Plasma environment of Titan: a 3-D hybrid simulation study
Directory of Open Access Journals (Sweden)
S. Simon
2006-05-01
Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.
CONEX and CORSIKA: a new 3D hybrid model for air shower simulation
International Nuclear Information System (INIS)
The hybrid air shower simulation code CONEX has been implemented as an option in the air shower Monte-Carlo model CORSIKA. In CONEX, Monte-Carlo simulation of high energy interactions is combined with a fast numerical solution of cascade equations. Low energy secondary particles can then be tracked within CORSIKA to obtain the lateral extension of the air shower. This allows the fast and realistic simulation of 3D showers at ultra-high energies.
2D-3D hybrid stabilized finite element method for tsunami runup simulations
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.
Mapping of coma anisotropies to plasma structures of weak comets: a 3-D hybrid simulation study
Directory of Open Access Journals (Sweden)
N. Gortsas
2009-04-01
Full Text Available The effects of coma anisotropies on the plasma environment of comets have been studied by means of a 3-D hybrid model which treats electrons as a massless, charge-neutralizing fluid, whereas ion dynamics are covered by a kinetic approach. From Earth-based observations as well as from in-situ spacecraft measurements the shape of the coma of many comets is ascertained to be anisotropic. However, most plasma simulation studies deploy a spherically symmetric activity pattern. In this paper anisotropy is studied by considering three different coma shape models. The first model is derived from the Haser model and is characterised by spherically symmetry. This reference model is then compared with two different neutral gas shape models: the dayside restricted model with no nightside activity and a cone shaped model with opening angle of π/2. In all models the integrated surface activity is kept constant. The simulations have been done for the Rosetta target comet 67P/Churyumov-Gerasimenko for two heliocentric distances, 1.30 AU and 3.25 AU. It is found that shock formation processes are modified as a result of increasing spatial confinement. Characteristic plasma structures of comets such as the bow shock, magnetic barrier region and the ion composition boundary exhibit a shift towards the sun. In addition, the cone shaped model leads to a strong increase of the mass-loaded region which in turn leads to a smooth deceleration of the solar wind flow and an increasing degree of mixture between the solar wind and cometary ion species. This creates an additional transport channel of the magnetic field from the magnetic barrier region away which in turn leads to a broadening of this region. In addition, it leads to an ion composition boundary which is only gradually developed.
Jovian Plasma Torus Interaction with Europa: 3D Hybrid Kinetic Simulation. First results
Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.; Sittler, E. C.; Hartle, R. E.; Simpson, D. G.
2010-01-01
The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa-moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo orbiter mission, and for planning flyby and orbital measurements, (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy etal.,2007;Shematovichetal.,2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyro radius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions).Non-thermal distributions of upstream plasma will be addressed in future work. Photoionization,electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider two models for background plasma:(a) with O(++) ions; (b) with O(++) and S(++) ions. The majority of O2 atmosphere is thermal with an extended cold population (Cassidyetal.,2007). A few first simulations already include an induced magnetic dipole; however, several important effects of induced magnetic fields arising from oceanic shell conductivity will be addressed in later work.
Plasma environment of magnetized asteroids: a 3-D hybrid simulation study
Directory of Open Access Journals (Sweden)
S. Simon
2006-03-01
Full Text Available The interaction of a magnetized asteroid with the solar wind is studied by using a three-dimensional hybrid simulation code (fluid electrons, kinetic ions. When the obstacle's intrinsic magnetic moment is sufficiently strong, the interaction region develops signs of magnetospheric structures. On the one hand, an area from which the solar wind is excluded forms downstream of the obstacle. On the other hand, the interaction region is surrounded by a boundary layer which indicates the presence of a bow shock. By analyzing the trajectories of individual ions, it is demonstrated that kinetic effects have global consequences for the structure of the interaction region.
Wiehle, S.; Plaschke, F.; Motschmann, U.; Glassmeier, K. H.; Auster, H. U.; Angelopoulos, V.; Mueller, J.; Kriegel, H.; Georgescu, E.; Halekas, J.; Sibeck, D. G.; McFadden, J. P.
2011-01-01
The spacecraft P1 of the new ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) mission passed the lunar wake for the first time on February 13, 2010. We present magnetic field and plasma data of this event and results of 3D hybrid simulations. As the solar wind magnetic field was highly dynamic during the passage, a simulation with stationary solar wind input cannot distinguish whether distortions were caused by these solar wind variations or by the lunar wake; therefore, a dynamic real-time simulation of the flyby has been performed. The input values of this simulation are taken from NASA OMNI data and adapted to the P1 data, resulting in a good agreement between simulation and measurements. Combined with the stationary simulation showing non-transient lunar wake structures, a separation of solar wind and wake effects is achieved. An anisotropy in the magnitude of the plasma bulk flow velocity caused by a non-vanishing magnetic field component parallel to the solar wind flow and perturbations created by counterstreaming ions in the lunar wake are observed in data and simulations. The simulations help to interpret the data granting us the opportunity to examine the entire lunar plasma environment and, thus, extending the possibilities of measurements alone: A comparison of a simulation cross section to theoretical predictions of MHD wave propagation shows that all three basic MHD modes are present in the lunar wake and that their expansion governs the lunar wake refilling process.
Energy Technology Data Exchange (ETDEWEB)
Flandrin, N.
2005-09-15
During the exploitation of an oil reservoir, it is important to predict the recovery of hydrocarbons and to optimize its production. A better comprehension of the physical phenomena requires to simulate 3D multiphase flows in increasingly complex geological structures. In this thesis, we are interested in this spatial discretization and we propose to extend in 3D the 2D hybrid model proposed by IFP in 1998 that allows to take directly into account in the geometry the radial characteristics of the flows. In these hybrid meshes, the wells and their drainage areas are described by structured radial circular meshes and the reservoirs are represented by structured meshes that can be a non uniform Cartesian grid or a Corner Point Geometry grids. In order to generate a global conforming mesh, unstructured transition meshes based on power diagrams and satisfying finite volume properties are used to connect the structured meshes together. Two methods have been implemented to generate these transition meshes: the first one is based on a Delaunay triangulation, the other one uses a frontal approach. Finally, some criteria are introduced to measure the quality of the transition meshes and optimization procedures are proposed to increase this quality under finite volume properties constraints. (author)
Reconstruction of 3-D digital cores using a hybrid method
Institute of Scientific and Technical Information of China (English)
Liu Xuefeng; Sun Jianmeng; Wang Haitao
2009-01-01
A 3-D digital core describes the pore space microstructure of rocks. An X-ray micro CT scan is the most accurate and direct but costly method to obtain a 3-D digital core. In this study, we propose a hybrid method which combines sedimentation simulation and simulated annealing (SA) method to generate 3-D digital cores based on 2-D images of rocks. The method starts with the sedimentation simulation to build a 3-D digital core, which is the initial configuration for the SA method. We update the initial digital core using the SA method to match the auto-correlation function of the 2-D rock image and eventually build the final 3-D digital core. Compared with the typical SA method, the hybrid method has significantly reduced the computation time. Local porosity theory is applied to quantitatively compare the reconstructed 3-D digital cores with the X-ray micro CT 3-D images. The results indicate that the 3-D digital cores reconstructed by the hybrid method have homogeneity and geometric connectivity similar to those of the X-ray micro CT image. The formation factors and permeabilities of the reconstructed 3-D digital cores are estimated using the finite element method (FEM) and lattice Boltzmann method (LBM), respectively. The simulated results are in good agreement with the experimental measurements. Comparison of the simulation results suggests that the digital cores reconstructed by the hybrid method more closely reflect the true transport properties than the typical SA method alone.
3-D Relativistic MHD Simulations
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.
Rudakov, Leonid; Mithaiwala, Manish; Ganguli, Gurudas
2012-01-01
Using electromagnetic particle-in-cell simulations Winske and Daughton [Phys Plasmas, 19, 072109, 2012] have recently demonstrated that the nonlinear evolution of a wave turbulence initiated by cold ion ring beam is vastly different in three dimensions than in two dimensions. We further analyze the Winske-Daughton three dimensional simulation data and show that the nonlinear induced scattering by thermal plasma particles is crucial for understanding the evolution of lower hybrid/whistler wave turbulence as described in the simulation.
Energy Technology Data Exchange (ETDEWEB)
Guildenbecher, Daniel R.; Gao, Jian; Reu, Phillip L.; Chen, Jun
2013-01-01
The accuracy of digital in-line holography to detect particle position and size within a 3D domain is evaluated with particular focus placed on detection of nonspherical particles. Dimensionless models are proposed for simulation of holograms from single particles, and these models are used to evaluate the uncertainty of existing particle detection methods. From the lessons learned, a new hybrid method is proposed. This method features automatic determination of optimum thresholds, and simulations indicate improved accuracy compared to alternative methods. To validate this, experiments are performed using quasi-stationary, 3D particle fields with imposed translations. For the spherical particles considered in experiments, the proposed hybrid method resolves mean particle concentration and size to within 4% of the actual value, while the standard deviation of particle depth is less than two particle diameters. Initial experimental results for nonspherical particles reveal similar performance.
Lipatov, A S; Paterson, W R; Sittler, E C; Hartle, R E; Simpson, D G
2012-01-01
The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect a to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream backgr...
Wang, Zhenyu; Lin, Yu; Wang, Xueyi; Tummel, Kurt; Chen, Liu
2016-07-01
The eigenmode stability properties of three-dimensional lower-hybrid-drift-instabilities (LHDI) in a Harris current sheet with a small but finite guide magnetic field have been systematically studied by employing the gyrokinetic electron and fully kinetic ion (GeFi) particle-in-cell (PIC) simulation model with a realistic ion-to-electron mass ratio mi/me . In contrast to the fully kinetic PIC simulation scheme, the fast electron cyclotron motion and plasma oscillations are systematically removed in the GeFi model, and hence one can employ the realistic mi/me . The GeFi simulations are benchmarked against and show excellent agreement with both the fully kinetic PIC simulation and the analytical eigenmode theory. Our studies indicate that, for small wavenumbers, ky, along the current direction, the most unstable eigenmodes are peaked at the location where k →.B → =0 , consistent with previous analytical and simulation studies. Here, B → is the equilibrium magnetic field and k → is the wavevector perpendicular to the nonuniformity direction. As ky increases, however, the most unstable eigenmodes are found to be peaked at k →.B → ≠0 . In addition, the simulation results indicate that varying mi/me , the current sheet width, and the guide magnetic field can affect the stability of LHDI. Simulations with the varying mass ratio confirm the lower hybrid frequency and wave number scalings.
A 3D Hybrid Integration Methodology for Terabit Transceivers
DEFF Research Database (Denmark)
Dong, Yunfeng; Johansen, Tom Keinicke; Zhurbenko, Vitaliy;
2015-01-01
This paper presents a three-dimensional (3D) hybrid integration methodology for terabit transceivers. The simulation methodology for multi-conductor structures are explained. The effect of ground vias on the RF circuitry and the preferred interposer substrate material for large bandwidth 3D hybrid...... integration are described. An equivalent circuit model of the via-throughs connecting the RF circuitry to the modulator is proposed and its lumped element parameters are extracted. Wire bonding transitions between the driving and RF circuitry were designed and simulated. An optimized 3D interposer design...... demonstrated a simulated -3 dB transmission bandwidth up to 95 GHz with associated return loss better than 10 dB. A thermal analysis of a subassembly for the packaged transmitter module is performed. A maximum temperature of 74 °C is predicted when copper-tungsten is used as the material of the sub...
3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows
Institute of Scientific and Technical Information of China (English)
Jie ZHOU; Cheng ZENG
2009-01-01
The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage.To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows,a hybrid LES-RANS model,which combines the large eddy simulation (LES) model with the Reynolds-averaged Navier-Stokes (RANS) model,is proposed in the present study.The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel,as well as the downstream region of a branch channel.The LES model was used to simulate the channel diversion region,where turbulent flow characteristics ate complicated.Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence.A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations.This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions.Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows.
3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows
Directory of Open Access Journals (Sweden)
Jie ZHOU
2009-09-01
Full Text Available The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage. To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows, a hybrid LES-RANS model, which combines the large eddy simulation (LES model with the Reynolds-averaged Navier-Stokes (RANS model, is proposed in the present study. The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel, as well as the downstream region of a branch channel. The LES model was used to simulate the channel diversion region, where turbulent flow characteristics are complicated. Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence. A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations. This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions. Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows.
Real-time 3-D hybrid simulation of Titan's plasma interaction during a solar wind excursion
Directory of Open Access Journals (Sweden)
S. Simon
2009-09-01
Full Text Available The plasma environment of Saturn's largest satellite Titan is known to be highly variable. Since Titan's orbit is located within the outer magnetosphere of Saturn, the moon can leave the region dominated by the magnetic field of its parent body in times of high solar wind dynamic pressure and interact with the thermalized magnetosheath plasma or even with the unshocked solar wind. By applying a three-dimensional hybrid simulation code (kinetic description of ions, fluid electrons, we study in real-time the transition that Titan's plasma environment undergoes when the moon leaves Saturn's magnetosphere and enters the supermagnetosonic solar wind. In the simulation, the transition between both plasma regimes is mimicked by a reversal of the magnetic field direction as well as a change in the composition and temperature of the impinging plasma flow. When the satellite enters the solar wind, the magnetic draping pattern in its vicinity is reconfigured due to reconnection, with the characteristic time scale of this process being determined by the convection of the field lines in the undisturbed plasma flow at the flanks of the interaction region. The build-up of a bow shock ahead of Titan takes place on a typical time scale of a few minutes as well. We also analyze the erosion of the newly formed shock front upstream of Titan that commences when the moon re-enters the submagnetosonic plasma regime of Saturn's magnetosphere. Although the model presented here is far from governing the full complexity of Titan's plasma interaction during a solar wind excursion, the simulation provides important insights into general plasma-physical processes associated with such a disruptive change of the upstream flow conditions.
Plasma and fields in the wake of Rhea: 3-D hybrid simulation and comparison with Cassini data
Directory of Open Access Journals (Sweden)
E. Roussos
2008-03-01
Full Text Available Rhea's magnetospheric interaction is simulated using a three-dimensional, hybrid plasma simulation code, where ions are treated as particles and electrons as a massless, charge-neutralizing fluid. In consistency with Cassini observations, Rhea is modeled as a plasma absorbing obstacle. This leads to the formation of a plasma wake (cavity behind the moon. We find that this cavity expands with the ion sound speed along the magnetic field lines, resulting in an extended depletion region north and south of the moon, just a few Rhea radii (R_{Rh} downstream. This is a direct consequence of the comparable thermal and bulk plasma velocities at Rhea. Perpendicular to the magnetic field lines the wake's extension is constrained by the magnetic field. A magnetic field compression in the wake and the rarefaction in the wake sides is also observed in our results. This configuration reproduces well the signature in the Cassini magnetometer data, acquired during the close flyby to Rhea on November 2005. Almost all plasma and field parameters show an asymmetric distribution along the plane where the corotational electric field is contained. A diamagnetic current system is found running parallel to the wake boundaries. The presence of this current system shows a direct corelation with the magnetic field configuration downstream of Rhea, while the resulting j×B forces on the ions are responsible for the asymmetric structures seen in the velocity and electric field vector fields in the equatorial plane. As Rhea is one of the many plasma absorbing moons of Saturn, we expect that this case study should be relevant for most lunar-type interactions at Saturn.
Hazenberg, P.; Broxton, P. D.; Brunke, M.; Gochis, D.; Niu, G. Y.; Pelletier, J. D.; Troch, P. A. A.; Zeng, X.
2015-12-01
The terrestrial hydrological system, including surface and subsurface water, is an essential component of the Earth's climate system. Over the past few decades, land surface modelers have built one-dimensional (1D) models resolving the vertical flow of water through the soil column for use in Earth system models (ESMs). These models generally have a relatively coarse model grid size (~25-100 km) and only account for sub-grid lateral hydrological variations using simple parameterization schemes. At the same time, hydrologists have developed detailed high-resolution (~0.1-10 km grid size) three dimensional (3D) models and showed the importance of accounting for the vertical and lateral redistribution of surface and subsurface water on soil moisture, the surface energy balance and ecosystem dynamics on these smaller scales. However, computational constraints have limited the implementation of the high-resolution models for continental and global scale applications. The current work presents a hybrid-3D hydrological approach is presented, where the 1D vertical soil column model (available in many ESMs) is coupled with a high-resolution lateral flow model (h2D) to simulate subsurface flow and overland flow. H2D accounts for both local-scale hillslope and regional-scale unconfined aquifer responses (i.e. riparian zone and wetlands). This approach was shown to give comparable results as those obtained by an explicit 3D Richards model for the subsurface, but improves runtime efficiency considerably. The h3D approach is implemented for the Delaware river basin, where Noah-MP land surface model (LSM) is used to calculated vertical energy and water exchanges with the atmosphere using a 10km grid resolution. Noah-MP was coupled within the WRF-Hydro infrastructure with the lateral 1km grid resolution h2D model, for which the average depth-to-bedrock, hillslope width function and soil parameters were estimated from digital datasets. The ability of this h3D approach to simulate
3D-FPA Hybridization Improvements Project
National Aeronautics and Space Administration — Advanced Scientific Concepts, Inc. (ASC) is a small business, which has developed a compact, eye-safe 3D Flash LIDARTM Camera (FLC) well suited for real-time...
INCORPORATING DYNAMIC 3D SIMULATION INTO PRA
Energy Technology Data Exchange (ETDEWEB)
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
3D FDTD simulations of photonic devices
International Nuclear Information System (INIS)
Full text: In our contribution we will present the recent results on 3D simulations of photonic devices. Particularly, quantum well infrared photodetectors with embedded photonic crystal are optimized to achieve optimal light coupling and quantum efficiency. Furthermore, we study schemes of light coupling into SOI waveguides. Both optical fibre-SOI waveguide and laser-SOI waveguide coupling schemes are investigated. The results of investigations regarding the influence of disorder on the reflection peak in opal 3D photonic crystal will be also presented. This work was supported by the Austrian Nanoinitiative RPC PLATON. (author)
Numerical Simulation of 3-D Wave Crests
Institute of Scientific and Technical Information of China (English)
YU Dingyong; ZHANG Hanyuan
2003-01-01
A clear definition of 3-D wave crest and a description of the procedures to detect the boundary of wave crest are presented in the paper. By using random wave theory and directional wave spectrum, a MATLAB-platformed program is designed to simulate random wave crests for various directional spectral conditions in deep water. Statistics of wave crests with different directional spreading parameters and different directional functions are obtained and discussed.
DRACO development for 3D simulations
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.
3D integrated hybrid silicon laser.
Song, Bowen; Stagarescu, Cristian; Ristic, Sasa; Behfar, Alex; Klamkin, Jonathan
2016-05-16
Lasers were realized on silicon by flip-chip bonding of indium phosphide (InP) devices containing total internal reflection turning mirrors for surface emission. Light is coupled to the silicon waveguides through surface grating couplers. With this technique, InP lasers were integrated on silicon. Laser cavities were also formed by coupling InP reflective semiconductor optical amplifiers to microring resonator filters and distributed Bragg reflector mirrors. Single-mode continuous wave lasing was demonstrated with a side mode suppression ratio of 30 dB. Up to 2 mW of optical power was coupled to the silicon waveguide. Thermal simulations were also performed to evaluate the low thermal impedance afforded by this architecture and potential for high wall-plug efficiency. PMID:27409867
Huang, L. C. P.; Cook, R. A.
1973-01-01
Models utilizing various sub-sets of the six degrees of freedom are used in trajectory simulation. A 3-D model with only linear degrees of freedom is especially attractive, since the coefficients for the angular degrees of freedom are the most difficult to determine and the angular equations are the most time consuming for the computer to evaluate. A computer program is developed that uses three separate subsections to predict trajectories. A launch rail subsection is used until the rocket has left its launcher. The program then switches to a special 3-D section which computes motions in two linear and one angular degrees of freedom. When the rocket trims out, the program switches to the standard, three linear degrees of freedom model.
Radiative Transfer in 3D Numerical Simulations
Stein, R; Stein, Robert; Nordlund, Aake
2002-01-01
We simulate convection near the solar surface, where the continuum optical depth is of order unity. Hence, to determine the radiative heating and cooling in the energy conservation equation, we must solve the radiative transfer equation (instead of using the diffusion or optically thin cooling approximations). A method efficient enough to calculate the radiation for thousands of time steps is needed. We assume LTE and a non-gray opacity grouped into 4 bins according to strength. We perform a formal solution of the Feautrier equation along a vertical and four straight, slanted, rays (at four azimuthal angles which are rotated 15 deg. every time step). We present details of our method. We also give some results: comparing simulated and observed line profiles for the Sun, showing the importance of 3D transfer for the structure of the mean atmosphere and the eigenfrequencies of p-modes, illustrating Stokes profiles for micropores, and analyzing the effect of radiation on p-mode asymmetries.
A Hybrid 3D Path Planning Method for UAVs
DEFF Research Database (Denmark)
Ortiz-Arroyo, Daniel
2015-01-01
This paper presents a hybrid method for path planning in 3D spaces. We propose an improvement to a near-optimal 2D off-line algorithm and a ﬂexible normalized on-line fuzzy controller to ﬁnd shortest paths. Our method, targeted to low altitude domains, is simple and efﬁcient. Our preliminary resu...
Direct numerical simulation of 3D transitional fluid flows
International Nuclear Information System (INIS)
Full text: For the numerical simulation of the 2D-3D transitional homogeneous and stratified incompressible viscous fluid flows, characterizing by the full Navier-Stokes equations, the splitting on physical factors method is used. The explicit hybrid finite difference scheme of the method has the following behaviors: the second order of accuracy in space, minimum scheme viscosity and dispersion, workable in wide range of Reynolds and Froude numbers and monotonicity. The efficiency of the developed numerical method and the advanced performance of the supercomputers allowed simulating 2D-3D transitional uncompressible viscous fluid flows around the bluff bodies in particular around a cylinder. By the numerical simulation of the fluid flows around 3D circular cylinder it was found that the transition to 3D regime arrives at Re>200. At 200< Re<300 the mode A with wavelength 3.5 d<λ<4.0 d (where d is the diameter of the cylinder) for 3D structures along the axis of a cylinder was observed. At 300< Re<400 the mode B with wavelength 0.8 d<λ<0.9 d was observed. At Re=300 the both modes A and B were observed simultaneously. The regime with large dislocations previously discovered experimentally was first obtained numerically at 210< Re<260. This regime is characterized by flow phase dislocation along the axis of the cylinder and as the effect by the amplitude fall of the lift force coefficient and the variations in the drag coefficient. There was simulated numerically the initiation of the attached internal waves behind the circular cylinder and upstream disturbance area at low Froude and moderate Reynolds numbers. (author)
3D simulation studies of tokamak plasmas using MHD and extended-MHD models
International Nuclear Information System (INIS)
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-β disruption studies in reversed shear plasmas using the MHD level MH3D code, ω*i stabilization and nonlinear island saturation of TAE mode using the hybrid particle/MHD level MH3D-K code, and unstructured mesh MH3D++ code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree which agree well with experimental data
Simulation of AIMS measurements using rigorous mask 3D modeling
Chou, Chih-Shiang; Huang, Hsu-Ting; Chu, Fu-Sheng; Chu, Yuan-Chih; Huang, Wen-Chun; Liu, Ru-Gun; Gau, Tsai-Sheng
2015-03-01
Aerial image measurement system (AIMSTM) has been widely used for wafer level inspection of mask defects. Reported inspection flows include die-to-die (D2D) and die-to-database (D2DB) methods. For patterns that do not repeat in another die, only the D2DB approach is applicable. The D2DB method requires accurate simulation of AIMS measurements for a mask pattern. An optical vectorial model is needed to depict the mask diffraction effect in this simulation. To accurately simulate the imaging results, a rigorous electro-magnetic field (EMF) model is essential to correctly take account of the EMF scattering induced by the mask topography, which is usually called the mask 3D effect. In this study, the mask 3D model we use is rigorous coupled-wave analysis (RCWA), which calculates the diffraction fields from a single plane wave incidence. A hybrid Hopkins-Abbe method with RCWA is used to calculate the EMF diffraction at a desired accuracy level while keeping the computation time practical. We will compare the speed of the hybrid Hopkins-Abbe method to the rigorous Abbe method. The matching between simulation and experiment is more challenging for AIMS than CD-SEM because its measurements provide full intensity information. Parameters in the mask 3D model such as film stack thickness or film optical properties, is optimized during the fitting process. We will report the fitting results of AIMS images for twodimensional structures with various pitches. By accurately simulating the AIMS measurements, it provides a necessary tool to perform the mask inspection using the D2DB approach and to accurately predict the mask defects.
Hybrid segmentation framework for 3D medical image analysis
Chen, Ting; Metaxas, Dimitri N.
2003-05-01
Medical image segmentation is the process that defines the region of interest in the image volume. Classical segmentation methods such as region-based methods and boundary-based methods cannot make full use of the information provided by the image. In this paper we proposed a general hybrid framework for 3D medical image segmentation purposes. In our approach we combine the Gibbs Prior model, and the deformable model. First, Gibbs Prior models are applied onto each slice in a 3D medical image volume and the segmentation results are combined to a 3D binary masks of the object. Then we create a deformable mesh based on this 3D binary mask. The deformable model will be lead to the edge features in the volume with the help of image derived external forces. The deformable model segmentation result can be used to update the parameters for Gibbs Prior models. These methods will then work recursively to reach a global segmentation solution. The hybrid segmentation framework has been applied to images with the objective of lung, heart, colon, jaw, tumor, and brain. The experimental data includes MRI (T1, T2, PD), CT, X-ray, Ultra-Sound images. High quality results are achieved with relatively efficient time cost. We also did validation work using expert manual segmentation as the ground truth. The result shows that the hybrid segmentation may have further clinical use.
International Nuclear Information System (INIS)
The real-time hybrid reactor simulation (HRS) capability of the Penn State TRIGA reactor has been recently expanded for BWR out-of-phase behavior. Out-of-phase oscillation is a phenomenon that occurs at BWRs. During this kind of event, 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. The HRS will be used for development and validation of stability monitoring and control techniques as part of an ongoing U.S. Department of Energy Nuclear Engineering Education and Research grant. The Penn State TRIGA reactor is used to simulate BWR fundamental mode power dynamics. The first harmonic mode power, together with detailed thermal hydraulics of boiling channels of both fundamental mode and first harmonic mode, is simulated digitally in real time with a computer. Simulations of boiling channels provide reactivity feedback to the TRIGA reactor, and the TRIGA reactor's power response is in turn fed into the channel simulations and the first harmonic mode power simulation. The combination of reactor power response and the simulated first harmonic power response with spatial distribution functions thus mimics the stability phenomena actually encountered in BWRs. The digital simulations of the boiling channels are performed by solving conservation equations for different regions in the channel with C-MEX S-functions. A fast three-dimensional (3-D) reactor power display of modal BWR power distribution was implemented using MATLAB graphics capability. Fundamental mode, first harmonic, together with the total power distribution over the reactor cross section, are displayed. Because of the large amount of computation for BWR boiling channel simulation and real-time data processing and graph generation, one computer is not sufficient to handle these jobs in the hybrid reactor simulation environment. A new three-computer setup has been
3D simulations of device performance for 3D-Trench electrode detector
Energy Technology Data Exchange (ETDEWEB)
Chen, Jianwei; Ding, Hao [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Center for Semiconductor Particle and photon Imaging Detector, Development and Fabrication, Xiangtan University, Xiangtan 411105 (China); Li, Zheng, E-mail: zhengli58@gmail.com [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Center for Semiconductor Particle and photon Imaging Detector, Development and Fabrication, Xiangtan University, Xiangtan 411105 (China); Yan, Shaoan [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Center for Semiconductor Particle and photon Imaging Detector, Development and Fabrication, Xiangtan University, Xiangtan 411105 (China)
2015-10-01
A square 3D-Trench electrode Si detector structure is simulated using a 3D TCAD tool. Electrical characteristics including electrostatic potential, electric field, leakage current, and capacitance have been simulated in detail. It has been found in simulations that both leakage current and the voltage to reach the geometry capacitance (full depletion voltage, V{sub fd}) increase with radiation fluence. The geometry capacitance is 99 fF for the standard structure in our study. Detector geometry capacitance's dependence on the length and area of the collection column has also been simulated.
3D electronics for hybrid pixel detectors – TWEPP-09
Godiot, S; Chantepie, B; Clémens, J C; Fei, R; Fleury, J; Fougeron, D; Garcia-Sciveres, M; Hemperek, T; Karagounis, M; Krueger, H; Mekkaoui, A; Pangaud, P; Rozanov, A; Wermes, N
2009-01-01
Future hybrid pixel detectors are asking for smaller pixels in order to improve spatial resolution and to deal with an increasing counting rate. Facing these requirements is foreseen to be done by microelectronics technology shrinking. However, this straightforward approach presents some disadvantages in term of performances and cost. New 3D technologies offer an alternative way with the advantage of technology mixing. For the upgrade of ATLAS pixel detector, a 3D conception of the read-out chip appeared as an interesting solution. Splitting the pixel functionalities into two separate levels will reduce pixel size and open the opportunity to take benefit of technology's mixing. Based on a previous prototype of the read-out chip FE-I4 (IBM 130nm), this paper presents the design of a hybrid pixel read-out chip using threedimensional Tezzaron-Chartered technology. In order to disentangle effects due to Chartered 130nm technology from effects involved by 3D architecture, a first translation of FEI4 prototype had ...
3D Convection-pulsation Simulations with the HERACLES Code
Felix, S.; Audit, E.; Dintrans, B.
2015-10-01
We present 3D simulations of the coupling between surface convection and pulsations due to the κ-mechanism in classical Cepheids of the red edge of Hertzsprung-Russell diagram's instability strip. We show that 3D convection is less powerful than 2D convection and does not quench the radiative pulsations, leading to an efficient 3D κ-mechanism. Thus, the 3D instability strip is closer to the observed one than the 1D or 2D were.
Investigation of a Hybrid Winding Concept for Toroidal Inductors using 3D Finite Element Modeling
DEFF Research Database (Denmark)
Schneider, Henrik; Andersen, Thomas; Mønster, Jakob Døllner;
2013-01-01
This paper investigates a hybrid winding concept for a toroidal inductor by simulating the winding resistance as a function of frequency. The problem of predicting the resistance of a non-uniform and complex winding shape is solved using 3D Finite Element Modeling. A prototype is built and tested...
Charge collection characterization of a 3D silicon radiation detector by using 3D simulations
Kalliopuska, J; Orava, R
2007-01-01
In 3D detectors, the electrodes are processed within the bulk of the sensor material. Therefore, the signal charge is collected independently of the wafer thickness and the collection process is faster due to shorter distances between the charge collection electrodes as compared to a planar detector structure. In this paper, 3D simulations are used to assess the performance of a 3D detector structure in terms of charge sharing, efficiency and speed of charge collection, surface charge, location of the primary interaction and the bias voltage. The measured current pulse is proposed to be delayed due to the resistance–capacitance (RC) product induced by the variation of the serial resistance of the pixel electrode depending on the depth of the primary interaction. Extensive simulations are carried out to characterize the 3D detector structures and to verify the proposed explanation for the delay of the current pulse. A method for testing the hypothesis experimentally is suggested.
2D/3D Monte Carlo Feature Profile Simulator FPS-3D
Moroz, Paul
2010-11-01
Numerical simulation of etching/deposition profiles is important for semiconductor industry, as it allows analysis and prediction of the outcome of materials processing on a micron and sub-micron scale. The difficulty, however, is in making such a simulator a reliable, general, and easy to use tool applicable to different situations, for example, with different ratios of ion to neutral fluxes, different chemistries, different energies of incoming particles, and different angular and energy dependencies for surface reactions, without recompiling the code each time when the parameters change. The FPS-3D simulator [1] does not need recompilation when the features, materials, gases, or plasma are changed -- modifications to input, chemistry, and flux files are enough. The code allows interaction of neutral low-energy species with the surface mono-layer, while considering finite penetration depth into the volume for fast particles and ions. The FPS-3D code can simulate etching and deposition processes, both for 2D and 3D geometries. FPS-3D is using an advanced graphics package from HFS for presenting real-time process and profile evolution. The presentation will discuss the FPS-3D code with examples for different process conditions. The author is thankful to Drs. S.-Y. Kang of TEL TDC and P. Miller of HFS for valuable discussions. [4pt] [1] P. Moroz, URP.00101, GEC, Saratoga, NY, 2009.
3D visualization of port simulation.
Energy Technology Data Exchange (ETDEWEB)
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
3D simulation studies of tokamak plasmas using MHD and extended-MHD models
International Nuclear Information System (INIS)
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-β disruption studies in reversed shear plasmas using the MHD level MH3D code, ω*i stabilization and nonlinear island rotation studies using the two-fluid level MH3D-T code, studies of nonlinear saturation of TAE modes using the hybrid particle/MHD level MH3D-K code, and unstructured mesh MH3D++ code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree well with experimental data
Surviving sepsis--a 3D integrative educational simulator.
Ježek, Filip; Tribula, Martin; Kulhánek, Tomáš; Mateják, Marek; Privitzer, Pavol; Šilar, Jan; Kofránek, Jiří; Lhotská, Lenka
2015-08-01
Computer technology offers greater educational possibilities, notably simulation and virtual reality. This paper presents a technology which serves to integrate multiple modalities, namely 3D virtual reality, node-based simulator, Physiomodel explorer and explanatory physiological simulators employing Modelica language and Unity3D platform. This emerging tool chain should allow the authors to concentrate more on educational content instead of application development. The technology is demonstrated through Surviving sepsis educational scenario, targeted on Microsoft Windows Store platform. PMID:26737091
3D MHD Simulations of Spheromak Compression
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.
Hybrid additive manufacturing of 3D electronic systems
Li, J.; Wasley, T.; Nguyen, T. T.; Ta, V. D.; Shephard, J. D.; Stringer, J.; Smith, P.; Esenturk, E.; Connaughton, C.; Kay, R.
2016-10-01
A novel hybrid additive manufacturing (AM) technology combining digital light projection (DLP) stereolithography (SL) with 3D micro-dispensing alongside conventional surface mount packaging is presented in this work. This technology overcomes the inherent limitations of individual AM processes and integrates seamlessly with conventional packaging processes to enable the deposition of multiple materials. This facilitates the creation of bespoke end-use products with complex 3D geometry and multi-layer embedded electronic systems. Through a combination of four-point probe measurement and non-contact focus variation microscopy, it was identified that there was no obvious adverse effect of DLP SL embedding process on the electrical conductivity of printed conductors. The resistivity maintained to be less than 4 × 10-4 Ω · cm before and after DLP SL embedding when cured at 100 °C for 1 h. The mechanical strength of SL specimens with thick polymerized layers was also identified through tensile testing. It was found that the polymerization thickness should be minimised (less than 2 mm) to maximise the bonding strength. As a demonstrator a polymer pyramid with embedded triple-layer 555 LED blinking circuitry was successfully fabricated to prove the technical viability.
Simulations on 3D shape tracking with fibre Bragg gratings
Hooft 't, G.W.; Tirard-Gâtel, A.
2010-01-01
This report deals with the development of a reconstruction algorithm of 3D optical shape sensing. The theoretical frame work is established and simulations are performed for a multicore fiber system without torque.
Design of 3D simulation engine for oilfield safety training
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.
An Evaluative Review of Simulated Dynamic Smart 3d Objects
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.
Fatigue of hybrid glass/carbon composites: 3D computational studies
DEFF Research Database (Denmark)
Dai, Gaoming; Mishnaevsky, Leon
2014-01-01
3D computational simulations of fatigue of hybrid carbon/glass fiber reinforced composites is carried out using X-FEM and multifiber unit cell models. A new software code for the automatic generation of unit cell multifiber models of composites with randomly misaligned fibers of various properties...... cyclic loading effects) on fatigue behavior of the materials are carried out. It was demonstrated that the higher fraction of carbon fibers in hybrid composites is beneficial for the fatigue lifetime of the composites under tension-tension cyclic loading, but might have negative effect on the lifetime...
3D Ultrasonic Wave Simulations for Structural Health Monitoring
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.
Statistical 3D damage accumulation model for ion implant simulators
Hernandez-Mangas, J M; Enriquez, L E; Bailon, L; Barbolla, J; Jaraiz, M
2003-01-01
A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided.
Testing the hybrid-3D Hillslope Hydrological Model in a Real-World Controlled Environment
Hazenberg, P.; Broxton, P. D.; Gochis, D. J.; Niu, G. Y.; Pelletier, J. D.; Troch, P. A. A.; Zeng, X.
2015-12-01
Hillslopes play an important role for converting rainfall into runoff, and as such, influence theterrestrial dynamics of the Earth's climate system. Recently, we have developed a hybrid-3D (h3D) hillslope hydrological model that couples a 1D vertical soil column model with a lateral pseudo-2D saturated zone and overland flow model. The h3D model gives similar results as the CATchment HYdrological model (CATHY), which simulates the subsurface movement of water with the 3D Richards equation, though the runtime efficiency of the h3D model is about 2-3 orders of magnitude faster. In the current work, the ability of the h3D model to predict real-world hydrological dynamics is assessed using a number of recharge-drainage experiments within the Landscape Evolution Observatory (LEO) at the Biosphere 2 near Tucson, Arizona, USA. LEO offers accurate and high-resolution (both temporally and spatially) observations of the inputs, outputs and storage dynamics of several hillslopes. The level of detail of these observations is generally not possible with real-world hillslope studies. Therefore, LEO offers an optimal environment to test the h3D model. The h3D model captures the observed storage, baseflow, and overland flow dynamics of both a larger and a smaller hillslope. Furthermore, it simulates overland flow better than CATHY. The h3D model has difficulties correctly representing the height of the saturated zone close to the seepage face of the smaller hillslope, though. There is a gravel layer near this seepage face, and the numerical boundary condition of the h3D model is insufficient to capture the hydrological dynamics within this region. In addition, the h3D model is used to test the hypothesis that model parameters change through time due to the migration of soil particles during the recharge-drainage experiments. An in depth calibration of the h3D model parameters reveals that the best results are obtained by applying an event-based optimization procedure as compared
Čillo, Vladimír
2015-01-01
Tato bakalářská práce se zabýva návrhem a implementací simulátoru 3D tiskárny v jazyce C++ s využitím knihovny Qt. Simulátor předpokládá tiskárnu založenou na nejrozšířenější metodě 3D tisku - Fused Deposition Modeling. Vstupem simulátoru je 3D model ve formátu STL. Pro daný 3D model simulátor poskytuje odhad celkové doby tisku. Součástí simulace je také vizualizace procesu 3D tisku. Výsledkem práce je přenositelný program testovaný pod operačními systémy Linux a Windows. Funkčnost simulátoru...
Sharkawi, K.-H.; Abdul-Rahman, A.
2013-09-01
to LoD4. The accuracy and structural complexity of the 3D objects increases with the LoD level where LoD0 is the simplest LoD (2.5D; Digital Terrain Model (DTM) + building or roof print) while LoD4 is the most complex LoD (architectural details with interior structures). Semantic information is one of the main components in CityGML and 3D City Models, and provides important information for any analyses. However, more often than not, the semantic information is not available for the 3D city model due to the unstandardized modelling process. One of the examples is where a building is normally generated as one object (without specific feature layers such as Roof, Ground floor, Level 1, Level 2, Block A, Block B, etc). This research attempts to develop a method to improve the semantic data updating process by segmenting the 3D building into simpler parts which will make it easier for the users to select and update the semantic information. The methodology is implemented for 3D buildings in LoD2 where the buildings are generated without architectural details but with distinct roof structures. This paper also introduces hybrid semantic-geometric 3D segmentation method that deals with hierarchical segmentation of a 3D building based on its semantic value and surface characteristics, fitted by one of the predefined primitives. For future work, the segmentation method will be implemented as part of the change detection module that can detect any changes on the 3D buildings, store and retrieve semantic information of the changed structure, automatically updates the 3D models and visualize the results in a userfriendly graphical user interface (GUI).
3D Simulations of line emission from ICF capsules
International Nuclear Information System (INIS)
Line emission from ICF implosions can be used to diagnose the temperature of the DT fuel and provides an indication of the distortion in the fuel-pusher interface. 2D simulations have provided valuable insights into the usefulness of argon and titanium dopants as diagnostics of instabilities. Characterizing the effects of drive asymmetries requires 3D modeling with large demands for computer time and memory, necessitating the use of parallel computers. We present the results of some 3D simulations achieved with a code utilizing both shared memory and distributed parallelism. We discuss the code structure and related performance issues
3D Fiber Orientation Simulation for Plastic Injection Molding
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.
3D Simulation of Nano-Imprint Lithography
DEFF Research Database (Denmark)
Román Marín, José Manuel; Rasmussen, Henrik K.; Hassager, Ole
2010-01-01
A proof of concept study of the feasibility of fully three-dimensional (3D) time-dependent simulation of nano-imprint lithography of polymer melt, where the polymer is treated as a structured liquid, has been presented. Considering the flow physics of the polymer as a structured liquid, we have...
3D Visualization and Simulation of the Human Navigation System
Hjelle, Henrik
2015-01-01
The aim of this thesis is to investigate how 3D visualizations and virtual reality can be used to make the human navigation system understandable for the general public. To do this, a 3D visualization of the human navigation systems components in the brain was created using Second Life. In addition, a simulation of how the cells in this system works was created with the same platform. These two types of visualization were used to see if they gave any learning outcome in relation to the ...
3D simulation of CANDU reactor regulating system
International Nuclear Information System (INIS)
Present paper shows the evaluation of the performance of the 3-D modal synthesis based reactor kinetic model in a closed-loop environment in a MATLAB/SIMULINK based Reactor Regulating System (RRS) simulation platform. A notable advantage of the 3-D model is the level of details that it can reveal as compared to the coupled point kinetic model. Using the developed RRS simulation platform, the reactor internal behaviours can be revealed during load-following tests. The test results are also benchmarked against measurements from an existing (CANDU) power plant. It can be concluded that the 3-D reactor model produces more realistic view of the core neutron flux distribution, which is closer to the real plant measurements than that from a coupled point kinetic model. It is also shown that, through a vectorization process, the computational load of the 3-D model is comparable with that of the 14-zone coupled point kinetic model. Furthermore, the developed Graphical User Interface (GUI) software package for RRS implementation represents a user friendly and independent application environment for education training and industrial utilizations. (authors)
A FLOSS Visual EM Simulator for 3D Antennas
Koutsos, Christos A; Zimourtopoulos, Petros E
2010-01-01
This paper introduces the FLOSS Free Libre Open Source Software [VEMSA3D], a contraction of "Visual Electromagnetic Simulator for 3D Antennas", which are geometrically modeled, either exactly or approximately, as thin wire polygonal structures; presents its GUI Graphical User Interface capabilities, in interactive mode and/or in handling suitable formed antenna data files; demonstrates the effectiveness of its use in a number of practical antenna applications, with direct comparison to experimental measurements and other freeware results; and provides the inexperienced user with a specific list of instructions to successfully build the given source code by using only freely available IDE Integrated Development Environment tools-including a cross-platform one. The unrestricted access to source code, beyond the ability for immediate software improvement, offers to independent users and volunteer groups an expandable, in any way, visual antenna simulator, for a genuine research and development work in the field ...
Comparative visual analysis of 3D urban wind simulations
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.
Junk, S.
2016-08-01
Today the methods of numerical simulation of sheet metal forming offer a great diversity of possibilities for optimization in product development and in process design. However, the results from simulation are only available as virtual models. Because there are any forming tools available during the early stages of product development, physical models that could serve to represent the virtual results are therefore lacking. Physical 3D-models can be created using 3D-printing and serve as an illustration and present a better understanding of the simulation results. In this way, the results from the simulation can be made more “comprehensible” within a development team. This paper presents the possibilities of 3D-colour printing with particular consideration of the requirements regarding the implementation of sheet metal forming simulation. Using concrete examples of sheet metal forming, the manufacturing of 3D colour models will be expounded upon on the basis of simulation results.
Hybrid 3D printing: a game-changer in personalized cardiac medicine?
Kurup, Harikrishnan K N; Samuel, Bennett P; Vettukattil, Joseph J
2015-12-01
Three-dimensional (3D) printing in congenital heart disease has the potential to increase procedural efficiency and patient safety by improving interventional and surgical planning and reducing radiation exposure. Cardiac magnetic resonance imaging and computed tomography are usually the source datasets to derive 3D printing. More recently, 3D echocardiography has been demonstrated to derive 3D-printed models. The integration of multiple imaging modalities for hybrid 3D printing has also been shown to create accurate printed heart models, which may prove to be beneficial for interventional cardiologists, cardiothoracic surgeons, and as an educational tool. Further advancements in the integration of different imaging modalities into a single platform for hybrid 3D printing and virtual 3D models will drive the future of personalized cardiac medicine. PMID:26465262
Hybrid 3D printing: a game-changer in personalized cardiac medicine?
Kurup, Harikrishnan K N; Samuel, Bennett P; Vettukattil, Joseph J
2015-12-01
Three-dimensional (3D) printing in congenital heart disease has the potential to increase procedural efficiency and patient safety by improving interventional and surgical planning and reducing radiation exposure. Cardiac magnetic resonance imaging and computed tomography are usually the source datasets to derive 3D printing. More recently, 3D echocardiography has been demonstrated to derive 3D-printed models. The integration of multiple imaging modalities for hybrid 3D printing has also been shown to create accurate printed heart models, which may prove to be beneficial for interventional cardiologists, cardiothoracic surgeons, and as an educational tool. Further advancements in the integration of different imaging modalities into a single platform for hybrid 3D printing and virtual 3D models will drive the future of personalized cardiac medicine.
Simulation of human ischemic stroke in realistic 3D geometry
Dumont, Thierry; Duarte, Max; Descombes, Stéphane; Dronne, Marie-Aimée; Massot, Marc; Louvet, Violaine
2013-06-01
In silico research in medicine is thought to reduce the need for expensive clinical trials under the condition of reliable mathematical models and accurate and efficient numerical methods. In the present work, we tackle the numerical simulation of reaction-diffusion equations modeling human ischemic stroke. This problem induces peculiar difficulties like potentially large stiffness which stems from the broad spectrum of temporal scales in the nonlinear chemical source term as well as from the presence of steep spatial gradients in the reaction fronts, spatially very localized. Furthermore, simulations on realistic 3D geometries are mandatory in order to describe correctly this type of phenomenon. The main goal of this article is to obtain, for the first time, 3D simulations on realistic geometries and to show that the simulation results are consistent with those obtain in experimental studies or observed on MRI images in stroke patients. For this purpose, we introduce a new resolution strategy based mainly on time operator splitting that takes into account complex geometry coupled with a well-conceived parallelization strategy for shared memory architectures. We consider then a high order implicit time integration for the reaction and an explicit one for the diffusion term in order to build a time operator splitting scheme that exploits efficiently the special features of each problem. Thus, we aim at solving complete and realistic models including all time and space scales with conventional computing resources, that is on a reasonably powerful workstation. Consequently and as expected, 2D and also fully 3D numerical simulations of ischemic strokes for a realistic brain geometry, are conducted for the first time and shown to reproduce the dynamics observed on MRI images in stroke patients. Beyond this major step, in order to improve accuracy and computational efficiency of the simulations, we indicate how the present numerical strategy can be coupled with spatial
3D simulation of the Cluster-Cluster Aggregation model
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.
Applications of Wavelets in 3-D Audio Simulation
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Wavelet has been used as a powerful tool in the signal processing and function approx imation recently. This paper presents the application of wavelets for solving two key problems in 3-1 audio simulation. First, we employ discrete wavelet transform (DWT) combined with vector quantisation (VQ) to compress audio data in order to reduce tremendous redundant data storage and transmission times. Secondly, we use wavelets as the activation functions in neural networks called feed-forward wavelet networks to approach auditory localisation information cues (head-related transfer functions (HRTFs) are used here). The experimental results demonstrate that the applica tion of wavelets is more efficientand useful in 3-D audio simulation.
Hybrid 2D-3D modelling of GTA welding with filler wire addition
Traidia, Abderrazak
2012-07-01
A hybrid 2D-3D model for the numerical simulation of Gas Tungsten Arc welding is proposed in this paper. It offers the possibility to predict the temperature field as well as the shape of the solidified weld joint for different operating parameters, with relatively good accuracy and reasonable computational cost. Also, an original approach to simulate the effect of immersing a cold filler wire in the weld pool is presented. The simulation results reveal two important observations. First, the weld pool depth is locally decreased in the presence of filler metal, which is due to the energy absorption by the cold feeding wire from the hot molten pool. In addition, the weld shape, maximum temperature and thermal cycles in the workpiece are relatively well predicted even when a 2D model for the arc plasma region is used. © 2012 Elsevier Ltd. All rights reserved.
