapes. The model can simulate quadratic shapes such as spheres, ellipsoids, cylinders. More importantly, any convex polyhedron can be used as a granular particle shape. These polyhedrons are very well suited to represent non-rounded sand particles. The main difficulty of any non-spherical DEM is the determination of particle-particle overlap. Our model uses two iterative geometric algorithms to determine the overlap. The algorithms are robust and can also determine multiple contact points which can occur for these shapes. With this method we are able to study different applications such as the discharging of a hopper or silo. Another application the creation of a random close packing, to determine the solid volume fraction as a function of the particle shape.

  1. Comparative visual analysis of 3D urban wind simulations

    NASA Astrophysics Data System (ADS)

    Röber, Niklas; Salim, Mohamed; Grawe, David; Leitl, Bernd; Böttinger, Michael; Schlünzen, Heinke

    2016-04-01

    Climate simulations are conducted in large quantity for a variety of different applications. Many of these simulations focus on global developments and study the Earth's climate system using a coupled atmosphere ocean model. Other simulations are performed on much smaller regional scales, to study very small fine grained climatic effects. These microscale climate simulations pose similar, yet also different, challenges for the visualization and the analysis of the simulation data. Modern interactive visualization and data analysis techniques are very powerful tools to assist the researcher in answering and communicating complex research questions. This presentation discusses comparative visualization for several different wind simulations, which were created using the microscale climate model MITRAS. The simulations differ in wind direction and speed, but are all centered on the same simulation domain: An area of Hamburg-Wilhelmsburg that hosted the IGA/IBA exhibition in 2013. The experiments contain a scenario case to analyze the effects of single buildings, as well as examine the impact of the Coriolis force within the simulation. The scenario case is additionally compared with real measurements from a wind tunnel experiment to ascertain the accuracy of the simulation and the model itself. We also compare different approaches for tree modeling and evaluate the stability of the model. In this presentation, we describe not only our workflow to efficiently and effectively visualize microscale climate simulation data using common 3D visualization and data analysis techniques, but also discuss how to compare variations of a simulation and how to highlight the subtle differences in between them. For the visualizations we use a range of different 3D tools that feature techniques for statistical data analysis, data selection, as well as linking and brushing.

  2. DREAM3D simulations of inner-belt dynamics

    SciTech Connect

    Cunningham, Gregory Scott

    2015-05-26

    A 1973 paper by Lyons and Thorne explains the two-belt structure for electrons in the inner magnetosphere as a balance between inward radial diffusion and loss to the atmosphere, where the loss to the atmosphere is enabled by pitch-angle scattering from Coulomb and wave-particle interactions. In the 1973 paper, equilibrium solutions to a decoupled set of 1D radial diffusion equations, one for each value of the first invariant of motion, μ, were computed to produce the equilibrium two-belt structure. Each 1D radial diffusion equation incorporated an L-and μ-dependent `lifetime' due to the Coulomb and wave-particle interactions. This decoupling of the problem is appropriate under the assumption that radial diffusion is slow in comparison to pitch-angle scattering. However, for some values of μ and L the lifetime associated with pitch-angle scattering is comparable to the timescale associated with radial diffusion, suggesting that the true equilibrium solutions might reflect `coupled modes' involving pitch-angle scattering and radial diffusion and thus requiring a 3D diffusion model. In the work we show here, we have computed the equilibrium solutions using our 3D diffusion model, DREAM3D, that allows for such coupling. We find that the 3D equilibrium solutions are quite similar to the solutions shown in the 1973 paper when we use the same physical models for radial diffusion and pitch-angle scattering from hiss. However, we show that the equilibrium solutions are quite sensitive to various aspects of the physics model employed in the 1973 paper that can be improved, suggesting that additional work needs to be done to understand the two-belt structure.

  3. 3D Smoothed Particle Hydrodynamics Models of Betelgeuse's Bow Shock

    NASA Astrophysics Data System (ADS)

    Mohamed, S.; Mackey, J.; Langer, N.

    2013-05-01

    Betelgeuse, the bright red supergiant (RSG) in Orion, is a runaway star. Its supersonic motion through the interstellar medium has resulted in the formation of a bow shock, a cometary structure pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse's bow shock. We show that the bow shock morphology depends substantially on the growth timescale for Rayleigh-Taylor versus Kelvin-Helmholtz instabilities. We discuss our models in light of the recent Herschel, GALEX and VLA observations. If the mass in the bow shock shell is low (~few × 10-3 M⊙), as seems to be implied by the AKARI and Herschel observations, then Betelgeuse's bow shock is very young and is unlikely to have reached a steady state. The circular, smooth bow shock shell is consistent with this conclusion. We further discuss the implications of our results, in particular, the possibility that Betelgeuse may have only recently entered the RSG phase.

  4. 3D simulation of the Cluster-Cluster Aggregation model

    NASA Astrophysics Data System (ADS)

    Li, Chao; Xiong, Hailing

    2014-12-01

    We write a program to implement the Cluster-Cluster Aggregation (CCA) model with java programming language. By using the simulation program, the fractal aggregation growth process can be displayed dynamically in the form of a three-dimensional (3D) figure. Meanwhile, the related kinetics data of aggregation simulation can be also recorded dynamically. Compared to the traditional programs, the program has better real-time performance and is more helpful to observe the fractal growth process, which contributes to the scientific study in fractal aggregation. Besides, because of adopting java programming language, the program has very good cross-platform performance.

  5. 3D Simulation of External Flooding Events for the RISMC Pathway

    SciTech Connect

    Prescott, Steven; Mandelli, Diego; Sampath, Ramprasad; Smith, Curtis; Lin, Linyu

    2015-09-01

    Incorporating 3D simulations as part of the Risk-Informed Safety Margins Characterization (RISMIC) Toolkit allows analysts to obtain a more complete picture of complex system behavior for events including external plant hazards. External events such as flooding have become more important recently – however these can be analyzed with existing and validated simulated physics toolkits. In this report, we describe these approaches specific to flooding-based analysis using an approach called Smoothed Particle Hydrodynamics. The theory, validation, and example applications of the 3D flooding simulation are described. Integrating these 3D simulation methods into computational risk analysis provides a spatial/visual aspect to the design, improves the realism of results, and can prove visual understanding to validate the analysis of flooding.

  6. Virtual environment display for a 3D audio room simulation

    NASA Technical Reports Server (NTRS)

    Chapin, William L.; Foster, Scott H.

    1992-01-01

    The development of a virtual environment simulation system integrating a 3D acoustic audio model with an immersive 3D visual scene is discussed. The system complements the acoustic model and is specified to: allow the listener to freely move about the space, a room of manipulable size, shape, and audio character, while interactively relocating the sound sources; reinforce the listener's feeling of telepresence in the acoustical environment with visual and proprioceptive sensations; enhance the audio with the graphic and interactive components, rather than overwhelm or reduce it; and serve as a research testbed and technology transfer demonstration. The hardware/software design of two demonstration systems, one installed and one portable, are discussed through the development of four iterative configurations.

  7. 3D-CANVENT: An interactive mine ventilation simulator

    SciTech Connect

    Hardcastle, S.G.

    1995-12-31

    3D-CANVENT is a software package that integrates advanced computer aided design (ACAD) true 3D graphics with a mine ventilation simulator. The package runs as a Windows{trademark} application to access its printer drivers environment and does not need third party CAD software. It is composed of two primary modules: DMVENT and MINEDESIGNER. DMVENT is a traditional Fortran coded Hardy-Cross iterative ventilation network solver written in 1980 with thermodynamic capabilities. This module is relatively unchanged with the traditional data input options for branch type, specified or calculated resistances, fixed flows, and fixed or variable pressure fans. MINEDESIGNER is the graphics engine that optimizes the ventilation design process. It performs the front-end transformation of input data entered in the graphical interface into the correct format for the solver. At the back-end it reconverts the historically standard tabular data output from the solver into an easily viewed graphical format. ACAD features of MINEDESIGNER are used to generate a 3D wire-frame node and branch network of the mine`s ventilation system. The network can be displayed in up to 4 views orientated to XYZ planes or a 3D view. AU the views have zoom, pan, slice and rotate options. The graphical interface efficiently permits data entry and editing via a mouse with pick-and-point item selection. Branches can be found or added with {open_quotes}search{close_quotes} and {open_quotes}join{close_quotes} options. Visual interpretation is enhanced by the 16 colour options for branches and numerous graphical attributes. Network locations are readily identified by alpha-numeric names for branches, junctions and fans, and also the logical numbering of junctions. The program is also readily expandable for pollutant simulation and control/monitoring applications.

  8. Acoustic simulation in realistic 3D virtual scenes

    NASA Astrophysics Data System (ADS)

    Gozard, Patrick; Le Goff, Alain; Naz, Pierre; Cathala, Thierry; Latger, Jean

    2003-09-01

    The simulation workshop CHORALE developed in collaboration with OKTAL SE company for the French MoD is used by government services and industrial companies for weapon system validation and qualification trials in the infrared domain. The main operational reference for CHORALE is the assessment of the infrared guidance system of the Storm Shadow missile French version, called Scalp. The use of CHORALE workshop is now extended to the acoustic domain. The main objective is the simulation of the detection of moving vehicles in realistic 3D virtual scenes. This article briefly describes the acoustic model in CHORALE. The 3D scene is described by a set of polygons. Each polygon is characterized by its acoustic resistivity or its complex impedance. Sound sources are associated with moving vehicles and are characterized by their spectra and directivities. A microphone sensor is defined by its position, its frequency band and its sensitivity. The purpose of the acoustic simulation is to calculate the incoming acoustic pressure on microphone sensors. CHORALE is based on a generic ray tracing kernel. This kernel possesses original capabilities: computation time is nearly independent on the scene complexity, especially the number of polygons, databases are enhanced with precise physical data, special mechanisms of antialiasing have been developed that enable to manage very accurate details. The ray tracer takes into account the wave geometrical divergence and the atmospheric transmission. The sound wave refraction is simulated and rays cast in the 3D scene are curved according to air temperature gradient. Finally, sound diffraction by edges (hill, wall,...) is also taken into account.

  9. Using Delft3D to Simulate Current Energy Conversion

    NASA Astrophysics Data System (ADS)

    James, S. C.; Chartrand, C.; Roberts, J.

    2015-12-01

    As public concern with renewable energy increases, current energy conversion (CEC) technology is being developed to optimize energy output and minimize environmental impact. CEC turbines generate energy from tidal and current systems and create wakes that interact with turbines located downstream of a device. The placement of devices can greatly influence power generation and structural reliability. CECs can also alter the ecosystem process surrounding the turbines, such as flow regimes, sediment dynamics, and water quality. Software is needed to investigate specific CEC sites to simulate power generation and hydrodynamic responses of a flow through a CEC turbine array. This work validates Delft3D against several flume experiments by simulating the power generation and hydrodynamic response of flow through a turbine or actuator disc(s). Model parameters are then calibrated against these data sets to reproduce momentum removal and wake recovery data with 3-D flow simulations. Simulated wake profiles and turbulence intensities compare favorably to the experimental data and demonstrate the utility and accuracy of a fast-running tool for future siting and analysis of CEC arrays in complex domains.

  10. 3-D Imaging and Simulation for Nephron Sparing Surgical Training.

    PubMed

    Ahmadi, Hamed; Liu, Jen-Jane

    2016-08-01

    Minimally invasive partial nephrectomy (MIPN) is now considered the procedure of choice for small renal masses largely based on functional advantages over traditional open surgery. Lack of haptic feedback, the need for spatial understanding of tumor borders, and advanced operative techniques to minimize ischemia time or achieve zero-ischemia PN are among factors that make MIPN a technically demanding operation with a steep learning curve for inexperienced surgeons. Surgical simulation has emerged as a useful training adjunct in residency programs to facilitate the acquisition of these complex operative skills in the setting of restricted work hours and limited operating room time and autonomy. However, the majority of available surgical simulators focus on basic surgical skills, and procedure-specific simulation is needed for optimal surgical training. Advances in 3-dimensional (3-D) imaging have also enhanced the surgeon's ability to localize tumors intraoperatively. This article focuses on recent procedure-specific simulation models for laparoscopic and robotic-assisted PN and advanced 3-D imaging techniques as part of pre- and some cases, intraoperative surgical planning. PMID:27314271

  11. A Bayesian approach for suppression of limited angular sampling artifacts in single particle 3D reconstruction.

    PubMed

    Moriya, Toshio; Acar, Erman; Cheng, R Holland; Ruotsalainen, Ulla

    2015-09-01

    In the single particle reconstruction, the initial 3D structure often suffers from the limited angular sampling artifact. Selecting 2D class averages of particle images generally improves the accuracy and efficiency of the reference-free 3D angle estimation, but causes an insufficient angular sampling to fill the information of the target object in the 3D frequency space. Similarly, the initial 3D structure by the random-conical tilt reconstruction has the well-known "missing cone" artifact. Here, we attempted to solve the limited angular sampling problem by sequentially applying maximum a posteriori estimate with expectation maximization algorithm (sMAP-EM). Using both simulated and experimental cryo-electron microscope images, the sMAP-EM was compared to the direct Fourier method on the basis of reconstruction error and resolution. To establish selection criteria of the final regularization weight for the sMAP-EM, the effects of noise level and sampling sparseness on the reconstructions were examined with evenly distributed sampling simulations. The frequency information filled in the missing cone of the conical tilt sampling simulations was assessed by developing new quantitative measurements. All the results of visual and numerical evaluations showed the sMAP-EM performed better than the direct Fourier method, regardless of the sampling method, noise level, and sampling sparseness. Furthermore, the frequency domain analysis demonstrated that the sMAP-EM can fill the meaningful information in the unmeasured angular space without detailed a priori knowledge of the objects. The current research demonstrated that the sMAP-EM has a high potential to facilitate the determination of 3D protein structures at near atomic-resolution. PMID:26193484

  12. 3D simulation of plant and living tissue superficial lesions

    NASA Astrophysics Data System (ADS)

    Bratchenko, Ivan A.; Sindyaeva, Alexandra R.; Zakharov, Valery P.

    2008-06-01

    The analytic schemes of calculated absorbed and scattered radiation spatial distribution in multilayer plant and living tissues and diagnostic of their physical state are presented. The correct realization of these tasks was obtained with 3D Monte Carlo simulation of optical radiation propagation through multiple scattering medium in TracePro environment. Analysis of simulation data was made by differential backscattering method, which allows to investigate general backscattered radiation dependences on optical and geometrical parameters of living tissue. It was shown that obtained results formed the basis for developing an algorithm of optical superficial inhomogeneous registration and spatial localization. Such diagnosis can be executed in tissues of any arbitrary surface structure. Designed scheme is intended to utilize in contactless macro diagnostics device. The same approach was used for simulation of optical spectra of healthy and diseased virtual leaves for plant tissue pathological changes revealing.

  13. 3-D simulations of solar and stellar convection and magnetoconvection

    NASA Astrophysics Data System (ADS)

    Nordlund, Å.; Stein, R. F.

    1990-05-01

    We present the key components of a 3-D code designed for simulating the hydrodynamics and magnetohydrodynamics of stellar atmospheres and envelopes. Some particular properties of the code are: (1) the ability to handle strong stratification (extensive simulations with bottom/top pressure ratios of 3×104 have been performed, and simulations with pressure ratios of 5×106 are being initiated); (2) a detailed treatment of the radiating surface; (3) a functional form of the subgrid-scale diffusion designed to minimize the influence on resolved motions; (4) boundary conditions open to flows. The top boundary allows the transmission of short period waves, while the bottom boundary condition was designed to enforce a displacement node for radial pressure modes.

  14. Unstructured 3D grid toolbox for modeling and simulation

    SciTech Connect

    George, D.

    1997-11-01

    Computable 3D grids that accurately represent complex multimaterial geometries are essential for both static and time-dependent modeling and simulation. LaGriT, the grid toolbox developed at Los Alamos provides a sophisticated set of initial grid generation, grid maintenance and grid optimization tools. We present example grids that demonstrate the flexibility of the grid generator. Additionally, we present the results of an electrostatic calculation and a grain growth problem that illustrate the grid optimization features and the utility of the grid server architecture.

  15. Numerical simulation of vortex breakdown via 3-D Euler equations

    NASA Astrophysics Data System (ADS)

    Le, T. H.; Mege, P.; Morchoisne, Y.

    1990-06-01

    The long term goal is the modeling of vortex breakdown that occurs in some aerodynamic configurations at high angle of attack, (i.e., fighters with highly swept delta wings or missiles). A numerical simulation was made based on solving the 3-D Euler equations for an usteady incompressible flow. Preliminary results were obtained using a pressure-velocity formulation with periodic boundary conditions, the Euler equations being discretized by 2nd order finite difference schemes. The continuation to this work by implementing more realistic boundary conditions and 4th order finite difference discretization schemes are presented.

  16. Finite-element 3D simulation tools for high-current relativistic electron beams

    NASA Astrophysics Data System (ADS)

    Humphries, Stanley; Ekdahl, Carl

    2002-08-01

    The DARHT second-axis injector is a challenge for computer simulations. Electrons are subject to strong beam-generated forces. The fields are fully three-dimensional and accurate calculations at surfaces are critical. We describe methods applied in OmniTrak, a 3D finite-element code suite that can address DARHT and the full range of charged-particle devices. The system handles mesh generation, electrostatics, magnetostatics and self-consistent particle orbits. The MetaMesh program generates meshes of conformal hexahedrons to fit any user geometry. The code has the unique ability to create structured conformal meshes with cubic logic. Organized meshes offer advantages in speed and memory utilization in the orbit and field solutions. OmniTrak is a versatile charged-particle code that handles 3D electric and magnetic field solutions on independent meshes. The program can update both 3D field solutions from the calculated beam space-charge and current-density. We shall describe numerical methods for orbit tracking on a hexahedron mesh. Topics include: 1) identification of elements along the particle trajectory, 2) fast searches and adaptive field calculations, 3) interpolation methods to terminate orbits on material surfaces, 4) automatic particle generation on multiple emission surfaces to model space-charge-limited emission and field emission, 5) flexible Child law algorithms, 6) implementation of the dual potential model for 3D magnetostatics, and 7) assignment of charge and current from model particle orbits for self-consistent fields.

  17. 3D measurement of the position of gold particles via evanescent digital holographic particle tracking velocimetry

    NASA Astrophysics Data System (ADS)

    Satake, Shin-ichi; Unno, Noriyuki; Nakata, Shuichiro; Taniguchi, Jun

    2016-08-01

    A new technique based on digital holography and evanescent waves was developed for 3D measurements of the position of gold nanoparticles in water. In this technique, an intensity profile is taken from a holographic image of a gold particle. To detect the position of the gold particle with high accuracy, its holographic image is recorded on a nanosized step made of MEXFLON, which has a refractive index close to that of water, and the position of the particle is reconstructed by means of digital holography. The height of the nanosized step was measured by using a profilometer and the digitally reconstructed height of the glass substrate had good agreement with the measured value. Furthermore, this method can be used to accurately track the 3D position of a gold particle in water.

  18. Advanced system for 3D dental anatomy reconstruction and 3D tooth movement simulation during orthodontic treatment

    NASA Astrophysics Data System (ADS)

    Monserrat, Carlos; Alcaniz-Raya, Mariano L.; Juan, M. Carmen; Grau Colomer, Vincente; Albalat, Salvador E.

    1997-05-01

    This paper describes a new method for 3D orthodontics treatment simulation developed for an orthodontics planning system (MAGALLANES). We develop an original system for 3D capturing and reconstruction of dental anatomy that avoid use of dental casts in orthodontic treatments. Two original techniques are presented, one direct in which data are acquired directly form patient's mouth by mean of low cost 3D digitizers, and one mixed in which data are obtained by 3D digitizing of hydrocollids molds. FOr this purpose we have designed and manufactured an optimized optical measuring system based on laser structured light. We apply these 3D dental models to simulate 3D movement of teeth, including rotations, during orthodontic treatment. The proposed algorithms enable to quantify the effect of orthodontic appliance on tooth movement. The developed techniques has been integrated in a system named MAGALLANES. This original system present several tools for 3D simulation and planning of orthodontic treatments. The prototype system has been tested in several orthodontic clinic with very good results.

  19. 3D FEM Simulation of Flank Wear in Turning

    NASA Astrophysics Data System (ADS)

    Attanasio, Aldo; Ceretti, Elisabetta; Giardini, Claudio

    2011-05-01

    This work deals with tool wear simulation. Studying the influence of tool wear on tool life, tool substitution policy and influence on final part quality, surface integrity, cutting forces and power consumption it is important to reduce the global process costs. Adhesion, abrasion, erosion, diffusion, corrosion and fracture are some of the phenomena responsible of the tool wear depending on the selected cutting parameters: cutting velocity, feed rate, depth of cut, …. In some cases these wear mechanisms are described by analytical models as a function of process variables (temperature, pressure and sliding velocity along the cutting surface). These analytical models are suitable to be implemented in FEM codes and they can be utilized to simulate the tool wear. In the present paper a commercial 3D FEM software has been customized to simulate the tool wear during turning operations when cutting AISI 1045 carbon steel with uncoated tungsten carbide tip. The FEM software was improved by means of a suitable subroutine able to modify the tool geometry on the basis of the estimated tool wear as the simulation goes on. Since for the considered couple of tool-workpiece material the main phenomena generating wear are the abrasive and the diffusive ones, the tool wear model implemented into the subroutine was obtained as combination between the Usui's and the Takeyama and Murata's models. A comparison between experimental and simulated flank tool wear curves is reported demonstrating that it is possible to simulate the tool wear development.

  20. Simulation of 3D Global Wave Propagation Through Geodynamic Models

    NASA Astrophysics Data System (ADS)

    Schuberth, B.; Piazzoni, A.; Bunge, H.; Igel, H.; Steinle-Neumann, G.

    2005-12-01

    This project aims at a better understanding of the forward problem of global 3D wave propagation. We use the spectral element program "SPECFEM3D" (Komatitsch and Tromp, 2002a,b) with varying input models of seismic velocities derived from mantle convection simulations (Bunge et al., 2002). The purpose of this approach is to obtain seismic velocity models independently from seismological studies. In this way one can test the effects of varying parameters of the mantle convection models on the seismic wave field. In order to obtain the seismic velocities from the temperature field of the geodynamical simulations we follow a mineral physics approach. Assuming a certain mantle composition (e.g. pyrolite with CMASF composition) we compute the stable phases for each depth (i.e. pressure) and temperature by system Gibbs free energy minimization. Elastic moduli and density are calculated from the equations of state of the stable mineral phases. For this we use a mineral physics database derived from calorimetric experiments (enthalphy and entropy of formation, heat capacity) and EOS parameters.

  1. Code System to Simulate 3D Tracer Dispersion in Atmosphere.

    Energy Science and Technology Software Center (ESTSC)

    2002-01-25

    Version 00 SHREDI is a shielding code system which executes removal-diffusion computations for bi-dimensional shields in r-z or x-y geometries. It may also deal with monodimensional problems (infinitely high cylinders or slabs). MESYST can simulate 3D tracer dispersion in the atmosphere. Three programs are part of this system: CRE_TOPO prepares the terrain data for MESYST. NOABL calculates three-dimensional free divergence windfields over complex terrain. PAS computes tracer concentrations and depositions on a given domain. Themore » purpose of this work is to develop a reliable simulation tool for pollutant atmospheric dispersion, which gives a realistic approach and allows one to compute the pollutant concentrations over complex terrains with good accuracy. The factional brownian model, which furnishes more accurate concentration values, is introduced to calculate pollutant atmospheric dispersion. The model was validated on SIESTA international experiments.« less

  2. Coniferous Canopy BRF Simulation Based on 3-D Realistic Scene

    NASA Technical Reports Server (NTRS)

    Wang, Xin-yun; Guo, Zhi-feng; Qin, Wen-han; Sun, Guo-qing

    2011-01-01

    It is difficulties for the computer simulation method to study radiation regime at large-scale. Simplified coniferous model was investigate d in the present study. It makes the computer simulation methods such as L-systems and radiosity-graphics combined method (RGM) more powerf ul in remote sensing of heterogeneous coniferous forests over a large -scale region. L-systems is applied to render 3-D coniferous forest scenarios: and RGM model was used to calculate BRF (bidirectional refle ctance factor) in visible and near-infrared regions. Results in this study show that in most cases both agreed well. Meanwhiie at a tree and forest level. the results are also good.

  3. GBS: Global 3D simulation of tokamak edge region

    NASA Astrophysics Data System (ADS)

    Zhu, Ben; Fisher, Dustin; Rogers, Barrett; Ricci, Paolo

    2012-10-01

    A 3D two-fluid global code, namely Global Braginskii Solver (GBS), is being developed to explore the physics of turbulent transport, confinement, self-consistent profile formation, pedestal scaling and related phenomena in the edge region of tokamaks. Aimed at solving drift-reduced Braginskii equations [1] in complex magnetic geometry, the GBS is used for turbulence simulation in SOL region. In the recent upgrade, the simulation domain is expanded into close flux region with twist-shift boundary conditions. Hence, the new GBS code is able to explore global transport physics in an annular full-torus domain from the top of the pedestal into the far SOL. We are in the process of identifying and analyzing the linear and nonlinear instabilities in the system using the new GBS code. Preliminary results will be presented and compared with other codes if possible.[4pt] [1] A. Zeiler, J. F. Drake and B. Rogers, Phys. Plasmas 4, 2134 (1997)

  4. Coniferous canopy BRF simulation based on 3-D realistic scene.

    PubMed

    Wang, Xin-Yun; Guo, Zhi-Feng; Qin, Wen-Han; Sun, Guo-Qing

    2011-09-01

    It is difficulties for the computer simulation method to study radiation regime at large-scale. Simplified coniferous model was investigated in the present study. It makes the computer simulation methods such as L-systems and radiosity-graphics combined method (RGM) more powerful in remote sensing of heterogeneous coniferous forests over a large-scale region. L-systems is applied to render 3-D coniferous forest scenarios, and RGM model was used to calculate BRF (bidirectional reflectance factor) in visible and near-infrared regions. Results in this study show that in most cases both agreed well. Meanwhile at a tree and forest level, the results are also good. PMID:22097856

  5. A Parallelized 3D Particle-In-Cell Method With Magnetostatic Field Solver And Its Applications

    NASA Astrophysics Data System (ADS)

    Hsu, Kuo-Hsien; Chen, Yen-Sen; Wu, Men-Zan Bill; Wu, Jong-Shinn

    2008-10-01

    A parallelized 3D self-consistent electrostatic particle-in-cell finite element (PIC-FEM) code using an unstructured tetrahedral mesh was developed. For simulating some applications with external permanent magnet set, the distribution of the magnetostatic field usually also need to be considered and determined accurately. In this paper, we will firstly present the development of a 3D magnetostatic field solver with an unstructured mesh for the flexibility of modeling objects with complex geometry. The vector Poisson equation for magnetostatic field is formulated using the Galerkin nodal finite element method and the resulting matrix is solved by parallel conjugate gradient method. A parallel adaptive mesh refinement module is coupled to this solver for better resolution. Completed solver is then verified by simulating a permanent magnet array with results comparable to previous experimental observations and simulations. By taking the advantage of the same unstructured grid format of this solver, the developed PIC-FEM code could directly and easily read the magnetostatic field for particle simulation. In the upcoming conference, magnetron is simulated and presented for demonstrating the capability of this code.

  6. Physics and 3D in Flash Simulations: Open Source Reality

    NASA Astrophysics Data System (ADS)

    Harold, J. B.; Dusenbery, P.

    2009-12-01

    Over the last decade our ability to deliver simulations over the web has steadily advanced. The improvements in speed of the Adobe Flash engine, and the development of open source tools to expand it, allow us to deliver increasingly sophisticated simulation based games through the browser, with no additional downloads required. In this paper we will present activities we are developing as part of two asteroids education projects: Finding NEO (funded through NSF and NASA SMD), and Asteroids! (funded through NSF). The first activity is Rubble!, an asteroids deflection game built on the open source Box2D physics engine. This game challenges players to push asteroids in to safe orbits before they crash in to the Earth. The Box2D engine allows us to go well beyond simple 2-body orbital calculations and incorporate “rubble piles”. These objects, which are representative of many asteroids, are composed of 50 or more individual rocks which gravitationally bind and separate in realistic ways. Even bombs can be modeled with sufficient physical accuracy to convince players of the hazards of trying to “blow up” incoming asteroids. The ability to easily build games based on underlying physical models allows us to address physical misconceptions in a natural way: by having the player operate in a world that directly collides with those misconceptions. Rubble! provides a particularly compelling example of this due to the variety of well documented misconceptions regarding gravity. The second activity is a Light Curve challenge, which uses the open source PaperVision3D tools to analyze 3D asteroid models. The goal of this activity is to introduce the player to the concept of “light curves”, measurements of asteroid brightness over time which are used to calculate the asteroid’s period. These measurements can even be inverted to generate three dimensional models of asteroids that are otherwise too small and distant to directly image. Through the use of the Paper

  7. Spacecraft charging analysis with the implicit particle-in-cell code iPic3D

    SciTech Connect

    Deca, J.; Lapenta, G.; Marchand, R.; Markidis, S.

    2013-10-15

    We present the first results on the analysis of spacecraft charging with the implicit particle-in-cell code iPic3D, designed for running on massively parallel supercomputers. The numerical algorithm is presented, highlighting the implementation of the electrostatic solver and the immersed boundary algorithm; the latter which creates the possibility to handle complex spacecraft geometries. As a first step in the verification process, a comparison is made between the floating potential obtained with iPic3D and with Orbital Motion Limited theory for a spherical particle in a uniform stationary plasma. Second, the numerical model is verified for a CubeSat benchmark by comparing simulation results with those of PTetra for space environment conditions with increasing levels of complexity. In particular, we consider spacecraft charging from plasma particle collection, photoelectron and secondary electron emission. The influence of a background magnetic field on the floating potential profile near the spacecraft is also considered. Although the numerical approaches in iPic3D and PTetra are rather different, good agreement is found between the two models, raising the level of confidence in both codes to predict and evaluate the complex plasma environment around spacecraft.

  8. Optimizing prostate needle biopsy through 3D simulation

    NASA Astrophysics Data System (ADS)

    Zeng, Jianchao; Kaplan, Charles; Xuan, Jian Hua; Sesterhenn, Isabell A.; Lynch, John H.; Freedman, Matthew T.; Mun, Seong K.

    1998-06-01

    Prostate needle biopsy is used for the detection of prostate cancer. The protocol of needle biopsy that is currently routinely used in the clinical environment is the systematic sextant technique, which defines six symmetric locations on the prostate surface for needle insertion. However, this protocol has been developed based on the long-term observation and experience of urologists. Little quantitative or scientific evidence supports the use of this biopsy technique. In this research, we aim at developing a statistically optimized new prostate needle biopsy protocol to improve the quality of diagnosis of prostate cancer. This new protocol will be developed by using a three-dimensional (3-D) computer- based probability map of prostate cancer. For this purpose, we have developed a computer-based 3-D visualization and simulation system with prostate models constructed from the digitized prostate specimens, in which the process of prostate needle biopsy can be simulated automatically by the computer. In this paper, we first develop an interactive biopsy simulation mode in the system, and evaluate the performance of the automatic biopsy simulation with the sextant biopsy protocol by comparing the results by the urologist using the interactive simulation mode with respect to 53 prostate models. This is required to confirm that the automatic simulation is accurate and reliable enough for the simulation with respect to a large number of prostate models. Then we compare the performance of the existing protocols using the automatic biopsy simulation system with respect to 107 prostate models, which will statistically identify if one protocol is better than another. Since the estimation of tumor volume is extremely important in determining the significance of a tumor and in deciding appropriate treatment methods, we further investigate correlation between the tumor volume and the positive core volume with 89 prostate models. This is done in order to develop a method to

  9. Coherent Vortex Simulations of 3D isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Goldstein, Daniel E.; Vasilyev, Oleg V.; Kevlahan, Nicholas K.-R.

    2006-11-01

    This is the first of three talks on the wavelet filter based dynamically adaptive eddy capturing computational methodology that unifies variable fidelity simulation approaches such as wavelet-based DNS, Coherent Vortex Simulation (CVS), and Stochastic Coherent Adaptive Large Eddy Simulation. The commonality of these approaches is their ability to identify and ``track" on an adaptive mesh energetic coherent vortical structures. In CVS the velocity field is decomposed into two orthogonal parts: a coherent, inhomogeneous, non-Gaussian component and an incoherent, homogeneous, Gaussian component. This separation of coherent and incoherent components is achieved by wavelet thresholding which can be viewed as a non-linear filter that depends on each flow realization. The essence of the CVS approach is to solve for the coherent non-Gaussian component of a turbulent flow field. It has been shown previously that second generation bi-orthogonal wavelet threshold filtering is able to decompose a turbulent velocity field such that the total resulting SGS dissipation is approximately zero. This physically allows a CVS simulation to recover low order statistics with no SGS model. In this work CVS simulations of decaying incompressible 3D isotropic turbulence are compared to DNS results. -6pt

  10. Simulated Photoevaporative Mass Loss from Hot Jupiters in 3D

    NASA Astrophysics Data System (ADS)

    Tripathi, Anjali; Kratter, Kaitlin M.; Murray-Clay, Ruth A.; Krumholz, Mark R.

    2015-08-01

    Ionizing stellar photons heat the upper regions of planetary atmospheres, driving atmospheric mass loss. Gas escaping from several hot, hydrogen-rich planets has been detected using UV and X-ray transmission spectroscopy. Because these planets are tidally locked, and thus asymmetrically irradiated, escaping gas is unlikely to be spherically symmetric. In this paper, we focus on the effects of asymmetric heating on local outflow structure. We use the Athena code for hydrodynamics to produce 3D simulations of hot Jupiter mass loss that jointly model wind launching and stellar heating via photoionization. Our fiducial planet is an inflated, hot Jupiter with radius {R}{{p}}=2.14{R}{Jup} and mass {M}{{p}}=0.53{M}{Jup}. We irradiate the initially neutral, atomic hydrogen atmosphere with 13.6 eV photons and compute the outflow’s ionization structure. There are clear asymmetries in the atmospheric outflow, including a neutral shadow on the planet’s nightside. Given an incident ionizing UV flux comparable to that of the Sun, we find a steady-state mass loss rate of ˜ 2× {10}10 g s-1. The total mass loss rate and the outflow substructure along the substellar ray show good agreement with earlier 1D models, for two different fluxes. Our 3D data cube can be used to generate the outflow’s extinction spectrum during transit. As a proof of concept, we find absorption of stellar Lyα at Doppler-shifted velocities of up to ±50 km s-1. Our work provides a starting point for further 3D models that can be used to predict observable signatures of hot Jupiter mass loss.

  11. A 3D diamond detector for particle tracking

    NASA Astrophysics Data System (ADS)

    Artuso, M.; Bachmair, F.; Bäni, L.; Bartosik, M.; Beacham, J.; Bellini, V.; Belyaev, V.; Bentele, B.; Berdermann, E.; Bergonzo, P.; Bes, A.; Brom, J.-M.; Bruzzi, M.; Cerv, M.; Chau, C.; Chiodini, G.; Chren, D.; Cindro, V.; Claus, G.; Collot, J.; Costa, S.; Cumalat, J.; Dabrowski, A.; D`Alessandro, R.; de Boer, W.; Dehning, B.; Dobos, D.; Dünser, M.; Eremin, V.; Eusebi, R.; Forcolin, G.; Forneris, J.; Frais-Kölbl, H.; Gan, K. K.; Gastal, M.; Goffe, M.; Goldstein, J.; Golubev, A.; Gonella, L.; Gorišek, A.; Graber, L.; Grigoriev, E.; Grosse-Knetter, J.; Gui, B.; Guthoff, M.; Haughton, I.; Hidas, D.; Hits, D.; Hoeferkamp, M.; Hofmann, T.; Hosslet, J.; Hostachy, J.-Y.; Hügging, F.; Jansen, H.; Janssen, J.; Kagan, H.; Kanxheri, K.; Kasieczka, G.; Kass, R.; Kassel, F.; Kis, M.; Kramberger, G.; Kuleshov, S.; Lacoste, A.; Lagomarsino, S.; Lo Giudice, A.; Maazouzi, C.; Mandic, I.; Mathieu, C.; McFadden, N.; McGoldrick, G.; Menichelli, M.; Mikuž, M.; Morozzi, A.; Moss, J.; Mountain, R.; Murphy, S.; Oh, A.; Olivero, P.; Parrini, G.; Passeri, D.; Pauluzzi, M.; Pernegger, H.; Perrino, R.; Picollo, F.; Pomorski, M.; Potenza, R.; Quadt, A.; Re, A.; Riley, G.; Roe, S.; Sapinski, M.; Scaringella, M.; Schnetzer, S.; Schreiner, T.; Sciortino, S.; Scorzoni, A.; Seidel, S.; Servoli, L.; Sfyrla, A.; Shimchuk, G.; Smith, D. S.; Sopko, B.; Sopko, V.; Spagnolo, S.; Spanier, S.; Stenson, K.; Stone, R.; Sutera, C.; Taylor, A.; Traeger, M.; Tromson, D.; Trischuk, W.; Tuve, C.; Uplegger, L.; Velthuis, J.; Venturi, N.; Vittone, E.; Wagner, S.; Wallny, R.; Wang, J. C.; Weilhammer, P.; Weingarten, J.; Weiss, C.; Wengler, T.; Wermes, N.; Yamouni, M.; Zavrtanik, M.

    2016-07-01

    In the present study, results towards the development of a 3D diamond sensor are presented. Conductive channels are produced inside the sensor bulk using a femtosecond laser. This electrode geometry allows full charge collection even for low quality diamond sensors. Results from testbeam show that charge is collected by these electrodes. In order to understand the channel growth parameters, with the goal of producing low resistivity channels, the conductive channels produced with a different laser setup are evaluated by Raman spectroscopy.

  12. Study, simulation and design of a 3D clinostat

    NASA Astrophysics Data System (ADS)

    Pavone, Valentina; Guarnieri, Vincenzo; Lobascio, Cesare; Soma, Aurelio; Bosso, Nicola; Lamantea, Matteo Maria

    High cost and limited number of physically executable experiments in space have introduced the need for ground simulation systems that enable preparing experiments to be carried out on board, identifying phenomena associated with the altered gravity conditions, and taking advantage of these conditions, as in Biotechnology. Among systems developed to simulate microgravity, especially for life sciences experiments, different types of clinostats were realized. This work deals with mechanical design of a three-dimensional clinostat and simulation of the dynamic behavior of the system by varying the operating parameters. The design and simulation phase was preceded by a careful analysis of the state of art and by the review of the most recent results, in particular from the major investigators of Life Sciences in Space. The mechanical design is quite innovative by adoption of a structure entirely in aluminum, which allows robustness while reducing the overall weight. The transmission system of motion has been optimized by means of brushless DC micro motors, light and compact, which helped to reduce weight, dimensions, power consumption and increase the reliability and durability of the system. The study of the dynamic behavior using SIMPACK, a multibody simulation software, led to results in line with those found in the most important and recent scientific publications. This model was also appropriately configured to represent any desired operating condition, and for eventual system scalability. It would be interesting to generate simulated hypogravity - e.g.: 0.38-g (Mars) or 0.17-g (Moon). This would allow to investigate how terrestrial life forms can grow in other planetary habitats, or to determine the gravity threshold response of different organisms. At the moment, such a system can only be achieved by centrifuges in real microgravity. We are confident that simulation and associated tests with our 3D clinostat can help adjusting the parameters allowing variable g

  13. MPSalsa 3D Simulations of Chemically Reacting Flows

    DOE Data Explorer

    Many important scientific and engineering applications require a detailed analysis of complex systems with coupled fluid flow, thermal energy transfer, mass transfer and nonequilibrium chemical reactions. Currently, computer simulations of these complex reacting flow problems are limited to idealized systems in one or two spatial dimensions when coupled with a detailed, fundamental chemistry model. The goal of our research is to develop, analyze and implement advanced MP numerical algorithms that will allow high resolution 3D simulations with an equal emphasis on fluid flow and chemical kinetics modeling. In our research, we focus on the development of new, fully coupled, implicit solution strategies that are based on robust MP iterative solution methods (copied from http://www.cs.sandia.gov/CRF/MPSalsa/). These simulations are needed for scientific and technical areas such as: combustion research for transportation, atmospheric chemistry modeling for pollution studies, chemically reacting flow models for analysis and control of manufacturing processes, surface catalytic reactors for methane to methanol conversion and chemical vapor deposition (CVD) process modeling for production of advanced semiconductor materials (http://www.cs.sandia.gov/CRF/MPSalsa/).

    This project website provides six QuickTime videos of these simulations, along with a small image gallery and slideshow animations. A list of related publications and conference presentations is also made available.

  14. 3D Simulation Modeling of the Tooth Wear Process

    PubMed Central

    Dai, Ning; Hu, Jian; Liu, Hao

    2015-01-01

    Severe tooth wear is the most common non-caries dental disease, and it can seriously affect oral health. Studying the tooth wear process is time-consuming and difficult, and technological tools are frequently lacking. This paper presents a novel method of digital simulation modeling that represents a new way to study tooth wear. First, a feature extraction algorithm is used to obtain anatomical feature points of the tooth without attrition. Second, after the alignment of non-attrition areas, the initial homogeneous surface is generated by means of the RBF (Radial Basic Function) implicit surface and then deformed to the final homogeneous by the contraction and bounding algorithm. Finally, the method of bilinear interpolation based on Laplacian coordinates between tooth with attrition and without attrition is used to inversely reconstruct the sequence of changes of the 3D tooth morphology during gradual tooth wear process. This method can also be used to generate a process simulation of nonlinear tooth wear by means of fitting an attrition curve to the statistical data of attrition index in a certain region. The effectiveness and efficiency of the attrition simulation algorithm are verified through experimental simulation. PMID:26241942

  15. 3D Discrete Element Model with 1 Million Particles: an Example of Hydro-fracturing

    NASA Astrophysics Data System (ADS)

    Liu, C.; Pollard, D. D.

    2013-12-01

    The Discrete Element Method (DEM) permits large relative motion and breakage of elements, and does not require re-meshing, for example as would the Finite Element Method. DEM has a wide range of applications in the fields of solid-earth geophysics, geomechanics, mining engineering, and structural geology. However, due to the computational cost, particle numbers of discrete element models are generally less than a few tens of thousands, which limits the applications. A new 3D DEM system 'MatDEM' can complete dynamic simulations of one million particles. The conversion formulas between particle parameters and model mechanical properties were derived, and the conversion of energy in DEM can be simulated. In a recent paper (Liu et al., 2013, JGR), the analytical solutions of elastic properties and failure modes of a 2D close-packed discrete element model were proposed. Based on these theoretical results, it is easy to create materials using DEM, which have similar mechanical properties to rock. Given the mechanical properties and state of stress, geologists and engineers can investigate the characteristics of rock deformation and failure under different conditions. MatDEM provides an alternative way to study the micro-macro relationships of rock and soil, and the evolution of geologic structures. As an example, MatDEM was used to investigate the generation and development of fluid driven fractures around a micro pore. The simulation result of fractures of an anisotropic 3D model, which includes 1 million particles, is demonstrated. Via parallel computing technology, MatDEM may handle tens of millions of particles in near future. Left: Fluid pressure is applied in the pore to generate fractures. Right: Simulation results (black segments represent fractures).

  16. Three-dimensional parallel UNIPIC-3D code for simulations of high-power microwave devices

    NASA Astrophysics Data System (ADS)

    Wang, Jianguo; Chen, Zaigao; Wang, Yue; Zhang, Dianhui; Liu, Chunliang; Li, Yongdong; Wang, Hongguang; Qiao, Hailiang; Fu, Meiyan; Yuan, Yuan

    2010-07-01

    This paper introduces a self-developed, three-dimensional parallel fully electromagnetic particle simulation code UNIPIC-3D. In this code, the electromagnetic fields are updated using the second-order, finite-difference time-domain method, and the particles are moved using the relativistic Newton-Lorentz force equation. The electromagnetic field and particles are coupled through the current term in Maxwell's equations. Two numerical examples are used to verify the algorithms adopted in this code, numerical results agree well with theoretical ones. This code can be used to simulate the high-power microwave (HPM) devices, such as the relativistic backward wave oscillator, coaxial vircator, and magnetically insulated line oscillator, etc. UNIPIC-3D is written in the object-oriented C++ language and can be run on a variety of platforms including WINDOWS, LINUX, and UNIX. Users can use the graphical user's interface to create the complex geometric structures of the simulated HPM devices, which can be automatically meshed by UNIPIC-3D code. This code has a powerful postprocessor which can display the electric field, magnetic field, current, voltage, power, spectrum, momentum of particles, etc. For the sake of comparison, the results computed by using the two-and-a-half-dimensional UNIPIC code are also provided for the same parameters of HPM devices, the numerical results computed from these two codes agree well with each other.

  17. Colossal Tooling Design: 3D Simulation for Ergonomic Analysis

    NASA Technical Reports Server (NTRS)

    Hunter, Steve L.; Dischinger, Charles; Thomas, Robert E.; Babai, Majid

    2003-01-01

    The application of high-level 3D simulation software to the design phase of colossal mandrel tooling for composite aerospace fuel tanks was accomplished to discover and resolve safety and human engineering problems. The analyses were conducted to determine safety, ergonomic and human engineering aspects of the disassembly process of the fuel tank composite shell mandrel. Three-dimensional graphics high-level software, incorporating various ergonomic analysis algorithms, was utilized to determine if the process was within safety and health boundaries for the workers carrying out these tasks. In addition, the graphical software was extremely helpful in the identification of material handling equipment and devices for the mandrel tooling assembly/disassembly process.

  18. 3D Simulations of Supernovae into the Young Remnant Phase

    NASA Astrophysics Data System (ADS)

    Ellinger, Carola I.; Young, P. A.; Fryer, C.; Rockefeller, G.; Park, S.

    2013-01-01

    The explosion of massive stars as core-collapse supernovae is an inherently three dimensional phenomenon. Observations of the young, ejecta dominated remnants of those explosions unambiguously demonstrate that asymmetry on large and small scales is the rule, rather than the exception. Numerical models of supernova remnants connect the observed remnants to models of the exploding stellar system and thus facilitate both improved interpretations of the observations as well as improve our understanding of the explosion mechanism. We present first 3D simulations of core- collapse supernovae evolving into supernova remnants calculated with SNSPH. The calculations were started from 1D collapsed models of 2 progenitor stars of different types, and follow the explosion from revival of the shock wave to shock break out in 3D. Two different interstellar media, a cold neutral medium and a dense molecular cloud, as well as a red supergiant stellar wind profile, were added to the explosion calculations shortly before shock breakout, so that the blast wave stays in the simulation. With this setup we can follow the dispersal of the nucleosynthesis products from the explosion into the Sedov stage of the supernova remnant evolution starting from realistic initial conditions for the supernova ejecta. We will present a first investigation in the mixing between stellar and interstellar matter as the supernova evolves into the young supernova remnant phase, and contrasts differences that are observed between the scenarios that are investigated. One of the goals is to distinguish between features that arose in instabilities during the explosion from those that were created in the interaction with the surrounding medium.

  19. The Vajont disaster: a 3D numerical simulation for the slide and the waves

    NASA Astrophysics Data System (ADS)

    Rubino, Angelo; Androsov, Alexey; Vacondio, Renato; Zanchettin, Davide; Voltzinger, Naum

    2016-04-01

    A very high resolution O(5 m), 3D hydrostatic nonlinear numerical model was used to simulate the dynamics of both the slide and the surface waves produced during the Vajont disaster (north Italy, 1963), one of the major landslide-induced tsunamis ever documented. Different simulated wave phenomena like, e.g., maximum run-up on the opposite shore, maximum height, and water velocity were analyzed and compared with data available in literature, including the results of a fully 3D simulation obtained with a Smoothed Particle Hydrodynamic code. The difference between measured and simulated after-slide bathymetries was calculated and used in an attempt to quantify the relative magnitude and extension of rigid and fluid motion components during the event.

  20. PAB3D Simulations for the CAWAPI F-16XL

    NASA Technical Reports Server (NTRS)

    Elmiligui, Alaa; Abdol-Hamid, K. S.; Massey, Steven J.

    2007-01-01

    Numerical simulations of the flow around F-16XL are performed as a contribution to the Cranked Arrow Wing Aerodynamic Project International (CAWAPI) using the PAB3D CFD code. Two turbulence models are used in the calculations: a standard k-! model, and the Shih-Zhu-Lumley (SZL) algebraic stress model. Seven flight conditions are simulated for the flow around the F-16XL where the free stream Mach number varies from 0.242 to 0.97. The range of angles of attack varies from 0deg to 20deg. Computational results, surface static pressure, boundary layer velocity profiles, and skin friction are presented and compared with flight data. Numerical results are generally in good agreement with flight data, considering that only one grid resolution is utilized for the different flight conditions simulated in this study. The ASM results are closer to the flight data than the k-! model results. The ASM predicted a stronger primary vortex, however, the origin of the vortex and footprint is approximately the same as in the k-! predictions.