Hybrid femtosecond laser 3D microprocessing and application to biochip fabrication
International Nuclear Information System (INIS)
To fabricate highly functional biochips, we propose a novel technique termed hybrid femtosecond laser processing, in which femtosecond laser 3D glass micromachining (subtractive manufacturing) and two-photon polymerization (TPP) (additive manufacturing) are combined. In this process, 3D microfluidic structures are first formed inside the glass by femtosecond laser 3D glass micromachining, and functional micro and nano components are then integrated in the 3D microfluidics by TPP. We refer such glass microfluidics integrated with 3D polymer micro and nanostructures to as a ship-in-a-bottle biochip. (author)
Hybrid animation integrating 2D and 3D assets
O'Hailey, Tina
2010-01-01
Artist imaginations continue to grow and stretch the boundaries of traditional animation. Successful animators adept and highly skilled in traditional animation mediums are branching out beyond traditional animation workflows and will often use multiple forms of animation in a single project. With the knowledge of 3D and 2D assets and the integration of multiple animation mediums into a single project, animators have a wealth of creative resources available for a project that is not limited to a specific animation medium, software package or workflow processs. Enhance a poignant scene by choos
Development of Advanced Models for 3D Photocathode PIC Simulations
Dimitrov, Dimitre; Cary, John R; Feldman, Donald; Jensen, Kevin; Messmer, Peter; Stoltz, Peter
2005-01-01
Codes for simulating photocathode electron guns invariably assume the emission of an idealized electron distribution from the cathode, regardless of the particular particle emission model that is implemented. The output of such simulations, a relatively clean and smooth distribution with very little variation as a function of the azimuthal angle, is inconsistent with the highly irregular and asymmetric electron bunches seen in experimental diagnostics. To address this problem, we have implemented a recently proposed theoretical model* that takes into account detailed solid-state physics of photocathode materials in the VORPAL particle-in-cell code.** Initial results from 3D simulations with this model and future research directions will be presented and discussed.
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.
1D-3D Hybrid Modelling - From Multi-Compartment Models to Full Resolution Models in Space and Time
Directory of Open Access Journals (Sweden)
Stephan eGrein
2014-07-01
Full Text Available Investigation of cellular and network dynamics in the brain by means of modeling & simulation has evolved into a highly interdisciplinary field, that uses sophisticated modeling & simulation approaches to understand distinct areas of brain function. Depending on the underlying complexity, these models vary in level of detail to cope with the attached computational cost. Hence for large network simulations, single neurons are typically reduced to time-dependent signal processors, dismissing spatial aspects of the cells. For single cell or small-world networks, general purpose simulators allow for space and time-dependent simulations of electrical signal processing, based on the cable equation theory. An emerging field in Computational Neuroscience encompasses a new level of detail by incorporating the 3D morphology of cells and organelles into 3D space and time-dependent simulations. Every approach has its advantages and limitations, such as computational cost, integrated and methods-spanning simulation approaches, depending on the network size could establish new ways to investigate the brain. We present a hybrid simulation approach, that makes use of reduced 1D-models using e.g. the NEURON which couples to fully resolved models for simulating cellular and sub-cellular dynamics, including the detailed 3D-morphology of neurons and organelles. To couple 1D- & 3D-simulations, we present a geometry and membrane potential mapping framework, with which graph-based morphologies, e.g. in swc-/hoc-format, are mapped to full surface and volume representations of the neuron; membrane potential data from 1D-simulations are used as boundary conditions for full 3D simulations. Thus, established models and data, based on general purpose 1D-simulators, can be directly coupled to the emerging field of fully resolved highly detailed 3D-modeling approaches. The new framework is applied to investigate electrically active neurons and their intracellular spatio
Hybrid Method for 3D Segmentation of Magnetic Resonance Images
Institute of Scientific and Technical Information of China (English)
ZHANGXiang; ZHANGDazhi; TIANJinwen; LIUJian
2003-01-01
Segmentation of some complex images, especially in magnetic resonance brain images, is often difficult to perform satisfactory results using only single approach of image segmentation. An approach towards the integration of several techniques seems to be the best solution. In this paper a new hybrid method for 3-dimension segmentation of the whole brain is introduced, based on fuzzy region growing, edge detection and mathematical morphology, The gray-level threshold, controlling the process of region growing, is determined by fuzzy technique. The image gradient feature is obtained by the 3-dimension sobel operator considering a 3×3×3 data block with the voxel to be evaluated at the center, while the gradient magnitude threshold is defined by the gradient magnitude histogram of brain magnetic resonance volume. By the combined methods of edge detection and region growing, the white matter volume of human brain is segmented perfectly. By the post-processing using mathematical morphological techniques, the whole brain region is obtained. In order to investigate the validity of the hybrid method, two comparative experiments, the region growing method using only gray-level feature and the thresholding method by combining gray-level and gradient features, are carried out. Experimental results indicate that the proposed method provides much better results than the traditional method using a single technique in the 3-dimension segmentation of human brain magnetic resonance data sets.
3D TCAD Simulation for Semiconductor Processes, Devices and Optoelectronics
Li, Simon
2012-01-01
Technology computer-aided design, or TCAD, is critical to today’s semiconductor technology and anybody working in this industry needs to know something about TCAD. This book is about how to use computer software to manufacture and test virtually semiconductor devices in 3D. It brings to life the topic of semiconductor device physics, with a hands-on, tutorial approach that de-emphasizes abstract physics and equations and emphasizes real practice and extensive illustrations. Coverage includes a comprehensive library of devices, representing the state of the art technology, such as SuperJunction LDMOS, GaN LED devices, etc. Provides a vivid, internal view of semiconductor devices, through 3D TCAD simulation; Includes comprehensive coverage of TCAD simulations for both optic and electronic devices, from nano-scale to high-voltage high-power devices; Presents material in a hands-on, tutorial fashion so that industry practitioners will find maximum utility; Includes a comprehensive library of devices, re...
Reconciling measured scattering response of 3D metamaterials with simulation
Directory of Open Access Journals (Sweden)
Adomanis Bryan M.
2015-01-01
Full Text Available Membrane projection lithography is used to create 3-dimensional unit cells in a silicon matrix decorated with metallic inclusions. The structures show pronounced resonances in the 4–16 µm wavelength range and demonstrate direct coupling to the magnetic field of a normally incident transverse electromagnetic (TEM wave, a behavior only possible for vertically oriented resonators. Qualitative agreement between rigorous coupled wave analysis (RCWA simulation and measured scattering response is shown. COMSOL simulations show that slight variations in both metallic inclusion and silicon unit cell physical dimensions can have large impact in the scattering response, so that design for manufacture of 3D metamaterial structures for applications should be done with care.
3D numerical simulation and analysis of railgun gouging mechanism
Directory of Open Access Journals (Sweden)
Jin-guo Wu
2016-04-01
Full Text Available A gouging phenomenon with a hypervelocity sliding electrical contact in railgun not only shortens the rail lifetime but also affects the interior ballistic performance. In this paper, a 3-D numerical model was introduced to simulate and analyze the generation mechanism and evolution of the rail gouging phenomenon. The results show that a rail surface bulge is an important factor to induce gouging. High density and high pressure material flow on the contact surface, obliquely extruded into the rail when accelerating the armature to a high velocity, can produce gouging. Both controlling the bulge size to a certain range and selecting suitable materials for rail surface coating will suppress the formation of gouging. The numerical simulation had a good agreement with experiments, which validated the computing model and methodology are reliable.
Coniferous Canopy BRF Simulation Based on 3-D Realistic Scene
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.
Optimizing prostate needle biopsy through 3D simulation
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
3D Printed PEG-Based Hybrid Nanocomposites Obtained by Sol-Gel Technique.
Chiappone, Annalisa; Fantino, Erika; Roppolo, Ignazio; Lorusso, Massimo; Manfredi, Diego; Fino, Paolo; Pirri, Candido Fabrizio; Calignano, Flaviana
2016-03-01
In this work, three-dimensional (3D) structured hybrid materials were fabricated combining 3D printing technology with in situ generation of inorganic nanoparticles by sol-gel technique. Those materials, consisting of silica nanodomains covalently interconnected with organic polymers, were 3D printed in complex multilayered architectures, incorporating liquid silica precursors into a photocurable oligomer in the presence of suitable photoinitiators and exposing them to a digital light system. A post sol-gel treatment in acidic vapors allowed the in situ generation of the inorganic phase in a dedicated step. This method allows to build hybrid structures operating with a full liquid formulation without meeting the drawbacks of incorporating inorganic powders into 3D printable formulations. The influence of the generated silica nanoparticle on the printed objects was deeply investigated at macro- and nanoscale; the resulting light hybrid structures show improved mechanical properties and, thus, have a huge potential for applications in a variety of advanced technologies. PMID:26871993
Simulated Photoevaporative Mass Loss from Hot Jupiters in 3D
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.
Study, simulation and design of a 3D clinostat
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
3D Simulation Modeling of the Tooth Wear Process.
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.
3D Simulation Modeling of the Tooth Wear Process.
Directory of Open Access Journals (Sweden)
Ning Dai
Full Text Available 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.
Linking 1D Stellar Evolution to 3D Hydrodynamical Simulations
Cristini, Andrea; Georgy, Cyril; Meakin, Casey; Arnett, David; Viallet, Maxime
2014-01-01
In this contribution we present initial results of a study on convective boundary mixing (CBM) in massive stellar models using the GENEVA stellar evolution code. Before undertaking costly 3D hydrodynamic simulations, it is important to study the general properties of convective boundaries, such as the: composition jump; pressure gradient; and `stiffness'. Models for a 15Mo star were computed. We found that for convective shells above the core, the lower (in radius or mass) boundaries are `stiffer' according to the bulk Richardson number than the relative upper (Schwarzschild) boundaries. Thus, we expect reduced CBM at the lower boundaries in comparison to the upper. This has implications on flame front propagation and the onset of novae.
3D MHD disruptions simulations of tokamaks plasmas
Paccagnella, Roberto; Strauss, Hank; Breslau, Joshua
2008-11-01
Tokamaks Vertical Displacement Events (VDEs) and disruptions simulations in toroidal geometry by means of a single fluid visco-resistive magneto-hydro-dynamic (MHD) model are presented in this paper. The plasma model, implemented in the M3D code [1], is completed with the presence of a 2D homogeneous wall with finite resistivity. This allows the study of the relatively slowly growing magneto-hydro-dynamical perturbation, the resistive wall mode (RWM), which is, in this work, the main drive of the disruptions. Amplitudes and asymmetries of the halo currents pattern at the wall are also calculated and comparisons with tokamak experimental databases and predictions for ITER are given. [1] W. Park, E.V. Belova, G.Y. Fu, X.Z. Tang, H.R. Strauss, L.E. Sugiyama, Phys. Plasmas 6 (1999) 1796.
3D Simulations of Galactic Winds in Dwarf Galaxies
Marcolini, A; D'Ercole, A; Marcolini, Andrea; Brighenti, Fabrizio; Ercole, Annibale D'
2002-01-01
We present 3D hydrodynamical simulations of galactic winds in dwarf, gas-rich galaxies. The galaxy is moving through the ICM of a small galaxy group at v=200 km/s. The ram pressure removes the galactic gas at large radii, but does not strongly influence the ISM near the center. A starburst generates a galactic wind. The newly produced metals are expelled in the ICM and carried to large distance from the galaxy by the ram pressure. 500 Myr after the starburst only a few percent of the heavy elements produced are present in the central region of the dwarf galaxy. A large collection of ram pressure + wind models will be presented in a forthcoming paper.
3D AMR simulations of G2 as an outflow
Ballone, A; Burkert, A; Gillessen, S; Plewa, P M; Pfuhl, O; Genzel, R; Eisenhauer, F; Ott, T; George, E M; Habibi, M
2016-01-01
We study the evolution of G2 in a \\textit{Compact Source Scenario}, where G2 is the outflow from a low-mass central star moving on the observed orbit. This is done through 3D AMR simulations of the hydrodynamic interaction of G2 with the surrounding hot accretion flow. A comparison with observations is done by means of mock position-velocity (PV) diagrams. We found that a massive ($\\dot{M}_\\mathrm{w}=5\\times 10^{-7} \\;M_{\\odot} \\; \\mathrm{yr^{-1}}$) and slow ($v_\\mathrm{w}=50 \\;\\mathrm{km\\; s^{-1}}$) outflow can reproduce G2's properties. A faster outflow ($v_\\mathrm{w}=400 \\;\\mathrm{km\\; s^{-1}}$) might also be able to explain the material that seems to follow G2 on the same orbit.
Validation of 3D simulations of reverse osmosis membrane biofouling.
Pintelon, Thomas R R; Creber, Sarah A; von der Schulenburg, Daniel A Graf; Johns, Michael L
2010-07-01
The increasing demand for drinking water and its stricter quality requirements have resulted in an exponentially expanding industry of membrane filtration processes. Currently, reverse osmosis (RO) is the most common method of desalination, able to produce water that is virtually free of pollutants and pathogenic micro-organisms. Biofouling of these devices however is a significant limitation. Here we present a 3D simulation of RO membrane biofouling based on a lattice Boltzmann (LB) platform that we subsequently favorably compare with experimental data. This data consists of temporally (and spatially) resolved velocity measurements acquired for a RO membrane using magnetic resonance techniques. The effect of biofilm cohesive strength on system pressure drop is then explored; weaker biomass is observed to have a reduced impact on pressure drop (per unit biomass accumulated).
Bioactive polymeric–ceramic hybrid 3D scaffold for application in bone tissue regeneration
International Nuclear Information System (INIS)
The regeneration of large bone defects remains a challenging scenario from a therapeutic point of view. In fact, the currently available bone substitutes are often limited by poor tissue integration and severe host inflammatory responses, which eventually lead to surgical removal. In an attempt to address these issues, herein we evaluated the importance of alginate incorporation in the production of improved and tunable β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) three-dimensional (3D) porous scaffolds to be used as temporary templates for bone regeneration. Different bioceramic combinations were tested in order to investigate optimal scaffold architectures. Additionally, 3D β-TCP/HA vacuum-coated with alginate, presented improved compressive strength, fracture toughness and Young's modulus, to values similar to those of native bone. The hybrid 3D polymeric–bioceramic scaffolds also supported osteoblast adhesion, maturation and proliferation, as demonstrated by fluorescence microscopy. To the best of our knowledge this is the first time that a 3D scaffold produced with this combination of biomaterials is described. Altogether, our results emphasize that this hybrid scaffold presents promising characteristics for its future application in bone regeneration. - Graphical abstract: B-TCP:HA–alginate hybrid 3D porous scaffolds for application in bone regeneration. - Highlights: • The produced hybrid 3D scaffolds are prone to be applied in bone tissue engineering. • Alginate coated 3D scaffolds present high mechanical and biological properties. • In vitro assays for evaluation of human osteoblast cell attachment in the presence of the scaffolds • The hybrid 3D scaffolds present suitable mechanical and biological properties for use in bone regenerative medicine
3D Hydrodynamic Simulations of Carbon Burning in Massive Stars
Cristini, Andrea; Hirschi, Raphael; Arnett, David; Georgy, Cyril; Viallet, Maxime
2016-01-01
We present the first detailed three-dimensional (3D) hydrodynamic implicit large eddy simulations of turbulent convection of carbon burning in massive stars. The simulations start with initial radial profiles mapped from a carbon burning shell within a 15$\\,\\textrm{M}_\\odot$ 1D stellar evolution model. We consider 4 resolutions from $128^3$ to $1024^3$ zones. The turbulent flow properties of these carbon burning simulations are very similar to the oxygen burning case. We performed a mean field analysis of the kinetic energy budgets within the Reynolds-averaged Navier-Stokes framework. For the upper convective boundary region, we find that the inferred numerical dissipation is insensitive to resolution for linear mesh resolutions between 512 and 1,024 grid points. For the stiffer and more stratified lower boundary, our highest resolution model still shows signs of decreasing dissipation suggesting that it is not yet fully resolved numerically. We estimate the widths of the upper and lower boundaries to be roug...
3D Dynamic Earthquake Fracture Simulation (Test Case)
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
Hybrid Detectors for Neutrons Combining Phenyl- Polysiloxanes with 3D Silicon Detectors
International Nuclear Information System (INIS)
We report on the initial results of a research project aimed at the development hybrid detectors for fast neutrons by combining a phenyl-polysiloxane-based converter with a 3D silicon detector. To this purpose, new 3D sensor structures have been designed, fabricated and electrically tested, showing low depletion voltage and good leakage current. Moreover, the radiation detection capability of 3D sensors was tested by measuring the signals recorded from alpha particles, gamma rays, and pulsed lasers. The converter has been poured into the 3D cavities with excellent coupling, as confirmed by cross-section SEM analyses. Preliminary tests with neutrons have been carried out on the first hybrid detector prototypes at the CN accelerator of INFN LNL. The device design and technology are discussed, along with the first results from the electrical and functional characterization. (authors)
3D mapping and simulation of Geneva Lake environmental data
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
Virtual environment display for a 3D audio room simulation
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.
3-D Relativistic MHD Simulations of Extragalactic Jets
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.
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.
Optimization of a Hybrid Magnetic Bearing for a Magnetically Levitated Blood Pump via 3-D FEA
Cheng, Shanbao; Olles, Mark W.; Burger, Aaron F.; Steven W Day
2011-01-01
In order to improve the performance of a magnetically levitated (maglev) axial flow blood pump, three-dimensional (3-D) finite element analysis (FEA) was used to optimize the design of a hybrid magnetic bearing (HMB). Radial, axial, and current stiffness of multiple design variations of the HMB were calculated using a 3-D FEA package and verified by experimental results. As compared with the original design, the optimized HMB had twice the axial stiffness with the resulting increase of negati...
3D Digital Design of Cranes' Structures Based on Hybrid Software Architecture
Institute of Scientific and Technical Information of China (English)
WANG Chonghua; LI Hua
2006-01-01
3D digital design for cranes' structures based on hybrid software architecture of Client/Server and Browser/Server is introduced in this paper. Based on Pro/ENGINEER platform, 3D parametric model family is built to allow generation of feasible configurations of cranes' structures in Client/Server framework. Taking use of Visual C++, the second exploiting software kit provided by Pro/ENGINEER and ANSYS GUI/APDL modeling patterns, an integration method of 3D CAD and CAE is achieved, which includes regeneration of 3D parametric model, synchronous updating and analysis of FEA model. As in Browser/Server framework, the 3D CAD models of parts, components and the whole structure could also be displayed in the customer's browser in VRML format.
3D two-fluid simulations of turbulence in LAPD
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
A hybrid method for the computation of quasi-3D seismograms.
Masson, Yder; Romanowicz, Barbara
2013-04-01
The development of powerful computer clusters and efficient numerical computation methods, such as the Spectral Element Method (SEM) made possible the computation of seismic wave propagation in a heterogeneous 3D earth. However, the cost of theses computations is still problematic for global scale tomography that requires hundreds of such simulations. Part of the ongoing research effort is dedicated to the development of faster modeling methods based on the spectral element method. Capdeville et al. (2002) proposed to couple SEM simulations with normal modes calculation (C-SEM). Nissen-Meyer et al. (2007) used 2D SEM simulations to compute 3D seismograms in a 1D earth model. Thanks to these developments, and for the first time, Lekic et al. (2011) developed a 3D global model of the upper mantle using SEM simulations. At the local and continental scale, adjoint tomography that is using a lot of SEM simulation can be implemented on current computers (Tape, Liu et al. 2009). Due to their smaller size, these models offer higher resolution. They provide us with images of the crust and the upper part of the mantle. In an attempt to teleport such local adjoint tomographic inversions into the deep earth, we are developing a hybrid method where SEM computation are limited to a region of interest within the earth. That region can have an arbitrary shape and size. Outside this region, the seismic wavefield is extrapolated to obtain synthetic data at the Earth's surface. A key feature of the method is the use of a time reversal mirror to inject the wavefield induced by distant seismic source into the region of interest (Robertsson and Chapman 2000). We compute synthetic seismograms as follow: Inside the region of interest, we are using regional spectral element software RegSEM to compute wave propagation in 3D. Outside this region, the wavefield is extrapolated to the surface by convolution with the Green's functions from the mirror to the seismic stations. For now, these
Hybrid 3D pregnant woman and fetus modeling from medical imaging for dosimetry studies
International Nuclear Information System (INIS)
Numerical simulations studying the interactions between radiations and biological tissues require the use of three-dimensional models of the human anatomy at various ages and in various positions. Several detailed and flexible models exist for adults and children and have been extensively used for dosimetry. On the other hand, progress of simulation studies focusing on pregnant women and the fetus have been limited by the fact that only a small number of models exist with rather coarse anatomical details and a poor representation of the anatomical variability of the fetus shape and its position over the entire gestation. In this paper, we propose a new computational framework to generate 3D hybrid models of pregnant women, composed of fetus shapes segmented from medical images and a generic maternal body envelope representing a synthetic woman scaled to the dimension of the uterus. The computational framework includes the following tasks: image segmentation, contour regularization, mesh-based surface reconstruction, and model integration. A series of models was created to represent pregnant women at different gestational stages and with the fetus in different positions, all including detailed tissues of the fetus and the utero-fetal unit, which play an important role in dosimetry. These models were anatomically validated by clinical obstetricians and radiologists who verified the accuracy and representativeness of the anatomical details, and the positioning of the fetus inside the maternal body. The computational framework enables the creation of detailed, realistic, and representative fetus models from medical images, directly exploitable for dosimetry simulations. (orig.)
Simulations of soluble surfactants in 3D multiphase flow
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.
3-D NUMERICAL SIMULATIONS OF FLOW LOSS IN HELICAL CHANNEL
Institute of Scientific and Technical Information of China (English)
ZHAO Ling-zhi; PENG Yan; LU Fang; LI Jian; LI Ran; LIU Bao-lin
2012-01-01
The flow loss of a helical channel Magnetohydrodynamic (MHD) thruster without MHD effect was numerically studied with 3-D simulations,and a flow loss coefficient ξ was defined to quantify the flow loss and its influencing factors were studied.The results show that ξ decreases in a first-order exponential manner with the pitch of a helical wall and the Reynolds number,and it declines slowly when t / T ＞ 0.2 and Re ＞ 105,a flow guide makes the flow more smooth and uniform,especially in the flow guide and helical wall sub-regions and thus reduces the flow loss greatly,by about 30％ with the averaged value of ξ from 0.0385to 0.027,a rectifier weakens the helical flow and strengthens the axial one in the rectifier and outlet sub-regions,thus reduces the rotational kinetic pressure with the averaged value of ξ declining about 4％ from 0.0385 to 0.037,and ξ decreases with a rectifier's axial length when Re ＞ 105.
Simulated Photoevaporative Mass Loss from Hot Jupiters in 3D
Tripathi, Anjali; Murray-Clay, Ruth A; Krumholz, Mark R
2015-01-01
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 $R_p=2.14 R_{\\rm Jup}$ and mass $M_p = 0.53 M_{\\rm Jup}$. 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 ...
Application of FUN3D Solver for Aeroacoustics Simulation of a Nose Landing Gear Configuration
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.
A hybrid experimental-numerical technique for determining 3D velocity fields from planar 2D PIV data
Eden, A.; Sigurdson, M.; Mezić, I.; Meinhart, C. D.
2016-09-01
Knowledge of 3D, three component velocity fields is central to the understanding and development of effective microfluidic devices for lab-on-chip mixing applications. In this paper we present a hybrid experimental-numerical method for the generation of 3D flow information from 2D particle image velocimetry (PIV) experimental data and finite element simulations of an alternating current electrothermal (ACET) micromixer. A numerical least-squares optimization algorithm is applied to a theory-based 3D multiphysics simulation in conjunction with 2D PIV data to generate an improved estimation of the steady state velocity field. This 3D velocity field can be used to assess mixing phenomena more accurately than would be possible through simulation alone. Our technique can also be used to estimate uncertain quantities in experimental situations by fitting the gathered field data to a simulated physical model. The optimization algorithm reduced the root-mean-squared difference between the experimental and simulated velocity fields in the target region by more than a factor of 4, resulting in an average error less than 12% of the average velocity magnitude.
3D graphene-based hybrid materials: synthesis and applications in energy storage and conversion.
Shi, Qiurong; Cha, Younghwan; Song, Yang; Lee, Jung-In; Zhu, Chengzhou; Li, Xiaoyu; Song, Min-Kyu; Du, Dan; Lin, Yuehe
2016-08-25
Porous 3D graphene-based hybrid materials (3D GBHMs) are currently attractive nanomaterials employed in the field of energy. Heteroatom-doped 3D graphene and metal, metal oxide, and polymer-decorated 3D graphene with modified electronic and atomic structures provide promising performance as electrode materials in energy storage and conversion. Numerous synthesis methods such as self-assembly, templating, electrochemical deposition, and supercritical CO2, pave the way to mass production of 3D GBHMs in the commercialization of energy devices. This review summarizes recent advances in the fabrication of 3D GBHMs with well-defined architectures such as finely controlled pore sizes, heteroatom doping types and levels. Moreover, current progress toward applications in fuel cells, supercapacitors and batteries employing 3D GBHMs is also highlighted, along with the detailed mechanisms of the enhanced electrochemical performance. Furthermore, current critical issues, challenges and future prospects with respect to applications of 3D GBHMs in practical devices are discussed at the end of this review. PMID:27531643
Applications of three-dimensional (3D) printing for microswimmers and bio-hybrid robotics.
Stanton, M M; Trichet-Paredes, C; Sánchez, S
2015-04-01
This article will focus on recent reports that have applied three-dimensional (3D) printing for designing millimeter to micrometer architecture for robotic motility. The utilization of 3D printing has rapidly grown in applications for medical prosthetics and scaffolds for organs and tissue, but more recently has been implemented for designing mobile robotics. With an increase in the demand for devices to perform in fragile and confined biological environments, it is crucial to develop new miniaturized, biocompatible 3D systems. Fabrication of materials at different scales with different properties makes 3D printing an ideal system for creating frameworks for small-scale robotics. 3D printing has been applied for the design of externally powered, artificial microswimmers and studying their locomotive capabilities in different fluids. Printed materials have also been incorporated with motile cells for bio-hybrid robots capable of functioning by cell contraction and swimming. These 3D devices offer new methods of robotic motility for biomedical applications requiring miniature structures. Traditional 3D printing methods, where a structure is fabricated in an additive process from a digital design, and non-traditional 3D printing methods, such as lithography and molding, will be discussed.
Plasma boundaries at Mars: a 3-D simulation study
Directory of Open Access Journals (Sweden)
A. Bößwetter
2004-12-01
Full Text Available The interaction of the solar wind with the ionosphere of planet Mars is studied using a three-dimensional hybrid model. Mars has only a weak intrinsic magnetic field, and consequently its ionosphere is directly affected by the solar wind. The gyroradii of the solar wind protons are in the range of several hundred kilometers and therefore comparable with the characteristic scales of the interaction region. Different boundaries emerge from the interaction of the solar wind with the continuously produced ionospheric heavy-ion plasma, which could be identified as a bow shock (BS, ion composition boundary (ICB and magnetic pile up boundary (MPB, where the latter both turn out to coincide. The simulation results regarding the shape and position of these boundaries are in good agreement with the measurements made by Phobos-2 and MGS spacecraft. It is shown that the positions of these boundaries depend essentially on the ionospheric production rate, the solar wind ram pressure, and the often unconsidered electron temperature of the ionospheric heavy ion plasma. Other consequences are rays of planetary plasma in the tail and heavy ion plasma clouds, which are stripped off from the dayside ICB region by some instability.
Key words. Magnetospheric physics (solar wind interactions with unmagnetized bodies – Space plasma physics (discontinuities; numerical simulation studies
SOLUTION OF 3-D TURBULENCE NAVIER-STOKES EQUATIONS USING HYBRID GRIDS
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Hybrid grids are used for the solution of 3D turbulence Navier-Stokes equations. The prismatic grids are generated near the wall, and the tetrahedron grids are generated in the other field. A Navier-Stokes solver using ic Baldwin-Lomax turbulence model is adopted. The numerical tests show that the above method is very efficient.``
A hybrid approach for addressing ring flexibility in 3D database searching.
Sadowski, J
1997-01-01
A hybrid approach for flexible 3D database searching is presented that addresses the problem of ring flexibility. It combines the explicit storage of up to 25 multiple conformations of rings, with up to eight atoms, generated by the 3D structure generator CORINA with the power of a torsional fitting technique implemented in the 3D database system UNITY. A comparison with the original UNITY approach, using a database with about 130,000 entries and five different pharmacophore queries, was performed. The hybrid approach scored, on an average, 10-20% more hits than the reference run. Moreover, specific problems with unrealistic hit geometries produced by the original approach can be excluded. In addition, the influence of the maximum number of ring conformations per molecule was investigated. An optimal number of 10 conformations per molecule is recommended.
20 and 3D Numerical Simulations of Flux Cancellation
Karpen, Judith T.; DeVore, C.; Antiochos, S. K.; Linton, M. G.
2009-01-01
Cancellation of magnetic flux in the solar photosphere and chromosphere has been linked observationally and theoretically to a broad range of solar activity, from filament channel formation to CME initiation. Because this phenomenon is typically measured at only a single layer in the atmosphere, in the radial (line of sight) component of the magnetic field, the actual processes behind this observational signature are ambiguous. It is clear that reconnection is involved in some way, but the location of the reconnection sites and associated connectivity changes remain uncertain in most cases. We are using numerical modeling to demystify flux cancellation, beginning with the simplest possible configuration: a subphotospheric Lundquist flux tube surrounded by a potential field, immersed in a gravitationally stratified atmosphere, spanning many orders of magnitude in plasma beta. In this system, cancellation is driven slowly by a 2-cell circulation pattern imposed in the convection zone, such that the tops of the cells are located around the beta= 1 level (Le., the photosphere) and the flows converge and form a downdraft at the polarity inversion line; note however that no flow is imposed along the neutral line. We will present the results of 2D and 3D MHD-AMR simulations of flux cancellation, in which the flux at the photosphere begins in either an unsheared or sheared state. In all cases, a lOW-lying flux rope is formed by reconnection at the polarity inversion line within a few thousand seconds. The flux rope remains stable and does not rise, however, in contrast to models which do not include the presence of significant mass loading.
2D and 3D Numerical Simulations of Flux Cancellation
Karpen, Judith T.; DeVore, C.; Antiochos, S. K.; Linton, M. G.
2009-01-01
Cancellation of magnetic flux in the solar photosphere and chromosphere has been linked observationally and theoretically to a broad range of solar activity, from filament channel formation to CME initiation. Because this phenomenon is typically measured at only a single layer in the atmosphere, in the radial (line of sight) component of the magnetic field, the actual processes behind this observational signature are ambiguous. It is clear that reconnection is involved in some way, but the location of the reconnection sites and associated connectivity changes remain uncertain in most cases. We are using numerical modeling to demystify flux cancellation, beginning with the simplest possible configuration: a subphotospheric Lundquist flux tube surrounded by a potential field, immersed in a gravitationally stratified atmosphere, spanning many orders of magnitude in plasma beta. In this system, cancellation is driven slowly by a 2-cell circulation pattern imposed in the convection zone, such that the tops of the cells are located around the beta=1 level (i.e., the photosphere) and the flows converge and form a downdraft at the polarity inversion line; note however that no flow is imposed along the neutral line. We will present the results of 2D and 3D MHD-AMR simulations of flux cancellation, in which the flux at the photosphere begins in either an unsheared or sheared state. In all cases, a low-lying flux rope is formed by reconnection at the polarity inversion line within a few thousand seconds. The flux rope remains stable and does not rise, however, in contrast to models which do not include the presence of significant mass loading.
Directory of Open Access Journals (Sweden)
K. H. Glassmeier
2009-06-01
Full Text Available The Rosetta spacecraft flew by Mars at a distance of 260 km on 25 February 2007 during a gravity assist manoeuvre. During the closest approach (CA the lander magnetometer ROMAP was switched on. The dataset taken during this swingby provides insight into the plasma environment around Mars: in addition to a pronounced bow shock crossing Rosetta recorded the signature of the pile up region of draped magnetic field. Also the Rosetta measurements showed signatures of crustal magnetic field anomalies which can be verified by results of a crustal magnetic field model. In order to understand the measured field morphology, multi-ion hybrid simulations were performed. Some of the input parameters for the simulations were obtained from Mars Express (MEX data which were contemporaneously collected during the Rosetta swingby. These simulations reproduces ROMAP magnetic field measurements and show that the interplanetary magnetic field pointed northward during the encounter. A spectral analysis shows upstream waves ahead of the bow shock and indicates the presence of the magnetic pile-up boundary (MPB. The multi-ion model reproduces the ion fluxes measured by MEX/ASPERA-3 and is in agreement with the measurements to within one order of magnitude.
Lorentz boosted frame simulation of Laser wakefield acceleration in quasi-3D geometry
Yu, Peicheng; Davidson, Asher; Tableman, Adam; Dalichaouch, Thamine; Meyers, Michael D; Tsung, Frank S; Decyk, Viktor K; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo A; Lu, Wei; Silva, Luis O; Mori, Warren B
2015-01-01
When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at $\\beta_b c$ towards the laser, which can lead to a computational speedup of $\\sim \\gamma_b^2=(1-\\beta_b^2)^{-1}$. 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 problems with the computation load on the order of two dimensional $r-z$ simulations. Here, we describe how to combine the speed ups 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 can be used to effectively eliminate the Numerical Cerenkov Instability (NCI) that 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 simul...
1D-3D hybrid modeling-from multi-compartment models to full resolution models in space and time.
Grein, Stephan; Stepniewski, Martin; Reiter, Sebastian; Knodel, Markus M; Queisser, Gillian
2014-01-01
Investigation of cellular and network dynamics in the brain by means of modeling and simulation has evolved into a highly interdisciplinary field, that uses sophisticated modeling and simulation approaches to understand distinct areas of brain function. Depending on the underlying complexity, these models vary in their level of detail, in order to cope with the attached computational cost. Hence for large network simulations, single neurons are typically reduced to time-dependent signal processors, dismissing the spatial aspect of each cell. For single cell or networks with relatively small numbers of neurons, general purpose simulators allow for space and time-dependent simulations of electrical signal processing, based on the cable equation theory. An emerging field in Computational Neuroscience encompasses a new level of detail by incorporating the full three-dimensional morphology of cells and organelles into three-dimensional, space and time-dependent, simulations. While every approach has its advantages and limitations, such as computational cost, integrated and methods-spanning simulation approaches, depending on the network size could establish new ways to investigate the brain. In this paper we present a hybrid simulation approach, that makes use of reduced 1D-models using e.g., the NEURON simulator-which couples to fully resolved models for simulating cellular and sub-cellular dynamics, including the detailed three-dimensional morphology of neurons and organelles. In order to couple 1D- and 3D-simulations, we present a geometry-, membrane potential- and intracellular concentration mapping framework, with which graph- based morphologies, e.g., in the swc- or hoc-format, are mapped to full surface and volume representations of the neuron and computational data from 1D-simulations can be used as boundary conditions for full 3D simulations and vice versa. Thus, established models and data, based on general purpose 1D-simulators, can be directly coupled to the
Graphene reinforced nanocomposites: 3D simulation of damage and fracture
DEFF Research Database (Denmark)
Dai, Gaoming; Mishnaevsky, Leon
2014-01-01
3D computational model of graphene reinforced polymer composites is developed and applied to the analysis of damage and fracture mechanisms in the composites. The graphene/polymer interface properties are determined using the inverse modeling approach. The effect of composite structure, in partic...
Interdisciplinary Collaboration through Designing 3D Simulation Case Studies
Directory of Open Access Journals (Sweden)
Xin Bai
2011-02-01
Full Text Available Interdisciplinary collaboration is essential for the advance of research. As domain subjects become more and more specialized, researchers need to cross disciplines for insights from peers in other areas to have a broader and deeper understand of a topic at micro- and macro-levels. We developed a 3D virtual learning environment that served as a platform for faculty to plan curriculum, share educational beliefs,and conduct cross-discipline research for effective learning. Based upon the scripts designed by facultyfrom five disciplines, virtual doctors, nurses, or patients interact in a 3D virtual hospital. The teaching vignettes were then converted to video clips, allowing users to view, pause, replay, or comment on the videos individually or in groups. Unlike many existing platforms, we anticipated a value-added by adding a social networking capacity to this virtual environment. The focus of this paper is on the cost-efficiency and system design of the virtual learning environment.
Interdisciplinary Collaboration through Designing 3D Simulation Case Studies
Directory of Open Access Journals (Sweden)
Xin Bai
2011-02-01
Full Text Available Interdisciplinary collaboration is essential for the advance of research. As domain subjects become more and more specialized, researchers need to cross disciplines for insights from peers in other areas to have a broader and deeper understand of a topic at micro- and macro-levels. We developed a 3D virtual learning environment that served as a platform for faculty to plan curriculum, share educational beliefs, and conduct cross-discipline research for effective learning. Based upon the scripts designed by faculty from five disciplines, virtual doctors, nurses, or patients interact in a 3D virtual hospital. The teaching vignettes were then converted to video clips, allowing users to view, pause, replay, or comment on the videos individually or in groups. Unlike many existing platforms, we anticipated a value-added by adding a social networking capacity to this virtual environment. The focus of this paper is on the cost-efficiency and system design of the virtual learning environment.
Interdisciplinary Collaboration through Designing 3D Simulation Case Studies
Bai, Xin; 10.5121/ijma.2011.3109
2011-01-01
Interdisciplinary collaboration is essential for the advance of research. As domain subjects become more and more specialized, researchers need to cross disciplines for insights from peers in other areas to have a broader and deeper understand of a topic at micro- and macro-levels. We developed a 3D virtual learning environment that served as a platform for faculty to plan curriculum, share educational beliefs, and conduct cross-discipline research for effective learning. Based upon the scripts designed by faculty from five disciplines, virtual doctors, nurses, or patients interact in a 3D virtual hospital. The teaching vignettes were then converted to video clips, allowing users to view, pause, replay, or comment on the videos individually or in groups. Unlike many existing platforms, we anticipated a value-added by adding a social networking capacity to this virtual environment. The focus of this paper is on the cost-efficiency and system design of the virtual learning environment.
An Architecture for Hybrid Manufacturing Combining 3D Printing and CNC Machining
Directory of Open Access Journals (Sweden)
Marcel Müller
2016-01-01
Full Text Available Additive manufacturing is one of the key technologies of the 21st century. Additive manufacturing processes are often combined with subtractive manufacturing processes to create hybrid manufacturing because it is useful for manufacturing complex parts, for example, 3D printed sensor systems. Currently, several CNC machines are required for hybrid manufacturing: one machine is required for additive manufacturing and one is required for subtractive manufacturing. Disadvantages of conventional hybrid manufacturing methods are presented. Hybrid manufacturing with one CNC machine offers many advantages. It enables manufacturing of parts with higher accuracy, less production time, and lower costs. Using the example of fused layer modeling (FLM, we present a general approach for the integration of additive manufacturing processes into a numerical control for machine tools. The resulting CNC architecture is presented and its functionality is demonstrated. Its application is beyond the scope of this paper.
DREAM3D simulations of inner-belt dynamics
Energy Technology Data Exchange (ETDEWEB)
Cunningham, Gregory Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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.
Towards the 3D Web with Open Simulator
Oliver, Iain Angus; Miller, Alan Henry David; Allison, Colin; Kennedy, Sarah Elizabeth; Dow, Lisa; Campbell, Anne; Davies, Christopher John; McCaffery, John Philip
2013-01-01
Continuing advances and reduced costs in computational power, graphics processors and network bandwidth have led to 3D immersive multi-user virtual worlds becoming increasingly accessible while offering an improved and engaging Quality of Experience. At the same time the functionality of the World Wide Web continues to expand alongside the computing infrastructure it runs on and pages can now routinely accommodate many forms of interactive multimedia components as standard features - streamin...
3D interactive visualization of crowd simulations at urban scale
Fanini, Bruno; Calori, Luigi
2014-01-01
Digital representations of the urban environment have constantly increased their complexity: starting from fixed chunks of 2D segment depicting the building base to complex data-sets comprising several layer of information such as multi-resolution GIS data combined with on field 3D data acquisition. Cities in particular and urban development in general emerge from the bottom up, so crowd is an essential part of the city environment but it is often absent from most of the intera...
Interactive and Stereoscopic Hybrid 3D Viewer of Radar Data with Gesture Recognition
Goenetxea, Jon; Moreno, Aitor; Unzueta, Luis; Galdós, Andoni; Segura, Álvaro
This work presents an interactive and stereoscopic 3D viewer of weather information coming from a Doppler radar. The hybrid system shows a GIS model of the regional zone where the radar is located and the corresponding reconstructed 3D volume weather data. To enhance the immersiveness of the navigation, stereoscopic visualization has been added to the viewer, using a polarized glasses based system. The user can interact with the 3D virtual world using a Nintendo Wiimote for navigating through it and a Nintendo Wii Nunchuk for giving commands by means of hand gestures. We also present a dynamic gesture recognition procedure that measures the temporal advance of the performed gesture postures. Experimental results show how dynamic gestures are effectively recognized so that a more natural interaction and immersive navigation in the virtual world is achieved.
Using 3-D Numerical Weather Data in Piloted Simulations
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.
Aeroacoustic Simulation of Nose Landing Gear on Adaptive Unstructured Grids With FUN3D
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.
Aeroacoustic Simulation of a Nose Landing Gear in an Open Jet Facility Using FUN3D
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.
Development of hybrid 3-D hydrological modeling for the NCAR Community Earth System Model (CESM)
Energy Technology Data Exchange (ETDEWEB)
Zeng, Xubin [Univ. of Arizona, Tucson, AZ (United States); Troch, Peter [Univ. of Arizona, Tucson, AZ (United States); Pelletier, Jon [Univ. of Arizona, Tucson, AZ (United States); Niu, Guo-Yue [Univ. of Arizona, Tucson, AZ (United States); Gochis, David [NCAR Research Applications Lab., Boulder, CO (United States)
2015-11-15
This is the Final Report of our four-year (3-year plus one-year no cost extension) collaborative project between the University of Arizona (UA) and the National Center for Atmospheric Research (NCAR). The overall objective of our project is to develop and evaluate the first hybrid 3-D hydrological model with a horizontal grid spacing of 1 km for the NCAR Community Earth System Model (CESM).
3d particle simulations on ultra short laser interaction
Energy Technology Data Exchange (ETDEWEB)
Nishihara, Katsunobu; Okamoto, Takashi; Yasui, Hidekazu [Osaka Univ., Suita (Japan). Inst. of Laser Engineering
1998-03-01
Two topics related to ultra short laser interaction with matter, linear and nonlinear high frequency conductivity of a solid density hydrogen plasma and anisotropic self-focusing of an intense laser in an overdense plasma, have been investigated with the use of 3-d particle codes. Frequency dependence of linear conductivity in a dense plasma is obtained, which shows anomalous conductivity near plasma frequency. Since nonlinear conductivity decreases with v{sub o}{sup -3}, where v{sub o} is a quivering velocity, an optimum amplitude exists leading to a maximum electron heating. Anisotropic self-focusing of a linear polarized intense laser is observed in an overdense plasma. (author)
A Web 2.0/Web3D Hybrid Platform For Engaging Students in E-Learning Environments
BYL, Penny De; Taylor, Janet
2007-01-01
ABSTRACTThis paper explores the Web 2.0 ethos with respect to the application of pedagogy within 3D online virtual environments. 3D worlds can create a synthetic experience capturing the essence of being in a particular world or context. The AliveX3D platform adopts the Web 2.0 ethos and applies it to online 3D virtual environment forming a Web 2.0/Web3D hybrid that has wider usability than previous alternatives. This combined with the AliveX3D Scene Editor allows learning experiences, which ...
Mesh Resolution Effect on 3D RANS Turbomachinery Flow Simulations
Yershov, Sergiy
2016-01-01
The paper presents the study of the effect of a mesh refinement on numerical results of 3D RANS computations of turbomachinery flows. The CFD solver F, which based on the second-order accurate ENO scheme, is used in this study. The simplified multigrid algorithm and local time stepping permit decreasing computational time. The flow computations are performed for a number of turbine and compressor cascades and stages. In all flow cases, the successively refined meshes of H-type with an approximate orthogonalization near the solid walls were generated. The results obtained are compared in order to estimate their both mesh convergence and ability to resolve the transonic flow pattern. It is concluded that for thorough studying the fine phenomena of the 3D turbomachinery flows, it makes sense to use the computational meshes with the number of cells from several millions up to several hundred millions per a single turbomachinery blade channel, while for industrial computations, a mesh of about or less than one mil...
3D Hydrodynamic Simulations of Relativistic Extragalactic Jets
Hughes, P A; Duncan, G C; Hughes, Philip A.; Miller, Mark A.
2002-01-01
We describe a new numerical 3D relativistic hydrodynamical code, the results of validation tests, and a comparison with earlier, 2D studies. The 3D code has been used to study the deflection and precession of relativistic flows. We find that even quite fast jets (gamma~10) can be significantly influenced by impinging on an oblique density gradient, exhibiting a rotation of the Mach disk in the jet's head. The flow is bent via a potentially strong, oblique internal shock that arises due to asymmetric perturbation of the flow by its cocoon. In extreme cases this cocoon can form a marginally relativistic flow orthogonal to the jet, leading to large scale dynamics quite unlike that normally associated with astrophysical jets. Exploration of a gamma=5 flow subject to a large amplitude precession (semi-angle 11.25dg) shows that it retains its integrity, with modest reduction in Lorentz factor and momentum flux, for almost 50 jet-radii, but thereafter, the collimated flow is disrupted. The flow is approximately ball...
3D Numerical Simulation of Projectile Penetration into Concrete Target
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Basing on the explicit instantaneous dynamics software MSC-Dytran and the general coupling arithmetic, the process of the projectile penetration into concrete target was simulated with the point-line-surface-body modeling method. Simulation results are in agreement with experimental results. The simulated data could provide design reference for the defense engineering construction and penetrator design.
Parallel Simulation of 3-D Turbulent Flow Through Hydraulic Machinery
Institute of Scientific and Technical Information of China (English)
徐宇; 吴玉林
2003-01-01
Parallel calculational methods were used to analyze incompressible turbulent flow through hydraulic machinery. Two parallel methods were used to simulate the complex flow field. The space decomposition method divides the computational domain into several sub-ranges. Parallel discrete event simulation divides the whole task into several parts according to their functions. The simulation results were compared with the serial simulation results and particle image velocimetry (PIV) experimental results. The results give the distribution and configuration of the complex vortices and illustrate the effectiveness of the parallel algorithms for numerical simulation of turbulent flows.
Rezania, Vahid; Tuszynski, Jack
2016-01-01
In this paper, we develop a spatio-temporal modeling approach to describe blood and drug flow, as well as drug uptake and elimination, on an approximation of the liver. Extending on previously developed computational approaches, we generate an approximation of a liver, which consists of a portal and hepatic vein vasculature structure, embedded in the surrounding liver tissue. The vasculature is generated via constrained constructive optimization, and then converted to a spatial grid of a selected grid size. Estimates for surrounding upscaled lobule tissue properties are then presented appropriate to the same grid size. Simulation of fluid flow and drug metabolism (hepatic clearance) are completed using discretized forms of the relevant convective-diffusive-reactive partial differential equations for these processes. This results in a single stage, uniformly consistent method to simulate equations for blood and drug flow, as well as drug metabolism, on a 3D structure representative of a liver. PMID:27649537
3D stress field simulation for Greater Munich, Germany
Ziegler, Moritz; Heidbach, Oliver; Reinecker, John; Przybycin, Anna Maria; Scheck-Wenderoth, Magdalena
2016-04-01
Geotechnical applications such as tunneling, storage of waste, wellbore planning, or reservoir engineering requires detailed 3D information on the rock properties and behavior of the continuum. One of the key parameters is the contemporary crustal in-situ stress state. However, generally the availability of stress data on reservoir scale is scarce or no data exists at all. Furthermore, stress data is often limited to the orientation of the maximum horizontal stress. Hence, geomechanical-numerical modelling provides an approximation of a continuous description of the 3D in-situ stress state. We present a model workflow that shows (1) how to calibrate a regional scale model of Greater Munich with stress orientations and magnitudes mainly from borehole data and (2) how to derive from the regional model boundary conditions for a local high-resolution model of a geothermal reservoir site. This approach using two models is an alternative to the required trade-off between resolution, computational cost and a sufficient number of calibration data which is otherwise inevitable for a single model. The incorporated 3D geological models contain the topography from a digital elevation model and 6 stratigraphic units with different elasto-plastic rock properties. The local model mimics the area of a planned reservoir and its resolution is significantly higher than in the regional model and down to 10 m near the planned borehole trajectories using 21×106 tetrahedron finite elements with linear approximation functions. The uncertainties of the calibrated regional model are large since no information on the magnitude of the maximum horizontal stress is available. Even in the entire Greater Munich area only two reliable leak-off tests that deliver the magnitude of the minimum horizontal stress could be used. These uncertainties are transferred also to the local model. Hence we also show how to quantify for the workflow in general the systematic uncertainties and discuss
Modeling and simulation of charge collection properties for 3D-trench electrode detector
Energy Technology Data Exchange (ETDEWEB)
Ding, Hao; Chen, Jianwei [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Center for Semiconductor Particle and photon Imaging Detector Development and Fabrication, Xiangtan University, Xiangtan 411105 (China); Li, Zheng, E-mail: zhengli58@gmail.com [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Center for Semiconductor Particle and photon Imaging Detector Development and Fabrication, Xiangtan University, Xiangtan 411105 (China); Brookhaven National Laboratory, Upton, NY (United States); Yan, Shaoan [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Center for Semiconductor Particle and photon Imaging Detector Development and Fabrication, Xiangtan University, Xiangtan 411105 (China)
2015-10-01
3D-trench electrode detectors were simulated in this paper. Charge collection of 3D-trench electrode detector was simulated using the full 3D device simulation. The induced current and collected charge caused by drifting carriers, generated by a minimum ionizing particle (MIP) incident through the detector, have been modeled and calculated. The results indicate that the total collected charge in irradiated detector change with particle incident position and radiation fluence. In addition, we have estimated the average total collected charge generated by a MIP incident in 3D-trench electrode detector.
Numerical Simulation of Effective Properties of 3D Piezoelectric Composites
Directory of Open Access Journals (Sweden)
Ri-Song Qin
2014-01-01
Full Text Available The prediction of the overall effective properties of fibre-reinforced piezocomposites has drawn much interest from investigators recently. In this work, an algorithm used in two-dimensional (2D analysis for calculating transversely isotropic material properties is developed. Since the finite element (FE meshing patterns on the opposite areas are the same, constraint equations can be applied directly to generate appropriate load. The numerical results derived using this model have found a good agreement with those in the literature. The 2D algorithm is then modified and improved in such a way that it is valid for three-dimensional (3D analysis in the case of random distributed shorts and inclusions. Linear interpolation of displacement field is employed to establish constraint equations of nodal displacements between two adjacent elements.
Sharkawi, K.-H.; A. Abdul-Rahman
2013-01-01
Cities and urban areas entities such as building structures are becoming more complex as the modern human civilizations continue to evolve. The ability to plan and manage every territory especially the urban areas is very important to every government in the world. Planning and managing cities and urban areas based on printed maps and 2D data are getting insufficient and inefficient to cope with the complexity of the new developments in big cities. The emergence of 3D city models hav...
3D FEM Simulations of a shape rolling process
Wisselink, H.H.; Huetink, J.; Dijk, van M.H.H.; Leeuwen, van A.J.
2001-01-01
A finite element model has been developed for the simulation of the shape rolling of stator vanes. These simulations should support the design of rolling tools for new vane types. For the time being only straight vanes (vanes with a constant cross-section over the length) are studied. In that case t
Single-sided sheet-to-tube spot welding investigated by 3D numerical simulations
DEFF Research Database (Denmark)
Nielsen, Chris Valentin; Chergui, Azeddine; Zhang, Wenqi
The single-sided resistance spot welding process is analyzed by a 3D numerical study of sheet-to-tube joining. Finite element simulations are carried out in SORPAS® 3D. Two levels of electrode force and five levels of welding current are simulated. The overall effects of changing current and force...
Institute of Scientific and Technical Information of China (English)
Zhang Laiping; Zhao Zhong; Chang Xinghua; He Xin
2013-01-01
A hybrid grid generation technique and a multigrid/parallel algorithm are presented in this paper for turbulence flow simulations over three-dimensional (3D) complex geometries.The hybrid grid generation technique is based on an agglomeration method of anisotropic tetrahedrons.Firstly,the complex computational domain is covered by pure tetrahedral grids,in which anisotropic tetrahedrons are adopted to discrete the boundary layer and isotropic tetrahedrons in the outer field.Then,the anisotropic tetrahedrons in the boundary layer are agglomerated to generate prismatic grids.The agglomeration method can improve the grid quality in boundary layer and reduce the grid quantity to enhance the numerical accuracy and efficiency.In order to accelerate the convergence history,a multigrid/parallel algorithm is developed also based on anisotropic agglomeration approach.The numerical results demonstrate the excellent accelerating capability of this multigrid method.
Hybrid wide-field and scanning microscopy for high-speed 3D imaging.
Duan, Yubo; Chen, Nanguang
2015-11-15
Wide-field optical microscopy is efficient and robust in biological imaging, but it lacks depth sectioning. In contrast, scanning microscopic techniques, such as confocal microscopy and multiphoton microscopy, have been successfully used for three-dimensional (3D) imaging with optical sectioning capability. However, these microscopic techniques are not very suitable for dynamic real-time imaging because they usually take a long time for temporal and spatial scanning. Here, a hybrid imaging technique combining wide-field microscopy and scanning microscopy is proposed to accelerate the image acquisition process while maintaining the 3D optical sectioning capability. The performance was demonstrated by proof-of-concept imaging experiments with fluorescent beads and zebrafish liver.
Benchmark of coupling codes (ALOHA, TOPLHA and GRILL3D) with ITER-relevant Lower Hybrid antenna
International Nuclear Information System (INIS)
In order to assist the design of the future ITER Lower Hybrid launcher, coupling codes ALOHA, from CEA/IRFM, TOPLHA, from Politecnico di Torino, and GRILL3D, developed by Dr. Mikhail Irzak (A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia) and operated by ENEA Frascati, have been compared with the updated (six modules with four active waveguides per module) Passive-Active Multi-junction (PAM) Lower Hybrid antennas. Both ALOHA and GRILL3D formulate the problem in terms of rectangular waveguides modes, while TOPLHA is based on boundary-value problem with the adoption of a triangular cell-mesh to represent the relevant waveguides surfaces. Several plasma profiles, with varying edge density and density increase, have been adopted to provide a complete description of the simulated launcher in terms of reflection coefficient, computed at the beginning of each LH module, and of power spectra. Good agreement can be observed among codes for all the simulated profiles.
The advanced simulation of fatigue crack growth in complex 3D structures
Energy Technology Data Exchange (ETDEWEB)
Kolk, Karsten; Kuhn, Guenther [Institute of Applied Mechanics, Erlangen (Germany)
2006-12-15
An advanced incremental crack growth algorithm for the three-dimensional (3D) simulation of fatigue crack growth in complex 3D structures with linear elastic material behavior is presented. To perform the crack growth simulation as effectively as possible an accurate stress analysis is done by the boundary-element method (BEM) in terms of the 3D dual BEM. The question concerning a reliable 3D crack growth criterion is answered based on experimental observations. All criteria under consideration are numerically realized by a predictor-corrector procedure. The agreement between numerically determined and experimentally observed crack fronts will be shown on both fracture specimens and an industrial application. (orig.)
3D Simulations of methane convective storms on Titan's atmosphere
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.
SIERRA - A 3-D device simulator for reliability modeling
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.
Humanoid Robot 3 -D Motion Simulation for Hardware Realization
Institute of Scientific and Technical Information of China (English)
CAO Xi; ZHAO Qun-fei; MA Pei-sun
2007-01-01
In this paper, three dimensions kinematics andkinetics simulation arc discussed for hardware realization ofa physical biped walking-chair robot. The direct and inverseclose-form kinematics solution of the biped walking-chairis deduced. Several gaits are realized with thekinematics solution, including walking straight on levelfloor, going up stair, squatting down and standing up. ZeroMoment Point(ZMP) equation is analyzed considering themovement of the crew. The simulated biped walking-chairrobot is used for mechanical design, gaits development andvalidation before they are tested on real robot.
Hierarchical approach to 'atomistic' 3-D MOSFET simulation
Asenov, A.; Brown, A. R.; J. H. Davies; S Saini
1999-01-01
We present a hierarchical approach to the 'atomistic' simulation of aggressively scaled sub-0.1-Î¼m MOSFETs. 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 de...
Aeroacoustic Simulations of a Nose Landing Gear Using FUN3D on Pointwise Unstructured Grids
Vatsa, Veer N.; Khorrami, Mehdi R.; Rhoads, John; Lockard, David P.
2015-01-01
Numerical simulations have been performed for a partially-dressed, cavity-closed (PDCC) nose landing gear configuration that was tested in the University of Florida's open-jet acoustic facility known as the UFAFF. The unstructured-grid flow solver FUN3D is used to compute the unsteady flow field for this configuration. Mixed-element grids generated using the Pointwise(TradeMark) grid generation software are used for these simulations. Particular care is taken to ensure quality cells and proper resolution in critical areas of interest in an effort to minimize errors introduced by numerical artifacts. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these simulations. Solutions are also presented for a wall function model coupled to the standard turbulence model. Time-averaged and instantaneous solutions obtained on these Pointwise grids are compared with the measured data and previous numerical solutions. The resulting CFD solutions are used as input to a Ffowcs Williams-Hawkings noise propagation code to compute the farfield noise levels in the flyover and sideline directions. The computed noise levels compare well with previous CFD solutions and experimental data.
Simulation of 3D-CRT treatment for lung cancer
Energy Technology Data Exchange (ETDEWEB)
Thalhofer, Jardel L.; Silva, Ademir X. da; Junior, Juraci R.P., E-mail: jardellt@yahoo.com.br [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Rebello, Wilson F., E-mail: rebello@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Nuclear; Correa, Samanda C.A., E-mail: samandacristine@uezo.rj.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil); Souza, Edmilson M., E-mail: emonteiro@nuclear.ufrj.br [Centro Universitario da Zona Oeste (UEZO), Rio de Janeiro, RJ (Brazil). Colegiado de Comutacao e Matematica; Batista, Delano V.S., E-mail: delano@inca.gov.br [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil)
2013-07-01
In radiotherapy treatment for lung cancer, occurs doses deposition in healthy organs. During the treatment planning are calculated some doses due to photons. This dose deposition in healthy organs could induce to the appearance of new cancers foci. The aim of this study was to analyze the equivalent doses in healthy organs of a patient treated by radiotherapy for lung cancer. In order to calculate the doses, was done a computer simulation of radiotherapy treatment for lung cancer, adopting database of the treatment performed by INCA. To perform the simulation was used several tools, among them, the radiation transport code MCNPX, in which was shaped the radiotherapy room and the head from the linear accelerator Varian 2300 C / D, the patient was simulated by Voxel male phantom in Rex,and the treatment protocol adopted considers a beam with energy of 6 MV focusing on three gantry tilt angles (0 deg, 180 deg and 45 deg). In addition, there was variation in the opening of the radiation field according to the angle of inclination. The results of this study point to the organs close to the irradiated area are predominantly affected by the dose due to photons, affecting organs from different body systems, such as esophagus, heart, thymus, spine and lymph nodes. The calculated values demonstrating that the angle of 0 deg was the most responsible for the deposit of unwanted dose. The results showed that the simulations in this paper is developed in accordance with the planning data described in different studies and literature. (author)
Vectors in Use in a 3D Juggling Game Simulation
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…
Hybrid Three-Dimensional (3-D) Woven Thick Composite Architectures in Bending
Pankow, Mark; Quabili, Ashiq; Yen, Chian-Fong
2013-11-01
In this study, three 3-dimensional (3-D) woven composite materials were examined to determine how yarn tow configurations affect the flexural response of the structure. Woven fabric preforms were manufactured with a Z-fiber architecture in 2-3 in. thicknesses. These preforms contained S-2 Glass (AGY, Aiken, SC, USA), carbon, and Twaron (Teijin Aramid, Arnhem, The Netherlands) yarns in different architectures creating a hybrid material system. Due to the thickness of the material, these samples required a significant span length (30 in.). The results showed a change in the strength and degradation after failure with the addition of carbon layers in tension.
Microbial Enhanced Oil Recovery: 3D Simulation with Gravity Effects
DEFF Research Database (Denmark)
Nielsen, Sidsel Marie; Jessen, K.; Shapiro, Alexander;
2010-01-01
calculations. We investigate the benefit of MEOR relative to water flooding, comparing the processes in multiple dimensions. The results of our simulations demonstrate that the oil recovery from MEOR processes in relation to water flooding is markedly increased, and the high recovery is achieved much faster......Microbial enhanced oil recovery (MEOR) utilizes the activity of microorganisms, where microorganisms simultaneously grow in a reservoir and convert substrate into recovery enhancing products (usually, surfactants). In order to predict the performance of a MEOR process, a simulation tool is required......, with all the relevant physical processes included. We have developed a mathematical model describing the process of MEOR, where reactive transport is combined with a simple compositional approach. The model describes the displacement of oil by water containing bacteria, substrate, and the produced...
Dynamic triangulations for efficient 3D simulation of granular materials
Ferrez, Jean-Albert; Liebling, Thomas M.
2007-01-01
Granular materials are omnipresent in many fields ranging from civil engineering to food, mining and pharmaceutical industries. Often considered a fourth state of matter, they exhibit specific phenomena such as segregation, arching effects, pattern formation, etc. Due to its potential capability of realistically rendering these behaviors, the Distinct Element Method (DEM) is a very enticing simulation technique. Indeed it makes it possible to analyze and observe phenomena that are barely if a...
3D simulation of superconducting microwave devices with an electromagnetic-field simulator
Takeuchi, N.; Yamanashi, Yuki; Saito, Y; Yoshikawa, Nobuyuki
2009-01-01
High-frequency microwave applications, such as filters, delay lines, and resonators, are quite important for superconducting electronic devices. In order to design the superconducting microwave devices, circuit parameters should be precisely extracted from the physical structure of the devices. A 3-dimentional electromagnetic-field simulators is very useful for designing microwave devices. However, designing of superconducting microwave devices using a conventional 3D electromagnetic-field si...
3D MHD simulation of polarized emission in SN 1006
Schneiter, E M; Reynoso, E M; Esquivel, A; De Colle, F
2015-01-01
We use three dimensional magnetohydrodynamic (MHD) 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.
Energy Technology Data Exchange (ETDEWEB)
Kolk, K.
2005-07-15
This is an important contribution to reliable simulation of stable fatigue crack growth in real 3D problems under complex loads. The nonlinear crack propagation process requires an incremental solution algorithm. Each increment starts with a load analysis of the current crack configuration using the fast dual boundary element method. The potential of this method is more fully utilized with a fast boundary element formulation. Afater this, a real 3D crack propagation criterion is evaluated which is based on experimental findings and is realized within a preditor-corrector method. Finally, the numeric model is generated for the next increment. This generation is made automatically using a local renetworking algorithm. With the crack propagation module thus developed, complex components, e.g. motor car components, can be analyzed fracture-mechanically on a standard PC. (orig.) [German] Die vorliegende Arbeit leistet einen wesentlichen Beitrag zur zuverlaessigen Simulation des stabilen Ermuedungsrisswachstums in realen 3D-Problemen unter komplexen Belastungen. Der nichtlineare Vorgang des Risswachstums erfordert einen inkrementellen Loesungsalgorithmus. In jedem Inkrement wird zunaechst eine Beanspruchungsanalyse der aktuellen Risskonfiguration mit der leistungsstarken dualen Randelementmethode durchgefuehrt. Das Potenzial dieser Methode wird mit einer schnellen Randelementformulierung weiter ausgeschoepft. Anschliessend wird ein echtes 3D-Rissfortschrittskriterium ausgewertet, welches auf experimentellen Erkenntnissen beruht und innerhalb eines Praediktor-Korrektor-Verfahrens realisiert ist. Abschliessend wird das numerische Modell fuer das naechste Inkrement generiert. Diese Generierung erfolgt automatisch mit einem lokalen Neuvernetzungsalgorithmus. Mit dem entwickelten Rissfortschrittsmodul koennen komplexe Bauteile, z.B. aus dem Automobilbau, erfolgreich auf einem Standard-PC bruchmechanisch analysiert werden.
3D Computational Simulation of Calcium Leaching in Cement Matrices
Directory of Open Access Journals (Sweden)
Gaitero, J. J.
2014-12-01
Full Text Available Calcium leaching is a degradation process consisting in progressive dissolution of the cement paste by migration of calcium atoms to the aggressive solution. It is therefore, a complex phenomenon involving several phases and dissolution and diffusion processes simultaneously. Along this work, a new computational scheme for the simulation of the degradation process in three dimensions was developed and tested. The toolkit was used to simulate accelerated calcium leaching by a 6M ammonium nitrate solution in cement matrices. The obtained outputs were the three dimensional representation of the matrix and the physicochemical properties of individual phases as a consequence of the degradation process. This not only makes it possible to study the evolution of such properties as a function of time but also as a function of the position within the matrix. The obtained results are in good agreement with experimental values of the elastic modulus in degraded and undegraded samples.El lixiviado de calcio es un proceso de degradación consistente en la disolución progresiva de la pasta de cemento por la migración de los átomos de calcio a la disolución agresiva. Se trata por tanto de un fenómeno complejo que involucra simultáneamente diferentes fases y procesos de disolución y difusión. En este trabajo se desarrolló y probó una nueva herramienta computacional para la simulación del proceso de degradación en tres dimensiones. Para ello se simuló el lixiviado de calcio acelerado provocado por una disolución de nitrato amónico 6M en matrices de cemento. Como resultado se obtuvieron la representación tridimensional de la matriz y las propiedades físico-químicas sus fases a lo largo del tiempo. Esto permitió estudiar la evolución de dichas propiedades a lo largo del proceso de degradación así como en función de su posición dentro de la matriz. Los resultados obtenidos coinciden con los valores experimentales del módulo elástico tanto
Simulation of Fully Nonlinear 3-D Numerical Wave Tank
Institute of Scientific and Technical Information of China (English)
张晓兔; 滕斌; 宁德志
2004-01-01
A fully nonlinear numerical wave tank (NWT) has been simulated by use of a three-dimensional higher order boundary element method (HOBEM) in the time domain. Within the frame of potential flow and the adoption of simply Rankine source, the resulting boundary integral equation is repeatedly solved at each time step and the fully nonlinear free surface boundary conditions are integrated with time to update its position and boundary values. A smooth technique is also adopted in order to eliminate the possible saw-tooth numerical instabilities. The incident wave at the uptank is given as theoretical wave in this paper. The outgoing waves are absorbed inside a damping zone by spatially varying artificial damping on the free surface at the wave tank end. The numerical results show that the NWT developed by these approaches has a high accuracy and good numerical stability.
Bao, Weizhai; Mondal, Anjon Kumar; Xu, Jing; Wang, Chengyin; Su, Dawei; Wang, Guoxiu
2016-09-01
We report a rational design and synthesis of 3D hybrid-porous carbon with a hierarchical pore architecture for high performance supercapacitors. It contains micropores (3D hybrid-porous carbon demonstrates a specific capacitance of 332 F g-1 at a constant charge/discharge current of 500 mA g-1. The supercapacitors can endure more than 10,000 cycles without degradation of capacitance.
Fajardo, Kristel C Meza; Chaillat, Stéphanie; Lenti, Luca
2016-01-01
In this work, we study seismic wave amplification in alluvial basins having 3D standard geometries through the Fast Multipole Boundary Element Method in the frequency domain. We investigate how much 3D amplification differs from the 1D (horizontal layering) case. Considering incident fields of plane harmonic waves, we examine the relationships between the amplification level and the most relevant physical parameters of the problem (impedance contrast, 3D aspect ratio, vertical and oblique incidence of plane waves). The FMBEM results show that the most important parameters for wave amplification are the impedance contrast and the so-called equivalent shape ratio. Using these two parameters, we derive simple rules to compute the fundamental frequency for various 3D basin shapes and the corresponding 3D/1D amplification factor for 5% damping. Effects on amplification due to 3D basin asymmetry are also studied and incorporated in the derived rules.
An Innovative Hybrid 3D Analytic-Numerical Approach for System Level Modelling of PEM Fuel Cells
Directory of Open Access Journals (Sweden)
Gregor Tavčar
2013-10-01
Full Text Available The PEM fuel cell model presented in this paper is based on modelling species transport and coupling electrochemical reactions to species transport in an innovative way. Species transport is modelled by obtaining a 2D analytic solution for species concentration distribution in the plane perpendicular to the gas-flow and coupling consecutive 2D solutions by means of a 1D numerical gas-flow model. The 2D solution is devised on a jigsaw puzzle of multiple coupled domains which enables the modelling of parallel straight channel fuel cells with realistic geometries. Electrochemical and other nonlinear phenomena are coupled to the species transport by a routine that uses derivative approximation with prediction-iteration. A hybrid 3D analytic-numerical fuel cell model of a laboratory test fuel cell is presented and evaluated against a professional 3D computational fluid dynamic (CFD simulation tool. This comparative evaluation shows very good agreement between results of the presented model and those of the CFD simulation. Furthermore, high accuracy results are achieved at computational times short enough to be suitable for system level simulations. This computational efficiency is owed to the semi-analytic nature of its species transport modelling and to the efficient computational coupling of electrochemical kinetics and species transport.
Computer-assisted three-dimensional surgical planning and simulation: 3D virtual osteotomy.
Xia, J; Ip, H H; Samman, N; Wang, D; Kot, C S; Yeung, R W; Tideman, H
2000-02-01
A computer-assisted three-dimensional virtual osteotomy system for orthognathic surgery (CAVOS) is presented. The virtual reality workbench is used for surgical planning. The surgeon immerses in a virtual reality environment with stereo eyewear, holds a virtual "scalpel" (3D Mouse) and operates on a "real" patient (3D visualization) to obtain pre-surgical prediction (3D bony segment movements). Virtual surgery on a computer-generated 3D head model is simulated and can be visualized from any arbitrary viewing point in a personal computer system.
Simulations of 3D LPI's relevant to IFE using the PIC code OSIRIS
Tsung, F. S.; Mori, W. B.; Winjum, B. J.
2014-10-01
We will study three dimensional effects of laser plasma instabilities, including backward raman scattering, the high frequency hybrid instability, and the two plasmon instability using OSIRIS in 3D Cartesian geometry and cylindrical 2D OSIRIS with azimuthal mode decompositions. With our new capabilities we hope to demonstrate that we are capable of studying single speckle physics relevant to IFE in an efficent manner.
Synergia: A hybrid, parallel beam dynamics code with 3D space charge
Energy Technology Data Exchange (ETDEWEB)
James F. Amundson; Panagiotis Spentzouris
2003-07-09
We describe Synergia, a hybrid code developed under the DOE SciDAC-supported Accelerator Simulation Program. The code combines and extends the existing accelerator modeling packages IMPACT and beamline/mxyzptlk. We discuss the design and implementation of Synergia, its performance on different architectures, and its potential applications.
Numerical simulation of 3D backward facing step flows at various Reynolds numbers
Directory of Open Access Journals (Sweden)
Louda Petr
2015-01-01
Full Text Available The work deals with the numerical simulation of 3D turbulent flow over backward facing step in a narrow channel. The mathematical model is based on the RANS equations with an explicit algebraic Reynolds stress model (EARSM. The numerical method uses implicit finite volume upwind discretization. While the eddy viscosity models fail in predicting complex 3D flows, the EARSM model is shown to provide results which agree well with experimental PIV data. The reference experimental data provide the 3D flow field. The simulations are compared with experiment for 3 values of Reynolds number.
Simulação 3D de movimento ortodôntico 3D simulation of orthodontic tooth movement
Directory of Open Access Journals (Sweden)
Norman Duque Penedo
2010-10-01
Full Text Available OBJETIVO: desenvolver e validar, através do Método dos Elementos Finitos (MEF, um modelo numérico tridimensional (3D de um incisivo central superior para simular o movimento dentário. MÉTODOS: esse modelo contempla a unidade dentária, o osso alveolar e o ligamento periodontal. Permite a simulação dos diferentes movimentos dentários e a determinação dos centros de rotação e de resistência. Limita o movimento ao espaço periodontal, registrando a direção, quantificando o deslocamento dentário e as tensões iniciais no ligamento periodontal. RESULTADOS: a análise dos deslocamentos dentários e das áreas que recebem tensões iniciais possibilita determinar os tipos de movimentos dentários. Com base nas forças ortodônticas, é possível quantificar a intensidade das tensões em cada região do dente, do ligamento periodontal ou do osso alveolar. Com base nas tensões axiais ao longo do ligamento periodontal e da tensão capilar, é possível predizer, teoricamente, as regiões em que deve ocorrer a remodelação óssea. CONCLUSÃO: o modelo foi validado pela determinação do módulo de elasticidade do ligamento periodontal de forma compatível com dados experimentais existentes na literatura. Os métodos utilizados na construção do modelo permitiram a criação de um modelo completo para uma arcada dentária, o qual possibilita realizar variadas simulações que envolvem a mecânica ortodôntica.OBJECTIVE: To develop and validate a three-dimensional (3D numerical model of a maxillary central incisor to simulate tooth movement using the Finite Element Method (FEM. METHODS: This model encompasses the tooth, alveolar bone and periodontal ligament. It allows the simulation of different tooth movements and the establishment of centers of rotation and resistance. It limits the movement into the periodontal space, recording the direction, quantifying tooth displacement and initial stress in the periodontal ligament. RESULTS: By
Tavčar, Gregor; Katrašnik, Tomaž
2014-01-01
The parallel straight channel PEM fuel cell model presented in this paper extends the innovative hybrid 3D analytic-numerical (HAN) approach previously published by the authors with capabilities to address ternary diffusion systems and counter-flow configurations. The model's core principle is modelling species transport by obtaining a 2D analytic solution for species concentration distribution in the plane perpendicular to the cannel gas-flow and coupling consecutive 2D solutions by means of a 1D numerical pipe-flow model. Electrochemical and other nonlinear phenomena are coupled to the species transport by a routine that uses derivative approximation with prediction-iteration. The latter is also the core of the counter-flow computation algorithm. A HAN model of a laboratory test fuel cell is presented and evaluated against a professional 3D CFD simulation tool showing very good agreement between results of the presented model and those of the CFD simulation. Furthermore, high accuracy results are achieved at moderate computational times, which is owed to the semi-analytic nature and to the efficient computational coupling of electrochemical kinetics and species transport. PMID:25125112
The Effects of 3D Computer Simulation on Biology Students' Achievement and Memory Retention
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,…
3D Ag/ZnO hybrids for sensitive surface-enhanced Raman scattering detection
Huang, Chenyue; Xu, Chunxiang; Lu, Junfeng; Li, Zhaohui; Tian, Zhengshan
2016-03-01
To combine the surface plasma resonance of metal and local field enhancement in metal/semiconductor interface, Ag nanoparticles (NPs) were assembled on a ZnO nanorod array which was grown by hydrothermally on carbon fibers. The construction of dimensional (3D) Surface-Enhanced Raman Scattering (SERS) substrate is used for the sensitive detection of organic pollutants with the advantages such as facile synthesis, short detection time and low cost. The hybrid substrate was manifested a high sensitivity to phenol red at a lower concentration of 1 × 10-9 M and a higher enhancement factor of 3.18 × 109. Moreover, the ZnO nanostructures decorated with Ag NPs were demonstrated self-cleaning function under UV irradiation via photocatalytic degradation of the analytic molecules. The fabrication process of the materials and sensors, optimization of the SERS behaviors for different sized Ag NPs, the mechanism of SERS and recovery were presented with a detailed discussion.
ASICs in nanometer and 3D technologies for readout of hybrid pixel detectors
Maj, Piotr; Grybos, Pawel; Kmon, Piotr; Szczygiel, Robert
2013-07-01
Hybrid pixel detectors working in a single photon counting mode are very attractive solutions for material science and medical X-ray imaging applications. Readout electronics of these detectors has to match the geometry of pixel detectors with an area of readout channel of 100 μm × 100 μm (or even less) and very small power consumption (a few tens of μW). New solutions of readout ASICs are going into directions of better spatial resolutions, higher data throughput and more advanced functionality. We report on the design and measurement results of two pixel prototype ASICs in nanometer technology and 3D technology which offer fast signal processing, low noise performance and advanced functionality per single readout pixel cell.
SIMULATION OF HYDRAULIC TRANSIENTS IN HYDROPOWER SYSTEMS USING THE 1-D-3-D COUPLING APPROACH
Institute of Scientific and Technical Information of China (English)
ZHANG Xiao-xi; CHENG Yong-guang
2012-01-01
Although the hydraulic transients in pipe systems are usually simulated by using a one-dimensional (l-D) approach,local three-dimensional (3-D) simulations are necessary because of obvious 3-D flow features in some local regions of the hydropower systems.This paper combines the 1-D method with a 3-D fluid flow model to simulate the Multi-Dimensional (MD) hydraulic transients in hydropower systems and proposes two methods for modeling the compressible watcr with the correct wave speed,and two strategies for efficiently coupling the 1-D and 3-D computational domains.The methods are validated by simulating the water hammer waves and the oscillations of the water level in a surge tank,and comparing the results with the 1 -D solution data.An MD study is conducted for the transient flows in a realistic water conveying system that consists of a draft tube,a tailrace surge tank and a tailrace tunnel.It is shown that the 1-D-3-D coupling approach is an efficient and promising way to simulate the hydraulic transients in the hydropower systems in which the interactions between 1-D hydraulic fluctuations of the pipeline systems and the local 3-D flow patterns should be considered.
Moortgat, Joachim
2016-01-01
Problems of interest in hydrogeology and hydrocarbon resources involve complex heterogeneous geological formations. Such domains are most accurately represented in reservoir simulations by unstructured computational grids. Finite element methods accurately describe flow on unstructured meshes with complex geometries, and their flexible formulation allows implementation on different grid types. In this work, we consider for the first time the challenging problem of fully compositional three-phase flow in 3D unstructured grids, discretized by any combination of tetrahedra, prisms, and hexahedra. We employ a mass conserving mixed hybrid finite element (MHFE) method to solve for the pressure and flux fields. The transport equations are approximated with a higher-order vertex-based discontinuous Galerkin (DG) discretization. We show that this approach outperforms a face-based implementation of the same polynomial order. These methods are well suited for heterogeneous and fractured reservoirs, because they provide ...
3D segmentation of medical images using a fast multistage hybrid algorithm
International Nuclear Information System (INIS)
In this paper, we propose a fast multistage hybrid algorithm for 3D segmentation of medical images. We first employ a morphological recursive erosion operation to reduce the connectivity between the object to be segmented and its neighborhood; then the fast marching method is used to greatly accelerate the initial propagation of a surface front from the user defined seed structure to a surface close to the desired boundary; a morphological reconstruction method then operates on this surface to achieve an initial segmentation result; and finally morphological recursive dilation is employed to recover any structure lost in the first stage of the algorithm. This approach is tested on 60 CT or MRI images of the brain, heart and urinary system, to demonstrate the robustness of this technique across a variety of imaging modalities and organ systems. The algorithm is also validated against datasets for which ''truth'' is known. These measurements revealed that the algorithm achieved a mean ''similarity index'' of 0.966 across the three organ systems. The execution time for this algorithm, when run on a 550 MHz Dual PIII-based PC runningWindows NT, and extracting the cortex from brain MRIs, the cardiac surface from dynamic CT, and the kidneys from 3D CT, was 38, 46 and 23 s, respectively. (orig.)
A hybrid radial basis function-pseudospectral method for thermal convection in a 3-D spherical shell
Wright, G. B.
2010-07-01
A novel hybrid spectral method that combines radial basis function (RBF) and Chebyshev pseudospectral methods in a "2 + 1" approach is presented for numerically simulating thermal convection in a 3-D spherical shell. This is the first study to apply RBFs to a full 3-D physical model in spherical geometry. In addition to being spectrally accurate, RBFs are not defined in terms of any surface-based coordinate system such as spherical coordinates. As a result, when used in the lateral directions, as in this study, they completely circumvent the pole issue with the further advantage that nodes can be "scattered" over the surface of a sphere. In the radial direction, Chebyshev polynomials are used, which are also spectrally accurate and provide the necessary clustering near the boundaries to resolve boundary layers. Applications of this new hybrid methodology are given to the problem of convection in the Earth\\'s mantle, which is modeled by a Boussinesq fluid at infinite Prandtl number. To see whether this numerical technique warrants further investigation, the study limits itself to an isoviscous mantle. Benchmark comparisons are presented with other currently used mantle convection codes for Rayleigh number (Ra) 7 × 10^{3} and 10^{5}. Results from a Ra = 10^{6} simulation are also given. The algorithmic simplicity of the code (mostly due to RBFs) allows it to be written in less than 400 lines of MATLAB and run on a single workstation. We find that our method is very competitive with those currently used in the literature. Copyright 2010 by the American Geophysical Union.
Directory of Open Access Journals (Sweden)
Gabriele Jost
2010-01-01
Full Text Available Today most systems in high-performance computing (HPC feature a hierarchical hardware design: shared-memory nodes with several multi-core CPUs are connected via a network infrastructure. When parallelizing an application for these architectures it seems natural to employ a hierarchical programming model such as combining MPI and OpenMP. Nevertheless, there is the general lore that pure MPI outperforms the hybrid MPI/OpenMP approach. In this paper, we describe the hybrid MPI/OpenMP parallelization of IR3D (Incompressible Realistic 3-D code, a full-scale real-world application, which simulates the environmental effects on the evolution of vortices trailing behind control surfaces of underwater vehicles. We discuss performance, scalability and limitations of the pure MPI version of the code on a variety of hardware platforms and show how the hybrid approach can help to overcome certain limitations.
Earthscape, a Multi-Purpose Interactive 3d Globe Viewer for Hybrid Data Visualization and Analysis
Sarthou, A.; Mas, S.; Jacquin, M.; Moreno, N.; Salamon, A.
2015-08-01
The hybrid visualization and interaction tool EarthScape is presented here. The software is able to display simultaneously LiDAR point clouds, draped videos with moving footprint, volume scientific data (using volume rendering, isosurface and slice plane), raster data such as still satellite images, vector data and 3D models such as buildings or vehicles. The application runs on touch screen devices such as tablets. The software is based on open source libraries, such as OpenSceneGraph, osgEarth and OpenCV, and shader programming is used to implement volume rendering of scientific data. The next goal of EarthScape is to perform data analysis using ENVI Services Engine, a cloud data analysis solution. EarthScape is also designed to be a client of Jagwire which provides multisource geo-referenced video fluxes. When all these components will be included, EarthScape will be a multi-purpose platform that will provide at the same time data analysis, hybrid visualization and complex interactions. The software is available on demand for free at france@exelisvis.com.
EARTHSCAPE, A MULTI-PURPOSE INTERACTIVE 3D GLOBE VIEWER FOR HYBRID DATA VISUALIZATION AND ANALYSIS
Directory of Open Access Journals (Sweden)
A. Sarthou
2015-08-01
Full Text Available The hybrid visualization and interaction tool EarthScape is presented here. The software is able to display simultaneously LiDAR point clouds, draped videos with moving footprint, volume scientific data (using volume rendering, isosurface and slice plane, raster data such as still satellite images, vector data and 3D models such as buildings or vehicles. The application runs on touch screen devices such as tablets. The software is based on open source libraries, such as OpenSceneGraph, osgEarth and OpenCV, and shader programming is used to implement volume rendering of scientific data. The next goal of EarthScape is to perform data analysis using ENVI Services Engine, a cloud data analysis solution. EarthScape is also designed to be a client of Jagwire which provides multisource geo-referenced video fluxes. When all these components will be included, EarthScape will be a multi-purpose platform that will provide at the same time data analysis, hybrid visualization and complex interactions. The software is available on demand for free at france@exelisvis.com.
Carbon Nanofiber/3D Nanoporous Silicon Hybrids as High Capacity Lithium Storage Materials.
Park, Hyeong-Il; Sohn, Myungbeom; Kim, Dae Sik; Park, Cheolho; Choi, Jeong-Hee; Kim, Hansu
2016-04-21
Carbon nanofiber (CNF)/3D nanoporous (3DNP) Si hybrid materials were prepared by chemical etching of melt-spun Si/Al-Cu-Fe alloy nanocomposites, followed by carbonization using a pitch. CNFs were successfully grown on the surface of 3DNP Si particles using residual Fe impurities after acidic etching, which acted as a catalyst for the growth of CNFs. The resulting CNF/3DNP Si hybrid materials showed an enhanced cycle performance up to 100 cycles compared to that of the pristine Si/Al-Cu-Fe alloy nanocomposite as well as that of bare 3DNP Si particles. These results indicate that CNFs and the carbon coating layer have a beneficial effect on the capacity retention characteristics of 3DNP Si particles by providing continuous electron-conduction pathways in the electrode during cycling. The approach presented here provides another way to improve the electrochemical performances of porous Si-based high capacity anode materials for lithium-ion batteries. PMID:26970098
3D-Simulation und Planung von Anlagen der Hütten- und Walzwerkstechnik
Oppermann, Ingo
2009-01-01
In der Präsentation werden typische Engineeringaufgaben präsentiert, die mit modernen IT-Werkzeugen erledigt werden. Es wird auf die Einführung und die Durchgängigkeit eines 3D-CAD-Systems eingegangen und gezeigt, wie mit diesem System Simulations- und Prozesskettenthemen in der Praxis bei der SMS Siemag AG behandelt werden. Ebenfalls anhand von Beispielen wird die Thematik der großen Baugruppen und der Anlagenplanung im 3D-Engineering dargestellt.
Web-Based 3D and Haptic Interactive Environments for e-Learning, Simulation, and Training
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.
Completion of PCFLOW3D Model for Simulation of Flow and Dispersion of Pollutants
Kovšca, Jasna
2007-01-01
An upgrade of the three-dimensional baroclinic mathematical model PCFLOW3D with a new turbulence model Smagorinsky-vertical is presented. Several test cases were made to compare this new turbulence model with other turbulence models already built in the PCFLOW3D model. Additional verifications of the test results were performed using the commercial software CORMIX of which main purpose is to simulate the near field areas of pollution inflows. CORMIX is restricted to steady flow...
3D Simulation of External Flooding Events for the RISMC Pathway
International Nuclear Information System (INIS)
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.
3D Simulation of External Flooding Events for the RISMC Pathway
Energy Technology Data Exchange (ETDEWEB)
Prescott, Steven [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sampath, Ramprasad [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lin, Linyu [Idaho National Lab. (INL), Idaho Falls, ID (United States)
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.
Energy Technology Data Exchange (ETDEWEB)
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.
Application of 3-D numerical simulation software SRIFCAST to produce ductile iron castings
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
Based on a method using numerical simulation equations and their solution schemes for liquid metal flows and heat transfer during mold filling and the solidification process of casting, 3-D numerical simulation software SRIFCAST was created. This includes enmeshment of casting; velocity and temperature fields calculation; displaying iso-temperature lines;velocity vectors and 3-D temperature fields on a Windows 9x operating system. SRIFCAST was applied to produce sound castings of automobile and diesel engines, and also to connect with microstructure simulation for ductile iron castings.
The M3D-C1 Approach to Simulating 3D 2-fluid Magnetohydrodynamics in Magnetic Fusion Experiments
International Nuclear Information System (INIS)
A new approach for solving the 3D MHD equations in a strongly magnetized toroidal plasma is presented which uses high-order 2D finite elements with C1 continuity. The vector fields use a physics-based decomposition. An efficient implicit time advance separates the velocity and field advance. ITAPS (SCOREC) adaptivity software and TOPS solvers are used
Calculation of residual stresses by means of a 3D numerical weld simulation
Energy Technology Data Exchange (ETDEWEB)
Nicak, Tomas; Huemmer, Matthias [AREVA NP GmbH, Postfach 1109 (Germany)
2008-07-01
The numerical weld simulation has developed very fast in recent years. The problem complexity has increased from simple 2D models to full 3D models, which can describe the entire welding process more realistically. As recent research projects indicate, a quantitative assessment of the residual stresses by means of a 3D analysis is possible. The structure integrity can be assessed based on the weld simulation results superimposed with the operating load. Moreover, to support the qualification of welded components parametric studies for optimization of the residual stress distribution in the weld region can be performed. In this paper a full 3D numerical weld simulation for a man-hole drainage nozzle in a steam generator will be presented. The residual stresses are calculated by means of an uncoupled transient thermal and mechanical FE analysis. The paper will present a robust procedure allowing reasonable predictions of the residual stresses for complex structures in industrial practice. (authors)
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
Simulating binocular vision for no-reference 3D visual quality measurement.
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
3D Tracking and Positioning of Surgical Instruments in Virtual Surgery Simulation
Directory of Open Access Journals (Sweden)
Zhaoliang Duan
2011-12-01
Full Text Available 3D tracking and positioning of surgical instruments is an indispensable part of virtual Surgery training system, because it is the unique interface for trainee to communicate with virtual environment. A suit of 3D tracking and positioning of surgical instruments based on stereoscopic vision is proposed. It can capture spatial movements of simulated surgical instrument in real time, and provide 6 degree of freedom information with the absolute error of less than 1 mm. The experimental results show that the 3D tracking and positioning of surgical instruments is highly accurate, easily operated, and inexpensive. Combining with force sensor and embedded acquisition device, this 3D tracking and positioning method can be used as a measurement platform of physical parameters to realize the measurement of soft tissue parameters.
Mixed reality orthognathic surgical simulation by entity model manipulation and 3D-image display
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.
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.
Simulation of Missing Pellet Surface thermal behavior with 3D dynamic gap element
International Nuclear Information System (INIS)
Most of the fuel performance codes that are able to simulate a multidimensional analysis are used to calculate the radial temperature distribution and perform a multidimensional mechanical analysis based on a one-dimensional (1D) temperature result. The FRAPCON-FRAPTRAN code system incorporates a 1D thermal module and two-dimensional (2D) mechanical module when FEM option is activated. In this method, the multidimensional gap conductance model is not required because one-dimensional thermal analysis is carried out. On the other hand, a gap conductance model for a multi-dimension should be developed in the code to perform a multidimensional thermal analysis. ALCYONE developed by CEA introduces an equivalent heat convection coefficient that represents the multidimensional gap conductance. However, the code does not employ dynamic gap conductance which is a function of gap thickness and gap characteristics in direct. The BISON code, which has been developed by INL (Idaho National Laboratory), employed a thermo-mechanical contact method that is specifically designed for tightly-coupled implicit solutions that employ Jacobian-free solution methods. Owing to tightly-coupled implicit solutions, the BISON code solves gap conductance and gap thickness simultaneously with given boundary conditions. In this paper, 3D dynamic gap element has been proposed to resolve convergence issue and nonlinear characteristic of multidimensional gap conductance. To evaluate 3D dynamic gap element module, 3D thermomechanical module using FORTRAN77 has been implemented incorporating 3D dynamic gap element. To demonstrate effect of 3D dynamic gap element, thermal behavior of missing pellet surface (MPS) has been simulated by the developed module. LWR fuel performance codes should incorporate thermo-mechanical loop to solve gap conductance problem, iteratively. However, gap conductance in multidimensional model is difficult issue owing to its nonlinearity and convergence characteristics. In
Study of 3-D Numerical Simulation for Gas Transfer in the Goaf of the Coal Mining
Institute of Scientific and Technical Information of China (English)
WU Zheng-yan; JIANG Shu-guang; HE Xin-jian; WANG Lan-yun; LIN Bai-quan
2007-01-01
In order to simulate field distribution rules, mathematical models for 3-D air flows and gas transfer in the goaf of the coal mining are established, based on theories of permeability and dynamic dispersion through porous media. A gas dispersion equation in a 3-D field is calculated by use of numerical method on a weighted upstream multi-element balance. Based on data of an example with a U type ventilation mode, surface charts of air pressure distribution and gas concentration are drawn by Graphtool software. Finally, a comparison between actually measured results in the model test and the numerical simulation results is made to proves the numerical implementation feasible.
3-D NUMERICAL SIMULATION OF FLOW THROUGH AN ORIFICE SPILL-WAY TUNNEL
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
A Large Eddy Simulation (LES) approachbased on the weakly compressible hydrodynamic equation with a single-plase fluid model for the cavitation flow has been de-veloped and employed in simulating 3-D unsteady viscous flowthrough an orifice type spillwy tunnel. The finite volume ap-proach in space and the predictor-corrector method in timehave been used to the numerical discretization, and the "Lawof wall" is applied at the solid boundary. The velocity, pres-sure fields and the cavitation phenomenon are obtained, thecomputational results show that 3-D LES approach can givemore realistic flow field prediction of the orifice type spillwaytunnel.
Detached eddy simulation of unsteady cavitation and pressure fluctuation around 3-D NACA66 hydrofoil
Directory of Open Access Journals (Sweden)
Zhang De-Sheng
2015-01-01
Full Text Available The unsteady cavitating flow and pressure fluctuation around the 3-D NACA66 hydrofoil were simulated and validated based on detached eddy simulation turbulence model and a homogeneous cavitation model. Numerical results show that detached eddy simulation can predict the evolution of cavity inception, sheet cavitation growth, cloud cavitation shedding, and breakup, as well as the pressure fluctuation on the surface of hydrofoil. The sheet cavitation growth, detachment, cloud cavitation shedding are responsible for the features of the pressure fluctuation.
Ground motion simulations in Marmara (Turkey) region from 3D finite difference method
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.
Real-Time 3D Face Acquisition Using Reconfigurable Hybrid Architecture
Directory of Open Access Journals (Sweden)
Mitéran Johel
2007-01-01
Full Text Available Acquiring 3D data of human face is a general problem which can be applied in face recognition, virtual reality, and many other applications. It can be solved using stereovision. This technique consists in acquiring data in three dimensions from two cameras. The aim is to implement an algorithmic chain which makes it possible to obtain a three-dimensional space from two two-dimensional spaces: two images coming from the two cameras. Several implementations have already been considered. We propose a new simple real-time implementation based on a hybrid architecture (FPGA-DSP, allowing to consider an embedded and reconfigurable processing. Then we show our method which provides depth map of face, dense and reliable, and which can be implemented on an embedded architecture. A various architecture study led us to a judicious choice allowing to obtain the desired result. The real-time data processing is implemented in an embedded architecture. We obtain a dense face disparity map, precise enough for considered applications (multimedia, virtual worlds, biometrics and using a reliable method.
Development of hybrid 3-D hydrological modeling for the NCAR Community Earth System Model (CESM)
Energy Technology Data Exchange (ETDEWEB)
Zeng, Xubin [Univ. of Arizona, Tucson, AZ (United States); Troch, Peter [Univ. of Arizona, Tucson, AZ (United States); Pelletier, Jon [Univ. of Arizona, Tucson, AZ (United States); Niu, Guo-Yue [Univ. of Arizona, Tucson, AZ (United States); Gochis, David [NCAR Research Applications (RAL), Boulder, CO (United States)
2015-11-15
This is the Final Report of our four-year (3-year plus one-year no cost extension) collaborative project between the University of Arizona (UA) and the National Center for Atmospheric Research (NCAR). The overall objective of our project is to develop and evaluate the first hybrid 3-D hydrological model with a horizontal grid spacing of 1 km for the NCAR Community Earth System Model (CESM). We have made substantial progress in model development and evaluation, computational efficiencies and software engineering, and data development and evaluation, as discussed in Sections 2-4. Section 5 presents our success in data dissemination, while Section 6 discusses the scientific impacts of our work. Section 7 discusses education and mentoring success of our project, while Section 8 lists our relevant DOE services. All peer-reviewed papers that acknowledged this project are listed in Section 9. Highlights of our achievements include: • We have finished 20 papers (most published already) on model development and evaluation, computational efficiencies and software engineering, and data development and evaluation • The global datasets developed under this project have been permanently archived and publicly available • Some of our research results have already been implemented in WRF and CLM • Patrick Broxton and Michael Brunke have received their Ph.D. • PI Zeng has served on DOE proposal review panels and DOE lab scientific focus area (SFA) review panels
A Jones matrix formalism for simulating 3D Polarised Light Imaging of brain tissue
Menzel, Miriam; De Raedt, Hans; Reckfort, Julia; Amunts, Katrin; Axer, Markus
2015-01-01
The neuroimaging technique 3D Polarised Light Imaging (3D-PLI) provides a high-resolution reconstruction of nerve fibres in human post-mortem brains. The orientations of the fibres are derived from birefringence measurements of histological brain sections assuming that the nerve fibres - consisting of an axon and a surrounding myelin sheath - are uniaxial birefringent and that the measured optic axis is oriented in direction of the nerve fibres (macroscopic model). Although experimental studies support this assumption, the molecular structure of the myelin sheath suggests that the birefringence of a nerve fibre can be described more precisely by multiple optic axes oriented radially around the fibre axis (microscopic model). In this paper, we compare the use of the macroscopic and the microscopic model for simulating 3D-PLI by means of the Jones matrix formalism. The simulations show that the macroscopic model ensures a reliable estimation of the fibre orientations as long as the polarimeter does not resolve ...