  1. 3D Dynamic Earthquake Fracture Simulation (Test Case)

    NASA Astrophysics Data System (ADS)

    Korkusuz Öztürk, Yasemin; Meral Özel, Nurcan; Ando, Ryosuke

    2016-04-01

    A 3D dynamic earthquake fracture simulation is being developed for the fault structures which are non-planar to understand heterogeneous stress states in the Marmara Sea. Locating in a seismic gap, a large earthquake is expected in the center of the Sea of Marmara. Concerning the fact that more than 14 million inhabitants of İstanbul, located very closely to the Marmara Sea, the importance of the analysis of the Central Marmara Sea is extremely high. A few 3D dynamic earthquake fracture studies have been already done in the Sea of Marmara for pure right lateral strike-slip stress regimes (Oglesby and Mai, 2012; Aochi and Ulrich, 2015). In this study, a 3D dynamic earthquake fracture model with heterogeneous stress patches from the TPV5, a SCEC code validation case, is adapted. In this test model, the fault and the ground surfaces are gridded by a scalene triangulation technique using GMSH program. For a grid size changing between 0.616 km and 1.050 km the number of elements for the fault surface is 1984 and for the ground surface is 1216. When these results are compared with Kaneko's results for TPV5 from SPECFEM3D, reliable findings could be observed for the first 6.5 seconds (stations on the fault) although a stability problem is encountered after this time threshold. To solve this problem grid sizes are made smaller, so the number of elements increase 7986 for the fault surface and 4867 for the ground surface. On the other hand, computational problems arise in that case, since the computation time is directly proportional to the number of total elements and the required memory also increases with the square of that. Therefore, it is expected that this method can be adapted for less coarse grid cases, regarding the main difficulty coming from the necessity of an effective supercomputer and run time limitations. The main objective of this research is to obtain 3D dynamic earthquake rupture scenarios, concerning not only planar and non-planar faults but also

  2. Freestanding 3D supramolecular particle bridges: fabrication and mechanical behavior.

    PubMed

    Ling, Xing Yi; Phang, In Yee; Schönherr, Holger; Reinhoudt, David N; Vancso, G Julius; Huskens, Jurriaan

    2009-06-01

    Freestanding particle bridges with controlled composition and macroscopic robustness are demonstrated by the use of supramolecular nanoparticle assembly. Self-assembly of nanoparticles, templating, and supramolecular glue infiltration are combined to form stable and ordered three-dimensional polystyrene particle composites on a polydimethylsiloxane stamp. Freestanding hybrid polystyrene nanoparticle bridges are obtained by transfer printing of the hybrid structures onto topographically patterned substrates via host-guest interactions. The mechanical robustness and rigidity of the particle bridges can be controlled by manipulating the layer-by-layer cycles of supramolecular glues of gold nanoparticles and dendrimers. Atomic force microscopy-based microbending results, in particular the location and force-dependent deflection behavior, confirm that the particle bridge fulfills the classical supported-beam characteristics. As estimated from classical beam theory, the bending moduli of the particle bridges vary between 0.8 and 1.1 GPa, depending on the degree of filling by the supramolecular glues. Failure analysis on the particle structure indicates linear elastic behavior and a plastic deformation upon failure. PMID:19373830

  3. Simulation of underwater explosion benchmark experiments with ALE3D

    SciTech Connect

    Couch, R.; Faux, D.

    1997-05-19

    Some code improvements have been made during the course of this study. One immediately obvious need was for more flexibility in the constitutive representation for materials in shell elements. To remedy this situation, a model with a tabular representation of stress versus strain and rate dependent effects was implemented. This was required in order to obtain reasonable results in the IED cylinder simulation. Another deficiency was in the ability to extract and plot variables associated with shell elements. The pipe whip analysis required the development of a scheme to tally and plot time dependent shell quantities such as stresses and strains. This capability had previously existed only for solid elements. Work was initiated to provide the same range of plotting capability for structural elements that exist with the DYNA3D/TAURUS tools. One of the characteristics of these problems is the disparity in zoning required in the vicinity of the charge and bubble compared to that needed in the far field. This disparity can cause the equipotential relaxation logic to provide a less than optimal solution. Various approaches were utilized to bias the relaxation to obtain more optimal meshing during relaxation. Extensions of these techniques have been developed to provide more powerful options, but more work still needs to be done. The results presented here are representative of what can be produced with an ALE code structured like ALE3D. They are not necessarily the best results that could have been obtained. More experience in assessing sensitivities to meshing and boundary conditions would be very useful. A number of code deficiencies discovered in the course of this work have been corrected and are available for any future investigations.

  4. Virtual environment display for a 3D audio room simulation

    NASA Astrophysics Data System (ADS)

    Chapin, William L.; Foster, Scott

    1992-06-01

    Recent developments in virtual 3D audio and synthetic aural environments have produced a complex acoustical room simulation. The acoustical simulation models a room with walls, ceiling, and floor of selected sound reflecting/absorbing characteristics and unlimited independent localizable sound sources. This non-visual acoustic simulation, implemented with 4 audio ConvolvotronsTM by Crystal River Engineering and coupled to the listener with a Poihemus IsotrakTM, tracking the listener's head position and orientation, and stereo headphones returning binaural sound, is quite compelling to most listeners with eyes closed. This immersive effect should be reinforced when properly integrated into a full, multi-sensory virtual environment presentation. This paper discusses the design of an interactive, visual virtual environment, complementing the acoustic model and specified to: 1) allow the listener to freely move about the space, a room of manipulable size, shape, and audio character, while interactively relocating the sound sources; 2) reinforce the listener's feeling of telepresence into the acoustical environment with visual and proprioceptive sensations; 3) enhance the audio with the graphic and interactive components, rather than overwhelm or reduce it; and 4) serve as a research testbed and technology transfer demonstration. The hardware/software design of two demonstration systems, one installed and one portable, are discussed through the development of four iterative configurations. The installed system implements a head-coupled, wide-angle, stereo-optic tracker/viewer and multi-computer simulation control. The portable demonstration system implements a head-mounted wide-angle, stereo-optic display, separate head and pointer electro-magnetic position trackers, a heterogeneous parallel graphics processing system, and object oriented C++ program code.

  5. 3-D Relativistic MHD Simulations of Extragalactic Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Sakai, J.-I.; Frank, J.; Christodoulou, D. M.; Sol, H.; Mutel, R. L.

    1997-12-01

    We present the numerical simulations of relativistic jets propagating initially oblique to the field lines of a magnetized ambient medium. Our simulations incorporate relativistic MHD in a four-dimensional spacetime and clearly show that (a) relatively weak, oblique fields (at 1/16 of the equipartition value) have only a negligible influence on the propagating jet and they are passively pushed away by the relativistically moving head; (b) oblique fields in equipartition with the ambient plasma provide more resistance and cause bending at the jet head, but the magnitude of this deflection and the associated backflow are small compared to those identified by previous studies with a 2-D slab model. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently during the simulations. The effect is analogous to pushing Japanese ``noren'' or vertical Venetian blinds out of the way while the slats are allowed to bend in 3-D space rather than as a 2-D slab structure. Applied to relativistic extragalactic jets from blazars, the new results are encouraging since superluminal outflows exhibit bending near their sources and their environments are profoundly magnetized---but observations do not provide support for irregular kinematics such as large-scale vortical motions and pronounced reverse flows near the points of origin.

  6. Online reconstruction of 3D magnetic particle imaging data

    NASA Astrophysics Data System (ADS)

    Knopp, T.; Hofmann, M.

    2016-06-01

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

  7. Online reconstruction of 3D magnetic particle imaging data.

    PubMed

    Knopp, T; Hofmann, M

    2016-06-01

    Magnetic particle imaging is a quantitative functional imaging technique that allows imaging of the spatial distribution of super-paramagnetic iron oxide particles at high temporal resolution. The raw data acquisition can be performed at frame rates of more than 40 volumes s(-1). However, to date image reconstruction is performed in an offline step and thus no direct feedback is available during the experiment. Considering potential interventional applications such direct feedback would be mandatory. In this work, an online reconstruction framework is implemented that allows direct visualization of the particle distribution on the screen of the acquisition computer with a latency of about 2 s. The reconstruction process is adaptive and performs block-averaging in order to optimize the signal quality for a given amount of reconstruction time. PMID:27182668

  8. 3D thermal modeling of TRISO fuel coupled with neutronic simulation

    SciTech Connect

    Hu, Jianwei; Uddin, Rizwan

    2010-01-01

    The Very High Temperature Gas Reactor (VHTR) is widely considered as one of the top candidates identified in the Next Generation Nuclear Power-plant (NGNP) Technology Roadmap under the U.S . Depanment of Energy's Generation IV program. TRlSO particle is a common element among different VHTR designs and its performance is critical to the safety and reliability of the whole reactor. A TRISO particle experiences complex thermo-mechanical changes during reactor operation in high temperature and high burnup conditions. TRISO fuel performance analysis requires evaluation of these changes on micro scale. Since most of these changes are temperature dependent, 3D thermal modeling of TRISO fuel is a crucial step of the whole analysis package. In this paper, a 3D numerical thermal model was developed to calculate temperature distribution inside TRISO and pebble under different scenarios. 3D simulation is required because pebbles or TRISOs are always subjected to asymmetric thermal conditions since they are randomly packed together. The numerical model was developed using finite difference method and it was benchmarked against ID analytical results and also results reported from literature. Monte-Carlo models were set up to calculate radial power density profile. Complex convective boundary condition was applied on the pebble outer surface. Three reactors were simulated using this model to calculate temperature distribution under different power levels. Two asymmetric boundary conditions were applied to the pebble to test the 3D capabilities. A gas bubble was hypothesized inside the TRISO kernel and 3D simulation was also carried out under this scenario. Intuition-coherent results were obtained and reported in this paper.

  9. Two new methods for simulating photolithography development in 3D

    SciTech Connect

    Helmsen, J.; Colella, P.; Dorr, M.; Puckett, E.G.

    1997-01-30

    Two methods are presented for simulating the development of photolithographic profiles during the resist dissolution phase. These algorithms are the volume-of-fluid algorithm, and the steady level-set algorithm. They are compared with the ray-trace, cell, and level-set techniques employed in SAMPLE-3D. The volume-of-fluid algorithm employs an Euclidean Grid with volume fractions. At each time step, the surface is reconstructed by computing an approximation of the tangent plane of the surface in each cell that contains a value between 0 and 1. The geometry constructed in this manner is used to determine flow velocity vectors and the flux across each edge. The material is then advanced by a split advection scheme. The steady Level Set algorithm is an extension of the Iterative Level Set algorithm. The steady Level Set algorithm combines Fast Level Set concepts and a technique for finding zero residual solutions to the ( ) function. The etch time for each cell is calculated in a time ordered manner. Use of heap sorting data structures allows the algorithm to execute extremely quickly. Comparisons of the methods have been performed and results shown.

  10. Simulations of soluble surfactants in 3D multiphase flow

    NASA Astrophysics Data System (ADS)

    Muradoglu, Metin; Tryggvason, Gretar

    2014-10-01

    A finite-difference/front-tracking method is developed for simulations of soluble surfactants in 3D multiphase flows. The interfacial and bulk surfactant concentration evolution equations are solved fully coupled with the incompressible Navier-Stokes equations. A non-linear equation of state is used to relate interfacial surface tension to surfactant concentration at the interface. Simple test cases are designed to validate different parts of the numerical algorithm and the computational results are found to be in a good agreement with the analytical solutions. The numerical algorithm is parallelized using a domain-decomposition method. It is then applied to study the effects of soluble surfactants on the motion of buoyancy-driven bubbles in a straight square channel in nearly undeformable (spherical) and deformable (ellipsoidal) regimes. Finally the method is used to examine the effects of soluble surfactants on the lateral migration of bubbles in a pressure-driven channel flow. It is found that surfactant-induced Marangoni stresses counteract the shear-induced lift force and can reverse the lateral bubble migration completely, i.e., the contaminated bubble drifts away from the channel wall and stabilizes at the center of the channel when the surfactant-induced Marangoni stresses are sufficiently large.

  11. 3-D simulation of posterior fossa reduction in Chiari I.

    PubMed

    Fernandes, Yvens Barbosa; Perestrelo, Pedro Fábio Mendonça; Noritomi, Pedro Yoshito; Mathias, Roger Neves; Silva, Jorge Vicente Lopes da; Joaquim, Andrei Fernandes

    2016-05-01

    We proposed a 3D model to evaluate the role of platybasia and clivus length in the development of Chiari I (CI). Using a computer aided design software, two DICOM files of a normal CT scan and MR were used to simulate different clivus lengths (CL) and also different basal angles (BA). The final posterior fossa volume (PFV) was obtained for each variation and the percentage of the volumetric change was acquired with the same method. The initial normal values of CL and BA were 35.65 mm and 112.66º respectively, with a total PFV of 209 ml. Ranging the CL from 34.65 to 29.65 - 24.65 - 19.65, there was a PFV decrease of 0.47% - 1.12% - 1.69%, respectively. Ranging the BA from 122.66º to 127.66º - 142.66º, the PFV decreased 0.69% - 3.23%, respectively. Our model highlights the importance of the basal angle and clivus length to the development of CI. PMID:27191237

  12. 3D finite element simulation of TIG weld pool

    NASA Astrophysics Data System (ADS)

    Kong, X.; Asserin, O.; Gounand, S.; Gilles, P.; Bergheau, J. M.; Medale, M.

    2012-07-01

    The aim of this paper is to propose a three-dimensional weld pool model for the moving gas tungsten arc welding (GTAW) process, in order to understand the main factors that limit the weld quality and improve the productivity, especially with respect to the welding speed. Simulation is a very powerful tool to help in understanding the physical phenomena in the weld process. A 3D finite element model of heat and fluid flow in weld pool considering free surface of the pool and traveling speed has been developed for the GTAW process. Cast3M software is used to compute all the governing equations. The free surface of the weld pool is calculated by minimizing the total surface energy. The combined effects of surface tension gradient, buoyancy force, arc pressure, arc drag force to drive the fluid flow is included in our model. The deformation of the weld pool surface and the welding speed affect fluid flow, heat flow and thus temperature gradients and molten pool dimensions. Welding trials study is presented to compare our numerical results with macrograph of the molten pool.

  13. Particle Acceleration in the Low Corona Over Broad Longitudes: Coupling Between 3D Magnetohydrodynamic and Energetic Particle Models

    NASA Astrophysics Data System (ADS)

    Gorby, M.; Schwadron, N.; Lee, M. A.; Booth, A. C.; Spence, H.; Torok, T.; Downs, C.; Lionello, R.; Linker, J.; Titov, V. S.; Mikic, Z.; Riley, P.; Desai, M. I.; Dayeh, M. A.; Kozarev, K. A.

    2013-12-01

    Recent work on the coupling between 3D energetic particle models (e.g., the Energetic Particle Radiation Environment Model, EPREM) and magnetohydrodynamic (MHD) models of Coronal Mass Ejections (CMEs, e.g., the PSI MAS model) has demonstrated the efficacy of compression regions in front of fast CMEs for particle acceleration from remarkably low in the corona (3-6 solar radii). Typically particle acceleration becomes rapid beyond 3Rs and often in regions where compression regions have not yet formed active shocks. The challenge for forming large SEP events in such compression-acceleration scenarios is to have enhanced scattering within the acceleration region while also allowing for efficient escape of accelerated particles downstream (away from the Sun) from the compression region. Simulations show rapid particle acceleration in the range of 3-8 Rs over a broad longitudinal region (80°) resulting from the pile-up of magnetic flux in the compression and the subsequent expansion of these fields. These results have important implications for multi-instrument observations that will allow Solar Probe Plus and Solar Orbiter to test the developing paradigm of SEP acceleration and transport from coronal compressions. We present here recent coupled simulations for SEP acceleration and transport, including energetic particle and CME plasma profiles. The broadness of the longitudinal profile from such events may be a key observational test of compression acceleration in the low corona.

  14. 3D MHD simulation of polarized emission in SN 1006

    NASA Astrophysics Data System (ADS)

    Schneiter, E. M.; Velázquez, P. F.; Reynoso, E. M.; Esquivel, A.; De Colle, F.

    2015-05-01

    We use three-dimensional magnetohydrodynamic simulations to model the supernova remnant SN 1006. From our numerical results, we have carried out a polarization study, obtaining synthetic maps of the polarized intensity, the Stokes parameter Q, and the polar-referenced angle, which can be compared with observational results. Synthetic maps were computed considering two possible particle acceleration mechanisms: quasi-parallel and quasi-perpendicular. The comparison of synthetic maps of the Stokes parameter Q maps with observations proves to be a valuable tool to discern unambiguously which mechanism is taking place in the remnant of SN 1006, giving strong support to the quasi-parallel model.

  15. Global gyrokinetic models for energetic particle driven Alfvén instabilities in 3D equilibria

    NASA Astrophysics Data System (ADS)

    Spong, Don; Holod, Ihor

    2015-11-01

    The GTC global gyrokinetic PIC model has been adapted to 3D VMEC equilibria and provides a new method for the analysis of Alfvénic instabilities in stellarators, 3D tokamaks, and helical RFP states. The gyrokinetic orderings (k||/k⊥ << 1, ω/Ωci << 1, ρEP/L << 1) are applicable to a range of energetic particle driven instabilities that have been observed in 3D configurations. Applications of this model to stellarators have indicated that a variety of different Alfvén instabilities can be excited, depending on the toroidal mode number, fast ion average energy and fast ion density profile. Both an LHD discharge where bursting n = 1 Alfvén activity in the TAE gap was observed and a W7-X case have been examined. TAE,/EAE/GAE modes have been found in the simulations, depending on the mode family and fast ion profiles used. The dynamical evolution of the instabilities shows the field period coupling between n and n + Nfp expected for a stellarator. The development of gyrofluid reduced models that can capture relevant physics aspects of the gyrokinetic models will also be discussed. Research sponsored by the U.S. Department of Energy under Contract DE-AC05-00OR22725 with UT-Battelle, LLC and the GSEP SciDAC Center.

  16. 3D Simulations of methane convective storms on Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sánchez-Lavega, A.

    2005-08-01

    The arrival of the Cassini/Huygens mission to Titan has opened an unprecedented opportunity to study the atmosphere of this satellite. Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe has shown a terrain shaped by erosion of probably liquid origin, suggestive of past rain. On the other hand, Voyager IRIS spectroscopic observations of Titan imply a saturated atmosphere of methane (amounting perhaps to 150 covered by methane clouds, if we think on Earth meteorology. However, observations from Earth and Cassini have shown that clouds are localized, transient and fast evolving, in particular in the South Pole (currently in its summer season). This might imply a lack of widespread presence on Titan of nuclei where methane could initiate condensation and particle growth with subsequent precipitation. We investigate different scenarios of moist convective storms on Titan using a complete 3D atmospheric model that incorporates a full microphysics treatment required to study cloud formation processes under a saturated atmosphere with low concentration of condensation nuclei. We study local convective development under a variety of atmospheric conditions: sub-saturation, super-saturation, abundances of condensation nuclei fall, condensation nuclei lifted from the ground or gently falling from the stratosphere. We show that under the appropriate circumstances, precipitation rates comparable to typical tropical storms on Earth can be found. Acknowledgements: This work has been funded by Spanish MCYT PNAYA2003-03216, fondos FEDER and Grupos UPV 15946/2004. R. Hueso acknowledges a post-doc fellowship from Gobierno Vasco.

  17. Parallel implementation of 3D FFT with volumetric decomposition schemes for efficient molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Jung, Jaewoon; Kobayashi, Chigusa; Imamura, Toshiyuki; Sugita, Yuji

    2016-03-01

    Three-dimensional Fast Fourier Transform (3D FFT) plays an important role in a wide variety of computer simulations and data analyses, including molecular dynamics (MD) simulations. In this study, we develop hybrid (MPI+OpenMP) parallelization schemes of 3D FFT based on two new volumetric decompositions, mainly for the particle mesh Ewald (PME) calculation in MD simulations. In one scheme, (1d_Alltoall), five all-to-all communications in one dimension are carried out, and in the other, (2d_Alltoall), one two-dimensional all-to-all communication is combined with two all-to-all communications in one dimension. 2d_Alltoall is similar to the conventional volumetric decomposition scheme. We performed benchmark tests of 3D FFT for the systems with different grid sizes using a large number of processors on the K computer in RIKEN AICS. The two schemes show comparable performances, and are better than existing 3D FFTs. The performances of 1d_Alltoall and 2d_Alltoall depend on the supercomputer network system and number of processors in each dimension. There is enough leeway for users to optimize performance for their conditions. In the PME method, short-range real-space interactions as well as long-range reciprocal-space interactions are calculated. Our volumetric decomposition schemes are particularly useful when used in conjunction with the recently developed midpoint cell method for short-range interactions, due to the same decompositions of real and reciprocal spaces. The 1d_Alltoall scheme of 3D FFT takes 4.7 ms to simulate one MD cycle for a virus system containing more than 1 million atoms using 32,768 cores on the K computer.

  18. Metos3D: a marine ecosystem toolkit for optimization and simulation in 3-D - Simulation Package v0.2

    NASA Astrophysics Data System (ADS)

    Piwonski, J.; Slawig, T.

    2015-06-01

    A general programming interface for parameter identification for marine ecosystem models is introduced. A comprehensive solver software for periodic steady-states is implemented that includes a fixed point iteration (spin-up) and a Newton solver. The software is based on the Portable, Extensible Toolkit for Scientific Computation (PETSc) library and uses transport matrices for efficient off-line simulation in 3-D. In addition to the usage of PETSc's parallel data structures and PETSc's Newton solver, an own load balancing algorithm is implemented. A simple verification is carried out using a well investigated biogeochemical model for phosphate (PO4) and dissolved organic phosphorous (DOP) with 7 parameters. The model is coupled via the interface to transport matrices that correspond to a longitudinal and latitudinal resolution of 2.8125° and 15 vertical layers. Initial tests show that both solvers and the load balancing algorithm work correctly. Further experiments demonstrate the robustness of the Newton solver with respect to parameter variations. Moreover, the numerical tests reveal that, with optimal control settings, the Newton solver converges at least 6 times faster towards a solution than the spin-up. However, additional twin experiments reveal differences between both solvers regarding a derivative-based black-box optimization. Whereas an optimization run with spin-up-based model evaluations is capable to identify model parameters of a reference solution, Newton-based model evaluations result in an inaccurate gradient approximation.

  19. Towards implementing plate tectonics in 3D mantle convection simulations

    NASA Astrophysics Data System (ADS)

    Bollada, Peter; Davies, Huw

    2010-05-01

    One of the great challenges in numerical mantle convection simulations is to achieve models that naturally develop plate tectonic like behaviour at the surface. In this work we are looking to achieve such models by investigating the set of models where a single consistent rheology is used for the whole model. We have started by investigating a viscoelastic rheology, related to the Oldroyd-B model from the field of polymers. The goal will be to have the parameter that controls the relaxation between elastic and viscous behaviour to depend upon temperature, pressure and strain-rate. With an appropriate choice of this dependence we have, on the near surface, high viscous/elastic regions interfaced with lower, pure viscous, regions of high strain-rate; while it also becomes more viscous at depth in the interior. In this way we hope to obtain plate like behaviour at the surface which naturally progresses to viscous convective behaviour in the interior. We have started to implement this model in the established mantle 3D finite element spherical mantle convection code TERRA (Baumgardner, 1984). Some parts of the model have been implemented as a force (to be combined with the gravitational body force) on the right hand side. The work has required us to develop and code in TERRA: (i) methods to overcome the continuity problem of the stress field stemming from the fact that the velocity field is represented by linear finite elements; (ii) new operators to handle stress and its gradients; (iii) methods to analyse plate-like behaviour at the surface (iv) the necessary functional dependence of viscosity and elastic relaxation time on temperature, strain-rate and pressure We will present the background to the work, its implementation and results.

  20. The ESyS_Particle: A New 3-D Discrete Element Model with Single Particle Rotation

    NASA Astrophysics Data System (ADS)

    Wang, Yucang; Mora, Peter

    In this paper, the Discrete Element Model (DEM) is reviewed, and the ESyS_Particle, our new version of DEM, is introduced. We particularly highlight some of the major physical concerns about DEMs and major differences between our model and most current DEMs. In the new model, single particle rotation is introduced and represented by a unit quaternion. For each 3-D particle, six degrees of freedom are employed: three for translational motion, and three for orientation. Six kinds of relative motions are permitted between two neighboring particles, and six interactions are transferred, i.e., radial, two shearing forces, twisting and two bending torques. The relative rotation between two particles is decomposed into two sequence-independent rotations such that all interactions due to the relative motions between interactive rigid bodies can be uniquely determined. This algorithm can give more accurate results because physical principles are obeyed. A theoretical analysis about how to choose the model parameters is presented. Several numerical tests have been carried out, the results indicate that most laboratory tests can be well reproduced using our model.

  1. 3D Hybrid Simulation of the Titan's Plasma Environment

    NASA Astrophysics Data System (ADS)

    Lipatov, A. S.; Sittler, E. C.; Hartle, R. E.

    2007-05-01

    Titan plays an important role as a simulation laboratory for multiscale kinetic plasma processes which are key processes in space and laboratory plasmas. A development of multiscale combined numerical methods allows us to use more realistic plasma models at Titan. In this report, we describe a Particle-Ion--Fluid-Ion--Fluid- Electron method of kinetic ion-neutral simulation code (see, e.g. [Lipatov, 2002]). This method takes into account charge-exchange and photoionization processes. The model of atmosphere of Titan was based on a paper by Sittler, Hartle, Vinas et al., [2005]. The background ions H+, O+ and pickup ions H2+, CH4+ and N2+ are described in a kinetic approximation, where the electrons are approximated as a fluid. In this report we study the coupling between background ions and pickup ions on the multiple space scales determined by the ion gyroradiis. The first results of such a simulation of the dynamics of ions near Titan are discussed in this report and compared with recent measurements made by the Cassini Plasma Spectrometer (CAPS, [Hartle, Sittler et al., 2006]). E C Sittler Jr., R E Hartle, A F Vinas, R E Johnson, H T Smith and I Mueller-Wodarg, J. Geophys. Res., 110, A09302, 2005. R. E. Hartle, E. C. Sittler, F. M. Neubauer, R. E. Johnson, et al., Planet. Space Sci., 54, 1211, 2006. A S Lipatov, The Hybrid Multiscale Simulation Technology. An Introduction with Application to Astrophysical and Laboratory Plasmas, Springer-Verlag, Berlin, Heidelberg, New York, 2002, p.p. 1-403.

  2. A Software System for Filling Complex Holes in 3D Meshes by Flexible Interacting Particles

    NASA Astrophysics Data System (ADS)

    Yamazaki, Daisuke; Savchenko, Vladimir

    3D meshes generated by acquisition devices such as laser range scanners often contain holes due to occlusion, etc. In practice, these holes are extremely geometrically and topologically complex. We propose a heuristic hole filling technique using particle systems to fill complex holes with arbitrary topology in 3D meshes. Our approach includes the following steps: hole identification, base surface creation, particle distribution, triangulation, and mesh refinement. We demonstrate the functionality of the proposed surface retouching system on synthetic and real data.

  3. Application of 3D hydrodynamic and particle tracking models for better environmental management of finfish culture

    NASA Astrophysics Data System (ADS)

    Moreno Navas, Juan; Telfer, Trevor C.; Ross, Lindsay G.

    2011-04-01

    Hydrographic conditions, and particularly current speeds, have a strong influence on the management of fish cage culture. These hydrodynamic conditions can be used to predict particle movement within the water column and the results used to optimise environmental conditions for effective site selection, setting of environmental quality standards, waste dispersion, and potential disease transfer. To this end, a 3D hydrodynamic model, MOHID, has been coupled to a particle tracking model to study the effects of mean current speed, quiescent water periods and bulk water circulation in Mulroy Bay, Co. Donegal Ireland, an Irish fjard (shallow fjordic system) important to the aquaculture industry. A Lagangrian method simulated the instantaneous release of "particles" emulating discharge from finfish cages to show the behaviour of waste in terms of water circulation and water exchange. The 3D spatial models were used to identify areas of mixed and stratified water using a version of the Simpson-Hunter criteria, and to use this in conjunction with models of current flow for appropriate site selection for salmon aquaculture. The modelled outcomes for stratification were in good agreement with the direct measurements of water column stratification based on observed density profiles. Calculations of the Simpson-Hunter tidal parameter indicated that most of Mulroy Bay was potentially stratified with a well mixed region over the shallow channels where the water is faster flowing. The fjard was characterised by areas of both very low and high mean current speeds, with some areas having long periods of quiescent water. The residual current and the particle tracking animations created through the models revealed an anticlockwise eddy that may influence waste dispersion and potential for disease transfer, among salmon cages and which ensures that the retention time of waste substances from cages is extended. The hydrodynamic model results were incorporated into the ArcView TM GIS

  4. 3D positional tracking of ellipsoidal particles in a microtube flow using holographic microscopy

    NASA Astrophysics Data System (ADS)

    Byeon, Hyeok Jun; Seo, Kyung Won; Lee, Sang Joon

    2014-11-01

    Understanding of micro-scale flow phenomena is getting large attention under advances in micro-scale measurement technologies. Especially, the dynamics of particles suspended in a fluid is essential in both scientific and industrial fields. Moreover, most particles handled in research and industrial fields have non-spherical shapes rather than a simple spherical shape. Under various flow conditions, these non-spherical particles exhibit unique dynamic behaviors. To analyze these dynamic behaviors in a fluid flow, 3D positional information of the particles should be measured accurately. In this study, digital holographic microscopy (DHM) is employed to measure the 3D positional information of non-spherical particles, which are fabricated by stretching spherical polystyrene particles. 3D motions of those particles are obtained by interpreting the holograms captured from particles. Ellipsoidal particles with known size and shape are observed to verify the performance of the DHM technique. In addition, 3D positions of particles in a microtube flow are traced. This DHM technique exhibits promising potential in the analysis of dynamic behaviors of non-spherical particles suspended in micro-scale fluid flows.

  5. Simulation of 3D Seismic Wave Propagation with Volcano Topography

    NASA Astrophysics Data System (ADS)

    Ripperger, J.; Igel, H.; Wassermann, J.

    2001-12-01

    We investigate the possibilities of using three-dimensional finite difference (FD) methods for numerical simulation of the seismic wave field at active volcanoes. We put special emphasis on the implementation of the boundary conditions for free surface topography. We compare two different approaches to solve the free surface boundary conditions. The algorithms are implemented on parallel hardware and have been tested for correctness and stability. We apply them to smooth artificial topographies and to the real topography of Mount Merapi, Indonesia. We conclude, that grid stretching type methods (e.g. Hestholm & Ruud, 1994) are not well suited for realistic volcano topography as they tend to become unstable for large topographic gradients. The representation of topography through staircase shaped grids (Ohminato & Chouet, 1997) results in stable calculations, while demanding very fine gridding. The simulations show the effects of a three-dimensional surface topography on elastic wave propagation. Ground motion at the surface is severely affected by topography. If neglected, this may jeopardize attempts to determine source location by analyzing particle motion. Numerical studies like this can help to understand wave propagation phenomena observed on field recordings in volcano seismology. Future studies will aim at separating the wave effects of internal scattering, topography and sources (tremors, tectonic events, pyroclastic flows).

  6. Measurements of the solid-body rotation of anisotropic particles in 3D turbulence

    NASA Astrophysics Data System (ADS)

    Marcus, Guy G.; Parsa, Shima; Kramel, Stefan; Ni, Rui; Voth, Greg A.

    2014-10-01

    We introduce a new method to measure Lagrangian vorticity and the rotational dynamics of anisotropic particles in a turbulent fluid flow. We use 3D printing technology to fabricate crosses (two perpendicular rods) and jacks (three mutually perpendicular rods). Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four video images of their motion in a turbulent flow between oscillating grids with {{R}λ } = 91. The advected particles have a largest dimension of 6 times the Kolmogorov length, making them a good approximation to anisotropic tracer particles. Crosses rotate like disks and jacks rotate like spheres, so these measurements, combined with previous measurements of tracer rods, allow experimental study of axisymmetric ellipsoids across the full range of aspect ratios. The measured mean square tumbling rate, < {{\\dot{p}}i}{{\\dot{p}}i}> , confirms previous direct numerical simulations that indicate that disks tumble much more rapidly than rods. Measurements of the alignment of a unit vector defining the orientation of crosses with the direction of their solid-body rotation rate vector provide the first direct observation of the alignment of anisotropic particles by the velocity gradients in a turbulent flow.

  7. A Framework for 3D Model-Based Visual Tracking Using a GPU-Accelerated Particle Filter.

    PubMed

    Brown, J A; Capson, D W

    2012-01-01

    A novel framework for acceleration of particle filtering approaches to 3D model-based, markerless visual tracking in monocular video is described. Specifically, we present a methodology for partitioning and mapping the computationally expensive weight-update stage of a particle filter to a graphics processing unit (GPU) to achieve particle- and pixel-level parallelism. Nvidia CUDA and Direct3D are employed to harness the massively parallel computational power of modern GPUs for simulation (3D model rendering) and evaluation (segmentation, feature extraction, and weight calculation) of hundreds of particles at high speeds. The proposed framework addresses the computational intensity that is intrinsic to all particle filter approaches, including those that have been modified to minimize the number of particles required for a particular task. Performance and tracking quality results for rigid object and articulated hand tracking experiments demonstrate markerless, model-based visual tracking on consumer-grade graphics hardware with pixel-level accuracy up to 95 percent at 60+ frames per second. The framework accelerates particle evaluation up to 49 times over a comparable CPU-only implementation, providing an increased particle count while maintaining real-time frame rates. PMID:21301027

  8. Correlated 3D Nanoscale Mapping and Simulation of Coupled Plasmonic Nanoparticles

    PubMed Central

    2015-01-01

    Electron tomography in combination with electron energy-loss spectroscopy (EELS) experiments and simulations was used to unravel the interplay between structure and plasmonic properties of a silver nanocuboid dimer. The precise 3D geometry of the particles fabricated by means of electron beam lithography was reconstructed through electron tomography, and the full three-dimensional information was used as an input for simulations of energy-loss spectra and plasmon resonance maps. Excellent agreement between experiment and theory was found throughout, bringing the comparison between EELS imaging and simulations to a quantitative and correlative level. In addition, interface mode patterns, normally masked by the projection nature of a transmission microscopy investigation, could be unambiguously identified through tomographic reconstruction. This work overcomes the need for geometrical assumptions or symmetry restrictions of the sample in simulations and paves the way for detailed investigations of realistic and complex plasmonic nanostructures. PMID:26495933

  9. 3-D turbulent particle dispersion submodel development. Quarterly progress report No. 1, 5 April--5 July 1991

    SciTech Connect

    Smith, P.J.

    1991-12-31

    The lack of a mathematical description of the interactions of fluid turbulence with other physics-chemical processes is a major obstacle in modeling many industrial program. Turbulent two-phase flow is a phenomenon that is of significant practical importance to coal combustion as well as other disciplines. The interactions of fluid turbulence with the particulate phase has yet to be accurately and efficiently modeled for these industrial applications. On 15 May 1991 work was initiated to cover four major tasks toward the development of a computational submodel for turbulent particle dispersion that would be applicable to coal combustion simulations. Those four tasks are: 1. A critical evaluation of the 2-D Lagrangian particle dispersion submodel, 2. Development of a 3-D submodel for turbulent particle dispersion, 3. Evaluation of the 3-D submodel for turbulent particle dispersion, 4.Exploration of extensions of the Lagrangian dispersion theory to other applications including chemistry-turbulence interactions.

  10. 3D Simulations for a Micron-Scale, Dielectric-Based Acceleration Experiment

    SciTech Connect

    Yoder, R. B.; Travish, G.; Xu Jin; Rosenzweig, J. B.

    2009-01-22

    An experimental program to demonstrate a dielectric, slab-symmetric accelerator structure has been underway for the past two years. These resonant devices are driven by a side-coupled 800-nm laser and can be configured to maintain the field profile necessary for synchronous acceleration and focusing of relativistic or nonrelativistic particles. We present 3D simulations of various versions of the structure geometry, including a metal-walled structure relevant to ongoing cold tests on resonant properties, and an all-dielectric structure to be constructed for a proof-of-principle acceleration experiment.

  11. 3D reconstruction and particle acceleration properties of Coronal Shock Waves During Powerful Solar Particle Events

    NASA Astrophysics Data System (ADS)

    Plotnikov, Illya; Vourlidas, Angelos; Tylka, Allan J.; Pinto, Rui; Rouillard, Alexis; Tirole, Margot

    2016-07-01

    Identifying the physical mechanisms that produce the most energetic particles is a long-standing observational and theoretical challenge in astrophysics. Strong pressure waves have been proposed as efficient accelerators both in the solar and astrophysical contexts via various mechanisms such as diffusive-shock/shock-drift acceleration and betatron effects. In diffusive-shock acceleration, the efficacy of the process relies on shock waves being super-critical or moving several times faster than the characteristic speed of the medium they propagate through (a high Alfven Mach number) and on the orientation of the magnetic field upstream of the shock front. High-cadence, multipoint imaging using the NASA STEREO, SOHO and SDO spacecrafts now permits the 3-D reconstruction of pressure waves formed during the eruption of coronal mass ejections. Using these unprecedented capabilities, some recent studies have provided new insights on the timing and longitudinal extent of solar energetic particles, including the first derivations of the time-dependent 3-dimensional distribution of the expansion speed and Mach numbers of coronal shock waves. We will review these recent developments by focusing on particle events that occurred between 2011 and 2015. These new techniques also provide the opportunity to investigate the enigmatic long-duration gamma ray events.

  12. Multiscale Processes Energizing Plasmas during Reconnection: 3D Simulations in preparation for the MMS mission

    NASA Astrophysics Data System (ADS)

    Lapenta, Giovanni; Goldman, Martin; Newman, David

    2015-11-01

    Magnetic reconnection is a mechanism to convert magnetic energy to particle energy in the form of heat and directed flows. We study here where reconnection and particle energization are found in full 3D models of a reconnecting plasma sheet. Three regions emerge as the primary loci of energy conversion: the separatrices, the dipolarization fronts and the electron diffusion region near x-points. We consider two scenarios: one where the exhaust from multiple x-lines forms a plasmoid (a flux rope in 3D) and one where the exhaust encounters pristine unreconnected plasma and forms a pile-up front. A key process intrinsically 3D, not present in 2D, is the development of an instability in the outflow leading to the formation of secondary reconnection sites that further enhance energy conversion. The MMS mission of NASA was launched on March 12 of this year with the stated goal of finding these regions. We will soon know if we are right in predicting these additional regions of dissipation in the reconnection outflow. Work supported by the NASA MMS Program and by the BOF funds of the KU Leuven. Simulations conducted on NASA Computing facilities, PRACE Tier-0 computing and at NERSC (DOE Office of Science User Contract No. DE-AC02-05CH11231).

  13. Using 3-D Numerical Weather Data in Piloted Simulations

    NASA Technical Reports Server (NTRS)

    Daniels, Taumi S.

    2016-01-01

    This report describes the process of acquiring and using 3-D numerical model weather data sets in NASA Langley's Research Flight Deck (RFD). A set of software tools implement the process and can be used for other purposes as well. Given time and location information of a weather phenomenon of interest, the user can download associated numerical weather model data. These data are created by the National Oceanic and Atmospheric Administration (NOAA) High Resolution Rapid Refresh (HRRR) model, and are then processed using a set of Mathworks' Matlab(TradeMark) scripts to create the usable 3-D weather data sets. Each data set includes radar re ectivity, water vapor, component winds, temperature, supercooled liquid water, turbulence, pressure, altitude, land elevation, relative humidity, and water phases. An open-source data processing program, wgrib2, is available from NOAA online, and is used along with Matlab scripts. These scripts are described with sucient detail to make future modi cations. These software tools have been used to generate 3-D weather data for various RFD experiments.

  14. Method and simulation to study 3D crosstalk perception

    NASA Astrophysics Data System (ADS)

    Khaustova, Dar'ya; Blondé, Laurent; Huynh-Thu, Quan; Vienne, Cyril; Doyen, Didier

    2012-03-01

    To various degrees, all modern 3DTV displays suffer from crosstalk, which can lead to a decrease of both visual quality and visual comfort, and also affect perception of depth. In the absence of a perfect 3D display technology, crosstalk has to be taken into account when studying perception of 3D stereoscopic content. In order to improve 3D presentation systems and understand how to efficiently eliminate crosstalk, it is necessary to understand its impact on human perception. In this paper, we present a practical method to study the perception of crosstalk. The approach consists of four steps: (1) physical measurements of a 3DTV, (2) building of a crosstalk surface based on those measurements and representing specifically the behavior of that 3TV, (3) manipulation of the crosstalk function and application on reference images to produce test images degraded by crosstalk in various ways, and (4) psychophysical tests. Our approach allows both a realistic representation of the behavior of a 3DTV and the easy manipulation of its resulting crosstalk in order to conduct psycho-visual experiments. Our approach can be used in all studies requiring the understanding of how crosstalk affects perception of stereoscopic content and how it can be corrected efficiently.

  15. 3D quantification of brain microvessels exposed to heavy particle radiation

    NASA Astrophysics Data System (ADS)

    Hintermüller, C.; Coats, J. S.; Obenaus, A.; Nelson, G.; Krucker, T.; Stampanoni, M.

    2009-09-01

    Space radiation with high energy particles and cosmic rays presents a significant hazard to spaceflight crews. Recent reviews of the health risk to astronauts from ionizing radiation concluded to establish a level of risk which may indicate the possible performance decrements and decreased latency of late dysfunction syndromes (LDS) of the brain. A hierarchical imaging approach developed at ETH Zürich and PSI, which relies on synchrotron based X-ray Tomographic Microscopy (SRXTM), was used to visualize and analyze 3D vascular structures down to the capillary level in their precise anatomical context. Various morphological parameters, such as overall vessel volume, vessel thickness and spacing, are extracted to characterize the vascular structure within a region of interest. For a first quantification of the effect of high energy particles on the vasculature we scanned a set of 6 animals, all of same age. The animals were irradiated with 1 Gy, 2 Gy and 4 Gy of 600MeV 56Fe heavy particles simulating the space radiation environment. We found that with increasing dose the diameter of vessels and the overall vessel volume are decreased whereas the vessel spacing is increased. As these parameters reflect blood flow in three-dimensional space they can be used as indicators for the degree of vascular efficiency which can have an impact on the function and development of lung tissue or tumors.

  16. Regional airflow and particle distribution in the lung with a 3D-1D coupled subject-specific boundary condition

    NASA Astrophysics Data System (ADS)

    Choi, Jiwoong; Yin, Youbing; Hoffman, Eric; Tawhai, Merryn; Lin, Ching-Long

    2010-11-01

    Correct prediction of regional distribution of inhaled aerosol particles is vital to improve pulmonary medicine. Physiologically consistent regional ventilations of airflow and aerosol particles are simulated with a 3D-1D coupled subject-specific boundary condition (BC). In 3D CT-resolved 7-generation airways, large eddy simulations are performed to capture detailed airflow characteristics and Lagrangian particle simulations are carried to track the particle transport and deposition. Results are compared with two traditional outlet BCs: uniform velocity and uniform pressure. Proposed BC is eligible for physiologically consistent airflow distribution in the lung, while the others are not. The regional ventilation and deposition of particles reflect the regional ventilation of airflow. In this study, two traditional BCs yield up to 98% (334%) over-prediction in lobar particle ventilation (deposition) fraction. Upper to lower particle ventilation ratios of both left and right lungs read ˜0.4 with the proposed BC, while those for the other two BCs vary with the error up to 73%.

  17. Characterizing heterogeneity among virus particles by stochastic 3D signal reconstruction

    NASA Astrophysics Data System (ADS)

    Xu, Nan; Gong, Yunye; Wang, Qiu; Zheng, Yili; Doerschuk, Peter C.

    2015-09-01

    In single-particle cryo electron microscopy, many electron microscope images each of a single instance of a biological particle such as a virus or a ribosome are measured and the 3-D electron scattering intensity of the particle is reconstructed by computation. Because each instance of the particle is imaged separately, it should be possible to characterize the heterogeneity of the different instances of the particle as well as a nominal reconstruction of the particle. In this paper, such an algorithm is described and demonstrated on the bacteriophage Hong Kong 97. The algorithm is a statistical maximum likelihood estimator computed by an expectation maximization algorithm implemented in Matlab software.

  18. 3-D Simulations of Plasma Wakefield Acceleration with Non-Idealized Plasmas and Beams

    SciTech Connect

    Deng, S.; Katsouleas, T.; Lee, S.; Muggli, P.; Mori, W.B.; Hemker, R.; Ren, C.; Huang, C.; Dodd, E.; Blue, B.E.; Clayton, C.E.; Joshi, C.; Wang, S.; Decker, F.J.; Hogan, M.J.; Iverson, R.H.; O'Connell, C.; Raimondi, P.; Walz, D.; /SLAC

    2005-09-27

    3-D Particle-in-cell OSIRIS simulations of the current E-162 Plasma Wakefield Accelerator Experiment are presented in which a number of non-ideal conditions are modeled simultaneously. These include tilts on the beam in both planes, asymmetric beam emittance, beam energy spread and plasma inhomogeneities both longitudinally and transverse to the beam axis. The relative importance of the non-ideal conditions is discussed and a worst case estimate of the effect of these on energy gain is obtained. The simulation output is then propagated through the downstream optics, drift spaces and apertures leading to the experimental diagnostics to provide insight into the differences between actual beam conditions and what is measured. The work represents a milestone in the level of detail of simulation comparisons to plasma experiments.

  19. Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence.

    PubMed

    Cole, Brendan C; Marcus, Guy G; Parsa, Shima; Kramel, Stefan; Ni, Rui; Voth, Greg A

    2016-01-01

    Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with Rλ = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates. PMID:27404898

  20. Development of a 3D Digital Particle Image Thermometry and Velocimetry (3DDPITV) System

    NASA Astrophysics Data System (ADS)

    Schmitt, David; Rixon, Greg; Dabiri, Dana

    2006-11-01

    A novel 3D Digital Particle Image Thermometry and Velocimetry (3DDPITV) system has been designed and fabricated. By combining 3D Digital Particle Image Velocimetry (3DDPIV) and Digital Particle Image Thermometry (DPIT) into one system, this technique provides simultaneous temperature and velocity data in a volume of ˜1x1x0.5 in^3 using temperature sensitive liquid crystal particles as flow sensors. Two high-intensity xenon flashlamps were used as illumination sources. The imaging system consists of six CCD cameras, three allocated for measuring velocity, based on particle motion, and three for measuring temperature, based on particle color. The cameras were optically aligned using a precision grid and high-resolution translation stages. Temperature calibration was then performed using a precision thermometer and a temperature-controlled bath. Results from proof-of-concept experiments will be presented and discussed.

  1. Global 3-D Hybrid Simulations of Mars and the Effect of Crustal Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Brecht, S. H.; Ledvina, S. A.; Luhmann, J. G.

    2001-12-01

    Mars is not protected from the solar wind by a strong intrinsic magnetic field. Further, Mars is a very small planet. These two aspects of Mars mean that the solar wind interaction with the planet is both direct and kinetic in behavior. The large gyroradius of the incoming solar wind and the large gyroradius of the pick up ions make the solar wind interaction with Mars very unique. Over the years the authors using a 3-D kinetic hybrid particle code have studied this planet. Mars Global Surveyor has produced many exciting discoveries. Probably the most significant and unexpected was the presence of the crustal magnetic fields on the surface of the planet. The presence of these strong crustal fields suggests that the solar wind interaction with Mars will be altered. In fact, it suggests that the loss rate of pick up ions and the shape of the Martian magnetosphere will be substantially changed. Results will be presented from our latest 3-D hybrid particle code simulations of Mars where models for the crustal magnetic field have been inserted into the simulations. Particular emphasis will be placed on changes to the magnetic field topology and the change in the rate of pick up ions.

  2. 3-D SIMULATIONS OF AIRWAYS WITHIN HUMAN LUNGS

    EPA Science Inventory

    Information regarding the deposition patterns of inhaled particles has important application to the fields of toxicology and medicine. The former concerns the risk assessment of inhaled air pollutants (inhalation toxicology); the latter concerns the targeted delivery of inhaled ...

  3. Enhancing Pre-Service Teachers' Awareness to Pupils' Test-Anxiety with 3D Immersive Simulation

    ERIC Educational Resources Information Center

    Passig, David; Moshe, Ronit

    2008-01-01

    This study investigated whether participating in a 3D immersive virtual reality world simulating the experience of test-anxiety would affect preservice teachers' awareness to the phenomenon. Ninety subjects participated in this study, and were divided into three groups. The experimental group experienced a 3D immersive simulation which made…

  4. Particle-based optical pressure sensors for 3D pressure mapping.

    PubMed

    Banerjee, Niladri; Xie, Yan; Chalaseni, Sandeep; Mastrangelo, Carlos H

    2015-10-01

    This paper presents particle-based optical pressure sensors for in-flow pressure sensing, especially for microfluidic environments. Three generations of pressure sensitive particles have been developed- flat planar particles, particles with integrated retroreflectors and spherical microballoon particles. The first two versions suffer from pressure measurement dependence on particles orientation in 3D space and angle of interrogation. The third generation of microspherical particles with spherical symmetry solves these problems making particle-based manometry in microfluidic environment a viable and efficient methodology. Static and dynamic pressure measurements have been performed in liquid medium for long periods of time in a pressure range of atmospheric to 40 psi. Spherical particles with radius of 12 μm and balloon-wall thickness of 0.5 μm are effective for more than 5 h in this pressure range with an error of less than 5%. PMID:26342493

  5. Full-Scale 3D Simulation of a sputtering magnetron

    NASA Astrophysics Data System (ADS)

    Walton, C. C.; Wilks, S. C.; Ayyaswamy, V.; Verboncoeur, J. P.; Parks, P. B.; Wu, W.; Zhou, C. D.; Stoltz, P. H.

    2010-11-01

    PIC simulations have been used to study ion energy distributions in magnetron plasmas, and coupled with other simulations to relate plasma processes to properties of sputtered films. The plasma is weakly ionized and exchanges heat with the background gas by scattering and charge-exchange reactions. Resulting heating of neutral background gas up to ˜1200K, leading to ˜5X rarefaction and increased plasma impedance, was studied with coupled PIC and Direct Simulation Monte Carlo (DSMC) simulations. Effects of scaling the PIC simulations from 0.1X to 1X physical size, and modifying the plasma potential by a dc substrate bias, will be presented. Comparison to experimental I-V relations and importance for roughness and density of sputtered films will be discussed.

  6. 3D kinetic simulations of the global interaction between the solar wind and the magnetosphere

    NASA Astrophysics Data System (ADS)

    Amaya, Jorge; Maneva, Yana; Deca, Jan; Lapenta, Giovanni

    2015-04-01

    We performed three dimensional simulations of the interaction between the solar wind and the magnetosphere, using the self-consistent fully kinetic code iPic3D. The main objective of our simulations is to link the global interaction phenomena to the local turbulence and reconnection processes in the magnetosphere. Other numerical approaches have been used before to study this problem, including MHD, hybrid and Vlasov codes. However, only particle-in-cell codes offer the possibility to study the kinetic effects of the diffusion regions of the Earth environment that drive the energy transfer from the solar wind to the magnetosphere. Previous attempts to perform such kinds of simulations were limited to unphysical thermal velocities of the ion and electron species, small simulation boxes or cell sizes that do not capture the local kinetic effects at the magnetopause. Using the implicit moment Particle-in-Cell approach we performed simulations that can capture these small scale effects and, at the same time, allow to study large scale phenomena such as the bow shock and the development of the magnetotail. We expect that these results will be used to maximize the impact of future space missions, such as THOR, MMS and BepiColombo, by improving our understanding of the planetary environment, from the conditions observed in the solar wind to the turbulence and reconnection processes downstream of the bow shock.

  7. 3D CFDTD PIC Simulation Study on Low-Frequency Oscillations in a Gyrotron

    NASA Astrophysics Data System (ADS)

    Lin, M. C.; Smithe, D. N.

    2011-10-01

    Low-frequency oscillations (LFOs) have been observed in a high average power gyrotron and the trapped electron population contributing to the oscillation has been measured. As high average power gyrotrons are the most promising millimeter wave source for thermonuclear fusion research, it is important to get a better understanding of this parasitic phenomenon to avoid any deterioration of the electron beam quality thus reducing the gyrotron efficiency. However, understanding of the LFOs remains incomplete and a full picture of this parasitic phenomenon has not been seen yet. In this work, we use a 3D conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) method to accurately and efficiently study the LFOs in a magnetron injection gun (MIG) of a high average power gyrotron. Employing a highly parallelized computation, the model can be simulated in time domain more realistically. LFOs have been obtained in a 3D time domain simulation for the first time. From our preliminary simulation studies, it is found that not only magnetic compression profile but initial velocity or velocity ratio play an important role in the operation of a MIG electron gun. In addition, the secondary emission effects on the LFOs are also studied. Detailed results will be presented. Work supported by the U.S. Department of Energy under Grant No. DE-SC0004436.

  8. Simple 3-D stimulus for motion parallax and its simulation.

    PubMed

    Ono, Hiroshi; Chornenkyy, Yevgen; D'Amour, Sarah

    2013-01-01

    Simulation of a given stimulus situation should produce the same perception as the original. Rogers et al (2009 Perception 38 907-911) simulated Wheeler's (1982, PhD thesis, Rutgers University, NJ) motion parallax stimulus and obtained quite different perceptions. Wheeler's observers were unable to reliably report the correct direction of depth, whereas Rogers's were. With three experiments we explored the possible reasons for the discrepancy. Our results suggest that Rogers was able to see depth from the simulation partly due to his experience seeing depth with random dot surfaces. PMID:23964382

  9. Tensor3D: A computer graphics program to simulate 3D real-time deformation and visualization of geometric bodies

    NASA Astrophysics Data System (ADS)

    Pallozzi Lavorante, Luca; Dirk Ebert, Hans

    2008-07-01

    Tensor3D is a geometric modeling program with the capacity to simulate and visualize in real-time the deformation, specified through a tensor matrix and applied to triangulated models representing geological bodies. 3D visualization allows the study of deformational processes that are traditionally conducted in 2D, such as simple and pure shears. Besides geometric objects that are immediately available in the program window, the program can read other models from disk, thus being able to import objects created with different open-source or proprietary programs. A strain ellipsoid and a bounding box are simultaneously shown and instantly deformed with the main object. The principal axes of strain are visualized as well to provide graphical information about the orientation of the tensor's normal components. The deformed models can also be saved, retrieved later and deformed again, in order to study different steps of progressive strain, or to make this data available to other programs. The shape of stress ellipsoids and the corresponding Mohr circles defined by any stress tensor can also be represented. The application was written using the Visualization ToolKit, a powerful scientific visualization library in the public domain. This development choice, allied to the use of the Tcl/Tk programming language, which is independent on the host computational platform, makes the program a useful tool for the study of geometric deformations directly in three dimensions in teaching as well as research activities.

  10. GATOR: A 3-D time-dependent simulation code for helix TWTs

    SciTech Connect

    Zaidman, E.G.; Freund, H.P.

    1996-12-31

    A 3D nonlinear analysis of helix TWTs is presented. The analysis and simulation code is based upon a spectral decomposition using the vacuum sheath helix modes. The field equations are integrated on a grid and advanced in time using a MacCormack predictor-corrector scheme, and the electron orbit equations are integrated using a fourth order Runge-Kutta algorithm. Charge is accumulated on the grid and the field is interpolated to the particle location by a linear map. The effect of dielectric liners on the vacuum sheath helix dispersion is included in the analysis. Several numerical cases are considered. Simulation of the injection of a DC beam and a signal at a single frequency is compared with a linear field theory of the helix TWT interaction, and good agreement is found.

  11. 3-D Hybrid Simulation of Interaction Between Solar Wind Discontinuity and Magnetosphere

    NASA Astrophysics Data System (ADS)

    Pang, Y.; Lin, Y.; Deng, X.; Wang, X.

    2008-12-01

    Previous simulations and observations indicate that interaction of interplanetary directional tangential discontinuities (TD), across which only the direction of magnetic field changes,with the bow shock may initiate magnetic reconnection as the TD is transmitted into the magnetosheath. We employ a 3-D electromagnetic, hybrid simulation to study such interaction between the TD and the bow shock-magnetosheath-magnetopause system, while the hybrid model treats the ions kinetically via particle-in-cell methods and the electrons as a massless fluid. We present results corresponding to different orientations of the initial IMF, TDs with various thicknesses ranging from 10 to 30 ion skin depths, and polarizations of magnetic field and senses of field rotation across the TD. Our results indicate that the reconnection rate and structure can be influenced by the width and the structure of the TD. The kinetic structure and evolution of FTEs produced by the magnetosheath reconnection, as they propagate to the magnetopause, will be studied.

  12. 3D Hot Test Simulations of a 220 GHz Folded Waveguide Traveling Wave Tube Using a CFDTD PIC Method

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Chieh; Song, Heather

    2015-11-01

    Millimeter or sub-THz wave sources centered at 220 GHz is of interest due to the potential for its commercial and military applications including high resolution radar, remote sensing, and high-data-rate communications. It has been demonstrated via 3D cold test finite element method (FEM) simulations that a folded waveguide traveling wave tube (FWTWT) can be designed and optimized at this frequency range with a small signal gain of 18 dB over a comparatively broad (-3 dB) bandwidth of ~ 10%. On the other hand, 3D hot test simulations of a V-band ladder TWT have been successfully demonstrated using a conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) method for center frequency of 50 GHz. In the present work, the 220 GHz FWTWT designs have been reviewed and studied. 3D Cold test simulations using both the CFDTD and FEM methods have been carried out and compared with each other as basis for 3D hot test CFDTD PIC simulations. The preliminary simulation result shows that the gain-bandwidth features at 220 GHz are achievable while carefully avoiding beam interceptions. Our study shows that the interaction characteristics are very sensitive to the operating beam parameters. Detail simulation results and discussions will be presented.

  13. 3-D dynamic rupture simulations by a finite volume method

    NASA Astrophysics Data System (ADS)

    Benjemaa, M.; Glinsky-Olivier, N.; Cruz-Atienza, V. M.; Virieux, J.

    2009-07-01

    Dynamic rupture of a 3-D spontaneous crack of arbitrary shape is investigated using a finite volume (FV) approach. The full domain is decomposed in tetrahedra whereas the surface, on which the rupture takes place, is discretized with triangles that are faces of tetrahedra. First of all, the elastodynamic equations are described into a pseudo-conservative form for an easy application of the FV discretization. Explicit boundary conditions are given using criteria based on the conservation of discrete energy through the crack surface. Using a stress-threshold criterion, these conditions specify fluxes through those triangles that have suffered rupture. On these broken surfaces, stress follows a linear slip-weakening law, although other friction laws can be implemented. For The Problem Version 3 of the dynamic-rupture code verification exercise conducted by the SCEC/USGS, numerical solutions on a planar fault exhibit a very high convergence rate and are in good agreement with the reference one provided by a finite difference (FD) technique. For a non-planar fault of parabolic shape, numerical solutions agree satisfactorily well with those obtained with a semi-analytical boundary integral method in terms of shear stress amplitudes, stopping phases arrival times and stress overshoots. Differences between solutions are attributed to the low-order interpolation of the FV approach, whose results are particularly sensitive to the mesh regularity (structured/unstructured). We expect this method, which is well adapted for multiprocessor parallel computing, to be competitive with others for solving large scale dynamic ruptures scenarios of seismic sources in the near future.

  14. SIERRA - A 3-D device simulator for reliability modeling

    NASA Astrophysics Data System (ADS)

    Chern, Jue-Hsien; Arledge, Lawrence A., Jr.; Yang, Ping; Maeda, John T.

    1989-05-01

    SIERRA is a three-dimensional general-purpose semiconductor-device simulation program which serves as a foundation for investigating integrated-circuit (IC) device and reliability issues. This program solves the Poisson and continuity equations in silicon under dc, transient, and small-signal conditions. Executing on a vector/parallel minisupercomputer, SIERRA utilizes a matrix solver which uses an incomplete LU (ILU) preconditioned conjugate gradient square (CGS, BCG) method. The ILU-CGS method provides a good compromise between memory size and convergence rate. The authors have observed a 5x to 7x speedup over standard direct methods in simulations of transient problems containing highly coupled Poisson and continuity equations such as those found in reliability-oriented simulations. The application of SIERRA to parasitic CMOS latchup and dynamic random-access memory single-event-upset studies is described.

  15. Vectors in Use in a 3D Juggling Game Simulation

    ERIC Educational Resources Information Center

    Kynigos, Chronis; Latsi, Maria

    2006-01-01

    The new representations enabled by the educational computer game the "Juggler" can place vectors in a central role both for controlling and measuring the behaviours of objects in a virtual environment simulating motion in three-dimensional spaces. The mathematical meanings constructed by 13 year-old students in relation to vectors as objects, as a…

  16. Hierarchical Approach to 'Atomistic' 3-D MOSFET Simulation

    NASA Technical Reports Server (NTRS)

    Asenov, Asen; Brown, Andrew R.; Davies, John H.; Saini, Subhash

    1999-01-01

    We present a hierarchical approach to the 'atomistic' simulation of aggressively scaled sub-0.1 micron MOSFET's. These devices are so small that their characteristics depend on the precise location of dopant atoms within them, not just on their average density. A full-scale three-dimensional drift-diffusion atomistic simulation approach is first described and used to verify more economical, but restricted, options. To reduce processor time and memory requirements at high drain voltage, we have developed a self-consistent option based on a solution of the current continuity equation restricted to a thin slab of the channel. This is coupled to the solution of the Poisson equation in the whole simulation domain in the Gummel iteration cycles. The accuracy of this approach is investigated in comparison to the full self-consistent solution. At low drain voltage, a single solution of the nonlinear Poisson equation is sufficient to extract the current with satisfactory accuracy. In this case, the current is calculated by solving the current continuity equation in a drift approximation only, also in a thin slab containing the MOSFET channel. The regions of applicability for the different components of this hierarchical approach are illustrated in example simulations covering the random dopant-induced threshold voltage fluctuations, threshold voltage lowering, threshold voltage asymmetry, and drain current fluctuations.

  17. Advanced 3D Photocathode Modeling and Simulations Final Report

    SciTech Connect

    Dimitre A Dimitrov; David L Bruhwiler

    2005-06-06

    High brightness electron beams required by the proposed Next Linear Collider demand strong advances in photocathode electron gun performance. Significant improvement in the production of such beams with rf photocathode electron guns is hampered by the lack high-fidelity simulations. The critical missing piece in existing gun codes is a physics-based, detailed treatment of the very complex and highly nonlinear photoemission process.

  18. 3D Numerical simulations of the C-start of a Bluegill Sunfish

    NASA Astrophysics Data System (ADS)

    Narayanan, Venkat R. T.; Borazjani, Iman; Sotiropoulos, Fotis; Tytell, Eric D.; Lauder, George V.

    2009-11-01

    Obtaining the 3D flow field, forces, and power produced during the fast start maneuvers of fish is essential for studying this behavior from the hydrodynamics perspective. During a typical fast start, which is typically referred to as the C-start, the fish initially bends its body in a C shape manner and then with a fast stroke bends out of the C shape. We carry out high-resolution, 3D simulations of a bluegill sunfish performing a C-start maneuver. The body geometry and motion during the C-start are obtained from the experimental. We used high-speed video and particle image velocimetry to quantify body motion and flows produced during the C-start. We carry out simulations both with the entire motion prescribed and by prescribing only the deformation of the body but predicting the motion of the fish center of mass via a fluid-structure interaction approach. The computed results are compared with experimental observations and analyzed to further elucidate dynamics and three-dimensional structure of the C-start flowfields.

  19. Large-scale 3D simulations of ICF and HEDP targets

    NASA Astrophysics Data System (ADS)

    Marinak, Michael M.

    2000-10-01

    The radiation hydrodynamics code HYDRA continues to be developed and applied to 3D simulations of a variety of targets for both inertial confinement fusion (ICF) and high energy density physics. Several packages have been added enabling this code to perform ICF target simulations with similar accuracy as two-dimensional codes of long-time historical use. These include a laser ray trace and deposition package, a heavy ion deposition package, implicit Monte Carlo photonics, and non-LTE opacities, derived from XSN or the linearized response matrix approach.(R. More, T. Kato, Phys. Rev. Lett. 81, 814 (1998), S. Libby, F. Graziani, R. More, T. Kato, Proceedings of the 13th International Conference on Laser Interactions and Related Plasma Phenomena, (AIP, New York, 1997).) LTE opacities can also be calculated for arbitrary mixtures online by combining tabular values generated by different opacity codes. Thermonuclear burn, charged particle transport, neutron energy deposition, electron-ion coupling and conduction, and multigroup radiation diffusion packages are also installed. HYDRA can employ ALE hydrodynamics; a number of grid motion algorithms are available. Multi-material flows are resolved using material interface reconstruction. Results from large-scale simulations run on up to 1680 processors, using a combination of massively parallel processing and symmetric multiprocessing, will be described. A large solid angle simulation of Rayleigh-Taylor instability growth in a NIF ignition capsule has resolved simultaneously the full spectrum of the most dangerous modes that grow from surface roughness. Simulations of a NIF hohlraum illuminated with the initial 96 beam configuration have also been performed. The effect of the hohlraum’s 3D intrinsic drive asymmetry on the capsule implosion will be considered. We will also discuss results from a Nova experiment in which a copper sphere is crushed by a planar shock. Several interacting hydrodynamic instabilities, including

  20. 3D imaging of particle tracks in Solid State Nuclear Track Detectors

    NASA Astrophysics Data System (ADS)

    Wertheim, D.; Gillmore, G.; Brown, L.; Petford, N.

    2009-04-01

    Inhalation of radon gas (222Rn) and associated ionizing decay products is known to cause lung cancer in human. In the U.K., it has been suggested that 3 to 5 % of total lung cancer deaths can be linked to elevated radon concentrations in the home and/or workplace. Radon monitoring in buildings is therefore routinely undertaken in areas of known risk. Indeed, some organisations such as the Radon Council in the UK and the Environmental Protection Agency in the USA, advocate a ‘to test is best' policy. Radon gas occurs naturally, emanating from the decay of 238U in rock and soils. Its concentration can be measured using CR?39 plastic detectors which conventionally are assessed by 2D image analysis of the surface; however there can be some variation in outcomes / readings even in closely spaced detectors. A number of radon measurement methods are currently in use (for examples, activated carbon and electrets) but the most widely used are CR?39 solid state nuclear track?etch detectors (SSNTDs). In this technique, heavily ionizing alpha particles leave tracks in the form of radiation damage (via interaction between alpha particles and the atoms making up the CR?39 polymer). 3D imaging of the tracks has the potential to provide information relating to angle and energy of alpha particles but this could be time consuming. Here we describe a new method for rapid high resolution 3D imaging of SSNTDs. A ‘LEXT' OLS3100 confocal laser scanning microscope was used in confocal mode to successfully obtain 3D image data on four CR?39 plastic detectors. 3D visualisation and image analysis enabled characterisation of track features. This method may provide a means of rapid and detailed 3D analysis of SSNTDs. Keywords: Radon; SSNTDs; confocal laser scanning microscope; 3D imaging; LEXT

  1. Photorealistic 3D omni-directional stereo simulator

    NASA Astrophysics Data System (ADS)

    Reiners, Dirk; Cruz-Neira, Carolina; Neumann, Carsten

    2015-03-01

    While a lot of areas in VR have made significant advances, visual rendering in VR is often not quite keeping up with the state of the art. There are many reasons for this, but one way to alleviate some of the issues is by using ray tracing instead of rasterization for image generation. Contrary to popular belief, ray tracing is a realistic, competitive technology nowadays. This paper looks at the pros and cons of using ray tracing and demonstrates the feasibility of employing it using the example of a helicopter flight simulator image generator.

  2. Linking continuum mechanics and 3D discrete dislocation simulations

    SciTech Connect

    El-Azab, A. A.; Fivel, M.

    1998-10-18

    A technique is developed for linking the methods of discrete dislocation dynamics simulation and finite element to treat elasto-plasticity problems. The overall formulation views the plastically deforming crystal as an elastic crystal with continuously changing dislocation microstructure which is tracked by the numerical dynamics simulation. The FEM code needed in this regard is based on linear elasticity only. This formulation presented here is focused on a continuous updating of the outer shape of the crystal, for possible regeneration of the FEM mesh, and adjustment of the surface geometry, in particular the surface normal. The method is expected to be potentially applicable to the nano- indentation experiments, where the zone around the indenter-crystal contact undergoes significant permanent deformation, the rigorous determination of which is very important to the calculation of the indentation print area and in turn, the surface hardness. Furthermore, the technique is expected to account for the plastic history of the surface displacement under the indenter. Other potential applications are mentioned in the text.

  3. Holographic particle velocimetry - A 3D measurement technique for vortex interactions, coherent structures and turbulence

    NASA Astrophysics Data System (ADS)

    Meng, Hui; Hussain, Fazle

    1991-10-01

    To understand the topology and dynamics of coherent structures (CS), the interactions of CS with fine-scale turbulence, and the effects of CS on entrainment, mixing and combustion, experimental tools are needed that can measure velocity (preferably vorticity) vector fields in both 3D space and time. While traditional measurement techniques are not able to serve this purpose, holographic particle velocimetry (HPV) appears to be promising. In a demonstration experiment, the instantaneous 3D velocity vector fields in some simple vortical flows have been obtained using the HPV technique. In this preliminary report, the principles of the HPV technique are illustrated and the key issues in its implementation are discussed.

  4. Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins

    NASA Astrophysics Data System (ADS)

    Tsai, Chun-Ying; Chang, Yuan-Chih; Lobato, Ivan; van Dyck, Dirk; Chen, Fu-Rong

    2016-06-01

    The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 Å resolution but using a strongly reduced number of images.

  5. Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins.

    PubMed

    Tsai, Chun-Ying; Chang, Yuan-Chih; Lobato, Ivan; Van Dyck, Dirk; Chen, Fu-Rong

    2016-01-01

    The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 Å resolution but using a strongly reduced number of images. PMID:27292544

  6. 3-D reconstruction of pre-characterized lithium and tungsten dust particle trajectories in NSTX

    NASA Astrophysics Data System (ADS)

    Nichols, J.; Roquemore, A. L.; Davis, W.; Mansfield, D. K.; Skinner, C. H.; Feibush, E.; Boeglin, W.; Patel, R.; Abolafia, D.; Hartzfeld, K.; Maqueda, R.

    2011-08-01

    Calibrated amounts of 40 μm lithium dust and 10 μm tungsten powder have been dropped from above into the SOL of the National Spherical Torus Experiment (NSTX) to benchmark modeling of dust dynamics and transport. By combining the output from two visible-range fast cameras, 3-D trajectories are reliably obtained and have resulted in the generation of several hundred individual particle tracks. Particles are observed to undergo a variety of accelerations both parallel and perpendicular to the magnetic field, as well as abrupt large-angle changes in direction. All tracks obtained to date display particle motion that is constrained to within a few centimeters of the last closed flux surface. The 3-D trajectories are presented and compared to the location of the last closed flux surface as determined by EFIT.

  7. Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins

    PubMed Central

    Tsai, Chun-Ying; Chang, Yuan-Chih; Lobato, Ivan; Van Dyck, Dirk; Chen, Fu-Rong

    2016-01-01

    The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 Å resolution but using a strongly reduced number of images. PMID:27292544

  8. Multisensor fusion for 3D target tracking using track-before-detect particle filter

    NASA Astrophysics Data System (ADS)

    Moshtagh, Nima; Romberg, Paul M.; Chan, Moses W.

    2015-05-01

    This work presents a novel fusion mechanism for estimating the three-dimensional trajectory of a moving target using images collected by multiple imaging sensors. The proposed projective particle filter avoids the explicit target detection prior to fusion. In projective particle filter, particles that represent the posterior density (of target state in a high-dimensional space) are projected onto the lower-dimensional observation space. Measurements are generated directly in the observation space (image plane) and a marginal (sensor) likelihood is computed. The particles states and their weights are updated using the joint likelihood computed from all the sensors. The 3D state estimate of target (system track) is then generated from the states of the particles. This approach is similar to track-before-detect particle filters that are known to perform well in tracking dim and stealthy targets in image collections. Our approach extends the track-before-detect approach to 3D tracking using the projective particle filter. The performance of this measurement-level fusion method is compared with that of a track-level fusion algorithm using the projective particle filter. In the track-level fusion algorithm, the 2D sensor tracks are generated separately and transmitted to a fusion center, where they are treated as measurements to the state estimator. The 2D sensor tracks are then fused to reconstruct the system track. A realistic synthetic scenario with a boosting target was generated, and used to study the performance of the fusion mechanisms.

  9. Dynamic 3D simulations of earthquakes on en echelon faults

    USGS Publications Warehouse

    Harris, R.A.; Day, S.M.

    1999-01-01

    One of the mysteries of earthquake mechanics is why earthquakes stop. This process determines the difference between small and devastating ruptures. One possibility is that fault geometry controls earthquake size. We test this hypothesis using a numerical algorithm that simulates spontaneous rupture propagation in a three-dimensional medium and apply our knowledge to two California fault zones. We find that the size difference between the 1934 and 1966 Parkfield, California, earthquakes may be the product of a stepover at the southern end of the 1934 earthquake and show how the 1992 Landers, California, earthquake followed physically reasonable expectations when it jumped across en echelon faults to become a large event. If there are no linking structures, such as transfer faults, then strike-slip earthquakes are unlikely to propagate through stepovers >5 km wide. Copyright 1999 by the American Geophysical Union.

  10. 3-D Coldtest Simulations of W-Band Devices

    NASA Astrophysics Data System (ADS)

    Petillo, John J.

    1998-04-01

    Recent advances in the simulation and modeling of vacuum electronic devices has opened up the door for the much-anticipated ``first-pass design success" of these devices by computational means. For W-band, this is an exciting prospect since many current designs begin with scaling from lower-frequency devices. The next step is trial and error by fabrication and experimental testing, which demands high precision machining practices as well as reproducible assembly procedures. This can be a very time-consuming, expensive, and error-prone undertaking. Aside from the unit-to-unit variances in dimensions between prototypes, the repeatability of material properties (e.g., dielectric constant and resistivity) in this frequency band is difficult to measure, predict, and ensure. Computers have no such repeatability problems, and run-to-run differences can be predefined, and subsequently analyzed. The computational limitations include setup difficulty, computer time, computer power, and fidelity of the calculation. For W-band devices with 1% or lower bandwidth, fidelity of the numerical solution is critical in the search for ``first-pass design success" capability. The codes have to not only be up to the task, but the appropriate application of these codes becomes an essential ingredient to predicting the accuracy of the results. These issues as well as cross validation between computational models will be discussed. Several recent simulation results of W-band devices will be presented, along with comparisons with data. These will include the NRL/Litton/CPI gyroklystron input coupler and several CPI Coupled Cavity Tube designs.

  11. The Virtual Radiopharmacy Laboratory: A 3-D Simulation for Distance Learning

    ERIC Educational Resources Information Center

    Alexiou, Antonios; Bouras, Christos; Giannaka, Eri; Kapoulas, Vaggelis; Nani, Maria; Tsiatsos, Thrasivoulos

    2004-01-01

    This article presents Virtual Radiopharmacy Laboratory (VR LAB), a virtual laboratory accessible through the Internet. VR LAB is designed and implemented in the framework of the VirRAD European project. This laboratory represents a 3D simulation of a radio-pharmacy laboratory, where learners, represented by 3D avatars, can experiment on…

  12. 3D Direct Simulation Monte Carlo Modeling of the Spacecraft Environment of Rosetta

    NASA Astrophysics Data System (ADS)

    Bieler, A. M.; Tenishev, V.; Fougere, N.; Gombosi, T. I.; Hansen, K. C.; Combi, M. R.; Huang, Z.; Jia, X.; Toth, G.; Altwegg, K.; Wurz, P.; Jäckel, A.; Le Roy, L.; Gasc, S.; Calmonte, U.; Rubin, M.; Tzou, C. Y.; Hässig, M.; Fuselier, S.; De Keyser, J.; Berthelier, J. J.; Mall, U. A.; Rème, H.; Fiethe, B.; Balsiger, H.

    2014-12-01

    The European Space Agency's Rosetta mission is the first to escort a comet over an extended time as the comet makes its way through the inner solar system. The ROSINA instrument suite consisting of a double focusing mass spectrometer, a time of flight mass spectrometer and a pressure sensor, will provide temporally and spatially resolved data on the comet's volatile inventory. The effect of spacecraft outgassing is well known and has been measured with the ROSINA instruments onboard Rosetta throughout the cruise phase. The flux of released neutral gas originating from the spacecraft cannot be distinguished from the cometary signal by the mass spectrometers and varies significantly with solar illumination conditions. For accurate interpretation of the instrument data, a good understanding of spacecraft outgassing is necessary. In this talk we present results simulating the spacecraft environment with the Adaptive Mesh Particle Simulator (AMPS) code. AMPS is a direct simulation monte carlo code that includes multiple species in a 3D adaptive mesh to describe a full scale model of the spacecraft environment. We use the triangulated surface model of the spacecraft to implement realistic outgassing rates for different areas on the surface and take shadowing effects in consideration. The resulting particle fluxes are compared to the measurements of the ROSINA experiment and implications for ROSINA measurements and data analysis are discussed. Spacecraft outgassing has implications for future space missions to rarefied atmospheres as it imposes a limit on the detection of various species.

  13. Measuring the orientation and rotation rate of 3D printed particles in turbulent flow

    NASA Astrophysics Data System (ADS)

    Voth, Greg; Marcus, Guy G.; Parsa, Shima; Kramel, Stefan; Ni, Rui; Cole, Brendan

    2014-11-01

    The orientation distribution and rotations of anisotropic particles plays a key role in many applications ranging from icy clouds to papermaking and drag reduction in pipe flow. Experimental access to time resolved orientations of anisotropic particles has not been easy to achieve. We have found that 3D printing technology can be used to fabricate a wide range of particle shapes with smallest dimension down to 300 μm. So far we have studied rods, crosses, jacks, tetrads, and helical shapes. We extract the particle orientations from stereoscopic video images using a method of least squares optimization in Euler angle space. We find that in turbulence the orientation and rotation rate of many particles can be understood using a simple picture of alignment of both the vorticity and a long axis of the particle with the Lagrangian stretching direction of the flow. This research is supported by NSF Grant DMR-1208990.

  14. Measuring the orientation and rotation rate of 3D printed particles in turbulent flow

    NASA Astrophysics Data System (ADS)

    Voth, Greg; Kramel, Stefan; Cole, Brendan

    2015-03-01

    The orientation distribution and rotations of anisotropic particles plays a key role in many applications ranging from icy clouds to papermaking and drag reduction in pipe flow. Experimental access to time resolved orientations of anisotropic particles has not been easy to achieve. We have found that 3D printing technology can be used to fabricate a wide range of particle shapes with smallest dimension down to 300 ?m. So far we have studied rods, crosses, jacks, tetrads, and helical shapes. We extract the particle orientations from stereoscopic video images using a method of least squares optimization in Euler angle space. We find that in turbulence the orientation and rotation rate of many particles can be understood using a simple picture of alignment of both the vorticity and a long axis of the particle with the Lagrangian stretching direction of the flow.

  15. 3D Plasma Clusters: Analysis of dynamical evolution and individual particle interaction

    SciTech Connect

    Antonova, T.; Thomas, H. M.; Morfill, G. E.; Annaratone, B. M.

    2008-09-07

    3D plasma clusters (up to 100 particles) have been built inside small (32 mm{sup 3}) plasma volume in gravity. It has been estimated that the external confinement has a negligible influence on the processes inside the clusters. At such conditions the analysis of dynamical evolution and individual particle interactions have shown that the binary interaction among particles in addition to the repelling Coulomb force exhibits also an attractive part. The tendency of the systems to approach the state with minimum energy by rearranging particles inside has been detected. The measured 63 particles' cluster vibrations are in close agreement with vibrations of a drop with surface tension. This indicates that even a 63 particle cluster already exhibits properties normally associated with the cooperative regime.

  16. Development of a 3D to 1D Particle Transport Model to Predict Deposition in the Lungs

    NASA Astrophysics Data System (ADS)

    Oakes, Jessica M.; Grandmont, Celine; Shadden, Shawn C.; Vignon-Clementel, Irene E.

    2014-11-01

    Aerosolized particles are commonly used for therapeutic drug delivery as they can be delivered to the body systemically or be used to treat lung diseases. Recent advances in computational resources have allowed for sophisticated pulmonary simulations, however it is currently impossible to solve for airflow and particle transport for all length and time scales of the lung. Instead, multi-scale methods must be used. In our recent work, where computational methods were employed to solve for airflow and particle transport in the rat airways (Oakes et al. (2014), Annals of Biomedical Engineering 42, 899), the number of particles to exit downstream of the 3D domain was determined. In this current work, the time-dependent Lagrangian description of particles was used to numerically solve a 1D convection-diffusion model (trumpet model, Taulbee and Yu (1975), Journal of Applied Physiology, 38, 77) parameterized specifically for the lung. The expansion of the airway dimensions was determined based on data collected from our aerosol exposure experiments (Oakes et al. (2014), Journal of Applied Physiology, 116, 1561). This 3D-1D framework enables us to predict the fate of particles in the whole lung. This work was supported by the Whitaker Foundation at the IIE, a INRIA Associated Team Postdoc Grant, and a UC Presidential Fellowship.

  17. Recent advances in 3D computed tomography techniques for simulation and navigation in hepatobiliary pancreatic surgery.

    PubMed

    Uchida, Masafumi

    2014-04-01

    A few years ago it could take several hours to complete a 3D image using a 3D workstation. Thanks to advances in computer science, obtaining results of interest now requires only a few minutes. Many recent 3D workstations or multimedia computers are equipped with onboard 3D virtual patient modeling software, which enables patient-specific preoperative assessment and virtual planning, navigation, and tool positioning. Although medical 3D imaging can now be conducted using various modalities, including computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasonography (US) among others, the highest quality images are obtained using CT data, and CT images are now the most commonly used source of data for 3D simulation and navigation image. If the 2D source image is bad, no amount of 3D image manipulation in software will provide a quality 3D image. In this exhibition, the recent advances in CT imaging technique and 3D visualization of the hepatobiliary and pancreatic abnormalities are featured, including scan and image reconstruction technique, contrast-enhanced techniques, new application of advanced CT scan techniques, and new virtual reality simulation and navigation imaging. PMID:24464989

  18. Multi-scale self-organisation of edge plasma turbulent transport in 3D global simulations

    NASA Astrophysics Data System (ADS)

    Tamain, P.; Ghendrih, Ph; Bufferand, H.; Ciraolo, G.; Colin, C.; Fedorczak, N.; Nace, N.; Schwander, F.; Serre, E.

    2015-05-01

    The 3D global edge turbulence code TOKAM3X is used to study the properties of edge particle turbulent transport in circular limited plasmas, including both closed and open flux surfaces. Turbulence is driven by an incoming particle flux from the core plasma and no scale separation between the equilibrium and the fluctuations is assumed. Simulations show the existence of a complex self-organization of turbulence transport coupling scales ranging from a few Larmor radii up to the machine scale. Particle transport is largely dominated by small scale turbulence with fluctuations forming quasi field-aligned filaments. Radial particle transport is intermittent and associated with the propagation of coherent structures on long distances via avalanches. Long range correlations are also found in the poloidal and toroidal direction. The statistical properties of fluctuations vary with the radial and poloidal directions, with larger fluctuation levels and intermittency found in the outboard scrape-off layer (SOL). Radial turbulent transport is strongly ballooned, with 90% of the flux at the separatrix flowing through the low-field side. One of the main consequences is the existence of quasi-sonic asymmetric parallel flows driving a net rotation of the plasma. Simulations also show the spontaneous onset of an intermittent E × B rotation characterized by a larger shear at the separatrix. Strong correlation is found between the turbulent particle flux and the E × B flow shear in a phenomenology reminiscent of H-mode physics. The poloidal position of the limiter is a key player in the observed dynamics.

  19. Transfer-printing and host-guest properties of 3D supramolecular particle structures.

    PubMed

    Ling, Xing Yi; Phang, In Yee; Reinhoudt, David N; Vancso, G Julius; Huskens, Jurriaan

    2009-04-01

    Mechanically robust and crystalline supramolecular particle structures have been constructed by decoupling nanoparticle assembly and supramolecular glue infiltration into a sequential process. First, beta-cyclodextrin (CD)-functionalized polystyrene particles (d approximately 500 nm) were assembled on a CD-functionalized surface via convective assembly to form highly ordered, but mechanically unstable, particle crystals. Subsequently, the crystals were infiltrated by a solution of adamantyl-functionalized dendrimers, functioning as a supramolecular glue to bind neighboring particles together and to couple the entire particle crystal to the CD surface, both in a noncovalent manner. The supramolecular particle crystals are highly robust, as witnessed by their ability to withstand agitation by ultrasonication. When assembled on a poly(dimethylsiloxane) (PDMS) stamp, the dendrimer-infiltrated particle crystals could be transfer-printed onto a CD-functionalized target surface. By variation of the geometry and size of the PDMS stamps, single particle lines, interconnected particle rings, and V-shaped particle assemblies were obtained. The particle structures served as 3D receptors for the binding of (multiple) complementary guest molecules, indicating that the supramolecular host functionalities of the particle crystals were retained throughout the fabrication process. PMID:20356024

  20. Ultra-high-speed 3D astigmatic particle tracking velocimetry: application to particle-laden supersonic impinging jets

    NASA Astrophysics Data System (ADS)

    Buchmann, N. A.; Cierpka, C.; Kähler, C. J.; Soria, J.

    2014-11-01

    The paper demonstrates ultra-high-speed three-component, three-dimensional (3C3D) velocity measurements of micron-sized particles suspended in a supersonic impinging jet flow. Understanding the dynamics of individual particles in such flows is important for the design of particle impactors for drug delivery or cold gas dynamic spray processing. The underexpanded jet flow is produced via a converging nozzle, and micron-sized particles ( d p = 110 μm) are introduced into the gas flow. The supersonic jet impinges onto a flat surface, and the particle impact velocity and particle impact angle are studied for a range of flow conditions and impingement distances. The imaging system consists of an ultra-high-speed digital camera (Shimadzu HPV-1) capable of recording rates of up to 1 Mfps. Astigmatism particle tracking velocimetry (APTV) is used to measure the 3D particle position (Cierpka et al., Meas Sci Technol 21(045401):13, 2010) by coding the particle depth location in the 2D images by adding a cylindrical lens to the high-speed imaging system. Based on the reconstructed 3D particle positions, the particle trajectories are obtained via a higher-order tracking scheme that takes advantage of the high temporal resolution to increase robustness and accuracy of the measurement. It is shown that the particle velocity and impingement angle are affected by the gas flow in a manner depending on the nozzle pressure ratio and stand-off distance where higher pressure ratios and stand-off distances lead to higher impact velocities and larger impact angles.

  1. 2D and 3D Mass Transfer Simulations in β Lyrae System

    NASA Astrophysics Data System (ADS)

    Nazarenko, V. V.; Glazunova, L. V.; Karetnikov, V. G.

    2001-12-01

    2D and 3D mass transfer simulations of the mass transfer in β Lyrae binary system. We have received that from a point L3 40 per cent of mass transfer from L1-point is lost.The structure of a gas envelope, around system is calculated.3-D mass transfer simulations has shown presence the spiral shock in the disk around primary star's and a jet-like structures (a mass flow in vertical direction) over a stream.

  2. 3D simulations of multipacting in the 56 MHz SRF cavity

    SciTech Connect

    Wu Q.; Belomestnykh, S.; Ge, L.; Ko, K.; Li, Z.; Ng, C.; Xiao, L.

    2012-05-20

    The 56 MHz SRF Quarter-Wave Resonator (QWR) is designed for RHIC as a storage cavity to improve the collider performance. 2D multipacting simulation has been done for the cavity alone. Ripples were added to the outer body of the cavity for multipacting suppression based on the simulation findings. During operation, there will be four higher order mode (HOM) couplers. All of these components will be exposed to high RF fields. In this paper we compare 2D and 3D codes simulation results for multipacting in the cavity. We also report 3D simulation results for multipacting simulation at the couplers.

  3. Characterization of an SRF gun: a 3D full wave simulation

    SciTech Connect

    Wang, E.; Ben-Zvi, I.; Wang, J.

    2011-03-28

    We characterized a BNL 1.3GHz half-cell SRF gun is tested for GaAs photocathode. The gun already was simulated several years ago via two-dimensional (2D) numerical codes (i.e., Superfish and Parmela) with and without the beam. In this paper, we discuss our investigation of its characteristics using a three dimensional (3D) full-wave code (CST STUDIO SUITE{trademark}).The input/pickup couplers are sited symmetrically on the same side of the gun at an angle of 180{sup o}. In particular, the inner conductor of the pickup coupler is considerably shorter than that of the input coupler. We evaluated the cross-talk between the beam (trajectory) and the signal on the input coupler compared our findings with published results based on analytical models. The CST STUDIO SUITE{trademark} also was used to predict the field within the cavity; particularly, a combination of transient/eigenmode solvers was employed to accurately construct the RF field for the particles, which also includes the effects of the couplers. Finally, we explored the beam's dynamics with a particle in cell (PIC) simulation, validated the results and compare them with 2D code result.

  4. 3D real-time visualization of blood flow in cerebral aneurysms by light field particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Carlsohn, Matthias F.; Kemmling, André; Petersen, Arne; Wietzke, Lennart

    2016-04-01

    Cerebral aneurysms require endovascular treatment to eliminate potentially lethal hemorrhagic rupture by hemostasis of blood flow within the aneurysm. Devices (e.g. coils and flow diverters) promote homeostasis, however, measurement of blood flow within an aneurysm or cerebral vessel before and after device placement on a microscopic level has not been possible so far. This would allow better individualized treatment planning and improve manufacture design of devices. For experimental analysis, direct measurement of real-time microscopic cerebrovascular flow in micro-structures may be an alternative to computed flow simulations. An application of microscopic aneurysm flow measurement on a regular basis to empirically assess a high number of different anatomic shapes and the corresponding effect of different devices would require a fast and reliable method at low cost with high throughout assessment. Transparent three dimensional 3D models of brain vessels and aneurysms may be used for microscopic flow measurements by particle image velocimetry (PIV), however, up to now the size of structures has set the limits for conventional 3D-imaging camera set-ups. On line flow assessment requires additional computational power to cope with the processing large amounts of data generated by sequences of multi-view stereo images, e.g. generated by a light field camera capturing the 3D information by plenoptic imaging of complex flow processes. Recently, a fast and low cost workflow for producing patient specific three dimensional models of cerebral arteries has been established by stereo-lithographic (SLA) 3D printing. These 3D arterial models are transparent an exhibit a replication precision within a submillimeter range required for accurate flow measurements under physiological conditions. We therefore test the feasibility of microscopic flow measurements by PIV analysis using a plenoptic camera system capturing light field image sequences. Averaging across a sequence of

  5. 3D numerical simulations of dispersion of volcanic ash using a Lagrangian model

    NASA Astrophysics Data System (ADS)

    Suzuki, Yujiro; Koyaguchi, Takehiro

    2014-05-01

    Dispersion of volcanic ash largely depends on the atmospheric wind speed and eruption intensity. In general, when the atmospheric wind is weak and/or eruption intensity is strong (i.e., magma discharge rate is small), the volcanic plume is characterized by the formation of umbrella cloud and the particles (i.e., volcanic ashes) are transported by the gravity current of umbrella cloud. On the other hand, if the wind is strong and/or eruption intensity is weak, the volcanic plume tends to be distorted by wind and the particles are drifted mainly by the wind. Because these effects of gravity current and wind also change depending on the particle size, it is difficult to quantitatively predict the distributions of particles suspended in the atmosphere and those deposited on the ground. In this study, we are developing a 3-D numerical model which directly simulates the ash transport and deposition. The model is designed to simulate the injection of a mixture of solid pyroclasts and volcanic gas from a circular vent above a flat surface in a stratified atmosphere, using a combination of a pseudo-gas model for fluid motion and a Lagrangian model for particle motion. During fluid dynamics calculations, we ignore the separation of solid pyroclasts from the eruption cloud, treating an eruption cloud as a single gas with a density calculated using a mixing ratio between ejected material and entrained air (Suzuki et al., 2005, JGR). In order to calculate the location and movement of ash particles, we employ Lagrangian marker particles of various sizes and densities. The marker particles are ejected from the vent with the same velocity of the eruption cloud every 2 sec. The particles are accelerated or decelerated by the drag force on the spheres and fall to the ground with their terminal velocities. We carried out a simulation of a small-scale eruption in the strong wind fields with the magma discharge rate of 2.5 x 106 kg/s. The rising plume is largely distorted by wind and

  6. Functional Stereology for 3D Particle Size Distributions from 2D Observations: a Practical Approach

    NASA Astrophysics Data System (ADS)

    Proussevitch, A. A.; Sahagian, D. L.; Jutzeler, M.

    2010-12-01

    Functional stereology applies known deconvolution techniques to obtain 3D size distributions from 2D cross-section data based on an assumption that both 2D and 3D statistics have known distribution functions with unknown parameters. A new stereological approach enables us to solve this problem by utilizing function minimization to find parameters of the distribution functions. There is no limit to continuous distribution function types that could be used, such as Gaussian, Logistic, Weibull, Gamma, and others. As compared to previously known 2D to 3D conversion methods (e.g. Sahagian and Proussevitch, 1998), functional stereology has much greater practical application to non-spherical particles/objects because it is free of uncontrollable error propagation for all particles shapes. The new practical method of functional stereology has been implemented in Stereonet software adapted for both a) direct logarithmic scales of particle/voids volumes, and b) Phi units of linear dimensions (-log2 of size). Applications of the method include distribution of voids/bubbles in all types of volcanic rocks, pore networks in sedimentary rocks, mineral and grain sizes, volcanic clasts, breccia, and texture features of a wide range of rock formations. Such applications demonstrate utility of this functional stereology approach.

  7. The Effects of 3D Computer Simulation on Biology Students' Achievement and Memory Retention

    ERIC Educational Resources Information Center

    Elangovan, Tavasuria; Ismail, Zurida

    2014-01-01

    A quasi experimental study was conducted for six weeks to determine the effectiveness of two different 3D computer simulation based teaching methods, that is, realistic simulation and non-realistic simulation on Form Four Biology students' achievement and memory retention in Perak, Malaysia. A sample of 136 Form Four Biology students in Perak,…

  8. Fast and efficient particle reconstruction on a 3D grid using sparsity

    NASA Astrophysics Data System (ADS)

    Cornic, P.; Champagnat, F.; Cheminet, A.; Leclaire, B.; Le Besnerais, G.

    2015-03-01

    We propose an approach for efficient localization and intensity reconstruction of particles on a 3D grid based on sparsity principles. The computational complexity of the method is limited by using the particle volume reconstruction paradigm (Champagnat et al. in Meas Sci Technol 25, 2014) and a reduction in the problem dimension. Tests on synthetic and experimental data show that the proposed method leads to more efficient detections and to reconstructions of higher quality than classical tomoPIV approaches on a large range of seeding densities, up to ppp ≈ 0.12.

  9. 3D multiple-point statistics simulation using 2D training images

    NASA Astrophysics Data System (ADS)

    Comunian, A.; Renard, P.; Straubhaar, J.

    2012-03-01

    One of the main issues in the application of multiple-point statistics (MPS) to the simulation of three-dimensional (3D) blocks is the lack of a suitable 3D training image. In this work, we compare three methods of overcoming this issue using information coming from bidimensional (2D) training images. One approach is based on the aggregation of probabilities. The other approaches are novel. One relies on merging the lists obtained using the impala algorithm from diverse 2D training images, creating a list of compatible data events that is then used for the MPS simulation. The other (s2Dcd) is based on sequential simulations of 2D slices constrained by the conditioning data computed at the previous simulation steps. These three methods are tested on the reproduction of two 3D images that are used as references, and on a real case study where two training images of sedimentary structures are considered. The tests show that it is possible to obtain 3D MPS simulations with at least two 2D training images. The simulations obtained, in particular those obtained with the s2Dcd method, are close to the references, according to a number of comparison criteria. The CPU time required to simulate with the method s2Dcd is from two to four orders of magnitude smaller than the one required by a MPS simulation performed using a 3D training image, while the results obtained are comparable. This computational efficiency and the possibility of using MPS for 3D simulation without the need for a 3D training image facilitates the inclusion of MPS in Monte Carlo, uncertainty evaluation, and stochastic inverse problems frameworks.

  10. Local characterization of hindered Brownian motion by using digital video microscopy and 3D particle tracking.

    PubMed

    Dettmer, Simon L; Keyser, Ulrich F; Pagliara, Stefano

    2014-02-01

    In this article we present methods for measuring hindered Brownian motion in the confinement of complex 3D geometries using digital video microscopy. Here we discuss essential features of automated 3D particle tracking as well as diffusion data analysis. By introducing local mean squared displacement-vs-time curves, we are able to simultaneously measure the spatial dependence of diffusion coefficients, tracking accuracies and drift velocities. Such local measurements allow a more detailed and appropriate description of strongly heterogeneous systems as opposed to global measurements. Finite size effects of the tracking region on measuring mean squared displacements are also discussed. The use of these methods was crucial for the measurement of the diffusive behavior of spherical polystyrene particles (505 nm diameter) in a microfluidic chip. The particles explored an array of parallel channels with different cross sections as well as the bulk reservoirs. For this experiment we present the measurement of local tracking accuracies in all three axial directions as well as the diffusivity parallel to the channel axis while we observed no significant flow but purely Brownian motion. Finally, the presented algorithm is suitable also for tracking of fluorescently labeled particles and particles driven by an external force, e.g., electrokinetic or dielectrophoretic forces. PMID:24593372

  11. Local characterization of hindered Brownian motion by using digital video microscopy and 3D particle tracking

    NASA Astrophysics Data System (ADS)

    Dettmer, Simon L.; Keyser, Ulrich F.; Pagliara, Stefano

    2014-02-01

    In this article we present methods for measuring hindered Brownian motion in the confinement of complex 3D geometries using digital video microscopy. Here we discuss essential features of automated 3D particle tracking as well as diffusion data analysis. By introducing local mean squared displacement-vs-time curves, we are able to simultaneously measure the spatial dependence of diffusion coefficients, tracking accuracies and drift velocities. Such local measurements allow a more detailed and appropriate description of strongly heterogeneous systems as opposed to global measurements. Finite size effects of the tracking region on measuring mean squared displacements are also discussed. The use of these methods was crucial for the measurement of the diffusive behavior of spherical polystyrene particles (505 nm diameter) in a microfluidic chip. The particles explored an array of parallel channels with different cross sections as well as the bulk reservoirs. For this experiment we present the measurement of local tracking accuracies in all three axial directions as well as the diffusivity parallel to the channel axis while we observed no significant flow but purely Brownian motion. Finally, the presented algorithm is suitable also for tracking of fluorescently labeled particles and particles driven by an external force, e.g., electrokinetic or dielectrophoretic forces.

  12. LEWICE3D/GlennHT Particle Analysis of the Honeywell Al502 Low Pressure Compressor

    NASA Technical Reports Server (NTRS)

    Bidwell, Colin S.; Rigby, David L.

    2015-01-01

    A flow and ice particle trajectory analysis was performed for the booster of the Honeywell AL502 engine. The analysis focused on two closely related conditions one of which produced a rollback and another which did not rollback during testing in the Propulsion Systems Lab at NASA Glenn Research Center. The flow analysis was generated using the NASA Glenn GlennHT flow solver and the particle analysis was generated using the NASA Glenn LEWICE3D v3.56 ice accretion software. The flow and particle analysis used a 3D steady flow, mixing plane approach to model the transport of flow and particles through the engine. The inflow conditions for the rollback case were: airspeed, 145 ms; static pressure, 33,373 Pa; static temperature, 253.3 K. The inflow conditions for the non-roll-back case were: airspeed, 153 ms; static pressure, 34,252 Pa; static temperature, 260.1 K. Both cases were subjected to an ice particle cloud with a median volume diameter of 24 microns, an ice water content of 2.0 gm3 and a relative humidity of 100 percent. The most significant difference between the rollback and non-rollback conditions was the inflow static temperature which was 6.8 K higher for the non-rollback case.

  13. Local characterization of hindered Brownian motion by using digital video microscopy and 3D particle tracking

    SciTech Connect

    Dettmer, Simon L.; Keyser, Ulrich F.; Pagliara, Stefano

    2014-02-15

    In this article we present methods for measuring hindered Brownian motion in the confinement of complex 3D geometries using digital video microscopy. Here we discuss essential features of automated 3D particle tracking as well as diffusion data analysis. By introducing local mean squared displacement-vs-time curves, we are able to simultaneously measure the spatial dependence of diffusion coefficients, tracking accuracies and drift velocities. Such local measurements allow a more detailed and appropriate description of strongly heterogeneous systems as opposed to global measurements. Finite size effects of the tracking region on measuring mean squared displacements are also discussed. The use of these methods was crucial for the measurement of the diffusive behavior of spherical polystyrene particles (505 nm diameter) in a microfluidic chip. The particles explored an array of parallel channels with different cross sections as well as the bulk reservoirs. For this experiment we present the measurement of local tracking accuracies in all three axial directions as well as the diffusivity parallel to the channel axis while we observed no significant flow but purely Brownian motion. Finally, the presented algorithm is suitable also for tracking of fluorescently labeled particles and particles driven by an external force, e.g., electrokinetic or dielectrophoretic forces.