3D numerical simulation analysis of passive drag near free surface in swimming
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.
3D Numerical Simulation Analysis of Passive Drag near Free Surface in Swimming
Institute of Scientific and Technical Information of China (English)
詹杰民; 李天赠; 陈学彬; 李毓湘; 韦永康
2015-01-01
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-εturbulence 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.
GRASIL-3D: an Implemention of Dust Effects in the SEDs of Simulated Galaxies
Domínguez-Tenreiro, R; Granato, G L; Schurer, A; Alpresa, P; Silva, L; Brook, C B; Serna, A
2013-01-01
We introduce a new model for the spectral energy distribution of galaxies, GRASIL-3D, which includes a careful modelling of the dust component of the interstellar medium. GRASIL-3D is an entirely new model based on the formalism of an existing and widely applied spectrophotometric model, GRASIL, but specifically designed to be interfaced with galaxies with any arbitrarily given geometry, such as galaxies calculated by theoretical hydrodynamical galaxy formation codes. GRASIL-3D is designed to separately treat radiative transfer in molecular clouds and in the diffuse cirrus component. The code has a general applicability to the outputs of simulated galaxies, either from Lagrangian or Eulerian hydrodynamic codes. As an application, the new model has been interfaced to the P-DEVA and GASOLINE smoothed-particle hydrodynamic codes, and has been used to calculate the spectral energy distribution for a variety of simulated galaxies from UV to sub-millimeter wavelengths, whose comparison with observational data gives...
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.
Simulation of Asymmetric Destabilization of Mine-void Rock Masses Using a Large 3D Physical Model
Lai, X. P.; Shan, P. F.; Cao, J. T.; Cui, F.; Sun, H.
2016-02-01
When mechanized sub-horizontal section top coal caving (SSTCC) is used as an underground mining method for exploiting extremely steep and thick coal seams (ESTCS), a large-scale surrounding rock caving may be violently created and have the potential to induce asymmetric destabilization from mine voids. In this study, a methodology for assessing the destabilization was developed to simulate the Weihuliang coal mine in the Urumchi coal field, China. Coal-rock mass and geological structure characterization were integrated with rock mechanics testing for assessment of the methodology and factors influencing asymmetric destabilization. The porous rock-like composite material ensured accuracy for building a 3D geological physical model of mechanized SSTCC by combining multi-mean timely track monitoring including acoustic emission, crack optical acquirement, roof separation observation, and close-field photogrammetry. An asymmetric 3D modeling analysis for destabilization characteristics was completed. Data from the simulated hydraulic support and buried pressure sensor provided effective information that was linked with stress-strain relationship of the working face in ESTCS. The results of the 3D physical model experiments combined with hybrid statistical methods were effective for predicting dynamic hazards in ESTCS.
Simulation System Design of 3-D Panorama of Ship Motions in Wave
Institute of Scientific and Technical Information of China (English)
LIU; Ya-dong; LI; Ji-de; LI; Zhen
2002-01-01
In this paper a 3-D panoramic simulation system of a ship is described which is developed with the MAXSCRIPT language and VC++ as programming tools on the platform of 3Dsmax. The strip theory method is applied to the motion prediction of the mono-hull. The time history solutions of heave and pitch are obtained in the condition of head sea to provide the primary data on panoramic simulation. The simulation system has following functions: 1)digital simulation;2) panoramic simulation; 3) environmental set-up; 4) render preview and output.
Renal Tumor Cryoablation Planning. The Efficiency of Simulation on Reconstructed 3D CT Scan
Directory of Open Access Journals (Sweden)
Ciprian Valerian LUCAN
2010-12-01
Full Text Available Introduction & Objective: Nephron-sparing surgical techniques risks are related to tumor relationships with adjacent anatomic structures. Complexity of the renal anatomy drives the interest to develop tools for 3D reconstruction and surgery simulation. The aim of the article was to assess the simulation on reconstructed 3D CT scan used for planning the cryoablation. Material & Method: A prospective randomized study was performed between Jan. 2007 and July 2009 on 27 patients who underwent retroperitoneoscopic T1a renal tumors cryoablation (RC. All patients were assessed preoperatively by CT scan, also used for 3D volume rendering. In the Gr.A, the patients underwent surgery planning by simulation on 3D CT scan. In the Gr.B., patients underwent standard RC. The two groups were compared in terms of surgical time, bleeding, postoperative drainage, analgesics requirement, hospital stay, time to socio-professional reintegration. Results: Fourteen patients underwent preoperative cryoablation planning (Gr.A and 13 patients underwent standard CR (Gr.B. All parameters analyzed were shorter in the Gr.A. On multivariate logistic regression, only shortens of the surgical time (138.79±5.51 min. in Gr.A. vs. 140.92±5.54 min in Gr.B. and bleeding (164.29±60.22 mL in Gr.A. vs. 215.38±100.80 mL in Gr.B. achieved statistical significance (p<0.05. The number of cryoneedles assessed by simulation had a 92.52% accuracy when compared with those effectively used. Conclusions: Simulation of the cryoablation using reconstructed 3D CT scan improves the surgical results. The application used for simulation was able to accurately assess the number of cryoneedles required for tumor ablation, their direction and approach.
Simulation of free surfaces in 3-D with the arbitrary Lagrange-Euler method
DEFF Research Database (Denmark)
Szabo, Peter; Hassager, Ole
1995-01-01
The arbitrary Lagrange-Euler (ALE) kinematic description has been implemented in a 3-D transient finite element program so as to simulate multiple fluid flows with Surfaces and interfaces of general shapes. The description of fluid interfaces includes continuity of velocity and a discontinuous...
An Object-Oriented Simulator for 3D Digital Breast Tomosynthesis Imaging System
Directory of Open Access Journals (Sweden)
Saeed Seyyedi
2013-01-01
Full Text Available 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.
Moortgat, Joachim; Firoozabadi, Abbas
2016-06-01
Problems of interest in hydrogeology and hydrocarbon resources involve complex heterogeneous geological formations. Such domains are most accurately represented in reservoir simulations by unstructured computational grids. Finite element methods accurately describe flow on unstructured meshes with complex geometries, and their flexible formulation allows implementation on different grid types. In this work, we consider for the first time the challenging problem of fully compositional three-phase flow in 3D unstructured grids, discretized by any combination of tetrahedra, prisms, and hexahedra. We employ a mass conserving mixed hybrid finite element (MHFE) method to solve for the pressure and flux fields. The transport equations are approximated with a higher-order vertex-based discontinuous Galerkin (DG) discretization. We show that this approach outperforms a face-based implementation of the same polynomial order. These methods are well suited for heterogeneous and fractured reservoirs, because they provide globally continuous pressure and flux fields, while allowing for sharp discontinuities in compositions and saturations. The higher-order accuracy improves the modeling of strongly non-linear flow, such as gravitational and viscous fingering. We review the literature on unstructured reservoir simulation models, and present many examples that consider gravity depletion, water flooding, and gas injection in oil saturated reservoirs. We study convergence rates, mesh sensitivity, and demonstrate the wide applicability of our chosen finite element methods for challenging multiphase flow problems in geometrically complex subsurface media.
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.
Institute of Scientific and Technical Information of China (English)
WANG Xin-yun; GUO Zhi-feng; QINWen-hans; 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 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.
The Vajont disaster: a 3D numerical simulation for the slide and the waves
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.
The computer simulation of 3d gas dynamics in a gas centrifuge
Borman, V. D.; Bogovalov, S. V.; Borisevich, V. D.; Tronin, I. V.; Tronin, V. N.
2016-09-01
We argue on the basis of the results of 2D analysis of the gas flow in gas centrifuges that a reliable calculation of the circulation of the gas and gas content in the gas centrifuge is possible only in frameworks of 3D numerical simulation of gas dynamics in the gas centrifuge (hereafter GC). The group from National research nuclear university, MEPhI, has created a computer code for 3D simulation of the gas flow in GC. The results of the computer simulations of the gas flows in GC are presented. A model Iguassu centrifuge is explored for the simulations. A nonaxisymmetric gas flow is produced due to interaction of the hypersonic rotating flow with the scoops for extraction of the product and waste flows from the GC. The scoops produce shock waves penetrating into a working camera of the GC and form spiral waves there.
Finite Volume Particle Method for 3-D Elasto-Plastic Solid Simulation
Jahanbakhsh, Ebrahim; Vessaz, Christian; Avellan, François
2014-01-01
Finite Volume Particle Method was successfully used to predict fluid flow behavior for 2-D simulations. In this paper, we present a FVPM which is applicable for 3-D solid mechanics simulations. This method features rectangular top-hat kernels for computing the interaction vectors exactly and efficiently. We employed this method to solve the elasto-plastic constitutive equations. To validate the model, we study the impact of rigid spherical particle to the solid surface with different velociti...
3D CFD Simulations of MOCVD Synthesis System of Titanium Dioxide Nanoparticles
Siti Hajar Othman; Suraya Abdul Rashid; Tinia Idaty Mohd Ghazi; Norhafizah Abdullah
2013-01-01
This paper presents the 3-dimensional (3D) computational fluid dynamics (CFD) simulation study of metal organic chemical vapor deposition (MOCVD) producing photocatalytic titanium dioxide (TiO2) nanoparticles. It aims to provide better understanding of the MOCVD synthesis system especially of deposition process of TiO2 nanoparticles as well as fluid dynamics inside the reactor. The simulated model predicts temperature, velocity, gas streamline, mass fraction of reactants and products, kinetic...
Neutron-induced complex reaction analysis with 3D nuclear track simulation
International Nuclear Information System (INIS)
Complex (multiple) etched tracks are analysed through digitised images and 3D simulation by a purpose-built algorithm. From a binary track image an unfolding procedure is followed to generate a 3D track model, from which several track parameters are estimated. The method presented here allows the deposited energy, that originated from particle fragmentation or carbon spallation by means of induced tracks in commercially available PADC detectors, to be estimated. Results of evaluated nuclear tracks related to 12C (n,3αn') reaction are presented here. The detectors were exposed on the ISS in 2001
Bao, Weizhai; Mondal, Anjon Kumar; Xu, Jing; Wang, Chengyin; Su, Dawei; Wang, Guoxiu
2016-09-01
We report a rational design and synthesis of 3D hybrid-porous carbon with a hierarchical pore architecture for high performance supercapacitors. It contains micropores (<2 nm diameter) and mesopores (2-4 nm), derived from carbonization of unique porous metal organic frameworks (MOFs). Owning to the synergistic effect of micropores and mesopores, the hybrid-porous carbon has exceptionally high ion-accessible surface area and low ion diffusion resistance, which is desired for supercapacitor applications. When applied as electrode materials in supercapacitors, 3D hybrid-porous carbon demonstrates a specific capacitance of 332 F g-1 at a constant charge/discharge current of 500 mA g-1. The supercapacitors can endure more than 10,000 cycles without degradation of capacitance.
3D FEM Simulation of Rolling Load Working on Piercer Plug in Mannesmann Piercing Process
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.
Simulations of 3D-Si sensors for the innermost layer of the ATLAS pixel upgrade
Baselga, Marta; Quirion, David
2016-01-01
The LHC is expected to reach luminosities up to 3000fb-1 and the innermost layer of the ATLAS upgrade plans to cope with higher occupancy and to decrease the pixel size. 3D-Si sensors are a good candidate for the innermost layer of the ATLAS pixel upgrade since they exhibit good performance under high fluences and the new designs will have smaller pixel size to fulfill the electronics expectations. This paper reports TCAD simulations of the 3D-Si sensors designed at IMB-CNM with non passing-through columns that are being fabricated for the next innermost layer of the ATLAS pixel upgrade, shows the charge collection response before and after irradiation, and the response of 3D-Si sensors located at large $\\eta$ angles.
Simulation of bootstrap current in 2D and 3D ideal magnetic fields in tokamaks
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.
Numerical Simulation of Injection Molding Cooling Process Based on 3D Surface Model
Institute of Scientific and Technical Information of China (English)
CUIShu-biao; ZHOUHua-min; LIDe-qun
2004-01-01
The design of the coohng system of injection molds directly affects both productivity and the quality of the final part. Using the cooling process CAE system to instruct the mold design, the efficiency and quality of design can be improved greatly. At the same time, it is helpful to confirm the cooling system structure and optimize the process conditions. In this paper, the 3D surface model of mold cavity is used to replace the middle-plane model in the simulation by Boundary Element Method, which break the bottleneck of the application of the injection molding simulation softwares base on the middle-plane model. With the improvements of this paper, a practical and commercial simulation software of injection molding cooling process named as HsCAE3D6.0 is developed.
Twisting Rolls. Heuristic Model and 3D Numerical Simulation of Vortex Patterns
Bouali, S
2003-01-01
We connect an appropriate feedback loop to a model of 2D vertical eddy of airflow which unfolds a wide range of vorticity behavior. Computational fluid dynamics of the twisted roll display a class of long lifespan 3D vortices. On the one hand, the infinitely stable columnar vortex simulated describes waterspouts and tornadoes with extended lifetime. On the other hand, a light modification of the retroaction exhibits strong similarities to tropical cyclones. Moreover, we investigate the outcome of the twisting process vertically shifted. This modelisation leads to the simulation of simultaneous vortices associated to this other class of 3D vortices with short lifespan. Our heuristic dynamical systems lay the foundations of a comprehensive modelisation of vortices since it joins numerical simulations and theory.
Digital simulation of 3D turbulence wind field of Sutong Bridge based on measured wind spectra
Institute of Scientific and Technical Information of China (English)
Hao WANG; Zhou-hong ZONG; Ai-qun LI; Teng TONG; Jie NIU; Wen-ping DENG
2012-01-01
Time domain analysis is an essential implement to study the buffeting behavior of long-span bridges for it can consider the non-linear effect which is significant in long-span bridges.The prerequisite of time domain analysis is the accurate description of 3D turbulence winds.In this paper,some hypotheses for simplifying the 3D turbulence simulation of long-span cable-stayed bridges are conducted,considering the structural characteristics.The turbulence wind which is a 3D multivariate stochastic vector process is converted into four independent ID univariate stochastic processes.Based on recorded wind data from structural health monitoring system (SHMS) of the Sutong Bridge,China,the measured spectra expressions are then presented using the nonlinear least-squares fitting method.Turbulence winds at the Sutong Bridge site are simulated based on the spectral representation method and the Fast Fourier transform (FFT) technique,and the relevant results derived from target spectra including measured spectra and recommended spectra are compared.The reliability and accuracy of the presented turbulence simulation method are validated through comparisons between simulated and target spectra (measured and recommended spectra).The obtained turbulence simulations can not only serve further analysis of the buffeting behavior of the Sutong Bridge,but references for structural anti-wind design in adjacent regions.
The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis
Energy Technology Data Exchange (ETDEWEB)
Shaheen, Eman; Van Ongeval, Chantal; Zanca, Federica; Cockmartin, Lesley; Marshall, Nicholas; Jacobs, Jurgen; Young, Kenneth C.; Dance, David R.; Bosmans, Hilde [Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford, GU2 7XX (United Kingdom); Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium)
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
The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis
International Nuclear Information System (INIS)
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
Numerical simulation of 3D boundary-driven acoustic streaming in microfluidic devices.
Lei, Junjun; Hill, Martyn; Glynne-Jones, Peter
2014-02-01
This article discusses three-dimensional (3D) boundary-driven streaming in acoustofluidic devices. Firstly, the 3D Rayleigh streaming pattern in a microchannel is simulated and its effect on the movement of microparticles of various sizes is demonstrated. The results obtained from this model show good comparisons with 3D experimental visualisations and demonstrate the fully 3D nature of the acoustic streaming field and the associated acoustophoretic motion of microparticles in acoustofluidic devices. This method is then applied to another acoustofluidic device in order to gain insights into an unusual in-plane streaming pattern. The origin of this streaming has not been fully described and its characteristics cannot be explained from the classical theory of Rayleigh streaming. The simulated in-plane streaming pattern was in good agreement with the experimental visualisation. The mechanism behind it is shown to be related to the active sound intensity field, which supports our previous findings on the mechanism of the in-plane acoustic streaming pattern visualised and modelled in a thin-layered capillary device.
Capability of coupled 3-D neutronics/thermalhydraulic models to simulate spatial-time effects
International Nuclear Information System (INIS)
Last advancements in computer technology made possible the incorporation on full three-dimensional reactor core model into system transient codes. Best-estimate simulations of interactions between reactor core behavior and plant dynamics have been allowed with 3D neutronics/thermalhydraulic coupled codes. Among these codes, the RELAP5-3D has been applied to the Main Steam Line Break accident to perform three-dimensional core behavior analysis. The advantage of using a 3-D neutronics/thermalhydraulic codes is more evident in the study of strongly asymmetric transient for which simple neutron point kinetic and 1-D thermalhydraulic models are not able to provide an acceptable physical representation of the phenomena that occur in the core. The main objective of this document is to demonstrate the capability to simulated complex spatial-time effects with 3-D coupled codes. Different core nodalizations and coupling schemes have been set up. This has shown that the methodology adopted and the computational tools allow accounting for different detail levels in the core representation. (author)
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.
Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments
International Nuclear Information System (INIS)
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. (paper)
Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.
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
3D thermal modeling of TRISO fuel coupled with neutronic simulation
Energy Technology Data Exchange (ETDEWEB)
Hu, Jianwei [Los Alamos National Laboratory; Uddin, Rizwan [UNIV OF ILLINIOS
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.
Clementel, N; 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 forbidde...
The Surface of Stellar Models - Now with more 3D simulations!
Directory of Open Access Journals (Sweden)
Trampedach Regner
2015-01-01
Full Text Available We have constructed a grid of 3D hydrodynamic simulations of deep convective and line-blanketed atmospheres. We have developed a new consistent method for computing and employing T(τ relations from these simulations, as surface boundary conditions for 1D stellar structure models. These 1D models have, in turn, had their mixing-length, α, calibrated against the averaged structure of each of the simulations. Both α and T(τ vary significantly with Teff and log g.
A Virtual Erection Simulation System for a Steel Structure Based on 3-D Measurement Data
Institute of Scientific and Technical Information of China (English)
Deok Eun Kim; Tuo Han Chen
2012-01-01
The virtual erection simulation system was explained for a steel structure including ship and ocean plant blocks.The simulation system predicted the erection state to optimize any gap or overlap of blocks based on 3-D measurement data.The blocks were modified (cut) on the basis of the simulation result on the ground before erecting them by crane.The re-cutting process was not required and the blocks were erected into a mother ship speedily.Therefore,the erection time is reduced,increasing the dock turnover.
3D Simulations of MHD Jet Propagation Through Uniform and Stratified External Environments
O'Neill, S. M.; Tregillis, I. L.; Jones, T. W.; Ryu, Dongsu
2005-01-01
We present a set of high-resolution 3D MHD simulations of steady light, supersonic jets, exploring the influence of jet Mach number and the ambient medium on jet propagation and energy deposition over long distances. The results are compared to simple self-similar scaling relations for the morphological evolution of jet-driven structures and to previously published 2D simulations. For this study we simulated the propagation of light jets with internal Mach numbers 3 and 12 to lengths exceedin...
3D modeling and simulation of 2G HTS stacks and coils
International Nuclear Information System (INIS)
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. (paper)
A WEB 2.0/WEB3D HYBRID PLATFORM FOR ENGAGING STUDENTS IN E-LEARNING ENVIRONMENTS
Directory of Open Access Journals (Sweden)
Penny de BYL
2007-07-01
Full Text Available ABSTRACTThis paper explores the Web 2.0 ethos with respect to the application of pedagogy within 3D online virtual environments. 3D worlds can create a synthetic experience capturing the essence of being in a particular world or context. The AliveX3D platform adopts the Web 2.0 ethos and applies it to online 3D virtual environment forming a Web 2.0/Web3D hybrid that has wider usability than previous alternatives. This combined with the AliveX3D Scene Editor allows learning experiences, which are controlled by the learner, appear authentic and facilitate collaboration conversations to be developed simultaneously. This immersion enables learners to negotiate meaning based on their own personal cognitive, affective and kinaesthetic experiences rather than on the descriptions of others’ experiences. We conclude by suggesting the choices embedded within the worlds allow the learning focus to shift away from isolated pre-designed interactions, to a situation that encourages the learner to control, manage and direct their own learning.
Momentum Transport: 2D and 3D Cloud Resolving Model Simulations
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.
Hagiwara, Masaya; Kawahara, Tomohiro; Nobata, Rina
2016-07-01
An in vitro 3D culturing platform enabling multidirectional observations of 3D biosamples is presented by M. Hagiwara and co-workers on page 1566. 3D recognition of a sample structure can be achieved by facilitating multi-directional views using a standard microscope without a laser system. The cubic platform has the potential to promote 3D culture studies, offering easy handling and compatibility with commercial culture plates at a low price tag. PMID:27384934
Confocal 3D DNA Cytometry: Assessment of Required Coefficient of Variation by Computer Simulation
Directory of Open Access Journals (Sweden)
Lennert S. Ploeger
2004-01-01
Full Text Available Background: Confocal Laser Scanning Microscopy (CLSM provides the opportunity to perform 3D DNA content measurements on intact cells in thick histological sections. So far, sample size has been limited by the time consuming nature of the technology. Since the power of DNA histograms to resolve different stemlines depends on both the sample size and the coefficient of variation (CV of histogram peaks, interpretation of 3D CLSM DNA histograms might be hampered by both a small sample size and a large CV. The aim of this study was to analyze the required CV for 3D CLSM DNA histograms given a realistic sample size. Methods: By computer simulation, virtual histograms were composed for sample sizes of 20000, 10000, 5000, 1000, and 273 cells and CVs of 30, 25, 20, 15, 10 and 5%. By visual inspection, the histogram quality with respect to resolution of G0/1 and G2/M peaks of a diploid stemline was assessed. Results: As expected, the interpretability of DNA histograms deteriorated with decreasing sample sizes and higher CVs. For CVs of 15% and lower, a clearly bimodal peak pattern with well distinguishable G0/1 and G2/M peaks were still seen at a sample size of 273 cells, which is our current average sample size with 3D CLSM DNA cytometry. Conclusions: For unambiguous interpretation of DNA histograms obtained using 3D CLSM, a CV of at most 15% is tolerable at currently achievable sample sizes. To resolve smaller near diploid stemlines, a CV of 10% or better should be aimed at. With currently available 3D imaging technology, this CV is achievable.
On 3D simulation of moving objects in a digital earth system
Institute of Scientific and Technical Information of China (English)
2008-01-01
"How do the rescue helicopters find out an optimized path to arrive at the site of a disaster as soon as possible?" or "How are the flight procedures over mountains and plateaus simulated?" and so on.In this paper a script language on spatial moving objects is presented by abstracting 3D spatial moving objects’ behavior when implementing moving objects simulation in 3D digital Earth scene,which is based on a platform of digital China named "ChinaStar".The definition of this script language,its morphology and syntax,its compiling and mediate language generating,and the behavior and state control of spatial moving objects are discussed emphatically.In addition,the language’s applications and implementation are also discussed.
3D Kinetic Simulations of Topography-Induced Electric Fields at Itokawa Asteroid
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.
3D COMPUTER SIMULATION FOR LIGNIFICATION OF ANCIENT CHINESE TIMBER BUILDINGS
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A pioneer research work was carried out by investigators engaged in surveying and mapping for describing ancient Chinese timber buildings by 3D frame graphs w ith a computer.Users can know the structural layers and the assembly process of the se buildings if the frame graphs are processed further with a computer model.Th is can be implemented by computer simulation technique.This technique display t he raw data on the screen of a computer and interactively manage them by combini ng technologies from computer graphics and image processing,multi-media technol ogy,artificial intelligence,highly parallel real-time computation technique an d human behavior science.This paper presents the implementing procedure of ligni fi cation simulation for large-sized wooden buildings as well as 3D dynamic assembl y of these buildings under the 3DS MAX environment.The results from computer sim ulation are also shown in the paper.
Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes
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.
The Idea and Concept of Metos3D: A Marine Ecosystem Toolkit for Optimization and Simulation in 3D
Piwonski, Jaroslaw
2014-01-01
The simulation and parameter optimization of coupled ocean circulation and ecosystem models in three space dimensions is one of the most challenging tasks in numerical climate research. Here we present a scientific toolkit that aims at supporting researchers by defining clear coupling interfaces, providing state-of-the-art numerical methods for simulation, parallelization and optimization while using only freely available and (to a great extend) platform-independent software. Besides defining a user-friendly coupling interface (API) for marine ecosystem or biogeochemical models, we heavily rely on the Portable, Extensible Toolkit for Scientific computation (PETSc) developed at Argonne Nat. Lab. for a wide variety of parallel linear and non-linear solvers and optimizers. We specifically focus on the usage of matrix-free Newton-Krylov methods for the fast computation of steady periodic solutions, and make use of the Transport Matrix Method (TMM) introduced by Khatiwala et al.
3D simulation of Industrial Hall in case of fire. Benchmark between ABAQUS, ANSYS and SAFIR
Vassart, Olivier; Cajot, Louis-Guy; O'Connor, Marc; Shenkai, Y.; Fraud, C.; Zhao, Bin; De la Quintana, Jesus; Martinez de Aragon, J.; Franssen, Jean-Marc; Gens, Frederic
2004-01-01
For simple storey buildings, the structural behaviour in case of fire is relevant only for the safety of the firemen. The protection of occupants and goods is a matter of fire spread, smoke propagation, active fire fighting measures and evacuation facilities. Brittle failure, progressive collapse and partial failure of façades elements outwards may endanger the fire fighters and have to be avoided. In order to deal with such an objective, the simulation softwares has to cover the 3D structura...
Twisting Rolls. An Heuristic Model and 3D Numerical Simulations of Vortex Patterns
Bouali, Safieddine
2003-01-01
We connect an appropriate feedback loop to a model of 2D vertical eddy of airflow which unfolds a wide range of vorticity behavior. Computational fluid dynamics of the twisted roll display a class of long lifespan 3D vortices. On the one hand, the infinitely stable columnar vortex simulated describes waterspouts and tornadoes with extended lifetime. On the other hand, a light modification of the retroaction exhibits strong similarities to tropical cyclones. Moreover, we investigate the outcom...
Analytical modeling and 3D finite element simulation of line edge roughness in scatterometry
Kato, A; Burger, S.; Scholze, F.
2012-01-01
The influence of edge roughness in angle resolved scatterometry at periodically structured surfaces is investigated. A good description of the radiation interaction with structured surfaces is crucial for the understanding of optical imaging processes like, e.g. in photolithography. We compared an analytical 2D model and a numerical 3D simulation with respect to the characterization of 2D diffraction of a line grating involving structure roughness. The results show a remarkably high agreement...
Pumping simulations using 3D FEM analysis on multi-pumping wells
Shuhei, KOTANI; Takahumi, KITAOKA; Makoto, NAKAMURA; Harushige, KUSUMI; 楠見, 晴重
2011-01-01
In this research, we chiefly conducted on-site measurement and analysis to examine how the pumping wells influence groundwater behavior. We established a 3D model for groundwater and make suggestions for the adequate management of the groundwater by a pumping simulation analysis. As a result, it can be seen from our research that the fluctuation of water level caused by group wells has been reproduced accurately by using our model.
Non-crimp 3D woven composites unit cell: from geometric modelling to damage simulation
Bedogni, Enrico
2013-01-01
In the last twenty years, the research on composite materials has increased and many progresses have been made. However, there are still unresolved issues concerning the geometric modelling of a material at the meso-level (i.e. on a unit cell) and its damage simulation. In particular, the complexity of the internal geometry of some composite materials, such as 3D textiles, yields to new challenges for the research community. A correct definition of the internal structure in all the important ...
Nigrin, S.; Armstrong, G. A.; Kranti, A.
2007-09-01
This paper provides a comprehensive analysis of thermal resistance of trench isolated bipolar transistors on SOI substrates based on 3D electro-thermal simulations calibrated to experimental data. The impact of emitter length, width, spacing and number of emitter fingers on thermal resistance is analysed in detail. The results are used to design and optimise transistors with minimum thermal resistance and minimum transistor area.
The 3D numerical simulation of waste heat inside the end-pumped DPAL
Hua, Weihong; Yang, Zining; Wang, Hongyan
2012-01-01
The thermal effect produced by quantum defect is an important factor that affects the performance of DPAL. We report on 3D simulation results of temperature distribution inside the alkali gain medium. The results show a high and non-uniform temperature rise under CW pumped condition, and the current models that assume uniform alkali density distribution needs to be modified. A convective cooling scheme should be applied for high power DPALs.
Directory of Open Access Journals (Sweden)
S. Gómez
2005-01-01
Full Text Available Se presenta un simulador de sombras vectoriales por radiación solar sobre objetos tridimensionales, SSV3D, una herramienta de computación gráfica desarrollada sobre la plataforma tridimensional del AUTOCAD 2004. El software simula vectorialmente la radiación solar directa, calculando y trazando los contornos de sombra sobre los planos iluminados del modelo 3D evaluado. En el desarrollo de la herramienta se comprobaron los resultados analíticos mediante su comparación con los obtenidos en las fórmulas de una hoja de cálculo, y de los resultados gráficos mediante comparación con las sombras arrojadas por simulación con un heliodón de tecnología francesa y por el Render de AUTOCAD. El simulador SSV3D respondió satisfactoriamente a las necesidades de estudio de sistemas de protección solar en investigaciones desarrolladas anteriormente.SSV3D is presented as a graphic computer tool developed on the three-dimensional platform of AUTOCAD 2004, which simulates direct solar radiation by measuring and vectorial tracing of shadow outlines on illuminated plans of the 3D model evaluated. The analytical results of this tool were tested during its' development by comparing its' results with those obtained in the formula of a calculus sheet, and graphic results were checked comparing these to the shadows obtained by simulation using physical models in a heliodon (French technology and by the Render of AUTOCAD. The SSV3D simulator responded satisfactorily to the requirements for the study of solar protection systems which had been determined in previous research.
Calculation of Effective Material Strengths for 3D Woven Hybrid Preforms and Composites Project
National Aeronautics and Space Administration — The design concepts being considered for Heatshield for Extreme Entry Environment Technology (HEEET) rely on the use of 3D woven carbon fiber preforms. Therefore,...
Simulation and testing of a multichannel system for 3D sound localization
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.
3D-CANVENT : an integrated computer package for simulating the underground mine ventilation systems
Energy Technology Data Exchange (ETDEWEB)
Li, G.; Kocsis, C.; Hardcastle, S. [Natural Resources Canada, Sudbury, ON (Canada). CANMET Mining and Mineral Sciences Laboratories
2009-07-01
Cool, fresh air is needed in the working areas of underground mines in order to remove pollutants created during mining operations and to create satisfactory air quality conditions. 3D-CANVENT is a computer package for simulating difficult underground ventilation systems that comprise airways, fans and control devices. The package has been recently upgraded and enhanced with several new features and capabilities. This paper discussed the advanced features and capabilities of 3D-CANVENT, as well as the improvements within its solver and the utilities that greatly enhanced data entry and processing. These features include fan libraries for archiving and retrieving fan data; auto-backup of ventilation models and simulation results; animation of airflow through ventilation networks; and integrated 3D processor for editing ventilation models and viewing simulation results in different windows and orientations. The paper also outlined and discussed the technology that incorporated the air density and natural ventilation pressure in ventilation analysis. A verification example was also provided. A new tool for sensitivity study on ventilation parameter changes was also proposed to further enhance the software. 7 refs., 7 figs.
Three-dimensional parallel UNIPIC-3D code for simulations of high-power microwave devices
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.
3D Numerical Simulation on the Sloshing Waves Excited by the Seismic Shacking
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
Characterizing the propagation of gravity waves in 3D nonlinear simulations of solar-like stars
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.
The Impact of 3D Data Quality on Improving GNSS Performance Using City Models Initial Simulations
Ellul, C.; Adjrad, M.; Groves, P.
2016-10-01
There is an increasing demand for highly accurate positioning information in urban areas, to support applications such as people and vehicle tracking, real-time air quality detection and navigation. However systems such as GPS typically perform poorly in dense urban areas. A number of authors have made use of 3D city models to enhance accuracy, obtaining good results, but to date the influence of the quality of the 3D city model on these results has not been tested. This paper addresses the following question: how does the quality, and in particular the variation in height, level of generalization and completeness and currency of a 3D dataset, impact the results obtained for the preliminary calculations in a process known as Shadow Matching, which takes into account not only where satellite signals are visible on the street but also where they are predicted to be absent. We describe initial simulations to address this issue, examining the variation in elevation angle - i.e. the angle above which the satellite is visible, for three 3D city models in a test area in London, and note that even within one dataset using different available height values could cause a difference in elevation angle of up to 29°. Missing or extra buildings result in an elevation variation of around 85°. Variations such as these can significantly influence the predicted satellite visibility which will then not correspond to that experienced on the ground, reducing the accuracy of the resulting Shadow Matching process.
Experimental validation of a numerical simulation on a ballscrew system by 3D photoelasticity
Directory of Open Access Journals (Sweden)
Germaneau A.
2010-06-01
Full Text Available The Trimmable Horizontal Stabilizer Actuator (THSA system equips the whole airbus line. One component of this system is a ball-screw system on which spalling problems appear on the balls. This phenomenon is mostly due to local high pressures and reduces the service life of the system. 3D numerical simulations are usually used to tackle this kind of problems but are subjected to assumptions. As the aim of the project is to build a numerical model able to predict pressure distribution, these assumptions need to be experimentally assessed to be perfectly relevant of the real load distribution in the ball screw system. Due to the 3D geometry of the specimen, a 3D measurement technique, Scattered Light Photoelasticity (SLP, has been chosen to perform experimental measurements,. Because of complexity of the geometry, the study is divided in three steps; the present paper is dealing with the second one where a demonstrator ball-screw system is manufactured in casted epoxy to perform the SLP. This technique gives information on 3D stress fields inside the epoxy specimen from the analysis of photoelastic fringes. They are compared to numerical ones and indicate whether numerical boundary conditions are relevant of the experimental ball-screw system behaviour.
OptogenSIM: a 3D Monte Carlo simulation platform for light delivery design in optogenetics.
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
Performance of dental students versus prosthodontics residents on a 3D immersive haptic simulator.
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 (pimmersive haptic simulator. These results are a first step in establishing the validity of this device. PMID:24706694
Implementation of Headtracking and 3D Stereo with Unity and VRPN for Computer Simulations
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.
3D CFD simulation of hydrodynamics of a 150 MWe circulating fluidized bed boiler
Energy Technology Data Exchange (ETDEWEB)
Nan Zhang; Bona Lu; Wei Wang; Jinghai Li [Chinese Academy of Sciences, Beijing (China). Institute of Process Engineering
2010-08-15
An Eulerian granular multiphase model with a drag coefficient based on the energy minimization multi-scale (EMMS) model was used to perform a three-dimensional (3D), full-loop, time-dependent simulation of hydrodynamics of a 150 MWe circulating fluidized bed (CFB) boiler. Simulation results were presented in terms of the pressure profile around the whole loop of solids circulation, profiles of solids volume fraction and solids vertical velocity, as well as the non-uniform distribution of solid fluxes into two parallel cyclones.
Simulation of the impact of 3-D porosity distribution in metallic U-10Zr fuels
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.
Feasibility of the integration of CRONOS, a 3-D neutronics code, into real-time simulators
Energy Technology Data Exchange (ETDEWEB)
Ragusa, J.C. [CEA Saclay, Dept. de Mecanique et de Technologie, 91 - Gif-sur-Yvette (France)
2001-07-01
In its effort to contribute to nuclear power plant safety, CEA proposes the integration of an engineering grade 3-D neutronics code into a real-time plant analyser. This paper describes the capabilities of the neutronics code CRONOS to achieve a fast running performance. First, we will present current core models in simulators and explain their drawbacks. Secondly, the mean features of CRONOS's spatial-kinetics methods will be reviewed. We will then present an optimum core representation with respect to mesh size, choice of finite elements (FE) basis and execution time, for accurate results as well as the multi 1-D thermal-hydraulics (T/H) model developed to take into account 3-D effects in updating the cross-sections. A Main Steam Line Break (MSLB) End-of-Life (EOL) Hot-Zero-Power (HZP) accident will be used as an example, before we conclude with the perspectives of integrating CRONOS's 3-D core model into real-time simulators. (author)
Full Core 3-D Simulation of a Partial MOX LWR Core
Energy Technology Data Exchange (ETDEWEB)
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.
Simulation domain size requirements for elastic response of 3D polycrystalline materials
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.
Phenomenological modelling and simulation of cell clusters in 3D cultures.
González-Valverde, I; Semino, C; García-Aznar, J M
2016-10-01
Cell clustering and aggregation are fundamental processes in the development of several tissues and the progression of many diseases. The formation of these aggregates also has a direct impact on the oxygen concentration in their surroundings due to cellular respiration and poor oxygen diffusion through clusters. In this work, we propose a mathematical model that is capable of simulating cell cluster formation in 3D cultures through combining a particle-based and a finite element approach to recreate complex experimental conditions. Cells are modelled considering cell proliferation, cell death and cell-cell mechanical interactions. Additionally, the oxygen concentration profile is calculated through finite element analysis using a reaction-diffusion model that considers cell oxygen consumption and diffusion through the extracellular matrix and the cell clusters. In our model, the local oxygen concentration in the medium determines both cell proliferation and cell death. Numerical predictions are also compared with experimental data from the literature. The simulation results indicate that our model can predict cell clustering, cluster growth and oxygen distribution in 3D cultures. We conclude that the initial cell distribution, cell death and cell proliferation dynamics determine the size and density of clusters. Moreover, these phenomena are directly affected by the oxygen transport in the 3D culture. PMID:27615191
International Nuclear Information System (INIS)
In the present study it is reported the synthesis, characterization and subsequent degradation performance of organic–inorganic hybrid systems chemically modified by bi-functional crosslinker (glutaraldehyde, GA). The hybrids were prepared by combining 70% poly (vinyl alcohol) and 30% bioactive glass (58SiO2–33CaO–9P2O5, BaG) via sol–gel route using foaming-casting method producing different macroporous tri-dimensional scaffolds depending on the degree of network crosslinking. The in vitro degradation kinetics was evaluated by measuring the mass loss upon soaking into de-ionized water at 37 °C for up to 21 days and different mathematical models were tested. The PVA/BaG hybrids scaffolds properties “as-synthesized” and after the degradation process were extensively characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), mechanical compressing tests and X-ray Micro-computed Tomography analysis (μCT). The results have clearly shown the effectiveness of tailoring the PVA/BaG hybrids properties and degradation kinetics mechanisms by chemically engineering the structure at nano-order level using different concentrations of the crosslinker. Moreover, these hybrid crosslinked nanostructures have shown 3D hierarchical pore size with interconnected architecture within the range of 10–450 μm for potential use in the field of bone regenerative medicine. Highlights: ► Hybrid scaffolds 70% polyvinyl alcohol-30%/bioactive glass (58SiO2–33CaO–9P2O5). ► 3D-Macropore nanostructure engineered by covalent chemical crosslinker. ► Pore size distribution and mechanical properties comparable to cancellous bone. ► Analysis of degradation kinetics and mechanism using five mathematical models. ► hybrid potentially appropriate for bone tissue regenerative medicine.
3D Finite Volume Simulation of Accretion Discs with Spiral Shocks
Makita, M; Makita, Makoto; Matsuda, Takuya
1998-01-01
We perform 2D and 3D numerical simulations of an accretion disc in a close binary system using the Simplified Flux vector Splitting (SFS) finite volume method. In our calculations, gas is assumed to be the ideal one, and we calculate the cases with gamma=1.01, 1.05, 1.1 and 1.2. The mass ratio of the mass losing star to the mass accreting star is unity. Our results show that spiral shocks are formed on the accretion disc in all cases. In 2D calculations we find that the smaller gamma is, the more tightly the spiral winds. We observe this trend in 3D calculations as well in somewhat weaker sense.
Numerical simulations of self-propelled swimming of 3D bionic fish school
Institute of Scientific and Technical Information of China (English)
WU ChuiJie; WANG Liang
2009-01-01
Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package producedfor 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.
Simulation of 3D chip shaping of aluminum alloy 7075 in milling processes
Institute of Scientific and Technical Information of China (English)
DONG Hui-yue; KE Ying-lin
2005-01-01
By adopting an equivalent geometry model of machining process and considering thermo-plastic properties of the work material, a finite element method(FEM) to study oblique milling process of aluminum alloy with a double-edge tool was presented. In the FEM, shear flow stress was determined by material test. Re-meshing technology was used to represent chip separation process. Comparing the predicted cutting forces with the measured forces shows the 3D FEM is reasonable. Using this FEM, chip forming process and temperature distribution were predicted. Chips obtained by the 3D FEM are in spiral shape and are similar to the experimental ones. Distribution and change trend of temperature in the tool and chip indicate that contact length between tool rake face and chip is extending as tool moving forward. These results confirm the capability of FEM simulation in predicting chip flow and selecting optimal tool.
3D anisotropy simulation of dendrites growth with phase field method
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
The anisotropy problem of 3D phase-field model was studied,and various degrees of anisotropy were simulated by numerical calculation method.The results show that with the change of interface anisotropy coefficients,from smooth transition to the appearance of angle,equilibrium crystals shape morphology has a critical value,and 3D critical value is 0.3.The growth of dendrites is stable and the interface is smooth when it is less than critical value;the interface is unstable,rolling edge appears and the growth is discontinuous when it is more than critical value.With the increase of anisotropy coefficients,the dendrites grow faster under the same condition.
HEXBU-3D, a three-dimensional PWR-simulator program for hexagonal fuel assemblies
International Nuclear Information System (INIS)
HEXBU-3D is a three-dimensional nodal simulator program for PWR reactors. It is designed for a reactor core that consists of hexagonal fuel assemblies and of big follower-type control assemblies. The program solves two-group diffusion equations in homogenized fuel assembly geometry by a sophisticated nodal method. The treatment of feedback effects from xenon-poisoning, fuel temperature, moderator temperature and density and soluble boron concentration are included in the program. The nodal equations are solved by a fast two-level iteration technique and the eigenvalue can be either the effective multiplication factor or the boron concentration of the moderator. Burnup calculations are performed by tabulated sets of burnup-dependent cross sections evaluated by a cell burnup program. HEXBY-3D has been originally programmed in FORTRAN V for the UNIVAC 1108 computer, but there is also another version which is operable on the CDC CYBER 170 computer. (author)
Li, Zheng; Zhang, Yuwen
2016-01-01
Three-dimensional melting problems are investigated numerically with Lattice Boltzmann method (LBM). Regarding algorithm's accuracy and stability, Multiple-Relaxation-Time (MRT) models are employed to simplify the collision term in LBM. Temperature and velocity fields are solved with double distribution functions, respectively. 3-D melting problems are solved with double MRT models for the first time in this article. The key point for the numerical simulation of a melting problem is the methods to obtain the location of the melting front and this article uses interfacial tracking method. The interfacial tracking method combines advantages of both deforming and fixed grid approaches. The location of the melting front was obtained by calculating the energy balance at the solid-liquid interface. Various 3-D conduction controlled melting problems are solved firstly to verify the numerical method. Liquid fraction tendency and temperature distribution obtained from numerical methods agree with the analytical result...
Energy Technology Data Exchange (ETDEWEB)
Young, R. P.; Collins, D.; Hazzard, J.; Heath, A. [Department of Earth Sciences, Liverpool University, 4 Brownlow street, UK-0 L69 3GP Liverpool (United Kingdom); Pettitt, W.; Baker, C. [Applied Seismology Consultants LTD, 10 Belmont, Shropshire, UK-S41 ITE Shrewsbury (United Kingdom); Billaux, D.; Cundall, P.; Potyondy, D.; Dedecker, F. [Itasca Consultants S.A., Centre Scientifique A. Moiroux, 64, chemin des Mouilles, F69130 Ecully (France); Svemar, C. [Svensk Karnbranslemantering AB, SKB, Aspo Hard Rock Laboratory, PL 300, S-57295 Figeholm (Sweden); Lebon, P. [ANDRA, Parc de la Croix Blanche, 7, rue Jean Monnet, F-92298 Chatenay-Malabry (France)
2004-07-01
This paper presents current results from work performed within the European Commission project SAFETI. The main objective of SAFETI is to develop and test an innovative 3D numerical modelling procedure that will enable the 3-D simulation of nuclear waste repositories in rock. The modelling code is called AC/DC (Adaptive Continuum/ Dis-Continuum) and is partially based on Itasca Consulting Group's Particle Flow Code (PFC). Results are presented from the laboratory validation study where algorithms and procedures have been developed and tested to allow accurate 'Models for Rock' to be produced. Preliminary results are also presented on the use of AC/DC with parallel processors and adaptive logic. During the final year of the project a detailed model of the Prototype Repository Experiment at SKB's Hard Rock Laboratory will be produced using up to 128 processors on the parallel super computing facility at Liverpool University. (authors)
Numerical simulations of self-propelled swimming of 3D bionic fish school
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis- cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.
Impact of 3D-model thickness on FE-simulations of microstructure
Energy Technology Data Exchange (ETDEWEB)
Soppa, Ewa, E-mail: ewa.soppa@mpa.uni-stuttgart.de [Materialpruefungsanstalt (MPA), University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart (Germany); Nellesen, Jens [Dortmunder Initiative zur rechnerintegrierten Fertigung (RIF) e.V., Joseph-von-Fraunhofer-Strasse 20, 44227 Dortmund (Germany); Romanova, Varvara [Institute of Strength Physics and Materials Science, SB RAS, pr. Academicheskii 2/1, 634021 Tomsk (Russian Federation); Fischer, Gottfried [Dortmunder Initiative zur rechnerintegrierten Fertigung (RIF) e.V., Joseph-von-Fraunhofer-Strasse 20, 44227 Dortmund (Germany); Crostack, Horst-Artur [Lehrstuhl fuer Qualitaetswesen (LQW), Technische Universitaet Dortmund, Joseph-von-Fraunhofer-Str. 20, 44227 Dortmund (Germany); Beckmann, Felix [GKSS-Research Center, c/o GKSS at DESY, Notkestr. 85, 22607 Hamburg (Germany)
2010-01-15
To investigate the effect of model thickness on simulated strain and stress fields in two-phase materials three-dimensional and two-dimensional finite element simulations were performed. The microstructure of the models was generated both by a stochastic procedure and by transforming computer tomograms representing the microstructure into a FE mesh (artificial and realistic models, respectively). The simulated equivalent plastic strains at the surface of the realistic model were compared to equivalent strain maps obtained by digital image correlation of SEM images. The results of this study demonstrate that 2D FE simulations generally do not describe the mechanical behaviour of two-phase materials adequately. The calculated distribution of surface strain coincides with the measured one only if the thickness of 3D model exceeds a minimum value that corresponds to microstructural length scale of the material. Therefore, the thickness should be equal or larger than this minimum to get correct results at the surface.
Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.
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
Directory of Open Access Journals (Sweden)
Hoffmann Alex C.
2013-05-01
Full Text Available Particle tracks in a hydrocyclone generated both experimentally by positron emission particle tracking (PEPT and numerically with Eulerian-Lagranian CFD have been studied and compared. A hydrocyclone with a cylinder-on-cone design was used in this study, the geometries used in the CFD simulations and in the experiments being identical. It is shown that it is possible to track a fast-moving particle in a hydrocyclone using PEPT with high temporal and spatial resolutions. The numerical 3-D particle trajectories were generated using the Large Eddy Simulation (LES turbulence model for the fluid and Lagrangian particle tracking for the particles. The behaviors of the particles were analyzed in detail and were found to be consistent between experiments and CFD simulations. The tracks of the particles are discussed and related to the fluid flow field visualized in the CFD simulations using the cross-sectional static pressure distribution.