  14. Forward-looking infrared 3D target tracking via combination of particle filter and SIFT

    NASA Astrophysics Data System (ADS)

    Li, Xing; Cao, Zhiguo; Yan, Ruicheng; Li, Tuo

    2013-10-01

    Aiming at the problem of tracking 3D target in forward-looking infrared (FLIR) image, this paper proposes a high-accuracy robust tracking algorithm based on SIFT and particle filter. The main contribution of this paper is the proposal of a new method of estimating the affine transformation matrix parameters based on Monte Carlo methods of particle filter. At first, we extract SIFT features on infrared image, and calculate the initial affine transformation matrix with optimal candidate key points. Then we take affine transformation parameters as particles, and use SIR (Sequential Importance Resampling) particle filter to estimate the best position, thus implementing our algorithm. The experiments demonstrate that our algorithm proves to be robust with high accuracy.

  15. Simulation of abrasive flow machining process for 2D and 3D mixture models

    NASA Astrophysics Data System (ADS)

    Dash, Rupalika; Maity, Kalipada

    2015-12-01

    Improvement of surface finish and material removal has been quite a challenge in a finishing operation such as abrasive flow machining (AFM). Factors that affect the surface finish and material removal are media viscosity, extrusion pressure, piston velocity, and particle size in abrasive flow machining process. Performing experiments for all the parameters and accurately obtaining an optimized parameter in a short time are difficult to accomplish because the operation requires a precise finish. Computational fluid dynamics (CFD) simulation was employed to accurately determine optimum parameters. In the current work, a 2D model was designed, and the flow analysis, force calculation, and material removal prediction were performed and compared with the available experimental data. Another 3D model for a swaging die finishing using AFM was simulated at different viscosities of the media to study the effects on the controlling parameters. A CFD simulation was performed by using commercially available ANSYS FLUENT. Two phases were considered for the flow analysis, and multiphase mixture model was taken into account. The fluid was considered to be a

  16. Multi-scale 3D simulation of lightning and thunderstorm electrodynamics

    NASA Astrophysics Data System (ADS)

    Kabirzadeh, R.; Lehtinen, N. G.; Liang, C.; Cohen, M.; Inan, U.

    2014-12-01

    Despite centuries studying thunderstorm electrodynamics, our understanding of these phenomena remains limited. The difficulty lies partly in the large number of processes and their mutual dependency and the wide range of temporal and the spatial scales involved. In this study we combine two numerical models to move toward a simulation that addresses these broad scales. First, we use a 3D numerical model to calculate the large scale quasi-electrostatic (QES) fields and charge distributions built up by updrafts in the thundercloud. This model self-consistently accounts for the conductivities, particle densities, large scale currents and charging mechanisms inside a thundercloud in the atmosphere. Second, we use a time-domain fractal lightning (TDFL) model developed that takes into account both the thermodynamics and electrodynamics of leader development and the return stroke on small time and spatial scales (Liang et al. 2014). The QES model simulates slow thunderstorm charging dynamics, and then passes the state to the TDFL model when a flash is ready to trigger. Using this combined simulation, we explain some recently observed patterns of lightning inside a thunderstorm and within a flash (e.g. Zoghzoghy et al. 2013, 2014). We attempt to constrain properties of the thundercloud like the size and shape of the charge pockets removed from the thundercloud, the flash rate and updraft currents, the relative occurrence rate of different types of lightning, and the cloud charge distribution structure effects on the lightning type.

  17. 3D electromagnetic simulation of spatial autoresonance acceleration of electron beams

    NASA Astrophysics Data System (ADS)

    Dugar-Zhabon, V. D.; González, J. D.; Orozco, E. A.

    2016-02-01

    The results of full electromagnetic simulations of the electron beam acceleration by a TE 112 linear polarized electromagnetic field through Space Autoresonance Acceleration mechanism are presented. In the simulations, both the self-sustaned electric field and selfsustained magnetic field produced by the beam electrons are included into the elaborated 3D Particle in Cell code. In this system, the space profile of the magnetostatic field maintains the electron beams in the acceleration regime along their trajectories. The beam current density evolution is calculated applying the charge conservation method. The full magnetic field in the superparticle positions is found by employing the trilinear interpolation of the mesh node data. The relativistic Newton-Lorentz equation presented in the centered finite difference form is solved using the Boris algorithm that provides visualization of the beam electrons pathway and energy evolution. A comparison between the data obtained from the full electromagnetic simulations and the results derived from the motion equation depicted in an electrostatic approximation is carried out. It is found that the self-sustained magnetic field is a factor which improves the resonance phase conditions and reduces the beam energy spread.

  18. NVision: A 3D Visualization Environment for N-Body Simulations

    NASA Astrophysics Data System (ADS)

    Markiel, J. A.

    2000-05-01

    NVision: A 3D Visualization Environment for N-Body Simulations We are developing a set of packages for 3D visualization and analysis of our numerical N-body simulations. These tools are intended to be generalizable to a wide range of related problems including cosmological, planetary dynamics, and molecular dynamics simulations. The applications and source code will be fully available to the community. To prototype this project we have adopted the Java platform with the newly released Java3D extension to take advantage of its portability, object-oriented environment, and availability of extensive documentation and class libraries. We will describe the goals and design principles of the project and demo the currently implemented features, including visualization of cosmological simulations and the simulated collision of two rubble-pile asteroids. This research is supported by NSF grants AST99-73209 and AST99-79891.

  19. Simulation of bacteria transport processes in a river with Flow3D

    NASA Astrophysics Data System (ADS)

    Schwarzwälder, Kordula; Bui, Minh Duc; Rutschmann, Peter

    2014-05-01

    Water quality aspects are getting more and more important due to the European water Framework directive (WFD). One problem related to this topic is the inflow of untreated wastewater due to combined sewer overflows into a river. The wastewater mixture contains even bacteria like E. coli and Enterococci which are markers for water quality. In our work we investigated the transport of these bacteria in river Isar by using a large-scale flume in the outside area of our lab (Oskar von Miller Institute). Therefor we could collect basic data and knowledge about the processes which occur during bacteria sedimentation and remobilisation. In our flume we could use the real grain with the exact size distribution curve as in the river Isar which we want to simulate and we had the chance to nurture a biofilm which is realistic for the analysed situation. This biofilm plays an important role in the remobilisation processes, because the bacteria are hindered to be washed out back into the bulk phase as fast and in such an amount as this would happen without biofilm. The results of our experiments are now used for a module in the 3D software Flow3D to simulate the effects of a point source inlet of raw wastewater on the water quality. Therefor we have to implement the bacteria not as a problem of concentration with advection and diffusion but as single particles which can be inactivated during the process of settling and need to be hindered from remobilisation by the biofilm. This biofilm has special characteristic, it is slippery and has a special thickness which influences the chance of bacteria being removed. To achieve realistic results we have to include the biofilm with more than a probabilistic-tool to make sure that our module is transferable. The module should be as flexible as possible to be improved step by step with increasing quality of dataset.

  20. Development and Characterization of Embedded Sensory Particles Using Multi-Scale 3D Digital Image Correlation

    NASA Technical Reports Server (NTRS)

    Cornell, Stephen R.; Leser, William P.; Hochhalter, Jacob D.; Newman, John A.; Hartl, Darren J.

    2014-01-01

    A method for detecting fatigue cracks has been explored at NASA Langley Research Center. Microscopic NiTi shape memory alloy (sensory) particles were embedded in a 7050 aluminum alloy matrix to detect the presence of fatigue cracks. Cracks exhibit an elevated stress field near their tip inducing a martensitic phase transformation in nearby sensory particles. Detectable levels of acoustic energy are emitted upon particle phase transformation such that the existence and location of fatigue cracks can be detected. To test this concept, a fatigue crack was grown in a mode-I single-edge notch fatigue crack growth specimen containing sensory particles. As the crack approached the sensory particles, measurements of particle strain, matrix-particle debonding, and phase transformation behavior of the sensory particles were performed. Full-field deformation measurements were performed using a novel multi-scale optical 3D digital image correlation (DIC) system. This information will be used in a finite element-based study to determine optimal sensory material behavior and density.

  1. 3D printing enables separation of orthogonal functions within a hydrogel particle.

    PubMed

    Raman, Ritu; Clay, Nicholas E; Sen, Sanjeet; Melhem, Molly; Qin, Ellen; Kong, Hyunjoon; Bashir, Rashid

    2016-06-01

    Multifunctional particles with distinct physiochemical phases are required by a variety of applications in biomedical engineering, such as diagnostic imaging and targeted drug delivery. This motivates the development of a repeatable, efficient, and customizable approach to manufacturing particles with spatially segregated bioactive moieties. This study demonstrates a stereolithographic 3D printing approach for designing and fabricating large arrays of biphasic poly (ethylene glycol) diacrylate (PEGDA) gel particles. The fabrication parameters governing the physical and biochemical properties of multi-layered particles are thoroughly investigated, yielding a readily tunable approach to manufacturing customizable arrays of multifunctional particles. The advantage in spatially organizing functional epitopes is examined by loading superparamagnetic iron oxide nanoparticles (SPIONs) and bovine serum albumin (BSA) in separate layers of biphasic PEGDA gel particles and examining SPION-induced magnetic resonance (MR) contrast and BSA-release kinetics. Particles with spatial segregation of functional moieties have demonstrably higher MR contrast and BSA release. Overall, this study will contribute significant knowledge to the preparation of multifunctional particles for use as biomedical tools. PMID:27215416

  2. Uniformly spaced 3D modeling of human face from two images using parallel particle swarm optimization

    NASA Astrophysics Data System (ADS)

    Chang, Yau-Zen; Hou, Jung-Fu; Tsao, Yi Hsiang; Lee, Shih-Tseng

    2011-09-01

    This paper proposes a scheme for finding the correspondence between uniformly spaced locations on the images of human face captured from different viewpoints at the same instant. The correspondence is dedicated for 3D reconstruction to be used in the registration procedure for neurosurgery where the exposure to projectors must be seriously restricted. The approach utilizes structured light to enhance patterns on the images and is initialized with the scale-invariant feature transform (SIFT). Successive locations are found according to spatial order using a parallel version of the particle swarm optimization algorithm. Furthermore, false locations are singled out for correction by searching for outliers from fitted curves. Case studies show that the scheme is able to correctly generate 456 evenly spaced 3D coordinate points in 23 seconds from a single shot of projected human face using a PC with 2.66 GHz Intel Q9400 CPU and 4GB RAM.

  3. Longitudinal Measurement of Extracellular Matrix Rigidity in 3D Tumor Models Using Particle-tracking Microrheology

    PubMed Central

    El-Hamidi, Hamid; Celli, Jonathan P.

    2014-01-01

    The mechanical microenvironment has been shown to act as a crucial regulator of tumor growth behavior and signaling, which is itself remodeled and modified as part of a set of complex, two-way mechanosensitive interactions. While the development of biologically-relevant 3D tumor models have facilitated mechanistic studies on the impact of matrix rheology on tumor growth, the inverse problem of mapping changes in the mechanical environment induced by tumors remains challenging. Here, we describe the implementation of particle-tracking microrheology (PTM) in conjunction with 3D models of pancreatic cancer as part of a robust and viable approach for longitudinally monitoring physical changes in the tumor microenvironment, in situ. The methodology described here integrates a system of preparing in vitro 3D models embedded in a model extracellular matrix (ECM) scaffold of Type I collagen with fluorescently labeled probes uniformly distributed for position- and time-dependent microrheology measurements throughout the specimen. In vitro tumors are plated and probed in parallel conditions using multiwell imaging plates. Drawing on established methods, videos of tracer probe movements are transformed via the Generalized Stokes Einstein Relation (GSER) to report the complex frequency-dependent viscoelastic shear modulus, G*(ω). Because this approach is imaging-based, mechanical characterization is also mapped onto large transmitted-light spatial fields to simultaneously report qualitative changes in 3D tumor size and phenotype. Representative results showing contrasting mechanical response in sub-regions associated with localized invasion-induced matrix degradation as well as system calibration, validation data are presented. Undesirable outcomes from common experimental errors and troubleshooting of these issues are also presented. The 96-well 3D culture plating format implemented in this protocol is conducive to correlation of microrheology measurements with therapeutic

  4. Web-Based 3D and Haptic Interactive Environments for e-Learning, Simulation, and Training

    NASA Astrophysics Data System (ADS)

    Hamza-Lup, Felix G.; Sopin, Ivan

    Knowledge creation occurs in the process of social interaction. As our service-based society is evolving into a knowledge-based society, there is an acute need for more effective collaboration and knowledge-sharing systems to be used by geographically scattered people. We present the use of 3D components and standards, such as Web3D, in combination with the haptic paradigm, for e-Learning and simulation.

  5. Prototype Development Capabilities of 3D Spatial Interactions and Failures During Scenario Simulation

    SciTech Connect

    Steven Prescott; Ramprasad Sampath; Curtis Smith; Tony Koonce

    2014-09-01

    Computers have been used for 3D modeling and simulation, but only recently have computational resources been able to give realistic results in a reasonable time frame for large complex models. This report addressed the methods, techniques, and resources used to develop a prototype for using 3D modeling and simulation engine to improve risk analysis and evaluate reactor structures and components for a given scenario. The simulations done for this evaluation were focused on external events, specifically tsunami floods, for a hypothetical nuclear power facility on a coastline.

  6. An improved virtual aberration model to simulate mask 3D and resist effects

    NASA Astrophysics Data System (ADS)

    Kanaya, Reiji; Fujii, Koichi; Imai, Motokatsu; Matsuyama, Tomoyuki; Tsuzuki, Takao; Lin, Qun Ying

    2015-03-01

    As shrinkage of design features progresses, the difference in best focus positions among different patterns is becoming a fatal issue, especially when many patterns co-exist in a layer. The problem arises from three major factors: aberrations of projection optics, mask 3D topography effects, and resist thickness effects. Aberrations in projection optics have already been thoroughly investigated, but mask 3D topography effects and resist thickness effects are still under study. It is well known that mask 3D topography effects can be simulated by various Electro-magnetic Field (EMF) analysis methods. However, it is almost impossible to use them for full chip modeling because all of these methods are extremely computationally intensive. Consequently, they usually apply only to a limited range of mask patterns which are about tens of square micro meters in area. Resist thickness effects on best focus positions are rarely treated as a topic of lithography investigations. Resist 3D effects are treated mostly for resist profile prediction, which also requires an intensive EMF analysis when one needs to predict it accurately. In this paper, we present a simplified Virtual Aberration (VA) model to simulate both mask 3D induced effects and resist thickness effects. A conventional simulator, when applied with this simplified method, can factor in both mask 3D topography effects and resist thickness effects. Thus it can be used to model inter-pattern Best Focus Difference (BFD) issues with the least amount of rigorous EMF analysis.

  7. Effect of particle size in a colloidal hydrogel scaffold for 3D cell culture.

    PubMed

    Gu, Jianjun; Zhao, Yening; Guan, Ying; Zhang, Yongjun

    2015-12-01

    The in situ-forming colloidal hydrogels from the thermal gelation of poly(N-isopropylacrylamide) (PNIPAM) microgel dispersions have been exploited for 3D cell culture. The properties of the hydrogel scaffold need to be tuned to further improve its performance. In addition, cellular uptake of the microgel particles need to be reduced to avoid their potential undesired influence. For these purposes we systematically examined the effect of microgel particle size on the hydrogel scaffold. It was found that gel properties could be tuned via changing particle size. Increasing particle size reduces the gel strength and its syneresis degree, both of which are favorable for cell growth. Meanwhile increasing particle size could also reduce significantly the cellular uptake of the microgel particles. Microgel with a size of ~162 nm shows the highest cellular uptake, beyond which cellular uptake decreases with increasing particle size. Hydrogel scaffold from 300 nm microgel, with suitable physical properties and reduced cellular uptake, were successfully used for multicellular spheroid generation. PMID:26613865

  8. Fully Kinetic 3D Simulations of the Interaction of the Solar Wind with Mercury

    NASA Astrophysics Data System (ADS)

    Amaya, J.; Deca, J.; Lembege, B.; Lapenta, G.

    2015-12-01

    The planet Mercury has been studied by the space mission Mariner 10, in the 1970's, and by the MESSENGER mission launched in 2004. Interest in the first planet of the Solar System has now been renewed by the launch in 2017 of the BepiColombo mission. MESSENGER and BepiColombo give access to information about the local conditions of the magnetosphere of Mercury. This data must be evaluated in the context of the global interaction between the solar wind and the planet's magnetosphere. Global scale simulations of the planet's environment are necessary to fully understand the data gathered from in-situ measurements. We use three-dimensional simulations to support the scientific goals of the two missions. In contrast with the results based on MHD (Kabin et al., 2000) and hybrid codes (Kallio et Janhumen, 2003; Travnicek et al., 2007, 2010; Richer et al., 2012), the present work is based on the implicit moment Particle-in-Cell (PiC) method, which allows to use large time and space steps, while granting access to the dynamics of the smaller electron scales in the plasma. The purpose of these preliminary PIC simulations is to retrieve the top-level features of Mercury's magnetosphere and its frontiers. We compare the results obtained with the implicit moment PiC method against 3D hybrid simulations. We perform simulations of the global plasma environment of Mercury using the solar wind conditions measured by MESSENGER. We show that complex flows form around the planet, including the development of Kelvin-Helmoltz instabilities at the flanks. We evaluate the dynamics of the shock, magnetosheath, magnetopause, the reconnection areas, the formation of plasma sheet and magnetotail, and the variation of ion/electron plasma flows when crossing these frontiers. The simulations also give access to detailed information about the particle dynamics and their velocity distribution at locations that can be used for comparison with data from MESSENGER and later on with the forthcoming

  9. Structural response to 3D simulated earthquake motions in San Bernardino Valley

    USGS Publications Warehouse

    Safak, E.; Frankel, A.

    1994-01-01

    Structural repsonse to one- and three-dimensional (3D) simulated motions in San Bernardino Valley from a hypothetical earthquake along the San Andreas fault with moment magnitude 6.5 and rupture length of 30km is investigated. The results show that the ground motions and the structural response vary dramatically with the type of simulation and the location. -from Authors

  10. The plasma interaction of Enceladus: 3D hybrid simulations and comparison with Cassini MAG data

    NASA Astrophysics Data System (ADS)

    Kriegel, H.; Simon, S.; Müller, J.; Motschmann, U.; Saur, J.; Glassmeier, K.-H.; Dougherty, M. K.

    2009-12-01

    We study the interaction of Saturn's small, icy moon Enceladus and its plume with the corotating magnetospheric plasma by means of a 3D hybrid simulation model, which treats the ions as individual particles and the electrons as a massless, charge-neutralizing fluid. We analyze systematically how Enceladus' internal conductivity and plasma absorption at the surface as well as charge exchange and pick-up in the plume contribute to the overall structure of the interaction region. Furthermore, we provide a comparison of our simulation results to data obtained by the Cassini magnetometer instrument. The major findings of this study are: (1) the magnetic field diffuses through the solid body of Enceladus almost unaffected, whereas plasma absorption gives rise to a symmetric depletion wake downstream of the moon; (2) due to the small gyroradii of the newly generated plume ions, the pick-up tail possesses a 2D structure; (3) the magnetic field lines drape around the plume, which triggers an Alfvén wing system that dominates the structure of Enceladus' plasma environment. Inside the plume itself, a magnetic cavity is formed; (4) besides the reproduction of the key features of the observed magnetic field signatures, evidence for variability in the locations of the active jets and in the total gas content of the plume are shown.

  11. 3D Global Braginskii Simulations of Plasma Dynamics and Turbulence in LAPD

    NASA Astrophysics Data System (ADS)

    Fisher, Dustin; Rogers, Barrett

    2013-10-01

    3D global two-fluid simulations are presented in an ongoing effort to identify and understand the plasma dynamics in the Large Plasma Device (LAPD) at UCLA's Basic Science Facility. Modeling is done using a modified version of the Global Braginskii Solver (GBS) that models the plasma from source to edge region on a field-aligned grid using a finite difference method and 4th order Runge-Kutta time stepping. Progress has been made to account for the thermionic cathode emission of fast electrons at the source, the axial dependence of the plasma source, and biasing the front and side walls. Along with trying to understand the effect sheath's and neutrals have in setting the plasma potential, work is being done to model the biasable limiter recently used by colleagues at UCLA to better understand flow shear and particle transport in the LAPD. Comparisons of the zero bias case are presented along with analysis of the growth and dynamics of turbulent structures (such as drift waves) seen in the simulations. Supported through CICART under the auspices of the DOE's EPSCoR Grant No. DE-FG02-10ER46372.

  12. A Computationally-Efficient Kinetic Approach for Gas/Particle Mass Transfer Treatments: Development, Testing, and 3-D Application

    NASA Astrophysics Data System (ADS)

    Hu, X.; Zhang, Y.

    2007-05-01

    The Weather Research and Forecast/Chemistry Model (WRF/Chem) that simulates chemistry simultaneously with meteorology has recently been developed for real-time forecasting by the U.S. National Center for Atmospheric Research (NCAR) and National Oceanic & Atmospheric Administration (NOAA). As one of the six air quality models, WRF/Chem with a modal aerosol module has been applied for ozone and PM2.5 ensemble forecasts over eastern North America as part of the 2004 New England Air Quality Study (NEAQS) program (NEAQS-2004). Significant differences exist in the partitioning of volatile species (e.g., ammonium and nitrate) simulated by the six models. Model biases are partially attributed to the equilibrium assumption used in the gas/particles mass transfer approach in some models. Development of a more accurate, yet computationally- efficient gas/particle mass transfer approach for three-dimensional (3-D) applications, in particular, real-time forecasting, is therefore warranted. Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) has been implemented into WRF/Chem (referred to as WRF/Chem-MADRID). WRF/Chem-MADRID offers three gas/particle partitioning treatments: equilibrium, kinetic, and hybrid approaches. The equilibrium approach is computationally-efficient and commonly used in 3-D air quality models but less accurate under certain conditions (e.g., in the presence of coarse, reactive particles such as PM containing sea-salts in the coastal areas). The kinetic approach is accurate but computationally-expensive, limiting its 3-D applications. The hybrid approach attempts to provide a compromise between merits and drawbacks of the two approaches by treating fine PM (typically < ~ 1 μm) with the equilibrium approach and coarse PM with the kinetic approach. A computationally-efficient kinetic gas/particle mass transfer approach in MADRID has recently been developed for 3-D applications based on an Analytical Predictor of Condensation (referred

  13. Charged-particle Gun Design with 3D Finite-element Methods

    NASA Astrophysics Data System (ADS)

    Humphries, Stanley

    2002-04-01

    The DARHT second-axis injector poses a major challenge for computer simulation. The relativistic electrons are subject to strong beam-generated electric and magnetic forces. The beam and applied fields are fully three-dimensional. Furthermore, accurate field calculations at surfaces are critical to model Child-law emission. Although several 2D relativistic beam codes are available, there is presently no 3D tool that can address all important processes in the DARHT injector. As a result, we created the OmniTrak 3D finite-element code suite. This talk gives a basic tutorial on finite-element methods with emphasis on electron gun design via the ray-tracing technique. Four main areas are covered: 1) the mesh as a tool to organize space, 2) transformation of the Poisson equation through the minimum residual principle, 3) orbit tracking in a complex environment and 4) handling self-consistent beam-generated fields. The components of a volume mesh (elements, nodes and facets) are reviewed. We consider motivations for choosing a 3D mesh style: structured versus unstructured, tetrahedrons versus hexahedrons. We discuss methods for taking volume integrals over arbitrary hexahedrons through normal coordinates and shape functions, leading to the fundamental field equations. The special problems of 3D magnetic field solutions and the advantages of the reduced potential method are outlined. Accurate field interpolations for orbit calculations require fast identification of occupied elements. A method for fast element identification that also yields the orbit penetration point on the element surface is described. The final topics are the assignment of charge and current to meshes from calculated orbits and techniques for space-charge-limited emission from multiple arbitrary 3D surfaces.

  14. Fractal geometry of sedimentary rocks: simulation in 3-D using a Relaxed Bidisperse Ballistic Deposition Model

    NASA Astrophysics Data System (ADS)

    Giri, Abhra; Tarafdar, Sujata; Gouze, Philippe; Dutta, Tapati

    2013-03-01

    Several studies, both theoretical and experimental, show that sedimentary rocks have a fractal pore-grain interface. In this paper a computer simulated 3-D sedimentary rock structure generated by the Relaxed Ballistic Bidisperse Deposition Model (RBBDM), is investigated to characterize the micro structure of its pores. The pore volume and the rock-pore interface show the same fractal dimension indicating that the pore volume is a fractal. The two point density correlation is computed for the pore space and the results compare favourably with the range reported from experiments. An array of 2-D X-ray tomography micrograph sections of a real sedimentary rock, an oolitic limestone (pure calcite) from the Mondeville formation of Middle Jurassic age (Paris Basin, France), was used to generate a 3-D bitmap. The 3-D real rock sample generated in this manner, was analysed for similar studies as the simulated structure. The results were compared with those obtained from simulation. The simulation results agree qualitatively with the real rock sample. Diffusion through the connected pore space of the simulated structure was studied using a random walk algorithm and the results compared with the similar simulation study done on the 3-D oolitic limestone specimen. In both cases diffusion was found to be anomalous indicating that the sedimentary rock has a fractal geometry. The favourable comparability of results between the simulated and real rock supports the usefulness of the model of sedimentary rock generation which can be applicable to transport phenomena.

  15. Parallel 3-D particle-in-cell modelling of charged ultrarelativistic beam dynamics

    NASA Astrophysics Data System (ADS)

    Boronina, Marina A.; Vshivkov, Vitaly A.

    2015-12-01

    > ) in supercolliders. We use the 3-D set of Maxwell's equations for the electromagnetic fields, and the Vlasov equation for the distribution function of the beam particles. The model incorporates automatically the longitudinal effects, which can play a significant role in the cases of super-high densities. We present numerical results for the dynamics of two focused ultrarelativistic beams with a size ratio 10:1:100. The results demonstrate high efficiency of the proposed computational methods and algorithms, which are applicable to a variety of problems in relativistic plasma physics.

  16. Magnetic properties of 3D nanocomposites consisting of an opal matrix with embedded spinel ferrite particles

    NASA Astrophysics Data System (ADS)

    Rinkevich, A. B.; Korolev, A. V.; Samoylovich, M. I.; Kleshcheva, S. M.; Perov, D. V.

    2016-02-01

    The magnetic properties of 3D nanocomposites representing Mn-Zn, Ni-Zn, Co-Zn, La-Co-Zn, and Nd-Co-Zn spinel ferrite particles embedded in the interspherical spaces of opal matrices are studied. Experimental data are obtained in the temperature interval 2-300 K by measuring the magnetization at a static magnetic field strength of up to 50 kOe and the ac magnetic susceptibility at an alternating magnetic field amplitude of 4 kOe and a frequency of 80 Hz.

  17. 3D silicon sensors with variable electrode depth for radiation hard high resolution particle tracking

    NASA Astrophysics Data System (ADS)

    Da Vià, C.; Borri, M.; Dalla Betta, G.; Haughton, I.; Hasi, J.; Kenney, C.; Povoli, M.; Mendicino, R.

    2015-04-01

    3D sensors, with electrodes micro-processed inside the silicon bulk using Micro-Electro-Mechanical System (MEMS) technology, were industrialized in 2012 and were installed in the first detector upgrade at the LHC, the ATLAS IBL in 2014. They are the radiation hardest sensors ever made. A new idea is now being explored to enhance the three-dimensional nature of 3D sensors by processing collecting electrodes at different depths inside the silicon bulk. This technique uses the electric field strength to suppress the charge collection effectiveness of the regions outside the p-n electrodes' overlap. Evidence of this property is supported by test beam data of irradiated and non-irradiated devices bump-bonded with pixel readout electronics and simulations. Applications include High-Luminosity Tracking in the high multiplicity LHC forward regions. This paper will describe the technical advantages of this idea and the tracking application rationale.

  18. Modeling blood flow circulation in intracranial arterial networks: a comparative 3D/1D simulation study.

    PubMed

    Grinberg, L; Cheever, E; Anor, T; Madsen, J R; Karniadakis, G E

    2011-01-01

    We compare results from numerical simulations of pulsatile blood flow in two patient-specific intracranial arterial networks using one-dimensional (1D) and three-dimensional (3D) models. Specifically, we focus on the pressure and flowrate distribution at different segments of the network computed by the two models. Results obtained with 1D and 3D models with rigid walls show good agreement in massflow distribution at tens of arterial junctions and also in pressure drop along the arteries. The 3D simulations with the rigid walls predict higher amplitude of the flowrate and pressure temporal oscillations than the 1D simulations with compliant walls at various segments even for small time-variations in the arterial cross-sectional areas. Sensitivity of the flow and pressure with respect to variation in the elasticity parameters is investigated with the 1D model. PMID:20661645

  19. 3D imaging of particle-scale rotational motion in cyclically driven granular flows

    NASA Astrophysics Data System (ADS)

    Harrington, Matt; Powers, Dylan; Cooper, Eric; Losert, Wolfgang

    Recent experimental advances have enabled three-dimensional (3D) imaging of motion, structure, and failure within granular systems. 3D imaging allows researchers to directly characterize bulk behaviors that arise from particle- and meso-scale features. For instance, segregation of a bidisperse system of spheres under cyclic shear can originate from microscopic irreversibilities and the development of convective secondary flows. Rotational motion and frictional rotational coupling, meanwhile, have been less explored in such experimental 3D systems, especially under cyclic forcing. In particular, relative amounts of sliding and/or rolling between pairs of contacting grains could influence the reversibility of both trajectories, in terms of both position and orientation. In this work, we apply the Refractive Index Matched Scanning technique to a granular system that is cyclically driven and measure both translational and rotational motion of individual grains. We relate measured rotational motion to resulting shear bands and convective flows, further indicating the degree to which pairs and neighborhoods of grains collectively rotate.

  20. Particle Filters and Occlusion Handling for Rigid 2D-3D Pose Tracking.

    PubMed

    Lee, Jehoon; Sandhu, Romeil; Tannenbaum, Allen

    2013-08-01

    In this paper, we address the problem of 2D-3D pose estimation. Specifically, we propose an approach to jointly track a rigid object in a 2D image sequence and to estimate its pose (position and orientation) in 3D space. We revisit a joint 2D segmentation/3D pose estimation technique, and then extend the framework by incorporating a particle filter to robustly track the object in a challenging environment, and by developing an occlusion detection and handling scheme to continuously track the object in the presence of occlusions. In particular, we focus on partial occlusions that prevent the tracker from extracting an exact region properties of the object, which plays a pivotal role for region-based tracking methods in maintaining the track. To this end, a dynamical choice of how to invoke the objective functional is performed online based on the degree of dependencies between predictions and measurements of the system in accordance with the degree of occlusion and the variation of the object's pose. This scheme provides the robustness to deal with occlusions of an obstacle with different statistical properties from that of the object of interest. Experimental results demonstrate the practical applicability and robustness of the proposed method in several challenging scenarios. PMID:24058277

  1. Simulating binocular vision for no-reference 3D visual quality measurement.

    PubMed

    Zhou, Wu-Jie; Yu, Lu; Wu, Ming-Wei

    2015-09-01

    Perceptual quality measurement of three-dimensional (3D) visual signals has become a fundamental challenge in 3D imaging fields. This paper proposes a novel no-reference (NR) 3D visual quality measurement (VQM) metric that uses simulations of the primary visual cortex (V1) of binocular vision. As the major technical contribution of this study, perceptual properties of simple and complex cells are considered for NR 3D-VQM. More specifically, the metric simulates the receptive fields of simple cells (one class of V1 neurons) using Gaussian derivative functions, and the receptive fields of complex cells (the other class of V1 neurons) using disparity energy responses and binocular rivalry responses. Subsequently, various quality-aware features are extracted from the primary visual cortex; these will change in the presence of distortions. Finally, those features are mapped to the subjective quality score of the distorted 3D visual signal by using support vector regression (SVR). Experiments on two publicly available 3D databases confirm the effectiveness of our proposed metric, compared to the relevant full-reference (FR) and NR metrics. PMID:26368467

  2. Dynamic earthquake rupture simulations on nonplanar faults embedded in 3D geometrically complex, heterogeneous elastic solids

    NASA Astrophysics Data System (ADS)

    Duru, Kenneth; Dunham, Eric M.

    2016-01-01

    Dynamic propagation of shear ruptures on a frictional interface in an elastic solid is a useful idealization of natural earthquakes. The conditions relating discontinuities in particle velocities across fault zones and tractions acting on the fault are often expressed as nonlinear friction laws. The corresponding initial boundary value problems are both numerically and computationally challenging. In addition, seismic waves generated by earthquake ruptures must be propagated for many wavelengths away from the fault. Therefore, reliable and efficient numerical simulations require both provably stable and high order accurate numerical methods. We present a high order accurate finite difference method for: a) enforcing nonlinear friction laws, in a consistent and provably stable manner, suitable for efficient explicit time integration; b) dynamic propagation of earthquake ruptures along nonplanar faults; and c) accurate propagation of seismic waves in heterogeneous media with free surface topography. We solve the first order form of the 3D elastic wave equation on a boundary-conforming curvilinear mesh, in terms of particle velocities and stresses that are collocated in space and time, using summation-by-parts (SBP) finite difference operators in space. Boundary and interface conditions are imposed weakly using penalties. By deriving semi-discrete energy estimates analogous to the continuous energy estimates we prove numerical stability. The finite difference stencils used in this paper are sixth order accurate in the interior and third order accurate close to the boundaries. However, the method is applicable to any spatial operator with a diagonal norm satisfying the SBP property. Time stepping is performed with a 4th order accurate explicit low storage Runge-Kutta scheme, thus yielding a globally fourth order accurate method in both space and time. We show numerical simulations on band limited self-similar fractal faults revealing the complexity of rupture dynamics

  3. Stem dependence on stiffness in 3D RNA simulation using SimRNA

    NASA Astrophysics Data System (ADS)

    Dawson, Wayne; Boniecki, Michal; Bujnicki, Janusz

    2015-03-01

    SimRNA is a recently developed de novo 3D structure prediction program in our laboratory that uses the Monte Carlo method to search the conformation space of RNA using knowledge based energy functions. In developing the 3D model, we have also be exploring the larger physical questions about what generates differences in Kuhn length (a measure of stiffness) in biopolymers. In previoius work, this was shown to depend on the stem length and to be a function of the length and Young's modulus. A complete theoretical model was of the entropy changes due to the freezing out of degrees of freedom was developed base on this model. In this study, we find that this is further supported in the development of the 3D statitstical potentials for actual 3D simulations of RNA.

  4. Mixed reality orthognathic surgical simulation by entity model manipulation and 3D-image display

    NASA Astrophysics Data System (ADS)

    Shimonagayoshi, Tatsunari; Aoki, Yoshimitsu; Fushima, Kenji; Kobayashi, Masaru

    2005-12-01

    In orthognathic surgery, the framing of 3D-surgical planning that considers the balance between the front and back positions and the symmetry of the jawbone, as well as the dental occlusion of teeth, is essential. In this study, a support system for orthodontic surgery to visualize the changes in the mandible and the occlusal condition and to determine the optimum position in mandibular osteotomy has been developed. By integrating the operating portion of a tooth model that is to determine the optimum occlusal position by manipulating the entity tooth model and the 3D-CT skeletal images (3D image display portion) that are simultaneously displayed in real-time, the determination of the mandibular position and posture in which the improvement of skeletal morphology and occlusal condition is considered, is possible. The realistic operation of the entity model and the virtual 3D image display enabled the construction of a surgical simulation system that involves augmented reality.

  5. Relativistic 3D precessing jet simulations for the X-ray binary SS433

    NASA Astrophysics Data System (ADS)

    Monceau-Baroux, Rémi; Porth, Oliver; Meliani, Zakaria; Keppens, Rony

    2014-01-01

    Context. Modern high-resolution radio observations allow us a closer look into the objects that power relativistic jets. This is especially the case for SS433, an X-ray binary that emits a precessing jet that is observed down to the subparsec scale. Aims: We aim to study full 3D dynamics of relativistic jets associated with active galactic nuclei or X-ray binaries (XRB). In particular, we incorporate the precessing motion of a jet into a model for the jet associated with the XRB SS433. Our study of the jet dynamics in this system focuses on the subparsec scales. We investigate the impact of jet precession and the variation of the Lorentz factor of the injected matter on the general 3D jet dynamics and its energy transfer to the surrounding medium. After visualizing and quantifying jet dynamics, we aim to realize synthetic radio mapping of the data, to compare our results with observations. Methods: For our study we used a block-tree adaptive mesh refinement scheme and an inner time-dependent boundary prescription to inject precessing bipolar supersonic jets. Parameters extracted from observations were used. Different 3D jet realizations that match the kinetic flux of the SS433 jet were intercompared, which vary in density contrast and jet beam velocity. We tracked the energy content deposited in different regions of the domain affected by the jet. Our code allows us to follow the adiabatic cooling of a population of relativistic particles injected by the jet. This evolving energy spectrum of accelerated electrons, using a pressure-based proxy for the magnetic field, allowed us to obtain the radio emission from our simulation. Results: We find a higher energy transfer for a precessing jet than for standing jets with otherwise identical parameters as a result of the effectively increased interaction area. We obtain synthetic radio maps for all jets, from which one can see that dynamical flow features are clearly linked with enhanced emission sites. Conclusions: The

  6. Secondary reconnection, energisation and turbulence in dipolarisation fronts: results of a 3D kinetic simulation campaign

    NASA Astrophysics Data System (ADS)

    Lapenta, Giovanni; Goldman, Martin; Newman, David; olshevskyi, Vyacheslav; Markidis, Stefano

    2016-04-01

    Dipolarization fronts (DF) are formed by reconnection outflows interacting with the pre-existing environment. These regions are host of important energy exchanges [1], particle acceleration [2] and a complex structure and evolution [3]. Our recent work has investigated these regions via fully kinetic 3D simulations [4]. As reported recently on Nature Physics [3], based on 3D fully kinetic simulations started with a well defined x-line, we observe that in the DF reconnection transitions towards a more chaotic regime. In the fronts an instability devel- ops caused by the local gradients of the density and by the unfavourable acceleration and field line curvature. The consequence is the break up of the fronts in a fashion similar to the classical fluid Rayleigh-Taylor instability with the formation of "fingers" of plasma and embedded magnetic fields. These fingers interact and produce secondary reconnection sites. We present several different diagnostics that prove the existence of these secondary reconnection sites. Each site is surrounded by its own electron diffusion region. At the fronts the ions are generally not magnetized and considerable ion slippage is present. The discovery we present is that electrons are also slipping, forming localized diffusion regions near secondary reconnection sites [1]. The consequence of this discovery is twofold. First, the instability in the fronts has strong energetic implications. We observe that the energy transfer locally is very strong, an order of magnitude stronger than in the "X" line. However, this energy transfer is of both signs as it is natural for a wavy rippling with regions of magnetic to kinetic and regions of kinetic to magnetic energy conversion. Second, and most important for this session, is that MMS should not limit the search for electron diffusion regions to the location marked with X in all reconnection cartoons. Our simulations predict more numerous and perhaps more easily measurable electron diffusion

  7. Particle acceleration in 3D single current sheets formed in the solar corona and heliosphere: PIC approach

    NASA Astrophysics Data System (ADS)

    Zharkova, V. V.; Siversky, T.

    2015-09-01

    Acceleration of protons and electrons in a reconnecting current sheet (RCS) is investigated with the test particle and particle-in-cell (PIC) approaches in a 3D magnetic topology. PIC simulations confirm a spatial separation of electrons and protons with respect to the midplane depending on the guiding field. Simulation reveals that the separation occurs in magnetic topologies with strong guiding fields and lasts as long as the particles are kept dragged into a current sheet. This separation produces a polarisation electric field induced by the plasma feedback to a presence of accelerated particles, which shape can change from symmetric towards the midplane (for weak guiding field) to fully asymmetric (for strong guiding field). Particles are found accelerated at a midplane of any current sheets present in the heliosphere to the energies up to hundred keV for electrons and hundred MeV for protons. The maximum energy gained by particles during their motion inside the current sheet is defined by its magnetic field topology (the ratio of magnetic field components), the side and location from the X-nullpoint, where the particles enter a current sheet. In strong magnetic fields of the solar corona with weaker guiding fields, electrons are found circulating about the midplane to large distances where proton are getting accelerated, creating about the current sheet midplane clouds of high energy electrons, which can be the source of hard X-ray emission in the coronal sources of flares. These electrons are ejected into the same footpoint as protons after the latter reach the energy sufficicent to break from a current sheet. In a weaker magnetic field of the heliosphere the bounced electrons with lower energies cannot reach the midplane turning instead at some distance D before the current sheet midplane by 180 degrees from their initial motion. Also the beams of accelerated transit and bounced particles are found to generate turbulent electric fields in a form of Langmuir

  8. A 3D Vector/Scalar Visualization and Particle Tracking Package

    Energy Science and Technology Software Center (ESTSC)

    1999-08-19

    BOILERMAKER is an interactive visualization system consisting of three components: a visualization component, a particle tracking component, and a communication layer. The software, to date, has been used primarily in the visualization of vector and scalar fields associated with computational fluid dynamics (CFD) models of flue gas flows in industrial boilers and incinerators. Users can interactively request and toggle static vector fields, dynamic streamlines, and flowing vector fields. In addition, the user can interactively placemore » injector nozzles on boiler walls and visualize massed, evaporating sprays emanating from them. Some characteristics of the spray can be adjusted from within the visualization environment including spray shape and particle size. Also included with this release is software that supports 3D menu capabilities, scrollbars, communication and navigation.« less

  9. Enhanced copper micro/nano-particle mixed paste sintered at low temperature for 3D interconnects

    NASA Astrophysics Data System (ADS)

    Dai, Y. Y.; Ng, M. Z.; Anantha, P.; Lin, Y. D.; Li, Z. G.; Gan, C. L.; Tan, C. S.

    2016-06-01

    An enhanced copper paste, formulated by copper micro- and nano-particles mixture, is reported to prevent paste cracking and obtain an improved packing density. The particle mixture of two different sizes enables reduction in porosity of the micro-paste and resolves the cracking issue in the nano-paste. In-situ temperature and resistance measurements indicate that the mixed paste has a lower densification temperature. Electrical study also shows a ˜12× lower sheet resistance of 0.27 Ω/sq. In addition, scanning electron microscope image analysis confirms a ˜50% lower porosity, which is consistent with the thermal and electrical results. The 3:1 (micro:nano, wt. %) mixed paste is found to have the strongest synergistic effect. This phenomenon is discussed further. Consequently, the mixed paste is a promising material for potential low temperature 3D interconnects fabrication.

  10. A 3D Vector/Scalar Visualization and Particle Tracking Package

    SciTech Connect

    Freitag, Lori; Disz, Terry; Papka, Mike; Heath, Daniel; Diachin, Darin; Herzog, Jim; Ryan, and Bob

    1999-08-19

    BOILERMAKER is an interactive visualization system consisting of three components: a visualization component, a particle tracking component, and a communication layer. The software, to date, has been used primarily in the visualization of vector and scalar fields associated with computational fluid dynamics (CFD) models of flue gas flows in industrial boilers and incinerators. Users can interactively request and toggle static vector fields, dynamic streamlines, and flowing vector fields. In addition, the user can interactively place injector nozzles on boiler walls and visualize massed, evaporating sprays emanating from them. Some characteristics of the spray can be adjusted from within the visualization environment including spray shape and particle size. Also included with this release is software that supports 3D menu capabilities, scrollbars, communication and navigation.

  11. Precipitation Processes Developed During ARM (1997), TOGA COARE (1992) GATE (1974), SCSMEX (1998), and KWAJEX (1999): Consistent 3D, Semi-3D and 3D Cloud Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Hou, A.; Atlas, R.; Starr, D.; Sud, Y.

    2003-01-01

    Real clouds and cloud systems are inherently three-dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D) have been used to study the response of clouds to large-scale forcing. IN these 3D simulators, the model domain was small, and the integration time was 6 hours. Only recently have 3D experiments been performed for multi-day periods for tropical clouds systems with large horizontal domains at the National Center of Atmospheric Research (NCAR) and at NASA Goddard Space Center. At Goddard, a 3D cumulus Ensemble (GCE) model was used to simulate periods during TOGA COARE, GATE, SCSMEX, ARM, and KWAJEX using a 512 by 512 km domain (with 2-km resolution). The result indicate that surface precipitation and latent heating profiles are very similar between the 2D and 3D GCE model simulation. The major objective of this paper are: (1) to assess the performance of the super-parametrization technique, (2) calculate and examine the surface energy (especially radiation) and water budget, and (3) identify the differences and similarities in the organization and entrainment rates of convection between simulated 2D and 3D cloud systems.

  12. Ground motion simulations in Marmara (Turkey) region from 3D finite difference method

    NASA Astrophysics Data System (ADS)

    Aochi, Hideo; Ulrich, Thomas; Douglas, John

    2016-04-01

    In the framework of the European project MARSite (2012-2016), one of the main contributions from our research team was to provide ground-motion simulations for the Marmara region from various earthquake source scenarios. We adopted a 3D finite difference code, taking into account the 3D structure around the Sea of Marmara (including the bathymetry) and the sea layer. We simulated two moderate earthquakes (about Mw4.5) and found that the 3D structure improves significantly the waveforms compared to the 1D layer model. Simulations were carried out for different earthquakes (moderate point sources and large finite sources) in order to provide shake maps (Aochi and Ulrich, BSSA, 2015), to study the variability of ground-motion parameters (Douglas & Aochi, BSSA, 2016) as well as to provide synthetic seismograms for the blind inversion tests (Diao et al., GJI, 2016). The results are also planned to be integrated in broadband ground-motion simulations, tsunamis generation and simulations of triggered landslides (in progress by different partners). The simulations are freely shared among the partners via the internet and the visualization of the results is diffused on the project's homepage. All these simulations should be seen as a reference for this region, as they are based on the latest knowledge that obtained during the MARSite project, although their refinement and validation of the model parameters and the simulations are a continuing research task relying on continuing observations. The numerical code used, the models and the simulations are available on demand.

  13. Simulation-Guided 3D Nanomanufacturing via Focused Electron Beam Induced Deposition

    DOE PAGESBeta

    Fowlkes, Jason D.; Winkler, Robert; Lewis, Brett B.; Stanford, Michael G.; Plank, Harald; Rack, Philip D.

    2016-06-10

    Focused electron beam induced deposition (FEBID) is one of the few techniques that enables direct-write synthesis of free-standing 3D nanostructures. While the fabrication of simple architectures such as vertical or curving nanowires has been achieved by simple trial and error, processing complex 3D structures is not tractable with this approach. This is due, inpart, to the dynamic interplay between electron–solid interactions and the transient spatial distribution of absorbed precursor molecules on the solid surface. Here, we demonstrate the ability to controllably deposit 3D lattice structures at the micro/nanoscale, which have received recent interest owing to superior mechanical and optical properties.more » Moreover, a hybrid Monte Carlo–continuum simulation is briefly overviewed, and subsequently FEBID experiments and simulations are directly compared. Finally, a 3D computer-aided design (CAD) program is introduced, which generates the beam parameters necessary for FEBID by both simulation and experiment. In using this approach, we demonstrate the fabrication of various 3D lattice structures using Pt-, Au-, and W-based precursors.« less

  14. Simulation-Guided 3D Nanomanufacturing via Focused Electron Beam Induced Deposition.

    PubMed

    Fowlkes, Jason D; Winkler, Robert; Lewis, Brett B; Stanford, Michael G; Plank, Harald; Rack, Philip D

    2016-06-28

    Focused electron beam induced deposition (FEBID) is one of the few techniques that enables direct-write synthesis of free-standing 3D nanostructures. While the fabrication of simple architectures such as vertical or curving nanowires has been achieved by simple trial and error, processing complex 3D structures is not tractable with this approach. In part, this is due to the dynamic interplay between electron-solid interactions and the transient spatial distribution of absorbed precursor molecules on the solid surface. Here, we demonstrate the ability to controllably deposit 3D lattice structures at the micro/nanoscale, which have received recent interest owing to superior mechanical and optical properties. A hybrid Monte Carlo-continuum simulation is briefly overviewed, and subsequently FEBID experiments and simulations are directly compared. Finally, a 3D computer-aided design (CAD) program is introduced, which generates the beam parameters necessary for FEBID by both simulation and experiment. Using this approach, we demonstrate the fabrication of various 3D lattice structures using Pt-, Au-, and W-based precursors. PMID:27284689

  15. Insights into Plasma Etch Profile Evolution with 3D Profile Simulation

    NASA Astrophysics Data System (ADS)

    Sriraman, Saravanapriyan; Paterson, Alex; Zhang, Yiting; Kushner, Mark

    2014-10-01

    Plasma etching is critical for pattern transfer in microelectronics fabrication. For planar devices, efforts in 2D etch profile simulations were sufficient to understand critical etch process mechanisms. In contrast, to understand the complex mechanisms in etching 3D structures of current technology nodes such as FinFETs, 2D profile simulators are inadequate. In this paper, we report on development of a 3D profile simulation platform, the Monte Carlo Feature Profile Model (MCFPM-3D). The MCFPM-3D builds upon the 2D MCFPM platform that includes aspects such as mixing, implantation, and photon assisted processes and addresses reaction mechanisms in surface etching, sputtering, and deposition to predict profile evolution. Model inputs include fluxes of species from plasma derived from the Hybrid Plasma Equipment Model (HPEM). Test cases of Si/SiO2 etching in Ar/Cl2 and Ar/CF4/O2 plasmas for representative 2D/3D feature topographies are considered and phenomena such as selectivity and aspect ratio dependent etching will be discussed.