3D Simulation of Dam-break effect on a Solid Wall using Smoothed Particle Hydrodynamics
Suprijadi,; Naa, Christian; Putra, Anggy Trisnawan
2013-01-01
Dam is built for water supply, water flow or flooding control and electricity energy storage, but in other hand, dam is one of the most dangerous natural disaster in many countries including in Indonesia. The impact of dam break in neighbour area and is huge and many flooding in remote area, as happen in Dam Situ Gintung in Tangerang (close to Jakarta) in 2009. Smoothed Particle Hydrodynamics (SPH), is one of numerical method based on Lagrangian grid which is ap- plied in astrophysical simulation may be used to solve the simulation on dam break effect. The development of SPH methods become alternative methods to solving Navier Stokes equation, which is main key in fluid dynamic simulation. In this paper, SPH is developed for supporting solid par- ticles in use for 3D dam break effect (3D-DBE) simulation. Solid particle have been treated same as fluid particles with additional calculation for converting gained position became translation and rotation of solid object in a whole body. With this capability, the r...
3D Numerical Simulation of Overbank Flow in Non-Orthogonal Curvilinear Coordinates
Institute of Scientific and Technical Information of China (English)
ZHANG Ming-liang; SHEN Yong-ming; WU Xiu-guang
2005-01-01
The velocity field in meandering compound channels with overbank flow is highly three dimensional. To date, its features have been investigated experimentally and little research has been undertaken to investigate the feasibility of reproducing these velocity fields with computer models. If computer modeling were to prove successful in this context, it could become a useful prediction technique and research tool to enhance our understanding of natural river dynamics. A 3-D k-ε turbulence hydrodynamic model in curvilinear coordinates is established to simulate the overbank flow. The body-fitted coordinate is adopted in the horizontal plane, the part grid is adopted in the vertical direction, and the wall-function method is employed to simulate the bed resistance. The model is applied to the simulation of the meandering channel with straight flood plain banks, and the main velocities and secondary velocities for both the longitudinal and cross sections are presented. Comparison and analysis show that the results of simulation are fit to reflect the results of experiment. These results show the application value of the model to 3D overbank flow.
Water flow prediction for Membranes using 3D simulations with detailed morphology
Shi, Meixia
2015-04-01
The membrane morphology significantly influences membrane performance. For osmotically driven membrane processes, the morphology strongly affects the internal concentration polarization. Different membrane morphologies were generated by simulation and their influence on membrane performance was studied, using a 3D model. The simulation results were experimentally validated for two classical phase-inversion membrane morphologies: sponge- and finger-like structures. Membrane porosity and scanning electron microscopy image information were used as model input. The permeance results from the simulation fit well the experimentally measured permeances. Water permeances were predicted for different kinds of finger-like cavity membranes with different finger-like cavity lengths and various finger-like cavity sets, as well as for membranes with cylindrical cavities. The results provide realistic information on how to increase water permeance, and also illustrate that membrane’s complete morphology is important for the accurate water permeance evaluation. Evaluations only based on porosity might be misleading, and the new 3D simulation approach gives a more realistic representation.
Institute of Scientific and Technical Information of China (English)
吴开腾; 宁建国
2003-01-01
A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves produced by an explosive source. These numerical results indicate that the code MMIC3D has the ability in computing cases such as 3D shock waves produced by air explosion, vortex region of the shock wave, the Mach wave, and reflected waves behind rigid boundaries.
RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations.
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
Gravitational Wave Signals from 3D Neutrino Hydrodynamics Simulations of Core-Collapse Supernovae
Andresen, Haakon; Mueller, Ewald; Janka, Hans-Thomas
2016-01-01
We present gravitational wave (GW) signal predictions from four 3D multi-group neutrino hydrodynamics simulations of core-collapse supernovae of progenitors with 11.2 Msun, 20 Msun, and 27 Msun. GW emission in the pre-explosion phase strongly depends on whether the post-shock flow is dominated by the standing accretion shock instability (SASI) or convection and differs considerably from 2D models. SASI activity produces a strong signal component below 250 Hz through asymmetric mass motions in the gain layer and a non-resonant coupling to the proto-neutron star (PNS). Both convection- and SASI-dominated models show GW emission above 250 Hz, but with considerably lower amplitudes than in 2D. This is due to a different excitation mechanism for high-frequency l=2 motions in the PNS surface, which are predominantly excited by PNS convection in 3D. Resonant excitation of high-frequency surface g-modes in 3D by mass motions in the gain layer is suppressed compared to 2D because of smaller downflow velocities and a l...
Detecting drug use in adolescents using a 3D simulation program
Directory of Open Access Journals (Sweden)
Luis Iribarne
2010-11-01
Full Text Available This work presents a new 3D simulation program, called MiiSchool, and its application to the detection of problem behaviours appearing in school settings. We begin by describing some of the main features of the Mii School program. Then, we present the results of a study in which adolescents responded to Mii School simulations involving the consumption of alcoholic drinks, cigarettes, cannabis, cocaine, and MDMA (ecstasy. We established a“risk profile” based on the observed response patterns. We also present results concerning user satisfaction with the program and the extent to which users felt that the simulated scenes were realistic. Lastly, we discuss the usefulness of Mii School as a tool for assessing drug use in school settings.
hp-HGS strategy for inverse 3D DC resistivity logging measurement simulations
Gajda-Zaǵorska, Ewa
2012-06-02
In this paper we present a twin adaptive strategy hp-HGS for solving inverse problems related to 3D DC borehole resistivity measurement simulations. The term “simulation of measurements” is widely used by the geophysical community. A quantity of interest, voltage, is measured at a receiver electrode located in the logging instrument. We use the self-adaptive goal-oriented hp-Finite Element Method (hp-FEM) computer simulations of the process of measurements in deviated wells (when the angle between the borehole and formation layers are < 90 deg). We also employ the hierarchical genetic search (HGS) algorithm to solve the inverse problem. Each individual in the population represents a single conﬁguration of the formation layers. The evaluation of the individual is performed by solving the direct problem by means of the hp-FEM algorithm and by comparison with measured logging curve. We conclude the paper with some discussion on the parallelization of the algorithm.
Institute of Scientific and Technical Information of China (English)
2008-01-01
Based on the potential flow theory, the vortex ring is introduced to simulate the toroidal bubble, and the boundary element method is applied to simulate the evo- lution of the bubble. Elastic-plasticity of structure being taken into account, the interaction between the bubble and the elastic-plastic structure is computed by combining the boundary element method (BEM) and the finite element method (FEM), and a corresponding 3D computing program is developed. This program is used to simulate the three-dimensional bubble dynamics in free field, near wall and near the elastic-plastic structure, and the numerical results are compared with the existing experimental results. The error is within 10%. The effects of different boundaries upon the bubble dynamics are presented by studying the bubble dy- namics near different boundaries.
3D printing of tissue-simulating phantoms as a traceable standard for biomedical optical measurement
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.
Institute of Scientific and Technical Information of China (English)
ZHANG AMan; YAO XiongLiang; LI Jia; GUO Jun
2008-01-01
Based on the potential flow theory,the vortex ring is introduced to simulate the toroidal bubble,and the boundary element method is applied to simulate the evo-lution of the bubble.Elastic-plasticity of structure being taken into account,the interaction between the bubble and the elastic-plastic structure is computed by combining the boundary element method (BEM) and the finite element method (FEM),and a corresponding 3D computing program is developed.This program is used to simulate the three-dimensional bubble dynamics in free field,near wall and near the elastic-plastic structure,and the numerical results are compared with the existing experimental results.The error is within 10%.The effects of different boundaries upon the bubble dynamics are presented by studying the bubble dy-namics near different boundaries.
Application of asymptotic waveform approximation technique to hybrid FE/BI method for 3D scattering
Institute of Scientific and Technical Information of China (English)
PENG Zhen; SHENG XinQing
2007-01-01
The asymptotic waveform evaluation (AWE) technique is a rational function approximation method in computational mathematics, which is used in many applications in computational electromagnetics. In this paper, the performance of the AWE technique in conjunction with hybrid finite element/boundary integral (FE/BI) method is firstly investigated. The formulation of the AWE applied in hybrid FE/BI method is given in detail. The characteristic implementation of the application of the AWE to the hybrid FE/BI method is discussed. Numerical results demonstrate that the AWE technique can greatly speed up the hybrid FE/BI method to acquire wide-band and wide-angle backscatter radar-cross-section (RCS) by complex targets.
3D Simulation of Storm Surge Disaster Based on Scenario Analysis
Institute of Scientific and Technical Information of China (English)
王晓玲; 孙小沛; 张胜利; 孙蕊蕊; 李瑞金; 朱泽彪
2016-01-01
The occurrence of storm surge disaster is often accompanied with floodplain, overflow, dike breach and other complex phenomena, while current studies on storm surge flooding are more concentrated on the 1D/2D numerical simulation of single disaster scenario (floodplain, overflow or dike breach), ignoring the composite ef-fects of various phenomena. Therefore, considering the uncertainty in the disaster process of storm surge, scenario analysis was firstly proposed to identify the composite disaster scenario including multiple phenomena by analyzing key driving forces, building scenario matrix and deducing situation logic. Secondly, by combining the advantages of k-ωand k-εmodels in the wall treatment, a shear stress transmission k-ωmodel coupled with VOF was proposed to simulate the 3D flood routing for storm surge disaster. Thirdly, risk degree was introduced to make the risk analysis of storm surge disaster. Finally, based on the scenario analysis, four scenarios with different storm surge intensity (100-year and 200-year frequency) were identified in Tianjin Binhai New Area. Then, 3D numerical simulation and risk map were made for the case.
3D numerical simulation of the evolutionary process of aeolian downsized crescent-shaped dunes
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.
3D simulations of globules and pillars formation around HII regions: turbulence and shock curvature
Tremblin, P; Minier, V; Schmidt, W; Schneider, N
2012-01-01
We investigate the interplay between the ionization radiation from massive stars and the turbulence inside the surrounding molecular gas thanks to 3D numerical simulations. We used the 3D hydrodynamical code HERACLES to model an initial turbulent medium that is ionized and heated by an ionizing source. Three different simulations are performed with different mean Mach numbers (1, 2 and 4). A non-equilibrium model for the ionization and the associated thermal processes was used. This revealed to be crucial when turbulent ram pressure is of the same order as the ionized-gas pressure. The density structures initiated by the turbulence cause local curvatures of the dense shell formed by the ionization compression. When the curvature of the shell is sufficient, the shell collapse on itself to form a pillar while a smaller curvature leads to the formation of dense clumps that are accelerated with the shell and therefore remain in the shell during the simulation. When the turbulent ram pressure of the cold gas is su...
Numerical simulation of a combined oxidation ditch flow using 3D k-εturbulence model
Institute of Scientific and Technical Information of China (English)
LUO Lin; LI Wei-min; DENG Yong-sen; WANG Tao
2005-01-01
The standard three dimensional(3D) k-ε 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.
NUMERICAL SIMULATION OF 3-D FLOW FIELD IN ARCIFORM PLUNGE POOL
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The 3-D complex turbulent flow fields in aplunge pool with arciform bottom are simulated by using thek-ε model in body-fitted coordinates. The calculated results re-veal the flow characteristics in the arciform plunge pool underthe different flood discharge conditions, which can not be easi-ly obtained in the physical model test because the measure-ment of the complex velocity is very difficult. The calculatedflow fields are helpful to understand in depth the hydrauliccharacteristics of plunge pool. The calculated and the meas-ured pressure distributions on the pool bottom are comparedand in good agreement.
RapidArc treatment verification in 3D using polymer gel dosimetry and Monte Carlo simulation
DEFF Research Database (Denmark)
Ceberg, Sofie; Gagne, Isabel; Gustafsson, Helen;
2010-01-01
and MC simulations, thus investigating any discrepancy between the planned dose delivery and the actual delivery. Additionally, the reproducibility of the delivery was investigated using repeated gel measurements. A prostate treatment plan was delivered to a 1.3 liter nPAG gel phantom using one single...... was within 2.5% (1SD). A 3D gamma analysis between the dose matrices were carried out using gamma criteria 3%/3 mm and 5%/5 mm (% dose difference and mm distance to agreement) within the volume enclosed by the 50% isodose surface (VOI50) and the 90% isodose surface (VOI90), respectively. All comparisons...
Coupling Magnetic Fields and ALE Hydrodynamics for 3D Simulations of MFCG's
Energy Technology Data Exchange (ETDEWEB)
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.
International Nuclear Information System (INIS)
Recently, the three-dimensional (3D) printing technique has received much attention for shape forming and manufacturing. The fused deposition modeling (FDM) printer is one of the various 3D printers available and has become widely used due to its simplicity, low-cost, and easy operation. However, the FDM technique has a limitation whereby its patterning resolution is too low at around 200 μm. In this paper, we first present a hybrid mechanism of electrohydrodynamic jet printing with the FDM technique, which we name E-FDM. We then develop a novel high-resolution 3D printer based on the E-FDM process. To determine the optimal condition for structuring, we also investigated the effect of several printing parameters, such as temperature, applied voltage, working height, printing speed, flow-rate, and acceleration on the patterning results. This method was capable of fabricating both high resolution 2D and 3D structures with the use of polylactic acid (PLA). PLA has been used to fabricate scaffold structures for tissue engineering, which has different hierarchical structure sizes. The fabrication speed was up to 40 mm/s and the pattern resolution could be improved to 10 μm. (paper)
Zhang, Bin; Seong, Baekhoon; Nguyen, VuDat; Byun, Doyoung
2016-02-01
Recently, the three-dimensional (3D) printing technique has received much attention for shape forming and manufacturing. The fused deposition modeling (FDM) printer is one of the various 3D printers available and has become widely used due to its simplicity, low-cost, and easy operation. However, the FDM technique has a limitation whereby its patterning resolution is too low at around 200 μm. In this paper, we first present a hybrid mechanism of electrohydrodynamic jet printing with the FDM technique, which we name E-FDM. We then develop a novel high-resolution 3D printer based on the E-FDM process. To determine the optimal condition for structuring, we also investigated the effect of several printing parameters, such as temperature, applied voltage, working height, printing speed, flow-rate, and acceleration on the patterning results. This method was capable of fabricating both high resolution 2D and 3D structures with the use of polylactic acid (PLA). PLA has been used to fabricate scaffold structures for tissue engineering, which has different hierarchical structure sizes. The fabrication speed was up to 40 mm/s and the pattern resolution could be improved to 10 μm.
Terascale direct numerical simulations of turbulent combustion using S3D
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
A 3D µPAD based on a multi-enzyme organic-inorganic hybrid nanoflower reactor.
Ariza-Avidad, M; Salinas-Castillo, A; Capitán-Vallvey, L F
2016-03-15
This work reports on the development of a 3D microfluidic paper-based device (3D µPAD) for glucose detection using organic-inorganic hybrid nanoflower technology to immobilize the bi-enzymatic system (glucose oxidase and horseradish peroxidase). The system is based on nanoflowerssupported on cellulose paper (the microreactor zone) coupled to 3,3',5,5'-tetramethylbenzidine (TMB) as the colorimetric probe in the detection zone. We used a digital camera for the quantitative analysis of glucose with the S coordinate of the HSV color space as the analytical parameter. Under optimal operational conditions, linearity was observed for glucose concentrations up to 300 μM, with a detection limit of 15.6 µM. The biosensor is reusable and remains stable for 75 days in conventional storage conditions. PMID:26386331
Insights from 3D numerical simulations on the dynamics of the India-Asia collision zone
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
Novel fabrication technique of hybrid structure lens array for 3D images
Lee, Junsik; Kim, Junoh; Kim, Cheoljoong; Shin, Dooseub; Koo, Gyohyun; Won, Yong Hyub
2016-03-01
Tunable liquid lens arrays can produce three dimensional images by using electrowetting principle that alters surface tensions by applying voltage. This method has advantages of fast response time and low power consumption. However, it is challenging to fabricate a high fill factor liquid lens array and operate three dimensional images which demand high diopter. This study describes a hybrid structure lens array which has not only a liquid lens array but a solid lens array. A concave-shape lens array is unavoidable when using only the liquid lens array and some voltages are needed to make the lens flat. By placing the solid lens array on the liquid lens array, initial diopter can be positive. To fabricate the hybrid structure lens array, a conventional lithographic process in semiconductor manufacturing is needed. A negative photoresist SU-8 was used as chamber master molds. PDMS and UV adhesive replica molding are done sequentially. Two immiscible liquids, DI water and dodecane, are injected in the fabricated chamber, followed by sealing. The fabricated structure has a 20 by 20 pattern of cylindrical shaped circle array and the aperture size of each lens is 1mm. The thickness of the overall hybrid structure is about 2.8mm. Hybrid structure lens array has many advantages. Solid lens array has almost 100% fill factor and allow high efficiency. Diopter can be increased by more than 200 and negative diopter can be shifted to the positive region. This experiment showed several properties of the hybrid structure and demonstrated its superiority.
Quasi 3D refined simulation of flow and pollutant transport in a meandering River Reach
Directory of Open Access Journals (Sweden)
Li-ren Yu
2013-03-01
Full Text Available This paper reports a quasi 3D numerical simulation in a meandering river reach of the Yellow River, aiming to develop a tool for modeling turbulent flows and pollutant transport in complex natural waters. The recently built depth-averaged two-equation turbulence model, together with and models, were used to close non-simplified quasi 3D hydrodynamic fundamental governing equations. The discretized equations were solved by advanced multi-grid iterative method under non-orthogonal body-fitted coarse and fine two-levels’ grids with collocated variable arrangement. Except for steady flow and transport computation, the processes of contaminant inpouring and plume development, caused by the side-discharge from a tribytary, also have been investigated numerically. The used three closure approaches are suitable for modeling strong mixing turbulence. The established model with higher order of magnitude of transported variable provides a possibility to elevate the computational precision. Based on the developed mathematical model, a CFD (Computational Fluid Dynamics software, namely Q3drm1.0, was developed. This numerical tool focuses on the refined simulations of the steady and unsteady problems of flow and temperature/contaminant transports in complicated computational domains with the strong ability to deal with different discharge situations: side-discharge, point-source discharge/point-sink, and area-source discharge from the slope along bank. In this article, the study of side-discharge is presented only.
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.
Growth and Transfer of Seamless 3D Graphene-Nanotube Hybrids.
Kim, Nam Dong; Li, Yilun; Wang, Gunuk; Fan, Xiujun; Jiang, Jinlong; Li, Lei; Ji, Yongsung; Ruan, Gedeng; Hauge, Robert H; Tour, James M
2016-02-10
Seamlessly connected graphene and carbon nanotube hybrids (GCNTs) have great potential as carbon platform structures in electronics due to their high conductivity and high surface area. Here, we introduce a facile method for making patterned GCNTs and their intact transfer onto other substrates. The mechanism for selective growth of vertically aligned CNTs (VA-CNTs) on the patterned graphene is discussed. The complete transfer of the GCNT pattern onto other substrates is possible because of the mechanical strength of the GCNT hybrids. Electrical conductivity measurements of the transferred GCNT structures show Ohmic contact through the VA-CNTs to graphene--evidence of its integrity after the transfer process. PMID:26789079
Growth and Transfer of Seamless 3D Graphene-Nanotube Hybrids.
Kim, Nam Dong; Li, Yilun; Wang, Gunuk; Fan, Xiujun; Jiang, Jinlong; Li, Lei; Ji, Yongsung; Ruan, Gedeng; Hauge, Robert H; Tour, James M
2016-02-10
Seamlessly connected graphene and carbon nanotube hybrids (GCNTs) have great potential as carbon platform structures in electronics due to their high conductivity and high surface area. Here, we introduce a facile method for making patterned GCNTs and their intact transfer onto other substrates. The mechanism for selective growth of vertically aligned CNTs (VA-CNTs) on the patterned graphene is discussed. The complete transfer of the GCNT pattern onto other substrates is possible because of the mechanical strength of the GCNT hybrids. Electrical conductivity measurements of the transferred GCNT structures show Ohmic contact through the VA-CNTs to graphene--evidence of its integrity after the transfer process.
Investigating the guiding of streamers in nitrogen/oxygen mixtures with 3D simulations
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.
A NUMERICAL SIMULATION OF 3-D INNER FLOW IN UP-STREAM PUMPING MECHANICAL SEAL
Institute of Scientific and Technical Information of China (English)
ZHANG Jin-feng; YUAN Shou-qi; FU Yong-hong; FANG Yu-jian
2006-01-01
Numerical simulation of 3-D inner flow between Up-stream Pumping Mechanical Face Seals (UPMFS) faces was initially done by CFD software, which made the flow visualization come true.Simulation results directly discover the action of hydrodynamic lubrication, and by comparison with that of Conventional Mechanic Face Seals (CMFS), the advantage over bigger bearing capability, less friction and much less leakage are explained clearly.Otherwise there are also some different ideas and results from precedent analysis and computational research results: dynamic and static pressure profiles can be obtained respectively instead of the analytic total pressure distribution only, pressure distribution is nonlinear, while always be solved as linear, lower pressure is observed at the area of inner diameter caused by the grooves, but its possible cavitations effects to the performance of UPMFS still need further study.
Casting directly from a computer model by using advanced simulation software FLOW-3D Cast ®
Directory of Open Access Journals (Sweden)
M. Sirviö
2009-01-01
Full Text Available ConiferRob - A patternless casting technique, originally conceived at VTT Technical Research Centre of Finland and furtherdeveloped at its spin-off company, Simtech Systems, offers up to 40% savings in product development costs, and up to two months shorterdevelopment times compared to conventional techniques. Savings of this order can be very valuable on today's highly competitivemarkets. Casting simulation is commonly used for designing of casting systems. However, most of the software are today old fashioned and predicting just shrinkage porosity. Flow Science, VTT and Simtech have developed new software called FLOW-3D Cast ® , whichcan simulate surface defects, air entrainment, filters, core gas problems and even a cavitation.
3-D CFD simulations of hydrodynamics in the Sulejow dam reservoir
Directory of Open Access Journals (Sweden)
Ziemińska-Stolarska Aleksandra
2015-12-01
Full Text Available This paper reports the processes by which a single-phase 3-D CFD model of hydrodynamics in a 17-km-long dam reservoir was developed, verified and tested. A simplified VOF model of flow was elaborated to determine the effect of wind on hydrodynamics in the lake. A hexahedral mesh with over 17 million elements and a k-ω SST turbulence model were defined for single-phase simulations in steady-state conditions. The model was verified on the basis of the extensive flow measurements (StreamPro ADCP, USA. Excellent agreement (average error of less than 10% between computed and measured velocity profiles was found. The simulation results proved a strong effect of wind on hydrodynamics in the lake, especially on the development of the water circulation pattern in the lacustrine zone.
Analytical modeling and 3D finite element simulation of line edge roughness in scatterometry
Kato, A; Scholze, F
2012-01-01
The influence of edge roughness in angle resolved scatterometry at periodically structured surfaces is investigated. A good description of the radiation interaction with structured surfaces is crucial for the understanding of optical imaging processes like, e.g. in photolithography. We compared an analytical 2D model and a numerical 3D simulation with respect to the characterization of 2D diffraction of a line grating involving structure roughness. The results show a remarkably high agreement. The diffraction intensities of a rough structure can therefore be estimated using the numerical simulation result of an undisturbed structure and an analytically derived correction function. This work allows to improve scatterometric results for the case of practically relevant 2D structures.
3D Transient CFD Simulation of Scroll Compressors with the Tip Seal
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.
[A rapid prototype fabrication method of dental splint based on 3D simulation and technology].
Lin, Yanping; Chen, Xiaojun; Zhang, Shilei; Wang, Chengtao
2006-04-01
The conventional design and fabrication of the dental splint (in orthognathic surgery) is based on the preoperative planning and model surgery so this process is of low precision and efficiency. In order to solve the problems and be up to the trend of computer-assisted surgery, we have developed a novel method to design and fabricate the dental splint--computer-generated dental splint, which is based on three-dimensional model simulation and rapid prototype technology. After the surgical planning and simulation of 3D model, we can modify the model to be superior in chewing action (functional) and overall facial appearance (aesthetic). Then, through the Boolean operation of the dental splint blank and the maxillofacial bone model the model of dental splint is formed. At last, the dental splint model is fabricated through rapid prototype machine and applied in clinic. The result indicates that, with the use of this method, the surgical precision and efficiency are improved.
Synthetic 3D modeling of active regions and simulation of their multi-wavelength emission
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
International Nuclear Information System (INIS)
Hybrid methods of neutron transport have increased greatly in use, for example, in applications of using both Monte Carlo and deterministic transport methods to calculate quantities of interest, such as the flux and eigenvalue in a nuclear reactor. Many 3d parallel Sn codes apply a Cartesian mesh, and thus for nuclear reactors the representation of curved fuels (cylinder, sphere, etc.) are impacted in the representation of proper fuel inventory, resulting in both a deviation of mass and exact geometry in the computer model representation. In addition, we discuss auto-conversion techniques with our 3d Cartesian mesh generation tools to allow for full generation of MCNP5 inputs (Cartesian mesh and Multigroup XS) from a basis PENTRAN Sn model. For a PWR assembly eigenvalue problem, we explore the errors associated with this Cartesian discrete mesh representation, and perform an analysis to calculate a slope parameter that relates the pcm to the percent areal/volumetric deviation (areal → 2d problems, volumetric → 3d problems). This paper analysis demonstrates a linear relationship between pcm change and areal/volumetric deviation using Multigroup MCNP on a PWR assembly compared to a reference exact combinatorial MCNP geometry calculation. For the same MCNP multigroup problems, we also characterize this linear relationship in discrete ordinates (3d PENTRAN). Finally, for 3D Sn models, we show an application of corner fractioning, a volume-weighted recovery of underrepresented target fuel mass that reduced pcm error to < 100, compared to reference Monte Carlo, in the application to a PWR assembly. (author)
Gibson, Stephen
2011-01-01
In this paper the author will describe and show examples of his live audio-visual work for 3D spatial environments. These projects use motion tracking technology to enable users to interact with sound, light and video using their body movements in 3D space, simulating the effect of synaesthesia.
Mendrik, A.M.; Vonken, E.J.; Rutten, A.; Viergever, M.A.; Ginneken, B. van
2009-01-01
Noise filtering techniques that maintain image contrast while decreasing image noise have the potential to optimize the quality of computed tomography (CT) images acquired at reduced radiation dose. In this paper, a hybrid diffusion filter with continuous switch (HDCS) is introduced, which exploits
The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis
Energy Technology Data Exchange (ETDEWEB)
Shaheen, Eman, E-mail: eman.shaheen@uzleuven.be; De Keyzer, Frederik; Bosmans, Hilde; Ongeval, Chantal Van [Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); Dance, David R.; Young, Kenneth C. [National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)
2014-08-15
Purpose: This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Methods: Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected 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. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. Results: The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly
The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis
International Nuclear Information System (INIS)
Purpose: This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Methods: Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected 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. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. Results: The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly
Mammogram synthesis using a 3D simulation. II. Evaluation of synthetic mammogram texture
International Nuclear Information System (INIS)
We have evaluated a method for synthesizing mammograms by comparing the texture of clinical and synthetic mammograms. The synthesis algorithm is based upon simulations of breast tissue and the mammographic imaging process. Mammogram texture was synthesized by projections of simulated adipose tissue compartments. It was hypothesized that the synthetic and clinical texture have similar properties, assuming that the mammogram texture reflects the 3D tissue distribution. The size of the projected compartments was computed by mathematical morphology. The texture energy and fractal dimension were also computed and analyzed in terms of the distribution of texture features within four different tissue regions in clinical and synthetic mammograms. Comparison of the cumulative distributions of the mean features computed from 95 mammograms showed that the synthetic images simulate the mean features of the texture of clinical mammograms. Correlation of clinical and synthetic texture feature histograms, averaged over all images, showed that the synthetic images can simulate the range of features seen over a large group of mammograms. The best agreement with clinical texture was achieved for simulated compartments with radii of 4-13.3 mm in predominantly adipose tissue regions, and radii of 2.7-5.33 and 1.3-2.7 mm in retroareolar and dense fibroglandular tissue regions, respectively
3D Multistage Simulation of Each Component of the GE90 Turbofan Engine
Turner, Mark; Topp, Dave; Veres, Joe
1999-01-01
A 3D multistage simulation of each component of the GE90 Turbofan engine has been made. This includes 49 blade rows. A coupled simulation of all blade rows will be made very soon. The simulation is running using two levels of parallelism. The first level is on a blade row basis with information shared using files. The second level is using a grid domain decomposition with information shared using MPI. Timings will be shown for running on the SP2, an SGI Origin and a distributed system of HP workstations. On the HP workstations, the CHIMP version of MPI is used, with queuing supplied by LSF (Load Sharing Facility). A script-based control system is used to ensure reliability. An MPEG movie illustrating the flow simulation of the engine has been created using PV3, a parallel visualization library created by Bob Haimes of MIT. PVM is used to create a virtual machine from 10 HP workstations and display on an SGI workstation. A representative component simulation will be compared to rig data to demonstrate its usefulness in turbomachinery design and analysis.
Parallel computing simulation of electrical excitation and conduction in the 3D human heart.
Di Yu; Dongping Du; Hui Yang; Yicheng Tu
2014-01-01
A correctly beating heart is important to ensure adequate circulation of blood throughout the body. Normal heart rhythm is produced by the orchestrated conduction of electrical signals throughout the heart. Cardiac electrical activity is the resulted function of a series of complex biochemical-mechanical reactions, which involves transportation and bio-distribution of ionic flows through a variety of biological ion channels. Cardiac arrhythmias are caused by the direct alteration of ion channel activity that results in changes in the AP waveform. In this work, we developed a whole-heart simulation model with the use of massive parallel computing with GPGPU and OpenGL. The simulation algorithm was implemented under several different versions for the purpose of comparisons, including one conventional CPU version and two GPU versions based on Nvidia CUDA platform. OpenGL was utilized for the visualization / interaction platform because it is open source, light weight and universally supported by various operating systems. The experimental results show that the GPU-based simulation outperforms the conventional CPU-based approach and significantly improves the speed of simulation. By adopting modern computer architecture, this present investigation enables real-time simulation and visualization of electrical excitation and conduction in the large and complicated 3D geometry of a real-world human heart.
Augmented reality intravenous injection simulator based 3D medical imaging for veterinary medicine.
Lee, S; Lee, J; Lee, A; Park, N; Lee, S; Song, S; Seo, A; Lee, H; Kim, J-I; Eom, K
2013-05-01
Augmented reality (AR) is a technology which enables users to see the real world, with virtual objects superimposed upon or composited with it. AR simulators have been developed and used in human medicine, but not in veterinary medicine. The aim of this study was to develop an AR intravenous (IV) injection simulator to train veterinary and pre-veterinary students to perform canine venipuncture. Computed tomographic (CT) images of a beagle dog were scanned using a 64-channel multidetector. The CT images were transformed into volumetric data sets using an image segmentation method and were converted into a stereolithography format for creating 3D models. An AR-based interface was developed for an AR simulator for IV injection. Veterinary and pre-veterinary student volunteers were randomly assigned to an AR-trained group or a control group trained using more traditional methods (n = 20/group; n = 8 pre-veterinary students and n = 12 veterinary students in each group) and their proficiency at IV injection technique in live dogs was assessed after training was completed. Students were also asked to complete a questionnaire which was administered after using the simulator. The group that was trained using an AR simulator were more proficient at IV injection technique using real dogs than the control group (P ≤ 0.01). The students agreed that they learned the IV injection technique through the AR simulator. Although the system used in this study needs to be modified before it can be adopted for veterinary educational use, AR simulation has been shown to be a very effective tool for training medical personnel. Using the technology reported here, veterinary AR simulators could be developed for future use in veterinary education. PMID:23103217
Energy Technology Data Exchange (ETDEWEB)
Mansur, Herman S., E-mail: hmansur@demet.ufmg.br [Department of Metallurgical and Materials Engineering, Laboratory of Biomaterials and Tissue Engineering, Federal University of Minas Gerais (Brazil); Costa, Hermes S. [Department of Materials Engineering, CEFET-MG (Brazil); Mansur, Alexandra A.P.; Pereira, Marivalda [Department of Metallurgical and Materials Engineering, Laboratory of Biomaterials and Tissue Engineering, Federal University of Minas Gerais (Brazil)
2012-04-01
In the present study it is reported the synthesis, characterization and subsequent degradation performance of organic-inorganic hybrid systems chemically modified by bi-functional crosslinker (glutaraldehyde, GA). The hybrids were prepared by combining 70% poly (vinyl alcohol) and 30% bioactive glass (58SiO{sub 2}-33CaO-9P{sub 2}O{sub 5}, BaG) via sol-gel route using foaming-casting method producing different macroporous tri-dimensional scaffolds depending on the degree of network crosslinking. The in vitro degradation kinetics was evaluated by measuring the mass loss upon soaking into de-ionized water at 37 Degree-Sign C for up to 21 days and different mathematical models were tested. The PVA/BaG hybrids scaffolds properties 'as-synthesized' and after the degradation process were extensively characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), mechanical compressing tests and X-ray Micro-computed Tomography analysis ({mu}CT). The results have clearly shown the effectiveness of tailoring the PVA/BaG hybrids properties and degradation kinetics mechanisms by chemically engineering the structure at nano-order level using different concentrations of the crosslinker. Moreover, these hybrid crosslinked nanostructures have shown 3D hierarchical pore size with interconnected architecture within the range of 10-450 {mu}m for potential use in the field of bone regenerative medicine. Highlights: Black-Right-Pointing-Pointer Hybrid scaffolds 70% polyvinyl alcohol-30%/bioactive glass (58SiO{sub 2}-33CaO-9P{sub 2}O{sub 5}). Black-Right-Pointing-Pointer 3D-Macropore nanostructure engineered by covalent chemical crosslinker. Black-Right-Pointing-Pointer Pore size distribution and mechanical properties comparable to cancellous bone. Black-Right-Pointing-Pointer Analysis of degradation kinetics and mechanism using five mathematical models. Black-Right-Pointing-Pointer hybrid potentially appropriate for bone tissue
The dark side of photovoltaic — 3D simulation of glare assessing risk and discomfort
International Nuclear Information System (INIS)
Photovoltaic (PV) systems form an important force in the implementation of renewable energies, but as we all know, the force has always its dark side. Besides efficiency considerations and discussions about architectures of power distribution networks, the increasing numbers of installations of PV systems for implementing renewable energies have secondary effects. PV systems can generate glare due to optical reflections and hence might be a serious concern. On the one hand, glare could affect safety, e.g. regarding traffic. On the other hand, glare is a constant source of discomfort in vicinities of PV systems. Hence, assessment of glare is decisive for the success of renewable energies near municipalities and traffic zones for the success of solar power. Several courts decided on the change of PV systems and even on their de-installation because of glare effects. Thus, location-based assessments are required to limit potential reflections and to avoid risks for public infrastructure or discomfort of residents. The question arises on how to calculate reflections accurately according to the environment's topography. Our approach is founded in a 3D-based simulation methodology to calculate and visualize reflections based on the geometry of the environment of PV systems. This computational model is implemented by an interactive tool for simulation and visualization. Hence, project planners receive flexible assistance for adjusting the parameters of solar panels amid the planning process and in particular before the installation of a PV system. - Highlights: • Solar panels cause glare that impacts neighborhoods and traffic infrastructures. • Glare might cause disability and discomfort. • 3D environment for the calculation of glare • Interactive tool to simulate and visualize reflections • Impact assessment of solar power plant farms
3D Simulation of Ultrasound in the Ultra-Distal Human Radius
Kaufman, Jonathan J.; Luo, Gangming; Siffert, Robert S.
The overall objective of this research is to develop an ultrasonic method for non-invasive assessment of the ultradistal radius (UDR). The specific objective of this study was to examine the propagation of ultrasound through the UDR and determine the relationships between bone mass and ultrasound, as well as the ability of ultrasound to discriminate between fracture and non-fracture cases. High-resolution peripheral-QCT (HR-pQCT) images were obtained from a set of 110 subjects that were part of a larger study on osteoporosis. Twenty-three of the subjects had experienced a UDR fracture within the past 2 years; the other 87 subjects served as controls. Each 3D image was used to simulate ultrasound measurements that would result from propagation through the UDR, from its anterior to its posterior surfaces. The simulation was carried out using Wave3000 (CyberLogic, Inc., New York, USA), which solves the full 3D viscoelastic wave equation using a finite difference time domain method. Bone mineral density associated with each radius was computed for each subject, and an ultrasound parameter known as net time delay (NTD) was evaluated. NTD has been shown to be highly correlated with total bone mass in both in vitro and clinical studies. Significant correlations were found between NTD and total bone mass (R2 = 0.91, p < 0.001). The data also showed a statistically significant difference in the NTD for the fracture and non-fracture cases (i.e., a decrease in mean NTD of 14% (P < 0.001), with a t-test statistic of 3.8). The study shows that ultrasound is correlated with bone mass at the UDR, as well as with fracture incidence. Therefore ultrasound may prove useful as a simple and convenient method for non-invasive assessment of osteoporosis and fracture risk. Work is ongoing to compare the simulated ultrasound data with clinical ultrasound measurements made on the same individuals.
Combination of intensity-based image registration with 3D simulation in radiation therapy
Li, Pan; Malsch, Urban; Bendl, Rolf
2008-09-01
Modern techniques of radiotherapy like intensity modulated radiation therapy (IMRT) make it possible to deliver high dose to tumors of different irregular shapes at the same time sparing surrounding healthy tissue. However, internal tumor motion makes precise calculation of the delivered dose distribution challenging. This makes analysis of tumor motion necessary. One way to describe target motion is using image registration. Many registration methods have already been developed previously. However, most of them belong either to geometric approaches or to intensity approaches. Methods which take account of anatomical information and results of intensity matching can greatly improve the results of image registration. Based on this idea, a combined method of image registration followed by 3D modeling and simulation was introduced in this project. Experiments were carried out for five patients 4DCT lung datasets. In the 3D simulation, models obtained from images of end-exhalation were deformed to the state of end-inhalation. Diaphragm motions were around -25 mm in the cranial-caudal (CC) direction. To verify the quality of our new method, displacements of landmarks were calculated and compared with measurements in the CT images. Improvement of accuracy after simulations has been shown compared to the results obtained only by intensity-based image registration. The average improvement was 0.97 mm. The average Euclidean error of the combined method was around 3.77 mm. Unrealistic motions such as curl-shaped deformations in the results of image registration were corrected. The combined method required less than 30 min. Our method provides information about the deformation of the target volume, which we need for dose optimization and target definition in our planning system.
The dark side of photovoltaic — 3D simulation of glare assessing risk and discomfort
Energy Technology Data Exchange (ETDEWEB)
Rose, Thomas; Wollert, Alexander
2015-04-15
Photovoltaic (PV) systems form an important force in the implementation of renewable energies, but as we all know, the force has always its dark side. Besides efficiency considerations and discussions about architectures of power distribution networks, the increasing numbers of installations of PV systems for implementing renewable energies have secondary effects. PV systems can generate glare due to optical reflections and hence might be a serious concern. On the one hand, glare could affect safety, e.g. regarding traffic. On the other hand, glare is a constant source of discomfort in vicinities of PV systems. Hence, assessment of glare is decisive for the success of renewable energies near municipalities and traffic zones for the success of solar power. Several courts decided on the change of PV systems and even on their de-installation because of glare effects. Thus, location-based assessments are required to limit potential reflections and to avoid risks for public infrastructure or discomfort of residents. The question arises on how to calculate reflections accurately according to the environment's topography. Our approach is founded in a 3D-based simulation methodology to calculate and visualize reflections based on the geometry of the environment of PV systems. This computational model is implemented by an interactive tool for simulation and visualization. Hence, project planners receive flexible assistance for adjusting the parameters of solar panels amid the planning process and in particular before the installation of a PV system. - Highlights: • Solar panels cause glare that impacts neighborhoods and traffic infrastructures. • Glare might cause disability and discomfort. • 3D environment for the calculation of glare • Interactive tool to simulate and visualize reflections • Impact assessment of solar power plant farms.
Large-eddy simulation of 3D turbulent flow past a complete marine hydrokinetic turbine
Kang, S.; Sotiropoulos, F.
2011-12-01
A high-resolution computational framework was recently developed by Kang et al (Adv. Water Resour., submitted) for simulating three-dimensional (3D), turbulent flow past real-life, complete marine hydrokinetic (MHK) turbine configurations. In this model the complex turbine geometry is resolved by employing the curvilinear immersed boundary (CURVIB) method, which solves the 3D unsteady incompressible Navier-Stokes equations in generalized curvilinear domains with embedded arbitrarily complex, moving and/or stationary immersed boundaries (Ge and Sotiropoulos, 2007). Turbulence is simulated using the large-eddy simulation (LES) approach adapted in the context of the CURVIB method, with a wall model based on solving the simplified boundary layer equations used to reconstruct boundary conditions near all solid surfaces (Kang et al., 2011). The model can resolve the flow patterns generated by the rotor and all stationary components of the turbine as well as the interactions of the flow structures with the channel bed. We apply this model to carry out LES of the flow past the model-size hydrokinetic turbine deployed in the St. Anthony Falls Laboratory main channel. The mean velocities and second-order turbulence statistics measured in the downstream wake using acoustic Doppler velocimetry (ADV) are compared with the LES results. The comparisons show that the computed mean velocities and turbulent stresses are in good agreement with the measurements. The high-resolution LES data are used to explore physically important downstream flow characteristics such as the time-averaged wake structure, recovery of cross-sectionally averaged power potential, near-bed scour potential, etc. This work is supported by Verdant Power.
Hybrid Characteristics: 3D radiative transfer for parallel adaptive mesh refinement hydrodynamics
Rijkhorst, E J; Dubey, A; Mellema, G R; Rijkhorst, Erik-Jan; Plewa, Tomasz; Dubey, Anshu; Mellema, Garrelt
2005-01-01
We have developed a three-dimensional radiative transfer method designed specifically for use with parallel adaptive mesh refinement hydrodynamics codes. This new algorithm, which we call hybrid characteristics, introduces a novel form of ray tracing that can neither be classified as long, nor as short characteristics, but which applies the underlying principles, i.e. efficient execution through interpolation and parallelizability, of both. Primary applications of the hybrid characteristics method are radiation hydrodynamics problems that take into account the effects of photoionization and heating due to point sources of radiation. The method is implemented in the hydrodynamics package FLASH. The ionization, heating, and cooling processes are modelled using the DORIC ionization package. Upon comparison with the long characteristics method, we find that our method calculates the column density with a similarly high accuracy and produces sharp and well defined shadows. We show the quality of the new algorithm ...
Numerical Simulation of 3-D Supersonic Viscous Flow in an Experimental MHD Channel
Kato, Hiromasa; Tannehill, John C.; Gupta, Sumeet; Mehta, Unmeel B.
2004-01-01
The 3-D supersonic viscous flow in an experimental MHD channel has been numerically simulated. The experimental MHD channel is currently in operation at NASA Ames Research Center. The channel contains a nozzle section, a center section, and an accelerator section where magnetic and electric fields can be imposed on the flow. In recent tests, velocity increases of up to 40% have been achieved in the accelerator section. The flow in the channel is numerically computed using a new 3-D parabolized Navier-Stokes (PNS) algorithm that has been developed to efficiently compute MHD flows in the low magnetic Reynolds number regime. The MHD effects are modeled by introducing source terms into the PNS equations which can then be solved in a very e5uent manner. To account for upstream (elliptic) effects, the flowfield can be computed using multiple streamwise sweeps with an iterated PNS algorithm. The new algorithm has been used to compute two test cases that match the experimental conditions. In both cases, magnetic and electric fields are applied to the flow. The computed results are in good agreement with the available experimental data.
3D MHD free surface fluid flow simulation based on magnetic-field induction equations
International Nuclear Information System (INIS)
The purpose of this paper is to present our recent efforts on 3D MHD model development and our results based on the technique derived from induced-magnetic-field equations. Two important features are utilized in our numerical method to obtain convergent solutions. First, a penalty factor is introduced in order to force the local divergence free condition of the magnetic fields. The second is that we extend the insulating wall thickness to ensure that the induced magnetic field at its boundaries is null. These simulation results for lithium film free surface flows under NSTX outboard mid-plane magnetic field configurations have shown that 3D MHD effects from a surface normal field gradient cause return currents to interact with surface normal fields and produce unfavorable MHD forces. This leads to a substantial change in flow pattern and a reduction in flow velocity, with most of the flow spilling over one side of the chute. These critical phenomena can not be revealed by 2D models. Additionally, a design which overcomes these undesired flow characteristics is obtained
3D cut-cell modelling for high-resolution atmospheric simulations
Yamazaki, H; Nikiforakis, N
2015-01-01
With the recent, rapid development of computer technology, the resolution of atmospheric numerical models has increased substantially. As a result, steep gradients in mountainous terrain are now being resolved in high-resolution models. This results in large truncation errors in those models using terrain-following coordinates. In this study, a new 3D Cartesian coordinate non-hydrostatic atmospheric model is developed. A cut-cell representation of topography based on finite-volume discretization is combined with a cell-merging approach, in which small cut-cells are merged with neighboring cells either vertically or horizontally. In addition, a block-structured mesh-refinement technique achieves a variable resolution on the model grid with the finest resolution occurring close to the terrain surface. The model successfully reproduces a flow over a 3D bell-shaped hill that shows a good agreement with the flow predicted by the linear theory. The ability of the model to simulate flows over steep terrain is demons...
A Simulated Motion Planning Algorithm in 2d And 3d Environments Using Hill Climbing
Directory of Open Access Journals (Sweden)
Haissam El-Aawar
2014-04-01
Full Text Available This paper describes a computer simulated artificial intell igence (AI agent moving in 2D and 3D environments. In the presented algorithm, the agent can take two operating modes: Manual Mode and Map or Autopilot mode. The user can control the agent fully in a manu al mode by moving it in all possible directions depending on the environment. Obstacles are sense d by the agent from a certain distance and are avoided accordingly. Another important mode is the Map mode. I n this mode the user create a custom map where initial position and a goal position are set. The use r is able also to assign sudden and predefined obstacles. By finding the shortest path, the agent moves to the goal position avoiding any obstacles on its path. The paper documents a set of algorithms that can help the age nt to find the shortest path to a predefined target location in a complex 3D environment, such as cities and mo untains, avoiding all predefined and sudden obstacles. These obstacles are avoided also in manual m ode and the agent moves automatically to a safe location. The implementation is based on the Hill Climb ing algorithm (descent version, where the agent finds its path to the global minimum (target goal. The Map generation algorithm, which is used to assign costs to every location in the map, avoids a lot of the lim itations of Hill Climbing
Sparse Approximations of the Schur Complement for Parallel Algebraic Hybrid Solvers in 3D
Institute of Scientific and Technical Information of China (English)
L.Giraud; A.Haidar; Y.Saad
2010-01-01
In this paper we study the computational performance of variants of an al-gebraic additive Schwarz preconditioner for the Schur complement for the solution of large sparse linear systems. In earlier works, the local Schur complements were com- puted exactly using a sparse direct solver. The robustness of the preconditioner comes at the price of this memory and time intensive computation that is the main bottleneck of the approach for tackling huge problems. In this work we investigate the use of sparse approximation of the dense local Schur complements. These approximations are com-puted using a partial incomplete LU factorization. Such a numerical calculation is the core of the multi-level incomplete factorization such as the one implemented in pARMS. The numerical and computing performance of the new numerical scheme is illustrated on a set of large 3D convection-diffusion problems;preliminary experiments on linear systems arising from structural mechanics are also reported.
Bae, Sung-Kuk; Choi, Beomjoon; Chung, Haseung; Shin, Seungwon; Song, Hee-Eun; Seo, Jung Hwan
2016-03-01
This article presents a novel technique to estimate the mechanical properties of the aluminum composite layer on silicon solar cells by using a hybrid 3-dimensional laser scanning force measurement (3-D LSFM) system. The 3-D LSFM system measures the material properties of sub-layers constituting a solar cell. This measurement is critical for realizing high-efficient ultra-thin solar cells. The screen-printed aluminum layer, which significantly affects the bowing phenomenon, is separated from the complete solar cell by removing the silicon (Si) layer with deep reactive ion etching. An elastic modulus of ~15.1 GPa and a yield strength of ~35.0 MPa for the aluminum (Al) composite layer were obtained by the 3-D LSFM system. In experiments performed for 6-inch Si solar cells, the bowing distances decreased from 12.02 to 1.18 mm while the Si layer thicknesses increased from 90 to 190 μm. These results are in excellent agreement with the theoretical predictions for ultra-thin Si thickness (90 μm) based on the obtained Al composite layer properties.
International Nuclear Information System (INIS)
Hybrid laser/MIG-MAG welding shows high advantages compared to laser welding or GMAW arc welding used separately. Thanks to this process, higher productivity can be gained through higher welding speed, higher squeeze tolerance moreover possible improvement of the metallurgical properties of the weld seam can be obtained. However, many operating parameters have to be set up in order to achieve optimal process. The complex physical phenomena, which govern welding process, have to be understood in order to use efficiently this technique in mass production. Understanding of these phenomena is also necessary to program numerical simulations which fit to this process. In the first step, experimental studies have been carried out with GMAW, laser and hybrid welding on samples of S355 steel. Influence of operating parameters has been analyzed through films performed with speed camera and macro-graphies of weld seam cross section. Surface deformations of the melt pool, induced by the arc pressure, weld pool length, droplet detachment and welding speed, have been analyzed precisely from images of the surface melt pool. In a second step, a numerical model was developed using the COMSOL Multiphysics software for MAG, laser and hybrid laser/MAG welding processes. A 3D quasi-stationary model has been calculated from the temperature field within the metal. The originality of the MAG and hybrid model lies in the prediction of the melt pool surface profile used to determine the 3D geometry, by taking into account the material input. The influence of different parameters such as arc power and speed welding on the efficiency as well as the distribution radius of the arc power and the arc pressure are analyzed through validations with different experimental results and different calculation configurations. (author)
3D Simulation of Flow with Free Surface Based on Adaptive Octree Mesh System
Institute of Scientific and Technical Information of China (English)
Li Shaowu; Zhuang Qian; Huang Xiaoyun; Wang Dong
2015-01-01
The technique of adaptive tree mesh is an effective way to reduce computational cost through automatic adjustment of cell size according to necessity. In the present study, the 2D numerical N-S solver based on the adaptive quadtree mesh system was extended to a 3D one, in which a spatially adaptive octree mesh system and multiple parti-cle level set method were adopted for the convenience to deal with the air-water-structure multiple-medium coexisting domain. The stretching process of a dumbbell was simulated and the results indicate that the meshes are well adaptable to the free surface. The collapsing process of water column impinging a circle cylinder was simulated and from the results, it can be seen that the processes of fluid splitting and merging are properly simulated. The interaction of sec-ond-order Stokes waves with a square cylinder was simulated and the obtained drag force is consistent with the result by the Morison’s wave force formula with the coefficient values of the stable drag component and the inertial force component being set as 2.54.
WebTOP: Interactive 3D Web-based Simulations for Teaching Waves and Optics
Mzoughi, Taha; Foley, John; Herring, Davis; Morris, Matt; Wyser, Ben
2003-03-01
WebTOP is 3D interactive computer graphics system designed to help students learn about waves and optics. It has been used to help teach undergraduate introductory physics and optics classes. It has sixteen modules that treat the following topics: waves, geometrical optics, reflection and refraction, polarization, interference, diffraction, lasers and scattering. WebTOP simulations have the following characteristics. First, they are three dimensional, i.e., they have navigation controls that allow the user to rotate the scene, pan it, or zoom into it. Secondly, they are interactive. The user can change the parameters either by typing the values into boxes, or by using the mouse cursor to move the corresponding widget in the scene. Thirdly, the simulations are animated, when animation is appropriate. Furthermore, the simulations include vcr-type controls that allow the user to record a session for later retrieval and viewing. Finally, these modules run inside a web browser. They can be run from our website, http://webtop.msstate.edu or be downloaded from this website and run locally. In addition to the simulations, each WebTOP module includes a short description of the theory used, and sets of recorded examples and suggested exercises. WebTOP is sponsored in part by the National Science Foundation (DUE 9950569).
The Shock Dynamics of Heterogeneous YSO Jets: 3-D Simulations Meet Multi-Epoch Observations
Hansen, E C; Hartigan, P; Lebedev, S V
2016-01-01
High resolution observations of Young Stellar Object (YSO) jets show them to be composed of many small-scale knots or clumps. In this paper we report results of 3-D numerical simulations designed to study how such clumps interact and create morphologies and kinematic patterns seen in emission line observations. Our simulations focus on clump scale dynamics by imposing velocity differences between spherical, over-dense regions which then lead to the formation of bow shocks as faster clumps overtake slower material. We show that much of the spatial structure apparent in emission line images of jets arises from the dynamics and interactions of these bow shocks. Our simulations show a variety of time-dependent features, including bright knots associated with Mach stems where the shocks intersect, a "frothy" emission structure that arises from the presence of the Non-linear Thin Shell Instability (NTSI) along the surfaces of the bow shocks, and the merging and fragmentation of clumps. Our simulations use a new non...
A GIS-Based 3D Simulation for Occupant Evacuation in a Building
Institute of Scientific and Technical Information of China (English)
TANG Fangqin; ZHANG Xin
2008-01-01
The evacuation efficiency of building plans is of obvious importance to the public safety.The cem- plexity of building plans,however,makes it difficult for the efficiency evaluation.This paper presents a com- putational model AutoEscape,which can simulate the evacuation process for any given occupant distribu. Uon in buildings.Designed as an extensible multi-level structure, the model constructs the geometry level and occupant level and establishes the interactions between levels.The GIS-based environmental analysis is realized to automatically generate the geometric representation and formulate the cognition of agents. The multi-agent based technology is employed to simulate the crowd behaviom with autonomously acting individuals.A visualization component,which provides 3D free observations for the simulation process,is developed on the platform of OGRE and integrated into the system interface in form of ActiveX control.Fi- nally,a case study has been conducted and the results have been compared with the results of an existing model to show the reliability and capacity of AutoEscape simulation.
3D design and electric simulation of a silicon drift detector using a spiral biasing adapter
Li, Yu-yun; Xiong, Bo; Li, Zheng
2016-09-01
The detector system of combining a spiral biasing adapter (SBA) with a silicon drift detector (SBA-SDD) is largely different from the traditional silicon drift detector (SDD), including the spiral SDD. It has a spiral biasing adapter of the same design as a traditional spiral SDD and an SDD with concentric rings having the same radius. Compared with the traditional spiral SDD, the SBA-SDD separates the spiral's functions of biasing adapter and the p-n junction definition. In this paper, the SBA-SDD is simulated using a Sentaurus TCAD tool, which is a full 3D device simulation tool. The simulated electric characteristics include electric potential, electric field, electron concentration, and single event effect. Because of the special design of the SBA-SDD, the SBA can generate an optimum drift electric field in the SDD, comparable with the conventional spiral SDD, while the SDD can be designed with concentric rings to reduce surface area. Also the current and heat generated in the SBA are separated from the SDD. To study the single event response, we simulated the induced current caused by incident heavy ions (20 and 50 μm penetration length) with different linear energy transfer (LET). The SBA-SDD can be used just like a conventional SDD, such as X-ray detector for energy spectroscopy and imaging, etc.
Validation of 3-D Ice Accretion Measurement Methodology for Experimental Aerodynamic Simulation
Broeren, Andy P.; Addy, Harold E., Jr.; Lee, Sam; Monastero, Marianne C.
2015-01-01
Determining the adverse aerodynamic effects due to ice accretion often relies on dry-air wind-tunnel testing of artificial, or simulated, ice shapes. Recent developments in ice-accretion documentation methods have yielded a laser-scanning capability that can measure highly three-dimensional (3-D) features of ice accreted in icing wind tunnels. The objective of this paper was to evaluate the aerodynamic accuracy of ice-accretion simulations generated from laser-scan data. Ice-accretion tests were conducted in the NASA Icing Research Tunnel using an 18-in. chord, two-dimensional (2-D) straight wing with NACA 23012 airfoil section. For six ice-accretion cases, a 3-D laser scan was performed to document the ice geometry prior to the molding process. Aerodynamic performance testing was conducted at the University of Illinois low-speed wind tunnel at a Reynolds number of 1.8 × 10(exp 6) and a Mach number of 0.18 with an 18-in. chord NACA 23012 airfoil model that was designed to accommodate the artificial ice shapes. The ice-accretion molds were used to fabricate one set of artificial ice shapes from polyurethane castings. The laser-scan data were used to fabricate another set of artificial ice shapes using rapid prototype manufacturing such as stereolithography. The iced-airfoil results with both sets of artificial ice shapes were compared to evaluate the aerodynamic simulation accuracy of the laser-scan data. For five of the six ice-accretion cases, there was excellent agreement in the iced-airfoil aerodynamic performance between the casting and laser-scan based simulations. For example, typical differences in iced-airfoil maximum lift coefficient were less than 3 percent with corresponding differences in stall angle of approximately 1 deg or less. The aerodynamic simulation accuracy reported in this paper has demonstrated the combined accuracy of the laser-scan and rapid-prototype manufacturing approach to simulating ice accretion for a NACA 23012 airfoil. For several
Gao, Nuo; Zhu, Shan-an; He, Bin
2005-01-01
We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types o...
International Nuclear Information System (INIS)
Natural circulation decay heat removal is one of the significant issues for fast reactor safety, especially in long term station blackout events. Several sodium experiments were carried out using a 7-subassembly core model for core thermal hydraulics under natural circulation conditions and for onset transients of natural circulation in a decay heat removal system (DHRS) including natural draft. Significant heat removal via inter-wrapper flow was confirmed in the experiments. Solidification of sodium in an air cooler is one of key issues in loss of heat sink events. Natural circulation characteristics under long-term decay heat removal were also obtained. Multi-dimensional phenomena, e.g., thermal stratification and bypass flow in plenums and/or heat exchangers, may influence the natural circulation. Thus, 3D simulation method was developed for entire region in the primary loop. Comparison of temperature distributions in a DHRS heat exchanger between experiment and analysis was done. (author)
Bu, Shuhui; Shiina, Tsuyoshi; Yamakawa, Makoto; Takizawa, Hotaka
Accurate assessment of local myocardial contraction is important for diagnosis of ischemic heart disease, because decreases of myocardial motion often appear in the early stages of the disease. Three-dimensional (3-D) assessment of the stiffness distribution is required for accurate diagnosis of ischemic heart disease. Since myocardium motion occurs radially within the left ventricle wall and the ultrasound beam propagates axially, conventional approaches, such as tissue Doppler imaging and strain-rate imaging techniques, cannot provide us with enough quantitative information about local myocardial contraction. In order to resolve this problem, we propose a novel myocardial contraction imaging system which utilizes the weighted phase gradient method, the extended combined autocorrelation method, and the dynamic grid interpolation (DGI) method. From the simulation results, we conclude that the strain image's accuracy and contrast have been improved by the proposed method.
Testa, Paola; Martinez-Sykora, Juan; Hansteen, Viggo; Carlsson, Mats
2012-01-01
Determining the temperature distribution of coronal plasmas can provide stringent constraints on coronal heating. Current observations with the Extreme ultraviolet Imaging Spectrograph onboard Hinode and the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory provide diagnostics of the emission measure distribution (EMD) of the coronal plasma. Here we test the reliability of temperature diagnostics using 3D radiative MHD simulations. We produce synthetic observables from the models, and apply the Monte Carlo Markov chain EMD diagnostic. By comparing the derived EMDs with the "true" distributions from the model we assess the limitations of the diagnostics, as a function of the plasma parameters and of the signal-to-noise of the data. We find that EMDs derived from EIS synthetic data reproduce some general characteristics of the true distributions, but usually show differences from the true EMDs that are much larger than the estimated uncertainties suggest, especially when structures with signif...
Implementation of 3D Lattice Monte Carlo Simulation on a Cluster of Symmetric Multiprocessors
Institute of Scientific and Technical Information of China (English)
雷咏梅; 蒋英; 等
2002-01-01
This paper presents a new approach to parallelize 3D lattice Monte Carlo algorithms used in the numerical simulation of polymer on ZiQiang 2000-a cluster of symmetric multiprocessors(SMPs).The combined load for cell and energy calculations over the time step is balanced together to form a single spatial decomposition.Basic aspects and strategies of running Monte Carlo calculations on parallel computers are studied.Different steps involved in porting the software on a parallel architecture based on ZiQiang 2000 running under Linux and MPI are described briefly.It is found that parallelization becomes more advantageous when either the lattice is very large or the model contains many cells and chains.
3D Nonlinear Numerical Simulation of Intact and Debonded Reinforced Concrete Beams
Institute of Scientific and Technical Information of China (English)
Chen Quan(陈权); Marcus L.
2004-01-01
To study the behaviour of reinforced concrete (RC) structures with sections of concrete removed and the reinforcement exposed, 3D nonlinear numerical analysis was performed upon both intact and debonded RC beams by using finite element techniques. The deformational characteristics and the ultimate loads were obtained through numerical models, as well as crack and stress distributions. The failure modes can also be deduced from computational results. Compared with intact beams, the normal assumptions of plane section behaviour is not hold true and the patterns of stress and strain are different in debonded RC beams. The numerical results show good consistency with experimental data. This kind of numerical simulation is a supplement to existing codes.
Relativistic MHD simulations of core-collapse GRB jets: 3D instabilities and magnetic dissipation
Bromberg, Omer
2015-01-01
Relativistic jets naturally occur in astrophysical systems that involve accretion onto compact objects, such as core collapse of massive stars in gamma-ray bursts (GRBs) and accretion onto supermassive black holes in active galactic nuclei (AGN). It is generally accepted that these jets are powered electromagnetically, by the magnetised rotation of a central compact object. However, how they produce the observed emission and survive the propagation for many orders of magnitude in distance without being disrupted by current-driven non-axisymmetric instabilities is the subject of active debate. We carry out time-dependent 3D relativistic magnetohydrodynamic simulations of relativistic, Poynting flux dominated jets. The jets are launched self-consistently by the rotation of a strongly magnetised central compact object. This determines the natural degree of azimuthal magnetic field winding, a crucial factor that controls jet stability. We find that the jets are susceptible to two types of instability: (i) a globa...
3-D NUMERICAL SIMULATION OF CONVOY-GENERATED WAVES IN A RESTRICTED WATERWAY
Institute of Scientific and Technical Information of China (English)
JI Sheng Cheng; OUAHSINE Abdellatif; SMAOUI Hassan; SERGENT Philippe
2012-01-01
We consider waves generated by the passing of convoys in a restricted waterway.The magnitude of these waves depends mainly on the geometrical and kinematical parameters of the convoy,such as the speed and the hull geometry.The objective of this study is to predict the relationship between these geometrical and kinematical parameters and the amplitude of ship-generated waves as well as the water plane drawdown.Numerical simulations are conducted by solving the 3-D Navier-Stokes equations along with the standard k-ε model for turbulent processes.The results are compared first with the empirical model and second with experimental measurements performed by the French company Compagnie National du Rh(o)ne (CNR).
GPU-advanced 3D electromagnetic simulations of superconductors in the Ginzburg-Landau formalism
Stošić, Darko; Stošić, Dušan; Ludermir, Teresa; Stošić, Borko; Milošević, Milorad V.
2016-10-01
Ginzburg-Landau theory is one of the most powerful phenomenological theories in physics, with particular predictive value in superconductivity. The formalism solves coupled nonlinear differential equations for both the electronic and magnetic responsiveness of a given superconductor to external electromagnetic excitations. With order parameter varying on the short scale of the coherence length, and the magnetic field being long-range, the numerical handling of 3D simulations becomes extremely challenging and time-consuming for realistic samples. Here we show precisely how one can employ graphics-processing units (GPUs) for this type of calculations, and obtain physics answers of interest in a reasonable time-frame - with speedup of over 100× compared to best available CPU implementations of the theory on a 2563 grid.
Cognitive/emotional models for human behavior representation in 3D avatar simulations
Peterson, James K.
2004-08-01
Simplified models of human cognition and emotional response are presented which are based on models of auditory/ visual polymodal fusion. At the core of these models is a computational model of Area 37 of the temporal cortex which is based on new isocortex models presented recently by Grossberg. These models are trained using carefully chosen auditory (musical sequences), visual (paintings) and higher level abstract (meta level) data obtained from studies of how optimization strategies are chosen in response to outside managerial inputs. The software modules developed are then used as inputs to character generation codes in standard 3D virtual world simulations. The auditory and visual training data also enable the development of simple music and painting composition generators which significantly enhance one's ability to validate the cognitive model. The cognitive models are handled as interacting software agents implemented as CORBA objects to allow the use of multiple language coding choices (C++, Java, Python etc) and efficient use of legacy code.
Numerical methods for 3D tokamak simulations using a flux-surface independent grid
Energy Technology Data Exchange (ETDEWEB)
Stegmeir, A.; Coster, D.; Maj, O.; Lackner, K. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany)
2014-06-15
A numerical approach for 3D Tokamak simulations using a flux surface independent grid is presented. The grid consists of few poloidal planes with a Cartesian isotropic grid within each poloidal plane. Perpendicular operators can be discretised within a poloidal plane using standard second order finite difference methods. The discretisation of parallel operators is achieved with a field line following map and an interpolation. The application of the support operator method to the parallel diffusion operator conserves the self-adjointness of the operator on the discrete level and keeps the numerical decay rate at a low level. The developed numerical methods can be applied to geometries where an X-point is present. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Simulation of 3D material flow in friction stir welding of AA6061-T6
Institute of Scientific and Technical Information of China (English)
Zhang Zhao; Zhang Hongwu
2008-01-01
This paper reports the numerical simulation of the 3D material flow in friction stir welding process by using finite element methods based on solid mechanics. It is found that the material flow behind the pin is much faster than that in front of the pin. The material in front of the pin moves upwards and then rotates with the pin due to the effect of the rotating tool. Behind of the pin, the material moves downwards. This process of material movement is the real cause to make the friction stir welding process continuing successfully. With the increase of the translational velocity or the rotational velocity of the pin, the material flow becomes faster.
Harvey, R. W. (Bob); Petrov, Yu. V.; Jaeger, E. F.; Berry, L. A.; Bonoli, P. T.; Bader, A.
2015-11-01
A time-dependent simulation of C-Mod pulsed ICRF power is made calculating minority hydrogen ion distribution functions with the CQL3D-Hybrid-FOW finite-orbit-width Fokker-Planck code. ICRF fields are calculated with the AORSA full wave code, and RF diffusion coefficients are obtained from these fields using the DC Lorentz gyro-orbit code. Prior results with a zero-banana-width simulation using the CQL3D/AORSA/DC time-cycles showed a pronounced enhancement of the H distribution in the perpendicular velocity direction compared to results obtained from Stix's quasilinear theory, in general agreement with experiment. The present study compares the new FOW results, including relevant gyro-radius effects, to determine the importance of these effects on the the NPA synthetic diagnostic time-dependence. The new NPA results give increased agreement with experiment, particularly in the ramp-down time after the ICRF pulse. Funded, through subcontract with Massachusetts Institute of Technology, by USDOE sponsored SciDAC Center for Simulation of Wave-Plasma Interactions.
Analysis of writing characteristics of CF-SPT head using 3-D read/write simulation system
Ohtake, Masaya; Takahashi, Norio; Shinagawa, Kiminari
2004-01-01
Recently, the increase of areal recording density is remarkable. In order to develop a high density recording device, a read/write (R/W) simulation using three dimensional (3-D) magnetic field analysis is indispensable. In this paper, the magnetic field in a cusp-field single-pole-type (CF-SPT) head with discrete track media is analyzed using a 3-D R/W simulation system, in which edge-based finite element method and 3-D medium hysteresis model based on the ensemble of the Stoner-Wohlfarth (SW...
Borazjani, Iman; Ge, Liang; Sotiropoulos, Fotis
2008-08-10
The sharp-interface CURVIB approach of Ge and Sotiropoulos [L. Ge, F. Sotiropoulos, A Numerical Method for Solving the 3D Unsteady Incompressible Navier-Stokes Equations in Curvilinear Domains with Complex Immersed Boundaries, Journal of Computational Physics 225 (2007) 1782-1809] is extended to simulate fluid structure interaction (FSI) problems involving complex 3D rigid bodies undergoing large structural displacements. The FSI solver adopts the partitioned FSI solution approach and both loose and strong coupling strategies are implemented. The interfaces between immersed bodies and the fluid are discretized with a Lagrangian grid and tracked with an explicit front-tracking approach. An efficient ray-tracing algorithm is developed to quickly identify the relationship between the background grid and the moving bodies. Numerical experiments are carried out for two FSI problems: vortex induced vibration of elastically mounted cylinders and flow through a bileaflet mechanical heart valve at physiologic conditions. For both cases the computed results are in excellent agreement with benchmark simulations and experimental measurements. The numerical experiments suggest that both the properties of the structure (mass, geometry) and the local flow conditions can play an important role in determining the stability of the FSI algorithm. Under certain conditions unconditionally unstable iteration schemes result even when strong coupling FSI is employed. For such cases, however, combining the strong-coupling iteration with under-relaxation in conjunction with the Aitken's acceleration technique is shown to effectively resolve the stability problems. A theoretical analysis is presented to explain the findings of the numerical experiments. It is shown that the ratio of the added mass to the mass of the structure as well as the sign of the local time rate of change of the force or moment imparted on the structure by the fluid determine the stability and convergence of the FSI
Borazjani, Iman; Ge, Liang; Sotiropoulos, Fotis
2008-08-10
The sharp-interface CURVIB approach of Ge and Sotiropoulos [L. Ge, F. Sotiropoulos, A Numerical Method for Solving the 3D Unsteady Incompressible Navier-Stokes Equations in Curvilinear Domains with Complex Immersed Boundaries, Journal of Computational Physics 225 (2007) 1782-1809] is extended to simulate fluid structure interaction (FSI) problems involving complex 3D rigid bodies undergoing large structural displacements. The FSI solver adopts the partitioned FSI solution approach and both loose and strong coupling strategies are implemented. The interfaces between immersed bodies and the fluid are discretized with a Lagrangian grid and tracked with an explicit front-tracking approach. An efficient ray-tracing algorithm is developed to quickly identify the relationship between the background grid and the moving bodies. Numerical experiments are carried out for two FSI problems: vortex induced vibration of elastically mounted cylinders and flow through a bileaflet mechanical heart valve at physiologic conditions. For both cases the computed results are in excellent agreement with benchmark simulations and experimental measurements. The numerical experiments suggest that both the properties of the structure (mass, geometry) and the local flow conditions can play an important role in determining the stability of the FSI algorithm. Under certain conditions unconditionally unstable iteration schemes result even when strong coupling FSI is employed. For such cases, however, combining the strong-coupling iteration with under-relaxation in conjunction with the Aitken's acceleration technique is shown to effectively resolve the stability problems. A theoretical analysis is presented to explain the findings of the numerical experiments. It is shown that the ratio of the added mass to the mass of the structure as well as the sign of the local time rate of change of the force or moment imparted on the structure by the fluid determine the stability and convergence of the FSI
3D simulations of young core-collapse supernova remnants undergoing efficient particle acceleration
Ferrand, Gilles
2016-01-01
Within our Galaxy, supernova remnants are believed to be the major sources of cosmic rays up to the "knee". However important questions remain regarding the share of the hadronic and leptonic components, and the fraction of the supernova energy channelled into these components. We address such question by the means of numerical simulations that combine a hydrodynamic treatment of the shock wave with a kinetic treatment of particle acceleration. Performing 3D simulations allows us to produce synthetic projected maps and spectra of the thermal and non-thermal emission, that can be compared with multi-wavelength observations (in radio, X-rays, and gamma-rays). Supernovae come in different types, and although their energy budget is of the same order, their remnants have different properties, and so may contribute in different ways to the pool of Galactic cosmic-rays. Our first simulations were focused on thermonuclear supernovae, like Tycho's SNR, that usually occur in a mostly undisturbed medium. Here we present...
Simulation of water temperature in two reservoirs with Delft3d
Yang, J. Y.; Zhou, L. Y.
2016-08-01
The proposeled Guanjingkou and Fengdou reservoir will be constructed at Chongqing city and Muling city in China respectively. The water temperature in the reservoir, in the downstream, and the aquatic ecosystem would be altered by the construction of the reservoirs. This paper simulates the water temperature in the two reservoirs by using the Delft3d z-layer model, which uses the fixed elevation for layers. According to the simulation results, the temperature profile in the reservoirs can be divided into three layers: the upmost epilimnion layer, the beneathed thermocline layer, and the constant tepmerature layer at bottom. The temperature effects can be reduced by measurements of stoplogs gates and mutiple gates, respectively. Based on the simulation results in the wet, nomal, and dry year, the temperature of water released from the stoplogs gates at Guanjingkou reservior can be respectively increased by 5.7°C, 6.8°C, 9.6°C, and 5.5°C in the irrigation season from May to August. The temperature of water released from the mutiple gates at Fengdou reservior can be respectively increased by 7.7 °C, 1.9 °C, 9.5 °C, and 10.1 °C from May to August. The negative impacts from the water with lower temperature on the related ecosystem can be significently alleviated.
Multi-scale 3D simulation of lightning and thunderstorm electrodynamics
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.
Study on 3-D simulation of flow and turbidity in an oxbow lake in tidal compartment
Yokoyama, H.; Momonoe, H.; Hamamoto, S.
2010-12-01
We aimed to make flow and turbidity simulation model for an oxbow lake in tidal compartment. The oxbow has two bottle-necks and inflow river from urban district. Bed topography of the oxbow is former meandering channel of large-basin river. Therefore characteristic of flow and water quality is complex. First, field observation was conducted to clarify the characteristics of flow and water quality in the oxbow. From observation results, flow and resuspension phenomena in the oxbow were affected by wind and tide, and the balance of the two factors changed longitudinally. Next, we built 3-D simulation model of flow which took account of the field observation results. In order to investigate effective water quality improvement, we set some test cases: condition of wind, inflow river were changed. From the simulation results, tide was the most important factor, however at the upper part of the oxbow, where the tidal power seemed to be weaker, flow and turbidity were clearly affected by the wind.
Realistic 3D Terrain Roaming and Real-Time Flight Simulation
Que, Xiang; Liu, Gang; He, Zhenwen; Qi, Guang
2014-12-01
This paper presents an integrate method, which can provide access to current status and the dynamic visible scanning topography, to enhance the interactive during the terrain roaming and real-time flight simulation. A digital elevation model and digital ortho-photo map data integrated algorithm is proposed as the base algorithm for our approach to build a realistic 3D terrain scene. A new technique with help of render to texture and head of display for generating the navigation pane is used. In the flight simulating, in order to eliminate flying "jump", we employs the multidimensional linear interpolation method to adjust the camera parameters dynamically and steadily. Meanwhile, based on the principle of scanning laser imaging, we draw pseudo color figures by scanning topography in different directions according to the real-time flying status. Simulation results demonstrate that the proposed algorithm is prospective for applications and the method can improve the effect and enhance dynamic interaction during the real-time flight.
The Making of FR Is I. Numerical Hydrodynamic 3D Simulations of Low Power Jets
Massaglia, S; Rossi, P; Capetti, S; Mignone, A
2016-01-01
Extragalactic radiosources have been classified in two classes, Fanaroff-Riley I and II, which differ in morphology and radio power. Strongly emitting sources belong to the edge brightened FR II class while the weak ones to the edge darkened FR I class. The origin of this dichotomy is not yet fully understood. Numerical simulations are successful in generating FR~II morphologies but they fail to reproduce the diffuse structure of FR Is. By means of hydro-dynamical 3D simulations of supersonic jets, we investigate how the displayed morphologies depend on the jet parameters. Bow shocks and Mach disks at the jet's head, likely responsible for the presence of hot spots in the FR II sources, disappear for a jet kinetic power less than 10^43 erg/s. This threshold compares favorably with the luminosity at which the FR~I/FR~II transition is observed. The problem is addressed by numerical means carrying out three-dimensional HD simulations of supersonic jets that propagate in a non homogeneous medium with the ambient ...
3D MHD Simulations of accreting neutron stars: evidence of QPO emission from the surface
Bachetti, Matteo; Kulkarni, Akshay; Burderi, Luciano; di Salvo, Tiziana; .,
2009-01-01
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 $\\dot{M}$. Moreover, in some cases double QPOs appear, each of them showing the same correlation with $\\dot{M}$.
Flux Emergence In The Solar Photosphere - Diagnostics Based On 3-D Rradiation-MHD Simulations
Yelles Chaouche, L.; Cheung, M.; Lagg, A.; Solanki, S.
2006-08-01
We investigate flux tube emergence in the solar photosphere using a diagnostic procedure based on analyzing Stokes signals from different spectral lines calculated in 3-D radiation-MHD simulations. The simulations include the effects of radiative transport and partial ionization and cover layers both above and below the solar surface. The simulations consider the emergence of a twisted magnetic flux tube through the solar surface. We consider different stages in the emergence process, starting from the early appearance of the flux tube at the solar surface, and following the emergence process until the emerged flux looks similar to a normal bipolar region. At every stage we compute line profiles by numerically solving the Unno-Rachkovsky equations at every horizontal grid point. Then, following observational practice, we apply Milne-Eddington-type inversions to the synthetic spectra in order to retrieve different atmospheric parameters. We include the influence of spatial smearing on the deduced atmospheric parameters to identify signatures of different stages of flux emergence in the solar photosphere.
Numerical simulation of unsteady flow characteristics for cavitation around a 3-D hydrofoil
Ahn, S. H.; Xiao, Y. X.; Wang, Z. W.
2015-01-01
At present it is possible to predict more accurately by various numerical methods established for cavitation simulation around a hydrofoil. However, for the solution of the complex unsteady cavity flow, it is still marginal. In this paper, numerical method is adopted to simulate cavitation around 3-D NACA0015 hydrofoil with homogeneous two-phase flow calculation using commercial code CFX-solver with two turbulence models, the standard RNG k-epsilon turbulence model and the modified RNG k-epsilon turbulence model respectively. First, pressure coefficient for non-cavitating flow, time averaged values of unsteady cavity flow around a hydrofoil are verified to simulate more closely to an actual cavity flow. And then frequency analysis is performed with Fast Fourier Transform. The results show that the calculation results with modified RNG k-epsilon turbulence model agree with experimental results in terms of mean cavity length and pressure drop, but the unsteady flow characteristics of oscillating cavitation still deviate slightly in terms of unsteady cavity flow.
Easy, Luke; Omotani, John; Dudson, Benjamin; Havlíčková, Eva; Tamain, Patrick; Naulin, Volker; Nielsen, Anders H
2014-01-01
This paper presents simulations of isolated 3D filaments in a slab geometry obtained using a 3D reduced fluid code. First, systematic scans were performed to investigate how the dynamics of a filament are affected by its amplitude, perpendicular size and parallel extent. The perpendicular size of the filament was found to have a strong influence on its motions, as it determined the relative importance of parallel currents to polarisation and viscous currents, whilst drift-wave instabilities were observed if the initial amplitude of the blob was increased sufficiently. Next, the 3D simulations were compared to 2D simulations using different parallel closures; namely, the sheath dissipation closure, which neglects parallel gradients, and the vorticity advection closure, which neglects the influence of parallel currents. The vorticity advection closure was found to not replicate the 3D perpendicular dynamics and overestimated the initial radial acceleration of all the filaments studied. In contrast, a more satis...
3D Staggered-Grid Finite-Difference Simulation of Acoustic Waves in Turbulent Moving Media
Symons, N. P.; Aldridge, D. F.; Marlin, D.; Wilson, D. K.; Sullivan, P.; Ostashev, V.
2003-12-01
Acoustic wave propagation in a three-dimensional heterogeneous moving atmosphere is accurately simulated with a numerical algorithm recently developed under the DOD Common High Performance Computing Software Support Initiative (CHSSI). Sound waves within such a dynamic environment are mathematically described by a set of four, coupled, first-order partial differential equations governing small-amplitude fluctuations in pressure and particle velocity. The system is rigorously derived from fundamental principles of continuum mechanics, ideal-fluid constitutive relations, and reasonable assumptions that the ambient atmospheric motion is adiabatic and divergence-free. An explicit, time-domain, finite-difference (FD) numerical scheme is used to solve the system for both pressure and particle velocity wavefields. The atmosphere is characterized by 3D gridded models of sound speed, mass density, and the three components of the wind velocity vector. Dependent variables are stored on staggered spatial and temporal grids, and centered FD operators possess 2nd-order and 4th-order space/time accuracy. Accurate sound wave simulation is achieved provided grid intervals are chosen appropriately. The gridding must be fine enough to reduce numerical dispersion artifacts to an acceptable level and maintain stability. The algorithm is designed to execute on parallel computational platforms by utilizing a spatial domain-decomposition strategy. Currently, the algorithm has been validated on four different computational platforms, and parallel scalability of approximately 85% has been demonstrated. Comparisons with analytic solutions for uniform and vertically stratified wind models indicate that the FD algorithm generates accurate results with either a vanishing pressure or vanishing vertical-particle velocity boundary condition. Simulations are performed using a kinematic turbulence wind profile developed with the quasi-wavelet method. In addition, preliminary results are presented
Real-Time Climate Simulations in the Interactive 3D Game Universe Sandbox ²
Goldenson, N. L.
2014-12-01
Exploration in an open-ended computer game is an engaging way to explore climate and climate change. Everyone can explore physical models with real-time visualization in the educational simulator Universe Sandbox ² (universesandbox.com/2), which includes basic climate simulations on planets. I have implemented a time-dependent, one-dimensional meridional heat transport energy balance model to run and be adjustable in real time in the midst of a larger simulated system. Universe Sandbox ² is based on the original game - at its core a gravity simulator - with other new physically-based content for stellar evolution, and handling collisions between bodies. Existing users are mostly science enthusiasts in informal settings. We believe that this is the first climate simulation to be implemented in a professionally developed computer game with modern 3D graphical output in real time. The type of simple climate model we've adopted helps us depict the seasonal cycle and the more drastic changes that come from changing the orbit or other external forcings. Users can alter the climate as the simulation is running by altering the star(s) in the simulation, dragging to change orbits and obliquity, adjusting the climate simulation parameters directly or changing other properties like CO2 concentration that affect the model parameters in representative ways. Ongoing visuals of the expansion and contraction of sea ice and snow-cover respond to the temperature calculations, and make it accessible to explore a variety of scenarios and intuitive to understand the output. Variables like temperature can also be graphed in real time. We balance computational constraints with the ability to capture the physical phenomena we wish to visualize, giving everyone access to a simple open-ended meridional energy balance climate simulation to explore and experiment with. The software lends itself to labs at a variety of levels about climate concepts including seasons, the Greenhouse effect
A Case Study of a Hybrid Parallel 3D Surface Rendering Graphics Architecture
DEFF Research Database (Denmark)
Holten-Lund, Hans Erik; Madsen, Jan; Pedersen, Steen
1997-01-01
This paper presents a case study in the design strategy used inbuilding a graphics computer, for drawing very complex 3Dgeometric surfaces. The goal is to build a PC based computer systemcapable of handling surfaces built from about 2 million triangles, andto be able to render a perspective view...... of these on a computer displayat interactive frame rates, i.e. processing around 50 milliontriangles per second. The paper presents a hardware/softwarearchitecture called HPGA (Hybrid Parallel Graphics Architecture) whichis likely to be able to carry out this task. The case study focuses ontechniques to increase...... the clock frequency as well as the parallelismof the system. This paper focuses on the back-end graphics pipeline,which is responsible for rasterizing triangles.%with a practically linear increase in performance. A pure software implementation of the proposed architecture iscurrently able to process 300...
3D Bridged Carbon Nanoring/Graphene Hybrid Paper as a High-Performance Lateral Heat Spreader.
Zhang, Jianwei; Shi, Gang; Jiang, Cai; Ju, Su; Jiang, Dazhi
2015-12-01
Graphene paper (GP) has attracted great attention as a heat dissipation material due to its unique thermal transfer property exceeding the limit of graphite. However, the relatively poor thermal transfer properties in the normal direction of GP restricts its wider applications in thermal management. In this work, a 3D bridged carbon nanoring (CNR)/graphene hybrid paper is constructed by the intercalation of polymer carbon source and metal catalyst particles, and the subsequent in situ growth of CNRs in the confined intergallery spaces between graphene sheets through thermal annealing. Further investigation demonstrates that the CNRs are covalently bonded to the graphene sheets and highly improve the thermal transport in the normal direction of the CNR/graphene hybrid paper. This full-carbon architecture shows excellent heat dissipation ability and is much more efficient in removing hot spots than the reduced GP without CNR bridges. This highly thermally conductive CNR/graphene hybrid paper can be easily integrated into next generation commercial high-power electronics and stretchable/foldable devices as high-performance lateral heat spreader materials. This full-carbon architecture also has a great potential in acting as electrodes in supercapacitors or hydrogen storage devices due to the high surface area. PMID:26476622
A faster method for 3D/2D medical image registration - a simulation study
Energy Technology Data Exchange (ETDEWEB)
Birkfellner, Wolfgang [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland); Wirth, Joachim [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland); Burgstaller, Wolfgang [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland); Baumann, Bernard [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland); Staedele, Harald [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland); Hammer, Beat [Department of Reconstructive Surgery, University Hospital Basel (Switzerland); Gellrich, Niels Claudius [Department of Oral and Maxillofacial Surgery, University of Freiburg (Germany); Jacob, Augustinus Ludwig [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland); Regazzoni, Pietro [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland); Messmer, Peter [CARCAS-Switzerland, University Hospitals Basel and Zurich (Switzerland)
2003-08-21
3D/2D patient-to-computed-tomography (CT) registration is a method to determine a transformation that maps two coordinate systems by comparing a projection image rendered from CT to a real projection image. Iterative variation of the CT's position between rendering steps finally leads to exact registration. Applications include exact patient positioning in radiation therapy, calibration of surgical robots, and pose estimation in computer-aided surgery. One of the problems associated with 3D/2D registration is the fact that finding a registration includes solving a minimization problem in six degrees of freedom (dof) in motion. This results in considerable time requirements since for each iteration step at least one volume rendering has to be computed. We show that by choosing an appropriate world coordinate system and by applying a 2D/2D registration method in each iteration step, the number of iterations can be grossly reduced from n{sup 6} to n{sup 5}. Here, n is the number of discrete variations around a given coordinate. Depending on the configuration of the optimization algorithm, this reduces the total number of iterations necessary to at least 1/3 of it's original value. The method was implemented and extensively tested on simulated x-ray images of a tibia, a pelvis and a skull base. When using one projective image and a discrete full parameter space search for solving the optimization problem, average accuracy was found to be 1.0 {+-} 0.6 (deg.) and 4.1 {+-} 1.9 (mm) for a registration in six parameters, and 1.0 {+-} 0.7 (deg.) and 4.2 {+-} 1.6 (mm) when using the 5 + 1 dof method described in this paper. Time requirements were reduced by a factor 3.1. We conclude that this hardware-independent optimization of 3D/2D registration is a step towards increasing the acceptance of this promising method for a wide number of clinical applications.
Directory of Open Access Journals (Sweden)
Chenming Xue
2015-03-01
Full Text Available Three-dimensional (3D layer-by-layer graphene-gold nanorod (GNR architecture has been constructed. The resulting hybrid nanomaterials’ architecture has been tested for detecting hydrogen peroxide (H2O2 through the electrocatalytic reaction on a three electrode disposable biosensor platform. Cyclic voltammetry and amperometry were used to characterize and assess the performance of the biosensor. The 3D layer-by-layer modified electrode exhibited the highest sensitivity compared to the active carbon, graphene-oxide, cysteine-graphene oxide and GNR coated electrodes. This research explored the feasibility of using the 3D hybrid graphene-GNR as a template for biosensor. The 3D hybrid structure exhibited higher sensitivity than GNRs alone. SEM showed the explanation that GNRs had self-aggregates reducing the contact surface area when coated on the active carbon electrode, while there were no such aggregates in the 3D structure, and TEM illustrated that GNRs dispersed well in the 3D structure. This research demonstrated a better way to prepare well-separated metal nanoparticles by using the 3D layer-by-layer structure. Consequently, other single and bi-metallic metal nanoparticles could be incorporated into such structure. As a practical example, 3D layer-by-layer nanomaterials modified active carbon electrode was used for detecting glucose showing very good sensitivity and minimum interference by ascorbic acid and uric acid in test solution, which indicated a good selectivity of the biosensor as well.
Radiative 3D MHD simulations of the spontaneous small-scale eruptions in the solar atmosphere
Kitiashvili, Irina N.
2015-08-01
Studying non-linear turbulent dynamics of the solar atmosphere is important for understanding mechanism of the solar and stellar brightness variations. High-resolution observations of the quiet Sun reveal ubiquitous distributions of high-speed jets, which are transport mass and energy into the solar corona and feeding the solar wind. However, the origin of these eruption events is still unknown. Using 3D realistic MHD numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push the surrounding material up, generating shocks. Our simulations reveal complicated high-speed flow patterns and thermodynamic and magnetic structure in the erupting vortex tubes and shows that the eruptions are initiated in the subsurface layers and are driven by high-pressure gradients in the subphotosphere and photosphere and by the Lorentz force in the higher atmosphere layers. I will discuss about properties of these eruptions, their effects on brightness and spectral variations and comparison with observations.
Pelton turbine Needle erosion prediction based on 3D three- phase flow simulation
International Nuclear Information System (INIS)
Pelton turbine, which applied to the high water head and small flow rate, is widely used in the mountainous area. During the operation period the sediment contained in the water does not only induce the abrasion of the buckets, but also leads to the erosion at the nozzle which may damage the needle structure. The nozzle and needle structure are mainly used to form high quality cylindrical jet and increase the efficiency of energy exchange in the runner to the most. Thus the needle erosion will lead to the deformation of jet, and then may cause the efficiency loss and cavitation. The favourable prediction of abrasion characteristic of needle can effectively guide the optimization design and maintenance of needle structure. This paper simulated the unsteady three-dimensional multi-phase flow in the nozzle and injected jet flow. As the jet containing water and sediment is injected into the free atmosphere air with high velocity, the VOF model was adopted to predict the water and air flow. The sediment is simplified into round solid particle and the discrete particle model (DPM) was employed to predict the needle abrasion characteristic. The sand particle tracks were analyzed to interpret the mechanism of sand erosion on the needle surface. And the numerical result of needle abrasion was obtained and compared with the abrasion field observation. The similarity of abrasion pattern between the numerical results and field observation illustrated the validity of the 3D multi-phase flow simulation method
3D simulations of disc-winds extending radially self-similar MHD models
Stute, Matthias; Vlahakis, Nektarios; Tsinganos, Kanaris; Mignone, Andrea; Massaglia, Silvano
2014-01-01
Disc-winds originating from the inner parts of accretion discs are considered as the basic component of magnetically collimated outflows. The only available analytical MHD solutions to describe disc-driven jets are those characterized by the symmetry of radial self-similarity. However, radially self-similar MHD jet models, in general, have three geometrical shortcomings, (i) a singularity at the jet axis, (ii) the necessary assumption of axisymmetry, and (iii) the non-existence of an intrinsic radial scale, i.e. the jets formally extend to radial infinity. Hence, numerical simulations are necessary to extend the analytical solutions towards the axis, by solving the full three-dimensional equations of MHD and impose a termination radius at finite radial distance. We focus here on studying the effects of relaxing the (ii) assumption of axisymmetry, i.e. of performing full 3D numerical simulations of a disc-wind crossing all magnetohydrodynamic critical surfaces. We compare the results of these runs with previou...
3D MHD Simulations of Laser Plasma Guiding in Curved Magnetic Field
Roupassov, S.; Rankin, R.; Tsui, Y.; Capjack, C.; Fedosejevs, R.
1999-11-01
The guiding and confinement of laser produced plasma in a curved magnetic field has been investigated numerically. These studies were motivated by experiments on pulsed laser deposition of diamond-like films [1] in which a 1kG magnetic field in a curved solenoid geometry was utilized to steer a carbon plasma around a curved trajectory and thus to separate it from unwanted macroparticles produced by the laser ablation. The purpose of the modeling was to characterize the plasma dynamics during the propagation through the magnetic guide field and to investigate the effect of different magnetic field configurations. A 3D curvilinear ADI code developed on the basis of an existing Cartesian code [2] was employed to simulate the underlying resistive one-fluid MHD model. Issues such as large regions of low background density and nonreflective boundary conditions were addressed. Results of the simulations in a curved guide field will be presented and compared to experimental results. [1] Y.Y. Tsui, D. Vick and R. Fedosejevs, Appl. Phys. Lett. 70 (15), pp. 1953-57, 1997. [2] R. Rankin, and I. Voronkov, in "High Performance Computing Systems and Applications", pp. 59-69, Kluwer AP, 1998.
Spicule-like structures observed in 3D realistic MHD simulations
Martinez-Sykora, J; De Pontieu, B; Carlsson, M
2009-01-01
We analyze features that resemble type i spicules in two different 3D numerical simulations in which we include horizontal magnetic flux emergence in a computational domain spanning the upper layers of the convection zone to the lower corona. The two simulations differ mainly in the preexisting ambient magnetic field strength and in the properties of the inserted flux tube. We use the Oslo Staggered Code (OSC) to solve the full MHD equations with non-grey and non-LTE radiative transfer and thermal conduction along the magnetic field lines. We find a multitude of features that show a spatiotemporal evolution that is similar to that observed in type i spicules, which are characterized by parabolic height vs. time profiles, and are dominated by rapid upward motion at speeds of 10-30 km/s, followed by downward motion at similar velocities. We measured the parameters of the parabolic profile of the spicules and find similar correlations between the parameters as those found in observations. The values for height (...
Statistical Analysis of Detailed 3-D CFD LES Simulations with Regard to CCV Modeling
Directory of Open Access Journals (Sweden)
Vítek Oldřich
2016-06-01
Full Text Available The paper deals with statistical analysis of large amount of detailed 3-D CFD data in terms of cycle-to-cycle variations (CCVs. These data were obtained by means of LES calculations of many consecutive cycles. Due to non-linear nature of Navier-Stokes equation set, there is a relatively significant CCV. Hence, every cycle is slightly different – this leads to requirement to perform statistical analysis based on ensemble averaging procedure which enables better understanding of CCV in ICE including its quantification. The data obtained from the averaging procedure provides results on different space resolution levels. The procedure is applied locally, i.e., in every cell of the mesh. Hence there is detailed CCV information on local level – such information can be compared with RANS simulations. Next, volume/mass averaging provides information at specific locations – e.g., gap between electrodes of a spark plug. Finally, volume/mass averaging of the whole combustion chamber leads to global information which can be compared with experimental data or results of system simulation tools (which are based on 0-D/1-D approach.
Nonlinear 3-D simulation of high-intensity focused ultrasound therapy in the kidney
Suomi, Visa; Treeby, Bradley; Cleveland, Robin
2016-01-01
Kidney cancer is a severe disease which can be treated non-invasively using high-intensity focused ultrasound (HIFU) therapy. However, tissue in front of the transducer and the deep location of kidney can cause significant losses to the efficiency of the treatment. The effect of attenuation, refraction and reflection due to different tissue types on HIFU therapy of the kidney was studied using a nonlinear ultrasound simulation model. The geometry of the tissue was derived from a computed tomography (CT) dataset of a patient which had been segmented for water, bone, soft tissue, fat and kidney. The combined effect of inhomogeneous attenuation and sound-speed was found to result in an 11.0 dB drop in spatial peak-temporal average (SPTA) intensity in the kidney compared to pure water. The simulation without refraction effects showed a 6.3 dB decrease indicating that both attenuation and refraction contribute to the loss in focal intensity. The losses due to reflections at soft tissue interfaces were less than 0....
Taha, Uday; Shabeeb, Ahmed; dragonetti, giovanna; Lamaddalena, Nicola; Coppola, Antonio
2016-04-01
This work analyzed the variability of sprinkler irrigation application over a bare soil, both in terms of water application efficiency and uniformity, by integrating and comparing the information on the irrigation depth data (ID), as measured by catch cans, soil water storage in the upper root zone, as measured by TDR probes, and a 3D simulations of water flow in soils. Three irrigation tests were performed at three different pressures (2, 3 and 4 bar). A lateral water redistribution was observed and simulated after each irrigation event by comparing spatial distributions of site-specific water application efficiency (AEs), as well as ratios of site-specific actual water storage increase (SWEs) and irrigation depth (IDs) to the water content before irrigation. Because of soil water redistribution processes, distribution uniformity based on soil storages was systematically higher than the catch can uniformity. The obvious consequence of lateral water redistribution processes was that the soil smoothing action on non-uniformity observed at the surface increased both with depth and over time. At a given depth the uniformity of soil water storages always attained the same value, whatever the pressure considered and the catch can-based uniformity coefficient. It was concluded that, for the case of random distribution of ID, the uniformity of water storages is driven by the soil behavior rather than by the irrigation system.