  16. 2D-3D hybrid stabilized finite element method for tsunami runup simulations

    NASA Astrophysics Data System (ADS)

    Takase, S.; Moriguchi, S.; Terada, K.; Kato, J.; Kyoya, T.; Kashiyama, K.; Kotani, T.

    2016-09-01

    This paper presents a two-dimensional (2D)-three-dimensional (3D) hybrid stabilized finite element method that enables us to predict a propagation process of tsunami generated in a hypocentral region, which ranges from offshore propagation to runup to urban areas, with high accuracy and relatively low computational costs. To be more specific, the 2D shallow water equation is employed to simulate the propagation of offshore waves, while the 3D Navier-Stokes equation is employed for the runup in urban areas. The stabilized finite element method is utilized for numerical simulations for both of the 2D and 3D domains that are independently discretized with unstructured meshes. The multi-point constraint and transmission methods are applied to satisfy the continuity of flow velocities and pressures at the interface between the resulting 2D and 3D meshes, since neither their spatial dimensions nor node arrangements are consistent. Numerical examples are presented to demonstrate the performance of the proposed hybrid method to simulate tsunami behavior, including offshore propagation and runup to urban areas, with substantially lower computation costs in comparison with full 3D computations.

  17. 2D-3D hybrid stabilized finite element method for tsunami runup simulations

    NASA Astrophysics Data System (ADS)

    Takase, S.; Moriguchi, S.; Terada, K.; Kato, J.; Kyoya, T.; Kashiyama, K.; Kotani, T.

    2016-05-01

    This paper presents a two-dimensional (2D)-three-dimensional (3D) hybrid stabilized finite element method that enables us to predict a propagation process of tsunami generated in a hypocentral region, which ranges from offshore propagation to runup to urban areas, with high accuracy and relatively low computational costs. To be more specific, the 2D shallow water equation is employed to simulate the propagation of offshore waves, while the 3D Navier-Stokes equation is employed for the runup in urban areas. The stabilized finite element method is utilized for numerical simulations for both of the 2D and 3D domains that are independently discretized with unstructured meshes. The multi-point constraint and transmission methods are applied to satisfy the continuity of flow velocities and pressures at the interface between the resulting 2D and 3D meshes, since neither their spatial dimensions nor node arrangements are consistent. Numerical examples are presented to demonstrate the performance of the proposed hybrid method to simulate tsunami behavior, including offshore propagation and runup to urban areas, with substantially lower computation costs in comparison with full 3D computations.

  18. From micro-scale 3D simulations to macro-scale model of periodic porous media

    NASA Astrophysics Data System (ADS)

    Crevacore, Eleonora; Tosco, Tiziana; Marchisio, Daniele; Sethi, Rajandrea; Messina, Francesca

    2015-04-01

    In environmental engineering, the transport of colloidal suspensions in porous media is studied to understand the fate of potentially harmful nano-particles and to design new remediation technologies. In this perspective, averaging techniques applied to micro-scale numerical simulations are a powerful tool to extrapolate accurate macro-scale models. Choosing two simplified packing configurations of soil grains and starting from a single elementary cell (module), it is possible to take advantage of the periodicity of the structures to reduce the computation costs of full 3D simulations. Steady-state flow simulations for incompressible fluid in laminar regime are implemented. Transport simulations are based on the pore-scale advection-diffusion equation, that can be enriched introducing also the Stokes velocity (to consider the gravity effect) and the interception mechanism. Simulations are carried on a domain composed of several elementary modules, that serve as control volumes in a finite volume method for the macro-scale method. The periodicity of the medium involves the periodicity of the flow field and this will be of great importance during the up-scaling procedure, allowing relevant simplifications. Micro-scale numerical data are treated in order to compute the mean concentration (volume and area averages) and fluxes on each module. The simulation results are used to compare the micro-scale averaged equation to the integral form of the macroscopic one, making a distinction between those terms that could be computed exactly and those for which a closure in needed. Of particular interest it is the investigation of the origin of macro-scale terms such as the dispersion and tortuosity, trying to describe them with micro-scale known quantities. Traditionally, to study the colloidal transport many simplifications are introduced, such those concerning ultra-simplified geometry that usually account for a single collector. Gradual removal of such hypothesis leads to a

  19. Understanding the core-halo relation of quantum wave dark matter from 3D simulations.

    PubMed

    Schive, Hsi-Yu; Liao, Ming-Hsuan; Woo, Tak-Pong; Wong, Shing-Kwong; Chiueh, Tzihong; Broadhurst, Tom; Hwang, W-Y Pauchy

    2014-12-31

    We examine the nonlinear structure of gravitationally collapsed objects that form in our simulations of wavelike cold dark matter, described by the Schrödinger-Poisson (SP) equation with a particle mass ∼10(-22)  eV. A distinct gravitationally self-bound solitonic core is found at the center of every halo, with a profile quite different from cores modeled in the warm or self-interacting dark matter scenarios. Furthermore, we show that each solitonic core is surrounded by an extended halo composed of large fluctuating dark matter granules which modulate the halo density on a scale comparable to the diameter of the solitonic core. The scaling symmetry of the SP equation and the uncertainty principle tightly relate the core mass to the halo specific energy, which, in the context of cosmological structure formation, leads to a simple scaling between core mass (Mc) and halo mass (Mh), Mc∝a(-1/2)Mh(1/3), where a is the cosmic scale factor. We verify this scaling relation by (i) examining the internal structure of a statistical sample of virialized halos that form in our 3D cosmological simulations and by (ii) merging multiple solitons to create individual virialized objects. Sufficient simulation resolution is achieved by adaptive mesh refinement and graphic processing units acceleration. From this scaling relation, present dwarf satellite galaxies are predicted to have kiloparsec-sized cores and a minimum mass of ∼10(8)M⊙, capable of solving the small-scale controversies in the cold dark matter model. Moreover, galaxies of 2×10(12)M⊙ at z=8 should have massive solitonic cores of ∼2×10(9)M⊙ within ∼60  pc. Such cores can provide a favorable local environment for funneling the gas that leads to the prompt formation of early stellar spheroids and quasars. PMID:25615301

  20. 3-D FDTD simulation of shear waves for evaluation of complex modulus imaging.

    PubMed

    Orescanin, Marko; Wang, Yue; Insana, Michael

    2011-02-01

    The Navier equation describing shear wave propagation in 3-D viscoelastic media is solved numerically with a finite differences time domain (FDTD) method. Solutions are formed in terms of transverse scatterer velocity waves and then verified via comparison to measured wave fields in heterogeneous hydrogel phantoms. The numerical algorithm is used as a tool to study the effects on complex shear modulus estimation from wave propagation in heterogeneous viscoelastic media. We used an algebraic Helmholtz inversion (AHI) technique to solve for the complex shear modulus from simulated and experimental velocity data acquired in 2-D and 3-D. Although 3-D velocity estimates are required in general, there are object geometries for which 2-D inversions provide accurate estimations of the material properties. Through simulations and experiments, we explored artifacts generated in elastic and dynamic-viscous shear modulus images related to the shear wavelength and average viscosity. PMID:21342824

  1. 3D simulations of fluctuation spectra in the hall-MHD plasma.

    PubMed

    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. PMID:19257431

  2. 3D numerical simulation analysis of passive drag near free surface in swimming

    NASA Astrophysics Data System (ADS)

    Zhan, Jie-min; Li, Tian-zeng; Chen, Xue-bin; Li, Yok-sheung; Wai, Wing-hong Onyx

    2015-04-01

    The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Navier-Stokes equations using RNG k- ɛ turbulence closure. The volume of fluid (VOF) method is used to locate the free surface. The 3D virtual model is created by Computer Aided Industrial Design (CAID) software, Rhinoceros. Firstly, a specific posture of swimming is studied. The simulation results are in good agreement with the data from mannequin towing experiments. The effects of a swimmer's arms and legs positions on swimming performance are then studied. Finally, it is demonstrated that the present method is capable of simulating gliding near the free surface.

  3. Flexible simulation framework to couple processes in complex 3D models for subsurface utilization assessment

    NASA Astrophysics Data System (ADS)

    Kempka, Thomas; Nakaten, Benjamin; De Lucia, Marco; Nakaten, Natalie; Otto, Christopher; Pohl, Maik; Tillner, Elena; Kühn, Michael

    2016-04-01

    Utilization of the geological subsurface for production and storage of hydrocarbons, chemical energy and heat as well as for waste disposal requires the quantification and mitigation of environmental impacts as well as the improvement of georesources utilization in terms of efficiency and sustainability. The development of tools for coupled process simulations is essential to tackle these challenges, since reliable assessments are only feasible by integrative numerical computations. Coupled processes at reservoir to regional scale determine the behaviour of reservoirs, faults and caprocks, generally demanding for complex 3D geological models to be considered besides available monitoring and experimenting data in coupled numerical simulations. We have been developing a flexible numerical simulation framework that provides efficient workflows for integrating the required data and software packages to carry out coupled process simulations considering, e.g., multiphase fluid flow, geomechanics, geochemistry and heat. Simulation results are stored in structured data formats to allow for an integrated 3D visualization and result interpretation as well as data archiving and its provision to collaborators. The main benefits in using the flexible simulation framework are the integration of data geological and grid data from any third party software package as well as data export to generic 3D visualization tools and archiving formats. The coupling of the required process simulators in time and space is feasible, while different spatial dimensions in the coupled simulations can be integrated, e.g., 0D batch with 3D dynamic simulations. User interaction is established via high-level programming languages, while computational efficiency is achieved by using low-level programming languages. We present three case studies on the assessment of geological subsurface utilization based on different process coupling approaches and numerical simulations.

  4. 3D Spectral Element Method Simulations Of The Seismic Response of Caracas (Venezuela) Basin

    NASA Astrophysics Data System (ADS)

    Delavaud, E.; Vilotte, J.; Festa, G.; Cupillard, P.

    2007-12-01

    We present here 3D numerical simulations of the response of the Caracas (Venezuela) valley up to 5 Hz for different scenarios of plane wave excitation based on the regional seismicity. Attention is focused on the effects of the 3D basin geometry and of the adjacent regional topography. The simulations are performed using Spectral Element method (SEM) together with an unstructured hexahedral mesh discretization and perfectly matched layers (PML). These simulations show 3D amplification phenomena associated with complex wave reflexion, diffraction and focalisation patterns linked to the geometry of the basin. Time and frequency analysis reveal some interesting features both in terms of amplification and energy residence in the basin. The low frequency amplification pattern is mainly controlled by the early response of the basin to the incident plane wave while the high frequency amplification patterns result mainly from late arrivals where complex 3D wave diffraction phenomena are dominating and the memory of the initial excitation is lost. Interestingly enough, it is shown that H/V method correctly predict the low frequency amplification pattern when apply to the late part of the recorded seismograms. The complex high frequency amplification pattern is shown to be associated with surface wave generation at, and propagation from, sharp edges of the basin. Importance of 3D phenomena is assessed by comparison with simple 2D simulations. Significant differences in terms of time of residence, energy and amplification levels point out the interest of complete 3D modeling. In conclusions some of the limitations associated with the use of unstructured hexahedral meshes will be adressed. Despite the use of unstructured meshing tool, modeling the geometry of geological basins remain a complex and time consuming task. Possible extensions using more elaborate techniques like non conforming domain decomposition will be also discussed in conclusion.

  5. Peach Bottom 2 Turbine Trip Simulation Using TRAC-BF1/COS3D, a Best-Estimate Coupled 3-D Core and Thermal-Hydraulic Code System

    SciTech Connect

    Ui, Atsushi; Miyaji, Takamasa

    2004-10-15

    The best-estimate coupled three-dimensional (3-D) core and thermal-hydraulic code system TRAC-BF1/COS3D has been developed. COS3D, based on a modified one-group neutronic model, is a 3-D core simulator used for licensing analyses and core management of commercial boiling water reactor (BWR) plants in Japan. TRAC-BF1 is a plant simulator based on a two-fluid model. TRAC-BF1/COS3D is a coupled system of both codes, which are connected using a parallel computing tool. This code system was applied to the OECD/NRC BWR Turbine Trip Benchmark. Since the two-group cross-section tables are provided by the benchmark team, COS3D was modified to apply to this specification. Three best-estimate scenarios and four hypothetical scenarios were calculated using this code system. In the best-estimate scenario, the predicted core power with TRAC-BF1/COS3D is slightly underestimated compared with the measured data. The reason seems to be a slight difference in the core boundary conditions, that is, pressure changes and the core inlet flow distribution, because the peak in this analysis is sensitive to them. However, the results of this benchmark analysis show that TRAC-BF1/COS3D gives good precision for the prediction of the actual BWR transient behavior on the whole. Furthermore, the results with the modified one-group model and the two-group model were compared to verify the application of the modified one-group model to this benchmark. This comparison shows that the results of the modified one-group model are appropriate and sufficiently precise.

  6. Simulated 3D ultrasound LV cardiac images for active shape model training

    NASA Astrophysics Data System (ADS)

    Butakoff, Constantine; Balocco, Simone; Ordas, Sebastian; Frangi, Alejandro F.

    2007-03-01

    In this paper a study of 3D ultrasound cardiac segmentation using Active Shape Models (ASM) is presented. The proposed approach is based on a combination of a point distribution model constructed from a multitude of high resolution MRI scans and the appearance model obtained from simulated 3D ultrasound images. Usually the appearance model is learnt from a set of landmarked images. The significant level of noise, the low resolution of 3D ultrasound images (3D US) and the frequent failure to capture the complete wall of the left ventricle (LV) makes automatic or manual landmarking difficult. One possible solution is to use artificially simulated 3D US images since the generated images will match exactly the shape in question. In this way, by varying simulation parameters and generating corresponding images, it is possible to obtain a training set where the image matches the shape exactly. In this work the simulation of ultrasound images is performed by a convolutional approach. The evaluation of segmentation accuracy is performed on both simulated and in vivo images. The results obtained on 567 simulated images had an average error of 1.9 mm (1.73 +/- 0.05 mm for epicardium and 2 +/- 0.07 mm for endocardium, with 95% confidence) with voxel size being 1.1 × 1.1 × 0.7 mm. The error on 20 in vivo data was 3.5 mm (3.44 +/- 0.4 mm for epicardium and 3.73 +/- 0.4 mm for endocardium). In most images the model was able to approximate the borders of myocardium even when the latter was indistinguishable from the surrounding tissues.

  7. Using 3D Printing and Stereoscopic Imaging to Measure the Alignment and Rotation of Anisotropic Particles in Turbulence

    NASA Astrophysics Data System (ADS)

    Marcus, Guy

    2014-03-01

    We have developed a general methodology to experimentally measure the time-resolved Lagrangian orientation and solid body rotation rate of anisotropic particles with arbitrary aspect ratio from standard stereoscopic video image data. We apply these techniques to particles advected in a Rλ ~ 110 fluid flow, where turbulence is generated by two grids oscillating in phase. We use 3D printing technology to design and fabricate neutrally buoyant rods, crosses (two perpendicular rods), and jacks (three mutually perpendicular rods) with a largest dimension of 7 times the Kolmogorov length scale, which makes them good approximations to tracer particles. We have measured the mean square rotation rate, p˙ip˙i , of particles spanning the full range of aspect ratios and obtained results that agree with direct numerical simulations. Our measurements of the full solid-body rotation of jacks, in particular, are of broad experimental relevance because they demonstrate a new and extensible way to directly probe the Lagrangian vorticity of a fluid. Lastly, we will present our direct measurements of the alignment of crosses with the direction of their solid body rotation rate vector, demonstrating how turbulence aligns particles along their longest dimension. This work was completed while at Wesleyan University.

  8. Qualitative Assessment of a 3D Simulation Program: Faculty, Students, and Bio-Organic Reaction Animations

    ERIC Educational Resources Information Center

    Günersel, Adalet B.; Fleming, Steven A.

    2013-01-01

    Research shows that computer-based simulations and animations are especially helpful in fields such as chemistry where concepts are abstract and cannot be directly observed. Bio-Organic Reaction Animations (BioORA) is a freely available 3D visualization software program developed to help students understand the chemistry of biomolecular events.…

  9. 3D Direct Simulation Monte Carlo Code Which Solves for Geometrics

    Energy Science and Technology Software Center (ESTSC)

    1998-01-13

    Pegasus is a 3D Direct Simulation Monte Carlo Code which solves for geometries which can be represented by bodies of revolution. Included are all the surface chemistry enhancements in the 2D code Icarus as well as a real vacuum pump model. The code includes multiple species transport.

  10. An object-oriented simulator for 3D digital breast tomosynthesis imaging system.

    PubMed

    Seyyedi, Saeed; Cengiz, Kubra; Kamasak, Mustafa; Yildirim, Isa

    2013-01-01

    Digital breast tomosynthesis (DBT) is an innovative imaging modality that provides 3D reconstructed images of breast to detect the breast cancer. Projections obtained with an X-ray source moving in a limited angle interval are used to reconstruct 3D image of breast. Several reconstruction algorithms are available for DBT imaging. Filtered back projection algorithm has traditionally been used to reconstruct images from projections. Iterative reconstruction algorithms such as algebraic reconstruction technique (ART) were later developed. Recently, compressed sensing based methods have been proposed in tomosynthesis imaging problem. We have developed an object-oriented simulator for 3D digital breast tomosynthesis (DBT) imaging system using C++ programming language. The simulator is capable of implementing different iterative and compressed sensing based reconstruction methods on 3D digital tomosynthesis data sets and phantom models. A user friendly graphical user interface (GUI) helps users to select and run the desired methods on the designed phantom models or real data sets. The simulator has been tested on a phantom study that simulates breast tomosynthesis imaging problem. Results obtained with various methods including algebraic reconstruction technique (ART) and total variation regularized reconstruction techniques (ART+TV) are presented. Reconstruction results of the methods are compared both visually and quantitatively by evaluating performances of the methods using mean structural similarity (MSSIM) values. PMID:24371468

  11. Online Stereo 3D Simulation in Studying the Spherical Pendulum in Conservative Force Field

    ERIC Educational Resources Information Center

    Zabunov, Svetoslav S.

    2013-01-01

    The current paper aims at presenting a modern e-learning method and tool that is utilized in teaching physics in the universities. An online stereo 3D simulation is used for e-learning mechanics and specifically the teaching of spherical pendulum as part of the General Physics course for students in the universities. This approach was realized on…

  12. PEGASUS. 3D Direct Simulation Monte Carlo Code Which Solves for Geometrics

    SciTech Connect

    Bartel, T.J.

    1998-12-01

    Pegasus is a 3D Direct Simulation Monte Carlo Code which solves for geometries which can be represented by bodies of revolution. Included are all the surface chemistry enhancements in the 2D code Icarus as well as a real vacuum pump model. The code includes multiple species transport.

  13. Trapping solids at the inner edge of the dead zone: 3-D global MHD simulations

    NASA Astrophysics Data System (ADS)

    Dzyurkevich, N.; Flock, M.; Turner, N. J.; Klahr, H.; Henning, Th.

    2010-06-01

    Context. The poorly-ionized interior of the protoplanetary disk or “dead zone” is the location where dust coagulation processes may be most efficient. However even here, planetesimal formation may be limited by the loss of solid material through radial drift, and by collisional fragmentation of the particles. Both depend on the turbulent properties of the gas. Aims: Our aim here is to investigate the possibility that solid particles are trapped at local pressure maxima in the dynamically evolving disk. We perform the first 3-D global non-ideal magnetohydrodynamical (MHD) calculations of a section of the disk treating the turbulence driven by the magneto-rotational instability (MRI). Methods: We use the ZeusMP code with a fixed Ohmic resistivity distribution. The domain contains an inner MRI-active region near the young star and an outer midplane dead zone, with the transition between the two modeled by a sharp increase in the magnetic diffusivity. Results: The azimuthal magnetic fields generated in the active zone oscillate over time, changing sign about every 150 years. We thus observe the radial structure of the “butterfly pattern” seen previously in local shearing-box simulations. The mean magnetic field diffuses from the active zone into the dead zone, where the Reynolds stress nevertheless dominates, giving a residual α between 10-4 and 10-3. The greater total accretion stress in the active zone leads to a net reduction in the surface density, so that after 800 years an approximate steady state is reached in which a local radial maximum in the midplane pressure lies near the transition radius. We also observe the formation of density ridges within the active zone. Conclusions: The dead zone in our models possesses a mean magnetic field, significant Reynolds stresses and a steady local pressure maximum at the inner edge, where the outward migration of planetary embryos and the efficient trapping of solid material are possible.

  14. 3-D Particle Tracking Velocimetry: Development and Applications in Small Scale Flows

    NASA Astrophysics Data System (ADS)

    Tien, Wei-Hsin

    The thesis contains two parts of studies. In part I, a novel volumetric velocimetry technique is developed to measure the 3-D flow field of small-scale flows. The technique utilizes a color-coded pinhole plate with multiple light sources aligned to each pinhole to achieve high particle image density and large measurable depth on a single lens microscope system. A color separation algorithm and an improved particle identification algorithm are developed to identify individual particle images from each pinhole view. Furthermore, a calibration-based technique based on epi-polar line search method is developed to reconstruct the spatial coordinates of the particle, and a new two-frame tracking particle-tracking algorithm is developed to calculate the velocity field. The system was setup to achieve a magnification of 2.69, resulting in an imaging volume of 3.35 x 2.5 x 1.5 mm3 and showed satisfactory measurement accuracy. The technique was then further miniaturized to achieve a magnification of 10, resulting in a imaging volume of 600 x 600 x 600 microm3. The system was applied to a backward-facing step flow to test its ability to reconstruct the unsteady flow field with two-frame tracking. Finally, this technique was applied to a steady streaming flow field in a microfluidic device used to trap particles. The results revealed the three-dimensional flow structure that has not been observed in previous studies, and provided insights to the design of a more efficient trapping device. In part II, an in-vitro study was carried out to investigate the flow around a prosthetic venous valve. Using 2-D PIV, the dynamics of the valve motion was captured and the velocity fields were measured to investigate the effect of the sinus pocket and the coupling effect of a pair of valves. The PIV and hemodynamic results showed that the sinus pocket around the valve functioned as a flow regulator to smooth the entrained velocity profile and suppress the jet width. For current prosthetic

  15. 3D Radiative Transfer in Eta Carinae: Application of the SimpleX Algorithm to 3D SPH Simulations of Binary Colliding Winds

    NASA Technical Reports Server (NTRS)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Icke, V.; Gull, T. R.

    2014-01-01

    Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in Eta Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in Eta Car. We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidden emission lines can form. Including collisional ionization is necessary to achieve a better description of the ionization states, especially in the areas shielded from the secondary's radiation. We find that reducing the primary's mass-loss rate increases the volume of ionized gas, creating larger areas where the forbidden emission lines can form. We conclude that post processing 3D SPH data with SimpleX is a viable tool to create ionization maps for Eta Car.

  16. 3D Radiative Transfer in Eta Carinae: Application of the SimpleX Algorithm to 3D SPH Simulations of Binary Colliding Winds

    NASA Technical Reports Server (NTRS)

    Clementel, N.; Madura, T. I.; Kruip, C.J.H.; Icke, V.; Gull, T. R.

    2014-01-01

    Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in eta Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in eta Car.We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidden emission lines can form. Including collisional ionization is necessary to achieve a better description of the ionization states, especially in the areas shielded from the secondary's radiation. We find that reducing the primary's mass-loss rate increases the volume of ionized gas, creating larger areas where the forbidden emission lines can form.We conclude that post processing 3D SPH data with SimpleX is a viable tool to create ionization maps for eta Car.

  17. 3D Particle image velocimetry test of inner flow in a double blade pump impeller

    NASA Astrophysics Data System (ADS)

    Liu, Houlin; Wang, Kai; Yuan, Shouqi; Tan, Minggao; Wang, Yong; Ru, Weimin

    2012-05-01

    The double blade pump is widely used in sewage treatment industry, however, the research on the internal flow characteristics of the double blade pump with particle image velocimetry (PIV) technology is very little at present. To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions, inner flows in a double blade pump impeller, whose specific speed is 111, are measured under the five off-design conditions and design condition by using 3D PIV test technology. In order to ensure the accuracy of the 3D PIV test, the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied. The 3D PIV relative velocity synthesis procedure is compiled by using Visual C++ 2005. Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained. Test results show that vortex exists in each condition, but the location, size and velocity of vortex core are different. Average absolute velocity value of impeller outlet increases at first, then decreases, and then increases again with increase of flow rate. Again average relative velocity values under 0.4, 0.8, and 1.2 design condition are higher than that under 1.0 design condition, while under 0.6 and 1.4 design condition it is lower. Under low flow rate conditions, radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate, while that of relative velocities at the suction side near the pump shaft decreases. Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions. The research results can be applied to instruct the hydraulic optimization design of double blade pumps.

  18. Dynamic earthquake rupture simulation on nonplanar faults embedded in 3D geometrically complex, heterogeneous Earth models

    NASA Astrophysics Data System (ADS)

    Duru, K.; Dunham, E. M.; Bydlon, S. A.; Radhakrishnan, H.

    2014-12-01

    Dynamic propagation of shear ruptures on a frictional interface is a useful idealization of a natural earthquake.The conditions relating slip rate and fault shear strength are often expressed as nonlinear friction laws.The corresponding initial boundary value problems are both numerically and computationally challenging.In addition, seismic waves generated by earthquake ruptures must be propagated, far away from fault zones, to seismic stations and remote areas.Therefore, reliable and efficient numerical simulations require both provably stable and high order accurate numerical methods.We present a numerical method for:a) enforcing nonlinear friction laws, in a consistent and provably stable manner, suitable for efficient explicit time integration;b) dynamic propagation of earthquake ruptures along rough faults; c) accurate propagation of seismic waves in heterogeneous media with free surface topography.We solve the first order form of the 3D elastic wave equation on a boundary-conforming curvilinear mesh, in terms of particle velocities and stresses that are collocated in space and time, using summation-by-parts finite differences in space. The finite difference stencils are 6th order accurate in the interior and 3rd order accurate close to the boundaries. Boundary and interface conditions are imposed weakly using penalties. By deriving semi-discrete energy estimates analogous to the continuous energy estimates we prove numerical stability. Time stepping is performed with a 4th order accurate explicit low storage Runge-Kutta scheme. We have performed extensive numerical experiments using a slip-weakening friction law on non-planar faults, including recent SCEC benchmark problems. We also show simulations on fractal faults revealing the complexity of rupture dynamics on rough faults. We are presently extending our method to rate-and-state friction laws and off-fault plasticity.

  19. Development of a 3D-printed external ventricular drain placement simulator: technical note.

    PubMed

    Tai, Bruce L; Rooney, Deborah; Stephenson, Francesca; Liao, Peng-Siang; Sagher, Oren; Shih, Albert J; Savastano, Luis E

    2015-10-01

    In this paper, the authors present a physical model developed to simulate accurate external ventricular drain (EVD) placement with realistic haptic and visual feedbacks to serve as a platform for complete procedural training. Insertion of an EVD via ventriculostomy is a common neurosurgical procedure used to monitor intracranial pressures and/or drain CSF. Currently, realistic training tools are scarce and mainly limited to virtual reality simulation systems. The use of 3D printing technology enables the development of realistic anatomical structures and customized design for physical simulators. In this study, the authors used the advantages of 3D printing to directly build the model geometry from stealth head CT scans and build a phantom brain mold based on 3D scans of a plastinated human brain. The resultant simulator provides realistic haptic feedback during a procedure, with visualization of catheter trajectory and fluid drainage. A multiinstitutional survey was also used to prove content validity of the simulator. With minor refinement, this simulator is expected to be a cost-effective tool for training neurosurgical residents in EVD placement. PMID:26115472

  20. Plane shear flows of frictionless spheres: Kinetic theory and 3D soft-sphere discrete element method simulations

    SciTech Connect

    Vescovi, D.; Berzi, D.; Richard, P.

    2014-05-15

    We use existing 3D Discrete Element simulations of simple shear flows of spheres to evaluate the radial distribution function at contact that enables kinetic theory to correctly predict the pressure and the shear stress, for different values of the collisional coefficient of restitution. Then, we perform 3D Discrete Element simulations of plane flows of frictionless, inelastic spheres, sheared between walls made bumpy by gluing particles in a regular array, at fixed average volume fraction and distance between the walls. The results of the numerical simulations are used to derive boundary conditions appropriated in the cases of large and small bumpiness. Those boundary conditions are, then, employed to numerically integrate the differential equations of Extended Kinetic Theory, where the breaking of the molecular chaos assumption at volume fraction larger than 0.49 is taken into account in the expression of the dissipation rate. We show that the Extended Kinetic Theory is in very good agreement with the numerical simulations, even for coefficients of restitution as low as 0.50. When the bumpiness is increased, we observe that some of the flowing particles are stuck in the gaps between the wall spheres. As a consequence, the walls are more dissipative than expected, and the flows resemble simple shear flows, i.e., flows of rather constant volume fraction and granular temperature.

  1. Mapping dynamic mechanical remodeling in 3D tumor models via particle tracking microrheology

    NASA Astrophysics Data System (ADS)

    Jones, Dustin P.; Hanna, William; Celli, Jonathan P.

    2015-03-01

    Particle tracking microrheology (PTM) has recently been employed as a non-destructive way to longitudinally track physical changes in 3D pancreatic tumor co-culture models concomitant with tumor growth and invasion into the extracellular matrix (ECM). While the primary goal of PTM is to quantify local viscoelasticity via the Generalized Stokes-Einstein Relation (GSER), a more simplified way of describing local tissue mechanics lies in the tabulation and subsequent visualization of the spread of probe displacements in a given field of view. Proper analysis of this largely untapped byproduct of standard PTM has the potential to yield valuable insight into the structure and integrity of the ECM. Here, we use clustering algorithms in R to analyze the trajectories of probes in 3D pancreatic tumor/fibroblast co-culture models in an attempt to differentiate between probes that are effectively constrained by the ECM and/or contractile traction forces, and those that exhibit uninhibited mobility in local water-filled pores. We also discuss the potential pitfalls of this method. Accurately and reproducibly quantifying the boundary between these two categories of probe behavior could result in an effective method for measuring the average pore size in a given region of ECM. Such a tool could prove useful for studying stromal depletion, physical impedance to drug delivery, and degradation due to cellular invasion.

  2. Fast parallel interferometric 3D tracking of numerous optically trapped particles and their hydrodynamic interaction.

    PubMed

    Ruh, Dominic; Tränkle, Benjamin; Rohrbach, Alexander

    2011-10-24

    Multi-dimensional, correlated particle tracking is a key technology to reveal dynamic processes in living and synthetic soft matter systems. In this paper we present a new method for tracking micron-sized beads in parallel and in all three dimensions - faster and more precise than existing techniques. Using an acousto-optic deflector and two quadrant-photo-diodes, we can track numerous optically trapped beads at up to tens of kHz with a precision of a few nanometers by back-focal plane interferometry. By time-multiplexing the laser focus, we can calibrate individually all traps and all tracking signals in a few seconds and in 3D. We show 3D histograms and calibration constants for nine beads in a quadratic arrangement, although trapping and tracking is easily possible for more beads also in arbitrary 2D arrangements. As an application, we investigate the hydrodynamic coupling and diffusion anomalies of spheres trapped in a 3 × 3 arrangement. PMID:22109012

  3. CELSS-3D: a broad computer model simulating a controlled ecological life support system.

    PubMed

    Schneegurt, M A; Sherman, L A

    1997-01-01

    CELSS-3D is a dynamic, deterministic, and discrete computer simulation of a controlled ecological life support system (CELSS) focusing on biological issues. A series of linear difference equations within a graphic-based modeling environment, the IThink program, was used to describe a modular CELSS system. The overall model included submodels for crop growth chambers, food storage reservoirs, the human crew, a cyanobacterial growth chamber, a waste processor, fixed nitrogen reservoirs, and the atmospheric gases, CO, O2, and N2. The primary process variable was carbon, although oxygen and nitrogen flows were also modeled. Most of the input data used in CELSS-3D were from published sources. A separate linear optimization program, What'sBest!, was used to compare options for the crew's vegetarian diet. CELSS-3D simulations were run for the equivalent of 3 years with a 1-h time interval. Output from simulations run under nominal conditions was used to illustrate dynamic changes in the concentrations of atmospheric gases. The modular design of CELSS-3D will allow other configurations and various failure scenarios to be tested and compared. PMID:11540449

  4. 3D FEM Simulation of Rolling Load Working on Piercer Plug in Mannesmann Piercing Process

    NASA Astrophysics Data System (ADS)

    Yoshida, Motohisa

    2010-06-01

    This paper presents 3D FEM simulation of piercer plug in Mannesmann piercing process. Target is establishment of a virtual piercing experiment tool to assistant piercer plug development. FEM simulation analysis has been applied to Mannesmann piercing process previously. Aspect of those studies is how to simulate material flow in piercing process, especially focused on how to describe ductile fracture which is known as Mannesmann effect. Thus far, simulation of rolling tools has not been focused. Present piercer plugs, made of special alloys, are damaged severely and quickly in case of piercing higher Cr contented alloys in seamless steel tube production process. Therefore, development of FEM simulation on rolling tools has been demanded in production side. 3D FEM analysis of piercer plug is performed with ALE (Arbitrary Lagrangian—Eulerian) method by using ABAQUS/Explicit 6.9. Simulations are thermo-mechanical, elasto-plastic coupled, and dynamic calculation. Piercer plug and the billet are modeled by solid elements to analyze various factors on stress, strain and temperature. Ductile fracture is not considered in the simulations. Simulation results are correlated sufficiently to experimental results on damage of piercer plugs. Verifying absolute value of simulated factors is hard since there are few empirical methods to measure them. As a conclusion, studied simulations are sufficient as a virtual piercing experiment tool to develop higher performance piercer plugs.

  5. Polyribosomes Are Molecular 3D Nanoprinters That Orchestrate the Assembly of Vault Particles

    PubMed Central

    2014-01-01

    Ribosomes are molecular machines that function in polyribosome complexes to translate genetic information, guide the synthesis of polypeptides, and modulate the folding of nascent proteins. Here, we report a surprising function for polyribosomes as a result of a systematic examination of the assembly of a large ribonucleoprotein complex, the vault particle. Structural and functional evidence points to a model of vault assembly whereby the polyribosome acts like a 3D nanoprinter to direct the ordered translation and assembly of the multi-subunit vault homopolymer, a process which we refer to as polyribosome templating. Structure-based mutagenesis and cell-free in vitro expression studies further demonstrated the critical importance of the polyribosome in vault assembly. Polyribosome templating prevents chaos by ensuring efficiency and order in the production of large homopolymeric protein structures in the crowded cellular environment and might explain the origin of many polyribosome-associated molecular assemblies inside the cell. PMID:25354757

  6. Full-field drift Hamiltonian particle orbits in 3D geometry

    NASA Astrophysics Data System (ADS)

    Cooper, W. A.; Graves, J. P.; Brunner, S.; Isaev, M. Yu

    2011-02-01

    A Hamiltonian/Lagrangian theory to describe guiding centre orbit drift motion which is canonical in the Boozer coordinate frame has been extended to include full electromagnetic perturbed fields in anisotropic pressure 3D equilibria with nested magnetic flux surfaces. A redefinition of the guiding centre velocity to eliminate the motion due to finite equilibrium radial magnetic fields and the choice of a gauge condition that sets the radial component of the electromagnetic vector potential to zero are invoked to guarantee that the Boozer angular coordinates retain the canonical structure. The canonical momenta are identified and the guiding centre particle radial drift motion and parallel gyroradius evolution are derived. The particle coordinate position is linearly modified by wave-particle interactions. All the nonlinear wave-wave interactions appear explicitly only in the evolution of the parallel gyroradius. The radial variation of the electrostatic potential is related to the binormal component of the displacement vector for MHD-type perturbations. The electromagnetic vector potential projections can then be determined from the electrostatic potential and the radial component of the MHD displacement vector.

  7. Acoustical vortices on a Chip for 3D single particle manipulation and vorticity control

    NASA Astrophysics Data System (ADS)

    Riaud, Antoine; Thomas, Jean-Louis; Bou Matar, Olivier; Baudoin, Michael

    Surface acoustic waves offer most of the basic functions required for on-chip actuation of fluids at small scales: efficient flow mixing, integrated pumping, particles separation, droplet displacement, atomization, division and fusion. Nevertheless some more advanced functions such as 3D particles manipulation and vorticity control require the introduction of some specific kind of waves called acoustic vortices. These helical waves propagate spinning around a phase singularity called the dark core. On the one hand, the beam angular momentum can be transferred to the fluid and create point-wise vorticity for confined mixing, and on the other the dark core can trap individual particles in an acoustic well for single object manipulation. In this presentation, I will show how acoustical vortices on-a-chip can be synthesized with a programmable electronics and an array of transducers. I will then highlight how some of their specificities can be used for acoustical tweezing and twisting. This work is supported by ANR Project No. ANR-12-BS09-0021-01 and ANR-12- BS09-0021-02, and Rgion Nord Pas de Calais.

  8. DOMINO: A fast 3D cartesian discrete ordinates solver for reference PWR simulations and SPN validation

    SciTech Connect

    Courau, T.; Moustafa, S.; Plagne, L.; Poncot, A.

    2013-07-01

    As part of its activity, EDF R and D is developing a new nuclear core simulation code named COCAGNE. This code relies on DIABOLO, a Simplified PN (SPN) method to compute the neutron flux inside the core for eigenvalue calculations. In order to assess the accuracy of SPN calculations, we have developed DOMINO, a new 3D Cartesian SN solver. The parallel implementation of DOMINO is very efficient and allows to complete an eigenvalue calculation involving around 300 x 10{sup 9} degrees of freedom within a few hours on a single shared-memory supercomputing node. This computation corresponds to a 26-group S{sub 8} 3D PWR core model used to assess the SPN accuracy. At the pin level, the maximal error for the SP{sub 5} DIABOLO fission production rate is lower than 0.2% compared to the S{sub 8} DOMINO reference for this 3D PWR core model. (authors)

  9. 3D dynamic simulation of crack propagation in extracorporeal shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Wijerathne, M. L. L.; Hori, Muneo; Sakaguchi, Hide; Oguni, Kenji

    2010-06-01

    Some experimental observations of Shock Wave Lithotripsy(SWL), which include 3D dynamic crack propagation, are simulated with the aim of reproducing fragmentation of kidney stones with SWL. Extracorporeal shock wave lithotripsy (ESWL) is the fragmentation of kidney stones by focusing an ultrasonic pressure pulse onto the stones. 3D models with fine discretization are used to accurately capture the high amplitude shear shock waves. For solving the resulting large scale dynamic crack propagation problem, PDS-FEM is used; it provides numerically efficient failure treatments. With a distributed memory parallel code of PDS-FEM, experimentally observed 3D photoelastic images of transient stress waves and crack patterns in cylindrical samples are successfully reproduced. The numerical crack patterns are in good agreement with the experimental ones, quantitatively. The results shows that the high amplitude shear waves induced in solid, by the lithotriptor generated shock wave, play a dominant role in stone fragmentation.

  10. The program FANS-3D (finite analytic numerical simulation 3-dimensional) and its applications

    NASA Technical Reports Server (NTRS)

    Bravo, Ramiro H.; Chen, Ching-Jen

    1992-01-01

    In this study, the program named FANS-3D (Finite Analytic Numerical Simulation-3 Dimensional) is presented. FANS-3D was designed to solve problems of incompressible fluid flow and combined modes of heat transfer. It solves problems with conduction and convection modes of heat transfer in laminar flow, with provisions for radiation and turbulent flows. It can solve singular or conjugate modes of heat transfer. It also solves problems in natural convection, using the Boussinesq approximation. FANS-3D was designed to solve heat transfer problems inside one, two and three dimensional geometries that can be represented by orthogonal planes in a Cartesian coordinate system. It can solve internal and external flows using appropriate boundary conditions such as symmetric, periodic and user specified.

  11. 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.

  12. Multidimensional multiphysics simulation of TRISO particle fuel

    NASA Astrophysics Data System (ADS)

    Hales, J. D.; Williamson, R. L.; Novascone, S. R.; Perez, D. M.; Spencer, B. W.; Pastore, G.

    2013-11-01

    Multidimensional multiphysics analysis of TRISO-coated particle fuel using the BISON finite element nuclear fuels code is described. The governing equations and material models applicable to particle fuel and implemented in BISON are outlined. Code verification based on a recent IAEA benchmarking exercise is described, and excellent comparisons are reported. Multiple TRISO-coated particles of increasing geometric complexity are considered. The code's ability to use the same algorithms and models to solve problems of varying dimensionality from 1D through 3D is demonstrated. The code provides rapid solutions of 1D spherically symmetric and 2D axially symmetric models, and its scalable parallel processing capability allows for solutions of large, complex 3D models. Additionally, the flexibility to easily include new physical and material models and straightforward ability to couple to lower length scale simulations makes BISON a powerful tool for simulation of coated-particle fuel. Future code development activities and potential applications are identified.

  13. Fast error simulation of optical 3D measurements at translucent objects

    NASA Astrophysics Data System (ADS)

    Lutzke, P.; Kühmstedt, P.; Notni, G.

    2012-09-01

    The scan results of optical 3D measurements at translucent objects deviate from the real objects surface. This error is caused by the fact that light is scattered in the objects volume and is not exclusively reflected at its surface. A few approaches were made to separate the surface reflected light from the volume scattered. For smooth objects the surface reflected light is dominantly concentrated in specular direction and could only be observed from a point in this direction. Thus the separation either leads to measurement results only creating data for near specular directions or provides data from not well separated areas. To ensure the flexibility and precision of optical 3D measurement systems for translucent materials it is necessary to enhance the understanding of the error forming process. For this purpose a technique for simulating the 3D measurement at translucent objects is presented. A simple error model is shortly outlined and extended to an efficient simulation environment based upon ordinary raytracing methods. In comparison the results of a Monte-Carlo simulation are presented. Only a few material and object parameters are needed for the raytracing simulation approach. The attempt of in-system collection of these material and object specific parameters is illustrated. The main concept of developing an error-compensation method based on the simulation environment and the collected parameters is described. The complete procedure is using both, the surface reflected and the volume scattered light for further processing.

  14. 3D Plasma Equilibrium and Stability with Hot Particle Anisotropic Pressure

    SciTech Connect

    Cooper, W. A.; Graves, J. P.; Hirshman, S. P.; Merkel, P.; Kisslinger, J.; Wobig, H. F. G.; Watanabe, K. Y.; Narushima, Y.

    2008-11-01

    The anisotropic pressure free-boundary three-dimsnsional (3D) equilibrium code ANI-MEC with nested magnetic flux surfaces has been developed as an extension of the VMEC2000 code. The preconditioning algorithm included is exploited to allow the computation of equilibrium states with radial force balance error improvements exceeding 4 orders of magnitude compared with the non-conditioned results. Large off-axis energetic particle deposition has been applied in a 2-field period quasiaxisymmetric stellarator reactor at <{beta}>{approx_equal}4.5% to test the limitations of the code. The hot particle pressures are roughly uniform around the flux surfaces when p{sub parallel}>p{sub perpendicular}. The fast particle perpendicular pressures localise in the region of deposition for p{sub perpendicular}>p{sub parallel}, while the energetic particle parallel pressures concentrate on the low-field side. Two anisotropic pressure models for global fluid stability implemented in the TERPSICHORE code have been applied to the LHD Heliotron for a sequence of equilibria with fixed <{beta}{sub dia}>{approx_equal}5%(<{beta}{sub th}>{approx_equal}3.5%) varying the fast particle temperature ratio T{sub parallel}/T{sub perpendicular}. Global magnetohydrodynamic modes are quasi-stable according to the model with rigid hot particle layers, while they become stabilised according to the fully interacting energetic particle model with increasing T{sub parallel}/T{sub perpendicular}. As T{sub parallel}/T{sub perpendicular} approaches 3, however, the n = 1 mode family becomes unstable. A transition from a nearly stable quasi-external ballooning-interchange structure to a weakly unstable internal kink mode takes place. The investigation of beam-driven fusion in a Heliotron system is broached. A background plasma with cold ions and warm electrons at <{beta}{sub ith}>{approx_equal}1% is examined with fixed T{sub parallel}/T{sub perpendicular} = 10 in which the hot particle contribution to <{beta

  15. 3-D land subsidence simulation using the NDIS package for MODFLOW

    NASA Astrophysics Data System (ADS)

    Kang, D. H.; Li, J.

    2015-11-01

    The standard subsidence package for MODFLOW, MODFLOW-SUB simulates aquifer-system compaction and subsidence assuming that only 1-D-vertical displacement of the aquifer system occurs in response to applied stresses such as drawdowns accompanying groundwater extraction. In the present paper, 3-D movement of an aquifer system in responses to one or more pumping wells is considered using the new aquifer-system deformation package for MODFLOW, NDIS. The simulation of aquifer- system 3-D movement using NDIS was conducted with a stress or hydraulic head dependent specific storage coefficient to simulate nonlinear deformation behavior of aquifer-system sedimentary materials. NDIS's numerical simulation for aquifer horizontal movement is consistent with an analytic solution for horizontal motion in response to pumping from a leaky confined aquifer (Li, 2007). For purposes of comparison, vertical subsidence of the aquifer system in response to groundwater pumping is simulated by the both the NDIS and MODFLOW-SUB models. The results of the simulations show that land subsidence simulated by MODFLOW-SUB is significantly larger and less sensitive to pumping rate and time than that simulated by NDIS. The NDIS simulations also suggest that if the total pumpage is the same, pumping from a single well may induce more land subsidence than pumping from multiple wells.

  16. Direct measurement of particle size and 3D velocity of a gas-solid pipe flow with digital holographic particle tracking velocimetry.

    PubMed

    Wu, Yingchun; Wu, Xuecheng; Yao, Longchao; Gréhan, Gérard; Cen, Kefa

    2015-03-20

    The 3D measurement of the particles in a gas-solid pipe flow is of great interest, but remains challenging due to curved pipe walls in various engineering applications. Because of the astigmatism induced by the pipe, concentric ellipse fringes in the hologram of spherical particles are observed in the experiments. With a theoretical analysis of the particle holography by an ABCD matrix, the in-focus particle image can be reconstructed by the modified convolution method and fractional Fourier transform. Thereafter, the particle size, 3D position, and velocity are simultaneously measured by digital holographic particle tracking velocimetry (DHPTV). The successful application of DHPTV to the particle size and 3D velocity measurement in a glass pipe's flow can facilitate its 3D diagnostics. PMID:25968543

  17. A novel 3D micron-scale DPTV (Defocused Particle Tracking Velocimetry) and its applications in microfluidic devices

    NASA Astrophysics Data System (ADS)

    Roberts, John

    2005-11-01

    The rapid advancements in micro/nano biotechnology demand quantitative tools for characterizing microfluidic flows in lab-on-a-chip applications, validation of computational results for fully 3D flows in complex micro-devices, and efficient observation of cellular dynamics in 3D. We present a novel 3D micron-scale DPTV (defocused particle tracking velocimetry) that is capable of mapping out 3D Lagrangian, as well as 3D Eulerian velocity flow fields at sub-micron resolution and with one camera. The main part of the imaging system is an epi-fluorescent microscope (Olympus IX 51), and the seeding particles are fluorescent particles with diameter range 300nm - 10um. A software package has been developed for identifying (x,y,z,t) coordinates of the particles using the defocused images. Using the imaging system, we successfully mapped the pressure driven flow fields in microfluidic channels. In particular, we measured the Laglangian flow fields in a microfluidic channel with a herring bone pattern at the bottom, the later is used to enhance fluid mixing in lateral directions. The 3D particle tracks revealed the flow structure that has only been seen in numerical computation. This work is supported by the National Science Foundation (CTS - 0514443), the Nanobiotechnology Center at Cornell, and The New York State Center for Life Science Enterprise.

  18. The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis

    SciTech Connect

    Shaheen, Eman; Van Ongeval, Chantal; Zanca, Federica; Cockmartin, Lesley; Marshall, Nicholas; Jacobs, Jurgen; Young, Kenneth C.; Dance, David R.; Bosmans, Hilde

    2011-12-15

    Purpose: This work proposes a new method of building 3D models of microcalcification clusters and describes the validation of their realistic appearance when simulated into 2D digital mammograms and into breast tomosynthesis images. Methods: A micro-CT unit was used to scan 23 breast biopsy specimens of microcalcification clusters with malignant and benign characteristics and their 3D reconstructed datasets were segmented to obtain 3D models of microcalcification clusters. These models were then adjusted for the x-ray spectrum used and for the system resolution and simulated into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. Six radiologists were asked to distinguish between 40 real and 40 simulated clusters of microcalcifications in two separate studies on 2D mammography and tomosynthesis datasets. Receiver operating characteristic (ROC) analysis was used to test the ability of each observer to distinguish between simulated and real microcalcification clusters. The kappa statistic was applied to assess how often the individual simulated and real microcalcification clusters had received similar scores (''agreement'') on their realistic appearance in both modalities. This analysis was performed for all readers and for the real and the simulated group of microcalcification clusters separately. ''Poor'' agreement would reflect radiologists' confusion between simulated and real clusters, i.e., lesions not systematically evaluated in both modalities as either simulated or real, and would therefore be interpreted as a success of the present models. Results: The area under the ROC curve, averaged over the observers, was 0.55 (95% confidence interval [0.44, 0.66]) for the 2D study, and 0.46 (95% confidence interval [0.29, 0.64]) for the tomosynthesis study, indicating no statistically significant difference between real and simulated

  19. Modeling the influence of particle morphology on the fracture behavior of silica sand using a 3D discrete element method

    NASA Astrophysics Data System (ADS)

    Cil, Mehmet B.; Alshibli, Khalid A.

    2015-02-01

    The constitutive behavior and deformation characteristics of uncemented granular materials are to a large extent derived from the fabric or geometry of the particle structure and the interparticle friction resulting from normal forces acting on particles or groups of particles. Granular materials consist of discrete particles with a fabric (microstructure) that changes under loading. Synchrotron micro-computed tomography (SMT) has emerged as a powerful non-destructive 3D scanning technique to study geomaterials. In this paper, SMT was used to acquire in situ scans of the oedometry test of a column of three silica sand particles. The sand is known as ASTM 20-30 Ottawa sand, and has a grain size between US sieves #20 (0.841 mm) and #30 (0.595 mm). The characteristics and evolution of particle fracture in sand were examined using SMT images, and a 3D discrete element method (DEM) was used to model the fracture behavior of sand particles. It adopts the bonded particle model to generate a crushable agglomerate that consists of a large number of small spherical sub-particles. The agglomerate shape matches the 3D physical shape of the tested sand particles by mapping the particle morphology from the SMT images. The paper investigates and discusses the influence of agglomerate packing (i.e., the number and size distribution of spherical sub-particles that constitute the agglomerate) and agglomerate shape on the fracture behavior of crushable particles.

  20. Development of discrete gas kinetic scheme for simulation of 3D viscous incompressible and compressible flows

    NASA Astrophysics Data System (ADS)

    Yang, L. M.; Shu, C.; Wang, Y.; Sun, Y.

    2016-08-01

    The sphere function-based gas kinetic scheme (GKS), which was presented by Shu and his coworkers [23] for simulation of inviscid compressible flows, is extended to simulate 3D viscous incompressible and compressible flows in this work. Firstly, we use certain discrete points to represent the spherical surface in the phase velocity space. Then, integrals along the spherical surface for conservation forms of moments, which are needed to recover 3D Navier-Stokes equations, are approximated by integral quadrature. The basic requirement is that these conservation forms of moments can be exactly satisfied by weighted summation of distribution functions at discrete points. It was found that the integral quadrature by eight discrete points on the spherical surface, which forms the D3Q8 discrete velocity model, can exactly match the integral. In this way, the conservative variables and numerical fluxes can be computed by weighted summation of distribution functions at eight discrete points. That is, the application of complicated formulations resultant from integrals can be replaced by a simple solution process. Several numerical examples including laminar flat plate boundary layer, 3D lid-driven cavity flow, steady flow through a 90° bending square duct, transonic flow around DPW-W1 wing and supersonic flow around NACA0012 airfoil are chosen to validate the proposed scheme. Numerical results demonstrate that the present scheme can provide reasonable numerical results for 3D viscous flows.

  1. Holographic particle image velocimetry: a comparison of digital shearing and 3D correlation analysis methods

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Alcock, Rob D.; Halliwell, Neil A.; Coupland, Jeremy M.

    2003-11-01

    In the past, the use of optical and digital three-dimensional correlation methods have been demonstrated to extract velocity data from the complex amplitude distribution of particle images in holographic particle image velocimetry (HPIV). Recently we have proposed a digital shearing method to extract three-component particle displacement data throughout a complete image field. In contrast to full three-dimensional correlation, it has been shown that all three components of particle image displacement can be retrieved using just four two-dimensional fast Fourier transform (FFT) operations and appropriate coordinate transformations. In this paper we describe three-dimensional correlation and digital shearing methods and compare their performance in terms of computational efficiency and measurement accuracy. The simulated results show that the digital shearing method has comparable accuracy to three-dimensional correlation but is significantly faster.

  2. Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.

    PubMed

    Szőke, I; Louka, M N; Bryntesen, T R; Bratteli, J; Edvardsen, S T; RøEitrheim, K K; Bodor, K

    2014-06-01

    This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation's lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers.IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry.This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors. PMID:24727389

  3. A cut cell method for the 3D simulation of Crookes radiometer

    SciTech Connect

    Dechriste, Guillaume; Mieussens, Luc

    2014-12-09

    Devices involved in engineering applications, such as vacuum pumps or MEMS, may be made of several moving parts. This raise the issue of the simulation of rarefied gas flow around moving boundaries. We propose a simple process, known as cut cell method, to treat the motion of a solid body in the framework of the deterministic solving of a kinetic equation. Up to our knowledge, this is the first time that this approach has been used for this kind of simulations. The method is illustrated by the 2D and 3D simulations of a Crookes radiometer.

  4. Determination of key parameters of SEU occurrence using 3-D full cell SRAM simulations

    SciTech Connect

    Roche, P.; Palau, J.M.; Bruguier, G.; Tavernier, C.; Ecoffet, R.; Gasiot, J.

    1999-12-01

    A 3-D entire SRAM cell, based on a 0.35-{micro}m current CMOS technology, is simulated in this work with a DEVICE simulator. The transient current, resulting from a heavy ion strike in the most sensitive region of the cell, is studied as a function of the LET value, the cell layout and the ion penetration depth. A definition of the critical charge is proposed and two new methods are presented to compute this basic amount of charge only using SPICE simulations. Numerical applications are performed with two different generations of submicron CMOS technologies, including the determination of the sensitive thicknesses.

  5. Random Telegraph Signal Amplitudes in Sub 100 nm (Decanano) MOSFETs: A 3D 'Atomistic' Simulation Study

    NASA Technical Reports Server (NTRS)

    Asenov, Asen; Balasubramaniam, R.; Brown, A. R.; Davies, J. H.; Saini, Subhash

    2000-01-01

    In this paper we use 3D simulations to study the amplitudes of random telegraph signals (RTS) associated with the trapping of a single carrier in interface states in the channel of sub 100 nm (decanano) MOSFETs. Both simulations using continuous doping charge and random discrete dopants in the active region of the MOSFETs are presented. We have studied the dependence of the RTS amplitudes on the position of the trapped charge in the channel and on the device design parameters. We have observed a significant increase in the maximum RTS amplitude when discrete random dopants are employed in the simulations.

  6. Reactive Flow Modeling of Liquid Explosives via ALE3D/Cheetah Simulations

    SciTech Connect

    Kuo, I W; Bastea, S; Fried, L E

    2010-03-10

    We carried out reactive flow simulations of liquid explosives such as nitromethane using the hydrodynamic code ALE3D coupled with equations of state and reaction kinetics modeled by the thermochemical code Cheetah. The simulation set-up was chosen to mimic cylinder experiments. For pure unconfined nitromethane we find that the failure diameter and detonation velocity dependence on charge diameter are in agreement with available experimental results. Such simulations are likely to be useful for determining detonability and failure behavior for a wide range of experimental conditions and explosive compounds.

  7. SU-E-T-380: Particle Microdosimetry Study Based On 3D-Cylindrical Silicon Radiaton Detectors

    SciTech Connect

    Guardiola, C; Carabe-Fernandez, A; Gomez, F; Pellegrini, G; Fleta, C; Quirion, D; Lozano, M

    2014-06-01

    Purpose: A new design of a solid-state-microdetector based on silicon 3D microfabrication and its performance to characterise Lineal energy, Specific Energy, dose, LET and other microdosimetric variables required for modelling particle relative biological effectiveness (RBE) is presented. Methods: A microdosimeter formed by a matrix of independent sensors with well-defined micrometric cylindrical shape and with a volume similar to those of cellular dimensions is used to measure microdosimetric variables. Each sensor measures the radiation deposited energy which, divided by the mean cord length of the sensors, provides us with the Linear Energy (y) of the radiation as well as its energy distribution, and frequencymean. Starting from the these distributions in different points of a proton beam, we generate biophysical data (e.g. Linear Energy Transfer (LET), Specific Energy (z), etc…) needed for relative biological effectiveness (RBE) calculations radiation effect models used in particle radiotherapy treatment planning. In addition, a Tissue Equivalent Proportional Counter (TEPC) will be used as baseline to calibrate the “y” magnitude of the microdosimeter unit-cells. Results: The experimental measurements will soon be carried out at the Perelman Center for Advanced Medicine (University of Pennsylvania), which provides proton beam for clinical research proposals. The results of distributions measured of the microdosimetric variables from the first tests developed in the proton facility will be presented and compared with Monte Carlo simulations using the Geant4 code. Conclusion: The use of 3D microdosimeters such as the one presented here will enhance the accuracy of RBE calculations normally affected by the inherent uncertainty of monte carlo simulations due to the approximation of material composition and energy dependent physical laws involved in such calculations. The effect of such approximations will be quatified by comparison with absolute measurement of

  8. 3D modeling and simulation of 2G HTS stacks and coils

    NASA Astrophysics Data System (ADS)

    Zermeño, Víctor M. R.; Grilli, Francesco

    2014-04-01

    Use of 2G HTS coated conductors in several power applications has become popular in recent years. Their large current density under high magnetic fields makes them suitable candidates for high power capacity applications such as stacks of tapes, coils, magnets, cables and current leads. For this reason, modeling and simulation of their electromagnetic properties is very desirable in the design and optimization processes. For many applications, when symmetries allow it, simple models consisting of 1D or 2D representations are well suited for providing a satisfying description of the problem at hand. However, certain designs such as racetrack coils and finite-length or non-straight stacks, do pose a 3D problem that cannot be easily reduced to a 2D configuration. Full 3D models have been developed, but their use for simulating superconducting devices is a very challenging task involving a large-scale computational problem. In this work, we present a new method to simulate the electromagnetic transient behavior of 2G HTS stacks and coils. The method, originally used to model stacks of straight superconducting tapes or circular coils in 2D, is now extended to 3D. The main idea is to construct an anisotropic bulk-like equivalent for the stack or coil, such that the geometrical layout of the internal alternating structures of insulating, metallic, superconducting and substrate layers is reduced while keeping the overall electromagnetic behavior of the original device. Besides the aforementioned interest in modeling and simulating 2G HTS coated conductors, this work provides a further step towards efficient 3D modeling and simulation of superconducting devices for large-scale applications.

  9. A Real-time 3D Visualization of Global MHD Simulation for Space Weather Forecasting

    NASA Astrophysics Data System (ADS)

    Murata, K.; Matsuoka, D.; Kubo, T.; Shimazu, H.; Tanaka, T.; Fujita, S.; Watari, S.; Miyachi, H.; Yamamoto, K.; Kimura, E.; Ishikura, S.

    2006-12-01

    Recently, many satellites for communication networks and scientific observation are launched in the vicinity of the Earth (geo-space). The electromagnetic (EM) environments around the spacecraft are always influenced by the solar wind blowing from the Sun and induced electromagnetic fields. They occasionally cause various troubles or damages, such as electrification and interference, to the spacecraft. It is important to forecast the geo-space EM environment as well as the ground weather forecasting. Owing to the recent remarkable progresses of super-computer technologies, numerical simulations have become powerful research methods in the solar-terrestrial physics. For the necessity of space weather forecasting, NICT (National Institute of Information and Communications Technology) has developed a real-time global MHD simulation system of solar wind-magnetosphere-ionosphere couplings, which has been performed on a super-computer SX-6. The real-time solar wind parameters from the ACE spacecraft at every one minute are adopted as boundary conditions for the simulation. Simulation results (2-D plots) are updated every 1 minute on a NICT website. However, 3D visualization of simulation results is indispensable to forecast space weather more accurately. In the present study, we develop a real-time 3D webcite for the global MHD simulations. The 3-D visualization results of simulation results are updated every 20 minutes in the following three formats: (1)Streamlines of magnetic field lines, (2)Isosurface of temperature in the magnetosphere and (3)Isoline of conductivity and orthogonal plane of potential in the ionosphere. For the present study, we developed a 3-D viewer application working on Internet Explorer browser (ActiveX) is implemented, which was developed on the AVS/Express. Numerical data are saved in the HDF5 format data files every 1 minute. Users can easily search, retrieve and plot past simulation results (3D visualization data and numerical data) by using

  10. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  11. 3D radiative transfer simulations of Eta Carinae's inner colliding winds - II. Ionization structure of helium at periastron

    NASA Astrophysics Data System (ADS)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Paardekooper, J.-P.

    2015-06-01

    Spectral observations of the massive colliding wind binary Eta Carinae show phase-dependent variations, in intensity and velocity, of numerous helium emission and absorption lines throughout the entire 5.54-yr orbit. Approaching periastron, the 3D structure of the wind-wind interaction region (WWIR) gets highly distorted due to the eccentric (e ˜ 0.9) binary orbit. The secondary star (ηB) at these phases is located deep within the primary's dense wind photosphere. The combination of these effects is thought to be the cause of the particularly interesting features observed in the helium lines at periastron. We perform 3D radiative transfer simulations of η Car's interacting winds at periastron. Using the SIMPLEX radiative transfer algorithm, we post-process output from 3D smoothed particle hydrodynamic simulations of the inner 150 au of the η Car system for two different primary star mass-loss rates (dot{M}_{η A}). Using previous results from simulations at apastron as a guide for the initial conditions, we compute 3D helium ionization maps. We find that, for higher dot{M}_{η A}, ηB He0+-ionizing photons are not able to penetrate into the pre-shock primary wind. He+ due to ηB is only present in a thin layer along the leading arm of the WWIR and in a small region close to the stars. Lowering dot{M}_{η A} allows ηB's ionizing photons to reach the expanding unshocked secondary wind on the apastron side of the system, and create a low fraction of He+ in the pre-shock primary wind. With apastron on our side of the system, our results are qualitatively consistent with the observed variations in strength and radial velocity of η Car's helium emission and absorption lines, which helps better constrain the regions where these lines arise.

  12. Single Particle Cryo-electron Microscopy and 3-D Reconstruction of Viruses

    PubMed Central

    Guo, Fei; Jiang, Wen

    2014-01-01

    With fast progresses in instrumentation, image processing algorithms, and computational resources, single particle electron cryo-microscopy (cryo-EM) 3-D reconstruction of icosahedral viruses has now reached near-atomic resolutions (3–4 Å). With comparable resolutions and more predictable outcomes, cryo-EM is now considered a preferred method over X-ray crystallography for determination of atomic structure of icosahedral viruses. At near-atomic resolutions, all-atom models or backbone models can be reliably built that allow residue level understanding of viral assembly and conformational changes among different stages of viral life cycle. With the developments of asymmetric reconstruction, it is now possible to visualize the complete structure of a complex virus with not only its icosahedral shell but also its multiple non-icosahedral structural features. In this chapter, we will describe single particle cryo-EM experimental and computational procedures for both near-atomic resolution reconstruction of icosahedral viruses and asymmetric reconstruction of viruses with both icosahedral and non-icosahedral structure components. Procedures for rigorous validation of the reconstructions and resolution evaluations using truly independent de novo initial models and refinements are also introduced. PMID:24357374

  13. Ghost Particle Velocimetry: Accurate 3D Flow Visualization Using Standard Lab Equipment

    NASA Astrophysics Data System (ADS)

    Buzzaccaro, Stefano; Secchi, Eleonora; Piazza, Roberto

    2013-07-01

    We describe and test a new approach to particle velocimetry, based on imaging and cross correlating the scattering speckle pattern generated on a near-field plane by flowing tracers with a size far below the diffraction limit, which allows reconstructing the velocity pattern in microfluidic channels without perturbing the flow. As a matter of fact, adding tracers is not even strictly required, provided that the sample displays sufficiently refractive-index fluctuations. For instance, phase separation in liquid mixtures in the presence of shear is suitable to be directly investigated by this “ghost particle velocimetry” technique, which just requires a microscope with standard lamp illumination equipped with a low-cost digital camera. As a further bonus, the peculiar spatial coherence properties of the illuminating source, which displays a finite longitudinal coherence length, allows for a 3D reconstruction of the profile with a resolution of few tenths of microns and makes the technique suitable to investigate turbid samples with negligible multiple scattering effects.

  14. CAST: Effective and Efficient User Interaction for Context-Aware Selection in 3D Particle Clouds.

    PubMed

    Yu, Lingyun; Efstathiou, Konstantinos; Isenberg, Petra; Isenberg, Tobias

    2016-01-01

    We present a family of three interactive Context-Aware Selection Techniques (CAST) for the analysis of large 3D particle datasets. For these datasets, spatial selection is an essential prerequisite to many other analysis tasks. Traditionally, such interactive target selection has been particularly challenging when the data subsets of interest were implicitly defined in the form of complicated structures of thousands of particles. Our new techniques SpaceCast, TraceCast, and PointCast improve usability and speed of spatial selection in point clouds through novel context-aware algorithms. They are able to infer a user's subtle selection intention from gestural input, can deal with complex situations such as partially occluded point clusters or multiple cluster layers, and can all be fine-tuned after the selection interaction has been completed. Together, they provide an effective and efficient tool set for the fast exploratory analysis of large datasets. In addition to presenting Cast, we report on a formal user study that compares our new techniques not only to each other but also to existing state-of-the-art selection methods. Our results show that Cast family members are virtually always faster than existing methods without tradeoffs in accuracy. In addition, qualitative feedback shows that PointCast and TraceCast were strongly favored by our participants for intuitiveness and efficiency. PMID:26390474

  15. Momentum Transport: 2D and 3D Cloud Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2001-01-01

    The major objective of this study is to investigate the momentum budgets associated with several convective systems that developed during the TOGA COARE IOP (west Pacific warm pool region) and GATE (east Atlantic region). The tool for this study is the improved Goddard Cumulas Ensemble (GCE) model which includes a 3-class ice-phase microphysical scheme, explicit cloud radiative interactive processes and air-sea interactive surface processes. The model domain contains 256 x 256 grid points (with 2 km resolution) in the horizontal and 38 grid points (to a depth of 22 km) in the vertical. The 2D domain has 1024 grid points. The simulations were performed over a 7-day time period (December 19-26, 1992, for TOGA COARE and September 1-7, 1994 for GATE). Cyclic literal boundary conditions are required for this type of long-term integration. Two well organized squall systems (TOGA, COARE February 22, 1993, and GATE September 12, 1994) were also simulated using the 3D GCE model. Only 9 h simulations were required to cover the life time of the squall systems. the lateral boundary conditions were open for these two squall systems simulations. the following will be examined: (1) the momentum budgets in the convective and stratiform regions, (2) the relationship between momentum transport and cloud organization (i.e., well organized squall lines versus less organized convective), (3) the differences and similarities in momentum transport between 2D and 3D simulated convective systems, and (4) the differences and similarities in momentum budgets between cloud systems simulated with open and cyclic lateral boundary conditions. Preliminary results indicate that there are only small differences between 2D and 3D simulated momentum budgets. Major differences occur, however, between momentum budgets associated with squall systems simulated using different lateral boundary conditions.

  16. The 3D Numerical Simulation for the Propagation Process of Multiple Pre-existing Flaws in Rock-Like Materials Subjected to Biaxial Compressive Loads

    NASA Astrophysics Data System (ADS)

    Bi, J.; Zhou, X. P.; Qian, Q. H.

    2016-05-01

    General particle dynamics (GPD), which is a novel meshless numerical method, is proposed to simulate the initiation, propagation and coalescence of 3D pre-existing penetrating and embedded flaws under biaxial compression. The failure process for rock-like materials subjected to biaxial compressive loads is investigated using the numerical code GPD3D. Moreover, internal crack evolution processes are successfully simulated using GPD3D. With increasing lateral stress, the secondary cracks keep growing in the samples, while the growth of the wing cracks is restrained. The samples are mainly split into fragments in a shear failure mode under biaxial compression, which is different from the splitting failure of the samples subjected to uniaxial compression. For specimens with macroscopic pre-existing flaws, the simulated types of cracks, the simulated coalescence types and the simulated failure modes are in good agreement with the experimental results.

  17. SEM simulation for 2D and 3D inspection metrology and defect review

    NASA Astrophysics Data System (ADS)

    Levi, Shimon; Schwartsband, Ishai; Khristo, Sergey; Ivanchenko, Yan; Adan, Ofer

    2014-03-01

    Advanced SEM simulation has become a key element in the ability of SEM inspection, metrology and defect review to meet the challenges of advanced technologies. It grants additional capabilities to the end user, such as 3D height measurements, accurate virtual metrology, and supports Design Based Metrology to bridge the gap between design layout and SEM image. In this paper we present SEM simulations capabilities, which take into consideration all parts of the SEM physical and electronic path, interaction between Electron beam and material, multi perspective SEM imaging and shadowing derived from proximity effects caused by the interaction of the Secondary Electrons signal with neighboring pattern edges. Optimizing trade-off between simulation accuracy, calibration procedures and computational complexity, the simulation is running in real-time with minimum impact on throughput. Experiment results demonstrate Height measurement capacities, and CAD based simulated pattern is compared with SEM image to evaluate simulated pattern fidelity.

  18. Blob Dynamics in 3D BOUT Simulations of Tokamak Edge Turbulence

    SciTech Connect

    Russell, D; D'Ippolito, D; Myra, J; Nevins, W; Xu, X

    2004-08-23

    Propagating filaments of enhanced plasma density, or blobs, observed in 3D numerical simulations of a diverted, neutral-fueled tokamak are studied. Fluctuations of vorticity, electrical potential {phi}, temperature T{sub e} and current density J{sub {parallel}} associated with the blobs have a dipole structure perpendicular to the magnetic field and propagate radially with large E {center_dot} B drift velocities (> 1 km/s). The simulation results are consistent with a 3D blob dynamics model that incorporates increased parallel plasma resistivity (from neutral cooling of the X-point region), blob disconnection from the divertor sheath, X-point closure of the current loops, and collisional physics to sustain the {phi}, T{sub e}, J{sub {parallel}} dipoles.

  19. 3D Kinetic Simulations of Topography-Induced Electric Fields at Itokawa Asteroid

    NASA Astrophysics Data System (ADS)

    Zimmerman, M. I.

    2015-12-01

    Results from a new 3D kinetic simulation code will be presented, showing how Itokawa's interaction with the solar wind plasma creates an ever-evolving electric field structure as the asteroid rotates. The simulations combine (1) a realistic surface shape model of Itokawa, (2) a careful and self-consistent accounting of surface charging processes, and (3) the freely-available FMMLib3d code library implementing the fast multipole method for electric field calculations. Fine details of the surface potential and electric grounding conditions, as revealed by this new code, could provide critical inputs into planning for a future asteroid retrieval mission in which extended, direct contact with the asteroid could occur.

  20. Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes

    NASA Astrophysics Data System (ADS)

    Mathieu, S.; Hamila, N.; Dupé, F.; Descamps, C.; Boisse, P.

    2016-08-01

    The simulation of thick 3D composite reinforcement forming brings to light new modeling challenges. The specific anisotropic material behavior due to the possible slippage between fibers induces, among other phenomena, the development of spurious transverse modes in bending-dominated 3D simulations. To obtain coherent finite element responses, two solutions are proposed. The first one uses a simple assumed strain formulation usually prescribed to prevent volumetric locking. This solution avoids spurious transverse modes by stiffening of the hourglass modes. Nevertheless the deformation obtained by this approach still suffers from the inability of the standard continuum mechanics of Cauchy to describe fibrous material deformation. The second proposed approach is based on the introduction of a bending stiffness which both avoids the spurious transverse modes and also improves the global behavior of the element formulation by enriching the underlying continuum. To emphasize the differences between different formulations, element stiffnesses are explicitly calculated and compared.

  1. Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes

    NASA Astrophysics Data System (ADS)

    Mathieu, S.; Hamila, N.; Dupé, F.; Descamps, C.; Boisse, P.

    2016-03-01

    The simulation of thick 3D composite reinforcement forming brings to light new modeling challenges. The specific anisotropic material behavior due to the possible slippage between fibers induces, among other phenomena, the development of spurious transverse modes in bending-dominated 3D simulations. To obtain coherent finite element responses, two solutions are proposed. The first one uses a simple assumed strain formulation usually prescribed to prevent volumetric locking. This solution avoids spurious transverse modes by stiffening of the hourglass modes. Nevertheless the deformation obtained by this approach still suffers from the inability of the standard continuum mechanics of Cauchy to describe fibrous material deformation. The second proposed approach is based on the introduction of a bending stiffness which both avoids the spurious transverse modes and also improves the global behavior of the element formulation by enriching the underlying continuum. To emphasize the differences between different formulations, element stiffnesses are explicitly calculated and compared.

  2. 3D Immersive Patient Simulators and Their Impact on Learning Success: A Thematic Review

    PubMed Central

    Wahba, Roger; Chang, De-Hua; Plum, Patrick; Hölscher, Arnulf H; Stippel, Dirk L

    2015-01-01

    Background Immersive patient simulators (IPSs) combine the simulation of virtual patients with a three-dimensional (3D) environment and, thus, allow an illusionary immersion into a synthetic world, similar to computer games. Playful learning in a 3D environment is motivating and allows repetitive training and internalization of medical workflows (ie, procedural knowledge) without compromising real patients. The impact of this innovative educational concept on learning success requires review of feasibility and validity. Objective It was the aim of this paper to conduct a survey of all immersive patient simulators currently available. In addition, we address the question of whether the use of these simulators has an impact on knowledge gain by summarizing the existing validation studies. Methods A systematic literature search via PubMed was performed using predefined inclusion criteria (ie, virtual worlds, focus on education of medical students, validation testing) to identify all available simulators. Validation testing was defined as the primary end point. Results There are currently 13 immersive patient simulators available. Of these, 9 are Web-based simulators and represent feasibility studies. None of these simulators are used routinely for student education. The workstation-based simulators are commercially driven and show a higher quality in terms of graphical quality and/or data content. Out of the studies, 1 showed a positive correlation between simulated content and real content (ie, content validity). There was a positive correlation between the outcome of simulator training and alternative training methods (ie, concordance validity), and a positive coherence between measured outcome and future professional attitude and performance (ie, predictive validity). Conclusions IPSs can promote learning and consolidation of procedural knowledge. The use of immersive patient simulators is still marginal, and technical and educational approaches are heterogeneous

  3. Simulation of a true-triaxial deformation test on anisotropic gneiss using FLAC3D

    NASA Astrophysics Data System (ADS)

    Ye, Shenghua; Sehizadeh, Mehdi; Nasseri, Mohammad; Young, Paul

    2016-04-01

    A series of true-triaxial experiments have been carried out at the University of Toronto's Rock Fracture Dynamics Laboratory. Isotropic pegmatite and gneiss have been used to systematically study the effect of anisotropy on the strength, behaviour and seismic response. Samples were loaded under true-triaxial stress conditions and subjected to complex loading and unloading histories associated with rock deformation around underground openings. The results show expected patterns of weakness from preferentially oriented samples and highlight the importance of unloading history under true-triaxial conditions on the deformation and seismic response of the samples. These tests have been used to validate a synthetic simulation using the Itasca FLAC3D numerical code. The paper describes the FLAC3D simulations of the complex true-triaxial loading and unloading history of the different anisotropic samples. Various parameters were created to describe the physico-mechanical properties of the synthetic rock samples. Foliation planes of preferential orientations with respect to the primary loading direction were added to the synthetic rock samples to reflect the anisotropy of the gneiss. These synthetic rock samples were subjected to the same loading and unloading paths as the real rock samples, and failed in the same mechanism as what was observed from the experiments, and thus it proved the validity of this numerical simulation with FLAC3D.

  4. Modeling and simulating the adaptive electrical properties of stochastic polymeric 3D networks

    NASA Astrophysics Data System (ADS)

    Sigala, R.; Smerieri, A.; Schüz, A.; Camorani, P.; Erokhin, V.

    2013-10-01

    Memristors are passive two-terminal circuit elements that combine resistance and memory. Although in theory memristors are a very promising approach to fabricate hardware with adaptive properties, there are only very few implementations able to show their basic properties. We recently developed stochastic polymeric matrices with a functionality that evidences the formation of self-assembled three-dimensional (3D) networks of memristors. We demonstrated that those networks show the typical hysteretic behavior observed in the ‘one input-one output’ memristive configuration. Interestingly, using different protocols to electrically stimulate the networks, we also observed that their adaptive properties are similar to those present in the nervous system. Here, we model and simulate the electrical properties of these self-assembled polymeric networks of memristors, the topology of which is defined stochastically. First, we show that the model recreates the hysteretic behavior observed in the real experiments. Second, we demonstrate that the networks modeled indeed have a 3D instead of a planar functionality. Finally, we show that the adaptive properties of the networks depend on their connectivity pattern. Our model was able to replicate fundamental qualitative behavior of the real organic 3D memristor networks; yet, through the simulations, we also explored other interesting properties, such as the relation between connectivity patterns and adaptive properties. Our model and simulations represent an interesting tool to understand the very complex behavior of self-assembled memristor networks, which can finally help to predict and formulate hypotheses for future experiments.

  5. Simulation and testing of a multichannel system for 3D sound localization

    NASA Astrophysics Data System (ADS)

    Matthews, Edward Albert

    Three-dimensional (3D) audio involves the ability to localize sound anywhere in a three-dimensional space. 3D audio can be used to provide the listener with the perception of moving sounds and can provide a realistic listening experience for applications such as gaming, video conferencing, movies, and concerts. The purpose of this research is to simulate and test 3D audio by incorporating auditory localization techniques in a multi-channel speaker system. The objective is to develop an algorithm that can place an audio event in a desired location by calculating and controlling the gain factors of each speaker. A MATLAB simulation displays the location of the speakers and perceived sound, which is verified through experimentation. The scenario in which the listener is not equidistant from each of the speakers is also investigated and simulated. This research is envisioned to lead to a better understanding of human localization of sound, and will contribute to a more realistic listening experience.

  6. 3D flow past transonic turbine cascade SE 1050 — Experiment and numerical simulations

    NASA Astrophysics Data System (ADS)

    Šimurda, D.; Fürst, J.; Luxa, M.

    2013-08-01

    This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 (known in QNET network as open test case SE1050). The primary goal was to assess the influence of the inlet velocity profile on the flow structures in the interblade channel and on the flow field parameters at the cascade exit and to compare these findings to results of numerical simulations. Investigations of 3D flow past the cascade with non-uniform inlet velocity profile were carried out both experimentally and numerically at subsonic ( M 2is = 0.8) and at transonic ( M 2is = 1.2) regime at design angle of incidence. Experimental data was obtained using a traversing device with a five-hole conical probe. Numerically, the 3D flow was simulated by open source code OpenFOAM and in-house code. Analyses of experimental data and CFD simulations have revealed the development of distinctive vortex structures resulting from non-uniform inlet velocity profile. Origin of these structures results in increased loss of kinetic energy and spanwise shift of kinetic energy loss coefficient distribution. Differences found between the subsonic and the transonic case confirm earlier findings available in the literature. Results of CFD and experiments agree reasonably well.

  7. 3D printing method for freeform fabrication of optical phantoms simulating heterogeneous biological tissue

    NASA Astrophysics Data System (ADS)

    Wang, Minjie; Shen, Shuwei; Yang, Jie; Dong, Erbao; Xu, Ronald

    2014-03-01

    The performance of biomedical optical imaging devices heavily relies on appropriate calibration. However, many of existing calibration phantoms for biomedical optical devices are based on homogenous materials without considering the multi-layer heterogeneous structures observed in biological tissue. Using such a phantom for optical calibration may result in measurement bias. To overcome this problem, we propose a 3D printing method for freeform fabrication of tissue simulating phantoms with multilayer heterogeneous structure. The phantom simulates not only the morphologic characteristics of biological tissue but also absorption and scattering properties. The printing system is based on a 3D motion platform with coordinated control of the DC motors. A special jet nozzle is designed to mix base, scattering, and absorption materials at different ratios. 3D tissue structures are fabricated through layer-by-layer printing with selective deposition of phantom materials of different ingredients. Different mixed ratios of base, scattering and absorption materials have been tested in order to optimize the printing outcome. A spectrometer and a tissue spectrophotometer are used for characterizing phantom absorption and scattering properties. The goal of this project is to fabricate skin tissue simulating phantoms as a traceable standard for the calibration of biomedical optical spectral devices.

  8. The arctic winter stratosphere: simulated with a 3-D chemistry transport model

    NASA Astrophysics Data System (ADS)

    van den Broek, Martina Maria Petronella

    2004-10-01

    During the past two decades, the ozone layer has developed a “hole” each winter and spring above the Antarctic continent. Also in cold Arctic winters substantial stratospheric ozone depletion has been measured, although less than in the Antarctic stratosphere. In the Arctic winter stratosphere, the amount of ozone depletion varies interannually and within one winter, depending on polar vortex stability and temperature. The simulation of transport and chemical conversion of ozone and related species requires a three-dimensional (3D) chemistry transport model (CTM), because of the non-symmetric behaviour of the Arctic polar vortex. This thesis reports on several studies of the Arctic winter stratosphere carried out with such a CTM, using off-line meteorological fields. In Chapter II, chlorine activation and ozone depletion in the Arctic winter stratosphere of 1996-1997 are modelled with the newly developed stratospheric version of our CTM. Comparisons have been made with total O3 columns and ClO concentrations observed by satellites, and with ozone loss rates derived from observations during February and March 1997. ClO concentrations and ozone depletion are somewhat underestimated by the model. Key model parameters have been varied to explain this underestimation. Next to temperature, the formation mechanism of solid and/or liquid PSC particles constitutes the main model uncertainty. The representation of tracer transport is a third uncertain parameter, influencing both ozone and inorganic chlorine. In Chapter III, we have used the CTM with different horizontal resolutions to evaluate this stratospheric transport by simulating the long-lived tracers HF and CH4 during the Arctic winter of 1999/2000. Outside the vortex the model results agree well with the observations, but inside, the model underestimates the observed vertical gradient in HF and CH4. Too strong mixing through the vortex edge could be a cause for these model discrepancies, e.g. associated with the

  9. Nonlinear Evolution of a 3D Inertial Alfvén Wave and Its Implication in Particle Acceleration

    NASA Astrophysics Data System (ADS)

    Sharma, Prachi; Yadav, Nitin; Sharma, R. P.

    2016-03-01

    A simulation based on a pseudo-spectral method has been performed in order to study particle acceleration. A model for the acceleration of charged particles by field localization is developed for the low-β plasma. For this purpose, a fractional diffusion approach has been employed. The nonlinear interaction between a 3D inertial Alfvén wave and a slow magnetosonic wave has been examined, and the dynamical equations of these two waves in the presence of ponderomotive nonlinearity have been solved numerically. The nonlinear evolution of the inertial Alfvén wave in the presence of slow magnetosonic wave undergoes a filamentation instability and results in field intensity localization. The results obtained show the localization and power spectrum of inertial Alfvén wave due to nonlinear coupling. The scaling obtained after the first break point of the magnetic power spectrum has been used to calculate the formation of the thermal tail of energetic particles in the solar corona.

  10. 3D Numerical Simulation on the Sloshing Waves Excited by the Seismic Shacking

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Wu, Tso-Ren

    2016-04-01

    In the event of 2015 Nepal earthquake, a video clip broadcasted worldwide showed a violent water spilling in a hotel swimming pool. This sloshing phenomenon indicates a potential water loss in the sensitive facilities, e.g. the spent fuel pools in nuclear power plant, has to be taken into account carefully under the consideration of seismic-induced ground acceleration. In the previous studies, the simulation of sloshing mainly focused on the pressure force on the structure by using a simplified Spring-Mass Method developed in the field of solid mechanics. However, restricted by the assumptions of plane water surface and limited wave height, significant error will be made in evaluating the amount of water loss in the tank. In this paper, the computational fluid dynamical model, Splash3D, was adopted for studying the sloshing problem accurately. Splash3D solved 3D Navier-Stokes Equation directly with Large-Eddy Simulation (LES) turbulent closure. The Volume-of-fluid (VOF) method with piecewise linear interface calculation (PLIC) was used to track the complex breaking water surface. The time series acceleration of a design seismic was loaded to excite the water. With few restrictions from the assumptions, the accuracy of the simulation results were improved dramatically. A series model validations were conducted by compared to a 2D theoretical solution, and a 3D experimental data. Good comparisons can be seen. After the validation, we performed the simulation for considering a sloshing case in a rectangular water tank with a dimension of 12 m long, 8 m wide, 8 m deep, which contained water with 7 m in depth. The seismic movement was imported by considering time-series acceleration in three dimensions, which were about 0.5 g to 1.2 g in the horizontal directions, and 0.3 g to 1 g in the vertical direction. We focused the discussions on the kinematics of the water surface, wave breaking, velocity field, pressure field, water force on the side walls, and, most

  11. Understanding fiber mixture by simulation in 3D Polarized Light Imaging.

    PubMed

    Dohmen, Melanie; Menzel, Miriam; Wiese, Hendrik; Reckfort, Julia; Hanke, Frederike; Pietrzyk, Uwe; Zilles, Karl; Amunts, Katrin; Axer, Markus

    2015-05-01

    3D Polarized Light Imaging (3D-PLI) is a neuroimaging technique that has opened up new avenues to study the complex architecture of nerve fibers in postmortem brains. The spatial orientations of the fibers are derived from birefringence measurements of unstained histological brain sections that are interpreted by a voxel-based analysis. This, however, implies that a single fiber orientation vector is obtained for each voxel and reflects the net effect of all comprised fibers. The mixture of various fiber orientations within an individual voxel is a priori not accessible by a standard 3D-PLI measurement. In order to better understand the effects of fiber mixture on the measured 3D-PLI signal and to improve the interpretation of real data, we have developed a simulation method referred to as SimPLI. By means of SimPLI, it is possible to reproduce the entire 3D-PLI analysis starting from synthetic fiber models in user-defined arrangements and ending with measurement-like tissue images. For the simulation, each synthetic fiber is considered as an optical retarder, i.e., multiple fibers within one voxel are described by multiple retarder elements. The investigation of different synthetic crossing fiber arrangements generated with SimPLI demonstrated that the derived fiber orientations are strongly influenced by the relative mixture of crossing fibers. In case of perpendicularly crossing fibers, for example, the derived fiber direction corresponds to the predominant fiber direction. The derived fiber inclination turned out to be not only influenced by myelin density but also systematically overestimated due to signal attenuation. Similar observations were made for synthetic models of optic chiasms of a human and a hooded seal which were opposed to experimental 3D-PLI data sets obtained from the chiasms of both species. Our study showed that SimPLI is a powerful method able to test hypotheses on the underlying fiber structure of brain tissue and, therefore, to improve the

  12. Characterizing the propagation of gravity waves in 3D nonlinear simulations of solar-like stars

    NASA Astrophysics Data System (ADS)

    Alvan, L.; Strugarek, A.; Brun, A. S.; Mathis, S.; Garcia, R. A.

    2015-09-01

    Context. The revolution of helio- and asteroseismology provides access to the detailed properties of stellar interiors by studying the star's oscillation modes. Among them, gravity (g) modes are formed by constructive interferences between progressive internal gravity waves (IGWs), propagating in stellar radiative zones. Our new 3D nonlinear simulations of the interior of a solar-like star allows us to study the excitation, propagation, and dissipation of these waves. Aims: The aim of this article is to clarify our understanding of the behavior of IGWs in a 3D radiative zone and to provide a clear overview of their properties. Methods: We use a method of frequency filtering that reveals the path of individual gravity waves of different frequencies in the radiative zone. Results: We are able to identify the region of propagation of different waves in 2D and 3D, to compare them to the linear raytracing theory and to distinguish between propagative and standing waves (g-modes). We also show that the energy carried by waves is distributed in different planes in the sphere, depending on their azimuthal wave number. Conclusions: We are able to isolate individual IGWs from a complex spectrum and to study their propagation in space and time. In particular, we highlight in this paper the necessity of studying the propagation of waves in 3D spherical geometry, since the distribution of their energy is not equipartitioned in the sphere.

  13. OptogenSIM: a 3D Monte Carlo simulation platform for light delivery design in optogenetics

    PubMed Central

    Liu, Yuming; Jacques, Steven L.; Azimipour, Mehdi; Rogers, Jeremy D.; Pashaie, Ramin; Eliceiri, Kevin W.

    2015-01-01

    Optimizing light delivery for optogenetics is critical in order to accurately stimulate the neurons of interest while reducing nonspecific effects such as tissue heating or photodamage. Light distribution is typically predicted using the assumption of tissue homogeneity, which oversimplifies light transport in heterogeneous brain. Here, we present an open-source 3D simulation platform, OptogenSIM, which eliminates this assumption. This platform integrates a voxel-based 3D Monte Carlo model, generic optical property models of brain tissues, and a well-defined 3D mouse brain tissue atlas. The application of this platform in brain data models demonstrates that brain heterogeneity has moderate to significant impact depending on application conditions. Estimated light density contours can show the region of any specified power density in the 3D brain space and thus can help optimize the light delivery settings, such as the optical fiber position, fiber diameter, fiber numerical aperture, light wavelength and power. OptogenSIM is freely available and can be easily adapted to incorporate additional brain atlases. PMID:26713200

  14. OptogenSIM: a 3D Monte Carlo simulation platform for light delivery design in optogenetics.

    PubMed

    Liu, Yuming; Jacques, Steven L; Azimipour, Mehdi; Rogers, Jeremy D; Pashaie, Ramin; Eliceiri, Kevin W

    2015-12-01

    Optimizing light delivery for optogenetics is critical in order to accurately stimulate the neurons of interest while reducing nonspecific effects such as tissue heating or photodamage. Light distribution is typically predicted using the assumption of tissue homogeneity, which oversimplifies light transport in heterogeneous brain. Here, we present an open-source 3D simulation platform, OptogenSIM, which eliminates this assumption. This platform integrates a voxel-based 3D Monte Carlo model, generic optical property models of brain tissues, and a well-defined 3D mouse brain tissue atlas. The application of this platform in brain data models demonstrates that brain heterogeneity has moderate to significant impact depending on application conditions. Estimated light density contours can show the region of any specified power density in the 3D brain space and thus can help optimize the light delivery settings, such as the optical fiber position, fiber diameter, fiber numerical aperture, light wavelength and power. OptogenSIM is freely available and can be easily adapted to incorporate additional brain atlases. PMID:26713200

  15. Flexible simulation strategy for modeling 3D cultural objects based on multisource remotely sensed imagery

    NASA Astrophysics Data System (ADS)

    Guienko, Guennadi; Levin, Eugene

    2003-01-01

    New ideas and solutions never come alone. Although automated feature extraction is not sufficiently mature to move from the realm of scientific investigation into the category of production technology, a new goal has arisen: 3D simulation of real-world objects, extracted from images. This task, which evolved from feature extraction and is not an easy task itself, becomes even more complex, multi-leveled, and often uncertain and fuzzy when one exploits time-sequenced multi-source remotely sensed visual data. The basic components of the process are familiar image processing tasks: fusion of various types of imagery, automatic recognition of objects, removng those objects from the source images, and replacing them in the images with their realistic simulated "twin" object rendering. This paper discusses how to aggregate the most appropriate approach to each task into one technological process in order to develop a Manipulator for Visual Simulation of 3D objects (ManVIS) that is independent or imagery/format/media. The technology could be made general by combining a number of competent special purpose algorithms under appropriate contextual, geometric, spatial, and temporal constraints derived from a-priori knowledge. This could be achieved by planning the simulation in an Open Structure Simulation Strategy Manager (O3SM) a distinct component of ManVIS building the simulation strategy before beginning actual image manipulation.

  16. Advanced 3D Poisson solvers and particle-in-cell methods for accelerator modeling

    NASA Astrophysics Data System (ADS)

    Serafini, David B.; McCorquodale, Peter; Colella, Phillip

    2005-01-01

    We seek to improve on the conventional FFT-based algorithms for solving the Poisson equation with infinite-domain (open) boundary conditions for large problems in accelerator modeling and related areas. In particular, improvements in both accuracy and performance are possible by combining several technologies: the method of local corrections (MLC); the James algorithm; and adaptive mesh refinement (AMR). The MLC enables the parallelization (by domain decomposition) of problems with large domains and many grid points. This improves on the FFT-based Poisson solvers typically used as it doesn't require the all-to-all communication pattern that parallel 3d FFT algorithms require, which tends to be a performance bottleneck on current (and foreseeable) parallel computers. In initial tests, good scalability up to 1000 processors has been demonstrated for our new MLC solver. An essential component of our approach is a new version of the James algorithm for infinite-domain boundary conditions for the case of three dimensions. By using a simplified version of the fast multipole method in the boundary-to-boundary potential calculation, we improve on the performance of the Hockney algorithm typically used by reducing the number of grid points by a factor of 8, and the CPU costs by a factor of 3. This is particularly important for large problems where computer memory limits are a consideration. The MLC allows for the use of adaptive mesh refinement, which reduces the number of grid points and increases the accuracy in the Poisson solution. This improves on the uniform grid methods typically used in PIC codes, particularly in beam problems where the halo is large. Also, the number of particles per cell can be controlled more closely with adaptivity than with a uniform grid. To use AMR with particles is more complicated than using uniform grids. It affects depositing particles on the non-uniform grid, reassigning particles when the adaptive grid changes and maintaining the load

  17. Radiation Quality Effects on Transcriptome Profiles in 3-d Cultures After Particle Irradiation

    NASA Technical Reports Server (NTRS)

    Patel, Z. S.; Kidane, Y. H.; Huff, J. L.

    2014-01-01

    In this work, we evaluate the differential effects of low- and high-LET radiation on 3-D organotypic cultures in order to investigate radiation quality impacts on gene expression and cellular responses. Reducing uncertainties in current risk models requires new knowledge on the fundamental differences in biological responses (the so-called radiation quality effects) triggered by heavy ion particle radiation versus low-LET radiation associated with Earth-based exposures. We are utilizing novel 3-D organotypic human tissue models that provide a format for study of human cells within a realistic tissue framework, thereby bridging the gap between 2-D monolayer culture and animal models for risk extrapolation to humans. To identify biological pathway signatures unique to heavy ion particle exposure, functional gene set enrichment analysis (GSEA) was used with whole transcriptome profiling. GSEA has been used extensively as a method to garner biological information in a variety of model systems but has not been commonly used to analyze radiation effects. It is a powerful approach for assessing the functional significance of radiation quality-dependent changes from datasets where the changes are subtle but broad, and where single gene based analysis using rankings of fold-change may not reveal important biological information. We identified 45 statistically significant gene sets at 0.05 q-value cutoff, including 14 gene sets common to gamma and titanium irradiation, 19 gene sets specific to gamma irradiation, and 12 titanium-specific gene sets. Common gene sets largely align with DNA damage, cell cycle, early immune response, and inflammatory cytokine pathway activation. The top gene set enriched for the gamma- and titanium-irradiated samples involved KRAS pathway activation and genes activated in TNF-treated cells, respectively. Another difference noted for the high-LET samples was an apparent enrichment in gene sets involved in cycle cycle/mitotic control. It is

  18. Sedimentary basin effects in Seattle, Washington: Ground-motion observations and 3D simulations

    USGS Publications Warehouse

    Frankel, Arthur; Stephenson, William; Carver, David

    2009-01-01

    Seismograms of local earthquakes recorded in Seattle exhibit surface waves in the Seattle basin and basin-edge focusing of S waves. Spectral ratios of Swaves and later arrivals at 1 Hz for stiff-soil sites in the Seattle basin show a dependence on the direction to the earthquake, with earthquakes to the south and southwest producing higher average amplification. Earthquakes to the southwest typically produce larger basin surface waves relative to S waves than earthquakes to the north and northwest, probably because of the velocity contrast across the Seattle fault along the southern margin of the Seattle basin. S to P conversions are observed for some events and are likely converted at the bottom of the Seattle basin. We model five earthquakes, including the M 6.8 Nisqually earthquake, using 3D finite-difference simulations accurate up to 1 Hz. The simulations reproduce the observed dependence of amplification on the direction to the earthquake. The simulations generally match the timing and character of basin surface waves observed for many events. The 3D simulation for the Nisqually earth-quake produces focusing of S waves along the southern margin of the Seattle basin near the area in west Seattle that experienced increased chimney damage from the earthquake, similar to the results of the higher-frequency 2D simulation reported by Stephenson et al. (2006). Waveforms from the 3D simulations show reasonable agreement with the data at low frequencies (0.2-0.4 Hz) for the Nisqually earthquake and an M 4.8 deep earthquake west of Seattle.

  19. Battery Particle Simulation

    SciTech Connect

    2014-09-15

    Two simulations show the differences between a battery being drained at a slower rate, over a full hour, versus a faster rate, only six minutes (a tenth of an hour). In both cases battery particles go from being fully charged (green) to fully drained (red), but there are significant differences in the patterns of discharge based on the rate.

  20. Improving light propagation Monte Carlo simulations with accurate 3D modeling of skin tissue

    SciTech Connect

    Paquit, Vincent C; Price, Jeffery R; Meriaudeau, Fabrice; Tobin Jr, Kenneth William

    2008-01-01

    In this paper, we present a 3D light propagation model to simulate multispectral reflectance images of large skin surface areas. In particular, we aim to simulate more accurately the effects of various physiological properties of the skin in the case of subcutaneous vein imaging compared to existing models. Our method combines a Monte Carlo light propagation model, a realistic three-dimensional model of the skin using parametric surfaces and a vision system for data acquisition. We describe our model in detail, present results from the Monte Carlo modeling and compare our results with those obtained with a well established Monte Carlo model and with real skin reflectance images.

  1. 3D and 4D Simulations of the Dynamics of the Radiation Belts using VERB code

    NASA Astrophysics Data System (ADS)

    Shprits, Yuri; Kellerman, Adam; Drozdov, Alexander; Orlova, Ksenia

    2015-04-01

    Modeling and understanding of ring current and higher energy radiation belts has been a grand challenge since the beginning of the space age. In this study we show long term simulations with a 3D VERB code of modeling the radiation belts with boundary conditions derived from observations around geosynchronous orbit. We also present 4D VERB simulations that include convective transport, radial diffusion, pitch angle scattering and local acceleration. We show that while lower energy radial transport is dominated by the convection and higher energy transport is dominated by the diffusive radial transport. We also show there exists an intermediate range of energies for electrons for which both processes work simultaneously.

  2. Implementation of Headtracking and 3D Stereo with Unity and VRPN for Computer Simulations

    NASA Technical Reports Server (NTRS)

    Noyes, Matthew A.

    2013-01-01

    This paper explores low-cost hardware and software methods to provide depth cues traditionally absent in monocular displays. The use of a VRPN server in conjunction with a Microsoft Kinect and/or Nintendo Wiimote to provide head tracking information to a Unity application, and NVIDIA 3D Vision for retinal disparity support, is discussed. Methods are suggested to implement this technology with NASA's EDGE simulation graphics package, along with potential caveats. Finally, future applications of this technology to astronaut crew training, particularly when combined with an omnidirectional treadmill for virtual locomotion and NASA's ARGOS system for reduced gravity simulation, are discussed.