International Nuclear Information System (INIS)
This paper presents the simulation of 3D free surface flows by the two-phase least-squares finite element method (LSFEM). It is believed that this is the first time the LSFEM be extended from a 2D model to a 3D one and applied to investigate the 3D free surface flow phenomena. The dynamic and kinematic boundary conditions of free surface are described in an Eulerian coordinate system. The governing 3D Navier-Stokes equations in association with the color function are solved by the element-by-element scheme. In this simulation, the volume of fluid (VOF) method and continuous stress force (CSF) models are applied for the determination of the interface between the two phases of liquid and gas. The free surface position at each time step is determined by the distribution of the color function. The formation of the 3D model is carefully examined; and the quantitative comparisons of the 3D numerical simulations with experimental measurements and previous 2D numerical results are verified in good agreement. For the partial dam-break flows, it is shown that the two-phase LSFEM can effectively simulate the 3D flows. The unsteady water surface profiles of dam-break flow moving over an obstacle and the liquid drop are also simulated in this study. A 3D two-phase LSFEM has been established and carefully justified by some benchmark free surface flows. The method will be useful for the actual application to the two-phase flows with two immiscible fluids, such as liquid-gas flow, and metallurgic flow.
Ngirmang, Gregory K; Feister, Scott; Morrison, John T; Chowdhury, Enam A; Frische, Kyle; Roquemore, W M
2015-01-01
We present 3D Particle-in-Cell (PIC) modeling of an ultra-intense laser experiment by the Extreme Light group at the Air Force Research Laboratory (AFRL) using the PIC code LSP. This is the first time PIC simulations have been performed in 3D for this experiment which involves an ultra-intense, short-pulse (30 fs) laser interacting with a water jet target at normal incidence. These 3D PIC simulation results are compared to results from 2D(3$v$) PIC simulations for both $5.4\\cdot10^{17}$ W cm$^{-2}$ and $3\\cdot10^{18}$ W cm$^{-2}$ intensities. Comparing the 2D(3$v$) and 3D simulation results, the laser-energy-to-ejected-electron-energy conversion efficiencies were comparable, but the angular distribution of ejected electrons show interesting differences with qualitative differences at higher intensity. An analytic plane-wave model is provided that provides some explanation for the angular distribution and energies of ejected electrons in the 2D(3$v$) simulations. We also performed a 3D simulation with circular...
International Nuclear Information System (INIS)
In a non-reactor tokamak environment, lower hybrid current drive can be combined with electron cyclotron waves, both (1) to control the radial profile of LH current deposition, and (2) to enhance the current drive efficiency. A related rf synergy is the use of multiple LH spectra for radial profile control as demonstrated in the ASDEX tokamak. In a reactor environment, fast waves provide an appropriate primary current drive system which can penetrate radially to the plasma core, and can be combined with ECCD. We use the CQL3D Fokker-Planck code to study these processes. Modelings of LHCD radial profile control by ''filling the spectral gap'' with EC or with additional LH power are presented. In the reactor environment, a range of cases with combined fast wave and electron cyclotron waves are examined, but no useful synergisms are found
Piezoresistive Sensor with High Elasticity Based on 3D Hybrid Network of Sponge@CNTs@Ag NPs.
Zhang, Hui; Liu, Nishuang; Shi, Yuling; Liu, Weijie; Yue, Yang; Wang, Siliang; Ma, Yanan; Wen, Li; Li, Luying; Long, Fei; Zou, Zhengguang; Gao, Yihua
2016-08-31
Pressure sensors with high elasticity are in great demand for the realization of intelligent sensing, but there is a need to develope a simple, inexpensive, and scalable method for the manufacture of the sensors. Here, we reported an efficient, simple, facile, and repeatable "dipping and coating" process to manufacture a piezoresistive sensor with high elasticity, based on homogeneous 3D hybrid network of carbon nanotubes@silver nanoparticles (CNTs@Ag NPs) anchored on a skeleton sponge. Highly elastic, sensitive, and wearable sensors are obtained using the porous structure of sponge and the synergy effect of CNTs/Ag NPs. Our sensor was also tested for over 2000 compression-release cycles, exhibiting excellent elasticity and cycling stability. Sensors with high performance and a simple fabrication process are promising devices for commercial production in various electronic devices, for example, sport performance monitoring and man-machine interfaces.
International Nuclear Information System (INIS)
A low-order flow/acoustics interaction method for the prediction of sound propagation and diffraction in unsteady subsonic compressible flow using adaptive 3-D hybrid grids is investigated. The total field is decomposed into the flow field described by the Euler equations, and the acoustics part described by the Nonlinear Perturbation Equations. The method is shown capable of predicting monopole sound propagation, while employment of acoustics-guided adapted grid refinement improves the accuracy of capturing the acoustic field. Interaction of sound with solid boundaries is also examined in terms of reflection, and diffraction. Sound propagation through an unsteady flow field is examined using static and dynamic flow/acoustics coupling demonstrating the importance of the latter.
Energy Technology Data Exchange (ETDEWEB)
Kallinderis, Yannis, E-mail: kallind@otenet.gr [Dept. of Mechanical and Aeronautical Engineering, University of Patras, Rio Patras 26504 (Greece); Vitsas, Panagiotis A.; Menounou, Penelope [Dept. of Mechanical and Aeronautical Engineering, University of Patras, Rio Patras 26504 (Greece)
2012-07-15
A low-order flow/acoustics interaction method for the prediction of sound propagation and diffraction in unsteady subsonic compressible flow using adaptive 3-D hybrid grids is investigated. The total field is decomposed into the flow field described by the Euler equations, and the acoustics part described by the Nonlinear Perturbation Equations. The method is shown capable of predicting monopole sound propagation, while employment of acoustics-guided adapted grid refinement improves the accuracy of capturing the acoustic field. Interaction of sound with solid boundaries is also examined in terms of reflection, and diffraction. Sound propagation through an unsteady flow field is examined using static and dynamic flow/acoustics coupling demonstrating the importance of the latter.
From micro-scale 3D simulations to macro-scale model of periodic porous media
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
Near field 3D displacement of El Mayor-Cupapah Earthquake: A hybrid approach. (Invited)
Hinojosa-Corona, A.; Limon, F. J.; Nissen, E.; Glennie, C. L.; Krishnan, A.; Oskin, M. E.; Arrowsmith, R.; Leprince, S.; Saripalli, S.; Arregui, S. M.; Borsa, A. A.; Kreylos, O.; Banesh, D.; Fletcher, J. M.
2013-12-01
The surface rupture produced on April 4th of 2010 by the M 7.2 El Mayor-Cucapah Earthquake is an ideal target to be analyzed by remote sensing techniques. It produced over 100 km of scarps, with vertical and horizontal slip on the order of 2 to 3 m in scarcely vegetated, rugged terrain underlain by mostly igneous rocks. A 3D displacement field (DF) was calculated by matching pre- to post-event airborne LiDAR point clouds through the Iterative Closest Point (ICP) algorithm, which first segments the point clouds into discrete windows, and for each, iteratively converges on a rigid body transformation comprising a translation and a rotation that best aligns the pre- to post-event point clouds. After testing different window sizes, we used a square window 100m a side. The El Mayor-Cucapah LiDAR data sets present special challenges for the ICP technique. The point clouds differ considerably in point density, by ~1:700. This, and the lower precision of the pre-earthquake data, limit the accuracy of the DF results. Despite these issues, the vertical and East-West (E-W) components of the DF from ICP very clearly delineate the trace of the surface rupture, showing east-side down dextral-normal motion in agreement with field measurements and the focal mechanism reported for this event. A systematic error in the LiDAR instrument used for the pre-event survey caused severe distortion of the North-South (N-S) component of the LiDAR returns. After reprocessing the source pre-event point cloud in various ways to correct for the systematic error, a more plausible pattern for the N-S component was obtained for the DF. To have another perspective for the horizontal DF, a subpixel correlation analysis of optical satellite images (SPOT 2.5 m panchromatic images) before and after the earthquake, was performed using the COSI-Corr software. We combined the N-S component from this analysis with the E-W and vertical components of the ICP results, and present the analysis of the resulting
Zaka, A.; Singer, J.; Dornel, E.; Garetto, D.; Rideau, D.; Rafhay, Q.; Clerc, R.; Manceau, J.-P.; Degors, N.; Boccaccio, C.; Tavernier, C.; Jaouen, H.
2011-09-01
The impact of 3D device architecture in aggressively scaled embedded non-volatile memories has been investigated by means of experiments and 3D TCAD simulations. A complete 3D calibration methodology covering DC and transient operating regimes has been introduced and validated against measurements for different technological options. This approach has been employed to determine the key features for device optimization. In particular, shallow trench isolation corners around the active area have been identified as critical regions of the memory cell for program and erase operations, as well as for gate coupling ratio optimization.
Institute of Scientific and Technical Information of China (English)
Aijun Zhu; Chuanpei Xu; Zhi Li; Jun Wu; Zhenbing Liu
2015-01-01
A new meta-heuristic method is proposed to enhance current meta-heuristic methods for global optimization and test scheduling for three-dimensional (3D) stacked system-on-chip (SoC) by hybridizing grey wolf optimization with differential evo-lution (HGWO). Because basic grey wolf optimization (GWO) is easy to fal into stagnation when it carries out the operation of at-tacking prey, and differential evolution (DE) is integrated into GWO to update the previous best position of grey wolf Alpha, Beta and Delta, in order to force GWO to jump out of the stagnation with DE’s strong searching ability. The proposed algorithm can accele-rate the convergence speed of GWO and improve its performance. Twenty-three wel-known benchmark functions and an NP hard problem of test scheduling for 3D SoC are employed to verify the performance of the proposed algorithm. Experimental results show the superior performance of the proposed algorithm for exploiting the optimum and it has advantages in terms of exploration.
Understanding the core-halo relation of quantum wave dark matter from 3D simulations.
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.
Characterization of double modified internal gate pixel by 3D simulation study
Aurola, A.; Marochkin, V.; Tuuva, T.
2015-01-01
We have developed a novel detector concept based on Modified Internal Gate Field Effect Transistor (MIGFET) wherein a buried Modified Internal Gate (MIG) is implanted underneath a channel of a FET. In between the MIG and the channel of the FET there is a depleted semiconductor material forming a potential barrier between charges in the channel and similar type signal charges located in the MIG. The signal charges in the MIG have a measurable effect on the conductance of the channel. In this paper a double MIGFET pixel is investigated comprising two MIGFETs. By transferring the signal charges between the two MIGs Non-Destructive Correlated Double Sampling Readout (NDCDSR) is enabled. The proposed MIG radiation detector suits particularly well for low-light-level imaging, X-ray spectroscopy, as well as synchrotron and X-ray Free Electron Laser (XFEL) facilities. The reason for the excellent X-ray detection performance stems from the fact that interface related issues can be considerably mitigated since interface generated dark noise can be completely avoided and interface generated 1/f and Random Telegraph Signal (RTS) noise can be considerably reduced due to a deep buried channel readout configuration. Electrical parameters of the double MIGFET pixel have been evaluated by 3D TCAD simulation study. Simulation results show the absence of interface generated dark noise, significantly reduced interface generated 1/f and RTS noise, well performing NDCDSR operation, and blooming protection due to an inherent vertical anti-blooming structure. In addition, the backside illuminated thick fully depleted pixel design provides a homogeneous radiation entry window, low crosstalk due to lack of diffusion, and good quantum efficiency for low energy X-rays and NIR light. These facts result in excellent Signal-to-Noise Ratio (SNR) and very low crosstalk enabling thus excellent X-ray energy and spatial resolution. The simulation demonstrates the charge to current conversion gain for
Collon-Drouaillet, Pauline; Henrion, Vincent; Pellerin, Jeanne
2012-01-01
International audience This paper presents a method to stochastically simulate 3D karstic networks and more specifically branchwork pattern cave systems. Considering that they can be compared with 3D fluvial networks, the topological classification of Strahler and the corresponding ratios of Horton are used to define three morphometric parameters. These parameters are integrated in an algorithm that computes branches hierarchically to obtain a final network organized around the main observ...
Westerveld, W J; Yousefi, M
2015-01-01
We present an accurate and fast 3D simulation scheme for out-of-plane grating couplers, based on two dimensional rigorous (finite difference time domain) grating simulations, the effective index method (EIM), and the Rayleigh-Sommerfeld diffraction formula. In comparison with full 3D FDTD simulations, the rms difference in electric field is below 5% and the difference in power flux is below 3%. A grating coupler for coupling from a silicon-on-insulator photonic integrated circuit to an optical fiber positioned 0.1 mm above the circuit is designed as example.
Software Development: 3D Animations and Creating User Interfaces for Realistic Simulations
Gordillo, Orlando Enrique
2015-01-01
My fall 2015 semester was spent at the Lyndon B. Johnson Space Center working in the Integrated Graphics, Operations, and Analysis Laboratory (IGOAL). My first project was to create a video animation that could tell the story of OMICS. OMICS is a term being used in the field of biomedical science to describe the collective technologies that study biological systems, such as what makes up a cell and how it functions with other systems. In the IGOAL I used a large 23 inch Wacom monitor to draw storyboards, graphics, and line art animations. I used Blender as the 3D environment to sculpt, shape, cut or modify the several scenes and models for the video. A challenge creating this video was to take a term used in biomedical science and describe it in such a way that an 8th grade student can understand. I used a line art style because it would visually set the tone for what we thought was an educational style. In order to get a handle on the perspective and overall feel for the animation without overloading my workspace, I split up the 2 minute animation into several scenes. I used Blender's python scripting capabilities which allowed for the addition of plugins to add or modify tools. The scripts can also directly interact with the objects to create naturalistic patterns or movements. After collecting the rendered scenes, I used Blender's built-in video editing workspace to output the animation. My second project was to write software that emulates a physical system's interface. The interface was to simulate a boat, ROV, and winch system. Simulations are a time and cost effective way to test complicated data and provide training for operators without having to use expensive hardware. We created the virtual controls with 3-D Blender models and 2-D graphics, and then add functionality in C# using the Unity game engine. The Unity engine provides several essential behaviors of a simulator, such as the start and update functions. A framework for Unity, which was developed in
Mandumpala Devassy, B.; Edelbauer, W.; Greif, D.
2015-12-01
Cavitation and its effect on spray formation and its dispersion play a crucial role in proper engine combustion and controlled emission. This study focuses on these effects in a typical common rail 6-hole diesel injector accounting for 3D needle movement and flow compressibility effects. Coupled numerical simulations using 1D and 3D CFD codes are used for this investigation. Previous studies in this direction have already presented a detailed structure of the adopted methodology. Compared to the previous analysis, the present study investigates the effect of 3D needle movement and cavitation on the spray formation for pilot and main injection events for a typical diesel engine operating point. The present setup performs a 3D compressible multiphase simulation coupled with a standalone 1D high pressure flow simulation. The simulation proceeds by the mutual communication between 1D and 3D solvers. In this work a typical common rail injector with a mini-sac nozzle is studied. The lateral and radial movement of the needle and its effect on the cavitation generation and the subsequent spray penetration are analyzed. The result indicates the effect of compressibility of the liquid on damping the needle forces, and also the difference in the spray penetration levels due to the asymmetrical flow field. Therefore, this work intends to provide an efficient and user-friendly engineering tool for simulating a complete fuel injector including spray propagation.
In vitro bioactivity of 3D Ti-mesh with bioceramic coatings in simulated body fluid
Directory of Open Access Journals (Sweden)
Wei Yi
2014-09-01
Full Text Available 3D Ti-mesh has been coated with bioceramics under different coating conditions, such as material compositions and micro-porosity, using a dip casting method. Hydroxyapatite (HA, micro-HA particles (HAp, a bioglass (BG and their different mixtures together with polymer additives were used to control HA-coating microstructures. Layered composites with the following coating-to-substrate designs, such as BG/Ti, HA + BG/BG/Ti and HAp + BG/BG/Ti, were fabricated. The bioactivity of these coated composites and the uncoated Ti-mesh substrate was then investigated in a simulated body fluid (SBF. The Ti-mesh substrate and BG/Ti composite did not induce biomimetic apatite deposition when they were immersed in SBF for the selected BG, a pressable dental ceramic, used in this study. After seven days in SBF, an apatite layer was formed on both HA + BG/BG/Ti and HAp + BG/BG/Ti composites. The difference is the apatite layer on the HAp + BG/BG/Ti composite was rougher and contained more micro-pores, while the apatite layer on the HA + BG/BG/Ti composite was dense and smooth. The formation of biomimetic apatite, being more bioresorbable, is favored for bone regeneration.
Ito, Takashi; Pilat, Marcin L; Suzuki, Reiji; Arita, Takaya
2016-01-01
Recent studies have reported that population dynamics and evolutionary dynamics, occurring at different time scales, can be affected by each other. Our purpose is to explore the interaction between population and evolutionary dynamics using an artificial life approach based on a 3D physically simulated environment in the context of predator-prey and morphology-behavior coevolution. The morphologies and behaviors of virtual prey creatures are evolved using a genetic algorithm based on the predation interactions between predators and prey. Both population sizes are also changed, depending on the fitness. We observe two types of cyclic behaviors, corresponding to short-term and long-term dynamics. The former can be interpreted as a simple population dynamics of Lotka-Volterra type. It is shown that the latter cycle is based on the interaction between the changes in the prey strategy against predators and the long-term change in both population sizes, resulting partly from a tradeoff between their defensive success and the cost of defense. PMID:26934093
Melioli, C; Raga, A
2005-01-01
Most galaxies present supernova shock fronts interacting with a cloudy interstellar medium. Particularly, in this work we are interested to study the by-products of SNR-clouds in a starburst (SB) system. Due to the high SN rate in this environment, a cloud may be shocked more than once by SNRs. These interactions can have an important role in the recycling of matter from the clouds to the ISM and vice-versa. Their study is also relevant to understand the evolution of the ISM density and the structure of the clouds embedded in it. In the present work, we have focused our attention on the global effects of the interactions between clouds and SN shock waves in the ISM of SB environments, and performed 3-D radiative cooling hydrodynamical simulations with the adaptive YGUAZU grid code. We have also considered the effects of the photo-evaporation due to the presence of a high number of UV photons from hot stars and supernovae (SNe). The results have shown that, in the presence of radiative cooling, instead of an e...
STATICS ANALYSIS AND OPENGL BASED 3D SIMULATION OF COLLABORATIVE RECONFIGURABLE PLANETARY ROBOTS
Institute of Scientific and Technical Information of China (English)
Zhang Zheng; Ma Shugen; Li Bin; Zhang Liping; Cao Binggang
2006-01-01
Objective To study mechanics characteristics of two cooperative reconfigurable planetary robots when they get across an obstacle, and to find out the relationship between the maximum height of a stair with the configuration of the two-robot, and to find some restrictions of kinematics for the cooperation. Methods Multirobot cooperation theory is used in the whole study process. Inverse kinematics of the robot is used to form a desired configuration in the cooperation process. Static equations are established to analyze the relations between the friction factor, the configuration of robots and the maximum height of a stair. Kinematics analysis is used to find the restrictions of the two collaborative robots in position, velocity and acceleration. Results 3D simulation shows that the two cooperative robots can climb up a stair under the condition of a certain height and a certain friction factor between robot wheel and the surface of the stair. Following the restrictions of kinematics, the climbing mission is fulfilled successfully and smoothly. Conclusion The maximum height of a stair, which the two cooperative robots can climb up, is involved in the configuration of robots, friction factor between the stair and the robots. The most strict restriction of the friction factor does not appear in the horizontal position. In any case, the maximum height is smaller than half of the distance between the centroid of robot1 with the centroid of robot2. However, the height can be higher than the radius of one robot wheel, which profit from the collaboration.
3D finite element simulation of TIG weld pool with free surface
International Nuclear Information System (INIS)
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 macrography of the molten pool. (authors)
Multi-ion, multi-fluid 3-D magnetohydrodynamic simulation of the outer heliosphere
Prested, Christina; Toth, Gabor
2012-01-01
Data from the Voyager probes and the Interstellar Boundary Explorer have revealed the importance of pick-up ions (PUIs) in understanding the character and behavior of the outer heliosphere, the region of interaction between the solar wind and the interstellar medium. In the outer heliosphere PUIs carry a large fraction of the thermal pressure, which effects the nature of the termination shock, and they are a dominate component of pressure in the heliosheath. This paper describes the development of a new multi-ion, multi-fluid 3-D magnetohydrodynamic model of the outer heliosphere. This model has the added capability of tracking the individual fluid properties of multiple ion populations. For this initial study two ion populations are modeled: the thermal solar wind ions and PUIs produced in the supersonic solar wind. The model also includes 4 neutral fluids that interact through charge-exchange with the ion fluids. The new multi-ion simulation reproduces the significant heating of PUIs at the termination shoc...
Modeling and simulation of 3D thermal stresses of large-sized castings in solidification processes
Institute of Scientific and Technical Information of China (English)
无
2004-01-01
When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large- sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings.Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.
3-D Simulation of a prototype pump-turbine during starting period in turbine model
International Nuclear Information System (INIS)
Three dimensional (3-D), unsteady flows in a prototype pump-turbine during a transient process of start-up at no load condition were studied using the computational fluid dynamics method. The fluid coupling and DM method were used to calculate the rotational speed for each time step. The dynamic mesh (DM) method and remeshing method were applied to simulate the rotation of guide vanes. Calculations were performed based on the v-bar 2−f turbulence model, and the calculation results were compared and verified by experimental data. Transient explicit characteristics such as the flow-rate, head, torque of the runner etc., as well as the internal flow during the start-up were analyzed. The amplitude of pressure fluctuation was larger as the rotational speed of runner increased. The pump-turbine was more unstable with the decrease of the moment of inertia. The impact jet flow in the runner has a direct relationship with the increase of the torque of runner. No stall phenomenon in the runner when the pump-turbine runs close to no load opening condition. This calculation was based on a prototype of a pumped storage power station and the computational method could be used in the fault diagnosis of transient operation
Turbulence and Steady Flows in 3D Global Stratified MHD Simulations of Accretion Disks
Flock, M; Klahr, H; Turner, N J; Henning, Th
2011-01-01
We present full 2 Pi global 3-D stratified MHD simulations of accretion disks. We interpret our results in the context of proto-planetary disks. We investigate the turbulence driven by the magneto-rotational instability (MRI) using the PLUTO Godunov code in spherical coordinates with the accurate and robust HLLD Riemann solver. We follow the turbulence for more than 1500 orbits at the innermost radius of the domain to measure the overall strength of turbulent motions and the detailed accretion flow pattern. We find that regions within two scale heights of the midplane have a turbulent Mach number of about 0.1 and a magnetic pressure two to three orders of magnitude less than the gas pressure, while outside three scale heights the magnetic pressure equals or exceeds the gas pressure and the turbulence is transonic, leading to large density fluctuations. The strongest large-scale density disturbances are spiral density waves, and the strongest of these waves has m=5. No clear meridional circulation appears in t...
3D MHD Simulations of Planet Migration in Turbulent Stratified Disks
Uribe, Ana; Flock, Mario; Henning, Thomas
2011-01-01
We performed 3D MHD simulations of planet migration in stratified disks using the Godunov code PLUTO, where the disk is turbulent due to the magnetorotational instability. We study the migration for planets with different planet-star mass ratios $q=M_{p}/M_{s}$. In agreement with previous studies, for the low-mass planet cases ($q=5\\times10^{-6}$ and $10^{-5}$), migration is dominated by random fluctuations in the torque. For a Jupiter-mass planet $(q=M_{p}/M_{s}=10^{-3}$ for $M_{s}=1M_{\\odot})$, we find a reduction of the magnetic stress inside the orbit of the planet and around the gap region. After an initial stage where the torque on the planet is positive, it reverses and we recover migration rates similar to those found in disks where the turbulent viscosity is modelled by an $\\alpha$ viscosity. For the intermediate-mass planets ($q=5\\times10^{-5}, 10^{-4}$ and $2\\times10^{-4}$) we find a new and so far unexpected behavior. In some cases they experience sustained and systematic outwards migration for th...
Method of internal 3D flow field numerical simulation for hydrodynamic torque converter
Institute of Scientific and Technical Information of China (English)
Tao SHANG; Dingxuan ZHAO; Yuankun ZHANG; Xiangen GUO; Xiangzhong SHI
2008-01-01
To enhance the performance of a hydrody-namic torque converter and thoroughly understand the trait of inside flow, a numerical simulation method of internal 3D flow for the three-element centrifugal hydrodynamic torque converter was systematically researched and expatiated in this paper. First, the internal flow field of each impeller was calculated. The curves that illustrate the relationships between the pressure differences of the inlet and outlet versus flux were drawn. Second, the concurrent working point of each impeller was approximately estimated. Finally, a calculation was performed considering the influence on each impeller. The flow field of a working point was solved by multiple calculations and the actual working condition was gradually determined. The pressure and velocity distributions of the flow field were proposed. The performance parameters of the hydrodynamic torque converter were predicted. The calculation method, and the proposed pressure and velocity distribution of the flow field, have practical significance for the design and improvement of a hydrodynamic torque converter.
Trapping Solids at the Inner Edge of the Dead Zone: 3-D Global MHD Simulations
Dzyurkevich, Natalia; Turner, Neal J; Klahr, Hubert; Henning, Thomas
2010-01-01
The poorly-ionized interior of the protoplanetary disk 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. Our aim 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 MHD calculations of the disk treating the turbulence driven by the magneto-rotational instability. 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. 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...
Numerical simulation on the evolution of cloud particles in 3-D convective cloud
Institute of Scientific and Technical Information of China (English)
LIU XiaoLi; NIU ShengJie
2009-01-01
A 3-D convective cloud model with compressible non-hydrostatic dynamics and the spectral bin microphysics of a 2-D slab-symmetric model has been used to simulate an observed supercell storm occurring on 29 June, 2000 near Bird City, Kansas, USA. The main objective of this paper is to study the evolution of particles in this convective storm with bin spectral microphysics scheme. Graupels form and grow through two mechanisms, deposition and riming, with the riming process dominant on top of the inflow and in the upper portion of main updraft. Over the outflow and during the developing and mature stages of the storm, graupel particles mainly grow through deposition with dominant unimodal spectra. Most fall out after growing up. Reducing initial relative humidity disturbance (increasing initial potential temperature disturbance) has negative impact on the formation and growth of graupels over the inflow (outflow). This study shows that large graupel and hail could be suppressed by altering the deposition and coalescence process over the inflow and main updraft. At different locations of the convective cells and with different initial humidity and potential temperature disturbance, the graupel formation and growth mechanisms are different, so as to the feasible hail suppression locations and methods.
3D finite element simulation of effects of deflection rate on energy absorption for TRIP steel
Directory of Open Access Journals (Sweden)
Hayashi Asuka
2015-01-01
Full Text Available Recently, with the requirement of lighter weight and more safety for a design of automobile, energy absorption capability of structural materials has become important. TRIP (Transformation-induced Plasticity steel is expected to apply to safety members because of excellent energy absorption capability and ductility. Past studies proved that such excellent characteristics in TRIP steel are dominated by strain-induced martensitic transformation (SIMT during plastic deformation. Because SIMT strongly depends on deformation rate and temperature, an investigation of the effects of deformation rate and temperature on energy absorption in TRIP is essential. Although energy absorption capability of material can be estimated by J-integral experimentally by using pre-cracked specimen, it is difficult to determine volume fraction of martensite and temperature rise during the crack extension. In addition, their effects on J-integral, especially at high deformation rate in experiment might be quite hard. Thus, a computational prediction needs to be performed. In this study, bending deformation behavior of pre-cracked specimen until the onset point of crack extension are predicted by 3D finite element simulation based on the transformation kinetics model proposed by Iwamoto et al. (1998. It is challenged to take effects of temperature, volume fraction of martensite and deformation rate into account. Then, the mechanism for higher energy absorption characteristic will be discussed.
Surface-effect corrections for solar-like oscillations using 3D hydrodynamical simulations
Sonoi, T; Belkacem, K; Ludwig, H -G; Caffau, E; Mosser, B
2015-01-01
The space-borne missions have provided us with a wealth of high-quality observational data that allows for seismic inferences of stellar interiors. This requires the computation of precise and accurate theoretical frequencies, but imperfect modeling of the uppermost stellar layers introduces systematic errors. To overcome this problem, an empirical correction has been introduced by Kjeldsen et al. (2008, ApJ, 683, L175) and is now commonly used for seismic inferences. Nevertheless, we still lack a physical justification allowing for the quantification of the surface-effect corrections. We used a grid of these simulations computed with the CO$^5$BOLD code to model the outer layers of solar-like stars. Upper layers of the corresponding 1D standard models were then replaced by the layers obtained from the horizontally averaged 3D models. The frequency differences between these patched models and the 1D standard models were then calculated using the adiabatic approximation and allowed us to constrain the Kjeldsen...
3D numerical simulation of gaseous flows structure in semidetached binaries
Bisikalo, D V; Chechetkin, V M; Kuznetsov, O A; Molteni, D
1998-01-01
The results of 3D hydrodynamic simulation of mass transfer in semidetached binaries of different types (cataclysmic variables and low-mass X-ray binaries) are presented. We find that taking into account of a circumbinary envelope leads to significant changes in the stream-disc morphology. In particular, the obtained steady-state self-consistent solutions show an absence of impact between gas stream from the inner Lagrangian point L1 and forming accretion disc. The stream deviates under the action of gas of circumbinary envelope, and does not cause the shock perturbation of the disc boundary (traditional `hotspot'). At the same time, the gas of circumbinary envelope interacts with the stream and causes the formation of an extended shock wave, located on the stream edge. We discuss the implication of this model without `hotspot' (but with a shock wave located outside the disc) for interpretation of observations. The comparison of synthetic light curves with observations proves the validity of the discussed hydr...
Towards Hybrid Overset Grid Simulations of the Launch Environment
Moini-Yekta, Shayan
A hybrid overset grid approach has been developed for the design and analysis of launch vehicles and facilities in the launch environment. The motivation for the hybrid grid methodology is to reduce the turn-around time of computational fluid dynamic simulations and improve the ability to handle complex geometry and flow physics. The LAVA (Launch Ascent and Vehicle Aerodynamics) hybrid overset grid scheme consists of two components: an off-body immersed-boundary Cartesian solver with block-structured adaptive mesh refinement and a near-body unstructured body-fitted solver. Two-way coupling is achieved through overset connectivity between the off-body and near-body grids. This work highlights verification using code-to-code comparisons and validation using experimental data for the individual and hybrid solver. The hybrid overset grid methodology is applied to representative unsteady 2D trench and 3D generic rocket test cases.
3D Particle Track Reconstrution in a Single Layer Cadmium-Telluride Hybrid Active Pixel Detector
Filipenko, Mykhaylo; Anton, Gisela; Michel, Thilo
2014-01-01
In the past 20 years the search for neutrinoless double beta decay has driven many developements in all kind of detector technology. A new branch in this field are highly-pixelated semiconductor detectors - such as the CdTe-Timepix detectors. It compromises a cadmium-telluride sensor of 14 mm x 14 mm x 1 mm size with an ASIC which has 256 x 256 pixel of 55 \\textmu m pixel pitch and can be used to obtain either spectroscopic or timing information in every pixel. In regular operation it can provide a 2D projection of particle trajectories; however, three dimensional trajectories are desirable for neutrinoless double beta decay and other applications. In this paper we present a method to obtain such trajectories. The method was developed and tested with simulations that assume some minor modifications to the Timepix ASIC. Also, we were able to test the method experimentally and in the best case achieved a position resolution of about 90 \\textmu m with electrons of 4.4 GeV.
Ziegle, Jens; Müller, Bernhard H.; Neumann, Bernd; Hoeschen, Christoph
2016-03-01
A new 3D breast computed tomography (CT) system is under development enabling imaging of microcalcifications in a fully uncompressed breast including posterior chest wall tissue. The system setup uses a steered electron beam impinging on small tungsten targets surrounding the breast to emit X-rays. A realization of the corresponding detector concept is presented in this work and it is modeled through Monte Carlo simulations in order to quantify first characteristics of transmission and secondary photons. The modeled system comprises a vertical alignment of linear detectors hold by a case that also hosts the breast. Detectors are separated by gaps to allow the passage of X-rays towards the breast volume. The detectors located directly on the opposite side of the gaps detect incident X-rays. Mechanically moving parts in an imaging system increase the duration of image acquisition and thus can cause motion artifacts. So, a major advantage of the presented system design is the combination of the fixed detectors and the fast steering electron beam which enable a greatly reduced scan time. Thereby potential motion artifacts are reduced so that the visualization of small structures such as microcalcifications is improved. The result of the simulation of a single projection shows high attenuation by parts of the detector electronics causing low count levels at the opposing detectors which would require a flat field correction, but it also shows a secondary to transmission ratio of all counted X-rays of less than 1 percent. Additionally, a single slice with details of various sizes was reconstructed using filtered backprojection. The smallest detail which was still visible in the reconstructed image has a size of 0.2mm.
Directory of Open Access Journals (Sweden)
L. Zhang
2015-01-01
Full Text Available In solar wind, dissipation of slow-mode magnetosonic waves may play a significant role in heating the solar wind, and these modes contribute essentially to the solar wind compressible turbulence. Most previous identifications of slow waves utilized the characteristic negative correlation between δ|B| and δρ. However, that criterion does not well identify quasi-parallel slow waves, for which δ|B| is negligible compared to δρ. Here we present a new method of identification, which will be used in 3-D compressible simulation. It is based on two criteria: (1 that VpB0 (phase speed projected along B0 is around ± cs, and that (2 there exists a clear correlation of δv|| and δρ. Our research demonstrates that if vA > cs, slow waves possess correlation between δv|| and δρ, with δρ / δv|| ≈ ± ρ0 / cs. This method helps us to distinguish slow-mode waves from fast and Alfvén waves, both of which do not have this polarity relation. The criteria are insensitive to the propagation angle θk B, defined as the angle between wave vector k and B0; they can be applied with a wide range of β if only vA > cs. In our numerical simulation, we have identified four cases of slow wave trains with this method. The slow wave trains seem to deform, probably caused by interaction with other waves; as a result, fast or Alfvén waves may be produced during the interaction and seem to propagate bidirectionally away. Our identification and analysis of the wave trains provide useful methods for investigations of compressible turbulence in the solar wind or in similar environments, and will thus deepen understandings of slow waves in the turbulence.
Jinya, John; Bipasha, Paul S.
2016-05-01
Clouds strongly modulate the Earths energy balance and its atmosphere through their interaction with the solar and terrestrial radiation. They interact with radiation in various ways like scattering, emission and absorption. By observing these changes in radiation at different wavelength, cloud properties can be estimated. Cloud properties are of utmost importance in studying different weather and climate phenomena. At present, no satellite provides cloud microphysical parameters over the Indian region with high temporal resolution. INSAT-3D imager observations in 6 spectral channels from geostationary platform offer opportunity to study continuous cloud properties over Indian region. Visible (0.65 μm) and shortwave-infrared (1.67 μm) channel radiances can be used to retrieve cloud microphysical parameters such as cloud optical thickness (COT) and cloud effective radius (CER). In this paper, we have carried out a feasibility study with the objective of cloud microphysics retrieval. For this, an inter-comparison of 15 globally available radiative transfer models (RTM) were carried out with the aim of generating a Look-up- Table (LUT). SBDART model was chosen for the simulations. The sensitivity of each spectral channel to different cloud properties was investigated. The inputs to the RT model were configured over our study region (50°S - 50°N and 20°E - 130°E) and a large number of simulations were carried out using random input vectors to generate the LUT. The determination of cloud optical thickness and cloud effective radius from spectral reflectance measurements constitutes the inverse problem and is typically solved by comparing the measured reflectances with entries in LUT and searching for the combination of COT and CER that gives the best fit. The products are available on the website www.mosdac.gov.in
Albedo and heat transport in 3-D model simulations of the early Archean climate
Directory of Open Access Journals (Sweden)
H. Kienert
2013-08-01
Full Text Available At the beginning of the Archean eon (ca. 3.8 billion years ago, the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun paradox" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-D model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. In order to do so, we have appropriately modified an intermediate complexity climate model that couples a statistical-dynamical atmosphere model (involving parameterizations of the dynamics to an ocean general circulation model and a thermodynamic-dynamic sea-ice model. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth". We find a reduction in meridional heat transport compared to today, which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterization of the ice-albedo feedback for 1-D model simulations of the early Archean and thus the faint young Sun problem.
Finite-Difference Algorithm for Simulating 3D Electromagnetic Wavefields in Conductive Media
Aldridge, D. F.; Bartel, L. C.; Knox, H. A.
2013-12-01
Electromagnetic (EM) wavefields are routinely used in geophysical exploration for detection and characterization of subsurface geological formations of economic interest. Recorded EM signals depend strongly on the current conductivity of geologic media. Hence, they are particularly useful for inferring fluid content of saturated porous bodies. In order to enhance understanding of field-recorded data, we are developing a numerical algorithm for simulating three-dimensional (3D) EM wave propagation and diffusion in heterogeneous conductive materials. Maxwell's equations are combined with isotropic constitutive relations to obtain a set of six, coupled, first-order partial differential equations governing the electric and magnetic vectors. An advantage of this system is that it does not contain spatial derivatives of the three medium parameters electric permittivity, magnetic permeability, and current conductivity. Numerical solution methodology consists of explicit, time-domain finite-differencing on a 3D staggered rectangular grid. Temporal and spatial FD operators have order 2 and N, where N is user-selectable. We use an artificially-large electric permittivity to maximize the FD timestep, and thus reduce execution time. For the low frequencies typically used in geophysical exploration, accuracy is not unduly compromised. Grid boundary reflections are mitigated via convolutional perfectly matched layers (C-PMLs) imposed at the six grid flanks. A shared-memory-parallel code implementation via OpenMP directives enables rapid algorithm execution on a multi-thread computational platform. Good agreement is obtained in comparisons of numerically-generated data with reference solutions. EM wavefields are sourced via point current density and magnetic dipole vectors. Spatially-extended inductive sources (current carrying wire loops) are under development. We are particularly interested in accurate representation of high-conductivity sub-grid-scale features that are common
Directory of Open Access Journals (Sweden)
W.-L. Lee
2014-12-01
Full Text Available We investigate 3-D mountain effects on solar flux distributions and their impact on surface hydrology over the Western United States, specifically the Rocky Mountains and Sierra Nevada using CCSM4 (CAM4/CLM4 global model with a 0.23° × 0.31° resolution for simulations over 6 years. In 3-D radiative transfer parameterization, we have updated surface topography data from a resolution of 1 km to 90 m to improve parameterization accuracy. In addition, we have also modified the upward-flux deviation [3-D − PP (plane-parallel] adjustment to ensure that energy balance at the surface is conserved in global climate simulations based on 3-D radiation parameterization. We show that deviations of the net surface fluxes are not only affected by 3-D mountains, but also influenced by feedbacks of cloud and snow in association with the long-term simulations. Deviations in sensible heat and surface temperature generally follow the patterns of net surface solar flux. The monthly snow water equivalent (SWE deviations show an increase in lower elevations due to reduced snowmelt, leading to a reduction in cumulative runoff. Over higher elevation areas, negative SWE deviations are found because of increased solar radiation available at the surface. Simulated precipitation increases for lower elevations, while decreases for higher elevations with a minimum in April. Liquid runoff significantly decreases in higher elevations after April due to reduced SWE and precipitation.
Rauch, Travis M.
2006-01-01
Visualizing operations environments in three dimensions (3D) supports the warfighters' ability to make rapid, well-informed decisions by presenting complex systems in a naturalistic, integrated display format. Unfortunately, constructing these environments is a time-consuming task requiring specific expertise not typically available in the command center. The future use of 3D visualization in military operations depends on the ability of personnel with minimal graphics experience to create vi...
Yang, R.; Song, A.; Li, X. D.; Lu, Y.; Yan, R.; Xu, B.; Li, X.
2014-10-01
A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect by deconvolution is proposed for noninvasive imaging of biological tissue. Compared with ultrasound current source density imaging, ultrasound Joule heat density tomography doesn't require any priori knowledge of conductivity distribution and lead fields, so it can gain better imaging result, more adaptive to environment and with wider application scope. For a general 3D volume conductor with broadly distributed current density field, in the AE equation the ultrasound pressure can't simply be separated from the 3D integration, so it is not a common modulation and basebanding (heterodyning) method is no longer suitable to separate Joule heat density from the AE signals. In the proposed method the measurement signal is viewed as the output of Joule heat density convolving with ultrasound wave. As a result, the internal 3D Joule heat density can be reconstructed by means of Wiener deconvolution. A series of computer simulations set for breast cancer imaging applications, with consideration of ultrasound beam diameter, noise level, conductivity contrast, position dependency and size of simulated tumors, have been conducted to evaluate the feasibility and performance of the proposed reconstruction method. The computer simulation results demonstrate that high spatial resolution 3D ultrasound Joule heat density imaging is feasible using the proposed method, and it has potential applications to breast cancer detection and imaging of other organs.
Trapping solids at the inner edge of the dead zone: 3-D global MHD simulations
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.
International Nuclear Information System (INIS)
The present study compares in silico treatment plans of clinically established three-dimensional conformal radiotherapy (3D-CRT) with a hybrid technique consisting of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) during normally fractionated radiation of mammary carcinomas with simultaneous integrated boost on the basis of dose-volume histogram (DVH) parameters. Radiation treatment planning was performed with a hybrid and a 3D-CRT treatment plan for 20 patients. Hybrid plans were implemented with two tangential IMRT fields and a VMAT field in the angular range of the tangents. Verification of the plan was performed with a manufacturer-independent measurement system consisting of a detector array and rotation unit. The mean values of the heart dose for the entire patient collective were 3.6 ± 2.5 Gy for 3D-CRT and 2.9 ± 2.1 Gy for the hybrid technique (p < 0.01). For the left side (n = 10), the mean values for the left anterior descending artery were 21.8 ± 7.4 Gy for 3D-CRT and 17.6 ± 7.4 Gy for the hybrid technique (p < 0.01). The mean values of the ipsilateral lung were 11.9 ± 1.6 Gy for 3D-CRT and 10.5 ± 1.3 Gy for the hybrid technique (p < 0.01). Calculated dose distributions in the hybrid arm were in good accordance with measured dose (on average 95.6 ± 0.5 % for γ < 1 and 3 %/3 mm). The difference of the mean treatment time per fraction was 7 s in favor of 3D-CRT. Compared with the established 3D-CRT technique, the hybrid technique allows for a decrease in dose, particularly of the mean heart and lung dose with comparable target volume acquisition and without disadvantageous low-dose load of contralateral structures. Uncomplicated implementation of the hybrid technique was demonstrated in this context. The hybrid technique combines the advantages of tangential IMRT with the superior sparing of organs at risk by VMAT. (orig.)
Guan, Binbin; Scott, Ryan P; Qin, Chuan; Fontaine, Nicolas K; Su, Tiehui; Ferrari, Carlo; Cappuzzo, Mark; Klemens, Fred; Keller, Bob; Earnshaw, Mark; Yoo, S J B
2014-01-13
We demonstrate free-space space-division-multiplexing (SDM) with 15 orbital angular momentum (OAM) states using a three-dimensional (3D) photonic integrated circuit (PIC). The hybrid device consists of a silica planar lightwave circuit (PLC) coupled to a 3D waveguide circuit to multiplex/demultiplex OAM states. The low excess loss hybrid device is used in individual and two simultaneous OAM states multiplexing and demultiplexing link experiments with a 20 Gb/s, 1.67 b/s/Hz quadrature phase shift keyed (QPSK) signal, which shows error-free performance for 379,960 tested bits for all OAM states.
Institute of Scientific and Technical Information of China (English)
XIE Hongqin; WU Zengmao; GAO Shanhong
2004-01-01
A series of test simulations are performed to evaluate the impact of satellite-derived meteorological data on numerical typhoon track prediction. Geostationary meteorological satellite (GMS-5) and NOAA's TIROS operational vertical sounder (TOVS) observations are used in the experiments. A three-dimensional variational (3D-Var) assimilation scheme is developed to assimilate the satellite data directly into the Penn State-NCAR nonhydrostatic meteorological model (MM5). Three-dimensional objective analysis fields based on the T213 results and conventional observations are employed as the background fields of the initialization. The comparisons of the simulated typhoon tracks are carried out, which correspond respectively to assimilate different kinds of satellite data. It is found that, compared with the experiment without satellite data assimilation, the 3D-Var assimilation schemes lead to significant improvements on typhoon track prediction. Track errors reduce from approximately 25% at 24 h to approximately 30% at 48 h for 3D-Var assimilation experiments.
Energy Technology Data Exchange (ETDEWEB)
Le Guen, E.
2010-11-15
Hybrid laser/MIG-MAG welding shows high advantages compared to laser welding or GMAW arc welding used separately. Thanks to this process, higher productivity can be gained through higher welding speed, higher squeeze tolerance moreover possible improvement of the metallurgical properties of the weld seam can be obtained. However, many operating parameters have to be set up in order to achieve optimal process. The complex physical phenomena, which govern welding process, have to be understood in order to use efficiently this technique in mass production. Understanding of these phenomena is also necessary to program numerical simulations which fit to this process. In the first step, experimental studies have been carried out with GMAW, laser and hybrid welding on samples of S355 steel. Influence of operating parameters has been analyzed through films performed with speed camera and macro-graphies of weld seam cross section. Surface deformations of the melt pool, induced by the arc pressure, weld pool length, droplet detachment and welding speed, have been analyzed precisely from images of the surface melt pool. In a second step, a numerical model was developed using the COMSOL Multiphysics software for MAG, laser and hybrid laser/MAG welding processes. A 3D quasi-stationary model has been calculated from the temperature field within the metal. The originality of the MAG and hybrid model lies in the prediction of the melt pool surface profile used to determine the 3D geometry, by taking into account the material input. The influence of different parameters such as arc power and speed welding on the efficiency as well as the distribution radius of the arc power and the arc pressure are analyzed through validations with different experimental results and different calculation configurations. (author)
Messier, Erik; Wilcox, Jascha; Dawson-Elli, Alexander; Diaz, Gabriel; Linte, Cristian A
2016-01-01
To inspire young students (grades 6-12) to become medical practitioners and biomedical engineers, it is necessary to expose them to key concepts of the field in a way that is both exciting and informative. Recent advances in medical image acquisition, manipulation, processing, visualization, and display have revolutionized the approach in which the human body and internal anatomy can be seen and studied. It is now possible to collect 3D, 4D, and 5D medical images of patient specific data, and display that data to the end user using consumer level 3D stereoscopic display technology. Despite such advancements, traditional 2D modes of content presentation such as textbooks and slides are still the standard didactic equipment used to teach young students anatomy. More sophisticated methods of display can help to elucidate the complex 3D relationships between structures that are so often missed when viewing only 2D media, and can instill in students an appreciation for the interconnection between medicine and technology. Here we describe the design, implementation, and preliminary evaluation of a 3D virtual anatomy puzzle dedicated to helping users learn the anatomy of various organs and systems by manipulating 3D virtual data. The puzzle currently comprises several components of the human anatomy and can be easily extended to include additional organs and systems. The 3D virtual anatomy puzzle game was implemented and piloted using three display paradigms - a traditional 2D monitor, a 3D TV with active shutter glass, and the DK2 version Oculus Rift, as well as two different user interaction devices - a space mouse and traditional keyboard controls. PMID:27046584
Influence of voids in the hybrid layer based on self-etching adhesive systems: a 3-D FE analysis
Directory of Open Access Journals (Sweden)
Ana Paula Martini
2009-01-01
Full Text Available The presence of porosities at the dentin/adhesive interface has been observed with the use of new generation dentin bonding systems. These porosities tend to contradict the concept that etching and hybridization processes occur equally and simultaneously. Therefore, the aim of this study was to evaluate the micromechanical behavior of the hybrid layer (HL with voids based on a self-etching adhesive system using 3-D finite element (FE analysis. MATERIAL AND METHODS: Three FE models (Mr were built: Mr, dentin specimen (41x41x82 μm with a regular and perfect (i.e. pore-free HL based on a self-etching adhesive system, restored with composite resin; Mp, similar to M, but containing 25% (v/v voids in the HL; Mpp, similar to Mr, but containing 50% (v/v voids in the HL. A tensile load (0.03N was applied on top of the composite resin. The stress field was obtained by using Ansys Workbench 10.0. The nodes of the base of the specimen were constrained in the x, y and z axes. The maximum principal stress (σmax was obtained for all structures at the dentin/adhesive interface. RESULTS: The Mpp showed the highest peak of σmax in the HL (32.2 MPa, followed by Mp (30 MPa and Mr (28.4 MPa. The stress concentration in the peritubular dentin was high in all models (120 MPa. All other structures positioned far from voids showed similar increase of stress. CONCLUSION: Voids incorporated into the HL raised the σmax in this region by 13.5%. This behavior might be responsible for lower bond strengths of self-etching and single-bottle adhesives, as reported in the literature.