  3. 3D MHD simulations of planet migration in turbulent stratified disks

    NASA Astrophysics Data System (ADS)

    Uribe, Ana; Klahr, Hubert; Flock, Mario; Henning, Thomas

    2011-11-01

    We performed 3D MHD numerical simulations of planet migration in stratified disks using the Godunov code PLUTO (Mignone et al. 2007). The disk is invaded by turbulence generated by the magnetorotational instability (MRI). We study the migration for planets with different mass to primary mass ratio. The migration of the low-mass planet (q=Mp/Ms=10-5) is dominated by random fluctuations in the torque and there is no defined direction of migration on timescales of 100 orbits. The intermediate-mass planet (q=Mp/Ms=10-4) can experience systematic outwards migration that was sustained for the times we were able to simulate.

  4. Performance of dental students versus prosthodontics residents on a 3D immersive haptic simulator.

    PubMed

    Eve, Elizabeth J; Koo, Samuel; Alshihri, Abdulmonem A; Cormier, Jeremy; Kozhenikov, Maria; Donoff, R Bruce; Karimbux, Nadeem Y

    2014-04-01

    This study evaluated the performance of dental students versus prosthodontics residents on a simulated caries removal exercise using a newly designed, 3D immersive haptic simulator. The intent of this study was to provide an initial assessment of the simulator's construct validity, which in the context of this experiment was defined as its ability to detect a statistically significant performance difference between novice dental students (n=12) and experienced prosthodontics residents (n=14). Both groups received equivalent calibration training on the simulator and repeated the same caries removal exercise three times. Novice and experienced subjects' average performance differed significantly on the caries removal exercise with respect to the percentage of carious lesion removed and volume of surrounding sound tooth structure removed (p<0.05). Experienced subjects removed a greater portion of the carious lesion, but also a greater volume of the surrounding tooth structure. Efficiency, defined as percentage of carious lesion removed over drilling time, improved significantly over the course of the experiment for both novice and experienced subjects (p<0.001). Within the limitations of this study, experienced subjects removed a greater portion of carious lesion on a 3D immersive haptic simulator. These results are a first step in establishing the validity of this device. PMID:24706694

  5. Lattice Boltzmann simulation of dynamics of plunge and pitch of 3D flexible wing

    NASA Astrophysics Data System (ADS)

    Qi, Dewei; Shyy, Wei

    2008-11-01

    The method of lattice Boltzmann (LB) simulation has been used to simulate fluid structures and motion of a flexible insect wing in a 3D space. In the method, a beam has been discretized into a chain of rigid segments. Each segment is connected through ball and socket joints at its ends. One segment may be bent and twisted with its neighboring segment. A constraint force is applied to each joint to ensure the solid structure moving as a whole flexible elastic body.We have demonstrated that the LB method is suitable for modeling of aerodynamics of insects flight at low Reynolds numbers. First, a simulation of plunging and pitching of a rigid wing is performed at Re=75 in a 2D space and the results of lift forces and flow structures are in excellent agreement with the previous results. Second, plunging and pitching of a flexible wing in span-wise direction is simulated at Re=136 in a 3D space. We found that when twisting elasticity is large enough the twisting angle could be controlled at a level of smaller than 0.2 degree. It is shown that as bending and twisting elasticity is large enough, the motion of flexible wing approaches that of a rigid membrane wing. The simulation results show that the optimization of flexibility in span-wise direction will benefit thrust and an intermediate level is favorable. The results are consistent with experimental finding.

  6. 3D Numerical simulation of high current vacuum arc in realistic magnetic fields considering anode evaporation

    NASA Astrophysics Data System (ADS)

    Wang, Lijun; Huang, Xiaolong; Jia, Shenli; Deng, Jie; Qian, Zhonghao; Shi, Zongqian; Schellenkens, H.; Godechot, X.

    2015-06-01

    A time-dependent 3D numerical model considering anode evaporation is developed for the high current vacuum arc (VA) under a realistic spatial magnetic field. The simulation work contains steady state 3D numerical simulation of high current VA considering anode evaporation at nine discrete moments of first half wave of 50 Hz AC current, transient numerical simulation of anode activity, and realistic spatial magnetic field calculation of commercial cup-shaped electrodes. In the simulation, contact opening and arc diffusion processes are also considered. Due to the effect of electrode slots, the simulation results of magnetic field and temperature of anode plate exhibit six leaves shape (SLS). During 6-8 ms, the strong evaporation of anode surface seriously influence the parameter distributions of VA. Ions emitted from anode penetrate into arc column and the axial velocity distribution on the anode side exhibits SLS. The ions emitted from anode surface have the same temperature with anode surface, which cool the arc plasma and lead to a relative low temperature area formed. The seriously evaporation of anode leads to the accumulation of ions near the anode, and then the current density is more uniform.

  7. Simulation of the impact of 3-D porosity distribution in metallic U-10Zr fuels

    NASA Astrophysics Data System (ADS)

    Yun, Di; Yacout, Abdellatif M.; Stan, Marius; Bauer, Theodore H.; Wright, Arthur E.

    2014-05-01

    Evolution of porosity generated in metallic U-Zr fuel irradiated in fast spectrum reactors leads to changes in fuel properties and impacts important phenomena such as heat transport and constituent redistribution. The porosity is generated as a result of the accumulation of fission gases and is affected by the possible bond sodium infiltration into the fuel. Typically, the impact of porosity development on properties, such as thermal conductivity, is accounted for through empirical correlations that are dependent on porosity and infiltrated sodium fractions. Currently available simulation tools make it possible to take into account fuel 3-D porosity distributions, potentially eliminating the need for such correlations. This development allows for a more realistic representation of the porosity evolution in metallic fuel and creates a framework for truly mechanistic fuel development models. In this work, COMSOL multi-physics simulation platform is used to model 3-D porosity distributions and simulate heat transport in metallic U-10Zr fuel. Available experimental data regarding microstructural evolution of fuel that was irradiated in EBR-II and associated phase stability information are used to guide the simulation. The impact of changes in porosity characteristics on material properties is estimated and the results are compared with calculated temperature distributions. The simulations demonstrate the developed capability and importance of accounting for detailed porosity distribution features for accurate fuel performance evaluation.

  8. Simulations of Aperture Synthesis Imaging Radar for the EISCAT_3D Project

    NASA Astrophysics Data System (ADS)

    La Hoz, C.; Belyey, V.

    2012-12-01

    EISCAT_3D is a project to build the next generation of incoherent scatter radars endowed with multiple 3-dimensional capabilities that will replace the current EISCAT radars in Northern Scandinavia. Aperture Synthesis Imaging Radar (ASIR) is one of the technologies adopted by the EISCAT_3D project to endow it with imaging capabilities in 3-dimensions that includes sub-beam resolution. Complemented by pulse compression, it will provide 3-dimensional images of certain types of incoherent scatter radar targets resolved to about 100 metres at 100 km range, depending on the signal-to-noise ratio. This ability will open new research opportunities to map small structures associated with non-homogeneous, unstable processes such as aurora, summer and winter polar radar echoes (PMSE and PMWE), Natural Enhanced Ion Acoustic Lines (NEIALs), structures excited by HF ionospheric heating, meteors, space debris, and others. To demonstrate the feasibility of the antenna configurations and the imaging inversion algorithms a simulation of synthetic incoherent scattering data has been performed. The simulation algorithm incorporates the ability to control the background plasma parameters with non-homogeneous, non-stationary components over an extended 3-dimensional space. Control over the positions of a number of separated receiving antennas, their signal-to-noise-ratios and arriving phases allows realistic simulation of a multi-baseline interferometric imaging radar system. The resulting simulated data is fed into various inversion algorithms. This simulation package is a powerful tool to evaluate various antenna configurations and inversion algorithms. Results applied to realistic design alternatives of EISCAT_3D will be described.

  9. Interactive 3D Visualization of Humboldt Bay Bridge Earthquake Simulation With High Definition Stereo Output

    NASA Astrophysics Data System (ADS)

    Ang, P. B.; Nayak, A.; Yan, J.; Elgamal, A.

    2006-12-01

    This visualization project involves the study of the Humboldt Bay Middle Channel Bridge, a Pacific Earthquake Engineering Research (PEER) testbed site, subjected to an earthquake simulated by the Department of Structural Engineering, UCSD. The numerical simulation and data generation was carried out using the OpenSees finite element analysis platform, and GiD was employed for the mesh generation in preprocessing. In collaboration with the Scripps Visualization Center, the data was transformed into a virtual 3D world that a viewer could rotate around, zoom into, pan about, step through each timestep or examine in true stereo. The data consists of the static mesh of the bridge-foundation-ground elements, material indices for each type of element, the displacement amount of each element nodes over time, and the shear stress levels for each ground element over time. The Coin3D C++ Open Inventor API was used to parse the data and to render the bridge system in full 3D at 1130 individual time steps to show how the bridge structure and the surrounding soil elements interact during the full course of an earthquake. The results can be viewed interactively while using the program, saved as images and processed into animated movies, in resolutions as high as High Definition (1920x1080), or in stereo modes such as red-blue anaglyph.

  10. Full Core 3-D Simulation of a Partial MOX LWR Core

    SciTech Connect

    S. Bays; W. Skerjanc; M. Pope

    2009-05-01

    A comparative analysis and comparison of results obtained between 2-D lattice calculations and 3-D full core nodal calculations, in the frame of MOX fuel design, was conducted. This study revealed a set of advantages and disadvantages, with respect to each method, which can be used to guide the level of accuracy desired for future fuel and fuel cycle calculations. For the purpose of isotopic generation for fuel cycle analyses, the approach of using a 2-D lattice code (i.e., fuel assembly in infinite lattice) gave reasonable predictions of uranium and plutonium isotope concentrations at the predicted 3-D core simulation batch average discharge burnup. However, it was found that the 2-D lattice calculation can under-predict the power of pins located along a shared edge between MOX and UO2 by as much as 20%. In this analysis, this error did not occur in the peak pin. However, this was a coincidence and does not rule out the possibility that the peak pin could occur in a lattice position with high calculation uncertainty in future un-optimized studies. Another important consideration in realistic fuel design is the prediction of the peak axial burnup and neutron fluence. The use of 3-D core simulation gave peak burnup conditions, at the pellet level, to be approximately 1.4 times greater than what can be predicted using back-of-the-envelope assumptions of average specific power and irradiation time.

  11. Simulation domain size requirements for elastic response of 3D polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Ozturk, Tugce; Stein, Clayton; Pokharel, Reeju; Hefferan, Christopher; Tucker, Harris; Jha, Sushant; John, Reji; Lebensohn, Ricardo A.; Kenesei, Peter; Suter, Robert M.; Rollett, Anthony D.

    2016-01-01

    A fast Fourier transform (FFT) based spectral algorithm is used to compute the full field mechanical response of polycrystalline microstructures. The field distributions in a specific region are used to determine the sensitivity of the method to the number of surrounding grains through quantification of the divergence of the field values from the largest simulation domain, as successively smaller surrounding volumes are included in the simulation. The analysis considers a mapped 3D structure where the location of interest is taken to be a particular pair of surface grains that enclose a small fatigue crack, and synthetically created statistically representative microstructures to further investigate the effect of anisotropy, loading condition, loading direction, and texture. The synthetic structures are generated via DREAM3D and the measured material is a cyclically loaded, Ni-based, low solvus high refractory (LSHR) superalloy that was characterized via 3D high energy x-ray diffraction microscopy (HEDM). Point-wise comparison of distributions in the grain pairs shows that, in order to obtain a Pearson correlation coefficient larger than 99%, the domain must extend to at least the third nearest neighbor. For an elastic FFT calculation, the stress-strain distributions are not sensitive to the shape of the domain. The main result is that convergence can be specified in terms of the number of grains surrounding a region of interest.

  12. 3D simulation and analytical model of chemical heating during silicon wet etching in microchannels

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2016-02-01

    We investigate chemical heating of a Silicon-on-Glass (SOG) chip during a highly exothermic reaction of silicon etching in potassium hydroxide (KOH) solution in a microchannel of 100-micron width inside a 1x1 cm SOG chip. Two modeling approaches have been developed, implemented and compared. (1) A detailed 3D model is based on unsteady Navier-Stokes equations, heat and mass transfer equations of a laminar flow of viscous incompressible fluid in microchannel, coupled to the heat transfer equation in the solid chip. 3D simulation results predicted temperature distributions for different KOH flow rates and silicon etching areas. Microchannels of a small diameter do not heat the chip due to the insufficient chemical heating of the cold fluid, whereas large-area etching (large channel diameter and/or length) leads to local overheating that may have negative effects on the device performance and durability. (2) A simplified analytical model solves a thermal balance equation describing the heating by chemical reactions inside the microchannel and energy loss by free convection of air around the chip. Analytical results compare well with the 3D simulations of a single straight microchannel, therefore the analytical model is suitable for quick estimation of process parameters. For complex microstructures, this simplified approach may be used as the first approximation.

  13. 3D Simulation of Velocity Profile of Turbulent Flow in Open Channel with Complex Geometry

    NASA Astrophysics Data System (ADS)

    Kamel, Benoumessad; Ilhem, Kriba; Ali, Fourar; Abdelbaki, Djebaili

    Simulation of open channel flow or river flow presents unique challenge to numerical simulators, which is widely used in the applications of computational fluid dynamics. The prediction is extremely difficult because the flow in open channel is usually transient and turbulent, the geometry is irregular and curved, and the free-surface elevation is varying with time. The results from a 3D non-linear k- ɛ turbulence model are presented to investigate the flow structure, the velocity distribution and mass transport process in a meandering compound open channel and a straight open channel. The 3D numerical model for calculating flow is set up in cylinder coordinates in order to calculate the complex boundary channel. The finite volume method is used to disperse the governing equations and the SIMPLE algorithm is applied to acquire the coupling of velocity and pressure. The non-linear k- ɛ turbulent model has good useful value because of taking into account the anisotropy and not increasing the computational time. The main contributions of this study are developing a numerical method that can be applied to predict the flow in river bends with various bend curvatures and different width-depth ratios. This study demonstrates that the 3D non-linear k- ɛ turbulence model can be used for analyzing flow structures, the velocity distribution and pollutant transport in the complex boundary open channel, this model is applicable for real river and wetland problem.

  14. Monitoring an eruption fissure in 3D: video recording, particle image velocimetry and dynamics

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2015-04-01

    The processes during an eruption are very complex. To get a better understanding several parameters are measured. One of the measured parameters is the velocity of particles and patterns, as ash and emitted magma, and of the volcano itself. The resulting velocity field provides insights into the dynamics of a vent. Here we test our algorithm for 3 dimensional velocity fields on videos of the second fissure eruption of Bárdarbunga 2014. There we acquired videos from lava fountains of the main fissure with 2 high speed cameras with small angles between the cameras. Additionally we test the algorithm on videos from the geyser Strokkur, where we had 3 cameras and larger angles between the cameras. The velocity is calculated by a correlation in the Fourier space of contiguous images. Considering that we only have the velocity field of the surface smaller angles result in a better resolution of the existing velocity field in the near field. For general movements also larger angles can be useful, e.g. to get the direction, height and velocity of eruption clouds. In summary, it can be stated that 3D velocimetry can be used for several application and with different setup due to the application.

  15. Multi-Cell Simulations of Development and Disease Using the CompuCell3D Simulation Environment

    PubMed Central

    Swat, Maciej H.; Hester, Susan D.; Heiland, Randy W.; Zaitlen, Benjamin L.; Glazier, James A.

    2009-01-01

    Mathematical modeling and computer simulation have become crucial to biological fields from genomics to ecology. However, multi-cell, tissue-level simulations of development and disease have lagged behind other areas because they are mathematically more complex and lack easy-to-use software tools that allow building and running in-silico experiments without requiring in-depth knowledge of programming. This tutorial introduces Glazier-Graner-Hogeweg (GGH) multi-cell simulations and CompuCell3D, a simulation framework that allows users to build, test and run GGH simulations. PMID:19399437

  16. Comparison between 2D and 3D Numerical Modelling of a hot forging simulative test

    SciTech Connect

    Croin, M.; Ghiotti, A.; Bruschi, S.

    2007-04-07

    The paper presents the comparative analysis between 2D and 3D modelling of a simulative experiment, performed in laboratory environment, in which operating conditions approximate hot forging of a turbine aerofoil section. The plane strain deformation was chosen as an ideal case to analyze the process because of the thickness variations in the final section and the consequent distributions of contact pressure and sliding velocity at the interface that are closed to the conditions of the real industrial process. In order to compare the performances of 2D and 3D approaches, two different analyses were performed and compared with the experiments in terms of loads and temperatures peaks at the interface between the dies and the workpiece.

  17. Application of FUN3D Solver for Aeroacoustics Simulation of a Nose Landing Gear Configuration

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Lockard, David P.; Khorrami, Mehdi R.

    2011-01-01

    Numerical simulations have been performed for a nose landing gear configuration corresponding to the experimental tests conducted in the Basic Aerodynamic Research Tunnel at NASA Langley Research Center. A widely used unstructured grid code, FUN3D, is examined for solving the unsteady flow field associated with this configuration. A series of successively finer unstructured grids has been generated to assess the effect of grid refinement. Solutions have been obtained on purely tetrahedral grids as well as mixed element grids using hybrid RANS/LES turbulence models. The agreement of FUN3D solutions with experimental data on the same size mesh is better on mixed element grids compared to pure tetrahedral grids, and in general improves with grid refinement.

  18. Numerical simulation of internal and external inviscid and viscous 3-D flow fields

    NASA Astrophysics Data System (ADS)

    Leicher, Stefan

    1986-11-01

    A numerical method for solving the 3-D Euler equations in geometrical complex domains was developed. The approach divides the computational space into multiple blocks whose structure follows the natural lines of the conficuration. A systematic, multi-block grid generation scheme is used to produce the grid. The flow solutions are obtained by solving the Euler equations by a finite volume discretization and a Runge-Kutta time stepping scheme. The main advantage of this method is the applicability to complex geometries, for example complete aircraft configurations including wing, fuselage, canard and tail. The coupling with a 3-D boundary layer method allows to account for viscous effects. Another application for the method was the simulation of flows in the presence of a propeller.

  19. 3D Simulations of Solar Observations in Radio, Millimeter and Submillimeter Wavelengths.

    NASA Astrophysics Data System (ADS)

    de La Luz, V. H.; Lara, A.; Mendoza, E.

    2007-05-01

    In this work we present 3D simulations of solar radio emission at different frequencies (1.4, 3.9, 17, 34, 43, 110GHz and 12GHz), in the centimeter - submilimeter wavelength range. We build a 3D, spherically symetric, solar model and solve the clasical equation of radiative transfer using quiet Sun temperature and electron density models. We compare our results with observations from Nobeyama Radio Heliograph and SMT submillimeter telescope at CASILEO. The 3.9 and 43 GHz images will be useful to calibrate the observations of new millimeter telescope (RT5) which is being constructed at "Sierra Negra" Volcano, in the state of Puebla, Mexico, at an altitude of 4,600 m. This project is a collaboration between Universidad Nacional Autonoma de Mexico (UNAM) and Instituto Nacional de Astrofisica Optica y Electronica (INAOE).

  20. Reconstruction of quadratic curves in 3D using two or more perspective views: simulation studies

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Sukavanam, N.; Balasubramanian, R.

    2006-01-01

    The shapes of many natural and man-made objects have planar and curvilinear surfaces. The images of such curves usually do not have sufficient distinctive features to apply conventional feature-based reconstruction algorithms. In this paper, we describe a method of reconstruction of a quadratic curve in 3-D space as an intersection of two cones containing the respective projected curve images. The correspondence between this pair of projections of the curve is assumed to be established in this work. Using least-square curve fitting, the parameters of a curve in 2-D space are found. From this we are reconstructing the 3-D quadratic curve. Relevant mathematical formulations and analytical solutions for obtaining the equation of reconstructed curve are given. The result of the described reconstruction methodology are studied by simulation studies. This reconstruction methodology is applicable to LBW decision in cricket, path of the missile, Robotic Vision, path lanning etc.

  1. Simple tools for simulating phased array focal laws on 3D solids

    NASA Astrophysics Data System (ADS)

    Weber, Walter H.; Mair, H. Douglas; Frazer, Leigh

    2001-04-01

    This paper reports our progress on the development of a three-dimensional raytracing program that can simulate the focal laws of a phased array system. The modeled transducer is divided into elements of a given length, width and inter-element gap distance. Each focal law to be modeled requires a steering angle, focal length and selection of which groups of elements are transmitting and receiving. Electronic scanning is simulated by stepping through a series of predefined focal laws. The program phase shifts and sums the received rays at each element based on the properties of the currently-active focal law. Simulated A-scans are constructed from the received rays which appear animated as the beam is swept. Beam profiles can also be generated that show the primary forward beam and energy in the side lobes. The work is based on Imagine3D ultrasonic simulation software and the dedicated efforts of Doug Mair and Leigh Frazer.

  2. Hybrid Reactor Simulation and 3-D Information Display of BWR Out-of-Phase Oscillation

    SciTech Connect

    Edwards, Robert; Huang, Zhengyu

    2001-06-17

    The real-time hybrid reactor simulation (HRS) capability of the Penn State TRIGA reactor has been expanded for boiling water reactor (BWR) out-of-phase behavior. During BWR out-of-phase oscillation half of the core can significantly oscillate out of phase with the other half, while the average power reported by the neutronic instrumentation may show a much lower amplitude for the oscillations. A description of the new HRS is given; three computers are employed to handle all the computations required, including real-time data processing and graph generation. BWR out-of-phase oscillation was successfully simulated. By adjusting the reactivity feedback gains from boiling channels to the TRIGA reactor and to the first harmonic mode power simulation, limit cycle can be generated with both reactor power and the simulated first harmonic power. A 3-D display of spatial power distributions of fundamental mode, first harmonic, and total powers over the reactor cross section is shown.

  3. Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.

    PubMed

    Idkaidek, Ashraf; Jasiuk, Iwona

    2015-12-01

    We aim to achieve a fast and accurate three-dimensional (3D) simulation of a porcine liver deformation under a surgical tool pressure using the commercial finite element software Abaqus. The liver geometry is obtained using magnetic resonance imaging, and a nonlinear constitutive law is employed to capture large deformations of the tissue. Effects of implicit versus explicit analysis schemes, element type, and mesh density on computation time are studied. We find that Abaqus explicit and implicit solvers are capable of simulating nonlinear soft tissue deformations accurately using first-order tetrahedral elements in a relatively short time by optimizing the element size. This study provides new insights and guidance on accurate and relatively fast nonlinear soft tissue simulations. Such simulations can provide force feedback during robotic surgery and allow visualization of tissue deformations for surgery planning and training of surgical residents. PMID:26530842

  4. Probabilistic Seismic Hazard Maps for Seattle, Washington, Based on 3D Ground-Motion Simulations

    NASA Astrophysics Data System (ADS)

    Frankel, A. D.; Stephenson, W. J.; Carver, D. L.; Williams, R. A.; Odum, J. K.; Rhea, S.

    2007-12-01

    We have produced probabilistic seismic hazard maps for Seattle using over 500 3D finite-difference simulations of ground motions from earthquakes in the Seattle fault zone, Cascadia subduction zone, South Whidbey Island fault, and background shallow and deep source areas. The maps depict 1 Hz response spectral accelerations with 2, 5, and 10% probabilities of being exceeded in 50 years. The simulations were used to generate site and source dependent amplification factors that are applied to rock-site attenuation relations. The maps incorporate essentially the same fault sources and earthquake recurrence times as the 2002 national seismic hazard maps. The simulations included basin surface waves and basin-edge focusing effects from a 3D model of the Seattle basin. The 3D velocity model was validated by modeling several earthquakes in the region, including the 2001 M6.8 Nisqually earthquake, that were recorded by our Seattle Urban Seismic Network and the Pacific Northwest Seismic Network. The simulations duplicate our observation that earthquakes from the south and southwest typically produce larger amplifications in the Seattle basin than earthquakes from other azimuths, relative to rock sites outside the basin. Finite-fault simulations were run for earthquakes along the Seattle fault zone, with magnitudes ranging from 6.6 to 7.2, so that the effects of rupture directivity were included. Nonlinear amplification factors for soft-soil sites of fill and alluvium were also applied in the maps. For the Cascadia subduction zone, 3D simulations with point sources at different locations along the zone were used to determine amplification factors across Seattle expected for great subduction-zone earthquakes. These new urban seismic hazard maps are based on determinations of hazard for 7236 sites with a spacing of 280 m. The maps show that the highest hazard locations for this frequency band (around 1 Hz) are soft-soil sites (fill and alluvium) within the Seattle basin and

  5. Surface processes on the asteroid deduced from the external 3D shapes and surface features of Itokawa particles

    NASA Astrophysics Data System (ADS)

    Tsuchiyama, A.; Matsumoto, T.

    2015-10-01

    Particles on the surface of S-type Asteroid 25143 Itokawa were successfully recovered by the Hayabusa mission of JAXA (e.g., [1,2]). They are not only the first samples recovered from an asteroid, but also the second extraterrestrial regolith to have been sampled, the first being the Moon by Apollo and Luna missions. The analysis of tiny sample particles (20-200 μm) shows that the Itokawa surface material is consistent with LL chondrites suffered by space weathering as expected and brought an end to the origin of meteorites (e.g., [2-4]). In addition, the examination of Itokawa particles allow studies of surface processes on the asteroid because regolith particles can be regarded as an interface with the space environment, where the impacts of small objects and irradiation by the solar wind and galactic cosmic rays should have been recorded. External 3D shapes and surface features of Itokawa regolith particles were examined. Two kinds of surface modification, formation of space-weathering rims mainly by solar wind implantation and surface abrasion by grain migration, were recognized. Spectral change of the asteroid proceeded by formation of space-weathering rims and refreshment of the regolith surfaces. External 3D shapes and surface morphologies of the regolith particles can provide information about formation and evolution history of regolith particles in relation to asteroidal surface processes. 3D shapes of Itokawa regolith particles were obtained using microtomography [3]. The surface nanomiromorpholgy of Itokawa particles were also observed using FE-SEM [5]. However, the number of particles was limited and genial feature on the surface morphology has not been understood. In this study, the surface morphology of Itokawa regolith particles was systematically investigated together with their 3D structures.

  6. 3D Global Magnetohydrodynamic Simulations of the Solar Wind/Earth's Magnetosphere Interaction

    NASA Astrophysics Data System (ADS)

    Yalim, M. S.; Poedts, S.

    2014-09-01

    In this paper, we present results of real-time 3D global magnetohydrodynamic (MHD) simulations of the solar wind interaction with the Earth's magnetosphere using time-varying data from the NASA Advanced Composition Explorer (ACE) satellite during a few big magnetic storm events of the previous and current solar cycles, namely the 06 April 2000, 20 November 2003 and 05 April 2010 storms. We introduce a numerical magnetic storm index and compare the geo-effectiveness of these events in terms of this storm index which is a measure for the resulting global perturbation of the Earth's magnetic field. Steady simulations show that the upstream solar wind plasma parameters enter the low-β switch-on regime for some time intervals during a magnetic storm causing a complex dimpled bow shock structure. We also investigate the traces of such bow shock structures during time-dependent simulations of the events. We utilize a 3D, implicit, parallel, unstructured grid, compressible finite volume ideal MHD solver with an anisotropic grid adaptation technique for the computer simulations.

  7. Multiple-mode Lamb wave scattering simulations using 3D elastodynamic finite integration technique.

    PubMed

    Leckey, Cara A C; Rogge, Matthew D; Miller, Corey A; Hinders, Mark K

    2012-02-01

    We have implemented three-dimensional (3D) elastodynamic finite integration technique (EFIT) simulations to model Lamb wave scattering for two flaw-types in an aircraft-grade aluminum plate, a rounded rectangle flat-bottom hole and a disbond of the same shape. The plate thickness and flaws explored in this work include frequency-thickness regions where several Lamb wave modes exist and sometimes overlap in phase and/or group velocity. For the case of the flat-bottom hole the depth was incrementally increased to explore progressive changes in multiple-mode Lamb wave scattering due to the damage. The flat-bottom hole simulation results have been compared to experimental data and are shown to provide key insight for this well-defined experimental case by explaining unexpected results in experimental waveforms. For the rounded rectangle disbond flaw, which would be difficult to implement experimentally, we found that Lamb wave behavior differed significantly from the flat-bottom hole flaw. Most of the literature in this field is restricted to low frequency-thickness regions due to difficulties in interpreting data when multiple modes exist. We found that benchmarked 3D EFIT simulations can yield an understanding of scattering behavior for these higher frequency-thickness regions and in cases that would be difficult to set up experimentally. Additionally, our results show that 2D simulations would not have been sufficient for modeling the complicated scattering that occurred. PMID:21908011

  8. A 3D parallel simulator for crystal growth and solidification in complex alloy systems

    NASA Astrophysics Data System (ADS)

    Nestler, Britta

    2005-02-01

    A 3D parallel simulator is developed to numerically solve the evolution equations of a new non-isothermal phase-field model for crystal growth and solidification in complex alloy systems. The new model and the simulator are capable to simultaneously describe the diffusion processes of multiple components, the phase transitions between multiple phases and the development of the temperature field. Weak and facetted formulations of both, surface energy and kinetic anisotropies are incorporated in the phase-field model. Multicomponent bulk diffusion effects including interdiffusion coefficients as well as diffusion in the interfacial region of phase or grain boundaries are considered. We introduce our parallel simulator that is based on a finite difference discretization including effective adaptive strategies and multigrid methods to reduce computation time and memory usage. The parallelization is realized for distributed as well as shared memory computer architectures using MPI libraries and OpenMP concepts. Applying the new computer model, we present a variety of simulated crystal structures such as dendrites, grains, binary and ternary eutectics in 2D and 3D. The influence of anisotropy on the microstructure evolution shows the formation of facets in preferred crystallographic directions. Phase transformations and solidification processes in a real multi-component alloy can be described by incorporating the physical data (e.g. surface tensions, kinetic coefficients, specific heat, heat and mass diffusion coefficients) and the specific phase diagram (in particular latent heats and melting temperatures) into the diffuse interface model via the free energies.

  9. XEDS STEM Tomography For 3D Chemical Characterization Of Nanoscale Particles

    SciTech Connect

    Genc, Arda; Kovarik, Libor; Gu, Meng; Cheng, Huikai; Plachinda, Pavel; Pullan, Lee; Freitag, Bert; Wang, Chong M.

    2013-08-01

    We present a tomography technique which couples scanning transmission electron microscopy (STEM) and X-ray energy dispersive spectrometry (XEDS) to resolve 3D distribution of elements in nanoscale materials. STEM imaging when combined with a symmetrically arranged XEDS detector design around the specimen overcomes many of the obstacles in 3D spectroscopic tomography of nanoscale materials and successfully elucidate the 3D chemical information in a large field of view of the TEM sample. We employed this technique to investigate 3D distribution of Nickel (Ni), Manganese (Mn) and Oxygen (O) in Li(NiMn)O2 battery cathode material. For this purpose, 2D elemental maps were acquired for a range of tilt angles and reconstructed to obtain 3D elemental distribution in an isolated Li(NiMnO2) nanoparticle. The results highlight the strength of this technique in 3D chemical analysis of nanoscale materials by successfully resolving Ni, Mn and O elemental distributions in 3D and discovering the new phenomenon of Ni surface segregation in this material. Furthermore, the comparison of simultaneously acquired HAADF STEM and XEDS STEM tomography results show that XEDS STEM tomography provides additional 3D chemical information of the material especially when there is low atomic number (Z) contrast in the material of interest.

  10. Unsteady Analysis of Particle Transport and Deposition in the Human Lung: A Hybrid 3D/0D Model

    NASA Astrophysics Data System (ADS)

    Haworth, Daniel C.; Kunz, Robert F.; Leemhuis, Laura S.; Banks, Syreeta S.; Kriete, Andres

    2003-11-01

    Three-dimensional CFD meshes including up the sixteenth generation of branching in a human tracheo-bronchial tree have been generated from surface data extracted using novel high-resolution bio-medical imaging and rendering methods. A zero-dimensional model for the deeper generations has been coupled with the three-dimensional model at each of the truncated branches. The 0D model imposes a time-varying volume to simulate realistic breathing cycles; it also includes a simple model for particle deposition. The resulting hybrid 3D/0D model has been exercised to compute the transport and deposition rates of particles of different sizes through full breathing cycles. Results are compared to earlier steady-flow CFD results, to results obtained using one-dimensional functional models of the human lung, and to experimental and modeling results for idealized branching-duct configurations. The aim of the research is to develop a virtual human respiratory system that can be used to address issues in pulmonary health in

  11. 3D hydrodynamic simulations of the Galactic supernova remnant CTB 109

    NASA Astrophysics Data System (ADS)

    Bolte, J.; Sasaki, M.; Breitschwerdt, D.

    2015-10-01

    Context. Using detailed 3D hydrodynamic simulations we study the nature of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0), which is well known for its semicircular shape and a bright diffuse X-ray emission feature inside the SNR. Aims: Our model has been designed to explain the observed morphology, with a special emphasis on the bright emission feature inside the SNR. Moreover, we determine the age of the remnant and compare our findings with X-ray observations. With CTB 109 we test a new method of detailed numerical simulations of diffuse young objects, using realistic initial conditions derived directly from observations. Methods: We performed numerical 3D simulations with the RAMSES code. The initial density structure has been directly taken from 12CO emission data, adding an additional dense cloud, which, when it is shocked, causes the bright emission feature. Results: From parameter studies we obtained the position (ℓ,b) = (109.1545°,-1.0078°) for an elliptical cloud with ncloud = 25 cm-3 based on the preshock density from Chandra data and a maximum diameter of 4.54 pc, whose encounter with the supernova (SN) shock wave generates the bright X-ray emission inside the SNR. The calculated age of the remnant is about 11 000 yr according to our simulations. In addition, we can also determine the most probable site of the SN explosion. Conclusions: Hydrodynamic simulations can reproduce the morphology and the observed size of the SNR CTB 109 remarkably well. Moreover, the simulations show that it is very plausible that the bright X-ray emission inside the SNR is the result of an elliptical dense cloud shocked by the SN explosion wave. We show that numerical simulations using observational data for an initial model can produce meaningful results.

  12. Simulation of a complete triple turbo molecular pumping stage using direct simulation Monte Carlo in 3D

    NASA Astrophysics Data System (ADS)

    Rose, Martin

    2014-12-01

    A triple stage turbo molecular pump is simulated using the DSMC method in 3D. A 90° sector of the complete pump is simulated taking the symmetry of the pump into account. Simulations were performed for various fore line pressures in order to determine the compression ratio and the maximum pumping speed. Various features of the three dimensional flow field are discussed. Also the CPU time required to obtain the flow field is discussed. The simulations presented here are a powerful tool for the design and improvement of turbo molecular pumps.

  13. Nanoelectronic Modeling (NEMO): Moving from commercial grade 1-D simulation to prototype 3-D simulation

    NASA Astrophysics Data System (ADS)

    Klimeck, Gerhard

    2001-03-01

    The quantum mechanical functionality of commercially pursued heterostructure devices such as resonant tunneling diodes (RTDs), quantum well infrared photodetectors, and quantum well lasers are enabled by material variations on an atomic scale. The creation of these heterostructure devices is realized in a vast design space of material compositions, layer thicknesses and doping profiles. The full experimental exploration of this design space is unfeasible and a reliable design tool is needed. The Nanoelectronic Modeling tool (NEMO) is one of the first commercial grade attempts for such a modeling tool. NEMO was developed as a general-purpose quantum mechanics-based 1-D device design and analysis tool from 1993-97 by the Central Research Laboratory of Texas Instruments (later Raytheon Systems). NEMO enables(R. Lake, G. Klimeck, R. C. Bowen, and D. Jovanovic, J. Appl. Phys. 81), 7845 (1997). the fundamentally sound inclusion of the required(G. Klimeck et al.), in the 1997 55th Annual Device Research Conference Digest, (IEEE, NJ, 1997), p. 92^,(R. C. Bowen et al.), J. Appl. Phys 81, 3207 (1997). physics: bandstructure, scattering, and charge self-consistency based on the non-equilibrium Green function approach. A new class of devices which require full 3-D quantum mechanics based models is starting to emerge: quantum dots, or in general semiconductor based deca-nano devices. We are currently building a 3-D modeling tool based on NEMO to include the important physics to understand electronic stated in such superscaled structures. This presentation will overview various facets of the NEMO 1-D tool such electron transport physics in RTDs, numerical technology, software engineering and graphical user interface. The lessons learned from that work are now entering the 3D>NEMO 3-D development and first results using the NEMO 3-D prototype will be shown. More information about

  14. 3-D imaging and quantitative comparison of human dentitions and simulated bite marks.

    PubMed

    Blackwell, S A; Taylor, R V; Gordon, I; Ogleby, C L; Tanijiri, T; Yoshino, M; Donald, M R; Clement, J G

    2007-01-01

    This study presents a technique developed for 3-D imaging and quantitative comparison of human dentitions and simulated bite marks. A sample of 42 study models and the corresponding bites, made by the same subjects in acrylic dental wax, were digitised by laser scanning. This technique allows image comparison of a 3-D dentition with a 3-D bite mark, eliminating distortion due to perspective as experienced in conventional photography. Cartesian co-ordinates of a series of landmarks were used to describe the dentitions and bite marks, and a matrix was created to compare all possible combinations of matches and non-matches using cross-validation techniques. An algorithm, which estimated the probability of a dentition matching its corresponding bite mark, was developed. A receiver operating characteristic graph illustrated the relationship between values for specificity and sensitivity. This graph also showed for this sample that 15% of non-matches could not be distinguished from the true match, translating to a 15% probability of falsely convicting an innocent person. PMID:16391946

  15. SVD-GFD scheme to simulate complex moving body problems in 3D space

    NASA Astrophysics Data System (ADS)

    Wang, X. Y.; Yu, P.; Yeo, K. S.; Khoo, B. C.

    2010-03-01

    The present paper presents a hybrid meshfree-and-Cartesian grid method for simulating moving body incompressible viscous flow problems in 3D space. The method combines the merits of cost-efficient and accurate conventional finite difference approximations on Cartesian grids with the geometric freedom of generalized finite difference (GFD) approximations on meshfree grids. Error minimization in GFD is carried out by singular value decomposition (SVD). The Arbitrary Lagrangian-Eulerian (ALE) form of the Navier-Stokes equations on convecting nodes is integrated by a fractional-step projection method. The present hybrid grid method employs a relatively simple mode of nodal administration. Nevertheless, it has the geometrical flexibility of unstructured mesh-based finite-volume and finite element methods. Boundary conditions are precisely implemented on boundary nodes without interpolation. The present scheme is validated by a moving patch consistency test as well as against published results for 3D moving body problems. Finally, the method is applied on low-Reynolds number flapping wing applications, where large boundary motions are involved. The present study demonstrates the potential of the present hybrid meshfree-and-Cartesian grid scheme for solving complex moving body problems in 3D.

  16. RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations.

    PubMed

    Pasipoularides, Ares D; Shu, Ming; Womack, Michael S; Shah, Ashish; Von Ramm, Olaf; Glower, Donald D

    2003-01-01

    We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent of the digital imaging modality used. It comprises three parts. First, a semiautomated segmentation aided by intraluminal contrast medium locates the RV endocardial surface. Second, a geometric scheme for dynamic RV chamber reconstruction applies a time interpolation procedure to the RT3D data to quantify wall geometry and motion at 400 Hz. A volumetric prism method validated the dynamic geometric reconstruction against simultaneous sonomicrometric canine measurements. Finally, the RV endocardial border motion information is used for mesh generation on a computational fluid dynamics solver to simulate development of the early RV diastolic inflow field. Boundary conditions (tessellated endocardial surface nodal velocities) for the solver are directly derived from the endocardial geometry and motion information. The new functional imaging approach may yield important kinematic information on the distribution of instantaneous velocities in the RV diastolic flow field of specific normal or diseased hearts. PMID:12388220

  17. ShrinkWrap: 3D model abstraction for remote sensing simulation

    SciTech Connect

    Pope, Paul A

    2009-01-01

    Remote sensing simulations often require the use of 3D models of objects of interest. There are a multitude of these models available from various commercial sources. There are image processing, computational, database storage, and . data access advantages to having a regularized, encapsulating, triangular mesh representing the surface of a 3D object model. However, this is usually not how these models are stored. They can have too much detail in some areas, and not enough detail in others. They can have a mix of planar geometric primitives (triangles, quadrilaterals, n-sided polygons) representing not only the surface of the model, but also interior features. And the exterior mesh is usually not regularized nor encapsulating. This paper presents a method called SHRlNKWRAP which can be used to process 3D object models to achieve output models having the aforementioned desirable traits. The method works by collapsing an encapsulating sphere, which has a regularized triangular mesh on its surface, onto the surface of the model. A GUI has been developed to make it easy to leverage this capability. The SHRlNKWRAP processing chain and use of the GUI are described and illustrated.

  18. 2-D/3-D ECE imaging data for validation of turbulence simulations

    NASA Astrophysics Data System (ADS)

    Choi, Minjun; Lee, Jaehyun; Yun, Gunsu; Lee, Woochang; Park, Hyeon K.; Park, Young-Seok; Sabbagh, Steve A.; Wang, Weixing; Luhmann, Neville C., Jr.

    2015-11-01

    The 2-D/3-D KSTAR ECEI diagnostic can provide a local 2-D/3-D measurement of ECE intensity. Application of spectral analysis techniques to the ECEI data allows local estimation of frequency spectra S (f) , wavenumber spectra S (k) , wavernumber and frequency spectra S (k , f) , and bispectra b (f1 ,f2) of ECE intensity over the 2-D/3-D space, which can be used to validate turbulence simulations. However, the minimum detectable fluctuation amplitude and the maximum detectable wavenumber are limited by the temporal and spatial resolutions of the diagnostic system, respectively. Also, the finite measurement area of the diagnostic channel could introduce uncertainty in the spectra estimation. The limitations and accuracy of the ECEI estimated spectra have been tested by a synthetic ECEI diagnostic with the model and/or fluctuations calculated by GTS. Supported by the NRF of Korea under Contract No. NRF-2014M1A7A1A03029881 and NRF-2014M1A7A1A03029865 and by U.S. DOE grant DE-FG02-99ER54524.

  19. Radiation in Particle Simulations

    SciTech Connect

    More, R; Graziani, F; Glosli, J; Surh, M

    2010-11-19

    Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of megabars to thousands of gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known. The second method expands the electromagnetic field in normal modes (planewaves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion. The third method is a hybrid molecular dynamics/Monte Carlo (MD/MC) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions. The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc. This approach is inspired by the virial expansion method of equilibrium statistical mechanics. Using a combination of these methods we believe it is possible to do atomic-scale particle simulations of

  20. Toward realistic radiofrequency ablation of hepatic tumors 3D simulation and planning

    NASA Astrophysics Data System (ADS)

    Villard, Caroline; Soler, Luc; Gangi, Afshin; Mutter, Didier; Marescaux, Jacques

    2004-05-01

    Radiofrequency ablation (RFA) has become an increasingly used technique in the treatment of patients with unresectable hepatic tumors. Evaluation of vascular architecture, post-RFA tissue necrosis prediction, and the choice of a suitable needle placement strategy using conventional radiological techniques remain difficult. In an attempt to enhance the safety of RFA, a 3D simulator and treatment planning tool, that simulates the necrosis of the treated area, and proposes an optimal placement for the needle, has been developed. From enhanced spiral CT scans with 2 mm cuts, 3D reconstructions of patients with liver metastases are automatically generated. Virtual needles can be added to the 3D scene, together with their corresponding zones of necrosis that are displayed as a meshed spheroids representing the 60° C isosurface. The simulator takes into account the cooling effect of local vessels greater than 3mm in diameter, making necrosis shapes more realistic. Using a voxel-based algorithm, RFA spheroids are deformed following the shape of the vessels, extended by an additional cooled area. This operation is performed in real-time, allowing updates while needle is adjusted. This allows to observe whether the considered needle placement strategy would burn the whole cancerous zone or not. Planned needle positioning can also be automatically generated by the software to produce complete destruction of the tumor with a 1 cm margin, with maximum respect of the healthy liver and of all major extrahepatic and intrahepatic structures to avoid. If he wishes, the radiologist can select on the skin an insertion window for the needle, focusing the research of the trajectory.

  1. Balloon Ascent: 3-D Simulation Tool for the Ascent and Float of High-Altitude Balloons

    NASA Technical Reports Server (NTRS)

    Farley, Rodger E.

    2005-01-01

    The BalloonAscent balloon flight simulation code represents a from-scratch development using Visual Basic 5 as the software platform. The simulation code is a transient analysis of balloon flight, predicting the skin and gas temperatures along with the 3-D position and velocity in a time and spatially varying environment. There are manual and automated controls for gas valving and the dropping of ballast. Also, there are many handy calculators, such as appropriate free lift, and steady-state thermal solutions with temperature gradients. The strength of this simulation model over others in the past is that the infrared environment is deterministic rather than guessed at. The ground temperature is specified along with the emissivity, which creates a ground level IR environment that is then partially absorbed as it travels upward through the atmosphere to the altitude of the balloon.

  2. Jupiter Magnetotail Interaction with a Variable Solar Wind: A 3D MHD Simulation

    NASA Astrophysics Data System (ADS)

    Ranquist, D. A.; Bagenal, F.; Delamere, P. A.; Ma, X.

    2015-12-01

    Jupiter's magnetosphere is the largest object within the heliosphere. Voyager 2 detected its influence at Saturn's orbit, 4.3 AU away. It takes considerable time, therefore, for the solar wind to propagate such lengths down the tail. This propagation time is much greater than typical periods between changes in direction of the interplanetary magnetic field (IMF). We expect these variable magnetic fields to create a jumbled structure in Jupiter's magnetotail, resulting in magnetic reconnection and other magnetic processes. We simulate the global interaction of the solar wind with Jupiter's magnetosphere using a 3D magnetohydrodynamics (MHD) code. Delamere & Bagenal (2010) argue that the interaction is largely viscous, so we simulate the jovian magnetosphere as a region where the momentum equation has an added loss term. We also use in situ data gathered by the Ulysses spacecraft near Jupiter's orbit for solar wind input. Here, we report on the simulated dynamics in Jupiter's tail region.

  3. 3D printing of tissue-simulating phantoms as a traceable standard for biomedical optical measurement

    NASA Astrophysics Data System (ADS)

    Dong, Erbao; Wang, Minjie; Shen, Shuwei; Han, Yilin; Wu, Qiang; Xu, Ronald

    2016-01-01

    Optical phantoms are commonly used to validate and calibrate biomedical optical devices in order to ensure accurate measurement of optical properties in biological tissue. However, commonly used optical phantoms are based on homogenous materials that reflect neither optical properties nor multi-layer heterogeneities of biological tissue. Using these phantoms for optical calibration may result in significant bias in biological measurement. We propose to characterize and fabricate tissue simulating phantoms that simulate not only the multi-layer heterogeneities but also optical properties of biological tissue. The tissue characterization module detects tissue structural and functional properties in vivo. The phantom printing module generates 3D tissue structures at different scales by layer-by-layer deposition of phantom materials with different optical properties. The ultimate goal is to fabricate multi-layer tissue simulating phantoms as a traceable standard for optimal calibration of biomedical optical spectral devices.

  4. Fully 3D Multiple Beam Dynamics Processes Simulation for the Fermilab Tevatron

    SciTech Connect

    Stern, E.; Amundson, J.; Spentzouris, P; Valishev, A.; /Fermilab

    2010-06-01

    The Fermilab Tevatron has been, until 2010, the premier high-energy physics collider in the world. The data collected over the last decade by high-energy physics experiments running at the Tevatron have been analyzed to make important measurements in fundamental areas such as B meson masses and flavor oscillation, searches for the Higgs boson, and supersymmetry. Collecting these data at the limits of detectability has required the Tevatron to operate reliably at high beam intensities to maximize the number of collisions to analyze. This impressive achievement has been assisted by the use of HPC resources and software provided through the SciDAC program. This paper describes the enhancements to the BeamBeam3d code to realistically simulate the Tevatron, the validation of these simulations, and the improvement in equipment reliability and personal safety achieved with the aid of simulations.

  5. Effect of Single-Electron Interface Trapping in Decanano MOSFETs: A 3D Atomistic Simulation Study

    NASA Technical Reports Server (NTRS)

    Asenov, Asen; Balasubramaniam, R.; Brown, A. R.; Davies, J. H.

    2000-01-01

    We study the effect of trapping/detrapping of a single-electron in interface states in the channel of n-type MOSFETs with decanano dimensions using 3D atomistic simulation techniques. In order to highlight the basic dependencies, the simulations are carried out initially assuming continuous doping charge, and discrete localized charge only for the trapped electron. The dependence of the random telegraph signal (RTS) amplitudes on the device dimensions and on the position of the trapped charge in the channel are studied in detail. Later, in full-scale, atomistic simulations assuming discrete charge for both randomly placed dopants and the trapped electron, we highlight the importance of current percolation and of traps with strategic position where the trapped electron blocks a dominant current path.

  6. 3D MHD Simulations of accreting neutron stars: evidence of QPO emission from the surface

    SciTech Connect

    Bachetti, Matteo; Burderi, Luciano; Romanova, Marina M.; Kulkarni, Akshay; Salvo, Tiziana di

    2010-07-15

    3D Magnetohydrodynamic simulations show that when matter accretes onto neutron stars, in particular if the misalignment angle is small, it does not constantly fall at a fixed spot. Instead, the location at which matter reaches the star moves. These moving hot spots can be produced both during stable accretion, where matter falls near the magnetic poles of the star, and unstable accretion, characterized by the presence of several tongues of matter which fall on the star near the equator, due to Rayleigh-Taylor instabilities. Precise modeling with Monte Carlo simulations shows that those movements could be observed as high frequency Quasi Periodic Oscillations. We performed a number of new simulation runs with a much wider set of parameters, focusing on neutron stars with a small misalignment angle. In most cases we observe oscillations whose frequency is correlated with the mass accretion rate M. Moreover, in some cases double QPOs appear, each of them showing the same correlation with M.

  7. 3D numerical simulation of the evolutionary process of aeolian downsized crescent-shaped dunes

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaosi; Zhang, Yang; Wang, Yuan; Li, Min

    2016-06-01

    A dune constitutive model was coupled with a large eddy simulation (LES) with the Smagorinsky subgrid-scale (SGS) model to accurately describe the evolutionary process of dunes from the macroscopic perspective of morphological dynamics. A 3D numerical simulation of the evolution of aeolian downsized crescent-shaped dunes was then performed. The evolution of the 3D structure of Gaussian-shaped dunes was simulated under the influence of gravity modulation, which was the same with the vertical oscillation of the sand bed to adjust the threshold of sand grain liftoff in wind tunnel experiments under the same wind speed. The influence of gravity modulation intensity on the characteristic scale parameter of the dune was discussed. Results indicated that the crescent shape of the dune was reproduced with the action of gravity during regulation of the saturation of wind-sand flow at specific times. The crescent shape was not dynamically maintained as time passed, and the dunes dwindled until they reached final decomposition because of wind erosion. The height of the dunes decreased over time, and the height-time curve converged as the intensity of modulation increased linearly. The results qualitatively agreed with those obtained from wind tunnel experiments.

  8. 3D thermo-chemical-mechanical simulation of power ramps with ALCYONE fuel code

    NASA Astrophysics Data System (ADS)

    Baurens, B.; Sercombe, J.; Riglet-Martial, C.; Desgranges, L.; Trotignon, L.; Maugis, P.

    2014-09-01

    This paper presents the coupling of the fuel performance code ALCYONE with the thermochemical code ANGE and its application to Iodine-Stress Corrosion Cracking (I-SCC). The coupling is illustrated by a 3D simulation of a power ramp. The release of chemically active gases (CsI(g), Tex(13D simulation, the definition of a stress corrosion initiation criterion is discussed. The combination of the hoop stress and of the quantity of reactive iodine (I(g), I2(g) and TeI2(g) only) released by the pellet is used to show that the necessary conditions for Pellet Cladding Interaction-Stress Corrosion Cracking (PCI-SCC) initiation, based on out-of-pile I-SCC laboratory tests criteria, are met during the simulated power transient.

  9. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    NASA Astrophysics Data System (ADS)

    Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.

    2014-02-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012©. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.

  10. Aeroacoustic Simulation of a Nose Landing Gear in an Open Jet Facility Using FUN3D

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Lockhard, David P.; Khorrami, Mehdi R.; Carlson, Jan-Renee

    2012-01-01

    Numerical simulations have been performed for a partially-dressed, cavity-closed nose landing gear configuration that was tested in NASA Langley s closed-wall Basic Aerodynamic Research Tunnel (BART) and in the University of Florida s open-jet acoustic facility known as UFAFF. The unstructured-grid flow solver, FUN3D, developed at NASA Langley Research center is used to compute the unsteady flow field for this configuration. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these computations. Time-averaged and instantaneous solutions compare favorably with the measured data. Unsteady flowfield data obtained from the FUN3D code are used as input to a Ffowcs Williams-Hawkings noise propagation code to compute the sound pressure levels at microphones placed in the farfield. Significant improvement in predicted noise levels is obtained when the flowfield data from the open jet UFAFF simulations is used as compared to the case using flowfield data from the closed-wall BART configuration.

  11. Aeroacoustic Simulation of Nose Landing Gear on Adaptive Unstructured Grids With FUN3D

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Khorrami, Mehdi R.; Park, Michael A.; Lockhard, David P.

    2013-01-01

    Numerical simulations have been performed for a partially-dressed, cavity-closed nose landing gear configuration that was tested in NASA Langley s closed-wall Basic Aerodynamic Research Tunnel (BART) and in the University of Florida's open-jet acoustic facility known as the UFAFF. The unstructured-grid flow solver FUN3D, developed at NASA Langley Research center, is used to compute the unsteady flow field for this configuration. Starting with a coarse grid, a series of successively finer grids were generated using the adaptive gridding methodology available in the FUN3D code. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these computations. Time-averaged and instantaneous solutions obtained on these grids are compared with the measured data. In general, the correlation with the experimental data improves with grid refinement. A similar trend is observed for sound pressure levels obtained by using these CFD solutions as input to a FfowcsWilliams-Hawkings noise propagation code to compute the farfield noise levels. In general, the numerical solutions obtained on adapted grids compare well with the hand-tuned enriched fine grid solutions and experimental data. In addition, the grid adaption strategy discussed here simplifies the grid generation process, and results in improved computational efficiency of CFD simulations.

  12. BioFVM: an efficient, parallelized diffusive transport solver for 3-D biological simulations

    PubMed Central

    Ghaffarizadeh, Ahmadreza; Friedman, Samuel H.; Macklin, Paul

    2016-01-01

    Motivation: Computational models of multicellular systems require solving systems of PDEs for release, uptake, decay and diffusion of multiple substrates in 3D, particularly when incorporating the impact of drugs, growth substrates and signaling factors on cell receptors and subcellular systems biology. Results: We introduce BioFVM, a diffusive transport solver tailored to biological problems. BioFVM can simulate release and uptake of many substrates by cell and bulk sources, diffusion and decay in large 3D domains. It has been parallelized with OpenMP, allowing efficient simulations on desktop workstations or single supercomputer nodes. The code is stable even for large time steps, with linear computational cost scalings. Solutions are first-order accurate in time and second-order accurate in space. The code can be run by itself or as part of a larger simulator. Availability and implementation: BioFVM is written in C ++ with parallelization in OpenMP. It is maintained and available for download at http://BioFVM.MathCancer.org and http://BioFVM.sf.net under the Apache License (v2.0). Contact: paul.macklin@usc.edu. Supplementary information: Supplementary data are available at Bioinformatics online. PMID:26656933

  13. Research on scene organization of process simulation in port 3D GIS

    NASA Astrophysics Data System (ADS)

    Ding, Jing; Jiang, Wenping

    2009-10-01

    At present, the application of three-dimensional GIS becomes more and more widespread gradually, but due to the defect of representing time, four-dimensional GIS based on spatial-temporal expression is facilitated to emerge and progress. Combined with developing the 3D dynamic demonstration of Tianjin center fishing port, this paper researches the mass data and animated simulation of building process and provides an approach that the data is dealt with in the way just as 2D map does such as classification and partition to get clarified data. At the same time, a scene integration method is proposed by dividing a large-scale 3D scene to several sub-scenes with a number of levels and various covering areas. And through editing and synthesizing the commentary, time axis and flight routes, the dynamic simulation and automatic demonstration are achieved. Based on the study above, a system of simulating and illustrating the port building process is designed and implemented.

  14. High-resolution 3D simulations of NIF ignition targets performed on Sequoia with HYDRA

    NASA Astrophysics Data System (ADS)

    Marinak, M. M.; Clark, D. S.; Jones, O. S.; Kerbel, G. D.; Sepke, S.; Patel, M. V.; Koning, J. M.; Schroeder, C. R.

    2015-11-01

    Developments in the multiphysics ICF code HYDRA enable it to perform large-scale simulations on the Sequoia machine at LLNL. With an aggregate computing power of 20 Petaflops, Sequoia offers an unprecedented capability to resolve the physical processes in NIF ignition targets for a more complete, consistent treatment of the sources of asymmetry. We describe modifications to HYDRA that enable it to scale to over one million processes on Sequoia. These include new options for replicating parts of the mesh over a subset of the processes, to avoid strong scaling limits. We consider results from a 3D full ignition capsule-only simulation performed using over one billion zones run on 262,000 processors which resolves surface perturbations through modes l = 200. We also report progress towards a high-resolution 3D integrated hohlraum simulation performed using 262,000 processors which resolves surface perturbations on the ignition capsule through modes l = 70. These aim for the most complete calculations yet of the interactions and overall impact of the various sources of asymmetry for NIF ignition targets. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

  15. 3-D-numerical approach to simulate an avalanche impact into a reservoir

    NASA Astrophysics Data System (ADS)

    Gabl, R.; Seibl, J.; Gems, B.; Aufleger, M.

    2015-06-01

    The impact of an avalanche into a reservoir induces an impulse wave, which poses a threat to population and infrastructure. For a good approximation of the generated wave height and length as well as the resulting outflow volume over structures and dams, formulas, which base on different simplifying assumptions, can be used. Further project-specific investigations by means of a scale model test or numerical simulations are advisable for complex reservoirs as well as the inclusion of hydraulic structures such as spillways. The paper presents a new approach for a 3-D-numerical simulation of an avalanche impact into a reservoir. In this model concept the energy and mass of the avalanche are represented by accelerated water on the real hill slope. Instead of snow, only water and air are used to simulate the moving avalanche with the software FLOW-3D. A significant advantage of this assumption is the self-adaptation of the model avalanche onto the terrain. In order to reach good comparability of the results with existing research at the ETH Zürich, a simplified reservoir geometry is investigated. Thus, a reference case has been analysed including a variation of three geometry parameters (still water depth in the reservoir, freeboard of the dam and reservoir width).

  16. Simulating Seismic Wave Propagation in 3-D Structure: A Case Study For Istanbul City

    NASA Astrophysics Data System (ADS)

    Yelkenci, Seda; Aktar, Mustafa

    2013-04-01

    Investigation of the wave propagation around the Marmara Sea, in particular for the city of Istanbul is critical because this target area is identified as one of the megacities with the highest seismic risk in the world. This study makes an attempt for creating an integrated 3D seismic/geologic model and precise understanding of 3-D wave propagation in the city of Istanbul. The approach is based on generating synthetic seismograms using realistic velocity structures as well as accurate location, focal mechanism and source parameters of reference earthquakes. The modarate size reference earthquakes occured in the Marmara Sea and were recorded by the National Seismic Network of Turkey as well as the network of Istanbul Early Warning and Rapid Response System. The seismograms are simulated by means of a 3-D finite difference method operated on parallel processing environment. In the content of creating a robust velocity model; 1D velocity models which are derived fom previous crustal studies of Marmara region such as refraction seismic and receiver functions have been conducted firstly for depths greater than 1km. Velocity structure in shallower part of the study region is then derived from recent geophysical and geotechnical surveys. To construct 3-D model from the obtained 1-D model data, a variety of interpolation methods are considered. According to the observations on amplitude and arrival time based on comparison of simulated seismograms, the considered velocity model is refined the way that S delay times are compensated. Another important task of this work is an application of the finite difference method to estimate three-dimensional seismic responses for a specified basin structure including soft sediments with low shear velocities in respect of the surrounded area in the Asian part of Istanbul. The analysis performed both in the time and frequency domain, helps in understanding of the comprehensive wave propagation characteristics and the distribution of

  17. Coupling Magnetic Fields and ALE Hydrodynamics for 3D Simulations of MFCG's

    SciTech Connect

    White, D; Rieben, R; Wallin, B

    2006-09-20

    We review the development of a full 3D multiphysics code for the simulation of explosively driven Magnetic Flux Compression Generators (MFCG) and related pulse power devices. In a typical MFCG the device is seeded with an initial electric current and the device is then detonated. The detonation compresses the magnetic field and amplifies the current. This is a multiphysics problem in that detonation kinetics, electromagnetic diffusion and induction, material deformation, and thermal effects are all important. This is a tightly coupled problem in that the different physical quantities have comparable spatial and temporal variation, and hence should be solved simultaneously on the same computational mesh.

  18. Simulation studies of defect textures and dynamics in 3-d cholesteric droplets

    NASA Astrophysics Data System (ADS)

    Gimenez-Pinto, Vianney; Lu, Shin-Ying; Selinger, Jonathan; Selinger, Robin

    2010-03-01

    We model defect texture evolution in droplets of cholesteric liquid crystals by solving for the dynamics of the nematic director field. In order to accommodate defects in the simulated texture, we use a finite difference formulation that is explicitly independent of sign reversal of the director at any position in the sample. Textures are visualized using either the Berreman 4x4 matrix method or by mapping free energy density. We study both planar and focal conic cholesteric textures in 3-d spherical and cylindrical droplets, with the goal to optimize device geometries for bistable display applications.

  19. Simulation studies of dynamics and defect textures in 3-d cholesteric droplets

    NASA Astrophysics Data System (ADS)

    Gimenez-Pinto, Vianney; Lu, Shin-Ying; Selinger, Jonathan; Selinger, Robin

    2010-04-01

    We model defect texture evolution in droplets of cholesteric liquid crystals by solving for the dynamics of the nematic director field. In order to accommodate defects in the simulated texture, we use a finite difference formulation that is explicitly independent of sign reversal of the director at any position in the sample. Textures are visualized using either the Berreman 4x4 matrix method or by mapping free energy density. We study both planar and focal conic cholesteric textures in 3-d spherical and cylindrical droplets, with the goal to optimize device geometries for bistable display applications.

  20. 3D Simulation of an Audible Ultrasonic Electrolarynx Using Difference Waves

    PubMed Central

    Mills, Patrick; Zara, Jason

    2014-01-01

    A total laryngectomy removes the vocal folds which are fundamental in forming voiced sounds that make speech possible. Although implanted prosthetics are commonly used in developed countries, simple handheld vibrating electrolarynxes are still common worldwide. These devices are easy to use but suffer from many drawbacks including dedication of a hand, mechanical sounding voice, and sound leakage. To address some of these drawbacks, we introduce a novel electrolarynx that uses vibro-acoustic interference of dual ultrasonic waves to generate an audible fundamental frequency. A 3D simulation of the principles of the device is presented in this paper. PMID:25401965

  1. Simulations of implosions with a 3D, parallel, unstructured-grid, radiation-hydrodynamics code

    SciTech Connect

    Kaiser, T B; Milovich, J L; Prasad, M K; Rathkopf, J; Shestakov, A I

    1998-12-28

    An unstructured-grid, radiation-hydrodynamics code is used to simulate implosions. Although most of the problems are spherically symmetric, they are run on 3D, unstructured grids in order to test the code's ability to maintain spherical symmetry of the converging waves. Three problems, of increasing complexity, are presented. In the first, a cold, spherical, ideal gas bubble is imploded by an enclosing high pressure source. For the second, we add non-linear heat conduction and drive the implosion with twelve laser beams centered on the vertices of an icosahedron. In the third problem, a NIF capsule is driven with a Planckian radiation source.

  2. Ultrafast vectorized multispin coding algorithm for the Monte Carlo simulation of the 3D Ising model

    NASA Astrophysics Data System (ADS)

    Wansleben, Stephan

    1987-02-01

    A new Monte Carlo algorithm for the 3D Ising model and its implementation on a CDC CYBER 205 is presented. This approach is applicable to lattices with sizes between 3·3·3 and 192·192·192 with periodic boundary conditions, and is adjustable to various kinetic models. It simulates a canonical ensemble at given temperature generating a new random number for each spin flip. For the Metropolis transition probability the speed is 27 ns per updates on a two-pipe CDC Cyber 205 with 2 million words physical memory, i.e. 1.35 times the cycle time per update or 38 million updates per second.

  3. Numerical simulation of a combined oxidation ditch flow using 3D k-epsilon turbulence model.

    PubMed

    Luo, Lin; Li, Wei-min; Deng, Yong-sen; Wang, Tao

    2005-01-01

    The standard three dimensional(3D) k-epsilon turbulence model was applied to simulate the flow field of a small scale combined oxidation ditch. The moving mesh approach was used to model the rotor of the ditch. Comparison of the computed and the measured data is acceptable. A vertical reverse flow zone in the ditch was found, and it played a very important role in the ditch flow behavior. The flow pattern in the ditch is discussed in detail, and approaches are suggested to improve the hydrodynamic performance in the ditch. PMID:16313008

  4. TOPAS Tool for Particle Simulation

    Energy Science and Technology Software Center (ESTSC)

    2013-05-30

    TOPAS lets users simulate the passage of subatomic particles moving through any kind of radiation therapy treatment system, can import a patient geometry, can record dose and other quantities, has advanced graphics, and is fully four-dimensional (3D plus time) to handle the most challenging time-dependent aspects of modern cancer treatments.TOPAS unlocks the power of the most accurate particle transport simulation technique, the Monte Carlo (MC) method, while removing the painstaking coding work such methods usedmore » to require. Research physicists can use TOPAS to improve delivery systems towards safer and more effective radiation therapy treatments, easily setting up and running complex simulations that previously used to take months of preparation. Clinical physicists can use TOPAS to increase accuracy while reducing side effects, simulating patient-specific treatment plans at the touch of a button. TOPAS is designed as a “user code” layered on top of the Geant4 Simulation Toolkit. TOPAS includes the standard Geant4 toolkit, plus additional code to make Geant4 easier to control and to extend Geant4 functionality. TOPAS aims to make proton simulation both “reliable” and “repeatable.” “Reliable” means both accurate physics and a high likelihood to simulate precisely what the user intended to simulate, reducing issues of wrong units, wrong materials, wrong scoring locations, etc. “Repeatable” means not just getting the same result from one simulation to another, but being able to easily restore a previously used setup and reducing sources of error when a setup is passed from one user to another. TOPAS control system incorporates key lessons from safety management, proactively removing possible sources of user error such as line-ordering mistakes In control files. TOPAS has been used to model proton therapy treatment examples including the UCSF eye treatment head, the MGH stereotactic alignment in radiosurgery treatment head and the MGH gantry

  5. TOPAS Tool for Particle Simulation

    SciTech Connect

    Perl, Joseph

    2013-05-30

    TOPAS lets users simulate the passage of subatomic particles moving through any kind of radiation therapy treatment system, can import a patient geometry, can record dose and other quantities, has advanced graphics, and is fully four-dimensional (3D plus time) to handle the most challenging time-dependent aspects of modern cancer treatments.TOPAS unlocks the power of the most accurate particle transport simulation technique, the Monte Carlo (MC) method, while removing the painstaking coding work such methods used to require. Research physicists can use TOPAS to improve delivery systems towards safer and more effective radiation therapy treatments, easily setting up and running complex simulations that previously used to take months of preparation. Clinical physicists can use TOPAS to increase accuracy while reducing side effects, simulating patient-specific treatment plans at the touch of a button. TOPAS is designed as a “user code” layered on top of the Geant4 Simulation Toolkit. TOPAS includes the standard Geant4 toolkit, plus additional code to make Geant4 easier to control and to extend Geant4 functionality. TOPAS aims to make proton simulation both “reliable” and “repeatable.” “Reliable” means both accurate physics and a high likelihood to simulate precisely what the user intended to simulate, reducing issues of wrong units, wrong materials, wrong scoring locations, etc. “Repeatable” means not just getting the same result from one simulation to another, but being able to easily restore a previously used setup and reducing sources of error when a setup is passed from one user to another. TOPAS control system incorporates key lessons from safety management, proactively removing possible sources of user error such as line-ordering mistakes In control files. TOPAS has been used to model proton therapy treatment examples including the UCSF eye treatment head, the MGH stereotactic alignment in radiosurgery treatment head and the MGH gantry treatment heads

  6. Terascale direct numerical simulations of turbulent combustion using S3D.

    SciTech Connect

    Sankaran, Ramanan; Mellor-Crummy, J.; DeVries, M.; Yoo, Chun Sang; Ma, K. L.; Podhorski, N.; Liao, W. K.; Klasky, S.; de Supinski, B.; Choudhary, A.; Hawkes, Evatt R.; Chen, Jacqueline H.; Shende, Sameer

    2008-08-01

    Computational science is paramount to the understanding of underlying processes in internal combustion engines of the future that will utilize non-petroleum-based alternative fuels, including carbon-neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions of particulates and nitrogen oxides. Next-generation engines will likely operate at higher pressures, with greater amounts of dilution and utilize alternative fuels that exhibit a wide range of chemical and physical properties. Therefore, there is a significant role for high-fidelity simulations, direct numerical simulations (DNS), specifically designed to capture key turbulence-chemistry interactions in these relatively uncharted combustion regimes, and in particular, that can discriminate the effects of differences in fuel properties. In DNS, all of the relevant turbulence and flame scales are resolved numerically using high-order accurate numerical algorithms. As a consequence terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air co-flow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. The enabling computer science, applied to combustion science, is also required in many other terascale physics and engineering simulations. In particular, performance monitoring is used to identify the performance of key kernels in the DNS code, S3D and especially memory

  7. Terascale direct numerical simulations of turbulent combustion using S3D

    NASA Astrophysics Data System (ADS)

    Chen, J. H.; Choudhary, A.; de Supinski, B.; DeVries, M.; Hawkes, E. R.; Klasky, S.; Liao, W. K.; Ma, K. L.; Mellor-Crummey, J.; Podhorszki, N.; Sankaran, R.; Shende, S.; Yoo, C. S.

    2009-01-01

    Computational science is paramount to the understanding of underlying processes in internal combustion engines of the future that will utilize non-petroleum-based alternative fuels, including carbon-neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions of particulates and nitrogen oxides. Next-generation engines will likely operate at higher pressures, with greater amounts of dilution and utilize alternative fuels that exhibit a wide range of chemical and physical properties. Therefore, there is a significant role for high-fidelity simulations, direct numerical simulations (DNS), specifically designed to capture key turbulence-chemistry interactions in these relatively uncharted combustion regimes, and in particular, that can discriminate the effects of differences in fuel properties. In DNS, all of the relevant turbulence and flame scales are resolved numerically using high-order accurate numerical algorithms. As a consequence terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air coflow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. The enabling computer science, applied to combustion science, is also required in many other terascale physics and engineering simulations. In particular, performance monitoring is used to identify the performance of key kernels in the DNS code, S3D and especially memory

  8. Insights from 3D numerical simulations on the dynamics of the India-Asia collision zone

    NASA Astrophysics Data System (ADS)

    Pusok, A. E.; Kaus, B.; Popov, A.

    2013-12-01

    The dynamics of the India-Asia collision zone remains one of the most remarkable topics of the current research interest: the transition from subduction to collision and uplift, followed by the rise of the abnormally thick Tibetan plateau, and the deformation at its Eastern and Western syntaxes, are processes still not fully understood. Models that have addressed this topic include wholescale underthrusting of Indian lithospheric mantle under Tibet, distributed homogeneous shortening or the thin-sheet model, slip-line field model for lateral extrusion or lower crustal flow models for the exhumation of the Himalayan units and lateral spreading of the Tibetan plateau. Of these, the thin-sheet model has successfully illustrated some of the basic physics of continental collision and has the advantage of a 3D model being reduced to 2D, but one of its major shortcomings is that it cannot simultaneously represent channel flow and gravitational collapse of the mantle lithosphere, since these mechanisms require the lithosphere to interact with the underlying mantle, or to have a vertically non-homogeneous rheology. As a consequence, 3D models are emerging as powerful tools to understand the dynamics of coupled systems. However, because of yet recent developments and various complexities, the current 3D models simulating the dynamics of continent collision zones have relied on certain explicit assumptions, such as replacing part of the asthenosphere with various types of boundary conditions that mimic the effect of mantle flow, in order to focus on the lithospheric/crustal deformation. Here, we employ the parallel 3D code LaMEM (Lithosphere and Mantle Evolution Model), with a finite difference staggered grid solver, which is capable of simulating lithospheric deformation while simultaneously taking mantle flow and a free surface into account. We present qualitative results on lithospheric and upper-mantle scale simulations in which the Indian lithosphere is subducted and

  9. Modeling of Localized Neutral Particle Sources in 3D Edge Plasmas

    SciTech Connect

    Umansky, M V; Rognlien, T D; Fenstermacher, M E; Borchardt, M; Mutzke, A; Riemann, J; Schneider, R; Owen, L W

    2002-05-23

    A new edge plasma code BoRiS [1] has a fully 3D fluid plasma model. We supplement BoRiS with a 3D fluid neutral model including equations for parallel momentum and collisional perpendicular diffusion. This makes BoRiS an integrated plasma-neutral model suitable for a variety of applications. We present modeling results for a localized gas source in the geometry of the NCSX stellarator.

  10. Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

    DOE PAGESBeta

    Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.; Gable, Carl W.; Karra, Satish

    2015-09-16

    The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates massmore » balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.« less

  11. Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

    SciTech Connect

    Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.; Gable, Carl W.; Karra, Satish

    2015-09-16

    The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates mass balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.

  12. Synthesis of micro-sized shell-isolated 3D plasmonic superstructures for in situ single-particle SERS monitoring.

    PubMed

    Zhang, Kun; Zhao, Jingjing; Ji, Ji; Liu, Baohong

    2016-04-21

    A single-particle SERS system enabling real-time and in situ observation of Au-catalyzed reactions has been developed. Both the catalytic activity and the SERS effect are coupled into a single bi-functional 3D superstructure comprising Au nanosatellites self-assembled onto a shell-insulated Ag microflower core, which eliminates the interference from photocatalysis. PMID:27044886

  13. A 3-D nonisothermal flow simulation and pulling force model for injection pultrusion processes

    NASA Astrophysics Data System (ADS)

    Mustafa, Ibrahim

    1998-12-01

    Injected Pultrusion (IP) is an efficient way of producing high quality, low cost, high volume and constant cross-section polymeric composites. This process has been developed recently, and the efforts to optimize it are still underway. This work is related to the development of a 3-D non-isothermal flow model for the IP processes. The governing equations for transport of mass, momentum and, energy are formulated by using a local volume averaging approach, and the Finite Element/Control Volume method is used to solve the system of equations numerically. The chemical species balance equation is solved in the Lagrangian frame of reference whereas the energy equation is solved using Galerkin, SU (Streamline Upwind), and SUPG (Streamline Upwind Petrov Galerkin) approaches. By varying degrees of freedom and the flow rates of the resin, it is shown that at high Peclet numbers the SUPG formulation performs better than the SU and the Galerkin methods in all cases. The 3-D model predictions for degree of cure and temperature are compared with a one dimensional analytical solution and the results are found satisfactory. Moreover, by varying the Brinkman Number, it is shown that the effect of viscous dissipation is insignificant. The 3-D flow simulations have been carried out for both thin and thick parts and the results are compared with the 2-D model. It is shown that for thick parts 2-D simulations render erroneous results. The effect of changing permeability on the flow fronts is also addressed. The effect of increasing taper angle on the model prediction is also investigated. A parametric study is conducted to isolate optimum conditions for both isothermal and non-isothermal cases using a straight rectangular die and a die with a tapered inlet. Finally, a simple pulling force model is developed and the pulling force required to pull the carbon-epoxy fiber resin system is estimated for dies of varying tapered inlet.

  14. Modelling the RXTE light curve of η Carinae from a 3D SPH simulation of its binary wind collision

    NASA Astrophysics Data System (ADS)

    Okazaki, A. T.; Owocki, S. P.; Russell, C. M. P.; Corcoran, M. F.

    2008-07-01

    The very massive star system η Carinae exhibits regular 5.54 yr (2024 d) period disruptive events in wavebands ranging from the radio to X-ray. There is a growing consensus that these events likely stem from periastron passage of an (as yet) unseen companion in a highly eccentric (e ~ 0.9) orbit. This Letter presents 3D smoothed particle hydrodynamics (SPH) simulations of the orbital variation of the binary wind-wind collision, and applies these to modelling the X-ray light curve observed by the Rossi X-ray Timing Explorer (RXTE). By providing a global 3D model of the phase variation of the density of the interacting winds, the simulations allow computation of the associated variation in X-ray absorption, presumed here to originate from near the apex of the wind-wind interaction cone. We find that the observed RXTE light curve can be readily fitted if the observer's line of sight is within this cone along the general direction of apastron. Specifically, the data are well fitted by an assumed inclination i = 45° for the orbit's polar axis, which is thus consistent with orbital angular momentum being along the inferred polar axis of the Homunculus nebula. The fits also constrain the position angle φ that an orbital-plane projection makes with the apastron side of the semimajor axis, strongly excluding positions φ < 9° along or to the retrograde side of the axis, with the best-fitting position given by φ = 27°. Overall the results demonstrate the utility of a fully 3D dynamical model for constraining the geometric and physical properties of this complex colliding wind binary system.

  15. 3D Radiative Transfer in Eta Carinae: The SimpleX Radiative Transfer Algorithm Applied to 3D SPH Simulations of Eta Car's Colliding Winds

    NASA Astrophysics Data System (ADS)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Icke, V.; Gull, T. R.

    2014-04-01

    At the heart of the spectacular bipolar Homunculus nebula lies an extremely luminous (5*10^6 L_sun) colliding wind binary with a highly eccentric (e ~ 0.9), 5.54-year orbit and a total mass ~ 110 M_sun. Our closest (D ~ 2.3 kpc) and best example of a pre-hypernova environment, Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions, stellar wind-wind collisions, and massive star evolution. In order to improve our knowledge of the system, we need to generate synthetic observations and compare them with the already available and future HST/STIS data. We present initial results from full 3D radiative transfer post-processing of 3D SPH hydrodynamical simulations of the interacting winds of Eta Carinae. We use SimpleX algorithm to obtain the ionization fractions of hydrogen and helium, this results in ionization maps of both species that constrain the regions where these lines can form. These results will allow us to put constraints on the number of ionizing photons coming from the companion. This construction of synthetic observations allows us to obtain insight into the highly complex 3D flows in Eta, from the shape of the ionized volume and its resulting optical/spectral appearance.

  16. 3D simulations of pre-ionized and two-stage ionization injected laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Davidson, Asher; Zheng, Ming; Lu, Wei; Xu, Xinlu; Joshi, Chang; Silva, Luis O.; Martins, Joana; Fonseca, Ricardo; Mori, Warren B.

    2012-12-01

    In plasma based accelerators (LWFA and PWFA), the methods of injecting high quality electron bunches into the accelerating wakefield is of utmost importance for various applications. To fully understand the numerical effect of simulating the trapping process, numerous numerical convergence tests were performed to ensure the correctness of preionized simulations which confirm the physical picture first proposed in [1]. We Further investigate the use of a two-stage ionization injected LWFA to achieve high quality monoenergetic beams through the use of 3D PIC simulations. The first stage constitutes the Injection Regime, which is 99.5% He and 0.5% N, while the second stage constitutes the Acceleration Regime, which is entirely composed of He. Two of the simulations model the parameters of the LWFA experiments for the LLNL Callisto laser, at laser powers of 90 and 100TW. energies as high as 680MeV were observed in the 90TW simulation, and those as high as 1.44GeV were observed in the 100TW simulation. The affect of the matching condition of the spot size in this LWFA is discussed.

  17. ALE3D Simulation of Heating and Violence in a Fast Cookoff Experiment with LX-10

    SciTech Connect

    McClelland, M A; Maienschein, J L; Howard, W M; Nichols, A L; deHaven, M R; Strand, O T

    2006-06-26

    We performed a computational and experimental analysis of fast cookoff of LX-10 (94.7% HMX, 5.3% Viton A) confined in a 2 kbar steel tube with reinforced end caps. A Scaled-Thermal-Explosion-eXperiment (STEX) was completed in which three radiant heaters were used to heat the vessel until ignition, resulting in a moderately violent explosion after 20.4 minutes. Thermocouple measurements showed tube temperatures as high as 340 C at ignition and LX-10 surface temperatures as high as 279 C, which is near the melting point of HMX. Three micro-power radar systems were used to measure mean fragment velocities of 840 m/s. Photonics Doppler Velocimeters (PDVs) showed a rapid acceleration of fragments over 80 {micro}s. A one-dimensional ALE3D cookoff model at the vessel midplane was used to simulate the heating, thermal expansion, LX-10 decomposition composition, and closing of the gap between the HE (High Explosive) and vessel wall. Although the ALE3D simulation terminated before ignition, the model provided a good representation of heat transfer through the case and across the dynamic gap to the explosive.

  18. ALE3D Simulation and Measurement of Violence in a Fast Cookoff Experiment with LX-10

    SciTech Connect

    McClelland, M A; Maienschein, J L; Howard, W M; deHaven, M R

    2006-11-22

    We performed a computational and experimental analysis of fast cookoff of LX-10 (94.7% HMX, 5.3% Viton A) confined in a 2 kbar steel tube with reinforced end caps. A Scaled-Thermal-Explosion-eXperiment (STEX) was completed in which three radiant heaters were used to heat the vessel until ignition, resulting in a moderately violent explosion after 20.4 minutes. Thermocouple measurements showed tube temperatures as high as 340 C at ignition and LX-10 surface temperatures as high as 279 C, which is near the melting point of HMX. Three micro-power radar systems were used to measure mean fragment velocities of 840 m/s. Photonics Doppler Velocimeters (PDVs) showed a rapid acceleration of fragments over 80 {micro}s. A one-dimensional ALE3D cookoff model at the vessel midplane was used to simulate the heating, thermal expansion, LX-10 decomposition composition, and closing of the gap between the HE (High Explosive) and vessel wall. Although the ALE3D simulation terminated before ignition, the model provided a good representation of heat transfer through the case and across the dynamic gap to the explosive.

  19. 3D Global Two-Fluid Simulations of Turbulence in LAPD

    NASA Astrophysics Data System (ADS)

    Fisher, Dustin; Rogers, Barrett; Ricci, Paolo

    2012-10-01

    3D global two-fluid simulations are presented in an ongoing effort to identify and understand the physics of instabilities that arise in the Large Plasma Device (LAPD) at UCLA's Basic Science Facility. The LAPD, with its wide range of tunable parameters and device configurations, is ideally suited for studying space and laboratory plasmas. Moreover, the highly detailed and reproducible measurements of the LAPD lend themselves amicably to comparisons with simulations. Ongoing modeling is done using a modified version of the Global Braginskii Solver (GBS) [1] that models the plasma from source to edge region in a fully 3D two-fluid code. The reduced Braginskii equations are solved on a field-aligned grid using a finite difference method and 4th order Runge-Kutta time stepping and are parallelized on Dartmouth's Discovery cluster. Recent progress has been made to account for the thermionic cathode emission of fast electrons at the source, the axial dependence of the plasma source, and it is now possible to vary the potential on the front and side walls. Preliminary results, seen from the density and temperature profiles, show that the low frequency Kelvin Helmholtz instability still dominates the turbulence in the device.[4pt] [1] B. Rogers and P. Ricci. Phys. Rev. Lett. 104:225002, 2010

  20. 3D Simulations of Galaxies in Clusters : Mass Accretion and Stripping

    NASA Astrophysics Data System (ADS)

    Balsara, D.

    1995-12-01

    The high metallicities found in cluster gas provides strong indication that galaxies moving in cluster gas must have had a strong exchange of their interstellar medium gas with the cluster's gas. Thus understanding the interstellar medium of galaxies in clusters is an intrinsically interesting question. Further interest in this question derives from the fact that magnetic fields have been observed in cluster gas. The turbulence churned up by such galaxies can be a strong source of dynamo action in the cluster gas. The fact that narraow angle tailed radio jets flowing through cluster gas remain synchrotron bright at distances that are well beyond those expected from synchrotron decay time arguments also points to the possibility that a turbulent cluster medium re-energizes them. Prior 2d simulations by Balsara, Livio and O'Dea (1994) had shown that ellipticals moving through cluster gas produce a pumping mode instability. This instability is a direct analogue to the pumping mode instability observed in Bondi-Hoyle accretion onto white dwarfs and neutron stars in wind-fed systems. Bondi-Hoyle accretion also produces a flip-flop instability in binary star systems. Though the threshold for the onset of this instability is much higher, once it sets in it overwhelms the pumping mode instability. Recent studies have shown that in 3d the flip-flop instability in binary star systems is much diminished. The present study shows that in 3d simulations the flip-flop instability for galaxies is supressed.

  1. Availability study of CFD-based Mask3D simulation method for next generation lithography technologies

    NASA Astrophysics Data System (ADS)

    Takahashi, M.; Kawabata, Y.; Washitani, T.; Tanaka, S.; Maeda, S.; Mimotogi, S.

    2014-03-01

    In progress of lithography technologies, the importance of Mask3D analysis has been emphasized because the influence of mask topography effects is not avoidable to be increased explosively. An electromagnetic filed simulation method, such as FDTD, RCWA and FEM, is applied to analyze those complicated phenomena. We have investigated Constrained Interpolation Profile (CIP) method, which is one of the Method of Characteristics (MoC), for Mask3D analysis in optical lithography. CIP method can reproduce the phase of propagating waves with less numerical error by using high order polynomial function. The restrictions of grid distance are relaxed with spatial grid. Therefore this method reduces the number of grid points in complex structure. In this paper, we study the feasibility of CIP scheme applying a non-uniform and spatial-interpolated grid to practical mask patterns. The number of grid points might be increased in complex layout and topological structure since these structures require a dense grid to remain the fidelity of each design. We propose a spatial interpolation method based on CIP method same as time-domain interpolation to reduce the number of grid points to be computed. The simulation results of two meshing methods with spatial interpolation are shown.

  2. Comparing TID simulations using 3-D ray tracing and mirror reflection

    NASA Astrophysics Data System (ADS)

    Huang, X.; Reinisch, B. W.; Sales, G. S.; Paznukhov, V. V.; Galkin, I. A.

    2016-04-01

    Measuring the time variations of Doppler frequencies and angles of arrival (AoA) of ionospherically reflected HF waves has been proposed as a means of detecting the occurrence of traveling ionospheric disturbances (TIDs). Simulations are made using ray tracing through the International Reference Ionosphere (IRI) electron density model in an effort to reproduce measured signatures. The TID is represented by a wavelike perturbation of the 3-D electron density traveling horizontally in the ionosphere with an amplitude that varies sinusoidally with time. By judiciously selecting the TID parameters the ray tracing simulation reproduces the observed Doppler frequencies and AoAs. Ray tracing in a 3-D realistic ionosphere is, however, excessively time consuming considering the involved homing procedures. It is shown that a carefully selected reflecting corrugated mirror can reproduce the time variations of the AoA and Doppler frequency. The results from the ray tracing through the IRI model ionosphere and the mirror model reflections are compared to assess the applicability of the mirror-reflection model.

  3. 3D face recognition using simulated annealing and the surface interpenetration measure.

    PubMed

    Queirolo, Chauã C; Silva, Luciano; Bellon, Olga R P; Segundo, Maurício Pamplona

    2010-02-01

    This paper presents a novel automatic framework to perform 3D face recognition. The proposed method uses a Simulated Annealing-based approach (SA) for range image registration with the Surface Interpenetration Measure (SIM), as similarity measure, in order to match two face images. The authentication score is obtained by combining the SIM values corresponding to the matching of four different face regions: circular and elliptical areas around the nose, forehead, and the entire face region. Then, a modified SA approach is proposed taking advantage of invariant face regions to better handle facial expressions. Comprehensive experiments were performed on the FRGC v2 database, the largest available database of 3D face images composed of 4,007 images with different facial expressions. The experiments simulated both verification and identification systems and the results compared to those reported by state-of-the-art works. By using all of the images in the database, a verification rate of 96.5 percent was achieved at a False Acceptance Rate (FAR) of 0.1 percent. In the identification scenario, a rank-one accuracy of 98.4 percent was achieved. To the best of our knowledge, this is the highest rank-one score ever achieved for the FRGC v2 database when compared to results published in the literature. PMID:20075453

  4. Fast Wave Trains Associated with Solar Eruptions: Insights from 3D Thermodynamic MHD Simulations

    NASA Astrophysics Data System (ADS)

    Downs, C.; Liu, W.; Torok, T.; Linker, J.; Mikic, Z.; Ofman, L.

    2015-12-01

    EUV imaging observations during the SDO/AIA era have provided new insights into a variety of wave phenomena occurring in the low solar corona. One example is the observation of quasi-periodic, fast-propagating wave trains that are associated with solar eruptions, including flares and CMEs. While there has been considerable progress in understanding such waves from both an observational and theoretical perspective, it remains a challenge to pin down their physical origin. In this work, we detail our results from a case-study 3D thermodynamic MHD simulation of a coronal mass ejection where quasi-periodic wave trains are generated during the simulated eruption. We find a direct correlation between the onset of non-steady reconnection in the flare current sheet and the generation of quasi-periodic wave train signatures when patchy, collimated downflows interact with the flare arcade. Via forward modeling of SDO/AIA observables, we explore how the appearance of the wave trains is affected by line-of-sight integration and the multi-thermal nature of the coronal medium. We also examine how the wave trains themselves are channeled by natural waveguides formed in 3D by the non-uniform background magnetic field. While the physical association of the reconnection dynamics to the generation of quasi-periodic wave trains appears to be a compelling result, unanswered questions posed from recent observations as well as future prospects will be discussed.

  5. Investigation of Charge Gain in Diamond Electron Beam Amplifiers Via 3D Simulations

    SciTech Connect

    Busby,R.; Rao,T.; D.A. Dimitrov, J.R. Cary, I. Ben-Zvi, X. Chang, J. Keister, E. Muller, J. Smedley, Q. Wu

    2009-05-04

    A promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved in the generation ofelectron beams from diamond, we have been developing models (within the VORPAL computational framework) to simulate secondary electron generation and charge transport. The currently implemented models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We will present results from 3D VORPAL simulations with these capabilities on charge gain as a function of primary electron energy and applied electric field. Moreover, we consider effects of electron and hole cloud expansion (initiated by primary electrons) and separation in a surface domain of diamond.

  6. Interpreting Irradiance Distributions Using High-Resolution 3D MHD Simulations

    NASA Astrophysics Data System (ADS)

    Peck, Courtney; Rast, Mark; Criscuoli, Serena; Uitenbroek, Han; Rempel, Matthias D.

    2016-05-01

    We present initial results of studies aimed at understanding the impact of the unresolved magnetic field distribution on solar spectral irradiance. Using high-resolution 3D MHD simulations (from MURaM code) and spectral synthesis (with the RH code), we examine the emergent spectra of two atmospheres with similar mean field strengths but differing imposed-field conditions at wavelengths spanning from visible to infrared. Comparing the contrast against the magnetic field strength for the two magnetic simulations, we find differences in the distributions of contrasts versus field strength. We repeat the analysis after convolving the images with the PSF of a typical solar telescope (1-meter) and discuss the potential implications for irradiance modeling and future steps.

  7. VAWT (Vertical-Axis Wind Turbines) stochastic loads using a 3-D turbulence simulation

    SciTech Connect

    Homicz, G.F.

    1988-01-01

    The stochastic (i.e., random) aerodynamic loads created by atmospheric turbulence are thought to be a primary cause of premature blade fatigue in Vertical-Axis Wind Turbines (VAWTs). This paper describes a computer program for the prediction of these stochastic loads, based on a full 3-D simulation of the turbulence field. Computed results using this model are compared with the deterministic (periodic) loads which occur in the absence of turbulence, and with the predictions of an earlier model which employed a 1-D simulation of the turbulence. The results show that not only are instantaneous loads significantly influenced by turbulence, but that load distributions averaged over numerous revolutions are affected as well. A particularly interesting finding is that, for the same mean wind speed, the average output power is altered by turbulence. 16 refs., 6 figs., 1 tab.

  8. VAWT (Vertical-Axis Wind Turbines) stochastic loads using a 3-D turbulence simulation

    NASA Astrophysics Data System (ADS)

    Homicz, Gregory F.

    The stochastic (i.e., random) aerodynamic loads created by atmospheric turbulence are thought to be a primary cause of premature blade fatigue in Vertical-Axis Wind Turbines (VAWTs). This paper describes a computer program for the prediction of these stochastic loads, based on a full 3-D simulation of the turbulence field. Computed results using this model are compared with the deterministic (periodic) loads which occur in the absence of turbulence, and with the predictions of an earlier model which employed a 1-D simulation of the turbulence. The results show that not only are instantaneous loads significantly influenced by turbulence, but that load distributions averaged over numerous revolutions are affected as well. A particularly interesting finding is that, for the same mean wind speed, the average output power is altered by turbulence.

  9. Nonintrusive 3D reconstruction of human bone models to simulate their bio-mechanical response

    NASA Astrophysics Data System (ADS)

    Alexander, Tsouknidas; Antonis, Lontos; Savvas, Savvakis; Nikolaos, Michailidis

    2012-06-01

    3D finite element models representing functional parts of the human skeletal system, have been repeatedly introduced over the last years, to simulate biomechanical response of anatomical characteristics or investigate surgical treatment. The reconstruction of geometrically accurate FEM models, poses a significant challenge for engineers and physicians, as recent advances in tissue engineering dictate highly customized implants, while facilitating the production of alloplast materials that are employed to restore, replace or supplement the function of human tissue. The premises of every accurate reconstruction method, is to encapture the precise geometrical characteristics of the examined tissue and thus the selection of a sufficient imaging technique is of the up-most importance. This paper reviews existing and potential applications related to the current state-of-the-art of medical imaging and simulation techniques. The procedures are examined by introducing their concepts; strengths and limitations, while the authors also present part of their recent activities in these areas. [Figure not available: see fulltext.

  10. 3D Transient CFD Simulation of Scroll Compressors with the Tip Seal

    NASA Astrophysics Data System (ADS)

    Gao, Haiyang; Ding, Hui; Jiang, Yu

    2015-08-01

    A new template simulation tool is developed for scroll compressors/expanders capable of modelling tip seal leakages. This scroll template generates a high quality 3D multiblock structured mesh from user-input stationary and orbiting scroll surfaces. The mesh movement is then automatically calculated to account for every position of the orbiting scroll, maintaining good grid quality and smooth movement throughout the whole revolution. A state- of-the-art efficient CFD solver is used to solve Navier-Stokes equations, capable of simulation with both real gas and ideal gas. A case study is presented for a generic scroll compressor with refrigerant R410A. The case was run with and without the tip seal volumes. Comparisons are made to show the impact of tip seals on the compressor performance.

  11. Investigating the guiding of streamers in nitrogen/oxygen mixtures with 3D simulations

    NASA Astrophysics Data System (ADS)

    Teunissen, Jannis; Nijdam, Sander; Takahashi, Eiichi; Ebert, Ute

    2014-10-01

    Recent experiments by S. Nijdam and E. Takahashi have demonstrated that streamers can be guided by weak pre-ionization in nitrogen/oxygen mixtures, as long as there is not too much oxygen (less than 1%). The pre-ionization was created by a laser beam, and was orders of magnitude lower than the density in a streamer channel. Here, we will study the guiding of streamers with 3D numerical simulations. First, we present simulations that can be compared with the experiments and confirm that the laser pre-ionization does not introduce space charge effects by itself. Then we investigate topics as: the conditions under which guiding can occur; how photoionization reduces the guiding at higher oxygen concentrations and whether guided streamers keep their propagation direction outside the pre-ionization. JT was supported by STW Project 10755, SN by the FY2012 Researcher Exchange Program between JSPS and NWO, and ET by JSPS KAKENHI Grant Number 24560249.

  12. Parameter modeling for nanopore lonic field effect transistors in 3-D device simulation.

    PubMed

    Park, Jun-Mo; Chun, Honggu; Park, Y Eugene; Park, Byung-Gook; Lee, Jong-Ho

    2014-11-01

    An Ion Field Effect Transistor (IFET) with nanopore structure was modeled in a conventional 3-dimensional (3-D) device simulator to understand current-voltage (I-V) characteristics and underlying physics of the device. Since the nanopore was filled with positive ions (K+) ions due to the negative interface charge on the insulator surface and negative gate bias condition, we could successfully simulate the IFET structure using modified p-type silicon to mimic KCl solution. We used p-type silicon with a doping concentration of 6.022 x 10(16) cm(-3) which has the same concentration of positive carriers (hole) as in 10(-4) M KCl. By controlling gate electric field effect on the mobility, the I-V curves obtained by the parameter modeling matched very well with the measured data. In addition, the decrease of [V(th)] with increasing V(DS) was physically analyzed. PMID:25958494

  13. Gyrokinetic particle simulation model

    SciTech Connect

    Lee, W.W.

    1986-07-01

    A new type of particle simulation model based on the gyrophase-averaged Vlasov and Poisson equations is presented. The reduced system, in which particle gyrations are removed from the equations of motion while the finite Larmor radius effects are still preserved, is most suitable for studying low frequency microinstabilities in magnetized plasmas. It is feasible to simulate an elongated system (L/sub parallel/ >> L/sub perpendicular/) with a three-dimensional grid using the present model without resorting to the usual mode expansion technique, since there is essentially no restriction on the size of ..delta..x/sub parallel/ in a gyrokinetic plasma. The new approach also enables us to further separate the time and spatial scales of the simulation from those associated with global transport through the use of multiple spatial scale expansion. Thus, the model can be a very efficient tool for studying anomalous transport problems related to steady-state drift-wave turbulence in magnetic confinement devices. It can also be applied to other areas of plasma physics.

  14. Synthetic 3D modeling of active regions and simulation of their multi-wavelength emission

    NASA Astrophysics Data System (ADS)

    Nita, Gelu M.; Fleishman, Gregory; Kuznetsov, Alexey A.; Loukitcheva, Maria A.; Viall, Nicholeen M.; Klimchuk, James A.; Gary, Dale E.

    2015-04-01

    To facilitate the study of solar active regions, we have created a synthetic modeling framework that combines 3D magnetic structures obtained from magnetic extrapolations with simplified 1D thermal models of the chromosphere, transition region, and corona. To handle, visualize, and use such synthetic data cubes to compute multi-wavelength emission maps and compare them with observations, we have undertaken a major enhancement of our simulation tools, GX_Simulator (ftp://sohoftp.nascom.nasa.gov/solarsoft/packages/gx_simulator/), developed earlier for modeling emission from flaring loops. The greatly enhanced, object-based architecture, which now runs on Windows, Mac, and UNIX platform, offers important new capabilities that include the ability to either import 3D density and temperature distribution models, or to assign to each individual voxel numerically defined coronal or chromospheric temperature and densities, or coronal Differential Emission Measure distributions. Due to these new capabilities, the GX_Simulator can now apply parametric heating models involving average properties of the magnetic field lines crossing a given voxel volume, as well as compute and investigate the spatial and spectral properties of radio (to be compared with VLA or EOVSA data), (sub-)millimeter (ALMA), EUV (AIA/SDO), and X-ray (RHESSI) emission calculated from the model. The application integrates shared-object libraries containing fast free-free, gyrosynchrotron, and gyroresonance emission codes developed in FORTRAN and C++, and soft and hard X-ray and EUV codes developed in IDL. We use this tool to model and analyze an active region and compare the synthetic emission maps obtained in different wavelengths with observations.This work was partially supported by NSF grants AGS-1250374, AGS-1262772, NASA grant NNX14AC87G, the Marie Curie International Research Staff Exchange Scheme "Radiosun" (PEOPLE-2011-IRSES-295272), RFBR grants 14-02-91157, 15-02-01089, 15-02-03717, 15

  15. A simulation technique for 3D MR-guided acoustic radiation force imaging

    PubMed Central

    Payne, Allison; de Bever, Josh; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-01-01

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation forc