An Interactive 3D Graphics Modeler Based on Simulated Human Immune System
Directory of Open Access Journals (Sweden)
Hiroaki Nishino
2008-07-01
Full Text Available We propose an intuitive computer graphics authoring method based on interactive evolutionary computation (IEC. Our previous systems employed genetic algorithm (GA and mainly focused on rapid exploration of a single optimum 3D graphics model. The proposed method adopts a different computation strategy called immune algorithm (IA to ease the creation of varied 3D models even if a user doesn’t have any specific idea of final 3D products. Because artistic work like graphics design needs a process to diversify the user’s imagery, a tool that allows the user to select his/her preferred ones from a broad range of possible design solutions is particularly desired. IA enables the user to effectively explore a wealth of solutions in a huge 3D parametric space by using its essential mechanisms such as antibody formation and self-regulating function. We conducted an experiment to verify the effectiveness of the proposed method. The results show that the proposed method helps the user to easily generating wide variety of 3D graphics models.
Institute of Scientific and Technical Information of China (English)
WANG Xi-fen; ZHOU Huai-chun
2005-01-01
The control of 3-D temperature distribution in a utility boiler furnace is essential for the safe, economic and clean operation of pcfired furnace with multi-burner system. The development of the visualization of 3-D temperature distributions in pc-fired furnaces makes it possible for a new combustion control strategy directly with the fumacs temperature as its goal to improve the control quality for the combustion processes. Studied in this paper is such a new strategy that the whole furnace is divided into several parts in the vertical direction, and the average temperature and its bias from the center in every cross section can be extracted from the visualization results of the 3-D temperature distributions. In the simulation stage, a computational fluid dynamics (CFD) code served to calculate the 3-D temperature distributions in a furnace, then a linear model was set up to relate the features of the temperature distributions with the input of the combustion processes, such as the flow rates of fuel and air fed into the furnaces through all the burners. The adaptive genetic algorithm was adopted to find the optimal combination of the whole input parameters which ensure to form an optimal 3-D temperature field in the furnace desired for the operation of boiler. Simulation results showed that the strategy could soon find the factors making the temperature distribution apart from the optimal state and give correct adjusting suggestions.
Simulated and Real Sheet-of-Light 3D Object Scanning Using a-Si:H Thin Film PSD Arrays
Directory of Open Access Journals (Sweden)
Javier Contreras
2015-11-01
Full Text Available A MATLAB/SIMULINK software simulation model (structure and component blocks has been constructed in order to view and analyze the potential of the PSD (Position Sensitive Detector array concept technology before it is further expanded or developed. This simulation allows changing most of its parameters, such as the number of elements in the PSD array, the direction of vision, the viewing/scanning angle, the object rotation, translation, sample/scan/simulation time, etc. In addition, results show for the first time the possibility of scanning an object in 3D when using an a-Si:H thin film 128 PSD array sensor and hardware/software system. Moreover, this sensor technology is able to perform these scans and render 3D objects at high speeds and high resolutions when using a sheet-of-light laser within a triangulation platform. As shown by the simulation, a substantial enhancement in 3D object profile image quality and realism can be achieved by increasing the number of elements of the PSD array sensor as well as by achieving an optimal position response from the sensor since clearly the definition of the 3D object profile depends on the correct and accurate position response of each detector as well as on the size of the PSD array.
Simulation of Natural Scene Based on 3-D IFS Theory%基于3-D IFS理论的自然景观模拟
Institute of Scientific and Technical Information of China (English)
王兴元; 刘波
2003-01-01
This article elaborates the theory of Iterated Function System (IFS)and gives the stochastic algorithm and the deterministic algorithm with which to construct IFS attractor. Based on the technique of coloring, lighting, shadow and mist in computer graphics, the authors construct a series of 3 dimension IFS (3-D IFS)characterized with the feature of natural scene on computer. The changing rules of the 3-D IFS are also discussed when the parameters mentioned above are changed.
Energy Technology Data Exchange (ETDEWEB)
Joest, Vincent; Kretschmer, Matthias; Sabatino, Marcello; Wuerschmidt, Florian; Dahle, Joerg; Lorenzen, Joern [Radiological Alliance, Hamburg (Germany); Ueberle, Friedrich [University of Applied Sciences, Faculty Life Sciences, Hamburg (Germany)
2015-09-15
The present study compares in silico treatment plans of clinically established three-dimensional conformal radiotherapy (3D-CRT) with a hybrid technique consisting of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) during normally fractionated radiation of mammary carcinomas with simultaneous integrated boost on the basis of dose-volume histogram (DVH) parameters. Radiation treatment planning was performed with a hybrid and a 3D-CRT treatment plan for 20 patients. Hybrid plans were implemented with two tangential IMRT fields and a VMAT field in the angular range of the tangents. Verification of the plan was performed with a manufacturer-independent measurement system consisting of a detector array and rotation unit. The mean values of the heart dose for the entire patient collective were 3.6 ± 2.5 Gy for 3D-CRT and 2.9 ± 2.1 Gy for the hybrid technique (p < 0.01). For the left side (n = 10), the mean values for the left anterior descending artery were 21.8 ± 7.4 Gy for 3D-CRT and 17.6 ± 7.4 Gy for the hybrid technique (p < 0.01). The mean values of the ipsilateral lung were 11.9 ± 1.6 Gy for 3D-CRT and 10.5 ± 1.3 Gy for the hybrid technique (p < 0.01). Calculated dose distributions in the hybrid arm were in good accordance with measured dose (on average 95.6 ± 0.5 % for γ < 1 and 3 %/3 mm). The difference of the mean treatment time per fraction was 7 s in favor of 3D-CRT. Compared with the established 3D-CRT technique, the hybrid technique allows for a decrease in dose, particularly of the mean heart and lung dose with comparable target volume acquisition and without disadvantageous low-dose load of contralateral structures. Uncomplicated implementation of the hybrid technique was demonstrated in this context. The hybrid technique combines the advantages of tangential IMRT with the superior sparing of organs at risk by VMAT. (orig.) [German] Die vorliegende Studie vergleicht ''in silico
3D Interdigital Au/MnO2 /Au Stacked Hybrid Electrodes for On-Chip Microsupercapacitors.
Hu, Haibo; Pei, Zhibin; Fan, Hongjin; Ye, Changhui
2016-06-01
On-chip microsupercapacitors (MSCs) have application in powering microelectronic devices. Most of previous MSCs are made from carbon materials, which have high power but low energy density. In this work, 3D interdigital Au/MnO2 /Au stacked MSCs have been fabricated based on laser printed flexible templates. This vertical-stacked electrode configuration can effectively increase the contact area between MnO2 active layer and Au conductive layer, and thus improve the electron transport and electrolyte ion diffusion, resulting in enhanced pseudocapacitive performance of MnO2 . The stacked electrode can achieve an areal capacitance up to 11.9 mF cm(-2) . Flexible and all-solid-state MSCs are assembled based on the sandwich hybrid electrodes and PVA/LiClO4 gel electrolyte and show outstanding high-rate capacity and mechanical flexibility. The laser printing technique in this work combined with the physical sputtering and electrodeposition allows fabrication of MSC array with random sizes and patterns, making them promising power sources for small-scale flexible microelectronic energy storage systems (e.g., next-generation smart phones). PMID:27116677
3D Interdigital Au/MnO2 /Au Stacked Hybrid Electrodes for On-Chip Microsupercapacitors.
Hu, Haibo; Pei, Zhibin; Fan, Hongjin; Ye, Changhui
2016-06-01
On-chip microsupercapacitors (MSCs) have application in powering microelectronic devices. Most of previous MSCs are made from carbon materials, which have high power but low energy density. In this work, 3D interdigital Au/MnO2 /Au stacked MSCs have been fabricated based on laser printed flexible templates. This vertical-stacked electrode configuration can effectively increase the contact area between MnO2 active layer and Au conductive layer, and thus improve the electron transport and electrolyte ion diffusion, resulting in enhanced pseudocapacitive performance of MnO2 . The stacked electrode can achieve an areal capacitance up to 11.9 mF cm(-2) . Flexible and all-solid-state MSCs are assembled based on the sandwich hybrid electrodes and PVA/LiClO4 gel electrolyte and show outstanding high-rate capacity and mechanical flexibility. The laser printing technique in this work combined with the physical sputtering and electrodeposition allows fabrication of MSC array with random sizes and patterns, making them promising power sources for small-scale flexible microelectronic energy storage systems (e.g., next-generation smart phones).
The Influence of Visual and Spatial Reasoning in Interpreting Simulated 3D Worlds.
Lowrie, Tom
2002-01-01
Explores ways in which 6-year-old children make sense of screen-based images on the computer. Uses both static and relatively dynamic software programs in the investigation. Suggests that young children should be exposed to activities that establish explicit links between 2D and 3D objects away from the computer before attempting difficult links…
3D FEM Simulation of shape rolling using an ALE method
Wisselink, H.H.; Huetink, J.
2003-01-01
The shape rolling of stator vanes has been modelled in 3D using the finite element method. Till now only the rolling of straight vanes, which have a constant cross section, is studied. Therefore this rolling process can be considered as a stationary process. Such processes can be described as a flow
Unidirectional high fiber content composites: Automatic 3D FE model generation and damage simulation
DEFF Research Database (Denmark)
Qing, Hai; Mishnaevsky, Leon
2009-01-01
A new method and a software code for the automatic generation of 3D micromechanical FE models of unidirectional long-fiber-reinforced composite (LFRC) with high fiber volume fraction with random fiber arrangement are presented. The fiber arrangement in the cross-section is generated through random...
Numerical simulation of behavior of gas bubbles using a 3-D front-tracking method
Sint Annaland, van M.; Dijkhuizen, W.; Deen, N.G.; Kuipers, J.A.M.
2005-01-01
In this paper a three-dimensional (3-D) front-tracking (FT) model is presented featuring a new method to evaluate the surface force model that circumvents the explicit computation of the interface curvature. This method is based on a direct calculation of the net tensile forces acting on a different
Energy Technology Data Exchange (ETDEWEB)
El-Morshedy, Salah El-Din; Salama, Amgad [Atomic Energy Authority, Cairo (Egypt). Reactors Dept.
2010-09-15
The hot channel in a typical Material Testing Reactor (MTR) is subjected to 3D simulation. Because of the existence of similarity planes, only a quarter of the hot channel including meat thickness, clad, and coolant channel is considered for CFD analysis using the FLUENT code. For the simulation, steady state normal operation regime at the reactor nominal power is assumed. In order to build confidence in our modeling approach, the results obtained in this work are compared with those obtained from the one-dimensional simulation code, MTRTHA. That is, modified variables were generated in order to match those obtained by MTRTHA and to allow comparisons. Quite good agreement is generally observed, however, the maximum clad surface temperature predicted by the 3D calculations, located at the clad mid-width, is higher than the 1D prediction by about 8 C but still below the onset of subcooled boiling by adequate safety margin. The results show quite interesting 3D patterns in both the flow field and the heat transfer. Temperature profiles, velocity profiles and contours are all presented to highlight the essential 3D features of this system. (orig.)
Design, simulation, fabrication, and preliminary tests of 3D CMS pixel detectors for the super-LHC
Energy Technology Data Exchange (ETDEWEB)
Koybasi, Ozhan; /Purdue U.; Bortoletto, Daniela; /Purdue U.; Hansen, Thor-Erik; /SINTEF, Oslo; Kok, Angela; /SINTEF, Oslo; Hansen, Trond Andreas; /SINTEF, Oslo; Lietaer, Nicolas; /SINTEF, Oslo; Jensen, Geir Uri; /SINTEF, Oslo; Summanwar, Anand; /SINTEF, Oslo; Bolla, Gino; /Purdue U.; Kwan, Simon Wing Lok; /Fermilab
2010-01-01
The Super-LHC upgrade puts strong demands on the radiation hardness of the innermost tracking detectors of the CMS, which cannot be fulfilled with any conventional planar detector design. The so-called 3D detector architectures, which feature columnar electrodes passing through the substrate thickness, are under investigation as a potential solution for the closest operation points to the beams, where the radiation fluence is estimated to reach 10{sup 16} n{sub eq}/cm{sup 2}. Two different 3D detector designs with CMS pixel readout electronics are being developed and evaluated for their advantages and drawbacks. The fabrication of full-3D active edge CMS pixel devices with p-type substrate has been successfully completed at SINTEF. In this paper, we study the expected post-irradiation behaviors of these devices with simulations and, after a brief description of their fabrication, we report the first leakage current measurement results as performed on wafer.
Analysis of hybrid viscous damper by real time hybrid simulations
DEFF Research Database (Denmark)
Brodersen, Mark Laier; Ou, Ge; Høgsberg, Jan Becker;
2016-01-01
Results from real time hybrid simulations are compared to full numerical simulations for a hybrid viscous damper, composed of a viscous dashpot in series with an active actuator and a load cell. By controlling the actuator displacement via filtered integral force feedback the damping performance...... of the hybrid viscous damper is improved, while for pure integral force feedback the damper stroke is instead increased. In the real time hybrid simulations viscous damping is emulated by a bang-bang controlled Magneto-Rheological (MR) damper. The controller activates high-frequency modes and generates drift...... in the actuator displacement, and only a fraction of the measured damper force can therefore be used as input to the investigated integral force feedback in the real time hybrid simulations....
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 ∼ γSUB>/bSUB>2 = (1 -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.
Probing the fuzzy sphere regularisation in simulations of the $3d \\lambda \\phi^4$ model
Medina, Julieta; O'Connor, Denjoe
2008-01-01
We regularise the 3d \\lambda \\phi^4 model by discretising the Euclidean time and representing the spatial part on a fuzzy sphere. The latter involves a truncated expansion of the field in spherical harmonics. This yields a numerically tractable formulation, which constitutes an unconventional alternative to the lattice. In contrast to the 2d version, the radius R plays an independent r\\^{o}le. We explore the phase diagram in terms of R and the cutoff, as well as the parameters m^2 and \\lambda. Thus we identify the phases of disorder, uniform order and non-uniform order. We compare the result to the phase diagrams of the 3d model on a non-commutative torus, and of the 2d model on a fuzzy sphere. Our data at strong coupling reproduce accurately the behaviour of a matrix chain, which corresponds to the c=1-model in string theory. This observation enables a conjecture about the thermodynamic limit.
Computational fluid dynamics simulations of blood flow regularized by 3D phase contrast MRI
DEFF Research Database (Denmark)
Rispoli, Vinicius C; Nielsen, Jon; Nayak, Krishna S;
2015-01-01
BACKGROUND: Phase contrast magnetic resonance imaging (PC-MRI) is used clinically for quantitative assessment of cardiovascular flow and function, as it is capable of providing directly-measured 3D velocity maps. Alternatively, vascular flow can be estimated from model-based computation fluid...... approach in regularizing 3D flow fields is evaluated. METHODS: The proposed algorithm incorporates both a Newtonian fluid physics model and a linear PC-MRI signal model. The model equations are solved numerically using a modified CFD algorithm. The numerical solution corresponds to the optimal solution of...... dynamics (CFD) calculations. CFD provides arbitrarily high resolution, but its accuracy hinges on model assumptions, while velocity fields measured with PC-MRI generally do not satisfy the equations of fluid dynamics, provide limited resolution, and suffer from partial volume effects. The purpose of this...
Justification for a 2D versus 3D fingertip finite element model during static contact simulations.
Harih, Gregor; Tada, Mitsunori; Dolšak, Bojan
2016-10-01
The biomechanical response of a human hand during contact with various products has not been investigated in details yet. It has been shown that excessive contact pressure on the soft tissue can result in discomfort, pain and also cumulative traumatic disorders. This manuscript explores the benefits and limitations of a simplified two-dimensional vs. an anatomically correct three-dimensional finite element model of a human fingertip. Most authors still use 2D FE fingertip models due to their simplicity and reduced computational costs. However we show that an anatomically correct 3D FE fingertip model can provide additional insight into the biomechanical behaviour. The use of 2D fingertip FE models is justified when observing peak contact pressure values as well as displacement during the contact for the given studied cross-section. On the other hand, an anatomically correct 3D FE fingertip model provides a contact pressure distribution, which reflects the fingertip's anatomy. PMID:26856769
Numerical simulation of the filling stage in injection molding based on a 3D model
Institute of Scientific and Technical Information of China (English)
GENG Tie; LI De-qun; ZHOU Hua-min
2005-01-01
Most injection molded parts are three-dimensional, with complex geometrical configurations and thick/thin wall sections. The change of the thickness of parts has significant influence on flow during injection molding. This paper presents a 3D finite element model to deal with the three-dimensional flow, which can more accurately predict the filling process than a 2. 5D model. In this model, equal-order velocity-pressure interpolation method is successfully employed and the relation between velocity and pressure is obtained from the discretized momentum equation in order to derive the pressure equation. A 3D control volume scheme is employed to track the flow front. The validity of the model has been tested through the analysis of the flow in a cavity.
Guo, Hanqi; Phillips, Carolyn L; Peterka, Tom; Karpeyev, Dmitry; Glatz, Andreas
2016-01-01
We propose a method for the vortex extraction and tracking of superconducting magnetic flux vortices for both structured and unstructured mesh data. In the Ginzburg-Landau theory, magnetic flux vortices are well-defined features in a complex-valued order parameter field, and their dynamics determine electromagnetic properties in type-II superconductors. Our method represents each vortex line (a 1D curve embedded in 3D space) as a connected graph extracted from the discretized field in both space and time. For a time-varying discrete dataset, our vortex extraction and tracking method is as accurate as the data discretization. We then apply 3D visualization and 2D event diagrams to the extraction and tracking results to help scientists understand vortex dynamics and macroscale superconductor behavior in greater detail than previously possible.
Guo, Hanqi; Phillips, Carolyn L; Peterka, Tom; Karpeyev, Dmitry; Glatz, Andreas
2016-01-01
We propose a method for the vortex extraction and tracking of superconducting magnetic flux vortices for both structured and unstructured mesh data. In the Ginzburg-Landau theory, magnetic flux vortices are well-defined features in a complex-valued order parameter field, and their dynamics determine electromagnetic properties in type-II superconductors. Our method represents each vortex line (a 1D curve embedded in 3D space) as a connected graph extracted from the discretized field in both space and time. For a time-varying discrete dataset, our vortex extraction and tracking method is as accurate as the data discretization. We then apply 3D visualization and 2D event diagrams to the extraction and tracking results to help scientists understand vortex dynamics and macroscale superconductor behavior in greater detail than previously possible. PMID:26529730
Simulation of 3D Needle-Tissue Interaction with Application to Image Guided Prostate Brachytherapy
Institute of Scientific and Technical Information of China (English)
姜杉; HATA; Nobuhiko; 肖渤瀚; 安蔚瑾
2010-01-01
To improve global control of disease and reduce global toxicity, a complex seed distribution pattern should be achieved with great accuracy during brachytherapy.However, the interaction between the needle and prostate will cause large deformation of soft tissue.As a result, seeds will be misplaced, sharp demarcation between irradiated volume and healthy structures is unavailable and this will cause side effects such as impotence and urinary incontinence.In this paper, a 3D nonlinear dynamic finite element s...
Trapping Solids at the Inner Edge of the Dead Zone: 3-D Global MHD Simulations
Dzyurkevich, Natalia; Flock, Mario; Turner, Neal J.; Klahr, Hubert; Henning, Thomas
2010-01-01
The poorly-ionized interior of the protoplanetary disk 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. Our aim 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 MHD calculations of the disk treat...
Simulation 3D electromagnetique et thermomecanique d'une cavite RF
Launay, F
2003-01-01
Une etude thermomecanique 3D de l'extremite de lame a l'entree du RFQ d'IPHI a ete menee avec le code I-DEAS. Le but est de comparer les temperatures atteintes, les contraintes et les deformations calculees a partir des densites de puissance RF deposee sur la lame obtenues a partir de deux codes de calcul electromagnetique differents: SOPRANO et MAFIA
Simulation study of a 3-D device integrating FinFET and UTBFET
Fahad, Hossain M.
2015-01-01
By integrating 3-D nonplanar fins and 2-D ultrathin bodies, wavy FinFETs merge two formerly competing technologies on a silicon-on-insulator platform to deliver enhanced transistor performance compared with conventional trigate FinFETs with unprecedented levels of chip-area efficiency. This makes it suitable for ultralarge-scale integration high-performance logic at and beyond the 10-nm technology node.
Directory of Open Access Journals (Sweden)
Sri Atmaja P. Rosidi
2007-01-01
Full Text Available The Spectral Analysis of Surface Wave (SASW method is a non-destructive in situ seismic technique used to assess and evaluate the material stiffness (dynamic elastic modulus and thickness of pavement layers at low strains. These values can be used analytically to calculate load capacities in order to predict the performance of pavement system. The SASW method is based on the dispersion phenomena of Rayleigh waves in layered media. In order to get the actual shear wave velocities, 2-D and 3-D models are used in the simulation of the inversion process for best fitting between theoretical and empirical dispersion curves. The objective of this study is to simulate and compare the 2-D and 3-D model of SASW analysis in the construction of the theoretical dispersion curve for pavement structure evaluation. The result showed that the dispersion curve from the 3-D model was similar with the dispersion curve of the actual pavement profile compared to the 2-D model. The wave velocity profiles also showed that the 3-D model used in the SASW analysis is able to detect all the distinct layers of flexible pavement units.
Zhang, Jingjie; Zhou, Yizhuo; Zheng, Guangping; Huang, Qiuying; Zheng, Xiucheng; Liu, Pu; Zhang, Jianmin; Guan, Xinxin
2016-10-01
TiO2-graphene aerogel (TiO2-GA) 3D hybrids were directly assembled via a one-pot hydrothermal process followed by freeze-drying without using any structure-directing agent. The hybrids with a hierarchical structure exhibited large surface area (SBET = 283.6 m2 g-1) and high pore volume (Vp = 0.278 cm3 g-1), in which the ultradispersed TiO2 nanoparticles were in a single crystal phase of anatase. When used as the anodes for lithium ion battery, the TiO2-GA hybrids exhibited higher reversible capacity, more stable cycling performance and better rate-capability than TiO2 ascribed to the unique 3D nanoporous structure and the synergistic interaction of GA and TiO2.
Luo, Cong; Friederich, Wolfgang
2016-04-01
Realistic shallow seismic wave propagation simulation is an important tool for studying induced seismicity (e.g., during geothermal energy development). However over a long time, there is a significant problem which constrains computational seismologists from performing a successful simulation conveniently: pre-processing. Conventional pre-processing has often turned out to be inefficient and unrobust because of the miscellaneous operations, considerable complexity and insufficiency of available tools. An integrated web-based platform for shallow seismic wave propagation simulation has been built. It is aiming at providing a user-friendly pre-processing solution, and cloud-based simulation abilities. The main features of the platform for the user include: revised digital elevation model (DEM) retrieving and processing mechanism; generation of multi-layered 3D shallow Earth model geometry (the computational domain) with user specified surface topography based on the DEM; visualization of the geometry before the simulation; a pipeline from geometry to fully customizable hexahedral element mesh generation; customization and running the simulation on our HPC; post-processing and retrieval of the results over cloud. Regarding the computational aspect, currently the widely accepted specfem3D is chosen as the computational package; packages using different types of elements can be integrated as well in the future. According to our trial simulation experiments, this web-based platform has produced accurate waveforms while significantly simplifying and enhancing the pre-processing and improving the simulation success rate.
Institute of Scientific and Technical Information of China (English)
GAO Nuo; ZHU Shan-an; HE Bin
2005-01-01
We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach.Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%,for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.
Hazenberg, P.; Broxton, P. D.; Brunke, M.; Gochis, D. J.; Lawrence, D. M.; Niu, G. Y.; Pelletier, J. D.; Troch, P. A. A.; Zeng, X.
2014-12-01
Traditionally, LSMs for use in Earth system models (ESMs) only account for one-dimensional (1-D) vertical hydrological processes at very coarse resolutions (~100 km). Recently, there has been interest in simulating lateral exchange of surface and subsurface water, as the grid resolution of ESMs increases (currently towards ~20 km) due to advances in computational power.In the current work, we present a new physically-based hydrological model capable of simulating lateral flow at a hyperresolution (1 km pixels) coupled with the vertical soil column of the Community Land Model (CLM), which has a much coarser resolution. Our new approach also uses sub-pixel topographic information to represent small scale lateral-flow processes. As input to our model, we use 1 km data of required surface and subsurface information, such depth to bedrock, hillslope width functions, fractional coverage of hillslopes/wetlands/riparian zones within each 1 km pixel, and a river network. Such data are largely derived from higher-resolution (30 m) topographic data, and will be made available to the community as global products.We have tested our model against measurements over a well instrumented, artificial hillslope at the University of Arizona's Biosphere 2 and found that both our approach and a full 3-D physically-based hydrological model can realistically simulate hydrological states and fluxes. However, computationally, our approach is 2 - 3 orders of magnitude faster than the latter. We are currently testing it for an ESM grid box that covers much of southeastern New York State, which includes the headwaters of the Delaware River, the Susquehana River, and parts of the Mohawk River Basin. Our approach improves upon the 1-D hydrological representation in CLM by representing the subgrid topographic and geomorphological variability in the grid box. The impact of representing such subgrid variability on surface water and energy fluxes will be discussed in our presentation.
HyFinBall: a two-handed, hybrid 2D/3D desktop VR interface for multi-dimensional visualization
Cho, Isaac; Wang, Xiaoyu; Wartell, Zachary J.
2013-12-01
This paper presents the concept, working prototype and design space of a two-handed, hybrid spatial user interface for minimally immersive desktop VR targeted at multi-dimensional visualizations. The user interface supports dual button balls (6DOF isotonic controllers with multiple buttons) which automatically switch between 6DOF mode (xyz + yaw,pitch,roll) and planar-3DOF mode (xy + yaw) upon contacting the desktop. The mode switch automatically switches a button ball's visual representation between a 3D cursor and a mouse-like 2D cursor while also switching the available user interaction techniques (ITs) between 3D and 2D ITs. Further, the small form factor of the button ball allows the user to engage in 2D multi-touch or 3D gestures without releasing and re-acquiring the device. We call the device and hybrid interface the HyFinBall interface which is an abbreviation for `Hybrid Finger Ball.' We describe the user interface (hardware and software), the design space, as well as preliminary results of a formal user study. This is done in the context of a rich, visual analytics interface containing coordinated views with 2D and 3D visualizations and interactions
Lipatov, A. S.; Sibeck, D. G.
2016-09-01
We use a new hybrid kinetic model to simulate the response of ring current, outer radiation belt, and plasmaspheric particle populations to impulsive interplanetary shocks. Since particle distributions attending the interplanetary shock waves and in the ring current and radiation belts are non-Maxwellian, wave-particle interactions play a crucial role in energy transport within the inner magnetosphere. Finite gyroradius effects become important in mass loading the shock waves with the background plasma in the presence of higher energy ring current and radiation belt ions and electrons. Initial results show that shocks cause strong deformations in the global structure of the ring current, radiation belt, and plasmasphere. The ion velocity distribution functions at the shock front, in the ring current, and in the radiation belt help us determine energy transport through the Earth's inner magnetosphere.
Benchmarks of 3D Laplace Equation Solvers in a Cubic Configuration for Streamer Simulation
Joseph-Marie, Plewa; Olivier, Ducasse; Philippe, Dessante; Carolyn, Jacobs; Olivier, Eichwald; Nicolas, Renon; Mohammed, Yousfi
2016-05-01
The aim of this paper is to test a developed SOR R&B method using the Chebyshev accelerator algorithm to solve the Laplace equation in a cubic 3D configuration. Comparisons are made in terms of precision and computing time with other elliptic equation solvers proposed in the open source LIS library. The first results, obtained by using a single core on a HPC, show that the developed SOR R&B method is efficient when the spectral radius needed for the Chebyshev acceleration is carefully pre-estimated. Preliminary results obtained with a parallelized code using the MPI library are also discussed when the calculation is distributed over one hundred cores.
Computer Simulation of Flow in CSO “OK3D Evropská”
Pollert, J
2000-01-01
During the last 30 years, a number of devices has been developed for dynamic separation of settle able solids in wastewaters. Initially, these separators were used for control of Combined Sewer Overflow (CSO) pollution by retaining the bulk of solids in the underflow, directed to the sewage treatment plant (STP), and allowing combined sewage with reduced pollutant loads to overflow from the sewer systém. This paper is describing CSO “OK 3D Evropská” in Prague 6 on Evropská Street. Inlet...
3D AMR simulations of the evolution of the diffuse gas cloud G2 in the Galactic Centre
Schartmann, M; Burkert, A; Gillessen, S; Genzel, R; Pfuhl, O; Eisenhauer, F; Plewa, P M; Ott, T; George, E M; Habibi, M
2016-01-01
With the help of 3D AMR hydrodynamical simulations we aim at understanding G2's nature, recent evolution and fate in the coming years. By exploring the possible parameter space of the diffuse cloud scenario, we find that a starting point within the disc of young stars is favoured by the observations, which may hint at G2 being the result of stellar wind interactions.
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.
Tsukahara, Hiroshi; Iwano, Kaoru; Mitsumata, Chiharu; Ishikawa, Tadashi; Ono, Kanta
2016-10-01
We implement low communication frequency three-dimensional fast Fourier transform algorithms on micromagnetics simulator for calculations of a magnetostatic field which occupies a significant portion of large-scale micromagnetics simulation. This fast Fourier transform algorithm reduces the frequency of all-to-all communications from six to two times. Simulation times with our simulator show high scalability in parallelization, even if we perform the micromagnetics simulation using 32 768 physical computing cores. This low communication frequency fast Fourier transform algorithm enables world largest class micromagnetics simulations to be carried out with over one billion calculation cells.
Institute of Scientific and Technical Information of China (English)
雷雨
2014-01-01
本文简要介绍了3DS MAX SCRIPT面向对象脚本语言的主要功能，如脚本语言的编辑器和监听器，UI界面，数据的I/O接口，及数学函数。并且描述了SCRIPT语言在三维模拟井眼轨迹方面的应用实例，实例主要以解决实际问题为导向，并结合3DMAX软件的脚本语言，根据杏6-2-丙503井和芳104-92井测量得到的深度、斜度、方位，以这三项作为数据输入，通过数学函数转换为计算机可识别的节点，并且用连线函数将节点坐标连接起来，经过渲染绘制成三维立体图像，同时生成动画，利于从各个角度观测。程序设计以结构化编程为主，可以根据客户需要添加各个模块的功能，同时能够满足大批量井绘制图像的要求。本文作者通过对实例的目标分析，流程设计，解释源代码，描述程序的运行情况，对这个方向的开发应用进行了初步的探讨。希望抛砖引玉，能够让更多人了解到3DS MAX强大的图像生成能力和编程功能，为油田3DMAX应用和二次开发贡献更多的力量。%This paper briefly introduces the main function of the 3DS MAX SCRIPT object-oriented scripting languages, such as script editor and listener, UI interface, data I/O interface, and the mathematical function. And describes the application of SCRIPT language in the 3D simulation of hole trajectory, examples mainly aiming to solve practical problems, and combined with the 3DMAX scripting language, according to the XING 6-2-C 503 wells and FANG104-92 well measured depth, inclination, orientation, use the three as the data input, converted to node the computer can be identified by a mathematical function, and connecting the nodes coordinate with line function, make three-dimensional image after drawing and rendering, animation, benefit from each angle observation. Program design of structured programming, can according to the customer need to add the function of each module
Clementel, Nicola; Kruip, Chael J H; Paardekooper, Jan-Pieter
2015-01-01
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-year orbit. Approaching periastron, the 3D structure of the wind-wind interaction region (WWIR) gets highly distorted due to the eccentric ($e \\sim 0.9$) binary orbit. The secondary star ($\\eta_{\\mathrm{B}}$) 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 $\\eta$ 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 $\\eta$ Car system for two different primary star mass-loss rates ($\\dot{M}_{\\eta_{\\mathrm{A}}}$). Using previous results from simulations at ap...
Simulation of the 3D viscoelastic free surface flow by a parallel corrected particle scheme
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).
Developing a GIS-Based Visual-Acoustic 3D Simulation for Wind Farm Assessment
Directory of Open Access Journals (Sweden)
Madeleine Manyoky
2014-01-01
Full Text Available Public landscape impact assessment of renewable energy installations is crucial for their acceptance. Thus, a sound assessment basis is crucial in the implementation process. For valuing landscape perception, the visual sense is the dominant human sensory component. However, the visual sense provides only partial information about our environment. Especially when it comes to wind farm assessments, noise produced by the rotating turbine blades is another major impact factor. Therefore, an integrated visual and acoustic assessment of wind farm projects is needed to allow lay people to perceive their impact adequately. This paper presents an approach of linking spatially referenced auralizations to a GIS-based virtual 3D landscape model. We demonstrate how to utilize a game engine for 3D visualization of wind parks, using geodata as a modeling basis. In particular, the controlling and recording of specific parameters in the game engine is shown in order to establish a link to the acoustical model. The resulting prototype has high potential to complement conventional tools for an improved public impact assessment of wind farms.
Computer Simulation of Flow in CSO “OK3D Evropská”
Directory of Open Access Journals (Sweden)
J. Pollert
2000-01-01
Full Text Available During the last 30 years, a number of devices has been developed for dynamic separation of settle able solids in wastewaters. Initially, these separators were used for control of Combined Sewer Overflow (CSO pollution by retaining the bulk of solids in the underflow, directed to the sewage treatment plant (STP, and allowing combined sewage with reduced pollutant loads to overflow from the sewer systém. This paper is describing CSO “OK 3D Evropská” in Prague 6 on Evropská Street. Inlet to CSO is 3 m diameter tube collecting water from location of Oepy, Vokovice, Liboc and Ruzyně. The outflow throttle pipe is 1.1 m in diameter and continues to central wastewater treatment plant and overflow is ending in Šárecký creek. Šárecký creek flows through the Šárka valley which is environmentally protected area. CSO “OK 3D Evropská" has high overflow crest and probability of the function is 0.44 per year.
Simulating 3D $Z_2$ Topological Nodes in Nonsymmorphic Photonic Crystals
Wang, Hai-Xiao; Hang, Zhi Hong; Chen, Huanyang; Kee, Hae-Young; Jiang, Jian-Hua
2016-01-01
We propose an all-dielectric, space-time reversal symmetric photonics-crystal architecture that possess 3D Dirac points and line-nodes with nontrivial $Z_2$ topological charge, which can be realized at infrared and microwave frequencies. The protected degeneracy of bands is achieved via nonsymmorphic symmetries despite the lack of Kramers degeneracy in photonic crystal systems. Two orthogonal screw axes lead to 3D $Z_2$ Dirac points on high symmetry Brillouin zone (BZ) boundary line. On the other hand, twofold $Z_2$ line-nodes appear around the $\\Gamma$-point due to a combination of nonsymmorphic and point-group symmetries. The lowest line-node is deterministic because of degeneracy partner switching between Bloch states with opposite parities. A pair of Fermi arcs associated with $Z_2$ topological charge is emerged below light-line and protected by total internal reflection on certain photonic-crystal-air interfaces. These robust surface states offer an unique opportunity to realize "open cavity" with strong...
A 3D simulation case study of airport air traffic handling
H. de Swaan Arons
1996-01-01
textabstractModern Windows-based simulation packages bring simulation within reach of decision-makers. The use of graphics enables the manager to observe an animation of the simulated reality, to focus on the essentials of the model without the need to bother about implementation details. In most ap
Liou, K. N.; Gu, Y.; Leung, L. R.; Lee, W. L.; Fovell, R. G.
2013-07-01
Essentially all modern climate models utilize a plane-parallel (PP) radiative transfer approach in physics parameterizations; however, the potential errors that arise from neglecting three-dimensional (3-D) interactions between radiation and mountains/snow on climate simulations have not been studied and quantified. This paper is a continuation of our efforts to investigate 3-D mountains/snow effects on solar flux distributions and their impact on surface hydrology over the Western United States, specifically the Rocky and Sierra-Nevada Mountains. We use the Weather Research and Forecasting (WRF) model applied at a 30 km grid resolution with incorporation of a 3-D radiative transfer parameterization covering a time period from 1 November 2007 to 31 May 2008 during which abundant snowfall occurred. Comparison of the 3-D WRF simulation with the observed snow water equivalent (SWE) and precipitation from Snowpack Telemetry (SNOTEL) sites shows reasonable agreement in terms of spatial patterns and daily and seasonal variability, although the simulation generally has a positive precipitation bias. We show that 3-D mountain features have a profound impact on the diurnal and monthly variation of surface radiative and heat fluxes and on the consequent elevation-dependence of snowmelt and precipitation distributions. In particular, during the winter months, large deviations (3-D-PP) of the monthly mean surface solar flux are found in the morning and afternoon hours due to shading effects for elevations below 2.5 km. During spring, positive deviations shift to earlier morning. Over the mountain tops above 3 km, positive deviations are found throughout the day, with the largest values of 40-60 W m-2 occurring at noon during the snowmelt season of April to May. The monthly SWE deviations averaged over the entire domain show an increase in lower elevations due to reduced snowmelt, leading to a reduction in cumulative runoff. Over higher elevation areas, positive SWE deviations
Energy Technology Data Exchange (ETDEWEB)
Jain, Prashant K [ORNL; Freels, James D [ORNL; Cook, David Howard [ORNL
2012-08-01
Three dimensional simulation capabilities are currently being developed at Oak Ridge National Laboratory using COMSOL Multiphysics, a finite element modeling software, to investigate thermal expansion of High Flux Isotope Reactor (HFIR) s low enriched uranium fuel plates. To validate simulations, 3D models have also been developed for the experimental setup used by Cheverton and Kelley in 1968 to investigate the buckling and thermal deflections of HFIR s highly enriched uranium fuel plates. Results for several simulations are presented in this report, and comparisons with the experimental data are provided when data are available. A close agreement between the simulation results and experimental findings demonstrates that the COMSOL simulations are able to capture the thermal expansion physics accurately and that COMSOL could be deployed as a predictive tool for more advanced computations at realistic HFIR conditions to study temperature-induced fuel plate deflection behavior.
International Nuclear Information System (INIS)
The percolation threshold problem in insulating polymers filled with exfoliated conductive graphite nanoplatelets (GNPs) is re-examined in this 3D Monte Carlo simulation study. GNPs are modelled as solid discs wrapped by electrically conductive layers of certain thickness which represent half of the electron tunnelling distance. Two scenarios of 'impenetrable' and 'penetrable' GNPs are implemented in the simulations. The percolation thresholds for both scenarios are plotted versus the electron tunnelling distance for various GNP thicknesses. The assumption of successful dispersion and exfoliation, and the incorporation of the electron tunnelling phenomenon in the impenetrable simulations suggest that the simulated percolation thresholds are lower bounds for any experimental study. Finally, the simulation results are discussed and compared with other experimental studies.
3D element imaging using NSECT for the detection of renal cancer: a simulation study in MCNP
Viana, R. S.; Agasthya, G. A.; Yoriyaz, H.; Kapadia, A. J.
2013-09-01
This work describes a simulation study investigating the application of neutron stimulated emission computed tomography (NSECT) for noninvasive 3D imaging of renal cancer in vivo. Using MCNP5 simulations, we describe a method of diagnosing renal cancer in the body by mapping the 3D distribution of elements present in tumors using the NSECT technique. A human phantom containing the kidneys and other major organs was modeled in MCNP5. The element composition of each organ was based on values reported in literature. The two kidneys were modeled to contain elements reported in renal cell carcinoma (RCC) and healthy kidney tissue. Simulated NSECT scans were executed to determine the 3D element distribution of the phantom body. Elements specific to RCC and healthy kidney tissue were then analyzed to identify the locations of the diseased and healthy kidneys and generate tomographic images of the tumor. The extent of the RCC lesion inside the kidney was determined using 3D volume rendering. A similar procedure was used to generate images of each individual organ in the body. Six isotopes were studied in this work—32S, 12C, 23Na, 14N, 31P and 39K. The results demonstrated that through a single NSECT scan performed in vivo, it is possible to identify the location of the kidneys and other organs within the body, determine the extent of the tumor within the organ, and to quantify the differences between cancer and healthy tissue-related isotopes with p ≤ 0.05. All of the images demonstrated appropriate concentration changes between the organs, with some discrepancy observed in 31P, 39K and 23Na. The discrepancies were likely due to the low concentration of the elements in the tissue that were below the current detection sensitivity of the NSECT technique.
Hybrid2 - The hybrid power system simulation model
Energy Technology Data Exchange (ETDEWEB)
Baring-Gould, E.I.; Green, H.J.; Dijk, V.A.P. van [National Renewable Energy Lab., Golden, CO (United States); Manwell, J.F. [Univ. of Massachusetts, Amherst, MA (United States)
1996-12-31
There is a large-scale need and desire for energy in remote communities, especially in the developing world; however the lack of a user friendly, flexible performance prediction model for hybrid power systems incorporating renewables hindered the analysis of hybrids as options to conventional solutions. A user friendly model was needed with the versatility to simulate the many system locations, widely varying hardware configurations, and differing control options for potential hybrid power systems. To meet these ends, researchers from the National Renewable Energy Laboratory (NREL) and the University of Massachusetts (UMass) developed the Hybrid2 software. This paper provides an overview of the capabilities, features, and functionality of the Hybrid2 code, discusses its validation and future plans. Model availability and technical support provided to Hybrid2 users are also discussed. 12 refs., 3 figs., 4 tabs.
Finite element method for accurate 3D simulation of plasmonic waveguides
Burger, S; Pomplun, J; Schmidt, F; 10.1117/12.841995
2010-01-01
Optical properties of hybrid plasmonic waveguides and of low-Q cavities, formed by waveguides of finite length are investigated numerically. These structures are of interest as building-blocks of plasmon lasers. We use a time-harmonic finite-element package including a propagation-mode solver, a resonance-mode solver and a scattering solver for studying various properties of the system. Numerical convergence of all used methods is demonstrated.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Basing on the analysis of the traits of the roll forging process, a system-model of computer simulation has been established. Three-dimensional rigid-plastic FEM has been used for the simulation of the deformation process in the oval and round pass rolling, including the entering, rolling, and separating stages. The analysis was conducted using the Deform-3D ver. 5.0 code.The important information concerned with the deformation area characteristic, material fiow, and velocity field has been presented. Otherwise, the location of the neutral plane in the deformation area was shown clearly.
Simulation Study of Real Time 3-D Synthetic Aperture Sequential Beamforming for Ultrasound Imaging
DEFF Research Database (Denmark)
Hemmsen, Martin Christian; Rasmussen, Morten Fischer; Stuart, Matthias Bo;
2014-01-01
This paper presents a new beamforming method for real-time three-dimensional (3-D) ultrasound imaging using a 2-D matrix transducer. To obtain images with sufficient resolution and contrast, several thousand elements are needed. The proposed method reduces the required channel count from the...... transducer to the main imaging system, by including electronics in the transducer handle. The reduction of element channel count is achieved using a sequential beamforming scheme. The beamforming scheme is a combination of a fixed focus beamformer in the transducer and a second dynamic focus beamformer in...... the main system. The real-time imaging capability is achieved using a synthetic aperture beamforming technique, utilizing the transmit events to generate a set of virtual elements that in combination can generate an image. The two core capabilities in combination is named Synthetic Aperture Sequential...
Numerical simulation in 3D of atomizing coaxial gas-liquid jets
Agbaglah, Gilou; Fuster, Daniel; McBain, Geordie; Popinet, Stephane; Zaleski, Stephane
2012-11-01
We investigate three-dimensional multiphase flows using the Volume of Fluid method. We are in particular focusing on the problem of jet atomizaton. We use a Volume of Fluid method with oct-tree adaptive finite volume discretization, mostly using the Gerris free code. Surface tension is computed by a balanced-force method. Coaxial, 3D, round and planar air-water jets similar to those investigated experimentally are studied and compared to the equivalent jets in 2D axisymetric and 2D planar setups. A mechanism for large-scale jet disruption is observed. The distribution of droplet sizes is compared to experimental measurements. The effect of grid resolution and of the presence of an explicitly modelled solid separator plate is discussed.
Experimental validation of 3D simulations of tungsten melt erosion under ITER-like transient loads
International Nuclear Information System (INIS)
Tungsten in form of a macrobrush structure is foreseen as one of two candidate materials for the ITER divertor. The main mechanisms of metallic target damage are surface melting and melt motion erosion, which determines the lifetime of plasma facing components (PFC). The damage to W-macrobrush targets under repetitive ELM-like heat loads corresponding to the conditions of the plasma gun QSPA-T and ITER is numerically investigated with the three-dimensional melt motion code MEMOS. The calculations revealed a significant damage to brush edges caused by the interaction of impacting plasma with the lateral surfaces. In addition, experimentally observed overlapping of brush gaps by molten tungsten was numerically confirmed. These 3D effects of the repetitive transient loads may significantly influence the PFC lifetime.
Human Body Modeling and Posture Simulating Based on 3D Surface Scan Data
Institute of Scientific and Technical Information of China (English)
马永有; 张辉; 任少云; 蒋寿伟
2003-01-01
This paper presents a new approach for modeling the human body by considering the motion state and the shape of whole body. The body model consists of a skeleton kinematic model and a surface model. The former is used to determine the posture of the body,and the latter is used to generate the body shape according to the given posture. The body surface is reconstructed with multi-segment B-spline surfaces based on the 3D scan data from a real human body.Using only a few joints parameters and the original surface scan data, the various body postures and the shape can be generated easily. The model has a strong potential of being used for ergonomic design,garment design, virtual reality environment, as well as creating human animation, etc.
A SPECT system simulator built on the SolidWorksTM 3D-Design package
LI, XIN; Furenlid, Lars R.
2014-01-01
We have developed a GPU-accelerated SPECT system simulator that integrates into instrument-design workflow [1]. This simulator includes a gamma-ray tracing module that can rapidly propagate gamma-ray photons through arbitrary apertures modeled by SolidWorksTM-created stereolithography (.STL) representations with a full complement of physics cross sections [2, 3]. This software also contains a scintillation detector simulation module that can model a scintillation detector with arbitrary scint...
International Nuclear Information System (INIS)
The Nuclear Steam Supply System (NSSS) thermal-hydraulic model adopted in the Korea Nuclear Plant Education Center (KNPEC)-2 simulator was provided in the early 1980s. The reference plant for KNPEC-2 is the Yong Gwang Nuclear Unit 1, which is a Westinghouse-type 3-loop, 950 MW(electric) pressurized water reactor. Because of the limited computational capability at that time, it uses overly simplified physical models and assumptions for a real-time simulation of NSSS thermal-hydraulic transients. This may entail inaccurate results and thus, the possibility of so-called ''negative training,'' especially for complicated two-phase flows in the reactor coolant system. To resolve the problem, we developed a realistic NSSS thermal-hydraulic program (named ARTS code) based on the best-estimate code RETRAN-3D. The systematic assessment of ARTS has been conducted by both a stand-alone test and an integrated test in the simulator environment. The non-integrated stand-alone test (NIST) results were reasonable in terms of accuracy, real-time simulation capability, and robustness. After successful completion of the NIST, ARTS was integrated with a 3-D reactor kinetics model and other system models. The site acceptance test (SAT) has been completed successively and confirmed to comply with the ANSI/ANS-3.5-1998 simulator software performance criteria. This paper presents our efforts for the ARTS development and some test results of the NIST and SAT
A hybrid parallel framework for the cellular Potts model simulations
Energy Technology Data Exchange (ETDEWEB)
Jiang, Yi [Los Alamos National Laboratory; He, Kejing [SOUTH CHINA UNIV; Dong, Shoubin [SOUTH CHINA UNIV
2009-01-01
The Cellular Potts Model (CPM) has been widely used for biological simulations. However, most current implementations are either sequential or approximated, which can't be used for large scale complex 3D simulation. In this paper we present a hybrid parallel framework for CPM simulations. The time-consuming POE solving, cell division, and cell reaction operation are distributed to clusters using the Message Passing Interface (MPI). The Monte Carlo lattice update is parallelized on shared-memory SMP system using OpenMP. Because the Monte Carlo lattice update is much faster than the POE solving and SMP systems are more and more common, this hybrid approach achieves good performance and high accuracy at the same time. Based on the parallel Cellular Potts Model, we studied the avascular tumor growth using a multiscale model. The application and performance analysis show that the hybrid parallel framework is quite efficient. The hybrid parallel CPM can be used for the large scale simulation ({approx}10{sup 8} sites) of complex collective behavior of numerous cells ({approx}10{sup 6}).